Multiple vesicular morphologies in AB/AC diblock copolymer complexes through hydrogen bonding interactions

We report for the first time multiple vesicular morphologies in block copolymer complexes formed in aqueous media via hydrogen bonding interactions. A model AB/AC diblock copolymer system consisting of polystyrene-block- poly(acrylic acid) (PS-b-PAA) and polystyrene-block-poly(ethylene oxide) (PS-b-PEO) was examined using transmission electron microscopy, small-angle X-ray scattering, and dynamic light scattering. The complexation and morphological transitions were driven by the hydrogen bonding between the complementary binding sites on PAA and PEO blocks of the two diblock copolymers. Upon the addition of PS-b-PEO, a variety of bilayer aggregates were formed in PS-b-PAA/PS-b-PEO complexes including vesicles, multilamellar vesicles (MLVs), thick-walled vesicles (TWVs), interconnected compound vesicles (ICCVs), and irregular aggregates. Among these aggregates, ICCVs were observed as a new morphology. The morphology of aggregates was correlated with respect to the molar ratio of PEO to PAA. At [EO]/[AA] = 0.5, vesicles were observed, while MLVs were obtained at [EO]/[AA] = 1. TWVs and ICCVs were formed at [EO]/[AA] = 2 and 6, respectively. When [EO]/[AA] reached 8 and above, only irregular aggregates appeared. These findings suggest that complexation between two amphiphilic diblock copolymers is a viable approach to prepare polymer vesicles in aqueous media.

Needleless electrospinning : influences of fibre generator geometry

The fibre generator shape and dimension are key factors affecting the needleless electrospinning process and fibre fineness. In this work, cylinder with rounded rim, disc and ball were used as spinnerets to electrospin polyvinyl alcohol and polyacrylonitrile solutions. A finite element method was used to analyse how the spinneret geometry affected the electric field generated during electrospinning and the associated changes in fibre diameter and productivity. For cylinder spinnerets, increasing the rim radius reduced the discrepancy of electric field intensity between the cylinder end and middle area, which affected the fibre productivity. The electrospinning failed to operate when the rim radius was over 20 mm. With decreasing cylinder diameter, the electric field intensity in the middle area increased, improving the fibre productivity. Thinner disc spinnerets increased the electric field intensity, resulting in finer nanofibres and higher productivities. Ball spinnerets produced evenly distributed electric field, but failed to electrospin fibres when the diameters were below 60 mm. It has been found that strong and narrowly distributed electric field in the fibre-generating area can significantly facilitate the mass production of quality nanofibres.

Undergraduate electronics students' use of home experiment kits for distance education

Laboratory practicals form an essential component in any electronics or electrical engineering course. Many students choose to study engineering by means of distance education. Providing such students with effective and manageable practical experience has always been a significant challenge for those involved in providing distance education. Our university has employed an experimental electronics kit for teaching laboratory skills to distance-education students over the past several years. The chief limitation of the early kit was the inability to use it for performing AC experiments without an additional AC signal generator and an oscilloscope. We now supply distance-education students with the original components pack, and an additional “HELP” kit which contains the signal generator, PC-oscilloscope, a basic multimeter, logic probe, software and documentation. The combined kits allow these students to perform basic DC and AC electronics experiments at home in both freshman and sophomore electronics courses. A more recent development is introducing a small robot platform intended to enhance the student experience and interest in electronics and mechatronics, while still covering the basic skills necessary for the engineer-in-training. Distance-education students receive an updated experimental kit containing the robot, other equipment and components to allow them to complete a fuller suite of practical exercises in electronics in their first two years of study. Within this paper, we present these developments in our HELP kit and also make comparisons between on-campus and off-campus performance.

Reperfusion-induced myocardial dysfunction is prevented by endogenous annexin-A1 and its N-terminal-derived peptide Ac-ANX-A12-26

BACKGROUND AND PURPOSE : Annexin-A1 (ANX-A1) is an endogenous, glucocorticoid-regulated anti-inflammatory protein. The N-terminal-derived peptide Ac-ANX-A12–26 preserves cardiomyocyte viability, but the impact of ANX-A1-peptides on cardiac contractility is unknown. We now test the hypothesis that ANX-A1 preserves post-ischaemic recovery of left ventricular (LV) function.

EXPERIMENTAL APPROACH : Ac-ANX-A12–26 was administered on reperfusion, to adult rat cardiomyocytes as well as hearts isolated from rats, wild-type mice and mice deficient in endogenous ANX-A1 (ANX-A1–/–). Myocardial viability and recovery of LV function were determined.

KEY RESULTS: Ischaemia–reperfusion markedly impaired both cardiomyocyte viability and recovery of LV function by 60%. Treatment with exogenous Ac-ANX-A12–26 at the onset of reperfusion prevented cardiomyocyte injury and significantly improved recovery of LV function, in both intact rat and wild-type mouse hearts. Ac-ANX-A12–26 cardioprotection was abolished by either formyl peptide receptor (FPR)-nonselective or FPR1-selective antagonists, Boc2 and cyclosporin H, but was relatively insensitive to the FPR2-selective antagonist QuinC7. ANX-A1-induced cardioprotection was associated with increased phosphorylation of the cell survival kinase Akt. ANX-A1−/− exaggerated impairment of post-ischaemic recovery of LV function, in addition to selective LV FPR1 down-regulation.

CONCLUSIONS AND IMPLICATIONS : These data represent the first evidence that ANX-A1 affects myocardial function. Our findings suggest ANX-A1 is an endogenous regulator of post-ischaemic recovery of LV function. Furthermore, the ANX-A1-derived peptide Ac-ANX-A12–26 on reperfusion rescues LV function, probably via activation of FPR1. ANX-A1-based therapies may thus represent a novel clinical approach for the prevention and treatment of myocardial reperfusion injury.

O Supremo Tribunal Federal para além das Ações Diretas de Inconstitucionalidade

Este livro é resultado da pesquisa conduzida no âmbito do “Núcleo de Justiça e Constituição” da Escola de Direito de São Paulo da Fundação Getulio Vargas – FGV DIREITO SP. A pesquisa foi realizada por integrantes do Núcleo e com financiamento da Fapesp entre março de 2012 e fevereiro de 2013. Teve como objetivo analisar a atuação do Supremo Tribunal Federal (STF) enquanto Corte recursal, função exercida especialmente por meio do julgamento de recursos extraordinários. O nosso estudo examina o processo de tomada de decisão do STF nos recursos extraordinários julgados em Plenário, de 5 de setembro de 2007 a 1º de setembro de 2009. Esse é o maior período no qual a composição do Tribunal permaneceu estável desde 2000. Nesse intervalo de tempo, integravam o STF as Ministras e os Ministros: Celso de Mello, Marco Aurélio, Gilmar Mendes, Ellen Gracie, Carlos Britto, Cezar Peluso, Eros Grau, Joaquim Barbosa, Ricardo Lewandowski, Cármen Lúcia e Menezes Direito. Optou-se por investigar somente as decisões tomadas em sede de Plenário, por sua relevância qualitativa.

AC Biosusceptometry as a Tool for Monitoring the Gastrointestinal Transit of Multiparticulate Drug Delivery System

Drug delivery systems based on natural polysaccharides, such as chitosan (CS) and pectin (PC), rather than on synthetic polymers, have been widely studied. Some reasons for that are low toxicity and costs and high biodegradability of the formers. A multiparticulate system based on CS and PC was developed in our laboratories, including the addition of an enteric polymer, cellulose acetate phtalate (CAP). Such improvement promoted stronger gastric and enteric resistances, as assessed in vitro, making the systems more selective to enzymatic degradation in the colon. Although in vitro dissolution tests can simulate some properties concerning the gastrointestinal transit (GT), collaborating to characterize the systems behavior in the biological fluids, frequently they do not result in satisfactory in vitro/in vivo correlations. The objective of this work was to follow in vivo the GT of the particles developed by means of AC biosusceptometry (ACB), a non-invasive and of low cost methodology. The particles containing ferrite in powder form were prepared by complex coacervation using an ideal 3:1:1 mass ratio for PC:CS:CAP. The magnetic particles were administered to healthy volunteers by oral route. The GT was monitored by using multi-sensor ACB system and the signal acquisition was performed every IS min until the colonic region was reached. By means of ACB technique, it was possible to acquiring images generated by the magnetic particles within the whole gastrointestinal tract including the colonic region. Variable particles transit times were observed among the volunteers, but without interference on the mapping of the particles until the colonic region. The particles were able to produce magnetic field strong enough to generate signals adequate for mapping the particles. The results suggest that integral particles reached the colon, after they resisted against gastric and enteric media. Studies associating transit time and in vivo drug release are in development in order to confirm the efficiency of the systems.

Analysis of the E-J Curve of HTS Tapes Under DC and AC Magnetic Fields at 77 K

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

DC and AC side harmonics in CCC converters

The capacitor-commutated converter (CCC) has frequently been used in the conception of HVDC systems connected to busbars with low short circuit level. This alternative arrangement, in substitution to the conventional ones, guarantees less sensitive operational conditions to problems related with the commutation failure in the inverters besides supplying part of the reactive energy to be compensated. Studies related with its performance in steady and transient states have been presented in several works, however its behavior as harmonic source is still little explored. This work presents preliminary studies focusing the generation of characteristic harmonics by this type of converter. Subjects related with the amplification of the harmonic magnitudes are investigated and compared considering similar arrangements of conventional static converters (LCC) and CCC schemes. It is also analyzed the harmonic generation on the dc side of the installation and its influence on the ac side harmonics. The results are obtained from simulations in the time domain in PSpice environment and they clearly illustrate the operational differences between the L CC and the CCC schemes with regard to characteristic harmonic generation.

DCM Boost interleaved converter for operation in AC and DC to trolleybus application

This paper is based on the development and experimental analysis of a DCM Boost interleaved converter suitable for application in traction systems of electrical vehicles pulled by electrical motors (Trolleybus), which are powered by urban DC or AC distribution networks. This front-end structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency. The architecture of proposed converter is composed by five boost power cells in interleaving connection, operating in discontinuous conduction mode. Furthermore, the converter can operate as AC-DC converter, or as DC-DC converter providing the proper DC output voltage range required by DC or AC adjustable speed drivers. Therefore, when supplied by single-phase AC distribution networks, and operating as AC-DC converter, it is capable to provide high power factor, reduced harmonic distortion in the input current, complying with the restrictions imposed by the IEC 61000-3-4 standards. The digital controller has been implemented using a low cost FPGA and developed totally using a hardware description language VHDL and fixed point arithmetic. Thus, two control strategies are evaluated considering the compliance with input current restrictions imposed by IEC 61000-3-4 standards, the regular PWM modulation and a current correction PWM modulation. In order to verify the feasibility and performance of the proposed system, experimental results from a 15 kW low power scale prototype are presented, operating in DC and AC conditions.

Efficient method for AC transmission network expansion planning

A combinatorial mathematical model in tandem with a metaheuristic technique for solving transmission network expansion planning (TNEP) using an AC model associated with reactive power planning (RPP) is presented in this paper. AC-TNEP is handled through a prior DC model while additional lines as well as VAr-plants are used as reinforcements to cope with real network requirements. The solution of the reinforcement stage can be obtained by assuming all reactive demands are supplied locally to achieve a solution for AC-TNEP and by neglecting the local reactive sources, a reactive power planning (RPP) will be managed to find the minimum required reactive power sources. Binary GA as well as a real genetic algorithm (RCA) are employed as metaheuristic optimization techniques for solving this combinatorial TNEP as well as the RPP problem. High quality results related with lower investment costs through case studies on test systems show the usefulness of the proposal when working directly with the AC model in transmission network expansion planning, instead of relaxed models. (C) 2010 Elsevier B.V. All rights reserved.

Mesoscopic structure evidenced by AC dielectric nonlinearities in Sr(0.75)Ba(0.25)Nb(2)O(6) relaxor ferroelectric thin films

The AC electric field and temperature dependences of the dielectric permittivity for strontium barium niobate (Sr(0.75)Ba(0.25)Nb(2)O(6)) relaxor ferroelectric thin films have been investigated. The results indicate the existence of a true mesoscopic structure evidenced by the nonlinear dielectric response of these films, which is similar to those observed for bulk relaxor ferroelectrics. A tendency for a temperature dependent crossover from a linear to a quadratic behaviour of the dielectric nonlinearity was observed, indicating an evolution from paraelectric to glass-like behaviour on cooling the samples towards the freezing temperature transition.