Changes in densities of hypothalamic mu opioid receptor during cupric acete-induced preovulatory lh surge in rabbit

Decrease in activity of hypothalamic beta-endorphin (beta-EP) is an important factor for inducing the preovulatory LH surge. To study whether hypothalamic mu opioid receptor is involved in this process, changes in densities of hypothalamic mu opioid receptors were observed in this study by autoradiography and image process during cupric acetate (CuAC)-induced preovulatory LH surge in rabbits. New Zealand female rabbits were injected 1% CuAC 0.9 ml or saline 0.9 ml and sacrificed at different times after the injection. The densities of mu opioid receptor in the medial basal hypothalamus (MBH) and the medial preoptic area (MPO) were measured. A transient increase in densities of MPO mu opioid receptor were observed 1 h after CuAC injection (P < 0.05). The densities of MPO mu opioid receptor decreased significantly before the onset of the LH surge (P < 0.05) and remained at a low level during the surge. The change in densities of mu opioid receptor in the MBH was similar to those in the MPO. No change was observed in the saline control group. There was a negative correlation between the changes in densities of MBH mu opioid receptor and serum LH levels in the process of LH surge. The results suggest that the decrease of hypothalamic mu opioid receptor may be involved in the preovulatory LH surge.     

Zinc Oxide Nanoparticles: Synthesis,Antimicrobial Activity and Food Packaging Applications

Zinc oxide (ZnO) is an inorganic compound widely used in everyday applications. ZnO is currently listed as a generally recognized as safe (GRAS) material by the Food and Drug Administration and is used as food additive. The advent of nanotechnology has led the development of materials with new properties for use as antimicrobial agents. Thus, ZnO in nanoscale has shown antimicrobial properties and potential applications in food preservation. ZnO nanoparticles have been incorporated in polymeric matrices in order to provide antimicrobial activity to the packaging material and improve packaging properties. This review presents the main synthesis methods of ZnO nanoparticles, principal characteristics and mechanisms of antimicrobial action as well as the effect of their incorporation in polymeric matrices. Safety issues such as exposure routes and migration studies are also discussed.     

Anticoagulant, Antioxidant and Antitumor Activities of Heterofucans from the Seaweed Dictyopteris delicatula

In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, uronic acid, and sulfate. The fucans F0.5v and F0.7v at 1.0 mg/mL showed high ferric chelating activity (～45%), whereas fucans F1.3v (0.5 mg/mL) showed considerable reducing power, about 53.2% of the activity of vitamin C. The fucan F1.5v presented the most prominent anticoagulant activity. The best antiproliferative activity was found with fucans F1.3v and F0.7v. However, F1.3v activity was much higher than F0.7v inhibiting almost 100% of HeLa cell proliferation. These fucans have been selected for further studies on structural characterization as well as in vivo experiments, which are already in progress.     

Antioxidant intake among Brazilian adults - The Brazilian Osteoporosis Study (BRAZOS): a cross-sectional study

Background  

Antioxidant nutrient intake and the lesser formation of free radicals seem to contribute to chronic diseases. The aim of the present study was to evaluate the intake profile of the main dietary antioxidants in a representative sample of the adult Brazilian population and discuss the main consequences of a low intake of these micronutrients on overall health.     

Solution blow spun titania nanofibers from solutions of high inorganic/organic precursor ratio

In this work titania nanofibers were produced from different precursor solutions by solution blow spinning. Hydrophilic polyvinylpyrrolidone, hydrophobic poly(vinyl acetate) and amorphous and semi-crystalline poly(lactic acid) polymers were used with green-solvents and titanium isopropoxide as the inorganic precursor. Hybrid nanofibers with high inorganic loading content were successfully produced from all precursor solutions. The fibers were calcined at different annealing temperatures for evaluation of phase transitions. The minimum temperature to obtain pure titania fiber was found to be 500 °C, as assessed by thermal characterization. Anatase was the unique polymorph formed at this annealing temperature. This is of paramount importance due to its photocatalytic character. Calcination at high temperatures showed that rutile slightly appeared at 600 °C for the polyvinylpyrrolidone-based system and showed a strong peak at 700 °C for all systems, co-existing with anatase as minor phase. The use of amorphous and semicrystalline poly(lactic acid) polymers did not influence the anatase crystal size and phase conversion. This was found to be dependent on the annealing temperature and medium acidity, as currently found in powder synthesis.     

包含负荷及系统动态的电力系统电压稳定仿真

本文提出一种对系统电压稳定进行详细仿真的方法，此方法考虑了系统及负荷动态的影响，诸如系统干扰、电动机力矩及滑差，变压器抽头的的换接、坚持Ｐ、Ｑ需要的负荷、抑制励磁以防止发电机过热，以及有电压偏移负反馈的ＳＶＣ等。由于是高阶次的非线性全模，作者采用一种既精确又快速的方法来进行积分，还应用了一种毋需经过亢介次矩阵求逆就可便捷地求解亢介次Ｊａｃｏｂｉ阵的方法。     

Polyaniline‐modified cellulose nanofibrils as reinforcement of a smart polyurethane

Segmented polyurethanes exhibiting shape memory properties were modified by the addition of polyaniline (PANI)‐coated cellulose nanofibrils (CNFs). The two‐phase structure of the polymer is responsible for the material's ability to ‘remember’ and autonomously recover its original shape after being deformed in response to an external thermal stimulus. PANI was grown on the surface of the CNFs via in situ polymerization. Modified nanocrystals were added to the segmented polyurethane in concentrations ranging from 0 to 15 wt%. The changes in the material properties associated with the percolation of the coated fibrils appear at higher concentrations than previously observed for non‐modified CNFs, which suggests that fibril agglomeration is occurring due to the PANI coating. The shape memory behavior of the composites is maintained at about the same level as that of the unfilled polyurethane only up to 4 wt% of fibrils. At higher concentrations, the rigidity of the nanofibrils as well as their interaction with the hard‐segment phase and the increasing difficulty of dispersing them in the polymer collaborate to produce early breakage of the specimens when stretched at temperatures above the melting point of the soft segments. Copyright © 2010 Society of Chemical Industry     

Design and characterization of PNVCL-based nanofibers and evaluation of their potential applications as scaffolds for surface drug delivery of hydrophobic drugs

In this work, nanofiber scaffolds for surface drug delivery applications were obtained by electrospinning poly(N-vinylcaprolactam) (PNVCL) and its blends with poly(ε-caprolactone) and poly(N-vinylcaprolactam)-b-poly(ε-caprolactone). The process parameters to obtain smooth and beadless PNVCL fibers were optimized. The average fibers diameter was less than 1 μm, and it was determined by scanning electron microscopy analyses. Their affinity toward water was evaluated by measuring the contact angle with water. The ketoprofen release behavior from the fibers was analyzed using independent and model-dependent approaches. The low values of the release exponent (n < 0.5) obtained for 20 and 42 °C, indicating a Fickian diffusion mechanism for all formulations. Dissolution efficiencies (DEs) revealed the effect of polymer composition, methodology used in the electrospinning process, and temperature on the release rate of ketoprofen. PNVCL/poly(N-vinylcaprolactam)-b-poly(ε-caprolactone)-based nanofibers showed greater ability to control the in vitro release of ketoprofen, in view of reduced kinetic constant and DE, making this material promising system for controlling release of hydrophobic drugs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48472.     

Poly(lactic acid)/poly(vinyl pyrrolidone) membranes produced by solution blow spinning: Structure,thermal, spectroscopic,and microbial barrier properties

Submicrometric and nanometric poly(lactic acid)/poly(vinyl pyrrolidone) (PLA/PVP) fibrous membranes containing 0, 5, 10, 15, and 20 wt % PVP, with or without 20 wt % Copaiba oil (Copaifera sp.), were produced by solution blow spinning (SBS), using polymer injection rate of 120 μL min^?1, gas pressure of 2.4 kPa, working distance of 20 cm, and collector rotation of 200 rpm. The morphological, thermal, and spectroscopic properties of these membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry (TG), and Fourier transform infrared spectroscopy (FTIR). A method for the evaluation of membrane microbial barrier properties based on resazurin colorimetric method was proposed. Results showed that the addition of both PVP and Copaiba oil produced thicker fibers; otherwise, there was no effect on morphology. Thermal analyses (TG and DSC) indicated the immiscible nature of polymer blends produced, also confirmed by the spectroscopic studies. Antimicrobial barrier properties were related to the antimicrobial effect of Copaiba oil, combined with it hydrophobic nature. The hydrophilic nature of PVP favored degradation of fiber mats, impairing barrier property when higher concentrations of PVP were added. Results indicate that produced spun mats can potentially be used in applications such as wound dressing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44802.