The Interaction Between N-Isopropylacrylamide-Acrylic Acid-Ethyl Methacrylate Thermosensitive Polymers and Cationic Surfactants

The interaction between cationic surfactants and isopropylacrylamide-acrylic acid-ethyl methacrylate (IPA:AA:EMA) terpolymers has been investigated using steady-state fluorescence and spectrophotometric measurements to assess the effect of the polymer composition on the aggregation process and terpolymers' thermosensitivities. Micropolarity studies using pyrene show that the interaction of cationic surfactants with IPA:AA:EMA terpolymers occurs at surfactant concentrations much smaller than that observed for the pure surfactant in aqueous solution. The critical aggregation concentration (CAC) values decrease with both the hydrocarbon length of the surfactant and the content of ethyl methacrylate. These results were interpreted as a manifestation of the increasing contribution of attractive hydrophobic and electrostatic forces between negatively charged polymer chains and positively charged surfactant molecules. The increase of ethyl methacrylate in the copolymers lowers the CAC due to the larger hydrophobic character of the polymer backbone. The cloud point determination reveals that the lower critical solution temperatures (LCST) depend strongly on the copolymer composition and surfactant nature. The binding of surfactants molecules to the polymer chain screens the electrostatic repulsion between the carboxylic groups inducing a conformational transition and the dehydration of the polymer chain.

Photodynamic inactivation of biofilms formed by Candida spp., Trichosporon mucoides, and Kodamaea ohmeri by cationic nanoemulsion of zinc 2,9,16,23-tetrakis(phenylthio)-29H, 31H-phthalocyanine (ZnPc)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Using b-tagging to enhance the supersymmetry reach of the CERN Large Hadron Collider

Assuming that supersymmetry is realized with parameters in the hyperbolic branch/focus point region of the minimal supergravity model, we show that by searching for multijet+E-T(miss) events with tagged b jets the reach of experiments at the LHC may be extended by as much as 20% from current projections. The reason for this is that gluino decays to third generation quarks are enhanced because the lightest neutralino has substantial Higgsino components. Although we were motivated to perform this analysis because the hyperbolic branch/focus point region is compatible with the recent determination of the relic density of cold dark matter, our considerations may well have a wider applicability since decays of gluinos to third generation quarks are favored in a wide variety of models.

Incorporation of a liquid crystal to enhance the luminescence properties of Langmuir-Blodgett films of OC1OC6-PPV

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Developing an Anchor system to enhance postural control

This article uses an anchor metaphor to explain the dynamic interplay between the human body's active uses of nonrigid tools to mediate information about its adjacent environment to enhance postural control. The author used an anchor system (ropes attached to varying weights resting on the floor) to test blindfolded adults who performed a restricted-balance task (30 s one-foot standing). Participants were tested while holding the anchors under a variety of weight conditions (125 g, 250 g, 500 g, and I kg) and again during a baseline condition (no anchors). When compared with the baseline condition, there was a significant reduction in the amount of body sway across the anchor conditions. The author found that mechanical support provided by the anchor system was secondary to its haptic exploratory function and that an individual can use the anchoring strategy with a dual purpose: for resting and for reorientation after intrinsic disruptions.

Use of cationic surfactant-xylenol orange indicator in metals complexometry by back-titration with EDTA.

The interaction of the xilenol orange and commercial disinfectant containing itself cationic-surfactant allowed the use indicator up to pH 11 by back-titration with EDTA, and the determination of total or partial concentration of metallic ions samples using the same indicator at the highest pH range.

Decoralin, a novel linear cationic alpha-helical peptide from the venom of the solitary eumenine wasp Oreumenes decoratus

A novel peptide, decoralin, was isolated from the venom of the solitary eumenine wasp Oreumenes decoratus. its sequence, Ser-Leu-Leu-Ser-Leu-Ile-Arg-Lys-Leu-Ile-Thr, was determined by Edman degradation and corroborated by solid-phase synthesis. This sequence has the characteristic features of linear cationic a-helical peptides; rich in hydrophobic and basic amino acids with no disulfide bond, and accordingly, it can be predicted to adopt an amphipathic a-helix secondary structure. In fact, the CD spectra of decoralin in the presence of TFE or SDS showed a high a-helical conformation content. In a biological evaluation, decoralin exhibited a significant broad-spectrum antimicrobial activity, and moderate mast cell degranulation and leishmanicidal activities, but showed virtually no hemolytic activity. A synthetic analog with C-terminal amidation showed a much more potent activity in all the biological assays. (c) 2007 Elsevier B.V. All rights reserved.

Tissue tolerance of diclofenac sodium encapsulated in liposomes after intramuscular administration

In this work the effect of the encapsulation of diclofenac sodium within liposomes on the reduction of the myotoxicity after intramuscular administration in rats was studied. Diclofenac sodium was encapsulated in small unilamellar liposomes obtained from phosphatidylcholine, cholesterol, and a-tocopherol (40:10:0.04 mM), and administered by intramuscular injection in the quadriceps femoral muscle of male Wistar rats. After a single dose of 0.2 mg diclofenac formulations the local tissue damage was assessed by plasma creatine kinase (CPK) activity and histological analysis. It was demonstrated that formulations containing free diclofenac produced a higher increase in CPK activity, while those encapsulated in liposomes exhibited CPK activity similar to the control groups. Histopathological analysis of local muscle tissue performed on the third and seventh days following the injection showed intense cellular damage when free drug solution was used, while encapsulation in liposome protected the tissue against the local tissue inflammation.

15d-PGJ2-loaded in nanocapsules enhance the antinociceptive properties into rat temporomandibular hypernociception

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal Behavior and Spectroscopic Study of Neutral and Cationic Mononuclear Cyclopalladated Compounds

The reactions of the precursor [Pd(N,C-dmba)(MeCN)2](NO 3) (1) (dmba = N,N-dimethylbenzylamine), with the proligands 3,5-dimethylpyrazole (Hdmpz), 2-quinolinethiol (qnSH) and 1,1′- bis(diphenylphosphine)ferrocene (dppf) afforded the compounds [Pd(N,C-dmba)(Hdmpz)(ONO2)]0.5CH2Cl2 (2), [Pd(N,C-dmba)(qnSH)(ONO2)] 0.5CH2Cl2 (3) and [Pd(N,C-dmba)(dppf)](NO3) (4), respectively. The mononuclear species 2,3 and 4 were characterized by elemental analysis, infrared spectroscopy, NMR and thermogravimetric analysis. The IR spectra show bands which are consistent with terminal monodentate nitrate group for 2-3 and ionic nitrate for 4. The 1H and 13C NMR data confirm that coordination of the organic ligands has occurred and the 31P{1H} NMR data for 4 clearly evidences the occurrence in solution of three cyclopalladated species with the dppf acting as a bridging ligand in two cases and as a chelate in one. The thermal behavior of compounds 1-4 suggests that complex 2 is the most stable. The X-ray diffractometry results show the formation of PdO from 1 and 2, Pd2OSO4 from 3, and of a mixture of PdO and Fe 2(PO4)3 from 4, as final decomposition products.

Liposomes and micro/nanoparticles as colloidal carriers for nasal drug delivery

The use of the nasal route for drug delivery has attracted much interest in recent years in the pharmaceutical field. Local and principally systemic drug delivery can be achieved by this route of administration. But the nasal route of delivery is not applicable to all drugs. Polar drugs and some macromolecules are not absorbed in sufficient concentration due to poor membrane permeability, rapid clearance and enzymatic degradation into the nasal cavity. Thus, alternative means that help overcome these nasal barriers are currently in development. Absorption enhancers such as phospholipids and surfactants are constantly used, but care must be taken in relation to their concentration. Drug delivery systems including liposomes, cyclodextrins, micro- and nanoparticles are being investigated to increase the bioavailability of drugs delivered intranasally. This review article discusses recent progress and specific development issues relating to colloidal drug delivery systems in nasal drug delivery. © 2006 Bentham Science Publishers Ltd.

Agronomic effectiveness of cationic phosphate impurities present in superphosphate fertilizers as affected by soil pH

The general concept that low-water-soluble phosphorus (P) fertilizers should be more agronomically effective when applied to acidic soils was developed based on sources containing mainly calcium (Ca)-P compounds, but it may not hold true for sources with different chemical composition. To obtain information related to this issue, two important iron (Fe)-potassium (K)-P compounds present in superphosphates [Fe 3 KH 8 (PO 4 ) 6·6H 2 O, H8, and Fe 3 KH 14 (PO 4 ) 8·4H 2 O, H14] were prepared and characterized. These P sources were used to provide 30 and 60 mg P kg -1 as neutral ammonium citrate (NAC)+H 2 O-soluble P. Reagent-grade monocalcium phosphate (MCP) was used as a standard P source with high water solubility with an additional rate of 120 mg P kg -1 included. Also, mixtures of both Fe-K-P compounds and MCP were prepared to provide 0, 25, 50, 75, and 100% of the total P as MCP. All sources were applied to a clayey loamy acid soil (pH 5.3) classified as Rhodic Kanhapludult. The soil was incubated at two rates (0 and 10 g kg -1 ) of lime, which resulted in pH 5.4 and 6.8. Upland rice was cultivated to maturity. The H14 compound confirmed to be a highly effective source of P for the rice plants at both soil pH, as opposed to the H8, which was poorly effective when applied alone. When mixed with water-soluble P (WSP), the H8 was able to provide P to the plants with the maximum yield of upland rice reached with 54.8 and 80.5% of WSP for pH 5.4 and 6.8, respectively. The high agronomic performance of the H14 compound clearly indicates that this low-water-soluble P source cannot be deemed as ineffective at high soil pH. Copyright © Taylor & Francis Group, LLC.

The mechanism of dephosphorylation of bis(2,4-dinitrophenyl) phosphate in mixed micelles of cationic surfactants and lauryl hydroxamic acid

(Figure Presented) Mixed micelles of cetyltrimethylammonium bromide (CTABr) or dodecyltrimethylammonium bromide (DTABr) and the α-nucleophile, lauryl hydroxamic acid (LHA) accelerate dephosphorylation of bis(2,4-dinitrophenyl) phosphate (BDNPP) over the pH range 4-10. With a 0.1 mole fraction of LHA in DTABr or CTABr, dephosphorylation of BDNPP is approximately 10 4-fold faster than its spontaneous hydrolysis, and monoanionic LHA - is the reactive species. The results are consistent with a mechanism involving concurrent nucleophilic attack by hydroxamate ion (i) on the aromatic carbon, giving an intermediate that decomposes to undecylamine and 2,4-dinitrophenol, and (ii) at phosphorus, giving an unstable intermediate that undergoes a Lossen rearrangement yielding a series of derivatives including N,N-dialkylurea, undecylamine, undecyl isocyanate, and carbamyl hydroxamate. © 2009 American Chemical Society.