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Sample records for controlled release iron

  1. Potential for iron oxides to control metal releases in CO2 sequestration scenarios

    Science.gov (United States)

    Berger, P.M.; Roy, W.R.

    2011-01-01

    The potential for the release of metals into groundwater following the injection of carbon dioxide (CO2) into the subsurface during carbon sequestration projects remains an open research question. Changing the chemical composition of even the relatively deep formation brines during CO2 injection and storage may be of concern because of the recognized risks associated with the limited potential for leakage of CO2-impacted brine to the surface. Geochemical modeling allows for proactive evaluation of site geochemistry before CO2 injection takes place to predict whether the release of metals from iron oxides may occur in the reservoir. Geochemical modeling can also help evaluate potential changes in shallow aquifers were CO2 leakage to occur near the surface. In this study, we created three batch-reaction models that simulate chemical changes in groundwater resulting from the introduction of CO2 at two carbon sequestration sites operated by the Midwest Geological Sequestration Consortium (MGSC). In each of these models, we input the chemical composition of groundwater samples into React??, and equilibrated them with selected mineral phases and CO 2 at reservoir pressure and temperature. The model then simulated the kinetic reactions with other mineral phases over a period of up to 100 years. For two of the simulations, the water was also at equilibrium with iron oxide surface complexes. The first model simulated a recently completed enhanced oil recovery (EOR) project in south-central Illinois in which the MGSC injected into, and then produced CO2, from a sandstone oil reservoir. The MGSC afterwards periodically measured the brine chemistry from several wells in the reservoir for approximately two years. The sandstone contains a relatively small amount of iron oxide, and the batch simulation for the injection process showed detectable changes in several aqueous species that were attributable to changes in surface complexation sites. After using the batch reaction

  2. Enzymatic- and temperature-sensitive controlled release of ultrasmall superparamagnetic iron oxides (USPIOs

    Directory of Open Access Journals (Sweden)

    Ortega Ryan A

    2011-02-01

    Full Text Available Abstract Background Drug and contrast agent delivery systems that achieve controlled release in the presence of enzymatic activity are becoming increasingly important, as enzymatic activity is a hallmark of a wide array of diseases, including cancer and atherosclerosis. Here, we have synthesized clusters of ultrasmall superparamagnetic iron oxides (USPIOs that sense enzymatic activity for applications in magnetic resonance imaging (MRI. To achieve this goal, we utilize amphiphilic poly(propylene sulfide-bl-poly(ethylene glycol (PPS-b-PEG copolymers, which are known to have excellent properties for smart delivery of drug and siRNA. Results Monodisperse PPS polymers were synthesized by anionic ring opening polymerization of propylene sulfide, and were sequentially reacted with commercially available heterobifunctional PEG reagents and then ssDNA sequences to fashion biofunctional PPS-bl-PEG copolymers. They were then combined with hydrophobic 12 nm USPIO cores in the thin-film hydration method to produce ssDNA-displaying USPIO micelles. Micelle populations displaying complementary ssDNA sequences were mixed to induce crosslinking of the USPIO micelles. By design, these crosslinking sequences contained an EcoRV cleavage site. Treatment of the clusters with EcoRV results in a loss of R2 negative contrast in the system. Further, the USPIO clusters demonstrate temperature sensitivity as evidenced by their reversible dispersion at ~75°C and re-clustering following return to room temperature. Conclusions This work demonstrates proof of concept of an enzymatically-actuatable and thermoresponsive system for dynamic biosensing applications. The platform exhibits controlled release of nanoparticles leading to changes in magnetic relaxation, enabling detection of enzymatic activity. Further, the presented functionalization scheme extends the scope of potential applications for PPS-b-PEG. Combined with previous findings using this polymer platform that

  3. Ferrous iron-dependent drug delivery enables controlled and selective release of therapeutic agents in vivo.

    Science.gov (United States)

    Deu, Edgar; Chen, Ingrid T; Lauterwasser, Erica M W; Valderramos, Juan; Li, Hao; Edgington, Laura E; Renslo, Adam R; Bogyo, Matthew

    2013-11-05

    The precise targeting of cytotoxic agents to specific cell types or cellular compartments is of significant interest in medicine, with particular relevance for infectious diseases and cancer. Here, we describe a method to exploit aberrant levels of mobile ferrous iron (Fe(II)) for selective drug delivery in vivo. This approach makes use of a 1,2,4-trioxolane moiety, which serves as an Fe(II)-sensitive "trigger," making drug release contingent on Fe(II)-promoted trioxolane fragmentation. We demonstrate in vivo validation of this approach with the Plasmodium berghei model of murine malaria. Malaria parasites produce high concentrations of mobile ferrous iron as a consequence of their catabolism of host hemoglobin in the infected erythrocyte. Using activity-based probes, we successfully demonstrate the Fe(II)-dependent and parasite-selective delivery of a potent dipeptidyl aminopeptidase inhibitor. We find that delivery of the compound in its Fe(II)-targeted form leads to more sustained target inhibition with greatly reduced off-target inhibition of mammalian cathepsins. This selective drug delivery translates into improved efficacy and tolerability. These findings demonstrate the utility of a purely chemical means to achieve selective drug targeting in vivo. This approach may find useful application in parasitic infections and more broadly in any disease state characterized by aberrant production of reactive ferrous iron.

  4. Efficacy and tolerability of a prolonged release ferrous sulphate formulation in iron deficiency anaemia: a non-inferiority controlled trial.

    Science.gov (United States)

    Zaim, Mohammed; Piselli, Leonardo; Fioravanti, Pino; Kanony-Truc, Claire

    2012-03-01

    Iron deficiency anaemia (IDA) is the last stage of iron deficiency, consecutive to an imbalance between iron supply through food intake and iron loss through physiological or pathological processes. As well as by haemoglobin levels, IDA is diagnosed by measuring biomarkers of iron stores. Women are most affected by IDA since their teenage years, as menstruation constitutes a chronic iron loss. Oral supplementation with ferrous sulphate is an effective therapy, but gastrointestinal side effects may impair treatment compliance. The present multicentric randomised controlled trial was designed to assess the non-inferiority of a ferrous sulphate prolonged release formulation called V0355 with the referential ferrous sulphate Ferrograd® in a population of Italian women aged 18-50 years diagnosed for IDA. Three hundred and ninety-nine patients were randomised to receive V0355 (80 mg Fe/day) or Ferrograd® (105 mg Fe/day). After 12 weeks of treatment, the difference in the mean haemoglobin level between the two groups was 0.081 g/dL ([-2.986;1.361], p = 0.54), which confirmed the hypothesis of non-inferiority. All the other biochemical parameters (serum iron, serum ferritin, transferrin, and soluble transferrin receptor) and haematological parameters (erythrocytes count, reticulocytes count, haematocrit, and mean corpuscular volume), as well as patient's anaemia-related symptoms, were not different between treatment groups throughout the study. Furthermore, the incidence of gastrointestinal adverse events of moderate and severe intensity was significantly lower (p = 0.007) in the V0355 group (5.6%) than in the Ferrograd® group (13.9%). V0355 was as efficient as Ferrograd® in the treatment of anaemia and exhibited a better gastrointestinal tolerance profile.

  5. Antimicrobial and Controlled Release Studies of a Novel Nystatin Conjugated Iron Oxide Nanocomposite

    Directory of Open Access Journals (Sweden)

    Samer Hasan Hussein-Al-Ali

    2014-01-01

    Full Text Available Nystatin is a tetraene diene polyene antibiotic showing a broad spectrum of antifungal activity. In the present study, we prepared a nystatin nanocomposite (Nyst-CS-MNP by loading nystatin (Nyst on chitosan (CS coated magnetic nanoparticles (MNPs. The magnetic nanocomposites were characterized by X-ray powder diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, thermogravimetry analysis (TGA, vibrating sample magnetometer (VSM, and scanning electron microscopy (SEM. The XRD results showed that the MNPs and nanocomposite are pure magnetite. The FTIR analysis confirmed the binding of CS on the surface of the MNPs and also the loading of Nyst in the nanocomposite. The Nyst drug loading was estimated using UV-Vis instrumentation and showing a 14.9% loading in the nanocomposite. The TEM size image of the MNPs, CS-MNP, and Nyst-CS-MNP was 13, 11, and 8 nm, respectively. The release profile of the Nyst drug from the nanocomposite followed a pseudo-second-order kinetic model. The antimicrobial activity of the as-synthesized Nyst and Nyst-CS-MNP nanocomposite was evaluated using an agar diffusion method and showed enhanced antifungal activity against Candida albicans. In this manner, this study introduces a novel nanocomposite that can decrease fungus activity on-demand for numerous medical applications.

  6. Synthesis of a novel supermagnetic iron oxide nanocomposite hydrogel based on graft copolymerization of poly((2-dimethylamino)ethyl methacrylate) onto salep for controlled release of drug

    Energy Technology Data Exchange (ETDEWEB)

    Bardajee, Ghasem Rezanejade, E-mail: rezanejad@pnu.ac.ir; Hooshyar, Zari; Asli, Maryam Jahanbakhsh; Shahidi, Fatemeh Emamjome; Dianatnejad, Nastaran

    2014-03-01

    In this research, a novel supermagnetic iron oxide nanocomposite hydrogel was prepared using simultaneous in situ formation of iron oxide nanoparticles (IONs) and three-dimensional cross-linked polymer networks based on graft copolymerization of poly((2-dimethylamino)ethyl methacrylate) (PDMA) onto salep (PDMA-g-salep). The prepared ION–PDMA-g-salep hydrogel was systematically characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDAX), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). In addition, the ION–PDMA-g-salep hydrogel exhibits favorable swelling properties that are sensitive to temperature, pH, and external magnetic field (EMF). The drug release behavior of the prepared hydrogel under EMF, different temperatures and pHs was also studied for the evaluation of the release mechanism and determination of diffusion coefficients. Finally, the antibacterial activity and cytotoxicity studies of the prepared hydrogel were examined. These results suggested that the ION–PDMA-g-salep hydrogel could be a promising candidate for biological dressing applications. - Highlights: • We introduce a novel biocompatible magnetic iron oxide nanocomposite hydrogel for controlled drug release. • We use a facile method to biocompatible magnetic iron oxide nanocomposite hydrogel. • We prepare magnetic iron oxide nanocomposite hydrogel with high pH, temperature, and magnetic field-sensitivity.

  7. pH responsive controlled release of anti-cancer hydrophobic drugs from sodium alginate and hydroxyapatite bi-coated iron oxide nanoparticles.

    Science.gov (United States)

    Manatunga, Danushika C; de Silva, Rohini M; de Silva, K M Nalin; de Silva, Nuwan; Bhandari, Shiva; Yap, Yoke Khin; Costha, N Pabakara

    2017-08-01

    Developing a drug carrier system which could perform targeted and controlled release over a period of time is utmost concern in the pharmaceutical industry. This is more relevant when designing drug carriers for poorly water soluble drug molecules such as curcumin and 6-gingerol. Development of a drug carrier system which could overcome these limitations and perform controlled and targeted drug delivery is beneficial. This study describes a promising approach for the design of novel pH sensitive sodium alginate, hydroxyapatite bilayer coated iron oxide nanoparticle composite (IONP/HAp-NaAlg) via the co-precipitation approach. This system consists of a magnetic core for targeting and a NaAlg/HAp coating on the surface to accommodate the drug molecules. The nanocomposite was characterized using FT-IR spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. The loading efficiency and loading capacity of curcumin and 6-gingerol were examined. In vitro drug releasing behavior of curcumin and 6-gingerol was studied at pH 7.4 and pH 5.3 over a period of seven days at 37°C. The mechanism of drug release from the nanocomposite of each situation was studied using kinetic models and the results implied that, the release is typically via diffusion and a higher release was observed at pH 5.3. This bilayer coated system can be recognized as a potential drug delivery system for the purpose of curcumin and 6-gingerol release in targeted and controlled manner to treat diseases such as cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Rationale and design of the oral HEMe iron polypeptide Against Treatment with Oral Controlled Release Iron Tablets trial for the correction of anaemia in peritoneal dialysis patients (HEMATOCRIT trial

    Directory of Open Access Journals (Sweden)

    Isbel Nicole M

    2009-07-01

    Full Text Available Abstract Background The main hypothesis of this study is that oral heme iron polypeptide (HIP; Proferrin® ES administration will more effectively augment iron stores in erythropoietic stimulatory agent (ESA-treated peritoneal dialysis (PD patients than conventional oral iron supplementation (Ferrogradumet®. Methods Inclusion criteria are peritoneal dialysis patients treated with darbepoietin alpha (DPO; Aranesp®, Amgen for ≥ 1 month. Patients will be randomized 1:1 to receive either slow-release ferrous sulphate (1 tablet twice daily; control or HIP (1 tablet twice daily for a period of 6 months. The study will follow an open-label design but outcome assessors will be blinded to study treatment. During the 6-month study period, haemoglobin levels will be measured monthly and iron studies (including transferring saturation [TSAT] measurements will be performed bi-monthly. The primary outcome measure will be the difference in TSAT levels between the 2 groups at the end of the 6 month study period, adjusted for baseline values using analysis of covariance (ANCOVA. Secondary outcome measures will include serum ferritin concentration, haemoglobin level, DPO dosage, Key's index (DPO dosage divided by haemoglobin concentration, and occurrence of adverse events (especially gastrointestinal adverse events. Discussion This investigator-initiated multicentre study has been designed to provide evidence to help nephrologists and their peritoneal dialysis patients determine whether HIP administration more effectively augments iron stores in ESP-treated PD patients than conventional oral iron supplementation. Trial Registration Australia New Zealand Clinical Trials Registry number ACTRN12609000432213.

  9. Computational modeling and analysis of iron release from macrophages.

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    Alka A Potdar

    2014-07-01

    Full Text Available A major process of iron homeostasis in whole-body iron metabolism is the release of iron from the macrophages of the reticuloendothelial system. Macrophages recognize and phagocytose senescent or damaged erythrocytes. Then, they process the heme iron, which is returned to the circulation for reutilization by red blood cell precursors during erythropoiesis. The amount of iron released, compared to the amount shunted for storage as ferritin, is greater during iron deficiency. A currently accepted model of iron release assumes a passive-gradient with free diffusion of intracellular labile iron (Fe2+ through ferroportin (FPN, the transporter on the plasma membrane. Outside the cell, a multi-copper ferroxidase, ceruloplasmin (Cp, oxidizes ferrous to ferric ion. Apo-transferrin (Tf, the primary carrier of soluble iron in the plasma, binds ferric ion to form mono-ferric and di-ferric transferrin. According to the passive-gradient model, the removal of ferrous ion from the site of release sustains the gradient that maintains the iron release. Subcellular localization of FPN, however, indicates that the role of FPN may be more complex. By experiments and mathematical modeling, we have investigated the detailed mechanism of iron release from macrophages focusing on the roles of the Cp, FPN and apo-Tf. The passive-gradient model is quantitatively analyzed using a mathematical model for the first time. A comparison of experimental data with model simulations shows that the passive-gradient model cannot explain macrophage iron release. However, a facilitated-transport model associated with FPN can explain the iron release mechanism. According to the facilitated-transport model, intracellular FPN carries labile iron to the macrophage membrane. Extracellular Cp accelerates the oxidation of ferrous ion bound to FPN. Apo-Tf in the extracellular environment binds to the oxidized ferrous ion, completing the release process. Facilitated-transport model can

  10. Controlled-release microchips.

    Science.gov (United States)

    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.

  11. The release of iron during coal combustion. Milestone report

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, L.L. [Sandia National Labs., Livermore, CA (United States). Combustion Research Facility

    1995-06-01

    Iron plays an important role in the formation of both fly ash and deposits in many pulverized-coal-fired boilers. Several authors indicate that iron content is a significant indicator of the slagging propensity of a majority of US bituminous coals, in particular eastern bituminous coals. The pyritic iron content of these coals is shown to be a particularly relevant consideration. A series of investigations of iron release during combustion is reported for a suite of coals ranging in rank from lignite to low-volatile bituminous coal under combustion conditions ranging from oxidizing to inert. Experimental measurements are described in which, under selected conditions, major fractions of the iron in the coal are released within a 25 ms period immediately following coal devolatilization. Mechanistic interpretation of the data suggest that the iron is released as a consequence of oxygen attack on porous pyrrhotite particles. Experimental testing of the proposed mechanism reveals that the release is dependent on the presence of both pyrite in the raw coal and oxygen in the gas phase, that slow preoxidation (weathering) of the pyrite significantly inhibits the iron release, and that iron loss increases as oxygen penetration of the particle increases. Each observation is consistent with the postulated mechanism.

  12. Effects of Iron on DNA Release and Biofilm Development by Pseudomonas Aeruginosa

    DEFF Research Database (Denmark)

    Yang, Liang; Barken, Kim Bundvig; Skindersø, Mette Elena;

    2007-01-01

    Extracellular DNA is one of the major matrix components in Pseudomonas aeruginosa biofilms. It functions as an intercellular connector and plays a role in stabilization of the biofilms. Evidence that DNA release in P. aeruginosa PAO1 biofilms is controlled by the las-rhl and pqs quorum......-sensing systems has been previously presented. This paper provides evidence that DNA release in P. aeruginosa PAO1 biofilms is also under iron regulation. Experiments involving cultivation of P. aeruginosa in microtitre trays suggested that pqs expression, DNA release and biofilm formation were favoured in media...... with low iron concentrations (5 mu M FeCIA and decreased with increasing iron concentrations. Experiments involving cultivation of P. aeruginosa in a flow-chamber system suggested that a high level of iron (1100 mu M FeCl3) in the medium suppressed DNA release, structural biofilm development...

  13. Control Effect of Regulating pH and Alkalinity on Iron Release in Drinking Water Distribution System%调节pH值和碱度对给水管网铁释放的控制作用

    Institute of Scientific and Technical Information of China (English)

    米子龙; 张晓健; 王洋; 陈超; 顾军农

    2012-01-01

    The control effect of regulating pH and alkalinity on iron release in the drinking water distribution system was investigated. Experiments using the pipe section simulation reactor found that the iron release rate, turbidity and color decreased significantly with increasing pH and alkalinity. Specifically, after increasing pH from 7.6 to 8.2 for 15 d, the iron release rate, turbidity and color decreased by 47% , 54% and 46% , respectively. Meanwhile, increasing alkalinity from 135 mg/L to 260 mg/L (calculated as CaCO3) for 15 d, the iron release rate, turbidity and color decreased by 50% , 58% and 52% , respectively. The cost-effectiveness of regulating pH and alkalinity to control iron release in drinking water was evaluated. The results showed that the cost of regulating pH of finished water was appropriate. This method can be used as an emergency water treatment technology for red water control.%利用管段模拟反应器,定量分析了调节pH值和调节碱度技术对给水管网铁释放的控制作用.研究发现,提高pH值和增加碱度均可使管网铁释放速率、浊度和色度明显降低.调节pH值从7.6增加至8.2,15 d后管网铁释放速率降低了47%,浊度降低了54%,色度降低了46%;调节碱度从135 mg/L增加至260 mg/L(以CaCO3计),15 d后管网铁释放速率降低了50%,浊度降低了58%,色度降低了52%.对比评价了调节pH值和调节碱度技术的经济性,结果表明;调节出厂水pH值控制管网铁释放的经济成本适宜,可作为突发性管网“黄水”问题的应急控制技术.

  14. A HYBRID SYSTEM OF EVALUATING IRON WEIGHT ON ITS RELEASE FROM BLAST FURNACE

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    Glebova, E.S.

    2016-05-01

    Full Text Available The article suggests a method for evaluating the weight of iron obtained from a specific release from a blast furnace under parallel production in a set of furnaces. The method is based on a hybrid approach using the weighing results of mixer carrier on the scales, a system of operational control of the process of pouring iron out into the mixer and the automated system of rolling stock registration. The proposed method can improve the speed, accuracy and reliability of evaluating the weight of iron obtained from a specific release of the blast furnace.

  15. Kinetics of iron release from transferrin bound to the transferrin receptor at endosomal pH.

    Science.gov (United States)

    Steere, Ashley N; Byrne, Shaina L; Chasteen, N Dennis; Mason, Anne B

    2012-03-01

    Human serum transferrin (hTF) is a bilobal glycoprotein that reversibly binds Fe(3+) and delivers it to cells by the process of receptor-mediated endocytosis. Despite decades of research, the precise events resulting in iron release from each lobe of hTF within the endosome have not been fully delineated. We provide an overview of the kinetics of iron release from hTF±the transferrin receptor (TFR) at endosomal pH (5.6). A critical evaluation of the array of biophysical techniques used to determine accurate rate constants is provided. Delivery of Fe(3+)to actively dividing cells by hTF is essential; too much or too little Fe(3+) directly impacts the well-being of an individual. Because the interaction of hTF with the TFR controls iron distribution in the body, an understanding of this process at the molecular level is essential. Not only does TFR direct the delivery of iron to the cell through the binding of hTF, kinetic data demonstrate that it also modulates iron release from the N- and C-lobes of hTF. Specifically, the TFR balances the rate of iron release from each lobe, resulting in efficient Fe(3+) release within a physiologically relevant time frame. This article is part of a Special Issue entitled Molecular Mechanisms of Iron Transport and Disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Iron metabolism in BeWo chorion carcinoma cells. Transferrin-mediated uptake and release of iron.

    Science.gov (United States)

    van der Ende, A; du Maine, A; Simmons, C F; Schwartz, A L; Strous, G J

    1987-06-25

    Growing human choriocarcinoma BeWo b24 cells contain 1.5 X 10(6) functional cell surface transferrin binding sites and 2.0 X 10(6) intracellular binding sites. These cells rapidly accumulate iron at a rate of 360,000 iron atoms/min/cell. During iron uptake the transferrin and its receptor recycle at least each 19 min. The accumulated iron is released from the BeWo cells at a considerable rate. The time required to release 50% of previously accumulated iron into the extracellular medium is 30 h. This release process is cell line-specific as HeLa cells release very little if any iron. The release of iron by BeWo cells is stimulated by exogenous chelators such as apotransferrin, diethylenetriaminepenta-acetic acid, desferral, and apolactoferrin. The time required to release 50% of the previously accumulated iron into medium supplemented with chelator is 15 h. In the absence of added chelators iron is released as a low molecular weight complex, whereas in the presence of chelator the iron is found complexed to the chelator. Uptake of iron is inhibited by 250 microM primaquine or 2.5 microM monensin. However, the release of iron is not inhibited by these drugs. Intracellular iron is stored bound to ferritin. A model for the release of iron by BeWo cells and its implication for transplacental iron transport is discussed.

  17. Controlling Iron Release in Drinking Water Distribution System Fed with Desalinated Seawater%淡化海水并网供水的管网铁释放控制技术研究

    Institute of Scientific and Technical Information of China (English)

    米子龙; 张晓健; 陈超; 陈沛君; 杜嘉丹

    2012-01-01

    Desalinated seawater, with strong corrosiveness, would possibly lead to serious iron release phenomenon and " red water" problem when fed into municipal drinking water distribution systems. To control iron release in the drinking water distribution system, the effect of adjusting pH, alkalinity, hardness and adding inhibitor were investigated in pipe section reactors which were designed to simulate pipe network conditions. The results found that the iron release decreased significantly as increasing pH, alkalinity, hardness and adding polyphosphate inhibitor. Meanwhile, the necessary water quality conditions for controlling iron release were established. The iron control criteria specify that pH, alkalinity and hardness should be more than 7. 70, 80 mg/L and 80 mg/L respectively. 0. 25 to 0. 50 mg/L of polyphosphate inhibitor should be added if necessary.%淡化海水由于具有较强的侵蚀性,并网供水后会对既有供水管网造成严重的铁释放现象和黄水问题.为了有效地控制管网铁释放,利用管段模拟反应器,定量研究了调节pH值、碱度、硬度和投加缓蚀剂对管网铁释放的控制效果.研究发现,提高pH值、增加碱度和硬度、投加磷酸盐缓蚀剂均可使淡化海水并网供水后造成的管网铁释放量明显降低.由此初步确定了控制淡化海水进入供水管网造成铁过量释放所需满足的水质条件为:管网水的pH值在7.70以上,碱度>80 mg/L,硬度>80 mg/L;必要时可选择投加0.25 ~0.50 mg/L的聚磷酸盐缓蚀剂.

  18. Assessing iron dynamics in the release from a stratified reservoir

    Science.gov (United States)

    Ashby, S.L.; Faulkner, S.P.; Gambrell, R.P.; Smith, B.A.

    2004-01-01

    Field and laboratory studies were conducted to describe the fate of total, dissolved, and ferrous (Fe2.) iron in the release from a stratified reservoir with an anoxic hypolimnion. Concentrations of total iron in the tail water indicated a first order removal process during a low flow release (0.6 m3sec1), yet negligible loss was observed during a period of increased discharge (2.8 m 3 sec-1). Dissolved and ferrous iron concentrations in the tailwater were highly variable during both release regimes and did not follow responses based on theoretical predictions. Ferrous iron concentrations in unfiltered samples were consistently greater than concentrations observed in samples filtered separately through 0.4, 0.2, and 0.1 ??m filters. Total iron removal in laboratory studies followed first order kinetics, but was twice that rate (0.077 mg.L-1 .hr 1) observed during low flow discharge in the tailwater (0.036 mg. L1 .hr1). Dissolved and ferrous iron losses in laboratory studies were rapid (???75% in the first 15 minutes and 95% within 1 hour), followed theoretical predictions, and were much faster than observations in the tailwater (???30% within the first hour). The presence of particulate forms of ferrous iron in the field and differences in removal rates observed in field and laboratory studies indicate a need for improved field assessment techniques and consideration of complexation reactions when assessing the dynamics of iron in reservoir releases and downstream impacts as a result of operation regimes. ?? Copyright by the North American Lake Management Society 2004.

  19. Workload Control with Continuous Release

    NARCIS (Netherlands)

    Phan, B. S. Nguyen; Land, M. J.; Gaalman, G. J. C.

    2009-01-01

    Workload Control (WLC) is a production planning and control concept which is suitable for the needs of make-to-order job shops. Release decisions based on the workload norms form the core of the concept. This paper develops continuous time WLC release variants and investigates their due date

  20. Birth control - slow release methods

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/007555.htm Birth control - slow release methods To use the sharing features on this page, please enable JavaScript. Certain birth control methods contain man-made forms of hormones. These ...

  1. Optogenetic control of ATP release

    Science.gov (United States)

    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.

  2. Controlled release from recombinant polymers.

    Science.gov (United States)

    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.

  3. Magnetically stimulated ciprofloxacin release from polymeric microspheres entrapping iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Sirivisoot S

    2015-07-01

    Full Text Available Sirinrath Sirivisoot,1 Benjamin S Harrison2 1Biological Engineering Program, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok, Thailand; 2Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Wake Forest University Health Sciences, Winston-Salem, NC, USA Abstract: To extend the external control capability of drug release, iron oxide nanoparticles (NPs encapsulated into polymeric microspheres were used as magnetic media to stimulate drug release using an alternating magnetic field. Chemically synthesized iron oxide NPs, maghemite or hematite, and the antibiotic ciprofloxacin were encapsulated together within polycaprolactone microspheres. The polycaprolactone microspheres entrapping ciprofloxacin and magnetic NPs could be triggered for immediate drug release by magnetic stimulation at a maximum value of 40%. Moreover, the microspheres were cytocompatible with fibroblasts in vitro with a cell viability percentage of more than 100% relative to a nontreated control after 24 hours of culture. Macrophage cell cultures showed no signs of increased inflammatory responses after in vitro incubation for 56 hours. Treatment of Staphylococcus aureus with the magnetic microspheres under an alternating (isolating magnetic field increased bacterial inhibition further after 2 days and 5 days in a broth inhibition assay. The findings of the present study indicate that iron oxide NPs, maghemite and hematite, can be used as media for stimulation by an external magnetic energy to activate immediate drug release. Keywords: antibacterial, maghemite, hematite, Staphylococcus aureus

  4. Potential of Phytase-Mediated Iron Release from Cereal-Based Foods: A Quantitative View

    Directory of Open Access Journals (Sweden)

    Anne S. Meyer

    2013-08-01

    Full Text Available The major part of iron present in plant foods such as cereals is largely unavailable for direct absorption in humans due to complexation with the negatively charged phosphate groups of phytate (myo-inositol (1,2,3,4,5,6-hexakisphosphate. Human biology has not evolved an efficient mechanism to naturally release iron from iron phytate complexes. This narrative review will evaluate the quantitative significance of phytase-catalysed iron release from cereal foods. In vivo studies have shown how addition of microbially derived phytases to cereal-based foods has produced increased iron absorption via enzyme-catalysed dephosphorylation of phytate, indicating the potential of this strategy for preventing and treating iron deficiency anaemia. Despite the immense promise of this strategy and the prevalence of iron deficiency worldwide, the number of human studies elucidating the significance of phytase-mediated improvements in iron absorption and ultimately in iron status in particularly vulnerable groups is still low. A more detailed understanding of (1 the uptake mechanism for iron released from partially dephosphorylated phytate chelates, (2 the affinity of microbially derived phytases towards insoluble iron phytate complexes, and (3 the extent of phytate dephosphorylation required for iron release from inositol phosphates is warranted. Phytase-mediated iron release can improve iron absorption from plant foods. There is a need for development of innovative strategies to obtain better effects.

  5. Phosphorus release from phosphate rock and iron phosphate by low-molecular-weight organic acids

    Institute of Scientific and Technical Information of China (English)

    XU Ren-kou; ZHU Yong-guan; David Chittleborough

    2004-01-01

    Low-molecular-weight(LMW) organic acids widely exist in soils, particularly in the rhizosphere. A series of batch experiments were carried out to investigate the phosphorus release from rock phosphate and iron phosphate by Iow-molecular-weight organic acids.Results showed that citric acid had the highest capacity to solubilize P from both rock and iron phosphate. P solubilization from rock phosphate and iron phosphate resulted in net proton consumption. P release from rock phosphate was positively correlated with the pKa values. P release from iron phosphate was positively correlated with Fe-organic acid stability constants except for aromatic acids, but was not correlated with PKa. Increase in the concentrations of organic acids enhanced P solubilization from both rock and iron phosphate almost linearrly. Addition of phenolic compounds further increased the P release from iron phosphate. Initial solution pH had much more substantial effect on P release from rock phosphate than from iron phosphate.

  6. [Control of iron deficiency in developing countries].

    Science.gov (United States)

    Berger, Jacques; Dillon, Jean-Claude

    2002-01-01

    Iron deficiency is the most prevalent nutritional disorder worldwide, especially in developing countries. It occurs when iron absorption cannot compensate iron requirements and losses. Requirements are especially high in pregnant women, infants, young children and adolescents who run a higher risk of being iron-deficient. In developing countries, the main cause of iron deficiency is the low iron bioavailability of the diet. The consequences of iron deficiency are many and serious, affecting not only individuals' health but also the development of societies and countries. The prevention and the control of iron deficiency and anemia in all groups of a population with different iron requirements imply to coordinate different interventions. Iron fortification of staple foods or condiments directed to the whole population is a sustainable and low cost-effective approach. However, at some periods of life, especially during pregnancy and in children from the age of 6 months, iron requirements are high. For pregnant women, the current approach favours the daily iron-folate supplementation during pregnancy but the results in terms of public health are disappointing. The preventive weekly iron-folate supplementation of women during their reproductive life, whose efficacy is recognized, offers a promising alternative; its impact in terms of public health is under current evaluation. For infants and young children, iron fortification of complementary food is effective but this food is generally imported and economically inaccessible to populations with limited resources. The production, by small private units from local products, of complementary foods of low viscosity, good nutritional quality, fortified with vitamins and minerals, and of low cost is at hand in several countries. When complementary foods are not available, the preventive iron supplementation from 6 to 18 months of age has to be advised. This approach should be strengthened by the advantages of the weekly

  7. Modelling and simulations of controlled release fertilizer

    Science.gov (United States)

    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.

  8. Magnetothermal release of payload from iron oxide/silica drug delivery agents

    Science.gov (United States)

    Luong, T. T.; Knoppe, S.; Bloemen, M.; Brullot, W.; Strobbe, R.; Locquet, J.-P.; Verbiest, T.

    2016-10-01

    The release of covalently bound Rhodamine B from iron oxide/mesoporous silica core/shell nanoparticles under magnetically induced heating was studied. The system acts as a model to study drug delivery and payload release under magnetothermal heating.

  9. CONTROLLING ODOROUS EMISSIONS FROM IRON FOUNDRIES

    Science.gov (United States)

    The report discusses the control of odorous emissions from iron foundries. he main process sources of odors in iron foundries are mold and core making, casting, and sand shakeout. he odors are usually caused by chemicals, which may be present as binders and other additives to the...

  10. Influence of Redox Potential on Arsenic Release from Soil in the Presence of Iron Oxyhydroxide

    OpenAIRE

    Nguyen, Kim Phuong; Itoi, Ryuichi; Yamashiro, Rie

    2008-01-01

    This paper presents the effects redox potential on the mobility of arsenic (As) from soil in the presence of iron oxyhydroxide with soil column experiment. The mineralogical characteristics of the soil were identified by acid digestion, X-ray diffraction and sequential extraction methods. Approximately 60% of the total arsenic was associated with iron oxyhydroxides and iron oxides. Redox potential played a significant role on the onset of arsenic and iron release from the soil. The arsenic an...

  11. Control of bacterial iron homeostasis by manganese

    Science.gov (United States)

    Puri, Sumant; Hohle, Thomas H.; O'Brian, Mark R.

    2010-01-01

    Perception and response to nutritional iron availability by bacteria are essential to control cellular iron homeostasis. The Irr protein from Bradyrhizobium japonicum senses iron through the status of heme biosynthesis to globally regulate iron-dependent gene expression. Heme binds directly to Irr to trigger its degradation. Here, we show that severe manganese limitation created by growth of a Mn2+ transport mutant in manganese-limited media resulted in a cellular iron deficiency. In wild-type cells, Irr levels were attenuated under manganese limitation, resulting in reduced promoter occupancy of target genes and altered iron-dependent gene expression. Irr levels were high regardless of manganese availability in a heme-deficient mutant, indicating that manganese normally affects heme-dependent degradation of Irr. Manganese altered the secondary structure of Irr in vitro and inhibited binding of heme to the protein. We propose that manganese limitation destabilizes Irr under low-iron conditions by lowering the threshold of heme that can trigger Irr degradation. The findings implicate a mechanism for the control of iron homeostasis by manganese in a bacterium. PMID:20498065

  12. Understanding the Role of Particulate Iron in Lead Release to Drinking Water.

    Science.gov (United States)

    Trueman, Benjamin F; Gagnon, Graham A

    2016-09-01

    Lead service lines (LSLs) are a major source of drinking water lead, and high iron levels are frequently observed along with elevated lead release. A model distribution system, dosed with orthophosphate, was used to evaluate the effect of corroded iron distribution mains on lead release from recovered LSLs. Lead release was higher by 96 μg L(-1), on average, from LSLs supplied by corroded iron compared to the inert reference material (PVC). This effect may be explained by deposition of semiconducting iron oxide particles within LSLs. When galvanic cells with lead and magnetite (Fe3O4) electrodes were short-circuited, lead release increased 8-fold and a current averaging 26 μA was observed. In effluent from LSLs with an upstream iron main, colloidal lead and iron occurred in the same size fraction-possibly due to release of colloidal particles from LSL corrosion scale enriched with iron. Under these circumstances, high molecular weight (>669 kDa) (208)Pb and (56)Fe elution profiles, observed via size-exclusion chromatography, were highly correlated (average R(2) = 0.97). Increasing orthophosphate from 0.5 to 1.0 mg L(-1) (as PO4(3-)) accompanied an average reduction in lead release of 6 μg L(-1) month(-1) but did not significantly reduce the effect of an upstream iron main.

  13. Potential of phytase-mediated iron release from cereal-based foods: a quantitative view

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Tetens, Inge; Meyer, Anne S.

    2013-01-01

    The major part of iron present in plant foods such as cereals is largely unavailable for direct absorption in humans due to complexation with the negatively charged phosphate groups of phytate (myo-inositol (1,2,3,4,5,6)-hexakisphosphate). Human biology has not evolved an efficient mechanism...... to naturally release iron from iron phytate complexes. This narrative review will evaluate the quantitative significance of phytase-catalysed iron release from cereal foods. In vivo studies have shown how addition of microbially derived phytases to cereal-based foods has produced increased iron absorption via...... enzyme-catalysed dephosphorylation of phytate, indicating the potential of this strategy for preventing and treating iron deficiency anaemia. Despite the immense promise of this strategy and the prevalence of iron deficiency worldwide, the number of human studies elucidating the significance of phytase...

  14. How the binding of human transferrin primes the transferrin receptor potentiating iron release at endosomal pH.

    Science.gov (United States)

    Eckenroth, Brian E; Steere, Ashley N; Chasteen, N Dennis; Everse, Stephen J; Mason, Anne B

    2011-08-09

    Delivery of iron to cells requires binding of two iron-containing human transferrin (hTF) molecules to the specific homodimeric transferrin receptor (TFR) on the cell surface. Through receptor-mediated endocytosis involving lower pH, salt, and an unidentified chelator, iron is rapidly released from hTF within the endosome. The crystal structure of a monoferric N-lobe hTF/TFR complex (3.22-Å resolution) features two binding motifs in the N lobe and one in the C lobe of hTF. Binding of Fe(N)hTF induces global and site-specific conformational changes within the TFR ectodomain. Specifically, movements at the TFR dimer interface appear to prime the TFR to undergo pH-induced movements that alter the hTF/TFR interaction. Iron release from each lobe then occurs by distinctly different mechanisms: Binding of His349 to the TFR (strengthened by protonation at low pH) controls iron release from the C lobe, whereas displacement of one N-lobe binding motif, in concert with the action of the dilysine trigger, elicits iron release from the N lobe. One binding motif in each lobe remains attached to the same α-helix in the TFR throughout the endocytic cycle. Collectively, the structure elucidates how the TFR accelerates iron release from the C lobe, slows it from the N lobe, and stabilizes binding of apohTF for return to the cell surface. Importantly, this structure provides new targets for mutagenesis studies to further understand and define this system.

  15. Asynchronous Reductive Release of Iron and Organic Carbon from Hematite-Humic Acid Complexes

    Science.gov (United States)

    Adhikari, D.; Poulson, S.; Sumaila, S.; Dynes, J.; McBeth, J. M.; Yang, Y.

    2015-12-01

    Association with solid-phase iron plays an important role in the accumulation and stabilization of soil organic matter (SOM). Ferric minerals are subject to redox reactions, which can compromise the stability of iron-bound SOM. To date, there is limited information available concerning the fate of iron-bound SOM during redox reactions. In this study, we investigated the release kinetics of hematite-bound organic carbon (OC) during the abiotic reduction of hematite-humic acid (HA) complexes by dithionite, as an analog for the fate of iron-bound SOM in natural redox reactions. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to examine the ratio of the aromatic, phenolic and carboxylic/imide functional groups of the adsorbed OC before and after reduction. Our results indicate that the reductive release of iron obeyed first-order kinetics with release rate constants of 6.67×10-3 to 13.0×10-3 min-1. The iron-bound OC was released rapidly during the initial stage with release rate constants of 0.011 to 1.49 min-1, and then became stable with residual fractions of 4.6% to 58.2% between 120 and 240 min. The release rate of aromatic OC was much faster than for the non-aromatic fraction of HA, and 90% of aromatic OC was released within the first hour for most samples. The more rapid release of aromatic OC was attributed to its potential distribution on the outer layer because of steric effects and the possible reduction of quinoids. Our findings show that in the reductive reaction the mobilization of iron-bound organic carbon was asynchronous with the reduction of iron, and aromatic carbon was released more readily than other organic components. This study illustrates the importance of evaluating the stability of iron-bound SOM, especially under aerobic-anaerobic transition conditions.

  16. Recent patents in flavor controlled release.

    Science.gov (United States)

    Feng, Tao; Xiao, Zuobing; Tian, Huaixiang

    2010-06-01

    In recent years, considerable effort has been directed toward the preparation of flavoring materials specifically, flavor materials have been sought that provide greater flavor intensity coupled with controlled flavor release for long periods of time. Here, some recent patents related to controlled flavor release are reviewed from the angle of its application field, its mechanism and its determination method. It is found that controlled flavor release often depends not only on materials' chemical and physical properties, such as melting point, solution properties and so on, but also on flavors' chemical and physical properties, such as diffusion capacity, its stability in different media etc. Meanwhile, flavor release is also controlled by an electric reducing device according to the flavor generation condition. It might be also known that flavor release rate could be determined by using a purge-and-trap/gas chromatographic procedure. In future, it's necessary to use mathematical model to study the kinetic behavior of controlled flavor release.

  17. Effects of pore topology and iron oxide core on doxorubicin loading and release from mesoporous silica nanoparticles

    Science.gov (United States)

    Ronhovde, Cicily J.; Baer, John; Larsen, Sarah C.

    2017-06-01

    Mesoporous silica nanoparticles (MSNs) have a network of pores that give rise to extremely high specific surface areas, making them attractive materials for applications such as adsorption and drug delivery. The pore topology can be readily tuned to achieve a variety of structures such as the hexagonally ordered Mobil Crystalline Material 41 (MCM-41) and the disordered "wormhole" (WO) mesoporous silica (MS) structure. In this work, the effects of pore topology and iron oxide core on doxorubicin loading and release were investigated using MSNs with pore diameters of approximately 3 nm and sub-100 nm particle diameters. The nanoparticles were loaded with doxorubicin, and the drug release into phosphate-buffered saline (PBS, 10 mM, pH 7.4) at 37 °C was monitored by fluorescence spectroscopy. The release profiles were fit using the Peppas model. The results indicated diffusion-controlled release for all samples. Statistically significant differences were observed in the kinetic host-guest parameters for each sample due to the different pore topologies and the inclusion of an iron oxide core. Applying a static magnetic field to the iron oxide core WO-MS shell materials did not have a significant impact on the doxorubicin release. This is the first time that the effects of pore topology and iron oxide core have been isolated from pore diameter and particle size for these materials.

  18. Multimicronutrient Slow-Release Fertilizer of Zinc, Iron, Manganese, and Copper

    Directory of Open Access Journals (Sweden)

    Siladitya Bandyopadhyay

    2014-01-01

    Full Text Available The process for the production of a slow-release micronutrient fertilizer is described. The compound contains zinc, iron, manganese, and copper as micronutrients and is produced by polymerizing a system containing phosphoric acid, zinc oxide, hematite, pyrolusite, copper sulfate, and magnesium oxide followed by neutralization of the polyphosphate chain with ammonium hydroxide. Changes in temperature, density, and viscosity of the reaction system during polymerization were studied. Reaction kinetics was studied at three different temperatures. Rate curves revealed a multistage process with essentially linear rates at each stage. Thus, each stage displayed zero order kinetics. The product was crystalline and revealed ordering of P-O-P chains. It had low solubility in water but high solubility in 0.33 M citric acid and 0.005 M DTPA. Three different field trials showed significant yield increments using the slow-release micronutrient fertilizer compared to the conventional micronutrients. Yield increments in rice were in the range of 10–55% over control (with no micronutrient and up to 17% over the conventional micronutrient fertilizers. There were significant increases in total uptake of zinc, iron, and manganese in the grain. Slow-release fertilizers also produced significant yield increases in potato as well as significant increase in vitamin C content of the tuber.

  19. Stimuli responsive nanomaterials for controlled release applications

    KAUST Repository

    Li, Song

    2012-01-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. Coupled with excellent biocompatibility profiles, various nanomaterials have showed great promise for biomedical applications. Stimuli-responsive nanomaterials guarantee the controlled release of cargo to a given location, at a specific time, and with an accurate amount. In this review, we have combined the major stimuli that are currently used to achieve the ultimate goal of controlled and targeted release by "smart" nanomaterials. The most heavily explored strategies include (1) pH, (2) enzymes, (3) redox, (4) magnetic, and (5) light-triggered release.

  20. Control of Cast Iron Microstructure

    Science.gov (United States)

    Graham, J.; Lillybeck, N.; Franco, N.; Stefanescu, D. M.

    1985-01-01

    The use of microgravity for industrial research in the processing of cast iron was investigated. Solidification experiments were conducted using the KC-135 and F-104 aircraft, and an experiment plan was developed for follow-on experiments using the Shuttle. Three areas of interest are identified: (1) measurement of thermophysical properties in the melt; (2) understanding of the relative roles of homogeneous nucleation, grain multiplication, and innocultants in forming the microstructure; and (3) exploring the possibility of obtaining an aligned graphite structure in hypereutectic Fe, Ni, and Co.

  1. Lignin based controlled release coatings

    NARCIS (Netherlands)

    Mulder, W.J.; Gosselink, R.J.A.; Vingerhoeds, M.H.; Harmsen, P.F.H.; Eastham, D.

    2011-01-01

    Urea is a commonly used fertilizer. Due to its high water-solubility, misuse easily leads to excess nitrogen levels in the soil. The aim of this research was to develop an economically feasible and biodegradable slow-release coating for urea. For this purpose, lignin was selected as coating material

  2. Lignin based controlled release coatings

    NARCIS (Netherlands)

    Mulder, W.J.; Gosselink, R.J.A.; Vingerhoeds, M.H.; Harmsen, P.F.H.; Eastham, D.

    2011-01-01

    Urea is a commonly used fertilizer. Due to its high water-solubility, misuse easily leads to excess nitrogen levels in the soil. The aim of this research was to develop an economically feasible and biodegradable slow-release coating for urea. For this purpose, lignin was selected as coating

  3. Lignin based controlled release coatings

    NARCIS (Netherlands)

    Mulder, W.J.; Gosselink, R.J.A.; Vingerhoeds, M.H.; Harmsen, P.F.H.; Eastham, D.

    2011-01-01

    Urea is a commonly used fertilizer. Due to its high water-solubility, misuse easily leads to excess nitrogen levels in the soil. The aim of this research was to develop an economically feasible and biodegradable slow-release coating for urea. For this purpose, lignin was selected as coating material

  4. Role of iron and aluminum coagulant metal residuals and lead release from drinking water pipe materials.

    Science.gov (United States)

    Knowles, Alisha D; Nguyen, Caroline K; Edwards, Marc A; Stoddart, Amina; McIlwain, Brad; Gagnon, Graham A

    2015-01-01

    Bench-scale experiments investigated the role of iron and aluminum residuals in lead release in a low alkalinity and high (> 0.5) chloride-to-sulfate mass ratio (CSMR) in water. Lead leaching was examined for two lead-bearing plumbing materials, including harvested lead pipe and new lead: tin solder, after exposure to water with simulated aluminum sulfate, polyaluminum chloride and ferric sulfate coagulation treatments with 1-25-μM levels of iron or aluminum residuals in the water. The release of lead from systems with harvested lead pipe was highly correlated with levels of residual aluminum or iron present in samples (R(2) = 0.66-0.88), consistent with sorption of lead onto the aluminum and iron hydroxides during stagnation. The results indicate that aluminum and iron coagulant residuals, at levels complying with recommended guidelines, can sometimes play a significant role in lead mobilization from premise plumbing.

  5. Correlation between surface physicochemical properties and the release of iron from stainless steel AISI 304 in biological media.

    Science.gov (United States)

    Hedberg, Yolanda; Karlsson, Maria-Elisa; Blomberg, Eva; Odnevall Wallinder, Inger; Hedberg, Jonas

    2014-10-01

    Stainless steel is widely used in biological environments, for example as implant material or in food applications, where adsorption-controlled ligand-induced metal release is of importance from a corrosion, health, and food safety perspective. The objective of this study was to elucidate potential correlations between surface energy and wettability of stainless steel surfaces and the release of iron in complexing biological media. This was accomplished by studying changes in surface energies calculated from contact angle measurements, surface oxide composition (X-ray photoelectron spectroscopy), and released iron (graphite furnace atomic absorption spectroscopy) for stainless steel grade AISI 304 immersed in fluids containing bovine serum albumin or citric acid, and non-complexing fluids such as NaCl, NaOH, and HNO3. It was shown that the surface wettability and polar surface energy components were all influenced by adventitious atmospheric carbon (surface contamination of low molecular weight), rather than differences in surface oxide composition in non-complexing solutions. Adsorption of both BSA and citrate, which resulted in ligand-induced metal release, strongly influenced the wettability and the surface energy, and correlated well with the measured released amount of iron.

  6. Release Control of Dye from Agar Ball

    OpenAIRE

    板屋, 智之; 山村, 俊貴; 唐澤, 有太朗

    2013-01-01

    Agar is a special product of Nagano prefecture. To utilize agar gel as adsorbing or releasing material of dyes or drugs, spherical agar gel “agar ball” was prepared by dropping aqueous agar solution into salad oil. And releasing behavior of a dye (rhodamine B) from agar ball was studied. The dye is released easily from agar ball, but the release can be controlled by hybiridazation of agar and galatin. In addition, it was found that agar ball could extract the dye from oil phase containing the...

  7. Endosome-mitochondria interactions are modulated by iron release from transferrin.

    Science.gov (United States)

    Das, Anupam; Nag, Sagarika; Mason, Anne B; Barroso, Margarida M

    2016-09-26

    Transient "kiss and run" interactions between endosomes containing iron-bound transferrin (Tf) and mitochondria have been shown to facilitate direct iron transfer in erythroid cells. In this study, we used superresolution three-dimensional (3D) direct stochastic optical reconstruction microscopy to show that Tf-containing endosomes directly interact with mitochondria in epithelial cells. We used live-cell time-lapse fluorescence microscopy, followed by 3D rendering, object tracking, and a distance transformation algorithm, to track Tf-endosomes and characterize the dynamics of their interactions with mitochondria. Quenching of iron sensor RDA-labeled mitochondria confirmed functional iron transfer by an interacting Tf-endosome. The motility of Tf-endosomes is significantly reduced upon interaction with mitochondria. To further assess the functional role of iron in the ability of Tf-endosomes to interact with mitochondria, we blocked endosomal iron release by using a Tf K206E/K534A mutant. Blocking intraendosomal iron release led to significantly increased motility of Tf-endosomes and increased duration of endosome-mitochondria interactions. Thus, intraendosomal iron regulates the kinetics of the interactions between Tf-containing endosomes and mitochondria in epithelial cells. © 2016 Das et al.

  8. Effects of sulfate on heavy metal release from iron corrosion scales in drinking water distribution system.

    Science.gov (United States)

    Sun, Huifang; Shi, Baoyou; Yang, Fan; Wang, Dongsheng

    2017-05-01

    Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R(2) > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe3O4) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe3O4. The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe6(OH)12CO3 content under higher sulfate concentrations.

  9. Pb-Free Soldering Iron Temperature Controller

    Science.gov (United States)

    Hamane, Hiroto; Wajima, Kenji; Hayashi, Yoichi; Komiyama, Eiichi; Tachibana, Toshiaki; Miyazaki, Kazuyoshi

    Recently, much importance has been attached to the environmental problem. The content of two directives to better control the management of waste electronic equipment was approved. The two directives are the Waste from Electrical and Electronic Equipment (WEEE) and the Restriction of Hazardous Substances (RoHS). These set phase-out dates for the use of lead materials contained in electronic products. Increasingly, attention is focusing on the potential use of Pb-free soldering in electronics manufacturing. It should be noted that many of the current solding irons are not suitable for Pb-free technology, due to the inferior wetting ability of Pb-free alloys compared with SnPb solder pastes. This paper presents a Pb-free soldering iron temperature controller using an embedded micro-processor with a low memory capacity.

  10. Cable Bacteria Control Iron-Phosphorus Dynamics in Sediments of a Coastal Hypoxic Basin.

    Science.gov (United States)

    Sulu-Gambari, Fatimah; Seitaj, Dorina; Meysman, Filip J R; Schauer, Regina; Polerecky, Lubos; Slomp, Caroline P

    2016-02-01

    Phosphorus is an essential nutrient for life. The release of phosphorus from sediments is critical in sustaining phytoplankton growth in many aquatic systems and is pivotal to eutrophication and the development of bottom water hypoxia. Conventionally, sediment phosphorus release is thought to be controlled by changes in iron oxide reduction driven by variations in external environmental factors, such as organic matter input and bottom water oxygen. Here, we show that internal shifts in microbial communities, and specifically the population dynamics of cable bacteria, can also induce strong seasonality in sedimentary iron-phosphorus dynamics. Field observations in a seasonally hypoxic coastal basin demonstrate that the long-range electrogenic metabolism of cable bacteria leads to a dissolution of iron sulfides in winter and spring. Subsequent oxidation of the mobilized ferrous iron with manganese oxides results in a large stock of iron-oxide-bound phosphorus below the oxic zone. In summer, when bottom water hypoxia develops and cable bacteria are undetectable, the phosphorus associated with these iron oxides is released, strongly increasing phosphorus availability in the water column. Future research should elucidate whether formation of iron-oxide-bound phosphorus driven by cable bacteria, as observed in this study, contributes to the seasonality in iron-phosphorus cycling in aquatic sediments worldwide.

  11. The impact of ocean deoxygenation on iron release from continental margin sediments

    OpenAIRE

    Scholz, Florian; McManus, James; Mix, Alan C; Hensen, Christian; Schneider, Ralph

    2014-01-01

    In the oceans’ high-nitrate–low-chlorophyll regions, such as the Peru/Humboldt Current system and the adjacent eastern equatorial Pacific1, primary productivity is limited by the micronutrient iron. Within the Peruvian upwelling area, bioavailable iron is released from the reducing continental margin sediments2. The magnitude of this seafloor source could change with fluctuations in the extension or intensity of the oxygen minimum zones3, 4. Here we show that measurements of molybdenum, urani...

  12. Ligand-based reduction of CO2 and release of CO on iron(II).

    Science.gov (United States)

    Thammavongsy, Zachary; Seda, Takele; Zakharov, Lev N; Kaminsky, Werner; Gilbertson, John D

    2012-09-01

    A synthetic cycle for the CO(2)-to-CO conversion (with subsequent release of CO) based on iron(II), a redox-active pydridinediimine ligand (PDI), and an O-atom acceptor is reported. This conversion is a passive-type ligand-based reduction, where the electrons for the CO(2) conversion are supplied by the reduced PDI ligand and the ferrous state of the iron is conserved.

  13. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    Science.gov (United States)

    Yassine, Omar; Zaher, Amir; Li, Er Qiang; Alfadhel, Ahmed; Perez, Jose E.; Kavaldzhiev, Mincho; Contreras, Maria F.; Thoroddsen, Sigurdur T.; Khashab, Niveen M.; Kosel, Jurgen

    2016-06-01

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

  14. Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications

    KAUST Repository

    Yassine, Omar

    2016-06-23

    Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

  15. Local control of striatal dopamine release

    Directory of Open Access Journals (Sweden)

    Roger eCachope

    2014-05-01

    Full Text Available The mesolimbic and nigrostriatal dopamine (DA systems play a key role in the physiology of reward seeking, motivation and motor control. Importantly, they are also involved in the pathophysiology of Parkinson’s and Huntington’s disease, schizophrenia and addiction. Control of DA release in the striatum is tightly linked to firing of DA neurons in the ventral tegmental area (VTA and the substantia nigra (SN. However, local influences in the striatum affect release by exerting their action directly on axon terminals. For example, endogenous glutamatergic and cholinergic activity is sufficient to trigger striatal DA release independently of cell body firing. Recent developments involving genetic manipulation, pharmacological selectivity or selective stimulation have allowed for better characterization of these phenomena. Such termino-terminal forms of control of DA release transform considerably our understanding of the mesolimbic and nigrostriatal systems, and have strong implications as potential mechanisms to modify impaired control of DA release in the diseased brain. Here, we review these and related mechanisms and their implications in the physiology of ascending DA systems.

  16. Electrosprayed nanoparticle delivery system for controlled release

    Energy Technology Data Exchange (ETDEWEB)

    Eltayeb, Megdi, E-mail: megdi.eltayeb@sustech.edu [Department of Biomedical Engineering, Sudan University of Science and Technology, PO Box 407, Khartoum (Sudan); Stride, Eleanor, E-mail: eleanor.stride@eng.ox.ac.uk [Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Old Road Campus Research Building, Headington OX3 7DQ (United Kingdom); Edirisinghe, Mohan, E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Harker, Anthony, E-mail: a.harker@ucl.ac.uk [London Centre for Nanotechnology, Gordon Street, London WC1H 0AH (United Kingdom); Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2016-09-01

    This study utilises an electrohydrodynamic technique to prepare core-shell lipid nanoparticles with a tunable size and high active ingredient loading capacity, encapsulation efficiency and controlled release. Using stearic acid and ethylvanillin as model shell and active ingredients respectively, we identify the processing conditions and ratios of lipid:ethylvanillin required to form nanoparticles. Nanoparticles with a mean size ranging from 60 to 70 nm at the rate of 1.37 × 10{sup 9} nanoparticles per minute were prepared with different lipid:ethylvanillin ratios. The polydispersity index was ≈ 21% and the encapsulation efficiency ≈ 70%. It was found that the rate of ethylvanillin release was a function of the nanoparticle size, and lipid:ethylvanillin ratio. The internal structure of the lipid nanoparticles was studied by transmission electron microscopy which confirmed that the ethylvanillin was encapsulated within a stearic acid shell. Fourier transform infrared spectroscopy analysis indicated that the ethylvanillin had not been affected. Extensive analysis of the release of ethylvanillin was performed using several existing models and a new diffusive release model incorporating a tanh function. The results were consistent with a core-shell structure. - Highlights: • Electrohydrodynamic spraying is used to produce lipid-coated nanoparticles. • A new model is proposed for the release rates of active components from nanoparticles. • The technique has potential applications in food science and medicine. • Electrohydrodynamic processing controlled release lipid nanoparticles.

  17. Formation and Release Behavior of Iron Corrosion Products under the Influence of Bacterial Communities in a Simulated Water Distribution System

    Science.gov (United States)

    Understanding the effects of biofilm on the iron corrosion, iron release and associated corrosion by-products is critical for maintaining the water quality and the integrity of drinking water distribution system (DWDS). In this work, iron corrosion experiments under sterilized a...

  18. Directly observed iron supplementation for control of iron deficiency anemia

    Directory of Open Access Journals (Sweden)

    Mohan Bairwa

    2017-01-01

    Full Text Available Anemia is major public health problem affecting 1.6 billion people worldwide. The poor compliance of iron supplementation remains main contributor for high prevalence of anemia. The current paper reviewed the effectiveness of direct observation of oral iron supplementation on anemia. A systematic search was performed through electronic databases and local libraries. Search strategies used subject headings and key words “directly observed” and “iron supplementation.” Searches were sought through April 2014. A total of 14 articles were included in the study. Findings were presented in three categories. First, all of those reported an improvement in compliance of iron supplementation. Second, reduction in the prevalence of anemia was reported by all and third, all except one reported increased blood hemoglobin level. Directly observed an iron supplementation is an effective approach for prevention and management of anemia in vulnerable groups. However, larger trials are needed before concluding that scaling up directly observed iron supplementation through community health volunteers would be beneficial.

  19. Ionic residues of human serum transferrin affect binding to the transferrin receptor and iron release.

    Science.gov (United States)

    Steere, Ashley N; Miller, Brendan F; Roberts, Samantha E; Byrne, Shaina L; Chasteen, N Dennis; Smith, Valerie C; MacGillivray, Ross T A; Mason, Anne B

    2012-01-17

    Efficient delivery of iron is critically dependent on the binding of diferric human serum transferrin (hTF) to its specific receptor (TFR) on the surface of actively dividing cells. Internalization of the complex into an endosome precedes iron removal. The return of hTF to the blood to continue the iron delivery cycle relies on the maintenance of the interaction between apohTF and the TFR after exposure to endosomal pH (≤6.0). Identification of the specific residues accounting for the pH-sensitive nanomolar affinity with which hTF binds to TFR throughout the cycle is important to fully understand the iron delivery process. Alanine substitution of 11 charged hTF residues identified by available structures and modeling studies allowed evaluation of the role of each in (1) binding of hTF to the TFR and (2) TFR-mediated iron release. Six hTF mutants (R50A, R352A, D356A, E357A, E367A, and K511A) competed poorly with biotinylated diferric hTF for binding to TFR. In particular, we show that Asp356 in the C-lobe of hTF is essential to the formation of a stable hTF-TFR complex: mutation of Asp356 in the monoferric C-lobe hTF background prevented the formation of the stoichiometric 2:2 (hTF:TFR monomer) complex. Moreover, mutation of three residues (Asp356, Glu367, and Lys511), whether in the diferric or monoferric C-lobe hTF, significantly affected iron release when in complex with the TFR. Thus, mutagenesis of charged hTF residues has allowed identification of a number of residues that are critical to formation of and release of iron from the hTF-TFR complex.

  20. Free boundary problems in controlled release pharmaceuticals: II. swelling-controlled release

    OpenAIRE

    Cohen, Donald S.; Erneux, Thomas

    1988-01-01

    A problem in controlled release pharmaceutical systems is formulated and studied. The device modeled is a polymer matrix containing an initially immobilized drug. The release of the drug is achieved by countercurrent diffusion through a penetrant solvent with the release rate being determined by the rate of diffusion of the solvent in the polymer. The mathematical theory yields a free boundary problem which is studied in various asymptotic regimes.

  1. The unique kinetics of iron release from transferrin: the role of receptor, lobe-lobe interactions, and salt at endosomal pH.

    Science.gov (United States)

    Byrne, Shaina L; Chasteen, N Dennis; Steere, Ashley N; Mason, Anne B

    2010-02-12

    Transferrins are a family of bilobal iron-binding proteins that play the crucial role of binding ferric iron and keeping it in solution, thereby controlling the levels of this important metal. Human serum transferrin (hTF) carries one iron in each of two similar lobes. Understanding the detailed mechanism of iron release from each lobe of hTF during receptor-mediated endocytosis has been extremely challenging because of the active participation of the transferrin receptor (TFR), salt, a chelator, lobe-lobe interactions, and the low pH within the endosome. Our use of authentic monoferric hTF (unable to bind iron in one lobe) or diferric hTF (with iron locked in one lobe) provided distinct kinetic end points, allowing us to bypass many of the previous difficulties. The capture and unambiguous assignment of all kinetic events associated with iron release by stopped-flow spectrofluorimetry, in the presence and in the absence of the TFR, unequivocally establish the decisive role of the TFR in promoting efficient and balanced iron release from both lobes of hTF during one endocytic cycle. For the first time, the four microscopic rate constants required to accurately describe the kinetics of iron removal are reported for hTF with and without the TFR. Specifically, at pH 5.6, the TFR enhances the rate of iron release from the C-lobe (7-fold to 11-fold) and slows the rate of iron release from the N-lobe (6-fold to 15-fold), making them more equivalent and producing an increase in the net rate of iron removal from Fe(2)hTF. Calculated cooperativity factors, in addition to plots of time-dependent species distributions in the absence and in the presence of the TFR, clearly illustrate the differences. Accurate rate constants for the pH and salt-induced conformational changes in each lobe precisely delineate how delivery of iron within the physiologically relevant time frame of 2 min might be accomplished. Copyright 2009 Elsevier Ltd. All rights reserved.

  2. Inequivalent contribution of the five tryptophan residues in the C-lobe of human serum transferrin to the fluorescence increase when iron is released.

    Science.gov (United States)

    James, Nicholas G; Byrne, Shaina L; Steere, Ashley N; Smith, Valerie C; MacGillivray, Ross T A; Mason, Anne B

    2009-04-07

    Human serum transferrin (hTF), with two Fe3+ binding lobes, transports iron into cells. Diferric hTF preferentially binds to a specific receptor (TFR) on the surface of cells, and the complex undergoes clathrin dependent receptor-mediated endocytosis. The clathrin-coated vesicle fuses with an endosome where the pH is lowered, facilitating iron release from hTF. On a biologically relevant time scale (2-3 min), the factors critical to iron release include pH, anions, a chelator, and the interaction of hTF with the TFR. Previous work, in which the increase in the intrinsic fluorescence signal was used to monitor iron release from the hTF/TFR complex, established that the TFR significantly enhances the rate of iron release from the C-lobe of hTF. In the current study, the role of the five C-lobe Trp residues in reporting the fluorescence change has been evaluated (+/-sTFR). Only four of the five recombinant Trp --> Phe mutants produced well. A single slow rate constant for iron release is found for the monoferric C-lobe (FeC hTF) and the four Trp mutants in the FeC hTF background. The three Trp residues equivalent to those in the N-lobe differed from the N-lobe and each other in their contributions to the fluorescent signal. Two rate constants are observed for the FeC hTF control and the four Trp mutants in complex with the TFR: k(obsC1) reports conformational changes in the C-lobe initiated by the TFR, and k(obsC2) is ascribed to iron release. Excitation at 295 nm (Trp only) and at 280 nm (Trp and Tyr) reveals interesting and significant differences in the rate constants for the complex.

  3. Preventing and controlling accidental gas releases

    Science.gov (United States)

    Moskowitz, P. D.; Fthenakis, V. M.; Kalb, P. D.

    1988-07-01

    Toxic, flammable, and explosive gases may be used in photovoltaic cell research laboratories and in commercial manufacturing facilities. Accidental release of these materials can present hazards to life and property. Accidents can arise from a variety of mechanical and human related failures. These can occur from the time materials are received at the loading dock of the facility to the time treated gases are discharged to the atmosphere through a stack. Each type of initiating event may require a different control approach. These may range from the training and certification of plant workers charged with the handling of gas cylinder hookups to installation of emergency pollution control systems. Since engineering options for controlling released materials are limited, emphasis should be placed on administrative and engineering approaches for preventing such accidents. These are likely to be the most effective approaches for protecting life and property.

  4. Melatonin attenuates hypochlorous acid-mediated heme destruction, free iron release, and protein aggregation in hemoglobin.

    Science.gov (United States)

    Maitra, Dhiman; Abdulhamid, Ibrahim; Diamond, Michael P; Saed, Ghassan M; Abu-Soud, Husam M

    2012-09-01

    In inflammatory diseases, where hypochlorous acid (HOCl) is elevated, iron homeostasis is disturbed, resulting in accumulation of free iron. Free iron is toxic by virtue of its ability to generate free radicals through the Fenton reaction. HOCl is generated by myeloperoxidase, (MPO) using chloride and hydrogen peroxide as substrates. Recent studies demonstrate that HOCl binds to the heme moiety of hemoglobin (Hb), which generates a transient ferric species whose formation and decay kinetics indicate it participates in protein aggregation, heme destruction, and free iron release. Here, we show that melatonin prevents HOCl-mediated Hb heme destruction and protein aggregation, using a combination of UV-vis spectrophotometry, ferrozine colorimetric assay, and in-gel heme staining. We also show that melatonin treatment prevents HOCl-mediated loss of red blood cell (RBC) viability, indicating biologic relevance of this finding. The mechanism by which melatonin prevents HOCl-mediated Hb heme destruction is by direct scavenging of HOCl and/or through the destabilization of the higher Hb oxidative states intermediates, ferryl porphyrin radical cation Hb-Fe(IV)=O(+π•) and Hb-Fe(IV)=O, which are formed through the reaction of HOCl with Hb. Our work establishes a direct mechanistic link between melatonin and its protective effect in chronic inflammatory diseases. Collectively, in addition to acting as an antioxidant and as a MPO inhibitor, melatonin can also exert its protective effect by inhibiting HOCl-mediated heme destruction of hemoproteins and subsequent free iron release.

  5. Controlled release fertilizer workshop, 1991: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Scheib, R.M. [ed.

    1991-11-01

    Over the last 20 years the Tennessee Valley Authority`s National Fertilizer and Environmental Research Center (NFERC) has carried out a number of programs to develop controlled release fertilizers. They pioneered the development and commercialization of sulfur coated urea and conducted extensive research in an attempt to develop an economical synthesis for oxamide. In recent years there has developed an increasing interest in the environmental impact of fertilizers, particularly on the potential for ground water contamination by nitrate derived from fertilizer materials. In response to this interest NFERC`s Chemical Research Department organized a five member Controlled Release Fertilizer (CRF) Team to reassess the potential for controlled release materials in agriculture with a view to minimizing any adverse environmental impact and increasing the efficiency of nutrient utilization by the crop. This workshop was part of that reassessment program. The workshop goals were: To determine the present status of CRF research, production and use; to assess the future needs of CRF producers and consumers; and to promote communication and exchange of information. To accomplish these goals the team invited speakers from across` the United States representing academics, experimental station researchers, fertilizer producers, environmentalists, and marketing experts to present papers.

  6. Controlled release fertilizer workshop, 1991: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Scheib, R.M. (ed.)

    1991-11-01

    Over the last 20 years the Tennessee Valley Authority's National Fertilizer and Environmental Research Center (NFERC) has carried out a number of programs to develop controlled release fertilizers. They pioneered the development and commercialization of sulfur coated urea and conducted extensive research in an attempt to develop an economical synthesis for oxamide. In recent years there has developed an increasing interest in the environmental impact of fertilizers, particularly on the potential for ground water contamination by nitrate derived from fertilizer materials. In response to this interest NFERC's Chemical Research Department organized a five member Controlled Release Fertilizer (CRF) Team to reassess the potential for controlled release materials in agriculture with a view to minimizing any adverse environmental impact and increasing the efficiency of nutrient utilization by the crop. This workshop was part of that reassessment program. The workshop goals were: To determine the present status of CRF research, production and use; to assess the future needs of CRF producers and consumers; and to promote communication and exchange of information. To accomplish these goals the team invited speakers from across' the United States representing academics, experimental station researchers, fertilizer producers, environmentalists, and marketing experts to present papers.

  7. Meticulous Overview on the Controlled Release Fertilizers

    Directory of Open Access Journals (Sweden)

    Siafu Ibahati Sempeho

    2014-01-01

    Full Text Available Owing to the high demand for fertilizer formulations that will exhaust the possibilities of nutrient use efficiency (NUE, regulate fertilizer consumption, and lessen agrophysicochemical properties and environmental adverse effects instigated by conventional nutrient supply to crops, this review recapitulates controlled release fertilizers (CRFs as a cutting-edge and safe way to supply crops’ nutrients over the conventional ways. Essentially, CRFs entail fertilizer particles intercalated within excipients aiming at reducing the frequency of fertilizer application thereby abating potential adverse effects linked with conventional fertilizer use. Application of nanotechnology and materials engineering in agriculture particularly in the design of CRFs, the distinctions and classification of CRFs, and the economical, agronomical, and environmental aspects of CRFs has been revised putting into account the development and synthesis of CRFs, laboratory CRFs syntheses and testing, and both linear and sigmoid release features of CRF formulations. Methodical account on the mechanism of nutrient release centring on the empirical and mechanistic approaches of predicting nutrient release is given in view of selected mathematical models. Compositions and laboratory preparations of CRFs basing on in situ and graft polymerization are provided alongside the physical methods used in CRFs encapsulation, with an emphasis on the natural polymers, modified clays, and superabsorbent nanocomposite excipients.

  8. Controls on Fe(II)-Activated Trace Element Release from Goethite and Hematite

    Energy Technology Data Exchange (ETDEWEB)

    Frierdich, Andrew J.; Catalano, Jeffrey G. (WU)

    2012-03-26

    Electron transfer and atom exchange (ETAE) between aqueous Fe(II) and Fe(III) oxides induces surface growth and dissolution that affects trace element fate and transport. We have recently demonstrated Ni(II) cycling through goethite and hematite (adsorbed Ni incorporates into the mineral structure and preincorporated Ni releases to solution) during Fe(II)-Fe(III) ETAE. However, the chemical parameters affecting net trace element release remain unknown. Here, we examine the chemical controls on Ni(II) and Zn(II) release from Ni- and Zn-substituted goethite and hematite during reaction with Fe(II). Release follows a rate law consistent with surface reaction limited mineral dissolution and suggests that release occurs near sites of Fe(III) reductive dissolution during Fe(II)-Fe(III) ETAE. Metal substituent type affects reactivity; Zn release is more pronounced from hematite than goethite, whereas the opposite trend occurs for Ni. Buildup of Ni or Zn in solution inhibits further release but this resumes upon fluid exchange, suggesting that sustained release is possible under flow conditions. Mineral and aqueous Fe(II) concentrations as well as pH strongly affect sorbed Fe(II) concentrations, which directly control the reaction rates and final metal concentrations. Our results demonstrate that structurally incorporated trace elements are mobilized from iron oxides into fluids without abiotic or microbial net iron reduction. Such release may affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems.

  9. Control of cast iron and casts manufacturing by Inmold method

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2009-07-01

    Full Text Available In this paper the usability of cast iron spheroidizing process in mould control by ATD method as well as by ultrasonic method were presented. Structure of instrumentation needed for control form performance of cast iron spheroidizing by Inmold method was illustrated. Author, pointed out that amount of magnesium master alloy should obtain 0,8 ÷ 1,0% of mass in form at all. Such quantity of preliminary alloy assure of obtain of nodular graphite in cast iron. In consequence of this, is reduce the cast iron liquidus temperature and decrease of recalescence temperature of graphite-eutectic crystallization in compare with initial cast iron. Control of casts can be carried out by ultrasonic method. In plain cast iron, ferritic-pearlitic microstructure is obtaining. Additives of 1,5% Cu ensure pearlitic structure.

  10. Soil Manganese and Iron Released due to Calcium Salts:Bioavailability to Pepper (Capsicum frutescens L.)

    Institute of Scientific and Technical Information of China (English)

    SI You-Bin; ZHOU Jing; ZHOU Dong-Mei; CHEN Huai-Man

    2004-01-01

    Releases of manganese and iron ions from an albic soil (Albic-Udic Luvisol), a yellow-red soil (Hap-Udic Ferrisol) and a yellow-brown soil (Arp-Udic Luvisol) induced by calcium salt addition and their bioavailability to pepper (Capsicum frutescens L.) were studied in a pot experiment. Addition of Ca(NO3)2 decreased soil pH and increased both exchangeable and DTPA (diethylenetriamine pentaacetic acid)-extractable Mn and Fe in soils. Meanwhile, total Mn accumulation in the shoots of Capsicum frutescens L. on the salt-treated soils increased significantly (P < 0.01) compared with the control, suggesting that salt addition to soil induced Mn toxicity in Capsicum frutescens L. Although exchangeable and DTPA-extractable Fe increased also in the salt-treated soils, Fe uptake by the shoots of Capsicum frutescens L. decreased. The effect of added salts in soils on dry matter weight of pepper varied with the soil characteristics, showing different buffer capacities of the soils for salt toxicity in an order of yellow-brown soil > albic soil > yellow-red soil. Fe/Mn ratio in shoots of Capsicum frutescens L. decreased with increasing salt addition for all the soils, which was ascribed to the antagonistic effect of Mn on Fe accumulation. The ratio of Fe/Mn in the tissue was a better indicator of the appearance of Mn toxicity symptoms than Mn concentration alone.

  11. Controlled Release Formulations of Auxinic Herbicides

    Science.gov (United States)

    Kowalski, Witold J.; Siłowiecki, Andrzej.; Romanowska, Iwona; Glazek, Mariola; Bajor, Justyna; Cieciwa, Katarzyna; Rychter, Piotr

    2013-04-01

    Controlled release formulations are applied extensively for the release of active ingredients such as plant protection agents and fertilizers in response to growing concern for ecological problems associated with increased use of plant protection chemicals required for intensive agricultural practices [1]. We synthesized oligomeric mixtures of (R,S)-3-hydroxy butyric acid chemically bonded with 2,4-D, Dicamba and MCPA herbicides (HBA) respectively, and determined their molecular structure and molecular weight dispersion by the size exclusion chromatography, proton magnetic resonance spectrometry and electro-spray ionization mass spectrometry. Further we carried out bioassays of herbicidal effectiveness of the HBA herbicides vs. series of dicotyledonous weeds and crop injury tests [2, 3, 4]. Field bioassays were accomplished according to the EPPO standards [5]. Groups of representative weeds (the development stages in the BCCH scale: 10 - 30) were selected as targets. Statistical variabilities were assessed by the Fisher LSD test for plants treated with the studied herbicides in form of HBA oligomers, the reference herbicides in form of dimethyl ammonium salts (DMA), and untreated plants. No statistically significant differences in the crop injuries caused by the HBA vs. the DMA reference formulation were observed. The effectiveness of the HBA herbicides was lower through the initial period (ca. 2 weeks) relative to the DMA salts, but a significant increase in the effectiveness of the HBA systems followed during the remaining fraction of each assay. After 6 weeks all observed efficiencies approached 100%. The death of weeds treated with the HBA herbicides was delayed when compared with the DMA reference herbicides. The delayed uptake observed for the HBA oligomers relative to the DMA salts was due to controlled release phenomena. In case of the DMA salts the total amount of active ingredients was available at the target site. By contrast, the amount of an active

  12. Iron release and ROS generation from mineral particles are not related to cytokine release or apoptosis in exposed A549 cells.

    Science.gov (United States)

    Ovrevik, J; Hetland, R B; Schins, R P; Myran, T; Schwarze, P E

    2006-08-01

    The generation of reactive oxygen species (ROS) by mineral particles is believed to be central to their toxicity and their ability to induce inflammation. Surface bound or soluble iron may contribute to the particle-effects by enhancing the ROS generation through the Fenton reaction. Nevertheless, the importance of ROS and transition metals to mineral particle-induced effects is still unclear and further investigations are needed. In the present study we have investigated different mineral particles for their total iron content, amount of soluble iron at pH 7.0 and 4.0, their ability to generate ROS in a cell-free environment, and their ability to induce cytokine release and apoptosis in a human alveolar epithelial cell line (A549). All the investigated parameters varied considerably between the different particles, with the exception of ability to induce apoptosis. Total iron content did not reflect the amount of soluble iron, and neither total nor soluble iron was correlated with ROS generation. Moreover, iron content and ROS was not correlated with the ability of particles to induce cytokine release or apoptosis. The present results suggest that there is no clear relationship between the particles iron content and ability to generate ROS. Moreover, neither iron content nor the ability to induce ROS generation appears to be a prerequisite for the inflammatory potential or cytotoxicity of mineral particles.

  13. Towards the development of multifunctional chitosan-based iron oxide nanoparticles: Optimization and modelling of doxorubicin release.

    Science.gov (United States)

    Soares, Paula I P; Sousa, Ana Isabel; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-11-20

    In the present work composite nanoparticles with a magnetic core and a chitosan-based shell were produced as drug delivery systems for doxorubicin (DOX). The results show that composite nanoparticles with a hydrodynamic diameter within the nanometric range are able to encapsulate more DOX than polymeric nanoparticles alone corresponding also to a higher drug release. Moreover the synthesis method of the iron oxide nanoparticles influences the total amount of DOX released and a high content of iron oxide nanoparticles inhibits DOX release. The modelling of the experimental results revealed a release mechanism dominated by Fickian diffusion.

  14. A Responsive Battery with Controlled Energy Release.

    Science.gov (United States)

    Wang, Xiaopeng; Gao, Jian; Cheng, Zhihua; Chen, Nan; Qu, Liangti

    2016-11-14

    A new type of responsive battery with the fascinating feature of pressure perceptibility has been developed, which can spontaneously, timely and reliably control the power outputs (e.g., current and voltage) in response to pressure changes. The device design is based on the structure of the Zn-air battery, in which graphene-coated sponge serves as pressure-sensitive air cathode that endows the whole system with the capability of self-controlled energy release. The responsive batteries exhibit superior battery performance with high open-circuit voltage (1.3 V), and competitive areal capacity of 1.25 mAh cm(-2) . This work presents an important move towards next-generation intelligent energy storage devices with energy management function. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Efficacy of Different Iron Fortificants in Wheat Flour in Controlling Iron Deficiency

    Institute of Scientific and Technical Information of China (English)

    JIAN HUANG; JING SUN; WEN-XIAN LI; LI-JUAN WANG; AN-XU WANG; JUN-SHENG HUO; JUN-SHI CHEN; CHUN-MING CHEN

    2009-01-01

    Objective To observe the different impacts of electrolytic iron, FeSO4, and NaFeEDTA on body iron store of anemic school students. Methods Four hundreds anemic students at the age of 11 -18 years were divided into four groups. Of which, three consumed different iron fortificants from wheat flour as food vehicle for six months and one consumed non-fortified flour (control). The fortification level of electrolytic iron, FeSO4, and NaFeEDTA was 60 mg Fe/kg, 30 mg Fe/kg, and 20 mg Fe/kg, respectively. Blood samples were collected at 0, 2, 4, and 6 months and hemoglobin (Hb), serum ferritin (SF), and transferrin receptor (TfR) were measured. Results The hemoglobin levels in three intervention groups increased, the increments of Hb in the NaFeEDTA group were significantly higher than that in the other groups. SF and TfR levels increased in the tested groups and body iron store in the NaFeEDTA group was higher than that in the other groups. These parameters did not show any significant changes in the control group. Conclusion NaFeEDTA and FeSO4 fortified wheat flour has positive impacts on iron status in anemic students and NaFeEDTA is more effective than FeSO4, while electrolytic iron is less effective in improving iron store in anemic students.

  16. Magnetically triggered release of molecular cargo from iron oxide nanoparticle loaded microcapsules

    Science.gov (United States)

    Carregal-Romero, Susana; Guardia, Pablo; Yu, Xiang; Hartmann, Raimo; Pellegrino, Teresa; Parak, Wolfgang J.

    2014-12-01

    Photothermal release of cargo molecules has been extensively studied for bioapplications. For instance, microcapsules decorated with plasmonic nanoparticles have been widely used in in vitro assays. However, some concerns about their suitability for some in vivo applications cannot be easily overcome, in particular the limited penetration depth of light (even infrared). Magnetic nanoparticles are alternative heat-mediators for local heating, which can be triggered by applying an alternating magnetic field (AMF). AMFs are much less absorbed by tissue than light and thus can penetrate deeper overcoming the above mentioned limitations. Here we present iron oxide nanocube-modified microcapsules as a platform for magnetically triggered molecular release. Layer-by-layer assembled polyelectrolyte microcapsules with 4.6 μm diameter, which had 18 nm diameter iron oxide nanocubes integrated in their walls, were synthesized. The microcapsules were further loaded with an organic fluorescent polymer (Cascade Blue-labelled dextran), which was used as a model of molecular cargo. Through an AMF the magnetic nanoparticles were able to heat their surroundings and destroy the microcapsule walls, leading to a final release of the embedded cargo to the surrounding solution. The cargo release was monitored in solution by measuring the increase in both absorbance and fluorescence signal after the exposure to an AMF. Our results demonstrate that magnetothermal release of the encapsulated material is possible using magnetic nanoparticles with a high heating performance.Photothermal release of cargo molecules has been extensively studied for bioapplications. For instance, microcapsules decorated with plasmonic nanoparticles have been widely used in in vitro assays. However, some concerns about their suitability for some in vivo applications cannot be easily overcome, in particular the limited penetration depth of light (even infrared). Magnetic nanoparticles are alternative heat

  17. Control of noradrenaline release from hippocampal synaptosomes

    Energy Technology Data Exchange (ETDEWEB)

    West, D.P.; Fillenz, M.

    1981-10-01

    Potassium-evoked tritiated noradrenaline (NA) release from hippocampal synaptosomes was measured with a superfusion method. A single 2-min high-K+ pulse released 39% of the vesicular NA by a Ca2+-dependent mechanism: the Ca2+-independent release was negligible. After changing the vesicular NA store size by pretreating rats with either alpha-methyl-para-tyrosine, 500 mg/kg, or tranylcypromine, 10 mg/kg, a single K+ pulse released a constant percentage of the vesicular NA. With two K+ pulses, however, there was a reduction in the percentage of vesicular NA released in response to the second pulse.

  18. Formation and release behavior of iron corrosion products under the influence of bacterial communities in a simulated water distribution system.

    Science.gov (United States)

    Sun, Huifang; Shi, Baoyou; Lytle, Darren A; Bai, Yaohui; Wang, Dongsheng

    2014-03-01

    To understand the formation and release behavior of iron corrosion products in a drinking water distribution system, annular reactors (ARs) were used to investigate the development processes of corrosion products and biofilm community as well as the concomitant iron release behavior. Results showed that the formation and transformation of corrosion products and bacterial community are closely related to each other. The presence of sulfate-reducing bacteria (SRB, e.g. Desulfovibrio and Desulfotomaculum), sulfur-oxidizing bacteria (SOB, e.g. Sulfuricella), and iron-oxidizing bacteria (IOB, e.g. Acidovorax, Gallionella, Leptothrix, and Sphaerotilus) in biofilms could speed up iron corrosion; however, iron-reducing bacteria (IRB, e.g. Bacillus, Clostridium, and Pseudomonas) could inhibit iron corrosion and iron release. Corrosion scales on iron coupons could develop into a two-layered structure (top layer and inner layer) with time. The relatively stable constituents such as goethite (α-FeOOH) and magnetite (Fe3O4) mainly existed in the top layers, while green rust (Fe6(OH)12CO3) mainly existed in the inner layers. The IOB (especially Acidovorax) contributed to the formation of α-FeOOH, while IRB and the anaerobic conditions could facilitate the formation of Fe3O4. Compared with the AR test without biofilms, the iron corrosion rate with biofilms was relatively higher (p iron release with biofilms was obviously lower both at the initial stage and after 3 months. Biofilm and corrosion scale samples formed under different water supply conditions in an actual drinking water distribution system verified the relationships between the bacterial community and corrosion products.

  19. Incorporation and release of drug into/from superparamagnetic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Maver, Uros; Bele, Marjan [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia); Makovec, Darko; Campelj, Stanislav [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Jamnik, Janko [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia); Gaberscek, Miran [National Institute of Chemistry Slovenia, Hajdrihova 19, 1000 Ljubljana (Slovenia)], E-mail: miran.gaberscek@ki.si

    2009-10-15

    The aim of this study was to attach a model drug (naproxen) onto superparamagnetic iron oxide nanoparticles (SPION). First, SPION were coated with thin layer of silica that contained micropores. We demonstrated that such surface functionalization could be optimized by the use of citric acid which prevented SPION agglomeration during the procedure. HRTEM investigation showed a uniform 1-2-nm-thick silica coating around SPION. This coating did not affect significantly the magnetic properties of the SPION. Into the coated SPION we successfully incorporated about 30 wt% of naproxen. The latter was readily released after immersion into a testing solution. The composites could be interesting for potential use in diagnostics.

  20. [Effect of the change in sulphate and dissolved oxygen mass concentration on metal release in old cast iron distribution pipes].

    Science.gov (United States)

    Wu, Yong-li; Shi, Bao-you; Sun, Hui-fang; Zhang, Zhi-huan; Gu, Jun-nong; Wang, Dong-sheng

    2013-09-01

    To understand the processes of corrosion by-product release and the consequent "red water" problems caused by the variation of water chemical composition in drinking water distribution system, the effect of sulphate and dissolved oxygen (DO) concentration on total iron release in corroded old iron pipe sections historically transporting groundwater was investigated in laboratory using small-scale pipe section reactors. The release behaviors of some low-level metals, such as Mn, As, Cr, Cu, Zn and Ni, in the process of iron release were also monitored. The results showed that the total iron and Mn release increased significantly with the increase of sulphate concentration, and apparent red water occurred when sulphate concentration was above 400 mg x L(-1). With the increase of sulfate concentration, the effluent concentrations of As, Cr, Cu, Zn and Ni also increased obviously, however, the effluent concentrations of these metals were lower than the influent concentrations under most circumstances, which indicated that adsorption of these metals by pipe corrosion scales occurred. Increasing DO within a certain range could significantly inhibit the iron release.

  1. Biological control of weeds release sites : Kulm Wetland Management District

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Table of release sites of insects for biological control of invasive plants at Kulm Wetland Management District (WMD). Insects were released on Kulm WMD to...

  2. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  3. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xiang Wang

    2013-01-01

    Full Text Available We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  4. Controls on radium transport by adsorption to iron minerals

    Science.gov (United States)

    Chen, M.; Wang, T.; Kocar, B. D.

    2015-12-01

    Radium is a naturally occurring radioactive metal found in many subsurface environments. Radium isotopes are generated by uranium and thorium decay, and are particularly abundant within groundwaters where minimal porewater flux leads to accumulation. These isotopes are used as natural tracers for estimating submarine groundwater discharge (SGD) [1], allowing for large scale estimation of GW fluxes into and out of the ocean [2]. They also represent a substantial hazard in wastewater produced after hydraulic fracturing for natural gas extraction [3], resulting in a significant risk of environmental release to surface and near-surface waters, and increased cost for water treatment or disposal. Adsorption to mineral surfaces represents a dominant pathway of radium retention in subsurface environments. For SGD studies, adsorption processes impact estimates of GW fluxes, while in hydraulic fracturing, radium adsorption to aquifer solids mediates wastewater radium activities. Analysis of past sorption studies revealed large variability in partition coefficients [4], while examination of radium adsorption kinetics and surface complexation have only recently started [5]. Accordingly, we present the results of sorption and column experiments of radium with a suite of iron minerals representative of those found within deep saline and near-surface (freshwater) aquifers, and evaluate impacts of varying salinity solutions through artificial waters. Further, we explore the impacts of pyrite oxidation and ferrihydrite transformation to other iron-bearing secondary minerals on the transport and retention of radium. These results will provide critical information on the mineralogical controls on radium retention in subsurface environments, and will therefore improve predictions of radium groundwater transport in natural and contaminated systems. [1] Charette, M.A., Buesseler, K.O. & Andrews, J.E., Limnol. Oceanogr. (2001). [2] Moore, W.S., Ann. Rev. Mar. Sci. (2010). [3] Vengosh, A

  5. Bioactive dietary polyphenols decrease heme iron absorption by decreasing basolateral iron release in human intestinal Caco-2 cells.

    Science.gov (United States)

    Ma, Qianyi; Kim, Eun-Young; Han, Okhee

    2010-06-01

    Because dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron, it is prudent to test whether the regular consumption of dietary bioactive polyphenols impair the utilization of dietary iron. Because our previous study showed the inhibitory effect of (-) -epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) on nonheme iron absorption, we investigated whether EGCG and GSE also affect iron absorption from heme. The fully differentiated intestinal Caco-2 cells grown on microporous membrane inserts were incubated with heme (55)Fe in uptake buffer containing EGCG or GSE in the apical compartment for 7 h. Both EGCG and GSE decreased (P heme-derived iron. However, apical heme iron uptake was increased (P heme (55)Fe, the transfer of iron across the intestinal basolateral membrane was extremely low, indicating that basolateral export was impaired by GSE. In contrast, EGCG moderately decreased the cellular assimilation of heme (55)Fe, but the basolateral iron transfer was extremely low, suggesting that the basolateral efflux of heme iron was also inhibited by EGCG. Expression of heme oxygenase, ferroportin, and hephaestin protein was not changed by EGCG and GSE. The apical uptake of heme iron was temperature dependent and saturable in fully differentiated Caco-2 cells. Our data show that bioactive dietary polyphenols inhibit heme iron absorption mainly by reducing basolateral iron exit rather than decreasing apical heme iron uptake in intestinal cells.

  6. Hydrologically Controlled Arsenic Release in Deltaic Wetlands and Coastal Riparian Zones

    Science.gov (United States)

    Stuckey, J.; LeMonte, J. J.; Yu, X.; Schaefer, M.; Kocar, B. D.; Benner, S. G.; Rinklebe, J.; Tappero, R.; Michael, H. A.; Fendorf, S. E.; Sparks, D. L.

    2016-12-01

    Wetland and riparian zone hydrology exerts critical controls on the biogeochemical cycling of metal contaminants including arsenic. The role of wetlands in driving geogenic arsenic release to groundwater has been debated in the deltas of South and Southeast Asia where the largest impacted human population resides. In addition, groundwater in coastal areas worldwide, such as those in South and Southeast Asia and the Mid-Atlantic of the U.S., is at risk to largely unexplored biogeochemical and hydrologic impacts of projected sea level rise. First, we present data from fresh-sediment incubations, in situ model sediment incubations and a controlled field experiment with manipulated wetland hydrology and organic carbon inputs in the minimally disturbed upper Mekong Delta. Here we show that arsenic release is limited to near-surface sediments of permanently saturated wetlands where both organic carbon and arsenic-bearing solids are sufficiently reactive for microbial oxidation of organic carbon and reduction of arsenic-bearing iron oxides. In contrast, within the deeper aquifer or seasonally saturated sediments, reductive dissolution of iron oxides is observed only when either more reactive exogenous forms of iron oxides or organic carbon are added, revealing a potential thermodynamic restriction to microbial metabolism. Second, in order to assess the potential impacts of sea level rise on arsenic release to groundwater, we determined the changes in arsenic speciation and partitioning in sediment collected from an anthropogenically contaminated coastal riparian zone under controlled Eh regimes in both seawater and freshwater systems. Here we show greater arsenic release under anoxic/suboxic conditions in the freshwater system than in the seawater system, potentially due to high salinity induced microbial inhibition. Collectively, our work shows that shifting hydrologic conditions in deltaic wetlands and tidally influenced zones impacts the extent of arsenic release to

  7. Molecularly imprinted nanotubes for enantioselective drug delivery and controlled release.

    Science.gov (United States)

    Yin, Junfa; Cui, Yue; Yang, Gengliang; Wang, Hailin

    2010-11-07

    Molecularly imprinted nanotubes for enantioselective drug delivery and controlled release are fabricated by the combination of template synthesis and ATRP grafting. The release of R-propranolol from the imprinted nanotubes in rats is restricted while the release of pharmacologically active S-enantiomer is greatly promoted.

  8. Analytical solution of diffusion model for nutrient release from controlled release fertilizer

    Science.gov (United States)

    Ameenuddin Irfan, Sayed; Razali, Radzuan; KuShaari, KuZilati; Mansor, Nurlidia; Azeem, Babar

    2017-09-01

    An analytical method has been developed to solve the initial value problem which arises from Fick’s diffusion equation encountered in the modelling of the Controlled Release Fertilizers. The proposed analytical solution is developed using the modified Adomian decomposition method. This method does not require the discretization method, reliability and efficiency of this method is more and it also reduces the calculation time. The model has predicted the effect of granule radius and diffusion coefficient on the nutrient release and total release time of Controlled Release Fertilizer. Model has predicted that increase in the radius of granule reduces the release and vice versa in case of diffusion coefficient. Detailed understanding of these parameters helps in improved designing of Controlled Release Fertilizer.

  9. Iron and manganese contamination: sources, adverse effects and control methods.

    Science.gov (United States)

    Satyanarayana, Y V V; Saraf, Renu

    2007-10-01

    This article discusses the problem of iron and manganese contamination, the adverse effects and available control methods. The presence of iron and manganese in water causes serious commercial and health problems. Various treatment methods are available to treat water contaminated with these elements. However, catalytic media is an excellent choice particularly increasing given the preference for non-chemical water treatment. INDION ISR and BIRM are the most popularly used synthetically manufactured catalytic media.

  10. Microfluidic synthesis of microfibers for magnetic-responsive controlled drug release and cell culture.

    Directory of Open Access Journals (Sweden)

    Yung-Sheng Lin

    Full Text Available This study demonstrated the fabrication of alginate microfibers using a modular microfluidic system for magnetic-responsive controlled drug release and cell culture. A novel two-dimensional fluid-focusing technique with multi-inlets and junctions was used to spatiotemporally control the continuous laminar flow of alginate solutions. The diameter of the manufactured microfibers, which ranged from 211 µm to 364 µm, could be well controlled by changing the flow rate of the continuous phase. While the model drug, diclofenac, was encapsulated into microfibers, the drug release profile exhibited the characteristic of a proper and steady release. Furthermore, the diclofenac release kinetics from the magnetic iron oxide-loaded microfibers could be controlled externally, allowing for a rapid drug release by applying a magnetic force. In addition, the successful culture of glioblastoma multiforme cells in the microfibers demonstrated a good structural integrity and environment to grow cells that could be applied in drug screening for targeting cancer cells. The proposed microfluidic system has the advantages of ease of fabrication, simplicity, and a fast and low-cost process that is capable of generating functional microfibers with the potential for biomedical applications, such as drug controlled release and cell culture.

  11. [Nutrient release characteristics and use efficiency of slow- and controlled release fertilizers].

    Science.gov (United States)

    Duan, Lu-Lu; Zhang, Min; Liu, Gang; Shang, Zhao-Cong; Yang, Yi

    2009-05-01

    Water extraction method and soil incubation method were used to study the nutrient release characteristics of four slow- and controlled release fertilizers (CRF1, CRF2, SCU, and IBDU), and pot experiment was conducted to assess the effects of the release characteristics on the nutrient requirements of canola (Brassica napus L.). The nutrient release curves of test fertilizers in water were S pattern for CRF1 and CRF2, burst pattern for SCU, and reverse L pattern for IBDU. The nutrient release characteristics of the four fertilizers in water and in soil all fitted binomial equations, suggesting that there existed some similarities in the nutrient release in the two media. The nutrient uptake and biomass of canola plants treated with CRF1 and CRF2 were significantly higher than those treated with SCU and IBDU, and CRF2 had the greatest effect. The nutrient release curves of CRF1 and CRF2 accorded more closely with the nutrient requirements of canola.

  12. Controls on Arsenic Retention in Surface and Subsurface Environments: Resolving the Impact of Iron Reduction

    Science.gov (United States)

    Tufano, K.; Fendorf, S.

    2007-12-01

    A transition from oxidizing to reducing conditions has long been implicated in increasing aqueous As concentrations. Confounding processes controlling the release of As, reductive transformation of ferrihydrite, a common Fe(III) (hydr)oxide, has recently been shown to promote As retention rather than release. Elucidating the processes controlling As desorption and subsequent migration in surface and subsurface environments and how environmental factors (for example, availability of labile carbon and duration/extent of flooding) affect these processes will allow predictions to be made regarding long-term stability of As in soil and sediment. In turn, this can aid in evaluating the likelihood of having measurable As in groundwater. To better resolve these processes, here we examine As desorption from ferrihydrite-coated sands pre-sorbed with As(III) at circumneutral pH under Fe-reducing conditions with the dissimilatory iron reducing bacterium (DIRB) Shewanella putrefaciens strain CN- 32. We reveal that upon iron reduction, transformation of As-bearing ferrihydrite results in As(III) retention. However, over time there is a shift from reductive transformation to reductive dissolution of the As-bearing Fe phase(s) coupled with prolonged release of As to the aqueous phase. Our results suggest that arsenic retention may increase or decrease depending on the type of iron oxide, secondary iron transformations, and duration of reducing conditions. Immediately following a transition to anaerobic conditions there is potential for As retention on newly formed ferric/ferrous (hydr)oxide phases; however prolonged reduction will result in both the dissolution of ferric/ferrous (hydr)oxides and release of aqueous arsenic.

  13. Monoubiquitin-dependent endocytosis of the IRON-REGULATED TRANSPORTER 1 (IRT1) transporter controls iron uptake in plants

    OpenAIRE

    Barberon, Marie; Zelazny, Enric; Robert, Stéphanie; Conejero, Geneviève; Curie, Catherine; Friml, Jìrí; Vert, Grégory

    2011-01-01

    Plants take up iron from the soil using the IRON-REGULATED TRANSPORTER 1 (IRT1) high-affinity iron transporter at the root surface. Sophisticated regulatory mechanisms allow plants to tightly control the levels of IRT1, ensuring optimal absorption of essential but toxic iron. Here, we demonstrate that overexpression of Arabidopsis thaliana IRT1 leads to constitutive IRT1 protein accumulation, metal overload, and oxidative stress. IRT1 is unexpectedly found in trans-Golgi network/early endosom...

  14. Environmental Release Prevention and Control Plan

    Energy Technology Data Exchange (ETDEWEB)

    Mamatey, A.; Arnett, M.

    1997-10-01

    During the history of SRS, continual improvements in facilities, process, and operations, and changes in the site`s mission have reduced the amount of radioactive liquid releases. In the early years of SRS (1958 to 1965), the amount of tritium discharged to the Savannah River averaged approximately 61,000 curies a year. During the mid-1980`s (1983 to 1988), liquid releases of tritium averaged 27,000 curies a year. By 1996, liquid releases of tritium are projected to be just 3000 curies for the year. This large projected decrease is the result of the planned shut-down of all reactors and the anticipated significant decline in the amount of tritium migrating from the site seepage basins and the Solid Waste Disposal Facility.

  15. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  16. Iron

    Science.gov (United States)

    ... of iron stored in the body become low, iron deficiency anemia sets in. Red blood cells become smaller and ... from the lungs throughout the body. Symptoms of iron deficiency anemia include tiredness and lack of energy, GI upset, ...

  17. Overview study of LNG release prevention and control systems

    Energy Technology Data Exchange (ETDEWEB)

    Pelto, P.J.; Baker, E.G.; Holter, G.M.; Powers, T.B.

    1982-03-01

    The liquefied natural gas (LNG) industry employs a variety of release prevention and control techniques to reduce the likelihood and the consequences of accidental LNG releases. A study of the effectiveness of these release prevention and control systems is being performed. Reference descriptions for the basic types of LNG facilities were developed. Then an overview study was performed to identify areas that merit subsequent and more detailed analyses. The specific objectives were to characterize the LNG facilities of interest and their release prevention and control systems, identify possible weak links and research needs, and provide an analytical framework for subsequent detailed analyses. The LNG facilities analyzed include a reference export terminal, marine vessel, import terminal, peakshaving facility, truck tanker, and satellite facility. A reference description for these facilities, a preliminary hazards analysis (PHA), and a list of representative release scenarios are included. The reference facility descriptions outline basic process flows, plant layouts, and safety features. The PHA identifies the important release prevention operations. Representative release scenarios provide a format for discussing potential initiating events, effects of the release prevention and control systems, information needs, and potential design changes. These scenarios range from relatively frequent but low consequence releases to unlikely but large releases and are the principal basis for the next stage of analysis.

  18. A retrospective mathematical analysis of controlled release design and experimentation.

    Science.gov (United States)

    Rothstein, Sam N; Kay, Jennifer E; Schopfer, Francisco J; Freeman, Bruce A; Little, Steven R

    2012-11-01

    The development and performance evaluation of new biodegradable polymer controlled release formulations relies on successful interpretation and evaluation of in vitro release data. However, depending upon the extent of empirical characterization, release data may be open to more than one qualitative interpretation. In this work, a predictive model for release from degradable polymer matrices was applied to a number of published release data in order to extend the characterization of release behavior. Where possible, the model was also used to interpolate and extrapolate upon collected released data to clarify the overall duration of release and also kinetics of release between widely spaced data points. In each case examined, mathematical predictions of release coincide well with experimental results, offering a more definitive description of each formulation's performance than was previously available. This information may prove particularly helpful in the design of future studies, such as when calculating proper dosing levels or determining experimental end points in order to more comprehensively evaluate a controlled release system's performance.

  19. Controlled oxidation of iron nanoparticles in chemical vapour synthesis

    Science.gov (United States)

    Ruusunen, Jarno; Ihalainen, Mika; Koponen, Tarmo; Torvela, Tiina; Tenho, Mikko; Salonen, Jarno; Sippula, Olli; Joutsensaari, Jorma; Jokiniemi, Jorma; Lähde, Anna

    2014-02-01

    In the present study, iron oxide nanoparticles (primary particle size of 80-90 nm) with controlled oxidation state were prepared via an atmospheric pressure chemical vapour synthesis (APCVS) method. Iron pentacarbonyl [Fe(CO)5], a precursor material, was thermally decomposed to iron in the APCVS reactor. Subsequently, the iron was oxidized with controlled amount of oxygen in the reactor to produce nearly pure magnetite or haematite particles depending on the oxygen concentration. Size, morphology and crystal structure of the synthesized nanoparticles were studied with scanning mobility particle sizer (SMPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). In addition, thermodynamic equilibrium calculations and computational fluid dynamics model were used to predict the oxidation state of the iron oxides and the reaction conditions during mixing. Aggregates of crystalline particles were formed, determined as magnetite at the oxygen volumetric fraction of 0.1 % and haematite at volumetric fraction of 0.5 %, according to the XRD. The geometric mean electrical mobility diameter of the aggregates increased from 110 to 155 nm when the volumetric fraction of oxygen increased from 0.1 to 0.5 %, determined using the SMPS. The aggregates were highly sintered based on TEM analyses. As a conclusion, APCVS method can be used to produce nearly pure crystalline magnetite or haematite nanoparticles with controlled oxidation in a continuous one-stage gas-phase process.

  20. Electrospinning nanofibers for controlled drug release

    Science.gov (United States)

    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.

  1. Application of advanced polymeric materials for controlled release pesticides

    Science.gov (United States)

    Rahim, M.; Hakim, M. R.; Haris, H. M.

    2016-08-01

    The objective of this work was to study the capability of advanced polymeric material constituted by chitosan and natural rubber matrices for controlled release of pesticides (1-hydroxynaphthalene and 2-hydroxynaphthalene) in aqueous solution. The released amount of pesticides was measured spectrophotometrically from the absorbance spectra applying a standardized curve. The release of the pesticides was studied into refreshing and non-refreshing neutral aqueous media. Interestingly, formulation successfully indicated a consistent, controlled and prolonged release of pesticides over a period of 35 days.

  2. Controlled-release Properties of Microencapsulated Disperse Dyes

    Institute of Scientific and Technical Information of China (English)

    LUO Yan; LI Chun-yan; CHEN Shui-lin

    2002-01-01

    Some disperse dyes were microencapsulated by means of in- situ polymerization. These microencapsulated disperse dyes was extracted respectively by ethanol under certain conditions. The controlled-release properties of disperse dyes through the shell of microcapsules were measured by spectrophotometer. According to the results, it was drawn that the type of disperse dyes, the auxiliaries contained in disperse dyes, the quantity of system controlling medium used and the core/shell ratio of microcapsules play important roles in controlling the release properties of microcapsules. The different controlled- release properties of microcapsules, which were prepared under given conditions, however, would in turn influence the performance of microcapsules in multiple-transfer printing.

  3. Optimal Release Control of Companion Satellite System Using Electromagnetic Forces

    Institute of Scientific and Technical Information of China (English)

    Zengwen Xu,Peng Shi; Yushan Zhao∗

    2015-01-01

    Electromagnetic forces generated by the inter⁃action of component satellites can be used to release companion satellites. Optimal release trajectories for companion satellite system using inter⁃electromagnetic forces were investigated. Firstly, nonlinear relative motion dynamic equations of a two⁃craft electromagnetic companion satellite system were derived in spatial polar coordinates. Then principles of electromagnetic satellite formation flying were introduced. Secondly, the characteristics of the electromagnetic companion satellites release were analyzed and optimal release trajectories of companion satellites using electromagnetic forces were obtained using Gauss pseudospectral method. Three performance criteria were chosen as minimum time, minimum acceleration of the separation distance and minimum control acceleration. Finally, three release examples including expansion along separation distance, rotation in orbital plane and stable formation reconfiguration were given to demonstrate the feasibility of this method. Results indicated that the release trajectories can converge to optimal solutions effectively and the concept of release companion satellites using electromagnetic forces is practicable.

  4. Release and control of hydrogen sulfide during sludge thermal drying

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Huanxin; Dai, Zhixin; Ji, Zhongqiang; Gao, Caixia; Liu, Chongxuan

    2015-04-15

    The release of hydrogen sulfide (H2S) during sludge drying is a major environmental problem because of its toxicity to human health. A series of experiments were performed to investigate the mechanisms and factors controlling the H2S release. Results of this study show that: 1) the biomass and activity of sulfate-reducing bacteria (SRB) in sludge were the major factors controlling the amount of H2S release, 2) the sludge drying temperature had an important effect on both the extent and the timing of H2S release from the sludge, and 3) decreasing sludge pH increased the H2S release. Based on the findings from this study, a new system that integrates sludge drying and H2S gas treatment was developed to reduce the amount of H2S released from sludge treatments.

  5. Redox controls on arsenic enrichment and release from aquifer sediments in central Yangtze River Basin

    Science.gov (United States)

    Schaefer, Michael V.; Guo, Xinxin; Gan, Yiqun; Benner, Shawn G.; Griffin, Aron M.; Gorski, Christopher A.; Wang, Yanxin; Fendorf, Scott

    2017-05-01

    More than 100 million people in Asia are presently exposed to groundwater with arsenic (As) concentrations exceeding the World Health Organization standard of 10 μg L-1. Arsenic contaminated groundwater within basins of the central portion of the Yangtze River has recently been reported, but the processes controlling arsenic concentrations have yet to be resolved. We examined the hydrologic and geochemical factors controlling arsenic within the Jianghan Plain, an inland sedimentary basin of the Yangtze River, where arsenic concentrations exhibit strong seasonal variability driven by surface and groundwater mixing (Schaefer et al., 2016). Hydrologic fluctuations alter redox conditions in the aquifer, leading to oscillations between arsenic/iron reduction and oxidation. Here we investigate the depth-distribution of solid and aqueous phase iron and arsenic species and, through a series of laboratory manipulations, constrain the biogeochemical processes controlling seasonal changes in groundwater arsenic concentrations. In sediment incubations from ∼20 m below the surface, where solid-phase arsenic concentrations exceed 100 mg kg-1, both unamended and glucose-amended sediment samples result in arsenic release to the aqueous phase. In situ carbon was capable of promoting As release in the sediment. In contrast, sediment batch incubations from other depths resulted in limited As release. Solid phase arsenic in the enriched zone was relatively oxidized but may become reduced over short time periods. In sediments below the As-enriched zone, glucose amendment resulted in arsenic reduction, but arsenic release to the aqueous phase was restricted by the subsequent formation of arsenic sulfide minerals. Buried sedimentary arsenic coupled with anaerobic microbial respiration of subsurface organic carbon within the Jianghan Plain aquifer leads to rapid release of As to groundwater. Arsenic release from sediments at ∼20 m depth is sufficient to explain arsenic concentrations

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

    Energy Technology Data Exchange (ETDEWEB)

    Cespedes, F.F.; Sanchez, M.V.; Garcia, S.P.; Perez, M.F. [University of Almeria, Almeria (Spain). Dept. of Inorganic Chemistry

    2007-10-15

    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, 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.

  7. Iron Release and Precipitation in Fracture Fluid-Shale Fracturing Systems

    Science.gov (United States)

    Jew, A. D.; Joe-Wong, C. M.; Harrison, A. L.; Thomas, D.; Dustin, M. K.; Brown, G. E.; Maher, K.; Bargar, J.

    2015-12-01

    Hydraulic fracturing of unconventional hydrocarbon reservoirs is important to the United States energy portfolio. Hydrocarbon production from new wells generally declines rapidly over the initial months of production. One possible reason for the decrease is the mineralization and clogging of microfracture networks proximal to propped fractures. One important but relatively unexplored class of reactions is oxidation of Fe(II) derived from Fe(II)-bearing mineral dissolution (primarily pyrite and siderite) and subsequent precipitation of Fe(III)-(oxy)hydroxides. To explore this topic, we reacted fracture fluid with sand-sized and whole rock chips from four different geological localities (Marcellus Fm., Barnett Fm., Eagle Ford Fm., and Green River Fm.) containing highly varied concentrations of clays, carbonates, and TOC. Additionally, kerogen was isolated from the Green River Fm. and reacted with fracture fluid. All the shale sands showed an initial release of Fe into solution during the first 96 hours of reaction followed by a plateau or significant drop in Fe indicating that mineral precipitation occurred. Conversely, the Fe concentrations in the kerogen reactors kept increasing throughout the 3-week experiments. The whole rock samples showed a steady increase then a plateau in Fe during the 3-weeks, indicating a slower Fe release and subsequently, slower Fe precipitation. Reactors with Marcellus Fm. Sands contained dilute HCl, water only, the fracture fluid with no headspace, and fracture fluid with no HCl. Results from these experiments show that HCl is the most important additive for the promotion of Fe release into solution. Iron oxidation is not promoted solely by O2 or organics but instead requires a combination of the two for precipitation in these systems. These results indicate that Fe redox cycling is an important and complex part of hydraulic fracturing that most likely results in production slowdown over the life of a well.

  8. Remotely Triggered Scaffolds for Controlled Release of Pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Clare Hoskins

    2013-04-01

    Full Text Available Fe3O4-Au hybrid nanoparticles (HNPs have shown increasing potential for biomedical applications such as image guided stimuli responsive drug delivery. Incorporation of the unique properties of HNPs into thermally responsive scaffolds holds great potential for future biomedical applications. Here we successfully fabricated smart scaffolds based on thermo-responsive poly(N-isopropylacrylamide (pNiPAM. Nanoparticles providing localized trigger of heating when irradiated with a short laser burst were found to give rise to remote control of bulk polymer shrinkage. Gold-coated iron oxide nanoparticles were synthesized using wet chemical precipitation methods followed by electrochemical coating. After subsequent functionalization of particles with allyl methyl sulfide, mercaptodecane, cysteamine and poly(ethylene glycol thiol to enhance stability, detailed biological safety was determined using live/dead staining and cell membrane integrity studies through lactate dehydrogenase (LDH quantification. The PEG coated HNPs did not show significant cytotoxic effect or adverse cellular response on exposure to 7F2 cells (p < 0.05 and were carried forward for scaffold incorporation. The pNiPAM-HNP composite scaffolds were investigated for their potential as thermally triggered systems using a Q-switched Nd:YAG laser. These studies show that incorporation of HNPs resulted in scaffold deformation after very short irradiation times (seconds due to internal structural heating. Our data highlights the potential of these hybrid-scaffold constructs for exploitation in drug delivery, using methylene blue as a model drug being released during remote structural change of the scaffold.

  9. Best Practices for Controlling Lead and Copper Release

    Science.gov (United States)

    Presentation draft, covering summary of current state-of-the-art knowledge for the best treatment strategies for minimizing lead release and controlling copper release. The presentation is intended to aid with compliance with the Lead and Copper Rule, but also provide a guide to...

  10. Repetitive on-demand drug release from polymeric matrices containing a macroscopic spherical iron core.

    Science.gov (United States)

    Rovers, Stefan A; Kemmere, Maartje F; Keurentjes, Jos T F; Hoogenboom, Richard

    2017-09-15

    A system for multiple on-demand drug release has been prepared that can be activated with an alternating magnetic field as external trigger. The core/shell samples have been developed based on a macroscopic spherical iron core coated with a thermoresponsive polymer, poly(styrene-stat-butyl methacrylate), containing ibuprofen as a model drug. During exposure of the samples to the magnetic field (ON state), the release rate of ibuprofen is significantly increased, up to 35 times the release rate without the magnetic field (OFF state). Using one sample or two samples in line with the magnetic field does not influence the ON/OFF ratio of the system, showing the possibility of using multiple samples to increase and tune the drug dose. Increasing the concentration of ibuprofen in the polymer layer is shown to increase the release rate in both the ON and OFF states. Increasing the size of the iron core and, consequently, decreasing the polymer thickness, was found to only increase the release rate during exposure resulting in higher ON/OFF ratios. The developed on demand drug delivery systems represents a promising development towards on demand drug delivery implants. During my chemical engineering studies, it was only during my master thesis work that I decided to continue with PhD research as I really enjoyed doing original research. When coming to the end of my PhD research under supervision of Prof. Ulrich S. Schubert, I developed the ambition to pursue an academic career. Fortunately, I got the opportunity to stay with Prof. Schubert as project leader for the Dutch Polymer Institute (DPI). Within this position, I supervised ten researchers and was able to start developing my independent research lines. Despite that I now advise students to not stay in the same laboratory, this first position allowed me to gain some initial independence and to publish a large number of papers that has been a great benefit in my further career. After two and a half years I needed a new

  11. Acupuncture Improves Intestinal Absorption of Iron in Iron-deficient Obese Patients: A Randomized Controlled Preliminary Trial

    Science.gov (United States)

    Xie, Xin-Cai; Cao, Yan-Qiang; Gao, Qian; Wang, Chen; Li, Man; Wei, Shou-Gang

    2017-01-01

    Background: Obesity has an adverse effect on iron status. Hepcidin-mediated inhibition of iron absorption in the duodenum is a potential mechanism. Iron-deficient obese patients have diminished response to oral iron therapy. This study was designed to assess whether acupuncture could promote the efficacy of oral iron supplementation for the treatment of obesity-related iron deficiency (ID). Methods: Sixty ID or ID anemia (IDA) patients with obesity were screened at Beijing Hospital of Traditional Chinese Medicine and were randomly allocated to receive either oral iron replacement allied with acupuncture weight loss treatment (acupuncture group, n = 30) or oral iron combined with sham-acupuncture treatment (control group, n = 30). Anthropometric parameters were measured and blood samples were tested pre- and post-treatment. Differences in the treatment outcomes of ID/IDA were compared between the two groups. Results: After 8 weeks of acupuncture treatment, there was a significant decrease in body weight, body mass index, waist circumference, and waist/hip circumference ratio of patients in the acupuncture group, while no significant changes were observed in the control group. Oral iron supplementation brought more obvious improvements of iron status indicators including absolute increases in serum iron (11.08 ± 2.19 μmol/L vs. 4.43 ± 0.47 μmol/L), transferrin saturation (11.26 ± 1.65% vs. 1.01 ± 0.23%), and hemoglobin (31.47 ± 1.19 g/L vs. 21.00 ± 2.69 g/L) in the acupuncture group than control group (all P acupuncture group than those in the control group. Conclusion: Acupuncture-based weight loss can enhance the therapeutic effects of iron replacement therapy for obesity-related ID/IDA through improving intestinal iron absorption, probably by downregulating the systemic leptin-hepcidin levels. PMID:28229980

  12. Preparation and evaluation of controlled release tablets of carvedilol

    Directory of Open Access Journals (Sweden)

    Varahala Setti M

    2009-01-01

    Full Text Available The objective of the present investigation is to design and evaluate controlled release tablets of carvedilol, employing synthetic polymers like polyethylene oxides, of different molecular weights as release retarding materials and to select the optimized formulation based on the pharmacokinetics of carvedilol. Matrix tablets each containing 80 mg of carvedilol were formulated employing PEO N60 K, PEO 301, and PEO 303 as release-retarding polymers and β Cyclodextrin and HP β cyclodextrin as release modulators from the matrix. Carvedilol release from the formulated tablets was very slow. Hence the release was modulated with the use of cyclodextrins. The dissolution from the matrix tablets was spread over more than 24 hours and depended on the type of polymer, its concentration and the type of cyclodextrin used. All the matrix tablets prepared using polyethylene oxides showed very good controlled release over more than 24 hours. The matrix tablets prepared using HP β cyclodextrin showed a higher dissolution rate and gave a dissolution profile that was comparable to the theoretical sustained release needed for once-a-day administration of carvedilol. The drug release mechanism from the matrix tablets was found to be quasi Fickian mechanism.

  13. Photoresponsive lipid-polymer hybrid nanoparticles for controlled doxorubicin release

    Science.gov (United States)

    Yao, Cuiping; Wu, Ming; Zhang, Cecheng; Lin, Xinyi; Wei, Zuwu; Zheng, Youshi; Zhang, Da; Zhang, Zhenxi; Liu, Xiaolong

    2017-06-01

    Currently, photoresponsive nanomaterials are particularly attractive due to their spatial and temporal controlled drug release abilities. In this work, we report a photoresponsive lipid-polymer hybrid nanoparticle for remote controlled delivery of anticancer drugs. This hybrid nanoparticle comprises three distinct functional components: (i) a poly(D,L-lactide-co-glycolide) (PLGA) core to encapsulate doxorubicin; (ii) a soybean lecithin monolayer at the interface of the core and shell to act as a molecular fence to prevent drug leakage; (iii) a photoresponsive polymeric shell with anti-biofouling properties to enhance nanoparticle stability, which could be detached from the nanoparticle to trigger the drug release via a decrease in the nanoparticle’s stability under light irradiation. In vitro results revealed that this core-shell nanoparticle had excellent light-controlled drug release behavior (76% release with light irradiation versus 10% release without light irradiation). The confocal microscopy and flow cytometry results also further demonstrated the light-controlled drug release behavior inside the cancer cells. Furthermore, a CCK8 assay demonstrated that light irradiation could significantly improve the efficiency of killing cancer cells. Meanwhile, whole-animal fluorescence imaging of a tumor-bearing mouse also confirmed that light irradiation could trigger drug release in vivo. Taken together, our data suggested that a hybrid nanoparticle could be a novel light controlled drug delivery system for cancer therapy.

  14. Controlled Release of Imidacloprid from Poly Styrene-Diacetone - Nanoformulation

    Science.gov (United States)

    Qian, Kun; Guo, Yanzhen; He, Lin

    2012-01-01

    Imidacloprid is a neonicotinoids insecticide, which is important for the cash crops such as tomato, rape and so on. The conventional formulation does not only increase the loss of pesticide but also leads to environmental pollution. Controlled-release formulations of pesticide are highly desirable not only for attaining the most effective utilization of the pesticide, but also for reducing environmental pollution. Pesticide imidacloprid was incorporated in poly (styrene-diacetone crylamide)-based formulation to obtain controlled release properties, and the imidacloprid nanocontrolled release formulation was characterized by infrared (IR) and field emission scanning electron microscope (FESEM). Factors related to loading efficiency, swelling and release behaviors of the formulation were investigated. It showed that the loading efficiency could reach about 40% (w/w). The values for the diffusion exponent "n" were in the range of 0.31-0.58, which indicated that the release of imidacloprid was diffusion-controlled. The time taken for 50% of the active ingredient to be released into water, T50, was also calculated for the comparison of formulations in different conditions. The results showed that the formulation with higher temperature and more diacetone crylamide had lower value of T50, which means a quicker release of the active ingredient. This study highlighted some pieces of evidence that improved pesticide incorporation and slower release were linked to potential interactions between the pesticide and the polymer.

  15. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    National Research Council Canada - National Science Library

    Sempeho, Siafu Ibahati; Kim, Hee Taik; Mubofu, Egid; Pogrebnoi, Alexander; Shao, Godlisten; Hilonga, Askwar

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion...

  16. Trigger release liposome systems: local and remote controlled delivery?

    Science.gov (United States)

    Bibi, Sagida; Lattmann, E; Mohammed, Afzal R; Perrie, Yvonne

    2012-01-01

    Target-specific delivery has become an integral area of research in order to increase bioavailability and reduce the toxic effects of drugs. As a drug-delivery option, trigger-release liposomes offer sophisticated targeting and greater control-release capabilities. These are broadly divided into two categories; those that utilise the local environment of the target site where there may be an upregulation in certain enzymes or a change in pH and those liposomes that are triggered by an external physical stimulus such as heat, ultrasound or light. These release mechanisms offer a greater degree of control over when and where the drug is released; furthermore, targeting of diseased tissue is enhanced by incorporation of target-specific components such as antibodies. This review aims to show the development of such trigger release liposome systems and the current research in this field.

  17. Nutrients Release from a Novel Gel-Based Slow/Controlled Release Fertilizer

    OpenAIRE

    Ding, H.; Y. S. Zhang; Li, W. H.; Zheng, X. Z.; Wang, M. K.; Tang, L. N.; Chen, D. L.

    2016-01-01

    A novel gel-based slow/controlled release fertilizer (G-CRF) was developed, which was produced by combining various natural, seminatural, and/or synthetic organic macromolecule materials and natural inorganic mineral with conventional NPK fertilizers. Its nutrient release characteristics were studied to compare with conventional fertilizers through the soil column leaching method. The influences of soil factors, including temperature, pH, water, and nutrient contents in the G-CRF on nutrient ...

  18. Controlling Liquid Release by Compressing Electrospun Nanowebs

    Directory of Open Access Journals (Sweden)

    K.G. Kornev

    2009-09-01

    Full Text Available Electrospun nanowebs with pores ranging from nanometers to micrometers, constitute new materials with enhanced absorbency and ability to retain liquids in pores for a long period of time. These materials can be used as nanofluidic probes collecting minute amount of liquids. However, extraction of liquids from nanofibrous materials presents a problem: menisci in the interfiber pores create very high suction pressure which holds the liquid inside the material. This problem can be resolved if the probe is completely filled with the liquid: menisci at the probe edges become flat to establish a pressure equilibrium with the atmosphere. Therefore, one can take advantage of the nanoweb softness and extract liquid by mechanically deforming the nanowebs. We show that the liquid-saturated nanowebs follow the Voigt-type rheology upon loading. We theoretically explain this behavior and derive the relations between the Voigt phenomenological parameters, nanoweb permeability and compression modulus. We show that the limiting deformations follow the Hooke’s law which assumes linear relation between the extracted volume of liquid and the applied load. Because of this predictable behavior, the nanoweb probes can be engineered to release minute liquid doses upon compression. The developed experimental methodology can be used for characterization of nanostructured materials which otherwise impossible to analyze by using the existing instruments.

  19. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present...... and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...

  20. Nanoporous Silicified Phospholipids and Application to Controlled Glycolic Acid Release

    Directory of Open Access Journals (Sweden)

    Kang SangHwa

    2008-01-01

    Full Text Available Abstract This work demonstrates the synthesis and characterization of novel nanoporous silicified phospholipid bilayers assembled inorganic powders. The materials are obtained by silicification process with silica precursor at the hydrophilic region of phospholipid bilayers. This process involves the co-assembly of a chemically active phospholipids bilayer within the ordered porosity of a silica matrix and holds promise as a novel application for controlled drug release or drug containers with a high level of specificity and throughput. The controlled release application of the synthesized materials was achieved to glycolic acid, and obtained a zero-order release pattern due to the nanoporosity.

  1. [Drug release system controlled by near infrared light].

    Science.gov (United States)

    Niidome, Takuro

    2013-01-01

    Gold nanorods have absorption bands in the near-infrared region; in this spectral range, light penetrates deeply into tissues. The absorbed light energy is converted into heat by gold nanorods. This is the so-called photothermal effect. Gold nanorods are therefore expected to act not only as thermal converters for photothermal therapy, but also as controllers for drug-release systems responding to irradiation with near-infrared light. To achieve a controlled-release system that could be triggered by light irradiation, the gold nanorods were modified with double-stranded DNA (dsDNA). When the dsDNA-modified gold nanorods were irradiated with near-infrared light, single-stranded DNA (ssDNA) was released from the gold nanorods because of the photothermal effect. The release of ssDNA was also observed in tumors grown on mice after near-infrared light irradiation. We also proposed a different controlled-release system responding to near-infrared light. Gold nanorods were modified with polyethylene glycol (PEG) through Diels-Alder cycloadducts. When the gold nanorods were irradiated with near-infrared light, the PEG chains were released from the gold nanorods because of the retro Diels-Alder reaction induced by the photothermal effect. Such controlled-release systems triggered by near-infrared light irradiation will be expanded for gold nanorod drug delivery system applications.

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

    Science.gov (United States)

    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.

  3. Assembly of bio-nanoparticles for double controlled drug release.

    Directory of Open Access Journals (Sweden)

    Wei Huang

    Full Text Available A critical limiting factor of chemotherapy is the unacceptably high toxicity. The use of nanoparticle based drug carriers has significantly reduced the side effects and facilitated the delivery of drugs. Source of the remaining side effect includes (1 the broad final in vivo distribution of the administrated nanoparticles, and (2 strong basal drug release from nanoparticles before they could reach the tumor. Despite the advances in pH-triggered release, undesirable basal drug release has been a constant challenge under in vivo conditions. In this study, functionalized single walled carbon nanohorn supported immunoliposomes were assembled for paclitaxel delivery. The immunoliposomes were formulated with polyethylene glycol, thermal stable and pH sensitive phospholipids. Each nanohorn was found to be encapsulated within one immunoliposome. Results showed a highly pH dependent release of paclitaxel in the presence of serum at body temperature with minimal basal release under physiological conditions. Upon acidification, paclitaxel was released at a steady rate over 30 days with a cumulative release of 90% of the loaded drug. The drug release results proved our hypothesized double controlled release mechanism from the nanoparticles. Other results showed the nanoparticles have doubled loading capacity compared to that of traditional liposomes and higher affinity to breast cancer cells overexpressing Her2 receptors. Internalized nanoparticles were found in lysosomes.

  4. Control of chilling tendency in grey cast iron reuse

    Directory of Open Access Journals (Sweden)

    Saliu Ojo Seidu

    2013-02-01

    Full Text Available In grey cast iron remelt and recycling, white iron can result in the cast product if careful control of the chilling tendency is not ensured. Many jobbing foundries are constrained in furnace types and available foundry additives that the operation always results in white irons. This study is towards ensuring grey iron is reproduced from cast iron scrap auto engine blocks, when using a diesel fired rotary furnace and a FeSi alloy for structural modification (inoculation. With varying addition rate of the FeSi alloy to the tapped molten metal, chill wedge tests were performed on two different wedge samples of type W (according to ASTM A367- wedge test with cooling modulus of 0.45 cm (W3½ and 0.54 cm (W4. The carbon equivalents for the test casts were within hypoeutectic range (3.85 wt. (% to 4.11 wt. (%. In the W4 wedge sample, at 2.0 wt. (% addition rate of the FeSi alloy, the relative clear chill was totally reduced to zero from 19.76%, while the relative mottled chill was brought down to 9.59% from 33.71%. The microstructure from the cast at this level of addition was free of carbidic phases; it shows randomly oriented graphite flakes evenly distributed in the iron matrix. Hardness assessment shows that increasing rate of FeSi addition results in decreasing hardness, with maximum effect at 2.0 wt. (% addition. With equivalent aspect ratio (cooling modulus in a target cast product, this addition rate for this FeSi alloy under this furnace condition will attain graphitized microstructure in the cast product.

  5. Control of chilling tendency in grey cast iron reuse

    Directory of Open Access Journals (Sweden)

    Saliu Ojo Seidu

    2012-01-01

    Full Text Available In grey cast iron remelt and recycling, white iron can result in the cast product if careful control of the chilling tendency is not ensured. Many jobbing foundries are constrained in furnace types and available foundry additives that the operation always results in white irons. This study is towards ensuring grey iron is reproduced from cast iron scrap auto engine blocks, when using a diesel fired rotary furnace and a FeSi alloy for structural modification (inoculation. With varying addition rate of the FeSi alloy to the tapped molten metal, chill wedge tests were performed on two different wedge samples of type W (according to ASTM A367- wedge test with cooling modulus of 0.45 cm (W3½ and 0.54 cm (W4. The carbon equivalents for the test casts were within hypoeutectic range (3.85 wt. (% to 4.11 wt. (%. In the W4 wedge sample, at 2.0 wt. (% addition rate of the FeSi alloy, the relative clear chill was totally reduced to zero from 19.76%, while the relative mottled chill was brought down to 9.59% from 33.71%. The microstructure from the cast at this level of addition was free of carbidic phases; it shows randomly oriented graphite flakes evenly distributed in the iron matrix. Hardness assessment shows that increasing rate of FeSi addition results in decreasing hardness, with maximum effect at 2.0 wt. (% addition. With equivalent aspect ratio (cooling modulus in a target cast product, this addition rate for this FeSi alloy under this furnace condition will attain graphitized microstructure in the cast product.

  6. The Effect of Iron Salt on Anaerobic Digestion and Phosphate Release to Sludge Liquor

    Directory of Open Access Journals (Sweden)

    Svetlana Ofverstrom

    2011-12-01

    Full Text Available Iron salts are used at wastewater treatment plants (WWTPs for several reasons: for removing chemical phosphorus, preventing from struvite formation and reducing the content of hydrogen sulfide (H2S in biogas. Anaerobic digestion is a common scheme for sludge treatment due to producing biogas that could be used as biofuel. Laboratory analysis has been carried out using anaerobic digestion model W8 (Armfield Ltd, UK to investigate any possible effect of adding FeCl3 on the anaerobic digestion of primary sludge (PS and waste activated sludge (WAS mixture as well as on releasing phosphates to digested sludge liquor. The obtained results showed that FeCl3 negatively impacted the anaerobic digestion process by reducing the volume of produced biogas. Fe-dosed sludge (max produced 30% less biogas. Biogas production from un-dosed and Fe-dosed sludge (min was similar to the average of 1.20 L/gVSfed. Biogas composition was not measured during the conducted experiments. Phosphorus content in sludge liquor increased at an average of 38% when digesting sludge without ferric chloride dosing. On the contrary, phosphate content in sludge liquor from digested Fe-dosed sludge decreased by approx. 80%.

  7. Fabrication of ultrathin polyelectrolyte fibers and their controlled release properties.

    Science.gov (United States)

    Chunder, Anindarupa; Sarkar, Sourangsu; Yu, Yingbo; Zhai, Lei

    2007-08-01

    Ultrathin fibers comprising 2-weak polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) were fabricated using the electrospinning technique. Methylene blue (MB) was used as a model drug to evaluate the potential application of the fibers for drug delivery. The release of MB was controlled in a nonbuffered medium by changing the pH of the solution. The sustained release of MB in a phosphate buffered saline (PBS) solution was achieved by constructing perfluorosilane networks on the fiber surfaces as capping layers. Temperature controlled release of MB was obtained by depositing temperature sensitive PAA/poly(N-isopropylacrylamide) (PNIPAAM) multilayers onto the fiber surfaces. The controlled release of drugs from electrospun fibers have potential applications as drug carriers in biomedical science.

  8. Controlled release implants based on cast lipid blends.

    Science.gov (United States)

    Kreye, F; Siepmann, F; Zimmer, A; Willart, J F; Descamps, M; Siepmann, J

    2011-05-18

    The aim of this study was to use lipid:lipid blends as matrix formers in controlled release implants. The systems were prepared by melting and casting and thoroughly characterized before and after exposure to the release medium. Based on the experimental results, a mechanistic realistic mathematical model was used to get further insight into the underlying drug release mechanisms. Importantly, broad spectra of drug release patterns could be obtained by simply varying the lipid:lipid blend ratio in implants based on Precirol ATO 5 (glyceryl palmitostearate):Dynasan 120 (hardened soybean oil) mixtures loaded with propranolol hydrochloride. Release periods ranging from a few days up to several months could be provided. Interestingly, the drug release rate monotonically decreased with increasing Dynasan 120 content, except for implants containing about 20-25% Precirol, which exhibited surprisingly high release rates. This could be attributed to the incomplete miscibility of the two lipids at these blend ratios: DSC thermograms showed phase separation in these systems. This is likely to cause differences in the implants' microstructure, which determines the mobility of water and dissolved drug as well as the mechanical stability of the systems. Purely diffusion controlled drug release was only observed at Precirol ATO 5 contents around 5-10%. In all other cases, limited drug solubility effects or matrix former erosion are also expected to play a major role. Thus, lipid:lipid blends are very interesting matrix formers in controlled release implants. However, care must be taken with respect to the mutual miscibility of the compounds: in case of phase separation, surprisingly high drug release rates might be observed.

  9. Iron Phosphate Coating:A Novel Approach to Controlling Pyrite Oxidation

    Institute of Scientific and Technical Information of China (English)

    HUANGXIAO; V.P.EVANGELOU

    1997-01-01

    A novel coating technique was develped for controlling pyrite oxidation .The technique involved leaching pyrite particles with a solution containing low concentrations of phosphate and hydrogen peroxide.During the leaching rpocess,the iron released from pyrite by hydrogen proxide was precipitated by phosphate as a ferric phosphate coating .This coating was shown to be able to effectively prevent pyirte from oxidation and it could be established at the expense of only surface portions of pyrite.The emergence of this technique could provide a unique potential route for abating acid mine draingage and reclaiming sulfide-containing degraded mining land.

  10. Modeling controlled nutrient release from polymer coated fertilizers: diffusion release from single granules.

    Science.gov (United States)

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A comprehensive model describing the complex and "non-Fickian" (mathematically nonlinear) nature of the release from single granules of membrane coated, controlled release fertilizers (CRFs) is proposed consisting of three stages: i. a lag period during which water penetrates the coating of the granule dissolving part of the solid fertilizer in it ii. a period of linear release during which water penetration into and release out occur concomitantly while the total volume of the granules remains practically constant; and iii. a period of "decaying release", starting as the concentration inside the granule starts to decrease. A mathematical model was developed based on vapor and nutrient diffusion equations. The model predicts the release stages in terms of measurable geometrical and chemophysical parameters such as the following: the product of granule radius and coating thickness, water and solute permeability, saturation concentration of the fertilizer, and its density. The model successfully predicts the complex and "sigmoidal" pattern of release that is essential for matching plant temporal demand to ensure high agronomic and environmental effectiveness. It also lends itself to more complex statistical formulations which account for the large variability within large populations of coated CRFs and can serve for further improving CRF production and performance.

  11. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-04-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued to guarantee the controlled release of cargo at a specific time and with an accurate amount. Upon applying different stimuli such as light, magnetic field, heat, pH change, enzymes or redox, functional materials change their physicochemical properties through physical transformation or chemical reactions, allowing the release of payload agents on demand. This dissertation studied three stimuli-responsive membrane systems for controlled release from films of macro sizes to microcapsules of nano sizes. The first membrane system is a polymeric composite film which can decrease and sustain diffusion upon light irradiation. The photo-response of membranes is based on the photoreaction of cinnamic derivatives. The second one is composite membrane which can improve diffusion upon heating. The thermo-response of membranes comes from the volume phase transition ability of hydrogels. The third one is microcapsule which can release encapsulated agents upon light irradiation. The photo-response of capsules results from the photoreaction of nitrobenzyl derivatives. The study on these membrane systems reveals that stimuli-responsive release can be achieved by utilizing different functional materials on either macro or micro level. Based on the abundant family of smart materials, designing and fabricating stimuli-responsive systems shall lead to various advanced release processes on demand for biomedical applications.

  12. Perception and Homeostatic Control of Iron in the Rhizobia and Related Bacteria.

    Science.gov (United States)

    O'Brian, Mark R

    2015-01-01

    Iron is an essential nutrient, but it can also be toxic. Therefore, iron homeostasis must be strictly regulated. Transcriptional control of iron-dependent gene expression in the rhizobia and other taxa of the Alphaproteobacteria is fundamentally different from the Fur paradigm in Escherichia coli and other model systems. Rather than sense iron directly, the rhizobia employ the iron response regulator (Irr) to monitor and respond to the status of an iron-dependent process, namely, heme biosynthesis. This novel control mechanism allows iron homeostasis to be integrated with other cellular processes, and it permits differential control of iron regulon genes in a manner not readily achieved by Fur. Moreover, studies of Irr have defined a role for heme in conditional protein stability that has been subsequently described in eukaryotes. Finally, Irr-mediated control of iron metabolism may reflect a cellular strategy that accommodates a greater reliance on manganese.

  13. Development of controlled release tablet by optimizing HPMC: consideration of theoretical release and RSM.

    Science.gov (United States)

    Pani, Nihar R; Nath, Lila K

    2014-04-15

    The objective of the study was to develop controlled release tablets of nateglinide, a meglitinide derivative anti-diabetic drug, considering theoretical release profile and response surface methodology (RSM). 3(2) factorial design was utilized to optimize concentration of hydroxylpropylmethylcellulose (HPMC) K15M and K100M to obtain the desired responses (drug release at one and six hours). Theoretical release profile of drug for controlled release formulation was calculated and considered as reference for the determination of similarity factor (f2) and desimilarity factor (f1). RSM, f2 and f1 were used to select the optimum formulation. Formulation containing HPMC K15M (5%) and HPMC K100M (15%) was found optimum with desired responses with f2=86.05 and drug release profile followed zero order kinetics. Excipients used were compatible with drug, confirmed initially through DSC and IST study. The optimization of experiments was validated and optimum formulation was passed the stability study. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Controlled release of tocopherols from polymer blend films

    Science.gov (United States)

    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

  15. Controlled release of curcumin from poly(HEMA-MAPA) membrane.

    Science.gov (United States)

    Caka, Müşerref; Türkcan, Ceren; Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2017-05-01

    In this work, poly(HEMA-MAPA) membranes were prepared by UV-polymerization technique. These membranes were characterized by SEM, FTIR, and swelling studies. Synthesized membranes had high porous structure. These membranes were used for controlled release of curcumin which is already used as folk remedy and used as drug for some certain diseases and cancers. Curcumin release was investigated for various pHs and temperatures. Optimum drug release yield was found to be as 70% at pH 7.4 and 37 °C within 2 h period. Time-depended release of curcumin was also investigated and its slow release from the membrane demonstrated within 48 h.

  16. Biodegradable Magnetic Silica@Iron Oxide Nanovectors with Ultra-Large Mesopores for High Protein Loading, Magnetothermal Release, and Delivery

    KAUST Repository

    Omar, Haneen

    2016-11-29

    The delivery of large cargos of diameter above 15 nm for biomedical applications has proved challenging since it requires biocompatible, stably-loaded, and biodegradable nanomaterials. In this study, we describe the design of biodegradable silica-iron oxide hybrid nanovectors with large mesopores for large protein delivery in cancer cells. The mesopores of the nanomaterials spanned from 20 to 60 nm in diameter and post-functionalization allowed the electrostatic immobilization of large proteins (e.g. mTFP-Ferritin, ~ 534 kDa). Half of the content of the nanovectors was based with iron oxide nanophases which allowed the rapid biodegradation of the carrier in fetal bovine serum and a magnetic responsiveness. The nanovectors released large protein cargos in aqueous solution under acidic pH or magnetic stimuli. The delivery of large proteins was then autonomously achieved in cancer cells via the silica-iron oxide nanovectors, which is thus a promising for biomedical applications.

  17. Effect Of Iron Supplementation In Breastfed Infants: A Randomized Controlled Study

    OpenAIRE

    seyma Kayali; Nilgun Caylan; Gonca Yilmaz; Selim Gokce; Candemir Karacan

    2016-01-01

    Aim The purpose of this study was to investigate the efficacy of daily iron supplementation for prevention of iron-deficiency and iron-deficiency anemia in healthy exclusively breast-fed infants and the factors affecting development of iron-deficiency anemia. Methods This study was conducted with 65 infants (35 in the iron supplemented group and 30 in the non-supplemented controls) between January 2009-March 2010. Detailed physical examination of all infants was carried out at ages...

  18. Nutrients Release from a Novel Gel-Based Slow/Controlled Release Fertilizer

    Directory of Open Access Journals (Sweden)

    H. Ding

    2016-01-01

    Full Text Available A novel gel-based slow/controlled release fertilizer (G-CRF was developed, which was produced by combining various natural, seminatural, and/or synthetic organic macromolecule materials and natural inorganic mineral with conventional NPK fertilizers. Its nutrient release characteristics were studied to compare with conventional fertilizers through the soil column leaching method. The influences of soil factors, including temperature, pH, water, and nutrient contents in the G-CRF on nutrient release, were also investigated through soil-water incubation method. These results indicated that the G-CRF had better effect on controlling release of N, P, and K nutrients, and the effect was more efficient when soil-water content was lower than 45% (w/w, temperature was below 35°C, and soil pH was in the range from weak acid to neutral. In addition, considering the effect of controlling nutrient release and cost of the materials in the G-CRF, it is recommended that the most feasible NPK nutrient contents in the G-CRF ranged from 30 to 35%.

  19. Magnetic molecularly imprinted polymer for aspirin recognition and controlled release

    Science.gov (United States)

    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.

  20. Design and characterization of controlled release tablet of metoprolol

    Directory of Open Access Journals (Sweden)

    Gautam Singhvi

    2012-01-01

    Full Text Available Metoprolol succinate is a selective beta-adrenergic receptor blocker useful in treatment of hypertension, angina and heart failure. The purpose of the present work was to design and evaluate controlled release matrix type tablet of Metoprolo succinate using HPMC K15M and Eudragit (RLPO and RSPO as a matrix forming agents. Effect of various polymer alone and combinations were studied in pH 1.2 buffer using USP type II paddle at 50 rpm. HPMC was used to form firm gel with Eudragit polymer. Formulation with Equal proportion (1:1 of Eudragit RSPO and RLPO showed optimum drug release t50 =7 hrs and t100 =16 hrs indicate optimum permeability for drug release from matrix. The drug release mechanism was predominantly found to be Non-Fickian diffusion controlled.

  1. Magnetic molecularly imprinted polymer for aspirin recognition and controlled release

    Energy Technology Data Exchange (ETDEWEB)

    Kan Xianwen; Geng Zhirong; Zhao Yao; Wang Zhilin; Zhu Junjie [State Key Laboratory of Coordination Chemistry, MOE Key Lab of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 22 Hankou Road, Nanjing 210093 (China)], E-mail: wangzl@nju.edu.cn, E-mail: jjzhu@nju.edu.cn

    2009-04-22

    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 Fe{sub 3}O{sub 4} 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.

  2. FERLENT - a controlled release fertilizer produced from a polymer material

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The possibility to use release controlled fertilizers in the agriculture of the tropical countries is more important than in the agriculture of the countries of the template regions. In this context, this work purpose the development of a new Fertilizer of Controlled Release named FERLENT, which was obtained starting from a polymeric material, under controlled conditions which allowed to corroborate the adjustment of the synthesis parameters under the modulate of nutrients liberation. It was characterized by, Scanning Microscopy Electron (SEM), Thermogravimetric analysis (TGA), Nuclear Magnetic Resonance (NMR) and infrared spectroscopy (FTIR). (author)

  3. Chemical analysis of substrates with controlled release fertilizer

    NARCIS (Netherlands)

    Kreij, de C.

    2004-01-01

    Water-soluble fertilizer added to media containing controlled release fertilizer cannot be analysed with the 1:1.5 volume water extract, because the latter increases the element content in the extract. During storage and stirring or mixing the substrate with the extractant, part of the controlled re

  4. Controlled release fertilizer improves quality of container longleaf pine seedlings

    Science.gov (United States)

    R. Kasten Dumroese; Jeff Parkhurst; James P. Barnett

    2005-01-01

    In an operational trial, increasing the amount of nitrogen (N) applied to container longleaf pine seedlings by incorporating controlled release fertilizer (CRF) into the media improved seedling growth and quality. Compared with control seedlings that received 40 mg N, seedlings receiving 66 mg N through CRF supplemented with liquid fertilizer had needles that were 4 in...

  5. Chemical analysis of substrates with controlled release fertilizer

    NARCIS (Netherlands)

    Kreij, de C.

    2004-01-01

    Water-soluble fertilizer added to media containing controlled release fertilizer cannot be analysed with the 1:1.5 volume water extract, because the latter increases the element content in the extract. During storage and stirring or mixing the substrate with the extractant, part of the controlled re

  6. [Controlled release hydromorphone for visceral, somatic and neuropathic pain].

    Science.gov (United States)

    Alon, E; Cachin, C

    2010-03-03

    The aim of this multicentre, longitudinal investigation was to document the efficacy and tolerability profiles of controlled release hydromorphone in patients with heavy visceral, somatic or neuropathic pain under practical conditions. To this end, a prospective observational study was conducted in 57 centres in Switzerland, on a total of 196 patients. After an average of 43 days of treatment with controlled release hydromorphone, the intensity of momentary pain dropped by 46.5% and that of maximum pain dropped by 41.3%, with the efficacy of the treatment being most pronounced with visceral and somatic pain. At the same time, the prevalence of sleep disorders as a result of pain decreased from initially 86.7% to 21.0%. Controlled release hydromorphone was excellently tolerated in this group of elderly (average age 70.6 years), multimorbid pain patients receiving various medical treatments (average of 2.4 drugs in addition to pain medication), even in the voluntary long-term extension study of up to 96 days. No medical interactions were reported. Six and thirteen weeks after introducing the treatment, 89.8% and 85.2%, respectively, were still taking controlled release hydromorphone. Controlled release hydromorphone is a recommendable option for practical treatment of heavy and extremely heavy pain of various genesis.

  7. Antimicrobial beeswax coated polylactide films with silver control release capacity.

    Science.gov (United States)

    Martínez-Abad, Antonio; Lagarón, Jose Maria; Ocio, María Jose

    2014-03-17

    Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrated a high burst release which in some instances implied surpassing some current migration restrictions (beeswax layer allowed a sustained release of the antimicrobial compound. Increasing the thickness of the beeswax layer resulted in an increase in the water barrier properties of the films while reducing the relatively constant values of sustained release. Antimicrobial performance was correlated with the release of silver ions, indicating threshold concentrations for biocide action of <6μg/L and 9-14μg/L for surface contact and in liquid media, respectively. Either by surface contact or by immersion in growth medium or vegetable soup, the coated films displayed a strong bactericidal effect against Salmonella enterica. The application of this functional barrier thus offers the possibility of tuning the release profiles of the films to suit a specific application and puts forth the possible suitability of these materials for food packaging or other migration sensitive applications.

  8. The Organization of Controller Motifs Leading to Robust Plant Iron Homeostasis.

    Directory of Open Access Journals (Sweden)

    Oleg Agafonov

    Full Text Available Iron is an essential element needed by all organisms for growth and development. Because iron becomes toxic at higher concentrations iron is under homeostatic control. Plants face also the problem that iron in the soil is tightly bound to oxygen and difficult to access. Plants have therefore developed special mechanisms for iron uptake and regulation. During the last years key components of plant iron regulation have been identified. How these components integrate and maintain robust iron homeostasis is presently not well understood. Here we use a computational approach to identify mechanisms for robust iron homeostasis in non-graminaceous plants. In comparison with experimental results certain control arrangements can be eliminated, among them that iron homeostasis is solely based on an iron-dependent degradation of the transporter IRT1. Recent IRT1 overexpression experiments suggested that IRT1-degradation is iron-independent. This suggestion appears to be misleading. We show that iron signaling pathways under IRT1 overexpression conditions become saturated, leading to a breakdown in iron regulation and to the observed iron-independent degradation of IRT1. A model, which complies with experimental data places the regulation of cytosolic iron at the transcript level of the transcription factor FIT. Including the experimental observation that FIT induces inhibition of IRT1 turnover we found a significant improvement in the system's response time, suggesting a functional role for the FIT-mediated inhibition of IRT1 degradation. By combining iron uptake with storage and remobilization mechanisms a model is obtained which in a concerted manner integrates iron uptake, storage and remobilization. In agreement with experiments the model does not store iron during its high-affinity uptake. As an iron biofortification approach we discuss the possibility how iron can be accumulated even during high-affinity uptake.

  9. Sintering of wax for controlling release from pellets.

    Science.gov (United States)

    Singh, Reena; Poddar, S S; Chivate, Amit

    2007-09-14

    The purpose of the present study was to investigate incorporation of hydrophobic (ie, waxy) material into pellets using a thermal sintering technique and to evaluate the pellets in vitro for controlled release. Pellets prepared by extrusion-spheronization technology were formulated with a water-soluble drug, microcrystalline cellulose, and carnauba wax. Powdered carnauba wax (4%-20%) prepared by grinding or by emulsification was studied with an attempt to retard the drug release. The inclusion of ground or emulsified carnauba wax did not sustain the release of theophylline for more than 3 hours. Matrix pellets of theophylline prepared with various concentrations of carnauba wax were sintered thermally at various times and temperatures. In vitro drug release profiles indicated an increase in drug release retardation with increasing carnauba wax concentration. Pellets prepared with ground wax showed a higher standard deviation than did those prepared with emulsified wax. There was incomplete release at the end of 12 hours for pellets prepared with 20% ground or emulsified wax. The sintering temperature and duration were optimized to allow for a sustained release lasting at least 12 hours. The optimized temperature and duration were found to be 100 degrees C and 140 seconds, respectively. The sintered pellets had a higher hydrophobicity than did the unsintered pellets. Scanning electron micrographs indicated that the carnauba wax moved internally, thereby increasing the surface area of wax within the pellets.

  10. Intestinal ferritin H is required for an accurate control of iron absorption.

    Science.gov (United States)

    Vanoaica, Liviu; Darshan, Deepak; Richman, Larry; Schümann, Klaus; Kühn, Lukas C

    2010-09-08

    To maintain appropriate body iron levels, iron absorption by the proximal duodenum is thought to be controlled by hepcidin, a polypeptide secreted by hepatocytes in response to high serum iron. Hepcidin limits basolateral iron efflux from the duodenal epithelium by binding and downregulating the intestinal iron exporter ferroportin. Here, we found that mice with an intestinal ferritin H gene deletion show increased body iron stores and transferrin saturation. As expected for iron-loaded animals, the ferritin H-deleted mice showed induced liver hepcidin mRNA levels and reduced duodenal expression of DMT1 and DcytB mRNA. In spite of these feedback controls, intestinal ferroportin protein and (59)Fe absorption were increased more than 2-fold in the deleted mice. Our results demonstrate that hepcidin-mediated regulation alone is insufficient to restrict iron absorption and that intestinal ferritin H is also required to limit iron efflux from intestinal cells.

  11. Controlled release of chlorhexidine from UDMA-TEGDMA resin.

    Science.gov (United States)

    Anusavice, K J; Zhang, N-Z; Shen, C

    2006-10-01

    Chlorhexidine salts are available in various formulations for dental applications. This study tested the hypothesis that the release of chlorhexidine from a urethane dimethacrylate and triethylene glycol dimethacrylate resin system can be effectively controlled by the chlorhexidine diacetate content and pH. The filler concentrations were 9.1, 23.1, or 33.3 wt%, and the filled resins were exposed to pH 4 and pH 6 acetate buffers. The results showed that Fickian diffusion was the dominant release mechanism. The rates of release were significantly higher in pH 4 buffer, which was attributed to the increase of chlorhexidine diacetate solubility at lower pH. The higher level of filler loading reduced the degree of polymerization, leading to a greater loss of organic components and higher chlorhexidine release rates.

  12. Press-coating of immediate release powders onto coated controlled release tablets with adhesives.

    Science.gov (United States)

    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.

  13. Iron regulatory proteins control a mucosal block to intestinal iron absorption.

    Science.gov (United States)

    Galy, Bruno; Ferring-Appel, Dunja; Becker, Christiane; Gretz, Norbert; Gröne, Hermann-Josef; Schümann, Klaus; Hentze, Matthias W

    2013-03-28

    Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs) that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated "mucosal block." We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin "mucosal block" and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  14. Iron Regulatory Proteins Control a Mucosal Block to Intestinal Iron Absorption

    Directory of Open Access Journals (Sweden)

    Bruno Galy

    2013-03-01

    Full Text Available Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated “mucosal block.” We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin “mucosal block” and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  15. FbpA iron storage and release are governed by periplasmic microenvironments.

    Science.gov (United States)

    Sensoy, Ozge; Atilgan, Ali Rana; Atilgan, Canan

    2017-02-22

    Ferric binding protein (FbpA) is part of an elaborate iron piracy mechanism evolved in Gram-negative bacteria, shuttling iron in the periplasmic space, from the outer to the cytoplasmic membrane side. We address how the dissociation process of iron is facilitated, since the binding constant of iron is on the order of 10(18) M(-1) at 6.5 pH and 200 mM ionic strength (IS). We monitor the conformational preferences of FbpA by extensive molecular dynamics (MD) simulations under conditions where IS, charge states of iron coordinating tyrosines and pH are varied, as well as when a mutation is introduced at an allosteric site. Steered MD is utilized to predict the binding affinity of iron. After triggering lobe opening by changing the charge states of tyrosines, the conformations adopted and the iron binding affinity still depend on pH, IS and allosteric interactions. To relate the observed conformational changes to the environmental conditions that might be encountered in the periplasmic space, we offer a plausible model that couples electrostatic potential distribution to the mechanical motions invoked. Although low pH/IS and allosteric perturbations decrease the affinity of iron, it remains high for spontaneous dissociation. However, the conformational changes modulated by the environmental conditions expose iron for chelation. Our study provides a quantitative dimension and molecular details to interpret the contribution of possible environmental conditions present in the periplasmic space to iron dissociation from FbpA, opening up the opportunity of modulating function via allosteric mutations or altering environmental conditions, thus offering a new route to developing strategies towards antibiotic resistance by targeting nutritional requirements.

  16. Light element controlled iron isotope fractionation in planetary cores

    Science.gov (United States)

    Shahar, A.; Hillgren, V. J.; Horan, M. F.; Duke, L.; Mock, T. D.

    2013-12-01

    Using iron isotope fractionations measured in planetary and meteorite samples to trace planetary differentiation or formation has yielded contradictory results. Iron from high-Ti lunar basalts is more enriched in 57Fe/54Fe than mantle-derived terrestrial samples, in contrast to the isotopic similarity for almost every other element between the Earth and Moon. SNC (Shergottite, Nakhlite, Chassigny) and HED (Howardite, Eucrite, Diogenite) meteorites, which are thought to be derived from the mantles of Mars and Vesta, respectively, show no isotopic fractionation relative to chondrites. While the Bulk Silicate Earth (BSE) value is debated, recent work has shown effectively that basalts (mid-ocean ridge basalts, terrestrial basalts, and ocean island basalts) are enriched in 57Fe/54Fe relative to chondrites, but the causes of that fractionation are unclear (Craddock et al. 2013). Angrites, basaltic achondrite meteorites, also show enrichment in δ57Fe (Wang et al. 2012). Possible mechanisms include high-pressure core formation, oxidation during perovskite disproportionation, evaporation during the giant impact, and mantle melting. It is important to reconcile why the Earth's basalts are enriched in 57Fe/54Fe but the meteorites from Mars and Vesta are not. One possible explanation is that Mars and Vesta are smaller and the lower pressure attenuated the potential Fe fractionation during core formation. A second possibility is that the intrinsic oxidation states of the planets are causing the differences. However, another option is that the light elements (e.g. S, C, O, H, Si) in the cores of differentiated bodies control the iron isotope fractionation during differentiation. We have conducted experiments at 1 GPa and 1650-1800°C in a piston cylinder apparatus to address how sulfur, carbon and silicon alloyed with iron affect the iron isotopic fractionation between metallic alloy and silicate melt. We find that sulfur has the greatest effect on the iron isotopic

  17. Stabilizing Alginate Confinement and Polymer Coating of CO-Releasing Molecules Supported on Iron Oxide Nanoparticles To Trigger the CO Release by Magnetic Heating.

    Science.gov (United States)

    Meyer, Hajo; Winkler, Felix; Kunz, Peter; Schmidt, Annette M; Hamacher, Alexandra; Kassack, Matthias U; Janiak, Christoph

    2015-12-07

    Maghemite (Fe2O3) iron oxide nanoparticles (IONPs) were synthesized, modified with covalent surface-bound CO-releasing molecules of a tri(carbonyl)-chlorido-phenylalaninato-ruthenium(II) complex (CORM), and coated with a dextran polymer. The time- and temperature-dependent CO release from this CORM-3 analogue was followed by a myoglobin assay. A new measurement method for the myoglobin assay was developed, based on confining "water-soluble" polymer-coated Dextran500k@CORM@IONP particles in hollow spheres of nontoxic and easily prepared calcium alginate. Dropping a mixture of Dextran500k@CORM@IONP and sodium alginate into a CaCl2 solution leads to stable hollow spheres of Ca(2+) cross-linked alginate which contain the Dextran500k@CORM@IONP particles. This "alginate-method" (i) protects CORM-3 analogues from rapid CO-displacement reactions with a protein, (ii) enables a spatial separation of the CORM from its surrounding myoglobin assay with the alginate acting as a CO-permeable membrane, and (iii) allows the use of substances with high absorptivity (such as iron oxide nanoparticles) in the myoglobin assay without interference in the optical path of the UV cell. Embedding the CORM@IONP nanoparticles in the alginate vessel represents a compartmentation of the reactive component and allows for close contact with, yet facile separation from, the surrounding myoglobin assay. The half-life of the CO release from Dextran500k@CORM@IONP particles surrounded by alginate was determined to be 890 ± 70 min at 20 °C. An acceleration of the CO release occurs at higher temperature with a half-life of 172 ± 27 min at 37 °C and 45 ± 7 min at 50 °C. The CO release can be triggered in an alternating current magnetic field (31.7 kA m(-1), 247 kHz, 39.9 mT) through local magnetic heating of the susceptible iron oxide nanoparticles. With magnetic heating at 20 °C in the bulk solution, the half-life of CO release from Dextran500k@CORM@IONP particles decreased to 155 ± 18 min

  18. Redox control of iron biomineralization in Magnetospirillum magneticum AMB-1

    Science.gov (United States)

    Jones, Stephanie Rhianon

    Magnetotactic bacteria have evolved complex subcellular machinery to construct linear chains of magnetite nanocrystals that allow the host cell to sense direction. Each mixed-valent iron nanoparticle is mineralized from soluble iron within a membrane-encapsulated vesicle termed the magnetosome, which serves as a specialized compartment that regulates the iron, redox, and pH environment of the growing mineral. In order to dissect the biological components that control this process, we have carried out genetic and biochemical studies of proteins proposed to function in iron mineralization in Magnetospirillum magneticum AMB-1. As iron biomineralization by magnetotactic bacteria represents a particularly interesting case for understanding how the production of nanomaterials can be programmed at the genetic level, we also apply synthetic biology techniques towards the production of new cellular materials and new cellular functions. As the production of magnetite requires both the formation of Fe(II) and Fe(III), the redox components of the magnetosome play an essential role in this process. Using genetic complementation studies, we show that the redox cofactors or heme sites of the two putative redox partners, MamP and MamT, are required for magnetite biomineralization in vivo and that removal of one or both sites leads to defects in mineralization. We develop and optimize a heterologous expression method in the E. coli periplasm to cleanly isolate fully heme-loaded MamP for biochemical studies. Spectrochemical redox titrations show that the reduction potential of MamP lies in a different range than other c-type cytochrome involved in either Fe(III) reduction or Fe(II) oxidation. Nonetheless, in vitro mineralization studies with MamP and Fe(II) show that it is able to catalyze the formation of mixed-valent Fe(II)/Fe(III) oxides such as green rust. Biomineralization also requires lattice-templating proteins that guide the growth of the functional crystalline material. We

  19. Oxidative dissolution of spent fuel and release of nuclides from a copper/iron canister. Model developments and applications

    Energy Technology Data Exchange (ETDEWEB)

    Longcheng Liu

    2001-12-01

    Three models have been developed and applied in the performance assessment of a final repository. They are based on accepted theories and experimental results for known and possible mechanisms that may dominate in the oxidative dissolution of spent fuel and the release of nuclides from a canister. Assuming that the canister is breached at an early stage after disposal, the three models describe three sub-systems in the near field of the repository, in which the governing processes and mechanisms are quite different. In the model for the oxidative dissolution of the fuel matrix, a set of kinetic descriptions is provided that describes the oxidative dissolution of the fuel matrix and the release of the embedded nuclides. In particular, the effect of autocatalytic reduction of hexavalent uranium by dissolved H{sub 2}, using UO{sub 2} (s) on the fuel pellets as a catalyst, is taken into account. The simulation results suggest that most of the radiolytic oxidants will be consumed by the oxidation of the fuel matrix, and that much less will be depleted by dissolved ferrous iron. Most of the radiolytically produced hexavalent uranium will be reduced by the autocatalytic reaction with H{sub 2} on the fuel surface. It will reprecipitate as UO{sub 2} (s) on the fuel surface, and thus very little net oxidation of the fuel will take place. In the reactive transport model, the interactions of multiple processes within a defective canister are described, in which numerous redox reactions take place as multiple species diffuse. The effect of corrosion of the cast iron insert of the canister and the reduction of dissolved hexavalent uranium by ferrous iron sorbed onto iron corrosion products and by dissolved H{sub 2} are particularly included. Scoping calculations suggest that corrosion of the iron insert will occur primarily under anaerobic conditions. The escaping oxidants from the fuel rods will migrate toward the iron insert. Much of these oxidants will, however, be consumed

  20. Controlled antiseptic release by alginate polymer films and beads.

    Science.gov (United States)

    Liakos, Ioannis; Rizzello, Loris; Bayer, Ilker S; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia

    2013-01-30

    Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca(2+)-cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants.

  1. Biopolymers in controlled release devices for agricultural applications.

    Science.gov (United States)

    The use of biopolymers such as starch for agricultural applications including controlled release devices is growing due the environmental benefits. Recently, concerns have grown about the worldwide spread of parasitic mites (Varroa destructor) that infect colonies of honey bees (Apis mellifera L.). ...

  2. Formulation and Pharmacokinetic Evaluation of Controlled-Release ...

    African Journals Online (AJOL)

    ISSN: 1596-5996 (print); 1596-9827 (electronic) ... Purpose: To develop and optimize controlled-release (CR) oxybutynin chloride matrix tablets. Methods: ... of the tablet was developed. ... India). Hydroxypropyl methylcellulose (HPMC) 4KM CR and ethyl cellulose (EC) were ..... Lyrinel OROS, and OXY/CR5C4 in SGF media.

  3. Using Randomized Controlled Trials to Evaluate Interventions for Releasing Prisoners

    Science.gov (United States)

    Pettus-Davis, Carrie; Howard, Matthew Owen; Dunnigan, Allison; Scheyett, Anna M.; Roberts-Lewis, Amelia

    2016-01-01

    Randomized controlled trials (RCTs) are rarely used to evaluate social and behavioral interventions designed for releasing prisoners. Objective: We use a pilot RCT of a social support intervention (Support Matters) as a case example to discuss obstacles and strategies for conducting RCT intervention evaluations that span prison and community…

  4. Composition for the controlled release of active compounds

    NARCIS (Netherlands)

    Hovens, I.A.P.; Jongboom, R.O.J.; Stuut, P.I.

    1999-01-01

    The invention provides a composition for the controlled release of one or more biologically active substances encapsulated in a degradable biopolymer matrix, consisting of a thermoplastic and/or partly crystalline inulin. A plasticiser such as glycerol, and an emulsifier may be present. The active s

  5. Rectal absorption of morphine from controlled release suppositories

    NARCIS (Netherlands)

    Moolenaar, Frits; Meyler, Pim; Frijlink, Erik; Jauw, Tjoe Hang; Visser, Jan; Proost, Johannes

    1995-01-01

    The absorption profiles and bioavailability of morphine in human volunteers (n = 13) were described after oral administration of MS Contin tablets and rectal administration of a newly developed controlled release suppository. By manipulating the viscosity of fatty suppository base an entirely

  6. Evaluation of Sterculia foetida gum as controlled release excipient.

    Science.gov (United States)

    Chivate, Amit Ashok; Poddar, Sushilkumar Sharatchandra; Abdul, Shajahan; Savant, Gaurav

    2008-01-01

    The purpose of the research was to evaluate Sterculia foetida gum as a hydrophilic matrix polymer for controlled release preparation. For evaluation as a matrix polymer; characterization of Sterculia foetida gum was done. Viscosity, pH, scanning electronmicrographs were determined. Different formulation aspects considered were: gum concentration (10-40%), particle size (75-420 microm) and type of fillers and those for dissolution studies; pH, and stirring speed were considered. Tablets prepared with Sterculia foetida gum were compared with tablets prepared with Hydroxymethylcellulose K15M. The release rate profiles were evaluated through different kinetic equations: zero-order, first-order, Higuchi, Hixon-Crowell and Korsemeyer and Peppas models. The scanning electronmicrographs showed that the gum particles were somewhat triangular. The viscosity of 1% solution was found to be 950 centipoise and pH was in range of 4-5. Suitable matrix release profile could be obtained at 40% gum concentration. Higher sustained release profiles were obtained for Sterculia foetida gum particles in size range of 76-125 microm. Notable influences were obtained for type of fillers. Significant differences were also observed with rotational speed and dissolution media pH. The in vitro release profiles indicated that tablets prepared from Sterculia foetida gum had higher retarding capacity than tablets prepared with Hydroxymethylcellulose K15M prepared tablets. The differential scanning calorimetry results indicated that there are no interactions of Sterculia foetida gum with diltiazem hydrochloride. It was observed that release of the drug followed through surface erosion and anomalous diffusion. Thus, it could be concluded that Sterculia foetida gum could be used a controlled release matrix polymer.

  7. Improvement of waste release control in French NPP

    Energy Technology Data Exchange (ETDEWEB)

    Samson, T.; Lucquin, E.; Dupin, M. [EDF/GDL (France); Florence, D. [EDF/GENV (France); Grisot, M. [EDF/CNPE Saint Laurent (France)

    2002-07-01

    The new waste release control in French NPP is more restrictive than the old one and needs heavy investment to bring plants to compliance with it. The great evolutions are a chemical follow up on more chemicals with a higher measurement frequency and with lower maximum concentrations and a specific measurement of carbon 14. Regarding radioactive releases, a new counting has been settled and activity of carbon 14 release is now measured and no longer calculated. The evolution of the French regulation leads to develop specific procedures and analytical techniques in chemistry and in radiochemistry (UV spectrometric methods, carbon 14 measurements,..) EDF NPP operators have launched a voluntarist process to reduce their releases since the beginning and before the evolution of the regulation. EDF priorities in terms of environment care lead henceforth to implement a global optimisation of the impact for a better control of releases. The new regulation will help EDF to reach its goals because it covers all the aspects in one administrative document: it is seen as a real simplification and a clarification towards public. In addition, this new regulation fits in with international practices which will allow an easier comparison of results between EDF and foreign NPP. These big environmental concerns lead EDF to create a national dedicated laboratory (LAMEN) in charge of developing specific measurement procedures to be implemented either by NPP or by sub-contractor laboratories. (authors)

  8. Multifunctional conducting fibres with electrically controlled release of ciprofloxacin.

    Science.gov (United States)

    Esrafilzadeh, Dorna; Razal, Joselito M; Moulton, Simon E; Stewart, Elise M; Wallace, Gordon G

    2013-08-10

    We hereby present a new method of producing coaxial conducting polymer fibres loaded with an antibiotic drug that can then be subsequently released (or sustained) in response to electrical stimulation. The method involves wet-spinning of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) fibre, which served as the inner core to the electropolymerised outer shell layer of polypyrrole (Ppy). Ciprofloxacin hydrochloride (Cipro) was selected as the model drug and as the dopant in the Ppy synthesis. The release of Cipro in phosphate buffered saline (PBS) from the fibres was controlled by switching the redox state of Ppy.Cipro layer. Released Cipro under passive and stimulated conditions were tested against Gram positive (Streptococcus pyogenes) and Gram negative (Escherichia coli) bacteria. Significant inhibition of bacterial growth was observed against both strains tested. These results confirm that Cipro retains antibacterial properties during fibre fabrication and electrochemically controlled release. In vitro cytotoxicity testing utilising the neural B35 cell line confirmed the cytocompatibility of the drug loaded conducting fibres. Electrical conductivity, cytocompatibility and tuning release profile from this flexible fibre can lead to promising bionic applications such as neuroprosthetics and localised drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Controlled release of ethylene via polymeric films for food packaging

    Science.gov (United States)

    Pisano, Roberto; Bazzano, Marco; Capozzi, Luigi Carlo; Ferri, Ada; Sangermano, Marco

    2015-12-01

    In modern fruit supply chain a common method to trigger ripening is to keep fruits inside special chambers and initiate the ripening process through administration of ethylene. Ethylene is usually administered through cylinders with inadequate control of its final concentration in the chamber. The aim of this study is the development of a new technology to accurately regulate ethylene concentration in the atmosphere where fruits are preserved: a polymeric film, containing an inclusion complex of α-cyclodextrin with ethylene, was developed. The complex was prepared by molecular encapsulation which allows the entrapment of ethylene into the cavity of α-cyclodextrin. After encapsulation, ethylene can be gradually released from the inclusion complex and its release rate can be regulated by temperature and humidity. The inclusion complex was dispersed into a thin polymeric film produced by UV-curing. This method was used because is solvent-free and involves low operating temperature; both conditions are necessary to prevent rapid release of ethylene from the film. The polymeric films were characterized with respect to thermal behaviour, crystalline structure and kinetics of ethylene release, showing that can effectively control the release of ethylene within confined volume.

  10. Tailoring liquid crystalline lipid nanomaterials for controlled release of macromolecules.

    Science.gov (United States)

    Bisset, Nicole B; Boyd, Ben J; Dong, Yao-Da

    2015-11-10

    Lipid-based liquid crystalline materials are being developed as drug delivery systems. However, the use of these materials for delivery of large macromolecules is currently hindered by the small size of the water channels in these structures limiting control over diffusion behaviour. The addition of the hydration-modulating agent, sucrose stearate, to phytantriol cubic phase under excess water conditions incrementally increased the size of these water channels. Inclusion of oleic acid enabled further control of swelling and de-swelling of the matrix via a pH triggerable system where at low pH the hexagonal phase is present and at higher pH the cubic phase is present. Fine control over the release of various sized model macromolecules is demonstrated, indicating future application to controlled loading and release of large macromolecules such as antibodies. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Hybrid Iron Oxide-Graphene Oxide-Polysaccharides Microcapsule: A Micro-Matryoshka for On-demand Drug Release and Antitumor Therapy In Vivo

    KAUST Repository

    Deng, Lin

    2016-02-25

    Premature drug release is a common drawback in stimuli responsive drug delivery systems (DDS) especially if it depends on internal triggers, that are hard to control, or a single external stimulus, that can only have one function. Thus, many DDS systems were reported combining different triggers, however limited success has been established in fine-tuning the release process mainly due to the poor bioavailability and complexity of the reported designs. This paper reports the design of a hybrid microcapsule (h-MC) by a simple layer-by-layer technique comprising polysaccharides (Alg, Chi, HA), iron oxide, and graphene oxide. Electrostatic assembly of the oppositely charged polysaccharides and graphene sheets provided a robust structure to load drugs through pH control. The polysaccharides component ensured high biocompatibility, bioavailability, and tumor cells targeting. Magnetic field and near infrared laser triggerable Fe3O4@GO component provided dual high energy and high penetration hyperthermia therapy. On-demand drug release from h-MC can be achieved by synchronizing these external triggers, making it highly controllable. The synergistic effect of hyperthermia and chemotherapy was successfully confirmed in vitro and in vivo.

  12. Iron therapy and anthropometry: A case-control study among iron deficient preschool children

    Directory of Open Access Journals (Sweden)

    Amany Ibrahim

    2017-09-01

    Conclusion: IDA during the first 6 years of life, when growth is fast, adversely affects both linear growth and weight gain which is reversible with iron therapy, thus adequate iron status is crucial for normal growth (height, weight and GV. The findings of the present study supported the beneficial effects of oral iron supplementation on physical growth parameters of IDA preschool children.

  13. Control of microstructure of cast irons Indefinite Chill Double Pour-ICDP

    Directory of Open Access Journals (Sweden)

    T.Válek

    2011-10-01

    Full Text Available ICDP cast irons designated for working layer of centrifugal cylinders of rolling mill must have precisely defined properties. The most closely observed parameters of the ICDP (Indefinite Child Double Pour cast irons are the following: the amount of graphite in a microstructure and hardness of base metal material. Secretion of graphite in cast iron with ledeburitic basic metal compound is a complex process that can be controlled and managed with the use of thermal analysis. On the basis of the evaluation of cooling curve parameters of cast iron there is performed metallurgical adjustment of meltage by adding elements supporting graphite end carbide formation into cast iron. The identified structural and mechanical properties of ICDP cast irons were correlated with recorded KO. Subsequently, a methodology for control of the metallurgical adjustment of cast iron before casting was proposed so as to ensure the desired microstructure and properties the ICDP cast iron.

  14. Halloysite clay nanotubes for controlled release of protective agents.

    Science.gov (United States)

    Lvov, Yuri M; Shchukin, Dmitry G; Möhwald, Helmuth; Price, Ronald R

    2008-05-01

    Halloysite aluminosilicate nanotubes with a 15 nm lumen, 50 nm external diameter, and length of 800 +/- 300 nm have been developed as an entrapment system for loading, storage, and controlled release of anticorrosion agents and biocides. Fundamental research to enable the control of release rates from hours to months is being undertaken. By variation of internal fluidic properties, the formation of nanoshells over the nanotubes and by creation of smart caps at the tube ends it is possible to develop further means of controlling the rate of release. Anticorrosive halloysite coatings are in development and a self-healing approach has been developed for repair mechanisms through response activation to external impacts. In this Perspective, applications of halloysite as nanometer-scale containers are discussed, including the use of halloysite tubes as drug releasing agents, as biomimetic reaction vessels, and as additives in biocide and protective coatings. Halloysite nanotubes are available in thousands of tons, and remain sophisticated and novel natural nanomaterials which can be used for the loading of agents for metal and plastic anticorrosion and biocide protection.

  15. Control of contents and release kinetics in block copolymer vesicles

    Science.gov (United States)

    Eisenberg, Adi

    2005-03-01

    Block copolymer vesicles have received considerable attention recently because of a wide range of potential applications. In our group, the thermodynamic aspects of vesicle formation, including curvature stabilization, as well as active loading and release from vesicles have been the focus of recent research. The vesicles are prepared from an amphiphilic diblock copolymer such as polystyrene-block-poly(acrylic acid) at a low pH (2.5) by adding water to a solution in a common solvent; then the extenal pH is raised to 6.5, and the compound, such as doxorubicin or another amine, is added. Since the compund inside the vesicle becomes ionized at the low pH, it can only escape at a rate very much slower than that of the loading process. The permeability of the wall can be controlled by the presence of plasticizers for the polystyrene wall; the plasticizers partition between the wall and the external aqueous solution with a known partition coefficient, and can be removed from the wall by dialysis. Release is then studied under perfect sink conditions and is diffusional. It is noteworthy that the rates of both loading and release can be varied by more than two orders of magnitude by controlling the plasticizer content. Also, between the loading and release processes, the vesicle wall can be hardened by removal of the plasticizer by dialysis. This degree of control makes block copolymer vesicles a promising delivery vehicle for a range of materials, including drugs.

  16. CONTROLLED RELEASE FROM PDMAEMA GELS PREPARED BY GAMMA RADIATION

    Institute of Scientific and Technical Information of China (English)

    Ning Liu; Min Yi; Shuang-ji Chen; Hong-fei Ha

    2002-01-01

    Poly(N,N-dimethylaminoethyl methacrylate) (polyDMAEMA) hydrogels prepared by γ-irradiation showed obvious temperature-sensitivity in a temperature range of 38-40℃ and pH-sensitivity at pH = 2.5. They also showed electric response behavior although it was not typical. The hydrogels were used in controlled release at different pH, temperature, and electric voltage. The release rates of methylene blue (MB) from the gels at 52℃ and pH = 1.24 were faster than those at 20℃ and pH = 10.56, respectively. In addition, the release rate at a field voltage of 5.0 was also faster than that without electric field.

  17. Optogenetic control of serotonin and dopamine release in Drosophila larvae.

    Science.gov (United States)

    Xiao, Ning; Privman, Eve; Venton, B Jill

    2014-08-20

    Optogenetic control of neurotransmitter release is an elegant method to investigate neurobiological mechanisms with millisecond precision and cell type-specific resolution. Channelrhodopsin-2 (ChR2) can be expressed in specific neurons, and blue light used to activate those neurons. Previously, in Drosophila, neurotransmitter release and uptake have been studied after continuous optical illumination. In this study, we investigated the effects of pulsed optical stimulation trains on serotonin or dopamine release in larval ventral nerve cords. In larvae with ChR2 expressed in serotonergic neurons, low-frequency stimulations produced a distinct, steady-state response while high-frequency patterns were peak shaped. Evoked serotonin release increased with increasing stimulation frequency and then plateaued. The steady-state response and the frequency dependence disappeared after administering the uptake inhibitor fluoxetine, indicating that uptake plays a significant role in regulating the extracellular serotonin concentration. Pulsed stimulations were also used to evoke dopamine release in flies expressing ChR2 in dopaminergic neurons and similar frequency dependence was observed. Release due to pulsed optical stimulations was modeled to determine the uptake kinetics. For serotonin, Vmax was 0.54 ± 0.07 μM/s and Km was 0.61 ± 0.04 μM; and for dopamine, Vmax was 0.12 ± 0.03 μM/s and Km was 0.45 ± 0.13 μM. The amount of serotonin released per stimulation pulse was 4.4 ± 1.0 nM, and the amount of dopamine was 1.6 ± 0.3 nM. Thus, pulsed optical stimulations can be used to mimic neuronal firing patterns and will allow Drosophila to be used as a model system for studying mechanisms underlying neurotransmission.

  18. Incorporation of 5-hydroxytryptophan into transferrin and its receptor allows assignment of the pH induced changes in intrinsic fluorescence when iron is released.

    Science.gov (United States)

    James, Nicholas G; Byrne, Shaina L; Mason, Anne B

    2009-03-01

    Human serum transferrin (hTF) is a bilobal glycoprotein that transports iron to cells. At neutral pH, diferric hTF binds with nM affinity to the transferrin receptor (TFR) on the cell surface. The complex is taken into the cell where, at the acidic pH of the endosome ( approximately pH 5.6), iron is released. Since iron coordination strongly quenches the intrinsic tryptophan fluorescence of hTF, the increase in the fluorescent signal reports the rate constant(s) of iron release. At pH 5.6, the TFR considerably enhances iron release from the C-lobe (with little effect on iron release from the N-lobe). The recombinant soluble TFR is a dimer with 11 tryptophan residues per monomer. In the hTF/TFR complex these residues could contribute to and compromise the readout ascribed to iron release from hTF. We report that compared to Fe(C) hTF alone, the increase in the fluorescent signal from the preformed complex of Fe(C) hTF and the TFR at pH 5.6 is significantly quenched (75%). To dissect the contributions of hTF and the TFR to the change in fluorescence, 5-hydroxytryptophan was incorporated into each using our mammalian expression system. Selective excitation of the samples at 280 or 315 nm shows that the TFR contributes little or nothing to the increase in fluorescence when ferric iron is released from Fe(C) hTF. Quantum yield determinations of TFR, Fe(C) hTF and the Fe(C) hTF/TFR complex strongly support our interpretation of the kinetic data.

  19. Arsenic release from flooded paddy soils is influenced by speciation, Eh, pH, and iron dissolution.

    Science.gov (United States)

    Yamaguchi, N; Nakamura, T; Dong, D; Takahashi, Y; Amachi, S; Makino, T

    2011-05-01

    Arsenic (As) is highly mobilized when paddy soil is flooded, causing increased uptake of As by rice. We investigated factors controlling soil-to-solution partitioning of As under anaerobic conditions. Changes in As and iron (Fe) speciation due to flooded incubation of two paddy soils (soils A and B) were investigated by HPLC/ICP-MS and XANES. The flooded incubation resulted in a decrease in Eh, a rise in pH, and an increase in the As(III) fraction in the soil solid phase up to 80% of the total As in the soils. The solution-to-soil ratio of As(III) and As(V) (R(L/S)) increased with pH due to the flooded incubation. The R(L/S) for As(III) was higher than that for As(V), indicating that As(III) was more readily released from soil to solution than was As(V). Despite the small differences in As concentrations between the two soils, the amount of As dissolved by anaerobic incubation was lower in soil A. With the development of anaerobic conditions, Fe(II) remained in the soil solid phase as the secondary mineral siderite, and a smaller amount of Fe was dissolved from soil A than from soil B. The dissolution of Fe minerals rather than redox reaction of As(V) to As(III) explained the different dissolution amounts of As in the two paddy soils. Anaerobic incubation for 30 d after the incomplete suppression of microbial activity caused a drop in Eh. However, this decline in Eh did not induce the transformation of As(V) to As(III) in either the soil solid or solution phases, and the dissolution of As was limited. Microbial activity was necessary for the reductive reaction of As(V) to As(III) even when Eh reached the condition necessary for the dominance of As(III). Ratios of released As to Fe from the soils were decreased with incubation time during both anaerobic incubation and abiotic dissolution by sodium ascorbate, suggesting that a larger amount of As was associated with an easily soluble fraction of Fe (hydr) oxide in amorphous phase and/or smaller particles. Copyright

  20. Release Characteristics of Different N Forms in an Uncoated Slow/Controlled Release Compound Fertilizer

    Institute of Scientific and Technical Information of China (English)

    DONG Yan; WANG Zheng-yin

    2007-01-01

    This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations: the first-order kinetics equation [Nt = N0 (1-e-kt)], Elovich equation (Nt = a + blnt), and parabola equation (Nt = a + bt0.5), with the best fitting by the first-order kinetics equation for different N (r= 0.9569**-0.9999**). The release potentials (N0 values estimated by the first-order kinetics equation) of different N in the UCRF decreased in the order of total N > DON > urea-N > NH4+-N > NO3--N in water, and total N > NH4+-N > DON > urea-N > NO3--N in soil, respectively,being in accordance with cumulative amounts of N release. The constants of N release rate (k values and b values) for different N forms were in decreasing order of total N > DON > NH4+-N > NO3--N in water, whereas the k values were urea-N >DON > NH4+-N > total N > NO3--N, and the b values were total N > NH4+-N > DON > NO3--N > urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg-1, and 5.17 kg kg-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0(1-e-kt)] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.

  1. Normal-release and controlled-release oxycodone: pharmacokinetics, pharmacodynamics, and controversy.

    Science.gov (United States)

    Davis, Mellar P; Varga, James; Dickerson, Duke; Walsh, Declan; LeGrand, Susan B; Lagman, Ruth

    2003-02-01

    Oxycodone has become one of the most popular opioids in the United States. It is superior to morphine in oral absorption and bioavailability, and similar in terms of protein binding and lipophilicity. Gender more than age influences oxycodone elimination. Unlike morphine, oxycodone is metabolized by the cytochrome isoenzyme CYP2D6, which is severely impaired by liver dysfunction. Controlled-release (CR) oxycodone has become one of the most frequently utilized sustained-release opioids in the United States. Both its analgesic benefits and its side effects are similar to those of CR morphine. CR oxycodone is similar to morphine and other opioids in its abuse potential. Deaths attributable to oxycodone are usually associated with polysubstance abuse in which oxycodone is combined with psychostimulants, other opioids, benzodiazepines or alcohol. Oxycodone's kappa receptor binding has little role in abuse or addiction. The cost of CR oxycodone is prohibitive for most American hospices.

  2. Mechanism of controlled release kinetics from medical devices

    Directory of Open Access Journals (Sweden)

    A. Raval

    2010-06-01

    Full Text Available Utilization of biodegradable polymers for controlled drug delivery has gained immense attention in the pharmaceutical and medical device industry to administer various drugs, proteins and other bio-molecules both systematically and locally to cure several diseases. The efficacy and toxicity of this local therapeutics depends upon drug release kinetics, which will further decide drug deposition, distribution, and retention at the target site. Drug Eluting Stent (DES presently possesses clinical importance as an alternative to Coronary Artery Bypass Grafting due to the ease of the procedure and comparable safety and efficacy. Many models have been developed to describe the drug delivery from polymeric carriers based on the different mechanisms which control the release phenomenon from DES. Advanced characterization techniques facilitate an understanding of the complexities behind design and related drug release behavior of drug eluting stents, which aids in the development of improved future drug eluting systems. This review discusses different drug release mechanisms, engineering principles, mathematical models and current trends that are proposed for drug-polymer coated medical devices such as cardiovascular stents and different analytical methods currently utilized to probe diverse characteristics of drug eluting devices.

  3. Controlled Release of Agrochemicals Intercalated into Montmorillonite Interlayer Space

    Directory of Open Access Journals (Sweden)

    Harrison Wanyika

    2014-01-01

    Full Text Available Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH pore volumes and Brunauer-Emmett-Teller (BET surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT and metalaxyl loaded montmorillonite (RMMT complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil.

  4. Controlled Release of Agrochemicals Intercalated into Montmorillonite Interlayer Space

    Science.gov (United States)

    2014-01-01

    Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil. PMID:24696655

  5. Monoubiquitin-dependent endocytosis of the iron-regulated transporter 1 (IRT1) transporter controls iron uptake in plants.

    Science.gov (United States)

    Barberon, Marie; Zelazny, Enric; Robert, Stéphanie; Conéjéro, Geneviève; Curie, Cathy; Friml, Jìrí; Vert, Grégory

    2011-08-09

    Plants take up iron from the soil using the iron-regulated transporter 1 (IRT1) high-affinity iron transporter at the root surface. Sophisticated regulatory mechanisms allow plants to tightly control the levels of IRT1, ensuring optimal absorption of essential but toxic iron. Here, we demonstrate that overexpression of Arabidopsis thaliana IRT1 leads to constitutive IRT1 protein accumulation, metal overload, and oxidative stress. IRT1 is unexpectedly found in trans-Golgi network/early endosomes of root hair cells, and its levels and localization are unaffected by iron nutrition. Using pharmacological approaches, we show that IRT1 cycles to the plasma membrane to perform iron and metal uptake at the cell surface and is sent to the vacuole for proper turnover. We also prove that IRT1 is monoubiquitinated on several cytosol-exposed residues in vivo and that mutation of two putative monoubiquitination target residues in IRT1 triggers stabilization at the plasma membrane and leads to extreme lethality. Together, these data suggest a model in which monoubiquitin-dependent internalization/sorting and turnover keep the plasma membrane pool of IRT1 low to ensure proper iron uptake and to prevent metal toxicity. More generally, our work demonstrates the existence of monoubiquitin-dependent trafficking to lytic vacuoles in plants and points to proteasome-independent turnover of plasma membrane proteins.

  6. Are fluoride releasing dental materials clinically effective on caries control?

    Science.gov (United States)

    Cury, Jaime Aparecido; de Oliveira, Branca Heloisa; dos Santos, Ana Paula Pires; Tenuta, Livia Maria Andaló

    2016-03-01

    (1) To describe caries lesions development and the role of fluoride in controlling disease progression; (2) to evaluate whether the use of fluoride-releasing pit and fissure sealants, bonding orthodontic agents and restorative materials, in comparison to a non-fluoride releasing material, reduces caries incidence in children or adults, and (3) to discuss how the anti-caries properties of these materials have been evaluated in vitro and in situ. The search was performed on the Cochrane Database of Systematic Reviews and on Medline via Pubmed. Caries is a biofilm-sugar dependent disease and as such it provokes progressive destruction of mineral structure of any dental surface - intact, sealed or restored - where biofilm remains accumulated and is regularly exposed to sugar. The mechanism of action of fluoride released from dental materials on caries is similar to that of fluoride found in dentifrices or other vehicles of fluoride delivery. Fluoride-releasing materials are unable to interfere with the formation of biofilm on dental surfaces adjacent to them or to inhibit acid production by dental biofilms. However, the fluoride released slows down the progression of caries lesions in tooth surfaces adjacent to dental materials. This effect has been clearly shown by in vitro and in situ studies but not in randomized clinical trials. The anti-caries effect of fluoride releasing materials is still not based on clinical evidence, and, in addition, it can be overwhelmed by fluoride delivered from dentifrices. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Controlled exosome release from the retinal pigment epithelium in situ.

    Science.gov (United States)

    Locke, Christina J; Congrove, Nicole R; Dismuke, W Michael; Bowen, Trent J; Stamer, W Daniel; McKay, Brian S

    2014-12-01

    Retinal Pigment Epithelial cells (RPE) express both GPR143 and myocilin, which interact in a signal transduction-dependent manner. In heterologous systems, activation of GPR143 with ligand causes transient recruitment of myocilin to internalized receptors, which appears to be the entry point of myocilin to the endocytic pathway. In some but not all cells, myocilin also traffics through the multivesicular body (MVB) and is released on the surface of exosomes in a signal transduction-dependent fashion. Little is known regarding the role of exosomes in RPE, but they likely serve as a mode of communication between the RPE and the outer retina. In this study, we used posterior poles with retina removed from fresh human donor eyes as a model to test the relationship between GPR143, myocilin, and exosomes in an endogenous system. We isolated exosomes released by RPE using differential centrifugation of media conditioned by the RPE for 25 min, and then characterized the exosomes using nanoparticle tracking to determine the number and size of the exosomes. Next, we tested whether ligand stimulation of GPR143 using l-DOPA altered RPE exosome release. Finally, we investigated whether myocilin was present on the exosomes released by RPE and whether l-DOPA stimulation of GPR143 caused recruitment of myocilin to the endocytic pathway, as we have previously observed using cultured cells. Activation of GPR143 halted RPE exosome release, while simultaneously recruiting myocilin to the endocytic compartment. Together, our results indicate that GPR143 and myocilin function in a signal transduction system that can control exosome release from RPE.

  8. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    OpenAIRE

    Siafu Ibahati Sempeho; Hee Taik Kim; Egid Mubofu; Alexander Pogrebnoi; Godlisten Shao; Askwar Hilonga

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging betwee...

  9. Hybrid Porous Materials for Controlled Release and Catalysis

    OpenAIRE

    Liu, Rui

    2010-01-01

    First reported in 1992, ordered mesoporous materials exhibit unique features, such as regular pore geometry, high surface area, and large pore volume, and have shown great potential in various applications. This dissertation combines the knowledge from the field of ordered mesoporous materials and several other research areas to design advanced hybrid porous materials for controlled release and catalysis applications.The demand for better treatment of illness has led to ever-increasing effort...

  10. Smart nanofibers with a photoresponsive surface for controlled release.

    Science.gov (United States)

    Fu, Guo-Dong; Xu, Li-Qun; Yao, Fang; Li, Guo-Liang; Kang, En-Tang

    2009-11-01

    A novel photocontrolled "ON-OFF" release system for the alpha-cyclodextrin-5-fluorouracial (alpha-CD-5FU) prodrug, based on host-guest interaction on the photoresponsive and cross-linked nanofiber surface, was demonstrated. The nanofibers with a stimuli-responsive surface were electrospun from the block copolymer prepared via controlled radical polymerization, followed by surface modification via "Click Chemistry", and loading of the prodrug via host-guest interaction.

  11. Hybrid Porous Materials for Controlled Release and Catalysis

    OpenAIRE

    Liu, Rui

    2010-01-01

    First reported in 1992, ordered mesoporous materials exhibit unique features, such as regular pore geometry, high surface area, and large pore volume, and have shown great potential in various applications. This dissertation combines the knowledge from the field of ordered mesoporous materials and several other research areas to design advanced hybrid porous materials for controlled release and catalysis applications.The demand for better treatment of illness has led to ever-increasing effort...

  12. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    OpenAIRE

    Siafu Ibahati Sempeho; Hee Taik Kim; Egid Mubofu; Alexander Pogrebnoi; Godlisten Shao; Askwar Hilonga

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging betwee...

  13. An oral controlled release matrix pellet formulation containing nanocrystalline ketoprofen.

    Science.gov (United States)

    Vergote, G J; Vervaet, C; Van Driessche, I; Hoste, S; De Smedt, S; Demeester, J; Jain, R A; Ruddy, S; Remon, J P

    2001-05-21

    A controlled release pellet formulation using a NanoCrystal colloidal dispersion of ketoprofen was developed. In order to be able to process the aqueous NanoCrystal colloidal dispersion into a hydrophobic solid dosage form a spray drying procedure was used. The in vitro dissolution profiles of wax based pellets loaded with nanocrystalline ketoprofen are compared with the profiles of wax based pellets loaded with microcrystalline ketoprofen and of a commercial sustained release ketoprofen formulation. Pellets were produced using a melt pelletisation technique. All pellet formulations were composed of a mixture of microcrystalline wax and starch derivatives. The starch derivatives used were waxy maltodextrin and drum dried corn starch. Varying the concentration of drum dried corn starch increased the release rate of ketoprofen but the ketoprofen recovery remained problematic. To increase the dissolution yield surfactants were utilised. The surfactants were either added during the production process of the NanoCrystal colloidal dispersion (sodium laurylsulphate) or during the pellet manufacturing process (Cremophor RH 40). Both methods resulted in a sustained but complete release of nanocrystalline ketoprofen from the matrix pellet formulations.

  14. Controlled release of 5-flurouracil from biomedical polyurethanes

    Indian Academy of Sciences (India)

    Reddy Seetharamareddy Harisha; Kallappa Mahadevappa Hosamani; Rangappa Sangappa Keri; Namdev Shelke; Vijay Kumar Wadi; Tejaraj M Aminabhavi

    2010-03-01

    Novel biodegradable aliphatic poly(ether-urethane)s (PEUs) based on pluronic F-68 (PLF68) and castor oil were synthesized by the solution polymerization technique. These polymers were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic spectroscopy (1HNMR) and gel permeation chromatography (GPC) to confirm the PEU formation and the molecular weight. Moderate molecular weight PEUs were obtained and converted into microspheres by solvent evaporation method to study the controlled release (CR) characteristics for 5-flurouracil (5-FU). PLF-68 acts as amphiphilic filler, which enhances the release of a hydrophobic drug such as 5-FU. Sizes of the microspheres as measured by laser light scattering technique ranged between 15 and 42 m. An increase in the size of particles was observed with increasing molar ratio of PLF-68 with respect to castor oil. The percentage encapsulation efficiency varied between 71 and 98. Surface morphology of the microspheres as studied by scanning electron microscopy (SEM) revealed the spherical nature of the particles with wrinkles on their surfaces. The release of 5-FU through the microspheres was investigated in pH 7.4-phosphate buffer. An increase in release rate was observed with increasing molar ratio of PLF68 with respect to castor oil.

  15. Encapsulation efficiency and controlled release characteristics of crosslinked polyacrylamide particles.

    Science.gov (United States)

    Sairam, Malladi; Babu, V Ramesh; Vijaya, Boya; Naidu, Kumar; Aminabhavi, Tejraj M

    2006-08-31

    Polyacrylamide (pAAm) particles crosslinked with N,N-methylenebis-acrylamide/ethylene glycol dimethacrylate (NNMBA/EGDMA) have been prepared in water-methanol medium by the dispersion polymerization using poly(vinyl pyrrolidone), PVP as a steric stabilizer. 5-fluorouracil an anticancer drug, has been loaded in situ into the crosslinked pAAm particles. Plain as well as drug loaded microparticles have been characterized by differential scanning calorimetry (DSC) and X-ray diffraction studies (XRD) and scanning electron microscopy (SEM). DSC and XRD studies have indicated a molecular level dispersion of the drug in pAAm particles during in situ loading and SEM pictures have shown the formation of spherical and oval-shaped particles. In vitro release of 5-fluorouracil from the crosslinked pAAm particles has been carried out in 7.4 pH buffer medium. Both encapsulation efficiency and release patterns are found to depend on the nature of the crosslinking agent, amount of crosslinking agent used and the amount of drug loaded. In vitro release studies indicated the controlled release of 5-fluorouracil up to 12 h.

  16. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    Directory of Open Access Journals (Sweden)

    Siafu Ibahati Sempeho

    2015-01-01

    Full Text Available Urea controlled release fertilizer (CRF was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU. Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-vermicular booklets. In addition, a unique brain-form agglomeration which transformed into roundish particles mart was observed after encapsulation. The nanocomposites decomposed between 48 and 600°C. Release profiles showed that 100% of urea was released in 97 hours from KPDMU while 87% was released in 150 hours from the encapsulated nanocomposite. The findings established that it is possible to use Pugu kaolinite and gum arabic biopolymer to prepare urea CRF formulations.

  17. Preparation and characterization of chitosan-Polyethylene glycol-polyvinylpyrrolidone-coated superparamagnetic iron oxide nanoparticles as carrier system: Drug loading and in vitro drug release study.

    Science.gov (United States)

    Prabha, G; Raj, V

    2016-05-01

    In the present research work, the anticancer drug "curcumin" is loaded with Chitosan (CS)-polyethylene glycol (PEG)-polyvinylpyrrolidone (PVP) (CS-PEG-PVP) polymer nanocomposites coated with superparamagnetic iron oxide (Fe3 O4 ) nanoparticles. The system can be used for targeted and controlled drug delivery of anticancer drugs with reduced side effects and greater efficiency. The prepared nanoparticles were characterized by Fourier transmission infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Curcumin drug-loaded Fe3 O4 -CS, Fe3 O4 -CS- PEG and Fe3 O4 -CS-PEG-PVP nanoparticles exhibited the mean particle size in the range of 183 - 390 nm with a zeta potential value of 26 mV-41 mV as measured using Malvern Zetasizer. The encapsulation efficiency, loading capacity and in-vitro drug release behaviour of curcumin drug-loaded Fe3 O4 -CS, Fe3 O4 -CS-PEG, and Fe3 O4 -CS-PEG-PVP nanoparticles were studied using UV spectrophotometer. Besides, the cytotoxicity of the prepared nanoparticles using MTT assay was also studied. The curcumin drug release was examined at different pH medium (4.5 and 7.4) and temperature (37°C and 45°C), and it was proved that the drug release depends upon the pH medium and temperature in addition to the nature of matrix.

  18. Hybrid nanostructured drug carrier with tunable and controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Depan, D.; Misra, R.D.K., E-mail: dmisra@louisiana.edu

    2012-08-01

    We describe here a transformative approach to synthesize a hybrid nanostructured drug carrier that exhibits the characteristics of controlled drug release. The synthesis of the nanohybrid architecture involved two steps. The first step involved direct crystallization of biocompatible copolymer along the long axis of the carbon nanotubes (CNTs), followed by the second step of attachment of drug molecule to the polymer via hydrogen bonding. The extraordinary inorganic-organic hybrid architecture exhibited high drug loading ability and is physically stable even under extreme conditions of acidic media and ultrasonic irradiation. The temperature and pH sensitive characteristics of the hybrid drug carrier and high drug loading ability merit its consideration as a promising carrier and utilization of the fundamental aspects used for synthesis of other promising drug carriers. The higher drug release response during the application of ultrasonic frequency is ascribed to a cavitation-type process in which the acoustic bubbles nucleate and collapse releasing the drug. Furthermore, the study underscores the potential of uniquely combining CNTs and biopolymers for drug delivery. - Graphical abstract: Block-copolymer crystallized on carbon nanotubes (CNTs). Nanohybrid drug carrier synthesized by attaching doxorubicin (DOX) to polymer crystallized CNTs. Crystallized polymer on CNTs provide mechanical stability. Triggered release of DOX. Highlights: Black-Right-Pointing-Pointer The novel synthesis of a hybrid nanostructured drug carrier is described. Black-Right-Pointing-Pointer The drug carrier exhibits high drug loading ability and is physically stable. Black-Right-Pointing-Pointer The high drug release is ascribed to a cavitation-type process.

  19. Design of a controlled release liquid formulation of lamotrigine

    Directory of Open Access Journals (Sweden)

    V Kumar

    2011-05-01

    Full Text Available "n  "n  Background and the purpose of the study: Lamotrigine is a broad spectrum anticonvulsant drug widely used as mono- or adjunct- therapy in adults and children. The aim of this study was to develop controlled release liquid formulation of lamotrigine to improve bioavailability and compliance of pediatric and geriatric epileptic patients. "n  Methods: Multiple (w/o/w emulsion was prepared using one step emulsification technique. It was evaluated for entrapment efficiency (EE, morphology, zeta potential (ZP, polydispersity index (PI, rheology, thermal property, in vitro drug release behavior and stability. In vivo studies in albino mice were carried out using maximal electroshock seizure (MES test and strychnine induced seizure (SIS pattern test and results were compared with marketed formulation. "n  Results: The EE of the formulations varied from 84.37% to 98.11%. The ZP and PI values of the prepared batches were in the range of +23.46 to +28.07 and 0.256 and 0.365, respectively. Microscopic observation clearly indicated the stability of the emulsions during the storage period. All batches exhibited controlled in vitro drug release up to 12 hrs. Batch C11 exhibited significantly longer duration of protection of seizure in mice against MES and exhibited comparable efficacy in SIS as compared to the marketed formulation. "n  Major Conclusion: Multiple emulsion of lamotrigine compared to the marketed tablet showed plasma drug concentration within therapeutic range for longer time and comparable efficacy.

  20. Development of controlled drug release systems based on thiolated polymers.

    Science.gov (United States)

    Bernkop-Schnürch, A; Scholler, S; Biebel, R G

    2000-05-03

    The purpose of the present study was to generate mucoadhesive matrix-tablets based on thiolated polymers. Mediated by a carbodiimide, L-cysteine was thereby covalently linked to polycarbophil (PCP) and sodium carboxymethylcellulose (CMC). The resulting thiolated polymers displayed 100+/-8 and 1280+/-84 micromol thiol groups per gram, respectively (means+/-S.D.; n=6-8). In aqueous solutions these modified polymers were capable of forming inter- and/or intramolecular disulfide bonds. The velocity of this process augmented with increase of the polymer- and decrease of the proton-concentration. The oxidation proceeded more rapidly within thiolated PCP than within thiolated CMC. Due to the formation of disulfide bonds within thiol-containing polymers, the stability of matrix-tablets based on such polymers could be strongly improved. Whereas tablets based on the corresponding unmodified polymer disintegrated within 2 h, the swollen carrier matrix of thiolated CMC and PCP remained stable for 6.2 h (mean, n=4) and more than 48 h, respectively. Release studies of the model drug rifampicin demonstrated that a controlled release can be provided by thiolated polymer tablets. The combination of high stability, controlled drug release and mucoadhesive properties renders matrix-tablets based on thiolated polymers useful as novel drug delivery systems.

  1. Dopamine control of LH release in the tench (Tinca tinca).

    Science.gov (United States)

    Podhorec, Peter; Socha, Magdalena; Sokolowska-Mikolajczyk, Miroslawa; Policar, Tomas; Svinger, Viktor W; Drozd, Borek; Kouril, Jan

    2012-01-01

    Tench (Tinca tinca) is apparently the only known member of the Cyprinidae in which ovulation is stimulated following administration of a low dose of GnRH analogue (GnRHa) without a dopamine inhibitor. This study evaluated LH release effectiveness of the most commonly used GnRHa and clarified whether LH secretion followed by ovulation is subject to inhibitory dopaminergic control in tench. Fish were intraperitoneally injected with three types of GnRHa, GnRHa with dopamine inhibitor metoclopramide (combined treatment), or the dopamine inhibitor metoclopramide alone. LH concentrations at five sampling times (0, 6, 12, 24, and 33 h) together with ovulation success and fecundity index were recorded. The combined treatment triggered an almost immediate LH release peak with a gradual decline, and resulted in a high ovulation rate. In contrast to the combined treatment, an application of GnRHa alone at 10 μg kg(-1) induced gradual increase of LH concentrations with peaks close to ovulation time, and with high ovulation success. Significant differences in LH concentrations at 6 and 12h and no differences in ovulation success were found between the combined and the GnRHa alone treatments. Metoclopramide alone induced a small increase in LH with no ovulation. The study presents clear evidence of dopaminergic control of LH release in tench, with a high ovulation rate obtained after application of GnRHa alone or in combination with dopamine inhibitor.

  2. Optical control of insulin release using a photoswitchable sulfonylurea.

    Science.gov (United States)

    Broichhagen, Johannes; Schönberger, Matthias; Cork, Simon C; Frank, James A; Marchetti, Piero; Bugliani, Marco; Shapiro, A M James; Trapp, Stefan; Rutter, Guy A; Hodson, David J; Trauner, Dirk

    2014-10-14

    Sulfonylureas are widely prescribed for the treatment of type 2 diabetes mellitus (T2DM). Through their actions on ATP-sensitive potassium (KATP) channels, sulfonylureas boost insulin release from the pancreatic beta cell mass to restore glucose homeostasis. A limitation of these compounds is the elevated risk of developing hypoglycemia and cardiovascular disease, both potentially fatal complications. Here, we describe the design and development of a photoswitchable sulfonylurea, JB253, which reversibly and repeatedly blocks KATP channel activity following exposure to violet-blue light. Using in situ imaging and hormone assays, we further show that JB253 bestows light sensitivity upon rodent and human pancreatic beta cell function. Thus, JB253 enables the optical control of insulin release and may offer a valuable research tool for the interrogation of KATP channel function in health and T2DM.

  3. Controlled release of hydrophilic guest molecules from photoresponsive nucleolipid vesicles.

    Science.gov (United States)

    Sun, Yawei; Yan, Yongfeng; Wang, Mingqing; Chen, Cuixia; Xu, Hai; Lu, Jian R

    2013-07-10

    Amphiphilic hybrid nucleolipids bear the structural and functional hallmarks of both lipids and nucleic acids and hold great potential for biotechnological applications. However, further tailoring of their structures and properties for specific applications represents a major challenge. We here report a novel design and synthesis of a light-responsive nucleolipid by introducing an o-nitrobenzyl group that acts as a linker between a nucleotide and a lipid. The nucleolipid was applied readily to preparing smart vesicles and encapsulating hydrophilic guest molecules 5(6)-carboxyfluorescein (CF) in their inner aqueous phase. Upon light irradiation, their vesicular structure was disrupted as a result of the photolytic degradation of the nucleotide, resulting in CF release. Furthermore, temporally controlled CF release from these vesicles could be readily realized by turning on and off light. By demonstrating the molecular assembly and photodisassembly cycle, this report aims to stimulate further research exploring practical applications of nucleolipids.

  4. Chitosan Hydrogels for Chondroitin Sulphate Controlled Release: An Analytical Characterization

    Directory of Open Access Journals (Sweden)

    Annalisa Bianchera

    2014-01-01

    Full Text Available This paper provides an analytical characterization of chitosan scaffolds obtained by freeze-gelation toward the uptake and the controlled release of chondroitin sulphate (CS, as cartilage repair agent, under different pH conditions. Scanning electron microscopy (SEM, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR, and liquid chromatography-UV spectrophotometry (LC-UV techniques were exploited to obtain qualitative and quantitative descriptions of polymer and drug behaviour in the biomaterial. As for morphology, SEM analysis allowed the evaluation of scaffold porosity in terms of pore size and distribution both at the surface (Feret diameter 58±19 μm and on the cross section (Feret diameter 106±51 μm. LC and ATR-FTIR evidenced a pH-dependent CS loading and release behaviour, strongly highlighting the role of electrostatic forces on chitosan/chondroitin sulphate interactions.

  5. Graphene as a photothermal switch for controlled drug release

    Science.gov (United States)

    Matteini, Paolo; Tatini, Francesca; Cavigli, Lucia; Ottaviano, Stefania; Ghini, Giacomo; Pini, Roberto

    2014-06-01

    Graphene has recently emerged as a novel material in the biomedical field owing to its optical properties, biocompatibility, large specific surface area and low cost. In this paper, we provide the first demonstration of the possibility of using light to remotely trigger the release of drugs from graphene in a highly controlled manner. Different drugs including chemotherapeutics and proteins are firmly adsorbed onto reduced graphene oxide (rGO) nanosheets dispersed in a biopolymer film and then released by individual millisecond-long light pulses generated by a near infrared (NIR) laser. Here graphene plays the dual role of a versatile substrate for temporary storage of drugs and an effective transducer of NIR-light into heat. Drug release appears to be narrowly confined within the size of the laser spot under noninvasive conditions and can be precisely dosed depending on the number of pulses. The approach proposed paves the way for tailor-made pharmacological treatments of chronic diseases, including cancer, anaemia and diabetes.Graphene has recently emerged as a novel material in the biomedical field owing to its optical properties, biocompatibility, large specific surface area and low cost. In this paper, we provide the first demonstration of the possibility of using light to remotely trigger the release of drugs from graphene in a highly controlled manner. Different drugs including chemotherapeutics and proteins are firmly adsorbed onto reduced graphene oxide (rGO) nanosheets dispersed in a biopolymer film and then released by individual millisecond-long light pulses generated by a near infrared (NIR) laser. Here graphene plays the dual role of a versatile substrate for temporary storage of drugs and an effective transducer of NIR-light into heat. Drug release appears to be narrowly confined within the size of the laser spot under noninvasive conditions and can be precisely dosed depending on the number of pulses. The approach proposed paves the way for tailor

  6. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    Science.gov (United States)

    Zhou, Zijun; Du, Changwen; Li, Ting; Shen, Yazhen; Zhou, Jianmin

    2015-09-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the polyacrylate membrane, and hence to analyze the mechanism of nutrient release, Fourier transform mid-infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were employed. The nutrient-release model of CRF post-treated at 30 °C was the inverse “L” curve, but an increased duration of the post-treatment had no effect. The nutrient-release model was “S” curve and nutrient-release period was enhanced at higher post-treatment temperatures, and increased post-treatment duration lengthened slowed nutrient release due to a more compact membrane and a smoother membrane surface as well as a promoted crosslinking action. CRF equipped with specified nutrient-release behaviors can be achieved by optimizing the thermal post-treatment parameters, which can contribute to the development and application of waterborne polymer-coated CRF and controlled-release technologies.

  7. INVITED PAPER: Control of sudden releases in channel flow

    Science.gov (United States)

    Katopodes, Nikolaos D.

    2009-12-01

    We present a method for the detection and real-time control of chemical releases in channel flow. Sensor arrays capable of detecting a broad menu of chemical agents are required at strategic locations of the channel. The sensors detect the instantaneous, spatially distributed concentration of the chemical agent and transmit the associated information to a predictive control model. The model provides optimal operation scenarios for computer controlled bleed valves mounted on the channel walls and connected to a common manifold. Control and elimination of the chemical cloud are achieved by optimal blowing and suction of ambient fluid. Gradient information is obtained by use of adjoint equations, so optimization of the control actions is achieved with the highest possible efficiency. The control is optimized over a finite prediction horizon and instructions are sent to the valve manifold. Next, the sensor arrays detect all changes effected by the control and report them to the control model, which advances the process over the next control horizon. Non-reflective boundary conditions for the adjoint equations are derived by a characteristic analysis, which minimizes spurious information in the computation of sensitivities.

  8. Collagen scaffolds with controlled insulin release and controlled pore structure for cartilage tissue engineering.

    Science.gov (United States)

    Nanda, Himansu Sekhar; Chen, Shangwu; Zhang, Qin; Kawazoe, Naoki; Chen, Guoping

    2014-01-01

    Controlled and local release of growth factors and nutrients from porous scaffolds is important for maintenance of cell survival, proliferation, and promotion of tissue regeneration. The purpose of the present research was to design a controlled release porous collagen-microbead hybrid scaffold with controlled pore structure capable of releasing insulin for application to cartilage tissue regeneration. Collagen-microbead hybrid scaffold was prepared by hybridization of insulin loaded PLGA microbeads with collagen using a freeze-drying technique. The pore structure of the hybrid scaffold was controlled by using preprepared ice particulates having a diameter range of 150-250 μ m. Hybrid scaffold had a controlled pore structure with pore size equivalent to ice particulates and good interconnection. The microbeads showed an even spatial distribution throughout the pore walls. In vitro insulin release profile from the hybrid scaffold exhibited a zero order release kinetics up to a period of 4 weeks without initial burst release. Culture of bovine articular chondrocytes in the hybrid scaffold demonstrated high bioactivity of the released insulin. The hybrid scaffold facilitated cell seeding and spatial cell distribution and promoted cell proliferation.

  9. Collagen Scaffolds with Controlled Insulin Release and Controlled Pore Structure for Cartilage Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Himansu Sekhar Nanda

    2014-01-01

    Full Text Available Controlled and local release of growth factors and nutrients from porous scaffolds is important for maintenance of cell survival, proliferation, and promotion of tissue regeneration. The purpose of the present research was to design a controlled release porous collagen-microbead hybrid scaffold with controlled pore structure capable of releasing insulin for application to cartilage tissue regeneration. Collagen-microbead hybrid scaffold was prepared by hybridization of insulin loaded PLGA microbeads with collagen using a freeze-drying technique. The pore structure of the hybrid scaffold was controlled by using preprepared ice particulates having a diameter range of 150–250 μm. Hybrid scaffold had a controlled pore structure with pore size equivalent to ice particulates and good interconnection. The microbeads showed an even spatial distribution throughout the pore walls. In vitro insulin release profile from the hybrid scaffold exhibited a zero order release kinetics up to a period of 4 weeks without initial burst release. Culture of bovine articular chondrocytes in the hybrid scaffold demonstrated high bioactivity of the released insulin. The hybrid scaffold facilitated cell seeding and spatial cell distribution and promoted cell proliferation.

  10. Voltage-Responsive Controlled Release Film with Cargo Release Self-Monitoring Property Based on Hydrophobicity Switching.

    Science.gov (United States)

    Jiao, Xiangyu; Li, Yanan; Li, Fengyu; Sun, Ruijuan; Wang, Wenqian; Wen, Yongqiang; Song, Yanlin; Zhang, Xueji

    2017-03-16

    Herein, voltage-responsive controlled release film was constructed by grafting ferrocene on the mesoporous inverse opal photonic crystal (mIOPC). The film achieved free-blockage controlled release and realized the monitoring of cargo release without external indicator. Free-blockage was attributed to the voltage switchable nanovalves which undergo hydrophobic-to-hydrophilic transition when applying voltage. Monitoring of cargo release was attributed to the optical property of mIOPC, the bandgap of mIOPC had a red shift when the solution invaded in. The film was hydrophobic enough to stop solution intrusion. Once the voltage was applied, the film became hydrophilic, leading to invasion of the solution. As a result, the cargos were released and the bandgap of mIOPC was red-shifted. Therefore, in this paper both a free-blockage controlled release film and a release sensing system was prepared. The study provides new insights into highly effective controlled release and release sensing without indicator.

  11. Randomised controlled trials of iron chelators for the treatment of cardiac siderosis in thalassaemia major

    Directory of Open Access Journals (Sweden)

    Arun John Baksi

    2014-09-01

    Full Text Available In conditions requiring repeated blood transfusion or where iron metabolism is abnormal, heart failure may result from accumulation of iron in the heart (cardiac siderosis. Death due to heart failure from cardiac iron overload has accounted for considerable early mortality in β-thalassemia major. The ability to detect iron loading in the heart by cardiovascular magnetic resonance using T2* sequences has created an opportunity to intervene in the natural history of such conditions. However, effective and well tolerated therapy is required to remove iron from the heart. There are currently 3 approved commercially available iron chelators: deferoxamine, deferiprone and deferasirox. We review the high quality randomised controlled trials in this area for iron chelation therapy in the management of cardiac siderosis.

  12. Health implications of PAH release from coated cast iron drinking water distribution systems in The Netherlands.

    Science.gov (United States)

    Blokker, E J Mirjam; van de Ven, Bianca M; de Jongh, Cindy M; Slaats, P G G Nellie

    2013-05-01

    Coal tar and bitumen have been historically used to coat the insides of cast iron drinking water mains. Polycyclic aromatic hydrocarbons (PAHs) may leach from these coatings into the drinking water and form a potential health risk for humans. We estimated the potential human cancer risk from PAHs in coated cast iron water mains. In a Dutch nationwide study, we collected drinking water samples at 120 locations over a period of 17 days under various operational conditions, such as undisturbed operation, during flushing of pipes, and after a mains repair, and analyzed these samples for PAHs. We then estimated the health risk associated with an exposure scenario over a lifetime. During flushing, PAH levels frequently exceeded drinking water quality standards; after flushing, these levels dropped rapidly. After the repair of cast iron water mains, PAH levels exceeded the drinking water standards for up to 40 days in some locations. The estimated margin of exposure for PAH exposure through drinking water was > 10,000 for all 120 measurement locations, which suggests that PAH exposure through drinking water is of low concern for consumer health. However, factors that differ among water systems, such as the use of chlorination for disinfection, may influence PAH levels in other locations.

  13. A Study of the Effects of Latent Iron Deficiency on Measures of Cognition: A Pilot Randomised Controlled Trial of Iron Supplementation in Young Women

    Directory of Open Access Journals (Sweden)

    Alecia J. Leonard

    2014-06-01

    Full Text Available Rates of iron deficiency are high amongst healthy young women. Cognitive impairment occurs secondary to iron deficiency in infants and children, but evaluation of the impact on cognition among young women is inconsistent. The aim was to determine the suitability of the IntegNeuro test battery for assessing cognitive function in iron-deficient and iron-sufficient young women. A pilot double-blinded, placebo-controlled intervention trial was conducted in iron-deficient (serum ferritin ≤ 20 μg/L and haemoglobin > 120 g/L and iron-sufficient young women (18–35 years. Cognitive function and haematological markers of iron status were measured at baseline and follow-up. Iron-deficient participants (n = 24 were randomised to receive placebo, 60 mg or 80 mg elemental iron daily supplements for 16 weeks. A control group of iron-sufficient participants (n = 8 was allocated to placebo. Change scores for Impulsivity and Attention were significantly greater in plasma ferritin improvers than in non-improvers (p = 0.004, p = 0.026. IntegNeuro was easy to administer and acceptable to young women. Based on the differences in Memory and Attention scores between iron-deficient participants on iron treatment and those on placebo, it was decided that between 26 and 84 participants would be required in each iron treatment group for an adequately powered extension of this pilot RCT.

  14. DEVELOPMENT AND EVALUATION OF CLOZAPINE PELLETS FOR CONTROLLED RELEASE

    Directory of Open Access Journals (Sweden)

    D.V. Gowda

    2012-08-01

    Full Text Available This research work was done to design oral controlled release matrix pellets of water insoluble drug Clozapine, using blend of Hydroxypropyl cellulose and glyceryl palmito stearate as as matrix polymers, methyl crystalline cellulose as spheronizer enhancer,sodium lauryl sulphate as pore forming agent. Clozapine formulations developed by the pellitization technique by drug loaded pellets were characterized with regard to the drug content, size distribution, Scanning electron microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy and Xray Diffraction study. Stability studies were carried out on the optimized formulation for aperiod of 90 days, 40 ± 2 oC and 75 ± 5% relative humidity. The drug content was in the range of 95.34 – 98.12 %. The mean particle size of drug loaded pellets was in the range 1018 to 1065 mm. SEM photographs and calculated sphericity factor confirms that the prepared formulations were spherical in nature. The drug loaded pellets were stable and compatible as confirmed by DSC and FTIR studies. XRD patterns revealed the crystalline nature of pure clozapine. Loose surface crystal study indicated that crystalline clozapine was observed in all formulation and more clear in formulation A5. Higher amount of clozapine released was observed from formulation A5 and Syclop® 25 mg tablet as compared to all other formulations and mechanism of drug release followed Fickian diffusion. It can be concluded that formulation A5 is an ideal formulation for once a day administration.

  15. Tunable controlled release of molecular species from Halloysite nanotubes

    Science.gov (United States)

    Elumalai, Divya Narayan

    Encouraged by potential applications in rust coatings, self-healing composites, selective delivery of drugs, and catalysis, the transport of molecular species through Halloysite nanotubes (HNTs), specifically the storage and controlled release of these molecules, has attracted strong interest in recent years. HNTs are a naturally occurring biocompatible nanomaterial that are abundantly and readily available. They are alumosilicate based tubular clay nanotubes with an inner lumen of 15 nm and a length of 600-900 nm. The size of the inner lumen of HNTs may be adjusted by etching. The lumen can be loaded with functional agents like antioxidants, anticorrosion agents, flame-retardant agents, drugs, or proteins, allowing for a sustained release of these agents for hours. The release times can be further tuned for days and months by the addition of tube end-stoppers. In this work a three-dimensional, time-quantified Monte Carlo model that efficiently describes diffusion through and from nanotubes is implemented. Controlled delivery from Halloysite Nanotubes (HNT) is modeled based on interactions between the HNT's inner wall and the nanoparticles (NP) and among NPs themselves. The model was validated using experimental data published in the literature. The validated model is then used to study the effect of multiple parameters like HNT diameter and length, particle charge, ambient temperature and the creation of smart caps at the tube ends on the release of encapsulated NPs. The results show that release profiles depend on the size distribution of the HNT batch used for the experiment, as delivery is sensitive to HNT lumen and length. The effect of the addition of end-caps to the HNTs, on the rate of release of encapsulated NPs is also studied here. The results show that the release profiles are significantly affected by the addition of end caps to the HNTs and is sensitive to the end-cap pore lumen. A very good agreement with the experiment is observed when a weight

  16. Gelatin-encapsulated iron oxide nanoparticles for platinum (IV) prodrug delivery, enzyme-stimulated release and MRI.

    Science.gov (United States)

    Cheng, Ziyong; Dai, Yunlu; Kang, Xiaojiao; Li, Chunxia; Huang, Shanshan; Lian, Hongzhou; Hou, Zhiyao; Ma, Pingan; Lin, Jun

    2014-08-01

    A facile method for transferring hydrophobic iron oxide nanoparticles (IONPs) from chloroform to aqueous solution via encapsulation of FITC-modified gelatin based on the hydrophobic-hydrophobic interaction is described in this report. Due to the existence of large amount of active groups such as amine groups in gelatin, the fluorescent labeling molecules of fluorescein isothiocyanate (FITC) and platinum (IV) prodrug functionalized with carboxylic groups can be conveniently conjugated on the IONPs. The nanoparticles carrying Pt(IV) prodrug exhibit good anticancer activities when the Pt(IV) complexes are reduced to Pt(II) in the intracellular environment, while the pure Pt(IV) prodrug only presents lower cytotoxicity on cancer cells. Meanwhile, fluorescence of FITC on the surface of nanoparticles was completely quenched due to the possible Förster Resonance Energy Transfer (FRET) mechanism and showed a fluorescence recovery after gelatin release and detachment from IONPs. Therefore FITC as a fluorescence probe can be used for identification, tracking and monitoring the drug release. In addition, adding pancreatic enzyme can effectively promote the gelatin release from IONPs owing to the degradation of gelatin. Noticeable darkening in magnetic resonance image (MRI) was observed at the tumor site after in situ injection of nanoparticles, indicating the IONPs-enhanced T2-weighted imaging. Our results suggest that the gelatin encapsulated Fe3O4 nanoparticles have potential applications in multi-functional drug delivery system for disease therapy, MR imaging and fluorescence sensor. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. δ-FeOOH: a superparamagnetic material for controlled heat release under AC magnetic field

    Science.gov (United States)

    Chagas, Poliane; da Silva, Adilson Cândido; Passamani, Edson Caetano; Ardisson, José Domingos; de Oliveira, Luiz Carlos Alves; Fabris, José Domingos; Paniago, Roberto M.; Monteiro, Douglas Santos; Pereira, Márcio César

    2013-04-01

    Experimental evidences on its in vitro use reveal that δ-FeOOH is a material that release-controlled amount of heat if placed under an AC magnetic field. δ-FeOOH nanoparticles were prepared by precipitating Fe(OH)2 in alkaline solution followed by fast oxidation with H2O2. XRD and 57Fe Mössbauer spectroscopy data confirmed that δ-FeOOH is indeed the only iron-bearing compound in the produced sample. TEM images evidence that the averaged particle sizes for this δ-FeOOH sample is 23 nm. Magnetization measurements indicate that these δ-FeOOH particles behave superparamagnetically at 300 K; its saturation magnetization was found to be 13.2 emu g-1; the coercivity and the remnant magnetization were zero at 300 K. The specific absorption rate values at 225 kHz were 2.1, 6.2, and 34.2 W g-1, under 38, 64, and 112 mT, respectively. The release rate of heat can be directly controlled by changing the mass of δ-FeOOH nanoparticles. In view of these findings, the so-prepared δ-FeOOH is a real alternative to be further tested as a material for medical practices in therapies involving magnetic hyperthermia as in clinical oncology.

  18. {delta}-FeOOH: a superparamagnetic material for controlled heat release under AC magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, Poliane; Candido da Silva, Adilson [ICEx, Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Caetano Passamani, Edson [Universidade Federal do Espirito Santo, Departamento de Fisica (Brazil); Ardisson, Jose Domingos [Centro de Desenvolvimento da Tecnologia Nuclear (Brazil); Alves de Oliveira, Luiz Carlos [ICEx, Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Domingos Fabris, Jose [Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) (Brazil); Paniago, Roberto M. [ICEx, Universidade Federal de Minas Gerais, Departamento de Fisica (Brazil); Monteiro, Douglas Santos; Pereira, Marcio Cesar, E-mail: mcpqui@gmail.com [Instituto de Ciencia, Engenharia e Tecnologia, UFVJM (Brazil)

    2013-04-15

    Experimental evidences on its in vitro use reveal that {delta}-FeOOH is a material that release-controlled amount of heat if placed under an AC magnetic field. {delta}-FeOOH nanoparticles were prepared by precipitating Fe(OH){sub 2} in alkaline solution followed by fast oxidation with H{sub 2}O{sub 2}. XRD and {sup 57}Fe Moessbauer spectroscopy data confirmed that {delta}-FeOOH is indeed the only iron-bearing compound in the produced sample. TEM images evidence that the averaged particle sizes for this {delta}-FeOOH sample is 23 nm. Magnetization measurements indicate that these {delta}-FeOOH particles behave superparamagnetically at 300 K; its saturation magnetization was found to be 13.2 emu g{sup -1}; the coercivity and the remnant magnetization were zero at 300 K. The specific absorption rate values at 225 kHz were 2.1, 6.2, and 34.2 W g{sup -1}, under 38, 64, and 112 mT, respectively. The release rate of heat can be directly controlled by changing the mass of {delta}-FeOOH nanoparticles. In view of these findings, the so-prepared {delta}-FeOOH is a real alternative to be further tested as a material for medical practices in therapies involving magnetic hyperthermia as in clinical oncology.

  19. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    Science.gov (United States)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J.

    2011-02-01

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s - 1. Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  20. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J, E-mail: Thomas_Webster@Brown.edu [School of Engineering, Brown University, Providence, RI 02912 (United States)

    2011-02-25

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s{sup -1}. Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  1. Distribution of radionuclides in an iron calibration standard for a free release measurement facility.

    Science.gov (United States)

    Hult, Mikael; Stroh, Heiko; Marissens, Gerd; Tzika, Faidra; Lutter, Guillaume; Šurán, Jiri; Kovar, Petr; Skala, Lukas; Sud, Jaromír

    2016-03-01

    A Europallet-sized calibration standard composed of 12 grey cast iron tubes contaminated with (60)Co and (110m)Ag with a mass of 246kg was developed. As the tubes were produced through centrifugal casting it was of particular concern to study the distribution of radionuclides in the radial direction of the tubes. This was done by removing 72 small samples (swarf) of ~0.3g each on both the inside and outside of the tubes. All of the samples were measured in the underground laboratory HADES.

  2. A randomised controlled trial to compare intravenous iron sucrose and oral iron in treatment of iron deficiency anemia in pregnancy.

    Science.gov (United States)

    Gupta, Avantika; Manaktala, Usha; Rathore, Asmita Muthal

    2014-06-01

    The aim of this study was to compare the efficacy and safety of intravenous iron sucrose with oral iron therapy in pregnant patients with anemia. The primary outcome of the study was increase in haemoglobin on day 7, 14 & 28 and rise of serum ferritin over 28 days. The study population consisted of 100 patients with singleton pregnancy between 24 and 34 weeks, hemoglobin levels between 7.0-9.0 gm/dL and serum ferritin levels less than 15 ng/mL. The participants in the oral group were given daily 180 mg elemental iron in three divided oral doses for 4 weeks. Total calculated dose of iron sucrose with a target hemoglobin of 11 gm %, was given in 200 mg dose on alternate days. Mean haemoglobin rise was 0.58 gm/dL in the IV group as compared to 0.23 gm/dL in the oral group on day 14 and 1.9 gm/dL in the IV group & 1.3 gm/dL in the oral group on day 28, (p <0.05). In the IV group, 76% of the subjects achieved haemoglobin levels of ≥11 gm% at the time of delivery, as compared to only 54% of the subjects in the oral group who achieved these levels. Serum ferritin value was significantly higher in the IV group, 37.45 ± 5.73 ng/mL as compared to 13.96 ± 1.88 ng/mL in the oral group at 4th week (p <0.001). There was no major side effect in the IV group. 36% subjects in the oral group developed gastrointestinal side effects & 10% of the subjects were non compliant. The rate of hemoglobin rise is faster with intravenous iron sucrose therapy as compared to oral iron therapy which can be beneficial in pregnant women presenting with anemia at a later period of gestation. Intravenous iron sucrose is very well tolerated during pregnancy.

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

    Science.gov (United States)

    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.

  4. Gelatin methacrylate microspheres for controlled growth factor release.

    Science.gov (United States)

    Nguyen, Anh H; McKinney, Jay; Miller, Tobias; Bongiorno, Tom; McDevitt, Todd C

    2015-02-01

    Gelatin has been commonly used as a delivery vehicle for various biomolecules for tissue engineering and regenerative medicine applications due to its simple fabrication methods, inherent electrostatic binding properties, and proteolytic degradability. Compared to traditional chemical cross-linking methods, such as the use of glutaraldehyde (GA), methacrylate modification of gelatin offers an alternative method to better control the extent of hydrogel cross-linking. Here we examined the physical properties and growth factor delivery of gelatin methacrylate (GMA) microparticles (MPs) formulated with a wide range of different cross-linking densities (15-90%). Less methacrylated MPs had decreased elastic moduli and larger mesh sizes compared to GA MPs, with increasing methacrylation correlating to greater moduli and smaller mesh sizes. As expected, an inverse correlation between microparticle cross-linking density and degradation was observed, with the lowest cross-linked GMA MPs degrading at the fastest rate, comparable to GA MPs. Interestingly, GMA MPs at lower cross-linking densities could be loaded with up to a 10-fold higher relative amount of growth factor than conventional GA cross-linked MPs, despite the GA MPs having an order of magnitude greater gelatin content. Moreover, a reduced GMA cross-linking density resulted in more complete release of bone morphogenic protein 4 and basic fibroblast growth factor and accelerated release rate with collagenase treatment. These studies demonstrate that GMA MPs provide a more flexible platform for growth factor delivery by enhancing the relative binding capacity and permitting proteolytic degradation tunability, thereby offering a more potent controlled release system for growth factor delivery.

  5. Controlled iodine release from polyurethane sponges for water decontamination.

    Science.gov (United States)

    Aviv, Oren; Laout, Natalia; Ratner, Stanislav; Harik, Oshrat; Kunduru, Konda Reddy; Domb, Abraham J

    2013-12-28

    Iodinated polyurethane (IPU) sponges were prepared by immersing sponges in aqueous/organic solutions of iodine or exposing sponges to iodine vapors. Iodine was readily adsorbed into the polymers up to 100% (w/w). The adsorption of iodine on the surface was characterized by XPS and SEM analyses. The iodine loaded IPU sponges were coated with ethylene vinyl acetate (EVA), in order to release iodine in a controlled rate for water decontamination combined with active carbon cartridge, which adsorbs the iodine residues after the microbial inactivation. The EVA coated IPU were incorporated in a water purifier and tested for iodine release to water and for microbial inactivation efficiency according to WQA certification program against P231/EPA for 250l, using 25l a day with flow rate of 6-8min/1l. The antimicrobial activity was also studied against Escherichia coli and MS2 phage. Bacterial results exceeded the minimal requirement for bacterial removal of 6log reduction throughout the entire lifespan. At any testing point, no bacteria was detected in the outlet achieving more than 7.1 to more than 8log reduction as calculated upon the inlet concentration. Virus surrogate, MS2, reduction results varied from 4.11log reduction under tap water, and 5.11log reduction under basic water (pH9) to 1.32 for acidic water (pH5). Controlled and stable iodine release was observed with the EVA coated IPU sponges and was effective in deactivating the bacteria and virus present in the contaminated water and thus, these iodinated PU systems could be used in water purification to provide safe drinking water. These sponges may find applications as disinfectants in medicine.

  6. Influence of alcohol on the release of tramadol from 24-h controlled-release formulations during in vitro dissolution experiments.

    Science.gov (United States)

    Traynor, M J; Brown, M B; Pannala, A; Beck, P; Martin, G P

    2008-08-01

    Recent warnings by regulatory bodies and a product recall by the FDA have generated much interest in the area of dose dumping from controlled-release opioid analgesic formulations when coingested with alcohol. It was the aim of this study to address this issue and in doing so, gain understanding on how alcohol-induced effects may be avoided. In this study, tramadol release from Ultram ER tablets and T-long capsules was significantly increased in the presence of ethanol. Conversely, a decrease in the rate of tramadol release was seen from Tridural extended-release tablets in the presence of alcohol.

  7. Rotor Field Oriented Control with adaptive Iron Loss Compensation

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Vadstrup, P.; Børsting, H.

    1999-01-01

    It is well known from the literature that iron loses in an induction motor implies field angle estimation errors and hence detuning problems. In this paper a new method for estimating the iron loss resistor in an induction motor is presented. The method is based on a traditional dynamic model of ...

  8. Contact lenses as drug controlled release systems: a narrative review

    Directory of Open Access Journals (Sweden)

    Helena Prior Filipe

    2016-06-01

    Full Text Available ABSTRACT Topically applied therapy is the most common way to treat ocular diseases, however given the anatomical and physiological constraints of the eye, frequent dosing is required with possible repercussions in terms of patient compliance. Beyond refractive error correction, contact lenses (CLs have, in the last few decades emerged as a potential ophthalmic drug controlled release system (DCRS. Extensive research is underway to understand how to best modify CLs to increase residence time and bioavailability of drugs within therapeutic levels on the ocular surface.These devices may simultaneously correct ametropia and have a role in managing ophthalmic disorders that can hinder CL wear such as dry eye, glaucoma, ocular allergy and cornea infection and injury. In this narrative review the authors explain how the ocular surface structures determine drug diffusion in the eye and summarize the strategies to enhance drug residence time and bioavailability. They synthesize findings and clinical applications of drug soaked CLs as DCRS combined with delivery diffusion barriers, incorporation of functional monomers, ion related controlled release, molecular imprinting, nanoparticles and layering. The authors draw conclusions about the impact of these novel ophthalmic agents delivery systems in improving drug transport in the target tissue and patient compliance, in reducing systemic absorption and undesired side effects, and discuss future perspectives.

  9. A concise review on smart polymers for controlled drug release.

    Science.gov (United States)

    Aghabegi Moghanjoughi, Arezou; Khoshnevis, Dorna; Zarrabi, Ali

    2016-06-01

    Design and synthesis of efficient drug delivery systems are of critical importance in health care management. Innovations in materials chemistry especially in polymer field allows introduction of advanced drug delivery systems since polymers could provide controlled release of drugs in predetermined doses over long periods, cyclic and tunable dosages. To this end, researchers have taken advantages of smart polymers since they can undergo large reversible, chemical, or physical fluctuations as responses to small changes in environmental conditions, for instance, in pH, temperature, light, and phase transition. The present review aims to highlight various kinds of smart polymers, which are used in controlled drug delivery systems as well as mechanisms of action and their applications.

  10. Modeling controlled nutrient release from a population of polymer coated fertilizers: statistically based model for diffusion release.

    Science.gov (United States)

    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.

  11. Effects of Control Release Fertilizers on Nutrient Leaching, Palm Growth and Production Cost

    OpenAIRE

    Pushpa Soti; Angie Fleurissaint; Stewart Reed; Krish Jayachandran

    2015-01-01

    Objective of this study was to evaluate the effect of different controlled release fertilizer technologies on nutrient leaching and plant growth parameters of two palm species, Chinese Fan (Livistona chinensis) and Queen (Syagrus romanzoffiana). We compared Nutri-Pak (12-4-12 controlled release packet) and Harrell’s (12-4-12 controlled release polymer coated urea) against Atlantic (8-4-12 controlled release polymer coated urea, coated sulfate of potash), the most commonly used palm fertilize...

  12. Biochar increases arsenic release from an anaerobic paddy soil due to enhanced microbial reduction of iron and arsenic.

    Science.gov (United States)

    Wang, Ning; Xue, Xi-Mei; Juhasz, Albert L; Chang, Zhi-Zhou; Li, Hong-Bo

    2017-01-01

    Previous studies have shown that biochar enhances microbial reduction of iron (Fe) oxyhydroxide under anaerobic incubation. However, there is a lack of data on its influence on arsenic (As) release from As-contaminated paddy soils. In this study, paddy soil slurries (120 mg As kg(-1)) were incubated under anaerobic conditions for 60 days with and without the addition of biochar (3%, w/w) prepared from rice straw at 500 °C. Arsenic release, Fe reduction, and As fractionation were determined at 1, 10, 20, 30, and 60 d, while Illumina sequencing and real-time PCR were used to characterize changes in soil microbial community structure and As transformation function genes. During the first month of incubation, As released into soil solution increased sharply from 27.9 and 55.9 to 486 and 630 μg kg(-1) in unamended and biochar amended slurries, with inorganic trivalent As (As(III)) being the dominant specie (52.7-91.0% of total As). Compared to unamended slurries, biochar addition increased As and ferrous ion (Fe(2+)) concentrations in soil solution but decreased soil As concentration in the amorphous Fe/Al oxide fraction (F3). Difference in released As between biochar and unamended treatments (ΔAs) increased with incubation time, showing strong linear relationships (R(2) = 0.23-0.33) with ΔFe(2+) and ΔF3, confirming increased As release due to enhanced Fe reduction. Biochar addition increased the abundance of Fe reducing bacteria such as Clostridum (27.3% vs. 22.7%), Bacillus (3.34% vs. 2.39%), and Caloramator (4.46% vs. 3.88%). In addition, copy numbers in biochar amended slurries of respiratory As reducing (arrA) and detoxifying reducing genes (arsC) increased 19.0 and 1.70 fold, suggesting microbial reduction of pentavalent As (As(V)) adsorbed on Fe oxides to As(III), further contributing to increased As release.

  13. Efficacy of iron-fortified whole maize flour on iron status of schoolchildren in Kenya: a randomised controlled trial

    NARCIS (Netherlands)

    Andang'o, P.E.A.; Osendarp, S.J.M.; Ayah, R.; West, C.E.; Mwaniki, D.; Wolf, de C.A.; Kraaijenhagen, R.; Kok, F.J.; Verhoef, H.

    2007-01-01

    Background Sodium iron edetic acid (NaFeEDTA) might be a more bioavailable source of iron than electrolytic iron, when added to maize flour. We aimed to assess the effect, on children's iron status, of consumption of whole maize flour fortified with iron as NaFeEDTA or electrolytic iron. Methods 516

  14. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    OpenAIRE

    Zijun Zhou; Changwen Du; Ting Li; Yazhen Shen; Jianmin Zhou

    2015-01-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the ...

  15. Thermal post-treatment alters nutrient release from a controlled-release fertilizer coated with a waterborne polymer

    OpenAIRE

    Zijun Zhou; Changwen Du; Ting Li; Yazhen Shen; Jianmin Zhou

    2015-01-01

    Controlled-release fertilizers (CRF) use a controlled-release technology to enhance the nutrient use efficiency of crops. Many factors affect the release of nutrients from the waterborne polymer-coated CRF, but the effects of thermal post-treatments remain unclear. In this study, a waterborne polyacrylate-coated CRF was post-treated at different temperatures (30 °C, 60 °C, and 80 °C) and durations (2, 4, 8, 12, and 24 h) after being developed in the Wurster fluidized bed. To characterize the ...

  16. Rotor Field Oriented Control with adaptive Iron Loss Compensation

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Vadstrup, P.; Børsting, H.

    1999-01-01

    It is well known from the literature that iron loses in an induction motor implies field angle estimation errors and hence detuning problems. In this paper a new method for estimating the iron loss resistor in an induction motor is presented. The method is based on a traditional dynamic model...... of the motor referenced to the rotor magnetizing current, and with the extension of an iron loss resistor added in parallel to the magnetizing inductance. The resistor estimator is based on the observation that the actual applied stator voltages deviates from the voltage estimated, when a motor is current...

  17. Association between functional iron deficiency and reactive thrombocytosis in hospitalised patients: a case-control study.

    Science.gov (United States)

    Nicola, H; Ho, K M; Cordingley, F

    2016-11-01

    The association of deficiency in total body iron with an increased risk of reactive thrombocytosis is well known, but whether 'functional iron deficiency' is also associated with reactive thrombocytosis is unknown. This retrospective case-control study assessed the relationships between functional iron deficiency, reactive thrombocytosis and risk of thromboembolism. A total of 150 patients with reactive thrombocytosis (platelet count >400 x 10(9)/l) and 343 controls (platelet count thrombocytosis, infection, and an elevated C-reactive protein (CRP) concentration were all significantly more common in patients with functional iron deficiency than in those without functional iron deficiency (all P thrombocytosis (odds ratio 1.66, 95% confidence interval 1.10-2.75; P=0.048). Thromboembolic events occurred in 32 patients (6.6%). This was not significantly associated with functional iron deficiency. Our results suggest that in patients without haematological malignancy or recent chemotherapy there might be a link between functional iron deficiency and reactive thrombocytosis. Whether treating patients with functional iron deficiency with intravenous iron corrects reactive thrombocytosis without inducing infection remains uncertain, but merits further investigation.

  18. Oral suspensions of morphine hydrochloride for controlled release: rheological properties and drug release.

    Science.gov (United States)

    Morales, M E; López, G; Gallardo, V; Ruiz, M A

    2011-04-04

    Recent developments in pharmaceutical technology have facilitated the design and production of modified release formulas for drugs whose physical, chemical or biological properties impede release and thus might compromise their efficacy or safety. One such drug is morphine, whose short half-life requires repeated doses at short intervals. The use of biocompatible polymers such as ethylcellulose has made it possible to develop microencapsulated formulations which facilitate liquid, sustained-release pharmaceutical formulas for oral administration. We developed a stable final formulation of morphine with an acceptable release profile by comparing the rheological properties and stability of formulations with different thickeners (xanthan gum, Carbopol, and carboxymethylcellulose with microcrystalline cellulose) at different concentrations from 0.25% to 1.0%. Release assays in a Franz-type cell were done to determine the most suitable release profile for the formulation.

  19. Properties and controlled release of chitosan microencapsulated limonene oil

    Directory of Open Access Journals (Sweden)

    Jefferson M. Souza

    2014-12-01

    Full Text Available Chitosan microcapsules containing limonene essential oil as active ingredient were prepared by coacervation using three different concentrations of NaOH (0.50, 1.00, 1.45 wt% and fixed concentrations of chitosan and surfactant of 0.50 wt%. The produced microcapsules were fully characterized in their morphology and chemical composition, and the kinetic release analysis of the active ingredient was evaluated after deposition in a non-woven cellulose fabric. The concentration of 1.00 and 1.45 wt% clearly show the best results in terms of dimension and shape of the microcapsules as well as in the volatility results. However, at the concentration of 1 wt% a higher number of microcapsules were produced as confirmed by FTIR and EDS analysis. Free microcapsules are spherical in size with disperse diameters between 2 and 12 μm. Immobilized microcapsules showed sizes from 4 to 7 μm, a rough surface and loss of spherical shape with pore formation in the chitosan walls. SEM analysis confirms that at higher NaOH concentrations, the larger the size of the microcapsules. This technique shows that by tuning NaOH concentration it is possible to efficiently control the release rate of encapsulated active agents demonstrating great potential as insect repellent for textiles.

  20. Dietary iron controls circadian hepatic glucose metabolism through heme synthesis.

    Science.gov (United States)

    Simcox, Judith A; Mitchell, Thomas Creighton; Gao, Yan; Just, Steven F; Cooksey, Robert; Cox, James; Ajioka, Richard; Jones, Deborah; Lee, Soh-Hyun; King, Daniel; Huang, Jingyu; McClain, Donald A

    2015-04-01

    The circadian rhythm of the liver maintains glucose homeostasis, and disruption of this rhythm is associated with type 2 diabetes. Feeding is one factor that sets the circadian clock in peripheral tissues, but relatively little is known about the role of specific dietary components in that regard. We assessed the effects of dietary iron on circadian gluconeogenesis. Dietary iron affects circadian glucose metabolism through heme-mediated regulation of the interaction of nuclear receptor subfamily 1 group d member 1 (Rev-Erbα) with its cosuppressor nuclear receptor corepressor 1 (NCOR). Loss of regulated heme synthesis was achieved by aminolevulinic acid (ALA) treatment of mice or cultured cells to bypass the rate-limiting enzyme in hepatic heme synthesis, ALA synthase 1 (ALAS1). ALA treatment abolishes differences in hepatic glucose production and in the expression of gluconeogenic enzymes seen with variation of dietary iron. The differences among diets are also lost with inhibition of heme synthesis with isonicotinylhydrazine. Dietary iron modulates levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a transcriptional activator of ALAS1, to affect hepatic heme. Treatment of mice with the antioxidant N-acetylcysteine diminishes PGC-1α variation observed among the iron diets, suggesting that iron is acting through reactive oxygen species signaling.

  1. Serum hepcidin levels in Helicobacter pylori-infected children with iron-deficiency anemia: a case-control study.

    Science.gov (United States)

    Azab, Seham F A; Esh, Asmaa M H

    2013-11-01

    Recently, hepcidin, an antimicrobial-like peptide hormone, has evolved as the master regulator of systemic iron homeostasis. Hepcidin integrates signals from diverse physiological inputs, forming a key connection between iron trafficking and response to infection. In this study, we aimed to investigate whether Helicobacter pylori infection modulates serum hepcidin level and response to oral iron therapy in children with iron-deficiency anemia. This was a case-control study including 60 children with iron-deficiency anemia (IDA; 30 H. pylori infected and 30 H. pylori noninfected) and 30 healthy children with comparable age and gender as the control group. Iron parameters including serum iron, ferritin, transferrin, total iron binding capacity, and transferrin saturation and serum hepcidin levels were assessed initially and after 3 months of oral iron therapy for IDA. Compared to the control group, serum hepcidin was significantly lower in H. pylori-noninfected children with IDA (P iron therapy (P iron therapy (P > 0.05). Although hepcidin showed significant positive correlations with serum ferritin, hemoglobin (Hb), iron, and transferrin saturation in noninfected children with IDA (P iron, and transferrin saturation in H. pylori-infected children with IDA (P iron therapy in children with iron-deficiency anemia.

  2. Externally controlled triggered-release of drug from PLGA micro and nanoparticles.

    Directory of Open Access Journals (Sweden)

    Xin Hua

    Full Text Available Biofilm infections are extremely hard to eradicate and controlled, triggered and controlled drug release properties may prolong drug release time. In this study, the ability to externally control drug release from micro and nanoparticles was investigated. We prepared micro/nanoparticles containing ciprofloxacin (CIP and magnetic nanoparticles encapsulated in poly (lactic-co-glycolic acid PLGA. Both micro/nanoparticles were observed to have narrow size distributions. We investigated and compared their passive and externally triggered drug release properties based on their different encapsulation structures for the nano and micro systems. In passive release studies, CIP demonstrated a fast rate of release in first 2 days which then slowed and sustained release for approximately 4 weeks. Significantly, magnetic nanoparticles containing systems all showed ability to have triggered drug release when exposed to an external oscillating magnetic field (OMF. An experiment where the OMF was turned on and off also confirmed the ability to control the drug release in a pulsatile manner. The magnetically triggered release resulted in a 2-fold drug release increase compared with normal passive release. To confirm drug integrity following release, the antibacterial activity of released drug was evaluated in Pseudomonas aeruginosa biofilms in vitro. CIP maintained its antimicrobial activity after encapsulation and triggered release.

  3. Factors controlling alkalisalt deposition in recovery boiler- release mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    McKeough, P.; Kylloenen, H.; Kurkela, M. [VTT Energy, Espoo (Finland). Process Technology Group

    1996-12-01

    As part of a cooperative effort to develop a model to describe the behaviour of inorganic compounds in kraft recovery boilers, an experimental investigation of the release of sulphur during black liquor pyrolysis has been undertaken. Previous to these studies, the mechanisms of sulphur release and the reasons for the observed effects of process conditions on sulphur release were very poorly understood. On the basis of the experimental results, the main reactions leading to sulphur release have been elucidated with a fair degree of certainty. Logical explanations for the variations of sulphur release with temperature and with liquor solids content have been proposed. The influence of pressure has been investigated in order to gain insights into the effects of mass transfer on the sulphur-release rate. In the near future, the research will be aimed at generating the kinetic data necessary for modelling the release of sulphur in the recovery furnace. (author)

  4. Temporal control of drug release from biodegradable polymer: multicomponent diclofenac sodium releasing PLGA 80/20 rod.

    Science.gov (United States)

    Nikkola, Lila; Viitanen, Petrus; Ashammakhi, Nureddin

    2009-05-01

    In our previous studies we have reported on the development of diclofenac sodium (DS) releasing rods. However, their drug release profiles were unsatisfactory. To enhance the drug release properties of the implant, we have developed a system whereby various elements can be combined into one implant. Melt extruded, self-reinforced (SR), and sterilized (S) DS-containing SR-PLGA 80/20 billets were combined to produce multicomponent implants with various compositions. These components were basically heat pressed together to form multicomponent rods. Drug release from single component and multicomponent rods was defined using a UV-Vis spectrophotometer. DS was released from individual components within 82-111 days and from multicomponent rods within 50-70 days. Thermal properties were analyzed using differential scanning calorimetry (DSC). The melting temperature (T(m)) of multicomponent implants was about 157 degrees C, change in heat fusion (DeltaH) was 13.3 J/g, and the glass transition temperature (T(g)) was 55.4 degrees C. Mechanical strength was measured for 2 weeks and it decreased from 55 to 15 MPa. In conclusion, by compression molding three components with different release rates it is possible to control the temporal release from multicomponent rods. Released DS concentrations were within range for 49-74 days depending on the fractions of individual components used.

  5. Reaction-Multi Diffusion Model for Nutrient Release and Autocatalytic Degradation of PLA-Coated Controlled-Release Fertilizer

    Directory of Open Access Journals (Sweden)

    Sayed Ameenuddin Irfan

    2017-03-01

    Full Text Available A mathematical model for the reaction-diffusion equation is developed to describe the nutrient release profiles and degradation of poly(lactic acid (PLA-coated controlled-release fertilizer. A multi-diffusion model that consists of coupled partial differential equations is used to study the diffusion and chemical reaction (autocatalytic degradation simultaneously. The model is solved using an analytical-numerical method. Firstly, the model equation is transformed using the Laplace transformation as the Laplace transform cannot be inverted analytically. Numerical inversion of the Laplace transform is used by employing the Zakian method. The solution is useful in predicting the nutrient release profiles at various diffusivity, concentration of extraction medium, and reaction rates. It also helps in explaining the transformation of autocatalytic concentration in the coating material for various reaction rates, times of reaction, and reaction-multi diffusion. The solution is also applicable to the other biodegradable polymer-coated controlled-release fertilizers.

  6. The Study of HFE Genotypes and Its Expression Effect on Iron Status of Iranian Haemochromatosis, Iron Deficiency Anemia Patients, Iron-Taker and Non Iron-Taker Controls.

    Science.gov (United States)

    Beiranvand, Elham; Abediankenari, Saeid; Rostamian, Mosayeb; Beiranvand, Behnoush; Naazeri, Saeed

    2015-01-01

    The role of HFE gene mutations or its expression in regulation of iron metabolism of hereditary haemochromatosis (HH) patients is remained controversial. Therefore here the correlation between two common HFE genotype (p.C282Y, p.H63D) and HFE gene expression with iron status in HH, iron deficiency anemia (IDA) and healthy Iranian participants was studied. For this purpose genotype determination was done by polymerase chain reaction--restriction fragment length polymorphism (PCR-RFLP). Real-Time PCR was applied for evaluation of HFE gene expression. Biochemical parameters and iron consumption were also assessed. Homozygote p.H63D mutation was seen in all HH patients and p.C282Y was not observed in any member of the population. A significant correlation was observed between serum ferritin (SF) level and gender or age of HH patients. p.H63D homozygote was seen to be able to significantly increase SF and transferrin saturation (TS) level without affecting on liver function. Our results also showed that iron consumption affects on TS level increasing. HFE gene expression level of IDA patients was significantly higher than other groups. Also the HFE gene expression was negatively correlated with TS. Finally, the main result of our study showed that loss of HFE function in HH is not derived from its gene expression inhibition and much higher HFE gene expression might lead to IDA. However we propose repeating of the study for more approval of our finding.

  7. Reduced cognitive and psychomotor impairment with extended-release oxymorphone versus controlled-release oxycodone.

    Science.gov (United States)

    Schoedel, Kerri A; McMorn, Stephen; Chakraborty, Bijan; Zerbe, Kathleen; Sellers, Edward M

    2010-01-01

    Opioids provide effective pain control, yet have risks including adverse events (AEs) (e.g., constipation, nausea/vomiting, sedation) and cognitive/psychomotor effects. To compare cognitive and psychomotor effects of oxymorphone extended release (OM-ER) versus oxycodone controlled release (OC-CR). Randomized, double-blind, 5-way crossover Single inpatient research unit Nondependent recreational opioid users were administered single intact oral tablets of placebo, OM-ER (15 and 30 mg), and OC-CR (30 and 60 mg), separated by a 7- to 21-day washout. The divided attention (DA) test measured psychomotor impairment (e.g., manual tracking [e.g., percentage over road], target accuracy [e.g., target hits], reaction time [hit latency]). Visual analog scales measured alertness/drowsiness, agitation/relaxation, and dizziness. Sedative, stimulant, and dysphoric effects were measured using the Addiction Research Center Inventory Pentobarbital-Chlorpromazine-Alcohol (PCAG), Benzedrine Group (BG), and Lysergic Acid Diethylamide (LSD) scales, respectively. Comparisons were made between equianalgesic doses (OM-ER 15 mg vs OC-CR 30 mg; OM-ER 30 mg vs OC-CR 60 mg), within active drug doses, and between active drugs and placebo using least squares (LS) mean difference of the peak maximum (Emax) or minimum (Emin) effect using linear mixed model analysis of covariance. Thirty-five participants received all 5 treatments. Peak cognitive and psychomotor impairment (LS mean [SE]) was less with OM-ER than equianalgesic doses of OC-CR for reaction time (Emax hit latency, longer if impaired; 571.2 [13.4] vs 588.1 ms [13.4], P=0.03 for OM-ER 15 mg vs OC-CR 30 mg, respectively; 572.4 [13.4] vs 604.3 ms [13.4], P=0.03 for OM-ER 15 mg vs OC-CR 30 mg, respectively; 572.4 [13.4] vs 604.3 ms [13.4], PLSD, P<0.001 for both equianalgesic dose groups), and sedation (Emax, PCAG; P<0.001 for both equianalgesic dose groups) and less stimulation (BG, Emin; P=0.01 for OM-ER 15 mg vs OC-CR mg; P<0.001 for OM

  8. Levitation of an iron ball in midair without active control

    Science.gov (United States)

    Sasaki, S.; Yagi, I.; Murakami, M.

    2004-02-01

    An iron ball floats in midair in a plastic box when several iron balls were attracted by a permanent magnet. A complex interaction between magnetized sphere materials and a lifting magnet enabled the suspension of an iron ball. The balls in the first row are simply attracted by the lifting magnet. The ball in the second row is also attracted by the lifting magnet, however, due to the repulsive forces exerted from the balls sitting above, it can float in midair. We also found that there are two stable positions for the ball to float. The floating ball could be transported from one equilibrium position to another by simply rotating the lifting magnet. This will make it possible to construct a noncontact load transport device.

  9. Ferric Citrate Controls Phosphorus and Delivers Iron in Patients on Dialysis

    Science.gov (United States)

    Sika, Mohammed; Koury, Mark J.; Chuang, Peale; Schulman, Gerald; Smith, Mark T.; Whittier, Frederick C.; Linfert, Douglas R.; Galphin, Claude M.; Athreya, Balaji P.; Nossuli, A. Kaldun Kaldun; Chang, Ingrid J.; Blumenthal, Samuel S.; Manley, John; Zeig, Steven; Kant, Kotagal S.; Olivero, Juan Jose; Greene, Tom; Dwyer, Jamie P.

    2015-01-01

    Patients on dialysis require phosphorus binders to prevent hyperphosphatemia and are iron deficient. We studied ferric citrate as a phosphorus binder and iron source. In this sequential, randomized trial, 441 subjects on dialysis were randomized to ferric citrate or active control in a 52-week active control period followed by a 4-week placebo control period, in which subjects on ferric citrate who completed the active control period were rerandomized to ferric citrate or placebo. The primary analysis compared the mean change in phosphorus between ferric citrate and placebo during the placebo control period. A sequential gatekeeping strategy controlled study-wise type 1 error for serum ferritin, transferrin saturation, and intravenous iron and erythropoietin-stimulating agent usage as prespecified secondary outcomes in the active control period. Ferric citrate controlled phosphorus compared with placebo, with a mean treatment difference of −2.2±0.2 mg/dl (mean±SEM) (Pferric citrate and active control, with comparable safety profiles. Subjects on ferric citrate achieved higher mean iron parameters (ferritin=899±488 ng/ml [mean±SD]; transferrin saturation=39%±17%) versus subjects on active control (ferritin=628±367 ng/ml [mean±SD]; transferrin saturation=30%±12%; Pferric citrate received less intravenous elemental iron (median=12.95 mg/wk ferric citrate; 26.88 mg/wk active control; Pagent (median epoetin-equivalent units per week: 5306 units/wk ferric citrate; 6951 units/wk active control; P=0.04). Hemoglobin levels were statistically higher on ferric citrate. Thus, ferric citrate is an efficacious and safe phosphate binder that increases iron stores and reduces intravenous iron and erythropoietin-stimulating agent use while maintaining hemoglobin. PMID:25060056

  10. Solid lipid nanoparticles (SLN) for controlled drug delivery--drug release and release mechanism.

    Science.gov (United States)

    zur Mühlen, A; Schwarz, C; Mehnert, W

    1998-03-01

    Solid lipid nanoparticles (SLN) are particulate systems for parenteral drug administration with mean particle diameters ranging from 50 up to 1000 nm. The model drugs tetracaine, etomidate and prednisolone were incorporated (1, 5 and 10%) to study the drug load, effect of drug incorporation on the structure of the lipid matrix and the release profiles and mechanism. SLN were produced by high pressure homogenization of aqueous surfactant solutions containing the drug-loaded lipids in the melted or in the solid state (500/1500 bar, 3/10 cycles). In case of tetracaine and etomidate, high drug loadings up to 10% could be achieved when using Compritol 888 ATO and Dynasan 112 as matrix material. The melting behavior of the drug loaded particles revealed that little or no interactions between drug and lipid occurred. A burst drug release (100% release < 1 min) was observed with tetracaine and etomidate SLN, which was attributed to the large surface area of the nanoparticles and drug enrichment in the outer shell of the particles. In contrast, prednisolone loaded SLN showed a distinctly prolonged release over a monitored period of 5 weeks. Depending on the chemical nature of the lipid matrix, 83.8 and 37.1% drug were released (cholesterol and compritol, respectively). These results demonstrate the principle suitability of SLN as a prolonged release formulation for lipophilic drugs.

  11. Release mechanisms behind polysaccharides-based famotidine controlled release matrix tablets.

    Science.gov (United States)

    Elmowafy, Enas M; Awad, Gehanne A S; Mansour, Samar; El-Shamy, Abd El-Hamid A

    2008-01-01

    Polysaccharides, which have been explored to possess gelling properties and a wide margin of safety, were used to formulate single-unit floating matrix tablets by a direct compression technique. This work has the aim to allow continuous slow release of famotidine above its site of absorption. The floating approach was achieved by the use of the low density polypropylene foam powder. Polysaccharides (kappa-carrageenan, gellan gum, xyloglucan, and pectin) and blends of polysaccharides (kappa-carrageenan and gellan gum) and cellulose ethers (hydroxypropylmethyl cellulose, hydroxypropylcellulose, sodium carboxymethyl cellulose) were tried to modulate the release characteristics. The prepared floating tablets were evaluated for their floating behavior, matrix integrity, swelling studies, in vitro drug release studies, and kinetic analysis of the release data. The differential scanning calorimetry and Fourier transform infrared spectroscopy studies revealed that changing the polymer matrix system by formulation of polymers blends resulted in formation of molecular interactions which may have implications on drug release characteristics. This was obvious from the retardation in drug release and change in its mechanistics.

  12. Controlled Release of the Indomethacin Microencapsulation Based on Layer-by-layer Assembly by Polyelectrolyte Multilayers

    Institute of Scientific and Technical Information of China (English)

    CHEN You-fang; LIN Xian-fu

    2007-01-01

    Indomethacin has been encapsulated with polyelectrolyte multilayers for controlled release. Gelatin and alginate were alternatively deposited on indomethacin microcrystals. The released amount of indomethacin from coated microcrystals in pH6. 8phosphate buffer solution (PBS) was measured with a UV spectrophometer. The polyelectrolyte multilayer capsule thickness was proved to control the release rate. The effects of osmotic pressure existed during the release process of indomethacin from microcapsules coated by (gelatin/alginate) 4.

  13. Leaching of Iron, Controlling Factors and Implication to Arsenic Mobilization in an aquifer of the Brahmaputra Floodplain

    NARCIS (Netherlands)

    Baviskar, S.M.; Mahanta, C.; Choudhary, R.

    2011-01-01

    To understand the process of iron leaching and arsenic (As) mobilization, three bore wells were drilled in suspected iron and arsenic enriched areas of Jorhat, Assam, India, to study possible release and mobilization process in the aquifer. Sediments and groundwater samples, collected from different

  14. Aggregate-Scale Variation in Iron Biogeochemistry Controls Element Cycling from Nitrogen to Uranium

    Science.gov (United States)

    Fendorf, S. E.; Ying, S.; Jones, L. C.; Jones, M. E.

    2014-12-01

    Iron exerts a major control on element cycling in soils by serving as a prominent sorbent (principally when present as an oxide phase) and as an electron acceptor (in the ferric-form) or donor (ferrous-form) in both chemical and microbially-mediated reactions. Within the aggregated structure of soils, steep chemical gradients arise from the supply of oxygen and nutrients along macropores that are rapidly consumed (relative to supply) within the micropore domains of aggregate interiors. As a consequence, iron undergoes a dynamic biogeochemical cycle whereby ferric (hydr)oxides form within aggregate exteriors while ferrous-iron generation dominates within interior regions. Further, inter-aggregate cycling of iron can transpire through the supply of electron donors and acceptors, linked with diffusive controlled response to gradients. Coupling to iron transformation are the varying retention of adsorptives such as lead and phosphorus and the redox alterations of elements from nitrogen to uranium. Nitrate, for example, diffusing into aggregate interiors encounters ferrous-iron fronts where the ensuring oxidation of Fe(II)-coupled to nitrate reduction transpires. The outcome of aggregate-scale iron transformations, described within this presentation, is fundamental controls on the cycling of redox active elements from nutrients such as carbon and nitrogen to contaminants such arsenic and uranium.

  15. Effect of ascorbic acid on iron release from the emulsifier interface and on the oxidative flavor deterioration in fish oil enriched mayonnaise.

    Science.gov (United States)

    Jacobsen, C; Adler-Nissen, J; Meyer, A S

    1999-12-01

    This research examines the effect of ascorbic acid (0-800 ppm) on the sensory perception of mayonnaises containing 16% fish oil and on the levels of iron and copper in the aqueous phase. Ascorbic acid increased the formation of fishy off-flavors in fresh mayonnaise. Simultaneously, the iron concentration increased from below the detection limit (1.8 microM) to 34 microM in the aqueous phase of mayonnaises. Model mayonnaises with various concentrations of egg yolk (1-7% w/w) and ascorbic acid (0-8000 ppm) were prepared. Iron concentrations in the aqueous phase increased with increasing ascorbic acid levels, whereas iron concentrations in the assumed interfacial layer decreased. It is proposed that ascorbic acid is able to complex and reduce Fe(3+) to Fe(2+) from phosvitin in the egg yolk, whereby iron is released from the interface. The ascorbic acid-iron complex subsequently reacts with lipid hydroperoxides, resulting in increased lipid oxidation and in the immediate formation of rancid and fishy off-flavors.

  16. Novel anhydrous emulsions: formulation as controlled release vehicles.

    Science.gov (United States)

    Suitthimeathegorn, Orawan; Jaitely, Vikas; Florence, Alexander T

    2005-07-25

    Novel anhydrous emulsions, which may offer some advantages as depot or reservoir vehicles for lipophilic drugs in controlled delivery systems, were formulated using castor oil as the disperse phase and dimethicone or cyclopentasiloxane as the continuous phase. Among the emulsifiers studied only silicone surfactants (cyclomethicone/dimethicone copolyols) which were miscible in silicone oil stabilized the emulsions. Cyclomethicone/PEG/PPG-18/18 Dimethicone and Cyclopentasiloxane/PEG/PPG-18/18 Dimethicone were more effective in lowering the interfacial tension between castor oil and both dimethicone and cyclopentasiloxane. Emulsions formulated using either of these two surfactants were found to be stable against phase separation and exhibited least globule growth over 168 h. The average particle size was found to be 2-6 microm in these systems formed by probe sonication. Slow release patterns of 3H-dehydroepiandrosterone (DHEA) and 3H-dexamethasone solubilized in the disperse castor oil phase into an aqueous dialyzing medium were observed over 48 h.

  17. Mechanoresponsive materials for drug delivery: Harnessing forces for controlled release.

    Science.gov (United States)

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

    2017-01-01

    Mechanically-activated delivery systems harness existing physiological and/or externally-applied forces to provide spatiotemporal control over the release of active agents. Current strategies to deliver therapeutic proteins and drugs use three types of mechanical stimuli: compression, tension, and shear. Based on the intended application, each stimulus requires specific material selection, in terms of substrate composition and size (e.g., macrostructured materials and nanomaterials), for optimal in vitro and in vivo performance. For example, compressive systems typically utilize hydrogels or elastomeric substrates that respond to and withstand cyclic compressive loading, whereas, tension-responsive systems use composites to compartmentalize payloads. Finally, shear-activated systems are based on nanoassemblies or microaggregates that respond to physiological or externally-applied shear stresses. In order to provide a comprehensive assessment of current research on mechanoresponsive drug delivery, the mechanical stimuli intrinsically present in the human body are first discussed, along with the mechanical forces typically applied during medical device interventions, followed by in-depth descriptions of compression, tension, and shear-mediated drug delivery devices. We conclude by summarizing the progress of current research aimed at integrating mechanoresponsive elements within these devices, identifying additional clinical opportunities for mechanically-activated systems, and discussing future prospects.

  18. PH-triggered micellar membrane for controlled release microchips

    KAUST Repository

    Yang, Xiaoqiang

    2011-01-01

    A pH-responsive membrane based on polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer was developed on a model glass microchip as a promising controlled polymer delivery system. The PS-b-P4VP copolymer assembles into spherical and/or worm-like micelles with styrene block cores and pyridine coronas in selective solvents. The self-assembled worm-like morphology exhibited pH-responsive behaviour due to the protonation of the P4VP block at low pH and it\\'s deprotonation at high pH and thus constituting a switchable "off/on" system. Doxorubicin (Dox) was used as cargo to test the PS-b-P4VP membrane. Luminescence experiments indicated that the membrane was able to store Dox molecules within its micellar structure at neutral pH and then release them as soon as the pH was raised to 8.0. The performance of the cast membrane was predictable and most importantly reproducible. The physiochemical and biological properties were also investigated carefully in terms of morphology, cell viability and cell uptake. This journal is © The Royal Society of Chemistry.

  19. The effect of some fluids on surface oxidation and amount of released iron of stainless steel endodontic files.

    Science.gov (United States)

    Saghiri, Mohammad Ali; García-Godoy, Franklin; Lotfi, Mehrdad; Mehrvazfar, Peyman; Aminsobhani, Mohsen; Rezaie, Samad; Asgar, Kamal

    2012-01-01

    Endodontic files come in contact with blood, infected pulp tissue, and irrigating solutions during root canal therapy. Some instruments such as stereomicroscopy and scanning electron microscopy are used to observe corrosion of endodontic files which are complicated and dependent on preparation methods. Having knowledge of the corrosion and ion release of endodontic files can help in drawing firm deductions as to which files would perform better in the clinical scenario. Therefore, we have used energy dispersive X-ray analysis and an atomic absorption spectrophotometer to track oxygen on the surface and iron in the exposed media to observe the oxidative rate of the media. In this study, corrosion by blood was higher than other biological fluids, but less than with sodium hypochlorite (NaOCl). Observations of energy dispersive X-ray analysis and atomic absorption spectrophotometer results demonstrated that after exposure the amount of oxygen on the surface and surrounding areas increased. Therefore, the files should be rinsed as soon as possible during and after use to hinder the oxidation rate, but blood may produce a different behavior and it might be considered as a decreased risk of broken stainless steel files remaining in the root canal after treatment.

  20. Complex comprised of dextran magnetite and conjugated cisplatin exhibiting selective hyperthermic and controlled-release potential

    Directory of Open Access Journals (Sweden)

    Akinaga Sonoda

    2010-07-01

    Full Text Available Akinaga Sonoda1, Norihisa Nitta1, Ayumi Nitta-Seko1, Shinich Ohta1, Shigeyuki Takamatsu2, Yoshio Ikehata3, Isamu Nagano3, Jun-ichiro Jo4, Yasuhiko Tabata4, Masashi Takahashi1, Osamu Matsui3, Kiyoshi Murata11Department of Radiology, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga, 520-2192, Japan; 2Department of Radiology, Graduate School of Medical Science, Kanazawa University, Takara-machi 13-1, Kanazawa Ishikawa, 920-8641, Japan; 3Department of Natural Science and Technology, Graduate School of Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan; 4Department of Biomaterials, Institute for Frontier Medical Sciences, Kyoto University, Shogoin kawara-machi 53, Sakyo-ku 606-8507, Kyoto, JapanAbstract: We developed a dextran-magnetite conjugated cisplatin (DM-Cis complex for use in thermal ablation and as a chemotherapeutic drug. To produce DM-Cis we reacted Cis with 1 mL DM (56 mg/mL iron. The temperature rise of DM-Cis was measured in vitro and in vivo under a portable induction-heating (IH device. Platinum desorption from DM-Cis over 24 hours was measured in bovine serum. In in vivo accumulation and magnet and exothermic experiments we used four rat groups. In group 1 we delivered DM-Cis intraperitoneally (ip and placed magnets subcutaneously (sc. In group 2 we injected saline (ip and placed magnets (sc. In group 3 we injected DM-Cis (ip and placed a sc incision (sham. The control (group 4 received an ip injection of saline. Rectus abdominis muscle tissue was stained with hematoxylin-eosin and iron-stained tissue areas (µm2 were calculated. The maximum platinum concentration in DM-Cis was approximately 105.6 µg/mL. Over 24 hours, 33.48% of platinum from DM-Cis was released. There was a significant difference (P < 0.05 in the iron-stained area between group 1 and the other groups. The temperature in muscle tissue registered a maximum of 56°C after about 4 min. DM-Cis may represent a

  1. A multi-scale model of hepcidin promoter regulation reveals factors controlling systemic iron homeostasis.

    Directory of Open Access Journals (Sweden)

    Guillem Casanovas

    2014-01-01

    Full Text Available Systemic iron homeostasis involves a negative feedback circuit in which the expression level of the peptide hormone hepcidin depends on and controls the iron blood levels. Hepcidin expression is regulated by the BMP6/SMAD and IL6/STAT signaling cascades. Deregulation of either pathway causes iron-related diseases such as hemochromatosis or anemia of inflammation. We quantitatively analyzed how BMP6 and IL6 control hepcidin expression. Transcription factor (TF phosphorylation and reporter gene expression were measured under co-stimulation conditions, and the promoter was perturbed by mutagenesis. Using mathematical modeling, we systematically analyzed potential mechanisms of cooperative and competitive promoter regulation by the transcription factors, and experimentally validated the model predictions. Our results reveal that hepcidin cross-regulation primarily occurs by combinatorial transcription factor binding to the promoter, whereas signaling crosstalk is insignificant. We find that the presence of two BMP-responsive elements enhances the steepness of the promoter response towards the iron-sensing BMP signaling axis, which promotes iron homeostasis in vivo. IL6 co-stimulation reduces the promoter sensitivity towards the BMP signal, because the SMAD and STAT transcription factors compete for recruiting RNA polymerase to the transcription start site. This may explain why inflammatory signals disturb iron homeostasis in anemia of inflammation. Taken together, our results reveal why the iron homeostasis circuit is sensitive to perturbations implicated in disease.

  2. A Preliminary Study on Natural Matrix Materials for Controlled Release Nitrogen Fertilizers

    Institute of Scientific and Technical Information of China (English)

    DU Chang-Wen; ZHOU Jian-Min; WANG Huo-Yan; LI Shou-Tian

    2004-01-01

    A controlled release N fertilizer was developed by the carrier method using natural polysaccharides (PS)and urea. The results showed that mixing of PS and urea led to significant control of urea release. When a cross-linker (boric acid or glutaraldehyde) was added, a better control effect was observed. During a 30 min leaching time the nitrogen release rate from the controlled release fertilizer was nearly constant, which was significantly different from normal urea. One of the controlled release mechanisms was related to space resistance from a large molecular structure. Infrared (IR) analysis indicated that interaction of PS with urea was through a hydrogen bond or a covalent bond. These bonds created an α-helix or high molecular network fertilizer carrier system, which was another reason for a controlled nutrient release. Pot experiment showed that nitrogen use efficiency could increase significantly with a carrier fertilizer.

  3. Poly (lactic-co-glycolic acid) controlled release systems: experimental and modeling insights

    Science.gov (United States)

    Hines, Daniel J.; Kaplan, David L.

    2013-01-01

    Poly-lactic-co-glycolic acid (PLGA) has been the most successful polymeric biomaterial for use in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in drug release device formulation. Mathematical modeling is a useful tool for identifying, characterizing, and predicting the mechanisms of controlled release. The advantages and limitations of poly (lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled release technology that utilize PLGA. Mathematical modeling applied towards controlled release rates from PLGA-based devices will also be discussed to provide a complete picture of state of the art understanding of the control achievable with this polymeric system, as well as the limitations. PMID:23614648

  4. Poly(lactic-co-glycolic) acid-controlled-release systems: experimental and modeling insights.

    Science.gov (United States)

    Hines, Daniel J; Kaplan, David L

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) has been the most successful polymeric biomaterial used in controlled drug delivery systems. There are several different chemical and physical properties of PLGA that impact the release behavior of drugs from PLGA delivery devices. These properties must be considered and optimized in the formulation of drug release devices. Mathematical modeling is a useful tool for identifying, characterizing, and predicting mechanisms of controlled release. The advantages and limitations of poly(lactic-co-glycolic acid) for controlled release are reviewed, followed by a review of current approaches in controlled-release technology that utilize PLGA. Mathematical modeling applied toward controlled-release rates from PLGA-based devices also will be discussed to provide a complete picture of a state-of-the-art understanding of the control that can be achieved with this polymeric system, as well as the limitations.

  5. Controlled-release NPK fertilizer encapsulated by polymeric membranes.

    Science.gov (United States)

    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.

  6. Preparation and characterization of metoprolol controlled-release solid dispersions.

    Science.gov (United States)

    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.

  7. Siderophore-mediated iron dissolution from nontronites is controlled by mineral cristallochemistry

    Directory of Open Access Journals (Sweden)

    Damien eParrello

    2016-03-01

    Full Text Available Bacteria living in oxic environments experience iron deficiency due to limited solubility and slow dissolution kinetics of iron-bearing minerals. To cope with iron deprivation, aerobic bacteria have evolved various strategies, including release of siderophores or other organic acids that scavenge external Fe(III and deliver it to the cells. This research investigated the role of siderophores produced by Pseudomonas aeruginosa in the acquisition of Fe(III from two iron-bearing colloidal nontronites (NAu-1 and NAu-2, comparing differences in bioavailability related with site occupancy and distribution of Fe(III in the two lattices. To avoid both the direct contact of the mineral colloids with the bacterial cells and the uncontrolled particle aggregation, nontronite suspensions were homogenously dispersed in a porous silica gel before the dissolution experiments. A multiparametric approach coupling UV-vis spectroscopy and spectral decomposition algorithm was implemented to monitor simultaneously the solubilisation of Fe and the production of pyoverdine in microplate-based batch experiments. Both nontronites released Fe in a particle concentration-dependent manner when incubated with the wild-type P. aeruginosa strain, however iron released from NAu-2 was substantially greater than from NAu-1. The profile of organic acids produced in both cases was similar and may not account for the difference in the iron dissolution efficiency. In contrast, a pyoverdine-deficient mutant was unable to mobilise Fe(III from either nontronite, whereas iron dissolution occurred in abiotic experiments conducted with purified pyoverdine. Overall, our data provide evidence that P. aeruginosa indirectly mobilise Fe from nontronites primarily through the production of pyoverdine. The structural Fe present on the edges of Nau-2 rather than Nau-1 particles appears to be more bio-accessible, indicating that the distribution of Fe, in the tetrahedron and/or in the octahedron

  8. Effect of diluents on tablet integrity and controlled drug release.

    Science.gov (United States)

    Zhang, Y E; Schwartz, J B

    2000-07-01

    The objective of this study was to evaluate the effect of diluents and wax level on tablet integrity during heat treatment and dissolution for sustained-release formulations and the resultant effect on drug release. Dibasic calcium phosphate dihydrate (DCPD), microcrystalline cellulose (MCC), and lactose were evaluated for their effect on tablet integrity during drug dissolution and heat treatment in wax matrix formulations. A newly developed direct compression diluent, dibasic calcium phosphate anhydrous (DCPA), was also evaluated. Compritol 888 ATO was used as the wax matrix material, with phenylpropanolamine hydrochloride (PPA) as a model drug. Tablets were made by direct compression and then subjected to heat treatment at 80 degrees C for 30 min. The results showed that MCC, lactose, and DCPA could maintain tablets intact during heat treatment above the melting point of wax (70 degrees C-75 degrees C). However, DCPD tablets showed wax egress during the treatment. MCC tablets swelled and cracked during drug dissolution and resulted in quick release. DCPD and lactose tablets remained intact during dissolution and gave slower release than MCC tablets. DCPA tablets without heat treatment disintegrated very quickly and showed immediate release. In contrast, heat-treated DCPA tablets remained intact through the 24-hr dissolution test and only released about 80% PPA at 6 hr. In the investigation of wax level, DCPD was used as the diluent. The drug release rate decreased as the wax content increased from 15% to 81.25%. The dissolution data were best described by the Higuchi square-root-of-time model. Diluents showed various effects during heat treatment and drug dissolution. The integrity of the tablets was related to the drug release rate. Heat treatment retarded drug release if there was no wax egress.

  9. Control of iron deficiency anemia in low- and middle-income countries.

    Science.gov (United States)

    Pasricha, Sant-Rayn; Drakesmith, Hal; Black, James; Hipgrave, David; Biggs, Beverley-Ann

    2013-04-04

    Despite worldwide economic and scientific development, more than a quarter of the world's population remains anemic, and about half of this burden is a result of iron deficiency anemia (IDA). IDA is most prevalent among preschool children and women. Among women, iron supplementation improves physical and cognitive performance, work productivity, and well-being, and iron during pregnancy improves maternal, neonatal, infant, and even long-term child outcomes. Among children, iron may improve cognitive, psychomotor, and physical development, but the evidence for this is more limited. Strategies to control IDA include daily and intermittent iron supplementation, home fortification with micronutrient powders, fortification of staple foods and condiments, and activities to improve food security and dietary diversity. The safety of routine iron supplementation in settings where infectious diseases, particularly malaria, are endemic remains uncertain. The World Health Organization is revising global guidelines for controlling IDA. Implementation of anemia control programs in developing countries requires careful baseline epidemiologic evaluation, selection of appropriate interventions that suit the population, and ongoing monitoring to ensure safety and effectiveness. This review provides an overview and an approach for the implementation of public health interventions for controlling IDA in low- and middle-income countries, with an emphasis on current evidence-based recommendations.

  10. CONTROLLED-RELEASE OF PARACETAMOL FROM AMYLODEXTRIN TABLETS - IN-VITRO AND IN-VIVO RESULTS

    NARCIS (Netherlands)

    VANDERVEEN, J; EISSENS, AC; LERK, CF

    1994-01-01

    Amylodextrin is a suitable excipient for the design of solid controlled-release systems. The release of paracetamol from tablets containing 30% drug and 70% amylodextrin was studied in vitro and in vivo. In vitro dissolution profiles showed almost-constant drug release rates during 8 hr, when measur

  11. Use of natural and biobased materials for controlled-release of urea in water: Environmental applications

    Science.gov (United States)

    Urea pearls were encapsulated in cloisite-based matrices using different natural materials (lignin, beeswax and latex) to control the release of urea over time. It was found that all cloisite-based fertilizer tablets showed better release profiles than neat urea tablets. The best release profile was...

  12. Effects of Controlled Release Fertilizer on the Flag Leaves Senescence in Dry-land Wheat

    OpenAIRE

    Dandan Liu; Yan Shi

    2013-01-01

    In order to select a reasonable controlled release fertilizer application method to slow down the senescence of flag leaf in dry-land wheat. The effects of controlled release fertilizer on soluble protein content, MDA content, the Catalase (CAT) activity, the Superoxide Dismutase (SOD) activity on the flag leaves senescence in dry-land wheat had been studied in the open field with the variety wheat Jimai22. The results indicated that, the combination application of controlled release fertiliz...

  13. Materials for Pharmaceutical Dosage Forms: Molecular Pharmaceutics and Controlled Release Drug Delivery Aspects

    Directory of Open Access Journals (Sweden)

    Patrick P. DeLuca

    2010-09-01

    Full Text Available Controlled release delivery is available for many routes of administration and offers many advantages (as microparticles and nanoparticles over immediate release delivery. These advantages include reduced dosing frequency, better therapeutic control, fewer side effects, and, consequently, these dosage forms are well accepted by patients. Advances in polymer material science, particle engineering design, manufacture, and nanotechnology have led the way to the introduction of several marketed controlled release products and several more are in pre-clinical and clinical development.

  14. Effects of Controlled Release Fertilizer on the Flag Leaves Senescence in Dry-land Wheat

    OpenAIRE

    Dandan Liu; Yan Shi

    2013-01-01

    In order to select a reasonable controlled release fertilizer application method to slow down the senescence of flag leaf in dry-land wheat. The effects of controlled release fertilizer on soluble protein content, MDA content, the Catalase (CAT) activity, the Superoxide Dismutase (SOD) activity on the flag leaves senescence in dry-land wheat had been studied in the open field with the variety wheat Jimai22. The results indicated that, the combination application of controlled release fertiliz...

  15. Controlled-release of Avermectin from Organically Modified Hydrotalcite-like Compound Nanohybrids

    Institute of Scientific and Technical Information of China (English)

    QIU,Depeng; LI,Yonghai; FU,Xiying; JIANG,Zhen; ZHAO,Xinyan; WANG,Tian; HOU,Wanguo

    2009-01-01

    The intercalation of avermectin (AVM)into sodium dodecyl sulfate(SDS)modified hydrotalcite-like com-pounds(HTlc) was carried out using an evaporating solvent enhanced intercalation method to obtain AVM-SDS-HTlc nanohybrids. It was found that the nanohybrids could well control the release of avermectin, showing the nanohybrids are a potential pesticide controlled-release formulation.The release of avermectin from AVM-SDS-HTlc nanohybrids is dependent on the pH.temperature and the presence of electrolyte in release me-dium. Acidic medium and higher temperature and the presence of electrolytes may induce the higher release rate of avermectin. The release process of avermectin from AVM-SDS-HTlc nanohybrids can be described by pseudo-first-order release kinetics, and the activation energy of release is 279 kJ/mol.

  16. Iron Status and Febrile Seizure- A Case Control Study in Children Less Than 3 Years

    Directory of Open Access Journals (Sweden)

    Mansour SADEGHZADEH

    2013-01-01

    Full Text Available  How to cite this article: Sadeghzadeh M, Khoshnevis P, Mahboubi E. Iron Status and Febrile Seizure- A Case Control Study in Children Less Than 3 Years. Iran J Child Neurol Autumn 2012; 6(4:27-31.Abstract Objective: Febrile seizure is one of the most common neurological conditions of childhood. Several theories, such as iron deficiency anemia have been proposed as the pathogenesis of this condition. The aim of this study was to find the association between iron deficiency anemia and febrile seizures in children aged 6 months to 3 years admitted in Valie Asr hospital in Zanjan. Materials &Methods Hemoglobin (Hb, mean corpuscular volume (MCV, serum iron (SI, total iron binding capacity (TIBC and SI/TIBC ratio were assessed in one hundred children with febrile seizures and compared to the values of one hundred healthy children presenting in a heath care center in the same period as the control group. Results A total of 6% of cases had iron deficiency anemia which was similar to the control group. In the case group SI/TIBC ratio below 12% was seen in 58% of children which was significantly higher than that of the control group (29%. Conclusion The results of this study suggest that although anemia was not common among febrile seizure patients, iron deficiency was more frequent in these patients. ReferencesBidabadi E, Mashouf M.. Association between iron deficiency anemia and first febrile convulsion: A case-control study. Seizure. 2009 Jan;18(5:347-51.Sadeghzadeh M, Khoshnevisasl P, Moussavinassab N, Koosha A, Norouzi M. The Relation Between Serum Zinc Level and Febrile Seizures in Children Admitted to Zanjan Valie-Asr Hospital. J Zanjan Uni Med Sci. 2011;19(74:17-24.Kumari PL, Nair MK, Nair SM, Kailas L, Geetha S. Iron deficiency as a risk factor for simple febrile seizures-a case control study. Indian Pediatr. 2012 Jan;49(1:17-9.Pisacane A, Sansone R, Impagliazzo N, Coppola A, Rolando P, D'Apuzzo A, Tregrossi C. Iron deficiency anaemia and

  17. Effects of vitamin A supplementation on iron status indices and iron deficiency anaemia: a randomized controlled trial.

    Science.gov (United States)

    Al-Mekhlafi, Hesham M; Al-Zabedi, Ebtesam M; Al-Maktari, Mohamed T; Atroosh, Wahib M; Al-Delaimy, Ahmed K; Moktar, Norhayati; Sallam, Atiya A; Abdullah, Wan Ariffin; Jani, Rohana; Surin, Johari

    2013-12-31

    Iron deficiency anaemia (IDA) is the most common nutritional deficiency in the world including developed and developing countries. Despite intensive efforts to improve the quality of life of rural and aboriginal communities in Malaysia, anaemia and IDA are still major public health problems in these communities particularly among children. A randomized, double-blind, placebo-controlled trial was conducted on 250 Orang Asli (aboriginal) schoolchildren in Malaysia to investigate the effects of a single high-dose of vitamin A supplementation (200,000 IU) on iron status indices, anaemia and IDA status. The effect of the supplement was assessed after 3 months of receiving the supplements; after a complete 3-day deworming course of 400 mg/day of albendazole tablets. The prevalence of anaemia was found to be high: 48.5% (95% CI=42.3, 54.8). Moreover, 34% (95% CI=28.3, 40.2) of the children had IDA, which accounted for 70.1% of the anaemic cases. The findings showed that the reduction in serum ferritin level and the increments in haemoglobin, serum iron and transferrin saturation were found to be significant among children allocated to the vitamin A group compared to those allocated to the placebo group (psupplementation showed a significant impact on iron status indices and IDA among Orang Asli children. Hence, providing vitamin A supplementation and imparting the knowledge related to nutritious food should be considered in the efforts to improve the nutritional and health status of these children as a part of efforts to improve the quality of life in rural and aboriginal communities.

  18. Effects of Vitamin A Supplementation on Iron Status Indices and Iron Deficiency Anaemia: A Randomized Controlled Trial

    Science.gov (United States)

    Al-Mekhlafi, Hesham M.; Al-Zabedi, Ebtesam M.; Al-Maktari, Mohamed T.; Atroosh, Wahib M.; Al-Delaimy, Ahmed K.; Moktar, Norhayati; Sallam, Atiya A.; Abdullah, Wan Ariffin; Jani, Rohana; Surin, Johari

    2013-01-01

    Iron deficiency anaemia (IDA) is the most common nutritional deficiency in the world including developed and developing countries. Despite intensive efforts to improve the quality of life of rural and aboriginal communities in Malaysia, anaemia and IDA are still major public health problems in these communities particularly among children. A randomized, double-blind, placebo-controlled trial was conducted on 250 Orang Asli (aboriginal) schoolchildren in Malaysia to investigate the effects of a single high-dose of vitamin A supplementation (200,000 IU) on iron status indices, anaemia and IDA status. The effect of the supplement was assessed after 3 months of receiving the supplements; after a complete 3-day deworming course of 400 mg/day of albendazole tablets. The prevalence of anaemia was found to be high: 48.5% (95% CI = 42.3, 54.8). Moreover, 34% (95% CI = 28.3, 40.2) of the children had IDA, which accounted for 70.1% of the anaemic cases. The findings showed that the reduction in serum ferritin level and the increments in haemoglobin, serum iron and transferrin saturation were found to be significant among children allocated to the vitamin A group compared to those allocated to the placebo group (p < 0.01). Moreover, a significant reduction in the prevalence of IDA by almost 22% than prevalence at baseline was reported among children in the vitamin A group compared with only 2.3% reduction among children in the placebo group. In conclusion, vitamin A supplementation showed a significant impact on iron status indices and IDA among Orang Asli children. Hence, providing vitamin A supplementation and imparting the knowledge related to nutritious food should be considered in the efforts to improve the nutritional and health status of these children as a part of efforts to improve the quality of life in rural and aboriginal communities. PMID:24384995

  19. Effects of Vitamin A Supplementation on Iron Status Indices and Iron Deficiency Anaemia: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Hesham M. Al-Mekhlafi

    2013-12-01

    Full Text Available Iron deficiency anaemia (IDA is the most common nutritional deficiency in the world including developed and developing countries. Despite intensive efforts to improve the quality of life of rural and aboriginal communities in Malaysia, anaemia and IDA are still major public health problems in these communities particularly among children. A randomized, double-blind, placebo-controlled trial was conducted on 250 Orang Asli (aboriginal schoolchildren in Malaysia to investigate the effects of a single high-dose of vitamin A supplementation (200,000 IU on iron status indices, anaemia and IDA status. The effect of the supplement was assessed after 3 months of receiving the supplements; after a complete 3-day deworming course of 400 mg/day of albendazole tablets. The prevalence of anaemia was found to be high: 48.5% (95% CI = 42.3, 54.8. Moreover, 34% (95% CI = 28.3, 40.2 of the children had IDA, which accounted for 70.1% of the anaemic cases. The findings showed that the reduction in serum ferritin level and the increments in haemoglobin, serum iron and transferrin saturation were found to be significant among children allocated to the vitamin A group compared to those allocated to the placebo group (p < 0.01. Moreover, a significant reduction in the prevalence of IDA by almost 22% than prevalence at baseline was reported among children in the vitamin A group compared with only 2.3% reduction among children in the placebo group. In conclusion, vitamin A supplementation showed a significant impact on iron status indices and IDA among Orang Asli children. Hence, providing vitamin A supplementation and imparting the knowledge related to nutritious food should be considered in the efforts to improve the nutritional and health status of these children as a part of efforts to improve the quality of life in rural and aboriginal communities.

  20. Local geology controlled the feasibility of vitrifying Iron Age buildings.

    Science.gov (United States)

    Wadsworth, Fabian B; Heap, Michael J; Damby, David E; Hess, Kai-Uwe; Najorka, Jens; Vasseur, Jérémie; Fahrner, Dominik; Dingwell, Donald B

    2017-01-12

    During European prehistory, hilltop enclosures made from polydisperse particle-and-block stone walling were exposed to temperatures sufficient to partially melt the constituent stonework, leading to the preservation of glassy walls called 'vitrified forts'. During vitrification, the granular wall rocks partially melt, sinter viscously and densify, reducing inter-particle porosity. This process is strongly dependent on the solidus temperature, the particle sizes, the temperature-dependence of the viscosity of the evolving liquid phase, as well as the distribution and longevity of heat. Examination of the sintering behaviour of 45 European examples reveals that it is the raw building material that governs the vitrification efficiency. As Iron Age forts were commonly constructed from local stone, we conclude that local geology directly influenced the degree to which buildings were vitrified in the Iron Age. Additionally, we find that vitrification is accompanied by a bulk material strengthening of the aggregates of small sizes, and a partial weakening of larger blocks. We discuss these findings in the context of the debate surrounding the motive of the wall-builders. We conclude that if wall stability by bulk strengthening was the desired effect, then vitrification represents an Iron Age technology that failed to be effective in regions of refractory local geology.

  1. Local geology controlled the feasibility of vitrifying Iron Age buildings

    Science.gov (United States)

    Fabian B Wadsworth,; Michael J Heap,; Damby, David; Kai-Uwe Hess,; Jens Najorka,; Jérémie Vasseur,; Dominik Fahrner,; Donald B Dingwell,

    2017-01-01

    During European prehistory, hilltop enclosures made from polydisperse particle-and-block stone walling were exposed to temperatures sufficient to partially melt the constituent stonework, leading to the preservation of glassy walls called ‘vitrified forts’. During vitrification, the granular wall rocks partially melt, sinter viscously and densify, reducing inter-particle porosity. This process is strongly dependent on the solidus temperature, the particle sizes, the temperature-dependence of the viscosity of the evolving liquid phase, as well as the distribution and longevity of heat. Examination of the sintering behaviour of 45 European examples reveals that it is the raw building material that governs the vitrification efficiency. As Iron Age forts were commonly constructed from local stone, we conclude that local geology directly influenced the degree to which buildings were vitrified in the Iron Age. Additionally, we find that vitrification is accompanied by a bulk material strengthening of the aggregates of small sizes, and a partial weakening of larger blocks. We discuss these findings in the context of the debate surrounding the motive of the wall-builders. We conclude that if wall stability by bulk strengthening was the desired effect, then vitrification represents an Iron Age technology that failed to be effective in regions of refractory local geology.

  2. Studies on pectins as potential hydrogel matrices for controlled-release drug delivery.

    Science.gov (United States)

    Sungthongjeen, S; Pitaksuteepong, T; Somsiri, A; Sriamornsak, P

    1999-12-01

    Polymeric hydrogels are widely used as controlled-release matrix tablets. In the present study, we investigated high-methoxy pectins for their potential value in controlled-release matrix formulations. The effects of compression force, ratio of drug to pectin, and type of pectin on drug release from matrix tablets were also investigated. The results of the in vitro release studies show that the drug release from compressed matrix tablets prepared from pectin can be modified by changing the amount and the type of pectin in the matrix tablets. However, compression force did not significantly affect the drug release. The mechanisms controlling release rate were discussed with respect to drug diffusion through the polymer matrices, but may be more complex.

  3. Efficacy and safety of oral iron(III) polymaltose complex versus ferrous sulfate in pregnant women with iron-deficiency anemia: a multicenter, randomized, controlled study.

    Science.gov (United States)

    Ortiz, Ricardo; Toblli, Jorge Eduardo; Romero, Juan Diego; Monterrosa, Beatriz; Frer, Cristina; Macagno, Eugenia; Breymann, Christian

    2011-11-01

    To evaluate the efficacy and safety of iron(III) polymaltose complex (Maltofer(®)) versus ferrous sulfate in iron-deficient pregnant women using recommended doses. An exploratory, open-label, randomized, controlled, multicenter study was undertaken in 80 pregnant women with iron-deficiency anemia (hemoglobin ≤ 10.5 g/dL, serum ferritin ≤ 15 ng/mL and mean corpuscular volume ferrous sulfate (each 100 mg iron twice daily) for 90 days. The primary endpoint, change in hemoglobin from baseline to days 60 and 90, did not differ significantly between treatment groups. The mean (SD) change to day 90 was 2.16 (0.67) g/dL in the iron(III) polymaltose complex group and 1.93 (0.97) g/dL in the ferrous sulfate group (n.s). Mean serum ferritin at day 90 was 179 (38) ng/mL and 157 (34) ng/mL with iron(III) polymaltose complex and ferrous sulfate, respectively (p = 0.014). Adverse events were significantly less frequent in the iron(III) polymaltose group, occurring in 12/41 (29.3%) patients, than in the ferrous sulfate group (22/39 [56.4%]) (p = 0.015). Oral iron(III) polymaltose complex offers at least equivalent efficacy and a superior safety profile compared to ferrous sulfate for the treatment of iron-deficiency anemia during pregnancy.

  4. Obesity modulate serum hepcidin and treatment outcome of iron deficiency anemia in children: a case control study.

    Science.gov (United States)

    Sanad, Mohammed; Osman, Mohammed; Gharib, Amal

    2011-07-19

    Recently, hepcidin expression in adipose tissue has been described and shown to be increased in patients with severe obesity. We tried to assess the effect of obesity on hepcidin serum levels and treatment outcome of iron deficiency anemia in children. This was a case control study included 70 children with iron deficiency anemia "IDA" (35 obese and 35 non-obese) and 30 healthy non-obese children with comparable age and sex(control group). Parameters of iron status (Serum iron, ferritin, transferrin, total iron binding capacity and transferrin saturation) and serum hepcidin levels were assessed initially and after 3 months of oral iron therapy for IDA. Compared to the control group, serum hepcidin was significantly lower in non-obese children with IDA(p children with IDA (p children with IDA after 3 months of iron therapy (P children showed non-significant change in hepcidin level after iron therapy (p > 0.05). Although hepcidin showed significant positive correlations with Hb, serum iron and transferrin saturation in non-obese children with IDA, it showed significant negative correlations with Hb, serum iron and transferrin saturation in obese children with IDA (P iron therapy in childhood iron deficiency anemia.

  5. Desktop 3D printing of controlled release pharmaceutical bilayer tablets.

    Science.gov (United States)

    Khaled, Shaban A; Burley, Jonathan C; Alexander, Morgan R; Roberts, Clive J

    2014-01-30

    Three dimensional (3D) printing was used as a novel medicine formulation technique for production of viable tablets capable of satisfying regulatory tests and matching the release of standard commercial tablets. Hydroxypropyl methylcellulose (HPMC 2208) (Methocel™ K100M Premium) and poly(acrylic acid) (PAA) (Carbopol(®) 974P NF) were used as a hydrophilic matrix for a sustained release (SR) layer. Hypromellose(®) (HPMC 2910) was used as a binder while microcrystalline cellulose (MCC) (Pharmacel(®) 102) and sodium starch glycolate (SSG) (Primojel(®)) were used as disintegrants for an immediate release (IR) layer. Commercial guaifenesin bi-layer tablets (GBT) were used as a model drug (Mucinex(®)) for this study. There was a favourable comparison of release of the active guaifenesin from the printed hydrophilic matrix compared with the commercially available GBT. The printed formulations were also evaluated for physical and mechanical properties such as weight variation, friability, hardness and thickness as a comparison to the commercial tablet and were within acceptable range as defined by the international standards stated in the United States Pharmacopoeia (USP). All formulations (standard tablets and 3D printed tablets) showed Korsmeyer-Peppas n values between 0.27 and 0.44 which indicates Fickian diffusion drug release through a hydrated HPMC gel layer. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Factors controlling alkali salt deposition in recovery boilers. Release mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    McKeough, P.; Kurkela, M.; Kylloenen, H.; Tapola, E. [VTT Energy, Espoo (Finland). Process Technology Group

    1997-10-01

    The research was part of an ongoing cooperative research effort aimed at developing a model to describe the behaviour of inorganic compounds in kraft recovery boilers. During 1996 experimental investigations of sulphur release were continued. Experiments at elevated pressures and employing larger particle sizes were performed in order to gain information about mass transfer effects. The first experiments yielding data on the rates of the sulphur-release reactions were performed. This data will be used as the basis of a drop model for sulphur release being developed in cooperation with another research group. The other part of the work during 1996 explored the possibility of using chemical equilibrium calculations to predict the release of sodium, potassium and chlorine in the recovery furnace. The approach is essentially different from that employed in earlier studies in that the effects of fume formation are taken into account. So far, the predictions of the chemical equilibrium release model have, in no way, conflicted with field measurements. (orig.)

  7. FORMULATION AND EVALUATION OF DICLOFENAC CONTROLLED RELEASE TABLETS EMPLOYING OLIBANUM RESIN

    Directory of Open Access Journals (Sweden)

    K.P.R. Chowdary and G. Rami Reddy *

    2012-04-01

    Full Text Available The objective of the study is to evaluate Olibanum resin, a natural resin polymer as matrix polymer for controlled release tablets and to design matrix tablets of diclofenac for controlled release. Matrix tablets of diclofenac were formulated employing Olibanum resin in different proportions of drug and polymer and the tablets were evaluated for drug release kinetics and mechanism .Two diluents namely lactose (water soluble and DCP (water insoluble were included in the formulations to assess their influence on drug release characteristics of olibanum resin matrix tablets. Matrix tablets were found t¬o be non- disint-egrating in water, acidic (pH 1.2 and alkaline (pH 7.4 fluids and were considered suitable for oral controlled release. Diclofenac release from the matrix tablets formulated was slow and spread over 24 h and depended on the concentration (% of olibanum resin in the matrix tablets and nature/type of diluent. As the concentration of olibanum resin in the matrix tablets was increased, drug release was decreased. Release was relatively faster with water soluble diluent lactose when compared to water insoluble diluent DCP at all concentrations of olibanum resin. Drug release from the tablets followed first order kinetics and followed non - Fickian (anomalous diffusion release mechanism. Good linear relationships were observed between percent polymer and release rate in each case. The results of the study thus indicated olibanum resin could be used as rate controlling matrix in design of controlled release tablets. Both water soluble and water insoluble diluents can be included in the olibanum resin matrix tablets without affecting its rate controlling efficiency. Matrix tablets formulated employing olibanum resin(DF2 are considered suitable for controlled release of diclofenac over 24 h (i.e. once-a-day administration.

  8. Control-release microcapsule of famotidine loaded biomimetic synthesized mesoporous silica nanoparticles: Controlled release effect and enhanced stomach adhesion in vitro.

    Science.gov (United States)

    Li, Jing; Wang, Hongyu; Yang, Baixue; Xu, Lu; Zheng, Nan; Chen, Hongtao; Li, Sanming

    2016-01-01

    In the present work, control-release microcapsule of famotidine (FMT) loaded biomimetic synthesized mesoporous silica nanoparticles (B-MSNs) was developed, and controlled release effect and stomach adhesion of this formulation in vitro were mainly investigated. B-MSN was previously synthesized and it was amorphous mesoporous nanoparticles with helical channels. Cytotoxicity of B-MSN was studied using human breast cancer cells (MCF-7) and the result indicated that cytotoxicity of B-MSN can be neglected. After loading FMT into B-MSN, specific surface area, pore volume and pore diameter of B-MSN were obviously reduced. In vitro dissolution test showed that B-MSN had the ability to slow down FMT release for 15 min. In order to prolong controlled release effect and remained the advantage of B-MSN (improve drug stability due to its rigid silica framework), the combined application of control-release microcapsule (using cellulose and hydroxypropyl methylcellulose K15M as excipients) with B-MSN was designed. It was obvious that newly designed formulation significantly controlled FMT release with Fickian diffusion mechanism and showed enhanced stomach adhesion in vitro, which has significant value in widening the application of B-MSN in formulation design.

  9. The blend modification of EVA-150/starch and controlled-release of imazethapyr

    Institute of Scientific and Technical Information of China (English)

    TAI Li-min; ZHU Xiu-yun

    2008-01-01

    The EVA-150 and starch were extruded by extruding press and the bio-degra-dation composite material was prepared to use as the controlled-release matrix of imazethapyr. The compatibility and crystallinity of EVA-150/starch blending were analyzed by SEM and DSC, and the controlled-released performance of imazethapyr in the carriers was also investigated by UV analysis. The results show that EVA-150/starch composite matrix has the obvious controlled-released function and the release rates of imazethapyr all exceed 50% in the environment of pH4, pH7, or pH9 after nine days.

  10. The blend modification of EVA-150/starch and controlled-release of imazethapyr

    Institute of Scientific and Technical Information of China (English)

    TAI LI-min; ZHU Xiu-yun

    2008-01-01

    The EVA-150 and starch were extruded by extruding press and the bio-degradation composite material was prepared to use as the controlled-release matrix of imazethapyr.The compatibility and crystallinity of EVA-150/starch blending were analyzed by SEM and DSC,and the controlled-released performance of imazethapyr in the carriers was also investigated by UV analysis.The results show that EVA-150/starch composite matrix has the obvious controlled-released function and the release rates of imazethapyr all exceed 50% in the environment of pH4,pH7,or pH9 after nine days.

  11. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    Energy Technology Data Exchange (ETDEWEB)

    Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani [School of Applied Physics, Faculty Science and Technology, University Kebangsaan Malaysia 43600 UKM Bangi, Selangor (Malaysia); Chiu, Wee Siong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur (Malaysia)

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  12. One-pot size and shape controlled synthesis of DMSO capped iron oxide nanoparticles

    Indian Academy of Sciences (India)

    Debanjan Guin; Sunkara V Manorama; S Radha; A K Nigam

    2006-11-01

    We report here the capping of iron oxide nanoparticles with dimethyl sulfoxide (DMSO) to make chloroform soluble iron oxide nanoparticles. Size and shape of the capped iron oxide nanoparticles are well controlled by simply varying the reaction parameters. The synthesized nanocrystallites were characterized by thermal analysis (TG–DTA), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) for evaluating phase, structure and morphology. 1H NMR spectra of the synthesized samples confirm DMSO, and the capping of DMSO on the ferrite samples. Shift of the S=O stretching frequency in Fourier transformed infrared (FTIR) spectra indicates that the bonding between DMSO and ferrite is through an oxygen moiety. The magnetic measurements of all the synthesized samples were investigated with a SQUID magnetometer which shows that the magnetic properties are strongly dependent on the size as well as shape of the iron oxide.

  13. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.

    The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected ...... to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis....

  14. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.;

    to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis.......The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected...

  15. Fabrication and Evaluation of Multilayer Nanofiber-Hydrogel Meshes with a Controlled Release Property

    Directory of Open Access Journals (Sweden)

    Rigumula Wu

    2015-07-01

    Full Text Available Controlled release drug delivery systems enable the sustained release of bioactive molecules, and increase bioavailability over an extended length of time. Biocompatible and biodegradable materials such as polycaprolactone (PCL nanofibers and alginate hydrogel play a significant role in designing controlled release systems. Prolonged release of bioactive molecules is observed when these polymer materials are used as matrices independently. However, there has not been a report in the literature that shows how different molecules are released at various rates over time. The goal of this study is to demonstrate a novel drug delivery system that has a property of releasing designated drugs at various rates over a defined length of time. We fabricated multilayer nanofiber-hydrogel meshes using electrospun PCL nanofiber and alginate hydrogel, and evaluated their controlled release properties. The multilayer meshes are composed of sandwiched layers of alternating PCL nanofibers and alginate hydrogel. Adenosine triphosphate (ATP, encapsulated in the designated hydrogel layers, is used as a mock drug for the release study. The exposed top layer of the meshes demonstrates a dramatically higher burst release and shorter release time compared to the deeper layers. Such properties of the different layers within the meshes can be employed to achieve the release of multiple drugs at different rates over a specified length of time.

  16. Biodegradable hollow fibres for the controlled release of drugs

    NARCIS (Netherlands)

    Schakenraad, J.M.; Oosterbaan, J.A.; Nieuwenhuis, P.; Molenaar, I.; Olijslager, J.; Potman, W.; Eenink, M.J.D.; Feijen, Jan

    1988-01-01

    Biodegradable hollow fibres of poly-l-lactic acid (PLLA) filled with a suspension of the contraceptive hormone levonorgestrel in castor oil were implanted subcutaneously in rats to study the rate of drug release, rate of biodegradation and tissue reaction caused by the implant. The in vivo drug

  17. A Remote Controlled Valve in Liposomes for Triggered Liposomal Release

    NARCIS (Netherlands)

    Koçer, Armağan

    2007-01-01

    In order to reduce the toxicity and increase the efficacy of drugs, there is a need for smart drug delivery systems. Liposomes are one of the promising tools for this purpose. An ideal liposomal delivery system should be stable, long-circulating, accumulate at the target site and release its drug in

  18. Control of oxygen release from peroxides using polymers

    NARCIS (Netherlands)

    Steg, Hilde; Buizer, Arina T.; Woudstra, Willem; Veldhuizen, Albert G.; Bulstra, Sjoerd K.; Grijpma, Dirk W.; Kuijer, Roel

    An important limitation in cell therapy for the regeneration of tissue is the initial lack of oxygen. After implantation of large 3D cell-seeded structures, cells die rather than contribute to tissue regenerating. Here we've tested oxygen-releasing materials to improve cell survival and growth after

  19. Control of oxygen release from peroxides using polymers

    NARCIS (Netherlands)

    Steg, Hilde; Buizer, A.T.; Woudstra, W.; Veldhuizen, A.G.; Bulstra, S.K.; Grijpma, Dirk W.; Kuijer, R.

    2015-01-01

    An important limitation in cell therapy for the regeneration of tissue is the initial lack of oxygen. After implantation of large 3D cell-seeded structures, cells die rather than contribute to tissue regenerating. Here we’ve tested oxygen-releasing materials to improve cell survival and growth after

  20. Biodegradable hollow fibres for the controlled release of drugs

    NARCIS (Netherlands)

    Schakenraad, J.M.; Oosterbaan, J.A.; Nieuwenhuis, P.; Molenaar, I.; Olijslager, J.; Potman, W.; Eenink, M.J.D.; Feijen, J.

    1988-01-01

    Biodegradable hollow fibres of poly-l-lactic acid (PLLA) filled with a suspension of the contraceptive hormone levonorgestrel in castor oil were implanted subcutaneously in rats to study the rate of drug release, rate of biodegradation and tissue reaction caused by the implant. The in vivo drug rele

  1. Control of oxygen release from peroxides using polymers

    NARCIS (Netherlands)

    Steg, Hilde; Buizer, A.T.; Woudstra, W.; Veldhuizen, A.G.; Bulstra, S.K.; Grijpma, D.W.; Kuijer, R.

    2015-01-01

    An important limitation in cell therapy for the regeneration of tissue is the initial lack of oxygen. After implantation of large 3D cell-seeded structures, cells die rather than contribute to tissue regenerating. Here we’ve tested oxygen-releasing materials to improve cell survival and growth after

  2. Concerning Workload Control and Order Release : The Pre-Shop Pool Sequencing Decision

    NARCIS (Netherlands)

    Thürer, Matthias; Land, Martin J.; Stevenson, Mark; Fredendall, Lawrence D.; Godinho Filho, Moacir

    2015-01-01

    Every production planning concept that incorporates controlled order release will initially withhold jobs from the shop floor and create a pre-shop pool. Order release is a key component of the Workload Control concept that aims to maintain work-in-process within limits while ensuring due dates are

  3. Application of waterborne acrylic emulsions in coated controlled release fertilizer using reacted layer technology

    Institute of Scientific and Technical Information of China (English)

    Yazhen Shen; Cong Zhao; Jianmin Zhou; Changwen Du

    2015-01-01

    Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release pro-files of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate so-dium could not improve water resistance performance and glass transition temperature Tg of coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorpo-ration of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated con-trol ed release fertilizer, with the 30-day cumulative nutrient release reduced to 16%and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.

  4. Designer protein delivery: From natural to engineered affinity-controlled release systems.

    Science.gov (United States)

    Pakulska, Malgosia M; Miersch, Shane; Shoichet, Molly S

    2016-03-18

    Exploiting binding affinities between molecules is an established practice in many fields, including biochemical separations, diagnostics, and drug development; however, using these affinities to control biomolecule release is a more recent strategy. Affinity-controlled release takes advantage of the reversible nature of noncovalent interactions between a therapeutic protein and a binding partner to slow the diffusive release of the protein from a vehicle. This process, in contrast to degradation-controlled sustained-release formulations such as poly(lactic-co-glycolic acid) microspheres, is controlled through the strength of the binding interaction, the binding kinetics, and the concentration of binding partners. In the context of affinity-controlled release--and specifically the discovery or design of binding partners--we review advances in in vitro selection and directed evolution of proteins, peptides, and oligonucleotides (aptamers), aided by computational design.

  5. One-step synthesis of magnetic chitosan for controlled release of 5-hydroxytryptophan

    Science.gov (United States)

    Santos Menegucci, Jucély dos; Santos, Mac-Kedson Medeiros Salviano; Dias, Diego Juscelino Santos; Chaker, Juliano Alexandre; Sousa, Marcelo Henrique

    2015-04-01

    In this work, nanoparticles of chitosan embedded with 25% (w/w) of iron oxide magnetic nanoparticles (magnetite/maghemite) with narrow size-distribution and with a loading efficiency of about 80% for 5-hydroxytryptophan (5-HTP), which is a chemical precursor in the biosynthesis of important neurotransmitters as serotonin, were synthesized with an initial mass ratio of 5-HTP/magnetic chitosan=1.2, using homogeneous precipitation by urea decomposition, in an efficient one-step procedure. Characterization of morphology, structure and surface were performed by XRD, TEM, FTIR, TGA, magnetization and zeta potential measurements, while drug loading and drug releasing were investigated using UV-vis spectroscopy. Kinetic drug release experiments under different pH conditions revealed a pH-sensitivecontrolled-release system, ruled by polymer swelling and/or particle dissolution.

  6. Two-Component Signaling System VgrRS Directly Senses Extracytoplasmic and Intracellular Iron to Control Bacterial Adaptation under Iron Depleted Stress.

    Directory of Open Access Journals (Sweden)

    Li Wang

    2016-12-01

    Full Text Available Both iron starvation and excess are detrimental to cellular life, especially for animal and plant pathogens since they always live in iron-limited environments produced by host immune responses. However, how organisms sense and respond to iron is incompletely understood. Herein, we reveal that in the phytopathogenic bacterium Xanthomonas campestris pv. campestris, VgrS (also named ColS is a membrane-bound receptor histidine kinase that senses extracytoplasmic iron limitation in the periplasm, while its cognate response regulator, VgrR (ColR, detects intracellular iron excess. Under iron-depleted conditions, dissociation of Fe3+ from the periplasmic sensor region of VgrS activates the VgrS autophosphorylation and subsequent phosphotransfer to VgrR, an OmpR-family transcription factor that regulates bacterial responses to take up iron. VgrR-VgrS regulon and the consensus DNA binding motif of the transcription factor VgrR were dissected by comparative proteomic and ChIP-seq analyses, which revealed that in reacting to iron-depleted environments, VgrR directly or indirectly controls the expressions of hundreds of genes that are involved in various physiological cascades, especially those associated with iron-uptake. Among them, we demonstrated that the phosphorylated VgrR tightly represses the transcription of a special TonB-dependent receptor gene, tdvA. This regulation is a critical prerequisite for efficient iron uptake and bacterial virulence since activation of tdvA transcription is detrimental to these processes. When the intracellular iron accumulates, the VgrR-Fe2+ interaction dissociates not only the binding between VgrR and the tdvA promoter, but also the interaction between VgrR and VgrS. This relieves the repression in tdvA transcription to impede continuous iron uptake and avoids possible toxic effects of excessive iron accumulation. Our results revealed a signaling system that directly senses both extracytoplasmic and intracellular

  7. Patients with acute myeloid leukemia can be subclassified based on the constitutive cytokine release of the leukemic cells; the possible clinical relevance and the importance of cellular iron metabolism.

    Science.gov (United States)

    Brenner, Annette K; Tvedt, Tor Henrik Anderson; Nepstad, Ina; Rye, Kristin P; Hagen, Karen M; Reikvam, Håkon; Bruserud, Øystein

    2017-04-01

    Acute myeloid leukaemia (AML) is a heterogeneous malignancy; we studied how the constitutive cytokine release by the AML cells varies among patients. We investigated the constitutive release of 28 mediators during in vitro culture for 79 consecutive patients. Constitutive cytokine release profiles differed among patients, and hierarchical clustering identified three subsets with high, intermediate and low release, respectively. The high-release subset showed high levels of most mediators, usually monocytic differentiation as well as altered mRNA expression of proteins involved in intracellular iron homeostasis and molecular trafficking; this subset also included 4 out of 6 patients with inv(16). Spontaneous in vitro apoptosis did not differ among the subsets. For the high-release patients, cytokines were released both by CD34(+) and CD34(-) cells. The mRNA and released protein levels showed statistically significant correlations only for eleven of the cytokines. The overall survival after intensive anti-leukemic therapy was significantly higher for high-release compared with low-release patients. Pharmacological targeting of iron metabolism (iron chelation, transferrin receptor blocking) altered the cytokine release profile. Subclassification of AML patients based on the constitutive cytokine release may be clinically relevant and a part of a low-risk (i.e. chemosensitive) AML cell phenotype.

  8. Angiocrine Bmp2 signaling in murine liver controls normal iron homeostasis.

    Science.gov (United States)

    Koch, Philipp-Sebastian; Olsavszky, Victor; Ulbrich, Friederike; Sticht, Carsten; Demory, Alexandra; Leibing, Thomas; Henzler, Thomas; Meyer, Mathias; Zierow, Johanna; Schneider, Sven; Breitkopf-Heinlein, Katja; Gaitantzi, Haristi; Spencer-Dene, Bradley; Arnold, Bernd; Klapproth, Kay; Schledzewski, Kai; Goerdt, Sergij; Géraud, Cyrill

    2017-01-26

    Microvascular endothelial cells (ECs) display a high degree of phenotypic and functional heterogeneity among different organs. Organ-specific ECs control their tissue microenvironment by angiocrine factors in health and disease. Liver sinusoidal endothelial cells (LSECs) are uniquely differentiated to fulfill important organ-specific functions in development, under homeostatic conditions, and in regeneration and liver pathology. Recently, Bmp2 has been identified by us as an organ-specific angiokine derived from LSECs. To study angiocrine Bmp2 signaling in the liver, we conditionally deleted Bmp2 in LSECs using EC subtype-specific Stab2-Cre mice. Genetic inactivation of hepatic angiocrine Bmp2 signaling in Stab2-Cre;Bmp2(fl/fl) (Bmp2(LSECKO)) mice caused massive iron overload in the liver and increased serum iron levels and iron deposition in several organs similar to classic hereditary hemochromatosis. Iron overload was mediated by decreased hepatic expression of hepcidin, a key regulator of iron homeostasis. Thus, angiocrine Bmp2 signaling within the hepatic vascular niche represents a constitutive pathway indispensable for iron homeostasis in vivo that is nonredundant with Bmp6. Notably, we demonstrate that organ-specific angiocrine signaling is essential not only for the homeostasis of the respective organ but also for the homeostasis of the whole organism.

  9. Using iron fertilizer to control Cd accumulation in rice plants: A new promising technology

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Effects of two kinds of iron fertilizer, FeSO4 and EDTA·Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth and rice grain yield. Soil application of EDTA·Na2Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both rice genotypes in the treatment of soil application of EDTA·Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentra- tion in cereal crop foods in State standard. However, soil application of FeSO4 or foliar application of FeSO4 or EDTA·Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control. The results also showed iron fertilizers increased the concentra- tion of iron, copper and manganese element in rice grain and also affected zinc concentration in plants. It may be a new promising way to regulate Cd accumulation in rice grain in rice production through soil application of EDTA·Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils.

  10. Using iron fertilizer to control Cd accumulation in rice plants: a new promising technology.

    Science.gov (United States)

    Shao, GuoSheng; Chen, MingXue; Wang, DanYing; Xu, ChunMei; Mou, RenXiang; Cao, ZhaoYun; Zhang, XiuFu

    2008-03-01

    Effects of two kinds of iron fertilizer, FeSO4 and EDTA.Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth and rice grain yield. Soil application of EDTA.Na2Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both rice genotypes in the treatment of soil application of EDTA.Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentration in cereal crop foods in State standard. However, soil application of FeSO4 or foliar application of FeSO4 or EDTA.Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control. The results also showed iron fertilizers increased the concentration of iron, copper and manganese element in rice grain and also affected zinc concentration in plants. It may be a new promising way to regulate Cd accumulation in rice grain in rice production through soil application of EDTA.Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils.

  11. Using iron fertilizer to control Cd accumulation in rice plants: A new promising technology

    Institute of Scientific and Technical Information of China (English)

    SHAO GuoSheng; CHEN MingXue; WANG DanYing; XU ChunMei; MOU RenXiang; CAO ZhaoYun; ZHANG XiuFu

    2008-01-01

    Effects of two kinds of iron fertilizer, FeSO4 and EDTA·Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth and rice grain yield. Soil application of EDTA.Na=Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both rice genotypes in the treatment of soil application of EDTA·Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentration in cereal crop foods in State standard. However, soil application of FeSO4 or foliar application of FeSO4 or EDTA·Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control. The results also showed iron fertilizers increased the concentration of iron, copper and manganese element in rice grain and also affected zinc concentration in plants.It may be a new promising way to regulate Cd accumulation in rice grain in rice production through soil application of EDTA·Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils.

  12. Controlled drug release on amine functionalized spherical MCM-41

    Science.gov (United States)

    Szegedi, Agnes; Popova, Margarita; Goshev, Ivan; Klébert, Szilvia; Mihály, Judit

    2012-10-01

    MCM-41 silica with spherical morphology and small particle sizes (100 nm) was synthesized and modified by post-synthesis method with different amounts of 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, was carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N2 physisorption, elemental analysis, thermal analysis and FT-IR spectroscopy. A new method was developed for the quantitative determination of amino groups in surface modified mesoporous materials by the ninhydrin reaction. Good correlation was found between the amino content of the MCM-41 materials determined by the ninhydrin method and their ibuprofen adsorption capacity. Amino modification resulted in high degree of ibuprofen loading and slow release rate in comparison to the parent non-modified MCM-41.

  13. Gastrin release: Antrum microdialysis reveals a complex neural control

    DEFF Research Database (Denmark)

    Ericsson, P; Håkanson, R; Rehfeld, Jens F.;

    2010-01-01

    in serum regardless of the prandial state. The rats were conscious during microdialysis except when subjected to electrical vagal stimulation. Acid blockade (omeprazole treatment of freely fed rats for 4 days), or bilateral sectioning of the abdominal vagal trunks (fasted, 3 days post-op.), raised...... the gastrin concentration in blood as well as microdialysate. The high gastrin concentration following omeprazole treatment was not affected by vagotomy. Vagal excitation stimulated the G cells: electrical vagal stimulation and pylorus ligation (fasted rats) raised the gastrin concentration transiently...... microdialysate gastrin concentration in omeprazole-treated rats by 65%. We conclude that activated gastrin release, unlike basal gastrin release, is highly dependent on a neural input: 1) Vagal excitation has a transient stimulating effect on the G cells. The transient nature of the response suggests...

  14. Formation, release and control of dioxins in cement kilns.

    Science.gov (United States)

    Karstensen, Kåre Helge

    2008-01-01

    Co-processing of hazardous wastes in cement kilns have for decades been thought to cause increased emissions of PCDD/PCDFs--a perception that has been evaluated in this study. Hundreds of PCDD/PCDF measurements conducted by the cement industry and others in the last few years, on emissions and solid materials, as well as recent test burns with hazardous wastes in developing countries do not support this perception. Newer data has been compared with older literature data and shows in particular that many emission factors have to be reconsidered. Early emission factors for cement kilns co-processing hazardous waste, which are still used in inventories, are shown to be too high compared with actual measurements. Less than 10 years ago it was believed that the cement industry was the main contributor of PCDD/PCDFs to air; data collected in this study indicates however that the industry contributes with less than 1% of total emissions to air. The Stockholm Convention on POPs presently ratified by 144 parties, classifies cement kilns co-processing hazardous waste as a source category having the potential for comparatively high formation and release of PCDD/PCDFs. This classification is based on early investigations from the 1980s and 1990s where kilns co-processing hazardous waste had higher emissions compared to those that did not burn hazardous waste. However, the testing of these kilns was often done under worst case scenario conditions known to favour PCDD/PCDF formation. More than 2000 PCDD/PCDF cement kiln measurements have been evaluated in this study, representing most production technologies and waste feeding scenarios. They generally indicate that most modern cement kilns co-processing waste today can meet an emission level of 0.1ngI-TEQ/m(3), when well managed and operated. In these cases, proper and responsible use of waste including organic hazardous waste to replace parts of the fossil fuel does not seem to increase formation of PCDD/PCDFs. Modern preheater

  15. Sandwich Structure-like Meshes Fabricated via Electrospinning for Controllable Release of Zoledronic Acid

    Institute of Scientific and Technical Information of China (English)

    LU Jian; LIU Jian-guo; SONG Xiao-feng; CHEN Xue-si; WU Xiao-dong

    2011-01-01

    Novel sandwich structure-like nanofiber multilayered meshes were fabricated via electrospinning. The purpose of the present work was to control zoledronic acid release via the novel structure of sandwich structure-like meshes. The in vitro release experiments reveal that the drug release speed and initial burst release were controllable by adjusting the thicknesses of electrospun barrier mesh and drug-loaded mesh. Compared with those of other drug delivery systems, the main advantages of the sandwich structure-like fiber meshes are facile preparation conditions and the generality for hydrophobic and hydrophilic pharmaceuticals.

  16. Model-based computer-aided design for controlled release of pesticides

    DEFF Research Database (Denmark)

    Muro Sunè, Nuria; Gani, Rafiqul; Bell, G.;

    2005-01-01

    In the field of controlled release technology for pesticides or active ingredients (AI), models that can predict its delivery during application are important for purposes of design and marketing of the pesticide product. Appropriate models for the controlled release of pesticides, if available, ...... extended models have been developed and implemented into a computer-aided system. The total model consisting of the property models embedded into the release models are then employed to study the release of different combinations of AIs and polymer-based microcapsules....

  17. Iron-deficiency Anemia in Children with Febrile Seizure: A Case-Control Study

    Directory of Open Access Journals (Sweden)

    Fateme GHASEMI

    2014-04-01

    Full Text Available How to Cite This Article: Ghasemi F, Valizadeh F, Taee N. Iron-deficiency Anemia in Children with Febrile Seizure: A Case-Control Study. Iran J Child Neurol. 2014 Spring 8(2:38-44.ObjectiveConsidering the recurrence of febrile seizure and costs for families, many studies have attempted to identify its risk factors. Some recent studies have reported that anemia is more common in children with febrile convulsion, whereas others have reported that iron deficiency raises the seizure threshold. This study was done to compare iron-deficiency anemia in children with first FS with children having febrile illness alone and with healthy children.Materials & MethodsThis case-control study evaluated 300 children in three groups (first FS, febrile without convulsion, and healthy in Khoramabad Madani Hospital from September 2009 to September 2010. Body temperature on admission wasmeasured using the tympanic method. CBC diff, MCV, MCH, MCHC, serum iron, plasma ferritin and TIBC tests were performed for all participants. Data were analyzed by frequency, mean, standard deviation, ANOVA, and chi-square statistical tests. Odds ratios were estimated by logistic regression at a confidence level of 95%.Results Forty percent of the cases with FS had iron-deficiency anemia, compared to 26% of children with febrile illness without seizure and 12% of healthy children. The Odds ratio for iron-deficiency anemia in the patients with FS was 1.89 (95% CI, 1.04-5.17 compared to the febrile children without convulsion and 2.21 (95% CI, 1.54-3.46 compared to the healthy group. ConclusionChildren with FS are more likely to be iron-deficient than those with febrile illness alone and healthy children. Thus, iron-deficiency anemia could be a risk factor for FS.References1. Østergaard J R. Febrile Seizures. Acta Pædiatr 2009;98(5:771-3.2. Jones T, Jacobsen SJ. Childhood Febrile Seizures: Overview and Implications. Int J Med Sci. 2007; 4(2:110-4.3. Flury T, Aebi

  18. Iron homeostasis and oxidative stress in idiopathic pulmonary alveolar proteinosis: a case-control study

    Directory of Open Access Journals (Sweden)

    Roggli Victor L

    2008-01-01

    Full Text Available Abstract Background Lung injury caused by both inhaled dusts and infectious agents depends on increased availability of iron and metal-catalyzed oxidative stress. Because inhaled particles, such as silica, and certain infections can cause secondary pulmonary alveolar proteinosis (PAP, we tested the hypothesis that idiopathic PAP is associated with an altered iron homeostasis in the human lung. Methods Healthy volunteers (n = 20 and patients with idiopathic PAP (n = 20 underwent bronchoalveolar lavage and measurements were made of total protein, iron, tranferrin, transferrin receptor, lactoferrin, and ferritin. Histochemical staining for iron and ferritin was done in the cell pellets from control subjects and PAP patients, and in lung specimens of patients without cardiopulmonary disease and with PAP. Lavage concentrations of urate, glutathione, and ascorbate were also measured as indices of oxidative stress. Results Lavage concentrations of iron, transferrin, transferrin receptor, lactoferrin, and ferritin were significantly elevated in PAP patients relative to healthy volunteers. The cells of PAP patients had accumulated significant iron and ferritin, as well as considerable amounts of extracellular ferritin. Immunohistochemistry for ferritin in lung tissue revealed comparable amounts of this metal-storage protein in the lower respiratory tract of PAP patients both intracellularly and extracellularly. Lavage concentrations of ascorbate, glutathione, and urate were significantly lower in the lavage fluid of the PAP patients. Conclusion Iron homeostasis is altered in the lungs of patients with idiopathic PAP, as large amounts of catalytically-active iron and low molecular weight anti-oxidant depletion are present. These findings suggest a metal-catalyzed oxidative stress in the maintenance of this disease.

  19. Phenobarbital loaded microemulsion: development, kinetic release and quality control

    Directory of Open Access Journals (Sweden)

    Kayo Alves Figueiredo

    Full Text Available ABSTRACT This study aimed to obtain and characterize a microemulsion (ME containing phenobarbital (PB. The PB was incorporated in the proportion of 5% and 10% in a microemulsion system containing Labrasol(r, ethanol, isopropyl myristate and purified water. The physicochemical characterization was performed and the primary stability of the ME was evaluated. An analytical method was developed using spectrophotometry in UV = 242 nm. The kinetics of the in vitro release (Franz model of the ME and the emulsion (EM containing PB was evaluated. The incorporation of PB into ME at concentrations of 5 and 10% did not change pH and resistance to centrifugation. There was an increase in particle size, a decrease of conductivity and a change in the refractive index in relation to placebo ME. The ME remained stable in preliminary stability tests. The analytical method proved to be specific, linear, precise, accurate and robust. Regarding the kinetics of the in vitro release, ME obtained an in vitro release profile greater than the EM containing PB. Thus, the obtained ME has a potential for future transdermal application, being able to compose a drug delivery system for the treatment of epilepsy.

  20. Electrospun biodegradable nanofiber nonwovens for controlled release of proteins.

    Science.gov (United States)

    Maretschek, Sascha; Greiner, Andreas; Kissel, Thomas

    2008-04-21

    Electrospinning of emulsions composed of an organic poly(l-lactide) solution and an aqueous protein solution yielded protein containing nanofiber nonwovens (NNs) having a mean fiber diameter of approximately 350 nm. Cytochrome C was chosen as a hydrophilic model protein for encapsulation. SEM imaging and gas adsorption measurements were carried out to determine morphology and surface characteristics of the different nanofiber nonwovens. Transmission electron microscopy was used to clarify the localization of the protein within the NN. PLLA NNs exhibited a highly hydrophobic surface which led to a slow wetting. It was shown that the protein release was dependent on the surface tension of the release medium. Electrospinning of emulsions consisting of an organic solution of PLLA and an aqueous solution of hydrophilic polymers yielded fibers composed of a polymer blend. The resulting NNs exhibited a less hydrophobic surface, which gave us the opportunity to tailor the release profile via this technology. Furthermore it was investigated how the addition of different amounts of hydrophilic polymer to the aqueous phase influenced the morphology of the resulting NNs.

  1. A novel and alternative approach to controlled release drug delivery system based on solid dispersion technique

    Directory of Open Access Journals (Sweden)

    Tapan Kumar Giri

    2012-12-01

    Full Text Available The solid dispersion method was originally used to improve the dissolution properties and the bioavailability of poorly water soluble drugs by dispersing them into water soluble carriers. In addition to the above, dissolution retardation through solid dispersion technique using water insoluble and water swellable polymer for the development of controlled release dosage forms has become a field of interest in recent years. Development of controlled release solid dispersion has a great advantage for bypassing the risk of a burst release of drug; since the structure of the solid dispersion is monolithic where drug molecules homogeneously disperse. Despite the remarkable potential and extensive research being conducted on controlled release solid dispersion system, commercialization and large scale production are limited. The author expects that recent technological advances may overcome the existing limitations and facilitate the commercial utilization of the techniques for manufacture of controlled release solid dispersions. This article begins with an overview of the different carriers being used for the preparation of controlled release solid dispersion and also different techniques being used for the purpose. Kinetics of drug release from these controlled release solid dispersions and the relevant mathematical modeling have also been reviewed in this manuscript.

  2. Controlled release of folic acid through liquid-crystalline folate nanoparticles.

    Science.gov (United States)

    Misra, Rahul; Katyal, Henna; Mohanty, Sanat

    2014-11-01

    The present study explores folate nanoparticles as nano-carriers for controlled drug delivery. Cross-linked nanoparticles of liquid crystalline folates are composed of ordered stacks. This paper shows that the folate nanoparticles can be made with less than 5% loss in folate ions. In addition, this study shows that folate nanoparticles can disintegrate in a controlled fashion resulting in controlled release of the folate ions. Release can be controlled by the size of nanoparticles, the extent of cross-linking and the choice of cross-linking cation. The effect of different factors like agitation, pH, and temperature on folate release was also studied. Studies were also carried out to show the effect of release medium and role of ions in the release medium on disruption of folate assembly.

  3. Halloysite Nanotube Composited Thermo-responsive Hydrogel System for Controlled-release

    Institute of Scientific and Technical Information of China (English)

    林茜; 巨晓洁; 谢锐; 江明月; 魏竭; 褚良银

    2013-01-01

    Halloysite nanotube-composited thermo-responsive hydrogel system has been successfully developed for controlled drug release by copolymerization of N-isopropylacrylamide (NIPAM) with silane-modified halloysite nanotubes (HNT) through thermally initiated free-radical polymerization. With methylene blue as a model drug, thermo-responsive drug release results demonstrate that the drug release from the nanotubes in the composited hy-drogel can be well controlled by manipulating the environmental temperature. When the hydrogel network is swol-len at temperature below the lower critical solution temperature (LCST), drug releases steadily from lumens of the embedded nanotubes, whereas the drug release stops when hydrogel shrinks at temperature above the LCST. The release of model drug from the HNT-composited hydrogel matches well with its thermo-responsive volume phase transition, and shows characteristics of well controlled release. The design strategy and release results of the pro-posed novel HNT-composited thermo-responsive hydrogel system provide valuable guidance for designing respon-sive nanocomposites for controlled-release of active agents.

  4. Preparation and characterization of controlled release matrices based on novel seaweed interpolyelectrolyte complexes.

    Science.gov (United States)

    Prado, Héctor J; Matulewicz, María C; Bonelli, Pablo R; Cukierman, Ana L

    2012-06-15

    Novel interpolyelectrolyte complexes (IPECs) between naturally sulfated polysaccharides of the seaweed Polysiphonia nigrescens (PN) and cationized agaroses (CAG) and Eudragit E (EE) were prepared using an organic solvent free process, characterized, and explored for controlled drug release. Tablets containing model drug ibuprofen and IPECs were prepared by direct compression. Drug release in acid medium was low owing to the low solubility of ibuprofen in that condition and to the matrix action. Zero order drug release was determined in the buffer stage (pH=6.8), with Fickian diffusion predominating over relaxation during the initial phases. Relaxation appears to increase along the release process and even overcomes diffusion for some systems. Drug release profiles could be controlled by varying the content of IPECs in the tablets. Also, the change in molecular weight and the degree of substitution of the components allowed altering the release profiles.

  5. Controlled Release of Salicylic Acid from Biodegradable Cross-Linked Polyesters.

    Science.gov (United States)

    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.

  6. Controlled growth factor release from synthetic extracellular matrices

    Science.gov (United States)

    Lee, Kuen Yong; Peters, Martin C.; Anderson, Kenneth W.; Mooney, David J.

    2000-12-01

    Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

  7. Coordinated coupling control of tethered space robot using releasing characteristics of space tether

    Science.gov (United States)

    Huang, Panfeng; Zhang, Fan; Xu, Xiudong; Meng, Zhongjie; Liu, Zhengxiong; Hu, Yongxin

    2016-04-01

    Tethered space robot (TSR) is a new concept of space robot, which is released from the platform satellite, and retrieved via connected tether after space debris capture. In this paper, we propose a new coordinate control scheme for optimal trajectory and attitude tracking, and use releasing motor torque to instead the tension force, since it is difficult to track in practical. Firstly, the 6-DOF dynamics model of TSR is derived, in which the dynamics of tether releasing system is taken into account. Then, we propose and design the coordinated coupled controller, which is composed of a 6-DOF sliding mode controller and a PD controller tether's releasing. Thrust is treated as control input of the 6-DOF sliding mode controller to control the in-plane and out-of-plane angle of the tether and attitude angles of the TSR. The torque of releasing motor is used as input of PD controller, which controls the length rate of space tether. After the verification of the control scheme, finally, the simulation experiment is presented in order to validate the effectiveness of this control method. The results show that TSR can track the optimal approaching trajectory accurately. Simultaneously, the attitude angles can be changed to the desired attitude angles in control period, and the terminal accuracy is ±0.3°.

  8. Controlled electropolymerisation of a carbazole-functionalised iron porphyrin electrocatalyst for CO2 reduction

    DEFF Research Database (Denmark)

    Hu, Xinming; Salmi, Zakaria; Lillethorup, Mie;

    2016-01-01

    Using a one-step electropolymerisation procedure, CO2 absorbing microporous carbazole-functionalised films of iron porphyrins are prepared in a controlled manner. The electrocatalytic reduction of CO2 for these films is investigated to elucidate their efficiency and the origin of their ultimate...

  9. Sustained and controlled release of lipophilic drugs from a self-assembling amphiphilic peptide hydrogel

    DEFF Research Database (Denmark)

    Briuglia, Maria-Lucia; Urquhart, Andrew; Lamprou, Dimitrios A.

    2014-01-01

    . In this work, we have investigated the diffusion properties of Pindolol, Quinine and Timolol maleate from RADA16 in PBS and in BSS-PLUS at 37°C. A sustained, controlled, reproducible and efficient drug release has been detected for all the systems, which allows to understand the dependence of release kinetics...

  10. Releasable Kinetic Energy-Based Inertial Control of a DFIG Wind Power Plant

    DEFF Research Database (Denmark)

    Lee, Jinsik; Muljadi, Eduard; Sørensen, Poul Ejnar

    2016-01-01

    Wind turbine generators (WTGs) in a wind power plant (WPP) contain different levels of releasable kinetic energy (KE) because of the wake effects. This paper proposes a releasable KE-based inertial control scheme for a doubly fed induction generator (DFIG) WPP that differentiates the contributions...

  11. Using polymer-coated controlled-release fertilizers in the nursery and after outplanting

    Science.gov (United States)

    Thomas D. Landis; R. Kasten Dumroese

    2009-01-01

    Controlled-release fertilizers (CRF) are the newest and most technically advanced way of supplying mineral nutrients to nursery crops. Compared to conventional fertilizers, their gradual pattern of nutrient release better meets plant needs, minimizes leaching, and therefore improves fertilizer use efficiency. In our review of the literature, we found many terms used...

  12. Releases of natural enemies in Hawaii since 1980 for classical biological control of weeds

    Science.gov (United States)

    P. Conant; J. N. Garcia; M. T. Johnson; W. T. Nagamine; C. K. Hirayama; G. P. Markin; R. L. Hill

    2013-01-01

    A comprehensive review of biological control of weeds in Hawaii was last published in 1992, covering 74 natural enemy species released from 1902 through 1980. The present review summarizes releases of 21 natural enemies targeting seven invasive weeds from 1981 to 2010. These projects were carried out by Hawaii Department of Agriculture (HDOA), USDA Forest Service (USFS...

  13. Computer-aided and predictive models for design of controlled release of pesticides

    DEFF Research Database (Denmark)

    Suné, Nuria Muro; Gani, Rafiqul

    2004-01-01

    In the field of pesticide controlled release technology, a computer based model that can predict the delivery of the Active Ingredient (AI) from fabricated units is important for purposes of product design and marketing. A model for the release of an M from a microcapsule device is presented...

  14. Oxidation Potential, Not Crystal Structure, Controls the Oxidation State of Iron in Perovskite

    Science.gov (United States)

    Panero, W. R.; Pigott, J. S.; Watson, H. C.; Scharenberg, M.; Green, H. W.; McComb, D. W.; Williams, R. E.

    2013-12-01

    The mantle's oxidation state has broad implications on the state and evolution of the earth's interior. The relatively high oxidation potential of the upper mantle is such that iron is predominantly Fe2+ with small amounts of Fe3+ . Fe3+ is more stable than Fe2+ in the dominant lower mantle mineral, perovskite, despite the fact that the effect of pressure is to reduce the oxidizing potential of a system. It is therefore suggested that iron undergoes a disproportionation reaction of 3Fe2+ =2Fe3+ +Fe0 , controlled by the crystallography instead of oxidation potential. We crystallized synthetic enstatite glass with 5% Al2O3, 14% FeO, and 3% Fe2O3 in the laser-heated diamond anvil cell at 25-63 GPa and 1700-2800 K. We find that for temperatures nm iron precipitates on grain boundaries. The precipitates have small amounts of dissolved oxygen, but are Mg- and Al- free. We interpret that the stishovite is forming due to the oxidation of the ferric iron to ferrous iron according to (Mg2+,Al3+)(Fe3+,Si4+)O3 +SiO2 + Fe0 while the lower-temperature samples crystallizing as approximately (Mg2+ Fe2+ Al3+ )(Fe3+ Al3+ Si4+ )O3. We observe 2.8(2) Å3 volume expansion of the perovskite and a 28(2) GPa decrease in compressibility of the perovskite relative to the perovskite forming at lower temperature, consistent with the proposed compositions of the perovskites. As the increased temperature increases the oxidation potential of the system, we suggest that the oxidation state of iron in perovskite is dependent on oxidation potential as opposed to perovskite's crystal structure. Transmission Electron Microscopy (TEM) coupled with Electron Energy Loss Spectroscopy (EELS) show iron precipitation on grain boundaries supporting the conclusion. We present a discussion of the results and implications for core formation and lower mantle dynamics.

  15. The feasibility study of autotrophic denitrification with iron sludge produced for sulfide control.

    Science.gov (United States)

    Wei, Yangyang; Dai, Ji; Mackey, Hamish R; Chen, Guang-Hao

    2017-10-01

    Ferric iron is widely dosed in wastewater treatment plants dealing with sulfide for septicity control, which generates a great amount of iron-rich chemical sludge that is challenging and costly to dispose. This study investigates the feasibility of using this iron sludge as the electron donor for autotrophic denitrification, not only realizing high nitrogen removal efficiency without additional carbon source requirement, but also partially mitigating iron-rich chemical sludge disposal and reduce sludge production by enriching low-yield autotrophic denitrifiers in the system. Both batch tests and performance monitoring of a lab-scale up-flow anaerobic sludge blanket reactor with a more than 300 days of operation were conducted. All the results confirmed the feasibility of using iron sludge as electron donor for autotrophic denitrification. The nitrate reduction rate with iron sludge was highly influenced by the type of ferrous electron donor and the electron donor/acceptor ratio. Ferrous hydroxide had significantly higher nitrate reduction rate than ferrous sulfide at the same electron donor/acceptor ratio. The nitrate reduction rate also accelerated with the increase of the electron donor/acceptor ratio. However, if the total surface area of the iron sludge is considered for comparison, it was shown that ferrous hydroxide and ferrous sulfide provided similar nitrate reduction rates of around 0.02 mmol N/m(2)/d in this study, indicating total surface area would be the key parameter for denitrification efficiency for the solid phase electron donor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. On-line iron loss resistance identification by a state observer for rotor-flux-oriented control of induction motor

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Pablo M. de la; Bossio, Guillermo R.; Garcia, Guillermo O. [Grupo de Electronica Aplicada (GEA), Facultad de Ingenieria, UNRC, Ruta Nacional 36 Km. 601, X5804BYA, Rio Cuarto (Argentina); Solsona, Jorge A. [Instituto de Investigaciones en Ingenieria Electrica ' ' Alfredo Desages' ' , Departamento de Ingenieria Electrica y de Computadoras, UNS, Av. Alem 1253 (8000) Bahia Blanca (Argentina)

    2008-10-15

    A rotor flux state observer considering iron loss, for an Induction Motor (IM), is proposed. The aim of this proposal is to avoid detuning caused by the IM iron loss on a field-oriented control (FOC). An adaptive scheme for the K{sub Fe}, a parameter that represents the IM iron loss, is also proposed. The main objective of this scheme is to improve the dynamic response of control by compensating the variations of iron losses due to possible variations in the stator core characteristics. Simulation results demonstrated that the observer and the adaptive scheme showed a good performance fulfilling then the objectives. (author)

  17. Magma redox and structural controls on iron isotope variations in Earth's mantle and crust

    Science.gov (United States)

    Dauphas, N.; Roskosz, M.; Alp, E. E.; Neuville, D. R.; Hu, M. Y.; Sio, C. K.; Tissot, F. L. H.; Zhao, J.; Tissandier, L.; Médard, E.; Cordier, C.

    2014-07-01

    The heavy iron isotopic composition of Earth's crust relative to chondrites has been explained by vaporization during the Moon-forming impact, equilibrium partitioning between metal and silicate at core-mantle-boundary conditions, or partial melting and magma differentiation. The latter view is supported by the observed difference in the iron isotopic compositions of MORBS and peridotites. However, the precise controls on iron isotope variations in igneous rocks remain unknown. Here, we show that equilibrium iron isotope fractionation is mainly controlled by redox (Fe3+/Fetot ratio) and structural (e.g., polymerization) conditions in magmas. We measured, for the first time, the mean force constants of iron bonds in silicate glasses by synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS, also known as Nuclear Resonance Vibrational Spectroscopy - NRVS, or Nuclear Inelastic Scattering - NIS). The same samples were studied by conventional Mössbauer and X-ray Absorption Near Edge Structure (XANES) spectroscopy. The NRIXS results reveal a +0.2 to +0.4‰ equilibrium fractionation on 56Fe/54Fe ratio between Fe2+ and Fe3+ end-members in basalt, andesite, and dacite glasses at magmatic temperatures. These first measurements can already explain ∼1/3 of the iron isotopic shift measured in MORBs relative to their source. Further work will be required to investigate how pressure, temperature, and structural differences between melts and glasses affect equilibrium fractionation factors. In addition, large fractionation is also found between rhyolitic glass and commonly occurring oxide and silicate minerals. This fractionation reflects mainly changes in the coordination environment of Fe2+ in rhyolites relative to less silicic magmas and mantle minerals, as also seen by XANES. We provide a new calibration of XANES features vs. Fe3+/Fetot ratio determinations by Mössbauer to estimate Fe3+/Fetot ratio in situ in glasses of basaltic, andesitic, dacitic, and rhyolitic

  18. Size-Controlled Pd Nanoparticle Catalysts Prepared by Galvanic Displacement into a Porous Si-Iron Oxide Nanoparticle Host.

    Science.gov (United States)

    Kim, Taeho; Fu, Xin; Warther, David; Sailor, Michael J

    2017-02-21

    Porous silicon nanoparticles containing both Pd and iron oxide nanoparticles are prepared and studied as magnetically recoverable catalysts for organic reductions. The Pd nanoparticles are generated in situ by electroless deposition of Pd(NH3)4(2+), where the porous Si skeleton acts as both a template and as a reducing agent and the released ammonia ligands raise the local pH to exert control over the size of the Pd nanoparticles. The nanocomposites are characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, nitrogen adsorption, X-ray diffraction, superconducting quantum interference device magnetization, and dynamic light scattering. The nanocomposite consists of a porous Si nanoparticle (150 nm mean diameter) containing ∼20 nm pores, uniformly decorated with a high loading of surfactant-free Pd nanoparticles (12 nm mean diameter) and superparamagnetic γ-Fe2O3 nanoparticles (∼7 nm mean diameter). The reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride is catalyzed by the nanocomposite, which is stable through the course of the reaction. Catalytic reduction of the organic dyes methylene blue and rhodamine B is also demonstrated. The conversion efficiency and catalytic activity are found to be superior to a commercial Pd/C catalyst compared under comparable reaction conditions. The composite catalyst can be recovered from the reaction mixture by applying an external magnetic field due to the existence of the superparamagnetic iron oxide nanoparticles in the construct. The recovered particles retain their catalytic activity.

  19. Controlled release of insect sex pheromones from paraffin wax and emulsions.

    Science.gov (United States)

    Atterholt, C A; Delwiche, M J; Rice, R E; Krochta, J M

    1999-02-22

    Paraffin wax and aqueous paraffin emulsions can be used as controlled release carriers for insect sex pheromones for mating disruption of orchard pests. Paraffin can be applied at ambient temperature as an aqueous emulsion, adheres to tree bark or foliage, releases pheromone for an extended period of time, and will slowly erode from bark and biodegrade in soil. Pheromone emulsions can be applied with simple spray equipment. Pheromone release-rates from paraffin were measured in laboratory flow-cell experiments. Pheromone was trapped from an air stream with an adsorbent, eluted periodically, and quantified by gas chromatography. Pheromone release from paraffin was partition-controlled, providing a constant (zero-order) release rate. A typical paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E acted as volatility suppressants. A constant release of oriental fruit moth pheromone from paraffin emulsions was observed in the laboratory for more than 100 days at 27 degreesC, with release-rates ranging from 0.4 to 2 mg/day, depending on the concentration and surface area of the dried emulsion. The use of paraffin emulsions is a viable method for direct application of insect pheromones for mating disruption. Sprayable formulations can be designed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degreesC, zero-order release was observed. At 38 degreesC and higher, pheromone oxidation occurred. A partition-controlled release mechanism was supported by a zero-order pheromone release-rate, low air/wax partition coefficients, and pheromone solubility in paraffin.

  20. Association between iron status, iron deficiency anaemia, and severe early childhood caries: a case–control study

    Directory of Open Access Journals (Sweden)

    Schroth Robert J

    2013-02-01

    Full Text Available Abstract Background Severe tooth decay is known to affect the health and well-being of young children. However, little is known about the influence of Severe Early Childhood Caries (S-ECC on childhood nutritional status. The purpose of this study was to contrast ferritin and haemoglobin levels between preschoolers with S-ECC and caries-free controls. Methods Children were recruited as part of a larger case–control study examining differences in nutritional status between those with and without S-ECC. Preschoolers with S-ECC were recruited on the day of their dental surgery, while caries-free controls were recruited from the community. Parents completed a questionnaire and the child underwent venipuncture. The study was approved by the University’s Health Research Ethics Board. Statistics included descriptive, bivariate and logistic regression analyses. A p value ≤ .05 was significant. A total of 266 children were recruited; 144 with S-ECC and 122 caries-free. Results The mean age was 40.8 ± 14.1 months. The mean ferritin concentration for all children was 29.6 ± 17.9 μg/L while the mean haemoglobin level was 115.1 ± 10.1 g/L. Children with S-ECC were significantly more likely to have low ferritin (p=.033 and low haemoglobin levels (p>.001. Logistic regression analyses revealed that children with S-ECC were nearly twice as likely to have low ferritin levels and were over six times more likely to have iron deficiency anaemia than caries-free controls. Conclusions Children with S-ECC appear to be at significantly greater odds of having low ferritin status compared with caries-free children and also appear to have significantly lower haemoglobin levels than the caries-free control group. Children with S-ECC also appear to be at significantly greater odds for iron deficiency anaemia than cavity-free children.

  1. Expected shortage based pre-release strategy for reservoir flood control

    Science.gov (United States)

    Chou, Frederick N.-F.; Wu, Chia-Wen

    2013-08-01

    In Taiwan, an increase in the frequency of severe flooding over the past decade has prompted demand for improved reservoir operation to control flood-related damage. Flood protection of reservoir can be enhanced by pre-releasing its storage to more adequately accommodate an impending flood. A procedure is proposed in this paper to evaluate the impact of pre-releases of flood control operation on water supply. A basic criterion used is that the pre-release of reservoir storage should not cause intolerable increment of water shortage risk. The shortage risks for different pre-release scenarios are simulated according to the uncertainties of storm rainfall and post-flood ordinary inflow till the end of next dry season. Two operational objectives are provided to help determining the target pre-released level. One of which identifies the minimum allowable pre-released threshold. The other seeks the pre-released level which maximizes the probability that the reservoir release during flood is below the non-damaging discharge and the end-of-operation storage target can still be achieved. This paper evaluated the operations of Tsengwen Reservoir of southern Taiwan during four typhoons from 2007 to 2012 to illustrate the significant contribution of pre-releases in reducing downstream flood potential.

  2. SOLID POLYMERIC MATRIX BASED ON CHITOSAN AND XANTHAN FOR CONTROLLED RELEASE OF FERTILIZERS

    Directory of Open Access Journals (Sweden)

    Mariana A. Melaj

    2012-03-01

    Full Text Available The main purpose of this work was to optimize the preparation conditions of solid polymeric matrix based on Chitosan and Xanthan, to be used in the controlled release of fertilizers. KNO3 was chosen as model agrochemical to be released. Both individual polymers and the Xanthan:Chitosan complex are biocompatible, leaving a residue on the soil which is non-toxic. The influence of different variables on the release pattern was studied: the type of polymer, the pressed conditions of the tablets and the presence of a drug-free polymeric coating. The polymer that presented a more promising release profile was Xanthan. The compression pressure applied to prepare the tablets was a more relevant variable than the compression time, in its effect on the kinetics of release. It was determined that the coating of the polymer matrix with crosslinked chitosan-glutaraldehyde allows getting a larger release time.

  3. Munc13 controls the location and efficiency of dense-core vesicle release in neurons.

    Science.gov (United States)

    van de Bospoort, Rhea; Farina, Margherita; Schmitz, Sabine K; de Jong, Arthur; de Wit, Heidi; Verhage, Matthijs; Toonen, Ruud F

    2012-12-10

    Neuronal dense-core vesicles (DCVs) contain diverse cargo crucial for brain development and function, but the mechanisms that control their release are largely unknown. We quantified activity-dependent DCV release in hippocampal neurons at single vesicle resolution. DCVs fused preferentially at synaptic terminals. DCVs also fused at extrasynaptic sites but only after prolonged stimulation. In munc13-1/2-null mutant neurons, synaptic DCV release was reduced but not abolished, and synaptic preference was lost. The remaining fusion required prolonged stimulation, similar to extrasynaptic fusion in wild-type neurons. Conversely, Munc13-1 overexpression (M13OE) promoted extrasynaptic DCV release, also without prolonged stimulation. Thus, Munc13-1/2 facilitate DCV fusion but, unlike for synaptic vesicles, are not essential for DCV release, and M13OE is sufficient to produce efficient DCV release extrasynaptically.

  4. Composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose for drug controlled release.

    Science.gov (United States)

    Pavaloiu, Ramona-Daniela; Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Dobre, Tanase

    2014-07-01

    Mono and multilayer composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose (PVA/chitosan/BC) have been prepared to achieve controlled release of ibuprofen sodium salt (IbuNa) as model drug. The composite films have been characterized by Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Surface morphology was investigated by scanning electron microscopy (SEM). Equilibrium swelling was measured in water at two different pH values and in vitro release of IbuNa in pH 1.2 and pH 7.4 media was studied. The release experiments revealed that drug release is pH sensitive. The release kinetics of IbuNa could be described by the Fickian model of diffusion with a good agreement. The IbuNa release rate was decreasing for all the films as the BC concentration was increased in the films composition, the decrease being higher for the multilayer films.

  5. Design and in vitro evaluation of controlled release alginate beads of diltiazem hydrochloride

    Institute of Scientific and Technical Information of China (English)

    D.Nagasamy Venkatesh; A.Kalaivani; Kritika D.Kalro; Lalitha Chintha; James Tharani; M.K. Samanta; B.Suresh

    2009-01-01

    Objective:Oral slow and sustained release drug delivery system can release their drug content with a controlled manner,producing a desirable blood serum level,reduction in drug toxicity and improving the patient compli-ance by prolonging dosing intervals.The major drawback of orally administered drug like diltiazem as a calcium channel blocker for the treatment of angina pectoris,arrhythmia and hypertension.Its has higher aqueous solu-bility and shorter elimination half-life.Methods:To overcome these drawbacks associated with diltiazem,an attempt has been made to develop a sustained release dosage form of diltiazem embedded alginate microbeads by ionotropic gelation technique employing various concentrations of polymer and keeping the drug concentra-tion constant.Results:The beads were characterized for its particle size,drug content and in vitro release stud-ies.The results revealed that the surface adhering drug was found to release immediately and a steady state of release was obtained up to 12 h from all the batches.The results indicated there was an inverse relationship be-tween the concentration of alginate and drug release.The drug release was found to follow non-fickian diffusion obeying first order kinetics.Conclusion:The developed alginate microbeads offered a sustained release of dilti-azem.Hence,the formulated microbeads were found to be potential,cost effective,possess satisfactory in vitro release studies.

  6. Immobilization and controlled release of drug using plasma polymerized thin film

    Energy Technology Data Exchange (ETDEWEB)

    Myung, Sung-Woon [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of); Jung, Sang-Chul [Department of Environmental Engineering, Sunchon National University, Sunchon 540-742 (Korea, Republic of); Kim, Byung-Hoon, E-mail: kim5055@chosun.ac.kr [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of)

    2015-06-01

    In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release.

  7. Design of cationic microspheres based on aminated gelatin for controlled release of peptide and protein drugs.

    Science.gov (United States)

    Morimoto, Kazuhiro; Chono, Sumio; Kosai, Tadashi; Seki, Toshinobu; Tabata, Yasuhiko

    2008-02-01

    Two different types of cationized microspheres based on a native cationic gelatin (NGMS) and aminated gelatin with ethylendiamine (CGMS) were investigated for the controlled release of three model acidic peptide/protein drugs with different molecular weights (MWs) and isoelectric points (IEPs). Recombinant human (rh)-insulin (MW: 5.8 kDa, IEP: 5.3), bovine milk lactoalbumin, BMLA (MW: 14 kDa, IEP: 4.3), and bovine serum albumin (BSA MW: 67 kDa, IEP: 4.9) were used as model acidic peptide/protein drugs. The in vitro release profiles of these acidic peptide/protein drugs from NGMS and CGMS were compared and different periods of cross-linking were obtained. The slower release of these acidic peptide/protein drugs from CGMS compared with those from NGMS with cross-linking for 48 hr. was caused by the suppression of burst release during the initial phase. The degree of suppression of burst release of the three peptide/protein drugs during the initial phase by CGMS was in the following order: (rh)-insulin > BMLA > BSA. The release of insulin with a lower molecular weight from CGMS was particularly suppressed compared with the other two drugs with higher molecular weights in the initial phase. The control of the release rate of acidic peptide/protein drugs from gelatin microsphere can be achieved by amination of gelatin. Therefore, CGMS is useful for the controlled release of acidic peptide/ protein drugs.

  8. Controlled-release fertilizer composition substantially coated with an impermeable layer

    Energy Technology Data Exchange (ETDEWEB)

    Ankeny, Mark

    2016-03-29

    A controlled-release fertilizer composition is provided that is substantially coated with an impermeable layer. The fertilizer composition may further include one or more hollow sections to allow for root penetration and efficient delivery of nutrients.

  9. Self-assembled nanoparticles of glycol chitosan – Ergocalciferol succinate conjugate, for controlled release

    DEFF Research Database (Denmark)

    Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

    2012-01-01

    Glycol chitosan was linked to vitamin D2 hemisuccinate (ergocalciferol hemisuccinate) for controlled release through water-soluble carbodiimide activation. The resulting conjugate formed self-assembled nanoparticles in aqueous solution with particle size of 279 nm and ergocalciferol hemisuccinate...

  10. Sedimentary particulate iron: the missing micronutrients ?

    Science.gov (United States)

    Beghoura, Houda; Gorgues, Thomas; Aumont, Olivier; Planquette, Hélène

    2017-04-01

    Iron is known to regulate the marine primary production and to impact the structure of ecosystems. Indeed, iron is the limiting nutrient for the phytoplankton growth over about 30% of the global ocean. However, the nature of the external sources of iron to the ocean and their quantification remain uncertain. Among these external sources, the sediment sources have been recently shown to be underestimated. Besides, since the operationally defined dissolved iron (which is the sum of truly dissolved and colloidal iron) was traditionally assumed to be the only form available to phytoplankton and bacteria, most studies have focused on the supply of dissolved iron to the ocean, the role of the particulate fraction of iron being largely ignored. This traditional view has been recently challenged, noticeably, by observational evidences. Indeed, in situ observations have shown that large amounts of particulate iron are being resuspended from continental margins to the open ocean thanks to fine grained particles' transport over long distances. A fraction of this particulate iron may dissolve and thereby fuel the phytoplankton growth. The magnitude of the sedimentary sources of particulate iron and the releasing processes affecting this iron phase are not yet well constrained or quantified. As a consequence, the role of sedimentary particulate iron in the biogeochemical cycles is still unclear despite its potentially major widespread importance. Here, we propose a modeling exercise to assess the first order impacts of this newly considered particulate sedimentary iron on global ocean biogeochemistry. We designed global experiments with a coupled dynamical-biogeochemical model (NEMO-PISCES). First, a control simulation that includes only a sediment source of iron in the dissolved phase has been run. Then, this control simulation is being compared with simulations, in which we include a sediment source of iron in both phases (dissolved as well as particulate). Those latter

  11. PREPARATION AND EVALUATION OF HPMC-ALGINATE MUCOADHESIVE MICROCAPSULES OF DICLOFENAC FOR CONTROLLED RELEASE

    Directory of Open Access Journals (Sweden)

    K.P.R. Chowdary

    2011-11-01

    Full Text Available A new, novel promising technology for obtaining controlled release and enhancing the bioavailability is a combination of mucoadhesion principle and microencapsulation to result in mucoadhesive microcapsules. Mucoadhesive microcapsules consist of either entirely of a mucoadhesive polymer or having an outer coating enclosing the drug particles. They facilitate an intimate and prolonged contact with the absorption surface to provide controlled release and enhanced bioavailability of the contained drug over longer period of time to prolong its therapeutic action. The objective of the present work is to prepare HPMC based mucoadhesive microcapsules of diclofenac and to evaluate the microcapsules for mucoadhesiveness and controlled drug release characteristics. Spherical HPMC-alginate mucoadhesive micro- capsules of diclofenac could be prepared by the orifice – ionic gelation method. Microencapsulation efficiency was in the range 98.7 % - 103.5 %. Drug release from the HPMC – alginate microcapsules was slow and spread over a period of 12 h and depended on core: coat ratio and wall thickness of the microcapsules. Drug release mechanism from these microcapsules was by non- Fickian diffusion. Good linear relationships were observed between wall thickness of the microcapsules and release rate [K0 and K1] of the microcapsules. Mucoadhesion testing by in vitro wash-off test indicated good mucoadhesive property of HPMC-alginate microcapsules with a slower wash-off when compared to non-mucoadhesive EVA microcapsules. Thus controlled release mucoadhesive microcapsules of diclofenac could be designed employing HPMC-alginate. HPMC-alginate microcapsules of diclofenac exhibited good mucoadhesion and controlled release characteristics and were found suitable for oral controlled release of diclofenac.

  12. [Research advances on controlled-release mechanisms of nutrients in coated fertilizers].

    Science.gov (United States)

    Zhang, Haijun; Wu, Zhijie; Liang, Wenju; Xie, Hongtu

    2003-12-01

    Using encapsulation techniques to coat easily soluble fertilizers is an important way to improve fertilizer use efficiency while reduce environmental hazards. Based on a wide range of literature collection on coated fertilizer research, the theories, processes, and characters of nutrient controlled-release from coated fertilizer were discussed, and the factors affecting nutrient controlled-release and the mathematical simulations on it were reviewed. The main tendencies related to this research in China were also put forward.

  13. PREPARATION AND EVALUATION OF HPMC-ALGINATE MUCOADHESIVE MICROCAPSULES OF DICLOFENAC FOR CONTROLLED RELEASE

    OpenAIRE

    K.P.R. Chowdary

    2011-01-01

    A new, novel promising technology for obtaining controlled release and enhancing the bioavailability is a combination of mucoadhesion principle and microencapsulation to result in mucoadhesive microcapsules. Mucoadhesive microcapsules consist of either entirely of a mucoadhesive polymer or having an outer coating enclosing the drug particles. They facilitate an intimate and prolonged contact with the absorption surface to provide controlled release and enhanced bioavailability of the containe...

  14. Laser-activated nano-biomaterials for tissue repair and controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Matteini, P; Ratto, F; Rossi, F; Pini, R [Institute of Applied Physics ' Nello Carrara' , National Research Council, via Madonna del Piano 10 50019 Sesto Fiorentino (Italy)

    2014-07-31

    We present recent achievements of minimally invasive welding of biological tissue and controlled drug release based on laser-activated nano-biomaterials. In particular, we consider new advancements in the biomedical application of near-IR absorbing gold nano-chromophores as an original solution for the photothermal repair of surgical incisions and as nanotriggers of controlled drug release from hybrid biopolymer scaffolds. (laser biophotonics)

  15. Controlled-Release Oxycodone and Naloxone in the Treatment of Chronic Low Back Pain: A Placebo-Controlled, Randomized Study

    Directory of Open Access Journals (Sweden)

    C Cloutier

    2013-01-01

    Full Text Available BACKGROUND: For Canadian regulatory purposes, an analgesic study was required to complement previously completed, pivotal studies on bowel effects and analgesia associated with controlled-release (CR oxycodone/CR naloxone.

  16. Iron Deficiency and Iron Deficiency Anemia in Children With First Attack of Seizure and on Healthy Control Group: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Razieh FALLAH

    2014-07-01

    Full Text Available How to Cite This Article: Fallah R, Tirandazi F, Ferdosian F, Fadavi N. Iron Deficiency And Iron Deficiency Anemia in Children With First Attack of Seizure and on Healthy Control Group : A Comparative Study. Iran J Child Neurol. 2014 Summer;8(3: 18-23. AbstractObjectiveSeizures are the most common pediatric neurologic problem. Research of the association between iron deficiency and seizures has shown conflicting results.This study evaluates iron status of children with a first seizure attack (febrile seizure (FS or first unprovoked afebrile seizure (FUS and healthy control group.Materials & MethodsIn a cross sectional case control study, iron status of 6–60 month year old admitted children with first seizure to Shahid Sadoughi Hospital from August 2011–December 2012 were evaluated and compared with healthy control children that were referred to primary health care center of Azadshar, Yazd, Iran.Results150 children were compared in three equal (FS, afebrile seizure, and control groups.Hemoglobin levels in FUS (11.39 ± 1.07 g/dl and FS (11.46 ± 1.18 g/dl were lower than the control group (11.9 ± 0.89 g/dl group.Serum iron levels in FS (38.52 ± 11.38 μg/dL and FUS (42.68 ± 14.76 μg/dL were lower than the control group (54.32 ± 13.46 μg/dL.Serum ferritin level in FUS (46.21 ± 27.63 ng/mL and FS (48.91 ±22.96 ng/mL was lower than the control group (75.13 ± 35.57 ng/mL.Iron deficiency (48% in FS, 44% in FUS and 28% in control group and iron deficiency anemia (26% in FUS, 22% in FS, and 10% in healthy children was more frequent in children with seizures.ConclusionIron status should be evaluated in children with a first attack of febrile or afebrile seizures.ReferencesMikati MA. Seizures in Childhood. Kliegman RM, Stanton BF, Schor NF, St. Geme JW, Behrman RE. Nelson Textbook of Pediatrics. Philadelphia, Saunders 2011; 19th edition, Pp: 2013-2017.Yadav D, Chandra J. Iron deficiency: beyond anemia. Indian J Pediatr 2011

  17. Mitofilin regulates cytochrome c release during apoptosis by controlling mitochondrial cristae remodeling

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui-feng; Zhao, Guo-wei; Liang, Shu-ting; Zhang, Yuan; Sun, Li-hong [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China); Chen, Hou-zao, E-mail: houzao@gmail.com [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China); Liu, De-pei, E-mail: liudp@pumc.edu.cn [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer Mitofilin deficiency caused disruption of the cristae structures in HeLa cells. Black-Right-Pointing-Pointer Mitofilin deficiency reduced cell proliferation and increased cell sensitivity to apoptotic stimuli. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated the release of cytochrome c from mitochondria. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated STS-induced intrinsic apoptotic pathway without interfering with the activation of Bax. -- Abstract: Mitochondria amplify caspase-dependent apoptosis by releasing proapoptotic proteins, especially cytochrome c. This process is accompanied by mitochondrial cristae remodeling. Our studies demonstrated that mitofilin, a mitochondrial inner membrane protein, acted as a cristae controller to regulate cytochrome c release during apoptosis. Knockdown of mitofilin in HeLa cells with RNAi led to fragmentation of the mitochondrial network and disorganization of the cristae. Mitofilin-deficient cells showed cytochrome c redistribution between mitochondrial cristae and the intermembrane space (IMS) upon intrinsic apoptotic stimuli. In vitro cytochrome c release experiments further confirmed that, compared with the control group, tBid treatment led to an increase in cytochrome c release from mitofilin-deficient mitochondria. Furthermore, the cells with mitofilin knockdown were more prone to apoptosis by accelerating cytochrome c release upon the intrinsic apoptotic stimuli than controls. Moreover, mitofilin deficiency did not interfere with the activation of proapoptotic member Bax upon intrinsic apoptotic stimuli. Thus, mitofilin distinctly functions in cristae remodeling and controls cytochrome c release during apoptosis.

  18. NAIL AS A PROMISING DRUG DELIVERY SYSTEM FOR CONTROLLED RELEASE

    Directory of Open Access Journals (Sweden)

    G. Sai Krishna*, P. Prem Kumar, K. Bala Murugan

    2013-03-01

    Full Text Available ABSTRACT: The effectiveness of topical therapies is limited by minimal drug permeability through the nail plate. Nail permeability is however quite low and limits topical therapy to early/mild disease states such as onychomycosis (fungal infections of the nail. Current research on nail permeation that focuses on altering the nail plate barrier by means of chemical treatments, penetration enhancers as well as physical and mechanical methods is reviewed also the recent research into ungual drug delivery is reviewed, a new method of nail sampling is examined. Topical therapy is worth pursuing however, as local action is required in many nail disorders. Drug transport into the nail plate can be assisted by filing the nail plate before topical application of drug formulations as well as by the use of chemical enhancers. Finally limitations of current ungual drug permeability studies are briefly discussed and the factors, which affect drug uptake and permeation through the nail plate such as solute molecular size, hydrophilicity/hydrophobicity, charge, and the nature of the vehicle, are then discussed, and drug-containing nail lacquers which, like cosmetic varnish, are brushed onto the nail plates to form a film, and from which drug is released and penetrates into the nail are reviewed. The nail plate behaves like a concentrated hydrogel to permeating molecules and diffusion of molecules through the nail plate has been compared to the diffusion of non-electrolytes through polymer gels. Thus, for optimal ungual permeation and uptake, drug molecules must be of small size and be uncharged.

  19. One-step synthesis of magnetic chitosan for controlled release of 5-hydroxytryptophan

    Energy Technology Data Exchange (ETDEWEB)

    Santos Menegucci, Jucély dos; Santos, Mac-Kedson Medeiros Salviano; Dias, Diego Juscelino Santos; Chaker, Juliano Alexandre; Sousa, Marcelo Henrique, E-mail: mhsqui@gmail.com

    2015-04-15

    In this work, nanoparticles of chitosan embedded with 25% (w/w) of iron oxide magnetic nanoparticles (magnetite/maghemite) with narrow size-distribution and with a loading efficiency of about 80% for 5-hydroxytryptophan (5-HTP), which is a chemical precursor in the biosynthesis of important neurotransmitters as serotonin, were synthesized with an initial mass ratio of 5-HTP/magnetic chitosan=1.2, using homogeneous precipitation by urea decomposition, in an efficient one-step procedure. Characterization of morphology, structure and surface were performed by XRD, TEM, FTIR, TGA, magnetization and zeta potential measurements, while drug loading and drug releasing were investigated using UV–vis spectroscopy. Kinetic drug release experiments under different pH conditions revealed a pH-sensitivecontrolled-release system, ruled by polymer swelling and/or particle dissolution. - Highlights: • One-step synthesis and incorporation of drug in magnetic chitosan. • Synthesis utilizes a cost-effective and environmentally friendly procedure. • Narrow size distribution of magnetic nanoparticles in the composite. • Composite is a basis for a magnetic pH triggered drug release system.

  20. Magnetic hyperthermia controlled drug release in the GI tract: solving the problem of detection

    Science.gov (United States)

    Bear, Joseph C.; Patrick, P. Stephen; Casson, Alfred; Southern, Paul; Lin, Fang-Yu; Powell, Michael J.; Pankhurst, Quentin A.; Kalber, Tammy; Lythgoe, Mark; Parkin, Ivan P.; Mayes, Andrew G.

    2016-09-01

    Drug delivery to the gastrointestinal (GI) tract is highly challenging due to the harsh environments any drug- delivery vehicle must experience before it releases it’s drug payload. Effective targeted drug delivery systems often rely on external stimuli to effect release, therefore knowing the exact location of the capsule and when to apply an external stimulus is paramount. We present a drug delivery system for the GI tract based on coating standard gelatin drug capsules with a model eicosane- superparamagnetic iron oxide nanoparticle composite coating, which is activated using magnetic hyperthermia as an on-demand release mechanism to heat and melt the coating. We also show that the capsules can be readily detected via rapid X-ray computed tomography (CT) and magnetic resonance imaging (MRI), vital for progressing such a system towards clinical applications. This also offers the opportunity to image the dispersion of the drug payload post release. These imaging techniques also influenced capsule content and design and the delivered dosage form. The ability to easily change design demonstrates the versatility of this system, a vital advantage for modern, patient-specific medicine.

  1. Magnetic hyperthermia controlled drug release in the GI tract: solving the problem of detection

    Science.gov (United States)

    Bear, Joseph C.; Patrick, P. Stephen; Casson, Alfred; Southern, Paul; Lin, Fang-Yu; Powell, Michael J.; Pankhurst, Quentin A.; Kalber, Tammy; Lythgoe, Mark; Parkin, Ivan P.; Mayes, Andrew G.

    2016-01-01

    Drug delivery to the gastrointestinal (GI) tract is highly challenging due to the harsh environments any drug- delivery vehicle must experience before it releases it’s drug payload. Effective targeted drug delivery systems often rely on external stimuli to effect release, therefore knowing the exact location of the capsule and when to apply an external stimulus is paramount. We present a drug delivery system for the GI tract based on coating standard gelatin drug capsules with a model eicosane- superparamagnetic iron oxide nanoparticle composite coating, which is activated using magnetic hyperthermia as an on-demand release mechanism to heat and melt the coating. We also show that the capsules can be readily detected via rapid X-ray computed tomography (CT) and magnetic resonance imaging (MRI), vital for progressing such a system towards clinical applications. This also offers the opportunity to image the dispersion of the drug payload post release. These imaging techniques also influenced capsule content and design and the delivered dosage form. The ability to easily change design demonstrates the versatility of this system, a vital advantage for modern, patient-specific medicine. PMID:27671546

  2. Structure-based mutagenesis reveals critical residues in the transferrin receptor participating in the mechanism of pH-induced release of iron from human serum transferrin.

    Science.gov (United States)

    Steere, Ashley N; Chasteen, N Dennis; Miller, Brendan F; Smith, Valerie C; MacGillivray, Ross T A; Mason, Anne B

    2012-03-13

    The recent crystal structure of two monoferric human serum transferrin (Fe(N)hTF) molecules bound to the soluble portion of the homodimeric transferrin receptor (sTFR) has provided new details about this binding interaction that dictates the delivery of iron to cells. Specifically, substantial rearrangements in the homodimer interface of the sTFR occur as a result of the binding of the two Fe(N)hTF molecules. Mutagenesis of selected residues in the sTFR highlighted in the structure was undertaken to evaluate the effect on function. Elimination of Ca(2+) binding in the sTFR by mutating two of four coordinating residues ([E465A,E468A]) results in low production of an unstable and aggregated sTFR. Mutagenesis of two histidines ([H475A,H684A]) at the dimer interface had little effect on the kinetics of release of iron at pH 5.6 from either lobe, reflecting the inaccessibility of this cluster to solvent. Creation of an H318A sTFR mutant allows assignment of a small pH-dependent initial decrease in the magnitude of the fluorescence signal to His318. Removal of the four C-terminal residues of the sTFR, Asp757-Asn758-Glu759-Phe760, eliminates pH-stimulated release of iron from the C-lobe of the Fe(2)hTF/sTFR Δ757-760 complex. The inability of this sTFR mutant to bind and stabilize protonated hTF His349 (a pH-inducible switch) in the C-lobe of hTF accounts for the loss. Collectively, these studies support a model in which a series of pH-induced events involving both TFR residue His318 and hTF residue His349 occurs to promote receptor-stimulated release of iron from the C-lobe of hTF.

  3. Overweight impairs efficacy of iron supplementation in iron-deficient South African children: a randomized controlled intervention

    NARCIS (Netherlands)

    Baumgartner, J.; Smuts, C.M.; Aeberli, I.; Malan, L.; Tjalsma, H.; Zimmermann, M.B.

    2013-01-01

    BACKGROUND: Many countries in the nutrition transition have high rates of iron deficiency (ID) and overweight (OW). ID is more common in OW children; this may be due to adiposity-related inflammation reducing iron absorption. OBJECTIVE: We investigated whether weight status predicts response to oral

  4. Iron oxide nanoparticles show no toxicity in the comet assay in lymphocytes: A promising vehicle as a nitric oxide releasing nanocarrier in biomedical applications

    Science.gov (United States)

    de Lima, R.; Oliveira, J. L.; Murakami, P. S. K.; Molina, M. A. M.; Itri, R.; Haddad, P.; Seabra, A. B.

    2013-04-01

    This work reports the synthesis and toxicological evaluation of surface modified magnetic iron oxide nanoparticles as vehicles to carry and deliver nitric oxide (NO). The surface of the magnetic nanoparticles (MNPs) was coated with two thiol-containing hydrophilic ligands: mercaptosuccinic acid (MSA) or dimercaptosuccinic acid (DMSA), leading to thiolated MNPs. Free thiols groups on the surface of MSA- or DMSA-MNPs were nitrosated leading to NO-releasing MNPs. The genotoxicity of thiolated-coated MNPs was evaluated towards human lymphocyte cells by the comet assay. No genotoxicity was observed due to exposure of human lymphocytes to MSA- or DMSA-MNPs, indicating that these nanovectors can be used as inert vehicles in drug delivery, in biomedical applications. On the other hand, NO-releasing MPNs showed genotoxicity and apoptotic activities towards human lymphocyte cell cultures. These results indicate that NO-releasing MNPs may result in important biomedical applications, such as the treatment of tumors, in which MNPs can be guided to the target site through the application of an external magnetic field, and release NO directly to the desired site of action.

  5. Affinity hydrogels for controlled protein release using nucleic acid aptamers and complementary oligonucleotides.

    Science.gov (United States)

    Soontornworajit, Boonchoy; Zhou, Jing; Snipes, Matthew P; Battig, Mark R; Wang, Yong

    2011-10-01

    Biomaterials for the precise control of protein release are important to the development of new strategies for treating human diseases. This study aimed to fundamentally understand aptamer--protein dissociation triggered by complementary oligonucleotides, and to apply this understanding to develop affinity hydrogels for controlled protein release. The results showed that the oligonucleotide tails of the aptamers played a critical role in inducing intermolecular hybridization and triggering aptamer--protein dissociation. In addition, the attachment of the oligonucleotide tails to the aptamers and the increase of hybridizing length could produce a synergistic effect on the dissociation of bound proteins from their aptamers. More importantly, pegylated complementary oligonucleotides could successfully trigger protein release from the aptamer-functionalized hydrogels at multiple time points. Based on these results, it is believed that aptamer-functionalized hydrogels and complementary oligonucleotides hold great potential of controlling the release of protein drugs to treat human diseases.

  6. Control of doxorubicin release from magnetic Poly(dl-lactide-co-glycolide) nanoparticles by application of a non-permanent magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Peça, Inês N. [Universidade Nova de Lisboa, LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia (Portugal); Bicho, A.; Gardner, Rui [Instituto Gulbenkian de Ciência (Portugal); Cardoso, M. Margarida, E-mail: margarida.cardoso@fct.unl.pt [Universidade Nova de Lisboa, LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia (Portugal)

    2015-11-15

    This work studied the effect of the application time of a non-permanent magnetic field on the rate of drug release from iron oxide polymeric nanoparticles. Magnetically responsive doxorubicin loaded poly(d-lactide-co-glycolide) (PLGA) nanoparticles were synthetized by the o/w solvent extraction/evaporation method and characterized. The produced particles show spherical shapes exhibiting a size between 200 and 400 nm, a drug loading of 3.6 % (w/w) and an iron concentration of 20.7 % (w/w). Cell cytotoxicity tests showed that unloaded magnetic PLGA nanoparticles were nontoxic. Concerning the therapeutic activity, doxorubicin-loaded magnetic particles cause a remarkable enhancement of the cell inhibition rates compared to their non-magnetic counterparts (40 against 7 % of dead cells). In vitro drug release studies performed under a non-permanent magnetic field show that the application time and the on/off cycle duration have a great influence with respect to the final amount and to the rate of drug release. The final amount and the rate of doxorubicin released increase with the time of field application reaching higher values for a higher number of pulses with a lower duration. Doxorubicin release mechanism has shown to be governed by Fickian diffusion in the absence of a magnetic field while in the presence of a magnetic field some controlled relaxation polymer chains might also be present. The results show that the drug release rate from magnetic PLGA nanoparticles can be modulated through the application time and the on/off cycles duration of a non-permanent magnetic field.

  7. [Effects of slow/controlled release fertilizers on the growth and nutrient use efficiency of pepper].

    Science.gov (United States)

    Tang, Shuan-Hu; Zhang, Fa-Bao; Huang, Xu; Chen, Jian-Sheng; Xu, Pei-Zhi

    2008-05-01

    Pot trails were conducted from 2003 to 2005 to study the effects of slow/controlled release fertilizers on the growth and nutrient use efficiency of pepper. The results indicated that in comparison with conventional splitting fertilization (T1), basal application of polymer-coated controlled release fertilizer (T2) enhanced the single fruit mass and vitamin C concentration, improved the root activity, and increased the fruit yield by 8.4%, but no significant effect was observed on the dissoluble sugar concentration in fruit. NH4MgPO4-coated controlled release fertilizer (T3) increased the dissoluble sugar concentration by 5.67%, but had less effect on single fruit mass and vitamin C concentration. Under the application of T3, the root system had a vigorous growth at early stages but became infirm at later stages, resulting in a lower yield. Comparing with T1, the application of 3 slow release fertilizers increased the dissoluble sugar concentration in fruit, enhanced the root activity, but had less effect on the yield. All test slow/controlled release fertilizers increased the use efficiency of N, P, and K significantly, with an exception for T2 which increased the use efficiency of N and K but decreased that of P. It was demonstrated that an appropriate application of slow/controlled release fertilizers could enhance pepper' s root activity and improve nutrient use efficiency.

  8. Preparation and characterization of controlled-release fertilizers coated with marine polysaccharide derivatives

    Science.gov (United States)

    Wang, Jing; Liu, Song; Qin, Yukun; Chen, Xiaolin; Xing, Rong'e.; Yu, Huahua; Li, Kecheng; Li, Pengcheng

    2017-09-01

    Encapsulation of water-soluble nitrogen fertilizers by membranes can be used to control the release of nutrients to maximize the fertilization effect and reduce environmental pollution. In this research, we formulated a new double-coated controlled-release fertilizer (CRF) by using food-grade microcrystalline wax (MW) and marine polysaccharide derivatives (calcium alginate and chitosan-glutaraldehyde copolymer). The pellets of water-soluble nitrogen fertilizer were coated with the marine polysaccharide derivatives and MW. A convenient and eco-friendly method was used to prepare the CRF. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and composition of the products. The nitrogen-release properties were determined in water using UV-Vis spectrophotometry. The controlled-release properties of the fertilizer were improved dramatically after coating with MW and the marine polysaccharide derivatives. The results show that the double-coated CRFs can release nitrogen in a controlled manner, have excellent controlled-release features, and meet the European Standard for CRFs.

  9. Preparation and characterization of controlled-release fertilizers coated with marine polysaccharide derivatives

    Science.gov (United States)

    Wang, Jing; Liu, Song; Qin, Yukun; Chen, Xiaolin; Xing, Rong'e.; Yu, Huahua; Li, Kecheng; Li, Pengcheng

    2016-10-01

    Encapsulation of water-soluble nitrogen fertilizers by membranes can be used to control the release of nutrients to maximize the fertilization effect and reduce environmental pollution. In this research, we formulated a new double-coated controlled-release fertilizer (CRF) by using food-grade microcrystalline wax (MW) and marine polysaccharide derivatives (calcium alginate and chitosan-glutaraldehyde copolymer). The pellets of water-soluble nitrogen fertilizer were coated with the marine polysaccharide derivatives and MW. A convenient and eco-friendly method was used to prepare the CRF. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and composition of the products. The nitrogen-release properties were determined in water using UV-Vis spectrophotometry. The controlled-release properties of the fertilizer were improved dramatically after coating with MW and the marine polysaccharide derivatives. The results show that the double-coated CRFs can release nitrogen in a controlled manner, have excellent controlled-release features, and meet the European Standard for CRFs.

  10. Iron ore sintering. Part 3: Automatic and control systems

    Directory of Open Access Journals (Sweden)

    Alejandro Cores

    2015-01-01

    Full Text Available El proceso de sinterización implica un gran número de parámetros, más de quinientos, cada uno de los cuales ejerce una mayor o menor influencia y necesita ser controlado, dentro de los límites posibles, con el fin de optimizar la productividad, la estabilidad del proceso, y la composición y la calidad de la sinterizado producido. Para cumplir con la legislación ambiental, un sistema de control de la contaminación debe monitorizar la composición de las partículas y los gases generados en la planta de sinterización y emitidos a la atmósfera. Los sistemas de automatización y control son herramientas vitales para ayudar a los operadores de la planta en el seguimiento de cada etapa del proceso de producción de sinterizado.

  11. Geochemical and microbiological controls on dissimilatory iron reduction

    Science.gov (United States)

    Roden, Eric E.

    2006-06-01

    Recent experimental studies permit development of conceptual and quantitative models of microbial Fe(III) oxide reduction at circumneutral pH that can be compared to and contrasted with established models of abiotic mineral dissolution. The findings collectively support a model for controls on enzymatic reduction that differs fundamentally from those applied to abiotic reductive dissolution as a result of two basic phenomena: (1) the relatively minor influence of oxide mineralogical and thermodynamic properties on rates of enzymatic reduction compared to abiotic reductive dissolution, and (2) the major limitation which sorption and/or surface precipitation of biogenic Fe(II) on residual oxide and Fe(III)-reducing bacterial cell surfaces poses to enzymatic electron transfer in the presence of excess electron donor. Parallel studies with two well-characterized Fe(III)-reducing organisms ( Shewanella putrefaciens and Geobacter sulfurreducens) lead to common conclusions regarding the importance of these phenomena in regulating the rate and long-term extent of Fe(III) oxide reduction. Models in which rates of enzymatic reduction are limited by Fe(III)-reducing bacterial cell density together with the abundance of 'available' oxide surface sites (as controlled by oxide surface area and the accumulation of surface-bound biogenic Fe(II)) provide an adequate macroscopic description of controls on the initial rate and long-term extent of oxide reduction. To cite this article: E.E. Roden, C. R. Geoscience 338 (2006).

  12. Solution combustion synthesis of calcium phosphate particles for controlled release of bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Junfeng, E-mail: daidai02304@163.com [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu (China); Zhao, Junjie; Qian, Yu; Zhang, Xiali; Zhou, Feifei; Zhang, Hong [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Lu, Hongbin [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing (China); Chen, JianHua; Wang, XuHong [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China); Jiangsu Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu (China); Yu, Wencong [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu (China)

    2015-05-01

    Four different phase compositions of calcium phosphate (CaP) particles were prepared via a solution combustion method. X-ray diffraction (XRD) and Rietveld analysis results revealed that the variations in the nominal Ca/P (molar) ratios were found to provide a favorable control in the different proportions of CaP materials. Bovine serum albumin (BSA) was used as a model protein to study the loading and release behavior. The release profile indicated that the BSA release rates depended on the phase compositions of the CaP particles, and showed an order of TCP-BSA > BCP-1-BSA > BCP-2-BSA > HA-BSA. The results suggested that the BSA protein release rate can be controlled by varying the phase compositions of CaP carriers. Moreover, the release process involved two stages: firstly surface diffusion via ion exchange and secondly intraparticle diffusion. - Highlights: • Solution combustion method was an efficient way to produced CaP powders. • Ca/P (molar) ratios provided a favorable control in the different proportions of phase composition. • BSA release rate varied depending on the phase composition of the CaP particles. • Two kinetic models were chosen to simulate the release kinetics of the drugs from CaP carriers.

  13. Detecting Organic Compounds Released from Iron Oxidizing Bacteria using Sample Analysis at Mars (SAM) Like Instrument Protocols

    Science.gov (United States)

    Glavin, D. P.; Popa, R.; Martin, M. G.; Freissinet, C.; Fisk, M. R.; Dworkin, J. P.; Mahaffy, P. R.

    2012-01-01

    Mars is a planet of great interest for Astrobiology since its past environmental conditions are thought to have been favourable for the emergence life. At present, the Red Planet is extremely cold and dry and the surface is exposed to intense UV and ionizing radiation, conditions generally considered to be incompatible with life as we know it on Earth. It was proposed that the shallow subsurface of Mars, where temperatures can be above freezing and liquid water can exist on rock surfaces, could harbor chemolithoautotrophic bacteria such as the iron oxidizing microorganism Pseudomonas sp. HerB. The Mars Science Laboratory (MSL) mission will provide the next opportunity to carry out in situ measurements for organic compounds of possible biological origin on Mars. One instrument onboard MSL, called the Sample Analysis at Mars (SAM) instrument suite, will carry out a broad and sensitive search for organic compounds in surface samples using either high temperature pyrolysis or chemical extraction followed by gas chromatography mass spectrometry. We present gas chromatograph mass spectrometer (GC/MS) data on crushed olivine rock powders that have been inoculated with Pseudomonas sp. HerB at different concentrations ranging from approx 10(exp 2) to 10(exp 7) cells per gram. The inoculated olivine samples were heated under helium carrier gas flow at 500 C and the pyrolysis products concentrated using a SAM-like hydrocarbon trap set at -20 C followed by trap heating and analysis by GC/Ms. In addition, the samples were also extracted using a low temperature "one-pot" chemical extraction technique using N-methyl, N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) as the silylating agent prior to GC/MS analysis. We identified several aldehydes, thiols, and alkene nitriles after pyrolysis GC/MS analysis of the bacteria that were not found in the olivine control samples that had not been inoculated with bacteria. The distribution of pyrolysis products extracted from the

  14. Opposing authigenic controls on the isotopic signature of dissolved iron in hydrothermal plumes

    Science.gov (United States)

    Lough, A. J. M.; Klar, J. K.; Homoky, W. B.; Comer-Warner, S. A.; Milton, J. A.; Connelly, D. P.; James, R. H.; Mills, R. A.

    2017-04-01

    Iron is a scarce but essential micronutrient in the oceans that limits primary productivity in many regions of the surface ocean. The mechanisms and rates of Fe supply to the ocean interior are still poorly understood and quantified. Iron isotope ratios of different Fe pools can potentially be used to trace sources and sinks of the global Fe biogeochemical cycle if these boundary fluxes have distinct signatures. Seafloor hydrothermal vents emit metal rich fluids from mid-ocean ridges into the deep ocean. Iron isotope ratios have the potential to be used to trace the input of hydrothermal dissolved iron to the oceans if the local controls on the fractionation of Fe isotopes during plume dispersal in the deep ocean are understood. In this study we assess the behaviour of Fe isotopes in a Southern Ocean hydrothermal plume using a sampling program of Total Dissolvable Fe (TDFe), and dissolved Fe (dFe). We demonstrate that δ56Fe values of dFe (δ56dFe) within the hydrothermal plume change dramatically during early plume dispersal, ranging from -2.39 ± 0.05‰ to -0.13 ± 0.06‰ (2 SD). The isotopic composition of TDFe (δ56TDFe) was consistently heavier than dFe values, ranging from -0.31 ± 0.03‰ to 0.78 ± 0.05‰, consistent with Fe oxyhydroxide precipitation as the plume samples age. The dFe present in the hydrothermal plume includes stabilised dFe species with potential to be transported to the deep ocean. We estimate that stable dFe exported from the plume will have a δ56Fe of -0.28 ± 0.17‰. Further, we show that the proportion of authigenic iron-sulfide and iron-oxyhydroxide minerals precipitating in the buoyant plume exert opposing controls on the resultant isotope composition of dissolved Fe passed into the neutrally buoyant plume. We show that such controls yield variable dissolved Fe isotope signatures under the authigenic conditions reported from modern vent sites elsewhere, and so ought to be considered during iron isotope reconstructions of past

  15. Design and evaluation of controlled onset extended release multiparticulate systems for chronotherapeutic delivery of ketoprofen

    Directory of Open Access Journals (Sweden)

    Shivakumar H

    2006-01-01

    Full Text Available An oral controlled onset extended release dosage form intended to approximate the chronobiology of rheumatoid arthritis is proposed for site-specific release to the colon. The multiparticulate system consisting of drug-loaded cellulose acetate cores encapsulated within Eudragit S-100 microcapsules was designed for chronotherapeutic delivery of ketoprofen. Drug-loaded cellulose acetate cores were prepared by emulsion solvent evaporation technique in an oily phase at different drug:polymer ratios (1:1, 2:1 and 4:1. These cores were successfully microencapsulated with Eudragit S-100 following the same technique at the core:coat ratio of 1:5. Scanning electron microscopy (SEM revealed that the cellulose acetate cores were discrete, uniform and spherical with a porous and rough surface, whereas the Eudragit microcapsules were discrete and spherical with a smooth and dense surface. In vitro drug release studies of the Eudragit microcapsules were performed in different pH conditions following pH-progression method for a period of 16 h. The release studies indicated that the microcapsules posses both pH-sensitive and controlled-release properties, showing limited drug release below pH 7.0 (6.40 to 8.94%, following which the cellulose acetate cores effectively controlled the drug release for a period of 11 h in pH 7.5. The differential scanning calorimetric and powder X-ray diffraction studies demonstrated that ketoprofen was present in dissolved state in the cellulose acetate polymeric matrix, which could explain the controlled drug release from the cores. The release of ketoprofen from Eudragit microcapsules in pH 7.5 depended on the cellulose acetate levels and was characterized by Higuchi′s diffusion model.

  16. Effects of Controlled Release Fertilizer on the Flag Leaves Senescence in Dry-land Wheat

    Directory of Open Access Journals (Sweden)

    Dandan Liu

    2013-05-01

    Full Text Available In order to select a reasonable controlled release fertilizer application method to slow down the senescence of flag leaf in dry-land wheat. The effects of controlled release fertilizer on soluble protein content, MDA content, the Catalase (CAT activity, the Superoxide Dismutase (SOD activity on the flag leaves senescence in dry-land wheat had been studied in the open field with the variety wheat Jimai22. The results indicated that, the combination application of controlled release fertilizer with conventional complex fertilizer on wheat was more conducive to the promotion of the soluble protein synthesis and it controlled the increasing of MDA content in flag leaf more effectively than the application of conventional complex fertilizer or controlled-release fertilizer alone on wheat. And it was more conductive to control or delay the process of flag leaf senescence with better maintenance of the SOD activity. The treatments in application of controlled release fertilization alone were conducive to these treatments with conventional complex fertilizer alone. Among these treatments, T6 was the best fertilization method with the lowest flag leaf senescence speed.

  17. Controlled release of an anti-cancer drug from DNA structured nano-films

    Science.gov (United States)

    Cho, Younghyun; Lee, Jong Bum; Hong, Jinkee

    2014-02-01

    We demonstrate the generation of systemically releasable anti-cancer drugs from multilayer nanofilms. Nanofilms designed to drug release profiles in programmable fashion are promising new and alternative way for drug delivery. For the nanofilm structure, we synthesized various unique 3-dimensional anti cancer drug incorporated DNA origami structures (hairpin, Y, and X shaped) and assembled with peptide via layer-by-layer (LbL) deposition method. The key to the successful application of these nanofilms requires a novel approach of the influence of DNA architecture for the drug release from functional nano-sized surface. Herein, we have taken first steps in building and controlling the drug incorporated DNA origami based multilayered nanostructure. Our finding highlights the novel and unique drug release character of LbL systems in serum condition taken full advantages of DNA origami structure. This multilayer thin film dramatically affects not only the release profiles but also the structure stability in protein rich serum condition.

  18. Controlled-Release Personal Use Arthropod Repellent Formulation

    Science.gov (United States)

    1985-09-25

    deodorant , or other cosmetic enhancers, and rinsed with 70% ethanol. For each subject control site, (5 cm in diameter), anG two test sites, 6 x 16.7 cm...Camouflage 0-1 c) Polyurethane Rifle Stocks 51 Metals S-1 a) Aluminum General Equipeent 6) Natural Products -- I a) Leather Boots 7) Textiles T-1 a...The area was slightly tacky to touch and a definite loss of gloss was noted. * e. metals Aluminum was not visibly affected by all three solutions. f

  19. Kinetics and corrosion products of aqueous nitrate reduction by iron powder without reaction conditions control

    Institute of Scientific and Technical Information of China (English)

    FAN Xiaomeng; GUAN Xiaohong; MA Jun; AI Hengyu

    2009-01-01

    Although considerable research has been conducted on nitrate reduction by zero-valent iron powder (Fe0), these studies were mostly operated under anaerobic and invariable pH conditions that was unsuitable for practical application.Without reaction conditions (dissolved oxygen or reaction pH) control, this study aimed at subjecting the kinetics of denitrification by microscale Fe0 (160-200 mesh) to analysis the factors affecting the denitrification of nitrate and the composition of iron reductive products coating upon the iron surface.Results of the kinetics study have indicated that a higher initial concentration of nitrate would yield a greater reaction rate constant.Additional test results showed that the reduction rate of nitrate increased with increasing Fe0 dosage.The reaction can be described as a pseudo-first order reaction with respect to nitrate concentration or Fe0 dosage.Experimental results also suggested that nitrate reduction by microscale Fe0 without reaction condition control primarily was an acid-driven surface-mediated process, and the reaction order was 0.65 with respect to hydrogen ion concentration.X-ray diffractometry and X-ray photoelectron spectroscopy indicated that a black coating, consisted of Fe2O3, Fe3O4 and FeO(OH), was formed on the surface of iron grains as an iron corrosion product when the system initial pH was lower than 5.The proportion of FeO(OH) increased as reaction time went on, whereas the proportion of Fe3O4 decreased.

  20. Feasibility of sulfide control in sewers by reuse of iron rich drinking water treatment sludge.

    Science.gov (United States)

    Sun, Jing; Pikaar, Ilje; Sharma, Keshab Raj; Keller, Jürg; Yuan, Zhiguo

    2015-03-15

    Dosage of iron salt is the most commonly used method for sulfide control in sewer networks but incurs high chemical costs. In this study, we experimentally investigate the feasibility of using iron rich drinking water treatment sludge for sulfide control in sewers. A lab-scale rising main sewer biofilm reactor was used. The sulfide concentration in the effluent decreased from 15.5 to 19.8 mgS/L (without dosing) to below 0.7-2.3 mgS/L at a sludge dosing rate achieving an iron to total dissolved inorganic sulfur molar ratio (Fe:S) of 1:1, with further removal of sulfide possible by prolonging the reaction time. In fact, batch tests revealed an Fe consumption to sulfide removal ratio of 0.5 ± 0.02 (mole:mole), suggesting the possible occurrence of other reactions involving the removal of sulfide. Modelling revealed that the reaction between iron in sludge and sulfide has reaction orders of 0.65 ± 0.01 and 0.77 ± 0.02 with respect to the Fe and sulfide concentrations, respectively. The addition of sludge slightly increased the total chemical oxidation demand (tCOD) concentration (by approximately 12%) as expected, but decreased the soluble chemical oxidation demand (sCOD) concentration and methane formation by 7% and 20%, respectively. Some phosphate removal (13%) was also observed at the sludge dosing rate of 1:1 (Fe:S), which is beneficial to nutrient removal from the wastewater. Overall, this study suggests that dosing iron-rich drinking water sludge to sewers could be an effective strategy for sulfide removal in sewer systems, which would also reduce the sludge disposal costs for drinking water treatment works. However, its potential side-effects on sewer sedimentation and on the wastewater treatment plant effluent remain to be investigated.

  1. Controlling pH in shake flasks using polymer-based controlled-release discs with pre-determined release kinetics

    Directory of Open Access Journals (Sweden)

    Klee Doris

    2011-03-01

    Full Text Available Abstract Background There are significant differences in the culture conditions between small-scale screenings and large-scale fermentation processes. Production processes are usually conducted in fed-batch cultivation mode with active pH-monitoring and control. In contrast, screening experiments in shake flasks are usually conducted in batch mode without active pH-control, but with high buffer concentrations to prevent excessive pH-drifts. These differences make it difficult to compare results from screening experiments and laboratory and technical scale cultivations and, thus, complicate rational process development. In particular, the pH-value plays an important role in fermentation processes due to the narrow physiological or optimal pH-range of microorganisms. To reduce the differences between the scales and to establish a pH-control in shake flasks, a newly developed easy to use polymer-based controlled-release system is presented in this paper. This system consists of bio-compatible silicone discs embedding the alkaline reagent Na2CO3. Since the sodium carbonate is gradually released from the discs in pre-determined kinetics, it will ultimately compensate the decrease in pH caused by the biological activity of microorganisms. Results The controlled-release discs presented here were successfully used to cultivate E. coli K12 and E. coli BL21 pRSET eYFP-IL6 in mineral media with glucose and glycerol as carbon (C sources, respectively. With glucose as the C-source it was possible to reduce the required buffer concentration in shake flask cultures by 50%. Moreover, with glycerol as the C-source, no buffer was needed at all. Conclusions These novel polymer-based controlled-release discs allowed buffer concentrations in shake flask media to be substantially reduced or omitted, while the pH remains in the physiological range of the microorganisms during the whole cultivation time. Therefore, the controlled-release discs allow a better control of

  2. Controlled poorly soluble drug release from solid self-microemulsifying formulations with high viscosity hydroxypropylmethylcellulose.

    Science.gov (United States)

    Yi, Tao; Wan, Jiangling; Xu, Huibi; Yang, Xiangliang

    2008-08-07

    The objective of this work was the development of a controlled release system based on self-microemulsifying mixture aimed for oral delivery of poorly water-soluble drugs. HPMC-based particle formulations were prepared by spray drying containing a model drug (nimodipine) of low water solubility and hydroxypropylmethylcellulose (HPMC) of high viscosity. One type of formulations contained nimodipine mixed with HPMC and the other type of formulations contained HPMC and nimodipine dissolved in a self-microemulsifying system (SMES) consisting of ethyl oleate, Cremophor RH 40 and Labrasol. Based on investigation by transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray powder diffraction, differences were found in the particle structure between both types of formulations. In vitro release was performed and characterized by the power law. Nimodipine release from both types of formulations showed a controlled release profile and the two power law parameters, n and K, correlated to the viscosity of HPMC. The parameters were also influenced by the presence of SMES. For the controlled release solid SMES, oil droplets containing dissolved nimodipine diffused out of HPMC matrices following exposure to aqueous media. Thus, it is possible to control the in vitro release of poorly soluble drugs from solid oral dosage forms containing SMES.

  3. Controlled release properties of zein-fatty acid blend films for multiple bioactive compounds.

    Science.gov (United States)

    Arcan, Iskender; Yemenicioğlu, Ahmet

    2014-08-13

    To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ⁹, linoleic (C18:2)Δ(9,12), or lauric (C₁₂) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm². The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food.

  4. Controlled growth of iron oxide nanoparticles in the aqueous microdroplets.

    Science.gov (United States)

    Jeon, Bong-sik; Lee, Seung-Jun; Kim, Jong-Duk

    2008-09-01

    Magnetite nanoparticles were synthesized by chemical coprecipitation of ferric and ferrous aqueous solutions via regulation of the microenvironment at ambient conditions. Nanocrystals having an average diameter of 6 to 12 nm were obtained by picoliter droplets, whereas only 9 nm diameter nanocrystals were prepared by microliter droplets. The size of the nanocrystals was controlled by a precise balance of reactions of hydroxide ions with positive ions at the surface layer and inner layers of the droplets. The crystal structure and average size were analyzed by X-ray diffraction pattern and transmission electron microscope images. The field dependence and temperature dependence on magnetization measured by a superconducting quantum interference device demonstrate that the as-synthesized particles are superparamagnetic at room temperature and have a size-dependent magnetic property. The anisotropy constant calculated by the blocking temperature and particle size was found to decrease with increasing particle size.

  5. Alginate inhibits iron absorption from ferrous gluconate in a randomized controlled trial and reduces iron uptake into Caco-2 cells.

    Science.gov (United States)

    Wawer, Anna A; Harvey, Linda J; Dainty, Jack R; Perez-Moral, Natalia; Sharp, Paul; Fairweather-Tait, Susan J

    2014-01-01

    Previous in vitro results indicated that alginate beads might be a useful vehicle for food iron fortification. A human study was undertaken to test the hypothesis that alginate enhances iron absorption. A randomised, single blinded, cross-over trial was carried out in which iron absorption was measured from serum iron appearance after a test meal. Overnight-fasted volunteers (n = 15) were given a test meal of 200 g cola-flavoured jelly plus 21 mg iron as ferrous gluconate, either in alginate beads mixed into the jelly or in a capsule. Iron absorption was lower from the alginate beads than from ferrous gluconate (8.5% and 12.6% respectively, p = 0.003). Sub-group B (n = 9) consumed the test meals together with 600 mg calcium to determine whether alginate modified the inhibitory effect of calcium. Calcium reduced iron absorption from ferrous gluconate by 51%, from 11.5% to 5.6% (p = 0.014), and from alginate beads by 37%, from 8.3% to 5.2% (p = 0.009). In vitro studies using Caco-2 cells were designed to explore the reasons for the difference between the previous in vitro findings and the human study; confirmed the inhibitory effect of alginate. Beads similar to those used in the human study were subjected to simulated gastrointestinal digestion, with and without cola jelly, and the digestate applied to Caco-2 cells. Both alginate and cola jelly significantly reduced iron uptake into the cells, by 34% (p = 0.009) and 35% (p = 0.003) respectively. The combination of cola jelly and calcium produced a very low ferritin response, 16.5% (p ferrous gluconate alone. The results of these studies demonstrate that alginate beads are not a useful delivery system for soluble salts of iron for the purpose of food fortification. ClinicalTrials.gov NCT01528644.

  6. Relationship between Iron Accumulation and White Matter Injury in Multiple Sclerosis: A Case-Control Study

    Science.gov (United States)

    Raz, Eytan; Branson, Brittany; Jensen, Jens H.; Bester, Maxim; Babb, James S.; Herbert, Joseph; Grossman, Robert I.; Inglese, Matilde

    2015-01-01

    PURPOSE Despite the increasing development and applications of iron imaging, the pathophysiology of iron accumulation in multiple sclerosis (MS), and its role in disease progression and development of clinical disability, is poorly understood. The aims of our study were to determine the presence and extent of iron in T2 visible lesions and gray and white matter using magnetic field correlation (MFC) MRI and correlate with microscopic white matter (WM) injury as measured by diffusion tensor imaging (DTI). MATERIALS AND METHODS This is a case-control study incuding a series of 31 patients with clinically definite MS. The mean age was 39 years [standard deviation (SD)=9.55], they were 11 males and 20 females, with a disease duration average of 3 years (range 0-13) and a median EDSS of 2 (0-4.5). Seventeen healthy volunteers (6 males and 11 females) with a mean age of 36 years (SD=11.4) were recruited. All subjects underwent MR imaging on a 3T scanner using T2-weighted sequence, 3D T1 MPRAGE, MFC, single-shot DTI and postcontrast T1. T2-lesion volumes, brain volumetry, DTI parameters and iron quantification were calculated and multiple correlations were exploited. RESULTS Increased MFC was found in the putamen (p=0.061), the thalamus (p=0.123), the centrum semiovale (p=0.053), globus pallidus (p=0.008) and gray matter (GM) (p=0.004) of MS patients compared to controls. The mean lesional MFC was 121 s−2 (SD=67), significantly lower compared to the GM MFC (<0.0001). The GM mean diffusivity (MD) was inversely correlated with the MFC in the centrum semiovale (p<0.001), and in the splenium of the corpus callosum (p<0.001). CONCLUSION Patients with MS have increased iron in the globus pallidus, putamen and centrum with a trend toward increased iron in all the brain structures. Quantitative iron evaluation of WM and GM may improve the understanding of MS pathophysiology, and might serve as a surrogate marker of disease progression. PMID:25416468

  7. Mercury mass flow in iron and steel production process and its implications for mercury emission control.

    Science.gov (United States)

    Wang, Fengyang; Wang, Shuxiao; Zhang, Lei; Yang, Hai; Gao, Wei; Wu, Qingru; Hao, Jiming

    2016-05-01

    The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%-49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%-36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039-0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%-73% of total mercury emissions to air.

  8. E-Control: First Public Release of Remote Control Software for VLBI Telescopes

    Science.gov (United States)

    Neidhardt, Alexander; Ettl, Martin; Rottmann, Helge; Ploetz, Christian; Muehlbauer, Matthias; Hase, Hayo; Alef, Walter; Sobarzo, Sergio; Herrera, Cristian; Himwich, Ed

    2010-01-01

    Automating and remotely controlling observations are important for future operations in a Global Geodetic Observing System (GGOS). At the Geodetic Observatory Wettzell, in cooperation with the Max-Planck-Institute for Radio Astronomy in Bonn, a software extension to the existing NASA Field System has been developed for remote control. It uses the principle of a remotely accessible, autonomous process cell as a server extension for the Field System. The communication is realized for low transfer rates using Remote Procedure Calls (RPC). It uses generative programming with the interface software generator idl2rpc.pl developed at Wettzell. The user interacts with this system over a modern graphical user interface created with wxWidgets. For security reasons the communication is automatically tunneled through a Secure Shell (SSH) session to the telescope. There are already successful test observations with the telescopes at O Higgins, Concepcion, and Wettzell. At Wettzell the software is already used routinely for weekend observations. Therefore the first public release of the software is now available, which will also be useful for other telescopes.

  9. Controlled release from aspirin based linear biodegradable poly(anhydride esters) for anti-inflammatory activity.

    Science.gov (United States)

    Dasgupta, Queeny; Movva, Sahitya; Chatterjee, Kaushik; Madras, Giridhar

    2017-08-07

    This work reports the synthesis of a novel, aspirin-loaded, linear poly (anhydride ester) and provides mechanistic insights into the release of aspirin from this polymer for anti-inflammatory activity. As compared to conventional drug delivery systems that rely on diffusion based release, incorporation of bioactives in the polymer backbone is challenging and high loading is difficult to achieve. In the present study, we exploit the pentafunctional sugar alcohol (xylitol) to provide sites for drug (aspirin) attachment at its non-terminal OH groups. The terminal OH groups are polymerized with a diacid anhydride. The hydrolysis of the anhydride and ester bonds under physiological conditions release aspirin from the matrix. The resulting poly(anhydride ester) has high drug loading (53%) and displays controlled release kinetics of aspirin. The polymer releases 8.5 % and 20%, of the loaded drug in one and four weeks, respectively and has a release rate constant of 0.0035h(-0.61). The release rate is suitable for its use as an anti-inflammatory agent without being cytotoxic. The polymer exhibits good cytocompatibility and anti-inflammatory properties and may find applications as injectable or as an implantable bioactive material. The physical insights into the release mechanism can provide development of other drug loaded polymers. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Plasmon excitation of supported gold nanoparticles can control molecular release from supramolecular systems.

    Science.gov (United States)

    Marquez, Daniela T; Carrillo, Adela I; Scaiano, Juan C

    2013-08-20

    Hybrid mesoporous silica materials containing gold nanoparticles (AuNPs) have been investigated as potential molecular delivery systems. The photophysical properties of AuNPs, particularly their plasmon band transitions, have been used to control the rate of the release of naproxen from the pores of mesoporous silica matrices. Two different approaches were employed to incorporate AuNPs into the silica network: that is, grafting (using 3-aminopropyltriethoxisilane) and direct absorption. In this research, the anti-inflamatory drug naproxen serves as a test molecule, showing how localized plasmon heating could be used to modify diffusion kinetics within mesoporous materials. Beyond naproxen release, the methodology developed could be employed to release other drugs, sensors, or active molecules, not just in medicine, but in many other fields where nanotechnology is leading to many innovative applications. The hybrid materials developed show a new simple system to efficiently control the release of active cargo from mesoporous silica matrices.

  11. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    Science.gov (United States)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  12. Smart electrospun nanofibers for controlled drug release: recent advances and new perspectives.

    Science.gov (United States)

    Weng, Lin; Xie, Jingwei

    2015-01-01

    In biological systems, chemical molecules or ions often release upon certain conditions, at a specific location, and over a desired period of time. Electrospun nanofibers that undergo alterations in the physicochemical characteristics corresponding to environmental changes have gained considerable interest for various applications. Inspired by biological systems, therapeutic molecules have been integrated with these smart electrospun nanofibers, presenting activation-modulated or feedback-regulated control of drug release. Compared to other materials like smart hydrogels, environment-responsive nanofiber-based drug delivery systems are relatively new but possess incomparable advantages due to their greater permeability, which allows shorter response time and more precise control over the release rate. In this article, we review the mechanisms of various environmental parameters functioning as stimuli to tailor the release rates of smart electrospun nanofibers. We also illustrate several typical examples in specific applications. We conclude this article with a discussion on perspectives and future possibilities in this field.

  13. Formulation optimization of hydrodynamically balanced oral controlled release bioadhesive tablets of tramadol hydrochloride.

    Science.gov (United States)

    Singh, Bhupinder; Rani, Ashu; Babita; Ahuja, Naveen; Kapil, Rishi

    2010-01-01

    The directly compressible floating-bioadhesive tablets of tramadol were formulated using varying amounts Carbopol 971P (CP) and hydroxy-propylmethyl cellulose (HPMC), along with other requisite excipients. In vitro drug release profile, floatational characteristics and ex vivo bioadhesive strength using texture analyzer were determined, and systematically optimized using a 3(2) central composite design (CCD). The studies indicated successful formulation of gastroretentive compressed matrices with excellent controlled release, mucoadhesion and hydrodynamic balance. Comparison of the dissolution profiles of the optimized formulation, with optimal composition of CP:HPMC :: 80.0:125.0, with that of the marketed controlled release formulation other indicated analogy of drug release performance with each other. Validation of optimization study using eight confirmatory experimental runs indicated very high degree of prognostic ability of CCD with mean  SEM of â0.06%  0.37. Further, the study successfully unravels the effect of the polymers on the selected response variables.

  14. FABRICATION AND EVALUATION OF GLIPIZIDE ABELMOSCHUS ESCULENTUS FRUIT MUCILAGE POVIDONE CONTROLLED RELEASE MATRIX TABLETS

    Directory of Open Access Journals (Sweden)

    Hindustan Abdul Ahad

    2011-02-01

    Full Text Available The present investigation was aimed to prepare matrix type controlled release tablets of Glipizide with Abelmoschus esculentus fruit mucilage and Povidone. The polymers were studied for its functionality as a matrix forming property to sustain the Glipizide release from the dosage form. Physicochemical properties of dried powdered mucilage of Abelmoschus esculentus fruit mucilage and Povidone blend were studied. Various formulations of Glipizide Abelmoschus esculentus fruit mucilage and Povidone were prepared. The prepared tablets were found to have better pharmacopoeial parameters with low standard deviation values. The swelling behavior and release rate characteristics were studied. The in-vitro dissolution study proved that the dried Abelmoschus esculentus fruit mucilage and Povidone in combination can be used as a matrix forming polymers for making controlled release matrix tablets.

  15. Photo-controlled release of fipronil from a coumarin triggered precursor.

    Science.gov (United States)

    Gao, Zhenhong; Yuan, Pengtao; Wang, Donghui; Xu, Zhiping; Li, Zhong; Shao, Xusheng

    2017-06-01

    Developing efficient controlled release system of insecticide can facilitate the better use of insecticide. We described here a first example of photo-controlled release of an insecticide by linking fipronil with photoresponsive coumarin covalently. The generated coumarin-fipronil (CF) precursor could undergo cleavage to release free fipronil in the presence of blue light (420nm) or sunlight. Photophysical studies of CF showed that it exhibited strong fluorescence properties. The CF had no obvious activity against mosquito larvae under dark, but it can be activated by light inside the mosquito larvae. The released Fip from CF by blue light irradiation in vitro retained its activity to armyworm (Mythimna separate) with LC50 value of 24.64μmolL(-1). This photocaged molecule provided an alternative delivery method for fipronil. Copyright © 2017. Published by Elsevier Ltd.

  16. Controlled release of simvastatin from biomimetic β-TCP drug delivery system.

    Directory of Open Access Journals (Sweden)

    Joshua Chou

    Full Text Available Simvastatin have been shown to induce bone formation and there is currently a urgent need to develop an appropriate delivery system to sustain the release of the drug to increase therapeutic efficacy whilst reducing side effects. In this study, a novel drug delivery system for simvastatin by means of hydrothermally converting marine exoskeletons to biocompatible beta-tricalcium phosphate was investigated. Furthermore, the release of simvastatin was controlled by the addition of an outer apatite coating layer. The samples were characterized by x-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and mass spectroscopy confirming the conversion process. The in-vitro dissolution of key chemical compositional elements and the release of simvastatin were measured in simulated body fluid solution showing controlled release with reduction of approximately 25% compared with un-coated samples. This study shows the potential applications of marine structures as a drug delivery system for simvastatin.

  17. Rosin and rosin derivatives as hydrophobic matrix materials for controlled release of drugs.

    Science.gov (United States)

    Pathak, Y V; Dorle, A K

    1990-09-01

    The evaluation of rosin, a rosin hard paraffin adduct, and four rosin esters as hydrophobic matrix materials for the controlled release of drugs is reported, using aspirin as a drug model. Aspirin matrix tablets were prepared using a wet granulation (nonaqueous) method, and were evaluated for various pharmaceutical parameters. Dissolution studies in pH 7.2 phosphate buffer showed that all formulations had hardness greater than 6 kg/cm2 and disintegration time greater than 150 min. Release of aspirin from the formulations obeyed a diffusion controlled first order kinetic and linear to the square root of time function. Two of the resin ester formulations had a T80% of more than 4 hr. The results suggest that these esters may find application in the development of sustained release formulations for the local treatment of dental diseases, or--as tablet matrices suitably coated with acid resistant material--in the development of oral sustained release drug delivery systems.

  18. The Preparation of Salbutamol Sulfate Controlled Release TabletsCoated with Cellulose Acetate Aqueous Dispersion

    Institute of Scientific and Technical Information of China (English)

    ZhangFengyu; WuTao; PanWeisan; ChenJimin; ZhangRuhua

    2001-01-01

    In this study, emulsion-solvent evaporation method was applied to prepare the cellulose acetate(CA) aqueous dispersion. Upon the analyzing of the character of the aqueous dispersion, a controlled releaseformulation of salbutamol sulfate coated with cellulose acetate aqueous dispersion was prepared through orthogonalexperiment design. The factors that control the drug release character of the tablets were investigated. The drugrelease mechanism of the formulation was also studied. The experimental results indicated that CA aqueousdispersion had excellent film-forming ability under the effect of plasticizer. The drug release profile of the controlledrelease tablets coated with CA aqueous dispersion exhibited zero-order release character and the drug release rate wasmodulated by the osmotic pressure of the dissolution medium.

  19. Controlled release of bovine serum albumin from hydroxyapatite microspheres for protein delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Boonsongrit, Yaowalak [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Abe, Hiroya [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Cooperative Research Center of Life Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan)], E-mail: h-abe@jwri.osaka-u.ac.jp; Sato, Kazuyoshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Naito, Makio [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Cooperative Research Center of Life Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan); Yoshimura, Masahiro [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ichikawa, Hideki; Fukumori, Yoshinobu [Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan); Cooperative Research Center of Life Sciences, Kobe Gakuin University, Minatojima 1-1-3, Chuo-ku, Kobe 650-8586 (Japan)

    2008-02-25

    Desorption behavior of a model protein (bovine serum albumin, BSA) on commercial hydroxyapatite (HAp) microspheres and its control were investigated for protein delivery system. The desorption behavior related strongly to the phosphate concentration in phosphate buffer solution: the amount of desorbed BSA increased when the phosphate concentration increased. In physiological buffer solution, which contains 10 mM phosphate, the initial burst release of BSA was observed: 70% of BSA was rapidly desorbed after 0.5 h, and 80% after 24 h. In contrast, the extremely low release profile of BSA was observed in distilled water. For the controlled release of BSA in physiological condition, the BSA-loaded HAp microspheres were encapsulated with a biodegradable polymer, poly(lactic acid-co-glycolic acid) (PLGA) by a solid-in oil-in water (S/O/W) emulsion solvent evaporation method. The initial burst was significantly reduced, and the BSA release was remarkably prolonged by the encapsulation.

  20. Preparation of acetylsalicylic acid-acylated chitosan as a novel polymeric drug for drug controlled release.

    Science.gov (United States)

    Liu, Changkun; Wu, Yiguang; Zhao, Liyan; Huang, Xinzheng

    2015-01-01

    The acetylsalicylic acid-acylated chitosan (ASACTS) with high degree of substitution (DS) was successfully synthesized, and characterized with FTIR, (1)H NMR and elemental analysis methods. The optimum synthesis conditions were obtained which gave the highest DS (about 60%) for ASACTS. Its drug release experiments were carried out in simulated gastric and intestine fluids. The results show that the drugs in the form of acetylsalicylic acid (ASA) and salicylic acid (SA) were released in a controlled manner from ASACTS only in simulated gastric fluid. The release profile can be best fitted with logistic and Weibull model. The research results reveal that ASACTS can be a potential polymeric drug for the controlled release of ASA and SA in the targeted gastric environment.

  1. Polysaccharide-based nanocomplexes for co-encapsulation and controlled release of 5-Fluorouracil and Temozolomide.

    Science.gov (United States)

    Di Martino, Antonio; Pavelkova, Alena; Maciulyte, Sandra; Budriene, Saulute; Sedlarik, Vladimir

    2016-09-20

    Polysaccharide-based nanocomplexes, intended for simultaneous encapsulation and controlled release of 5-Fluorouracil (5-FU) and Temozolomide (TMZ) were developed via the complexation method using chitosan, alginic and polygalacturonic acid. Investigation focused on the influence of polysaccharides on the properties of the system and amelioration of the stability of the drugs, in particular TMZ. The dimensions of particles and their ζ-potential were found to range between 100 and 200nm and -25 to +40mV, respectively. Encapsulation efficiency varied from 16% to over 70%, depending on the given system. The influence of pH on the release and co-release of TMZ and 5-FU was evaluated under different pH conditions. The stability of the loaded drug, in particular TMZ, after release was evaluated and confirmed by LC-MS analysis. Results suggested that the amount of loaded drug(s) and the release rate is connected with the weight ratio of polysaccharides and the pH of the media. One-way ANOVA analysis on the obtained data revealed no interference between the drugs during the encapsulation and release process, and in particular no hydrolysis of TMZ occurred suggesting that CS-ALG and CS-PGA would represent interesting carriers for multi-drug controlled release and drugs protection.

  2. A Study on the Control of Pseudoephedrine Hydrochloride Release from Hydroxypropylmethylcellulose Matrices

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H.; Chung, Y.S. [Department of Chemistry, Chungbuk National University, Cheongju (Korea); Bang, M.S. [Department of Industrial Chemistry, Chonan National Technical College, Chonnam (Korea)

    1999-04-01

    Hydroxypropylmethylcelluloses (HPMC) are cellulose ethers which may be used as the basis for hydrophilic matrices for controlled release oral delivery and offer the advantages of being non-toxic and relatively inexpensive. In this work, we designed new drug release system using HPMC as matrix, manufactured by direct compression technology and have investigated the effects of the controlling factors on drug release from a swellable hydrophillic delivery system. It was found that the release rate of the drug decreased with increasing the polymer molecular weight and the polymer content in tablets, and was independent of compaction pressure and pH of dissolution fluids. Especially, the ability of the anionic surfactant, sodium laurylsulfate, to retard the release of pseudoephedrine hydrochloride from HPMC was characterised. With increasing the concentration of the sodium laurylsulfate within the matrix, drug release rate decreased. It is believed that, provided the pseudoephedrine hydrochloride and the sodium laurylsulfate are oppositely charged, they will bind together in situ within the HPMC matrix, leading to reduced drug release rates. 23 refs., 7 figs.

  3. Mucoadhesive Microcapsules of Indomethacin: Evaluation for Controlled Release and Ulcerogenic Activity

    Directory of Open Access Journals (Sweden)

    K.P.R. Chowdary

    2009-07-01

    Full Text Available Mucoadhesive microcapsules of indomethacin were prepared by an emulsification-ionic gelation process employing sodium carboxy methylcellulose, methylcellulose, Carbopol and hydroxy propyl methyl cellulose along with alginate and the microcapsules were evaluated for release kinetics and ulcerogenic activity. The resulting microcapsules were discrete, free flowing, multinucleate, monolithic and spherical. Microencapsulation efficiency was 41-70 % and relatively high with alginate-sodium carboxymethylcellulose. Indomethacin release from these mucoadhesive microcapsules was found to be slow and extended over longer periods of time and depended on the composition of coat and size of the microcapsules. Drug release was diffusion controlled and followed first order kinetics. Alginate-methyl cellulose and alginate-sodium carboxymethylcellulose microcapsules were found suitable for oral controlled release. The microcapsules exhibited good mucoadhesive property in the in vitro wash-off test. Release from some microcapsules fulfilled the official (USP 23 drug release test-2 requirement of indomethacin extended release capsules. A 62-80 % reduction in ulcerogenic activity was observed with these microcapsules when compared to pure drug indomethacin.

  4. Hydrophobic Drug-Loaded PEGylated Magnetic Liposomes for Drug-Controlled Release

    Science.gov (United States)

    Hardiansyah, Andri; Yang, Ming-Chien; Liu, Ting-Yu; Kuo, Chih-Yu; Huang, Li-Ying; Chan, Tzu-Yi

    2017-05-01

    Less targeted and limited solubility of hydrophobic-based drug are one of the serious obstacles in drug delivery system. Thus, new strategies to enhance the solubility of hydrophobic drug and controlled release behaviors would be developed. Herein, curcumin, a model of hydrophobic drug, has been loaded into PEGylated magnetic liposomes as a drug carrier platform for drug controlled release system. Inductive magnetic heating (hyperthermia)-stimulated drug release, in vitro cellular cytotoxicity assay of curcumin-loaded PEGylated magnetic liposomes and cellular internalization-induced by magnetic guidance would be investigated. The resultant of drug carriers could disperse homogeneously in aqueous solution, showing a superparamagnetic characteristic and could inductive magnetic heating with external high-frequency magnetic field (HFMF). In vitro curcumin release studies confirmed that the drug carriers exhibited no significant release at 37 °C, whereas exhibited rapid releasing at 45 °C. However, it would display enormous (three times higher) curcumin releasing under the HFMF exposure, compared with that without HFMF exposure at 45 °C. In vitro cytotoxicity test shows that curcumin-loaded PEGylated magnetic liposomes could efficiently kill MCF-7 cells in parallel with increasing curcumin concentration. Fluorescence microscopy observed that these drug carriers could internalize efficiently into the cellular compartment of MCF-7 cells. Thus, it would be anticipated that the novel hydrophobic drug-loaded PEGylated magnetic liposomes in combination with inductive magnetic heating are promising to apply in the combination of chemotherapy and thermotherapy for cancer therapy.

  5. Age-related iron deposition in the basal ganglia of controls and Alzheimer disease patients quantified using susceptibility weighted imaging.

    Science.gov (United States)

    Wang, Dan; Li, Yan-Ying; Luo, Jian-Hua; Li, Yue-Hua

    2014-01-01

    This study aimed to investigate age-related iron deposition changes in healthy subjects and Alzheimer disease patients using susceptibility weighted imaging. The study recruited 182 people, including 143 healthy volunteers and 39 Alzheimer disease patients. All underwent conventional magnetic resonance imaging and susceptibility weighted imaging sequences. The groups were divided according to age. Phase images were used to investigate iron deposition in the bilateral head of the caudate nucleus, globus pallidus and putamen, and the angle radian value was calculated. We hypothesized that age-related iron deposition changes may be different between Alzheimer disease patients and controls of the same age, and that susceptibility weighted imaging would be a more sensitive method of iron deposition quantification. The results revealed that iron deposition in the globus pallidus increased with age, up to 40 years. In the head of the caudate nucleus, iron deposition peaked at 60 years. There was a general increasing trend with age in the putamen, up to 50-70 years old. There was significant difference between the control and Alzheimer disease groups in the bilateral globus pallidus in both the 60-70 and 70-80 year old group comparisons. In conclusion, iron deposition increased with age in the globus pallidus, the head of the caudate nucleus and putamen, reaching a plateau at different ages. Furthermore, comparisons between the control and Alzheimer disease group revealed that iron deposition changes were more easily detected in the globus pallidus. Crown Copyright © 2014. Published by Elsevier Ireland Ltd. All rights reserved.

  6. PECTIN MICROGELS CONTAINING SYNTHETIC POLYMERS BASED ON NANOCAPSULES FOR THE CONTROLLED RELEASE OF INDOMETHACIN

    Directory of Open Access Journals (Sweden)

    Mihaela HOLBAN

    2015-12-01

    Full Text Available Nanocapsule-based Eudragit RS100 and Eudragit E100 containing indomethacin have been prepared. The nanosuspensions have been included into pectin microgels of different polysaccharide concentrations, 28-61 µm-ranged polymer microgels with size and size polydispersity highly depending on the pectin amount being thus obtained. Study of the drug release revealed that indomethacin was released at a slower and more controlled rate from the microgels containing nanocapsules than from the empty pectin microgels. Also, the rate of released indomethacin increased with the augmentation of pectin amount into the microgels.

  7. A study on controlled cooling process for making bainitic ductile iron

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    In the present research, TTT curve of bainitic ductile iron under the condition of controlled cooling was generated. The cooling rate of grinding ball and its temperature distribution were also measured at the same time. It can be concluded that the bainitic zone of TTT curve is separated from the pearlitic zone. As compared to the water-quenching condition, more even cooling rate and temperature distribution can be achieved in the controlled cooling process. The controlled cooling can keep away from pearlitic zone in the high temperature cooling stage and produce similar results to the process of traditional isothermal cooling with a low cooling rate in the low temperature cooling stage.

  8. Controlled oxygen release from pyridone endoperoxides promotes cell survival under anoxic conditions

    OpenAIRE

    Benz, Sebastian; Noetzli, Sarah; Siegel, Jay; Eberli, Daniel; Jessen, Henning Jacob

    2013-01-01

    In tissue engineering, survival of larger constructs remains challenging due to limited supply with oxygen caused by a lack of early vascularization. Controlled release of oxygen from small organic molecules represents a possible strategy to prevent cell death under anoxic conditions. A comprehensive study of methylated pyridone-derived endoperoxides has led to the development of water-soluble molecules that undergo retro Diels-Alder reactions in aqueous environment releasing oxygen in high y...

  9. Design and evaluation of controlled release mucoadhesive microspheres of amoxicillin for anti Helicobacter pylori therapy

    OpenAIRE

    N Venkateswaramurthy; Sambathkumar, R.; Perumal, P.

    2011-01-01

    The aim of this study was to develop controlled release mucoadhesive microspheres of amoxicillin trihydrate for the treatment of peptic ulcer disease caused by Helicobacter pylori (H. pylori). Microspheres were prepared by solvent evaporation technique using carbopol 974P, hydroxypropyl methyl cellulose K4M (HPMC K4M) and Eudragit RS 100. The prepared microspheres were subjected to evaluation for particle size, incorporation efficiency, in vitro mucoadhesion and in vitro drug release characte...

  10. Effect Of Iron Supplementation In Breastfed Infants: A Randomized Controlled Study

    Directory of Open Access Journals (Sweden)

    seyma Kayali

    2016-09-01

    Conclusion Consumption of iron rich complementary foods together with routine iron supplementation of term, breast-fed infants from 4 months of age can improve their iron status. Receiving sufficient iron in diet is an effective way prevent iron-deficiency anemia. [J Contemp Med 2016; 6(3.000: 165-172

  11. Controlled release behaviour and antibacterial effects of antibiotic-loaded titania nanotubes.

    Science.gov (United States)

    Feng, Wenchao; Geng, Zhen; Li, Zhaoyang; Cui, Zhenduo; Zhu, Shengli; Liang, Yanqin; Liu, Yunde; Wang, Renfeng; Yang, Xianjin

    2016-05-01

    Bacterial infections have been identified as the main cause of orthopaedic implant failure. Owing to their high antibiotic delivery efficiency, titania nanotubes loaded with antibiotics constitute one of the most promising strategies for suppressing bacterial infections. However, it is difficult to control the drug-release behaviour of such nanotubes. Although sealing the nanotubes with a polymer solution provides sustained release effects to a certain extent, it inevitably influences their initial antibacterial activity. This study reports on the controlled release of gentamicin sulphate (GS) from titania nanotube surfaces whereby their initial antibacterial activity remains unaffected. Titania nanotubes were fabricated via electrochemical anodization and loaded with GS through physical adsorption. Experimental results showed that this loading method is feasible and efficient. The GS-loaded titania nanotubes were further covered by a thin film comprising a mixture of GS and chitosan (GSCH). The release kinetics confirmed that the drug release could be controlled by this thin film. Moreover, such a film was shown to not only inhibit initial bacterial adherence owing to its strong antibacterial properties but also enhance cell viability. Thus, GS-loaded titania nanotubes coated with GSCH have considerable potential as biomaterials for preventing initial release and peri-implant infection in the field of orthopaedics.

  12. Controlled release by novel lysostaphin-loaded hydroxyapatite/chitosan composites.

    Science.gov (United States)

    Wang, Jin-Cheng; Xue, Bai; Ge, Kui-Kui; Wang, Yi-Han; Li, Guo-Dong; Huang, Qing-Shan

    2014-09-01

    Lysostaphin is highly effective on eliminating methicillin resistant Staphylococcus aureus (MRSA). In order to achieve controlled release of lysostaphin, a biocompatible drug carrier is needed. Hydroxyapatite/chitosan (HA/CS) composites were chosen to carry lysostaphin and sample composites with different weight ratios of HA to CS, including 80/20, 70/30, 60/40, and 40/60, were prepared. Multiple analyses were performed to determine the structural and physicochemical properties of the composites, including scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. We immersed HA/CS composites loaded with 1 wt% lysostaphin to test in vitro release activity and cultured MC3T3-E1 cells to carry out biocompatibility test. The result of the release behavior of the composites revealed that the controlled release of lysostaphin from 60/40 HA/CS composites was the highest release rate of (87.4 ± 2.8)%, which lasted for 120 hours. In biocompatibility testing, MC3T3-E1 cells were able to proliferate on the surface of these composites, and the extract liquid from the composites could increase the growth of the cells. These results demonstrate the controlled release of lysostaphin from HA/CS composites and their biocompatibility, suggesting the potential application of these composites to bone injury and infection applications.

  13. Improving the controlled release of water-insoluble emodin from amino-functionalized mesoporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yunqiang; Wang Chunfeng [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry, Shandong Polytechnic University, Jinan 250353, Shandong (China); Zhou Guowei, E-mail: guoweizhou@hotmail.com [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry, Shandong Polytechnic University, Jinan 250353, Shandong (China); Wu Yue; Chen Jing [Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry, Shandong Polytechnic University, Jinan 250353, Shandong (China)

    2012-06-15

    Several types of amino-functionalized mesoporous silica, including F5-SBA-15, F10-SBA-15, and F15-SBA-15 were prepared through co-condensation of tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES) in varying molar ratios (5 mol%, 10 mol%, and 15 mol%) via a hydrothermal process. The materials obtained were characterized by means of small-angle X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, N{sub 2} adsorption-desorption, Fourier transformed infrared spectra, and X-ray photoelectron spectroscopy. Increasing APTES molar ratios decreased the degree of orderliness of the functionalized mesoporous silica. Pure and amino-functionalized SBA-15 samples were employed as supports for the controlled release of water-insoluble drug emodin. Loading experiments showed that drug loading capacities mainly depended on the surface areas and pore diameters of the carriers. Controlled release profiles of emodin-loaded samples were studied in phosphate buffered saline (PBS, pH 7.4), and results indicated that the emodin release rate could be controlled by surface amino-functionalized carriers. Emodin loaded on functionalized mesoporous supports exhibited a lower release rate than that of loaded on pure SBA-15, emodin loaded on F10-SBA-15 showed the smallest release amount (71.74 wt%) after stirring in PBS for 60 h. Findings suggest that functionalized mesoporous SBA-15 is a promising carrier for achieving prolonged release time periods.

  14. Formulation and evaluation of controlled release floating microspheres of tolperisone hydrochloride

    Directory of Open Access Journals (Sweden)

    Pooja Jani

    2012-01-01

    Full Text Available Main aim of this study was to develop controlled release (CR floating multiparticulate drug delivery system of tolperisone hydrochloride. Microspheres were prepared by nonaqueous solvent evaporation technique consisting of porous calcium silicate (Florite or FLR as porous carrier, tolperisone hydrochloride (API, Ethyl cellulose (EC, and HPMC 15 cPs as rate controlling polymers. 2 3 full factorial design was applied for optimization of formulation. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in vitro floating behavior, entrapment efficiency, and in vitro drug release were studied. The size of microspheres was varied from 300 to 500 μm. The microspheres were found to be highly porous and regular in shape. All the formulations showed excellent flow properties. The percentage entrapment efficiency of all batches was greater than 80%. The percentage buoyancy varied from 85% to 98% at the end of 12 h. The release rate was determined in simulated gastric fluids. The formulation demonstrated favorable in vitro floating and release characteristics. Different kinetic models were applied to study the release mechanism. All formulations followed Higuchi model, which indicates the diffusion control release of water soluble drug from polymer matrix. Multiple regression analysis was applied for study of the effect of independent variables on the dependent variables.

  15. Chitosan-polycarbophil complexes in swellable matrix systems for controlled drug release.

    Science.gov (United States)

    Lu, Z; Chen, W; Hamman, J H

    2007-10-01

    A prerequisite for progress in the design of novel drug delivery systems is the development of excipients that are capable of fulfilling multifunctional roles such as controlling the release of the drug according to the therapeutic needs. Although several polymers have been utilised in the development of specialised drug delivery systems, their scope in dosage form design can be enlarged through combining different polymers. When a polymer is cross-linked or complexed with an oppositely charged polyelectrolyte, a three-dimensional network is formed in which the drug can be incorporated to control its release. The swelling properties and release kinetics of two model drugs with different water solubilities (i.e. diltiazem and ibuprofen) from monolithic matrix tablets consisting of an interpolyelectrolyte complex between chitosan and polycarbophil are reported. Matrix tablets consisting of this polymeric complex without drug or excipients exhibited extremely high swelling properties that are completely reversible upon drying. The drug release from matrix systems with different formulations depended on the concentration of the chitosan-polycarbophil interpolyelectrolyte complex and approached zero order release kinetics for both model drugs. The chitosan-polycarbophil interpolyelectrolyte complex has demonstrated a high potential as an excipient for the production of swellable matrix systems with controlled drug release properties.

  16. Selective translational control of the Alzheimer amyloid precursor protein transcript by iron regulatory protein-1.

    Science.gov (United States)

    Cho, Hyun-Hee; Cahill, Catherine M; Vanderburg, Charles R; Scherzer, Clemens R; Wang, Bin; Huang, Xudong; Rogers, Jack T

    2010-10-08

    Iron influx increases the translation of the Alzheimer amyloid precursor protein (APP) via an iron-responsive element (IRE) RNA stem loop in its 5'-untranslated region. Equal modulated interaction of the iron regulatory proteins (IRP1 and IRP2) with canonical IREs controls iron-dependent translation of the ferritin subunits. However, our immunoprecipitation RT-PCR and RNA binding experiments demonstrated that IRP1, but not IRP2, selectively bound the APP IRE in human neural cells. This selective IRP1 interaction pattern was evident in human brain and blood tissue from normal and Alzheimer disease patients. We computer-predicted an optimal novel RNA stem loop structure for the human, rhesus monkey, and mouse APP IREs with reference to the canonical ferritin IREs but also the IREs encoded by erythroid heme biosynthetic aminolevulinate synthase and Hif-2α mRNAs, which preferentially bind IRP1. Selective 2'-hydroxyl acylation analyzed by primer extension analysis was consistent with a 13-base single-stranded terminal loop and a conserved GC-rich stem. Biotinylated RNA probes deleted of the conserved CAGA motif in the terminal loop did not bind to IRP1 relative to wild type probes and could no longer base pair to form a predicted AGA triloop. An AGU pseudo-triloop is key for IRP1 binding to the canonical ferritin IREs. RNA probes encoding the APP IRE stem loop exhibited the same high affinity binding to rhIRP1 as occurs for the H-ferritin IRE (35 pm). Intracellular iron chelation increased binding of IRP1 to the APP IRE, decreasing intracellular APP expression in SH-SY5Y cells. Functionally, shRNA knockdown of IRP1 caused increased expression of neural APP consistent with IRP1-APP IRE-driven translation.

  17. Controlled release from triple layer, donut-shaped tablets with enteric polymers.

    Science.gov (United States)

    Kim, Cherng-ju

    2005-10-22

    The purpose of this research was to evaluate triple layer, donut-shaped tablets (TLDSTs) for extended release dosage forms. TLDSTs were prepared by layering 3 powders sequentially after pressing them with a punch. The core tablet consisted of enteric polymers, mainly hydroxypropyl methylcellulose acetate succinate, and the bottom and top layers were made of a water-insoluble polymer, ethyl cellulose. Drug release kinetics were dependent on the pH of the dissolution medium and the drug properties, such as solubility, salt forms of weak acid and weak base drugs, and drug loading. At a 10% drug loading level, all drugs, regardless of their type or solubility, yielded the same release profiles within an acceptable level of experimental error. As drug loading increased from 10% to 30%, the drug release rate of neutral drugs increased for all except sulfathiazole, which retained the same kinetics as at 10% loading. HCl salts of weak base drugs had much slower release rates than did those of neutral drugs (eg, theophylline) as drug loading increased. The release of labetalol HCl retarded as drug loading increased from 10% to 30%. On the other hand, Na salts of weak acid drugs had much higher release rates than did those of neutral drugs (eg, theophylline). Drug release kinetics were governed by the ionization/erosion process with slight drug diffusion, observing no perfect straight line. A mathematical expression for drug release kinetics (erosion-controlled system) of TLDSTs is presented. In summary, a TLDST is a good design to obtain zero-order or nearly zero-order release kinetics for a wide range of drug solubilities.

  18. Detecting Organic Compounds Released from Iron Oxidizing Bacteria using Sample Analysis at Mars (SAM)-like Instrument Protocols

    Science.gov (United States)

    Glavin, D. P.; Popa, R.; Martin, M. G.; Freissinet, C.; Fisk, M. R.; Dworkin, J. P.; Mahaffy, P. R.

    2012-12-01

    Mars is a planet of great interest for Astrobiology since its past environmental conditions are thought to have been favourable for the emergence life. At present, the Red Planet is extremely cold and dry and the surface is exposed to intense UV and ionizing radiation, conditions generally considered to be incompatible with life as we know it on Earth. It was proposed that the shallow subsurface of Mars, where temperatures can be above freezing and liquid water can exist on rock surfaces, could harbor chemolithoautotrophic bacteria such as the iron oxidizing microorganism Pseudomonas sp. HerB [Popa et al. 2012]. The Mars Science Laboratory (MSL) mission will provide the next opportunity to carry out in situ measurements for organic compounds of possible biological origin on Mars. One instrument onboard MSL, called the Sample Analysis at Mars (SAM) instrument suite, will carry out a broad and sensitive search for organic compounds in surface samples using either high temperature pyrolysis or chemical extraction followed by gas chromatography mass spectrometry [Mahaffy et al. 2012]. We present gas chromatograph mass spectrometer (GC/MS) data on crushed olivine rock powders that have been inoculated with Pseudomonas sp. HerB at different concentrations ranging from ~102 to 107 cells per gram. The inoculated olivine samples were heated under helium carrier gas flow at 500°C and the pyrolysis products concentrated using a SAM-like hydrocarbon trap set at -20°C followed by trap heating and analysis by GC/MS. In addition, the samples were also extracted using a low temperature "one-pot" chemical extraction technique using N-methyl, N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) as the silylating agent prior to GC/MS analysis [Stalport et al. 2012]. We identified several aldehydes, thiols, and alkene nitriles after pyrolysis GC/MS analysis of the bacteria that were not found in the olivine control samples that had not been inoculated with bacteria. The

  19. Alzheimer's disease therapeutics targeted to the control of amyloid precursor protein translation: maintenance of brain iron homeostasis.

    Science.gov (United States)

    Bandyopadhyay, Sanghamitra; Rogers, Jack T

    2014-04-15

    The neurotoxicity of amyloid beta (Aβ), a major cleavage product of the amyloid precursor protein (APP), is enhanced by iron, as found in the amyloid plaques of Alzheimer's disease (AD) patients. By contrast, the long-known neuroprotective activity of APP is evident after α-secretase cleavage of the precursor to release sAPPα, and depends on the iron export actions of APP itself. The latter underlie its neurotrophic and protective effects in facilitating the homeostatic actions of ferroportin mediated-iron export. Thus APP-dependent iron export may alleviate oxidative stress by minimizing labile iron thus protecting neurons from iron overload during stroke and hemorrhage. Consistent with this, altered phosphorylation of iron-regulatory protein-1 (IRP1) and its signaling processes play a critical role in modulating APP translation via the 5' untranslated region (5'UTR) of its transcript. The APP 5'UTR region encodes a functional iron-responsive element (IRE) RNA stem loop that represents a potential target for modulating APP production. Targeted regulation of APP gene expression via the modulation of 5'UTR sequence function represents a novel approach for the potential treatment of AD since altering APP translation can be used to improve both the protective brain iron balance and provide anti-amyloid efficacy. Approved drugs including paroxetine and desferrioxamine and several novel compounds have been identified that suppress abnormal metal-promoted Aβ accumulation with a subset of these acting via APP 5'UTR-dependent mechanisms to modulate APP translation and cleavage to generate the non-toxic sAPPα.

  20. Ferrous Sulfate (Iron)

    Science.gov (United States)

    Ferrous sulfate provides the iron needed by the body to produce red blood cells. It is used ... Ferrous sulfate comes as regular, coated, and extended-release (long-acting) tablets; regular and extended-release capsules; ...

  1. 硫酸根浓度突变对给水管网铁释放的影响%Effect of sulphate concentration change on iron release in drinking water distribution systems

    Institute of Scientific and Technical Information of China (English)

    米子龙; 张晓健; 陆品品; 陈超; 汪隽; 顾军农

    2013-01-01

    This study investigated the effect of sulphate concentration changes on the iron release in a drinking water distribution system caused frequently switching of the water source.The rates of iron release from corrosion scale for different water sources were analyzed with pipe section reactors designed to simulate the distribution system flow mode.The results showed that the sulphate concentration was the dominant factor that led to red water.The iron release rate from the corrosion scale correlated well with the sulphate concentration with a sulphate concentration increase from 25 mg/L to 180 mg/L accompanied by a Larson ratio increase from about 0.35 to 1.40.The turbidity in the pipe section reactors increased 6 NTU after 8 h,the color increased 50 degrees and the iron release rate increased 2.00 mg/(m2 · h).These results indicate that the sulphate concentration should be lower than 75 mg/L and the Larson Ratio should be controlled to less than 0.70 for the water quality in the distribution system to meet the Chinese drinking water quality standard.Based on these results,t was suggested to be and controlled less than 0.70 in order that in meet the standard of drinking in China.%针对水源频繁切换造成原水水质硫酸根质量浓度突变对给水管网铁释放的影响开展试验研究.选取北京市城区3个不同地区的管段,设计并制作管段模拟反应器,比较分析不同硫酸根质量浓度水质条件下、不同地区管段的铁释放情况.结果表明:硫酸根质量浓度的大幅增加可导致黄水问题.给水管网铁释放量与硫酸根质量浓度具有显著相关性,当硫酸根质量浓度从25 mg/L增加到180 mg/L,相应的Larson指数从0.35增加到1.40时,8h滞留时间后管段出水浊度、色度的最大增加值分别约为6 NTU和50度,总铁释放速率最大增加约2.00 mg/(m2·h).由此,确定了水源切换条件下,硫酸报和Larson指数对管垢铁释放的控制指标:硫酸根质量浓度<75 mg

  2. Diffusion of Oligonucleotides from within Iron-Crosslinked Polyelectrolyte-Modified Alginate Beads: A Model System for Drug Release

    CERN Document Server

    Privman, Vladimir; Luz, Roberto A S; Guz, Nataliia; Glasser, M Lawrence; Katz, Evgeny

    2016-01-01

    We developed and experimentally verified an analytical model to describe diffusion of oligonucleotides from stable hydrogel beads. The synthesized alginate beads are Fe3+-cross-linked as well as polyelectrolyte-doped for uniformity and stability at physiological pH. Data on diffusion of oligonucleotides from inside the beads provide physical insights into the volume nature of the immobilization of a fraction of oligonucleotides due to polyelectrolyte cross-linking, i.e., the absence of the surface-layer barrier in this case. Furthermore, our results suggest a new simple approach to measuring the diffusion coefficient of the mobile oligonucleotide molecules inside hydrogel. The considered alginate beads provide a model for a well-defined component in drug release systems and for the oligonucleotide-release transduction steps in drug-delivering and biocomputing applications. This is illustrated by destabilizing the beads with citrate that induces full oligonucleotide release with non-diffusional kinetics.

  3. Reducing Runoff Loss of Applied Nutrients in Oil Palm Cultivation Using Controlled-Release Fertilizers

    Directory of Open Access Journals (Sweden)

    A. Bah

    2014-01-01

    Full Text Available Controlled-release fertilizers are expected to minimize nutrient loss from crop fields due to their potential to supply plant-available nutrients in synchrony with crop requirements. The evaluation of the efficiency of these fertilizers in tropical oil palm agroecological conditions is not yet fully explored. In this study, a one-year field trial was conducted to determine the impact of fertilization with water soluble conventional mixture and controlled-release fertilizers on runoff loss of nutrients from an immature oil palm field. Soil and nutrient loss were monitored for one year in 2012/2013 under erosion plots of 16 m2 on 10% slope gradient. Mean sediments concentration in runoff amounted to about 6.41 t ha−1. Conventional mixture fertilizer posed the greatest risk of nutrient loss in runoff following fertilization due to elevated nitrogen (6.97%, potassium (13.37%, and magnesium (14.76% as percentage of applied nutrients. In contrast, this risk decreased with the application of controlled-release fertilizers, representing 0.75–2.44% N, 3.55–5.09% K, and 4.35–5.43% Mg loss. Meanwhile, nutrient loss via eroded sediments was minimal compared with loss through runoff. This research demonstrates that the addition of controlled-release fertilizers reduced the runoff risks of nutrient loss possibly due to their slow-release properties.

  4. Ibuprofen-loaded poly(lactic-co-glycolic acid films for controlled drug release

    Directory of Open Access Journals (Sweden)

    Pang JM

    2011-04-01

    Full Text Available Jianmei Pang1, Yuxia Luan1, Feifei Li1, Xiaoqing Cai1, Jimin Du2, Zhonghao Li31School of Pharmaceutical Science, Shandong University, Jinan, Shandong Province, PR China; 2School of Chemistry and Chemical Engineering, Anyang Normal University, Henan Province, PR China; 3School of Materials Science and Engineering, Shandong University, Jinan, Shandong Province, PR ChinaAbstract: Ibuprofen- (IBU loaded biocompatible poly(lactic-co-glycolic acid (PLGA films were prepared by spreading polymer/ibuprofen solution on the nonsolvent surface. By controlling the weight ratio of drug and polymer, different drug loading polymer films can be obtained. The synthesized ibuprofen-loaded PLGA films were characterized with scanning electron microscopy, powder X-ray diffraction, and differential scanning calorimetry. The drug release behavior of the as-prepared IBU-loaded PLGA films was studied to reveal their potential application in drug delivery systems. The results show the feasibility of the as-obtained films for controlling drug release. Furthermore, the drug release rate of the film could be controlled by the drug loading content and the release medium. The development of a biodegradable ibuprofen system, based on films, should be of great interest in drug delivery systems.Keywords: ibuprofen, controlled release, poly(lactic-co-glycolic acid, films

  5. Application of photoremovable protecting group for controlled release of plant growth regulators by sunlight.

    Science.gov (United States)

    Atta, Sanghamitra; Ikbal, Mohammed; Kumar, Ashutosh; Pradeep Singh, N D

    2012-06-01

    We report a novel technique for controlled release of plant growth regulators (PGRs) by sunlight using photoremovable protecting group (PRPG) as a delivery device. In the present work, carboxyl-containing PGRs of the auxin group [indoleacetic acid (IAA) and naphthoxyacetic acid (NOAA)] were chemically caged using PRPGs of coumarin derivatives. Photophysical studies showed that caged PGRs exhibited good fluorescence properties. Irradiation of caged PGRs by sunlight in both aqueous ethanol and soil media resulted in controlled release of PGRs. The results of the bioactivity experiments indicated that caged PGRs showed better enhancement in the root and shoot length growth of Cicer arietinum compared to PGRs after 10days of sunlight exposure. Our results indicated that use of PRPG as a delivery device for controlled release of PGRs by sunlight in soil holds great interest for field application since it can overcome the rapid loss of PGRs in environmental conditions.

  6. Laponite-based nanohybrid for enhanced solubility and controlled release of itraconazole.

    Science.gov (United States)

    Jung, Hyun; Kim, Hyun-Mi; Choy, Young Bin; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-02-12

    Laponite, a form of layered aluminosilicates, and itraconazole, a water insoluble drug, were hybridized through an interfacial reaction at the boundary between water and a water-immiscible liquid. The reaction was carried out under a controlled pH to maintain both physical and chemical stability of the drug. The X-ray diffraction patterns and spectroscopic analyses indicated that itraconazole was intercalated into the interlayer space of clay with a lateral monolayer structure. No significant chemical structural change of itraconazole was seen through the formation of the hybrid. The hybrid system exhibited enhanced solubility and controlled release of itraconazole. The released amount of itraconazole could be controlled in the range from 18 to 75%, depending on the kinds of cations in the release media.

  7. Extracellular control of intracellular drug release for enhanced safety of anti-cancer chemotherapy

    Science.gov (United States)

    Zhu, Qian; Qi, Haixia; Long, Ziyan; Liu, Shang; Huang, Zhen; Zhang, Junfeng; Wang, Chunming; Dong, Lei

    2016-06-01

    The difficulty of controlling drug release at an intracellular level remains a key challenge for maximising drug safety and efficacy. We demonstrate herein a new, efficient and convenient approach to extracellularly control the intracellular release of doxorubicin (DOX), by designing a delivery system that harnesses the interactions between the system and a particular set of cellular machinery. By simply adding a small-molecule chemical into the cell medium, we could lower the release rate of DOX in the cytosol, and thereby increase its accumulation in the nuclei while decreasing its presence at mitochondria. Delivery of DOX with this system effectively prevented DOX-induced mitochondria damage that is the main mechanism of its toxicity, while exerting the maximum efficacy of this anti-cancer chemotherapeutic agent. The present study sheds light on the design of drug delivery systems for extracellular control of intracellular drug delivery, with immediate therapeutic implications.

  8. FORMULATION AND EVALUATION OF METOPROLOL SUCCINATE CONTROLLED RELEASE TABLETS USING NATURAL AND SYNTHETIC POLYMER

    Directory of Open Access Journals (Sweden)

    A. Sathyaraj

    2012-01-01

    Full Text Available The objective of the present study to develop controlled release tablets of Metoprolol succinate using Natural polymer, guar gum and synthetic polymer, carbopol as a rate controlling polymers.. It was also desired to study the effect of polymer concentration. Metoprolol succinate, β1- selective adrenergic receptor- blocking agent used in the management of hypertension, angina pectoris, cardiac arrthymias, myocardial infarction, heart failure, hyperthyroidism and in the prophylactic treatment of migraine. The half-life of drug is relatively short approximately 4-6 hrs and in normal course of therapy drug administration is required every 4-6 hrs, thus warrants the use of controlled release formulation for prolong action and to improve patient compliance. In the present investigation Natural polymer, guar gum and synthetic polymer, carbopol have been selected as matrix forming materials for the drug. The formulations are made by employing the conventional wet granulation method, to achieve prolonged release of medicaments.

  9. Controlled Release of Ciprofloxacin from Core-Shell Nanofibers with Monolithic or Blended Core.

    Science.gov (United States)

    Zupančič, Špela; Sinha-Ray, Sumit; Sinha-Ray, Suman; Kristl, Julijana; Yarin, Alexander L

    2016-04-04

    Sustained controlled drug release is one of the prominent contributions for more successful treatment outcomes in the case of several diseases. However, the incorporation of hydrophilic drugs into nanofibers, a promising novel delivery system, and achieving a long-term sustained release still pose a challenging task. In this work we demonstrated a robust method of avoiding burst release of drugs and achieving a sustained drug release from 2 to 4 weeks using core-shell nanofibers with poly(methyl methacrylate) (PMMA) shell and monolithic poly(vinyl alcohol) (PVA) core or a novel type of core-shell nanofibers with blended (PVA and PMMA) core loaded with ciprofloxacin hydrochloride (CIP). It is also shown that, for core-shell nanofibers with monolithic core, drug release can be manipulated by varying flow rate of the core PVA solution, whereas for core-shell nanofibers with blended core, drug release can be manipulated by varying the ratios between PMMA and PVA in the core. During coaxial electrospinning, when the solvent from the core evaporates in concert with the solvent from the shell, the interconnected pores spanning the core and the shell are formed. The release process is found to be desorption-limited and agrees with the two-stage desorption model. Ciprofloxacin-loaded nanofiber mats developed in the present work could be potentially used as local drug delivery systems for treatment of several medical conditions, including periodontal disease and skin, bone, and joint infections.

  10. Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP).

    Science.gov (United States)

    Allison, David B; Gadde, Kishore M; Garvey, William Timothy; Peterson, Craig A; Schwiers, Michael L; Najarian, Thomas; Tam, Peter Y; Troupin, Barbara; Day, Wesley W

    2012-02-01

    A 56-week randomized controlled trial was conducted to evaluate safety and efficacy of a controlled-release combination of phentermine and topiramate (PHEN/TPM CR) for weight loss (WL) and metabolic improvements. Men and women with class II and III obesity (BMI ≥ 35 kg/m(2)) were randomized to placebo, PHEN/TPM CR 3.75/23 mg, or PHEN/TPM CR 15/92 mg, added to a reduced-energy diet. Primary end points were percent WL and proportions of patients achieving 5% WL. Secondary end points included waist circumference (WC), systolic and diastolic blood pressure (BP), fasting glucose, and lipid measures. In the primary analysis (randomized patients with at least one postbaseline weight measurement who took at least one dose of assigned drug or placebo), patients in the placebo, 3.75/23, and 15/92 groups lost 1.6%, 5.1%, and 10.9% of baseline body weight (BW), respectively, at 56 weeks (P fasting glucose, triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL). The most common adverse events were paresthesia, dry mouth, constipation, dysgeusia, and insomnia. Dropout rate from the study was 47.1% for placebo patients, 39.0% for 3.75/23 patients, and 33.6% of 15/92 patients. PHEN/TPM CR demonstrated dose-dependent effects on weight and metabolic variables in the direction expected to be beneficial with no evidence of serious adverse events induced by treatment.

  11. Intervenções nutricionais na anemia ferropriva Nutritional strategies for controlling iron deficiency anemia

    Directory of Open Access Journals (Sweden)

    Marly A. Cardoso

    1994-06-01

    Full Text Available O objetivo deste estudo de revisão bibliográfica é fornecer subsídios para o planejamento e avaliação de medidas de combate à anemia ferropriva. A necessidade de intervenções para o controle da prevalência da anemia ferropriva deve ser determinada pela magnitude da defi ciência nutricional e pelo conhecimento de seus efeitos na qualidade de vida, morbidade e mortalidade. A abordagem mais usual é fornecer ferro suplementar a gestantes, nutrizes e lactentes em programas de assistência primária à saúde, reconhecidamente os grupos de maior vulnerabilidade. A fortificação de alimentos e orientações sobre modificações da dieta representam medidas complementares e devem ser incrementadas.This review was elaborated in order to contribute to the planning of strategies for controlling iron deficiency anemia in developing countries. The need for intervention should be determined by the degree of iron deficiency in the individual group and knowledge of its effects on quality of life, morbidity, and mortality. The most frequent approach is to provide iron supplementation during pregnancy, lactation, and early childhood as a basic primary healthcare measure. Fortification and dietary modification are complementary approaches, and should be developed.

  12. Controlled release of NELL-1 protein from chitosan/hydroxyapatite-modified TCP particles.

    Science.gov (United States)

    Zhang, Yulong; Dong, Rui; Park, Yujin; Bohner, Marc; Zhang, Xinli; Ting, Kang; Soo, Chia; Wu, Benjamin M

    2016-09-10

    NEL-like molecule-1 (NELL-1) is a novel osteogenic protein that showing high specificity to osteochondral cells. It was widely used in bone regeneration research by loading onto carriers such as tricalcium phosphate (TCP) particles. However, there has been little research on protein controlled release from this material and its potential application. In this study, TCP was first modified with a hydroxyapatite coating followed by a chitosan coating to prepare chitosan/hydroxyapatite-coated TCP particles (Chi/HA-TCP). The preparation was characterized by SEM, EDX, FTIR, XRD, FM and Zeta potential measurements. The NELL-1 loaded Chi/HA-TCP particles and the release kinetics were investigated in vitro. It was observed that the Chi/HA-TCP particles prepared with the 0.3% (wt/wt) chitosan solution were able to successfully control the release of NELL-1 and maintain a slow, steady release for up to 28 days. Furthermore, more than 78% of the loaded protein's bioactivity was preserved in Chi/HA-TCP particles over the period of the investigation, which was significantly higher than that of the protein released from hydroxyapatite coated TCP (HA-TCP) particles. Collectively, this study suggests that the osteogenic protein NELL-1 showed a sustained release pattern after being encapsulated into the modified Chi/HA-TCP particles, and the NELL-1 integrated composite of Chi/HA-TCP showed a potential to function as a protein delivery carrier and as an improved bone matrix for use in bone regeneration research.

  13. Synthetic Zeolites as Controlled-Release Delivery Systems for Anti-Inflammatory Drugs.

    Science.gov (United States)

    Khodaverdi, Elham; Soleimani, Hossein Ali; Mohammadpour, Fatemeh; Hadizadeh, Farzin

    2016-06-01

    Scientists have always been trying to use artificial zeolites to make modified-release drug delivery systems in the gastrointestinal tract. An ideal carrier should have the capability to release the drug in the intestine, which is the main area of absorption. Zeolites are mineral aluminosilicate compounds with regular structure and huge porosity, which are available in natural and artificial forms. In this study, soaking, filtration and solvent evaporation methods were used to load the drugs after activation of the zeolites. Weight measurement, spectroscopy FTIR, thermogravimetry and scanning electronic microscope were used to determine drug loading on the systems. Finally, consideration of drug release was made in a simulated gastric fluid and a simulated intestinal fluid for all matrixes (zeolites containing drugs) and drugs without zeolites. Diclofenac sodium (D) and piroxicam (P) were used as the drug models, and zeolites X and Y as the carriers. Drug loading percentage showed that over 90% of drugs were loaded on zeolites. Dissolution tests in stomach pH environment showed that the control samples (drug without zeolite) released considerable amount of drugs (about 90%) within first 15 min when it was about 10-20% for the matrixes. These results are favorable as NSAIDs irritate the stomach wall and it is ideal not to release much drugs in the stomach. Furthermore, release rate of drugs from matrixes has shown slower rate in comparison with control samples in intestine pH environment.

  14. Zinc polycarboxylate dental cement for the controlled release of an active organic substance: proof of concept.

    Science.gov (United States)

    Ali, Mohammad Naseem; Edwards, Mark; Nicholson, John W

    2010-04-01

    The potential of employing zinc polycarboxylate dental cement as a controlled release material has been studied. Benzalkonium chloride was used as the active ingredient, and incorporated at concentrations of 1, 2 and 3% by mass within the cement. At these levels, there was no observable effect on the speed of setting. Release was followed using an ion-selective electrode to determine changes in chloride ion concentration with time. This technique showed that the additive was released when the cured cement was placed in water, with release occurring by a diffusion mechanism for the first 3 h, but continuing beyond that for up to 1 week. Diffusion coefficients were in the range 5.62 x 10(-6) cm(2) s(-1) (for 1% concentration) to 10.90 x 10(-6) cm(2) s(-1) (for 3% concentration). Up to 3% of the total loading of benzalkonium chloride was released from the zinc polycarboxylate after a week, which is similar to that found in previous studies with glass-ionomer cement. It is concluded that zinc polycarboxylate cement is capable of acting as a useful material for the controlled release of active organic compounds.

  15. Synthesis and characterization of a HAp-based biomarker with controlled drug release for breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    González, Maykel [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico); Merino, Ulises [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico); University of the Valley of Mexico (UVM), Boulevard Villas del Mesón 1000, Juriquilla, Santiago de Querétaro, Querétaro 76320 (Mexico); Vargas, Susana [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico); Quintanilla, Francisco [University of the Valley of Mexico (UVM), Boulevard Villas del Mesón 1000, Juriquilla, Santiago de Querétaro, Querétaro 76320 (Mexico); Rodríguez, Rogelio, E-mail: rogelior@unam.mx [Dept. of Molecular Engineering of Materials, Center of Applied Physics and Advanced Technology, National Autonomous University of Mexico (CFATA-UNAM), Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230 (Mexico)

    2016-04-01

    A biocompatible hybrid porous polymer–ceramic material was synthesized to be used as a biomarker in the treatment of breast cancer. This device was equipped with the capacity to release medicaments locally in a controlled manner. The biomaterial was Hydroxyapatite(HAp)-based and had a controlled pore size and pore volume fraction. It was implemented externally using a sharp end and a pair of barbed rings placed opposite each other to prevent relative movement once implanted. The biomarker was impregnated with cis-diamine dichloride platinum (II) [Cl{sub 2}-Pt-(NH{sub 3}){sub 2}]; the rate of release was obtained using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and release occurred over the course of three months. Different release profiles were obtained as a function of the pore volume fraction. The biomaterial was characterized using scanning electron microscopy (SEM) and Raman spectroscopy. - Highlights: • A novel biocompatible hybrid porous polymer–ceramic material was synthesized. • The polymer–ceramic (HAp-based) material was used to prepare a biomarker. • The biomarker was impregnated with cis-diamine dichloride platinum (II). • The rate of cisplatin release was determined using inductively coupled plasma. • The kinetics of the cisplatin release was studied varying the biomarker porosity.

  16. Design and evaluation of osmotic pump-based controlled release system of Ambroxol Hydrochloride.

    Science.gov (United States)

    Cheng, Xiongkai; Sun, Min; Gao, Yan; Cao, Fengliang; Zhai, Guangxi

    2011-08-01

    The purpose of the present study was to design and evaluate an osmotic pump-based drug delivery system for controlling the release of Ambroxol Hydrochloride (Amb). Citric acid, lactose and polyethylene glycol 6000 (PEG 6000) were employed as osmotic agents. Surelease EC containing polyethylene glycol 400 (PEG 400) controlling the membrane porosity was used as semi-permeable membrane. The formulation of tablet core was optimized by orthogonal design and evaluated by weighted mark method. The influences of the amount of PEG 400 and membrane thickness on Amb release were investigated. The optimal osmotic pump tablet (OPT) was evaluated in different release media and at different stirring rates. The major release power confirmed was osmotic pressure. The release of Amb from OPT was verified at a rate of approximately zero-order, and cumulative release percentage at 12?h was 92.6%. The relative bioavailability of Amb OPT in rabbits relative to the commercial sustained capsule was 109.6%. Our results showed that Amb OPT could be a practical preparation with a good prospect.

  17. Preparation and evaluation of waxes/fat microspheres loaded with lithium carbonate for controlled release

    Directory of Open Access Journals (Sweden)

    Gowda D

    2007-01-01

    Full Text Available To minimize the unwanted toxic effects of anti maniac drug lithium carbonate by kinetic control of drug release, it was entrapped into gastro resistant, biodegradable, waxes and fat such as beeswax, cetostearyl alcohol, spermaceti and cetylalcohol microspheres using meltable emulsified dispersion cooling induced solidification technique utilizing a wetting agent. Solid, discrete, reproducible free flowing microspheres were obtained. The yield of the microspheres was up to 90.0%. More than 98.0% of the isolated microspheres were of particle size range 115 to 855 mm. The microspheres had smooth surfaces, with free flowing and good packing properties. Scanning electron microscope confirmed their spherical structures within a size range of 339-355 mm. The drug loaded in waxes and fat microspheres was stable and compatible, as confirmed by DSC and FTIR studies. The release of drug was controlled for more than 8 hours. Intestinal drug release from waxes/ fat microspheres was studied and compared with the releases behavior of commercially available formulation Intalith CR ®-450. The release kinetics followed different transport mechanisms. The drug release performance was greatly affected by the materials used in microsphere preparations, which allows absorption in the intestinal tract.

  18. Controlled release/removal technology; Seigyo hoshutsu {center_dot} jokyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Tojo, K. [Kyushu Inst. of Tech., Fukuoka (Japan)

    2000-02-05

    The controlled release is to control optimally releasing velocity of active ingredient in medication or agricultural chemicals for therapy or vermin control. The novel transdermal therapeutic system can be developed considering diapause term of medication setting type or time pharmacology by storing information of time lag for medication permeability in medication keeping layer. Furthermore by resent iontophoresis technology using electric fields for controlling drug permeability through the skin, migration volume of active ingredient to blood can be controlled pulsed shape by On- Off of electric fields. In another hand, it comes to be clarified that drugs in the body can be extracted by contrarotating operation of electrodes. From now, effective removal system of barren materials from organism or time controlling therapeutic system with feed buck function can be realized by being optimal novel technology of medical engineering therapy. (NEDO)

  19. Role of nitric oxide in control of prolactin release by the adenohypophysis.

    Science.gov (United States)

    Duvilanski, B H; Zambruno, C; Seilicovich, A; Pisera, D; Lasaga, M; Diaz, M C; Belova, N; Rettori, V; McCann, S M

    1995-01-01

    Nitric oxide synthase-containing cells were visualized in the anterior pituitary gland by immunocytochemistry. Consequently, we began an evaluation of the possible role of NO in the control of anterior pituitary function. Prolactin is normally under inhibitory hypothalamic control, and in vitro the gland secretes large quantities of the hormone. When hemipituitaries were incubated for 30 min in the presence of sodium nitroprusside, a releaser of NO, prolactin release was inhibited. This suppression was completely blocked by the scavenger of NO, hemoglobin. Analogs of arginine, such as NG-monomethyl-L-arginine (NMMA, where NG is the terminal guanidino nitrogen) and nitroarginine methyl ester, inhibit NO synthase. Incubation of hemipituitaries with either of these compounds significantly increased prolactin release. Since in other tissues most of the actions of NO are mediated by activation of soluble guanylate cyclase with the formation of cyclic GMP, we evaluated the effects of cyclic GMP on prolactin release. Cyclic GMP (10 mM) produced an approximately 40% reduction in prolactin release. Prolactin release in vivo and in vitro can be stimulated by several peptides, which include vasoactive intestinal polypeptide and substance P. Consequently, we evaluated the possible role of NO in these stimulations by incubating the glands in the presence of either of these peptides alone or in combination with NMMA. In the case of vasoactive intestinal polypeptide, the significant stimulation of prolactin release was augmented by NMMA to give an additive effect. In the case of substance P, there was a smaller but significant release of prolactin that was not significantly augmented by NMMA. We conclude that NO has little effect on the stimulatory action of these two peptides on prolactin release. Dopamine (0.1 microM), an inhibitor of prolactin release, reduced prolactin release, and this inhibitory action was significantly blocked by either hemoglobin (20 micrograms/ml) or

  20. Synthesis and Performance of Polyurethane Coated Urea as Slow/controlled Release Fertilizer

    Institute of Scientific and Technical Information of China (English)

    LI Qingshan; WU Shu; RU Tiejun; WANG Limin; XING Guangzhong; WANG Jinming

    2012-01-01

    Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules,isocyanate,polyols and paraffin.Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface.Paraffin serves as a lubricant during syntheses of polyurethane skin layers.The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR,SEM and TG.Urea nitrogen slow-release behavior of the polyurethane coated urea was tested.The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 μm were formed on urea surface,the urea nitrogen slow-release time can reach 40-50 days.Paraffin proves to play a key role in inhibiting water to penetrate into urea,but excessive addition would decrease the polyurethane crosslinking density.

  1. Control of neurotransmitter release by an internal gel matrix in synaptic vesicles.

    Science.gov (United States)

    Reigada, David; Díez-Pérez, Ismael; Gorostiza, Pau; Verdaguer, Albert; Gómez de Aranda, Inmaculada; Pineda, Oriol; Vilarrasa, Jaume; Marsal, Jordi; Blasi, Joan; Aleu, Jordi; Solsona, Carles

    2003-03-18

    Neurotransmitters are stored in synaptic vesicles, where they have been assumed to be in free solution. Here we report that in Torpedo synaptic vesicles, only 5% of the total acetylcholine (ACh) or ATP content is free, and that the rest is adsorbed to an intravesicular proteoglycan matrix. This matrix, which controls ACh and ATP release by an ion-exchange mechanism, behaves like a smart gel. That is, it releases neurotransmitter and changes its volume when challenged with small ionic concentration change. Immunodetection analysis revealed that the synaptic vesicle proteoglycan SV2 is the core of the intravesicular matrix and is responsible for immobilization and release of ACh and ATP. We suggest that in the early steps of vesicle fusion, this internal matrix regulates the availability of free diffusible ACh and ATP, and thus serves to modulate the quantity of transmitter released.

  2. Misrepresentation of randomized controlled trials in press releases and news coverage: a cohort study.

    Science.gov (United States)

    Yavchitz, Amélie; Boutron, Isabelle; Bafeta, Aida; Marroun, Ibrahim; Charles, Pierre; Mantz, Jean; Ravaud, Philippe

    2012-01-01

    Previous studies indicate that in published reports, trial results can be distorted by the use of "spin" (specific reporting strategies, intentional or unintentional, emphasizing the beneficial effect of the experimental treatment). We aimed to (1) evaluate the presence of "spin" in press releases and associated media coverage; and (2) evaluate whether findings of randomized controlled trials (RCTs) based on press releases and media coverage are misinterpreted. We systematically searched for all press releases indexed in the EurekAlert! database between December 2009 and March 2010. Of the 498 press releases retrieved and screened, we included press releases for all two-arm, parallel-group RCTs (n = 70). We obtained a copy of the scientific article to which the press release related and we systematically searched for related news items using Lexis Nexis. "Spin," defined as specific reporting strategies (intentional or unintentional) emphasizing the beneficial effect of the experimental treatment, was identified in 28 (40%) scientific article abstract conclusions and in 33 (47%) press releases. From bivariate and multivariable analysis assessing the journal type, funding source, sample size, type of treatment (drug or other), results of the primary outcomes (all nonstatistically significant versus other), author of the press release, and the presence of "spin" in the abstract conclusion, the only factor associated, with "spin" in the press release was "spin" in the article abstract conclusions (relative risk [RR] 5.6, [95% CI 2.8-11.1], p < 0.001). Findings of RCTs based on press releases were overestimated for 19 (27%) reports. News items were identified for 41 RCTs; 21 (51%) were reported with "spin," mainly the same type of "spin" as those identified in the press release and article abstract conclusion. Findings of RCTs based on the news item was overestimated for ten (24%) reports. "Spin" was identified in about half of press releases and media coverage. In

  3. Misrepresentation of randomized controlled trials in press releases and news coverage: a cohort study.

    Directory of Open Access Journals (Sweden)

    Amélie Yavchitz

    Full Text Available BACKGROUND: Previous studies indicate that in published reports, trial results can be distorted by the use of "spin" (specific reporting strategies, intentional or unintentional, emphasizing the beneficial effect of the experimental treatment. We aimed to (1 evaluate the presence of "spin" in press releases and associated media coverage; and (2 evaluate whether findings of randomized controlled trials (RCTs based on press releases and media coverage are misinterpreted. METHODS AND FINDINGS: We systematically searched for all press releases indexed in the EurekAlert! database between December 2009 and March 2010. Of the 498 press releases retrieved and screened, we included press releases for all two-arm, parallel-group RCTs (n = 70. We obtained a copy of the scientific article to which the press release related and we systematically searched for related news items using Lexis Nexis. "Spin," defined as specific reporting strategies (intentional or unintentional emphasizing the beneficial effect of the experimental treatment, was identified in 28 (40% scientific article abstract conclusions and in 33 (47% press releases. From bivariate and multivariable analysis assessing the journal type, funding source, sample size, type of treatment (drug or other, results of the primary outcomes (all nonstatistically significant versus other, author of the press release, and the presence of "spin" in the abstract conclusion, the only factor associated, with "spin" in the press release was "spin" in the article abstract conclusions (relative risk [RR] 5.6, [95% CI 2.8-11.1], p < 0.001. Findings of RCTs based on press releases were overestimated for 19 (27% reports. News items were identified for 41 RCTs; 21 (51% were reported with "spin," mainly the same type of "spin" as those identified in the press release and article abstract conclusion. Findings of RCTs based on the news item was overestimated for ten (24% reports. CONCLUSION: "Spin" was identified in

  4. Controlled release from drug microparticles via solventless dry-polymer coating.

    Science.gov (United States)

    Capece, Maxx; Barrows, Jason; Davé, Rajesh N

    2015-04-01

    A novel solvent-less dry-polymer coating process employing high-intensity vibrations avoiding the use of liquid plasticizers, solvents, binders, and heat treatments is utilized for the purpose of controlled release. The main hypothesis is that such process having highly controllable processing intensity and time may be effective for coating particularly fine particles, 100 μm and smaller via exploiting particle interactions between polymers and substrates in the dry state, while avoiding breakage yet achieving conformal coating. The method utilizes vibratory mixing to first layer micronized polymer onto active pharmaceutical ingredient (API) particles by virtue of van der Waals forces and to subsequently mechanically deform the polymer into a continuous film. As a practical example, ascorbic acid and ibuprofen microparticles, 50-500 μm, are coated with the polymers polyethylene wax or carnauba wax, a generally recognized as safe material, resulting in controlled release on the order of seconds to hours. As a novelty, models are utilized to describe the coating layer thickness and the controlled-release behavior of the API, which occurs because of a diffusion-based mechanism. Such modeling would allow the design and control of the coating process with application for the controlled release of microparticles, particularly those less than 100 μm, which are difficult to coat by conventional solvent coating methods. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  5. Ultrafast optical control of magnetization dynamics in polycrystalline bismuth doped iron garnet thin films

    Energy Technology Data Exchange (ETDEWEB)

    Deb, Marwan, E-mail: marwan.deb@ipcms.unistra.fr; Vomir, Mircea; Rehspringer, Jean-Luc; Bigot, Jean-Yves [Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, CNRS, Université de Strasbourg, BP 43, 23 rue du Loess, 67034 Strasbourg Cedex 02 (France)

    2015-12-21

    Controlling the magnetization dynamics on the femtosecond timescale is of fundamental importance for integrated opto-spintronic devices. For industrial perspectives, it requires to develop simple growth techniques for obtaining large area magneto-optical materials having a high amplitude ultrafast Faraday or Kerr response. Here we report on optical pump probe studies of light induced spin dynamics in high quality bismuth doped iron garnet polycrystalline film prepared by the spin coating method. We demonstrate an ultrafast non-thermal optical control of the spin dynamics using both circularly and linearly polarized pulses.

  6. Ammonium-nitrogen-contaminated groundwater remediation by a sequential three-zone permeable reactive barrier (multibarrier) with oxygen-releasing compound (ORC)/clinoptilolite/spongy iron: column studies.

    Science.gov (United States)

    Huang, Guoxin; Liu, Fei; Yang, Yingzhao; Kong, Xiangke; Li, Shengpin; Zhang, Ying; Cao, Dejun

    2015-03-01

    A novel sequential permeable reactive barrier (multibarrier), composed of oxygen-releasing compound (ORC)/clinoptilolite/spongy iron zones in series, was proposed for ammonium-nitrogen-contaminated groundwater remediation. Column experiments were performed to: (1) evaluate the overall NH4(+)-N removal performance of the proposed multibarrier, (2) investigate nitrogen transformation in the three zones, (3) determine the reaction front progress, and (4) explore cleanup mechanisms for inorganic nitrogens. The results showed that NH4 (+)-N percent removal by the multibarrier increased up to 90.43 % after 21 pore volumes (PVs) at the influent dissolved oxygen of 0.68∼2.45 mg/L and pH of 6.76∼7.42. NH4(+)-N of 4.06∼10.49 mg/L was depleted and NOx(-)-N (i.e., NO3 (-)-N + NO2(-)-N) of 4.26∼9.63 mg/L was formed before 98 PVs in the ORC zone. NH4(+)-N of ≤4.76 mg/L was eliminated in the clinoptilolite zone. NOx(-)-N of 10.44∼12.80 mg/L was lost before 21 PVs in the spongy iron zone. The clinoptilolite zone length should be reduced to 30 cm. Microbial nitrification played a dominant role in NH4(+)-N removal in the ORC zone. Ion exchange was majorly responsible for NH4(+)-N elimination in the clinoptilolite zone. Chemical reduction and hydrogenotrophic denitrification both contributed to NOx(-)-N transformation, but the chemical reduction capacity decreased after 21 PVs in the spongy iron.

  7. The Radiological Impact of 210Pb and 210Po Released from the Iron- and Steel-Making Plant ILVA in Taranto (Italy on the Environment and the Public

    Directory of Open Access Journals (Sweden)

    Guogang Jia

    2013-01-01

    Full Text Available Lead-210 and 210Po are naturally occurring radionuclides. Due to volatile characteristic of lead and polonium, environmental pollution of 210Pb and 210Po released from the coal power plant, steel-making industry and refractory material industry has been an exposure problem for the members of public. In this paper studies on the activity concentrations of 210Po and 210Pb in the raw materials, dust particles, surficial soils and atmospheric particulate samples collected in the area of the Iron- and Steel-Making Plant ILVA Taranto (Italy were made. These data have been used to evaluate the source-term, distributions, inventories, mass balance, biological availability, ecological migration processes and public exposure risk of 210Pb and 210Po in the concerned environment.

  8. Doses of controlled-release fertilizer for production of rubber tree rootstocks

    OpenAIRE

    Renato Luis Grisi Macedo; Elainy Botelho Carvalho Pereira; Ailton Vitor Pereira; Nelson Venturin; Antonio Nilson Zamunér Filho

    2012-01-01

    This experimental study aimed to evaluate the effects of doses of controlled-release fertilizer (ALL) on the development of rubber tree rootstocks. The fertilizer used was Osmocote®, scheduled to be released for 8-9 months and with the following composition: N (15%), P2O5 (9%), K2O (12%), Mg (1%), S (2.3%), B (0.02%), Cu (0.05%), Fe (1%), Mn (0.06%), Mo (0.02%) and Zn (0.05%). A randomized block design was used, with four treatments and eight replicates of 20 plants per plot. The controlled-r...

  9. Formulation and evaluation of controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum

    Directory of Open Access Journals (Sweden)

    Gurpreet Arora

    2011-01-01

    Full Text Available The aim of study was to prepare controlled release matrix mucoadhesive tablets of domperidone using Salvia plebeian gum as natural polymer. Tablets were formulated by direct compression technology employing the natural polymer in different concentrations (5, 10, 15 and 20% w/w. The prepared batches were evaluated for drug assay, diameter, thickness, hardness and tensile strength, swelling index, mucoadhesive strength (using texture analyzer and subjected to in vitro drug release studies. Real-time stability studies were also conducted on prepared batches. In vitro drug release data were fitted in various release kinetic models for studying the mechanism of drug release. Tensile strength was found to increase from 0.808 ± 0.098 to 1.527 ± 0.10 mN/cm 2 and mucoadhesive strength increased from 13.673 ± 1.542 to 40.378 ± 2.345 N, with an increase in the polymer concentration from 5 to 20% (A1 to A4. Swelling index was reported to increase with both increase in the concentration of gum and the time duration. The in vitro drug release decreased from 97.76 to 83.4% (A1 to A4 with the increase in polymer concentration. The drug release from the matrix tablets was found to follow zero-order and Higuchi models, indicating the matrix-forming potential of natural polymer. The value of n was found to be between 0.5221 and 0.8992, indicating the involvement of more than one drug release mechanism from the formulation and possibly the combination of both diffusion and erosion. These research findings clearly indicate the potential of S. plebeian gum to be used as binder, release retardant and mucoadhesive natural material in tablet formulations.

  10. Ciprofloxacin Controlled-Solid Lipid Nanoparticles: Characterization, In Vitro Release, and Antibacterial Activity Assessment

    Science.gov (United States)

    2017-01-01

    The objective of this research was to formulate ciprofloxacin (CIP) in solid lipid nanoparticles (SLNs) in an attempt to develop a controlled drug delivery system. An ultrasonic melt-emulsification method was used for preparing CIP-loaded SLNs. Key findings included that SLNs were successfully produced with average particle sizes ranging from 165 to 320 nm and polydispersity index in the range of 0.18–0.33. High entrapment efficiency values were reported in all formulations. The atomic force scanning microscopic images showed spherical shape with the size range closer to those found by the particle size analyzer. CIP release exhibited controlled-release behavior with various lipids. Ciprofloxacin solid lipid nanoparticles formula containing stearic acid (CIPSTE) displayed the strongest burst effect and the most rapid release rate. The release data revealed a better fit to the Higuchi diffusion model. After storing the CIPSTE formula at room temperature for 120 days, no significant difference in particle size and zeta potential was found. CIP-loaded SLNs exhibited superior antibacterial activity. Incorporation of CIP into SLNs leads to controlled release and a superior antibacterial effect of CIP. PMID:28194408

  11. A controlled release system of titanocene dichloride by electrospun fiber and its antitumor activity in vitro.

    Science.gov (United States)

    Chen, Ping; Wu, Qing-Sheng; Ding, Ya-Ping; Chu, Maoquan; Huang, Zheng-Ming; Hu, Wen

    2010-11-01

    In order to improve both safety and efficacy of cancer chemotherapy of titanocene dichloride and overcome the shortcomings such as instability and short half-life in the human body, we report a controlled release system of titanocene dichloride by electrospun fiber and its in vitro antitumor activity against human lung tumor spca-1 cells. The system was developed by electrospinning. The release profiles of titanocene dichloride in PBS were researched by UV-Vis spectrophotometer. In vitro antitumor activities of the fibers were examined by MTT method. Titanocene dichloride was well incorporated in biodegradable poly(L-lactic acid) fibers. XRD results suggest that titanocene dichloride exists in the amorphous form in the fibers. The controlled release of titanocene dichloride can be gained for long time. MTT showed actual titanocene dichloride content 40, 80, 160 and 240 mg/L from the fibers mat, cell growth inhibition rates of 11.2%, 22.1%, 44.2% and 68.2% were achieved, respectively. The titanocene dichloride released has obvious inhibition effect against lung tumor cells. The system has an effect of controlled release of titanocene dichloride and may be used as an implantable anticancer drug in clinical applications in the future.

  12. FORMULATION AND EVALUATION OF ORAL CONTROLLED RELEASE DOSAGE FORM OF ANTI-HYPERTENSIVE AGENT

    Directory of Open Access Journals (Sweden)

    Lakshmi Parvathi A

    2012-12-01

    Full Text Available The aim of present investigation is preparation, characterization and evaluation of oral controlled release matrix tablets of Propranolol HCl in order to improve efficacy and to reduce the side effects. Tablets were prepared by direct compression method using different polymers like Guar gum, HPMC K4M, PVP and MCC used as the directly compressible vehicle. The granules were evaluated for pre-formulation characteristics and the tablets were subjected to post compression parameters, drug content and in-vitro dissolution release studies. In-vitro dissolution studies were carried out for 12 hrs and the results showed that among the nine formulations F8 and F9 showed good dissolution profile to control the drug release respectively. The drug release follows first order kinetics and the mechanism was found to be diffusion controlled for all the formulations (except F-9. The mechanism of drug release from F-9 was diffusion coupled with erosion. The Stability studies were carried out according to ICH guideline which indicates that the selected formulations (F8 and F9 were stable. In conclusion the results suggest that the developed matrix tablets of Propranolol HCl could perform therapeutically better than conventional dosage form, leading to improved efficacy and better patient compliance.

  13. Ciprofloxacin Controlled-Solid Lipid Nanoparticles: Characterization, In Vitro Release, and Antibacterial Activity Assessment

    Directory of Open Access Journals (Sweden)

    Gamal A. Shazly

    2017-01-01

    Full Text Available The objective of this research was to formulate ciprofloxacin (CIP in solid lipid nanoparticles (SLNs in an attempt to develop a controlled drug delivery system. An ultrasonic melt-emulsification method was used for preparing CIP-loaded SLNs. Key findings included that SLNs were successfully produced with average particle sizes ranging from 165 to 320 nm and polydispersity index in the range of 0.18–0.33. High entrapment efficiency values were reported in all formulations. The atomic force scanning microscopic images showed spherical shape with the size range closer to those found by the particle size analyzer. CIP release exhibited controlled-release behavior with various lipids. Ciprofloxacin solid lipid nanoparticles formula containing stearic acid (CIPSTE displayed the strongest burst effect and the most rapid release rate. The release data revealed a better fit to the Higuchi diffusion model. After storing the CIPSTE formula at room temperature for 120 days, no significant difference in particle size and zeta potential was found. CIP-loaded SLNs exhibited superior antibacterial activity. Incorporation of CIP into SLNs leads to controlled release and a superior antibacterial effect of CIP.

  14. Intercalation of urea into kaolinite for preparation of controlled release fertilizer

    Directory of Open Access Journals (Sweden)

    Mahdavi Fariba

    2014-01-01

    Full Text Available In this study urea was intercalated between layers of kaolinite by dry grinding technique to be used for preparing controlled release fertilizer. X-ray powder diffraction (XRPD patterns confirmed the intercalation of urea into kaolinite by the significant expansion of the basal spacing of kaolinite layers from 0.710 nm to 1.090 nm. Fourier transform infrared spectroscopy (FT-IR also confirmed the hydrogen bonding between urea and kaolinite. Based on CHNS elemental analysis, 20% (wt. urea was intercalated between kaolinite layers. The urea-intercalated kaolinite was mixed with hydroxypropyl methylcellulose (HPMC binder and was granulated to prepare the nitrogen-based controlled release fertilizer. To study the nitrogen release behavior of granules, ultraviolet/visible (UV-Vis spectroscopy was used through the diacetyl monoxime (DAM colorimetric method. The result of UV-Vis spectroscopy showed that intercalation of urea into kaolinite decreased the nitrogen release from 25.50 to 13.66 % after 24 hours and from 98.15 to 70.01% after 30 days incubation in water. According to the results, the prepared controlled release fertilizer (CRF behaved according to the standard for CRFs.

  15. Effect of microbial mediated iron plaque reduction on arsenic mobility in paddy soil

    Institute of Scientific and Technical Information of China (English)

    WANG Xinjun; CHEN Xueping; YANG Jing; WANG Zhaosu; SUN Guoxin

    2009-01-01

    The potential of microbial mediated iron plaque reduction,and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil.To our knowledge,this is the first time to report the impact of microbial iron plaque reduction on As mobility.Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors,respectively.The Fe(Ⅱ) concentration with the treatment of anthraquinone-2,6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control.Arsenic released from iron plaque with the iron reduction,and a significant correlation between Fe(Ⅱ) and total As in culture was observed.However,compared with control,the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS.In addition,the concentrations of As(Ⅲ) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30.These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase,however,microbial iron reduction induced the formation of more crystalline iron minerals,leading to As sequestration.In addition,the presence of AQDS in solution can accelerate the iron reduction,the As release from iron plaque and subsequently the As retention in the crystalline iron mineral.Thus,our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.

  16. Multivitamin and iron supplementation to prevent periconceptional anemia in rural tanzanian women: a randomized, controlled trial.

    Directory of Open Access Journals (Sweden)

    Nilupa S Gunaratna

    Full Text Available Women's nutritional status during conception and early pregnancy can influence maternal and infant outcomes. This study examined the efficacy of pre-pregnancy supplementation with iron and multivitamins to reduce the prevalence of anemia during the periconceptional period among rural Tanzanian women and adolescent girls.A double-blind, randomized controlled trial was conducted in which participants were individually randomized to receive daily oral supplements of folic acid alone, folic acid and iron, or folic acid, iron, and vitamins A, B-complex, C, and E at approximately single recommended dietary allowance (RDA doses for six months.Rural Rufiji District, Tanzania.Non-pregnant women and adolescent girls aged 15-29 years (n = 802.The study arms were comparable in demographic and socioeconomic characteristics, food security, nutritional status, pregnancy history, and compliance with the regimen (p>0.05. In total, 561 participants (70% completed the study and were included in the intention-to-treat analysis. Hemoglobin levels were not different across treatments (median: 11.1 g/dL, Q1-Q3: 10.0-12.4 g/dL, p = 0.65. However, compared with the folic acid arm (28%, there was a significant reduction in the risk of hypochromic microcytic anemia in the folic acid and iron arm (17%, RR: 0.61, 95% CI: 0.42-0.90, p = 0.01 and the folic acid, iron, and multivitamin arm (19%, RR: 0.66, 95% CI: 0.45-0.96, p = 0.03. Inverse probability of treatment weighting (IPTW to adjust for potential selection bias due to loss to follow-up did not materially change these results. The effect of the regimens was not modified by frequency of household meat consumption, baseline underweight status, parity, breastfeeding status, or level of compliance (in all cases, p for interaction>0.2.Daily oral supplementation with iron and folic acid among women and adolescents prior to pregnancy reduces risk of anemia. The potential benefits of supplementation on the risk of

  17. Multivitamin and Iron Supplementation to Prevent Periconceptional Anemia in Rural Tanzanian Women: A Randomized, Controlled Trial

    Science.gov (United States)

    Gunaratna, Nilupa S.; Masanja, Honorati; Mrema, Sigilbert; Levira, Francis; Spiegelman, Donna; Hertzmark, Ellen; Saronga, Naomi; Irema, Kahema; Shuma, Mary; Elisaria, Ester; Fawzi, Wafaie

    2015-01-01

    Objective Women’s nutritional status during conception and early pregnancy can influence maternal and infant outcomes. This study examined the efficacy of pre-pregnancy supplementation with iron and multivitamins to reduce the prevalence of anemia during the periconceptional period among rural Tanzanian women and adolescent girls. Design A double-blind, randomized controlled trial was conducted in which participants were individually randomized to receive daily oral supplements of folic acid alone, folic acid and iron, or folic acid, iron, and vitamins A, B-complex, C, and E at approximately single recommended dietary allowance (RDA) doses for six months. Setting Rural Rufiji District, Tanzania. Subjects Non-pregnant women and adolescent girls aged 15–29 years (n = 802). Results The study arms were comparable in demographic and socioeconomic characteristics, food security, nutritional status, pregnancy history, and compliance with the regimen (p>0.05). In total, 561 participants (70%) completed the study and were included in the intention-to-treat analysis. Hemoglobin levels were not different across treatments (median: 11.1 g/dL, Q1-Q3: 10.0–12.4 g/dL, p = 0.65). However, compared with the folic acid arm (28%), there was a significant reduction in the risk of hypochromic microcytic anemia in the folic acid and iron arm (17%, RR: 0.61, 95% CI: 0.42–0.90, p = 0.01) and the folic acid, iron, and multivitamin arm (19%, RR: 0.66, 95% CI: 0.45–0.96, p = 0.03). Inverse probability of treatment weighting (IPTW) to adjust for potential selection bias due to loss to follow-up did not materially change these results. The effect of the regimens was not modified by frequency of household meat consumption, baseline underweight status, parity, breastfeeding status, or level of compliance (in all cases, p for interaction>0.2). Conclusions Daily oral supplementation with iron and folic acid among women and adolescents prior to pregnancy reduces risk of anemia. The

  18. Controlled synthesis of metallic iron nanoparticles and their magnetic hyperthermia performance in polyaniline composite nanofibers

    Science.gov (United States)

    Yang, Ta-I.; Chang, Su-Hua

    2017-02-01

    Electrospun magnetic iron/polyaniline nanofibers with applicable heating performance in an AC magnetic field were developed. A new and low-cost method was introduced to synthesize metallic iron (Fe0) nanoparticles with uniform size distribution. The Fe0 nanoparticles were synthesized in an aqueous environment at room temperature with the assistance of polyvinylpyrrolidone and sodium citrate to tailor their particle sizes ranging from 10 to 20 nm. The experimental results showed that regulating the free iron ions present in the solution is critical for obtaining Fe0 nanoparticles with narrow size distribution. The Fe0 nanoparticles were subsequently incorporated with conductive polyaniline (PANI) to fabricate Fe0/PANI/polycaprolactone nanofibers using an electrospinning technique. The resultant composite nanofibers have controlled fiber diameters and also show electrochemical redox properties originating from the PANI polymer. The heating performance test concluded that both eddy current loss from PANI and Neel relaxation loss of magnetic Fe0 nanoparticles can contribute to the power dissipation of the prepared composite nanofibers. The optimal heating performance can be obtained by adjusting the composition of Fe0 nanoparticles and PANI in nanofibers.

  19. Phytoestrogens modulate hepcidin expression by Nrf2: Implications for dietary control of iron absorption.

    Science.gov (United States)

    Bayele, Henry K; Balesaria, Sara; Srai, Surjit K S

    2015-12-01

    Hepcidin is a liver-derived antimicrobial peptide that regulates iron absorption and is also an integral part of the acute phase response. In a previous report, we found evidence that this peptide could also be induced by toxic heavy metals and xenobiotics, thus broadening its teleological role as a defensin. However it remained unclear how its sensing of disparate biotic and abiotic stressors might be integrated at the transcriptional level. We hypothesized that its function in cytoprotection may be regulated by NFE2-related factor 2 (Nrf2), the master transcriptional controller of cellular stress defenses. In this report, we show that hepcidin regulation is inextricably linked to the acute stress response through Nrf2 signaling. Nrf2 regulates hepcidin expression from a prototypical antioxidant response element in its promoter, and by synergizing with other basic leucine-zipper transcription factors. We also show that polyphenolic small molecules or phytoestrogens commonly found in fruits and vegetables including the red wine constituent resveratrol can induce hepcidin expression in vitro and post-prandially, with concomitant reductions in circulating iron levels and transferrin saturation by one such polyphenol quercetin. Furthermore, these molecules derepress hepcidin promoter activity when its transcription by Nrf2 is repressed by Keap1. Taken together, the data show that hepcidin is a prototypical antioxidant response or cytoprotective gene within the Nrf2 transcriptional circuitry. The ability of phytoestrogens to modulate hepcidin expression in vivo suggests a novel mechanism by which diet may impact iron homeostasis.

  20. Controlled Release of Benzocaine from Monomer and Copolymer Carriers in Synthetic Gastro-intestinal Media

    Directory of Open Access Journals (Sweden)

    Houaria Merine

    2014-05-01

    Full Text Available New dosage forms able to control drug release in the gastro-intestinal media have been prepared and investigated in this paper. Two different type of medicinal agent bonding (MA, in our case Benzocaine (Bz, were chosen in order to examine drug release. i MA attached to ethylenic monomer (m,p-vinylbenzaldehyde, condensation reaction. ii The copolymer carrier (Cp is obtained by copolymerizing this monomer. These two carriers were well characterized by microanalysis, FTIR, DSC (Tg and GPC (Ip and the two fraction α and β were calculated from elemental analyses of Cp. The results showed good polydispersity and low average molecular weight. MA linked to an organic product by the azomethine function (C=N, hydrolytically sensitive, allowed controlled release of Bz, from the monomer carrier and from the bending Schiff bases groups. Theoretical and experimental analyses of controlled release of Bz kinetics from monomer and copolymer carriers were conducted for the case of contact with synthetic gastro-intestinal fluids at various pH (1,2; 6,0 and 8,0 at 37°C. The process was found to be controlled by the nature of media (heterogeneous, which involved the preliminary hydrolysis, and the drug (Bz diffusing out of structure of copolymer (Cp to the external aqueous media. The results obtained on the rate of delivery showed a clear difference between pH = 1,2 and pH = 6,0 and 8,0 based on: i The cation of p-aminoniumbenzoic acid (PABAH+ release at pH = 1,2 ii Bz release at pH = 6,0 and 8,0

  1. Controlled release profiles of dipyridamole from biodegradable microspheres on the base of poly(3-hydroxybutyrate.

    Directory of Open Access Journals (Sweden)

    2007-12-01

    Full Text Available Novel biodegradable microspheres on the base of poly(3-hydroxybutyrate (PHB designed for controlled release of antithrombotic drug, namely dipyridamole (DPD, have been kinetically studied. The profiles of release from the microspheres with different diameters 4, 9, 63, and 92 µm present the progression of nonlinear and linear stages. Diffusionkinetic equation describing both linear (PHB hydrolysis and nonlinear (diffusion stages of the DPD release profiles from the spherical subjects has been written down as the sum of two terms: desorption from the homogeneous sphere in accordance with diffusion mechanism and the zero-order release. In contrast to the diffusivity dependence on microsphere size, the constant characteristics (k of linearity are scarcely affected by the diameter of PHB microparticles. The view of the kinetic profiles as well as the low rate of DPD release are in satisfactory agreement with kinetics of weight loss measured in vitro for the PHB films. Taking into account kinetic results, we suppose that the degradation of both films and PHB microspheres is responsible for the linear stage of DPD release profiles. In the nearest future, combination of biodegradable PHB and DPD as a representative of proliferation cell inhibitors will give possibility to elaborate the novel injectable therapeutic system for a local, long-term, antiproliferative action.

  2. The Transcription Factor NIN-LIKE PROTEIN7 Controls Border-Like Cell Release.

    Science.gov (United States)

    Karve, Rucha; Suárez-Román, Frank; Iyer-Pascuzzi, Anjali S

    2016-07-01

    The root cap covers the tip of the root and functions to protect the root from environmental stress. Cells in the last layer of the root cap are known as border cells, or border-like cells (BLCs) in Arabidopsis (Arabidopsis thaliana). These cells separate from the rest of the root cap and are released from its edge as a layer of living cells. BLC release is developmentally regulated, but the mechanism is largely unknown. Here, we show that the transcription factor NIN-LIKE PROTEIN7 (NLP7) is required for the proper release of BLCs in Arabidopsis. Mutations in NLP7 lead to BLCs that are released as single cells instead of an entire layer. NLP7 is highly expressed in BLCs and is activated by exposure to low pH, a condition that causes BLCs to be released as single cells. Mutations in NLP7 lead to decreased levels of cellulose and pectin. Cell wall-loosening enzymes such as CELLULASE5 (CEL5) and a pectin lyase-like gene, as well as the root cap regulators SOMBRERO and BEARSKIN1/2, are activated in nlp7-1 seedlings. Double mutant analysis revealed that the nlp7-1 phenotype depends on the expression level of CEL5 Mutations in NLP7 lead to an increase in susceptibility to a root-infecting fungal pathogen. Together, these data suggest that NLP7 controls the release of BLCs by acting through the cell wall-loosening enzyme CEL5.

  3. Controlled drug-release system based on pH-sensitive chloride-triggerable liposomes.

    Science.gov (United States)

    Wehunt, Mark P; Winschel, Christine A; Khan, Ali K; Guo, Tai L; Abdrakhmanova, Galya R; Sidorov, Vladimir

    2013-03-01

    New pH-sensitive lipids were synthesized and utilized in formulations of liposomes suitable for controlled drug release. These liposomes contain various amounts of NaCl in the internal aqueous compartments. The release of the drug model is triggered by an application of HCl cotransporter and exogenous physiologically relevant NaCl solution. HCl cotransporter allows an uptake of HCl by liposomes to the extent of their being proportional to the transmembrane Cl(-) gradient. Therefore, each set of liposomes undergoes internal acidification, which, ultimately, leads to the hydrolysis of the pH-sensitive lipids and content release at the desired time. The developed system releases the drug model in a stepwise fashion, with the release stages separated by periods of low activity. These liposomes were found to be insensitive to physiological concentrations of human serum albumin and to be nontoxic to cells at concentrations exceeding pharmacological relevance. These results render this new drug-release model potentially suitable for in vivo applications.

  4. Formulation and evaluation of dorzolamide hydrochloride-loaded nanoparticles as controlled release drug delivery system

    Directory of Open Access Journals (Sweden)

    Azza A Hasan

    2012-01-01

    Full Text Available This study aimed to prepare anti-glaucomatous dorzolamide hydrochloride-(Dorzo loaded nanoparticles as a controlled release system. Eudragit RS 100 (RS and/or RL 100 (RL were used in formulations by an opportunely adapted Quasi-emulsion solvent diffusion technique. The formulations were evaluated in terms of particle size, zeta potential, drug entrapment, and release profile. All formulations showed tiny particle size varying from 114 to 395 nm for RS and 65 to 277 nm for RL. Positive zeta potential was +19 to +32 mV for RS and +23 to +42 mV for RL formulations. It was demonstrated that increasing polymer concentration lead to increase the percentage of drug entrapped in all batches, to a certain extent (drug: polymer 1:4. Nanoparticles prepared using RL showed lower entrapment efficiency than RS. In contrast, increasing the stirring rate resulted in an increase in the percentage of Dorzo entrapped. A prolonged drug release was shown by all the formulations. Increasing the polymer concentration caused a decrease in the release rate. Moreover, it was evident that increasing RL content increased the amount of Dorzo released. Dorzo-loaded nanoparticles could represent promising drug ophthalmic carriers, due to small particle size, positive zeta potential, and sustained release profile; hence, expecting prolonged corneal contact time, more therapeutically efficient, decreased frequency of administration per day, and better patient compliance.

  5. Oxidative Dissolution of Spent Fuel and Release of Nuclides from a Copper/Iron Canister : Model Developments and Applications

    OpenAIRE

    Liu, Longcheng

    2001-01-01

    Three models have been developed and applied in the performance assessment of a final repository. They are based on accepted theories and experimental results for known and possible mechanisms that may dominate in the oxidative dissolution of spent fuel and the release of nuclides from a canister. Assuming that the canister is breached at an early stage after disposal, the three models describe three sub-systems in the near field of the repository, in which the governing processes and mechani...

  6. Effect of Intravenous Iron Supplementation on Acute Mountain Sickness: A Preliminary Randomized Controlled Study.

    Science.gov (United States)

    Ren, Xuewen; Zhang, Qiuying; Wang, Hao; Man, Chunyan; Hong, Heng; Chen, Li; Li, Tanshi; Ye, Ping

    2015-07-15

    The aim of this study was to assess the role of intravenous iron supplementation in the prevention of AMS. This was a randomized, double-blinded, placebo-controlled study. Forty-one (n=41) healthy Chinese low-altitude inhabitants living in Beijing, China (altitude of about 50 meters) were randomly assigned into intravenous iron supplementation (ISS group; n=21) and placebo (CON group; n=20) groups. Participants in the ISS group received iron sucrose supplement (200 mg) before flying to Lhasa, China (altitude of 4300 meters). Acute mountain sickness (AMS) severity was assessed with the Lake Louise scoring (LLS) system within 5 days after landing on the plateau (at high altitude). Routine check-ups, clinical biochemistry, and blood tests were performed before departure and 24 h after arrival. A total of 38 participants completed the study (ISS group: n=19; CON group: n=19). The rate of subjects with AMS (LLS>3) was lower in the ISS group compared with the CON group, but no significant differences were obtained (P>0.05). There were no differences in patients' baseline characteristics. The physiological indices were similar in both groups except for serum iron concentrations (19.44±10.02 vs. 85.10±26.78 μmol/L) and transferrin saturation rates (28.20±12.14 vs. 68.34±33.12%), which were significantly higher in the ISS group (Piron supplementation has no significant protective effect on AMS in healthy Chinese low-altitude inhabitants.

  7. Novel layered pesticide slow/controlled release materials--supramolecular structure and slow release property of glyphosate intercalated layered double hydroxides

    Institute of Scientific and Technical Information of China (English)

    MENG Jinhong; ZHANG Hui; David G. Evans; DUAN Xue

    2005-01-01

    Two different interlayer structured glyphosate (GLY) intercalated MgAl layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various reaction pH values. The slow/controlled release properties have been tested in Na2CO3 aqueous solution. The release mechanism has been interpreted on the basis of the ion-exchange between the guest GLY anions in the lamellar host and in the release media, and the diffusion process of GLY anions in the interstice and interlayer of GLY intercalates, i.e. diffusion through the particles, is the rate-limiting step of GLY release process. The GLY intercalate assembled at lower pH, possessing higher interlayer gallery height and vertical monolayered arrangement of guest anions in the interlayer with larger packing density, exhibits better slow release property than that assembled at higher pH. The results reveal that the layered double hydroxides have potential application in the pesticide slow/controlled release area.

  8. Escitalopram versus paroxetine controlled release in major depressive disorder: a randomized trial

    Science.gov (United States)

    Kishi, Taro; Matsuda, Yuki; Matsunaga, Shinji; Moriwaki, Masatsugu; Otake, Yoichiro; Akamatsu, Kaku; Okochi, Tomo; Hirano, Shigeki; Funahashi, Toshihiko; Okuda, Momoko; Tabuse, Hideaki; Fujita, Kiyoshi; Iwata, Nakao

    2017-01-01

    Objective There are no direct comparisons between escitalopram and paroxetine controlled release in patients with major depressive disorder (MDD). Methods We conducted a 24-week, rater-masked, randomized trial of escitalopram (5–20 mg/day) versus paroxetine controlled release (12.5–50 mg/day) in patients with MDD (UMIN000011191). Patients with the diagnosis of moderate-to-severe MDD (a 17-item Hamilton Rating Scale for Depression [HAMD-17], with total score at baseline being ≥20) were recruited to participate in a parallel, randomized, controlled trial. The primary outcome for efficacy was an improvement in the 21-item HAMD (HAMD-21) total score at 24 weeks. The secondary outcomes were the response, remission, and discontinuation rates and the incidence of individual adverse events. Results A total of 88 patients with MDD (males, 61.4%; mean age, 40.8±13.4 years) were recruited. The discontinuation rate was 58.0% (escitalopram, 55.8%; paroxetine controlled release, 60.0%). Both escitalopram and paroxetine controlled-release treatment groups exhibited significant reduction in the HAMD-21 total score at 2, 4, 8, 12, and 24 weeks from the baseline. However, there were no significant differences in the HAMD-21 total score, response rate, remission rate, and discontinuation rate at any time point between the groups. In addition, there were no significant differences in the incidence of any individual adverse events (eg, nausea, vomiting, and somnolence) between the treatment groups. Conclusion Our results suggest that escitalopram and paroxetine controlled release had similar efficacy and safety profiles in patients with MDD. One of the primary limitations of this study is the small sample size. PMID:28123299

  9. Effects of Control Release Fertilizers on Nutrient Leaching, Palm Growth and Production Cost

    Directory of Open Access Journals (Sweden)

    Pushpa Soti

    2015-11-01

    Full Text Available Objective of this study was to evaluate the effect of different controlled release fertilizer technologies on nutrient leaching and plant growth parameters of two palm species, Chinese Fan (Livistona chinensis and Queen (Syagrus romanzoffiana. We compared Nutri-Pak (12-4-12 controlled release packet and Harrell’s (12-4-12 controlled release polymer coated urea against Atlantic (8-4-12 controlled release polymer coated urea, coated sulfate of potash, the most commonly used palm fertilizer in South Florida. Plants were grown in 25 cm (11 L pots under 70% shade, watered weekly, with pest and weed control done as required. Plant growth parameters: number of leaves, leaf length and width, and basal diameter, were measured every two months. Leachate was collected weekly after irrigation and a two-month composite sample was analyzed for nutrient concentrations. There was no difference in the growth parameters among the three fertilizers for Chinese Fan plants. However for Queen, Atlantic and Harrell’s had significantly thicker basal diameter than Nutri-Pak. Significant difference in the concentration of nutrients in the leachate was observed among the fertilizer types. Throughout the study period, Nutri-Pak had a lower concentration of nutrients in the leachate than Atlantic and Harrell’s. Our research indicates that Nutri-Pak control release fertilizer is comparable to other commercial fertilizers in Chinese Fan growth, but the larger Queen palms likely require an additional packet. Nutri-Pak fertilizer resulted in less nutrient leaching and could be a better environmental choice.

  10. Transferrin-mediated cellular iron delivery.

    Science.gov (United States)

    Luck, Ashley N; Mason, Anne B

    2012-01-01

    Essential to iron homeostasis is the transport of iron by the bilobal protein human serum transferrin (hTF). Each lobe (N- and C-lobe) of hTF forms a deep cleft which binds a single Fe(3+). Iron-bearing hTF in the blood binds tightly to the specific transferrin receptor (TFR), a homodimeric transmembrane protein. After undergoing endocytosis, acidification of the endosome initiates the release of Fe(3+) from hTF in a TFR-mediated process. Iron-free hTF remains tightly bound to the TFR at acidic pH; following recycling back to the cell surface, it is released to sequester more iron. Efficient delivery of iron is critically dependent on hTF/TFR interactions. Therefore, identification of the pH-specific contacts between hTF and the TFR is crucial. Recombinant protein production has enabled deconvolution of this complex system. The studies reviewed herein support a model in which pH-induced interrelated events control receptor-stimulated iron release from each lobe of hTF. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. The Iron Cage and the Gaze: Interpreting Medical Control in the English Health System

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    Mark Exworthy

    2015-05-01

    Full Text Available This paper seeks to determine the value of theoretical ideal-types of medical control. Whilst ideal types (such as the iron cage and gaze need revision in their application to medical settings, they remain useful in describing and explaining patterns of control and autonomy in the medical profession. The apparent transition from the cage to the gaze has often been over-stated since both types are found in many contemporary health reforms. Indeed, forms of neo-bureaucracy have emerged alongside surveillance of the gaze. These types are contextualised and elaborated in terms of two empirical examples: the management of medical performance and financial incentives for senior hospital doctors in England. Findings point towards the reformulation of medical control, an on-going re-stratification of the medical profession, and the internalisation of managerial discourses. The cumulative effect involves the medical profession’s ability to re-cast and enhance its position (vis-à-vis managerial interests.Keywords: medical profession, medical control, iron cage, gaze

  12. Wireless platform for controlled nitric oxide releasing optical fibers for mediating biological response to implanted devices.

    Science.gov (United States)

    Starrett, Michael A; Nielsen, Matthew; Smeenge, David M; Romanowicz, Genevieve E; Frost, Megan C

    2012-12-01

    Despite the documented potential to leverage nitric oxide generation to improve in vivo performance of implanted devices, a key limitation to current NO releasing materials tested thus far is that there has not been a means to modulate the level of NO release after it has been initiated. We report the fabrication of a wireless platform that uses light to release NO from a polymethylmethacrylate (PMMA) optical fiber coated with an S-nitroso-N-acetylpenicillamine derivatized polydimethylsiloxane (SNAP-PDMS). We demonstrate that a VAOL-5GSBY4 LED (λ(dominant)=460 nm) can be used as a dynamic trigger to vary the level of NO released from 500 μm diameter coated PMMA. The ability to generate programmable sequences of NO flux from the surface of these coated fibers offers precise spatial and temporal control over NO release and provides a platform to begin the systematic study of in vivo physiological response to implanted devices. NO surface fluxes up to 3.88 ± 0.57 × 10(-10)mol cm(-2)min(-1) were achieved with -100 μm thick coatings on the fibers and NO flux was pulsed, ramped and held steady using the wireless platform developed. We demonstrate the NO release is linearly proportional to the drive current applied to the LED (and therefore level of light produced from the LED). This system allow the surface flux of NO from the fibers to be continuously changed, providing a means to determine the level and duration of NO needed to mediate physiological response to blood contacting and subcutaneous implants and will ultimately lead to the intelligent design of NO releasing materials tailored to specific patterns of NO release needed to achieve reliable in vivo performance for intravascular and subcutaneous sensors and potentially for a wide variety of other implanted biomedical devices.

  13. Iron load

    Directory of Open Access Journals (Sweden)

    Filippo Cassarà

    2013-03-01

    Full Text Available Recent research addressed the main role of hepcidin in the regulation of iron metabolism. However, while this mechanism could be relevant in causing iron load in Thalassemia Intermedia and Sickle-Cell Anemia, its role in Thalassemia Major (TM is marginal. This is mainly due to the high impact of transfusional requirement into the severe increase of body iron. Moreover, the damage of iron load may be worsened by infections, as HCV hepatitis, or liver and endocrinological damage. One of the most relevant associations was found between splenectomy and increase of risk for mortality due,probably, to more severe iron load. These issues suggest as morbidity and mortality of this group of patients they do not depend only by our ability in controlling heart damage but even in preventing or treating particular infections and complications. This finding is supported by the impairment of survival curves in patients with complications different from heart damage. However, because, during recent years different direct and indirect methods to detect iron overload in patients affected by secondary hemochromatosis have been implemented, our ability to maintain under control iron load is significantly improved. Anyway, the future in iron load management remains to be able to have an iron load map of our body for targeting chelation and other medical treatment according to the single organ damage.

  14. Effects of Controlled Release Fertilizer on the Post-Production Performance of Impatiens Wallerana

    Science.gov (United States)

    Controlled release fertilizers (CRF) in production systems have been known to reduce environmental contamination. However, there is a lot to be explored as per its use in bedding plant production. Bedding plant growers have not adapted CRF use because there is little information about its use and ...

  15. Longevity of controlled release fertilizer influences the growth of bedding Impatiens

    Science.gov (United States)

    Controlled-release fertilizers (CRF) have not been extensively used in floriculture production, perhaps due to lack of grower experience and research-based information with their use in herbaceous plant production. Any information about the correct use of CRF should increase growers’ confidence in ...

  16. Substrates and controlled-release fertilizations on the quality of eucalyptus cuttings

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    Richardson B. G. da Silva

    2014-11-01

    Full Text Available To produce cuttings with quality, the most appropriate nutritional management strategies should be sought to reduce wastage of fertilizer, while accounting for the characteristics of each substrate. This study evaluated the effect of substrates and doses of controlled-release fertilizer on the quality of Eucalyptus grandis Hill ex Maiden x Eucalyptus urophylla S. T. Blake cuttings. The substrates consisted of several mixtures: vermiculite+carbonized rice chaff+coconut fibre (1:1:1; vermiculite+coconut fibre (1:1; and vermiculite+carbonized rice chaff (1:1. These mixtures were added to 2, 4, 6 and 8 kg of controlled-release fertilizer per cubic meter of substrate. The substrates that do not support root development and have lower water retention, independently of the dose of controlled-release fertilizer, reduce the quality of the root system. For substrates with proper values of water retention, such as vermiculite+coconut fibre (1:1 and vermiculite+carbonised rice chaff+coconut fibre (1:1:1, the utilization of dose 2 kg of controlled-release fertilizer to each cubic meter is enough to promote cuttings with greater quality of the root systems and proper heights and stem diameters.

  17. Timing of insertion of levonorgestrel-releasing intrauterine system : a randomised controlled trial

    NARCIS (Netherlands)

    van der Heijden, Pahh; Geomini, Pmaj; Herman, M C; Veersema, S; Bongers, M Y

    OBJECTIVE: The objective was to assess whether patient-perceived pain during the insertion of the levonorgestrel-releasing intrauterine system (LNG-IUS) depends on the timing during the menstrual cycle. DESIGN: A stratified two-armed non-inferiority randomised controlled trial. SETTING: Large

  18. Evaluation of Dosing Guidelines for Use of Controlled-Release Codeine in Chronic Noncancer Plan

    Directory of Open Access Journals (Sweden)

    Alan Russell

    2003-01-01

    Full Text Available OBJECTIVE: The clinical utility of guidelines for conversion of patients from a combination analgesic preparation of acetaminophen 300 mg plus codeine 30 mg every 4 h to 6h as needed to scheduled controlled-release (CR codeine every 12 h was evaluated.

  19. Supramolecular Controlled Cargo Release via Near Infrared Tunable Cucurbit[7]uril-Gold Nanostars.

    Science.gov (United States)

    Han, Yanwei; Yang, Xiran; Liu, Yingzhu; Ai, Qiushuang; Liu, Simin; Sun, Chunyan; Liang, Feng

    2016-02-26

    The near infrared (NIR) absorption and average particle size of gold nanostars (GNSs) can be precisely controlled by varying the molar ratios of cucurbit[7]urils (CB[7]) and GNSs in aqueous solution. GNSs modified with CB[7] achieved high cargo loading with thermally activated release upon the NIR laser irradiation.

  20. EVALUATION OF BIOREMEDIATION STRATEGIES OF A CONTROLLED OIL RELEASE IN A WETLAND

    Science.gov (United States)

    A controlled