Science.gov

Sample records for 3h-2b release rate

  1. Strategic 3-hydroxy-2-butanone release in the dominant male lobster cockroach, Nauphoeta cinerea

    NASA Astrophysics Data System (ADS)

    Chen, Shu-Chun; Yang, Rou-Ling; Ho, Hsiao-Yung; Chou, Szu-Ying; Kou, Rong

    2007-11-01

    In the lobster cockroach Nauphoete cinerea, the dominant subordinate hierarchy formed via the agonistic interactions is unstable, and changes in rank order are common. Our previous results showed that in the first encounter fight during initial rank formation, microgram levels of 3H-2B are released by the aggressive posture (AP)-adopting dominant male. In the present study, the pattern of daily pheromone (3H-2B) release during the domination period and on the day of rank switch, rank duration, and rank switch frequency were investigated in three-male groups and six-male groups to examine the effect of higher frequency of agonistic encounters. The results showed that, in the three-male groups (50-day observation period), daily 3H-2B release rate was not constant, but fluctuated, the average duration of dominant rank was 16.6 ± 2.0 days, rank switch occurred in 58.8% of groups, and the frequency of rank switching (average number of rank switches/group/50 days) was 1.4 ± 0.2. For the six-male groups (30-day observation period), the daily 3H-2B release rate also fluctuated, but the duration of dominant rank was significantly shorter at 4.2 ± 0.6 days, rank switch occurred in 100% of groups, and the frequency of rank switching (average number of rank switches/group/30 days) was significantly higher at 6.9 ± 0.6. The results for both sets of male groups showed that as a new rank formed (either on the first encounter day or on the day of rank switching), the dominant status was significantly associated with a higher 3H-2B release rate. In the animal kingdom, fighting usually involves communication or the exchange of signals, and the results of this study indicated that the fluctuating daily 3H-2B release rate adopted by the dominants is a kind of strategic release and the 3H-2B release rate is a signal used to determine dominance.

  2. Kinesin ATPase: Rate-Limiting ADP Release

    NASA Astrophysics Data System (ADS)

    Hackney, David D.

    1988-09-01

    The ATPase rate of kinesin isolated from bovine brain by the method of S. A. Kuznetsov and V. I. Gelfand [(1986) Proc. Natl. Acad. Sci. USA 83, 8530-8534)] is stimulated 1000-fold by interaction with tubulin (turnover rate per 120-kDa peptide increases from ≈ 0.009 sec-1 to 9 sec-1). The tubulin-stimulated reaction exhibits no extra incorporation of water-derived oxygens over a wide range of ATP and tubulin concentrations, indicating that Pi release is faster than the reversal of hydrolysis. ADP release, however, is slow for the basal reaction and its release is rate limiting as indicated by the very tight ADP binding (Ki < 5 nM), the retention of a stoichiometric level of bound ADP through ion-exchange chromatography and dialysis, and the reversible labeling of a bound ADP by [14C]ATP at the steady-state ATPase rate as shown by centrifuge gel filtration and inaccessibility to pyruvate kinase. Tubulin accelerates the release of the bound ADP consistent with its activation of the net ATPase reaction. The detailed kinetics of ADP release in the presence of tubulin are biphasic indicating apparent heterogeneity with a fraction of the kinesin active sites being unaffected by tubulin.

  3. Strain-Energy-Release Rates In Delamination

    NASA Technical Reports Server (NTRS)

    Raju, I. S.

    1988-01-01

    Q3DG computer program developed to perform quasi-three-dimensional stress analysis of composite laminates containing delaminations. Calculates strain-energy-release rates for long, rectangular composite laminates containing delaminations and subjected to any combination of mechanical, thermal, and hygroscopic loading. Written in FORTRAN V.

  4. Gas cylinder release rate testing and analysis

    NASA Astrophysics Data System (ADS)

    Despres, Joseph; Sweeney, Joseph; Yedave, Sharad; Chambers, Barry

    2012-11-01

    There are varying cylinder technologies employed for the storage of gases, each resulting in a potentially different hazard level to the surroundings in the event of a gas release. Subatmospheric Gas delivery Systems Type I (SAGS I) store and deliver gases subatmospherically, while Subatmospheric Gas delivery Systems Type II (SAGS II) deliver gases subatmospherically, but store them at high pressure. Standard high pressure gas cylinders store and deliver their contents at high pressure. Due to the differences in these cylinder technologies, release rates in the event of a leak or internal component failure, can vary significantly. This paper details the experimental and theoretical results of different Arsine (AsH3) gas cylinder release scenarios. For the SAGS II experimental analysis, Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the spatial concentration profiles when a surrogate gas, CF4, was released via a simulated leak within an ion implanter. Various SAGS I and SAGS II cylinder types and failure modes were tested. Additionally, theoretical analysis was performed to support an understanding of the different potential AsH3 leak rates. The results of this work show that the effects of a leak from the various cylinder types can be quite different, with the concentrations resulting from cylinders containing high pressure gas often being in excess of IDLH levels.

  5. Patient release criteria for low dose rate brachytherapy implants.

    PubMed

    Boyce, Dale E; Sheetz, Michael A

    2013-04-01

    A lack of consensus regarding a model governing the release of patients following sealed source brachytherapy has led to a set of patient release policies that vary from institution to institution. The U.S. Nuclear Regulatory Commission has issued regulatory guidance on patient release in NUREG 1556, Volume 9, Rev. 2, Appendix U, which allows calculation of release limits following implant brachytherapy. While the formalism presented in NUREG is meaningful for the calculation of release limits in the context of relatively high energy gamma emitters, it does not estimate accurately the effective dose equivalent for the common low dose rate brachytherapy sources Cs, I, and Pd. NUREG 1556 states that patient release may be based on patient-specific calculations as long as the calculation is documented. This work is intended to provide a format for patient-specific calculations to be used for the consideration of patients' release following the implantation of certain low dose rate brachytherapy isotopes.

  6. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Speith, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials were evaluated for their rates of heat release and smoke generation. Top layers with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/cm2. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers

  7. Calculated emission rates for barium releases in space

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.

    1989-01-01

    The optical emissions from barium releases in space are caused by resonance and fluorescent scattering of sunlight. Emission rates for the dominant ion and neutral lines are calculated assuming the release to be optically thin and the barium to be in radiative equilibrium with the solar radiation. The solar spectrum has deep Fraunhofer absorption lines at the primary barium ion resonances. A velocity component toward or away from the sun will Doppler shift the emission lines relative to the absorption lines and the emission rates will increase many-fold over the rest value. The Doppler brightening is important in shaped charge or satellite releases where the barium is injected at high velocities. Emission rates as a function of velocity are calculated for the 4554, 4934, 5854, 6142 and 6497 A ion emission lines and the dominant neutral line at 5535 A. Results are presented for injection parallel to the ambient magnetic field, B, and for injection at an angle to B.

  8. Release-rate calorimetry of multilayered materials for aircraft seats

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Parker, J. A.; Duskin, F.; Spieth, H.; Trabold, E.

    1980-01-01

    Multilayered samples of contemporary and improved fire-resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire-blocking layer, and cushion-reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat-release rate of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicon adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis.

  9. 48 CFR 1509.170-7 - Release of ratings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Release of ratings. 1509... National Institutes of Health Contract Performance System, a written request is not applicable. (c) Freedom of Information Act requests shall be processed by the EPA Freedom of Information Act office where...

  10. Anthropogenic carbon release rate unprecedented during past 66 million years

    NASA Astrophysics Data System (ADS)

    Zeebe, R. E.; Ridgwell, A.; Zachos, J. C.

    2015-12-01

    Carbon release rates from anthropogenic sources have reached a record high of about 10 Pg C/y in 2013. However, due to uncertainties in the strength of climate system feedbacks, the full impact of the rapid carbon release on the Earth system is difficult to predict with confidence. Geologic analogues from past transient climate changes could provide invaluable constraints but only if the associated carbon release rates can be reliably reconstructed. We present a new technique - based on combined data-model analysis - to extract rates of change from the geological record, without the need for a stratigraphic age model. Given currently available records, we then show that the present anthropogenic carbon release rate is unprecedented during the Cenozoic (past 66 million years) by at least an order of magnitude. Our results have important implications for our ability to use past analogues to predict future changes, including constraints on climate sensitivity, ocean acidification, and impacts on marine and terrestrial ecosystems. For example, the fact that we have effectively entered an era of 'no analogue' state presents fundamental challenges to constraining forward modeling. Furthermore, future ecosystem disruptions will likely exceed the relatively limited extinctions observed during climate aberrations throughout the Cenozoic.

  11. Fracture patterns and the energy release rate of phosphorene

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Hong, Jiawang; Pidaparti, Ramana; Wang, Xianqiao

    2016-03-01

    Phosphorene, also known as monolayer black phosphorus, has been enjoying popularity in electronic devices due to its superior electrical properties. However, it's relatively low Young's modulus, low fracture strength and susceptibility to structural failure have limited its application in mechanical devices. Therefore, in order to design more mechanically reliable devices that utilize phosphorene, it is necessary to explore the fracture patterns and energy release rate of phosphorene. In this study, molecular dynamics simulations are performed to investigate phosphorene's fracture mechanism. The results indicate that fracture under uniaxial tension along the armchair direction is attributed to a break in the interlayer bond angles, while failure in the zigzag direction is triggered by the break in both intra-layer angles and bonds. Furthermore, we developed a modified Griffith criterion to analyze the energy release rate of phosphorene and its dependence on the strain rates and orientations of cracks. Simulation results indicate that phosphorene's energy release rate remains almost unchanged in the armchair direction while it fluctuates intensively in the zigzag direction. Additionally, the strain rate was found to play a negligible role in the energy release rate. The geometrical factor α in the Griffith's criterion is almost constant when the crack orientation is smaller than 45 degree, regardless of the crack orientation and loading direction. Overall, these findings provide helpful insights into the mechanical properties and failure behavior of phosphorene.Phosphorene, also known as monolayer black phosphorus, has been enjoying popularity in electronic devices due to its superior electrical properties. However, it's relatively low Young's modulus, low fracture strength and susceptibility to structural failure have limited its application in mechanical devices. Therefore, in order to design more mechanically reliable devices that utilize phosphorene, it is

  12. Effect of crack-microcracks interaction on energy release rates

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.; Wu, Shaofu

    1990-01-01

    The energy release rates associated with the main crack advancing into its surrounding damage zone, and the damage zone translation relative to the main crack, as well as the energy of interaction between the crack and the damage zone are analyzed. The displacement and stress fields for this crack-damage interaction problem are reconstructed by employing a semi-empirical stress analysis which involves experimental evaluation of the average microcrack density in the damage zone.

  13. Release rates in a salt repository by diffusion

    SciTech Connect

    Hwang, Y.; Lee, W.W.L.; Chambre, P.L.; Pigford, T.H.

    1988-09-01

    In a recent analysis, we predicted extremely small brine migration velocities after emplacement of waste packages. Therefore it is expected that mass transfer of radioactive species dissolved in the brine is likely to be controlled by molecular diffusion. Here we apply the analytic solutions for the rate of diffusive mass transfer of dissolved species through a porous medium predict radionuclide release from waste packages in salt. This analysis shows that for the parameter values selected here, and for containment times of over 300 years, release rates from individual waste packages in sale can meet the US Nuclear Regulatory Commission's (USNRC) performance objective for the engineered barrier system. If many waste packages are actually exposed to brine much sooner than 300 years after emplacement, it will be difficult to meet the release rate for /sup 137/Cs, calculated from the USNRC regulation. In this report we present the analytic solutions and some numerical illustrations of the molecular diffusion analysis. We also compare the results with a different type of diffusion analysis in the Environmental Assessments for the potential repository sites in salt. 21 refs., 4 figs.

  14. Dynamic energy release rate in couple-stress elasticity

    NASA Astrophysics Data System (ADS)

    Morini, L.; Piccolroaz, A.; Mishuris, G.

    2013-07-01

    This paper is concerned with energy release rate for dynamic steady state crack problems in elastic materials with microstructures. A Mode III semi-infinite crack subject to loading applied on the crack surfaces is considered. The micropolar behaviour of the material is described by the theory of couple-stress elasticity developed by Koiter. A general expression for the dynamic J-integral including both traslational and micro-rotational inertial contributions is derived, and the conservation of this integral on a path surrounding the crack tip is demonstrated.

  15. Effect of Quaternary Ammonium Carboxymethylchitosan on Release Rate In-vitro of Aspirin Sustained-release Matrix Tablets

    PubMed Central

    Meng, Lingbin; Teng, Zhongqiu; Zheng, Nannan; Meng, Weiwei; Dai, Rongji; Deng, Yulin

    2013-01-01

    The aim of this study was to develop a derivative of chitosan as pharmaceutical excipient used in sustained-release matrix tablets of poorly soluble drugs. A water-soluble quaternary ammonium carboxymethylchitosan was synthesized by a two-step reaction with carboxymethylchitosan (CMCTS), decylalkyl dimethyl ammonium and epichlorohydrin. The elemental analysis showed that the target product with 10.27% of the maximum grafting degree was obtained. To assess the preliminary safety of this biopolymer, cell toxicity assay was employed. In order to further investigate quaternary ammonium carboxymethylchitosan application as pharmaceutical excipient, aspirin was chosen as model drug. The effect of quaternary ammonium CMCTS on aspirin release rate from sustained-release matrix tablets was examined by in-vitro dissolution experiments. The results showed that this biopolymer had a great potential in increasing the dissolution of poorly soluble drug. With the addition of CMCTS-CEDA, the final cumulative release rate of drug rose up to 90%. After 12 h, at the grade of 10, 20 and 50 cps, the drug release rate increased from 58.1 to 90.7%, from 64.1 to 93.9%, from 69.3 to 96.1%, respectively. At the same time, aspirin release rate from sustainedrelease model was found to be related to the amount of quaternary ammonium CMCTS employed. With the increase of CMCTS-CEDA content, the accumulated release rate increased from 69.1% to 86.7%. The mechanism of aspirin release from sustained-release matrix tablets was also preliminary studied to be Fick diffusion. These data demonstrated that the chitosan derivative has positive effect on drug release from sustained-release matrix tablets. PMID:24250627

  16. Impact of release rates on the effectiveness of augmentative biological control agents.

    PubMed

    Crowder, David W

    2007-01-01

    To access the effect of augmentative biological control agents, 31 articles were reviewed that investigated the impact of release rates of 35 augmentative biological control agents on the control of 42 arthropod pests. In 64% of the cases, the release rate of the biological control agent did not significantly affect the density or mortality of the pest insect. Results where similar when parasitoids or predators were utilized as the natural enemy. Within any order of natural enemy, there were more cases where release rates did not affect augmentative biological control than cases where release rates were significant. There were more cases in which release rates did not affect augmentative biological control when pests were from the orders Hemiptera, Acari, or Diptera, but not with pests from the order Lepidoptera. In most cases, there was an optimal release rate that produced effective control of a pest species. This was especially true when predators were used as a biological control agent. Increasing the release rate above the optimal rate did not improve control of the pest and thus would be economically detrimental. Lower release rates were of ten optimal when biological control was used in conjunction with insecticides. In many cases, the timing and method of biological control applications were more significant factors impacting the effectiveness of biological control than the release rate. Additional factors that may limit the relative impact of release rates include natural enemy fecundity, establishment rates, prey availability, dispersal, and cannibalism.

  17. Impact of Release Rates on the Effectiveness of Augmentative Biological Control Agents

    PubMed Central

    Crowder, David W.

    2007-01-01

    To access the effect of augmentative biological control agents, 31 articles were reviewed that investigated the impact of release rates of 35 augmentative biological control agents on the control of 42 arthropod pests. In 64% of the cases, the release rate of the biological control agent did not significantly affect the density or mortality of the pest insect. Results where similar when parasitoidsor predators were utilized as the natural enemy. Within any order of natural enemy, there were more cases where release rates did not affect augmentative biological control than cases where release rates were significant. There were more cases in which release rates did not affect augmentative biological control when pests were from the orders Hemiptera, Acari, or Diptera, but not with pests from the order Lepidoptera. In most cases, there was an optimal release rate that produced effective control of a pest species. This was especially true when predators were used as a biological control agent. Increasing the release rate above the optimal rate did not improve control of the pest and thus would be economically detrimental. Lower release rates were of ten optimal when biological control was used in conjunction with insecticides. In many cases, the timing and method of biological control applications were more significant factors impacting the effectiveness of biological control than the release rate. Additional factors that may limit the relative impact of release rates include natural enemy fecundity, establishment rates, prey availability, dispersal, and cannibalism. PMID:20307240

  18. Inverse modelling of radionuclide release rates using gamma dose rate observations

    NASA Astrophysics Data System (ADS)

    Hamburger, Thomas; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2014-05-01

    Severe accidents in nuclear power plants such as the historical accident in Chernobyl 1986 or the more recent disaster in the Fukushima Dai-ichi nuclear power plant in 2011 have drastic impacts on the population and environment. The hazardous consequences reach out on a national and continental scale. Environmental measurements and methods to model the transport and dispersion of the released radionuclides serve as a platform to assess the regional impact of nuclear accidents - both, for research purposes and, more important, to determine the immediate threat to the population. However, the assessments of the regional radionuclide activity concentrations and the individual exposure to radiation dose underlie several uncertainties. For example, the accurate model representation of wet and dry deposition. One of the most significant uncertainty, however, results from the estimation of the source term. That is, the time dependent quantification of the released spectrum of radionuclides during the course of the nuclear accident. The quantification of the source terms of severe nuclear accidents may either remain uncertain (e.g. Chernobyl, Devell et al., 1995) or rely on rather rough estimates of released key radionuclides given by the operators. Precise measurements are mostly missing due to practical limitations during the accident. Inverse modelling can be used to realise a feasible estimation of the source term (Davoine and Bocquet, 2007). Existing point measurements of radionuclide activity concentrations are therefore combined with atmospheric transport models. The release rates of radionuclides at the accident site are then obtained by improving the agreement between the modelled and observed concentrations (Stohl et al., 2012). The accuracy of the method and hence of the resulting source term depends amongst others on the availability, reliability and the resolution in time and space of the observations. Radionuclide activity concentrations are observed on a

  19. Development of a Model for the Heat Release Rate of Wood. A Status Report.

    DTIC Science & Technology

    1985-05-01

    designates the slice bounded by the rear surface 0 ambient or original *0 oxygen R radiation rel release S front surface of specimen Vol volatiles ix w water...rate is one of the most important fire properties of a material. Whether a room fire will attain flashover depends on the total heat release rate of all...function of the net heat transfer through their front surface . A number of calorimeters have been developed to measure the heat release , rate per unit

  20. Inverse modelling of radionuclide release rates using gamma dose rate observations

    NASA Astrophysics Data System (ADS)

    Hamburger, Thomas; Evangeliou, Nikolaos; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2015-04-01

    Severe accidents in nuclear power plants such as the historical accident in Chernobyl 1986 or the more recent disaster in the Fukushima Dai-ichi nuclear power plant in 2011 have drastic impacts on the population and environment. Observations and dispersion modelling of the released radionuclides help to assess the regional impact of such nuclear accidents. Modelling the increase of regional radionuclide activity concentrations, which results from nuclear accidents, underlies a multiplicity of uncertainties. One of the most significant uncertainties is the estimation of the source term. That is, the time dependent quantification of the released spectrum of radionuclides during the course of the nuclear accident. The quantification of the source term may either remain uncertain (e.g. Chernobyl, Devell et al., 1995) or rely on estimates given by the operators of the nuclear power plant. Precise measurements are mostly missing due to practical limitations during the accident. The release rates of radionuclides at the accident site can be estimated using inverse modelling (Davoine and Bocquet, 2007). The accuracy of the method depends amongst others on the availability, reliability and the resolution in time and space of the used observations. Radionuclide activity concentrations are observed on a relatively sparse grid and the temporal resolution of available data may be low within the order of hours or a day. Gamma dose rates, on the other hand, are observed routinely on a much denser grid and higher temporal resolution and provide therefore a wider basis for inverse modelling (Saunier et al., 2013). We present a new inversion approach, which combines an atmospheric dispersion model and observations of radionuclide activity concentrations and gamma dose rates to obtain the source term of radionuclides. We use the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998; Stohl et al., 2005) to model the atmospheric transport of the released radionuclides. The

  1. 77 FR 47918 - Information Collection Activities (Released Rates)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-10

    ... rates that interstate movers of household goods charge for the services they offer). More specifically, the Interstate Commerce Act requires that such a mover offer what are known as ``full-value'' rates... predecessor agency, the Interstate Commerce Commission, have authorized moving companies to offer consumers...

  2. Residual thermal and moisture influences on the strain energy release rate analysis of edge delamination

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.; Raju, I. S.; Garber, D. P.

    1985-01-01

    A laminated plate theory analysis is developed to calculate the strain energy release rate associated with edge delamination growth in a composite laminate. The analysis includes the contribution of residual thermal and moisture stresses to the strain energy released. The strain energy release rate, G, increased when residual thermal effects were combined with applied mechanical strains, but then decreased when increasing moisture content was included. A quasi-three-dimensional finite element analysis indicated identical trends and demonstrated these same trends for the individual strain energy release rate components, G sub I and G sub II, associated with interlaminar tension and shear. An experimental study indicated that for T300/5208 graphite-epoxy composites, the inclusion of residual thermal and moisture stresses did not significantly alter the calculation of interlaminar fracture toughness from strain energy release rate analysis of edge delamination data taken at room temperature, ambient conditions.

  3. [Rate of controlled-release urea pervasion through membrane determined by ultraviolet spectrophotometry].

    PubMed

    Zuo, Xiu-jin; Wang, Zhen-xin; Dai, Xiao-min; Zhou, Yi; Ma, Xiao-jun

    2006-06-01

    Application of controlled-release nitrogenous fertilizers can improve the efficiency of fertilizers and reduce the environmental pollution. Controlled-release urea (coated urea) is one of the controlled-release nitrogenous fertilizers developed quickly in the recent years. The rate of controlled-release urea pervasion through membrane is the most important index of the capacity of controlled release. There is a maximum absorption at lambda=426 nm with complex in acidic solution, using p-dimethylaminozenzaldehyde as color reagent, and the absorbance exhibits a linear reponses to the urea concentration over the range of 7.5-210 microg x mL(-1). The method for determining the rate of controlled-release urea pervasion through membrane was realized through determining the content of urea in the liquor, the recovery efficiency of the method is 96.1%-103.9%.

  4. A simplified approach to strain energy release rate computations for interlaminar fracture of composites

    NASA Technical Reports Server (NTRS)

    Armanios, Erian A.; Rehfield, Lawrence W.

    1989-01-01

    A simple approach for the strain energy release rate computations based on the finite element method and a singular fitting model is presented. The model uses the stress and displacement distributions at the delamination front. The method is applied to a mixed-mode double cracked-lap-shear composite configuration. The strain energy release rate components predicted by the model are compared with the finite element crack-closure method. The effect of the mesh size on the stress and displacement distribution is isolated. The strain energy release rates predicted by relatively coarse mesh sizes are in good agreement with the finite element crack closure method.

  5. An atomistic methodology of energy release rate for graphene at nanoscale

    SciTech Connect

    Zhang, Zhen; Lee, James D.; Wang, Xianqiao

    2014-03-21

    Graphene is a single layer of carbon atoms packed into a honeycomb architecture, serving as a fundamental building block for electric devices. Understanding the fracture mechanism of graphene under various conditions is crucial for tailoring the electrical and mechanical properties of graphene-based devices at atomic scale. Although most of the fracture mechanics concepts, such as stress intensity factors, are not applicable in molecular dynamics simulation, energy release rate still remains to be a feasible and crucial physical quantity to characterize the fracture mechanical property of materials at nanoscale. This work introduces an atomistic simulation methodology, based on the energy release rate, as a tool to unveil the fracture mechanism of graphene at nanoscale. This methodology can be easily extended to any atomistic material system. We have investigated both opening mode and mixed mode at different temperatures. Simulation results show that the critical energy release rate of graphene is independent of initial crack length at low temperature. Graphene with inclined pre-crack possesses higher fracture strength and fracture deformation but smaller critical energy release rate compared with the graphene with vertical pre-crack. Owing to its anisotropy, graphene with armchair chirality always has greater critical energy release rate than graphene with zigzag chirality. The increase of temperature leads to the reduction of fracture strength, fracture deformation, and the critical energy release rate of graphene. Also, higher temperature brings higher randomness of energy release rate of graphene under a variety of predefined crack lengths. The energy release rate is independent of the strain rate as long as the strain rate is small enough.

  6. Anthropogenic carbon release rate unprecedented during the past 66 million years

    NASA Astrophysics Data System (ADS)

    Zeebe, Richard E.; Ridgwell, Andy; Zachos, James C.

    2016-04-01

    Carbon release rates from anthropogenic sources reached a record high of ~10 Pg C yr-1 in 2014. Geologic analogues from past transient climate changes could provide invaluable constraints on the response of the climate system to such perturbations, but only if the associated carbon release rates can be reliably reconstructed. The Palaeocene-Eocene Thermal Maximum (PETM) is known at present to have the highest carbon release rates of the past 66 million years, but robust estimates of the initial rate and onset duration are hindered by uncertainties in age models. Here we introduce a new method to extract rates of change from a sedimentary record based on the relative timing of climate and carbon cycle changes, without the need for an age model. We apply this method to stable carbon and oxygen isotope records from the New Jersey shelf using time-series analysis and carbon cycle-climate modelling. We calculate that the initial carbon release during the onset of the PETM occurred over at least 4,000 years. This constrains the maximum sustained PETM carbon release rate to less than 1.1 Pg C yr-1. We conclude that, given currently available records, the present anthropogenic carbon release rate is unprecedented during the past 66 million years. We suggest that such a `no-analogue’ state represents a fundamental challenge in constraining future climate projections. Also, future ecosystem disruptions are likely to exceed the relatively limited extinctions observed at the PETM.

  7. 77 FR 15187 - Released Rates of Motor Common Carriers of Household Goods

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Surface Transportation Board Released Rates of Motor Common Carriers of Household Goods AGENCY: Surface Transportation Board. ACTION: Notice of changes to rules protecting consumers during interstate...

  8. 76 FR 5431 - Released Rates of Motor Common Carriers of Household Goods

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-31

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Surface Transportation Board Released Rates of Motor Common Carriers of Household Goods AGENCY: Surface Transportation Board. ACTION: Notice, request for comments. SUMMARY: The Surface Transportation Board...

  9. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    SciTech Connect

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  10. Impact of heat release on strain rate field in turbulent premixed Bunsen flames

    DOE PAGES

    Coriton, Bruno Rene Leon; Frank, Jonathan H.

    2016-08-10

    The effects of combustion on the strain rate field are investigated in turbulent premixed CH4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts of heatmore » release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the

  11. Identification of release rates as a consequence of thermal impact on Radwaste - Experimental Studies

    SciTech Connect

    Boetsch, W.U.; Gruendler, D.; Thiel, J.

    2006-07-01

    Considering the fact that to our experiences fire accidents are of highest significance for the operational safety of a repository for Radwaste, a broad research project has been carried out in Germany on behalf of BfS (Federal Office for Radiation Protection) to develop a comprehensive approach for the determination of release rates under fire conditions. Various experiments were performed to target at the adjustment of theoretical models within safety and risk analysis of such installation. The investigations included the study of the release mechanisms caused by combustion of radioactive waste and the heating up of radioactive metallic scrap as well as the research of the behavior of an inactive waste drum in an open fire and the release rates out of waste simulation material. The experiments resulted in the identification of release rates as a consequence of thermal impact on Radwaste to allow a more realistic look at the nuclide specific risks and their consequences for safety assessments. Finally release fractions are calculated based on the thermal behavior of elements in the case of fire and their release rates. (authors)

  12. Production and release rate of (37)Ar from the UT TRIGA Mark-II research reactor.

    PubMed

    Johnson, Christine; Biegalski, Steven R; Artnak, Edward J; Moll, Ethan; Haas, Derek A; Lowrey, Justin D; Aalseth, Craig E; Seifert, Allen; Mace, Emily K; Woods, Vincent T; Humble, Paul

    2017-02-01

    Air samples were taken at various locations around The University of Texas at Austin's TRIGA Mark II research reactor and analyzed to determine the concentrations of (37)Ar, (41)Ar, and (133)Xe present. The measured ratio of (37)Ar/(41)Ar and historical records of (41)Ar releases were then utilized to estimate an annual average release rate of (37)Ar from the reactor facility. Using the calculated release rate, atmospheric transport modeling was performed in order to determine the potential impact of research reactor operations on nearby treaty verification activities. Results suggest that small research reactors (∼1 MWt) do not release (37)Ar in concentrations measurable by currently proposed OSI detection equipment.

  13. Influence of Finite Element Software on Energy Release Rates Computed Using the Virtual Crack Closure Technique

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Goetze, Dirk; Ransom, Jonathon (Technical Monitor)

    2006-01-01

    Strain energy release rates were computed along straight delamination fronts of Double Cantilever Beam, End-Notched Flexure and Single Leg Bending specimens using the Virtual Crack Closure Technique (VCCT). Th e results were based on finite element analyses using ABAQUS# and ANSYS# and were calculated from the finite element results using the same post-processing routine to assure a consistent procedure. Mixed-mode strain energy release rates obtained from post-processing finite elem ent results were in good agreement for all element types used and all specimens modeled. Compared to previous studies, the models made of s olid twenty-node hexahedral elements and solid eight-node incompatible mode elements yielded excellent results. For both codes, models made of standard brick elements and elements with reduced integration did not correctly capture the distribution of the energy release rate acr oss the width of the specimens for the models chosen. The results suggested that element types with similar formulation yield matching results independent of the finite element software used. For comparison, m ixed-mode strain energy release rates were also calculated within ABAQUS#/Standard using the VCCT for ABAQUS# add on. For all specimens mod eled, mixed-mode strain energy release rates obtained from ABAQUS# finite element results using post-processing were almost identical to re sults calculated using the VCCT for ABAQUS# add on.

  14. Calcium release rates from tooth enamel treated with dentifrices containing whitening agents and abrasives.

    PubMed

    Araujo, Danilo Barral; Silva, Luciana Rodrigues; de Araujo, Roberto Paulo Correia

    2010-01-01

    Tooth whitening agents containing hydrogen peroxide and carbamide peroxide are used frequently in esthetic dental procedures. However, lesions on the enamel surface have been attributed to the action of these products. Using conventional procedures for separating and isolating biological structures, powdered enamel was obtained and treated with hydrogen peroxide, carbamide peroxide, and sodium bicarbonate, ingredients typically found in dentifrices. The enamel was exposed to different pH levels, and atomic emission spectrometry was used to determine calcium release rates. As the pH level increased, the rate of calcium release from enamel treated with dentifrices containing whitening agents decreased. Carbamide peroxide produced the lowest amount of decalcification, while sodium bicarbonate produced the highest release rates at all pH levels.

  15. Effect of Different Polymer Concentration on Drug Release Rate and Physicochemical Properties of Mucoadhesive Gastroretentive Tablets.

    PubMed

    Agarwal, Shweta; Murthy, R S R

    2015-01-01

    Mucoadhesive tablets have emerged as potential candidates for gastroretentive drug delivery providing controlled release along with prolonged gastric residence time. Gastroretentive mucoadhesive tablets could result in increased bioavailability due to prolonged gastric residence time. A hydrophilic matrix system was developed as mucoadhesion is achievable on appropriate wetting and swelling of the polymers used. The polymers were so chosen so as to provide a balance between swelling, mucoadhesion and drug release. The polymers chosen were hydroxypropyl methylcellulose K4M, chitosan, and Carbopol 934. The concentrations of these polymers used has a great impact on the physicochemical properties of the resulting formulation. The tablets were formulated using wet granulation method and tranexamic acid was used as the model drug. The prepared tablets were characterized for size, shape, appearance, hardness, friability, weight variation, swelling, mucoadhesion and in vitro drug release. Several batches of tablets were prepared by varying the ratio of hydroxypropyl methylcellulose K4M and Chitosan. The batches having a greater ratio of chitosan showed higher rate of swelling, greater erosion, less mucoadhesion and faster release rate of the drug whereas the batches having greater ratio of hydroxypropyl methylcellulose K4M showed lesser rate of swelling, less erosion, better mucoadhesion and a smaller drug release rate. The level of carbopol was kept constant in all the batches.

  16. Effect of Different Polymer Concentration on Drug Release Rate and Physicochemical Properties of Mucoadhesive Gastroretentive Tablets

    PubMed Central

    Agarwal, Shweta; Murthy, R. S. R.

    2015-01-01

    Mucoadhesive tablets have emerged as potential candidates for gastroretentive drug delivery providing controlled release along with prolonged gastric residence time. Gastroretentive mucoadhesive tablets could result in increased bioavailability due to prolonged gastric residence time. A hydrophilic matrix system was developed as mucoadhesion is achievable on appropriate wetting and swelling of the polymers used. The polymers were so chosen so as to provide a balance between swelling, mucoadhesion and drug release. The polymers chosen were hydroxypropyl methylcellulose K4M, chitosan, and Carbopol 934. The concentrations of these polymers used has a great impact on the physicochemical properties of the resulting formulation. The tablets were formulated using wet granulation method and tranexamic acid was used as the model drug. The prepared tablets were characterized for size, shape, appearance, hardness, friability, weight variation, swelling, mucoadhesion and in vitro drug release. Several batches of tablets were prepared by varying the ratio of hydroxypropyl methylcellulose K4M and Chitosan. The batches having a greater ratio of chitosan showed higher rate of swelling, greater erosion, less mucoadhesion and faster release rate of the drug whereas the batches having greater ratio of hydroxypropyl methylcellulose K4M showed lesser rate of swelling, less erosion, better mucoadhesion and a smaller drug release rate. The level of carbopol was kept constant in all the batches. PMID:26997698

  17. Bioactive silica-based nanomaterials for doxorubicin delivery: evaluation of structural properties associated with release rate.

    PubMed

    Prokopowicz, Magdalena

    2013-10-01

    This study investigated the use of a novel particle-type formulation, composed of a sol-gel derived bioactive silica-poly(dimethylsiloxane) composite containing calcium and phosphate, as a slow release delivery system for an anticancer drug (doxorubicin hydrochloride, DOX). DOX in the solution form was in situ incorporated into the composite network during the sol-gel process. The DOX loaded-formulation was immersed in a simulated body fluid (SBF) having ion concentrations and a pH value nearly equal to those of human blood plasma. The effect of different drug loads and particle sizes - on the release profiles in such biomimetic conditions was studied. The bioactivity was examined in vitro with respect to the ability of hydroxyapatite layer to form on the surface of residual DOX-loaded formulation as a result of contact with SBF. The infrared absorption spectra, scanning electron microscopy, nitrogen gas adsorption/desorption, and X-ray powder diffraction studies were conducted before and after contact of the formulation with SBF. The results show that all the DOX-loaded formulations are characterized by mesoporosity with the uniform pore-size-distribution. The release profiles of DOX consisted of two sequential zero order-controlled stages with distinctly different release rates. After 20 days of DOX release, a semicrystalline carbonated hydroxyapatite with a highly developed porous structure was formed, indicative of their bioactive character. Furthermore, these new covered-particle-type formulations released DOX over 1 month at a constant rate.

  18. Effect of protein release rates from tablet formulations on the immune response after sublingual immunization.

    PubMed

    Borde, Annika; Ekman, Annelie; Holmgren, Jan; Larsson, Anette

    2012-11-20

    Dry vaccine formulations for sublingual administration would provide great advantages for public health use, especially in developing countries, since they are easy to administer and might also have improved stability properties. This study investigates the influence of protein release rate from mucoadhesive two-layer tablets on the elicited antibody responses after sublingual immunization. Two fast release tablets, one based on a mixture of lactose and microcrystalline cellulose (MCC) and one protein coated ethylcellulose (EC) tablet, and three hydrophilic matrix tablets with extended release (ER) properties based on HPMC 90 SH 100000 or Carbopol® 974-P NF were tested. The in vitro release profiles of the model protein ovalbumin (OVA) from these tablets were characterized and correlated to the in vivo potential of the tablets to induce an immune response after sublingual immunization in BALB/c mice. It could be concluded that a tablet with fast protein release elicits antibody titres not significantly different from titres obtained with OVA in solution, whereas low immune responses were observed with a slow release of OVA from the ER formulations. Thus, an ER tablet seems not favorable for vaccine delivery to the sublingual mucosa. Thus, we can present a fast releasing tablet formulation with attractive features for sublingual immunization, whereas the use of ER formulations for sublingual vaccination has to be investigated more in detail.

  19. Estimating release rates of phosphorus from zooplankton: model and experimental verification

    SciTech Connect

    Not Available

    1985-07-01

    The flux of phosphorus in a zooplankton-phytoplankton system is described by a simple compartment model, with differential equations for grazing, growth and reproduction of animals, and release and recycling of P. The mean release rates from zooplankton for a given period are derived for cases restricted to animals feeding on algae at densities above the incipient limiting food concentration. The model is used to analyze short term incubation experiments with Daphnia pulex feeding on Scenedesmus sp. and Daphnia longispina feeding on Rhodomonas lacustris in dim light. When food organisms were saturated with P. total release rates were in the range 1.1-1.5 ..mu..g P (mg dry wt)/sup -1/h/sup -1/ in accordance with a maximal excretion rate of 0.8 ..mu..g P (mg dry wt)/sup -1/h)/sup 1/ predicted by the model of Peters. Phosphorus-starved phytoplankton, containing less P, gave much lower release rates, about 0.05 ..mu..g P (mg dry wt)/sup -1/h/sup -1/, only 10% of the excretion rate predicted by the model of Peters.

  20. Esterase-Sensitive Prodrugs with Tunable Release Rates and Direct Generation of Hydrogen Sulfide.

    PubMed

    Zheng, Yueqin; Yu, Bingchen; Ji, Kaili; Pan, Zhixiang; Chittavong, Vayou; Wang, Binghe

    2016-03-24

    Prodrugs that release hydrogen sulfide upon esterase-mediated cleavage of an ester group followed by lactonization are described herein. By modifying the ester group and thus its susceptibility to esterase, and structural features critical to the lactonization rate, H2 S release rates can be tuned. Such prodrugs directly release hydrogen sulfide without the involvement of perthiol species, which are commonly encountered with existing H2 S donors. Additionally, such prodrugs can easily be conjugated to another non-steroidal anti-inflammatory agent, leading to easy synthesis of hybrid prodrugs. As a biological validation of the H2 S prodrugs, the anti-inflammatory effects of one such prodrug were examined by studying its ability to inhibit LPS-induced TNF-α production in RAW 264.7 cells. This type of H2 S prodrugs shows great potential as both research tools and therapeutic agents.

  1. Calculating the rate of exothermic energy release for catalytic converter efficiency monitoring

    SciTech Connect

    Hepburn, J.S.; Meitzler, A.H.

    1995-12-31

    This paper reports on the development of a new methodology for OBD-II catalyst efficiency monitoring. Temperature measurements taken from the center of the catalyst substrate or near the exterior surface of the catalyst brick were used in conjunction with macroscopic energy balances to calculate the instantaneous rate of exothermic energy generation within the catalyst. The total calculated rate of exothermic energy release over the FTP test cycle was within 10% of the actual or theoretical value and provided a good indicator of catalyst light-off for a variety of aged catalytic converters. Normalization of the rate of exothermic energy release in the front section of the converter by the mass flow rate of air inducted through the engine was found to provide a simple yet practical means of monitoring the converter under both FTP and varying types of road driving.

  2. Translational and extensional energy release rates (the J- and M-integrals) for a crack layer in thermoelasticity

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.; Gommerstadt, B.

    1985-01-01

    A number of papers have been presented on the evaluation of energy release rate for thermoelasticity and corresponding J integral. Two main approaches were developed to treat energy release rate in elasticity. The first is based on direct calculation of the potential energy rate with respect to crack length. The second makes use of Lagrangian formalism. The translational and expansional energy release rates in thermoelasticity are studied by employing the formalism of irreversible thermodynamics and the Crack Layer Approach.

  3. Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti1

    PubMed Central

    Hartwig, Ueli A.; Joseph, Cecillia M.; Phillips, Donald A.

    1991-01-01

    Alfalfa (Medicago sativa L.) releases different flavonoids from seeds and roots. Imbibing seeds discharge 3′,4′,5,7-substituted flavonoids; roots exude 5-deoxy molecules. Many, but not all, of these flavonoids induce nodulation (nod) genes in Rhizobium meliloti. The dominant flavonoid released from alfalfa seeds is identified here as quercetin-3-O-galactoside, a molecule that does not induce nod genes. Low concentrations (1-10 micromolar) of this compound, as well as luteolin-7-O-glucoside, another major flavonoid released from germinating seeds, and the aglycones, quercetin and luteolin, increase growth rate of R. meliloti in a defined minimal medium. Tests show that the 5,7-dihydroxyl substitution pattern on those molecules was primarily responsible for the growth effect, thus explaining how 5-deoxy flavonoids in root exudates fail to enhance growth of R. meliloti. Luteolin increases growth by a mechanism separate from its capacity to induce rhizobial nod genes, because it still enhanced growth rate of R. meliloti lacking functional copies of the three known nodD genes. Quercetin and luteolin also increased growth rate of Pseudomonas putida. They had no effect on growth rate of Bacillus subtilis or Agrobacterium tumefaciens, but they slowed growth of two fungal pathogens of alfalfa. These results suggest that alfalfa can create ecochemical zones for controlling soil microbes by releasing structurally different flavonoids from seeds and roots. PMID:16668056

  4. Measurement of semiochemical release rates with a dedicated environmental control system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    nsect semiochemical dispensers are commonly deployed under variable environmental conditions over a specified time frame; however, predictions of their longevity are hampered by a lack of methods to accurately monitor and predict how the primary variables affect the semiochemical release rate. Herei...

  5. Flash-Fire Propensity and Heat-Release Rate Studies of Improved Fire Resistant Materials

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.

    1978-01-01

    Twenty-six improved fire resistant materials were tested for flash-fire propensity and heat release rate properties. The tests were conducted to obtain a descriptive index based on the production of ignitable gases during the thermal degradation process and on the response of the materials under a specific heat load.

  6. The Release Rate of Environmental DNA from Juvenile and Adult Fish

    PubMed Central

    Maruyama, Atsushi; Nakamura, Keisuke; Yamanaka, Hiroki; Kondoh, Michio; Minamoto, Toshifumi

    2014-01-01

    The environmental DNA (eDNA) technique is expected to become a powerful, non-invasive tool for estimating the distribution and biomass of organisms. This technique was recently shown to be applicable to aquatic vertebrates by collecting extraorganismal DNA floating in the water or absorbed onto suspended particles. However, basic information on eDNA release rate is lacking, despite it being essential for practical applications. In this series of experiments with bluegill sunfish (Lepomis macrochirus), we examined the effect of fish developmental stage on eDNA release rate. eDNA concentration reached equilibrium 3 days after the individual fish were introduced into the separate containers, enabling calculation of the eDNA release rate (copies h−1) from individual fish on the assumption that the number of eDNA released from the fish per unit time equals total degradation in the container (copies h−1). The eDNA release rate was 3–4 times higher in the adult (body weight: 30–75 g) than in the juvenile group (0.5–2.0 g). Such positive relationship between fish size and eDNA release rate support the possibility of biomass rather than density estimation using eDNA techniques. However, the eDNA release rate per fish body weight (copies h−1 g−1) was slightly higher in the juvenile than the adult group, which is likely because of the ontogenetic reduction in metabolic activity. Therefore, quantitative eDNA data should be carefully interpreted to avoid overestimating biomass when the population is dominated by juveniles, because the age structure of the focal population is often variable and unseen in the field. eDNA degradation rates (copies l−1 h−1), calculated by curve fitting of time-dependent changes in eDNA concentrations after fish removal, were 5.1–15.9% per hour (half-life: 6.3 h). This suggests that quantitative eDNA data should be corrected using a degradation curve attained in the target field. PMID:25479160

  7. Optimum timing for integrated pest management: modelling rates of pesticide application and natural enemy releases.

    PubMed

    Tang, Sanyi; Tang, Guangyao; Cheke, Robert A

    2010-05-21

    Many factors including pest natural enemy ratios, starting densities, timings of natural enemy releases, dosages and timings of insecticide applications and instantaneous killing rates of pesticides on both pests and natural enemies can affect the success of IPM control programmes. To address how such factors influence successful pest control, hybrid impulsive pest-natural enemy models with different frequencies of pesticide sprays and natural enemy releases were proposed and analyzed. With releasing both more or less frequent than the sprays, a stability threshold condition for a pest eradication periodic solution is provided. Moreover, the effects of times of spraying pesticides (or releasing natural enemies) and control tactics on the threshold condition were investigated with regard to the extent of depression or resurgence resulting from pulses of pesticide applications. Multiple attractors from which the pest population oscillates with different amplitudes can coexist for a wide range of parameters and the switch-like transitions among these attractors showed that varying dosages and frequencies of insecticide applications and the numbers of natural enemies released are crucial. To see how the pesticide applications could be reduced, we developed a model involving periodic releases of natural enemies with chemical control applied only when the densities of the pest reached the given Economic Threshold. The results indicate that the pest outbreak period or frequency largely depends on the initial densities and the control tactics.

  8. Comparison of in vitro release rates of acyclovir from cream formulations using vertical diffusion cells.

    PubMed

    Nallagundla, Sumalatha; Patnala, Srinivas; Kanfer, Isadore

    2014-08-01

    Acyclovir, indicated in the treatment of herpes labialis ("cold sores"), is formulated as semisolid topical dosage forms and marketed in numerous countries. Since the formulations of the various acyclovir products may differ from country to country, this study was undertaken to compare the in vitro release of acyclovir from various generic cream products available on the South African and Indian markets using the respective brand/innovator product as the reference product. The in vitro studies were carried out using vertical diffusion cells with a diffusional surface area of 1.767 cm(2) and various commercially available membranes. Normal saline was used as receptor fluid and the temperature maintained at 32 ± 0.5°C. The in vitro release comparisons were based on the recommendations described in the US Food and Drug Administration Draft Guidance for acyclovir ointment and the SUPAC-SS Guidance for non-sterile semisolid dosage forms. The release rates (slope) of the test (T) and the relevant reference product (R) were monitored and compared. The comparative release of acyclovir from the various generic formulations compared with the reference product was found to be within the limits of 75-133.33% with a 90% confidence interval. These experiments indicate that the generic acyclovir cream formulations exhibited release rates that were comparable to the innovator product and could be considered to be bioequivalent.

  9. Oil and drug control the release rate from lyotropic liquid crystals.

    PubMed

    Martiel, Isabelle; Baumann, Nicole; Vallooran, Jijo J; Bergfreund, Jotam; Sagalowicz, Laurent; Mezzenga, Raffaele

    2015-04-28

    The control of the diffusion coefficient by the dimensionality d of the structure appears as a most promising lever to efficiently tune the release rate from lyotropic liquid crystalline (LLC) phases and dispersed particles towards sustained, controlled and targeted release. By using phosphatidylcholine (PC)- and monolinoleine (MLO)-based mesophases with various apolar structural modifiers and water-soluble drugs, we present a comprehensive study of the dimensional structural control of hydrophilic drug release, including 3-d bicontinuous cubic, 2-d lamellar, 1-d hexagonal and 0-d micellar cubic phases in excess water. We investigate how the surfactant, the oil properties and the drug hydrophilicity mitigate or even cancel the effect of structure variation on the drug release rate. Unexpectedly, the observed behavior cannot be fully explained by the thermodynamic partition of the drug into the lipid matrix, which points out to previously overlooked kinetic effects. We therefore interpret our results by discussing the mechanism of structural control of the diffusion rate in terms of drug permeation through the lipid membrane, which includes exchange kinetics. A wide range of implications follow regarding formulation and future developments, both for dispersed LLC delivery systems and topical applications in bulk phase.

  10. Steric environment around acetylcholine head groups of bolaamphiphilic nanovesicles influences the release rate of encapsulated compounds

    PubMed Central

    Stern, Avital; Guidotti, Matteo; Shaubi, Eleonora; Popov, Mary; Linder, Charles; Heldman, Eliahu; Grinberg, Sarina

    2014-01-01

    Two bolaamphiphilic compounds with identical acetylcholine (ACh) head groups, but with different lengths of an alkyl chain pendant adjacent to the head group, as well as differences between their hydrophobic skeleton, were investigated for their ability to self-assemble into vesicles that release their encapsulated content upon hydrolysis of their head groups by acetylcholinesterase (AChE). One of these bolaamphiphiles, synthesized from vernolic acid, has an alkyl chain pendant of five methylene groups, while the other, synthesized from oleic acid, has an alkyl chain pendant of eight methylene groups. Both bolaamphiphiles formed stable spherical vesicles with a diameter of about 130 nm. The ACh head groups of both bolaamphiphiles were hydrolyzed by AChE, but the hydrolysis rate was significantly faster for the bolaamphiphile with the shorter aliphatic chain pendant. Likewise, upon exposure to AChE, vesicles made from the bolaamphiphile with the shorter alkyl chain pendant released their encapsulated content faster than vesicles made from the bolaamphiphile with the longer alkyl chain pendant. Our results suggest that the steric environment around the ACh head group of bolaamphiphiles is a major factor affecting the hydrolysis rate of the head groups by AChE. Attaching an alkyl chain to the bolaamphiphile near the ACh head group allows self-assembled vesicles to form with a controlled release rate of the encapsulated materials, whereas shorter alkyl chains enable a faster head group hydrolysis, and consequently faster release, than longer alkyl chains. This principle may be implemented in the design of bolaamphiphiles for the formation of vesicles for drug delivery with desired controlled release rates. PMID:24531296

  11. Study on encapsulation of chlorine dioxide in gelatin microsphere for reducing release rate

    PubMed Central

    Ci, Ying; Wang, Lin; Guo, Yanchuan; Sun, Ruixue; Wang, Xijie; Li, Jinyou

    2015-01-01

    Objective: This study aims to explore the effects of encapsulation of chlorine dioxide in a hydrophilic biodegradable polymer gelatin to reduce its release rate. Methods: An emulsification-coacervation method was adopted. The characterizations of chlorine dioxide-gelatin microspheres were described. Using UV-vis spectrophotometer the λmax of chlorine dioxide was observed at 358 nm. The particle size and distribution of chlorine oxide-gelatin microspheres was measured by a dynamic light scattering (DLS) method, the diameter was (1400~1900) nm. The entrapment of chlorine dioxide-gelatin microspheres was confirmed by IR. The surface morphology, size, and shape of chlorine dioxide-gelatin microspheres were analyzed using Scanning electron microscope (SEM). Results: It showed that the encapsulated microspheres size was around 2000 nm with uniform distribution. The percentage entrapment of chlorine dioxide in the encapsulated samples was about 80~85%. A slow release study of chlorine dioxide from the encapsulated biopolymer (gelatin) in air was also carried out, which showed continuous release up to ten days. Conclusions: It can be concluded that it is possible to make a slow release formulation of ClO2 by entrapped in a hydrophilic biodegradable polymer gelatin. ClO2-gelatin microspheres can stable release low concentration ClO2 gas over an extended period. PMID:26550151

  12. Variation of strain energy release rate with plate thickness. [fracture mode transition

    NASA Technical Reports Server (NTRS)

    Sih, G. C.; Hartranft, R. J.

    1973-01-01

    An analytical model of a through-thickness crack in a statically stretched plate is presented in which the crack front stress state is permitted to vary in the direction of the plate thickness. The amplitude or intensity of this stress field can be made nearly constant over a major portion of the interior crack front which is in a state of plane strain. The average amount of work available for extending a small segment of the crack across the thickness is associated with an energy release rate quantity in a manner similar to the two-dimensional Griffith crack model. The theoretically calculated energy release rate is shown to increase with increasing plate thickness, indicating that available work for crack extension is higher in a thicker plate.

  13. Interaction of Two Micro-slot Flames: Heat Release Rate and Flame Shape

    NASA Astrophysics Data System (ADS)

    Kuwana, K.; Kato, S.; Kosugi, A.; Hirasawa, T.; Nakamura, Y.

    2014-11-01

    This paper studies the interaction between two identical micro-slot diffusion flames. Here, we define a micro-slot flame as a slot flame of which the slot width is less than about 1 mm. Because of its smallness, a micro-slot flame has a high heating density and can be used as a small heat source. However, the heat release rate of a single micro-slot flame is limited, and therefore, multiple micro-slot flames may be used to increase total heat release rate. As a first step, this paper considers a situation in which two micro-slot flames are used with certain burner spacing. When two diffusion flames are placed closely, flame shape changes from that of an isolated flame. Studying such flame shape change and resultant change in total heat release rate is the topic of this paper. Experiment is conducted and total heat release rate is measured by integrating CH* chemiluminescence recorded using a CCD camera and an optical filter of the wavelength of 430 nm. Two different burner materials, copper and glass, are tested to study the effect of heat loss to burners. An analytical model is applied to predict flame shape. In addition to the classical Burke-Schumann assumptions, two slot flames are modeled as line sources with zero width, enabling a simple analytical solution for the critical burner spacing at which two flames touch each other. The critical burner spacing is a key parameter that characterizes the interaction between two micro-slot flames. Computational fluid dynamics (CFD) simulations are then conducted to test the validity of the present theory. CFD results are favorably compared with the theoretical prediction.

  14. Convergence of strain energy release rate components for edge-delaminated composite laminates

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Crews, J. H., Jr.; Aminpour, M. A.

    1987-01-01

    Strain energy release rates for edge delaminated composite laminates were obtained using quasi 3 dimensional finite element analysis. The problem of edge delamination at the -35/90 interfaces of an 8-ply composite laminate subjected to uniform axial strain was studied. The individual components of the strain energy release rates did not show convergence as the delamination tip elements were made smaller. In contrast, the total strain energy release rate converged and remained unchanged as the delamination tip elements were made smaller and agreed with that calculated using a classical laminated plate theory. The studies of the near field solutions for a delamination at an interface between two dissimilar isotropic or orthotropic plates showed that the imaginary part of the singularity is the cause of the nonconvergent behavior of the individual components. To evaluate the accuracy of the results, an 8-ply laminate with the delamination modeled in a thin resin layer, that exists between the -35 and 90 plies, was analyzed. Because the delamination exists in a homogeneous isotropic material, the oscillatory component of the singularity vanishes.

  15. Convergence of strain energy release rate components for edge-delaminated composite laminates

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Crews, J. H., Jr.; Aminpour, M. A.

    1988-01-01

    Strain energy release rates for edge delaminated composite laminates were obtained using quasi 3 dimensional finite element analysis. The problem of edge delamination at the -35/90 interfaces of an 8-ply composite laminate subjected to uniform axial strain was studied. The individual components of the strain energy release rates did not show convergence as the delamination tip elements were made smaller. In contrast, the total strain energy release rate converged and remained unchanged as the delamination tip elements were made smaller and agreed with that calculated using a classical laminated plate theory. The studies of the near field solutions for a delamination at an interface between two dissimilar isotropic or orthotropic plates showed that the imaginary part of the singularity is the cause of the nonconvergent behavior of the individual components. To evaluate the accuracy of the results, an 8-ply laminate with the delamination modeled in a thin resin layer, that exists between the -35 and 90 plies, was analyzed. Because the delamination exists in a homogeneous isotropic material, the oscillatory component of the singularity vanishes.

  16. Enclosure fire hazard analysis using relative energy release criteria. [burning rate and combustion control

    NASA Technical Reports Server (NTRS)

    Coulbert, C. D.

    1978-01-01

    A method for predicting the probable course of fire development in an enclosure is presented. This fire modeling approach uses a graphic plot of five fire development constraints, the relative energy release criteria (RERC), to bound the heat release rates in an enclosure as a function of time. The five RERC are flame spread rate, fuel surface area, ventilation, enclosure volume, and total fuel load. They may be calculated versus time based on the specified or empirical conditions describing the specific enclosure, the fuel type and load, and the ventilation. The calculation of these five criteria, using the common basis of energy release rates versus time, provides a unifying framework for the utilization of available experimental data from all phases of fire development. The plot of these criteria reveals the probable fire development envelope and indicates which fire constraint will be controlling during a criteria time period. Examples of RERC application to fire characterization and control and to hazard analysis are presented along with recommendations for the further development of the concept.

  17. Species production and heat release rates in two-layered natural gas fires

    SciTech Connect

    Zukoski, E.E.; Morehart, J.H.; Kubota, T.; Toner, S.J. )

    1991-02-01

    A fire burning in an enclosure with restricted ventilation will result in the accumulation of a layer of warm products of combustion mixed with entrained air adjacent to the ceiling. For many conditions, the depth of this layer will extend to occupy a significant fraction of the volume of the room. Eventually, the interface between this vitiated ceiling layer and the uncontaminated environment below will position itself so that a large portion of the combustion processes occur in this vitiated layer. A description is given of experimental work concerning the rates of formation of product species and heat release in a turbulent, buoyant natural gas diffusion flame burning in this two-layered configuration. The enclosure was modeled by placing a hood above a burner so that it accumulated the plume gases, and the unsteady development of the ceiling layer was modeled by the direct addition of air into the upper portion of the hood. Measurements of the composition of these gases allowed the computation of stoichiometries and heat release rates. These investigations showed that the species produced in the flame depend primarily on the stoichiometry of the gases present in the ceiling layer and weakly on the temperature of the layer, but are independent of the fuel pair ratio of the mass transported into the layer by the plume. Heat release rates in the fires were compared to a theoretical limit based on a stoichiometric reaction of fuel and air with excess components left unchanged by the combustion.

  18. Modulation of Tenoxicam release from hydrophilic matrix: modulator membrane versus rate-controlling membrane.

    PubMed

    El-Nabarawi, Mohamed Ahmed

    2005-09-01

    This paper describes the preparation of two layered device comprising of tenoxicam containing layer and a drug free membrane layer based on Geomatrix Technology. Our device based on bilaminated films which produced by a casting/solvent evaporation technique. The drug-hydroxypropyl methylcellulose (HPMC) layer was covered by drug free membrane layer composed of a mixture of different ratios of HPMC and ethyl cellulose (EC). The prepared devices were evaluated for thickness, weight, drug content uniformity, water absorption capacity and in-vitro drug release. The films were also evaluated for appearance, smoothness and transparency. The influence of drug free membrane layer composition and thickness on the drug release pattern was studied on 12 devices (D1 to D12). The results indicate that, the release of drug from HPMC matrixes without the drug free membrane layer was fast and follows diffusion controlled mechanism. The release of drug from the devices D1, D4, D9 and D12 follow the same mechanism, while the release of drug from other devices become linear with time (zero order) and extended for long time especially when thickness and the ratio of EC was increased in the drug free membrane layer. From this study it is concluded that, changing the geometry of drug layer by addition of drug free membrane layer and changing its composition and thickness plays an important role in determining whether the drug free membrane layer is rate-controlling or modulator membrane. Hence it can facilitate the development of different pharmaceutical products with different release pattern.

  19. Planar laser-induced fluorescence imaging of flame heat release rate

    SciTech Connect

    Paul, P.H.; Najm, H.N.

    1997-12-12

    Local heat release rate represents one of the most interesting experimental observables in the study of unsteady reacting flows. The direct measure of burning or heat release rate as a field variable is not possible. Numerous experimental investigations have relied on inferring this type of information as well as flame front topology from indirect measures which are presumed to be correlated. A recent study has brought into question many of the commonly used flame front marker and burning rate diagnostics. This same study found that the concentration of formyl radical offers the best possibility for measuring flame burning rate. However, primarily due to low concentrations, the fluorescence signal level from formyl is too weak to employ this diagnostic for single-pulse measurements of turbulent reacting flows. In this paper the authors describe and demonstrate a new fluorescence-based reaction front imaging diagnostic suitable for single-shot applications. The measurement is based on taking the pixel-by-pixel product of OH and CH{sub 2}O planar laser-induced fluorescence images to yield an image closely related to a reaction rate. The spectroscopic and collisional processes affecting the measured signals are discussed and the foundation of the diagnostic, as based on laminar and unsteady flame calculations, is presented. The authors report the results of applying this diagnostic to the study of a laminar premixed flame subject to an interaction with an isolated line-vortex pair.

  20. Increased survival rate by local release of diclofenac in a murine model of recurrent oral carcinoma

    PubMed Central

    Will, Olga Maria; Purcz, Nicolai; Chalaris, Athena; Heneweer, Carola; Boretius, Susann; Purcz, Larissa; Nikkola, Lila; Ashammakhi, Nureddin; Kalthoff, Holger; Glüer, Claus-Christian; Wiltfang, Jörg; Açil, Yahya; Tiwari, Sanjay

    2016-01-01

    Despite aggressive treatment with radiation and combination chemotherapy following tumor resection, the 5-year survival rate for patients with head and neck cancer is at best only 50%. In this study, we examined the therapeutic potential of localized release of diclofenac from electrospun nanofibers generated from poly(D,L-lactide-co-glycolide) polymer. Diclofenac was chosen since anti-inflammatory agents that inhibit cyclooxygenase have shown great potential in their ability to directly inhibit tumor growth as well as suppress inflammation-mediated tumor growth. A mouse resection model of oral carcinoma was developed by establishing tumor growth in the oral cavity by ultrasound-guided injection of 1 million SCC-9 cells in the floor of the mouth. Following resection, mice were allocated into four groups with the following treatment: 1) no treatment, 2) implanted scaffolds without diclofenac, 3) implanted scaffolds loaded with diclofenac, and 4) diclofenac given orally. Small animal ultrasound and magnetic resonance imaging were utilized for longitudinal determination of tumor recurrence. At the end of 7 weeks following tumor resection, 33% of mice with diclofenac-loaded scaffolds had a recurrent tumor, in comparison to 90%–100% of the mice in the other three groups. At this time point, mice with diclofenac-releasing scaffolds showed 89% survival rate, while the other groups showed survival rates of 10%–25%. Immunohistochemical staining of recurrent tumors revealed a near 10-fold decrease in the proliferation marker Ki-67 in the tumors derived from mice with diclofenac-releasing scaffolds. In summary, the local application of diclofenac in an orthotopic mouse tumor resection model of oral cancer reduced tumor recurrence with significant improvement in survival over a 7-week study period following tumor resection. Local drug release of anti-inflammatory agents should be investigated as a therapeutic option in the prevention of tumor recurrence in oral squamous

  1. Increased survival rate by local release of diclofenac in a murine model of recurrent oral carcinoma.

    PubMed

    Will, Olga Maria; Purcz, Nicolai; Chalaris, Athena; Heneweer, Carola; Boretius, Susann; Purcz, Larissa; Nikkola, Lila; Ashammakhi, Nureddin; Kalthoff, Holger; Glüer, Claus-Christian; Wiltfang, Jörg; Açil, Yahya; Tiwari, Sanjay

    Despite aggressive treatment with radiation and combination chemotherapy following tumor resection, the 5-year survival rate for patients with head and neck cancer is at best only 50%. In this study, we examined the therapeutic potential of localized release of diclofenac from electrospun nanofibers generated from poly(D,L-lactide-co-glycolide) polymer. Diclofenac was chosen since anti-inflammatory agents that inhibit cyclooxygenase have shown great potential in their ability to directly inhibit tumor growth as well as suppress inflammation-mediated tumor growth. A mouse resection model of oral carcinoma was developed by establishing tumor growth in the oral cavity by ultrasound-guided injection of 1 million SCC-9 cells in the floor of the mouth. Following resection, mice were allocated into four groups with the following treatment: 1) no treatment, 2) implanted scaffolds without diclofenac, 3) implanted scaffolds loaded with diclofenac, and 4) diclofenac given orally. Small animal ultrasound and magnetic resonance imaging were utilized for longitudinal determination of tumor recurrence. At the end of 7 weeks following tumor resection, 33% of mice with diclofenac-loaded scaffolds had a recurrent tumor, in comparison to 90%-100% of the mice in the other three groups. At this time point, mice with diclofenac-releasing scaffolds showed 89% survival rate, while the other groups showed survival rates of 10%-25%. Immunohistochemical staining of recurrent tumors revealed a near 10-fold decrease in the proliferation marker Ki-67 in the tumors derived from mice with diclofenac-releasing scaffolds. In summary, the local application of diclofenac in an orthotopic mouse tumor resection model of oral cancer reduced tumor recurrence with significant improvement in survival over a 7-week study period following tumor resection. Local drug release of anti-inflammatory agents should be investigated as a therapeutic option in the prevention of tumor recurrence in oral squamous

  2. The effect of HPMC particle size on the drug release rate and the percolation threshold in extended-release mini-tablets.

    PubMed

    Mohamed, Faiezah A A; Roberts, Matthew; Seton, Linda; Ford, James L; Levina, Marina; Rajabi-Siahboomi, Ali R

    2015-01-01

    The particle size of HPMC is a critical factor that can influence drug release rate from hydrophilic matrix systems. Percolation theory is a statistical tool which is used to study the disorder of particles in a lattice of a sample. The percolation threshold is the point at which a component is dominant in a cluster resulting in significant changes in drug release rates. Mini-tablets are compact dosage forms of 1.5-4 mm diameter, which have potential benefits in the delivery of drug to some patient groups such as pediatrics. In this study, the effect of HPMC particle size on hydrocortisone release and its associated percolation threshold for mini-tablets and tablets was assessed. For both mini-tablets and tablets, large polymer particles reduced tensile strength, but increased the drug release rate and the percolation threshold. Upon hydration, compacts with 45-125 μm HPMC particles formed a strong gel layer with low porosity, reducing hydrocortisone release rates. In comparison, faster drug release rates were obtained when 125-355 µm HPMC particles were used, due to the greater pore sizes that resulted in the formation of a weaker gel. Using 125-355 µm HPMC particles increased the percolation threshold for tablets and to a greater extent for mini-tablets. This work has demonstrated the importance of HPMC particle size in ER matrices, the effects of which are even more obvious for mini-tablets.

  3. Self-Setting Calcium Phosphate Cements with Tunable Antibiotic Release Rates for Advanced Antimicrobial Applications.

    PubMed

    Ghosh, Shreya; Wu, Victoria; Pernal, Sebastian; Uskoković, Vuk

    2016-03-01

    Osteomyelitis, an infectious disease predominantly tied to poor sanitary conditions in underdeveloped regions of the world, is in need of inexpensive, easily in situ synthesizable and administrable materials for its treatment. The results of this study stem from the attempt to create one such affordable and minimally invasive therapeutic platform in the form of a self-setting, injectable cement with a tunable drug release profile, composed of only nanoparticulate hydroxyapatite, the synthetic version of the bone mineral. Cements comprised two separately synthesized hydroxyapatite powders, one of which, HAP2, was precipitated abruptly, retaining the amorphous nature longer, and the other one of which, HAP1, was precipitated at a slower rate, more rapidly transitioning to the crystalline structure. Cements were made with four different weight ratios of the two hydroxyapatite components: 100/0, 85/15, 50/50, and 0/100 with respect to HAP1 and HAP2. Both the setting and the release rates measured on two different antibiotics, vancomycin and ciprofloxacin, were controlled using the weight ratio of the two hydroxyapatite components. Various inorganic powder properties were formerly used to control drug release, but here we demonstrate for the first time that the kinetics of the mechanism of formation of a solid compound can be controlled to produce tunable drug release profiles. Specifically, it was found that the longer the precursor calcium phosphate component of the cement retains the amorphous nature of the primary precipitate, the more active it was in terms of speeding up the diffusional release of the adsorbed drug. The setting rate was, in contrast, inversely proportional to the release rate and to the content of this active hydroxyapatite component, HAP2. The empirical release profiles were fitted to a set of equations that could be used to tune the release rate to the therapeutic occasion. All of the cements loaded with vancomycin or ciprofloxacin inhibited the

  4. An investigation of carbon release rate via leachate from an industrial solid waste landfill.

    PubMed

    Kim, Hee Jong; Matsuto, Toshihiko; Tojo, Yasumasa

    2011-06-01

    Long-term behaviour of leachate pollutants is a key factor to estimate time and cost required for the leachate treatment in landfills. Estimating carbon release via leachate can be a good way by which to understand the long-term behaviour, however, most studies have had a timeline of only several months or years. In this study, a release rate of carbon via leachate for 20 years was estimated at an industrial solid waste landfill. The total carbon content in dumped waste was estimated based on combustible contents determined by collecting samples from other industrial landfills and pretreatment facilities, and carbon contents in literature values. Leachate quantity data, which were not recorded for the first ten years, were estimated using a macro-moisture balance model including the effect of snow melt. Because leachate quantity and quality at each site were only measured after leachates were mixed, the quantity at each site was calculated by assuming infiltration rates with and without final cover. Results indicated that less than 2% of total input carbon was released from each site via leachate regardless of landfill age.

  5. Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design.

    PubMed

    Khatun, Sabera; Sutradhar, Kumar B

    2014-01-01

    In recent years natural polymers have been widely used because of their effectiveness and availability over synthetic polymers. In this present investigation matrix tablets of Metformin hydrochloride were formulated using Water hyacinth powder and its rate retardant activity was studied. Tablets were prepared using wet granulation method with 8% starch as granulating agent and 5, 10, 15, 20, 25 and 30% of Water hyacinth powder to the drug. In preformulation study, angle of repose, Carr's Index and Hausner ratio were calculated. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) studies were performed and no interactions were found between drug and excipients. Weight variation, friability, hardness, thickness, diameter, and in vitro release study were performed with the prepared matrix tablets. Dissolution studies were conducted using USP type II apparatus at a speed of 100 rpm at 37°C ± 0.5 temperature for 8 h. Though all the formulations comply with both BP and USP requirements, formulation F-1 (5% of Water hyacinth) was the best fitted formula. The drug release patterns were explained in different kinetic models such as Zero order, First order, Higuchi, Hixson Crowell, and Korsmeyer-Peppas equations. The current investigation implies that Water hyacinth has the potential to be used as a rate-retarding agent in sustained release drug formulations.

  6. Phosphorus release rates from sediments and pollutant characteristics in Han River, Seoul, Korea.

    PubMed

    Kim, Lee-Hyung; Choi, Euiso; Gil, Kyung-Ik; Stenstrom, Michael K

    2004-04-05

    The Han River is 469.7-km long and drains a 26219-km(2) watershed. The sediments in the river are highly polluted due to inputs from upstream tributaries as well as partially treated municipal wastewaters that are discharged to the river. The water quality and strategy for control are important because the river is the primary drinking water supply for the City of Seoul, as well as being a major source for irrigation and industrial water. The Jamsil submerged dam partitions the river to isolate an upstream area for drinking water, but also captures sediments. Samples from four sites were studied to determine sediment pollutant concentrations and phosphorus release rates. Phosphorus tends to desorb from sediments when the concentration of overlying water is less than 1.4 mg/l. Water column P concentrations range from 0.04 to 0.1 mg/l, which suggests that sediments will act as a P source. In a series of batch experiments, P was released at approximately 15-20 mg/m(2)week in the winter (1-5 degrees C) and as much as 90 mg/m(2)week in the summer (20-24 degrees C), and is also a function of pH and dissolved oxygen concentration. The sediment total phosphorus concentration, which averages 833 mg/kg, is evenly distributed among non-apatite-P (33%), apatite-P (32%) and residual-P (34%). An equilibrium model is proposed to describe release rate.

  7. Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design

    PubMed Central

    Khatun, Sabera; Sutradhar, Kumar B.

    2014-01-01

    In recent years natural polymers have been widely used because of their effectiveness and availability over synthetic polymers. In this present investigation matrix tablets of Metformin hydrochloride were formulated using Water hyacinth powder and its rate retardant activity was studied. Tablets were prepared using wet granulation method with 8% starch as granulating agent and 5, 10, 15, 20, 25 and 30% of Water hyacinth powder to the drug. In preformulation study, angle of repose, Carr's Index and Hausner ratio were calculated. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) studies were performed and no interactions were found between drug and excipients. Weight variation, friability, hardness, thickness, diameter, and in vitro release study were performed with the prepared matrix tablets. Dissolution studies were conducted using USP type II apparatus at a speed of 100 rpm at 37°C ± 0.5 temperature for 8 h. Though all the formulations comply with both BP and USP requirements, formulation F-1 (5% of Water hyacinth) was the best fitted formula. The drug release patterns were explained in different kinetic models such as Zero order, First order, Higuchi, Hixson Crowell, and Korsmeyer-Peppas equations. The current investigation implies that Water hyacinth has the potential to be used as a rate-retarding agent in sustained release drug formulations. PMID:24966835

  8. Observed rate of ionization in shaped-charge releases of barium in the ionosphere

    NASA Technical Reports Server (NTRS)

    Hallinan, Thomas J.

    1988-01-01

    Data from 36 Ba shaped-charge releases carried out at an angle of less than 25 deg to the magnetic field, by the technique of Wescott et al. (1972) and Michel (1974), were examined for evidence of a sustained rate of ionization in excess of that attributable to sunlight. In four of the experiments, the time constant for the decay of the neutrals was measured using an ultrasensitive color TV camera and was found to have a value of about 30 sec, consistent with slow (solar) ionization. Although the qualitative appearance of most jets was found to be consistent with a slow process of ionization, some releases produced a thin confined jet that was suggestive of rapid ionization. Two of these jets were analyzed in detail, but no evidence of anomalous ionization was produced. The data obtained in this work agree with the geometrical predictions of the Swift model.

  9. Liquid-Phase Heat-Release Rates of the Systems Hydrazine-Nitric Acid and Unsymmetrical Dimethylhydrazine-Nitric Acid

    NASA Technical Reports Server (NTRS)

    Somogyi, Dezso; Feiler, Charles E.

    1960-01-01

    The initial rates of heat release produced by the reactions of hydrazine and unsymmetrical dimethylhydrazine with nitric acid were determined in a bomb calorimeter under conditions of forced mixing. Fuel-oxidant weight ratio and injection velocity were varied. The rate of heat release apparently depended on the interfacial area between the propellants. Above a narrow range of injection velocities representing a critical amount of interfacial area, the rates reached a maximum and were almost constant with injection velocity. The maximum rate for hydrazine was about 70 percent greater than that for unsymmetrical dimethylhydrazine. The total heat released did not vary with mixture ratio over the range studied.

  10. Measurements of the heat release rate integral in turbulent premixed stagnation flames with particle image velocimetry

    SciTech Connect

    Chen, Yung-Cheng; Kim, Munki; Han, Jeongjae; Yun, Sangwook; Yoon, Youngbin

    2008-08-15

    A new definition of turbulent consumption speed is proposed in this work that is based on the heat release rate integral, rather than the mass burning rate integral. Its detailed derivation and the assumptions involved are discussed in a general context that applies to all properly defined reaction progress variables. The major advantage of the proposed definition is that it does not require the thin-flame assumption, in contrast to previous definitions. Experimental determination of the local turbulent displacement speed, S{sub D}, and the local turbulent consumption speed, S{sub C}, is also demonstrated with the particle image velocimetry technique in three turbulent premixed stagnation flames. The turbulence intensity of these flames is of the same order of the laminar burning velocity. Based on the current data, a model equation for the local mean heat release rate is proposed. The relationship between S{sub D} and S{sub C} is discussed along with a possible modeling approach for the turbulent displacement speed. (author)

  11. Variation of the energy release rate as a crack approaches and passes through an elastic inclusion

    NASA Astrophysics Data System (ADS)

    Li, Rongshun; Chudnovsky, A.

    1993-02-01

    The variation of the energy release rate (ERP) at the tip of a crack penetrating an elastic inclusion is analyzed using an approach involving modeling the random array of microcracks or other defects by an elastic inclusion with effective elastic properties. Computations are carried out using a finite element procedure. The eight-noded isoparametric serendipity element with the shift of the midpoint to the quarter-point is used to simulate the singularity at the crack tip, and the crack growth is accommodated by implementing a mesh regeneration technique. The ERP values were calculated for various crack tip positions which simulate the process of the crack approaching and penetrating the inclusion.

  12. LEAK: A source term generator for evaluating release rates from leaking vessels

    SciTech Connect

    Clinton, J.H.

    1994-09-01

    An interactive computer code for estimating the rate of release of any one of several materials from a leaking tank or broken pipe leading from a tank is presented. It is generally assumed that the material in the tank is liquid. Materials included in the data base are acetonitrile, ammonia, carbon tetrachloride, chlorine, chlorine trifluoride, fluorine, hydrogen fluoride, nitric acid, nitrogen tetroxide, sodium hydroxide, sulfur hexafluoride, sulfuric acid, and uranium hexafluoride. Materials that exist only as liquid and/or vapor over expected ranges of temperature and pressure can easily be added to the data base file. The Fortran source code for LEAK and the data file are included with this report.

  13. Variation of the energy release rate as a crack approaches and passes through an elastic inclusion

    NASA Technical Reports Server (NTRS)

    Li, Rongshun; Chudnovsky, A.

    1993-01-01

    The variation of the energy release rate (ERP) at the tip of a crack penetrating an elastic inclusion is analyzed using an approach involving modeling the random array of microcracks or other defects by an elastic inclusion with effective elastic properties. Computations are carried out using a finite element procedure. The eight-noded isoparametric serendipity element with the shift of the midpoint to the quarter-point is used to simulate the singularity at the crack tip, and the crack growth is accommodated by implementing a mesh regeneration technique. The ERP values were calculated for various crack tip positions which simulate the process of the crack approaching and penetrating the inclusion.

  14. Luteinizing hormone--releasing hormone agonists: a quick reference for prevalence rates of potential adverse effects.

    PubMed

    Walker, Lauren M; Tran, Susan; Robinson, John W

    2013-12-01

    Men with prostate cancer (PCa) frequently undergo androgen deprivation therapy (ADT), typically in the form of a depot injection of luteinizing hormone-releasing hormone agonists (LHRHa). LHRHa are associated with many adverse effects (eg, hot flashes, sexual dysfunction, loss of muscle mass, osteopenia, metabolic syndrome), which drastically impact patient quality of life. This literature review, which includes a comprehensive table documenting prevalence rates, provides a quick reference for health care professionals involved in the care of men undergoing ADT with LHRHa. Primary sources were acquired from PubMed using the search terms "androgen deprivation therapy" and each potentially adverse effect (eg, "androgen deprivation therapy and hot flashes"). Commonly cited review articles were also examined for citations of original studies containing prevalence rates. More than 270 articles were reviewed. In contrast to many existing reviews, rates are cited exclusively from original sources. The prevalence rates, obtained from original sources, suggest that more than half of documented adverse effects are experienced by as many as 40% or more of patients. A critique of the literature is also provided. Although there is a vast literature of both original and review articles on specific adverse effects of LHRHa, the quality of research on prevalence rates for some adverse effects is subpar. Many review articles contain inaccuracies and do not cite original sources. The table of prevalence rates will serve as a quick reference for health care providers when counseling patients and will aid in the development of evidence-based patient education materials.

  15. Effects of Time-Release Caffeine Containing Supplement on Metabolic Rate, Glycerol Concentration and Performance

    PubMed Central

    Gonzalez, Adam M.; Hoffman, Jay R.; Wells, Adam J.; Mangine, Gerald T.; Townsend, Jeremy R.; Jajtner, Adam R.; Wang, Ran; Miramonti, Amelia A.; Pruna, Gabriel J.; LaMonica, Michael B.; Bohner, Jonathan D.; Hoffman, Mattan W.; Oliveira, Leonardo P.; Fukuda, David H.; Fragala, Maren S.; Stout, Jeffrey R.

    2015-01-01

    This study compared caffeine pharmacokinetics, glycerol concentrations, metabolic rate, and performance measures following ingestion of a time-release caffeine containing supplement (TR-CAF) versus a regular caffeine capsule (CAF) and a placebo (PL). Following a double-blind, placebo-controlled, randomized, cross-over design, ten males (25.9 ± 3.2 y) who regularly consume caffeine ingested capsules containing either TR-CAF, CAF, or PL. Blood draws and performance measures occurred at every hour over an 8-hour period. Plasma caffeine concentrations were significantly greater (p < 0.05) in CAF compared to TR-CAF during hours 2-5 and significantly greater (p = 0.042) in TR-CAF compared to CAF at hour 8. There were no significant differences between trials in glycerol concentrations (p = 0.86) or metabolic measures (p = 0.17-0.91). Physical reaction time was significantly improved for CAF at hour 5 (p=0.01) compared to PL. Average upper body reaction time was significantly improved for CAF and TR-CAF during hours 1-4 (p = 0.04 and p = 0.01, respectively) and over the 8-hour period (p = 0.04 and p = 0.001, respectively) compared to PL. Average upper body reaction time was also significantly improved for TR-CAF compared to PL during hours 5-8 (p = 0.004). TR-CAF and CAF showed distinct pharmacokinetics yielding modest effects on reaction time, yet did not alter glycerol concentration, metabolic measures, or other performance measures. Key points Time-release caffeine and regular caffeine showed distinct pharmacokinetics over an 8-hour period following ingestion. Time-release caffeine and regular caffeine yielded modest effects on reaction time over an 8-hour period following ingestion. Time-release caffeine and regular caffeine did not alter glycerol concentration, metabolic measures, or other performance measures over an 8-hour period following ingestion. PMID:25983581

  16. Energy release rates for interfacial cracks in elastic bodies with thin semirigid inclusions

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Viktor

    2017-02-01

    In this paper, we present some rigorous results for an equilibrium problem arising from the study of fiber-reinforced composites. We consider a two-dimensional homogeneous anisotropic linear elastic body containing a thin semirigid inclusion. The semirigid inclusion is an anisotropic thin structure that stretches along one direction and moves like a rigid body possessing both rotational and translatory motion along the perpendicular direction. A pre-existing interfacial crack is subject to nonlinear conditions that do not allow the opposite crack faces to penetrate each other. We focus on a variational approach to modelling the physical phenomenon of equilibrium and to demonstrate that the energy release rate associated with perturbation of the crack along the interface is well defined. A higher regularity result for the displacement field is formulated and proved. Then, taking into account this result, we deduce representations for the energy release rates associated with local translation and self-similar expansion of the crack by means of path-independent energy integrals along smooth contour surrounding one or both crack tips. Finally, some relations between the integrals obtained are discussed briefly.

  17. Evaluating release alternatives for a long-lived bird species under uncertainty about long-term demographic rates

    USGS Publications Warehouse

    Moore, Clinton T.; Converse, Sarah J.; Folk, Martin J.; Runge, Michael C.; Nesbitt, Stephen A.

    2012-01-01

    The release of animals to reestablish an extirpated population is a decision problem that is often attended by considerable uncertainty about the probability of success. Annual releases of captive-reared juvenile Whooping Cranes (Grus americana) were begun in 1993 in central Florida, USA, to establish a breeding, non-migratory population. Over a 12-year period, 286 birds were released, but by 2004, the introduced flock had produced only four wild-fledged birds. Consequently, releases were halted over managers' concerns about the performance of the released flock and uncertainty about the efficacy of further releases. We used data on marked, released birds to develop predictive models for addressing whether releases should be resumed, and if so, under what schedule. To examine the outcome of different release scenarios, we simulated the survival and productivity of individual female birds under a baseline model that recognized age and breeding-class structure and which incorporated empirically estimated stochastic elements. As data on wild-fledged birds from captive-reared parents were sparse, a key uncertainty that confronts release decision-making is whether captive-reared birds and their offspring share the same vital rates. Therefore, we used data on the only population of wild Whooping Cranes in existence to construct two alternatives to the baseline model. The probability of population persistence was highly sensitive to the choice of these three models. Under the baseline model, extirpation of the population was nearly certain under any scenario of resumed releases. In contrast, the model based on estimates from wild birds projected a high probability of persistence under any release scenario, including cessation of releases. Therefore, belief in either of these models suggests that further releases are an ineffective use of resources. In the third model, which simulated a population Allee effect, population persistence was sensitive to the release decision

  18. A smoothed stochastic earthquake rate model considering seismicity and fault moment release for Europe

    NASA Astrophysics Data System (ADS)

    Hiemer, S.; Woessner, J.; Basili, R.; Danciu, L.; Giardini, D.; Wiemer, S.

    2014-08-01

    We present a time-independent gridded earthquake rate forecast for the European region including Turkey. The spatial component of our model is based on kernel density estimation techniques, which we applied to both past earthquake locations and fault moment release on mapped crustal faults and subduction zone interfaces with assigned slip rates. Our forecast relies on the assumption that the locations of past seismicity is a good guide to future seismicity, and that future large-magnitude events occur more likely in the vicinity of known faults. We show that the optimal weighted sum of the corresponding two spatial densities depends on the magnitude range considered. The kernel bandwidths and density weighting function are optimized using retrospective likelihood-based forecast experiments. We computed earthquake activity rates (a- and b-value) of the truncated Gutenberg-Richter distribution separately for crustal and subduction seismicity based on a maximum likelihood approach that considers the spatial and temporal completeness history of the catalogue. The final annual rate of our forecast is purely driven by the maximum likelihood fit of activity rates to the catalogue data, whereas its spatial component incorporates contributions from both earthquake and fault moment-rate densities. Our model constitutes one branch of the earthquake source model logic tree of the 2013 European seismic hazard model released by the EU-FP7 project `Seismic HAzard haRmonization in Europe' (SHARE) and contributes to the assessment of epistemic uncertainties in earthquake activity rates. We performed retrospective and pseudo-prospective likelihood consistency tests to underline the reliability of our model and SHARE's area source model (ASM) using the testing algorithms applied in the collaboratory for the study of earthquake predictability (CSEP). We comparatively tested our model's forecasting skill against the ASM and find a statistically significant better performance for

  19. The Relationship between Toxics Release Inventory Discharges and Mortality Rates in Rural and Urban Areas of the United States

    ERIC Educational Resources Information Center

    Hendryx, Michael; Fedorko, Evan

    2011-01-01

    Background: Potential environmental exposures from chemical manufacturing or industrial sites have not been well studied for rural populations. The current study examines whether chemical releases from facilities monitored through the Toxics Release Inventory (TRI) program are associated with population mortality rates for both rural and urban…

  20. The Effect of Synthetic Brine Constituents on the Rate of Arsenic Release from Arsenopyrite

    NASA Astrophysics Data System (ADS)

    Parthasarathy, H.; Dzombak, D. A.; Karamalidis, A.

    2013-12-01

    Geologic carbon dioxide storage (GCS) in deep saline sedimentary formations is a potential method for mitigating increased levels of atmospheric CO2. Injection of CO2 in those formations may induce dissolution of reservoir minerals. Leakage of CO2-saturated brines and native brines could impact overlying drinking water aquifers by contaminating them with toxic constituents. Of particular concern is the effect of CO2 on the rates of dissolution of arsenic and other toxic metals from reservoir minerals. The most common pure phase arsenic mineral in sedimentary geologic formations is arsenopyrite (FeAsS). Natural brines have high salinities (up to 7M), with high concentrations of Na+, Ca2+, Mg2+ and K+. The focus of this study is to examine the effect of brine components on the dissolution rate of arsenic from arsenopyrite. A small-scale flow-through column system was constructed for this purpose and is being used to measure arsenic release rates from arsenopyrite. Influent solutions of NaCl, CaCl2, and MgCl2 at equal ionic strengths were used to examine the effect of the cationic species. A cleaning procedure to remove prior surface oxidation on the surface of the arsenopyrite particles was also developed. Preliminary results with NaCl and CaCl2 at an ionic strength of 0.011M indicate that the rate of dissolution of arsenic is dependent on the cationic species but independent of ionic strength.

  1. Product release is rate-limiting for catalytic processing by the Dengue virus protease

    PubMed Central

    Shannon, A. E.; Pedroso, M. M.; Chappell, K. J.; Watterson, D.; Liebscher, S.; Kok, W. M.; Fairlie, D. P.; Schenk, G.; Young, P. R.

    2016-01-01

    Dengue Virus (DENV) is the most prevalent global arbovirus, yet despite an increasing burden to health care there are currently no therapeutics available to treat infection. A potential target for antiviral drugs is the two-component viral protease NS2B-NS3pro, which is essential for viral replication. Interactions between the two components have been investigated here by probing the effect on the rate of enzyme catalysis of key mutations in a mobile loop within NS2B that is located at the interface of the two components. Steady-state kinetic assays indicated that the mutations greatly affect catalytic turnover. However, single turnover and fluorescence experiments have revealed that the mutations predominantly affect product release rather than substrate binding. Fluorescence analysis also indicated that the addition of substrate triggers a near-irreversible change in the enzyme conformation that activates the catalytic centre. Based on this mechanistic insight, we propose that residues within the mobile loop of NS2B control product release and present a new target for design of potent Dengue NS2B-NS3 protease inhibitors. PMID:27897196

  2. Endogenous adenosine release is involved in the control of heart rate in rats.

    PubMed

    Jammes, Yves; Joulia, Fabrice; Steinberg, Jean Guillaume; Ravailhe, Sylvie; Delpierre, Stéphane; Condo, Jocelyne; Guieu, Regis; Delliaux, Stéphane

    2015-08-01

    Intravenous (i.v.) injections of adenosine exert marked effects on heart rate (HR) and arterial blood pressure (BP), but the role of an endogenous adenosine release by vagal stimulation has not been evaluated. In anaesthetized rats, we examined HR and BP changes induced by 1 min electrical vagal stimulation in the control condition, and then after i.v. injections of (i) atropine, (ii) propranolol, (iii) caffeine, (iv) 8 cyclopentyl-1,3-dipropylxanthine (DPCPX), or (v) dipyridamole to increase the plasma concentration of adenosine (APC). APC was measured by chromatography in the arterial blood before and at the end of vagal stimulation. The decrease in HR in the controls during vagal stimulation was markedly attenuated, but persisted after i.v. injections of atropine and propranolol. When first administered, DPCPX modestly but significantly reduced the HR response to vagal stimulation, but this disappeared after i.v. caffeine administration. Both the HR and BP responses were significantly accentuated after i.v. injection of dipyridamole. Vagal stimulation induced a significant increase in APC, proportional to the magnitude of HR decrease. Our data suggest that the inhibitory effects of electrical vagal stimulations on HR and BP were partly mediated through the activation of A1 and A2 receptors by an endogenous adenosine release. Our experimental data could help to understand the effects of ischemic preconditioning, which are partially mediated by adenosine.

  3. An analysis of crud contribution to the maximum permissible release rates for reactor spent fuel shipments

    SciTech Connect

    Sandoval, R.P.; Sanders, T.L.; Einziger, R.E.; Malinauskas, A.P.; Mings, W.J.

    1988-01-08

    The Office of Civilian Radioactive Waste Management is sponsoring a program to develop standardized methodologies for evaluating spent fuel source terms and demonstrating compliance of spent fuel shipping packages to the federal containment requirements. An important subtask of the program is the evaluation of the neutron-activated corrosion-product deposits (i.e., ''crud'') on irradiated fuel rod surfaces and the determination of the contribution of these ''crud'' deposits to the total activity available for release from cask containment. During transportation, crud may spall from the fuel rods, disperse and become suspended in the cavity medium (gas or liquid), and could be the major contributor to the total source term. An analysis of all available data on crud deposit activity concentration distributions, composition, spallation properties, particle size distribution, and crud friability was conducted for various light-water-reactor fuels for selected burnups and decay times. Assuming that crud is the only source of activity release, the maximum permissible leakage rates were estimated using these data for seven types of truck and rail shipping casks containing 1-year-cooled and 10-year-cooled spent fuel. The details and results of this analysis are presented in this paper. 2 refs.

  4. Adhesive-Bonded Composite Joint Analysis with Delaminated Surface Ply Using Strain-Energy Release Rate

    NASA Technical Reports Server (NTRS)

    Chadegani, Alireza; Yang, Chihdar; Smeltzer, Stanley S. III

    2012-01-01

    This paper presents an analytical model to determine the strain energy release rate due to an interlaminar crack of the surface ply in adhesively bonded composite joints subjected to axial tension. Single-lap shear-joint standard test specimen geometry with thick bondline is followed for model development. The field equations are formulated by using the first-order shear-deformation theory in laminated plates together with kinematics relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. The system of second-order differential equations is solved to using the symbolic computation tool Maple 9.52 to provide displacements fields. The equivalent forces at the tip of the prescribed interlaminar crack are obtained based on interlaminar stress distributions. The strain energy release rate of the crack is then determined by using the crack closure method. Finite element analyses using the J integral as well as the crack closure method are performed to verify the developed analytical model. It has been shown that the results using the analytical method correlate well with the results from the finite element analyses. An attempt is made to predict the failure loads of the joints based on limited test data from the literature. The effectiveness of the inclusion of bondline thickness is justified when compared with the results obtained from the previous model in which a thin bondline and uniform adhesive stresses through the bondline thickness are assumed.

  5. Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

    SciTech Connect

    Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel; Tansel, Berrin

    2013-09-05

    ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperatures of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.

  6. Fertility Rates in Young Korean Breast Cancer Patients Treated with Gonadotropin-Releasing Hormone and Chemotherapy

    PubMed Central

    Kim, Isaac; Ryu, Jai Min; Paik, Hyun-June; Park, Sungmin; Bae, Soo Youn; Lee, Se Kyung; Yu, Jonghan; Kim, Seok Won; Nam, Seok Jin

    2017-01-01

    Purpose Gonadotropin-releasing hormone (GnRH) agonists have been used with adjuvant chemotherapy to protect ovarian function. However, there are no data on the actual pregnancy rates among young breast cancer patients receiving GnRH agonists and concurrent chemotherapy in Korea. Methods Among patients who underwent surgery from January 2002 to April 2012, premenopausal patients aged between 20 and 40 years were included in the analysis. We retrospectively reviewed clinicopathologic features (e.g., age, obstetric and menstruation history), recurrence, and survival status. The rate of resumption of menstruation was calculated in all patients. In the married group, pregnancy and delivery rates were also recorded. Results Among 101 patients, 19 were lost to follow-up and 82 were eligible for the analysis. Among them, 31 were married, 10 of 51 got married, and 41 remained unmarried through the follow-up period. Among the married patients, 15 became pregnant and gave birth to 19 babies, whereas 26 did not become pregnant. The pregnancy rate in the married group was 50.0% (15/30). Three of 15 pregnancies (20.0%) were multiparous. Most of the delivered babies were healthy and 80.0% of patients had no problems breastfeeding (12/15). More than half the patients in all groups recovered menstrual status within 12 months. Conclusion Fifty percent of young breast cancer patients who attempted pregnancy succeeded in pregnancy after adjuvant chemotherapy and GnRH agonists. Further studies that include control groups are required to confirm whether the use of GnRH agonists improves pregnancy. PMID:28382099

  7. Static and dynamic strain energy release rates in toughened thermosetting composite laminates

    NASA Technical Reports Server (NTRS)

    Cairns, Douglas S.

    1992-01-01

    In this work, the static and dynamic fracture properties of several thermosetting resin based composite laminates are presented. Two classes of materials are explored. These are homogeneous, thermosetting resins and toughened, multi-phase, thermosetting resin systems. Multi-phase resin materials have shown enhancement over homogenous materials with respect to damage resistance. The development of new dynamic tests are presented for composite laminates based on Width Tapered Double Cantilevered Beam (WTDCB) for Mode 1 fracture and the End Notched Flexure (ENF) specimen. The WTDCB sample was loaded via a low inertia, pneumatic cylinder to produce rapid cross-head displacements. A high rate, piezo-electric load cell and an accelerometer were mounted on the specimen. A digital oscilloscope was used for data acquisition. Typical static and dynamic load versus displacement plots are presented. The ENF specimen was impacted in three point bending with an instrumented impact tower. Fracture initiation and propagation energies under static and dynamic conditions were determined analytically and experimentally. The test results for Mode 1 fracture are relatively insensitive to strain rate effects for the laminates tested in this study. The test results from Mode 2 fracture indicate that the toughened systems provide superior fracture initiation and higher resistance to propagation under dynamic conditions. While the static fracture properties of the homogeneous systems may be relatively high, the apparent Mode 2 dynamic critical strain energy release rate drops significantly. The results indicate that static Mode 2 fracture testing is inadequate for determining the fracture performance of composite structures subjected to conditions such as low velocity impact. A good correlation between the basic Mode 2 dynamic fracture properties and the performance is a combined material/structural Compression After Impact (CAI) test is found. These results underscore the importance of

  8. Rates of zinc and trace metal release from dissolving sphalerite at pH 2.0-4.0

    USGS Publications Warehouse

    Stanton, M.R.; Gemery-Hill, P. A.; Shanks, Wayne C.; Taylor, C.D.

    2008-01-01

    High-Fe and low-Fe sphalerite samples were reacted under controlled pH conditions to determine nonoxidative rates of release of Zn and trace metals from the solid-phase. The release (solubilization) of trace metals from dissolving sphalerite to the aqueous phase can be characterized by a kinetic distribution coefficient, (Dtr), which is defined as [(Rtr/X(tr)Sph)/(RZn/X(Zn) Sph)], where R is the trace metal or Zn release rate, and X is the mole fraction of the trace metal or Zn in sphalerite. This coefficient describes the relationship of the sphalerite dissolution rate to the trace metal mole fraction in the solid and its aqueous concentration. The distribution was used to determine some controls on metal release during the dissolution of sphalerite. Departures from the ideal Dtr of 1.0 suggest that some trace metals may be released via different pathways or that other processes (e.g., adsorption, solubility of trace minerals such as galena) affect the observed concentration of metals. Nonoxidative sphalerite dissolution (mediated by H+) is characterized by a "fast" stage in the first 24-30 h, followed by a "slow" stage for the remainder of the reaction. Over the pH range 2.0-4.0, and for similar extent of reaction (reaction time), sphalerite composition, and surface area, the rates of release of Zn, Fe, Cd, Cu, Mn and Pb from sphalerite generally increase with lower pH. Zinc and Fe exhibit the fastest rates of release, Mn and Pb have intermediate rates of release, and Cd and Cu show the slowest rates of release. The largest variations in metal release rates occur at pH 2.0. At pH 3.0 and 4.0, release rates show less variation and appear less dependent on the metal abundance in the solid. For the same extent of reaction (100 h), rates of Zn release range from 1.53 ?? 10-11 to 5.72 ?? 10-10 mol/m2/s; for Fe, the range is from 4.59 ?? 10-13 to 1.99 ?? 10-10 mol/m2/s. Trace metal release rates are generally 1-5 orders of magnitude slower than the Zn or Fe rates

  9. STEADY STATE FLAMMABLE GAS RELEASE RATE CALCULATION AND LOWER FLAMMABILITY LEVEL EVALUATION FOR HANFORD TANK WASTE

    SciTech Connect

    MEACHAM JE

    2008-11-17

    This report assesses the steady state flammability level under off normal ventilation conditions in the tank headspace for 28 double-shell tanks (DST) and 149 single shell-tanks (SST) at the Hanford Site. Flammability was calculated using estimated gas release rates, Le Chatelier's rule, and lower flammability limits of fuels in an air mixture. This revision updates the hydrogen generation rate input data for al1 177 tanks using waste composition information from the Best Basis Inventory Detail Report (data effective as of August 4,2008). Assuming only barometric breathing, the shortest time to reach 25% of the lower flammability limit is 13 days for DSTs (i.e., tank 241-AZ-102) and 36 days for SSTs (i.e., tank 241-B-203). Assuming zero ventilation, the shortest time to reach 25% of the lower flammability limit is 12 days for DSTs (i.e., tank 241-AZ-102) and 34 days for SSTs (i.e., tank 241-B-203).

  10. STEADY STATE FLAMMABLE GAS RELEASE RATE CALCULATION AND LOWER FLAMMABILITY LEVEL EVALUATION FOR HANFORD TANK WASTE

    SciTech Connect

    MEACHAM JE

    2009-10-26

    This report assesses the steady state flammability level under off normal ventilation conditions in the tank headspace for 28 double-shell tanks (DST) and 149 single shell-tanks (SST) at the Hanford Site. Flammability was calculated using estimated gas release rates, Le Chatelier's rule, and lower flammability limits of fuels in an air mixture. This revision updates the hydrogen generation rate input data for all 177 tanks using waste composition information from the Best Basis Inventory Detail Report (data effective as of August 4,2008). Assuming only barometric breathing, the shortest time to reach 25% of the lower flammability limit is 11 days for DSTs (i.e., tank 241-AZ-10l) and 36 days for SSTs (i.e., tank 241-B-203). Assuming zero ventilation, the shortest time to reach 25% of the lower flammability limit is 10 days for DSTs (i.e., tank 241-AZ-101) and 34 days for SSTs (i.e., tank 241-B-203).

  11. Laboratory experiment to determine phosphate release rates from sediments of a formerly oligotrophic lake (Silbersee, Cuxhaven)

    NASA Astrophysics Data System (ADS)

    Elmarami, Hatem; Greskowiak, Janek; Hamann, Enrico; Massmann, Gudrun

    2016-04-01

    The Silbersee is a small, formerly oligotrophic lake in northwestern Germany which still contains rare character species for oligotrophic lakes (Isoëtes lacustris, Littorella uniflora) threatened by eutrophication. It was suspected that the lake sediments and the redox conditions in the hypolimnon play an important role with regard to eutrophication, potentially releasing phosphorus (P) into the water column. This was the motivation to conduct experiments to estimate the release rate of phosphorus into the lake. It had been noted that the P concentrations in the bottom water were higher during summer in the stagnation phase, when conditions turned sulfidic. Eight sediment cores were taken with a Mondsee-corer (manufactured by UWITEC) at different sites of the lake. The thickness of the sediment within the cores ranged from 15cm to 35 cm and were overlying by approximately 40cm of lake water water. The headspace was approximately 10cm. The cores were stored in a fridge first under oxic, then under anoxic conditions as observed in the lake bottom water in the different seasons. Redox conditions were maintained by bubbling with oxygen and nitrogen gas during the respective time periods. During the experiment, the temperature was held constant to match the water temperature measured at the bottom of the lake (~ 7±1°C). Concentrations of total phosphorus (TP) and dissolved phosphorus (DP), iron (Fe) and dissolved oxygen (DO) as well as pH were measured under oxic and anoxic conditions in the water column. The results showed that TP, DP and Fe concentrations were higher under anoxic conditions than under oxic conditions. The observed increase of phosporous in the water column during the anoxic phase was presumably a result of (i) reductive Fe-oxides dissolution and the corresponding loss of sorption sites and (ii) desorption of phosphorous via surface complexation reactions due to pH changes during the experiment.

  12. Determination of Nitrogen, Phosphorus, and Potassium Release Rates of Slow- and Controlled-Release Fertilizers: Single-Laboratory Validation, First Action 2015.15.

    PubMed

    Thiex, Nancy

    2016-01-01

    A previously validated method for the determination of nitrogen release patterns of slow- and controlled-release fertilizers (SRFs and CRFs, respectively) was submitted to the Expert Review Panel (ERP) for Fertilizers for consideration of First Action Official Method(SM) status. The ERP evaluated the single-laboratory validation results and recommended the method for First Action Official Method status and provided recommendations for achieving Final Action. The 180 day soil incubation-column leaching technique was demonstrated to be a robust and reliable method for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and the results were only slightly affected by variations in environmental factors such as microbial activity, soil moisture, temperature, and texture. The release of P and K were also studied, but at fewer replications than for N. Optimization experiments on the accelerated 74 h extraction method indicated that temperature was the only factor found to substantially influence nutrient-release rates from the materials studied, and an optimized extraction profile was established as follows: 2 h at 25°C, 2 h at 50°C, 20 h at 55°C, and 50 h at 60°C.

  13. Effects of changes in cell volume on the rates of glutamine and alanine release from rat skeletal muscle in vitro.

    PubMed

    Parry-Billings, M; Bevan, S J; Opara, E; Newsholme, E A

    1991-06-01

    The effect of changes in cell volume on the rates of release of glutamine and alanine from muscle and on the concentrations of these amino acids in muscle were investigated by using an isolated preparation of rat skeletal muscle incubated in the presence of hypo- and hyper-osmotic media. Changes in cell volume were associated with changes in the rates of release of glutamine and alanine from muscle: incubation in hypo-osmotic medium decreased the rates of release of glutamine and alanine, and incubation in hyperosmotic medium increased these rates. These changes were rapidly reversed by a change in osmoticity of the medium. Despite marked changes in cell volume, the concentrations of these amino acids in muscle were maintained. It is suggested that cell volume may play a role in the regulation of amino acid metabolism in skeletal muscle.

  14. Layered double hydroxides as effective carrier for anticancer drugs and tailoring of release rate through interlayer anions.

    PubMed

    Senapati, Sudipta; Thakur, Ravi; Verma, Shiv Prakash; Duggal, Shivali; Mishra, Durga Prasad; Das, Parimal; Shripathi, T; Kumar, Mohan; Rana, Dipak; Maiti, Pralay

    2016-02-28

    Hydrophobic anticancer drug, raloxifene hydrochloride (RH) is intercalated into a series of magnesium aluminum layered double hydroxides (LDHs) with various charge density anions through ion exchange technique for controlled drug delivery. The particle nature of the LDH in presence of drug is determined through electron microscopy and surface morphology. The release of drug from the RH intercalated LDHs was made very fast or sustained by altering the exchangeable anions followed by the modified Freundlich and parabolic diffusion models. The drug release rate is explained from the interactions between the drug and LDHs along with order-disorder structure of drug intercalated LDHs. Nitrate bound LDH exhibits greater interaction with drug and sustained drug delivery against the loosely interacted phosphate bound LDH-drug, which shows fast release. Cell viability through MTT assay suggests drug intercalated LDHs as better drug delivery vehicle for cancer cell line against poor bioavailability of the pure drug. In vivo study with mice indicates the differential tumor healing which becomes fast for greater drug release system but the body weight index clearly hints at damaged organ in the case of fast release system. Histopathological experiment confirms the damaged liver of the mice treated either with pure drug or phosphate bound LDH-drug, fast release system, vis-à-vis normal liver cell morphology for sluggish drug release system with steady healing rate of tumor. These observations clearly demonstrate that nitrate bound LDH nanoparticle is a potential drug delivery vehicle for anticancer drugs without any side effect.

  15. Evaluation of in vitro release rate and in vivo absorption characteristics of four metoprolol tartrate immediate-release tablet formulations.

    PubMed

    Rekhi, G S; Eddington, N D; Fossler, M J; Schwartz, P; Lesko, L J; Augsburger, L L

    1997-02-01

    The purpose of this investigation was to examine the impact of formulation and process changes on dissolution and bioavailability/bioequivalency of metoprolol tartrate tablets manufactured using a high-shear granulation process. A half-factorial (2(4-1), Res IV) design was undertaken to study the selected formulation and processing variables during scale-up. Levels and ranges for excipients and processing changes studied represented level 2 or greater changes as indicated by the SUPAC-IR Guidance. Blend and tableting properties were evaluated. Changes in sodium starch glycolate and magnesium stearate levels, and the order of addition microcrystalline cellulose (intra- vs. extragranular) were significant only in affecting percent drug released (Q) in 5, 10, and 15 min. Statistical analysis of data showed no significant curvature. No interaction effects were found to be statistically significant. To examine the impact of formulation and processing variables on in vivo absorption, three batches were selected for a bioavailability study based on their dissolution profiles. Subjects received four metoprolol treatments (Lopressor, slow-, medium-, and fast-dissolving formulations) separated by 1 week according to a randomized crossover design. After an overnight fast, subjects were administered one tablet (100 mg), blood samples were collected over 24 hr and plasma samples were analyzed. The formulations were found to be bioequivalent with respect to the log Cmax and log AUC0-infinity. The results of this study suggest that: (i) bioavailability/bioequivalency studies may not be necessary for metoprolol tartrate and perhaps other class 1 drugs after level 2 type changes and (ii) in vitro dissolution tests may be used to show bioequivalence of metoprolol formulations with processing or formulation changes within the specified level 2 ranges for the equipment examined.

  16. The relationship between the instantaneous velocity field and the rate of moment release in the lithosphere

    USGS Publications Warehouse

    Pollitz, F.F.

    2003-01-01

    Instantaneous velocity gradients within the continental lithosphere are often related to the tectonic driving forces. This relationship is direct if the forces are secular, as for the case of loading of a locked section of a subduction interface by the downgoing plate. If the forces are static, as for the case of lateral variations in gravitational potential energy, then velocity gradients can be produced only if the lithosphere has, on average, zero strength. The static force model may be related to the long-term velocity field but not the instantaneous velocity field (typically measured geodetically over a period of several years) because over short time intervals the upper lithosphere behaves elastically. In order to describe both the short- and long-term behaviour of an (elastic) lithosphere-(viscoelastic) asthenosphere system in a self-consistent manner, I construct a deformation model termed the expected interseismic velocity (EIV) model. Assuming that the lithosphere is populated with faults that rupture continually, each with a definite mean recurrence time, and that the Earth is well approximated as a linear elastic-viscoelastic coupled system, I derive a simple relationship between the instantaneous velocity field and the average rate of moment release in the lithosphere. Examples with synthetic fault networks demonstrate that velocity gradients in actively deforming regions may to a large extent be the product of compounded viscoelastic relaxation from past earthquakes on hundreds of faults distributed over large ( ≥106 km2) areas.

  17. The energy release rate of a pressurized crack in soft elastic materials: effects of surface tension and large deformation.

    PubMed

    Liu, Tianshu; Long, Rong; Hui, Chung-Yuen

    2014-10-21

    In this paper we present a theoretical study on how surface tension affects fracture of soft solids. In classical fracture theory, the resistance to fracture is partly attributed to the energy required to create new surfaces. Thus, the energy released to the crack tip must overcome the surface energy in order to propagate a crack. In soft materials, however, surface tension can cause significant deformation and can reduce the energy release rate for crack propagation by resisting the stretch of crack surfaces. We quantify this effect by studying the inflation of a penny-shaped crack in an infinite elastic body with applied pressure. To avoid numerical difficulty caused by singular fields near the crack tip, we derived an expression for the energy release rate which depends on the applied pressure, the surface tension, the inflated crack volume and the deformed crack area. This expression is evaluated using a newly developed finite element method with surface tension elements. Our calculation shows that, when the elasto-capillary number ω ≡ σ/Ea is sufficiently large, where σ is the isotropic surface tension, E is the small strain Young's modulus and a is the initial crack radius, both the energy release rate and the crack opening displacement of an incompressible neo-Hookean solid are significantly reduced by surface tension. For a sufficiently high elasto-capillary number, the energy release rate can be negative for applied pressure less than a critical amount, suggesting that surface tension can cause crack healing in soft elastic materials.

  18. Assessment of survival rates and reproductive success of captive bred milky stork released at Kuala Gula Bird Sanctuary, Perak

    NASA Astrophysics Data System (ADS)

    Faiq, H.; Safie, M. Y.; Shukor, M. N.

    2016-11-01

    A release programme of captive bred Milky Storks was initiated to increase population size in the wild. Population size depends on the survival rate and breeding success of individuals in the population. Among factors that affect survival rate and breeding success are population age class and sex ratio. The main objective of this study was to estimate the survival rate of Mycteria cinerea that has been released in Kuala Gula Bird Sanctuary since 2007. The estimation of the survival rate was done across gender and age class. This study was conducted in 2012 at Kuala Gula Bird Sanctuary. The presence of M. cinerea individuals were recorded at the sanctuary and identified to background information, such as date of birth, gender and date of release. Females of M. cinerea were estimated to have a higher survival rate (30.0%) than male (16.7%). Across gender, each individual was assigned into 4 different age classes, namely less than 1 year, between 1 and 2 years, between 2 and 3 years, and more than 3 years. The survival rate of individuals less than 1 year was about 50%, between 1 and 2 years was 25%, between 2 and 3 years was 9.1%, and more than 3 years was 0%. This study was intended to facilitate future release programmeme on which gender and age class to emphasize.

  19. Flash photolytic release of alcohols from photolabile carbamates or carbonates is rate-limited by decarboxylation of the photoproduct.

    PubMed

    Papageorgiou, George; Barth, Andreas; Corrie, John E T

    2005-02-01

    Flash photolysis of a 7-nitroindolinyl carbamate derivative in neutral aqueous solution rapidly generated a monoalkyl carbonate salt. The rate constant for subsequent decarboxylation of this salt [mono(2-phosphoryloxyethyl) carbonate], determined by rapid scan IR difference spectroscopy, was 0.4 s(-1) at pH 7.0, 20 degrees C. This rate reflects release of the product alcohol upon photolysis of the parent compound. In general, alcohols protected as photolabile carbamate (or carbonate) derivatives will therefore be released too slowly for studies of the kinetics of millisecond time scale biological processes.

  20. Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001

    USGS Publications Warehouse

    Fisher, Lawrence H.; Wood, Tamara M.

    2004-01-01

    Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Aerial release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resuspension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus is slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 mg/L/day (micrograms per liter per day) at pH 8, and 0.9 mg/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance

  1. Diastolic Calcium Release Controls the Beating Rate of Rabbit Sinoatrial Node Cells: Numerical Modeling of the Coupling Process

    PubMed Central

    Maltsev, Victor A.; Vinogradova, Tatiana M.; Bogdanov, Konstantin Y.; Lakatta, Edward G.; Stern, Michael D.

    2004-01-01

    Recent studies employing Ca2+ indicators and confocal microscopy demonstrate substantial local Ca2+ release beneath the cell plasma membrane (subspace) of sinoatrial node cells (SANCs) occurring during diastolic depolarization. Pharmacological and biophysical experiments have suggested that the released Ca2+ interacts with the plasma membrane via the ion current (INaCa) produced by the Na+/Ca2+ exchanger and constitutes an important determinant of the pacemaker rate. This study provides a numerical validation of the functional importance of diastolic Ca2+ release for rate control. The subspace Ca2+ signals in rabbit SANCs were measured by laser confocal microscopy, averaged, and calibrated. The time course of the subspace [Ca2+] displayed both diastolic and systolic components. The diastolic component was mainly due to the local Ca2+ releases; it was numerically approximated and incorporated into a SANC cellular electrophysiology model. The model predicts that the diastolic Ca2+ release strongly interacts with plasma membrane via INaCa and thus controls the phase of the action potential upstroke and ultimately the final action potential rate. PMID:15041695

  2. The surface-forming energy release rate based fracture criterion for elastic-plastic crack propagation

    NASA Astrophysics Data System (ADS)

    Xiao, Si; Wang, He-Ling; Liu, Bin; Hwang, Keh-Chih

    2015-11-01

    The J-integral based criterion is widely used in elastic-plastic fracture mechanics. However, it is not rigorously applicable when plastic unloading appears during crack propagation. One difficulty is that the energy density with plastic unloading in the J-integral cannot be defined unambiguously. In this paper, we alternatively start from the analysis on the power balance, and propose a surface-forming energy release rate (ERR), which represents the energy available for separating the crack surfaces during the crack propagation and excludes the loading-mode-dependent plastic dissipation. Therefore the surface-forming ERR based fracture criterion has wider applicability, including elastic-plastic crack propagation problems. Several formulae are derived for calculating the surface-forming ERR. From the most concise formula, it is interesting to note that the surface-forming ERR can be computed using only the stress and deformation of the current moment, and the definition of the energy density or work density is avoided. When an infinitesimal contour is chosen, the expression can be further simplified. For any fracture behaviors, the surface-forming ERR is proven to be path-independent, and the path-independence of its constituent term, so-called Js-integral, is also investigated. The physical meanings and applicability of the proposed surface-forming ERR, traditional ERR, Js-integral and J-integral are compared and discussed. Besides, we give an interpretation of Rice paradox by comparing the cohesive fracture model and the surface-forming ERR based fracture criterion.

  3. Attraction of agrilus planipennis fairmaire (Coleoptera: Buprestidae) to a volatile pheromone: effects of release rate, host volatile and trap placement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Attraction of emerald ash borer, Agrilus planipennis Fairmaire, to a volatile pheromone was demonstrated in three field experiments using baited green sticky traps. A dose-response curve was generated for male A. planipennis to increasing release rates of (3Z)-dodecen-12-olide, (3Z)-lactone, in com...

  4. Local Ca2+ releases enable rapid heart rates in developing cardiomyocytes

    PubMed Central

    Korhonen, Topi; Rapila, Risto; Ronkainen, Veli-Pekka; Koivumäki, Jussi T; Tavi, Pasi

    2010-01-01

    The ability to generate homogeneous intracellular Ca2+ oscillations at high frequency is the basis of the rhythmic contractions of mammalian cardiac myocytes. While the specific mechanisms and structures enabling homogeneous high-frequency Ca2+ signals in adult cardiomyocytes are well characterized, it is not known how these kind of Ca2+ signals are produced in developing cardiomyocytes. Here we investigated the mechanisms reducing spatial and temporal heterogeneity of cytosolic Ca2+ signals in mouse embryonic ventricular cardiomyocytes. We show that in developing cardiomyocytes the propagating Ca2+ signals are amplified in cytosol by local Ca2+ releases. Local releases are based on regular 3-D sarcoplasmic reticulum (SR) structures containing SR Ca2+ uptake ATPases (SERCA) and Ca2+ release channels (ryanodine receptors, RyRs) at regular intervals throughout the cytosol. By evoking [Ca2+]i-induced Ca2+ sparks, the local release sites promote a 3-fold increase in the cytosolic Ca2+ propagation speed. We further demonstrate by mathematical modelling that without these local release sites the developing cardiomyocytes lose their ability to generate homogeneous global Ca2+ signals at a sufficiently high frequency. The mechanism described here is robust and indispensable for normal mammalian cardiomyocyte function from the first heartbeats during the early embryonic phase till terminal differentiation after birth. These results suggest that local cytosolic Ca2+ releases are indispensable for normal cardiomyocyte development and function of developing heart. PMID:20211983

  5. Local Ca2+ releases enable rapid heart rates in developing cardiomyocytes.

    PubMed

    Korhonen, Topi; Rapila, Risto; Ronkainen, Veli-Pekka; Koivumäki, Jussi T; Tavi, Pasi

    2010-05-01

    The ability to generate homogeneous intracellular Ca(2+) oscillations at high frequency is the basis of the rhythmic contractions of mammalian cardiac myocytes. While the specific mechanisms and structures enabling homogeneous high-frequency Ca(2+) signals in adult cardiomyocytes are well characterized, it is not known how these kind of Ca(2+) signals are produced in developing cardiomyocytes. Here we investigated the mechanisms reducing spatial and temporal heterogeneity of cytosolic Ca(2+) signals in mouse embryonic ventricular cardiomyocytes. We show that in developing cardiomyocytes the propagating Ca(2+) signals are amplified in cytosol by local Ca(2+) releases. Local releases are based on regular 3-D sarcoplasmic reticulum (SR) structures containing SR Ca(2+) uptake ATPases (SERCA) and Ca(2+) release channels (ryanodine receptors, RyRs) at regular intervals throughout the cytosol. By evoking [Ca(2+)](i)-induced Ca(2+) sparks, the local release sites promote a 3-fold increase in the cytosolic Ca(2+) propagation speed. We further demonstrate by mathematical modelling that without these local release sites the developing cardiomyocytes lose their ability to generate homogeneous global Ca(2+) signals at a sufficiently high frequency. The mechanism described here is robust and indispensable for normal mammalian cardiomyocyte function from the first heartbeats during the early embryonic phase till terminal differentiation after birth. These results suggest that local cytosolic Ca(2+) releases are indispensable for normal cardiomyocyte development and function of developing heart.

  6. Controlling the drug release rate from electrospun phospholipid polymer nanofibers with micro-patterned diamond-like carbon (DLC) coating

    NASA Astrophysics Data System (ADS)

    Yoshida, Soki; Hasebe, Terumitsu; Suzuki, Tetsuya; Hotta, Atsushi

    2013-03-01

    An effective way of controlling drug release from polymer fibers coated with thin diamond-like carbon (DLC) film was introduced. It is highly expected that electrospinning will produce polymer fiber and useful for drug delivery systems. The drug release rate should be rather precisely controlled in order to prevent side effects due to the burst drug-release from polymers. Our previous research has already revealed that the micro-patterned DLC could control the drug release rate from biocompatible polymer films. In this study, the drug release profile of the polymer fibers with DLC was investigated. Hydrophilic 2-methacryloyloxyethyl phosphorylcholine (MPC) was selected as a typical biocompatible polymer. It is well known that the MPC polymers show good hemocompatibility and that both MPC and DLC are excellent biocompatible materials with antithrombogenicity. The DLC/MPC composites could therefore be extensively utilized for blood-contacting medical devices. The percentile covered area with patterned DLC on MPC fibers containing drug was varied from 0% (without DLC) to 100% (fully covered). It was found that the drug eluting profiles could be effectively controlled by changing the covered area of micro-patterned DLC coatings on MPC.

  7. The optimal sex pheromone release rate for trapping the codling moth Cydia pomonella (Lepidoptera: Tortricidae) in the field

    PubMed Central

    Liu, Wei; Xu, Jing; Zhang, Runzhi

    2016-01-01

    For successful pest management, codlemone (E, E-8,10-dodecadien-1-ol) is widely used to monitor codling moth. The pheromone release rate is essential for the lure’s attractiveness. The optimal sex pheromone release rate (V0) for trapping codling moth was evaluated during 2013–2014. The overwinter generation V0 was 6.7–33.4 μg wk−1, and moth catches (MCs) were 0.82 ± 0.11 adults/trap/week; MCs for lower (V1) and higher (V2) release rates were 52.4% and 46.3%, respectively, of that for V0. The first generation V0 was 18.4–29.6 μg wk−1, with MCs of 1.45 ± 0.29 adults/week/trap. V1 and V2 MCs were 34.5% and 31.7%, respectively, of those for V0. Combining across generations, the final V0 was 18.4–29.6 μg wk−1, with MCs of 1.07 ± 0.06 adults/week/trap. V1 and V2 MCs were 51.4% and 41.1%, respectively, of that for V0. Overwinter generation emergence was relatively concentrated, requiring a wider V0. Maintaining the release rate at 18.4–29.6 μg wk−1 could optimize the lure’s efficacy; this resulted in the capture of nearly 1.9 and 2.4 times more moths than V1 and V2, respectively. The results also indicate that a dispenser pheromone release rate of 200–300 times that of the female moth can perfectly outcompetes females in the field. PMID:26879373

  8. The optimal sex pheromone release rate for trapping the codling moth Cydia pomonella (Lepidoptera: Tortricidae) in the field.

    PubMed

    Liu, Wei; Xu, Jing; Zhang, Runzhi

    2016-02-16

    For successful pest management, codlemone (E, E-8,10-dodecadien-1-ol) is widely used to monitor codling moth. The pheromone release rate is essential for the lure's attractiveness. The optimal sex pheromone release rate (V0) for trapping codling moth was evaluated during 2013-2014. The overwinter generation V0 was 6.7-33.4 μg wk(-1), and moth catches (MCs) were 0.82 ± 0.11 adults/trap/week; MCs for lower (V1) and higher (V2) release rates were 52.4% and 46.3%, respectively, of that for V0. The first generation V0 was 18.4-29.6 μg wk(-1), with MCs of 1.45 ± 0.29 adults/week/trap. V1 and V2 MCs were 34.5% and 31.7%, respectively, of those for V0. Combining across generations, the final V0 was 18.4-29.6 μg wk(-1), with MCs of 1.07 ± 0.06 adults/week/trap. V1 and V2 MCs were 51.4% and 41.1%, respectively, of that for V0. Overwinter generation emergence was relatively concentrated, requiring a wider V0. Maintaining the release rate at 18.4-29.6 μg wk(-1) could optimize the lure's efficacy; this resulted in the capture of nearly 1.9 and 2.4 times more moths than V1 and V2, respectively. The results also indicate that a dispenser pheromone release rate of 200-300 times that of the female moth can perfectly outcompetes females in the field.

  9. Size-fractionated characterization and quantification of nanoparticle release rates from a consumer spray product containing engineered nanoparticles

    NASA Astrophysics Data System (ADS)

    Hagendorfer, Harald; Lorenz, Christiane; Kaegi, Ralf; Sinnet, Brian; Gehrig, Robert; Goetz, Natalie V.; Scheringer, Martin; Ludwig, Christian; Ulrich, Andrea

    2010-09-01

    This study describes methods developed for reliable quantification of size- and element-specific release of engineered nanoparticles (ENP) from consumer spray products. A modified glove box setup was designed to allow controlled spray experiments in a particle-minimized environment. Time dependence of the particle size distribution in a size range of 10-500 nm and ENP release rates were studied using a scanning mobility particle sizer (SMPS). In parallel, the aerosol was transferred to a size-calibrated electrostatic TEM sampler. The deposited particles were investigated using electron microscopy techniques in combination with image processing software. This approach enables the chemical and morphological characterization as well as quantification of released nanoparticles from a spray product. The differentiation of solid ENP from the released nano-sized droplets was achieved by applying a thermo-desorbing unit. After optimization, the setup was applied to investigate different spray situations using both pump and gas propellant spray dispensers for a commercially available water-based nano-silver spray. The pump spray situation showed no measurable nanoparticle release, whereas in the case of the gas spray, a significant release was observed. From the results it can be assumed that the homogeneously distributed ENP from the original dispersion grow in size and change morphology during and after the spray process but still exist as nanometer particles of size <100 nm. Furthermore, it seems that the release of ENP correlates with the generated aerosol droplet size distribution produced by the spray vessel type used. This is the first study presenting results concerning the release of ENP from spray products.

  10. Dam Breach Release of Non-Cohesive Sediments: Channel Response and Recovery Rates

    NASA Astrophysics Data System (ADS)

    Collins, M. J.; Boardman, G.; Banks, W.; Andrews, M.; Conlon, M.; Dillow, J. J. A.; Gellis, A.; Lowe, S.; McClain, S.; Miller, A. J.; Snyder, N. P.; Wilcock, P. R.

    2014-12-01

    Dam removals featuring unchecked releases of non-cohesive sediments are excellent opportunities to learn more about stream channel response to abrupt increases in bed material supply that can occur deliberately or by natural processes like landslides and volcanic eruptions. Understanding channel response to sediment pulses, including response rates, is essential because human uses of river channels and floodplains are impacted by these events as are aquatic habitats. We had the opportunity to study a dam removal site at the Simkins Dam in Maryland, USA, that shares many important geophysical attributes of another well-studied dam removal in the humid northeast United States [Merrimack Village Dam, New Hampshire; Pearson et al., 2011]. The watershed sizes are the same order of magnitude (102 km2), and at both sites relatively low head dams were removed (~ 3-4 m) and ~60,000 m3 of dominantly sand-sized sediments discharged to low-gradient reaches immediately downstream. Analyzing four years of repeat morphometry and bed sediment grain size surveys at the Simkins site on the Patapsco River, as well as continuous discharge and suspended sediment gaging data, we clearly document a two-phase response in the upstream reach as described by Pearson et al. [2011] for their New Hampshire site and noted at other dam removals [e.g., Major et al., 2012]. In the early phase, approximately 50% of the impounded sediment mass was eroded rapidly over a period of about three months when flows were very modest (Figure 1). After incision to base level and channel widening in the former impoundment, a second phase began when further erosion depended on floods large enough to access impounded sediments more distant from the newly-formed channel. We also found important differences in the upstream responses at the Maryland and New Hampshire sites that appear to be related to valley type (non-glaciated versus glaciated, respectively). Response variances immediately downstream between the

  11. Nanoscale architectural tuning of parylene patch devices to control therapeutic release rates

    NASA Astrophysics Data System (ADS)

    Pierstorff, Erik; Lam, Robert; Ho, Dean

    2008-11-01

    The advent of therapeutic functionalized implant coatings has significantly impacted the medical device field by enabling prolonged device functionality for enhanced patient treatment. Incorporation of drug release from a stable, biocompatible surface is instrumental in decreasing systemic application of toxic therapeutics and increasing the lifespan of implants by the incorporation of antibiotics and anti-inflammatories. In this study, we have developed a parylene C-based device for controlled release of Doxorubicin, an anti-cancer chemotherapy and definitive read-out for preserved drug functionality, and further characterized the parylene deposition condition-dependent tunability of drug release. Drug release is controlled by the deposition of a layer of 20-200 nm thick parylene over the drug layer. This places a porous layer above the Doxorubicin, limiting drug elution based on drug accessibility to solvent and the solvent used. An increase in the thickness of the porous top layer prolongs the elution of active drug from the device from, in the conditions tested, the order of 10 min to the order of 2 d in water and from the order of 10 min to no elution in PBS. Thus, the controlled release of an anti-cancer therapeutic has been achieved via scalably fabricated, parylene C-encapsulated drug delivery devices.

  12. Activation of ras p21 transforming properties associated with an increase in the release rate of bound guanine nucleotide.

    PubMed Central

    Lacal, J C; Aaronson, S A

    1986-01-01

    An Ala-to-Thr substitution at position 59 activates the transforming properties of the p21ras protein without impairment of GTPase activity, a biochemical alteration associated with other activating mutations. To investigate the basis for the transforming properties of the Thr-59 mutant, we characterized guanine nucleotide release. This reaction exhibited a slow rate and stringent temperature requirements. To further dissect the release reaction, we used monoclonal antibodies directed against different epitopes of the p21 molecule. One monoclonal specifically interfered with nucleotide release, while others which recognized different regions of the molecule blocked nucleotide binding. Mutants with the Thr-59 substitution exhibited a three- to ninefold-higher rate of GDP and GTP release than normal p21 or mutants with other activating lesions. This alteration in the Thr-59 mutant would have the effect of increasing its rate of nucleotide exchange. In an intracellular environment with a high GTP/GDP ratio, this would favor the association of GTP with the Thr-59 mutant. Consistent with knowledge of known G-regulatory proteins, these findings support a model in which the p21-GTP complex is the biologically active form of the p21 protein. PMID:3540608

  13. Effects of gonadotropin-releasing hormone administration or a controlled internal drug-releasing insert after timed artificial insemination on pregnancy rates of dairy cows

    PubMed Central

    Jeong, Jae Kwan; Choi, In Soo; Kang, Hyun Gu; Hur, Tai Young

    2016-01-01

    This study investigated the effects of gonadotrophin-releasing hormone (GnRH) administration (Experiment 1) and a controlled internal drug-releasing (CIDR) insert (Experiment 2) after timed artificial insemination (TAI) on the pregnancy rates of dairy cows. In Experiment 1, 569 dairy cows that underwent TAI (day 0) following short-term synchronization with prostaglandin F2α were randomly allocated into two groups: no further treatment (control, n = 307) or injection of 100 µg of gonadorelin on day 5 (GnRH, n = 262). In Experiment 2, 279 dairy cows that underwent TAI (day 0) following Ovsynch were randomly allocated into two groups: no further treatment (control, n = 140) or CIDR insert treatment from days 3.5 to 18 (CIDR, n = 139). The probability of pregnancy following TAI did not differ between the GnRH (34.4%) and control (31.6%, p > 0.05) groups. However, the probability of pregnancy following TAI was higher (odds ratio: 1.74, p < 0.05) in the CIDR group (51.1%) than in the control group (39.3%). Overall, CIDR insert treatment at days 3.5 to 18 increased pregnancy rates relative to non-treated controls, whereas a single GnRH administration on day 5 did not affect the pregnancy outcomes of dairy cows. PMID:27030200

  14. Low effective activation energies for oxygen release from metal oxides: evidence for mass-transfer limits at high heating rates.

    PubMed

    Jian, Guoqiang; Zhou, Lei; Piekiel, Nicholas W; Zachariah, Michael R

    2014-06-06

    Oxygen release from metal oxides at high temperatures is relevant to many thermally activated chemical processes, including chemical-looping combustion, solar thermochemical cycles and energetic thermite reactions. In this study, we evaluated the thermal decomposition of nanosized metal oxides under rapid heating (~10(5) K s(-1)) with time-resolved mass spectrometry. We found that the effective activation-energy values that were obtained using the Flynn-Wall-Ozawa isoconversional method are much lower than the values found at low heating rates, indicating that oxygen transport might be rate-determining at a high heating rate.

  15. Paclitaxel-loaded polymeric microparticles: Quantitative relationships between in vitro drug release rate and in vivo pharmacodynamics

    PubMed Central

    Tsai, Max; Lu, Ze; Wientjes, M. Guillaume; Au, Jessie L.-S.

    2013-01-01

    Intraperitoneal therapy (IP) has demonstrated survival advantages in patients with peritoneal cancers, but has not become a widely practiced standard-of-care in part due to local toxicity and sub-optimal drug delivery. Paclitaxel-loaded, polymeric microparticles were developed to overcome these limitations. The present study evaluated the effects of microparticle properties on paclitaxel release (extent and rate) and in vivo pharmacodynamics. In vitro paclitaxel release from microparticles with varying physical characteristics (i.e., particle size, copolymer viscosity and composition) was evaluated. A method was developed to simulate the dosing rate and cumulative dose released in the peritoneal cavity based on the in vitro release data. The relationship between the simulated drug delivery and treatment outcomes of seven microparticle compositions was studied in mice bearing IP human pancreatic tumors, and compared to that of the intravenous Cremophor micellar paclitaxel solution used off-label in previous IP studies. Paclitaxel release from polymeric microparticles in vitro was multi-phasic; release was greater and more rapid from microparticles with lower polymer viscosities and smaller diameters (e.g., viscosity of 0.17 vs. 0.67 dl/g and diameter of 5–6 vs. 50–60 μm). The simulated drug release in the peritoneal cavity linearly correlated with treatment efficacy in mice (r2>0.8, p<0.001). The smaller microparticles, which distribute more evenly in the peritoneal cavity compared to the large microparticles, showed greater dose efficiency. For single treatment, the microparticles demonstrated up to 2-times longer survival extension and 4-times higher dose efficiency, relative to the paclitaxel/Cremophor micellar solution. Upon repeated dosing, the paclitaxel/Cremophor micellar solution showed cumulative toxicity whereas the microparticle that yielded 2-times longer survival did not display cumulative toxicity. The efficacy of IP therapy depended on both

  16. Strain-energy-release rate analysis of the end-notched flexure specimen using the finite-element method

    NASA Technical Reports Server (NTRS)

    Salpekar, S. A.; Raju, I. S.; Obrien, T. K.

    1987-01-01

    Two-dimensional finite-element analysis of the end-notched flexure specimen was performed using 8-node isoparametric, parabolic elements to evaluate compliance and mode II strain energy release rates, G sub II. The G sub II values were computed using two different techniques: the virtural crack-closure technique (VCCT) and the rate of change of compliance with crack length (compliance derivative method). The analysis was performed for various crack-length-to-semi-span (a/L) ratios ranging from 0.2 to 0.9. Three material systems representing a wide range of material properties were analyzed. The compliance and strain energy release rates of the specimen calculated with the present finite-element analysis agree very well with beam theory equations including transverse shear. The G sub II values calculated using the compliance derivative method compared extremely well with those calculated using the VCCT. The G sub II values obtained by the compliance derivative method using the top or bottom beam deflections agreed closely with each other. The strain energy release rates from a plane-stress analysis were higher than the plane-strain values by only a small percentage, indicating that either assumption may be used in the analysis. The G sub II values for one material system calculated from the finite-element analysis agreed with one solution in the literature and disagreed with the other solution in the literature.

  17. Strain energy release rate analysis of the end-notched flexure specimen using the finite-element method

    NASA Technical Reports Server (NTRS)

    Salpekar, S. A.; Raju, I. S.; O'Brien, T. K.

    1988-01-01

    Two-dimensional finite-element analysis of the end-notched flexure specimen was performed using 8-node isoparametric, parabolic elements to evaluate compliance and mode II strain energy release rates, G sub II. The G sub II values were computed using two different techniques: the virtual crack-closure technique (VCCT) and the rate of change of compliance with crack length (compliance derivative method). The analysis was performed for various crack-length-to-semi-span (a/L) ratios ranging from 0.2 to 0.9. Three material systems representing a wide range of material properties were analyzed. The compliance and strain energy release rates of the specimen calculated with the present finite-element analysis agree very well with beam theory equations including transverse shear. The G sub II values calculated using the compliance derivative method compared extremely well with those calculated using the VCCT. The G sub II values obtained by the compliance derivative method using the top or bottom beam deflections agreed closely with each other. The strain energy release rates from a plane-stress analysis were higher than the plane-strain values by only a small percentage, indicating that either assumption may be used in the analysis. The G sub II values for one material system calculated from the finte-element analysis agreed with one solution in the literature and disagreed with the other solution in the literature.

  18. Effects of the rate of releases from Sam Rayburn Reservoir on the Aeration Capacity of the Angelina River, eastern Texas

    USGS Publications Warehouse

    Rawson, Jack; Goss, Richard L.; Rathbun, Ira G.

    1980-01-01

    A three-phase study was conducted during July and August 1979 to determine the effects of varying release rates through the power-outlet works at Sam Rayburn Reservoir, eastern Texas, on aeration capacity of a 14-mile reach of the Angelina River below Sam Rayburn Dam. The dominant factors that affected the aeration capacity during the study time were time of travel and the dissolved-oxygen deficit of the releases. Aeration was low throughout the study but increased in response to increases in the dissolved-oxygen deficit and the duration of time that the releases were exposed to the atmosphere (time of travel). The average concentration of dissolved oxygen sustained by release of 8,800 cubic feet per second decreased from 5.0 milligrams per liter at a site near the power outlet to 4.8 milligrams per liter at a site about 14 miles downstream; the time of travel averaged about 8 hours. The average concentration of dissolved oxygen in flow sustained by releases of 2,200 cubic feet per second increased from 5.2 to 5.5 milligrams per liter; the time of travel averaged about 20 hours. (USGS)

  19. Controlling the hydration rate of a hydrophilic matrix in the core of an intravaginal ring determines antiretroviral release.

    PubMed

    Teller, Ryan S; Malaspina, David C; Rastogi, Rachna; Clark, Justin T; Szleifer, Igal; Kiser, Patrick F

    2016-02-28

    Intravaginal ring technology is generally limited to releasing low molecular weight species that can diffuse through the ring elastomer. To increase the diversity of drugs that can be delivered from intravaginal rings, we designed an IVR that contains a drug matrix encapsulated in the core of the IVR whereby the mechanism of drug release is uncoupled from the interaction of the drug with the ring elastomer. We call the device a flux controlled pump, and it is comprised of compressed pellets of a mixture of drug and hydroxypropyl cellulose within the hollow core of the ring. The pump orifice size and chemistry of the polymer pellets control the rate of hydration and diffusion of the drug-containing hydroxypropyl cellulose gel from the device. A mechanistic model describing the hydration and diffusion of the hydroxypropyl cellulose matrix is presented. Good agreement between the quantitative model predictions and the experimental studies of drug release was obtained. We achieved controlled release rates of multiple antiretrovirals ranging from μg/d to mg/d by altering the orifice design, drug loading, and mass of pellets loaded in the device. This device could provide an adaptable platform for the vaginal drug delivery of many molecules.

  20. Measurement of copper release rates from antifouling paint under laboratory and in situ conditions: implications for loading estimation to marine water bodies.

    PubMed

    Valkirs, Aldis O; Seligman, Peter F; Haslbeck, Elizabeth; Caso, Joaquin S

    2003-06-01

    The release of biocides, such as copper (Cu), from antifouling (AF) coatings on vessel hulls represents a significant proportion of overall Cu loading in those harbors and estuaries where substantial numbers of small craft or large vessels are berthed. Copper release rates were measured on several self-polishing, tin-free coatings and an ablative Cu reference coating applied to steel panels using three measurement methods. The panels were exposed in natural seawater in San Diego Bay, and release rates were measured both in the laboratory and field over 2 years. Results with the static (20 cm x 30 cm) panels indicated that Cu release rates were initially high (25-65 microg Cu cm(-2)day(-1)), with a large range of values between paint types. Release rates declined to substantially lower rates (8-22 microg cm(-2)day(-1)) with reduced variability within 2 months. Release rates continued to decrease over time for approximately 6 months when relatively constant release rates were observed for most coatings. Over time, relative differences in Cu release rates measured by three exposure methods decreased, with all coatings exhibiting similar behavior toward the end of the study. Lowest overall Cu release rates were observed with the self-polishing experimental paint no. 7 in static-dynamic and in situ treatments. The highest periodic release rates were measured from panels that experienced periods of both static and dynamic exposure (8.7 ms(-1) rotation). The lowest release rates were measured from panels that experienced static, constant depth exposure, and where release rates were evaluated in situ, using a novel diver-deployed measurement system. Results from this in situ technique suggests that it more closely reflects actual Cu release rates on vessel hulls measured with intact natural biofilms under ambient conditions than measurements using standardized laboratory release rate methods. In situ measurements made directly on the AF surface of vessels demonstrated

  1. A theoretical approach to evaluate the release rate of acetaminophen from erosive wax matrix dosage forms.

    PubMed

    Agata, Yasuyoshi; Iwao, Yasunori; Shiino, Kai; Miyagishima, Atsuo; Itai, Shigeru

    2011-07-29

    To predict drug dissolution and understand the mechanisms of drug release from wax matrix dosage forms containing glyceryl monostearate (GM; a wax base), aminoalkyl methacrylate copolymer E (AMCE; a pH-dependent functional polymer), and acetaminophen (APAP; a model drug), we tried to derive a novel mathematical model with respect to erosion and diffusion theory. Our model exhibited good agreement with the whole set of experimentally obtained values pertaining to APAP release at pH 4.0 and pH 6.5. In addition, this model revealed that the eroding speed of wax matrices was strongly influenced by the loading content of AMCE, but not that of APAP, and that the diffusion coefficient increased as APAP loading decreased and AMCE loading increased, thus directly defining the physicochemical properties of erosion and diffusion. Therefore, this model might prove a useful equation for the precise prediction of dissolution and for understanding the mechanisms of drug release from wax matrix dosage forms.

  2. Two-time correlation of heat release rate and spectrum of combustion noise from turbulent premixed flames

    NASA Astrophysics Data System (ADS)

    Liu, Yu

    2015-09-01

    The spectral characteristics of combustion noise are dictated by the temporal correlation of the overall change of heat release rate fluctuations which has not received sufficient attention in prior studies. In this work, the two-time correlation of the volumetric heat release rate fluctuations within the flame brush and its role in modeling combustion noise spectrum are investigated by analyzing direct numerical simulation (DNS) data of turbulent premixed V-flames. This two-time correlation can be well represented by Gaussian-type functions and it captures the slow global variation of the fluctuating heat release rate and hence the low-frequency noise sources of unsteady combustion. The resulting correlation model is applied to predict the far-field noise spectrum from test open flames, and different reference time scales are used to scale this correlation from the DNS data to the test flames. The comparison between predictions and measurements indicates that the correlation models of all reference time scales are capable of reproducing the essential spectral shape including the low- and high-frequency dependencies. Reasonable agreement in the peak frequency, peak sound pressure level, and the Strouhal number scaling of peak frequency is also achieved for two turbulent time scales. A promising convective time scale shows great potential for characterizing the spectral features, yet its predictive capabilities are to be further verified through a longer DNS signal of a bounded flame configuration.

  3. Spatial release from masking improves sound pattern discrimination along a biologically relevant pulse-rate continuum in gray treefrogs

    PubMed Central

    Ward, Jessica L.; Buerkle, Nathan P.; Bee, Mark A.

    2013-01-01

    Frogs form large choruses during the mating season in which males produce loud advertisement calls to attract females and repel rival males. High background noise levels in these social aggregations can impair vocal perception. In humans, spatial release from masking contributes to our ability to understand speech in noisy social groups. Here, we tested the hypothesis that spatial separation between target signals and ‘chorus-shaped noise’ improves the ability of female gray treefrogs (Hyla chrysoscelis) to perform a behavioral discrimination task based on perceiving differences in the pulsatile structure of advertisement calls. We used two-stimulus choice tests to measure phonotaxis (approach toward sound) in response to calls differing in pulse rate along a biologically relevant continuum between conspecific (50 pulses s−1) and heterospecific (20 pulses s−1) calls. Signals were presented in quiet, in colocated noise, and in spatially separated noise. In quiet conditions, females exhibited robust preferences for calls with relatively faster pulse rates more typical of conspecific calls. Behavioral discrimination between calls differing in pulse rate was impaired in the presence of colocated noise but similar between quiet and spatially separated noise conditions. Our results indicate that spatial release from energetic masking facilitates a biologically important temporal discrimination task in frogs. We discuss these results in light of previous work on spatial release from masking in frogs and other animals. PMID:24055623

  4. Effect of geometrical structure on drug release rate of a three-dimensionally perforated porous apatite/collagen composite cement.

    PubMed

    Otsuka, Makoto; Nakagawa, Hidenori; Ito, Atsuo; Higuchi, William I

    2010-01-01

    To improve the biocompatibility, inter-connective pore structure, and drug delivery ability of self-setting apatite/collagen composite cement (ACC), a three-dimensionally perforated porous apatite/collagen composite cement (TPPACC) containing 3% indomethacin (IMC) was obtained in an arranged multi-cross with 20, 40, and 60 stainless steel needlelike male dies, and stored and hardened at 37 degrees C and 100% relative humidity for 24 h. The mean radius of micro-pores of the TPPACC was evaluated to be 0.125 microm by mercury porosimetry. X-ray powder diffraction and FT-IR spectroscopy suggested that TPPACC consisted of carbonated apatite and had a structure similar to that of natural rat bone. The IMC release rates from a TPPACC block containing the drug were measured in simulated body fluid. The rate of release increased with the number of macro-pores that from planar surface matrix systems followed the Higuchi equation. The relationship between the Higuchi constant and surface area of TPPACC showed a straight line with K = 0.2123 and R(2) = 0.9892. These results indicated that the rate of drug release from TPPACC could be controlled by the number of macro-pores for bone cells.

  5. Solvent and viscosity effects on the rate-limiting product release step of glucoamylase during maltose hydrolysis.

    PubMed

    Sierks, M R; Sico, C; Zaw, M

    1997-01-01

    Release of product from the active site is the rate-limiting step in a number of enzymatic reactions, including maltose hydrolysis by glucoamylase (GA). With GA, an enzymatic conformational change has been associated with the product release step. Solvent characteristics such as viscosity can strongly influence protein conformational changes. Here we show that the rate-limiting step of GA has a rather complex dependence on solvent characteristics. Seven different cosolvents were added to the GA/maltose reaction solution. Five of the cosolvents, all having an ethylene glycol base, resulted in an increase in activity at low concentration of cosolvent and variable decreases in activity at higher concentrations. The increase in enzyme activity was dependent on polymer length of the cosolvent; the longer the polymer, the lower the concentration needed. The maximum increase in catalytic activity at 45 degrees C (40-45%) was obtained with the three longest polymers (degree of polymerization from 200 to 8000). A further increase in activity to 60-65% was obtained at 60 degrees C. The linear relationship between ln(kcat) and (viscosity)2 obtained with all the cosolvents provides further evidence that product release is the rate-limiting step in the GA catalytic mechanism. A substantial increase in the turnover rate of GA by addition of relatively small amounts of a cosolvent has potential applications for the food industry where high-fructose corn syrup (HFCS) is one of the primary products produced with GA. Since maltodextrin hydrolysis by GA is by far the slowest step in the production of HFCS, increasing the catalytic rate of GA can substantially reduce the process time.

  6. Myosin MgADP release rate decreases at longer sarcomere length to prolong myosin attachment time in skinned rat myocardium.

    PubMed

    Tanner, Bertrand C W; Breithaupt, Jason J; Awinda, Peter O

    2015-12-15

    Cardiac contractility increases as sarcomere length increases, suggesting that intrinsic molecular mechanisms underlie the Frank-Starling relationship to confer increased cardiac output with greater ventricular filling. The capacity of myosin to bind with actin and generate force in a muscle cell is Ca(2+) regulated by thin-filament proteins and spatially regulated by sarcomere length as thick-to-thin filament overlap varies. One mechanism underlying greater cardiac contractility as sarcomere length increases could involve longer myosin attachment time (ton) due to slowed myosin kinetics at longer sarcomere length. To test this idea, we used stochastic length-perturbation analysis in skinned rat papillary muscle strips to measure ton as [MgATP] varied (0.05-5 mM) at 1.9 and 2.2 μm sarcomere lengths. From this ton-MgATP relationship, we calculated cross-bridge MgADP release rate and MgATP binding rates. As MgATP increased, ton decreased for both sarcomere lengths, but ton was roughly 70% longer for 2.2 vs. 1.9 μm sarcomere length at maximally activated conditions. These ton differences were driven by a slower MgADP release rate at 2.2 μm sarcomere length (41 ± 3 vs. 74 ± 7 s(-1)), since MgATP binding rate was not different between the two sarcomere lengths. At submaximal activation levels near the pCa50 value of the tension-pCa relationship for each sarcomere length, length-dependent increases in ton were roughly 15% longer for 2.2 vs. 1.9 μm sarcomere length. These changes in cross-bridge kinetics could amplify cooperative cross-bridge contributions to force production and thin-filament activation at longer sarcomere length and suggest that length-dependent changes in myosin MgADP release rate may contribute to the Frank-Starling relationship in the heart.

  7. Estimation of (41)Ar activity concentration and release rate from the TRIGA Mark-II research reactor.

    PubMed

    Hoq, M Ajijul; Soner, M A Malek; Rahman, A; Salam, M A; Islam, S M A

    2016-03-01

    The BAEC TRIGA research reactor (BTRR) is the only nuclear reactor in Bangladesh. Bangladesh Atomic Energy Regulatory Authority (BAERA) regulations require that nuclear reactor licensees undertake all reasonable precautions to protect the environment and the health and safety of persons, including identifying, controlling and monitoring the release of nuclear substances to the environment. The primary activation product of interest in terms of airborne release from the reactor is (41)Ar. (41)Ar is a noble gas readily released from the reactor stacks and most has not decayed by the time it moves offsite with normal wind speed. Initially (41)Ar is produced from irradiation of dissolved air in the primary water which eventually transfers into the air in the reactor bay. In this study, the airborne radioisotope (41)Ar generation concentration, ground level concentration and release rate from the BTRR bay region are evaluated theoretically during the normal reactor operation condition by several governing equations. This theoretical calculation eventually minimizes the doubt about radiological safety to determine the radiation level for (41)Ar activity whether it is below the permissible limit or not. Results show that the estimated activity for (41)Ar is well below the maximum permissible concentration limit set by the regulatory body, which is an assurance for the reactor operating personnel and general public. Thus the analysis performed within this paper is so much effective in the sense of ensuring radiological safety for working personnel and the environment.

  8. STEADY STATE FLAMMABLE GAS RELEASE RATE CALCULATION & LOWER FLAMMABILITY LEVEL EVALUATION FOR HANFORD TANK WASTE

    SciTech Connect

    HU, T.A.

    2005-10-27

    Assess the steady-state flammability level at normal and off-normal ventilation conditions. The hydrogen generation rate was calculated for 177 tanks using the rate equation model. Flammability calculations based on hydrogen, ammonia, and methane were performed for 177 tanks for various scenarios.

  9. STEADY STATE FLAMMABLE GAS RELEASE RATE CALCULATION AND LOWER FLAMMABILITY LEVEL EVALUATION FOR HANFORD TANK WASTE

    SciTech Connect

    HU TA

    2009-10-26

    Assess the steady-state flammability level at normal and off-normal ventilation conditions. The hydrogen generation rate was calculated for 177 tanks using the rate equation model. Flammability calculations based on hydrogen, ammonia, and methane were performed for 177 tanks for various scenarios.

  10. Steady State Flammable Gas Release Rate Calculation and Lower Flammability Level Evaluation for Hanford Tank Waste

    SciTech Connect

    HU, T.A.

    2000-04-27

    This work is to assess the steady-state flammability level at normal and off-normal ventilation conditions in the tank dome space for 177 double-shell and single-shell tanks at Hanford. Hydrogen generation rate was calculated for 177 tanks using rate equation model developed recently.

  11. Emission rates and the personal cloud effect associated with particle release from the perihuman environment.

    PubMed

    Licina, D; Tian, Y; Nazaroff, W W

    2016-12-23

    Inhalation exposure to elevated particulate matter levels is correlated with deleterious health and well-being outcomes. Despite growing evidence that identifies humans as sources of coarse airborne particles, the extent to which personal exposures are influenced by particle releases near occupants is unknown. In a controlled chamber, we monitored airborne total particle levels with high temporal and particle-size resolution for a range of simulated occupant activities. We also sampled directly from the subject's breathing zone to characterize exposures. A material-balance model showed that a sitting occupant released 8 million particles/h in the diameter range 1-10 μm. Elevated emissions were associated with increased intensity of upper body movements and with walking. Emissions were correlated with exposure, but not linearly. The personal PM10 exposure increment above the room-average levels was 1.6-13 μg/m(3) during sitting, owing to spatial heterogeneity of particulate matter concentrations, a feature that was absent during walking. The personal cloud was more discernible among larger particles, as would be expected for shedding from skin and clothing. Manipulating papers and clothing fabric was a strong source of airborne particles. An increase in personal exposure was observed owing to particle mass exchange associated with a second room occupant.

  12. Evidence That the Pi Release Event Is the Rate-Limiting Step in the Nitrogenase Catalytic Cycle.

    PubMed

    Yang, Zhi-Yong; Ledbetter, Rhesa; Shaw, Sudipta; Pence, Natasha; Tokmina-Lukaszewska, Monika; Eilers, Brian; Guo, Qingjuan; Pokhrel, Nilisha; Cash, Valerie L; Dean, Dennis R; Antony, Edwin; Bothner, Brian; Peters, John W; Seefeldt, Lance C

    2016-07-05

    Nitrogenase reduction of dinitrogen (N2) to ammonia (NH3) involves a sequence of events that occur upon the transient association of the reduced Fe protein containing two ATP molecules with the MoFe protein that includes electron transfer, ATP hydrolysis, Pi release, and dissociation of the oxidized, ADP-containing Fe protein from the reduced MoFe protein. Numerous kinetic studies using the nonphysiological electron donor dithionite have suggested that the rate-limiting step in this reaction cycle is the dissociation of the Fe protein from the MoFe protein. Here, we have established the rate constants for each of the key steps in the catalytic cycle using the physiological reductant flavodoxin protein in its hydroquinone state. The findings indicate that with this reductant, the rate-limiting step in the reaction cycle is not protein-protein dissociation or reduction of the oxidized Fe protein, but rather events associated with the Pi release step. Further, it is demonstrated that (i) Fe protein transfers only one electron to MoFe protein in each Fe protein cycle coupled with hydrolysis of two ATP molecules, (ii) the oxidized Fe protein is not reduced when bound to MoFe protein, and (iii) the Fe protein interacts with flavodoxin using the same binding interface that is used with the MoFe protein. These findings allow a revision of the rate-limiting step in the nitrogenase Fe protein cycle.

  13. Poverty Rate Hits Lowest Level since 1979 as Unemployment Reaches a 30-Year Low. News Release.

    ERIC Educational Resources Information Center

    Center on Budget and Policy Priorities, Washington, DC.

    This brief presents some U.S. Census figures on poverty and employment patterns for 1999. The percentage of U.S. citizens living in poverty declined to 11.8 percent in 1999, the lowest poverty rate since 1979, as poverty rates for people aged 65 and over, African Americans, Hispanic Americans, and people living in the South fell to all-time lows.…

  14. STEADY STATE FLAMMABLE GAS RELEASE RATE CALCULATION & LOWER FLAMMABILITY LEVEL EVALUATION FOR HANFORD TANK WASTE [SEC 1 & 2

    SciTech Connect

    HU, T.A.

    2003-09-30

    Flammable gases such as hydrogen, ammonia, and methane are observed in the tank dome space of the Hanford Site high-level waste tanks. This report assesses the steady-state flammability level under normal and off-normal ventilation conditions in the tank dome space for 177 double-shell tanks and single-shell tanks at the Hanford Site. The steady-state flammability level was estimated from the gas concentration of the mixture in the dome space using estimated gas release rates, Le Chatelier's rule and lower flammability limits of fuels in an air mixture. A time-dependent equation of gas concentration, which is a function of the gas release and ventilation rates in the dome space, has been developed for both soluble and insoluble gases. With this dynamic model, the time required to reach the specified flammability level at a given ventilation condition can be calculated. In the evaluation, hydrogen generation rates can be calculated for a given tank waste composition and its physical condition (e.g., waste density, waste volume, temperature, etc.) using the empirical rate equation model provided in Empirical Rate Equation Model and Rate Calculations of Hydrogen Generation for Hanford Tank Waste, HNF-3851. The release rate of other insoluble gases and the mass transport properties of the soluble gas can be derived from the observed steady-state gas concentration under normal ventilation conditions. The off-normal ventilation rate is assumed to be natural barometric breathing only. A large body of data is required to do both the hydrogen generation rate calculation and the flammability level evaluation. For tank waste that does not have sample-based data, a statistical-based value from probability distribution regression was used based on data from tanks belonging to a similar waste group. This report (Revision 3) updates the input data of hydrogen generation rates calculation for 177 tanks using the waste composition information in the Best-Basis Inventory Detail

  15. Kinetics of scheelite dissolution in groundwater: defining the release rate of tungsten contamination from a natural source

    NASA Astrophysics Data System (ADS)

    Montgomery, S. D.; Mckibben, M. A.

    2011-12-01

    Tungsten, an emerging contaminant, has no EPA standard for its permissible levels in drinking water. At sites in California, Nevada, and Arizona there may be a correlation between elevated levels of tungsten in drinking water and clusters of childhood acute lymphocytic leukemia (ALL). Developing a better understanding of how tungsten is released from rocks into surface and groundwaters is therefore of growing environmental interest. Knowledge of tungstate ore mineral weathering processes, particularly the rates of dissolution of scheelite (CaWO4) in groundwater, could improve models of how tungsten is released and transported in natural waters. Our research is focusing on experimental determination of the rates and products of tungstate mineral dissolution in synthetic groundwater, as a function of temperature, pH and mineral surface area. The initial rate method is being used to develop rate laws. Batch reactor experiments are conducted within constant temperature circulation baths over a pH range of 2-9. Cleaned scheelite powder with grain diameters of 106-150um is placed between two screens in a sample platform and then placed inside a two liter Teflon vessel filled with synthetic groundwater. Ports on the vessel allow sample extraction, temperature and pH measurement, gas inflow, and water circulation. Aliquots of solution are taken periodically for product analysis by ICP -MS. Changes in mineral surface characteristics are monitored using SEM and EDS methods. Results so far reveal that the dissolution of scheelite is incongruent at both neutral and low pH. Solid tungstic acid forms on scheelite mineral surfaces under acidic conditions, implying that this phase controls the dissolution rate in acidic environments. The influence of dissolved CO2 and resultant calcium carbonate precipitation on the dissolution of scheelite at higher pH is also being investigated. The rate law being developed for scheelite dissolution will be useful in reactive-transport computer

  16. 75 FR 66057 - Waybill Data Released in Three-Benchmark Rail Rate Proceedings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ... be posted to the Board's Web site. ] FOR FURTHER INFORMATION CONTACT: Valerie Quinn at (202) 245-0382. (Assistance for the hearing impaired is available through the Federal Information Relay Service (FIRS) at 1-800-877-8339.) SUPPLEMENTARY INFORMATION: In Simplified Standards for Rail Rate Cases...

  17. Comparison of different water/oil microemulsions containing diclofenac sodium: preparation, characterization, release rate, and skin irritation studies.

    PubMed

    Kantarci, Gülten; Ozgüney, Işik; Karasulu, H Yeşim; Arzik, Sevgi; Güneri, Tamer

    2007-11-02

    The aim of the present study was to make a comparison of the in vitro release rate of diclofenac sodium (DS) from microemulsion (M) vehicles containing soybean oil, nonionic surfactants (Brij 58 and Span 80), and different alcohols (ethanol [E], isopropyl alcohol [I], and propanol [P]) as cosurfactant. The optimum surfactant:cosurfactant (S:CoS) weight ratios and microemulsion areas were detected by the aid of phase diagrams. Three microemulsion formulations were selected, and their physicochemical properties were examined for the pH, viscosity, and conductivity. According to the release rate of DS, M prepared with P showed the significantly highest flux value (0.059 +/- 0.018 mg/cm(2)/h) among all formulations (P < .05). The conductivity results showed that DS-loaded microemulsions have higher conductivity values (18.8-20.2 microsiemens/cm) than unloaded formulations (16.9-17.9 microsiemens/cm), and loading DS into the formulation had no negative effect on system stability. Moreover, viscosity measurements were examined as a function of shear rate, and Newtonian fluid characterization was observed for each microemulsion system. All formulations had appropriate observed pH values varying from 6.70 to 6.85 for topical application. A skin irritation study was performed with microemulsions on human volunteers, and no visible reaction was observed with any of the formulations. In conclusion, M prepared with P may be a more appropriate formulation than the other 2 formulations studied as drug carrier for topical application.

  18. Zero-Order Antibiotic Release from Multilayer Contact Lenses: Nonuniform Drug and Diffusivity Distributions Produce Constant-Rate Drug Delivery.

    PubMed

    Guzman, Gustavo; Es-Haghi, Siamak Shams; Nugay, Turgut; Cakmak, Mukerrem

    2017-02-01

    A novel approach to zero-order constant-rate drug delivery from contact lenses is presented. Quasi-Case II non-Fickian transport is achieved by nonuniform drug and diffusivity distributions within three-layer bimodal amphiphilic conetworks (β-APCNs). The center layer is a highly oxygen permeable β-APCN matrix, which contains the drug and exhibits a high drug diffusivity. The outer β-APCN layers contain no-drug and are loaded with vitamin E, which slows diffusion. In contrast to single-layer neat-polymer and vitamin E-loaded films that display first-order "burst" kinetics, it is demonstrated experimentally and by modeling that the combined effect of nonuniform distribution of drug loading and diffusion constants within the three-layer lens maintains low local drug concentration at the lens-fluid interface and yields zero-order drug delivery. The release rates of topical antibiotics provide constant-rate therapeutic-level delivery with appropriate oxygen permeability for at least 30 h, at which time ≈25% of the drug was released.

  19. Formulation and implementation of a high-order 3-D domain integral method for the extraction of energy release rates

    NASA Astrophysics Data System (ADS)

    Ozer, H.; Duarte, C. A.; Al-Qadi, I. L.

    2012-04-01

    This article presents a three dimensional (3-D) formulation and implementation of a high-order domain integral method for the computation of energy release rate. The method is derived using surface and domain formulations of the J-integral and the weighted residual method. The J-integral along 3-D crack fronts is approximated by high-order Legendre polynomials. The proposed implementation is tailored for the Generalized/eXtended Finite Element Method and can handle discontinuities arbitrarily located within a finite element mesh. The domain integral calculations are based on the same integration elements used for the computation of the stiffness matrix. Discontinuities of the integrands across crack surfaces and across computational element boundaries are fully accounted for. The proposed method is able to deliver smooth approximations and to capture the boundary layer behavior of the J-integral using tetrahedral meshes. Numerical simulations of mode-I and mixed mode benchmark fracture mechanics examples verify expected convergence rates for the computed energy release rates. The results are also in good agreement with other numerical solutions available in the literature.

  20. Metal release rate from AISI 316L stainless steel and pure Fe, Cr and Ni into a synthetic biological medium--a comparison.

    PubMed

    Herting, G; Wallinder, I Odnevall; Leygraf, C

    2008-09-01

    Metal release rates from stainless steel grade 316L were investigated in artificial lysosomal fluid (ALF), simulating a human inflammatory cell response. The main focus was placed on release rates of main alloying elements using graphite furnace atomic absorption spectroscopy, and changes in surface oxide composition by means of X-ray photoelectron spectroscopy. To emphasise that alloys and pure metals possess totally different intrinsic properties, comparative studies were performed on the pure alloying constituents: iron, nickel and chromium. Significant differences in release rates were observed due to the presence of a passive surface film on stainless steel. Iron and nickel were released at rates more than 300 times lower from the 316L alloy compared with the pure metals whereas the release rate of chromium was similar. Iron was preferentially released compared with nickel and chromium. Immersion in ALF resulted in the gradual enrichment of chromium in the surface film, a small increase of nickel, and the reduction of oxidized iron with decreasing release rates of alloy constituents as a result. As expected, released metals from stainless steel grade 316L were neither in proportion to the bulk alloy composition nor to the surface film composition.

  1. Strain energy release rate as a function of temperature and preloading history utilizing the edge delamination fatique test method

    NASA Technical Reports Server (NTRS)

    Zimmerman, Richard S.; Adams, Donald F.

    1989-01-01

    Static laminate and tension-tension fatigue tests of IM7/8551-7 composite materials was performed. The Edge Delamination Test (EDT) was utilized to evaluate the temperature and preloading history effect on the critical strain energy release rate. Static and fatigue testing was performed at room temperature and 180 F (82 C). Three preloading schemes were used to precondition fatigue test specimens prior to performing the normal tension-tension fatigue EDT testing. Computer software was written to perform all fatigue testing while monitoring the dynamic modulus to detect the onset of delamination and record the test information for later retrieval and reduction.

  2. Outpacing the Anthropocene: New Constraints for the Rate of Carbon Release at the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Wright, J. D.; Schaller, M. F.

    2012-12-01

    The Paleocene/Eocene Thermal Maximum (PETM) Carbon Isotope Excursion (CIE) is linked to benthic foraminiferal extinction and excursion taxa in planktonic foraminifera and calcareous nannofossils. Previous studies have used integrated bio-magneto-stratigraphies, cycle counting, and extraterrestrial 3He accumulation rates to produce a range of estimates for the duration of the initial onset of the PETM CIE between 750 years to 30 kyr. Durations for the total release time (onset to initiation of recovery) range from 45 to 95 kyr. Uncertainty in the timing of the onset of the PETM CIE prevents the identification of a causal mechanism, and hence understanding the biological responses. Recent work on the Paleocene/Eocene Marlboro Clay has unveiled the presence of regular couplets (~2 cm) expressed in multiple cores and exposures throughout the Atlantic Coastal Plain. Specifically, the Millville and newly recovered Wilson Lake B cores contain 750 and 660 layers through the CIE, respectively. These couplets have corresponding oxygen stable isotope cycles, arguing for a climatic origin. Orbital and millennial periodicities are far too long to explain the ~750 layers identified in the Millville core. Seasonal insolation is the only regular climate cycle that can plausibly account for the observed δ18O amplitudes (~1‰, with some cycles up to 2‰) and layer counts. Seasonal freshwater input can also augment the cyclic oscillations in δ18O, but the majority of the variability is most plausibly ascribed to temperature. Wilson Lake B and Millville have total δ13C excursions of -5 and -4.5‰ respectively, as well as highly expanded sections of the PETM CIE. In the Millville core, high-resolution, bulk stable isotope records show a 3.5‰ δ13C decrease over 12 layers across the PETM CIE onset. Concomitant with this δ13C decrease is a sharp drop in CaCO3. Decreases in both proxies require a large, sudden release of isotopically light carbon. The couplet chronology indicates

  3. Conditional Release of Forensic Psychiatric Patients Consistent with or Contrary to Behavioral Experts' Recommendations in the Netherlands: Prevalence Rates, Patient Characteristics and Recidivism After Discharge from Conditional Release.

    PubMed

    Nagtegaal, Maria H; Boonmann, Cyril

    2016-03-01

    The present study examined a group of 447 Dutch forensic psychiatric patients on conditional release (CR). After a brief overview of the Dutch CR system for forensic psychiatric patients is presented, two sets of factors were studied: factors associated with behavioral experts' recommendations on CR readiness (prevalence rates of recommendations in contrast to or consistent with the judge's decision on CR, written vs. oral recommendations and consensus among parties); and characteristics of forensic psychiatric patients on CR imposed consistent with or contrary to behavioral experts' recommendations (i.e., demographic variables, psychopathology, judicial background and outcomes of violent behavior). Patients on CR consistent with or contrary to the behavioral experts' recommendations did not differ in demographic background variables and psychopathology. Patients on CR contrary to the behavioral experts' recommendations, however, had more prior convictions, and their index offense more often included a sex offense and a property offense (with or without violence) as compared to patients on CR consistent with the behavioral experts' recommendations. In addition, decisions contrary to the behavioral experts' recommendations were more often reached after a 3-month continuation adjournment and after an appeal. Also, patients on CR contrary to the behavioral experts' recommendations were less often found to have been on trial leave before their CR. Finally, recidivism rates were found to be much higher for those on CR contrary to, as compared with those on CR consistent with the behavioral experts' recommendations. However, when corrected for other well-known static predictors of recidivism, this significant difference was no longer prevalent. The implications for evaluators' CR readiness reports and lessons that may be learned from the Dutch forensic psychiatric CR system are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Sill intrusion driven fluid flow and vent formation in volcanic basins: Modeling rates of volatile release and paleoclimate effects

    NASA Astrophysics Data System (ADS)

    Iyer, Karthik; Schmid, Daniel

    2016-04-01

    Evidence of mass extinction events in conjunction with climate change occur throughout the geological record and may be accompanied by pronounced negative carbon isotope excursions. The processes that trigger such globally destructive changes are still under considerable debate. These include mechanisms such as poisoning from trace metals released during large volcanic eruptions (Vogt, 1972), CO2 released from lava degassing during the formation of Large Igneous Provinces (LIPs) (Courtillot and Renne, 2003) and CH4 release during the destabilization of sub-seafloor methane (Dickens et al., 1995), to name a few. Thermogenic methane derived from contact metamorphism associated with magma emplacement and cooling in sedimentary basins has been recently gaining considerable attention as a potential mechanism that may have triggered global climate events in the past (e.g. Svensen and Jamtveit, 2010). The discovery of hydrothermal vent complexes that are spatially associated with such basins also supports the discharge of greenhouse gases into the atmosphere (e.g. Jamtveit et al., 2004; Planke et al., 2005; Svensen et al., 2006). A previous study that investigated this process using a fluid flow model (Iyer et al., 2013) suggested that although hydrothermal plume formation resulting from sill emplacement may indeed release large quantities of methane at the surface, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative δ13C excursions observed in the fossil record over short time scales observed in the fossil record. Here, we reinvestigate the rates of gas release during sill emplacement in a case study from the Harstad Basin off-shore Norway with a special emphasis on vent formation. The presented study is based on a seismic line that crosses multiple sill structures emplaced around 55 Ma within the Lower Cretaceous sediments. A single well-defined vent complex is interpreted above the termination of the

  5. Calcium dependence of neurotransmitter release and rate of spontaneous vesicle fusions are altered in Drosophila synaptotagmin mutants.

    PubMed Central

    Littleton, J T; Stern, M; Perin, M; Bellen, H J

    1994-01-01

    Since the demonstration that Ca2+ influx into the presynaptic terminal is essential for neurotransmitter release, there has been much speculation about the Ca2+ receptor responsible for initiating exocytosis. Numerous experiments have shown that the protein, or protein complex, binds multiple Ca2+ ions, resides near the site of Ca2+ influx, and has a relatively low affinity for Ca2+. Synaptotagmin is an integral membrane protein of synaptic vesicles that contains two copies of a domain known to be involved in Ca(2+)-dependent membrane interactions. Synaptotagmin has been shown to bind Ca2+ in vitro with a relatively low affinity. In addition, synaptotagmin has been shown to bind indirectly to Ca2+ channels, positioning the protein close to the site of Ca2+ influx. Recently, a negative regulatory role for synaptotagmin has been proposed, in which it functions as a clamp to prevent fusion of synaptic vesicles with the presynaptic membrane. Release of the clamp would allow exocytosis. Here we present genetic and electrophysiological evidence that synaptotagmin forms a multimeric complex that can function as a clamp in vivo. However, upon nerve stimulation and Ca2+ influx, all synaptotagmin mutations dramatically decrease the ability of Ca2+ to promote release, suggesting that synaptotagmin probably plays a key role in activation of synaptic vesicle fusion. This activity cannot simply be attributed to the removal of a barrier to secretion, as we can electrophysiologically separate the increase in rate of spontaneous vesicle fusion from the decrease in evoked response. We also find that some syt mutations, including those that lack the second Ca(2+)-binding domain, decrease the fourth-order dependence of release on Ca2+ by approximately half, consistent with the hypothesis that a synaptotagmin complex functions as a Ca2+ receptor for initiating exocytosis. Images PMID:7971978

  6. Methane emissions and contaminant degradation rates at sites affected by accidental releases of denatured fuel-grade ethanol

    NASA Astrophysics Data System (ADS)

    Sihota, Natasha J.; Mayer, K. Ulrich; Toso, Mark A.; Atwater, Joel F.

    2013-08-01

    The recent increase in the use of denatured fuel-grade ethanol (DFE) has enhanced the probability of its environmental release. Due to the highly labile nature of ethanol (EtOH), it is expected to rapidly biodegrade, increasing the potential for inducing methanogenic conditions in the subsurface. As environmental releases of DFE can be expected to occur at the ground surface or in the vadose zone (e.g., due to surficial spills from rail lines or tanker trucks and leaking underground storage tanks), the potential for methane (CH4) generation at DFE spill sites requires evaluation. An assessment is needed because high CH4 generation rates may lead to CH4 fluxes towards the ground surface, which is of particular concern if spills are located close to human habitation—related to concerns of soil vapor intrusion (SVI). This work demonstrates, for the first time, the measurement of surficial gas release rates at large volume DFE spill sites. Two study sites, near Cambria and Balaton, in MN are investigated. Total carbon emissions at the ground surface (summing carbon dioxide (CO2) and CH4 emissions) are used to quantify depth-integrated DFE degradation rates. Results from both sites demonstrate that substantial CO2 and CH4 emissions do occur—even years after a spill. However, large total carbon fluxes, and CH4 emissions in particular, were restricted to a localized area within the DFE source zone. At the Balaton site, estimates of total DFE carbon losses in the source zone ranged between 5 and 174 μmol m- 2 s- 1, and CH4 effluxes ranged between non-detect and 9 μmol m- 2 s- 1. At the Cambria site estimates of total DFE carbon losses in the source zone ranged between 8 and 500 μmol m- 2 s- 1, and CH4 effluxes ranged between non-detect and 393 μmol m- 2 s- 1. Substantial CH4 accumulation, coupled with oxygen (O2) depletion, measured in samples collected from custom-designed gas collection chambers at the Cambria site suggests that the development of explosion or

  7. Methane emissions and contaminant degradation rates at sites affected by accidental releases of denatured fuel-grade ethanol.

    PubMed

    Sihota, Natasha J; Mayer, K Ulrich; Toso, Mark A; Atwater, Joel F

    2013-08-01

    The recent increase in the use of denatured fuel-grade ethanol (DFE) has enhanced the probability of its environmental release. Due to the highly labile nature of ethanol (EtOH), it is expected to rapidly biodegrade, increasing the potential for inducing methanogenic conditions in the subsurface. As environmental releases of DFE can be expected to occur at the ground surface or in the vadose zone (e.g., due to surficial spills from rail lines or tanker trucks and leaking underground storage tanks), the potential for methane (CH4) generation at DFE spill sites requires evaluation. An assessment is needed because high CH4 generation rates may lead to CH4 fluxes towards the ground surface, which is of particular concern if spills are located close to human habitation-related to concerns of soil vapor intrusion (SVI). This work demonstrates, for the first time, the measurement of surficial gas release rates at large volume DFE spill sites. Two study sites, near Cambria and Balaton, in MN are investigated. Total carbon emissions at the ground surface (summing carbon dioxide (CO2) and CH4 emissions) are used to quantify depth-integrated DFE degradation rates. Results from both sites demonstrate that substantial CO2 and CH4 emissions do occur-even years after a spill. However, large total carbon fluxes, and CH4 emissions in particular, were restricted to a localized area within the DFE source zone. At the Balaton site, estimates of total DFE carbon losses in the source zone ranged between 5 and 174 μmol m(-2) s(-1), and CH4 effluxes ranged between non-detect and 9 μmol m(-2) s(-1). At the Cambria site estimates of total DFE carbon losses in the source zone ranged between 8 and 500 μmol m(-2) s(-1), and CH4 effluxes ranged between non-detect and 393 μmol m(-2) s(-1). Substantial CH4 accumulation, coupled with oxygen (O2) depletion, measured in samples collected from custom-designed gas collection chambers at the Cambria site suggests that the development of explosion

  8. Stretch of contracting cardiac muscle abruptly decreases the rate of phosphate release at high and low calcium.

    PubMed

    Mansfield, Catherine; West, Tim G; Curtin, Nancy A; Ferenczi, Michael A

    2012-07-27

    The contractile performance of the heart is linked to the energy that is available to it. Yet, the heart needs to respond quickly to changing demands. During diastole, the heart fills with blood and the heart chambers expand. Upon activation, contraction of cardiac muscle expels blood into the circulation. Early in systole, parts of the left ventricle are being stretched by incoming blood, before contraction causes shrinking of the ventricle. We explore here the effect of stretch of contracting permeabilized cardiac trabeculae of the rat on the rate of inorganic phosphate (P(i)) release resulting from ATP hydrolysis, using a fluorescent sensor for P(i) with millisecond time resolution. Stretch immediately reduces the rate of P(i) release, an effect observed both at full calcium activation (32 μmol/liter of Ca(2+)), and at a physiological activation level of 1 μmol/liter of Ca(2+). The results suggest that stretch redistributes the actomyosin cross-bridges toward their P(i)-containing state. The redistribution means that a greater fraction of cross-bridges will be poised to rapidly produce a force-generating transition and movement, compared with cross-bridges that have not been subjected to stretch. At the same time stretch modifies the P(i) balance in the cytoplasm, which may act as a cytoplasmic signal for energy turnover.

  9. Statistical correlation of the soil incubation and the accelerated laboratory extraction methods to estimate nitrogen release rates of slow- and controlled-release fertilizers.

    PubMed

    Medina, L Carolina; Sartain, Jerry; Obreza, Thomas; Leary, Emily; Hall, William L; Thiex, Nancy J

    2014-01-01

    Several technologies have been proposed to characterize the nutrient release patterns of enhanced-efficiency fertilizers (EEFs) during the last few decades. These technologies have been developed mainly by manufacturers and are product-specific based on the regulation and analysis of each EEF product. Despite previous efforts to characterize nutrient release of slow-release fertilizer (SRF) and controlled-release fertilizer (CRF) materials, no official method exists to assess their nutrient release patterns. However, the increased production and distribution of EEFs in specialty and nonspecialty markets requires an appropriate method to verify nutrient claims and material performance. Nonlinear regression was used to establish a correlation between the data generated from a 180-day soil incubation-column leaching procedure and 74 h accelerated lab extraction method, and to develop a model that can predict the 180-day nitrogen (N) release curve for a specific SRF and CRF product based on the data from the accelerated laboratory extraction method. Based on the R2 > 0.90 obtained for most materials, results indicated that the data generated from the 74 h accelerated lab extraction method could be used to predict N release from the selected materials during 180 days, including those fertilizers that require biological activity for N release.

  10. Helium release rates and ODH calculations from RHIC magnet cooling line failure

    SciTech Connect

    Liaw, C.J.; Than, Y.; Tuozzolo, J.

    2011-03-28

    A catastrophic failure of the magnet cooling lines, similar to the LHC superconducting bus failure incident, could discharge cold helium into the RHIC tunnel and cause an Oxygen Deficiency Hazard (ODH) problem. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the insulating vacuum volumes and discharging via the reliefs into the RHIC tunnel, had been developed. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces are included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Results, including helium discharge rates, helium inventory loss, and the resulting oxygen concentration in the RHIC tunnel area, are reported. Good agreement had been achieved when comparing the simulation results, a RHIC sector depressurization test measurement, and some simple analytical calculations.

  11. The Rate of Permafrost Carbon Release Under Aerobic and Anaerobic Decomposition

    NASA Astrophysics Data System (ADS)

    Lee, H.; Vogel, J. G.; Schuur, E. A.; Inglett, K. S.

    2008-12-01

    One of the ecological consequences caused by increased temperature in northern ecosystems is permafrost thawing. When ice-rich permafrost thaws, the land surface may develop lakes but could also drain, depending on the soil ice content and topographic position. More than 50% of terrestrial soil carbon is stored in the permafrost region, which may be subjected to faster decomposition due to permafrost thaw. As a result of thaw effects on hydrology, soil organic matter from permafrost may be deposited in an oxic or an anoxic environment after permafrost thaw. We tested how the oxygen status and soil substrate quality affect CO2 and CH4 emissions from permafrost soil by conducting laboratory soil incubation experiment. We measured CO2 emissions from aerobic incubations, and CO2 and CH4 from anaerobic incubations. Soil C to N ratios and enzyme activities (glucosidase, phosphatase, and aminopeptidase) were also analyzed to compare the organic matter quality of permafrost soils from different sites. The mass of C lost after 108 days of aerobic soil incubation ranged 0.06-7.98 mg C gdw-1 for mineral soil layers and 2.21-18.56 mg C gdw-1 for organic soil layers. In the anaerobic incubations, C loss in the form of CO2 emissions was 0.04-4.87 mg C gdw-1 while CH4 emissions were 0.00-0.23 mg C gdw- 1. The total C loss was about 3 times lower for the anaerobic soil incubations compared to the aerobic incubations. The carbon loss from CO2 emissions in aerobic incubation showed a linear relationship with C:N (R2=0.58). Overall, rates of C loss were 4-57 times higher in organic soils than mineral soils, which indicated the importance of substrate quality in the decomposition of permafrost carbon. The initial soil enzyme activities were higher in organic soils as compared to mineral soils for all the enzymes tested. Aminopeptidase activity was linearly correlated with C to N ratio (R2=0.78) and both phosphatase and glucosidase were exponentially correlated with %C (R2

  12. An analysis of crud contribution to the maximum permissible release rates for reactor spent-fuel shipments

    SciTech Connect

    Sandoval, R.P.; Sanders, T.L.; Einziger, R.E.; Malinauskas, A.P.; Mings, W.J.

    1988-01-01

    Through The Cask Systems Development Project Office at the US Department of Energy (DOE) in Idaho, the DOE Office of Civilian Radioactive Waste Management is sponsoring a program at Sandia National Laboratories to develop standardized methodologies for evaluating spent-fuel shipping packages to the federal containment requirements. An important subtask of the program is the evaluation of the neutron-activated corrosion-product deposits (i.e., crud) on irradiated fuel rod surfaces and the determination of the contribution of these crud deposits to the total activity available for release from cask containment. During transportation, cured may spall from the fuel rods, disperse, and become suspended in the cavity medium (gas or liquid) and could be the major contributor to the total source term. An analysis of all available data on crud deposit activity, concentration distributions, composition, spallation properties, particle size distribution, and crud friability was conducted for various light ware reactor fuels for selected burnups and decay items. Assuming that crud is the only source of activity release, the maximum permissible leakage rates were estimated using these data for seven types of truck and rail shipping casks containing 1- and 10-yr-cooled spent fuel. The details and results of this analysis are presented in this paper.

  13. Effect of ethanol, temperature, and gas flow rate on volatile release from aqueous solutions under dynamic headspace dilution conditions.

    PubMed

    Tsachaki, Maroussa; Gady, Anne-Laure; Kalopesas, Michalis; Linforth, Robert S T; Athès, Violaine; Marin, Michele; Taylor, Andrew J

    2008-07-09

    On the basis of a mechanistic model, the overall and liquid mass transfer coefficients of aroma compounds were estimated during aroma release when an inert gas diluted the static headspace over simple ethanol/water solutions (ethanol concentration = 120 mL x L(-1)). Studied for a range of 17 compounds, they were both increased in the ethanol/water solution compared to the water solution, showing a better mass transfer due to the presence of ethanol, additively to partition coefficient variation. Thermal imaging results showed differences in convection of the two systems (water and ethanol/water) arguing for ethanol convection enhancement inside the liquid. The effect of ethanol in the solution on mass transfer coefficients at different temperatures was minor. On the contrary, at different headspace dilution rates, the effect of ethanol in the solution helped to maintain the volatile headspace concentration close to equilibrium concentration, when the headspace was replenished 1-3 times per minute.

  14. A Novel Method for Calculation of Strain Energy Release Rate of Asymmetric Double Cantilever Laminated Composite Beams

    NASA Astrophysics Data System (ADS)

    Shokrieh, M. M.; Zeinedini, A.

    2014-06-01

    In this research, a novel data reduction method for calculation of the strain energy release rate ( SERR) of asymmetric double cantilever beams ( ADCB) is presented. For this purpose the elastic beam theory ( EBT) is modified and the new method is called as the modified elastic beam theory ( MEBT). Also, the ADCB specimens are modeled using ABAQUS/Standard software. Then, the initiation of delamination of ADCB specimens is modeled using the virtual crack closure technique ( VCCT). Furthermore, magnitudes of the SERR for different samples are also calculated by an available data reduction method, called modified beam theory ( MBT). Using the hand lay-up method, different laminated composite samples are manufactured by E-glass/epoxy unidirectional plies. In order to measure the SERR, all samples are tested using an experimental setup. The results determined by the new data reduction method ( MEBT) show good agreements with the results of the VCCT and the MBT.

  15. Angiotensin II and renal prostaglandin release in the dog. Interactions in controlling renal blood flow and glomerular filtration rate.

    PubMed

    Bugge, J F; Stokke, E S

    1994-04-01

    The relationship between angiotensin II and renal prostaglandins, and their interactions in controlling renal blood flow (RBF) and glomerular filtration rate (GFR) were investigated in 18 anaesthetized dogs with acutely denervated kidneys. Intrarenal angiotensin II infusion increased renal PGE2 release (veno-arterial concentration difference times renal plasma flow) from 1.7 +/- 0.9 to 9.1 +/- 0.4 and 6-keto-PGF1 alpha release from 0.1 +/- 0.1 to 5.3 +/- 2.1 pmol min-1. An angiotensin II induced reduction in RBF of 20% did not measurably change GFR whereas a 30% reduction reduced GFR by 18 +/- 8%. Blockade of prostaglandin synthesis approximately doubled the vasoconstrictory action of angiotensin II, and all reductions in RBF were accompanied by parallel reductions in GFR. When prostaglandin release was stimulated by infusion of arachidonic acid (46.8 +/- 13.3 and 15.9 +/- 5.4 pmol min-1 for PGE2, and 6-keto-PGF1 alpha, respectively), angiotensin II did not change prostaglandin release, but had similar effects on the relationship between RBF and GFR as during control. In an ureteral occlusion model with stopped glomerular filtration measurements of ureteral pressure and intrarenal venous pressure permitted calculations of afferent and efferent vascular resistances. Until RBF was reduced by 25-30% angiotensin II increased both afferent and efferent resistances almost equally, keeping the ureteral pressure constant. At greater reductions in RBF, afferent resistance increased more than the efferent leading to reductions in ureteral pressure. This pattern was not changed by blockade of prostaglandin synthesis indicating no influence of prostaglandins on the distribution of afferent and efferent vascular resistances during angiotensin II infusion. In this ureteral occlusion model glomerular effects of angiotensin II will not be detected, and it might well be that the shift from an effect predominantly on RBF to a combined effect on both RBF and GFR induced by inhibition

  16. Enhanced bioconversion rate and released substrate inhibition in (R)-phenylephrine whole-cell bioconversion via partial acetone treatment.

    PubMed

    Kan, Shu-Chen; Zang, Chi-Zong; Yeh, Chiung-Wen; Chang, Wei-Feng; Lin, Chia-Chi; Hung, Tzu-Hsiang; Shieh, Chwen-Jen; Liu, Yung-Chuan

    2016-05-01

    An approach was developed to enhance the efficiency for the bioconversion of 1-(3-hydroxyphenyl)-2-(methyamino)-ethanone to (R)-phenylephrine. The strain Serratia marcescens N10612, giving the benefit of 99% enantiomeric excess in (R)-PE conversion, was used. The fermentation was devised to harvest cells with high hydrophobic prodigiosin content inside the cells. Then, the partial acetone extraction was applied to remove prodigiosin from the cells. The treatment was found to increase the cells conversion rate without loss of the cells NADPH redox system. When using 50% (v/v) acetone for 5min, the processed cells can give a specific conversion rate of 16.03μmol/h/g-cells. As compared the treated cells with cells under the basal medium, the maximum reaction rate (Vmax) increased from 6.69 to 10.27 (μmol/h/g-cells), the dissociation constant (Km) decreased from 0.236 to 0.167mM and the substrate inhibition constant (KSi) increased from 0.073 to 1.521mM. The 20-fold increase in substrate inhibition constant referred to a great release from the substrate inhibition for the use of S. marcescens N10612 in the bioconversion, which would greatly benefit the bioconversion to be industrialized.

  17. Changes in cortisol release and heart rate and heart rate variability during the initial training of 3-year-old sport horses.

    PubMed

    Schmidt, Alice; Aurich, Jörg; Möstl, Erich; Müller, Jürgen; Aurich, Christine

    2010-09-01

    Based on cortisol release, a variety of situations to which domestic horses are exposed have been classified as stressors but studies on the stress during equestrian training are limited. In the present study, Warmblood stallions (n=9) and mares (n=7) were followed through a 9 respective 12-week initial training program in order to determine potentially stressful training steps. Salivary cortisol concentrations, beat-to-beat (RR) interval and heart rate variability (HRV) were determined. The HRV variables standard deviation of the RR interval (SDRR), RMSSD (root mean square of successive RR differences) and the geometric means standard deviation 1 (SD1) and 2 (SD2) were calculated. Nearly each training unit was associated with an increase in salivary cortisol concentrations (p<0.01). Cortisol release varied between training units and occasionally was more pronounced in mares than in stallions (p<0.05). The RR interval decreased slightly in response to lunging before mounting of the rider. A pronounced decrease occurred when the rider was mounting, but before the horse showed physical activity (p<0.001). The HRV variables SDRR, RMSSD and SD1 decreased in response to training and lowest values were reached during mounting of a rider (p<0.001). Thereafter RR interval and HRV variables increased again. In contrast, SD2 increased with the beginning of lunging (p<0.05) and no changes in response to mounting were detectable. In conclusion, initial training is a stressor for horses. The most pronounced reaction occurred in response to mounting by a rider, a situation resembling a potentially lethal threat under natural conditions.

  18. Effects of pH, Temperature, Dissolved Oxygen, and Flow Rate on Phosphorus Release Processes at the Sediment and Water Interface in Storm Sewer

    PubMed Central

    Li, Haiyan; Li, Mingyi; Zhang, Xiaoran

    2013-01-01

    The effects of pH, temperature, dissolved oxygen (DO), and flow rate on the phosphorus (P) release processes at the sediment and water interface in rainwater pipes were investigated. The sampling was conducted in a residential storm sewer of North Li Shi Road in Xi Cheng District of Beijing on August 3, 2011. The release rate of P increased with the increase of pH from 8 to 10. High temperature is favorable for the release of P. The concentration of total phosphorus (TP) in the overlying water increased as the concentration of DO decreased. With the increase of flow rate from 0.7 m s−1 to 1.1 m s−1, the concentration of TP in the overlying water increased and then tends to be stable. Among all the factors examined in the present study, the flow rate is the primary influence factor on P release. The cumulative amount of P release increased with the process of pipeline runoff in the rainfall events with high intensities and shorter durations. Feasible measures such as best management practices and low-impact development can be conducted to control the P release on urban sediments by slowing down the flow rate. PMID:24349823

  19. The sludge loading rate regulates the growth and release of heterotrophic bacteria resistant to six types of antibiotics in wastewater activated sludge.

    PubMed

    Yuan, Qing-Bin; Guo, Mei-Ting; Yang, Jian

    2015-01-01

    Wastewater treatment plants are considered as hot reservoirs of antimicrobial resistance. However, the fates of antibiotic-resistant bacteria during biological treatment processes and relevant influencing factors have not been fully understood. This study evaluated the effects of the sludge loading rate on the growth and release of six kinds of antibiotic-resistant bacteria in an activated sludge system. The results indicated that higher sludge loading rates amplified the growth of all six types of antibiotic resistant bacteria. The release of most antibiotic-resistant bacteria through both the effluent and biosolids was amplified with increased sludge loading rate. Biosolids were the main pattern for all antibiotic-resistant bacteria release in an activated sludge system, which was determined primarily by their growth in the activated sludge. A higher sludge loading rate reactor tended to retain more antibiotic resistance. An activated sludge system with lower sludge loading rates was considered more conducive to the control of antibiotic resistance.

  20. Xylitol vs glucose: Effect on the rate of gastric emptying and motilin, insulin, and gastric inhibitory polypeptide release

    SciTech Connect

    Salminen, E.K.; Salminen, S.J.; Porkka, L.; Kwasowski, P.; Marks, V.; Koivistoinen, P.E.

    1989-06-01

    The effect of xylitol and glucose on the rate of gastric emptying and intestinal transit and on motilin, gastric inhibitory polypeptide (GIP), and insulin release were studied in human volunteers. A single oral dose of 200 mL water containing 30 g glucose or 30 g xylitol, mixed with a /sup 99m/technetium-tin (99mTc-Sn) colloid, was used. Similar dosing without the label was used in motilin, GIP, and insulin studies. Xylitol decreased the rate of gastric emptying but concomitantly accelerated intestinal transit compared with glucose. The half-times for gastric emptying were 77.5 +/- 4.6 and 39.8 +/- 3.4 min after ingestion of xylitol and glucose solutions, respectively. Glucose suppressed motilin and stimulated GIP secretion; xylitol stimulated motilin secretion but had no effect on GIP, which is currently the main candidate for the role of enterogastrone. The accelerated intestinal transit and increase in plasma motilin observed after xylitol ingestion were thought to be causally related to the diarrhea and gastrointestinal discomfort produced by it.

  1. Ca2+-induced Ca2+ Release Phenomena in Mammalian Sympathetic Neurons Are Critically Dependent on the Rate of Rise of Trigger Ca2+

    PubMed Central

    Hernández-Cruz, Arturo; Escobar, Ariel L.; Jiménez, Nicolás

    1997-01-01

    The role of ryanodine-sensitive intracellular Ca2+ stores present in nonmuscular cells is not yet completely understood. Here we examine the physiological parameters determining the dynamics of caffeine-induced Ca2+ release in individual fura-2–loaded sympathetic neurons. Two ryanodine-sensitive release components were distinguished: an early, transient release (TR) and a delayed, persistent release (PR). The TR component shows refractoriness, depends on the filling status of the store, and requires caffeine concentrations ≥10 mM. Furthermore, it is selectively suppressed by tetracaine and intracellular BAPTA, which interfere with Ca2+-mediated feedback loops, suggesting that it constitutes a Ca2+-induced Ca2+-release phenomenon. The dynamics of release is markedly affected when Sr2+ substitutes for Ca2+, indicating that Sr2+ release may operate with lower feedback gain than Ca2+ release. Our data indicate that when the initial release occurs at an adequately fast rate, Ca2+ triggers further release, producing a regenerative response, which is interrupted by depletion of releasable Ca2+ and Ca2+-dependent inactivation. A compartmentalized linear diffusion model can reproduce caffeine responses: When the Ca2+ reservoir is full, the rapid initial Ca2+ rise determines a faster occupation of the ryanodine receptor Ca2+ activation site giving rise to a regenerative release. With the store only partially loaded, the slower initial Ca2+ rise allows the inactivating site of the release channel to become occupied nearly as quickly as the activating site, thereby suppressing the initial fast release. The PR component is less dependent on the store's Ca2+ content. This study suggests that transmembrane Ca2+ influx in rat sympathetic neurons does not evoke widespread amplification by CICR because of its inability to raise [Ca2+] near the Ca2+ release channels sufficiently fast to overcome their Ca2+-dependent inactivation. Conversely, caffeine-induced Ca2+ release can

  2. Pregnancy rates to timed artificial insemination in dairy cows treated with gonadotropin-releasing hormone or porcine luteinizing hormone.

    PubMed

    Colazo, M G; Gordon, M B; Rajamahendran, R; Mapletoft, R J; Ambrose, D J

    2009-07-15

    We compared the effects of porcine luteinizing hormone (pLH) versus gonadotropin-releasing hormone (GnRH) on ovulatory response and pregnancy rate after timed artificial insemination (TAI) in 605 lactating dairy cows. Cows (mean+/-SEM: 2.4+/-0.08 lactations, 109.0+/-2.5 d in milk, and 2.8+/-0.02 body condition score) at three locations were assigned to receive, in a 2x2 factorial design, either 100 microg GnRH or 25mg pLH im on Day 0, 500 microg cloprostenol (PGF) on Day 7, and GnRH or pLH on Day 9, with TAI 14 to 18h later. Ultrasonographic examinations were performed in a subset of cows on Days 0, 7, 10, and 11 to determine ovulations, presence of corpus luteum, and follicle diameter and in all cows 32 d after TAI for pregnancy determination. In 35 cows, plasma progesterone concentrations were determined 0, 3, 4, 5, 6, 7, and 12 d after ovulation. The proportion of noncyclic cows and cows with ovarian cysts on Day 0 were 12% and 6%, respectively. Ovulatory response to first treatment was 62% versus 44% for pLH and GnRH and 78% versus 50% for noncyclic and cyclic cows (P<0.01). Location, ovulatory response to first pLH or GnRH, cyclic status, presence of an ovarian cyst, and preovulatory follicle size did not affect pregnancy rate. Plasma progesterone concentrations after TAI did not differ among treatments. Pregnancy rate to TAI was greater (P<0.01) in the GnRH/PGF/pLH group (42%) than in the other three groups (28%, 30%, and 26% for GnRH/PGF/GnRH, pLH/PGF/GnRH, and pLH/PGF/pLH, respectively). Although only 3% of cows given pLH in lieu of GnRH on Day 9 lost their embryo versus 7% in those subjected to a conventional TAI using two GnRH treatments, the difference was not statistically significant. In summary, pLH treatment on Day 0 increased ovulatory response but not pregnancy rate. Cows treated with GnRH/PGF/pLH had the highest pregnancy rate to TAI, but progesterone concentrations after TAI were not increased. In addition, preovulatory follicle diameter did not

  3. Partial fuel stratification to control HCCI heat release rates : fuel composition and other factors affecting pre-ignition reactions of two-stage ignition fuels.

    SciTech Connect

    Dec, John E.; Sjoberg, Carl-Magnus G.; Cannella, William; Yang, Yi; Dronniou, Nicolas

    2010-11-01

    Homogeneous charge compression ignition (HCCI) combustion with fully premixed charge is severely limited at high-load operation due to the rapid pressure-rise rates (PRR) which can lead to engine knock and potential engine damage. Recent studies have shown that two-stage ignition fuels possess a significant potential to reduce the combustion heat release rate, thus enabling higher load without knock.

  4. Community partnering as a tool for improving live release rate in animal shelters in the United States.

    PubMed

    Weiss, Emily; Patronek, Gary; Slater, Margaret; Garrison, Laurie; Medicus, Karen

    2013-01-01

    Collaboration among all shelters and nonhuman animal welfare groups within a community along with the transparent, shared reporting of uniform data have been promoted as effective ways to increase the number of animals' lives saved. This article summarizes the shelter intakes, outcomes, and live release rate (LRR) from 6 geographically diverse communities participating in the American Society for the Prevention of Cruelty to Animals Partnership program for 5 years (2007-2011). This program is both a grant program and a coaching program that works to focus the community partners on a data-driven goal using standardized definitions and metrics. There was improvement in LRR in all communities over time regardless of intake numbers, human population, or mix of dogs/puppies and cats/kittens entering shelters. Averaged across all communities over the 5-year period, there was an overall improvement in LRR of 62%. Within individual communities, the degree of improvement ranged from 18% to 96%. This improvement in LRR was accomplished through a wide variety of programs in each community based on resources and interests during the time period.

  5. A Method for Calculating Strain Energy Release Rates in Preliminary Design of Composite Skin/Stringer Debonding Under Multi-Axial Loading

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Minguet, Pierre J.; OBrien, T. Kevin

    1999-01-01

    Three simple procedures were developed to determine strain energy release rates, G, in composite skin/stringer specimens for various combinations of unaxial and biaxial (in-plane/out-of-plane) loading conditions. These procedures may be used for parametric design studies in such a way that only a few finite element computations will be necessary for a study of many load combinations. The results were compared with mixed mode strain energy release rates calculated directly from nonlinear two-dimensional plane-strain finite element analyses using the virtual crack closure technique. The first procedure involved solving three unknown parameters needed to determine the energy release rates. Good agreement was obtained when the external loads were used in the expression derived. This superposition technique was only applicable if the structure exhibits a linear load/deflection behavior. Consequently, a second technique was derived which was applicable in the case of nonlinear load/deformation behavior. The technique involved calculating six unknown parameters from a set of six simultaneous linear equations with data from six nonlinear analyses to determine the energy release rates. This procedure was not time efficient, and hence, less appealing. A third procedure was developed to calculate mixed mode energy release rates as a function of delamination lengths. This procedure required only one nonlinear finite element analysis of the specimen with a single delamination length to obtain a reference solution for the energy release rates and the scale factors. The delamination was extended in three separate linear models of the local area in the vicinity of the delamination subjected to unit loads to obtain the distribution of G with delamination lengths. This set of sub-problems was Although additional modeling effort is required to create the sub- models, this local technique is efficient for parametric studies.

  6. Effect of binders on the release rates of direct molded verapamil tablets using twin-screw extruder in melt granulation.

    PubMed

    Tan, David Cheng Thiam; Chin, William Wei Lim; Tan, En Hui; Hong, Shiqi; Gu, Wei; Gokhale, Rajeev

    2014-03-10

    Conventional manufacturing of pharmaceutical tablets often involves single processes such as blending, granulation, milling and direct compression. A process that minimizes and incorporates all these in a single continuous step is desirable. The concept of omitting milling step followed by direct-molding of tablets utilizing a twin-screw extruder in a melt granulation process using thermoplastic binders was explored. The objective of this study was to investigate the effect of combining hydrophilic binder (HPMC K4M, PEO 1M), and hydrophobic binder (Compritol® ATO 888, Precirol® ATO 5) on the release profiles of direct-molded tablets and direct-compressed tablets from milled extrudates using a quality-by-design approach. It was identified that hydrophilic binder type and process significantly affects (p=0.005) the release profiles of verapamil. Moreover, two-way interaction analysis demonstrated that the combination of process with type of hydrophilic polymer (p=0.028) and the type of hydrophilic polymer with polymer ratio (p=0.033) significantly affected the release profiles. The formulation release kinetics correlated to Higuchi release model and the mechanism correlated to a non-Fickian release mechanism. The results of the present study indicated that direct-molded tablets with different release profiles can be manufactured without milling process and through a continuous melt granulation using twin-screw extruder with appropriate thermoplastic binder ratio.

  7. Cosmogenic 3He production rates revisited from evidences of grain size dependent release of matrix-sited helium

    USGS Publications Warehouse

    Blard, P.-H.; Pik, R.; Lave, J.; Bourles, D.; Burnard, P.G.; Yokochi, R.; Marty, B.; Trusdell, F.

    2006-01-01

    Measurements of the cosmogenic 3He (3Hec) content of various size aliquots of exposed olivines show that the fine fraction (<140 μm) has 3Hec concentrations between 14 and 100% lower than that of the coarse fractions (0.14–1 mm). Such differences attest to a grain size dependent partial release of 3Hec from the phenocrysts matrix during the preliminary in vacuo crushing. This result might have important implications since most 3Hec measurements have used for ∼20 yr a standard routine based on the fusion of bulk powdered phenocrysts, whatever their grain size. A suite of new data obtained from coarse olivine grains yielded a mean Sea Level High Latitude 3Hec production rate (SLHL P3) of 128±5 and 136±6 at. g−1 yr−1, depending on the scaling factors used. This new value, which is ∼15% higher than previously published rates, is obtained from 5 ropy flow surfaces of Mt Etna (38°N) and Hawaiian (19°N) volcanoes, at elevations between sea level and 870 m and ranging in age from 1.47±0.05 to 149±23 ka according to independent 14C or K/Ar dating. 3He loss during the crushing step might account for the discrepancy between the standard reference value of 110–115 at. g−1 y−1 and the higher SLHL P3 proposed here. More generally, removal of the powdered fraction before fusion is an important point to consider in further studies in order to avoid any 3Hec systematic underestimates.An altitudinal section has also been sampled on the ropy surface of a ∼1500 yr single flow of Mauna Loa (19°N) which allowed a new empirical atmospheric attenuation length of 149±22 g cm−2 to be documented for 3Hec in olivines between 2400 and 4000 m elevations.

  8. Pregnancy rate in women with adenomyosis undergoing fresh or frozen embryo transfer cycles following gonadotropin-releasing hormone agonist treatment

    PubMed Central

    Choi, Min Hye; Yang, Kwang Moon; Song, In Ok

    2016-01-01

    Objective To determine the preferred regimen for women with adenomyosis undergoing in vitro fertilization (IVF), we compared the IVF outcomes of fresh embryo transfer (ET) cycles with or without gonadotropin-releasing hormone (GnRH) agonist pretreatment and of frozen-thawed embryo transfer (FET) cycles following GnRH agonist treatment. Methods This retrospective study included 241 IVF cycles of women with adenomyosis from January 2006 to January 2012. Fresh ET cycles without (147 cycles, group A) or with (105 cycles, group B) GnRH agonist pretreatment, and FET cycles following GnRH agonist treatment (43 cycles, group C) were compared. Adenomyosis was identified by using transvaginal ultrasound at the initial workup and classified into focal and diffuse types. The IVF outcomes were also subanalyzed according to the adenomyotic region. Results GnRH agonist pretreatment increased the stimulation duration (11.5±2.1 days vs. 9.9±2.0 days) and total dose of gonadotropin (3,421±1,141 IU vs. 2,588±1,192 IU), which resulted in a significantly higher number of retrieved oocytes (10.0±8.2 vs. 7.9±6.8, p=0.013) in group B than in group A. Controlled ovarian stimulation for freezing resulted in a significantly higher number of retrieved oocytes (14.3±9.2 vs. 10.0±8.2, p=0.022) with a lower dose of gonadotropin (2,974±1,112 IU vs. 3,421±1,141 IU, p=0.037) in group C than in group B. The clinical pregnancy rate in group C (39.5%) tended to be higher than those in groups B (30.5%) and A (25.2%) but without a significant difference. Conclusion FET following GnRH agonist pretreatment tended to increase the pregnancy rate in patients with adenomyosis. Further large-scale prospective studies are required to confirm this result. PMID:27689040

  9. What is Rate-Limiting during Sustained Synaptic Activity: Vesicle Supply or the Availability of Release Sites

    PubMed Central

    Neher, Erwin

    2010-01-01

    For some types of synapses the availability of release-ready vesicles is a limiting factor during ongoing activity. Synaptic strength in this case is determined both by the recruitment of such vesicles and the probability of their release during an action potential. Here it is argued that not the availability of vesicles is the limiting factor for recruitment, but rather the availability of specific sites to which vesicles can dock. PMID:21423530

  10. Small scale controls of greenhouse gas release under elevated N deposition rates in a restoring peat bog in NW Germany

    NASA Astrophysics Data System (ADS)

    Glatzel, S.; Forbrich, I.; Krüger, C.; Lemke, S.; Gerold, G.

    2008-06-01

    In Central Europe, most bogs have a history of drainage and many of them are currently being restored. Success of restoration as well as greenhouse gas exchange of these bogs is influenced by environmental stress factors as drought and atmospheric nitrogen deposition. We determined the methane and nitrous oxide exchange of sites in the strongly decomposed center and less decomposed edge of the Pietzmoor bog in NW Germany in 2004. Also, we examined the methane and nitrous oxide exchange of mesocosms from the center and edge before, during, and following a drainage experiment as well as carbon dioxide release from disturbed unfertilized and nitrogen fertilized surface peat. In the field, methane fluxes ranged from 0 to 3.8 mg m-2 h-1 and were highest from hollows. Field nitrous oxide fluxes ranged from 0 to 574 μg m-2 h-1 and were elevated at the edge. A large Eriophorum vaginatum tussock showed decreasing nitrous oxide release as the season progressed. Drainage of mesocosms decreased methane release to 0, even during rewetting. There was a tendency for a decrease of nitrous oxide release during drainage and for an increase in nitrous oxide release during rewetting. Nitrogen fertilization did not increase decomposition of surface peat. Our examinations suggest a competition between vascular vegetation and denitrifiers for excess nitrogen. We also provide evidence that the von Post humification index can be used to explain nitrous oxide release from bogs, if the role of vascular vegetation is also considered. An assessment of the greenhouse gas release from nitrogen saturated restoring bogs needs to take into account elevated release from fresh Sphagnum peat as well as from sedges growing on decomposed peat. Given the high atmospheric nitrogen deposition, restoration will not be able to achieve an oligotrophic ecosystem in the short term.

  11. The release of dipicolinic acid--the rate-limiting step of Bacillus endospore inactivation during the high pressure thermal sterilization process.

    PubMed

    Reineke, Kai; Schlumbach, Karl; Baier, Daniel; Mathys, Alexander; Knorr, Dietrich

    2013-03-01

    High pressure combined with elevated temperatures can produce low acid, commercially sterile and shelf-stable foods. Depending on the temperature and pressure levels applied, bacterial endospores pass through different pathways, which can lead to a pressure-induced germination or inactivation. Regardless of the pathway, Bacillus endospores first release pyridine-2,6-dicarboxylic acid (DPA), which contributes to the low amount of free water in the spore core and is consequently responsible for the spore's high resistance against wet and dry heat. This is therefore the rate-limiting step in the high pressure sterilization process. To evaluate the impact of a broad pressure, temperature and time domain on the DPA release, Bacillus subtilis spores were pressure treated between 0.1 and 900 MPa at between 30 and 80 °C under isothermal isobaric conditions during dwell time. DPA quantification was assessed using HPLC, and samples were taken both immediately and 2 h after the pressure treatment. To obtain a release kinetic for some pressure-temperature conditions, samples were collected between 1s and 60 min after decompression. A multiresponse kinetic model was then used to derive a model covering all kinetic data. The isorate lines modeled for the DPA release in the chosen pressure-temperature landscape enabled the determination of three distinct zones. (I) For pressures <600 MPa and temperatures >50 °C, a 90% DPA release was achievable in less than 5 min and no difference in the amount of DPA was found immediately 2 h after pressurization. This may indicate irreversible damage to the inner spore membrane or membrane proteins. (II) Above 600 MPa the synergism between pressure and temperature diminished, and the treatment temperature alone dominated DPA release. (III) Pressures <600 MPa and temperatures <50 °C resulted in a retarded release of DPA, with strong increased differences in the amount of DPA released after 2 h, which implies a pressure-induced physiological

  12. Poly(ethylene glycol)-poly(lactic-co-glycolic acid) core-shell microspheres with enhanced controllability of drug encapsulation and release rate.

    PubMed

    Cha, Chaenyung; Jeong, Jae Hyun; Kong, Hyunjoon

    2015-01-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres have been widely used as drug carriers for minimally invasive, local, and sustained drug delivery. However, their use is often plagued by limited controllability of encapsulation efficiency, initial burst, and release rate of drug molecules, which cause unsatisfactory outcomes and several side effects including inflammation. This study presents a new strategy of tuning the encapsulation efficiency and the release rate of protein drugs from a PLGA microsphere by filling the hollow core of the microsphere with poly(ethylene glycol) (PEG) hydrogels of varying cross-linking density. The PEG gel cores were prepared by inducing in situ cross-linking reactions of PEG monoacrylate solution within the PLGA microspheres. The resulting PEG-PLGA core-shell microspheres exhibited (1) increased encapsulation efficiency, (2) decreased initial burst, and (3) a more sustained release of protein drugs, as the cross-linking density of the PEG gel core was increased. In addition, implantation of PEG-PLGA core-shell microspheres encapsulated with vascular endothelial growth factor (VEGF) onto a chicken chorioallantoic membrane resulted in a significant increase in the number of new blood vessels at an implantation site, while minimizing inflammation. Overall, this strategy of introducing PEG gel into PLGA microspheres will be highly useful in tuning release rates and ultimately in improving the therapeutic efficacy of a wide array of protein drugs.

  13. Examining the mechanisms responsible for lower ROS release rates in liver mitochondria from the long-lived house sparrow (Passer domesticus) and big brown bat (Eptesicus fuscus) compared to the short-lived mouse (Mus musculus).

    PubMed

    Brown, Jason C L; McClelland, Grant B; Faure, Paul A; Klaiman, Jordan M; Staples, James F

    2009-08-01

    Lower ROS release rate in long-lived species is likely caused by decreased reduction of electron transport chain (ETC) complexes, but how this is achieved remains largely unknown. We compared liver mitochondrial H(2)O(2) release rates among endotherms of comparable size and metabolic rate: house sparrow and big brown bat (both long-lived) and house mouse (short-lived). We hypothesized that low ROS release rates in long-lived species result from (i) lower mitochondrial respiration rate, (ii) increased mitochondrial proton conductance ('uncoupling to survive'), and/or (iii) increased ETC oxidative capacity ('spare oxidative capacity'). H(2)O(2) release rate was 70% lower in bats than mice despite similar respiration rates. Consistent with 'uncoupling to survive', proton leakiness was 3-fold higher in bats at membrane potentials above 130mV. Basal H(2)O(2) release rate and respiration rates were 2-fold higher in sparrows than mice. Consistent with 'spare oxidative capacity', subsaturating succinate decreased H(2)O(2) release rate in sparrows but not mice. Moreover, succinate:Cytochrome c oxidoreductase activity was 3-fold higher in sparrows, and ETC inhibitors increased ROS release rate 20-27-fold in sparrows (with glutamate or subsaturating succinate) but only 4-5-fold in mice. Taken together these data suggest that complexes I and III are less reduced under physiological conditions in sparrows. We conclude that different long-lived species may use distinct mechanisms to lower mitochondrial ROS release rate.

  14. Does cattle grazing of dual-purpose wheat accelerate the rate of stubble decomposition and nutrients released

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Decomposition and nutrient release of winter annual forages in integrated crop-livestock systems could be affected by the resultant alterations in structure and quality of residues caused by grazing, but little information is available to test this hypothesis. Information on residue dynamics is need...

  15. Effect of release rate of the SF(6) tracer on methane emission estimates based on ruminal and breath gas samples.

    PubMed

    Martin, C; Koolaard, J; Rochette, Y; Clark, H; Jouany, J P; Pinares-Patiño, C S

    2012-03-01

    The release rate (RR) of sulphur hexafluoride (SF(6)) gas from permeation tube in the rumen appears to be positively related with methane (CH(4)) emissions calculated using the SF(6) tracer technique. Gas samples of breath and ruminal headspace were collected simultaneously in order to evaluate the hypothesis that transactions of SF(6) in the rumen are the source for this relationship. Six non-lactating dairy cows fitted with rumen cannulae were subdivided into two groups and randomly assigned to a two-period crossover design to permeation tubes with low RR (LRR = 1.577 mg/day) or two-times higher RR (HRR = 3.147 mg/day) RR. The cows were fed limited amounts of maize silage (80% ad libitum) split into two meals (40% at 0800 h and 60% at 1600 h). Each period consisted of 3-day gas sampling. Immediately before the morning feed and then each hour over 8 h, ruminal gas samples (50 ml) were withdrawn through the cannula fitted with stoppers to prevent opening. Simultaneously, 8-h integrated breath gas samples were collected over the same period. Ratios of concentration of CH(4)/SF(6), CO(2)/SF(6) and CO(2)/CH(4) and emission estimates of CH(4) and CO(2) were calculated for each sample source using the SF(6) tracer technique principles. The LRR treatment yielded higher (P < 0.001) ruminal CH(4)/SF(6) (by 1.79 times) and CO(2)/SF(6) (by 1.90 times) ratios than the HRR treatment; however, these differences were lower than the 2.0 times difference expected from the RR between the LRR and HRR. Consequently, the LRR treatment was associated with lower (P < 0.01) ruminal emissions of CH(4) over the 8-h collection period than with the HRR treatment (+11%), a difference also confirmed by the breath samples (+11%). RR treatments did not differ (P = 0.53) in ruminal or breath CO(2) emissions; however, our results confirm that the SF(6) tracer seems inappropriate for CO(2) emissions estimation in ruminants. Irrespective of the RR treatment, breath samples yielded 8% to 9% higher CH

  16. Stretch-Induced Drug Delivery from Superhydrophobic Polymer Composites: Use of Crack Propagation Failure Modes for Controlling Release Rates.

    PubMed

    Wang, Julia; Kaplan, Jonah A; Colson, Yolonda L; Grinstaff, Mark W

    2016-02-18

    The concept of using crack propagation in polymeric materials to control drug release and its first demonstration are reported. The composite drug delivery system consists of highly-textured superhydrophobic electrosprayed microparticle coatings, composed of biodegradable and biocompatible polymers poly(caprolactone) and poly(glycerol monostearate carbonate-co-caprolactone), and a cellulose/polyester core. The release of entrapped agents is controlled by the magnitude of applied strain, resulting in a graded response from water infiltration through the propagating patterned cracks in the coating. Strain-dependent delivery of the anticancer agents cisplatin and 7-ethyl-10-hydroxycamptothecin to esophageal cancer cells (OE33) in vitro is observed. Finally the device is integrated with an esophageal stent to demonstrate delivery of fluorescein diacetate, using applied tension, to an ex vivo esophagus.

  17. Release of colloids from primary minimum contact under unfavorable conditions by perturbations in ionic strength and flow rate.

    PubMed

    Pazmino, Eddy; Trauscht, Jacob; Johnson, William P

    2014-08-19

    Colloid release from surfaces in response to ionic strength and flow perturbations has been mechanistically simulated. However, these models do not address the mechanism by which colloid attachment occurs, at least in the presence of bulk colloid-collector repulsion (unfavorable conditions), which is a prevalent environmental condition. We test whether a mechanistic model that predicts colloid attachment under unfavorable conditions also predicts colloid release in response to reduced ionic strength (IS) and increased fluid velocity (conditions thought prevalent for mobilization of environmental colloids). The model trades in mean-field colloid-collector interaction for discrete representation of surface heterogeneity, which accounts for a combination of attractive and repulsive interactions simultaneously, and results in an attached colloid population (in primary minimum contact with the surface) having a distribution of strengths of attraction. The model moderates equilibrium separation distance by inclusion of steric interactions. By using the same model parameters to quantitatively predict attachment under unfavorable conditions, simulated release of colloids (for all three sizes) from primary minimum attachment in response to perturbations qualitatively matched experimental results, demonstrating that both attachment and detachment were mechanistically simulated.

  18. Effect of trap design, chemical lure, carbon dioxide release rate, and source of carbon dioxide on efficacy of bed bug monitors.

    PubMed

    Singh, Narinderpal; Wang, Changlu; Cooper, Richard

    2013-08-01

    Bed bugs, (Cimex lectularius L.), are difficult to find because of their nocturnal and secretive behavior. In recent years, a number of monitors containing carbon dioxide (CO2), chemical lures, heat, or both, to attract bed bugs have been developed for detecting bed bugs. Ineffective trap design, lack of attraction of chemical lures, high cost of the CO2 delivery system, or insufficient CO release rates are some factors that limited the wide adoption of these monitors. To develop an affordable and effective monitor, we conducted a series of laboratory and field tests. Specifically, we tested a new pitfall trap design, a chemical lure mixture, different CO2 release rates, and a sugar and yeast mixture as CO2 source. Results show the new pitfall trap design was significantly more effective than Climbup insect interceptor, the most effective passive monitor available in the market for bed bugs. The experimental chemical lure mixture increased Climbup insect interceptor catch by 2.2 times. Results exhibit a distinct positive relationship between the CO2 release rates and bed bug trap catches. There were no significant differences between CO2 derived from cylinders and CO2 generated from sugar and yeast mixture in their attractiveness to bed bugs. The findings suggest an effective and affordable monitor can be made incorporating the new pitfall trap design, a sugar and yeast mixture, and a chemical lure.

  19. STEADY-STATE FLAMMABLE GAS RELEASE RATE CALCULATION AND LOWER FLAMMABILITY LEVEL EVALUATION FOR HANFORD TANK WASTE

    SciTech Connect

    HU TA

    2007-10-26

    Assess the steady-state flammability level at normal and off-normal ventilation conditions. The methodology of flammability analysis for Hanford tank waste is developed. The hydrogen generation rate model was applied to calculate the gas generation rate for 177 tanks. Flammability concentrations and the time to reach 25% and 100% of the lower flammability limit, and the minimum ventilation rate to keep from 100 of the LFL are calculated for 177 tanks at various scenarios.

  20. Q3DG: A computer program for strain-energy-release rates for delamination growth in composite laminates

    NASA Technical Reports Server (NTRS)

    Raju, I. S.

    1986-01-01

    The Q3DG is a computer program developed to perform a quasi-three-dimensional stress analysis for composite laminates which may contain delaminations. The laminates may be subjected to mechanical, thermal, and hygroscopic loads. The program uses the finite element method and models the laminates with eight-noded parabolic isoparametric elements. The program computes the strain-energy-release components and the total strain-energy release in all three modes for delamination growth. A rectangular mesh and data file generator, DATGEN, is included. The DATGEN program can be executed interactively and is user friendly. The documentation includes sections dealing with the Q3D analysis theory, derivation of element stiffness matrices and consistent load vectors for the parabolic element. Several sample problems with the input for Q3DG and output from the program are included. The capabilities of the DATGEN program are illustrated with examples of interactive sessions. A microfiche of all the examples is included. The Q3DG and DATGEN programs have been implemented on CYBER 170 class computers. Q3DG and DATGEN were developed at the Langley Research Center during the early eighties and documented in 1984 to 1985.

  1. Primer release is the rate-limiting event in lagging-strand synthesis mediated by the T7 replisome

    PubMed Central

    Hernandez, Alfredo J.; Lee, Seung-Joo; Richardson, Charles C.

    2016-01-01

    DNA replication occurs semidiscontinuously due to the antiparallel DNA strands and polarity of enzymatic DNA synthesis. Although the leading strand is synthesized continuously, the lagging strand is synthesized in small segments designated Okazaki fragments. Lagging-strand synthesis is a complex event requiring repeated cycles of RNA primer synthesis, transfer to the lagging-strand polymerase, and extension effected by cooperation between DNA primase and the lagging-strand polymerase. We examined events controlling Okazaki fragment initiation using the bacteriophage T7 replication system. Primer utilization by T7 DNA polymerase is slower than primer formation. Slow primer release from DNA primase allows the polymerase to engage the complex and is followed by a slow primer handoff step. The T7 single-stranded DNA binding protein increases primer formation and extension efficiency but promotes limited rounds of primer extension. We present a model describing Okazaki fragment initiation, the regulation of fragment length, and their implications for coordinated leading- and lagging-strand DNA synthesis. PMID:27162371

  2. Nano-encapsulation of olive leaf phenolic compounds through WPC-pectin complexes and evaluating their release rate.

    PubMed

    Mohammadi, Adeleh; Jafari, Seid Mahdi; Assadpour, Elham; Faridi Esfanjani, Afshin

    2016-01-01

    In this study, W/O micro-emulsions as primary emulsions and a complex of whey protein concentrate (WPC) and pectin in the external aqueous phase were used to produce W/O/W emulsions. Average droplet size of primary W/O emulsion and multiple emulsions stabilized by WPC or WPC-pectin after one day of production was 6.16, 675.7 and 1443 nm, respectively, which achieved to 22.97, 347.7 and, 1992.4 nm after 20 days storage without any sedimentation. The encapsulation efficiency of phenolic compounds for stabilized W/O/W emulsions with WPC and WPC-pectin were 93.34% and 96.64%, respectively, which was decreased to 72.73% and 88.81% at 20th storage day. The lowest release of phenolics observed in multiple emulsions of WPC-pectin. These results suggest that nano-encapsulation of olive leaf extract within inner aqueous phase of W/O/W emulsions was successful, and there could be a high potential for the application of olive leaf extract in fortification of food products.

  3. The biowaiver extension for BCS class III drugs: the effect of dissolution rate on the bioequivalence of BCS class III immediate-release drugs predicted by computer simulation.

    PubMed

    Tsume, Yasuhiro; Amidon, Gordon L

    2010-08-02

    The Biopharmaceutical Classification System (BCS) guidance issued by the FDA allows waivers for in vivo bioavailability and bioequivalence studies for immediate-release (IR) solid oral dosage forms only for BCS class I drugs. However, a number of drugs within BCS class III have been proposed to be eligible for biowaivers. The World Health Organization (WHO) has shortened the requisite dissolution time of BCS class III drugs on their Essential Medicine List (EML) from 30 to 15 min for extended biowaivers; however, the impact of the shorter dissolution time on AUC(0-inf) and C(max) is unknown. The objectives of this investigation were to assess the ability of gastrointestinal simulation software to predict the oral absorption of the BCS class I drugs propranolol and metoprolol and the BCS class III drugs cimetidine, atenolol, and amoxicillin, and to perform in silico bioequivalence studies to assess the feasibility of extending biowaivers to BCS class III drugs. The drug absorption from the gastrointestinal tract was predicted using physicochemical and pharmacokinetic properties of test drugs provided by GastroPlus (version 6.0). Virtual trials with a 200 mL dose volume at different drug release rates (T(85%) = 15 to 180 min) were performed to predict the oral absorption (C(max) and AUC(0-inf)) of the above drugs. Both BCS class I drugs satisfied bioequivalence with regard to the release rates up to 120 min. The results with BCS class III drugs demonstrated bioequivalence using the prolonged release rate, T(85%) = 45 or 60 min, indicating that the dissolution standard for bioequivalence is dependent on the intestinal membrane permeability and permeability profile throughout the gastrointestinal tract. The results of GastroPlus simulations indicate that the dissolution rate of BCS class III drugs could be prolonged to the point where dissolution, rather than permeability, would control the overall absorption. For BCS class III drugs with intestinal absorption patterns

  4. Effect of release rate and ratio of (Z)-11-hexadecen-1-ol from synthetic pheromone blends on trap capture ofHeliothis subflexa (Lepidoptera: Noctuidae).

    PubMed

    Heath, R R; Mitchell, E R; Cibrian Tovar, J

    1990-04-01

    Response of maleHeliothis subflexa to pheromone-baited traps containing blends of tetradecanal, (Z)-9-tetradecanal, hexadecanal, (Z)-7-hexadecenal, (Z)-9-hexadecenal, (Z)-11-hexadecenal, hexadecan-1-ol acetate, (Z)-7-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol acetate, (Z)-11-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol, and (Z)-11-hexadecen-1-ol was evaluated. Analysis of trap capture data indicated that (Z)-11-hexadecen-1-ol was a critical component of the pheromone blend. It was determined from emission rate data and measurements of the ratio of pheromone components emitted from rubber septa tested that a significant increase in trap capture of maleH. subflexa occurred when the blends investigated released the alcohol in a narrow range relative to the total amount of pheromone emitted. The optimum range of release ratio of the alcohol for the capture of males in sticky traps was determined to be 0.9-3.5% of the pheromone blend. This release ratio range was reduced to 0.9-1.6% when bucket traps were used.

  5. [Nitrogen uptake rate and use efficiency by rice under different levels of the controlled-release N fertilizers (CRF) in the Nansi Lake basin].

    PubMed

    Zhang, Qing-Wen; Du, Chun-Xiang; Li, Xiao-Wei; Li, Gui-Chun; Wang, Ming

    2011-07-01

    The nitrogen (N) fertilizers overused or misused are the main contributors for water eutrophication of the Nansi Lake in eastern China. A field experiment with different application levels of controlled-release N fertilizer (CRF) was carried out at a rice field in the Nansi lake basin to provide information on the nitrogen uptake rate and use efficiency by rice with CRF application at different growth stages of rice. The fertilization levels for the controlled fertilizer in this study were 0, 300, 337.5 and 375 kg/hm2, respectively, and 375 kg/hm2 for conventional urea (CU). We estimated the N uptake rate in different growing season and apparent recovery of fertilizer in root, stover and grain of rice. The result showed that grain yield increased by higher N rate. However, the N uptake rate did not increase linearly with the nitrogen application amount. The highest N uptake rate was 22.48 mg/(plant x d) under the fertilization amount of 337.5 kg/hm2 during the young panicle differentiation stage. Apparent N recovery efficiency for CU with traditional application amount of 375 kg/hm2 was 21.86%. Apparent N recovery efficiency for CRF with application amount of 337.5 kg/hm2 was highest with 37.17%. Based on the statistical data, with CU of traditional urea application amount of 375 kg/hm2, nitrogen loss and soil N residue at one growing season are 130.07 x 10(3) t for Jining city and 11.4 x 10(3) t for Yutai county of the Nansi Lake basin. If using CRF with the optimized application amount of 337.5 kg/hm2, nitrogen loss and soil residual at one growing season is 10.46 x 10(4) t for Jining city. It could reduce losses of 2.55 x 10(4) t N for Jining city and 2 235.26 t N for Yutai county per year. Because of releasing patterns more closely matched to crop N uptake patterns, controlled release N fertilizer could be a good way to prevent water eutrophication due to nitrogen fertilizer overused or misused in the Nansi Lake.

  6. Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion.

    PubMed

    Rodriguez, Omar; Matinmanesh, Ali; Phull, Sunjeev; Schemitsch, Emil H; Zalzal, Paul; Clarkin, Owen M; Papini, Marcello; Towler, Mark R

    2016-12-01

    Silica-based and borate-based glass series, with increasing amounts of TiO₂ incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate's (Ti6Al4V) CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO₂ in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO₂ to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO₂ incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass(®) and Pyrex.

  7. A Semi-Analytical Method for Determining the Energy Release Rate of Cracks in Adhesively-Bonded Single-Lap Composite Joints

    NASA Technical Reports Server (NTRS)

    Yang, Charles; Sun, Wenjun; Tomblin, John S.; Smeltzer, Stanley S., III

    2007-01-01

    A semi-analytical method for determining the strain energy release rate due to a prescribed interface crack in an adhesively-bonded, single-lap composite joint subjected to axial tension is presented. The field equations in terms of displacements within the joint are formulated by using first-order shear deformable, laminated plate theory together with kinematic relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. Based on the adhesive stress distributions, the forces at the crack tip are obtained and the strain energy release rate of the crack is determined by using the virtual crack closure technique (VCCT). Additionally, the test specimen geometry from both the ASTM D3165 and D1002 test standards are utilized during the derivation of the field equations in order to correlate analytical models with future test results. The system of second-order differential field equations is solved to provide the adherend and adhesive stress response using the symbolic computation tool, Maple 9. Finite element analyses using J-integral as well as VCCT were performed to verify the developed analytical model. The finite element analyses were conducted using the commercial finite element analysis software ABAQUS. The results determined using the analytical method correlated well with the results from the finite element analyses.

  8. Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion

    PubMed Central

    Rodriguez, Omar; Matinmanesh, Ali; Phull, Sunjeev; Schemitsch, Emil H.; Zalzal, Paul; Clarkin, Owen M.; Papini, Marcello; Towler, Mark R.

    2016-01-01

    Silica-based and borate-based glass series, with increasing amounts of TiO2 incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion) closer to the substrate’s (Ti6Al4V) CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO2 in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO2 to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO2 incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass® and Pyrex. PMID:27916951

  9. Using gonadotropin-releasing hormone agonist before frozen embryo transfer may improve ongoing pregnancy rates in hyperandrogenic polycystic ovary syndrome women.

    PubMed

    Tsai, Hsiao-Wen; Wang, Peng-Hui; Lin, Li-Te; Chen, San-Nung; Tsui, Kuan-Hao

    2017-04-10

    Polycystic ovary syndrome (PCOS), affecting more than 5-10% of woman at reproductive childbearing age, is characterized by anovulation and hyperandrogenism. Frozen-thawed embryo transfer (ET) has been widely used for PCOS women to minimize the risk of ovarian hyperstimulation syndrome. However, the hyperandrogenic status of PCOS women deteriorates endometrial function, which has subsequently increased miscarriage rates in PCOS women. Therefore, we conducted this retrospective study to compare the pregnancy outcomes of hyperandrogenic PCOS women with (n = 29) and without (n = 31, controls) pretreatment of gonadotropin-releasing hormone (GnRH) agonist before frozen-thawed ET. We found that pretreatment with GnRH agonist before frozen-thawed ETs could not significantly improve the clinical pregnancy rate in these hyperandrogenic PCOS women. However, the ongoing pregnancy rate was significantly increased in women with GnRH agonist pretreatment (odds ratio: 3.98, 95% confidence interval: 1.12-14.20, p = 0.033). We concluded that androgen deprivation status due to pretreatment with GnRH agonist might improve the ongoing pregnancy rate in hyperandrogenic PCOS women. Additional large, well-designed prospective studies are worthwhile and necessary.

  10. Influence of spawn rate and commercial delayed release nutrient levels on Pleurotus cornucopiae (oyster mushroom) yield, size, and time to production.

    PubMed

    Royse, D J

    2002-03-01

    Pleurotus cornucopiae 608 was grown on a mixture of pasteurized cottonseed hulls (75% dry wt). 24% chopped wheat straw, and 1% ground limestone. The substrate was spawned at various levels (1.25%, 2.5%, 3.75%, or 5% wet wt) and not supplemented or supplemented with commercial delayed release nutrient (Campbell's S-41) at various levels (0%, 3%, 6%, 9%, or 12%). Maximum yield (weight of fresh mushrooms harvested at maturity) was obtained at 3.75-5% spawn level and 6% S-41 supplement. As supplement levels exceeded 6%, yields declined significantly. There was a negative correlation (r=-0.81) between spawn rate and days to production. As the spawn rate increased, the number of days to production decreased. By using a spawn rate of 3.75% of the wet substrate wt, it was possible to reduce the time to production by a mean of 9.2 days compared with a spawn rate of 1.25%.

  11. A poly(glycerol sebacate)-coated mesoporous bioactive glass scaffold with adjustable mechanical strength, degradation rate, controlled-release and cell behavior for bone tissue engineering.

    PubMed

    Lin, Dan; Yang, Kai; Tang, Wei; Liu, Yutong; Yuan, Yuan; Liu, Changsheng

    2015-07-01

    Various requirements in the field of tissue engineering have motivated the development of three-dimensional scaffold with adjustable physicochemical properties and biological functions. A series of multiparameter-adjustable mesoporous bioactive glass (MBG) scaffolds with uncrosslinked poly(glycerol sebacate) (PGS) coating was prepared in this article. MBG scaffold was prepared by a modified F127/PU co-templating process and then PGS was coated by a simple adsorption and lyophilization process. Through controlling macropore parameters and PGS coating amount, the mechanical strength, degradation rate, controlled-release and cell behavior of the composite scaffold could be modulated in a wide range. PGS coating successfully endowed MBG scaffold with improved toughness and adjustable mechanical strength covering the bearing range of trabecular bone (2-12MPa). Multilevel degradation rate of the scaffold and controlled-release rate of protein from mesopore could be achieved, with little impact on the protein activity owing to an "ultralow-solvent" coating and "nano-cavity entrapment" immobilization method. In vitro studies indicated that PGS coating promoted cell attachment and proliferation in a dose-dependent manner, without affecting the osteogenic induction capacity of MBG substrate. These results first provide strong evidence that uncrosslinked PGS might also yield extraordinary achievements in traditional MBG scaffold. With the multiparameter adjustability, the composite MBG/PGS scaffolds would have a hopeful prospect in bone tissue engineering. The design considerations and coating method of this study can also be extended to other ceramic-based artificial scaffolds and are expected to provide new thoughts on development of future tissue engineering materials.

  12. Enhanced dissolution rate and synchronized release of drugs in binary systems through formulation: Amorphous naproxen-cimetidine mixtures prepared by mechanical activation.

    PubMed

    Allesø, Morten; Chieng, Norman; Rehder, Sönke; Rantanen, Jukka; Rades, Thomas; Aaltonen, Jaakko

    2009-05-21

    Naproxen, a non-steroidal anti-inflammatory drug (NSAID), is a biopharmaceutics classification system (BCS) class II drug whose bioavailability is rate-limited by its dissolution. Cimetidine is sometimes co-administered with naproxen for the treatment of NSAID-induced gastro-intestinal disorders. Hence, there is interest in the design of new formulations that offer (1) concomitant release of both drugs, and (2) an enhanced dissolution rate of naproxen. This study investigates the formation of amorphous binary systems with naproxen and cimetidine. The binary mixtures of all tested molar ratios were found to become amorphous upon co-milling for 60 min at 4 degrees C. In contrast, pure naproxen could not be transformed to the amorphous state by mechanical activation. The 1:1 sample was the most physically stable when stored for 33 days at 40 degrees C, even though it did not have the highest T(g) when compared to the 1:2 sample. The 1:1 sample was further stored for 186 days and remained amorphous under all conditions. Raman spectroscopy suggested a 1:1 solid-state interaction between the imidazole ring of cimetidine and the carboxylic acid moiety of naproxen in the co-milled amorphous sample. Thus, the stabilization of the amorphous binary system is dictated by molecular-level interactions rather than bulk-level phenomena. No recrystallization of either drug in the 1:1 co-milled sample was observed during dissolution testing, with naproxen and cimetidine having a four and two times higher intrinsic dissolution rate, respectively, compared to their crystalline counterparts. Further, the release of the two drugs could be synchronized using this formulation approach.

  13. Comparison of toxicity and release rates of Cu and Zn from anti-fouling paints leached in natural and artificial brackish seawater.

    PubMed

    Ytreberg, Erik; Karlsson, Jenny; Eklund, Britta

    2010-05-15

    Biocide-containing anti-fouling paints are regulated and approved according to the added active ingredients, such as Cu. Biocide-free paints are considered to be less environmentally damaging and do not need an approval. Zn, a common ingredient in paints with the potential of causing adverse effects has received only minor attention. Laboratory experiments were conducted in artificial brackish seawater (ASW) and natural brackish seawater (NSW) to quantify release rates of Cu and Zn from biocide-containing and biocide-free labeled eroding anti-fouling paints used on commercial vessels as well as leisure boats. In addition, organisms from three trophic levels, the crustacean Nitocra spinipes, the macroalga Ceramium tenuicorne and the bacteria Vibrio fischeri, were exposed to Cu and Zn to determine the toxicity of these metals. The release rate of Cu in NSW was higher from the paints for professional use (3.2-3.6 microg cm(-)(2)d(-1)) than from the biocide leaching leisure boat paint (1.1 microg cm(-)(2)d(-1)). Biocide-free paints did leach considerably more Zn (4.4-8.2 microg cm(-)(2)d(-1)) than biocide-containing leisure boat paint (3.0 microg cm(-)(2)d(-1)) and ship paints (0.7-2.0 microg cm(-)(2)d(-1)). In ASW the release rates of both metals were notably higher than in NSW for most tested paints. The macroalga was the most sensitive species to both Cu (EC(50)=6.4 microg l(-1)) and Zn (EC(50)=25 microg l(-1)) compared to the crustacean (Cu, LC(50)=2000 microg l(-1) Zn, LC(50)=890 microg l(-1)), and the bacteria (Cu, EC(50)=800 microg l(-1) and Zn, EC(50)=2000 microg l(-1)). The results suggest that the amounts of Zn and Cu leached from anti-fouling paints may attain toxic concentrations in areas with high boat density. To fully account for potential ecological risk associated with anti-fouling paints, Zn as well as active ingredients should be considered in the regulatory process.

  14. Plasma progesterone profile and conception rate following exogenous supplementation of gonadotropin-releasing hormone, human chorionic gonadotropin, and progesterone releasing intra-vaginal device in repeat-breeder crossbred cows

    PubMed Central

    Pandey, N. K. J.; Gupta, H. P.; Prasad, Shiv; Sheetal, S. K.

    2016-01-01

    Aim: This study was designed to evaluate the effect of gonadotropin-releasing hormone (GnRH), human chorionic gonadotropin (hCG), and progesterone impregnated intra-vaginal device on progesterone profile and conception rate in repeat-breeding crossbred cows. Materials and Methods: Repeat-breeding crossbred cows aged 3-8 years (n=32), lactating and negative to white side test were randomly divided into four groups: Group 1 (Control, n=8), Group 2 (GnRH at 10 µg i.m, n=8), Group 3 (hCG at 1500 IU i.m., n=8), and Group 4 (progesterone impregnated intra-vaginal device at 958 mg, n=8). All the treatme nts were given on 5th daypostbreeding and in Group 4 intra-vaginally implanted device was withdrawn on 9th day (i.e., implant inserted for total 4 days) of the estrous cycle. Blood samples were collected on day 0, 5, 10, 15, and day 20 of estrous cycle, and plasma was separated for progesterone estimation. Results: Accessory corpus luteum was not formed in crossbred cows of Group4 and control group. However, total 6 and 8 accessory corpora lutea were found in Group 2 and Group 3, respectively. In pregnant cows, the plasma progesterone concentration increased continuously from day 0 to day 20. In non-pregnant cows, it increased from day 0 to day 15 and then declined. The conception rate on day 60 in Group 1, Group 2, Group 3, and Group 4 was 37.5%, 50%, 75%, and 37.5%, respectively. Conclusions: Treating repeat-breeder cows with hCG is effective in increasing conception rate by developing accessory corpora lutea and higher progesterone level. PMID:27397976

  15. Quarterly technical progress report No. 2, December 20-March 19, 1982. Second quarterly report on the effect of rapid heating rate on coal nitrogen and sulfur release

    SciTech Connect

    Gat, N.

    1982-04-26

    A laser pyrolysis technique is applied to the investigation of the effects of heating rate on release of coal-bound sulfur and nitrogen. An experimental system characterization and calibration has been completed. A detailed documentation was prepared describing the 3-color pyrometer and the data analysis technique. The coal particle feed system has been calibrated to provide accurate mass flow rate at pre-selected particle velocities. The first batch of samples submitted for chemical analysis will be used for the determination of kinetics parameters at a high heating rate (approximately equal to 10/sup 6/ K/s). The coal used presently is a Montana Rosebud. Two other coals are available; one is ILL No. 6 (through EERC) which will need to be pulverized and the second is a Pitt. hv-A (through KVB). It was confirmed that sieve and drag size distribution of coal differ significantly, and that particle shape effects may be significant in the modelling of particle dynamics.

  16. Comparison of pregnancy rates in beef cattle after a fixed-time AI with once- or twice-used controlled internal drug release devices.

    PubMed

    Muth-Spurlock, A M; Poole, D H; Whisnant, C S

    2016-02-01

    The use of fixed-time artificial insemination (FTAI) provides producers with numerous benefits including the use of superior genetics, shorter breeding and calving seasons, and a more uniform calf crop. However, the cost of implementing FTAI protocols is one of the several drawbacks hindering their use in the beef industry. Potential injection-site lesions from intramuscular injections of the hormones necessary for estrus synchronization are also a cause of concern for carcass quality. The objectives of this experiment were to (1) determine whether or not a twice-used controlled internal drug release (CIDR) device would be effective in an FTAI protocol without adversely affecting pregnancy rate and (2) whether or not the subcutaneous administration of PGF2α affects pregnancy rate. Nulliparous females (n = 99) between 13 and 27 months of age and multiparous cows (n = 43) between 48 and 74 months of age were synchronized for estrus using the 7-day CO-Synch + CIDR protocol. The females were randomly assigned to one of the two treatments: (1) a once-used CIDR (control) or (2) a twice-used CIDR device (treatment) incorporated into their synchronization protocol. The females were also randomly assigned to have their injection of PGF2α administered either intramuscularly or subcutaneously. Blood was taken in a random subset of nulliparous females (n = 52) just before device removal and assayed for concentration of progesterone. The concentration of progesterone was higher (P = 0.01) in the animals that received once-used CIDR devices than that in those received twice-used CIDR devices (3.4 ± 0.5 and 1.4 ± 0.5 ng/mL, respectively). There was no significant effect of parity (P = 0.82), artificial insemination technician (P = 0.60), PGF2α administration (P = 0.83), or treatment (P = 0.67) on pregnancy rates to artificial insemination which were 75.4 ± 6.0% and 71.7 ± 6.4%, for animals that received once- and twice-used CIDR devices, respectively. This study provides

  17. Parsing the Sources of Gross Gains in Stream Flow Based on Mass Recovery of Concurrent Instantaneous and Constant-Rate Tracer Releases Over Multi-Scaled Reaches

    NASA Astrophysics Data System (ADS)

    Gooseff, M. N.; Payn, R. A.; McGlynn, B. L.

    2014-12-01

    Reach-scale solute transport studies are often used to characterize transient storage of solutes or groundwater-stream exchanges, yet the results are limited by window of detection issues (the limit of temporal and spatial scales over which one can infer processes from observed breakthrough curves). To determine the influence of exchanges into and out of reaches of different spatial scales, we conducted two simultaneous tracer injection types in a headwater stream in the Tenderfoot Creek Experimental Forest in central Montana, USA - one constant rate Rhodamine WT (RWT) injection (8 days) over 2.8 km of stream, and synoptic chloride releases in 28 100-m and 14 200-m subreaches when the RWT concentrations were at quasi-steady state. From the synoptic releases, we examined the spatial distribution of stream flow exchanges. Stream discharge increased from 0.8 L s-1 (at the head) to 27 L s-1 (at the base) along the 2.8-km study reach. Although the stream gains water at the scale of the 2.8-km study reach, stream water balances in the 100-m and 200-m subreaches demonstrate gross gains and losses. When comparing the summed gains and losses of the two 100-m subreach exchanges to that of the encompassing 200-m reach, the combined 100 m reaches always exhibit greater gain and loss. We interpret this as an indication that the 200-m reach includes return flows that appear to be losses from the 100-m subreaches. When we evaluate the change in RWT load at 100-m and 200-m subreach scales, we find typically less mass loss of RWT than is computed from the chloride slug releases, indicating the gain of RWT from long hyporheic flowpaths that originate upstream of the subreach of interest (even when RWT is likely to be a less conservative tracer than chloride). We can further parse gains of stream water at the 100-m and 200-m scales into estimates of hyporheic water (i.e., streamwater labelled with RWT returning to the channel) and lateral water (not labelled with RWT), and we find

  18. Exploitation of 3D face-centered cubic mesoporous silica as a carrier for a poorly water soluble drug: influence of pore size on release rate.

    PubMed

    Zhu, Wenquan; Wan, Long; Zhang, Chen; Gao, Yikun; Zheng, Xin; Jiang, Tongying; Wang, Siling

    2014-01-01

    The purposes of the present work were to explore the potential application of 3D face-centered cubic mesoporous silica (FMS) with pore size of 16.0nm as a delivery system for poorly soluble drugs and investigate the effect of pore size on the dissolution rate. FMS with different pore sizes (16.0, 6.9 and 3.7nm) was successfully synthesized by using Pluronic block co-polymer F127 as a template and adjusting the reaction temperatures. Celecoxib (CEL), which is a BCS class II drug, was used as a model drug and loaded into FMS with different pore sizes by the solvent deposition method at a drug-silica ratio of 1:4. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen adsorption, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) was used to systematically investigate the drug loading process. The results obtained showed that CEL was in a non-crystalline state after incorporation of CEL into the pores of FMS-15 with pore size of 16.0nm. In vitro dissolution was carried out to demonstrate the effects of FMS with different pore sizes on the release of CEL. The results obtained indicated that the dissolution rate of CEL from FMS-15 was significantly enhanced compared with pure CEL. This could be explained by supposing that CEL encountered less diffusion resistance and its crystallinity decreased due to the large pore size of 16.0nm and the nanopore channels of FMS-15. Moreover, drug loading and pore size both play an important role in enhancing the dissolution properties for the poorly water-soluble drugs. As the pore size between 3.7 and 16.0nm increased, the dissolution rate of CEL from FMS gradually increased.

  19. Strain energy release rates of composite interlaminar end-notch and mixed-mode fracture: A sublaminate/ply level analysis and a computer code

    NASA Technical Reports Server (NTRS)

    Valisetty, R. R.; Chamis, C. C.

    1987-01-01

    A computer code is presented for the sublaminate/ply level analysis of composite structures. This code is useful for obtaining stresses in regions affected by delaminations, transverse cracks, and discontinuities related to inherent fabrication anomalies, geometric configurations, and loading conditions. Particular attention is focussed on those layers or groups of layers (sublaminates) which are immediately affected by the inherent flaws. These layers are analyzed as homogeneous bodies in equilibrium and in isolation from the rest of the laminate. The theoretical model used to analyze the individual layers allows the relevant stresses and displacements near discontinuities to be represented in the form of pure exponential-decay-type functions which are selected to eliminate the exponential-precision-related difficulties in sublaminate/ply level analysis. Thus, sublaminate analysis can be conducted without any restriction on the maximum number of layers, delaminations, transverse cracks, or other types of discontinuities. In conjunction with the strain energy release rate (SERR) concept and composite micromechanics, this computational procedure is used to model select cases of end-notch and mixed-mode fracture specimens. The computed stresses are in good agreement with those from a three-dimensional finite element analysis. Also, SERRs compare well with limited available experimental data.

  20. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    SciTech Connect

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injection strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still significant

  1. A spontaneously arising mutation in connexin32 with repeated passage of FRTL-5 cells coincides with increased growth rate and reduced thyroxine release

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Tran, D. T.; Nelson, G. A.; Shah, M. M.; Luben, R. A.

    2001-01-01

    In this study we examine changes in the cellular properties of FRTL-5 cells as a function of passage number, with particular emphasis on gap junction expression, karyotype, morphology, growth rate and thyroxine (T(4)) release. Early passage FRTL-5 follicular cells transfer dye through gap junctions from injected cell(s) to third-order neighboring cells and beyond within their respective follicles and have immuno-detectable connexin32 (Cx32) type gap junctional plaques in their lateral contacting plasma membranes. By contrast, FRTL-5 cells established as monolayers, or as follicles from cultures passed more than 15 times, did not transfer microinjected Lucifer Yellow dye to contiguous neighboring cells and did not express any immuno-detectable rat thyroid specific connexins (Cx43, Cx32 or Cx26). Western blots confirmed that total, membrane and cytosolic Cx32 protein was present only in early pass follicular cultures. To better understand the passage-dependent loss of Cx32 expression, RT-PCR primers were made to the most unique sequences of the rat Cx32 molecule, the cytoplasmic and carboxyl-terminal regions. These primers were used to screen FRTL-5 RNA from cultures of various passage numbers. The results revealed that later passage cultures had a single base deletion in the middle of the Cx32 cytoplasmic loop region at nucleotide position 378. This base deletion was in the middle position of the codon for amino acid 116, which is normally a CAC (histidine) but read with the frame shift was a CCC (proline). The four amino acids that followed this deletion were also altered with the fourth one becoming UAA, the ochre translation stop codon. This premature stopping of translation resulted in a truncation of 60% of the protein, which included the remaining cytoplasmic loop, third and fourth transmembrane regions and the carboxyl-terminus. The later passage cultures did not produce a carboxyl-terminal RT-PCR product, indicating that the mRNA was also truncated. These

  2. A spontaneously arising mutation in connexin32 with repeated passage of FRTL-5 cells coincides with increased growth rate and reduced thyroxine release

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Tran, D. T.; Nelson, G. A.; Shah, M. M.; Luben, R. A.

    2001-01-01

    In this study we examine changes in the cellular properties of FRTL-5 cells as a function of passage number, with particular emphasis on gap junction expression, karyotype, morphology, growth rate and thyroxine (T(4)) release. Early passage FRTL-5 follicular cells transfer dye through gap junctions from injected cell(s) to third-order neighboring cells and beyond within their respective follicles and have immuno-detectable connexin32 (Cx32) type gap junctional plaques in their lateral contacting plasma membranes. By contrast, FRTL-5 cells established as monolayers, or as follicles from cultures passed more than 15 times, did not transfer microinjected Lucifer Yellow dye to contiguous neighboring cells and did not express any immuno-detectable rat thyroid specific connexins (Cx43, Cx32 or Cx26). Western blots confirmed that total, membrane and cytosolic Cx32 protein was present only in early pass follicular cultures. To better understand the passage-dependent loss of Cx32 expression, RT-PCR primers were made to the most unique sequences of the rat Cx32 molecule, the cytoplasmic and carboxyl-terminal regions. These primers were used to screen FRTL-5 RNA from cultures of various passage numbers. The results revealed that later passage cultures had a single base deletion in the middle of the Cx32 cytoplasmic loop region at nucleotide position 378. This base deletion was in the middle position of the codon for amino acid 116, which is normally a CAC (histidine) but read with the frame shift was a CCC (proline). The four amino acids that followed this deletion were also altered with the fourth one becoming UAA, the ochre translation stop codon. This premature stopping of translation resulted in a truncation of 60% of the protein, which included the remaining cytoplasmic loop, third and fourth transmembrane regions and the carboxyl-terminus. The later passage cultures did not produce a carboxyl-terminal RT-PCR product, indicating that the mRNA was also truncated. These

  3. [Lateral retinacular release].

    PubMed

    Verdonk, P; Bonte, F; Verdonk, R

    2008-09-01

    This overview of numerous studies discusses, based on short-term and long-term results, which diagnoses are indications for lateral retinacular release. No significant differences in outcome between arthroscopic and open lateral release could be documented. Isolated lateral release offers a good success rate for treating a stable patella with excessive lateral pressure. In patellar instability, the results are less favorable in long-term follow-up evaluation. Hyperlaxity with hypermobility of the patella is an absolute contraindication. Lateral release provides only temporary benefit for patellofemoral osteoarthritis. Proximal and/or distal realignment of the extensor mechanism gives better results than isolated lateral release.

  4. Investigating Effects of the November 2004 High-Flow Release From Glen Canyon Dam on Aeolian Sand-Transport Rates in the Colorado River Corridor, Grand Canyon, Arizona

    NASA Astrophysics Data System (ADS)

    Draut, A. E.; Rubin, D. M.

    2005-12-01

    In November, 2004, a 60-hour experimental flood release from Glen Canyon Dam held the Colorado River flow through Grand Canyon, Arizona, above 1,160 m3 s-1 (41,000 ft3 s-1). This high-flow experiment was designed to rebuild fluvial sand deposits, restoring a component of the ecosystem that had declined since closure of the dam in 1963. Transport and deposition of aeolian sand has important implications for archaeological resources in the river corridor, many of which are located in and covered by aeolian deposits. This study presents aeolian sediment-transport data collected in the river corridor during the year before and in the months after the flood experiment. At each of the six study locations, substantial new deposition of fluvial sand occurred as a result of the 2004 flood, which temporarily increased the amount of sand available for aeolian entrainment. However, high daily fluctuations (142 to 566 m3 s-1; 5,000 to 20,000 ft3 s-1) of the river flow from January to March 2005 removed much of the new sand before the start of the 2005 windy season. The greatest potential for aeolian re-distribution of flood-deposited sand occurred during the April-May windy season, during which the highest measured winds can locally exceed 25 m s-1, with sand-transport rates ~5 kg cm-1 day-1. These data may be used to guide decisions regarding future experimental floods and subsequent flow schedules, if maximizing sand redistribution by wind is a management objective.

  5. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    DOE PAGES

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injectionmore » strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still

  6. Encapsulation of proteins in hydrogel carrier systems for controlled drug delivery: influence of network structure and drug size on release rate.

    PubMed

    Bertz, Andreas; Wöhl-Bruhn, Stefanie; Miethe, Sebastian; Tiersch, Brigitte; Koetz, Joachim; Hust, Michael; Bunjes, Heike; Menzel, Henning

    2013-01-20

    Novel hydrogels based on hydroxyethyl starch modified with polyethylene glycol methacrylate (HES-P(EG)₆MA) were developed as delivery system for the controlled release of proteins. Since the drug release behavior is supposed to be related to the pore structure of the hydrogel network the pore sizes were determined by cryo-SEM, which is a mild technique for imaging on a nanometer scale. The results showed a decreasing pore size and an increase in pore homogeneity with increasing polymer concentration. Furthermore, the mesh sizes of the hydrogels were calculated based on swelling data. Pore and mesh size were significantly different which indicates that both structures are present in the hydrogel. The resulting structural model was correlated with release data for bulk hydrogel cylinders loaded with FITC-dextran and hydrogel microspheres loaded with FITC-IgG and FITC-dextran of different molecular size. The initial release depended much on the relation between hydrodynamic diameter and pore size while the long term release of the incorporated substances was predominantly controlled by degradation of the network of the much smaller meshes.

  7. The Effect of Potassium Nitrate on the Reduction of Phytophthora Stem Rot Disease of Soybeans, the Growth Rate and Zoospore Release of Phytophthora Sojae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of potassium nitrate (KNO3) application on Phytophthora stem rot disease reduction of Glycine max (L.) Merr. cvs. Chusei-Hikarikuro and Sachiyutaka, and fungal growth and zoospore release of a Phytophthora sojae isolate were investigated under laboratory conditions. The application of 4-...

  8. Finite-Layer Method: Exact Numerical and Analytical Calculations of the Energy Release Rate for Unidirectional Composite Specimens in Double-Cantilever Beam and End-Notched Flexure Tests

    NASA Astrophysics Data System (ADS)

    Timonin, A. M.

    2016-09-01

    Based on the finite-layer method, a method for evaluating the stress-strain state and energy release rate for specimens with delaminations in double-cantilever beam and end-notched flexure tests is proposed. Exact numerical solutions of boundary-value problems for the "stiff" systems of differential equations describing deformations of test specimens are obtained. The distributions of forces, moments, displacements, and rotations in the specimens and the distributions of normal and tangential stresses on their midline are presented. New closed-form expressions for these functions and for compliance of the specimens are developed. Calculation results for the energy release rate obtained by a numerical differentiation and from analytical relations are presented. Two new techniques for estimating the energy release rate are proposed: (1) using the calculated values of peak stress and jumps of displacements at the tip of delamination; (2) by evaluation of indeterminacy at the tip of delamination with the use of stresses and derivatives of stresses and displacements. The effect of the transverse shear and Poisson ratio on the results is estimated. A comparison of the numerical and analytical solutions obtained with known results and the ASTM standard is presented.

  9. The Measurements of Affinity Constants of Osmptrophs For P and Release Rates of P From Microbial Food Web From Late Summer To Early Winter In The Bay of Villefranche, The NW Mediterranean

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Rassoulzadegan, F.; Thingstad, T. F.

    Orthophosphate uptake by bacteria and phytoplankton was measured with 32P for wa- ter from the Bay of Villefranche (NW Mediterranean) from September to December 2001. The 32P release rate was measured for waters with different size of micro- bial community. During this period, the thermocline was gradually declined and the vertical mixing started, showing the transition from nutrient depleted to replete pe- riods. Before the vertical mixing started, orthophosphate turnover time ranged from 1 to 5 h. The fraction of orthophosphate uptake was dominated (mean 70%) by the 0.6-2 µm fraction where cyanobacteria biomass was dominant. Based on the theo- retical considerations proposed by Thingstad and Rassoulzadegan (1999), the affinity constants were estimated for bacteria, cyanobacteria and autotrophic nanoflagellates, respectively. They ranged from 0.001 to 0.028 L/nM-P/h for bacteria, from 0.047 to 0.103 L/nM-P/h for cyanobacteria and from 0.002 to 0.032 L/nM-P/h for autotrophic nanoflagellates when 32P turnover time was relatively shorter (<5 h). This may sup- port the previous report in which cyanobacteria were dominant in the primary pro- duction in autumn at the study site. The 32P release rates after the addition of cold chase were always less than 0.5%/h. This release appeared to be from the 0.2-0.6 or 0.6-2 µm fractions. The increase of 32P in the >2 µm fraction suggests P transfer by predation. Virus appeared to not contribute to 32P release from bacteria during the study period. These results indicate long P turnover times within particulate fraction and thus less contribution of P release from microbial food web.

  10. Effect of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer on bioadhesion and release rate property of eplerenone pellets.

    PubMed

    Kendre, Prakash Namdeo; Chaudhari, Pravin Digambar

    2017-05-01

    The present study involved the design and development of oral bioadhesive pellets of eplerenone. A solid dispersion of eplerenone was developed with a hydrophilic carrier, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus(®)). Bioadhesive pellets were prepared from this solid dispersion using a combination of HPMC K4M and Carbopol 934P. Both the solid dispersion and the pellets were evaluated for various physicochemical properties such as solubility, entrapment efficiency, drug content, surface morphology, mucoadhesion and swelling behavior. Analysis carried out using FT-IR, DSC and XRD found no interaction between the eplerenone and excipients. The solid dispersion had irregular-shaped smooth-surfaced particles of diameter 265 ± 105.5 μm. In TEM analysis, eplerenone particles of size 79-120 nm were found. The solubility and dissolution of eplerenone in the Soluplus(®)-based solid dispersion were 5.26 and 2.50 times greater, respectively. Investigation of the swelling behavior of the pellets showed that the thickness of the gel layer increased continuously over the duration of the study. Moreover, a correlation was observed between the thickness and strength of the gel layer and the percentage release. The mechanism of drug release was found to be non-Fickian (anomalous), with the release kinetics approaching first-order kinetics. The bioavailability of the eplerenone bioadhesive pellet formulation was studied using Wistar rats and was found to be improved. An in vivo mucoadhesion study showed that the pellets are retained for 24 h in rabbits. It was concluded that Soluplus(®) had a positive effect on the solubility and dissolution of pellets without affecting the bioadhesion.

  11. Matrix tablets: the effect of hydroxypropyl methylcellulose/anhydrous dibasic calcium phosphate ratio on the release rate of a water-soluble drug through the gastrointestinal tract I. In vitro tests.

    PubMed

    Mamani, Pseidy L; Ruiz-Caro, Roberto; Veiga, María D

    2012-12-01

    Different hydroxypropyl methylcellulose (HPMC)/anhydrous dibasic calcium phosphate (ADCP) matrix tablets have been developed aiming to evaluate the influence of both components ratio in the control release of a water-soluble drug (theophylline). In order to characterise the matrix tablets, swelling, buoyancy and dissolution studies have been carried out in different aqueous media (demineralised water, progressive pH medium, simulated gastric fluid, simulated intestinal fluid and simulated colonic fluid). The HPMC/ADCP ratio has turned out to be the determinant in the matrix behaviour: the HPMC characteristic swelling behaviour was modulated, in some cases, by the ADCP characteristic acidic dissolution. When the HPMC/ADCP ratio was ≥0.69, buoyancy, continuous swelling and low theophylline dissolution rate from the matrices (H1, H2 and H3) were observed in all dissolution media. Consequently, these formulations could be adequate as gastro-retentive drug delivery systems. Additionally, HPMC/ADCP ratio ≤0.11 (H5 and H6) induces a pH-dependent drug release which could be applied to design control drug release enteric formulations (with a suitable enteric coating). Finally, a HPMC/ADCP ratio between 0.11 and 0.69 (H4) yield a gastrointestinal controlled drug release, due to its time-dependent buoyancy (7 h) and a total drug delivery in 17 h in simulated colonic fluid.

  12. Significant decrease of ADP release rate underlies the potent activity of dimethylenastron to inhibit mitotic kinesin Eg5 and cancer cell proliferation

    SciTech Connect

    Sun, Linlin; Sun, Xiaodong; Xie, Songbo; Yu, Haiyang; Zhong, Diansheng

    2014-05-09

    Highlights: • DIMEN displays higher anti-proliferative activity than enastron. • DIMEN induced mitotic arrest and apoptosis more significantly than enastron. • DIMEN blocked the conformational change of ADP-binding pocket more effectively. • DIMEN hindered ADP release more potently than enastron. - Abstract: Eg5 is a mitotic kinesin that plays a crucial role in the formation of bipolar mitotic spindles, by hydrolyzing ATP to push apart anti-parallel microtubules. Dimethylenastron is potent specific small molecule inhibitor of Eg5. The mechanism by which dimethylenastron inhibits Eg5 function remains unclear. By comparing with enastron, here we report that dimethylenastron prevents the growth of pancreatic and lung cancer cells more effectively, by halting mitotic progression and triggering apoptosis. We analyze their interactions with ADP-bound Eg5 crystal structure, and find that dimethylenastron binds Eg5 motor domain with higher affinity. In addition, dimethylenastron allosterically blocks the conformational change of the “sandwich”-like ADP-binding pocket more effectively. We subsequently use biochemical approach to reveal that dimethylenastron slows ADP release more significantly than enastron. These data thus provide biological, structural and mechanistic insights into the potent inhibitory activity of dimethylenastron.

  13. Rad-Release

    SciTech Connect

    2011-01-01

    The R&D 100 Award winning Rad-Release Chemical Decontamination Technology is a highly effective (up to 99% removal rate), affordable, patented chemical-foam-clay decontamination process tailored to specific radiological and metal contaminants, which is applicable to a wide variety of substrates. For more information about this project, visit http://www.inl.gov/rd100/2011/rad-release/

  14. Rad-Release

    ScienceCinema

    None

    2016-07-12

    The R&D 100 Award winning Rad-Release Chemical Decontamination Technology is a highly effective (up to 99% removal rate), affordable, patented chemical-foam-clay decontamination process tailored to specific radiological and metal contaminants, which is applicable to a wide variety of substrates. For more information about this project, visit http://www.inl.gov/rd100/2011/rad-release/

  15. Development and optimization of oil-filled lipid nanoparticles containing docetaxel conjugates designed to control the drug release rate in vitro and in vivo

    PubMed Central

    Feng, Lan; Wu, Huali; Ma, Ping; Mumper, Russell J; Benhabbour, S Rahima

    2011-01-01

    Three docetaxel (DX) lipid conjugates: 2′-lauroyl-docetaxel (C12-DX), 2′-stearoyl-docetaxel (C18-DX), and 2′-behenoyl-docetaxel (C22-DX) were synthesized to enhance drug loading, entrapment, and retention in liquid oil-filled lipid nanoparticles (NPs). The three conjugates showed ten-fold higher solubility in the liquid oil phase Miglyol 808 than DX. To further increase the drug entrapment efficiency in NPs, orthogonal design was performed. The optimized formulation was composed of Miglyol 808, Brij 78, and Vitamin E tocopheryl polyethylene glycol succinate (TPGS). The conjugates were successfully entrapped in the reduced-surfactant NPs with entrapment efficiencies of about 50%–60% as measured by gel permeation chromatography (GPC) at a final concentration of 0.5 mg/mL. All three conjugates showed 45% initial burst release in 100% mouse plasma. Whereas C12-DX showed another 40% release over the next 8 hours, C18-DX and C22-DX in NPs showed no additional release after the initial burst of drug. All conjugates showed significantly lower cytotoxicity than DX in human DU-145 prostate cancer cells. The half maximal inhibitory concentration values (IC50) of free conjugates and conjugate NPs were comparable except for C22-DX, which was nontoxic in the tested concentration range and showed only vehicle toxicity when entrapped in NPs. In vivo, the total area under the curve (AUC0–∞) values of all DX conjugate NPs were significantly greater than that of Taxotere, demonstrating prolonged retention of drug in the blood. The AUC0–∞ value of DX in Taxotere was 8.3-fold, 358.0-fold, and 454.5-fold lower than that of NP-formulated C12-DX, C18-DX, and C22-DX, respectively. The results of these studies strongly support the idea that the physical/chemical properties of DX conjugates may be fine-tuned to influence the affinity and retention of DX in oil-filled lipid NPs, which leads to very different pharmacokinetic profiles and blood exposure of an otherwise potent

  16. Dry powders based on PLGA nanoparticles for pulmonary delivery of antibiotics: modulation of encapsulation efficiency, release rate and lung deposition pattern by hydrophilic polymers.

    PubMed

    Ungaro, Francesca; d'Angelo, Ivana; Coletta, Ciro; d'Emmanuele di Villa Bianca, Roberta; Sorrentino, Raffaella; Perfetto, Brunella; Tufano, Maria Antonietta; Miro, Agnese; La Rotonda, Maria Immacolata; Quaglia, Fabiana

    2012-01-10

    Although few experimental studies have been handled so far to exploit the potential of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) in the production of dry powders for antibiotic inhalation, there has been no comprehensive study on the role played by NP composition. In this work, we try to shed light on this aspect by designing and developing a pulmonary delivery system for antibiotics, such as tobramycin (Tb), based on PLGA NPs embedded in an inert microcarrier made of lactose, referred to as nano-embedded micro-particles (NEM). At nanosize level, helper hydrophilic polymers were used to impart the desired surface, bulk and release properties to PLGA NPs prepared by a modified emulsion-solvent diffusion technique. Results showed that poly(vinyl alcohol) (PVA) and chitosan (CS) are essential to optimise the size and modulate the surface properties of Tb-loaded PLGA NPs, whereas the use of alginate (Alg) allows efficient Tb entrapment within NPs and its release up to one month. Optimized formulations display good in vitro antimicrobial activity against P. aeruginosa planktonic cells. Furthermore, spray-drying of the NPs with lactose yielded NEM with peculiar but promising flow and aerosolization properties, while preserving the peculiar NP features. Nonetheless, in vivo biodistribution studies showed that PVA-modified Alg/PLGA NPs reached the deep lung, while CS-modified NPs were found in great amounts in the upper airways, lining lung epithelial surfaces. In conclusion, PLGA NP composition appears to play a crucial role in determining not only the technological features of NPs but, once processed in the form of NEM, also their in vitro/in vivo deposition pattern.

  17. Separate and Combined Effects of Naltrexone and Extended-Release Alprazolam on the Reinforcing, Subject-Rated, and Cardiovascular Effects of Methamphetamine.

    PubMed

    Marks, Katherine R; Lile, Joshua A; Stoops, William W; Glaser, Paul E A; Hays, Lon R; Rush, Craig R

    2016-06-01

    Opioid antagonists (eg, naltrexone) and positive modulators of γ-aminobutyric acid type A receptors (eg, alprazolam) each modestly attenuate the abuse-related effects of stimulants. A previous study demonstrated that acute pretreatment with the combination of naltrexone and alprazolam attenuated a greater number of the subject-rated effects of D-amphetamine than the constituent drugs alone. This study tested the hypothesis that maintenance on the combination of naltrexone and alprazolam XR would attenuate the reinforcing and "positive" subject-rated effects of methamphetamine to a greater extent than the constituent drugs alone.Eight non-treatment-seeking, stimulant-using individuals completed a placebo-controlled, crossover, double-blind inpatient protocol. Participants were maintained on naltrexone (0 and 50 mg), alprazolam XR (0 and 1 mg), and the combination of naltrexone and alprazolam XR (50 mg and 1 mg, respectively) for 6 to 7 days. Under each maintenance condition, participants sampled intranasal doses of methamphetamine (0, 10, and 30 mg), and were then offered the opportunity to work for the sampled dose on a modified progressive-ratio procedure. Subject-rated drug effect questionnaires, psychomotor, and physiology assessments were collected.Intranasal methamphetamine functioned as a reinforcer and produced prototypical stimulant-like "positive" subject-rated and physiological effects. Maintenance on naltrexone significantly decreased the reinforcing, but not subject-rated drug effects of 10-mg methamphetamine. Alprazolam XR and the combination of naltrexone and alprazolam XR did not impact methamphetamine self-administration or subject-rated drug effects. The results support the continued evaluation of naltrexone for methamphetamine dependence, as well as the identification of other drugs that enhance its ability to reduce drug-taking behavior.

  18. Drug dispersion degree and drug dissolution rate in Hybrane S1200-based instant-release matricial particles prepared by hot melt extrusion.

    PubMed

    Ravina-Eirin, Elena; Gomez-Amoza, J L; Martínez-Pacheco, Ramón

    2015-06-01

    The objective of this study is to evaluate the dissolution of a poorly soluble drug (prednisolone) from different sized matricial particles (from <250 to >1500 µm) with two drug contents (10% or 20%) obtained by hot melt extrusion using the hyperbranched polyesteramide Hybrane S1200 (water-soluble and with a Tg of 45 °C) as the carrier. X-ray diffraction, differential scanning calorimetry and SEM studies permit us to conclude that in 10% prednisolone extrudate, the drug is mainly dispersed within the carrier, whereas in those containing 20% an important fraction of the drug remains in a crystalline state and is accumulated on the surface of the extrudates. On particles proceeding from 10% drug extrudate, the drug dissolution rate is very high and slightly dependant on particle size and in all cases, higher than the pure micronized drug. However, on particles proceeding from 20% prednisolone extrudate particle size have a major effect on drug dissolution rate, attributable to higher proportions of crystalline drug accumulated on the surface, hindering polymer dissolution. Thus, the reduction of the particle size after extrudate grinding creates new surfaces from inside, that leads to strong increments on prednisolone dissolution rate, and becomes higher than the pure micronized drug one when the particle size is <250 µm.

  19. Syndactyly Release.

    PubMed

    Braun, Tara L; Trost, Jeffrey G; Pederson, William C

    2016-11-01

    Syndactyly is one of the most common congenital hand anomalies treated by pediatric plastic surgeons. Established principles of syndactyly separation dictate the timing and order of syndactyly release, with the goals of surgery being the creation of an anatomically normal webspace, tension-free closure of soft tissue, and return of function to the fingers. Numerous surgical methods have been described, many of which involve the use of local flaps to reconstruct the commissure and full-thickness skin grafts for coverage of raw areas. Recently, reconstructive techniques without the use of skin grafts have been devised, which work well for certain indications. Special considerations are described for complete, complex, and syndromic syndactylies. Outcomes for simple syndactyly release are typically good when surgical principles are followed, whereas complex syndactyly release tends to have less-favorable outcomes and more complications.

  20. The influence of hook type, angler experience, and fish size on injury rates and the duration of capture in an Alaskan catch-and-release rainbow trout fishery

    USGS Publications Warehouse

    Meka, Julie M.

    2004-01-01

    Owing to concerns about the high incidence of past hooking injuries in Alagnak River rainbow trout Oncorhynchus mykiss, fish were captured with spin- and fly-fishing gear with barbed and barbless circle and "J" hooks to determine gear types contributing to injury. Landing and hook removal times were measured for a portion of fish captured, and the anatomical hooking location, hooking scar locations, bleeding intensity, angler experience, and fish size were recorded for all captured fish. Approximately 62% of fish captured experienced at least one new hooking injury, and 29% of fish had at least one past hooking injury. Small fish sustained higher new injury and bleeding rates, but large fish had higher past injury rates. Injury rates were higher for barbed J hooks, barbed J hooks took longer to remove, and fish caught by spin-fishing were injured more frequently than fish caught by fly-fishing. Fewer fly-fishing-caught fish were injured using circle hooks, and circle hooks tended to hook fish in only one location, generally in the jaw. Barbed J hooks were more efficient at landing fish, and J hooks were more efficient at landing fish than circle hooks. Novice anglers injured proportionally more fish than experienced anglers, primarily during hook removal. Landing time was positively correlated with fish size, and experienced anglers took longer to land fish than novices because they captured larger fish. These results suggest that a reduction in hooking injuries may be achieved by using circle hooks as an alternative to J hooks and barbless J hooks to reduce injury and handling time, yet catch efficiency for both methods would be reduced. Although fish captured with barbless J hooks and circle hooks had fewer injuries, it is important to note that each hook type also caused significant injury, and angler education is recommended to promote proper hook removal techniques.

  1. Boar taint, meat quality and fail rate in entire male pigs and male pigs immunized against gonadotrophin releasing factor as related to body weight and feeding regime.

    PubMed

    Moore, K L; Mullan, B P; Dunshea, F R

    2017-03-01

    The objective of this experiment was to compare the pork quality of entire male pigs and pigs immunized against GnRF (IC males) at both light (64.8kg) and heavy (106kg) liveweights and two feeding regimes (restricted at 2.5 times maintenance and ad libitum). There was no difference in objective measurements (P>0.05) or eating pork quality (P>0.1) between entire male and IC males. Fail rates were reduced by 9.1% and 12% for pork from IC males for quality grade (P=0.007) and re-purchase intention (P=0.001), respectively, compared to pork from entire males. Skatole (P=0.001) and androstenone (P<0.001) levels in belly fat were higher in entire male than IC male pigs. In addition, 37.5% of the light entire male pigs fed ad libitum showed skatole levels that exceeded the sensory threshold of 0.2μg/g. This work confirms that immunization against GnRF is effective in eliminating boar taint and reducing pork quality fail rates by approximately 10% compared to pork from entire males.

  2. Toggle release

    NASA Technical Reports Server (NTRS)

    Graves, Thomas J. (Inventor); Yang, Robert A. (Inventor); Brown, Christopher W. (Inventor)

    1989-01-01

    A pyrotechnic actuated structural release device 10 which is mechanically two fault tolerant for release. The device 10 comprises a fastener plate 11 and fastener body 12, each attachable to a different one of a pair of structures to be joined. The fastener plate 11 and body 12 are fastenable by a toggle 13 supported at one end on the fastener plate and mounted for universal pivotal movement thereon. At its other end which is received in a central opening in the fastener body 12 and adapted for limited pivotal movement therein the toggle 13 is restrained by three retractable latching pins 61 symmetrically disposed in equiangular spacing about the axis of the toggle 13 and positionable in latching engagement with an end fitting on the toggle. Each pin 61 is individually retractable by combustion of a pyrotechnic charge 77, the expanding gases of which are applied to a pressure receiving face 67 on the latch pin 61 to effect its retraction from the toggle. While retraction of all three pins 62 releases the toggle, the fastener is mechanically two fault tolerant since the failure of any single one or pair of the latch pins to retract results in an asymmetrical loading on the toggle and its pivotal movement to effect a release. An annular bolt 18 is mounted on the fastener plate 11 as a support for the socket mounting 30, 37 of the toggle whereby its selective axial movement provides a means for preloading the toggle.

  3. Nitrogen release during coal combustion

    SciTech Connect

    Baxter, L.L.; Mitchell, R.E.; Fletcher, T.H.; Hurt, R.H.

    1995-02-01

    Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99% on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release rate relative to that of carbon and mass increases, with fractional nitrogen release rates exceeding fractional mass and fractional carbon release rates during devolatilization for high-rank (low-volatile bituminous) coals. At the onset of combustion, nitrogen release rates increase significantly. For all coals investigated, cumulative fractional nitrogen loss rates relative to those of mass and carbon passes through a maximum during the earliest stages of oxidation. The mechanism for generating this maximum is postulated to involve nascent thermal rupture of nitrogen-containing compounds and possible preferential oxidation of nitrogen sites. During later stages of oxidation, the cumulative fractional loss of nitrogen approaches that of carbon for all coals. Changes in the relative release rates of nitrogen compared to those of both overall mass and carbon during all stages of combustion are attributed to a combination of the chemical structure of coals, temperature histories during combustion, and char chemistry.

  4. Cluster-root formation and carboxylate release in three Lupinus species as dependent on phosphorus supply, internal phosphorus concentration and relative growth rate

    PubMed Central

    Wang, Xing; Pearse, Stuart J.; Lambers, Hans

    2013-01-01

    Background and Aims Some Lupinus species produce cluster roots in response to low plant phosphorus (P) status. The cause of variation in cluster-root formation among cluster-root-forming Lupinus species is unknown. The aim of this study was to investigate if cluster-root formation is, in part, dependent on different relative growth rates (RGRs) among Lupinus species when they show similar shoot P status. Methods Three cluster-root-forming Lupinus species, L. albus, L. pilosus and L. atlanticus, were grown in washed river sand at 0, 7·5, 15 or 40 mg P kg−1 dry sand. Plants were harvested at 34, 42 or 62 d after sowing, and fresh and dry weight of leaves, stems, cluster roots and non-cluster roots of different ages were measured. The percentage of cluster roots, tissue P concentrations, root exudates and plant RGR were determined. Key Results Phosphorus treatments had major effects on cluster-root allocation, with a significant but incomplete suppression in L. albus and L. pilosus when P supply exceeded 15 mg P kg−1 sand. Complete suppression was found in L. atlanticus at the highest P supply; this species never invested more than 20 % of its root weight in cluster roots. For L. pilosus and L. atlanticus, cluster-root formation was decreased at high internal P concentration, irrespective of RGR. For L. albus, there was a trend in the same direction, but this was not significant. Conclusions Cluster-root formation in all three Lupinus species was suppressed at high leaf P concentration, irrespective of RGR. Variation in cluster-root formation among the three species cannot be explained by species-specific variation in RGR or leaf P concentration. PMID:24061491

  5. Cortisol release, heart rate and heart rate variability, and superficial body temperature, in horses lunged either with hyperflexion of the neck or with an extended head and neck position.

    PubMed

    Becker-Birck, M; Schmidt, A; Wulf, M; Aurich, J; von der Wense, A; Möstl, E; Berz, R; Aurich, C

    2013-04-01

    Bringing the head and neck of ridden horses into a position of hyperflexion is widely used in equestrian sports. In our study, the hypothesis was tested that hyperflexion is an acute stressor for horses. Salivary cortisol concentrations, heart rate, heart rate variability (HRV) and superficial body temperature were determined in horses (n = 16) lunged on two subsequent days. The head and neck of the horse was fixed with side reins in a position allowing forward extension on day A and fixed in hyperflexion on day B. The order of treatments alternated between horses. In response to lunging, cortisol concentration increased (day A from 0.73 ± 0.06 to 1.41 ± 0.13 ng/ml, p < 0.001; day B from 0.68 ± 0.07 to 1.38 ± 0.13 ng/ml, p < 0.001) but did not differ between days A and B. Beat-to-beat (RR) interval decreased in response to lunging on both days. HRV variables standard deviation of RR interval (SDRR) and RMSSD (root mean square of successive RR differences) decreased (p < 0.001) but did not differ between days. In the cranial region of the neck, the difference between maximum and minimum temperature was increased in hyperflexion (p < 0.01). In conclusion, physiological parameters do not indicate an acute stress response to hyperflexion of the head alone in horses lunged at moderate speed and not touched with the whip. However, if hyperflexion is combined with active intervention of a rider, a stressful experience for the horse cannot be excluded.

  6. Controlled-release microchips.

    PubMed

    Sharma, Sadhana; Nijdam, A Jasper; Sinha, Piyush M; Walczak, Robbie J; Liu, Xuewu; Cheng, Mark M-C; Ferrari, Mauro

    2006-05-01

    Efficient drug delivery remains an important challenge in medicine: continuous release of therapeutic agents over extended time periods in accordance with a predetermined temporal profile; local delivery at a constant rate to the tumour microenvironment to overcome much of the systemic toxicity and to improve antitumour efficacy; improved ease of administration, and increasing patient compliance required are some of the unmet needs of the present drug delivery technology. Microfabrication technology has enabled the development of novel controlled-release microchips with capabilities not present in the current treatment modalities. In this review, the current status and future prospects of different types of controlled-release microchips are summarised and analysed with reference to microneedle-based microchips, as well as providing an in-depth focus on microreservoir-based and nanoporous microchips.

  7. Increased Release of Mercury from Dental Amalgam Fillings due to Maternal Exposure to Electromagnetic Fields as a Possible Mechanism for the High Rates of Autism in the Offspring: Introducing a Hypothesis.

    PubMed

    Mortazavi, Gh; Haghani, M; Rastegarian, N; Zarei, S; Mortazavi, S M J

    2016-03-01

    According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields.  Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring.

  8. Increased Release of Mercury from Dental Amalgam Fillings due to Maternal Exposure to Electromagnetic Fields as a Possible Mechanism for the High Rates of Autism in the Offspring: Introducing a Hypothesis

    PubMed Central

    Mortazavi, Gh.; Haghani, M.; Rastegarian, N.; Zarei, S.; Mortazavi, S.M.J.

    2016-01-01

    According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields.  Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring. PMID:27026954

  9. A rapid technique for prediction of nutrient release from controlled release fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient release from soluble granular fertilizers can be modified by polymer coating to extend the total duration nutrient release up to 3 to 9 months and rate of release to match the nutrient requirement of the plant during the growing period. Hence these products are termed as “Controlled Release...

  10. Determination of the uptake and release rates of multifamilies of endocrine disruptor compounds on the polar C18 Chemcatcher. Three potential performance reference compounds to monitor polar pollutants in surface water by integrative sampling.

    PubMed

    Camilleri, J; Morin, N; Miège, C; Coquery, M; Cren-Olivé, C

    2012-05-11

    The uptake kinetics of 27 emerging pollutants on the polar C18 Chemcatcher have been investigated. This investigation determined the sampling rates of 20 compounds, including 16 endocrine disruptors and 4 pharmaceuticals, which were used as overall pollution indicators. Calibrations were completed in a 50-L flow-through microcosm with continuous renewal of tap water spiked with approximately 3 μg/L of each pollutant and with sampling times at 1, 3, 6 and 12h and 1, 3, 7, 14, 21 and 28 days. Exponential regressions for the accumulation kinetics were plotted to confirm the maximum linear uptake times for each molecule using the half time of equilibrium (t(1/2)) criteria. Of the compounds tested, 17 were accumulated linearly for up to 14 or 21 days with an R(2) above 0.98 for linear correlations. The evaluation of the release kinetics of a C18 Chemcatcher spiked with 20 deuterated compounds identified 3 potential performance reference compounds (PRCs) with exponential desorption rates showing relatively good isotropic exchange.

  11. Non-Toxic, Self Cleaning Silicone Fouling Release Coatings

    DTIC Science & Technology

    2007-11-02

    Attempts to microencapsulate silicone oils for enhanced fouling release coatings with thermoset wall structures were unsuccessful: Microcapsule ...filled coatings failed abrasion resistance tests and had mediocre fouling release properties, despite having controlled release rates. Microcapsules with

  12. Effects of Experimental High Flow Releases and Increased Fluctuations in Flow from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lee's Ferry Reach of the Colorado River

    NASA Astrophysics Data System (ADS)

    Korman, Josh

    2010-05-01

    The abundance of adult fish populations is controlled by the growth and survival rates of early life stages. Evaluating the effects of flow regimes on early life stages is therefore critical to determine how these regimes affect the abundance of adult populations. Experimental high flow releases from Glen Canyon Dam, primarily intended to conserve fine sediment and improve habitat conditions for native fish in the Colorado River in Grand Canyon, AZ, have been conducted in 1996, 2004, and 2008. These flows potentially affect the Lee's Ferry reach rainbow trout population, located immediately downstream of the dam, which supports a highly valued fishery and likely influences the abundance of rainbow trout in Grand Canyon. Due to concerns about negative effects of high trout abundance on endangered native fish, hourly variation in flow from Glen Canyon Dam was experimentally increased between 2003 and 2005 to reduce trout abundance. This study reports on the effects of experimental high flow releases and fluctuating flows on early life stages of rainbow trout in the Lee's Ferry reach based on monthly sampling of redds (egg nests) and the abundance and growth of age-0 trout between 2003 and 2009. Data on spawn timing, spawning elevations, and intergravel temperatures were integrated in a model to estimate the magnitude and seasonal trend in incubation mortality resulting from redd dewatering due to fluctuations in flow. Experimental fluctuations from January through March promoted spawning at higher elevations where the duration of dewatering was longer and intergravel temperatures exceeded lethal thresholds. Flow-dependent incubation mortality rates were 24% (2003) and 50% (2004) in years with higher flow fluctuations, compared to 5-11% under normal operations (2006-2009). Spatial and temporal predictions of mortality were consistent with direct observations of egg mortality determined from the excavation of 125 redds. The amount of variation in backcalculated hatch

  13. Rate of tuberculosis infection in children and adolescents with household contact with adults with active pulmonary tuberculosis as assessed by tuberculin skin test and interferon-gamma release assays.

    PubMed

    Ferrarini, M A G; Spina, F G; Weckx, L Y; Lederman, H M; De Moraes-Pinto, M I

    2016-03-01

    Tuberculosis (TB) infection was evaluated in Brazilian immunocompetent children and adolescents exposed and unexposed (control group) to adults with active pulmonary TB. Both groups were analysed by clinical and radiological assessment, TST, QFT-IT and T-SPOT.TB. The three tests were repeated after 8 weeks in the TB-exposed group if results were initially negative. Individuals with latent tuberculosis infection (LTBI) were treated and tests were repeated after treatment. Fifty-nine TB-exposed and 42 controls were evaluated. Rate of infection was 69·5% and 9·5% for the exposed and control groups, respectively. The exposed group infection rate was 61% assessed by TST, 57·6% by T-SPOT.TB, and 59·3%, by QFT-IT. No active TB was diagnosed. Agreement between the three tests was 83·1% and 92·8% in the exposed and control groups, respectively. In the exposed group, T-SPOT.TB added four TB diagnoses [16%, 95% confidence interval (CI) 1·6-30·4] and QFT-IT added three TB diagnoses (12%, 95% CI 0-24·7) in 25 individuals with negative tuberculin skin test (TST). Risk factors associated to TB infection were contact with an adult with active TB [0-60 days: odds ratio (OR) 6·9; >60 days: OR 27·0] and sleeping in the same room as an adult with active TB (OR 5·2). In Brazilian immunocompetent children and adolescents, TST had a similar performance to interferon-gamma release assays and detected a high rate of LTBI.

  14. Quantification of Energy Release in Composite Structures

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C. (Technical Monitor)

    2003-01-01

    Energy release rate is usually suggested as a quantifier for assessing structural damage tolerance. Computational prediction of energy release rate is based on composite mechanics with micro-stress level damage assessment, finite element structural analysis and damage progression tracking modules. This report examines several issues associated with energy release rates in composite structures as follows: Chapter I demonstrates computational simulation of an adhesively bonded composite joint and validates the computed energy release rates by comparison with acoustic emission signals in the overall sense. Chapter II investigates the effect of crack plane orientation with respect to fiber direction on the energy release rates. Chapter III quantifies the effects of contiguous constraint plies on the residual stiffness of a 90 deg ply subjected to transverse tensile fractures. Chapter IV compares ICAN and ICAN/JAVA solutions of composites. Chapter V examines the effects of composite structural geometry and boundary conditions on damage progression characteristics.

  15. Quantification of Energy Release in Composite Structures

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon

    2003-01-01

    Energy release rate is usually suggested as a quantifier for assessing structural damage tolerance. Computational prediction of energy release rate is based on composite mechanics with micro-stress level damage assessment, finite element structural analysis and damage progression tracking modules. This report examines several issues associated with energy release rates in composite structures as follows: Chapter I demonstrates computational simulation of an adhesively bonded composite joint and validates the computed energy release rates by comparison with acoustic emission signals in the overall sense. Chapter II investigates the effect of crack plane orientation with respect to fiber direction on the energy release rates. Chapter III quantifies the effects of contiguous constraint plies on the residual stiffness of a 90 ply subjected to transverse tensile fractures. Chapter IV compares ICAN and ICAN/JAVA solutions of composites. Chapter V examines the effects of composite structural geometry and boundary conditions on damage progression characteristics.

  16. Added release time in diffusion/dissolution coupled release.

    PubMed

    Nuxoll, Eric

    2015-10-15

    While increasingly sophisticated models have been developed to more accurately predict dispersed solute release from complex systems, distillation of their results into quantitative trends has been difficult. Here, the numerically calculated release profiles of coupled diffusion/dissolution systems are quantified by their cumulative release time (CRT) and compared against corresponding diffusion-controlled limits. The increase in CRT due to a finite dissolution rate was found to vary inversely with the second Damköhler number across several orders of magnitude, and also vary linearly with the amount of solid drug loaded in the system. The analytical nature of the relationship provides new physical insights into the system and appears to be indifferent to the form of the secondary rate-limiting step. This work provides a simple analytical expression with which one can not only predict the mean release time for a given set of parameter values, but understand precisely how each parameter value will affect it. The simplicity of the correlation and the lack of apparent limits to its validity also suggest the existence of an analytical pathway for its derivation, which may yield additional insights into the effect of secondary rate processes on controlled release.

  17. Salt release from potato crisps.

    PubMed

    Tian, Xing; Fisk, Ian D

    2012-04-01

    The rate of salt release in-mouth from salted potato crisps was evaluated. It was hypothesised that a slow steady release of sodium would occur on chewing and hydration; to test this a crisp was chewed and held in the oral cavity without swallowing for 60 s. Sodium release was measured over the entire holding period, after 20-30 s a peak in salivary sodium levels was recorded. A similar trend was observed with sensory perceived saltiness by trained panellists. The results suggest that a significant proportion of the crisp's salt flavouring is released in a pulse-type mechanism which would not be encountered when the crisp is exposed to normal eating patterns and would result in the consumption of a large proportion of unperceived sodium.

  18. A Rapid Test for Prediction of Nutrient Release from Controlled Release Fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient release from soluble granular fertilizers can be modified by polymer coating. The coating technology can be fine-tuned to change the duration (3 to 9 months) and rate of nutrient release, hence these products are termed as controlled release fertilizers (CRF). There is a need to develop a r...

  19. Modelling and analysis of impulsive releases of sterile mosquitoes.

    PubMed

    Huang, Mingzhan; Song, Xinyu; Li, Jia

    2017-12-01

    To study the impact of releasing sterile mosquitoes on mosquito-borne disease transmissions, we propose two mathematical models with impulsive releases of sterile mosquitoes. We consider periodic impulsive releases in the first model and obtain the existence, uniqueness, and globally stability of a wild-mosquito-eradication periodic solution. We also establish thresholds for the control of the wild mosquito population by selecting the release rate and the release period. In the second model, the impulsive releases are determined by the closely monitored wild mosquito density, or the state feedback. We prove the existence of an order one periodic solution and find a relatively small attraction region, which ensures the wild mosquito population is under control. We provide numerical analysis which shows that a smaller release rate and more frequent releases are more efficient in controlling the wild mosquito population for the periodic releases, but an early release of sterile mosquitoes is more effective for the state feedback releases.

  20. 103 INFLUENCE OF ESTRUS EXPRESSION AND TREATMENT WITH GONADOTROPIN-RELEASING HORMONE ON PREGNANCY RATES IN RECIPIENTS SYNCHRONIZED WITH PROGESTERONE DEVICES AND ESTRADIOL AND TRANSFERRED AT A FIXED TIME.

    PubMed

    Cedeño, A; Tribulo, A; Andrada, S; Barajas, J L; Fonseca, J; Ruiz, A; Tribulo, R; Tribulo, H; Mapletoft, R J; Bó, G A

    2016-01-01

    An experiment was designed to evaluate whether expression of oestrus in recipients synchronized with progesterone devices and oestradiol affects pregnancy rates to a fixed-time embryo transfer (FTET). A secondary objective was to determine whether administration of gonadotropin-releasing hormone (GnRH) to those recipients not showing oestrus by 48h after device removal had an effect on pregnancy rates. Mature, non-lactating beef recipients (Bonsmara, Brangus, and Braford; n=729), with a corpus luteum (CL) or a follicle ≥8mm in diameter detected by ultrasonography (Mindray DP 30, Shenzhen, China) and body condition score 2 to 4 (1 to 5 scale) were synchronized in 7 replicates. On Day 0, recipients received a progesterone device (DIB 0.5g, Zoetis, Buenos Aires, Argentina) and 2mg of oestradiol benzoate (Gonadiol, Zoetis). On Day 8, DIB were removed and recipients received 400IU eCG (Novormon 5000, Zoetis) plus 0.5mg of oestradiol cypionate (Cipiosyn, Zoetis) and 500μg of cloprostenol (Cyclase, Zoetis). In addition, all cows were tail-painted on the sacrococcygeal area (CeloTest, Biotay, Buenos Aires, Argentina) at DIB removal and were observed to determine the expression of oestrus, according to the percentage of paint loss 48h later. The animals that showed oestrus (paint loss >30%) were recorded, and those with paint loss ≤30% (not in oestrus) were randomly allocated to receive 100μg of gonadorelin (GnRH; Gonasyn, Zoetis) or no treatment. On Day 17, all recipients were examined by ultrasonography and those with a CL ≥18mm (G1), ≥16 and <18mm (G2), or ≥14 and <16mm (G3) in diameter received in vivo-produced frozen-thawed embryos by direct transfer or fresh in vitro-produced embryos. Pregnancy was diagnosed by ultrasonography at 23 days after FTET, and data were analysed by logistic regression. There were no differences between replicates, in vivo- and in vitro-produced embryos, or operators (P>0.2). However, the proportion of recipients transferred and

  1. Observed Barium Emission Rates

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  2. Cholecystokinin facilitates glutamate release by increasing the number of readily releasable vesicles and releasing probability.

    PubMed

    Deng, Pan-Yue; Xiao, Zhaoyang; Jha, Archana; Ramonet, David; Matsui, Toshimitsu; Leitges, Michael; Shin, Hee-Sup; Porter, James E; Geiger, Jonathan D; Lei, Saobo

    2010-04-14

    Cholecystokinin (CCK), a neuropeptide originally discovered in the gastrointestinal tract, is abundantly distributed in the mammalian brains including the hippocampus. Whereas CCK has been shown to increase glutamate concentration in the perfusate of hippocampal slices and in purified rat hippocampal synaptosomes, the cellular and molecular mechanisms whereby CCK modulates glutamatergic function remain unexplored. Here, we examined the effects of CCK on glutamatergic transmission in the hippocampus using whole-cell recordings from hippocampal slices. Application of CCK increased AMPA receptor-mediated EPSCs at perforant path-dentate gyrus granule cell, CA3-CA3 and Schaffer collateral-CA1 synapses without effects at mossy fiber-CA3 synapses. CCK-induced increases in AMPA EPSCs were mediated by CCK-2 receptors and were not modulated developmentally and transcriptionally. CCK reduced the coefficient of variation and paired-pulse ratio of AMPA EPSCs suggesting that CCK facilitates presynaptic glutamate release. CCK increased the release probability and the number of readily releasable vesicles with no effects on the rate of recovery from vesicle depletion. CCK-mediated increases in glutamate release required the functions of phospholipase C, intracellular Ca(2+) release and protein kinase Cgamma. CCK released endogenously from hippocampal interneurons facilitated glutamatergic transmission. Our results provide a cellular and molecular mechanism to explain the roles of CCK in the brain.

  3. Delayed simultaneous release mechanism

    NASA Technical Reports Server (NTRS)

    Moyer, X. W.; Webb, J. B. (Inventor)

    1973-01-01

    The disclosed appendage release mechanism is particularly adapted for use with spacecraft operating with despin mechanisms and releasable appendages. It includes a flexible loop and a number of appendage releasing devices which are attached to the flexible loop. The appendage releasing devices are made up of piston-cams and ball latches which hold the appendages as long as the flexible loop is maintained in a taut condition, but which release the appendages upon relaxation of the flexible loop. The flexible loop remains taut as long as the despin weights remain attached, but relaxes when the despin weights are released.

  4. Payload holddown and release mechanism

    NASA Technical Reports Server (NTRS)

    Chaput, Dale; Visconti, Mark; Edwards, Michael; Moran, Tom

    1994-01-01

    A payload holddown and release mechanism, designated the Model 1172, was designed and built at G&H Technology during the winter of 1992/1993. The mechanism is able to restrain and release a 45-pound payload with minimal tipoff. The payload is held in place by a stainless steel band and released using electrically triggered non-explosive actuators. These actuators provide reliable operation with negligible shock and no special handling requirements. The performance of the mechanism was demonstrated in two flight tests. Data showed pitch and yaw tipoff rates of less than 0.07 radian (4 degree) per second. The Model 1172 design is an efficient replacement for conventional payload deployment devices, especially where low transmitted shock is required.

  5. Nanostructured Diclofenac Sodium Releasing Material

    NASA Astrophysics Data System (ADS)

    Nikkola, L.; Vapalahti, K.; Harlin, A.; Seppälä, J.; Ashammakhi, N.

    2008-02-01

    Various techniques have been developed to produce second generation biomaterials for tissue repair. These include extrusion, molding, salt leaching, spinning etc, but success in regenerating tissues has been limited. It is important to develop porous material, yet with a fibrous structure for it to be biomimetic. To mimic biological tissues, the extra-cellular matrix usually contains fibers in nano scale. To produce nanostructures, self-assembly or electrospinning can be used. Adding a drug release function to such a material may advance applications further for use in controlled tissue repair. This turns the resulting device into a multifunctional porous, fibrous structure to support cells and drug releasing properties in order to control tissue reactions. A bioabsorbable poly(ɛ-caprolactone-co-D,L lactide) 95/5 (PCL) was made into diluted solution using a solvent, to which was added 2w-% of diclofenac sodium (DS). Nano-fibers were made by electrospinning onto substrate. Microstructure of the resulting nanomat was studied using SEM and drug release profiles with UV/VIS spectroscopy. Thickness of the electrospun nanomat was about 2 mm. SEM analysis showed that polymeric nano-fibers containing drug particles form a highly interconnected porous nano structure. Average diameter of the nano-fibers was 130 nm. There was a high burst peak in drug release, which decreased to low levels after one day. The used polymer has slow a degradation rate and though the nanomat was highly porous with a large surface area, drug release rate is slow. It is feasible to develop a nano-fibrous porous structure of bioabsorbable polymer, which is loaded with test drug. Drug release is targeted at improving the properties of biomaterial for use in controlled tissue repair and regeneration.

  6. CERCLA and EPCRA Continuous Release Reporting

    EPA Pesticide Factsheets

    Congress established reportable quantities for Superfund hazardous substances. A continuous release of a hazardous substance is defined as being without interruption or abatement and stable in quantity and rate.

  7. Minimum Release of Tributyltin to Prevent Macrofouling

    DTIC Science & Technology

    1990-10-01

    identify by block number) The minimum release of tni-and dibutyltin has been determined for both barnacles and hydrozoans. The test method involved...prevented hydrozoans from attaching. No minimum release rate could be calculated for the dibutyltin because the flux rates were not high enoughi to achieve a...DATA FOR SETTLEMENT WITH TRI- AND DIBUTYLTIN ........................................... 13 FIGURES 1. Percent settlement of barnacles relative to

  8. Dust release from surfaces exposed to plasma

    SciTech Connect

    Flanagan, T. M.; Goree, J.

    2006-12-15

    Micrometer-sized particles adhered to a surface can be released when exposed to plasma. In an experiment with a glass surface coated with lunar-simulant dust, it was found that particle release requires exposure to both plasma and an electron beam. The dust release rate diminishes almost exponentially in time, which is consistent with a random process. As proposed here, charges of particles adhered to the surface fluctuate. These charges experience a fluctuating electric force that occasionally overcomes the adhesive van der Waals force, causing particle release. The release rate increases with plasma density, so that plasma cleaning is feasible at high plasma densities. Applications of this cleaning include controlling particulate contamination in semiconductor manufacturing, dust mitigation in the exploration of the moon and Mars, and dusty plasmas.

  9. Release Data Package for Hanford Site Assessments

    SciTech Connect

    Riley, Robert G.; Lopresti, Charles A.; Engel, David W.

    2006-07-01

    Beginning in fiscal year (FY) 2003, the U.S. Department of Energy (DOE) Richland Operations Office initiated activities, including the development of data packages, to support a Hanford assessment. This report describes the data compiled in FY 2003 through 2005 to support the Release Module of the System Assessment Capability (SAC) for the updated composite analysis. This work was completed as part of the Characterization of Systems Project, part of the Remediation and Closure Science Project, the Hanford Assessments Project, and the Characterization of Systems Project managed by Pacific Northwest National Laboratory. Related characterization activities and data packages for the vadose zone and groundwater are being developed under the remediation Decision Support Task of the Groundwater Remediation Project managed by Fluor Hanford, Inc. The Release Module applies release models to waste inventory data from the Inventory Module and accounts for site remediation activities as a function of time. The resulting releases to the vadose zone, expressed as time profiles of annual rates, become source terms for the Vadose Zone Module. Radioactive decay is accounted for in all inputs and outputs of the Release Module. The Release Module is implemented as the VADER (Vadose zone Environmental Release) computer code. Key components of the Release Module are numerical models (i.e., liquid, soil-debris, cement, saltcake, and reactor block) that simulate contaminant release from the different waste source types found at the Hanford Site. The Release Module also handles remediation transfers to onsite and offsite repositories.

  10. ELECTROMAGNETIC RELEASE MECHANISM

    DOEpatents

    Michelson, C.

    1960-09-13

    An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.

  11. Multicomponent Implant Releasing Dexamethasone

    NASA Astrophysics Data System (ADS)

    Nikkola, L.; Vapalahti, K.; Ashammakhi, N.

    2008-02-01

    Several inflammatory conditions are usually treated with corticosteroids. There are various problems like side effects with traditional applications of steroids, e.g. topical, or systemic routes. Local drug delivery systems have been studied and developed to gain more efficient administration with fewer side effects. Earlier, we reported on developing Dexamethasone (DX) releasing biodegradable fibers. However, their drug release properties were not satisfactory in terms of onset of drug release. Thus, we assessed the development of multicomponent (MC) implant to enhance earlier drug release from such biodegradable fibers. Poly (lactide-co-glycolide) (PLGA) and 2 wt-% and 8 wt-% DX were compounded and extruded with twin-screw extruder to form of fibers. Some of the fibers were sterilized to obtain a change in drug release properties. Four different fiber classes were studied: 2 wt-%, 8 wt-%, sterilized 2 wt-%, and sterilized 8 wt-%. 3×4 different DX-releasing fibers were then heat-pressed to form one multicomponent rod. Half of the rods where sterilized. Drug release was measured from initial fibers and multicomponent rods using a UV/VIS spectrometer. Shear strength and changes in viscosity were also measured. Drug release studies showed that drug release commenced earlier from multicomponent rods than from component fibers. Drug release from multicomponent rods lasted from day 30 to day 70. The release period of sterilized rods extended from day 23 to day 57. When compared to the original component fibers, the drug release from MC rods commenced earlier. The initial shear strength of MC rods was 135 MPa and decreased to 105 MPa during four weeks of immersion in phosphate buffer solution. Accordingly, heat pressing has a positive effect on drug release. After four weeks in hydrolysis, no disintegration was observed.

  12. Effect of transfer of one or two in vitro-produced embryos and post-transfer administration of gonadotropin releasing hormone on pregnancy rates of heat-stressed dairy cattle.

    PubMed

    Franco, M; Block, J; Jousan, F D; de Castro e Paula, L A; Brad, A M; Franco, J M; Grisel, F; Monson, R L; Rutledge, J J; Hansen, P J

    2006-07-15

    Pregnancy rates following transfer of an in vitro-produced (IVP) embryo are often lower than those obtained following transfer of an embryo produced by superovulation. The purpose of the current pair of experiments was to examine two strategies for increasing pregnancy rates in heat stressed, dairy recipients receiving an IVP embryo. One method was to transfer two embryos into the uterine horn ipsilateral to the CL, whereas the other method involved injection of GnRH at Day 11 after the anticipated day of ovulation. In Experiment 1, 32 virgin crossbred heifers and 26 lactating crossbred cows were prepared for timed embryo transfer by being subjected to a timed ovulation protocol. Those having a palpable CL were randomly selected to receive one (n = 31 recipients) or two (n = 27 recipients) embryos on Day 7 after anticipated ovulation. At Day 64 of gestation, the pregnancy rate tended to be higher (P = 0.07) for cows than for heifers. Heifers that received one embryo tended to have a higher pregnancy rate than those that received two embryos (41% versus 20%, respectively) while there was no difference in pregnancy rate for cows that received one or two embryos (57% versus 50%, respectively). Pregnancy loss between Day 64 and 127 only occurred for cows that received two embryos (pregnancy rate at Day 127=17%). Between Day 127 and term, one animal (a cow with a single embryo) lost its pregnancy. There was no difference in pregnancy rates at Day 127 or calving rates between cows and heifers, but females that received two embryos had lower Day-127 pregnancy rates and calving rates than females that received one embryo (P < 0.03). Of the females receiving two embryos that calved, 2 of 5 gave birth to twins. For Experiment 2, 87 multiparous, late lactation, nonpregnant Holstein cows were synchronized for timed embryo transfer as in Experiment 1. Cows received a single embryo in the uterine horn ipsilateral to the ovary containing the CL and received either 100 microg Gn

  13. Use of insulin-like growth factor-I during embryo culture and treatment of recipients with gonadotropin-releasing hormone to increase pregnancy rates following the transfer of in vitro-produced embryos to heat-stressed, lactating cows.

    PubMed

    Block, J; Drost, M; Monson, R L; Rutledge, J J; Rivera, R M; Paula-Lopes, F F; Ocon, O M; Krininger, C E; Liu, J; Hansen, P J

    2003-06-01

    An experiment was conducted to determine whether pregnancy rates following the transfer of in vitro-produced embryos to heat-stressed cows could be improved by 1) culturing embryos in the presence of IGF-I and 2) treating recipients with GnRH. Lactating Holstein cows (n = 260) were synchronized using a timed ovulation protocol. Embryos were produced in vitro and cultured with or without 100 ng/mL of IGF-I. On d 7 after anticipated ovulation (d 0), a single embryo was transferred to all recipients with a palpable corpus luteum (n = 210). A subset of recipients (n = 164) was injected with either GnRH or placebo on d 11. Plasma progesterone concentrations on d 0 and 7 were used to determine the synchrony of recipients. Pregnancy was diagnosed at d 53 and 81 by rectal palpation. Among all recipients, transfer of IGF-I-treated embryos increased pregnancy rate at d 53 (P < 0.05) and tended to increase pregnancy rate at d 81 (P < 0.06). Calving rate also tended to be higher for recipients that received IGF-I-treated embryos (P < 0.07). Among the subset of synchronized recipients (n = 190), pregnancy rate at d 53 and d 81 and calving rate were higher (P < 0.05) for IGF-I-treated embryos. The GnRH tended to increase pregnancy rate at d 53 for all recipients (P < 0.08) and the subset of synchronized recipients (P < 0.10). There were no effects of GnRH (P > 0.10) for pregnancy rate at d 81 and calving rate. The overall proportion of male calves was 64.3%. There was no effect (P > 0.10) of embryo treatment or GnRH on the birth weight or sex ratio of calves. Results of this experiment indicate that treatment of embryos with IGF-I can improve pregnancy and calving rates following transfer of in vitro-produced embryos. Further research is necessary to determine whether the treatment of recipients with GnRH is a practical approach to increase pregnancy rates following in vitro embryo transfer.

  14. Dendritic Release of Neurotransmitters.

    PubMed

    Ludwig, Mike; Apps, David; Menzies, John; Patel, Jyoti C; Rice, Margaret E

    2016-12-06

    Release of neuroactive substances by exocytosis from dendrites is surprisingly widespread and is not confined to a particular class of transmitters: it occurs in multiple brain regions, and includes a range of neuropeptides, classical neurotransmitters, and signaling molecules, such as nitric oxide, carbon monoxide, ATP, and arachidonic acid. This review is focused on hypothalamic neuroendocrine cells that release vasopressin and oxytocin and midbrain neurons that release dopamine. For these two model systems, the stimuli, mechanisms, and physiological functions of dendritic release have been explored in greater detail than is yet available for other neurons and neuroactive substances. © 2017 American Physiological Society. Compr Physiol 7:235-252, 2017.

  15. Release the Body, Release the Mind.

    ERIC Educational Resources Information Center

    Stoner, Martha Goff

    1998-01-01

    A college English teacher describes the anxiety and resentment of students during in-class writing assignments and the successful classroom use of meditation and body movement. Movement seemed to relax the students, change their attitudes, and release their creative impulses to write. Implications related to the body-mind connection are pondered.…

  16. Tailoring nanoarchitectonics to control the release profile of payloads

    NASA Astrophysics Data System (ADS)

    Jiang, Shuai; Lv, Liping; Li, Qifeng; Wang, Junwei; Landfester, Katharina; Crespy, Daniel

    2016-06-01

    We demonstrate here that the control over the release rate of payloads and on the selectivity of the release can be achieved by designing nanomaterials with a hierarchical structure. Redox-responsive silica nanocapsules are first synthesized to allow for an accelerated release of the corrosion inhibitor 2-mercaptobenzothiazole as a payload upon chemical reduction and retarded release upon oxidation. In a second step, we embedded the nanocapsules into nanofibers by colloid-electrospinning, yielding a hierarchical composite structure. Remarkably, the encapsulation of the nanocapsules in the fibers provides two decisive advantages that are a higher selectivity of the release and a higher control over the release rate of payloads.We demonstrate here that the control over the release rate of payloads and on the selectivity of the release can be achieved by designing nanomaterials with a hierarchical structure. Redox-responsive silica nanocapsules are first synthesized to allow for an accelerated release of the corrosion inhibitor 2-mercaptobenzothiazole as a payload upon chemical reduction and retarded release upon oxidation. In a second step, we embedded the nanocapsules into nanofibers by colloid-electrospinning, yielding a hierarchical composite structure. Remarkably, the encapsulation of the nanocapsules in the fibers provides two decisive advantages that are a higher selectivity of the release and a higher control over the release rate of payloads. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00917d

  17. Morphology of Gas Release in Physical Simulants

    SciTech Connect

    Daniel, Richard C.; Burns, Carolyn A.; Crawford, Amanda D.; Hylden, Laura R.; Bryan, Samuel A.; MacFarlan, Paul J.; Gauglitz, Phillip A.

    2014-07-03

    This report documents testing activities conducted as part of the Deep Sludge Gas Release Event Project (DSGREP). The testing described in this report focused on evaluating the potential retention and release mechanisms of hydrogen bubbles in underground radioactive waste storage tanks at Hanford. The goal of the testing was to evaluate the rate, extent, and morphology of gas release events in simulant materials. Previous, undocumented scoping tests have evidenced dramatically different gas release behavior from simulants with similar physical properties. Specifically, previous gas release tests have evaluated the extent of release of 30 Pa kaolin and 30 Pa bentonite clay slurries. While both materials are clays and both have equivalent material shear strength using a shear vane, it was found that upon stirring, gas was released immediately and completely from bentonite clay slurry while little if any gas was released from the kaolin slurry. The motivation for the current work is to replicate these tests in a controlled quality test environment and to evaluate the release behavior for another simulant used in DSGREP testing. Three simulant materials were evaluated: 1) a 30 Pa kaolin clay slurry, 2) a 30 Pa bentonite clay slurry, and 3) Rayleigh-Taylor (RT) Simulant (a simulant designed to support DSGREP RT instability testing. Entrained gas was generated in these simulant materials using two methods: 1) application of vacuum over about a 1-minute period to nucleate dissolved gas within the simulant and 2) addition of hydrogen peroxide to generate gas by peroxide decomposition in the simulants over about a 16-hour period. Bubble release was effected by vibrating the test material using an external vibrating table. When testing with hydrogen peroxide, gas release was also accomplished by stirring of the simulant.

  18. Historical river flow rates for dose calculations

    SciTech Connect

    Carlton, W.H.

    1991-06-10

    Annual average river flow rates are required input to the LADTAP Computer Code for calculating offsite doses from liquid releases of radioactive materials to the Savannah River. The source of information on annual river flow rates used in dose calculations varies, depending on whether calculations are for retrospective releases or prospective releases. Examples of these types of releases are: Retrospective - releases from routine operations (annual environmental reports) and short term release incidents that have occurred. Prospective - releases that might be expected in the future from routine or abnormal operation of existing or new facilities (EIS`s, EID`S, SAR`S, etc.). This memorandum provides historical flow rates at the downstream gauging station at Highway 301 for use in retrospective dose calculations and derives flow rate data for the Beaufort-Jasper and Port Wentworth water treatment plants.

  19. Higher Death Rate Among Youth With First Episode Psychosis

    MedlinePlus

    ... Releases News Release Thursday, April 6, 2017 Higher death rate among youth with first episode psychosis NIH- ... experiencing first episode psychosis have a much higher death rate than previously thought. Researchers analyzed data on ...

  20. Coaxial nanotubes of stimuli responsive polymers with tunable release kinetics.

    PubMed

    Armagan, Efe; Ozaydin Ince, Gozde

    2015-11-07

    Stimuli responsive polymeric (SRP) nanotubes have great potential as nanocarriers of macromolecules due to their large surface areas and release mechanisms that can be activated externally. In this work, we demonstrate vapor phase synthesis of coaxial nanotubes with layers of different SRP polymers for improved release kinetics. Temperature responsive poly(N-isopropylacrylamide) (pNIPAAm), pH responsive poly(methacrylic acid) (pMAA) and poly(hydroxyethyl methacrylate) (pHEMA) are used to fabricate the responsive coaxial nanotubes and the phloroglucinol dye is used as the model molecule to study the release kinetics. Fastest release is observed with single layer pNIPAAm nanotubes with rates of 0.134 min(-1), whereas introducing pHEMA or pMAA as inner layers slows down the release, enabling tuning of the response. Furthermore, repeating the release studies multiple times shows that the release rates remain similar after each run, confirming the stability of the nanotubes.

  1. Sustain-release of various drugs from leucaena leucocephala polysaccharide.

    PubMed

    Jeevanandham, S; Sekar, M; Dhachinamoorthi, D; Muthukumaran, M; Sriram, N; Joysaruby, J

    2010-01-01

    This study examines the sustained release behavior of both water-soluble (acetaminophen, caffeine, theophylline and salicylic acid) and water-insoluble (indomethacin) drugs from Leucaena leucocephala seed Gum isolated from Leucaena leucocephala kernel powder. It further investigates the effect of incorporation of diluents like microcrystalline cellulose and lactose on release of caffeine and partial cross-linking of the gum (polysaccharide) on release of acetaminophen. Applying exponential equation, the mechanism of release of soluble drugs was found to be anomalous. The insoluble drug showed near case II or zero-order release mechanism. The rate of release was in the decreasing order of caffeine, acetaminophen, theophylline, salicylic acid and indomethacin. An increase in release kinetics of drug was observed on blending with diluents. However, the rate of release varied with type and amount of blend in the matrix. The mechanism of release due to effect of diluents was found to be anomalous. The rate of release of drug decreased on partial cross-linking and the mechanism of release was found to be super case II.

  2. Diffuse-interface theory for structure formation and release behavior in controlled drug release systems.

    PubMed

    Saylor, David M; Kim, Chang-Soo; Patwardhan, Dinesh V; Warren, James A

    2007-11-01

    A common method of controlling drug release has been to incorporate the drug into a polymer matrix, thereby creating a diffusion barrier that slows the rate of drug release. It has been demonstrated that the internal microstructure of these drug-polymer composites can significantly impact the drug release rate. However, the effect of processing conditions during manufacture on the composite structure and the subsequent effects on release behavior are not well understood. We have developed a diffuse-interface theory for microstructure evolution that is based on interactions between drug, polymer and solvent species, all of which may be present in either crystalline or amorphous states. Because the theory can be applied to almost any specific combination of material species and over a wide range of environmental conditions, it can be used to elucidate and quantify the relationships between processing, microstructure and release response in controlled drug release systems. Calculations based on the theory have now demonstrated that, for a characteristic delivery system, variations in microstructure arising due to changes in either drug loading or processing time, i.e. evaporation rate, could have a significant impact on both the bulk release kinetics and the uniformity of release across the system. In fact, we observed that changes in process time alone can induce differences in bulk release of almost a factor of two and typical non-uniformities of +/-30% during the initial periods of release. Because these substantial variations may have deleterious clinical ramifications, it is critical that both the system microstructure and the control of that microstructure are considered to ensure the device will be both safe and effective in clinical use.

  3. Kinetics of Cd Release from Some Contaminated Calcareous Soils

    SciTech Connect

    Sajadi Tabar, S.; Jalali, M.

    2013-03-15

    Contamination of soils with heavy metals may pose long-term risk to groundwater quality leading to health implications. Bioavailability of heavy metals, like cadmium (Cd) is strongly affected by sorption and desorption processes. The release of heavy metals from contaminated soils is a major contamination risks to natural waters. The release of Cd from contaminated soils is strongly influenced by its mobility and bioavailability. In this study, the kinetics of Cd desorption from ten samples of contaminated calcareous soils, with widely varying physicochemical properties, were studied using 0.01 M EDTA extraction. The median percentage of Cd released was about 27.7% of the total extractable Cd in the soils. The release of Cd was characterized by an initial fast release rate (of labile fractions) followed by a slower release rate (of less labile fractions) and a model of two first-order reactions adequately describes the observed release of Cd from the studied soil samples. There was positive correlation between the amount of Cd released at first phase of release and Cd in exchangeable fraction, indicating that this fraction of Cd is the main fraction controlling the Cd in the kinetic experiments. There was strongly negative correlation between the amount of Cd released at first and second phases of release and residual fraction, suggesting that this fraction did not contribute in Cd release in the kinetic experiments. The results can be used to provide information for evaluation of Cd potential toxicity and ecological risk from contaminated calcareous soils.

  4. Fiber release from impacted graphite reinforced epoxy composites

    NASA Technical Reports Server (NTRS)

    Babinsky, T. C.

    1980-01-01

    Carbon fibers released from composites by aircraft fires and crashes can cause electrical shorts and consequent equipment damage. This report investigates less vigorous release mechanisms than that previously simulated by explosive burn/blast tests. When AS/3501-6 composites are impacted by various head and weight configurations of a pendulum impactor, less than 0.2 percent by weight of the original sample is released as single fibers. Other fiber release mechanisms studied were air blasts, constant airflow, torsion, flexural, and vibration of composite samples. The full significance of the low single fiber release rates found here is to be evaluated by NASA in their aircraft vulnerability studies.

  5. Evaluation of a soil incubation method to characterize nitrogen release patterns of slow- and controlled-release fertilizers.

    PubMed

    Medina, L Carolina; Sartain, Jerry B; Obreza, Thomas A; Hall, William L; Thiex, Nancy J

    2014-01-01

    Several technologies have been proposed to characterize the nutrient release patterns of slow-release fertilizers (SRF) and controlled-release fertilizers (CRF) during the last few decades. These technologies have been developed mainly by manufacturers, and are product-specific, based on the regulation and analysis of each SRF and CRF product. Despite previous efforts to characterize SRF and CRF materials, no standardized, validated method exists to assess their nutrient release patterns. However, the increased production and distribution of these materials in specialty and nonspecialty markets requires an appropriate method to verify product claims and material performance. A soil incubation column leaching procedure was evaluated to determine its suitability as a standard method to estimate nitrogen (N) release patterns of SRFs and CRFs during 180 days. The influence of three soil/sand ratios, three incubation temperatures, and four soils on method behavior was assessed using five SRFs and three CRFs. In general, the highest soil/sand ratio increased the N release rate of all materials, but this effect was more marked for the SRFs. Temperature had the greatest influence on N release rates. For CRFs, the initial N release rates and the percentage N released/day increased as temperature increased. For SRFs, raising the temperature from 25 to 35 degreesC increased initial N release rate and the total cumulative N released, and almost doubled the percentage released/day. The percentage N released/day from all products generally increased as the texture of the soil changed from sandy to loamy (lowa>California>Pennsylvania>Florida). The soil incubation technique was demonstrated to be robust and reliable for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and variations in soil/sand ratio, temperature, and soil had little effect on the results.

  6. RAVEN Beta Release

    SciTech Connect

    Rabiti, Cristian; Alfonsi, Andrea; Cogliati, Joshua Joseph; Mandelli, Diego; Kinoshita, Robert Arthur; Wang, Congjian; Maljovec, Daniel Patrick; Talbot, Paul William

    2016-02-01

    This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.

  7. Altitude release mechanism

    DOEpatents

    Kulhanek, Frank C.

    1977-01-01

    An altitude release mechanism for releasing a radiosonde or other measuring instrument from a balloon carrying it up into the atmosphere includes a bottle partially filled with water, a tube sealed into the bottle having one end submerged in the water in the bottle and the free end extending above the top of the bottle and a strip of water-disintegrable paper held within the free end of the tube linking the balloon to the remainder of the package. As the balloon ascends, the lowered atmospheric air pressure causes the air in the bottle to expand, forcing the water in the bottle up the tubing to wet and disintegrate the paper, releasing the package from the balloon.

  8. 40 CFR 68.25 - Worst-case release scenario analysis.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance... volatilization rate (release rate) shall be calculated at the boiling point of the substance and at the... below their atmospheric boiling point, the volatilization rate shall be calculated at the...

  9. 40 CFR 68.25 - Worst-case release scenario analysis.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance... volatilization rate (release rate) shall be calculated at the boiling point of the substance and at the... below their atmospheric boiling point, the volatilization rate shall be calculated at the...

  10. 40 CFR 68.25 - Worst-case release scenario analysis.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance... volatilization rate (release rate) shall be calculated at the boiling point of the substance and at the... below their atmospheric boiling point, the volatilization rate shall be calculated at the...

  11. 40 CFR 68.25 - Worst-case release scenario analysis.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance... volatilization rate (release rate) shall be calculated at the boiling point of the substance and at the... below their atmospheric boiling point, the volatilization rate shall be calculated at the...

  12. 40 CFR 68.25 - Worst-case release scenario analysis.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance... volatilization rate (release rate) shall be calculated at the boiling point of the substance and at the... below their atmospheric boiling point, the volatilization rate shall be calculated at the...

  13. INVESTIGATION OF DRUG RELEASE FROM BIODEGRADABLE PLG MICROSPHERES: EXPERIMENT AND THEORY

    SciTech Connect

    ANDREWS, MALCOLM J.; BERCHANE, NADER S.; CARSON, KENNETH H.; RICE-FICHT, ALLISON C.

    2007-01-30

    Piroxicam containing PLG microspheres having different size distributions were fabricated, and in vitro release kinetics were determined for each preparation. Based on the experimental results, a suitable mathematical theory has been developed that incorporates the effect of microsphere size distribution and polymer degradation on drug release. We show from in vitro release experiments that microsphere size has a significant effect on drug release rate. The initial release rate decreased with an increase in microsphere size. In addition, the release profile changed from first order to concave-upward (sigmoidal) as the system size was increased. The mathematical model gave a good fit to the experimental release data.

  14. Releasable Asbestos Field Sampler

    EPA Science Inventory

    Asbestos aerosolization (or releasability) is the potential for fibrous asbestos structures that are present in a material or on a solid surface to become airborne when the source is disturbed by human activities or natural forces. In turn, the magnitude of the airborne concentra...

  15. Release of OLe peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    OLe is a high oleic Spanish-type peanut that has excellent yield and enhanced Sclerotinia blight and pod rot resistance when compared to other high oleic Spanish cultivars. The purpose for releasing OLe is to provide peanut producers with a true Spanish peanut that is high oleic and has enhanced yi...

  16. Hydraulic release oil tool

    SciTech Connect

    Mims, M.G.; Mueller, M.D.; Ehlinger, J.C.

    1992-03-11

    This patent describes a hydraulic release tool. It comprises a setting assembly; a coupling member for coupling to drill string or petroleum production components, the coupling member being a plurality of sockets for receiving the dogs in the extended position and attaching the coupling member the setting assembly; whereby the setting assembly couples to the coupling member by engagement of the dogs in the sockets of releases from and disengages the coupling member in movement of the piston from its setting to its reposition in response to a pressure in the body in exceeding the predetermined pressure; and a relief port from outside the body into its bore and means to prevent communication between the relief port and the bore of the body axially of the piston when the piston is in the setting position and to establish such communication upon movement of the piston from the setting position to the release position and reduce the pressure in the body bore axially of the piston, whereby the reduction of the pressure signals that the tool has released the coupling member.

  17. Data Release Summary Statement

    Atmospheric Science Data Center

    2016-11-14

    ... 3 CALIOP Level 1 data are released with a product maturity classification of Validated Stage1 , indicating that initial validation of ... users for evaluation and to provide feedback to the CALIOP algorithm development team. Users should carefully read the section of the Data ...

  18. Suppression pheromone and cockroach rank formation

    NASA Astrophysics Data System (ADS)

    Kou, Rong; Chang, Huan-Wen; Chen, Shu-Chun; Ho, Hsiao-Yung

    2009-06-01

    Although agonistic behaviors in the male lobster cockroach ( Nauphoeta cinerea) are well known, the formation of an unstable hierarchy has long been a puzzle. In this study, we investigate how the unstable dominance hierarchy in N. cinerea is maintained via a pheromone signaling system. In agonistic interactions, aggressive posture (AP) is an important behavioral index of aggression. This study showed that, during the formation of a governing hierarchy, thousands of nanograms of 3-hydroxy-2-butanone (3H-2B) were released by the AP-adopting dominant in the first encounter fight, then during the early domination period and that this release of 3H-2B was related to rank maintenance, but not to rank establishment. For rank maintenance, 3H-2B functioned as a suppression pheromone, which suppressed the fighting capability of rivals and kept them in a submissive state. During the period of rank maintenance, as the dominant male gradually decreased his 3H-2B release, the fighting ability of the subordinate gradually developed, as shown by the increasing odds of a subordinate adopting an AP (OSAP). The OSAP was negatively correlated with the amount of 3H-2B released by the dominant and positively correlated with the number of domination days. The same OSAP could be achieved earlier by reducing the amount of 3H-2B released by the dominant indicates that whether the subordinate adopts an offensive strategy depends on what the dominant is doing.

  19. Ultrasound-enhanced polymer degradation and release of incorporated substances.

    PubMed Central

    Kost, J; Leong, K; Langer, R

    1989-01-01

    The effect of ultrasound on the degradation of polymers and the release rate of incorporated molecules within those polymers was examined. Up to 5-fold reversible increases in degradation rate and up to 20-fold reversible increases in release rate of incorporated molecules were observed with biodegradable polyanhydrides, polyglycolides, and polylactides. Up to 10-fold reversible increases in release rate of incorporated molecules within nonerodible ethylene/vinyl acetate copolymer were also observed. The release rate increased in proportion to the intensity of ultrasound. Temperature and mixing were relatively unimportant in effecting enhanced polymer degradation, whereas cavitation appeared to play a significant role. Increased release rates were also observed when ultrasound was applied to biodegradable polymers implanted in rats. Histological examination revealed no differences between normal rat skin and rat skin that had been exposed to ultrasonic radiation for 1 hr. With further study, ultrasound may prove useful as a way of externally regulating release rates from polymers in a variety of situations where on-demand release is required. Images PMID:2813349

  20. Controlled drug release from bifunctionalized mesoporous silica

    SciTech Connect

    Xu Wujun; Gao Qiang; Xu Yao Wu Dong; Sun Yuhan; Shen Wanling; Deng Feng

    2008-10-15

    Serial of trimethylsilyl-carboxyl bifunctionalized SBA-15 (TMS/COOH/SBA-15) have been studied as carriers for controlled release of drug famotidine (Famo). To load Famo with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized by one-pot synthesis under the assistance of KCl. The mesostructure of carboxyl functionalized SBA-15 (COOH/SBA-15) could still be kept even though the content of carboxyl groups was up to 57.2%. Increasing carboxyl content could effectively enhance the loading capacity of Famo. Compared with pure SBA-15, into which Famo could be hardly adsorbed, the largest drug loading capacity of COOH/SBA-15 could achieve 396.9 mg/g. The release of Famo from mesoporous silica was studied in simulated intestine fluid (SIF, pH=7.4). For COOH/SBA-15, the release rate of Famo decreased with narrowing pore size. After grafting TMS groups on the surface of COOH/SBA-15 with hexamethyldisilazane, the release of Famo was greatly delayed with the increasing content of TMS groups. - Graphical abstract: Trimethylsilyl-carboxyl bifunctionalized SBA-15 has been studied as carrier for controlled release of drug famotidine. To load drug with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized. After grafting trimethylsilyl groups on the surface of carboxyl functionalized SBA-15, the release of Famo was greatly delayed with the increasing content of TMS groups.

  1. Mental illness, criminal risk factors and parole release decisions.

    PubMed

    Matejkowski, Jason; Draine, Jeffrey; Solomon, Phyllis; Salzer, Mark S

    2011-01-01

    Research has not examined whether higher rates of parole denial among inmates with mental illness (MI) are the result of the increased presence of criminal risk factors among this population. Employing a representative sample of inmates with (n  =  219) and without (n  =  184) MI receiving parole release decisions in 2007, this study tested whether the central eight risk factors for recidivism considered in parole release decisions intervened in the relationship between MI and parole release. MI was associated with possession of a substance use disorder, antisocial personality disorder and violent charges while incarcerated; however, these factors were not related to release decisions. MI was found to have neither a direct nor an indirect effect on release decisions. While results indicate that release decisions appear, to some extent, to be evidence-based, they also suggest considerable discretion is being implemented by parole board members in release decisions above and beyond consideration of criminal risk factors.

  2. Release Fraction Evaluation

    SciTech Connect

    Bamberger, Judith A.; Glissmeyer, John A.

    2004-01-01

    This document presents results of experiments conducted to measure release fractions during certain tank retrieval processes. The tests were performed in a 1/4 scale model of a waste storage tank. The retrieval processes simulated were: (1) Discharging liquid or slurry from the mouth of a vertically oriented two-in. Schedule 40 pipe. The discharging material was in free-fall from the mouth of the pipe near the top of the tank into a liquid or slurry pool at the bottom of the tank. (2) The jet from a 9/16-in.-diameter nozzle transferring liquid or slurry waste from one side of the tank to the other. The discharging liquid was aimed at the opposite side of the tank from the nozzle and either impacted the tank wall or fell into a liquid or slurry pool in the bottom of the tank. (3) A high pressure fan jet of liquid striking a steel plate or simulated waste from a stand-off distance of a few inches. For each process, a water-soluble fluorescent dye was added to the liquid fraction as a tracer. Kaolin clay was used to represent the solids. The tank was covered and there was no forced ventilation in the tank during the tests. Six air samples were collected during each test. The air samples were collected at fixed positions in the tank. The air sample filters were dried and weighed to determine the solids collection. The fluorescent dye was then leached from each filter and quantified with a fluorometer to determine the collection of liquid. Samples of the slurry and liquid simulants were also collected to determine the quantities of simulant used in each test. To calculate the release fraction, the quantity collected on each air sample was adjusted for the fraction of the tank volume sampled and divided by the quantity of material exposed in the simulation. The method was not as sensitive for the solids content as it was for the liquid content, but in those instances where a solids release fraction was determined, it was in relatively good agreement with that of the

  3. Biomechanical coupling in renin-releasing cells.

    PubMed Central

    Carey, R M; McGrath, H E; Pentz, E S; Gomez, R A; Barrett, P Q

    1997-01-01

    The renin-angiotensin system is a major regulatory system controlling extracellular fluid volume and blood pressure. The rate-limiting enzyme in this hormonal cascade is renin, which is synthesized and secreted into the circulation by renal juxtaglomerular (JG) cells. The renal baroreceptor is a key physiologic regulator of renin secretion, whereby a change in renal perfusion pressure is sensed by these cells and results in a change in renin release. However, the mechanism, direct or indirect, underlying pressure transduction is unknown. We studied the direct application of mechanical stretch to rat JG cells and human renin-expressing (CaLu-6) cells on the release of renin. JG cells released a low level of baseline renin, comprising < 5% of their total renin content. By contrast, renin secretion from CaLu-6 cells comprised approximately 30% of cellular stores, yet was also stimulated twofold by 10 microM forskolin (P release by 42% (P < 0.01) and forskolin-stimulated renin release by 25% (P < 0.05). In CaLu-6 cells, stretch inhibited basal- and forskolin-stimulated renin release by 30 and 26%, respectively (both P < 0.01). Northern blot analysis demonstrated a stretch-induced reduction in baseline renin mRNA accumulation of 26% (P < 0.05) in JG and 46% (P < 0.05) in CaLu-6 cells. The data demonstrate that mechanical stretch in renin-releasing cells inhibits basal and stimulated renin release accompanied by a decrease in renin mRNA accumulation. Further studies will be necessary to characterize the intracellular events mediating biomechanical coupling in renin-expressing cells and the relationship of this signaling pathway to the in vivo baroreceptor control of renin secretion. PMID:9294125

  4. Tryptophan availability modulates serotonin release from rat hypothalamic slices

    NASA Technical Reports Server (NTRS)

    Schaechter, Judith D.; Wurtman, Richard J.

    1989-01-01

    The relationship between the tryptophan availability and serononin release from rat hypothalamus was investigated using a new in vitro technique for estimating rates at which endogenous serotonin is released spontaneously or upon electrical depolarization from hypothalamic slices superfused with a solution containing various amounts of tryptophan. It was found that the spontaneous, as well as electrically induced, release of serotonin from the brain slices exhibited a dose-dependent relationship with the tryptophan concentration of the superfusion medium.

  5. Electrochemical Corrosion Studies for Modeling Metallic Waste Form Release Rates

    SciTech Connect

    Poineau, Frederic; Tamalis, Dimitri

    2016-08-01

    The isotope 99Tc is an important fission product generated from nuclear power production. Because of its long half-life (t1/2 = 2.13 ∙ 105 years) and beta-radiotoxicity (β⁻ = 292 keV), it is a major concern in the long-term management of spent nuclear fuel. In the spent nuclear fuel, Tc is present as an alloy with Mo, Ru, Rh, and Pd called the epsilon-phase, the relative amount of which increases with fuel burn-up. In some separation schemes for spent nuclear fuel, Tc would be separated from the spent fuel and disposed of in a durable waste form. Technetium waste forms under consideration include metallic alloys, oxide ceramics and borosilicate glass. In the development of a metallic waste form, after separation from the spent fuel, Tc would be converted to the metal, incorporated into an alloy and the resulting waste form stored in a repository. Metallic alloys under consideration include Tc–Zr alloys, Tc–stainless steel alloys and Tc–Inconel alloys (Inconel is an alloy of Ni, Cr and iron which is resistant to corrosion). To predict the long-term behavior of the metallic Tc waste form, understanding the corrosion properties of Tc metal and Tc alloys in various chemical environments is needed, but efforts to model the behavior of Tc metallic alloys are limited. One parameter that should also be considered in predicting the long-term behavior of the Tc waste form is the ingrowth of stable Ru that occurs from the radioactive decay of 99Tc (99Tc → 99Ru + β⁻). After a geological period of time, significant amounts of Ru will be present in the Tc and may affect its corrosion properties. Studying the effect of Ru on the corrosion behavior of Tc is also of importance. In this context, we studied the electrochemical behavior of Tc metal, Tc-Ni alloys (to model Tc-Inconel alloy) and Tc-Ru alloys in acidic media. The study of Tc-U alloys has also been performed in order to better understand the nature of Tc in metallic spent fuel. Computational modeling and simulations were performed to shed light on experimental results and explain structural and kinetics trends.

  6. Releasable locking mechanisms

    NASA Technical Reports Server (NTRS)

    Ahmed, Rafiq (Inventor); Wingate, Robert J. (Inventor)

    2005-01-01

    In the aerospace field spacecraft components are held together by separation systems until a specific time when they must be separated or deployed. Customarily a threaded joining bolt engages one of the components to be joined, and a threaded nut is placed on that bolt against the other component so they can be drawn together by a releasable locking assembly. The releasable locking assembly herein includes a plunger having one end coupled to one end of a plunger bolt. The other end is flanged to abut and compress a coil spring when the plunger is advanced toward the interface plane between the two components. When the plunger is so advanced toward the interface plane, the end of the plunger bolt can be connected to the joining bolt. Thus during retraction the joining bolt is drawn to one side of the interface plane by the force of the expanding spring.

  7. 7 CFR Appendix B to Subpart E of... - Federal Reserve Statistical Release

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Statistical Release Federal Reserve Statistical Release These data are released each Monday. The availability... rates on nationally traded certificates of deposit. 9 Bid rates for Eurodollar deposits at 11 a.m... the Federal Reserve Bank of New York. 12 Auction date for daily data; weekly and monthly...

  8. 7 CFR Appendix B to Subpart E of... - Federal Reserve Statistical Release

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Statistical Release Federal Reserve Statistical Release These data are released each Monday. The availability... rates on nationally traded certificates of deposit. 9 Bid rates for Eurodollar deposits at 11 a.m... the Federal Reserve Bank of New York. 12 Auction date for daily data; weekly and monthly...

  9. Characterization of Release Mechanism in Polymeric Drug Delivery Systems

    NASA Astrophysics Data System (ADS)

    Laplante, Arthur James; Plachy, Robin Marie; Aou, Kaoru; Ferguson, Jake; Hsu, Shaw Ling

    2006-03-01

    Our polymeric drug delivery system is based on our understanding of phase behavior of polymers [e.g poly(lactic acid)], low molecular drugs and various solvents used in processing. Clearly the different morphologies achieved, based on different phase separation kinetics, can affect drug release rates. Release of drugs, in most cases, involves the exchange between the extraction media and drug. We have characterized the transport behavior using a number of unique techniques. Reflectance infrared spectroscopy has given us a detailed description of the release rate of drugs into the extraction media. Surface plasmon resonance has shown the overall mass loss. UV-visible spectroscopy has yielded the concentration of drug in the solution. These measurements are compared to the release mechanism based on Fickian diffusion. The two step release rates observed can only be explained by taking into account differences in the morphological features of the phase separated films.

  10. Cryogenic hydrogen release research.

    SciTech Connect

    LaFleur, Angela Christine

    2015-12-01

    The objective of this project was to devolop a plan for modifying the Turbulent Combustion Laboratory (TCL) with the necessary infrastructure to produce a cold (near liquid temperature) hydrogen jet. The necessary infrastructure has been specified and laboratory modifications are currently underway. Once complete, experiments from this platform will be used to develop and validate models that inform codes and standards which specify protection criteria for unintended releases from liquid hydrogen storage, transport, and delivery infrastructure.

  11. Sudden releases of gases

    NASA Astrophysics Data System (ADS)

    Chaloupecká, Hana; Jaňour, Zbyněk; Jurčáková, Klára; Kukačka, Libor; Nosek, Štěpán

    2014-03-01

    Conurbations all over the world have enlarged for numberless years. The accidental or intentional releases of gases become more frequent. Therefore, these crises situations have to be studied. The aim of this paper is to describe experiments examining these processes that were carried out in the laboratory of Environmental Aerodynamics of the Institute of Thermomechanics AS CR in Nový Knín. Results show huge puff variability from replica to replica.

  12. Slow-release fertilizer

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W. (Inventor); Golden, D. C. (Inventor)

    1992-01-01

    A synthetic apatite containing agronutrients and a method for making the apatite are disclosed. The apatite comprises crystalline calcium phosphate having agronutrients dispersed in the crystalline structure. The agronutrients can comprise potassium, magnesium, sulfur, iron, manganese, molybdenum, chlorine, boron, copper and zinc in amounts suited for plant growth. The apatite can optionally comprise a carbonate and/or silicon solubility control agent. The agronutrients are released slowly as the apatite dissolves.

  13. Slow-release fertilizer

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W. (Inventor); Golden, Dadigamuwage C. (Inventor)

    1995-01-01

    A synthetic apatite containing agronutrients and a method for making the apatite are disclosed. The apatite comprises crystalline calcium phosphate having agronutrients dispersed in the crystalline structure. The agronutrients can comprise potassium, magnesium, sulfur, iron, manganese, molybdenum, chlorine, boron, copper and zinc in amounts suited for plant growth. The apatite can optionally comprise a carbonate and/or silicon solubility control agent. The agronutrients are released slowly as the apatite dissolves.

  14. EIA new releases

    SciTech Connect

    Not Available

    1994-12-01

    This report was prepared by the Energy Information Administration. It contains news releases on items of interest to the petroleum, coal, nuclear, electric and alternate fuels industries ranging from economic outlooks to environmental concerns. There is also a listing of reports by industry and an energy education resource listing containing sources for free or low-cost energy-related educational materials for educators and primary and secondary students.

  15. Slow-release fertilizer

    NASA Astrophysics Data System (ADS)

    Ming, Douglas W.; Golden, D. C.

    1992-10-01

    A synthetic apatite containing agronutrients and a method for making the apatite are disclosed. The apatite comprises crystalline calcium phosphate having agronutrients dispersed in the crystalline structure. The agronutrients can comprise potassium, magnesium, sulfur, iron, manganese, molybdenum, chlorine, boron, copper and zinc in amounts suited for plant growth. The apatite can optionally comprise a carbonate and/or silicon solubility control agent. The agronutrients are released slowly as the apatite dissolves.

  16. Clinton releases oceans report

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    U.S. President Bill Clinton is trying to beat the clock on the January 20 close of his administration by maintaining a flurry of activity on resource and conservation issues.During a December 4 speech in Washington, D.C., he released a broad-ranging report by the Presidents Panel on Ocean Exploration, entitled “Discovering Earth's Final Frontier: A U.S. Strategy for Ocean Exploration.”

  17. Controlled release of biologically active silver from nanosilver surfaces.

    PubMed

    Liu, Jingyu; Sonshine, David A; Shervani, Saira; Hurt, Robert H

    2010-11-23

    Major pathways in the antibacterial activity and eukaryotic toxicity of nanosilver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nanosilver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nanosilver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nanosilver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nanosilver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over 4 orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by preoxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and releasing inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through a bacterial inhibition zone assay carried out on selected formulations of controlled release nanosilver.

  18. Contact: Releasing the news

    NASA Astrophysics Data System (ADS)

    Pinotti, Roberto

    The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

  19. Triggered Release from Polymer Capsules

    SciTech Connect

    Esser-Kahn, Aaron P.; Odom, Susan A.; Sottos, Nancy R.; White, Scott R.; Moore, Jeffrey S.

    2011-07-06

    Stimuli-responsive capsules are of interest in drug delivery, fragrance release, food preservation, and self-healing materials. Many methods are used to trigger the release of encapsulated contents. Here we highlight mechanisms for the controlled release of encapsulated cargo that utilize chemical reactions occurring in solid polymeric shell walls. Triggering mechanisms responsible for covalent bond cleavage that result in the release of capsule contents include chemical, biological, light, thermal, magnetic, and electrical stimuli. We present methods for encapsulation and release, triggering methods, and mechanisms and conclude with our opinions on interesting obstacles for chemically induced activation with relevance for controlled release.

  20. Chronic Release of Tritium from Stainless Steel 316

    NASA Astrophysics Data System (ADS)

    Torikai, Yuji; Naoe, Shogo; Akaishi, Kenya; Watanabe, Kuniaki; Matsuyama, Masao

    To understand the release mechanism of tritium from solid materials, release rate of tritium was measured when a tritium loaded 316 stainless steel specimen was put in dry argon gas flow of atmospheric pressure at room temperature. During blowing of argon gas released products from the specimen were collected in water bubblers which were set in the downstream of the blowing circuit, and the tritium content in the bubbler water was periodically measured as a function of time by scintillation counter. More than 99% of released species from the specimen was tritiated water, HTO. The measured result of tritium release rate showed that tritium is released chronically for a long time. The chronic release rate of tritium was evaluated using the diffusion model reported by Calder and Lewin, and it was found that when a reasonable value for the bulk diffusion coefficient of tritium is assumed, the tritium release rate can be described with the diffusion flux at the surface boundary of the specimen.

  1. Ghrelin and obestatin modulate growth hormone-releasing hormone release and synaptic inputs onto growth hormone-releasing hormone neurons.

    PubMed

    Feng, Dan D; Yang, Seung-Kwon; Loudes, Catherine; Simon, Axelle; Al-Sarraf, Tamara; Culler, Michael; Alvear-Perez, Rodrigo; Llorens-Cortes, Catherine; Chen, Chen; Epelbaum, Jacques; Gardette, Robert

    2011-09-01

    Ghrelin, a natural ligand of the growth hormone secretagogue receptor (GHS-R), is synthesized in the stomach but may also be expressed in lesser quantity in the hypothalamus where the GHS-R is located on growth hormone-releasing hormone (GHRH) neurons. Obestatin, a peptide derived from the same precursor as ghrelin, is able to antagonize the ghrelin-induced increase of growth hormone (GH) secretion in vivo but not from pituitary explants in vitro. Thus, the blockade of ghrelin-induced GH release by obestatin could be mediated at the hypothalamic level by the neuronal network that controls pituitary GH secretion. Ghrelin increased GHRH and decreased somatostatin (somatotropin-releasing inhibitory factor) release from hypothalamic explants, whereas obestatin only reduced the ghrelin-induced increase of GHRH release, thus indicating that the effect of ghrelin and obestatin is targeted to GHRH neurons. Patch-clamp recordings on mouse GHRH-enhanced green fluorescent protein neurons indicated that ghrelin and obestatin had no significant effects on glutamatergic synaptic transmission. Ghrelin decreased GABAergic synaptic transmission in 44% of the recorded neurons, an effect blocked in the presence of the GHS-R antagonist BIM28163, and stimulated the firing rate of 78% of GHRH neurons. Obestatin blocked the effects of ghrelin by acting on a receptor different from the GHS-R. These data suggest that: (i) ghrelin increases GHRH neuron excitability by increasing their action potential firing rate and decreasing the strength of GABA inhibitory inputs, thereby leading to an enhanced GHRH release; and (ii) obestatin counteracts ghrelin actions. Such interactions on GHRH neurons probably participate in the control of GH secretion.

  2. Recommended for release on recognizance: factors affecting pretrial release recommendations.

    PubMed

    Petee, T A

    1994-06-01

    Researchers have acknowledged the influence of pretrial release agencies in judicial decision making regarding bail; however, few researchers have focused on the process used by the pretrial release agencies to make bail-bond recommendations. In this study I sought to establish which factors were most salient in making the decision to recommend a defendant for release on recognizance. I found that both officially sanctioned release criteria and "extralegal" variables were predictive of this decision.

  3. Interfacial Fast Release Layer in Monodisperse Poly (lactic-co-glycolic acid) Microspheres Accelerates the Drug Release.

    PubMed

    Wu, Jun; Zhao, Xiaoli; Yeung, Kelvin W K; To, Michael K T

    2016-01-01

    Understanding microstructural evolutions of drug delivery devices during drug release process is essential for revealing the drug release mechanisms and controlling the drug release profiles. In this study, monodisperse poly (lactic-co-glycolic acid) microspheres in different diameters were fabricated by microfluidics in order to find out the relationships between the microstructural evolutions and the drug release profiles. It was found that poly (lactic-co-glycolic acid) microspheres underwent significant size expansion which took place from the periphery to the center, resulting in the formation of interfacial fast release layers. At the same time, inner pores were created and the diffusion rate was increased so that the early stage drug release was accelerated. Due to the different expansion rates, small poly (lactic-co-glycolic acid) microspheres tendered to follow homogeneous drug release while large poly (lactic-co-glycolic acid) microspheres tendered to follow heterogeneous drug release. This study suggests that the size expansion and the occurrence of interfacial fast release layer were important mechanisms for early stage drug release of poly (lactic-co-glycolic acid) microspheres.

  4. Sustained-release, extended-release, and other time-release formulations in neuropsychiatry.

    PubMed

    Andrade, Chittaranjan

    2015-08-01

    Pills and capsules may release their contents within minutes of ingestion; these are immediate-release formulations. Pills and capsules may also release their contents after a time lag, or a little at a time, or in some other predetermined way; these are time-release formulations. Many drugs in psychiatry have been time-release formulated to reduce their local adverse effects in the gastrointestinal tract, to reduce adverse effects associated with peak blood levels, or to artificially extend their half-life. Time-release formulations are associated with the added advantages of convenience of dosing, improved compliance, and less fluctuation in blood levels across the course of the day. A disadvantage of time-release formulations is that they may be incompletely absorbed; this is a serious issue in patients with acute or chronic intestinal hurry disorders, such as gastroenteritis or irritable bowel syndrome. Time-release formulations may also be more expensive than immediate-release formulations.

  5. Active compounds release from semisolid dosage forms.

    PubMed

    Olejnik, Anna; Goscianska, Joanna; Nowak, Izabela

    2012-11-01

    The aim of this paper is to review all the aspects of the in vitro release testing (IVRT) from semisolid dosage forms. Although none of the official dissolution methods has been specified for use with semisolid dosage forms, their utility for assessing release rates of drugs from semisolid dosage forms has become a topic of considerable interest. One can expect to overcome such complexity in the future, when the official "Topical and Transdermal Drug Products-Product Performance Tests" will be published in an issue of the Pharmacopeial Forum. Many factors such as type of the dissolution medium, membrane, temperature, and speed have an influence on the mechanism and kinetics of the release testing from gels, creams, and ointments; therefore, those parameters have been widely discussed.

  6. Modifying sorbents in controlled release formulations to prevent herbicides pollution.

    PubMed

    Flores Céspedes, F; Villafranca Sánchez, M; Pérez García, S; Fernández Pérez, M

    2007-10-01

    The herbicides chloridazon and metribuzin, identified as groundwater pollutants, were incorporated in alginate-based granules to obtain controlled release properties. In this research the effect of incorporation of sorbents such as bentonite, anthracite and activated carbon in alginate basic formulation were not only studied on encapsulation efficiency but also on the release rate of herbicides which was studied using water release kinetic tests. In addition, sorption studies of herbicides with bentonite, anthracite and activated carbon were made. The kinetic experiments of chloridazon and metribuzin release in water have shown that the release rate is higher in metribuzin systems than in those prepared with chloridazon, which has lower water solubility. Besides, it can be deduced that the use of sorbents reduces the release rate of the chloridazon and metribuzin in comparison to the technical product and to the alginate formulation without sorbents. The highest decrease in release rate corresponds to the formulations prepared with activated carbon as a sorbent. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T(50), were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the herbicide release data, the release of chloridazon and metribuzin from the various formulations into water is controlled by a diffusion mechanism. Sorption capacity of the sorbents for chloridazon and metribuzin, ranging from 0.53mgkg(-1) for the metribuzin sorption on bentonite to 2.03x10(5)mgkg(-1) for the sorption of chloridazon on the activated carbon, was the most important factor modulating the herbicide release.

  7. Gas releases from salt

    SciTech Connect

    Ehgartner, B.; Neal, J.; Hinkebein, T.

    1998-06-01

    The occurrence of gas in salt mines and caverns has presented some serious problems to facility operators. Salt mines have long experienced sudden, usually unexpected expulsions of gas and salt from a production face, commonly known as outbursts. Outbursts can release over one million cubic feet of methane and fractured salt, and are responsible for the lives of numerous miners and explosions. Equipment, production time, and even entire mines have been lost due to outbursts. An outburst creates a cornucopian shaped hole that can reach heights of several hundred feet. The potential occurrence of outbursts must be factored into mine design and mining methods. In caverns, the occurrence of outbursts and steady infiltration of gas into stored product can effect the quality of the product, particularly over the long-term, and in some cases renders the product unusable as is or difficult to transport. Gas has also been known to collect in the roof traps of caverns resulting in safety and operational concerns. The intent of this paper is to summarize the existing knowledge on gas releases from salt. The compiled information can provide a better understanding of the phenomena and gain insight into the causative mechanisms that, once established, can help mitigate the variety of problems associated with gas releases from salt. Outbursts, as documented in mines, are discussed first. This is followed by a discussion of the relatively slow gas infiltration into stored crude oil, as observed and modeled in the caverns of the US Strategic Petroleum Reserve. A model that predicts outburst pressure kicks in caverns is also discussed.

  8. Hydrogen release behavior.

    SciTech Connect

    LaChance, Jeffrey L.; Dedrick, Daniel E.; Keller, Jay O.; Evans, Gregory Herbert; Houf, William G.; Winters, William Stanley, Jr.; Ruggles, A.; Zhang, J.

    2010-04-01

    The summary of this presentation is: (1) Barrier walls are used to reduce setbacks by factor of 2; (2) We found no ignition-timing vs. over-pressure sensitivities for jet flow obstructed by barrier walls; (3) Cryogenic vapor cloud model indicates hazard length scales exceed the room-temperature release; validation experiments are required to confirm; (4) Light-up maps developed for lean limit ignition; flammability factor model provides good indication of ignition probability; and (5) Auto-ignition is enhanced by blunt-body obstructions - increases gas temperature and promotes fuel/air mixing.

  9. Uniform biodegradable microparticle systems for controlled release

    PubMed Central

    Xia, Yujie; Pack, Daniel W.

    2014-01-01

    Drug delivery methods can impact efficacy as much as the nature of the drug itself. Microparticles made of biodegradable polymers such as poly(D,L-lactide-co-glycolide) and poly(lactic acid) (PLA) have been studied extensively for controlled release of diverse drugs. By using a modified solvent extraction/evaporation method called precision particle fabrication (PPF), uniform microparticles such as single-wall microspheres, double-wall microspheres and liquid-core microcapsules have been fabricated with precise control of their geometric structures. By producing particles of uniform size, which has crucial impact on drug release behaviors, PPF-fabricated microparticles provide unique insights about drug release mechanism. Using small-molecule and macromolecule model drugs, our group demonstrated that physicochemical properties of the polymers and drugs and structural properties of the matrix can greatly impact drug distribution within microparticles, particle erosion and drug release rates. By careful selection of particle size and shell thickness, uniform microparticles can achieve “zero-order”, pulsatile or tandem release of drugs. PMID:12106984

  10. Nonequivalent release sites govern synaptic depression

    PubMed Central

    Wen, Hua; McGinley, Matthew J.; Mandel, Gail; Brehm, Paul

    2016-01-01

    Synaptic depression is prominent among synapses, but the underlying mechanisms remain uncertain. Here, we use paired patch clamp recording to study neuromuscular transmission between the caudal primary motor neuron and target skeletal muscle in zebrafish. This synapse has an unusually low number of release sites, all with high probabilities of release in response to low-frequency stimulation. During high-frequency stimulation, the synapse undergoes short-term depression and reaches steady-state levels of transmission that sustain the swimming behavior. To determine the release parameters underlying this steady state, we applied variance analysis. Our analysis revealed two functionally distinct subclasses of release sites differing by over 60-fold in rates of vesicle reloading. A slow reloading class requires seconds to recover and contributes to depression onset but not the steady-state transmission. By contrast, a fast reloading class recovers within tens of milliseconds and is solely responsible for steady-state transmission. Thus, in contrast to most current models that assign levels of steady-state depression to vesicle availability, our findings instead assign this function to nonuniform release site kinetics. The duality of active-site properties accounts for the highly nonlinear dependence of steady-state depression levels on frequency. PMID:26715759

  11. Environmental Releases for Calendar Year 2001

    SciTech Connect

    DYEKMAN, D L

    2002-08-01

    This report fulfills the annual reporting requirements of US Department of Energy (DOE) Order 5400.1, General Environmental Protection Program. The report contains tabular data summaries on air emissions and liquid effluents released to the environment as well as nonroutine releases during calendar year (CY) 2001. These releases, bearing radioactive and hazardous substances, were from Bechtel Hanford, Inc. (BHI), CH2M HILL Hanford Group, Inc. (CHG), and Fluor Hanford (FH) managed facilities and activities. These data were obtained from direct sampling and analysis and from estimates based upon approved release factors. This report further serves as a supplemental resource to the Hanford Site Environmental Report (HSER PNNL-13910), published by the Pacific Northwest National Laboratory. HSER includes a yearly accounting of the impacts on the surrounding populace and environment from major activities at the Hanford Site. HSER also summarizes the regulatory compliance status of the Hanford Site. Tables ES-1 through ES-5 display comprehensive data summaries of CY2001 air emission and liquid effluent releases. The data displayed in these tables compiles the following: Radionuclide air emissions; Nonradioactive air emissions; Radionuclides in liquid effluents discharged to ground; Total volumes and flow rates of radioactive liquid effluents discharged to ground; and Radionuclides discharged to the Columbia River.

  12. Monitoring ibuprofen enantiomers released from polymeric systems.

    PubMed

    Simó, C; Gallardo, A; Parejo, C; San Román, J; Barbas, C; Cifuentes, A

    2002-07-01

    Two methacrylic derivatives of ibuprofen (N-[4-[2-(4-isobutylphenyl)propionyloxy]phenyl] methacrylamide (MAI) and 2-[(4-isobutylphenyl)propionyloxy]ethyl methacrylate (MEI)) were used together with 2-hydroxyethyl methacrylate (HEMA) to synthesize four polymeric materials: two hydrophobic homopolymers, PMAI and PMEI, and two hydrophilic copolymers containing 70% (w/w) HEMA, MAI-HEMA 30 and MEI-HEMA 30. The enantiomeric determination of R- and S-IBU released from these four systems has been carried out by capillary electrophoresis. Release of R- and S-IBU was monitored during in vitro assays done at 37 degrees C at pH 7.4 and 10 in buffered solutions and rat plasma. There is a hydrolytical activation in plasma and at pH 10 compared to pH 7.4; moreover, the release rate from the copolymers is much higher than from the homopolymers as a consequence of the greater hydrophilic character. A slight excess of the S-enantiomer of IBU is observed in all the experiments, being more relevant at higher release rates, i.e. copolymers at pH 10.

  13. Controlling protein release from scaffolds using polymer blends and composites.

    PubMed

    Ginty, Patrick J; Barry, John J A; White, Lisa J; Howdle, Steve M; Shakesheff, Kevin M

    2008-01-01

    We report the development of three protein loaded polymer blend and composite materials that modify the release kinetics of the protein from poly(dl-lactic acid) (P(dl)LA) scaffolds. P(dl)LA has been combined with either poly(ethylene glycol) (PEG), poly(caprolactone) (PCL) microparticles or calcium alginate fibres using supercritical CO(2) (scCO(2)) processing to form single and dual protein release scaffolds. P(dl)LA was blended with the hydrophilic polymer PEG using scCO(2) to increase the water uptake of the resultant scaffold and modify the release kinetics of an encapsulated protein. This was demonstrated by the more rapid release of the protein when compared to the release rate from P(dl)LA only scaffolds. For the P(dl)LA/alginate scaffolds, the protein loaded alginate fibres were processed into porous protein loaded P(dl)LA scaffolds using scCO(2) to produce dual release kinetics from the scaffolds. Protein release from the hydrophilic alginate fibres was more rapid in the initial stages, complementing the slower release from the slower degrading P(dl)LA scaffolds. In contrast, when protein loaded PCL particles were loaded into P(dl)LA scaffolds, the rate of protein release was retarded from the slow degrading PCL phase.

  14. Building an Efficient Model for Afterburn Energy Release

    SciTech Connect

    Alves, S; Kuhl, A; Najjar, F; Tringe, J; McMichael, L; Glascoe, L

    2012-02-03

    Many explosives will release additional energy after detonation as the detonation products mix with the ambient environment. This additional energy release, referred to as afterburn, is due to combustion of undetonated fuel with ambient oxygen. While the detonation energy release occurs on a time scale of microseconds, the afterburn energy release occurs on a time scale of milliseconds with a potentially varying energy release rate depending upon the local temperature and pressure. This afterburn energy release is not accounted for in typical equations of state, such as the Jones-Wilkins-Lee (JWL) model, used for modeling the detonation of explosives. Here we construct a straightforward and efficient approach, based on experiments and theory, to account for this additional energy release in a way that is tractable for large finite element fluid-structure problems. Barometric calorimeter experiments have been executed in both nitrogen and air environments to investigate the characteristics of afterburn for C-4 and other materials. These tests, which provide pressure time histories, along with theoretical and analytical solutions provide an engineering basis for modeling afterburn with numerical hydrocodes. It is toward this end that we have constructed a modified JWL equation of state to account for afterburn effects on the response of structures to blast. The modified equation of state includes a two phase afterburn energy release to represent variations in the energy release rate and an afterburn energy cutoff to account for partial reaction of the undetonated fuel.

  15. Programmable and on-demand drug release using electrical stimulation

    PubMed Central

    Yi, Y. T.; Sun, J. Y.; Lu, Y. W.; Liao, Y. C.

    2015-01-01

    Recent advancement in microfabrication has enabled the implementation of implantable drug delivery devices with precise drug administration and fast release rates at specific locations. This article presents a membrane-based drug delivery device, which can be electrically stimulated to release drugs on demand with a fast release rate. Hydrogels with ionic model drugs are sealed in a cylindrical reservoir with a separation membrane. Electrokinetic forces are then utilized to drive ionic drug molecules from the hydrogels into surrounding bulk solutions. The drug release profiles of a model drug show that release rates from the device can be electrically controlled by adjusting the stimulated voltage. When a square voltage wave is applied, the device can be quickly switched between on and off to achieve pulsatile release. The drug dose released is then determined by the duration and amplitude of the applied voltages. In addition, successive on/off cycles can be programmed in the voltage waveforms to generate consistent and repeatable drug release pulses for on-demand drug delivery. PMID:25825612

  16. Sustained release of methotrexate through liquid-crystalline folate nanoparticles.

    PubMed

    Misra, Rahul; Mohanty, Sanat

    2014-09-01

    To make chemotherapy more effective, sustained release of the drug is desirable. By controlling the release rates, constant therapeutic levels can be achieved which can avoid re-administration of drug. This helps to combat tumors more effectively with minimal side effects. The present study reports the control release of methotrexate through liquid-crystalline folate nanoparticles. These nanoparticles are composed of highly ordered folate self-assembly which encapsulate methotrexate molecules. These drug molecules can be released in a controlled manner by disrupting this assembly in the environment of monovalent cations. The ordered structure of folate nanoparticles offers low drug losses of about 4-5%, which is significant in itself. This study reports the size-control method of forming methotrexate encapsulated folate nanoparticles as well as the release of methotrexate through these nanoparticles. It has been demonstrated that methotrexate release rates can be controlled by controlling the size of the nanoparticles, cross-linking cation and cross-linking concentration. The effect of different factors like drug loading, release medium, and pH of the medium on methotrexate release rates was also studied.

  17. Hydroxypropyl methylcellulose based cephalexin extended release tablets: influence of tablet formulation, hardness and storage on in vitro release kinetics.

    PubMed

    Saravanan, Muniyandy; Sri Nataraj, Kalakonda; Ganesh, Kettavarampalayam Swaminath

    2003-08-01

    The object of this study was to develop hydroxypropyl methylcellulose (HPMC) based cephalexin extended release tablet, which can release the drug for six hours in predetermined rate. Twenty-one batches of cephalexin tablets were prepared by changing various physical and chemical parameters, in order to get required theoretical release profile. The influences of HPMC, microcrystalline cellulose powder (MCCP), granulation technique, wetting agent and tablet hardness on cephalexin release from HPMC based extended release tablets were studied. The formulated tablets were also characterized by physical and chemical parameters. The dissolution results showed that a higher amount of HPMC in tablet composition resulted in reduced drug release. Addition of MCCP resulted in faster drug release. Tablets prepared by dry granulation was released the drug slowly than the same prepared with a wet granulation technique. Addition of wetting agent in the tablets prepared with dry granulation technique showed slower release. An increase in tablet hardness resulted in faster drug release. Tablets prepared with a wet granulation technique and having a composition of 9.3% w/w HPMC with a hardness of 10-12 kg/cm(2) gave predicted release for 6 h. The in vitro release data was well fit in to Higuchi and Korsmeyer-Peppas model. Physical and chemical parameters of all formulated tablets were within acceptable limits. One batch among formulated twenty-one batches was successful and showed required theoretical release. The effect of storage on in vitro release and physicochemical parameters of successful batch was studied and was found to be in acceptable limits.

  18. [Compound erythromycin sustained release preparation and its in vitro release].

    PubMed

    Chen, Hai-xia; Chen, Zhi-peng; Wang, Qi-rong; Liu, Ze-kun; Ma, Quan-long

    2011-11-01

    Using the weight-average molecular weight 50 000 polylactic acid (PLA) as a carrier, and a certain proportion of erythromycin (EM) and prednisone acetate (PNA) to mixed prepare the compound erythromycin sustained release preparation (sustained-release tablets). Using ultraviolet spectrophotometry and high performance liquid chromatography (HPLC) to detect separately the release amount of EM and PNA in vitro medium. The sustained-release tablets release for about 21 days, the average content of EM is 99.7 mg/table, RSD = 0.82%; and the average content of PNA is 10.03 mg/table, RSD = 0.93%. Within 21 days, the cumulative releases of EM and PNA are 86.1% and 78.3%, respectively. The drug release is steady and slow after 5 days, the burst release phenomenon in early stage is more significant. The results showed that the sustained-release tablet preparation method is feasible, the release performance is good and the clinical efficacy is significant.

  19. QUICK RELEASABLE DRIVE

    DOEpatents

    Dickson, J.J.

    1958-07-01

    A quick releasable mechanical drive system suitable for use in a nuclear reactor is described. A small reversible motor positions a control rod by means of a worm and gear speed reducer, a magnetic torque clutch, and a bell crank. As the control rod is raised to the operating position, a heavy coil spring is compressed. In the event of an emergency indicated by either a''scram'' signal or a power failure, the current to the magnetic clutch is cut off, thereby freeing the coil spring and the bell crank positioner from the motor and speed reduction gearing. The coil spring will immediately act upon the bell crank to cause the insertion of the control rod. This arrangement will allow the slow, accurate positioning of the control rod during reactor operation, while providing an independent force to rapidly insert the rod in the event of an emergency.

  20. Quick release engine cylinder

    DOEpatents

    Sunnarborg, Duane A.

    2000-01-01

    A quick release engine cylinder allows optical access to an essentially unaltered combustion chamber, is suitable for use with actual combustion processes, and is amenable to rapid and repeated disassembly and cleaning. A cylinder member, adapted to constrain a piston to a defined path through the cylinder member, sealingly engages a cylinder head to provide a production-like combustion chamber. A support member mounts with the cylinder member. The support-to-cylinder mounting allows two relationships therebetween. In the first mounting relationship, the support engages the cylinder member and restrains the cylinder against the head. In the second mounting relationship, the cylinder member can pass through the support member, moving away from the head and providing access to the piston-top and head.

  1. SITELLE's Data Release 1

    NASA Astrophysics Data System (ADS)

    Martin, T. B.; Drissen, L.

    2016-12-01

    Installed at the Canada-France-Hawaii Telescope (CFHT) since August 2015, SITELLE is an Imaging Fourier Transform Spectrometer (IFTS) with an 11×11 field of view. After its prototype SpIOMM, installed at Mont Mégantic (Québec, Canada), it is the second IFTS in the world operating in the visible band (350-1000 nm). It delivers hyperspectral data cubes of 4 million spectra at R˜1500-5000 with a spatial sampling of 0.32" and a filling factor of 100 %. A suite of softwares has been designed to reduce (ORBS) and analyze (ORCS) the data. Based on commissioning data obtained in August 2015, a first stable version has been released in March 2016 which is capable of reducing all the data. In this paper the quality of the calibration is discussed.

  2. Characteristics of CO2 release from forest soil in the mountains near Beijing.

    PubMed

    Sun, Xiang Yang; Gao, Cheng Da; Zhang, Lin; Li, Su Yan; Qiao, Yong

    2011-04-01

    CO2 release from forest soil is a key driver of carbon cycling between the soil and atmosphere ecosystem. The rate of CO2 released from soil was measured in three forest stands (in the mountainous region near Beijing, China) by the alkaline absorption method from 2004 to 2006. The rate of CO2 released did not differ among the three stands. The CO2 release rate ranged from - 341 to 1,193 mg m(-2) h(-1), and the mean value over all three forests and sampling times was 286 mg m(-2) h(-1). CO2 release was positively correlated with soil water content and the soil temperature. Diurnally, CO2 release was higher in the day than at night. Seasonally, CO2 release was highest in early autumn and lowest in winter; in winter, negative values of CO2 release suggested that CO2 was absorbed by soil.

  3. Effects of formulation and process variables on the release of a weakly basic drug from single unit extended release formulations.

    PubMed

    Kranz, H; Wagner, T

    2006-01-01

    A new commercially available extended release matrix material, Kollidon SR, composed of polyvinylacetate (PVA) and polyvinylpyrrolidone (PVP), was evaluated with respect to its ability to modulate the in vitro release of the weakly basic drug ZK 811 752. The effect of different formulation and process parameters on the release kinetics of ZK 811 752 from PVA/PVP based matrix tablets was investigated as a function of the (i) nature of excipient added to the drug-polymer mixtures, (ii) method of manufacturing (direct compression versus wet granulation), and (iii) effect of a post-compression curing step. ZK 811 752 containing extended release matrix tablets were successfully prepared by using Kollidon SR. The drug release from the matrix tablets increased by the addition of excipients such as maize starch, lactose and calcium phosphate. Addition of the highly swellable maize starch and the water-soluble lactose accelerated the drug release in a more pronounced manner compared to the water-insoluble calcium phosphate. Compound release from matrix tablets prepared by wet granulation was faster compared to the drug release from tablets prepared by direct compression. Post compression curing did not influence the drug release rate from drug-lactose-Kollidon SR formulations. Stability studies demonstrated no degradation of the drug substance and reproducible drug release patterns for matrix tablets stored at 25 degrees C/60% RH and 30 degrees C/70% RH for up to 6 months.

  4. Chlorhexidine-releasing methacrylate dental composite materials.

    PubMed

    Leung, Danny; Spratt, David A; Pratten, Jonathan; Gulabivala, Kishor; Mordan, Nicola J; Young, Anne M

    2005-12-01

    Light curable antibacterial, dental composite restoration materials, consisting of 80 wt% of a strontium fluoroaluminosilicate glass dispersed in methacrylate monomers have been produced. The monomers contained 40-100 wt% of a 10 wt% chlorhexidine diacetate (CHXA) in hydroxyethylmethacrylate (HEMA) solution and 60-0 wt% of a 50/50 mix of urethane dimethacrylate (UDMA) and triethyleneglycol dimethacrylate (TEGDMA). On raising HEMA content, light cure polymerisation rates decreased. Conversely, water sorption induced swelling and rates of diffusion controlled CHXA release from the set materials increased. Experimental composites with 50 and 90 wt% of the CHXA in HEMA solution in the monomer were shown, within a constant depth film fermentor (CDFF), to have slower rates of biofilm growth on their surfaces between 1 and 7 days than the commercial dental composite Z250 or fluoride-releasing dental cements, Fuji II LC and Fuji IX. When an excavated bovine dentine cylinder re-filled with Z250 was placed for 10 weeks in the CDFF, both bacteria and polymers from the artificial saliva penetrated between the material and dentine. With the 50 wt% experimental HEMA/CHXA formulation, this bacterial microleakage was substantially reduced. Polymer leakage, however, still occurred. Both polymer and bacterial microleakage were prevented with a 90 wt% HEMA/CHXA restoration in the bovine dentine due to swelling compensation for polymerisation shrinkage in combination with antibacterial release.

  5. Understanding and managing the impact of HPMC variability on drug release from controlled release formulations.

    PubMed

    Zhou, Deliang; Law, Devalina; Reynolds, Judie; Davis, Lynn; Smith, Clifford; Torres, Jose L; Dave, Viraj; Gopinathan, Nishanth; Hernandez, Daniel T; Springman, Mary Kay; Zhou, Casey Chun

    2014-06-01

    The purpose of this study is to identify critical physicochemical properties of hydroxypxropyl methylcellulose (HPMC) that impact the dissolution of a controlled release tablet and develop a strategy to mitigate the HPMC lot-to-lot and vendor-to-vendor variability. A screening experiment was performed to evaluate the impacts of methoxy/hydroxypropyl substitutions, and viscosity on drug release. The chemical diversity of HPMC was explored by nuclear magnetic resonance (NMR), and the erosion rate of HPMC was investigated using various dissolution apparatuses. Statistical evaluation suggested that the hydroxypropyl content was the primary factor impacting the drug release. However, the statistical model prediction was not robust. NMR experiments suggested the existence of structural diversity of HPMC between lots and more significantly between vendors. Review of drug release from hydrophilic matrices indicated that erosion is a key aspect for both poorly soluble and soluble drugs. An erosion rate method was then developed, which enabled the establishment of a robust model and a meaningful HPMC specification. The study revealed that the overall substitution level is not the unique parameter that dictates its release-controlling properties. Fundamental principles of polymer chemistry and dissolution mechanisms are important in the development and manufacturing of hydrophilic matrices with consistent dissolution performance.

  6. Stored energy release behaviour of disordered carbon

    NASA Astrophysics Data System (ADS)

    Dasgupta, K.; Barat, P.; Sarkar, A.; Mukherjee, P.; Sathiyamoorthy, D.

    2007-06-01

    The use of graphite as a moderator in a low temperature thermal nuclear reactor is restricted due to accumulation of energy caused by displacement of atoms by neutrons and high energetic particles. Thermal transients may lead to a release of stored energy that may raise the temperature of the fuel clad above the design limit. Disordered carbon is thought to be an alternative choice for this purpose. Two types of disordered carbon composites, namely, CB (made up of 15 wt. % carbon black dispersed in carbonized phenolic resin) and PAN (made up of 20 vol. % chopped polyacrylonitrile carbon fibre dispersed in carbonized phenolic resin matrix) have been irradiated with 145 MeV Ne6+ ions at three fluence levels of 1.0×1013, 5.0×1013 and 1.5×1014 Ne6+/cm2, respectively. The XRD patterns revealed that both the samples remained disordered even after irradiation. The maximum release of stored energy for CB was 212 J/g and that of PAN was 906 J/g. For CB, the release of stored energy was a first order reaction with activation energy of 2.79 eV and a frequency factor of 3.72×1028 per second. 13% of the defects got annealed by heating up to 700 °C. PAN showed a third-order release rate with activation energy of 1.69 eV and a frequency factor of 1.77×1014 per second. 56% of the total defects got annealed by heating it up to 700 °C. CB seems to be the better choice than PAN as it showed less energy release with a slower rate.

  7. A mathematical model for pulsatile release: controlled release of rhodamine B from UV-crosslinked thermoresponsive thin films.

    PubMed

    Yang, Rongbing; Vo T N, Tuoi; Gorelov, Alexander V; Aldabbagh, Fawaz; Carroll, William M; Meere, Martin G; Rochev, Yury

    2012-05-10

    A controlled drug delivery system fabricated from a thermoresponsive polymer was designed to obtain a pulsatile release profile which was triggered by altering the temperature of the dissolution medium. Two stages of release behaviour were found: fast release for a swollen state and slow (yet significant and non-negligible) release for a collapsed state. Six cycles of pulsatile release between 4 °C and 40 °C were obtained. The dosage of drug (rhodamine B) released in these cycles could be controlled to deliver approximately equal doses by altering the release time in the swollen state. However, for the first cycle, the swollen release rate was found to be large, and the release time could not be made short enough to prevent a larger dose than desired being delivered. A model was developed based on Fick's law which describes pulsatile release mathematically for the first time, and diffusion coefficients at different temperatures (including temperatures corresponding to both the fully swollen and collapsed states) were estimated by fitting the experimental data with the theoretical release profile given by this model. The effect of temperature on the diffusion coefficient was studied and it was found that in the range of the lower critical solution temperature (LCST), the diffusion coefficient increased with decreasing temperature. The model predicts that the effective lifetime of the system lies in the approximate range of 1-42 h (95% of drug released), depending on how long the system was kept at low temperature (below the LCST). Therefore this system can be used to obtain a controllable pulsatile release profile for small molecule drugs thereby enabling optimum therapeutic effects.

  8. Hanford production reactor heat releases 1951--1971

    SciTech Connect

    Kannberg, L.D.

    1992-04-01

    The purpose of this report is to document and detail the thermal releases from the Hanford nuclear production reactors during the period 1951 through 1971, and to put these releases in historical perspective with respect to changing Columbia River flows and temperatures. This information can also be used as a foundation for further ecological evaluations. When examining Hanford production reactor thermal releases to the Columbia River all related factors affecting the releases and the characteristics of the river should be considered. The major considerations in the present study were the characteristics of the releases themselves (primarily coolant flow rate, temperatures, discharge facilities, period of operation, and level of operation) and the characteristics of the river in that reach (primarily flow rate, temperature and mixing characteristics; the effects of dam construction were also taken into account). In addition, this study addressed ecological effects of thermal releases on aquatic species. Accordingly, this report includes discussion of the reactor cooling system, historical heat releases, thermal mixing and transport studies, hydroelectric power development, and ecologic effects of Hanford production reactor heat releases on salmon and trout. Appendix A contains reactor operating statistics, and Appendix B provide computations of heat added to the Columbia River between Priest Rapids Dam and Richland, Washington.

  9. Optogenetic control of ATP release

    NASA Astrophysics Data System (ADS)

    Lewis, Matthew A.; Joshi, Bipin; Gu, Ling; Feranchak, Andrew; Mohanty, Samarendra K.

    2013-03-01

    Controlled release of ATP can be used for understanding extracellular purinergic signaling. While coarse mechanical forces and hypotonic stimulation have been utilized in the past to initiate ATP release from cells, these methods are neither spatially accurate nor temporally precise. Further, these methods cannot be utilized in a highly effective cell-specific manner. To mitigate the uncertainties regarding cellular-specificity and spatio-temporal release of ATP, we herein demonstrate use of optogenetics for ATP release. ATP release in response to optogenetic stimulation was monitored by Luciferin-Luciferase assay (North American firefly, photinus pyralis) using luminometer as well as mesoscopic bioluminescence imaging. Our result demonstrates repetitive release of ATP subsequent to optogenetic stimulation. It is thus feasible that purinergic signaling can be directly detected via imaging if the stimulus can be confined to single cell or in a spatially-defined group of cells. This study opens up new avenue to interrogate the mechanisms of purinergic signaling.

  10. Sulphate release from building rubble of WWII

    NASA Astrophysics Data System (ADS)

    Mekiffer, Beate; Wessolek, Gerd; Vogeler, Iris; Brettholle, Mareike

    2010-05-01

    Sulphate concentration in the upper aquifer of Berlin, Germany is increasing continuously since 40 years. In downtown Berlin they particular exceed the precaution values of drinking water ordinance. We assume that the main source of sulphate in the groundwater is technogenic material, which is part of building rubble from WW II bombing. Nearly 115 Mio t of this material have been deposited in Berlin. Our aim is, ­ to identify rubble components which contain S and to quantify the S-pool of this material ­ to identify factors, influencing the release of SO4 and ­ to predict sulphate release from building rubble of WW II We analyzed total and water soluble S of various components and the fine earth fraction of the soils containing the rubble. We investigated the influence of physical and chemical parameters on the release of SO4 using unsaturated column experiments (With an automatic percolation system). Thereby, the particle size, the flow rate and the pH of the solution has been varied. Among the components, slag shows the highest total S-contents of up to 0,7% . Lignite Coal-ashes from Lusatia, Germany are also rich in SO4. The total S of brick varies between 0,01% and 0,3%. Mortar shows S-Values between 0,08 and 0,12%. In 75% of all samples show total S of less than 0,14%. There was no significant correlation between total S-amount and water-soluble SO4, which is caused by different chemical compounds in the samples. In the percolation experiments technogenic components with grain size <2mm cause a higher density, resulting in a lower percolation velocity. The concentration of ions in the according leachate is higher than in the leachate of coarse fraction (2 - 20mm). Gypsum-rich material (10%) released constant SO4 -concentration over the whole experiment. Slag-rich material released high initial SO4-concentrations which then fastly decreased. We concluded, that the kind of technogenic component and its grain size strongly influences the release of SO4 to the

  11. Comparison of acute behavioral effects of sustained-release and immediate-release methylphenidate.

    PubMed

    Kollins, S H; Rush, C R; Pazzaglia, P J; Ali, J A

    1998-11-01

    The rate of onset of a drug's effect is an important determinant of its abuse potential. This experiment examined the acute behavioral effects of orally administered sustained-release methylphenidate (SR; 20-40 mg), immediate-release methylphenidate (IR; 20-40 mg), and placebo in 10 healthy volunteers. Drug effects were assessed before drug administration and periodically afterwards for 6 hr using drug-effect questionnaires and performance measures that are sensitive to the acute effects of stimulants. The IR formulation produced stimulant-like drug effects (e.g., increased ratings of "good effects") that generally varied as a function of dose and time. The SR formulation produced only transient effects on these measures. These findings are consistent with previous research on the influence of rate of onset using other drugs and suggest that the abuse potential of IR methylphenidate may be greater than that of SR methylphenidate.

  12. A biokinetic model for nickel released from cardiovascular devices.

    PubMed

    Saylor, David M; Adidharma, Lingga; Fisher, Jeffrey W; Brown, Ronald P

    2016-10-01

    Many alloys used in cardiovascular device applications contain high levels of nickel, which if released in sufficient quantities, can lead to adverse health effects. While nickel release from these devices is typically characterized through the use of in-vitro immersion tests, it is unclear if the rate at which nickel is released from a device during in-vitro testing is representative of the release rate following implantation in the body. To address this uncertainty, we have developed a novel biokinetic model that combines a traditional toxicokinetic compartment model with a physics-based model to estimate nickel release from an implanted device. This model links the rate of in-vitro nickel release from a cardiovascular device to serum nickel concentrations, an easily measured endpoint, to estimate the rate and extent of in-vivo nickel release from an implanted device. The model was initially parameterized using data in the literature on in-vitro nickel release from a nickel-containing alloy (nitinol) and baseline serum nickel levels in humans. The results of this first step were then used to validate specific components of the model. The remaining unknown quantities were fit using serum values reported in patients following implantation with nitinol atrial occluder devices. The model is not only consistent with levels of nickel in serum and urine of patients following treatment with the atrial occluders, but also the optimized parameters in the model were all physiologically plausible. The congruity of the model with available data suggests that it can provide a framework to interpret nickel biomonitoring data and use data from in-vitro nickel immersion tests to estimate in-vivo nickel release from implanted cardiovascular devices.

  13. Floodplain Hyporheic Response under Dam Release Hydrographs

    NASA Astrophysics Data System (ADS)

    Zhou, T.; Ward, A. S.; O'Connor, B. L.; Endreny, T. A.

    2012-12-01

    Hydropower operations cause altered hydrograph patterns downstream of dams, which regulates the direction and magnitude of floodplain and riverbed hyporheic flux. Periodic adjustments in river stage changes temporal and spatial patterns in hydraulic pressure, initiates propagation of lateral and vertical hyporheic flux, and affects the riparian ecological system by changing the hyporheic penetration distance, hyporheic flux rate, and thermal conditions in river banks. While this issue has been largely neglected by watershed scientists and managers, there is the potential to use hyporheic metrics in setting dam release rules and restoring downstream river reaches. In order to evaluate the hyporheic feedbacks of various dam release patterns, this study applied a computational fluid dynamics (CFD) model to simulate the interaction of open water hydrographs on porous media lateral hyporheic exchange for the Green River, Utah, downstream of Flaming Gorge Dam. The CFD initially represented the river as a straight channel with a thick porous media extending from the channel banks and bottom. The dam release hydrographs changed the patterns of hyporheic flux at the river banks, the penetration distance of the hyporheic flux, the subsurface thermal patterns, and the residence time of water in the subsurface. The results suggest the undulating river stage downstream of dam releases can initiate patterns of hyporheic exchange similar to those induced by restoration of river bed morphology.

  14. Releasable Conjugation of Polymers to Proteins.

    PubMed

    Gong, Yuhui; Leroux, Jean-Christophe; Gauthier, Marc A

    2015-07-15

    Many synthetic strategies are available for preparing well-defined conjugates of peptides/proteins and polymers. Most reports on this topic involve coupling methoxy poly(ethylene glycol) to therapeutic proteins, a process referred to as PEGylation, to increase their circulation lifetime and reduce their immunogenicity. Unfortunately, the major dissuading dogma of PEGylation is that, in many cases, polymer modification leads to significant (or total) loss of activity/function. One approach that is gaining momentum to address this challenge is to release the native protein from the polymer with time in the body (releasable PEGylation). This contribution will present the state-of-the-art of this rapidly evolving field, with emphasis on the chemistry behind the release of the peptide/protein and the means for altering the rate of release in biological fluids. Linkers discussed include those based on the following: substituted maleic anhydride and succinates, disulfides, 1,6-benzyl-elimination, host-guest interactions, bicin, β-elimination, biodegradable polymers, E1cb elimination, β-alanine, photoimmolation, coordination chemistry, zymogen activation, proteolysis, and thioesters.

  15. A vacuum microgripping tool with integrated vibration releasing capability

    SciTech Connect

    Rong, Weibin; Fan, Zenghua Wang, Lefeng; Xie, Hui; Sun, Lining

    2014-08-01

    Pick-and-place of micro-objects is a basic task in various micromanipulation demands. Reliable releasing of micro-objects is usually disturbed due to strong scale effects. This paper focuses on a vacuum micro-gripper with vibration releasing functionality, which was designed and assembled for reliable micromanipulation tasks. Accordingly, a vibration releasing strategy of implementing a piezoelectric actuator on the vacuum microgripping tool is presented to address the releasing problem. The releasing mechanism was illustrated using a dynamic micro contact model. This model was developed via theoretical analysis, simulations and pull-off force measurement using atomic force microscopy. Micromanipulation experiments were conducted to verify the performance of the vacuum micro-gripper. The results show that, with the assistance of the vibration releasing, the vacuum microgripping tool can achieve reliable release of micro-objects. A releasing location accuracy of 4.5±0.5 μm and a successful releasing rate of around 100% (which is based on 110 trials) were achieved for manipulating polystyrene microspheres with radius of 35–100 μm.

  16. Compounding of slow-release niacinamide capsules: feasibility and characterization.

    PubMed

    Radojkovic, Branko; Milić, Jela; Calija, Bojan

    2012-01-01

    The purpose of this study was to assess the feasibility of extemporaneous compounding of slow-release oral dosage form of niacinamide and to evaluate its release kinetics. The model formulation (preparation) was developed in the form of powder-filled hard gelatin capsules. Two slow-release preparations with different ratios of hypromellose have been prepared and evaluated in comparison with an immediate-release preparation. The dissolution tests were performed as per United States Pharmacopoeia requirements: Type I Apparatus, over 7 hours. Both slow-release preparations, containing 40% and 60% v/v hypromellose, respectively, have showed slow release kinetics. The dissolution profiles were significantly different, with similarity factor f2<50. The dissolution data demonstrated Korsmeyer-Peppas kinetics with n values indicating anomalous transport. In conclusion, the results of this study suggest that slow-release niacinamide capsules can be successfully compounded using hypromellose as a sole release rate modifier, and that the release mechanism is comparable to hydrophilic polymer matrix-based systems.

  17. Predicting red wolf release success in the southeastern United States

    USGS Publications Warehouse

    van Manen, Frank T.; Crawford, Barron A.; Clark, Joseph D.

    2000-01-01

    Although the red wolf (Canis rufus) was once found throughout the southeastern United States, indiscriminate killing and habitat destruction reduced its range to a small section of coastal Texas and Louisiana. Wolves trapped from 1973 to 1980 were taken to establish a captive breeding program that was used to repatriate 2 mainland and 3 island red wolf populations. We collected data from 320 red wolf releases in these areas and classified each as a success or failure based on survival and reproductive criteria, and whether recaptures were necessary to resolve conflicts with humans. We evaluated the relations between release success and conditions at the release sites, characteristics of released wolves, and release procedures. Although <44% of the variation in release success was explained, model performance based on jackknife tests indicated a 72-80% correct prediction rate for the 4 operational models we developed. The models indicated that success was associated with human influences on the landscape and the level of wolf habituation to humans prior to release. We applied the models to 31 prospective areas for wolf repatriation and calculated an index of release success for each area. Decision-makers can use these models to objectively rank prospective release areas and compare strengths and weaknesses of each.

  18. In vitro release of metoclopramide from hydrophobic matrix tablets. influence of hydrodynamic conditions on kinetic release parameters.

    PubMed

    Frutos, P; Pabón, C; Lastres, J L; Frutos, G

    2001-10-01

    There has been growing interest in the subject of drug delivery and the design and evaluation of controlled-release systems. The simplest way to control the release of an active agent is to disperse it in an inert polymeric matrix. Controlled-release systems are of interest because they are technologically simple, relatively cheap, and practically unaffected by physiological changes. In this study, a new matrix system was formed by an active principle, metoclopramide hydrochloride, scattered into a biocompatible hydrophobic polymerical mesh, polyamide 12, to achieve sustained and controlled delivery of metoclopramide hydrochloride. This research was conducted to investigate the in vitro drug release behavior from these new inert polymeric matrix tablets. The drug release process was investigated both experimentally and by means of mathematical models. Different models were applied for the evaluation of drug release data. On the basis of our results, a biexponential equation was proposed, Q=Qfast(1)(1 - e(-Kfast t)) + Qslow(2)(1 - e(-Kslow t)), in an attempt to explain the mechanism responsible for the release process. Additionally, the influence of the experimental conditions of the dissolution devices, such as rate of flow and pH of dissolution medium, on the parameters that characterize the release mechanism was studied, and it was found that the main factor was the hydrodynamic condition of rate of flow.

  19. In vitro release of theophylline from poly(lactic acid) sustained-release pellets prepared by direct compression.

    PubMed

    Kader, A; Jalil, R

    1998-06-01

    Poly(L-lactic acid), (L-PLA) pellets containing theophylline as a model drug were prepared with increasing bovine serum albumin (BSA) load of 10, 20, 30, 40, or 50% by direct compression. The drug release from pellets was studied in phosphate buffered saline (PBS, pH 7.4) at 37 degrees C. The annealing effect on theophylline release from pellets was also studied at 20, 30, 60, and 80 degrees C. In all cases, release kinetics followed the Higuchian mechanism with an initial burst effect followed by sustained release of theophylline during the experimental period. Increasing BSA load resulted in a linear increase in Higuchian release rates presumably because of the hydrophilic nature of BSA. Furthermore, BSA did not interact chemically with the polymer matrix and was held physically by the dense polymer matrix. However, drug release decreased with an increase in annealing temperature. Release of theophylline was higher from PLA-BSA combination pellets compared to PLA pellets at temperatures below the glass transition temperature (Tg) of the polymer and lower for temperatures above Tg. The temperature effect on drug release may be attributed to both the reduction of core solubility in the bulk phase and the lowering of diffusibility of the polymeric membrane. No drug-polymer interactions or polymer degradation was observed within the experimental setup when studied by differential scanning calorimetry (DSC), infrared (FTIR) spectroscopy, and gravimetric methods. DSC studies of pellets showed no hints of microstructural changes (crystallinity) of the polymers. In our experiments, theophylline was released primarily by leaching through channels and not by polymer degradation. The release rate was dependent on BSA loading and annealing. It may be concluded that PLA pellets can be fabricated suitably using BSA and annealing to design sustained-release preparations of water-soluble drugs.

  20. Materials for storage and release of hydrogen and methods for preparing and using same

    DOEpatents

    Autrey, Thomas S.; Gutowska, Anna; Shin, Yongsoon; Li, Liyu

    2008-01-08

    The invention relates to materials for storing and releasing hydrogen and methods for preparing and using same. The materials exhibit fast release rates at low release temperatures and are suitable as fuel and/or hydrogen sources for a variety of applications such as automobile engines.

  1. 76 FR 8946 - Security Ratings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-16

    ... From the Federal Register Online via the Government Publishing Office ] SECURITIES AND EXCHANGE COMMISSION 17 CFR Parts 200, 229, 230, 232, 239, 240, and 249 RIN 3235-AK18 Security Ratings AGENCY: Securities and Exchange Commission. ACTION: Proposed rule. SUMMARY: This is one of several releases that...

  2. Press-coating of immediate release powders onto coated controlled release tablets with adhesives.

    PubMed

    Waterman, Kenneth C; Fergione, Michael B

    2003-05-20

    A novel adhesive coating was developed that allows even small quantities of immediate-release (IR) powders to be press-coated onto controlled-release (CR), coated dosage forms without damaging the CR coating. The process was exemplified using a pseudoephedrine osmotic tablet (asymmetric membrane technology, AMT) where a powder weighing less than 25% of the core was pressed onto the osmotic tablet providing a final combination tablet with low friability. The dosage form with the adhesive plus the press-coated powder showed comparable sustained drug release rates to the untreated dosage form after an initial 2-h lag. The adhesive layer consisted of an approximately 100- microm coating of Eudragit RL, polyethylene glycol (PEG) and triethyl citrate (TEC) at a ratio of 5:3:1.2. This coating provides a practical balance between handleability before press-coating and good adhesion.

  3. Influence of formulation composition and process on the characteristics and in vitro release from PLGA-based sustained release injectables.

    PubMed

    Meeus, Joke; Scurr, David J; Appeltans, Bernard; Amssoms, Katie; Annaert, Pieter; Davies, Martyn C; Roberts, Clive J; Van den Mooter, Guy

    2015-02-01

    Understanding and controlling the in vitro release behavior of a formulation is a first step toward rationalized selection of a solubility enhancing formulation strategy with a desired release profile in vivo. Therefore six model formulations, representing three different formulation strategies, were physicochemically analyzed and their in vitro release was determined. Solid dispersions based on a PLGA/PVP matrix were compared to solid dispersions in a pure PLGA matrix. Additionally these solid dispersion strategies were compared to the strategy of particle size reduction by means of an API microsuspension. Depending on composition and manufacturing method, formulations varied in particle size, porosity, phase behavior, surface coverage and physical state of the API. This resulted in observed differences in their in vitro release profile. For the various formulation strategies tested both a porous PLGA-based formulation and PLGA/PVP-based formulations, resulted in vitro in sustained release of the poorly soluble API with over 50% of drug released after 24h. For PLGA-based formulations the porosity was identified as a critical parameter influencing in vitro drug release. For the PLGA/PVP-based formulations the release rate can be tailored by the amount of PLGA present. Particle size reduction resulted in immediate total drug release.

  4. Modeling controlled nutrient release from a population of polymer coated fertilizers: statistically based model for diffusion release.

    PubMed

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A statistically based model for describing the release from a population of polymer coated controlled release fertilizer (CRF) granules by the diffusion mechanism was constructed. The model is based on a mathematical-mechanistic description of the release from a single granule of a coated CRF accounting for its complex and nonlinear nature. The large variation within populations of coated CRFs poses the need for a statistically based approach to integrate over the release from the individual granules within a given population for which the distribution and range of granule radii and coating thickness are known. The model was constructed and verified using experimentally determined parameters and release curves of polymer-coated CRFs. A sensitivity analysis indicated the importance of water permeability in controlling the lag period and that of solute permeability in governing the rate of linear release and the total duration of the release. Increasing the mean values of normally distributed granule radii or coating thickness, increases the lag period and the period of linear release. The variation of radii and coating thickness, within realistic ranges, affects the release only when the standard deviation is very large or when water permeability is reduced without affecting solute permeability. The model provides an effective tool for designing and improving agronomic and environmental effectiveness of polymer-coated CRFs.

  5. Regulation of serotonin release from enterochromaffin cells of rat cecum mucosa

    SciTech Connect

    Simon, C.; Ternaux, J.P. )

    1990-05-01

    The release of endogenous serotonin or previously taken up tritiated serotonin from isolated strips of rat cecum mucosa containing enterochromaffin cells was studied in vitro. Release of tritiated serotonin was increased by potassium depolarization and was decreased by tetrodotoxin, veratridine and the absence of calcium. Endogenous serotonin was released at a lower rate than tritiated serotonin; endogenous serotonin release was stimulated by potassium depolarization but was unaffected by tetrodotoxin, veratridine or the absence of calcium. Carbachol, norepinephrine, clonidine and isoproterenol decreased release of tritiated serotonin but had less or reverse effect on release of endogenous serotonin. The results suggest two different serotoninergic pools within the enterochromaffin cell population.

  6. Drug release behavior from nanoporous anodic aluminum oxide.

    PubMed

    Kwak, Dae-Hyun; Yoo, Ji-Beom; Kim, Deug Joong

    2010-01-01

    In this study, we developed a new drug delivery system using anodic oxidation. The growth of a porous oxide layer on aluminum under anodic bias in various electrolytes has been studied for more than 40 years. Anodic Aluminum Oxide (AAO) has many uniform nanopores on its surface. This nanoporous surface can be used for drug storage. The effects of the diameter and depth of the AAO on the release characteristics of a drug were investigated. Paclitaxel was used for the drug loading and release test. Paclitaxel was loaded on the inside of the AAO by ultrasonication. The amount of the drug released from the AAO was analyzed by high performance liquid chromatography (HPLC). The pore size did not affect the drug release behavior. However, the depth of the pores had a significant influence on the release rate of the drug.

  7. Alternate polyelectrolyte coating of chitosan beads for extending drug release.

    PubMed

    Srinatha, A; Pandit, Jayanta K

    2008-01-01

    In the present study, we addressed the factors modifying ciprofloxacin release from multiple coated beads. Beads were prepared by simple ionic cross-linking with sodium tripolyphoshate and coated with alginate and/or chitosan to prepare single, double, or multilayered beads. The water uptake capacity depended on the nature of beads (coated or uncoated) and pH of test medium. The number of coatings given to the beads influenced ciprofloxacin release rate. The coating significantly decreased the drug release from the beads in comparison to uncoated beads (p < 0.001). When the beads were given three coatings, viz., alginate, chitosan, and again alginate, the drug release appeared to follow the pattern exhibited by colon-targeted drug delivery systems with time dependent release behavior. The increase in coating formed a barrier for easy ingress of dissolution medium into the bead matrix, reducing the diffusion of drug.

  8. Effects of light intensity and water temperature on oxygen release from roots into water lettuce rhizosphere.

    PubMed

    Soda, S; Ike, M; Ogasawara, Y; Yoshinaka, M; Mishima, D; Fujita, M

    2007-01-01

    The oxygen release rate into the rhizosphere by a floating aquatic plant-water lettuce-was determined under various light intensities (0.0-1.2x10(5)lx) and water temperatures (10-35 degrees C). The net specific oxygen release rate was expressed by a model equation comprising the gross oxygen release rate and the rhizosphere respiration terms. Experimental and simulated results show that the net specific oxygen release rate increased with light intensity up to the optimal value, but slight inhibition by higher light intensities was observed at 10-20 degrees C. With increased water temperature, the respiration rate became larger than the gross oxygen release rate. The maximum net specific oxygen release rate of 11.0-12.5mg-O(2)kg-wet(-1)h(-1) was obtained at the optimal condition of about 25 degrees C and 9.0x10(4)-1.1x10(5)lx. The net oxygen release rate was negligible at 35 degrees C at any light intensity because the respiration rate was much greater than the gross oxygen release rate into the rhizosphere.

  9. Controlled Release Applications of Organometals.

    ERIC Educational Resources Information Center

    Thayer, John S.

    1981-01-01

    Reviews two classes of controlled release organometals: (1) distributional, to distribute bioactive materials to control a certain target organism; and (2) protective, to protect surface or interior of some structure from attach by organisms. Specific examples are given including a discussion of controlled release for schistosomiasis. (SK)

  10. Kepler Data Release 4 Notes

    NASA Technical Reports Server (NTRS)

    Van Cleve, Jeffrey (Editor); Jenkins, Jon; Caldwell, Doug; Allen, Christopher L.; Batalha, Natalie; Bryson, Stephen T.; Chandrasekaran, Hema; Clarke, Bruce D.; Cote, Miles T.; Dotson, Jessie L.; Gilliland, Ron; Girouard, Forrest; Haas, Michael R.; Hall, Jennifer; Ibrahim, Khadeejah; Klaus, Todd; Kolodziejczak, Jeff; Li, Jie; McCauliff, Sean D.; Middour, Christopher K.; Pletcher, David L.; Quintana, Elisa V.; Tenenbaum, Peter G.; Twicken, Joe; Uddin, Akm Kamal

    2010-01-01

    The Data Analysis Working Group have released long and short cadence materials, including FFIs and Dropped Targets for the Public. The Kepler Science Office considers Data Release 4 to provide "browse quality" data. These notes have been prepared to give Kepler users of the Multimission Archive at STScl (MAST) a summary of how the data were collected and prepared, and how well the data processing pipeline is functioning on flight data. They will be updated for each release of data to the public archive and placed on MAST along with other Kepler documentation, at http://archive.stsci.edu/kepler/documents.html. Data release 3 is meant to give users the opportunity to examine the data for possibly interesting science and to involve the users in improving the pipeline for future data releases. To perform the latter service, users are encouraged to notice and document artifacts, either in the raw or processed data, and report them to the Science Office.

  11. Electrospinning nanofibers for controlled drug release

    NASA Astrophysics Data System (ADS)

    Banik, Indrani

    Electrospinning is the most widely studied technique for the synthesis of nanofibers. Electrospinning is considered as one of the technologies that can produce nanosized drugs incorporated in polymeric nanofibers. In vitro and in vivo studies have demonstrated that the release rates of drugs from these nanofiber formulations are enhanced compared to those from original drug substance. This technology has the potential for enhancing the oral delivery of poorly soluble drugs. The electrospun mats were made using Polycaprolactone/PCL, Poly(DL-lactide)/PDL 05 and Poly(DL-lactide-co-glycolide)/PLGA. The drugs incorporated in the electrospun fibers were 5-Fluorouracil and Rapamycin. The evidence of the drugs being embedded in the polymers was obtained by scanning electron microscopy (SEM), Raman and infrared spectroscopy. The release of 5-Fluorouracil and Rapamycin were followed by UV-VIS spectroscopy.

  12. ORNL fission product release tests VI-6

    SciTech Connect

    Osborne, M.F.; Lorenz, R.A.; Collins, J.L.; Lee, C.S.

    1991-01-01

    The ORNL fission product release tests investigate release and transport of the major fission products from high-burnup fuel under LWR accident conditions. The two most recent tests (VI-4 and VI-5) were conducted in hydrogen. In three previous tests in this series (VI-1, VI-2, and VI-3), which had been conducted in steam, the oxidized Zircaloy cladding remained largely intact and acted as a barrier to steam reaction with the UO{sub 2}. Test VI-6 was designed to insure significant oxidation of the UO{sub 2} fuel, which has been shown to enhance release of certain fission products, especially molybdenum and ruthenium. The BR3 fuel specimen used in test VI-6 will be heated in hydrogen to 2300 K; the Zircaloy cladding is expected to melt and runoff at {approximately}2150 K. Upon reaching the 2300 K test temperature, the test atmosphere will be changed to steam, and that temperature will be maintained for 60 min, with the three collection trains being operated for 2-, 18-, and 40-min periods. The releases of {sup 85}Kr and {sup 137}Cs will be monitored continuously throughout the test. Posttest analyses of the material collected on the three trains will provide results on the release and transport of Mo, Ru, Sb, Te, Ba, Ce, and Eu as a function of time at 2300 K. Continuous monitoring of the hydrogen produced during the steam atmosphere period at high temperature will provide a measure of the oxidation rate of the cladding and fuel. Following delays in approval of the safety documentation and in decontamination of the hot cell and test apparatus, test VI-6 will be conducted in late May.

  13. Hybridization and Selective Release of DNA Microarrays

    SciTech Connect

    Beer, N R; Baker, B; Piggott, T; Maberry, S; Hara, C M; DeOtte, J; Benett, W; Mukerjee, E; Dzenitis, J; Wheeler, E K

    2011-11-29

    DNA microarrays contain sequence specific probes arrayed in distinct spots numbering from 10,000 to over 1,000,000, depending on the platform. This tremendous degree of multiplexing gives microarrays great potential for environmental background sampling, broad-spectrum clinical monitoring, and continuous biological threat detection. In practice, their use in these applications is not common due to limited information content, long processing times, and high cost. The work focused on characterizing the phenomena of microarray hybridization and selective release that will allow these limitations to be addressed. This will revolutionize the ways that microarrays can be used for LLNL's Global Security missions. The goals of this project were two-fold: automated faster hybridizations and selective release of hybridized features. The first study area involves hybridization kinetics and mass-transfer effects. the standard hybridization protocol uses an overnight incubation to achieve the best possible signal for any sample type, as well as for convenience in manual processing. There is potential to significantly shorten this time based on better understanding and control of the rate-limiting processes and knowledge of the progress of the hybridization. In the hybridization work, a custom microarray flow cell was used to manipulate the chemical and thermal environment of the array and autonomously image the changes over time during hybridization. The second study area is selective release. Microarrays easily generate hybridization patterns and signatures, but there is still an unmet need for methodologies enabling rapid and selective analysis of these patterns and signatures. Detailed analysis of individual spots by subsequent sequencing could potentially yield significant information for rapidly mutating and emerging (or deliberately engineered) pathogens. In the selective release work, optical energy deposition with coherent light quickly provides the thermal energy to

  14. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    PubMed Central

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nano-silver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nano-silver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over four orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by pre-oxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and release inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through bacterial inhibition zone assay carried out on selected formulations of controlled release nano-silver. PMID:20968290

  15. Controlled release of tocopherols from polymer blend films

    NASA Astrophysics Data System (ADS)

    Obinata, Noe

    Controlled release packaging has great potential to increase storage stability of foods by releasing active compounds into foods continuously over time. However, a major limitation in development of this technology is the inability to control the release and provide rates useful for long term storage of foods. Better understanding of the factors affecting active compound release is needed to overcome this limitation. The objective of this research was to investigate the relationship between polymer composition, polymer processing method, polymer morphology, and release properties of active compounds, and to provide proof of principle that compound release is controlled by film morphology. A natural antioxidant, tocopherol was used as a model active compound because it is natural, effective, heat stable, and soluble in most packaging polymers. Polymer blend films were produced from combination of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), polypropylene (PP), or polystyrene (PS) with 3000 ppm mixed tocopherols using conventional blending method and innovative blending method, smart blending with a novel mixer using chaotic advection. Film morphologies were visualized with scanning electron microscopy (SEM). Release of tocopherols into 95% ethanol as a food simulant was measured by UV/Visible spectrophotometry or HPLC, and diffusivity of tocopherols in the polymers was estimated from this data. Polymer composition (blend proportions) and processing methods have major effects on film morphology. Four different types of morphologies, dispersed, co-continuous, fiber, and multilayer structures were developed by either conventional extrusion or smart blending. With smart blending of fixed polymer compositions, different morphologies were progressively developed with fixed polymer composition as the number of rod rotations increased, providing a way to separate effects of polymer composition and morphology. The different morphologies

  16. Plasma-mediated release of morphine from synthesized prodrugs.

    PubMed

    Thomas, Thommey P; Huang, Baohua; Desai, Ankur; Zong, Hong; Cheng, Xue-Min; Kotlyar, Alina; Leroueil, Pascale R; Dunham, Thomas; van der Spek, Abraham; Ward, Brent B; Baker, James R

    2010-11-01

    Two morphine prodrugs ('PDA' and 'PDB') were synthesized and the kinetics of esterase-mediated morphine release from these prodrugs were determined when incubated with plasma from different animal species. Morphine was rapidly released from PDA by all species plasma with the maximum reached within 5-10min; the released morphine was biologically active as determined by an in vitro cAMP assay. The morphine was released from PDB at a slower and species-dependent rate (mouse>rat>guinea pig>human). Morphine's release from PDB appeared to be mediated by carboxyl esterases as the release was inhibited by the carboxyl esterase inhibitor benzil. PDA nor PDB induce cytotoxicity in the neuronal cell lines SK-NSH and SH-SY5Y. The carboxyl and amino functional moieties present on the linker portions of PDA and PDB, respectively, may facilitate their conjugation to nanoparticles to tailor morphine pharmacokinetics and specific targeting. These studies suggest the potential clinical utility of these prodrugs for morphine release at desired rates by administration of their mixture at selected ratios.

  17. Preparation and characterization of metoprolol controlled-release solid dispersions.

    PubMed

    Varshosaz, Jaleh; Faghihian, Hossein; Rastgoo, Kobra

    2006-01-01

    In recent years, great attention has been paid to using solid dispersions to make sustained-release drugs. The objective of this study is to produce sustained-release systems of metoprolol tartrate using solid dispersion techniques and to evaluate their physicochemical characteristics. The solid dispersions were produced by melting and solvent methods, containing 7%, 15%, or 25% of the drug and different ratios of Eudragit RLPO and RSPO in ratios of 0:10, 3:7, 5:5, 7:3, and 10:0. Drug release profiles were determined by USP XXIII rotating paddle method in phosphate buffer solution (pH 6.8). XRD, DSC, IR, and microscopic observations were performed to evaluate the physical characteristics of solid dispersions. Results showed that the drug release from dispersions was at a slower rate than pure drug and physical mixtures. Moreover, the formulations containing greater ratios of Eudragit RSPO showed slower release rates and smaller DE8% but larger mean dissolution time than those containing greater ratios of Eudragit RLPO. Dispersions with particle size of less than 100 microm containing 7% of metoprolol and Eudragit RL:RS 5:5 (solvent method) and those with the ratio of 3:7 (melting method) had similar release pattern to Lopressor sustained-release tablets by zero-order and Higuchi kinetics, respectively.

  18. Carbon dioxide release from ocean thermal energy conversion (OTEC) cycles

    SciTech Connect

    Green, H.J. ); Guenther, P.R. )

    1990-09-01

    This paper presents the results of recent measurements of CO{sub 2} release from an open-cycle ocean thermal energy conversion (OTEC) experiment. Based on these data, the rate of short-term CO{sub 2} release from future open-cycle OTEC plants is projected to be 15 to 25 times smaller than that from fossil-fueled electric power plants. OTEC system that incorporate subsurface mixed discharge are expected to result in no long-term release. OTEC plants can significantly reduce CO{sub 2} emissions when substituted for fossil-fueled power generation. 12 refs., 4 figs., 3 tabs.

  19. Theory, Image Simulation, and Data Analysis of Chemical Release Experiments

    NASA Technical Reports Server (NTRS)

    Wescott, Eugene M.

    1994-01-01

    The final phase of Grant NAG6-1 involved analysis of physics of chemical releases in the upper atmosphere and analysis of data obtained on previous NASA sponsored chemical release rocket experiments. Several lines of investigation of past chemical release experiments and computer simulations have been proceeding in parallel. This report summarizes the work performed and the resulting publications. The following topics are addressed: analysis of the 1987 Greenland rocket experiments; calculation of emission rates for barium, strontium, and calcium; the CRIT 1 and 2 experiments (Collisional Ionization Cross Section experiments); image calibration using background stars; rapid ray motions in ionospheric plasma clouds; and the NOONCUSP rocket experiments.

  20. Theory, Image Simulation, and Data Analysis of Chemical Release Experiments

    SciTech Connect

    Wescott, E.M.

    1994-04-01

    The final phase of Grant NAG6-1 involved analysis of physics of chemical releases in the upper atmosphere and analysis of data obtained on previous NASA sponsored chemical release rocket experiments. Several lines of investigation of past chemical release experiments and computer simulations have been proceeding in parallel. This report summarizes the work performed and the resulting publications. The following topics are addressed: analysis of the 1987 Greenland rocket experiments; calculation of emission rates for barium, strontium, and calcium; the CRIT 1 and 2 experiments (Collisional Ionization Cross Section experiments); image calibration using background stars; rapid ray motions in ionospheric plasma clouds; and the NOONCUSP rocket experiments.

  1. Electronic equipment vulnerability to fire released carbon fibers

    NASA Technical Reports Server (NTRS)

    Pride, R. A.; Mchatton, A. D.; Musselman, K. A.

    1980-01-01

    The vulnerability of electronic equipment to damage by carbon fibers released from burning aircraft type structural composite materials was investigated. Tests were conducted on commercially available stereo power amplifiers which showed that the equipment was damaged by fire released carbon fibers but not by the composite resin residue, soot and products of combustion of the fuel associated with burning the carbon fiber composites. Results indicate that the failure rates of the equipment exposed to the fire released fiber were consistent with predictions based on tests using virgin fibers.

  2. Analysis of LNG import terminal release prevention systems

    SciTech Connect

    Baker, E G

    1982-04-01

    The release prevention systems of liquefied natural gas (LNG) import terminal were analyzed. A series of potential release scenarios were analyzed to determine the frequency of the release events, the probability these releases are not stopped or isolated by emergency shutdown systems, the estimated release quantities, and the critical components of the system. The two plant areas identified as being most significant with respect to safety are the unloading system and the storage system. Rupture of the main transfer line and gross failure of the storage tanks are the two release scenarios of primary safety interest. Reducing the rate of failure by improved design, better maintenance and testing, or adding redundancy of the critical system components for these plant areas and release scenarios will result in improved safety. Several design alternatives which have the potential to significantly reduce the probability of a large release of LNG occurring at an import terminal are identified. These design alternatives would reduce the probability of a large release of LNG by reducing the expected number of failures which could cause a release or by reducing the magnitude of releases that do occur. All of these alternatives are technically feasible and have been used or considered for use in at least one LNG facility. A more rigorous analysis of the absolute risk of LNG import terminal operation is necessary before the benefits of these design alternatives can be determined. In addition, an economic evaluation of these alternatives must be made so the costs and benefits can be compared. It is concludd that for remotely located facilities many of these alternatives are probably not justified; however, for facilities located in highly populated areas, these alternatives deserve serious consideration.

  3. Modeling of Fission Gas Release in UO2

    SciTech Connect

    MH Krohn

    2006-01-23

    A two-stage gas release model was examined to determine if it could provide a physically realistic and accurate model for fission gas release under Prometheus conditions. The single-stage Booth model [1], which is often used to calculate fission gas release, is considered to be oversimplified and not representative of the mechanisms that occur during fission gas release. Two-stage gas release models require saturation at the grain boundaries before gas is release, leading to a time delay in release of gases generated in the fuel. Two versions of a two-stage model developed by Forsberg and Massih [2] were implemented using Mathcad [3]. The original Forsbers and Massih model [2] and a modified version of the Forsberg and Massih model that is used in a commercially available fuel performance code (FRAPCON-3) [4] were examined. After an examination of these models, it is apparent that without further development and validation neither of these models should be used to calculate fission gas release under Prometheus-type conditions. There is too much uncertainty in the input parameters used in the models. In addition. the data used to tune the modified Forsberg and Massih model (FRAPCON-3) was collected under commercial reactor conditions, which will have higher fission rates relative to Prometheus conditions [4].

  4. Modulation of Venlafaxine Hydrochloride Release from Press Coated Matrix Tablet

    PubMed Central

    Gohel, M. C.; Soni, C. D.; Nagori, S. A.; Sarvaiya, K. G.

    2008-01-01

    The aim of present study was to prepare novel modified release press coated tablets of venlafaxine hydrochloride. Hydroxypropylmethylcellulose K4M and hydroxypropylmethylcellulose K100M were used as release modifier in core and coat, respectively. A 32 full factorial design was adopted in the optimization study. The drug to polymer ratio in core and coat were chosen as independent variables. The drug release in the first hour and drug release rate between 1 and 12 h were chosen as dependent variables. The tablets were characterized for dimension analysis, crushing strength, friability and in vitro drug release. A check point batch, containing 1:2.6 and 1:5.4 drug to polymer in core and coat respectively, was prepared. The tablets of check point batch were subjected to in vitro drug release in dissolution media with pH 5, 7.2 and distilled water. The kinetics of drug release was best explained by Korsmeyer and Peppas model (anomalous non-Fickian diffusion). The systematic formulation approach enabled us to develop modified release venlafaxine hydrochloride tablets. PMID:20046735

  5. Drug Release and Skin Permeation from Lipid Liquid Crystalline Phases

    NASA Astrophysics Data System (ADS)

    Costa-Balogh, F. O.; Sparr, E.; Sousa, J. J. S.; Pais, A. A. C. C.

    We have studied drug release and skin permeation from several different liquid crystalline lipid formulations that may be used to control the respective release rates. We have studied the release and permeation through human skin of a water-soluble and amphiphilic drug, propranolol hydrochloride, from several formulations prepared with monoolein and phytantriol as permeation enhancers and controlled release excipients. Diolein and cineol were added to selected formulations. We observed that viscosity decreases with drug load, wich is compatible with the occurrence of phase changes. Diolein stabilizes the bicontinuous cubic phases leading to an increase in viscosity and sustained release of the drug. The slowest release was found for the cubic phases with higher viscosity. Studies on skin permeation showed that these latter formulations also presented lower permeability than the less viscous monoolein lamellar phases. Formulations containing cineol originated higher permeability with higher enhancement ratios. Thus, the various formulations are adapted to different circumstances and delivery routes. While a slow release is usually desired for drug sustained delivery, the transdermal route may require a faster release. Lamellar phases, which are less viscous, are more adapted to transdermal applications. Thus, systems involving lamellar phases of monoolein and cineol are good candidates to be used as skin permeation enhancers for propranolol hydrochloride.

  6. Modulation of venlafaxine hydrochloride release from press coated matrix tablet.

    PubMed

    Gohel, M C; Soni, C D; Nagori, S A; Sarvaiya, K G

    2008-01-01

    The aim of present study was to prepare novel modified release press coated tablets of venlafaxine hydrochloride. Hydroxypropylmethylcellulose K4M and hydroxypropylmethylcellulose K100M were used as release modifier in core and coat, respectively. A 3(2) full factorial design was adopted in the optimization study. The drug to polymer ratio in core and coat were chosen as independent variables. The drug release in the first hour and drug release rate between 1 and 12 h were chosen as dependent variables. The tablets were characterized for dimension analysis, crushing strength, friability and in vitro drug release. A check point batch, containing 1:2.6 and 1:5.4 drug to polymer in core and coat respectively, was prepared. The tablets of check point batch were subjected to in vitro drug release in dissolution media with pH 5, 7.2 and distilled water. The kinetics of drug release was best explained by Korsmeyer and Peppas model (anomalous non-Fickian diffusion). The systematic formulation approach enabled us to develop modified release venlafaxine hydrochloride tablets.

  7. Toxics Release Inventory indicates big increases in releases

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-01-01

    Nearly 4 billion pounds of tracked toxic chemicals were released into the environment throughout the United States during 2010, according to an analysis by the U.S. Environmental Protection Agency (EPA) of the Toxics Release Inventory (TRI), the agency announced on 5 January. This is a 16% increase above 2009. The agency said the increase is mainly due to changes in the metal-mining sector, where differences in the chemical composition of ore being mined can result in significant changes in the amount of toxic chemicals. The chemical and primary metals industries were other sectors with increases in toxic releases in 2010, the latest year for which data collection is complete. EPA also noted that although releases in 2010 were higher than during the previous 2 years, they were lower than in 2007 and in prior years.

  8. Endoscopic Versus Open Cubital Tunnel Release

    PubMed Central

    Aldekhayel, Salah; Govshievich, Alexander; Lee, James; Tahiri, Youssef; Luc, Mario

    2016-01-01

    Background: Several surgical techniques exist for treatment of cubital tunnel syndrome. Endoscopic cubital tunnel release (ECTuR) has been recently reported as a promising minimally invasive technique. This study aims to compare outcomes and complications of open cubital tunnel release (OCTuR) and ECTuR in the treatment of idiopathic cubital tunnel syndrome. Methods: A systematic review of the literature (1980-2014) identified 118 citations. Studies including adults with idiopathic cubital tunnel treated exclusively by ECTuR or OCTuR were included. Outcomes of interest were postoperative grading, complications, number of reoperations, and the need for intraoperative conversion to another technique. Postoperative outcomes were combined into a uniform scale with 4 categories: “excellent,” “good,” “fair,” and “poor.” Results: Twenty studies met the inclusion criteria (17 observational and 3 comparative), representing 425 open and 556 endoscopic decompressions. In the open group, 79.8% experienced “good” or “excellent” results with 12% complication rate and 2.8% reoperation rate. In the endoscopic group, 81.8% experienced “good” or “excellent” results with 9% complication rate and 1.6% reoperation rate. Meta-analysis of 3 comparative studies demonstrated a significantly lower overall complication rate with ECTuR. Subgroup analysis of complications revealed a significantly higher incidence of scar tenderness and elbow pain with OCTuR. Conclusions: The current study demonstrates similar effectiveness between the endoscopic (ECTuR) and open (OCTuR) techniques for treatment of idiopathic cubital tunnel syndrome with similar outcomes, complication profiles, and reoperation rates. PMID:27418887

  9. Mast cell release of superoxide

    SciTech Connect

    Dileepan, K.N.; Simpson, K.M.; Stechschulte, D.J.

    1987-05-01

    The ability of rat serosal mast cells (MC) to release superoxide (O/sub 2//sup -/) upon activation by immunologic and nonimmunologic stimuli was investigated. Purified MC (90-95%) were either sensitized with monoclonal IgE reactive against dinitrophenyl bovine serum albumin (DNP-BSA) and challenged with DNP-BSA, or naive MC were treated with compound 48/80 or ionophore A23187. O/sub 2//sup -/ release was measured by O/sub 2//sup -/ dismutase (SOD)-sensitive reduction of cytochrome C and MC activation was assessed by the release of histamine or (/sup 14/C)5-hydroxytryptamine (5HT). The results reveal that activation of MC by 48/80 or immunologic challenge does not release O/sub 2//sup -/, although these stimuli induce substantial release of histamine and 5HT (40-70%). In contrast, A23187 released O/sub 2//sup -/ (3-6 nMols/10/sup 6/ MC) and histamine (40-80%). In mixed cell preparations containing MC and macrophages (M0), activation of MC with 48/80 resulted in inhibition of M0 O/sub 2//sup -/ release. The MC-mediated inhibition of O/sub 2//sup -/ production was not due to histamine or 5HT, but was due to MC-granule SOD. MC contain abundant quantities of SOD and, therefore, release O/sub 2//sup -/ only when its production exceeds the intracellular SOD threshold following activation with selective stimuli. In addition, the apparent differences in the mode and site of action of various stimuli on MC may contribute to the discriminative release of O/sub 2//sup -/.

  10. Controlled release liquid dosage formulation

    DOEpatents

    Benton, Ben F.; Gardner, David L.

    1989-01-01

    A liquid dual coated dosage formulation sustained release pharmaceutic having substantial shelf life prior to ingestion is disclosed. A dual coating is applied over controlled release cores to form dosage forms and the coatings comprise fats melting at less than approximately 101.degree. F. overcoated with cellulose acetate phthalate or zein. The dual coated dosage forms are dispersed in a sugar based acidic liquid carrier such as high fructose corn syrup and display a shelf life of up to approximately at least 45 days while still retaining their release profiles following ingestion. Cellulose acetate phthalate coated dosage form cores can in addition be dispersed in aqueous liquids of pH <5.

  11. Effect of soil moisture on the release of alachlor from alginate-based controlled-release formulations.

    PubMed

    Nasser, Ahmed; Mingelgrin, Uri; Gerstl, Zev

    2008-02-27

    The release of alachlor from controlled-release formulations (CRFs) based on alginate-montmorillonite matrices into aqueous polyethylene glycol (PEG) solutions of different concentrations and into a soil at different moisture contents was studied. In distilled water and in PEG-containing solutions displaying -0.1 MPa potential and up, the beads imbibe water and swell. The ensuing increase in weight is about 5%, and the increase in the bead's diameter is about 10%. At water potentials of -0.5 MPa and lower, loss of weight and shrinkage of the beads were observed. The changes in weight and diameter of the alginate-clay beads incubated in a Hamra loamy sand soil at 26.5% moisture content (w/w; -0.18 MPa) were similar to those observed in PEG solutions of >-0.5 MPa moisture potential. The weight and diameter losses observed in the drier soils (12.0 and 7.1% water content; -0.49 and -1.11 MPa) were similar to those in the more concentrated PEG solutions. A decrease in the rate of release of the active ingredient from the beads into soil was observed as the water potential decreased (drier soils). The release of the active ingredient from the investigated CRFs displayed a linear relationship to the square root of time, suggesting a diffusion-controlled-release rate. Data extracted from this relationship enabled the formulation of a mathematical model that correlates rate of release to water content.

  12. Environmental releases for calendar year 1993

    SciTech Connect

    Thomas, S.P.; Curn, B.L.

    1994-07-01

    This report presents data on radioactive and nonradioactive materials released into the environment during calendar year 1993 from facilities managed by Westinghouse Hanford Company. As part of this executive summary, comprehensive data summaries of air emissions and liquid effluents in 1993 are displayed in tables. These tables represent the following: radionuclide air emissions data; data on radioactive liquid effluents discharged to the soil; radionuclides discharged to the Columbia River; nonradioactive air emissions data; total volumes and flow rates of 200/600 area liquid effluents. Both summary and detailed presentations of these data are given. When appropriate, comparisons to data from previous years are made.

  13. Tyrosine - Effects on catecholamine release

    NASA Technical Reports Server (NTRS)

    Acworth, Ian N.; During, Matthew J.; Wurtman, Richard J.

    1988-01-01

    Tyrosine administration elevates striatal levels of dopamine metabolites in animals given treatments that accelerate nigrostriatal firing, but not in untreated rats. We examined the possibility that the amino acid might actually enhance dopamine release in untreated animals, but that the technique of measuring striatal dopamine metabolism was too insensitive to demonstrate such an effect. Dopamine release was assessed directly, using brain microdialysis of striatal extracellular fluid. Tyrosine administration (50-200 mg/kg IP) did indeed cause a dose related increase in extracellular fluid dopamine levels with minor elevations in levels of DOPAC and HVA, its major metabolites, which were not dose-related. The rise in dopamine was short-lived, suggesting that receptor-mediated feedback mechanisms responded to the increased dopamine release by diminishing neuronal firing or sensitivity to tyrosine. These observations indicate that measurement of changes in striatal DOPAC and HVA, if negative, need not rule out increases in nigrostriatal dopamine release.

  14. Birth control - slow release methods

    MedlinePlus

    Contraception - slow-release hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring ... implants while breastfeeding. Progestin implants work better than birth control pills to prevent pregnancy. Very few women who ...

  15. SELF-RELEASING GRAPPLING DEVICE

    DOEpatents

    Hoover, D.A. Sr.

    1963-11-01

    >A self-releasing grappling device that lifts by virtue of engagement between clamping jaws and the undercut lower side of a conical head of a lifting lug attached to the object to be lifted and employs a releasing sleeve on the lug to free the jaws from the lug is presented. When the jaws are to be released, they are dropped over the releasing sleeve, which is located well below lug head. When the jaws are lifted, they engage a conical surface on the sleeve and lift it up to the head of the lifting lug. In this position of the sleeve, the lower side of the lug head is covered by the sleeve and so cannot be engaged by the jaws, which move past before clearing the sleeve. (AEC)

  16. Influence of pore water velocity on the release of carbofuran and fenamiphos from commercial granulates embedded in a porous matrix

    NASA Astrophysics Data System (ADS)

    Paradelo, Marcos; Pérez-Rodríguez, Paula; Arias-Estévez, Manuel; López-Periago, J. Eugenio

    2012-11-01

    Pore water flow velocity can influence the processes involved in the contaminant transport between relative stagnant zones of porous media and their adjacent mobile zones. A particular case of special interest is the occurrence of high flow rates around the controlled release granules containing pesticides buried in soil. The release of the pesticides carbofuran and fenamiphos from commercial controlled release formulations (CRFs) was studied, comparing release tests in a finite volume of water with water flow release tests in saturated packed sand at different seepage velocities. For water release kinetics, the time taken for 50% of the pesticide to be released (T50) was 0.64 hours for carbofuran and 1.97 hours for fenamiphos. In general, the release rate was lower in the porous matrix than in the free water tests. The faster release rate for carbofuran was attributed to its higher water diffusivity. The seepage velocity has a strong influence on the pesticide release rate. The dominant release mechanism varies with the progress of release. The evolution of the mechanism is discussed on the basis of the successive steps that involve the moving boundary of the dissolution front of the pesticide inside the granule, the concentration gradient inside the granule and the flow boundary layer resistance to solute diffusion around the granule. The pore water velocity influences the overall release dynamics. Therefore, seepage velocity should be considered in pesticide release to evaluate the risk of pesticide leaching, especially in scenarios with fast infiltration.

  17. Microparticle dispensers for the controlled release of insect pheromones.

    PubMed

    Stipanovic, Arthur J; Hennessy, Patrick J; Webster, Francis X; Takahashi, Yae

    2004-04-21

    The potential utility of micrometer-sized particles as controlled-release devices for the volatilization of insect pheromones for mating disruption applications is evaluated in this study for two pheromone/model compound systems (codlemone/1-dodecanol and disparlure/1,2-epoxyoctadecane). To expedite the measurement of release rates from these particle devices, two techniques based on thermogravimetric analysis (TGA) have been exploited: isothermal TGA (I-TGA) at elevated temperatures (40-80 degrees C) with N(2) convection and volatilization temperature (VT) by dynamic TGA. A correlation between these two methods has been established. Samples that exhibit a higher VT provide a lower release rate from a particle substrate. Using these techniques, it has been demonstrated that chemical interactions between adsorbed liquids and particle surfaces may play a small role in defining release characteristics under conditions of low surface area, whereas parameters associated with total surface area and micropore structure appear to be much more significant in retarding evaporation for uncoated particles containing an adsorbed liquid. Additional regulation of release rates was achieved by coating the particle systems with water-soluble or water-dispersible polymers. By careful selection of particle porosity and coating composition, it is envisioned that the evaporation rate of pheromones can be tailored to specific insect control applications.

  18. Energy release in solar flares

    NASA Technical Reports Server (NTRS)

    Brown, John C.; Correia, Emilia; Farnik, Frantisek; Garcia, Howard; Henoux, Jean-Claude; La Rosa, Ted N.; Machado, Marcos E. (Compiler); Nakajima, Hiroshi; Priest, Eric R.

    1994-01-01

    Team 2 of the Ottawa Flares 22 Workshop dealt with observational and theoretical aspects of the characteristics and processes of energy release in flares. Main results summarized in this article stress the global character of the flaring phenomenon in active regions, the importance of discontinuities in magnetic connectivity, the role of field-aligned currents in free energy storage, and the fragmentation of energy release in time and space.

  19. Oxidative calcium release from catechol.

    PubMed

    Riley, Patrick A; Stratford, Michael R L

    2015-04-01

    Oxidation of 4-methylcatechol previously exposed to aqueous calcium chloride was shown by ion chromatography to be associated with release of calcium ions. The catechol was oxidised to the corresponding orthoquinone by the use of tyrosinase from Agaricus bisporus. The oxidative release of calcium from the catechol is ascribed to the diminution of the available hydroxyl functions able to act as chelating groups. Our results suggest that the redox status of melanin may regulate calcium binding and influence calcium levels in pigmented cells.

  20. Transdermal anaesthesia for percutaneous trigger finger release.

    PubMed

    Yiannakopoulos, Christos K; Ignatiadis, Ioannis A

    2006-01-01

    The purpose of this study was to evaluate the safety and efficiency of transdermal anaesthesia using eutectic mixture of lidocaine and prilocaine (EMLA) in patients undergoing percutaneous trigger finger release and to compare it with lidocaine infiltration. In this prospective, randomised study percutaneous release of the A1 annular pulley was performed to treat stenosing tenosynovitis (trigger finger syndrome) in 50 patients (50 fingers). The procedure was performed either under transdermal anaesthesia using EMLA applied transcutaneously 120 minutes prior to the operation (Group A, n = 25) or using local infiltration anaesthesia using lidocaine (Group B, n = 25). Pain experienced during administration of anaesthesia and during the operation was assessed using a 10-point Visual Analogue Pain Scale (VAPS), while all patients rated the effectiveness of anaesthesia with a 5-point scale. There were no significant differences between the two groups in the VAPS during the operation (1.33 +/- 0.52 versus 1.59 +/- 0.87) and the satisfaction scores (4.6 +/- 0.2 versus 4.4 +/- 0.3). The VAPS score during the administration of anaesthesia was statistically significantly less in the EMLA group (0 versus 5.96 +/- 2.41). All patients were satisfied with the final result of the operation. Percutaneous trigger finger release can be performed as an office procedure with the use of EMLA avoiding the use of injectable local infiltration anaesthesia.

  1. Control of bisphosphonate release using hydroxyapatite granules.

    PubMed

    Seshima, Hisashi; Yoshinari, Masao; Takemoto, Shinji; Hattori, Masayuki; Kawada, Eiji; Inoue, Takashi; Oda, Yutaka

    2006-08-01

    The efficacy of hydroxyapatite (HAp) as a carrier was investigated to establish a method of local administration of bisphosphonates (Bps), which has currently been administered systemically. HAp granules (300-500 microm in size) with different physicochemical features were prepared by altering the sintering temperature. To ascertain the physicochemical properties of the HAp granules, their crystallinity was assessed using X-ray diffraction, the surface morphology was examined under scanning electron microscopy, and the specific surface area and calcium dissolution were evaluated. Different Bps-HAp composites were subsequently prepared and the concentration of Bps released from these composites was measured. The influence of Bps-HAp composites on the rate of osteoclast survival was also evaluated. The results revealed that (1) HAp solubility depends on the sintering temperature; (2) The concentration of released Bps could be controlled by regulating the sintering temperature of HAp as a carrier; and (3) Bps released from Bps-HAp composites reduced the number of osteoclasts. These findings indicated that Bps-HAp composites could be locally administered as a drug delivery system to areas with bone resorption.

  2. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres.

  3. Evaporation rate of emulsion and oil-base emulsion pheromones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of pheromone evaporation rate is critical to distribute pheromone containers effectively in the forest, orchard and field. There are several factors influencing the pheromone evaporation rate that include wind speed, container size and porosity, release area, temperature, humidity, pherom...

  4. Formulation development of sustained-release hydrophilic matrix tablets of zileuton.

    PubMed

    Qiu, Y; Hui, H W; Cheskin, H

    1997-08-01

    The purpose of this paper was to develop a hydrophilic matrix system for extended oral delivery of zileuton, and study the effects of certain formulation, processing, and dissolution variables on in vitro drug release. Tablet formulations with 60-70% drug and varying release rates were prepared by wet granulation using low and medium viscosity grades of hydroxypropylmethocellulose. In vitro drug release was evaluated using USP apparatus 1. The in vitro drug release from all formulations followed zero-order kinetics and was independent of compression force. In general, the release rate decreased with increasing drug load and higher polymer concentration or viscosity. High-shear granulation also resulted in lower release rate. Accelerated release was observed with increased agitation as well as in the dissolution media with higher surfactant concentration and/or ionic strength. No stereoselective release from the matrix system was observed. The hydrophilic matrix system effectively controlled the in vitro release of zileuton. Matrix tablets with desired release rates can be prepared by adjusting various formulation and processing parameters. The matrix system also has the advantage of simple processing and relatively low cost.

  5. The release of monoterpenes during convective drying of wood chips

    SciTech Connect

    Johansson, A.; Rasmuson, A.

    1998-08-01

    The release of volatile organic components (VOC) during high temperature convective drying of wood chips was studied experimentally and theoretically. The drying medium was superheated steam with a pressure of two bar. Two different temperature levels of the drying medium, 160 and 180 C, and two different materials, Scots Pine and Norway Spruce, were investigated. It was found that the main components released consist of various types of monoterpenes, with {alpha}-pinene dominating in each of the two materials. The amount released is dependent on the drying temperature as well as the time of the drying process. In order to describe the release rate of monoterpenes during drying, two separate models, called the communicating and the non-communicating model respectively, were developed. The mechanisms included for the transport of monoterpenes are, in the communicating model, transport by diffusion and with the advective gas and liquid flow within the tracheids and, in the non-communicating model, diffusion within the resin canal system. The results obtained using the communicating model largely overpredict the experimental results. To avoid this rapid release, additional mass transfer resistance for the transport of monoterpenes between the two canal systems could be introduced. The non-communicating model was found to be useful in explaining the release rate when drying spruce. This model, however, cannot distinguish between the two temperature levels studied.

  6. Release behaviour of clozapine matrix pellets based on percolation theory.

    PubMed

    Aguilar-de-Leyva, Angela; Sharkawi, Tahmer; Bataille, Bernard; Baylac, Gilles; Caraballo, Isidoro

    2011-02-14

    The release behaviour of clozapine matrix pellets was studied in order to investigate if it is possible to explain it applying the concepts of percolation theory, previously used in the understanding of the release process of inert and hydrophilic matrix tablets. Thirteen batches of pellets with different proportions of clozapine/microcrystalline cellulose (MCC)/hydroxypropylmethyl cellulose (HPMC) and different clozapine particle size fractions were prepared by extrusion-spheronisation and the release profiles were studied. It has been observed that the distance to the excipient (HPMC) percolation threshold is important to control the release rate. Furthermore, the drug percolation threshold has a big influence in these systems. Batches very close to the drug percolation threshold, show a clear effect of the drug particle size in the release rate. However, this effect is much less evident when there is a bigger distance to the drug percolation threshold, so the release behaviour of clozapine matrix pellets is possible to be explained based on the percolation theory.

  7. Formulation of controlled release gellan gum macro beads of amoxicillin.

    PubMed

    Babu, R Jayachandra; Sathigari, Sateesh; Kumar, M Thilek; Pandit, J K

    2010-01-01

    Gellan gum has been reported to have wide pharmaceutical applications such as tablet binder, disintegrant, gelling agent and as a controlled release polymer. Multiparticulate delivery systems spread out more uniformly in the gastrointestinal tract and reduce the local irritation. The purpose of this study is to explore possible applicability of gellan macro beads as an oral controlled release system of a sparingly soluble drug, amoxicillin. Gellan gum beads were prepared by ionotropic gelation with calcium ions. The effect of drug loading, stirring time, polymer concentration, electrolyte (CaCl2) concentration, curing time etc. influencing the preparation of the gellan gum macro beads and the drug release from gellan gum beads were investigated in this study. Optimal preparation conditions allowed very high incorporation efficiency for amoxicillin (91%) The release kinetics of amoxicillin from gellan beads followed the diffusion model for an inert porous matrix in the order: 0.1 N HCl > phosphate buffer > distilled water. Change in curing time did not significantly affect the release rate constant, but drug concentration, polymer concentration and electrolyte concentration significantly affect the release rate of amoxicillin from the beads. The gellan macro beads may be suitable for gastro retentive controlled delivery of amoxicillin.

  8. Student Self-Assessment and Student Ratings of Teacher Rapport in Secondary Student Course Ratings

    ERIC Educational Resources Information Center

    Roe, John Wilford

    2010-01-01

    This study involved administering two rating forms (student self-rating on commitment and student rating of teacher rapport) to approximately 1,400 secondary students taught by 12 different teachers at two different high school Latter-day Saint (LDS) released time seminaries along the Wasatch Front in Utah. Seminaries and Institutes of Religion…

  9. Studies on renin release from isolated superfused glomeruli: effects of temperature, urea, ouabain and ethacrynic acid.

    PubMed Central

    Baumbach, L; Leyssac, P P; Skinner, S L

    1976-01-01

    1. The effects of different energy substrates, of low temperature, of urea, and of ouabain and ethacrynic acid were studied on the rate of renin release from viable juxtaglomerular cells during superfusion of isolated rat glomeruli. 2. Neither lactate nor glutamate altered renin release rate from that observed using glucose as the sole energy substrate. Succinate 10 mM elevated release transiently but did not influence the release caused by reductions in osmolality through lowering sucrose concentration. 3. Peak renin release was more prolonged and returned more slowly to control following reductions in osmolality in phosphate-Ringer than in bicarbonate-Ringer. 4. At 37 degrees C, the peak of renin released induced by hypo-osmolality was smaller and delayed, and returned earlier to control than at 30 degrees C. Reduction in temperature from 30 to 4 degrees C resulted in a 32-fold increase in basal release rate. At 4 degrees C a 20 m-osmole/kg reduction in tonicity caused an additional 2-5-fold increase in release rate. 6. Increasing superfusate osmolality with urea did not affect basal renin release but 100 mM urea suppressed the releasing effect of a 15 mM reduction in NaCl concentration. 7. Ouabain (10(-4) M) caused a small (33 +/- 9%, P less than 0-025) transient increase in renin release. Ethacrynic acid (10(-3) M) provoked a progressive increase in release reaching 100 +/- 15% above control within 50 min. In the presence of both inhibitors the release provoked by hyposmolality was prolonged. 8. It is concluded that renin release in vitro is a function of actively regulated cell volume and it is proposed that a similar mechanism could underline both barorecptor and macula densa controls of renin secretion in vivo. PMID:940062

  10. Toxic chemical considerations for tank farm releases. Revision 1

    SciTech Connect

    Van Keuren, J.C.

    1995-11-01

    This document provides a method of determining the toxicological consequences of accidental releases from Hanford Tank Farms. A determination was made of the most restrictive toxic chemicals that are expected to be present in the tanks. Concentrations were estimated based on the maximum sample data for each analyte in all the tanks in the composite. Composite evaluated were liquids and solids from single shell tanks, double shell tanks, flammable gas watch list tanks, as well as all solids, all liquids, head space gases, and 241-C-106 solids. A sum of fractions of the health effects was computed for each composite for unit releases based emergency response planning guidelines (ERPGs). Where ERPGs were not available for chemical compounds of interest, surrogate guidelines were established. The calculation method in this report can be applied to actual release scenarios by multiplying the sum of fractions by the release rate for continuous releases, or the release amount for puff releases. Risk guidelines are met if the product is less than for equal to one.

  11. Wetting mechanisms of gel-based controlled-release fertilizers.

    PubMed

    Shavit, U; Reiss, M; Shaviv, A

    2003-02-14

    The release mechanism of gel-based controlled release fertilizers (CRFs) involves water penetration into dry mixtures of fertilizers and gel forming polymers. Water penetration provides an upper limit to the whole release process. Where wetting prediction is often based on models that describe the flow of the liquid phase, vapor motion may become significant when a sharp wetting front exists. In this study we examine the role of vapor and fluid flows in the wetting process of CRFs consisting of urea or KNO(3) mixed with polyacrylamide (PAM). Vapor adsorption isotherms were obtained for typical fertilizer-PAM mixtures. Wetting and release experiments were conducted by dividing the CRFs into regions alternately filled with a pure fertilizer and mixtures of PAM and fertilizer. The experiments were designed in such a way that when the wetting front reaches a mixtures interface, its motion depends on the gradient imposed by the difference in osmotic potential (OP). The coupled equations of vapor and liquid flow in initially dry conditions were solved numerically to demonstrate the conceptual understanding gained by the experiments. The results show that wetting front motion is affected by transport and adsorption of vapor. It was also shown that the release rate is different when wetting is governed by vapor flow or by liquid flow. The release pattern from a multi-regions device was consistent with the wetting pattern, demonstrating the possibility to tailor the release according to periods of peak demand.

  12. Controlled-release NPK fertilizer encapsulated by polymeric membranes.

    PubMed

    Jarosiewicz, Anna; Tomaszewska, Maria

    2003-01-15

    The commercial granular fertilizer NPK6-20-30 was coated using polysulfone (PSF), polyacrylonitrile (PAN), and cellulose acetate (CA). The coatings were formed from the polymer solutions by the phase inversion technique. Measurements of the thickness and porosity of the prepared coatings and a microphotographic observation of the coatings were performed. The physical properties of the coatings influence the release rate of macronutrients which are present in the core of the coated fertilizer. In the case of PAN coating with 60.45% porosity, prepared from a 16% polymer solution, 100% of NH(4)(+) and P(2)O(5) was released after 4 h of test and 99.7% of K(+) after 5 h of test, whereas in the case of coating with 48.8% porosity, 31.8% of NH(4)(+), 16.7% of P(2)O(5), and 11.6% of K(+) was released after 5 h. In all experiments, different selectivities of the coatings in terms of the release of components were observed. The release of potassium through the coatings made of PSF and PAN was the slowest. The same tendency was observed for the release of nitrogen through a coating of CA. The release of fertilizer active components was the slowest in the case of PSF. The lowest porosity coating was prepared from the 18% PSF solution.

  13. Radiological effluents released from US continental tests, 1961 through 1992. Revision 1

    SciTech Connect

    Schoengold, C.R.; DeMarre, M.E.; Kirkwood, E.M.

    1996-08-01

    This report documents all continental tests from September 15, 1961, through September 23, 1992, from which radioactive effluents were released. The report includes both updated information previously published in the publicly available May, 1990 report, DOE/NV-317, ``Radiological Effluents Released from Announced US Continental Tests 1961 through 1988``, and effluent release information on formerly unannounced tests. General information provided for each test includes the date, time, location, type of test, sponsoring laboratory and/or agency or other sponsor, depth of burial, purpose, yield or yield range, extent of release (onsite only or offsite), and category of release (detonation-time versus post-test operations). Where a test with simultaneous detonations is listed, location, depth of burial and yield information are given for each detonation if applicable, as well as the specific source of the release. A summary of each release incident by type of release is included. For a detonation-time release, the effluent curies are expressed at R+12 hours. For a controlled releases from tunnel-tests, the effluent curies are expressed at both time of release and at R+12 hours. All other types are listed at the time of the release. In addition, a qualitative statement of the isotopes in the effluent is included for detonation-time and controlled releases and a quantitative listing is included for all other types. Offsite release information includes the cloud direction, the maximum activity detected in the air offsite, the maximum gamma exposure rate detected offsite, the maximum iodine level detected offsite, and the maximum distance radiation was detected offsite. A release summary incudes whatever other pertinent information is available for each release incident. This document includes effluent release information for 433 tests, some of which have simultaneous detonations. However, only 52 of these are designated as having offsite releases.

  14. Thiophenic Sulfur Compounds Released During Coal Pyrolysis.

    PubMed

    Xing, Mengwen; Kong, Jiao; Dong, Jie; Jiao, Haili; Li, Fan

    2013-06-01

    Thiophenic sulfur compounds are released during coal gasification, carbonization, and combustion. Previous studies indicate that thiophenic sulfur compounds degrade very slowly in the environment, and are more carcinogenic than polycyclic aromatic hydrocarbons and nitrogenous compounds. Therefore, it is very important to study the principle of thiophenic sulfur compounds during coal conversion, in order to control their emission and promote clean coal utilization. To realize this goal and understand the formation mechanism of thiophenic sulfur compounds, this study focused on the release behavior of thiophenic sulfur compounds during coal pyrolysis, which is an important phase for all coal thermal conversion processes. The pyrolyzer (CDS-5250) and gas chromatography-mass spectrometry (Focus GC-DSQII) were used to analyze thiophenic sulfur compounds in situ. Several coals with different coal ranks and sulfur contents were chosen as experimental samples, and thiophenic sulfur compounds of the gas produced during pyrolysis under different temperatures and heating rates were investigated. Levels of benzothiophene and dibenzothiophene were obtained during pyrolysis at temperatures ranging from 200°C to 1300°C, and heating rates ranging from 6°C/ms to 14°C/ms and 6°C/s to 14°C/s. Moreover, the relationship between the total amount of benzothiophene and dibenzothiophene released during coal pyrolysis and the organic sulfur content in coal was also discussed. This study is beneficial for understanding the formation and control of thiophenic sulfur compounds, since it provides a series of significant results that show the impact that operation conditions and organic sulfur content in coal have on the amount and species of thiophenic sulfur compounds produced during coal pyrolysis.

  15. Thiophenic Sulfur Compounds Released During Coal Pyrolysis

    PubMed Central

    Xing, Mengwen; Kong, Jiao; Dong, Jie; Jiao, Haili; Li, Fan

    2013-01-01

    Abstract Thiophenic sulfur compounds are released during coal gasification, carbonization, and combustion. Previous studies indicate that thiophenic sulfur compounds degrade very slowly in the environment, and are more carcinogenic than polycyclic aromatic hydrocarbons and nitrogenous compounds. Therefore, it is very important to study the principle of thiophenic sulfur compounds during coal conversion, in order to control their emission and promote clean coal utilization. To realize this goal and understand the formation mechanism of thiophenic sulfur compounds, this study focused on the release behavior of thiophenic sulfur compounds during coal pyrolysis, which is an important phase for all coal thermal conversion processes. The pyrolyzer (CDS-5250) and gas chromatography–mass spectrometry (Focus GC-DSQII) were used to analyze thiophenic sulfur compounds in situ. Several coals with different coal ranks and sulfur contents were chosen as experimental samples, and thiophenic sulfur compounds of the gas produced during pyrolysis under different temperatures and heating rates were investigated. Levels of benzothiophene and dibenzothiophene were obtained during pyrolysis at temperatures ranging from 200°C to 1300°C, and heating rates ranging from 6°C/ms to 14°C/ms and 6°C/s to 14°C/s. Moreover, the relationship between the total amount of benzothiophene and dibenzothiophene released during coal pyrolysis and the organic sulfur content in coal was also discussed. This study is beneficial for understanding the formation and control of thiophenic sulfur compounds, since it provides a series of significant results that show the impact that operation conditions and organic sulfur content in coal have on the amount and species of thiophenic sulfur compounds produced during coal pyrolysis. PMID:23781126

  16. Cellulose, chitosan, and keratin composite materials. Controlled drug release.

    PubMed

    Tran, Chieu D; Mututuvari, Tamutsiwa M

    2015-02-03

    A method was developed in which cellulose (CEL) and/or chitosan (CS) were added to keratin (KER) to enable [CEL/CS+KER] composites to have better mechanical strength and wider utilization. Butylmethylimmidazolium chloride ([BMIm(+)Cl(-)]), an ionic liquid, was used as the sole solvent, and because the [BMIm(+)Cl(-)] used was recovered, the method is green and recyclable. Fourier transform infrared spectroscopy results confirm that KER, CS, and CEL remain chemically intact in the composites. Tensile strength results expectedly show that adding CEL or CS into KER substantially increases the mechanical strength of the composites. We found that CEL, CS, and KER can encapsulate drugs such as ciprofloxacin (CPX) and then release the drug either as a single or as two- or three-component composites. Interestingly, release rates of CPX by CEL and CS either as a single or as [CEL+CS] composite are faster and independent of concentration of CS and CEL. Conversely, the release rate by KER is much slower, and when incorporated into CEL, CS, or CEL+CS, it substantially slows the rate as well. Furthermore, the reducing rate was found to correlate with the concentration of KER in the composites. KER, a protein, is known to have secondary structure, whereas CEL and CS exist only in random form. This makes KER structurally denser than CEL and CS; hence, KER releases the drug slower than CEL and CS. The results clearly indicate that drug release can be controlled and adjusted at any rate by judiciously selecting the concentration of KER in the composites. Furthermore, the fact that the [CEL+CS+KER] composite has combined properties of its components, namely, superior mechanical strength (CEL), hemostasis and bactericide (CS), and controlled drug release (KER), indicates that this novel composite can be used in ways which hitherto were not possible, e.g., as a high-performance bandage to treat chronic and ulcerous wounds.

  17. Magnetic molecularly imprinted polymer for aspirin recognition and controlled release

    NASA Astrophysics Data System (ADS)

    Kan, Xianwen; Geng, Zhirong; Zhao, Yao; Wang, Zhilin; Zhu, Jun-Jie

    2009-04-01

    Core-shell structural magnetic molecularly imprinted polymers (magnetic MIPs) with combined properties of molecular recognition and controlled release were prepared and characterized. Magnetic MIPs were synthesized by the co-polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) around aspirin (ASP) at the surface of double-bond-functionalized Fe3O4 nanoparticles in chloroform. The obtained spherical magnetic MIPs with diameters of about 500 nm had obvious superparamagnetism and could be separated quickly by an external magnetic field. Binding experiments were carried out to evaluate the properties of magnetic MIPs and magnetic non-molecularly imprinted polymers (magnetic NIPs). The results demonstrated that the magnetic MIPs had high adsorption capacity and selectivity to ASP. Moreover, release profiles and release rate of ASP from the ASP-loaded magnetic MIPs indicated that the magnetic MIPs also had potential applications in drug controlled release.

  18. A review of parenteral sustained-release naltrexone systems

    SciTech Connect

    Olsen, J.L.; Kincl, F.A.

    1981-01-01

    The ideal naltrexone sustained-release delivery system should be easy to inject or implant, not cause adverse tissue reaction, release the drug at a relatively constant rate for at least 30 days, and biodegrade within a short time afterwards. Mechanisms which can be used for sustaining drug release include reducing solubility and surface area, coating, encapsulation and microencapsulation, complexation, binding and hydrophilic gelation. Drug release from such systems is controlled by diffusion through a barrier/film, diffusion from a monolithic device, erosion of the surface, hydrolysis, ion exchange, biodegradation, or a combination of these. Injectable systems would seem to be ultimately preferred because of the ease of administration and handling, while the implantable devices may find first use in man since they are easily removable, should that be necessary. Maintaining particulate-free products and sterilization methods are two problems with all parenteral dosage forms. Production must be particularly well controlled and validated.

  19. Hexamethylenetetramine carboxyborane: synthesis, structural characterization and CO releasing properties.

    PubMed

    Ayudhya, T I; Raymond, C C; Dingra, N N

    2017-01-17

    Carbon monoxide, although widely known as a toxic gas, has received great attention in the past few decades due to its promising role as a medical gas. Several classes of carbon monoxide releasing molecules (CORMs) have been synthesised with many of them having pharmacological activities under physiological conditions. Herein, we report the synthesis and structural characterization of the first example of amine carboxyborane that releases CO under physiological conditions without the aid of inducers. A representative compound hexamethylenetetramine carboxyborane (HMTA-CB) described here has a half-life of 2.7 days and gradually releases CO with the rate constant of 3.0 × 10(-6) s(-1). Its ability to promote cell growth shows the beneficial effect of slow CO release to supplement CO in small amounts over time.

  20. Thermally controlled protein release from gelatin dextran hydrogels

    NASA Astrophysics Data System (ADS)

    Aso, Y.; Yoshioka, S.; Nakai, Y.; Kojima, S.

    1999-06-01

    Biodegradable hydrogels in which drug release was controlled by sol-gel transition were prepared. Gelatin was used as a component because it exhibits sol-gel transition in response to temperature changes. Glycidyl methacrylated (GMA) dextran was crosslinked by low dose γ-irradiation in the presence of gelatin and the model drugs, β-galactosidase ( β-GA), bovine serum albumin (BSA) or 5-fluorouracil (5-FU). The enzyme activity of β-GA remained greater than 95% after irradiation. Temperature-responsive release of β-GA and BSA resulted from the sol-gel transition of gelatin. Sol-gel transition was confirmed by the temperature dependence of the spin-spin relaxation time of the gel polymer protons. The protein release rate was affected by both the degree of GMA substitution and the gelatin concentration. Desired release rate could be achieved by adjusting these factors. The release rate of 5-FU was not affected by the sol-gel transition of gelatin.

  1. Programmable release of multiple protein drugs from aptamer-functionalized hydrogels via nucleic acid hybridization.

    PubMed

    Battig, Mark R; Soontornworajit, Boonchoy; Wang, Yong

    2012-08-01

    Polymeric delivery systems have been extensively studied to achieve localized and controlled release of protein drugs. However, it is still challenging to control the release of multiple protein drugs in distinct stages according to the progress of disease or treatment. This study successfully demonstrates that multiple protein drugs can be released from aptamer-functionalized hydrogels with adjustable release rates at predetermined time points using complementary sequences (CSs) as biomolecular triggers. Because both aptamer-protein interactions and aptamer-CS hybridization are sequence-specific, aptamer-functionalized hydrogels constitute a promising polymeric delivery system for the programmable release of multiple protein drugs to treat complex human diseases.

  2. In Job-Placement Rates, Fuzzy Data

    ERIC Educational Resources Information Center

    Sandoval, Timothy

    2012-01-01

    As colleges and lawmakers seek better data about the employment success of graduates, a lack of standardized tracking makes much of the information unreliable. Many colleges release placement rates based on scant information: More than a third of colleges' reported rates in 2010 were based on responses from half of their graduates or fewer,…

  3. Development of metoprolol tartrate-loaded sustained-release pellets: effect of talc on the mechanism of drug release.

    PubMed

    Wang, Yuli; Yang, Meiyan; Shen, Ruifang; Shao, Shuai; Chen, Lu; Gong, Wei; Shan, Li; Gao, Chunsheng

    2016-07-28

    Talc is one of the most commonly used antiadherents in the coating film. However, the mechanism of influence of talc on drug release has yet to be fully understood. In this study, metoprolol tartrate (MT)-loaded Eudragit NE 30 D-coated sustained-release (SR) pellets were prepared using talc as an antiadherent in the layering and coating processes. Talc significantly reduced the stickiness of the layered or coated substrates, thus enhancing the process smoothness. Moreover, the incorporation of talc into the coating film significantly affected drug release. The water vapor permeability and drug permeability of free films increased as the concentration of talc increased. Importantly, talc had a dynamic effect on the drug release. The drug release rate of the pellets in the initial stage (within 2 h) increased with increasing talc concentrations, which exceeded the critical pigment volume concentration resulted in leaks formation in the coated film. However, subsequent swelling of the membrane and expansion of the copolymer network eliminated the influence of talc and the drug release was then controlled by the polymeric membrane. These results suggest that talc contributed to the reduction of the sticking of layered or coated substrates, and facilitated the manufacturing process and drug release properties.

  4. Controlled Release of Multiple Therapeutics from Silicone Hydrogel Contact Lenses

    PubMed Central

    White, Charles J.; DiPasquale, Stephen A.; Byrne, Mark E.

    2016-01-01

    Purpose The majority of contact lens wearers experience a significant level of ocular discomfort associated with lens wear, often within hours of wear, related to dry lenses, inflammation, protein adhesion to the lens surface, etc. Application of controlled drug release techniques has focused on the incorporation and/or release of a single comfort molecule from a lens including high molecular weight comfort agents or pharmaceutical agents. Previous studies have sought to mitigate the occurrence of only single propagators of discomfort. Clinical studies with eye drop solutions have shown that a mixture of diverse comfort agents selected to address multiple propagators of discomfort provide the greatest and longest lasting sensations of comfort for the patient. In this paper, multiple propagators of discomfort are addressed through the simultaneous release of four molecules from a novel contact lens to ensure high level of lens wear comfort. Methods Silicone hydrogel contact lenses were engineered via molecular imprinting strategies to simultaneously release up to four template molecules including hydropropyl methylcellulose (HPMC), trehalose, ibuprofen, and prednisolone. Results By adjusting the ratio of functional monomer to comfort molecule, a high level of control was demonstrated over the release rate. HPMC, trehalose, ibuprofen, and prednisolone were released at therapeutically relevant concentrations with varying rates from a single lens. Conclusions The results indicate use as daily disposable lenses for single day release or extended-wear lenses with multiple day release. Imprinted lenses are expected to lead to higher efficacy for patients compared to topical eye drops by improving compliance and mitigating concentration peaks and valleys associated with multiple drops. PMID:26945177

  5. Fluoride release from new light-cured orthodontic bonding agents.

    PubMed

    McNeill, C J; Wiltshire, W A; Dawes, C; Lavelle, C L

    2001-10-01

    The purpose of this study was to compare the rates of fluoride release with time from 1 nonfluoridated and 3 fluoride-containing orthodontic bonding materials in distilled water and artificial saliva. Materials tested were Assure (Reliance Orthodontic Products, Itasca, Ill), Fuji Ortho LC (GC, Tokyo, Japan), Python (TP Orthodontics, LaPorte, Ind), and Transbond XT (3M Dental Products, Monrovia, Calif). Ten specimens of each material type were stored in distilled water, and 10 of each type were stored in artificial saliva at 37 degrees C. Fluoride release was measured with an ion-specific electrode. Readings were taken periodically for a total time period of 6 months. At day 1, Assure released the most fluoride into distilled water (66.2 microg/cm(2)) and into artificial saliva (65.8 microg/cm(2)), followed by Fuji Ortho LC (25.9 microg/cm(2); 18.8 microg/cm(2)), Python (6.3 microg/cm(2); 4.2 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The fluoride release rates were highest during the first days of testing, declining to lower but more stable levels. At the end of 6 months, Fuji Ortho LC released the most fluoride (3.8 microg/cm(2); 3.5 microg/cm(2)) followed by Assure (3.1 microg/cm(2); 2.8 microg/cm(2)), Python (2.6 microg/cm(2); 1.7 microg/cm(2)), and Transbond (0.1 microg/cm(2); 0.1 microg/cm(2)). The type of storage medium did not dramatically affect fluoride release. The second part of the study, undertaken after a year of sample storage, tested the 20 samples of Assure for a further 2-week period, after exposure to running and still distilled water. Although fluoride release rates declined with time, they were still higher than the 1.5 microg/cm(2) level that is referenced as inhibiting decalcification of enamel in a clinical environment. Release rates were similar in running and still water at all time points. Throughout the 6-month period, all 3 fluoride-containing materials had rates of fluoride release that could theoretically

  6. Controlled Release from Recombinant Polymers

    PubMed Central

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  7. Controlled release from recombinant polymers.

    PubMed

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-09-28

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed.

  8. Hydrocarbon release investigations in Missouri

    SciTech Connect

    Fels, J.B.

    1996-09-01

    Hydrocarbon releases are among the most common environmental problems in Missouri, as well as across the country. Old, unprotected underground storage tanks and buried piping from the tanks to pumps are notorious sources of petroleum contamination at LUST (leaking underground storage tank) sites. Missouri has an estimated 5000 LUST sites across the state with the majority being simple spills into clay-rich soils or into a shallow perched water system. However, in the southern half of the state, where residual soils and karst bedrock are not conducive to trapping such releases, significant groundwater supplies are at risk. This article discusses the process used to identify the source of contamination.

  9. Counterion release and electrostatic adsorption

    PubMed

    Sens; Joanny

    2000-05-22

    The effective charge of a rigid polyelectrolyte (PE) approaching an oppositely charged surface is studied. The cases of a weak (annealed) and strongly charged PE with condensed counterions (such as DNA) are discussed. In the most interesting case of the adsorption onto a substrate of low dielectric constant (such as a lipid membrane or a mica sheet) the condensed counterions are not always released as the PE approaches the substrate, because of the major importance of the image-charge effect. For the adsorption onto a surface with freely moving charges, the image-charge effect becomes less important and full release is often expected.

  10. Numerical methods to determine calcium release flux from calcium transients in muscle cells.

    PubMed Central

    Timmer, J; Müller, T; Melzer, W

    1998-01-01

    Several methods are currently in use to estimate the rate of depolarization-induced calcium release in muscle cells from measured calcium transients. One approach first characterizes calcium removal of the cell. This is done by determining parameters of a reaction scheme from a fit to the decay of elevated calcium after the depolarizing stimulus. In a second step, the release rate during depolarization is estimated based on the fitted model. Using simulated calcium transients with known underlying release rates, we tested the fidelity of this analysis in determining the time course of calcium release under different conditions. The analysis reproduced in a satisfactory way the characteristics of the input release rate, even when the assumption that release had ended before the start of the fitting interval was severely violated. Equally good reconstructions of the release rate time course could be obtained when the model used for the analysis differed in structure from the one used for simulating the data. We tested the application of a new strategy (multiple shooting) for fitting parameters in nonlinear differential equation systems. This procedure rendered the analysis less sensitive to ill-chosen initial guesses of the parameters and to noise. A locally adaptive kernel estimator for calculating numerical derivatives allowed good reconstructions of the original release rate time course from noisy calcium transients when other methods failed. PMID:9545033

  11. Prediction of modified release pharmacokinetics and pharmacodynamics from in vitro, immediate release, and intravenous data.

    PubMed

    Lukacova, Viera; Woltosz, Walter S; Bolger, Michael B

    2009-06-01

    The aim of this study was to demonstrate the value of mechanistic simulations in gaining insight into the behaviors of modified release (MR) formulations in vivo and to use the properly calibrated models for prediction of pharmacokinetics (PK) and pharmacodynamics (PD). GastroPlus (Simulations Plus, Inc.) was used to fit mechanistic models for adinazolam and metoprolol that describe the absorption, PK, and PD after intravenous (i.v.) and immediate release (IR) oral (p.o.) administration. The fitted model for adinazolam was then used to predict the PD profile for a MR formulation and to design a new formulation with desired onset and duration of action. The fitted metoprolol model was used to gain insight and to explain the in vivo behaviors of MR formulations. For each drug, a single absorption/PK model was fitted that provided simulated plasma concentration-time profiles closely matching observed in vivo profiles across several different i.v. and p.o doses. Sedation score profiles of adinazolam were fitted with an indirect PD model. For metoprolol, the fitted absorption/PK model for IR p.o. doses was used to select in vitro dissolution conditions that best matched the in vivo release of MR doses. This model also explained differences in exposure after administration of MR formulations with different release rates. Mechanistic absorption/PK models allow for detailed descriptions of all processes affecting the two drugs' bioavailability, including release/dissolution, absorption, and intestinal and hepatic first pass extraction. The insights gained can be used to design formulations that more effectively overcome identified problems.

  12. The effect of polymer blends on release profiles of diclofenac sodium from matrices.

    PubMed

    Samani, Soliman Mohammadi; Montaseri, Hashem; Kazemi, Abdolghani

    2003-05-01

    The purpose of this study was to evaluate the effect of polymer blends on the in vitro release profile of diclofenac sodium. Several controlled release matrices of diclofenac sodium with different proportions of hydroxypropyl methylcellulose (HPMC; viscosity grade 60 and 500 mPa.s), carbopol 940 and lactose as a water soluble filler were prepared. The results showed that when HPMC (viscosity grade 60 mPa.s) alone was used as matrix former, diclofenac sodium was released fast but the release rate became slower with HPMC (viscosity grade 500 mPa.s) at higher polymer/drug ratios (more than 0.8:1). However in lower polymer/drug ratios (lower than 0.7:1) the release rate still was fast. The results showed that carbopol can extend the release time appreciably but the release profiles had considerable fluctuations, and drug release in first hours was slow but increased appreciably with time at the end of profiles. When an appropriate blend of HPMC (viscosity grade 60 or 500 mPa.s) and carbopol 940 was used, the drug release became more uniform and its kinetic approached to zero order and release fluctuations were diminished. The results with these polymer blends showed that it is possible to reduce the total amounts of polymer in each formulation. According to kinetic analysis data, drug release from these matrix tablets did not follow Fick's law of diffusion and the results were in agreement with the earlier reports.

  13. Stabilization of spontaneous neurotransmitter release at ribbon synapses by ribbon-specific subtypes of complexin.

    PubMed

    Vaithianathan, Thirumalini; Zanazzi, George; Henry, Diane; Akmentin, Wendy; Matthews, Gary

    2013-05-08

    Ribbon synapses of tonically releasing sensory neurons must provide a large pool of releasable vesicles for sustained release, while minimizing spontaneous release in the absence of stimulation. Complexins are presynaptic proteins that may accomplish this dual task at conventional synapses by interacting with the molecular machinery of synaptic vesicle fusion at the active zone to retard spontaneous vesicle exocytosis yet facilitate release evoked by depolarization. However, ribbon synapses of photoreceptor cells and bipolar neurons in the retina express distinct complexin subtypes, perhaps reflecting the special requirements of these synapses for tonic release. To investigate the role of ribbon-specific complexins in transmitter release, we combined presynaptic voltage clamp, fluorescence imaging, electron microscopy, and behavioral assays of photoreceptive function in zebrafish. Acute interference with complexin function using a peptide derived from the SNARE-binding domain increased spontaneous synaptic vesicle fusion at ribbon synapses of retinal bipolar neurons without affecting release triggered by depolarization. Knockdown of complexin by injection of an antisense morpholino into zebrafish embryos prevented photoreceptor-driven migration of pigment in skin melanophores and caused the pigment distribution to remain in the dark-adapted state even when embryos were exposed to light. This suggests that loss of complexin function elevated spontaneous release in illuminated photoreceptors sufficiently to mimic the higher release rate normally associated with darkness, thus interfering with visual signaling. We conclude that visual system-specific complexins are required for proper illumination-dependent modulation of the rate of neurotransmitter release at visual system ribbon synapses.

  14. Stabilization of spontaneous neurotransmitter release at ribbon synapses by ribbon-specific subtypes of Complexin

    PubMed Central

    Vaithianathan, Thirumalini; Zanazzi, George; Henry, Diane; Akmentin, Wendy; Matthews, Gary

    2013-01-01

    Ribbon synapses of tonically releasing sensory neurons must provide a large pool of releasable vesicles for sustained release, while minimizing spontaneous release in the absence of stimulation. Complexins are presynaptic proteins that may accomplish this dual task at conventional synapses, by interacting with the molecular machinery of synaptic vesicle fusion at the active zone to retard spontaneous vesicle exocytosis yet facilitate release evoked by depolarization. However, ribbon synapses of photoreceptor cells and bipolar neurons in the retina express distinct Complexin subtypes, perhaps reflecting the special requirements of these synapses for tonic release. To investigate the role of ribbon-specific Complexins in transmitter release, we combined presynaptic voltage-clamp, fluorescence imaging, electron microscopy, and behavioral assays of photoreceptive function in zebrafish. Acute interference with Complexin function using a peptide derived from the SNARE-binding domain increased spontaneous synaptic vesicle fusion at ribbon synapses of retinal bipolar neurons without affecting release triggered by depolarization. Knockdown of Complexin by injection of an antisense morpholino into zebrafish embryos prevented photoreceptor-driven migration of pigment in skin melanophores and caused the pigment distribution to remain in the dark-adapted state even when embryos were exposed to light. This suggests that loss of Complexin function elevated spontaneous release in illuminated photoreceptors sufficiently to mimic the higher release rate normally associated with darkness, thus interfering with visual signaling. We conclude that visual system-specific Complexins are required for proper illumination-dependent modulation of the rate of neurotransmitter release at visual system ribbon synapses. PMID:23658160

  15. Urediniospore Release and Escape from Rust-Infected Soybean Fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phakopsora pachyrhizi, soybean rust, has infected soybeans in the continental United States from 2004-2006. This study monitored release, dispersal, and germination rates of soybean rust spores produced from epidemics at various stages of development using rotorods, passive traps, and water agar pl...

  16. 40 CFR 264.193 - Containment and detection of releases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., the type of corrosion or erosion protection used, the rate of corrosion or erosion observed during the... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Containment and detection of releases. 264.193 Section 264.193 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)...

  17. ALKALINITY, PH, AND COPPER CORROSION BY-PRODUCT RELEASE

    EPA Science Inventory

    Contrary to expectations, higher bicarbonate concentrations exacerbate copper corrosion rates and by-product release. In fact, as illustrated by monitoring experiences of large utilities and by laboratory data, the concentration of copper corrosion by-products in drinking water i...

  18. Spatial release from informational masking

    NASA Astrophysics Data System (ADS)

    Rakerd, Brad; Aaronson, Neil L.

    2001-05-01

    A new method for investigating spatial release from informational masking was developed and employed in two experiments. The new method is computer controlled and efficient. It employs the versatile coordinate response measure speech stimulus set [Bolia et al., J. Acoust. Soc. Am. 107, 1065 (2000)]. The experiments were conducted in an anechoic room, with a primary loudspeaker in front of the listener and a secondary loudspeaker at 60 deg to the right. Target messages were presented from the primary speaker only. For a standard, distractor messages, simultaneous with the target, were also presented from the primary speaker only. Spatial release was measured by presenting the distractors from both primary and secondary speakers with a temporal offset. Experiment 1 fixed the offset (secondary leading, +4 ms) and varied the number of distractors (1 to 3) and the target-to-distractor ratio (-12 to +4 dB). Masking release, sometimes as large as 10 dB, was found for all combinations of these variables. Experiment 2 varied the offset over a wide range of values. Substantial release from masking was found for both positive and negative offsets, but only in the range in which speech echoes are suppressed (<50 ms). [Work supported by NIDCD grant DC 00181.

  19. Very low shock release pyromechanisms

    NASA Astrophysics Data System (ADS)

    Soulier, Grégory; Gaechter, J. Pierre

    2003-09-01

    Pyromechanisms have long been used in space for launchers and satellites applications, particularly for release or separation purposes, such as bolt cutters, release nuts, pyrovalves, etc. They offer a great variety of uses, a high potential between the power supplied and the weight on board with, at the same time, a high reliability. However, they also feature a drawback due to the high dynamics generated by their functioning. Pyroshocks levels may damage adjacent sensible equipments (eg electronic boxes, reaction wheels,...) and require to design damping systems or to remove those equipments from the shock source. In a mechanism using standard pyrodevices, shock generation comes from three sources: 1. Pyrotechnic reaction. 2. Energy from internal parts in motion. 3. The release of structural constraints. Devices developed by E. LACROIX have the objectives to avoid the two last ones by: Using heat and gas generated by pyrotechnic effects. Reducing speed of parts in motion. Reducing release speed of mechanical constraints. In this paper, LACROIX presents two products named "PYROSOFT" and "VIROSOFT " designed by LACROIX and supported by CNES Toulouse (French Space Agency). R&T contracts.

  20. 2014 Pee Dee germplasm releases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PD 05035, PD 05041, PD 05064, PD 05069, PD 05070, PD 05071, PD 06001, and PD 06078 are noncommercial breeding lines of cotton jointly released by the Agricultural Research Service, United States Department of Agriculture, Clemson University Experiment Station, and Cotton Incorporated in 2014. These ...

  1. Dynamical response of nanostructures and Joule heat release.

    PubMed

    Gurevich, V L; Kozub, V I; Muradov, M I

    2011-10-12

    We consider Joule heat release in a quantum wire joining two classical reservoirs under the action of a nonstationary periodic electric field. The rate of heat generation and its spatial distribution is discussed. The heat is spread over the lengths of electron mean free paths in the reservoirs. We find that the total rates of heat generation in both reservoirs that are joined by the nanostructure are the same.

  2. 7 CFR 550.29 - Press releases.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Press releases. 550.29 Section 550.29 Agriculture... Program Management § 550.29 Press releases. Press releases or other forms of public notification will be... opportunity to review, in advance, all written press releases and any other written information to be...

  3. 28 CFR 2.83 - Release planning.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Release planning. 2.83 Section 2.83... Release planning. (a) All grants of parole shall be conditioned on the development of a suitable release... parole date for purposes of release planning for up to 120 days without a hearing. If efforts...

  4. Index to NASA News Releases 1995

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This issue of the index to NASA News Releases contains a listing of news releases distributed by the Office of Public Affairs, NASA Headquarters, during 1995. The index is arranged in six sections: Subject index, Personal name index, News release number index, Accession number index, Speeches, and News releases.

  5. Aroma release and retronasal perception during and after consumption of flavored whey protein gels with different textures. 1. in vivo release analysis.

    PubMed

    Mestres, Montserrat; Moran, Noelia; Jordan, Alfons; Buettner, Andrea

    2005-01-26

    The influence of gel texture on retronasal aroma release during mastication was followed by means of real-time proton-transfer reaction mass spectrometry and compared to sensory perception of overall aroma intensity. A clear correlation was found between individual-specific consumption patterns and the respective physicochemical release patterns in vivo. A modified data analysis approach was used to monitor the aroma changes during the mastication process. It was found that the temporal resolution of the release profile played an important role in adequate description of the release processes. On the basis of this observation, a hypothesis is presented for the observed differences in intensity rating.

  6. Modelling and simulations of controlled release fertilizer

    NASA Astrophysics Data System (ADS)

    Irfan, Sayed Ameenuddin; Razali, Radzuan; Shaari, Ku Zilati Ku; Mansor, Nurlidia

    2016-11-01

    The recent advancement in controlled release fertilizer has provided an alternative solution to the conventional urea, controlled release fertilizer has a good plant nutrient uptake they are environment friendly. To have an optimum plant intake of nutrients from controlled release fertilizer it is very essential to understand the release characteristics. A mathematical model is developed to predict the release characteristics from polymer coated granule. Numerical simulations are performed by varying the parameters radius of granule, soil water content and soil porosity to study their effect on fertilizer release. Understanding these parameters helps in the better design and improve the efficiency of controlled release fertilizer.

  7. Kepler Data Release 3 Notes

    NASA Technical Reports Server (NTRS)

    Cleve, Jeffrey E.

    2010-01-01

    This describes the collection of data and the processing done on it so when researchers around the world get the Kepler data sets (which are a set of pixels from the telescope of a particular target (star, galaxy or whatever) over a 3 month period) they can adjust their algorithms fro things that were done (like subtracting all of one particular wavelength for example). This is used to calibrate their own algorithms so that they know what it is they are starting with. It is posted so that whoever is accessing the publicly available data (not all of it is made public) can understand it .. (most of the Kepler data is under restriction for 1 - 4 years and is not available, but the handbook is for everyone (public and restricted) The Data Analysis Working Group have released long and short cadence materials, including FFls and Dropped Targets for the Public. The Kepler Science Office considers Data Release 3 to provide "browse quality" data. These notes have been prepared to give Kepler users of the Multimission Archive at STScl (MAST) a summary of how the data were collected and prepared, and how well the data processing pipeline is functioning on flight data. They will be updated for each release of data to the public archive and placed on MAST along with other Kepler documentation, at http:// archive.stsci.edu/kepler/documents.html .Data release 3 is meant to give users the opportunity to examine the data for possibly interesting science and to involve the users in improving the pipeline for future data releases. To perform the latter service, users are encouraged to notice and document artifacts, either in the raw or processed data, and report them to the Science Office.

  8. Mechanistic analysis of triamcinolone acetonide release from PLGA microspheres as a function of varying in vitro release conditions.

    PubMed

    Doty, Amy C; Zhang, Ying; Weinstein, David G; Wang, Yan; Choi, Stephanie; Qu, Wen; Mittal, Sachin; Schwendeman, Steven P

    2017-04-01

    In vitro tests for controlled release PLGA microspheres in their current state often do not accurately predict in vivo performance of these products during formulation development. Here, we introduce a new mechanistic and multi-phase approach to more clearly understand in vitro-in vivo relationships, and describe the first "in vitro phase" with the model drug, triamcinolone acetonide (Tr-A). Two microsphere formulations encapsulating Tr-A were prepared from PLGAs of different molecular weights and end-capping (18kDa acid-capped and 54kDa ester-capped). In vitro release kinetics and the evidence for controlling mechanisms (i.e., erosion, diffusion, and water-mediated processes) were studied in four release media: PBST pH 7.4 (standard condition), PBST pH 6.5, PBS+1.0% triethyl citrate (TC), and HBST pH 7.4. The release mechanism in PBST was primarily polymer erosion-controlled as indicated by the similarity of release and mass loss kinetics. Release from the low MW PLGA was accelerated at low pH due to increased rate of hydrolysis and in the presence of the plasticizer TC due to slightly increased hydrolysis and much higher diffusion in the polymer matrix. TC also increased release from the high MW PLGA due to increased hydrolysis, erosion, and diffusion. This work demonstrates how in vitro conditions can be manipulated to change not only rates of drug release from PLGA microspheres but also the mechanism(s) by which release occurs. Follow-on studies in the next phases of this approach will utilize these results to compare the mechanistic data of the Tr-A/PLGA microsphere formulations developed here after recovery of microspheres in vivo. This new approach based on measuring mechanistic indicators of release in vitro and in vivo has the potential to design better, more predictive in vitro release tests for these formulations and potentially lead to mechanism-based in vitro-in vivo correlations.

  9. Fluorescence-based retention assays reveals sustained release of vascular endothelial growth factor from bone grafts.

    PubMed

    Kang, Wonmo; Yun, Ye-Rang; Lee, Dong-Sung; Kim, Tae-Hyun; Kim, Joong-Hyun; Kim, Hae-Won; Jang, Jun-Hyeog

    2016-01-01

    The sustained release of growth factors following their implantation in vivo is essential for successful outcomes in bone tissue engineering. In this study, we evaluated the release kinetics and delivery efficacies of vascular endothelial growth factor (VEGF), a potent angiogenic growth factor, incorporated into calcium phosphate bone grafts (BGs). We evaluated the release profile of VEGF from BGs using a novel fluorescence-based retention assay, which revealed that VEGF loaded on BGs can be released in a sustained manner without an initial burst (near zero-order cumulative release) with a controlled release rate of 13.6% per week for up to 7 weeks. In contrast, an ELISA-based release assay showed VEGF to have an early burst-release profile for the first week. However, the biological activity of VEGF released from the BGs was preserved over the 7-week release period, which is consistent with the sustained-release profile observed in the fluorescence-based retention assay. Furthermore, the in vivo bone-forming action of the VEGF-loaded BGs was well demonstrated in a rat subcutaneous model. Taken together, the sustained release of VEGF loaded onto BGs was effective in stimulating proliferation, angiogenesis and osteogenesis, suggesting the ultimate value of VEGF-engineered BGs for bone tissue engineering.

  10. Predicting release and transport of pesticides from a granular formulation during unsaturated diffusion in porous media

    NASA Astrophysics Data System (ADS)

    Paradelo, Marcos; Soto-Gómez, Diego; Pérez-Rodríguez, Paula; Pose-Juan, Eva; López-Periago, J. Eugenio

    2014-03-01

    The release and transport of active ingredients (AIs) from controlled-release formulations (CRFs) have potential to reduce groundwater pesticide pollution. These formulations have a major effect on the release rate and subsequent transport to groundwater. Therefore the influence of CRFs should be included in modeling non-point source pollution by pesticides. We propose a simplified approach that uses a phase transition equation coupled to the diffusion equation that describes the release rate of AIs from commercial CRFs in porous media; the parameters are as follows: a release coefficient, the solubility of the AI, and diffusion transport with decay. The model gives acceptable predictions of the pesticides release from commercial CRFs in diffusion cells filled with quartz sand. This approach can be used to study the dynamics of the CRF-porous media interaction. It also could be implemented in fate of agricultural chemical models to include the effect of CRFs.

  11. Evaluation of the Thermosensitive Release Properties of Microspheres Containing an Agrochemical Compound.

    PubMed

    Terada, Takatoshi; Ohtsubo, Toshiro; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2017-01-01

    The purpose of this study was to develop a deeper understanding of the key physicochemical parameters involved in the release profiles of microsphere-encapsulated agrochemicals at different temperatures. Microspheres consisting of different polyurethanes (PUs) were prepared using our previously reported solventless microencapsulation technique. Notably, these microspheres exhibited considerable differences in their thermodynamic characteristics, including their glass transition temperature (Tg), extrapolated onset temperature (To) and extrapolated end temperature (Te). At test temperatures below the To of the PU, only 5-10% of the agrochemical was rapidly released from the microspheres within 1 d, and none was released thereafter. However, at test temperatures above the To of the PU, the rate of agrochemical release gradually increased with increasing temperatures, and the rate of release from the microspheres was dependent on the composition of the PU. Taken together, these results show that the release profiles of the microspheres were dependent on their thermodynamic characteristics and changes in their PU composition.

  12. Release of allyl isothiocyanate from mustard seed meal powder.

    PubMed

    Dai, Ruyan; Lim, Loong-Tak

    2014-01-01

    Allyl isothiocyanate (AITC) is a wide-spectrum antimicrobial compound found in mustard seeds, produced when their tissues are disrupted. The formation of AITC in mustard seed is mediated by the myrosinase enzyme which catalyzes the release of volatile AITC from a glucosinolate-sinigrin. Since water is a substrate in the reaction, humidity from the air can be used to activate the release of AITC from mustard seed. In this study, defatted and partially defatted mustard seed meals were ground into powders with particle size ranging from 5 to 300 μm. The mustard seed meal powder (MSMP) samples were enclosed within hermetically sealed glass jars wherein the headspace air was adjusted to 85% or 100% relative humidity at 5, 20, or 35 °C. Data from gas chromatography analysis showed that AITC release rate and amount increased with increasing relative humidity and temperature. Moreover, the release rate can be manipulated by particle size and lipid content of the MSMP samples. The amount of AITC released ranged from 2 to 17 mg/g MSMP within 24 h under the experimental conditions tested. In view of the antimicrobial properties of AITC, the mustard meal powder may be used as a natural antimicrobial material for extending the shelf life of food products.

  13. Use of polysulfone in controlled-release NPK fertilizer formulations.

    PubMed

    Tomaszewska, Maria; Jarosiewicz, Anna

    2002-07-31

    Encapsulation of fertilizers in polymeric coatings is a method used to reduce fertilizer losses and to minimize environmental pollution. Polysulfone was used for a coating preparation for soluble NPK granular fertilizer in controlled-release fertilizer formulations. The coatings were formed by the phase inversion technique (wet method). The influence of the polymer concentration in the film-forming solution on the physical properties of the coatings was examined. The coating structure controls the diffusion of the elements from the interior of the fertilizer granule. It was experimentally confirmed that the use of polysulfone as a coating for a soluble fertilizer decreases the release rate of components. Moreover, the release rate of nutrients from coated granules decreases with the decrease of the coating porosity. In the case of coating with 38.5% porosity, prepared from 13.5% polymer solution after 5 h of test, 100% of NH(4)(+) was released, whereas only 19.0% of NH(4)(+) was released after 5 h for the coating with 11% porosity. In addition, coating of fertilizers leads to improvement of handling properties, and the crushing strength of all coated fertilizers was an average 40% higher than that for uncoated NPK fertilizer.

  14. Hazardous animal waste carcasses transformation into slow release fertilizers.

    PubMed

    Sharrock, Patrick; Fiallo, Marina; Nzihou, Ange; Chkir, Mouna

    2009-08-15

    Because of the need to address disposal of materials infected with pathogens new regulations have come into effect for the transport and disposal of dead farm animals or carcasses. For precautionary reasons, disposal to landfill, composting, biogas generation or fertilizer use are banned recycling paths because of incomplete knowledge about contamination transmission paths. Thermal treatment is recognized as a safe elimination process. Animal wastes have a high calorific value (above 16 MJ/kg). However, combustion of the organics leaves mineral residues (near 30%). The ashes contain mostly calcium and phosphate with some sodium, potassium and magnesium. We have examined the transformation of the ashes into a slow release fertilizer. We used a mixture of acids to partly dissolve the combustion residues and form slurry. In a second step, base was added to neutralize and solidify the reaction mixture. The final product was a whitish polycrystalline solid. Leaching tests were made to evaluate the nutrient release rate in laboratory columns. Water leachates were analyzed for up to ten pore-bed volumes and showed, as expected, large differences in release rates. Nitrate release was slowed and phosphate did not level even after ten pore-bed volumes. This demonstrates that insoluble precipitates (gypsum) contribute to control soluble ion release.

  15. Nitric oxide release from polydimethylsiloxane-based polyurethanes.

    PubMed

    Nguyen, Evelyne B; Zilla, Peter; Bezuidenhout, Deon

    2014-12-30

    Localized nitric oxide (NO) release from polymeric materials holds much promise for the prevention of coagulation often associated with implantable and extracorporeal blood-contacting devices. Films of polyurethane (PU) containing incorporated polyethyleneimine were thus exposed to NO gas to form diazeniumdiolates (NONOates) in situ. Donor incorporation and NO gas exposure did not affect the mechanical properties of the films. The NO release capacity increased with increasing polydimethylsiloxane (PDMS) content in the soft segment of the PU: total capacity could be more than doubled (P<0.05) from 0.093 ± 0.028 to 0.225 ± 0.004 mmol/g when the PDMS content was increased from 0 to 100%. Release kinetics were best approximated using a modified Korsemeyer-Peppas power law (R2=0.95-0.99). Despite the resultant rapid initial decrease in NO release rates, values above that observed for quiescent endothelial cells (0.83 pmol·cm(-2)·s(-1)) were maintained for extended periods of 5-10 days, while rates above that of a stimulated endothelium (2.7-6.8 pmol·cm(-2)·s(-1)) were achieved for the first 24 hours. This method of NONOate formation may be advantageous, as potential premature NO release by exposure of diazeniumdiolated donors during incorporation, processing and storage, can be avoided by in situ diazoniumdiolation closer to the time of implantation.

  16. Magnesium Modulates Actin Binding and ADP Release in Myosin Motors*

    PubMed Central

    Swenson, Anja M.; Trivedi, Darshan V.; Rauscher, Anna A.; Wang, Yuan; Takagi, Yasuharu; Palmer, Bradley M.; Málnási-Csizmadia, András; Debold, Edward P.; Yengo, Christopher M.

    2014-01-01

    We examined the magnesium dependence of five class II myosins, including fast skeletal muscle myosin, smooth muscle myosin, β-cardiac myosin (CMIIB), Dictyostelium myosin II (DdMII), and nonmuscle myosin IIA, as well as myosin V. We found that the myosins examined are inhibited in a Mg2+-dependent manner (0.3–9.0 mm free Mg2+) in both ATPase and motility assays, under conditions in which the ionic strength was held constant. We found that the ADP release rate constant is reduced by Mg2+ in myosin V, smooth muscle myosin, nonmuscle myosin IIA, CMIIB, and DdMII, although the ADP affinity is fairly insensitive to Mg2+ in fast skeletal muscle myosin, CMIIB, and DdMII. Single tryptophan probes in the switch I (Trp-239) and switch II (Trp-501) region of DdMII demonstrate these conserved regions of the active site are sensitive to Mg2+ coordination. Cardiac muscle fiber mechanic studies demonstrate cross-bridge attachment time is increased at higher Mg2+ concentrations, demonstrating that the ADP release rate constant is slowed by Mg2+ in the context of an activated muscle fiber. Direct measurements of phosphate release in myosin V demonstrate that Mg2+ reduces actin affinity in the M·ADP·Pi state, although it does not change the rate of phosphate release. Therefore, the Mg2+ inhibition of the actin-activated ATPase activity observed in class II myosins is likely the result of Mg2+-dependent alterations in actin binding. Overall, our results suggest that Mg2+ reduces the ADP release rate constant and rate of attachment to actin in both high and low duty ratio myosins. PMID:25006251

  17. Controlled Release Formulations of Auxinic Herbicides

    NASA Astrophysics Data System (ADS)

    Kowalski, Witold J.; Siłowiecki, Andrzej.; Romanowska, Iwona; Glazek, Mariola; Bajor, Justyna; Cieciwa, Katarzyna; Rychter, Piotr

    2013-04-01

    ingredient in the HBA oligomers was chemically bound to the oligomer matrix and a controlled release followed in concert with the hydrolysis of ester bonds in the oligomer systems. Due to the high volatility and high water solubility of the DMA salts, significant amounts of active ingredients were predisposed to be dispersed in the environment. On the other hand, the HBA oligomers exhibit low volatility and low solubility in water, so they tend to exhibit lover migrating rates from the target site. The obtained plots suggested that in the case of the HBA oligomers the effectiveness were delayed in time when compared with the DMA salts. The integral effectiveness of the studied HBA oligomers was practically equivalent to the conventional DMA salts, but the release of the HBA herbicides was delayed in time vs. DMA salts. The mixtures of oligo (R,S)-3-hydroxybutyric acid containing chemically bonded 2,4-D, Dicamba and MCPA (HBA) were proposed as carriers of active ingredients that could be released to control the sensitive weeds. The synthesized HBA oligomers could be particularly useful in a number of practical applications, because they release the herbicide to plants at a controlled rate and in amounts required over a specified period of time, their degradation products are identical to metabolites formed in plant cells, the physicochemical and operational parameters of the carrier oligomers might be optimized by fine-tuning of synthesis conditions. The decreased vapor pressure and increased lipophilicity of the studied materials could reduce the risk exposure of the operational personnel, as well as, a decrease the environmental pollution. Acknowledgments The authors would like to thank the Polish Ministry of Science and Higher Education for supporting this work through the grant No. NN 310 303039. References [1] S. Dubey, V. Jhelum, P.K. Patanjali, Controlled release agrochemical formulations: A review, J. Scientific &Industrial Research (India) 70 (2011) 105-112. [2] W. J

  18. Stabilization and release of enzymes from silk films.

    PubMed

    Lu, Qiang; Wang, Xiaoqin; Hu, Xiao; Cebe, Peggy; Omenetto, Fiorenzo; Kaplan, David L

    2010-04-08

    A significant challenge remains to protect protein drugs from inactivation during production, storage, and use. In the present study, the stabilization and release of horseradish peroxidase (HRP) in silk films was investigated. Water-insoluble silk films were prepared under mild aqueous conditions, maintaining the activity of the entrapped enzyme. Depending on film processing and post-processing conditions, HRP retained more than 90% of the initial activity at 4 degrees C, room temperature and 37 degrees C over two months. The stability of protein drugs in silk films is attributed to intermolecular interactions between the silk and the enzymes, based on Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The unique structural feature of silk molecules, periodic hydrophobic-hydrophilic domains, enabled strong interactions with proteins. The entrapped protein was present in two states, untrapped active and trapped inactive forms. The ratio between the two forms varied according to processing conditions. Proteolytic degradation and dissolution of the silk films resulted in the release of the bound enzyme which was otherwise not released by diffusion; enzyme recovered full activity upon release. There was a linear relationship between silk degradation/dissolution and the release of entrapped enzyme. Modifying the secondary structure of the silk matrix and the interactions with the non-crystalline domains resulted in control of the film degradation or dissolution rate, and therefore the release rate of the entrapped enzyme. Based on the above results, silk materials are an intriguing carrier for proteins in terms of both retention of activity and controllable release kinetics from the films.

  19. Investigating the feasibility of temperature-controlled accelerated drug release testing for an intravaginal ring.

    PubMed

    Externbrink, Anna; Clark, Meredith R; Friend, David R; Klein, Sandra

    2013-11-01

    The objective of the present study was to investigate if temperature can be utilized to accelerate drug release from Nuvaring®, a reservoir type intravaginal ring based on polyethylene vinyl acetate copolymer that releases a constant dose of contraceptive steroids over a duration of 3 weeks. The reciprocating holder apparatus (USP 7) was utilized to determine real-time and accelerated etonogestrel release from ring segments. It was demonstrated that drug release increased with increasing temperature which can be attributed to enhanced drug diffusion. An Arrhenius relationship of the zero-order release constants was established, indicating that temperature is a valid parameter to accelerate drug release from this dosage form and that the release mechanism is maintained under these accelerated test conditions. Accelerated release tests are particularly useful for routine quality control to assist during batch release of extended release formulations that typically release the active over several weeks, months or even years, since they can increase the product shelf life. The accelerated method should therefore be able to discriminate between formulations with different release characteristics that can result from normal manufacturing variance. In the case of Nuvaring®, it is well known that the process parameters during the extrusion process strongly influence the polymeric structure. These changes in the polymeric structure can affect the permeability which, in turn, is reflected in the release properties. Results from this study indicate that changes in the polymeric structure can lead to a different temperature dependence of the release rate, and as a consequence, the accelerated method can become less sensitive to detect changes in the release properties. When the accelerated method is utilized during batch release, it is therefore important to take this possible restriction into account and to evaluate the accelerated method with samples from non

  20. Selective nucleotide-release from dense-core granules in insulin-secreting cells.

    PubMed

    Obermüller, Stefanie; Lindqvist, Anders; Karanauskaite, Jovita; Galvanovskis, Juris; Rorsman, Patrik; Barg, Sebastian

    2005-09-15

    Secretory granules of insulin-secreting cells are used to store and release peptide hormones as well as low-molecular-weight compounds such as nucleotides. Here we have compared the rate of exocytosis with the time courses of nucleotide and peptide release by a combination of capacitance measurements, electrophysiological detection of ATP release and single-granule imaging. We demonstrate that the release of nucleotides and peptides is delayed by approximately 0.1 and approximately 2 seconds with respect to membrane fusion, respectively. We further show that in up to 70% of the cases exocytosis does not result in significant release of the peptide cargo, likely because of a mechanism that leads to premature closure of the fusion pore. Release of nucleotides and protons occurred regardless of whether peptides were secreted or not. These observations suggest that insulin-secreting cells are able to use the same secretory vesicles to release small molecules either alone or together with the peptide hormone.

  1. Nickel release from stainless steels.

    PubMed

    Haudrechy, P; Mantout, B; Frappaz, A; Rousseau, D; Chabeau, G; Faure, M; Claudy, A

    1997-09-01

    In 1994, a study of nickel release and allergic contact dermatitis from nickel-plated metals and stainless steels was published in this journal. It was shown that low-sulfur stainless steel grades like AISI 304, 316L or 430 (S < or = 0.007%) release less than 0.03 microgram/cm2/week of nickel in acid artificial sweat and elicit no reactions in patients already sensitized to nickel. In contrast, nickel-plated samples release around 100 micrograms/cm2/week of Ni and high-sulfur stainless steel (AISI 303-S approximately 0.3%) releases about 1.5 micrograms/cm2/week in this acid artificial sweat. Applied on patients sensitized to nickel, these metals elicit positive reactions in 96% and 14%, respectively, of the patients. The main conclusion was that low-sulfur stainless steels like AISI 304, 316L or 430, even when containing Ni, should not elicit nickel contact dermatitis, while metals having a mean corrosion resistance like a high-sulfur stainless steel (AISI 303) or nickel-plated steel should be avoided. The determining characteristic was in fact the corrosion resistance in chloride media, which, for stainless steels, is connected, among other factors, to the sulfur content. Thus, a question remained concerning the grades with an intermediate sulfur content, around 0.03%, which were not studied. They are the object of the study presented in this paper. 3 tests were performed: leaching experiments, dimethylglyoxime and HNO3 spot tests, and clinical patch tests; however, only stainless steels were tested: a low-sulfur AISI 304 and AISI 303 as references and 3 grades with a sulfur content around 0.03%: AISI 304L, AISI 304L added with Ca, AISI 304L+Cu. Leaching experiments showed that the 4 non-resulfurised grades released less than 0.5 microgram/cm2/week in acid sweat while the reulfurized AISI 303 released around or more than 0.5 microgram/cm2/week. This is explained by the poorer corrosion resistance of the resulfurized grade. Yet all these grades had the same

  2. The Reshock and Release Waves in PTFE

    NASA Astrophysics Data System (ADS)

    Karakhanov, S. M.; Bordzilovsky, S. A.

    1999-06-01

    To study the deformation and destruction of PTFE polymer the specimens were loaded by the complex wave structure: shock, reshock and release wave. The transmitted stress-time profiles were recorded with the manganin gages. The Lagrange analysis of stress histories gave the stress-volume paths during reshock loading and unloading of PTFE in the stress range of 10 to 35 GPa. The data revealed the viscoelastic behavior typical for polymers. For a single shock loading the relaxation zone with the duration of about 0.3 μs was noticeable behind the first stress jump. The reshock-release stress pulse that started from the state behind the first shock attenuated with the rate greater than in hydrodynamic approximation. The correlation was noticed between the stress-time and electrical resistivity-time profiles in the relaxation zone. The reloading-unloading stress hysteresis gave the possibility to measure the critical shear stress (τ) in a shocked state. The data showed the decrease in τ at higher stresses. The authors suggested that the most probable mechanism of destruction of PTFE in the studied region of pressures and temperatures is thermodestruction of a polymer chain by the thermal fluctuations under load.

  3. Evaluation of Phosphorylated Psyllium Seed Polysaccharide as a Release Retardant

    PubMed Central

    Rao, Monica R. P.; Warrier, Deepa U.; Rao, Shivani H.

    2015-01-01

    The aim of the present study was to modify psyllium seed polysaccharide and evaluate the modified polysaccharide as release retardant in tablets employing ciprofloxacin hydrochloride as model drug. Studies on polysaccharide from psyllium husk has been reported but no work has been reported on characterization and modification of the polysaccharide present in the psyllium (Plantago ovata) seed and the use of the modified polysaccharide as a release retardant in tablets. In this study, the seed gum was modified using sodium trimetaphosphate as crosslinking agent. Sustained release matrix tablets of ciprofloxacin hydrochloride were prepared by wet granulation using various drug-polymer ratios. The polymers investigated were psyllium polysaccharide, phosphorylated psyllium polysaccharide and widely used release retardant hydroxypropyl methylcellulose K100M. The tablets were evaluated for hardness, friability, drug content, swelling profile and in vitro dissolution studies. The matrix tablets containing 1:3 proportion of drug-phosphorylated psyllium polysaccharide was found to have higher hardness as compared to tablets containing 1:1 and 1:2 proportions. The results of swelling behavior in water showed that the tablets containing 1:3 drug:phosphorylated psyllium polysaccharide ratio had swelling comparable to that of tablets containing 1:3 drug:hydroxypropyl methylcellulose ratio. The in vitro dissolution studies shows that the dissolution rate was retarded from 98.41 to 37.6% in 6 h with increase in concentration of phosphorylated psyllium polysaccharide from 100 to 300 mg. Formulations containing psyllium polysaccharide showed complete drug release in 8 h whereas those formulated with phosphorylated psyllium polysaccharide exhibited extended drug release over the 12 h period. Drug release kinetic studies revealed that drug release followed Korsmeyer-Peppas model. PMID:26798177

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

    NASA Astrophysics Data System (ADS)

    Fang, Jonathan

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

  5. Interrelationship of islet metabolism, adenosine triphosphate content and insulin release

    PubMed Central

    Ashcroft, Stephen J. H.; Weerasinghe, L. Chatra C.; Randle, Philip J.

    1973-01-01

    The oxidation of some exogenous substrates and their effects on ATP content and insulin release in mouse pancreatic islets were measured. The ATP concentration of islets incubated without exogenous substrate shows a gradual decrease, which can be prevented by glucose or mannose (20mm) or leucine (2.5mm); d-glyceraldehyde (5mm) is as effective as glucose (5mm); fructose or N-acetylglucosamine (20mm), pyruvate (10mm) and dl-3-hydroxybutyrate (2mm) are less effective; galactose (20mm), acetate (10mm), octanoate (2mm) and succinate (10mm) have no ATP-maintaining ability. Islets oxidize glucose, mannose, glyceraldehyde, leucine and, less readily, N-acetylglucosamine and glucosamine; galactose, however, is poorly metabolized. Mannoheptulose inhibits the oxidation of glucose but not of glyceraldehyde. Insulin release, measured over a 2h incubation, is stimulated by glucose, mannose, leucine, glyceraldehyde or glucosamine but not by fructose or N-acetylglucosamine. The latter, however, potentiates the effects of glucose or glyceraldehyde (5mm) or leucine (2.5mm) on release; the potentiating effects are inhibited by mannoheptulose, which also blocks glucose-, but not glyceraldehyde- or leucine-stimulated release. In the presence of glucose (20mm), metabolic inhibitors depress insulin release and islet ATP content in parallel. However, rates of insulin release and ATP content measured after incubation with various combinations of exogenous substrates do not appear to be correlated. Sulphonylureas stimulate insulin release but decrease islet ATP concentrations. These results provide further evidence of a close association between the metabolic activity of exogenous substrates and their ability to initiate insulin release. Glucoreceptor models are formulated in the light of these observations and discussed. PMID:4199014

  6. Modeling and measurement of vesicle pools at the cone ribbon synapse: changes in release probability are solely responsible for voltage-dependent changes in release

    PubMed Central

    Thoreson, Wallace B.; Van Hook, Matthew J.; Parmelee, Caitlyn; Curto, Carina

    2015-01-01

    Post-synaptic responses are a product of quantal amplitude (Q), size of the releasable vesicle pool (N), and release probability (P). Voltage-dependent changes in presynaptic Ca2+ entry alter post-synaptic responses primarily by changing P but have also been shown to influence N. With simultaneous whole cell recordings from cone photoreceptors and horizontal cells in tiger salamander retinal slices, we measured N and P at cone ribbon synapses by using a train of depolarizing pulses to stimulate release and deplete the pool. We developed an analytical model that calculates the total pool size contributing to release under different stimulus conditions by taking into account the prior history of release and empirically-determined properties of replenishment. The model provided a formula that calculates vesicle pool size from measurements of the initial post-synaptic response and limiting rate of release evoked by a train of pulses, the fraction of release sites available for replenishment, and the time constant for replenishment. Results of the model showed that weak and strong depolarizing stimuli evoked release with differing probabilities but the same size vesicle pool. Enhancing intraterminal Ca2+ spread by lowering Ca2+ buffering or applying BayK8644 did not increase PSCs evoked with strong test steps showing there is a fixed upper limit to pool size. Together, these results suggest that light-evoked changes in cone membrane potential alter synaptic release solely by changing release probability. PMID:26541100

  7. Controlled release of cyclosporine A self-nanoemulsifying systems from osmotic pump tablets: near zero-order release and pharmacokinetics in dogs.

    PubMed

    Zhang, Xi; Yi, Yueneng; Qi, Jianping; Lu, Yi; Tian, Zhiqiang; Xie, Yunchang; Yuan, Hailong; Wu, Wei

    2013-08-16

    It is very important to enhance the absorption simultaneously while designing controlled release delivery systems for poorly water-soluble and poorly permeable drugs (BCS IV). In this study, controlled release of cyclosporine (CyA) was achieved by the osmotic release strategy taking advantage of the absorption-enhancing capacity of self-nanoemulsifying drug delivery systems (SNEDDSs). The liquid SNEDDS consisting of Labrafil M 1944CS, Transcutol P and Cremophor EL was absorbed by the osmotic tablet core excipients (sucrose, lactose monohydrate, polyethylene oxide, and partly pregelatinized starch) and then transformed into osmotic tablets. Near zero-order release could be achieved for CyA-loaded nanoemulsions reconstituted from the SNEDDS. In general, the influencing factor study indicated that the release rate increased with increase of inner osmotic pressure, ratio of osmotic agent to suspending agent, content of pore-forming agent, and size of release orifice, whereas the thickness of the membrane impeded the release of CyA nanoemulsion. Pharmacokinetic study showed steady blood CyA profiles with prolonged Tmax and MRT, and significantly reduced Cmax for self-nanoemulsifying osmotic pump tablet (SNEOPT) in comparison with highly fluctuating profiles of the core tablet and Sandimmune Neoral(®). However, similar oral bioavailability was observed for either controlled release or non-controlled release formulations. It was concluded that simultaneous controlling on CyA release and absorption-enhancing had been achieved by a combination of osmotic tablet and SNEDDS.

  8. Modeling and measurement of vesicle pools at the cone ribbon synapse: Changes in release probability are solely responsible for voltage-dependent changes in release.

    PubMed

    Thoreson, Wallace B; Van Hook, Matthew J; Parmelee, Caitlyn; Curto, Carina

    2016-01-01

    Postsynaptic responses are a product of quantal amplitude (Q), size of the releasable vesicle pool (N), and release probability (P). Voltage-dependent changes in presynaptic Ca(2+) entry alter postsynaptic responses primarily by changing P but have also been shown to influence N. With simultaneous whole cell recordings from cone photoreceptors and horizontal cells in tiger salamander retinal slices, we measured N and P at cone ribbon synapses by using a train of depolarizing pulses to stimulate release and deplete the pool. We developed an analytical model that calculates the total pool size contributing to release under different stimulus conditions by taking into account the prior history of release and empirically determined properties of replenishment. The model provided a formula that calculates vesicle pool size from measurements of the initial postsynaptic response and limiting rate of release evoked by a train of pulses, the fraction of release sites available for replenishment, and the time constant for replenishment. Results of the model showed that weak and strong depolarizing stimuli evoked release with differing probabilities but the same size vesicle pool. Enhancing intraterminal Ca(2+) spread by lowering Ca(2+) buffering or applying BayK8644 did not increase PSCs evoked with strong test steps, showing there is a fixed upper limit to pool size. Together, these results suggest that light-evoked changes in cone membrane potential alter synaptic release solely by changing release probability.

  9. [Evolution of oral drug forms of metoprolol: advantages of long acting modified release forms with modified release].

    PubMed

    Leonova, M V; Maneshina, O A; Belousov, Iu B

    2010-01-01

    Review oral modified release drug forms of beta-adrenoblocker metoprolol which is used in arterial hypertension and ischemic heart disease is presented. Metoprolol has salts such as tartrate which is used for production of immediate release (IR) and sustained release (SR) forms and succinate used for production of controlled release form (CR/XL). Metoprolol SR has monolith matrix type, metoprolol CR/XL-system of multiple pellets. Effect of metoprolol tartrate (IR) on mortality was demonstrated in a number of studies in patients with arterial hypertension (AH) (MAPHY), myocardial infarction (SMT, GMT, MIAMI), dilated cardiomyopathy and heart failure (MDC). Studies of efficacy of metoprolol SR are scarce. Antihypertensive efficacy of metoprolol SR in patients with AH did not exceed that of a metoprolol IR or CR/XL. First retrospective analysis of efficacy of metoprolol tartrate and succinate (CR/XL) in patients after myocardial infarction allowed to obtain comparable results of 34% mortality lowering. In a prospective study in patients with chronic heart failure (COMET) metoprolol tartrate IR was not superior to carvedilol when mortality lowering was concerned. At the same time administration of controlled release metoprolol (CR/XL) in 2 large clinical trials (RESOLVD, MERITAHF) was advantageous in patients with chronic heart failure relative to lowering of mortality and rate of hospitalizations. A novel controlled release form of metoprolol has been created as a tartrate salt on the basis of pellet technology (CD/ERT) and its bioequivalence to metoprolol CR/XL has been proved.

  10. Release mechanism and parameter estimation in drug-eluting stent systems: analytical solutions of drug release and tissue transport.

    PubMed

    McGinty, Sean; McKee, Sean; McCormick, Christopher; Wheel, Marcus

    2015-06-01

    Drug-eluting stents have significantly improved the treatment of coronary artery disease. They offer reduced rates of restenosis compared with their bare-metal predecessors and are the current gold standard in percutaneous coronary interventions. Drug-eluting stents have been approved for use in humans since 2002 and yet, despite the intensive research activity over the past decade, the drug release mechanism(s) and the uptake into the arterial wall are still poorly understood. While stent manufacturers have focussed primarily on empirical methods, several mathematical models have appeared in the literature considering the release problem, the uptake problem and also the coupled problem. However, two significant challenges that remain are in understanding the drug release mechanism(s) and also the determination of the various parameters characterizing the system. These include drug diffusion coefficients and dissolution constants in the stent polymer coating as well as drug diffusion coefficients, binding/uptake rates and the magnitude of the transmural convection in the arterial wall. In this paper we attempt to address these problems. We provide analytical solutions which, when compared with appropriate experiments, may allow the various parameters of the system to be estimated via the inverse problem. The analytical solutions which we provide here for drug release in vitro may thus be used as a tool for providing insights into the mechanism(s) of release.

  11. Limited incision carpal tunnel release

    PubMed Central

    Gaba, Sunil; Bhogesha, Sandeep; Singh, Onkar

    2017-01-01

    Background: Carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy. Limited incision techniques for carpal tunnel release are gaining popularity. The main advantages of these techniques are less scar load, less pillar pain, shorter recovery, and return-to-work time. However, the completeness of release, and risk of neurovascular injury are always a concern. We devised a method of limited incision release with two mini-incisions and use of nasal speculum and a probe. We aimed to evaluate the clinical and neurological outcome of this technique. Materials and Methods: Twenty seven cases (9 male and 18 female, age 28–56 years) of isolated CTS cases were enrolled in the study. A total of 33 hands (six bilateral) underwent limited incision carpal tunnel release. In this study, two mini-incisions were used and release was done with the help of nasal speculum. Evaluation preoperatively and in 6 months and at 1-year postoperatively was done, namely, (a) clinical status examination, (b) motor testing using grip and pinch dynamometer, and (c) neurological outcome measure using nerve conduction study. Results: All the patients had good clinical and neurological outcome with no recurrence during followup. The first symptom to get relieved was night pains, with a mean of 4.5 days (range 2–14 days). Compared to pain, improvement of sensory symptoms was delayed; the mean duration was 42.8 days (range 30–90 days). Scar tenderness was present only for a mean duration of 9 days (range 7–21 days). The mean duration for patients to resume their daily activities was12 days (range 7–28 days) and to work was 32 days (range 21–90 days). The hand grip showed mean values of 45.12 ± 16.16 g/mm2 preoperatively, 62.45 ± 18.86 g/mm2 at 6 months postoperatively, and 74.87 ± 20.35 g/mm2 at 1-year postoperatively. The key pinch showed mean values of 11.27 ± 3.51 g/mm2 preoperatively, 20.181 ± 3.94 g/mm2 at 6 months postoperatively, and 27.96 ± 94.42 g/mm2

  12. Zegerid--immediate-release omeprazole.

    PubMed

    2005-04-11

    The FDA has approved marketing of Zegerid powder for oral suspension (Santarus), an immediate-release formulation of the proton-pump inhibitor (PPI) omeprazole (Prilosec, and others). All other oral PPIs are delayed-release, enteric-coated formulations designed to prevent degradation of the drug by gastric acid. Each 20- or 40-mg packet of Zegerid contains 1680 mg sodium bicarbonate, which protects the drug from gastric acid degradation. A dose of Zegerid contains 460 mg of sodium, which may be excessive for some patients. Zegerid is the first oral PPI to be approved by the FDA for reduction of risk of upper GI bleeding in critically ill patients. The drug may be useful for patients who are unable to swallow and have nasogastric (NG) tubes in place. Zegerid cost $70.00 for 14 days' treatment, compared to less than $10 for 14 tablets of Prilosec OTC.

  13. Neutron-absorber release device

    DOEpatents

    VAN Erp, Jan B.; Kimont, Edward L.

    1976-01-01

    A resettable device is provided for supporting an object, sensing when an environment reaches a critical temperature and releasing the object when the critical temperature is reached. It includes a flexible container having a material inside with a melting point at the critical temperature. The object's weight is supported by the solid material which gives rigidity to the container until the critical temperature is reached at which point the material in the container melts. The flexible container with the now fluid material inside has insufficient strength to support the object which is thereby released. Biasing means forces the container back to its original shape so that when the temperature falls below the melting temperature the material again solidifies, and the object may again be supported by the device.

  14. PREDICTING RECIDIVISM FOR RELEASED STATE PRISON OFFENDERS

    PubMed Central

    Stahler, Gerald J.; Mennis, Jeremy; Belenko, Steven; Welsh, Wayne N.; Hiller, Matthew L.; Zajac, Gary

    2013-01-01

    We examined the influence of individual and neighborhood characteristics and spatial contagion in predicting reincarceration on a sample of 5,354 released Pennsylvania state prisoners. Independent variables included demographic characteristics, offense type, drug involvement, various neighborhood variables (e.g., concentrated disadvantage, residential mobility), and spatial contagion (i.e., proximity to others who become reincarcerated). Using geographic information systems (GIS) and logistic regression modeling, our results showed that the likelihood of reincarceration was increased with male gender, drug involvement, offense type, and living in areas with high rates of recidivism. Older offenders and those convicted of violent or drug offenses were less likely to be reincarcerated. For violent offenders, drug involvement, age, and spatial contagion were particular risk factors for reincarceration. None of the neighborhood environment variables were associated with increased risk of reincarceration. Reentry programs need to particularly address substance abuse issues of ex-offenders as well as take into consideration their residential locations. PMID:24443612

  15. Method and apparatus for controlling accidental releases of tritium

    DOEpatents

    Galloway, Terry R. [Berkeley, CA

    1980-04-01

    An improvement in a tritium control system based on a catalytic oxidation reactor wherein accidental releases of tritium into room air are controlled by flooding the catalytic oxidation reactor with hydrogen when the tritium concentration in the room air exceeds a specified limit. The sudden flooding with hydrogen heats the catalyst to a high temperature within seconds, thereby greatly increasing the catalytic oxidation rate of tritium to tritiated water vapor. Thus, the catalyst is heated only when needed. In addition to the heating effect, the hydrogen flow also swamps the tritium and further reduces the tritium release.

  16. Method and apparatus for controlling accidental releases of tritium

    DOEpatents

    Galloway, T.R.

    1980-04-01

    An improvement is described in a tritium control system based on a catalytic oxidation reactor wherein accidental releases of tritium into room air are controlled by flooding the catalytic oxidation reactor with hydrogen when the tritium concentration in the room air exceeds a specified limit. The sudden flooding with hydrogen heats the catalyst to a high temperature within seconds, thereby greatly increasing the catalytic oxidation rate of tritium to tritiated water vapor. Thus, the catalyst is heated only when needed. In addition to the heating effect, the hydrogen flow also swamps the tritium and further reduces the tritium release. 1 fig.

  17. Macula densa sensing and signaling mechanisms of renin release.

    PubMed

    Peti-Peterdi, János; Harris, Raymond C

    2010-07-01

    Macula densa cells in the distal nephron, according to the classic paradigm, are salt sensors that generate paracrine chemical signals in the juxtaglomerular apparatus to control vital kidney functions, including renal blood flow, glomerular filtration, and renin release. Renin is the rate-limiting step in the activation of the renin-angiotensin system, a key modulator of body fluid homeostasis. Here, we discuss recent advances in understanding macula densa sensing and suggest these cells, in addition to salt, also sense various chemical and metabolic signals in the tubular environment that directly trigger renin release.

  18. Macula Densa Sensing and Signaling Mechanisms of Renin Release

    PubMed Central

    Peti-Peterdi, János; Harris, Raymond C.

    2015-01-01

    Macula densa cells in the distal nephron, according to the classic paradigm, are salt sensors that generate paracrine chemical signals in the juxtaglomerular apparatus to control vital kidney functions, including renal blood flow, glomerular filtration, and renin release. Renin is the rate-limiting step in the activation of the renin-angiotensin system, a key modulator of body fluid homeostasis. Here, we discuss recent advances in understanding macula densa sensing and suggest these cells, in addition to salt, also sense various chemical and metabolic signals in the tubular environment that directly trigger renin release. PMID:20360309

  19. Fabrication of drug eluting implants: study of drug release mechanism from titanium dioxide nanotubes

    NASA Astrophysics Data System (ADS)

    Hamlekhan, Azhang; Sinha-Ray, Suman; Takoudis, Christos; Mathew, Mathew T.; Sukotjo, Cortino; Yarin, Alexander L.; Shokuhfar, Tolou

    2015-06-01

    Formation of titanium dioxide nanotubes (TNTs) on a titanium surface holds great potential for promoting desirable cellular response. However, prolongation of drug release from these nano-reservoirs remains to be a challenge. In our previous work TNTs were successfully loaded with a drug. In this study the effect of TNTs dimensions on prolongation of drug release is quantified aiming at the introduction of a simple novel technique which overcomes complications of previously introduced methods. Different groups of TNTs with different lengths and diameters are fabricated. Samples are loaded with a model drug and rate of drug release over time is monitored. The relation of the drug release rate to the TNT dimensions (diameter, length, aspect ratio and volume) is established. The results show that an increase in any of these parameters increases the duration of the release process. However, the strongest parameter affecting the drug release is the aspect ratio. In fact, TNTs with higher aspect ratios release drug slower. It is revealed that drug release from TNT is a diffusion-limited process. Assuming that diffusion of drug in (Phosphate-Buffered Saline) PBS follows one-dimensional Fick’s law, the theoretical predictions for drug release profile is compatible with our experimental data for release from a single TNT.

  20. The Use of Cellulose Membrane to Eliminate Burst Release from Intravaginal Rings.

    PubMed

    Helbling, Ignacio M; Ibarra, Juan C D; Luna, Julio A

    2016-07-01

    Burst release was observed when ethylene vinyl acetate copolymer (EVA) intravaginal rings were tested for progesterone release in our previous work (Helbling et al. Pharm Res. 31(3):795-808, 2014). Burst release is undesirable in controlled delivery devices because release is uncontrollable and higher levels of active pharmaceutical ingredient could lead to the occurrence of adverse effect. The present contribution is about the use of membranes to coat EVA rings to eliminate burst release. Physicochemical state of progesterone in uncoated rings and the solubility and diffusion coefficient in membrane were studied. Hormone delivery from several rings of different sizes was compared. A mathematical model was used to analyze the effects of membrane properties on delivery rate. No chemical interactions were detected between hormone and polymer. Hormone was mainly forming amorphous aggregates inside rings, and migration to membrane was not observed during storage. Diffusion coefficient was smaller in membrane (∼10(-8) cm(2) s(-1)) than in matrix (∼10(-7) cm(2) s(-1)). Zero-order release kinetics were obtained for coated rings, and release rate decreases as the thickness of the coat increases. Cellulose membrane successfully eliminates burst release and controls the delivery from EVA rings. The equations developed can be used to determine the appropriate coat thickness to produce specific release rate.

  1. PS foams at high pressure drop rates

    NASA Astrophysics Data System (ADS)

    Tammaro, Daniele; De Maio, Attilio; Carbone, Maria Giovanna Pastore; Di Maio, Ernesto; Iannace, Salvatore

    2014-05-01

    In this paper, we report data on PS foamed at 100 °C after CO2 saturation at 10 MPa in a new physical foaming batch that achieves pressure drop rates up to 120 MPa/s. Results show how average cell size of the foam nicely fit a linear behavior with the pressure drop rate in a double logarithmic plot. Furthermore, foam density initially decreases with the pressure drop rate, attaining a constant value at pressure drop rates higher than 40 MPa/s. Interestingly, furthermore, we observed that the shape of the pressure release curve has a large effect on the final foam morphology, as observed in tests in which the maximum pressure release rate was kept constant but the shape of the curve changed. These results allow for a fine tuning of the foam density and morphology for specific applications.

  2. Controlled release of carbofuran from an alginate-bentonite formulation: water release kinetics and soil mobility.

    PubMed

    Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E; Martinez-López, F; Flores-Céspedes, F

    2000-03-01

    The insecticide-nematicide carbofuran was incorporated in alginate-based granules to obtain controlled-release (CR) properties. The basic formulation [sodium alginate (1.61%)-carbofuran (0. 59%)-water] was modified by addition of sorbents. The effect on carbofuran release rate, caused by the incorporation of natural and acid-treated bentonite (0.5 and 1.0 M H(2)SO(4)) in alginate formulation, was studied by immersion of the granules in water under shaking. The time taken for 50% of the active ingredient to be released into water, t(50), was longer for those formulations containing natural bentonite (6.1 h) or acid-treated bentonite (9.0 and 11.7 h for 0.5 and 1.0 M H(2)SO(4) treatments, respectively) than for the preparation without bentonite (4.7 h). It appears from the results that the release of carbofuran from the various formulations is controlled by a diffusion mechanism according to the n values obtained, which were close to 0.5 in all cases. The mobility of carbofuran from alginate-based CR formulations was investigated by using soil columns packed with a clay soil (53% clay and 0.08% organic matter). Two alginate-based CR formulations containing natural bentonite or acid-treated bentonite (0.5 M H(2)SO(4)) were compared to technical grade carbofuran. The use of alginate-based CR formulations resulted in a reduction of the leached amount of carbofuran compared with the total amount of pesticide leached using the technical product (50 and 75% for CR granules containing natural and acid-treated bentonite, respectively). Alginate-bentonite CR formulations might be efficient systems for reducing carbofuran leaching in clay soils, which would reduce the risk of groundwater pollution.

  3. Fluoride release from restorative materials.

    PubMed

    Basso, Gabriela Romanini; Della Bona, Alvaro; Gobbi, Delton Luiz; Cecchetti, Dileta

    2011-01-01

    The aim of this study was to evaluate in vitro fluoride (F) release from 4 restorative materials (3M ESPE): Ketak Molar Easymix [KME - conventional glass ionomer cement (GIC)]; Rely-X luting 2 [RL2 - resin-modified GIC (RMGIC)]; Vitremer (VIT- RMGIC); and Filtek Z250 [Z250 - negative control]. Disc-shaped specimens were fabricated according to the manufacturer's instructions and placed into 10 mL of reverse osmosis water at 37°C until the analyses were done using a liquid membrane for selective F ion electrode (Orion 710). F release was evaluated every 6 h in the first day and thereafter daily during 28 days (d). The results were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Mean F release and standard deviation values (in ppm) were: KME: 6 h- 0.34 ± 0.04; 24 h- 1.22 ± 0.30; 7 d- 0.29 ± 0.09; 14 d- 0.20 ± 0.04; 28 d- 0.16 ± 0.01; RL2: 6 h- 2.46 ± 0.48; 24 h-12.33 ± 2.93; 7 d- 1.37 ± 0.38; 14 d- 0.80 ± 0.13; 28 d- 0.80 ± 0.21; VIT: 6 h- 0.98 ± 0.35; 24 h- 4.35 ± 1.22; 7 d- 0.66 ± 0.23; 14 d- 0.40 ± 0.07; 28 d- 0.39 ± 0.08; Z250: 6 h- 0.029 ± 0.001; 24 h- 0.024 ± 0.009; 7 d- 0.023 ± 0.004; 14 d- 0.025 ± 0.001; 28 d- 0.028 ± 0.001. RL2 RMGIC released more F than the other materials in all periods. The greatest release of F occurred in the first 24 h.

  4. Sulfur dioxide prodrugs: triggered release of SO2via a click reaction.

    PubMed

    Wang, Wenyi; Ji, Xingyue; Du, Zhenming; Wang, Binghe

    2017-01-24

    Sulfur dioxide (SO2) is being recognized as a possible endogenous gasotransmitter with importance on par with that of NO, CO, and H2S. Herein we describe a series of SO2 prodrugs that are activated for SO2 release via a bioorthogonal click reaction. The release rate can be tuned by adjusting the substituents on the prodrug.

  5. Kinetics of piroxicam release from low-methylated pectin/zein hydrogel microspheres

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The kinetics of a model drug (piroxicam) release from pectin/zein hydrogel microspheres was studied under conditions simulating the gastrointestinal tract. It is established that the rate-limiting step in the release mechanism is drug diffusion out of the microspheres rather than its dissolution. ...

  6. Novel slow release nanocomposite nitrogen fertilizers: the impact of polymers on nanocomposite properties and function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efficient use of fertilizers, especially nitrogen, is essential and strategic to agricultural production. Among the technologies that can contribute to efficient use of fertilizers are slow or controlled release products. This paper describes the impact on structure, urea release rate and function i...

  7. Percutaneous Release of the First Dorsal Extensor Compartment: A Cadaver Study

    PubMed Central

    Güleç, Ali; Türkmen, Faik; Toker, Serdar

    2016-01-01

    Background: To evaluate the efficiency of the percutaneous 18-G needle technique in releasing the fibro-osseous sheath over the first dorsal extensor compartment of the hand. Methods: Using anatomic landmarks, percutaneous release was performed with an 18-G needle on 48 wrists of 24 cadavers. The specimens were then dissected and examined for the completeness of the first dorsal extensor compartment release and any tendon or neurovascular injuries. The tunnel length, number of abductor pollicis longus and extensor pollicis brevis tendons, presence of an intertendinous septum, and the effects of these parameters on percutaneous release were evaluated. Results: Percutaneous release was performed on all of the wrists, and the evaluation of the adequacy of release revealed 25 complete releases, 21 partial releases, and 2 missed releases. There were 19 cases of tendon complications. No neurovascular injuries were noted. The mean tunnel length was 2.66 ± 30 cm, and the mean number of tendons was 2.75 ± 0.86. A septum was present in 33.3% of cases. Tunnel length and tendon number had no statistically significant effect on release, whereas the presence of a septum was significantly associated with inadequate tunnel release and the development of tendon complications. Conclusions: Percutaneous release of the first dorsal extensor compartment using an 18-G needle was associated with high rates of incomplete release and tendon damage in the presence of an intertendinous septum. Further study is required under ultrasound guidance to determine the usefulness of percutaneous release in the first dorsal extensor compartment. Clinical Relevance: Release with a percutaneous needle tip in De Quervain’s syndrome may provide the advantages of better cosmetic results with less scar formation and an early return to work. PMID:27826460

  8. Effectiveness of multiple release sites in reintroduction of Persian fallow deer.

    PubMed

    Berger-Tal, Oded; Bar-David, Shirli; Saltz, David

    2012-02-01

    Releasing animals in more than one location may increase or decrease the probability of success of a reintroduction project, yet the question of how many release sites to use has received little attention. We used empirical data from the reintroduction program of the Persian fallow deer (Dama mesopotamica) (Galilee region in northern Israel) in an individual-based spatially explicit simulation model to assess the effects of releasing deer from multiple sites. We examined whether multiple release sites increase reintroduction success, and if so, whether the optimal number of sites for a given scenario can be determined and whether the outcome differs if animals are released alternately (i.e., the location of the release alternates yearly between sites) or consecutively (i.e., one release site is used for several years, then another is used, and so forth). We selected 8 potential release sites in addition to the original site and simulated the release of 180 individuals at a rate of 10 individuals per year in different combinations of the original site and 1-4 additional sites. In our model, releasing animals into the wild at multiple sites produced higher population growth and greater spatial expansion than releasing animals at only one site and a consecutive-release approach was superior to an alternate-release approach. We suggest that through the use of simulation modeling that is based on empirical data from previous releases, managers can make better-informed decisions regarding the use of multiple release sites and greatly improve the probability of reintroduction success.

  9. Controlled Release of Salicylic Acid from Biodegradable Cross-Linked Polyesters.

    PubMed

    Dasgupta, Queeny; Chatterjee, Kaushik; Madras, Giridhar

    2015-09-08

    The purpose of this work was to develop a family of cross-linked poly(xylitol adipate salicylate)s with a wide range of tunable release properties for delivering pharmacologically active salicylic acid. The synthesis parameters and release conditions were varied to modulate polyester properties and to understand the mechanism of release. Varying release rates were obtained upon longer curing (35% in the noncured polymer to 10% in the cured polymer in 7 days). Differential salicylic acid loading led to the synthesis of polymers with variable cross-linking and the release could be tuned (100% release for the lowest loading to 30% in the highest loading). Controlled release was monitored by changing various factors, and the release profiles were dependent on the stoichiometric composition, pH, curing time, and presence of enzyme. The polymer released a combination of salicylic acid and disalicylic acid, and the released products were found to be nontoxic. Minimal hemolysis and platelet activation indicated good blood compatibility. These polymers qualify as "bioactive" and "resorbable" and can, therefore, find applications as immunomodulatory resorbable biomaterials with tunable release properties.

  10. Synapsins Differentially Control Dopamine and Serotonin Release

    PubMed Central

    Kile, Brian M.; Guillot, Thomas S.; Venton, B. Jill; Wetsel, William C.; Augustine, George J.; Wightman, R. Mark

    2010-01-01

    Synapsins are a family of synaptic vesicle proteins that are important for neurotransmitter release. Here we have used triple knockout (TKO) mice lacking all three synapsin genes to determine the roles of synapsins in the release of two monoamine neurotransmitters, dopamine and serotonin. Serotonin release evoked by electrical stimulation was identical in substantia nigra pars reticulata slices prepared from TKO and wild-type mice. In contrast, release of dopamine in response to electrical stimulation was approximately doubled in striatum of TKO mice, both in vivo and in striatal slices, in comparison to wild-type controls. This was due to loss of synapsin III, because deletion of synapsin III alone was sufficient to increase dopamine release. Deletion of synapsins also increased the sensitivity of dopamine release to extracellular calcium ions. Although cocaine did not affect the release of serotonin from nigral tissue, this drug did enhance dopamine release. Cocaine-induced facilitation of dopamine release was a function of external calcium, an effect that was reduced in TKO mice. We conclude that synapsins play different roles in the control of release of dopamine and serotonin, with release of dopamine being negatively regulated by synapsins, specifically synapsin III, while serotonin release appears to be relatively independent of synapsins. These results provide further support for the concept that synapsin function in presynaptic terminals varies according to the neurotransmitter being released. PMID:20660258

  11. Study of the radon released from open drill holes

    SciTech Connect

    Pacer, J C

    1981-06-01

    The radon emanating from three open drill holes was measured at a site of known uranium mineralization in the Red Desert of south central Wyoming. The radon flux from the soil and drill holes was measured by the accumulator method with activated charcoal cartridges. The surface soil was found to release radon at an average rate of 0.41 atoms/cm/sup 2//sec; the radon emanating from the holes was more variable than that from the soil. The three holes studied released an average of 47 atoms/cm/sup 2//sec of radon. This average is equivalent to the radon released to the atmosphere by 14.5 ft/sup 2/ of soil. The data indicate that the radon emanated from an open drill hole is not as significant as other possible activities at a drill site (i.e. digging a trench or drilling a hole) or from household activities involving the usage of water.

  12. [The release of biologically active compounds from peat peloids].

    PubMed

    Babaskin, D V

    2011-01-01

    This work had the objective to study kinetics of the release of flavonoides from peat peloid compositions containing extracts of medicinal herbs in model systems.The key parameters of the process are defined. The rate of liberation of flavonoides is shown to depend on their initial concentration in the compositions being used. The influence of the flavonoide composition of the tested extracts and dimethylsulfoxide on the release of biologically active compounds contained in the starting material in the model environment is estimated. The possibility of the layer-by-layer deposition of the compositions and peat peloids in order to increase the efficacy of flavonoide release from the starting composition and to ensure more rational utilization of the extracts of medicinal plants is demonstrated.

  13. Imaging renin content and release in the living kidney.

    PubMed

    Toma, Ildikó; Kang, Jung Julie; Peti-Peterdi, János

    2006-01-01

    Renin release is the first, and at least initially, the rate-limiting step in the activation of the renin-angiotensin system, which helps to maintain body salt and water balance. Recent advances in our understanding of pathophysiology have generated a renewed interest in the multiple roles of renin and prorenin as a hormone, enzyme, and signaling molecule. The assays available to measure renin content, release and tissue activity are complex, indirect and work with significant internal errors. We developed an imaging approach to directly visualize renin content and study the dynamics of both the release and tissue activity of renin. Our experimental model uses multiphoton fluorescence microscopy, which is ideal for deep optical sectioning of the living renal tissue. Here we review the application of this renin imaging approach to the dissected, in vitro microperfused glomerulus as well as in the intact kidney in vivo.

  14. Gastrin-releasing peptide stimulates glycoconjugate release from feline trachea

    SciTech Connect

    Lundgren, J.D.; Baraniuk, J.N.; Ostrowski, N.L.; Kaliner, M.A.; Shelhamer, J.H. )

    1990-02-01

    The effect of gastrin-releasing peptide (GRP) on respiratory glycoconjugate (RGC) secretion was investigated in a feline tracheal organ culture model. RGC secretion was stimulated by GRP in a dose-dependent fashion at concentrations from 10(-8) to 10(-5) M (range 15-38% increase above control) with a peak effect within 0.5-1 h of incubation. GRP-(14-27), the receptor binding portion of GRP, and the related molecule, bombesin, also stimulated RGC secretion by approximately 20% above control. Acetyl-GRP-(20-27) stimulated RGC release by 10%, whereas GRP-(1-16) was inactive. Autoradiographic studies with 125I-GRP revealed that specific binding was restricted to the submucosal glands and the surface epithelium. A specific radioimmunoassay showed the content of GRP in feline trachea after extraction with ethanol-acetic acid to be 156 +/- 91 fmol/g wet wt. Indirect immunohistochemistry indicated that ganglion cells located just outside the cartilage contained GRP-immunoreactive materials. GRP is a novel mucus secretagogue that may participate in regulating airway mucosal gland secretion.

  15. Modified pipe extension safely releases chain binders

    NASA Technical Reports Server (NTRS)

    Haw, D. W.

    1978-01-01

    Pipe, cut partly in half lengthwise, and cupped and notched at one end, safely releases tension in chain binders that cinch tiedown chains around truck loads. Device prevents binder-handle from being thrown violently during release.

  16. Safety Precautions for Total Release Foggers

    EPA Pesticide Factsheets

    Total release foggers, also known as bug bombs, are pesticide products containing aerosol propellants that release their contents at once to fumigate an area. They can pose a hazard if used incorrectly. Find safety information and videos on this page.

  17. Section 9: Ground Water - Likelihood of Release

    EPA Pesticide Factsheets

    HRS training. the ground water pathway likelihood of release factor category reflects the likelihood that there has been, or will be, a release of hazardous substances in any of the aquifers underlying the site.

  18. Pathways of proton release in the bacteriorhodopsin photocycle

    NASA Technical Reports Server (NTRS)

    Zimanyi, L.; Varo, G.; Chang, M.; Ni, B.; Needleman, R.; Lanyi, J. K.

    1992-01-01

    The pH dependencies of the rate constants in the photocycles of recombinant D96N and D115N/D96N bacteriorhodopsins were determined from time-resolved difference spectra between 70 ns and 420 ms after photoexcitation. The results were consistent with the model suggested earlier for proteins containing D96N substitution: BR hv----K----L----M1----M2----BR. Only the M2----M1 back-reaction was pH-dependent: its rate increased with increasing [H+] between pH 5 and 8. We conclude from quantitative analysis of this pH dependency that its reverse, the M1----M2 reaction, is linked to the release of a proton from a group with a pKa = 5.8. This suggests a model for wild-type bacteriorhodopsin in which at pH greater than 5.8 the transported proton is released on the extracellular side from this as yet unknown group and on the 100-microseconds time scale, but at pH less than 5.8, the proton release occurs from another residue and later in the photocycle most likely directly from D85 during the O----BR reaction. We postulate, on the other hand, that proton uptake on the cytoplasmic side will be by D96 and during the N----O reaction regardless of pH. The proton kinetics as measured with indicator dyes confirmed the unique prediction of this model: at pH greater than 6, proton release preceded proton uptake, but at pH less than 6, the release was delayed until after the uptake. The results indicated further that the overall M1----M2 reaction includes a second kinetic step in addition to proton release; this is probably the earlier postulated extracellular-to-cytoplasmic reorientation switch in the proton pump.

  19. Mars Express releases Beagle 2

    NASA Astrophysics Data System (ADS)

    2003-12-01

    At 9:31 CET, the crucial sequence started to separate the Beagle 2 lander from Mars Express. As data from Mars Express confirm, the pyrotechnic device was fired to slowly release a loaded spring, which gently pushed Beagle 2 away from the mother spacecraft. An image from the onboard visual monitoring camera (VMC) showing the lander drifting away is expected to be available later today. Since the Beagle 2 lander has no propulsion system of its own, it had to be put on the correct course for its descent before it was released. For this reason, on 16 December the trajectory of the whole Mars Express spacecraft had to be adjusted to ensure that Beagle 2 would be on course to enter the atmosphere of Mars. This manoeuvre, called "retargeting'' was critical: if the entry angle is too steep, the lander could overheat and burn up in the atmosphere; if the angle is too shallow, the lander might skim like a pebble on the surface of a lake and miss its target. This fine targeting and today's release were crucial manoeuvres for which ESA's Ground Control Team at ESOC (European Space Operations Centre) had trained over the past several months. The next major milestone for Mars Express will be the manoeuvre to enter into orbit around Mars. This will happen at 3:52 CET on Christmas morning, when Beagle 2 is expected to land on the surface of Mars. "Good teamwork by everybody - ESA, industry and the Beagle 2 team - has got one more critical step accomplished. Mars, here comes Europe!" said David Southwood, ESA Director of Science.

  20. Social support among releasing men prisoners with lifetime trauma experiences.

    PubMed

    Pettus-Davis, Carrie

    2014-01-01

    High rates of lifetime trauma experiences exist among men incarcerated in US state and federal prisons. Because lifetime trauma experiences have been linked to problematic behavioral and psychiatric outcomes for incarcerated populations, trauma-informed interventions could improve post-release well-being of releasing men prisoners with trauma histories. Social support has consistently been found to have a positive impact on trauma-related outcomes in non-incarcerated populations. Therefore, it is reasonable to hypothesize that social support may be an important intervention component for releasing men prisoners with trauma experiences; yet, the relationship between trauma experiences, psychiatric and behavioral factors, and social support has received almost no attention in research with men prisoners. Using a probability sample of 165 soon-to-be-released men, the present study examined differences in certain demographic, criminal justice history, mental health, substance abuse, and social support (type, quality, amount, and source) variables between releasing men prisoners with and without lifetime trauma experiences. Results indicate that men with trauma histories had more negative social support experiences and fewer positive social support resources before prison than their counterparts. Men with trauma histories also had more lifetime experiences with mental health and substance use problems. On further investigation of the subsample of men with trauma histories, those who were older, had substance use disorders, and histories of mental health problems anticipated fewer post-release social support resources. Study findings underscore the nuances of social support for men prisoners with trauma experiences and point to implications for future directions in targeted trauma-informed intervention development for releasing men prisoners.

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

    NASA Astrophysics Data System (ADS)

    Kou, Jim Hwai-Cher

    In this study, ionizable copolymers of HEMA and methacrylic acid (MA) are investigated for their potential use in developing pH dependent oral delivery systems. Because of the MA units, these gels swell extensively at high pH. Since solute diffusion in the hydrophilic polymers depends highly on the water content of the matrix, it is anticipated that the release rate will be modulated by this pH induced swelling. From a practical point of view, the advantage of the present system is that one can minimize drug loss in the stomach and achieve a programmed release in intestine. This approach is expected to improve delivery of acid labile drugs or drugs that cause severe gastrointestinal side effects. This work mainly focuses on the basic understanding of the mechanism involved in drug release from the poly(HEMA -co- MA) gels, especially under dynamic swelling conditions. Equilibrium swelling is first characterized since water content is the major determinant of transport properties in these gels. Phenylpropanolamine (PPA) is chosen as the model drug for the release study and its diffusion characteristics in the gel matrix determined. The data obtained show that the PPA diffusivity follows the free volume theory of Yasuda, which explains the accelerating effect of swelling on drug release. A mathematical model based on a diffusion mechanism has been developed to describe PPA release from the swelling gels. Based on this model, several significant conclusions can be drawn. First, the release