Styrene ATRP using the new initiator 2,2,2‐tribromoethanol: Experimental and simulation approach

Atom transfer radical polymerization (ATRP) is a powerful technique for the controlled synthesis of polymers, and one of the most important ATRP characteristics is the possibility to produce functionalized polymers. 2,2,2‐Tribromoethanol appears as a promising initiator for the ATRP process, because it allows the production of polymers with end hydroxyl groups, making it easy for copolymerization with biomonomers. This article explores, in experimental and computational level, the styrene ATRP using 2,2,2‐tribromoethanol to understand how this new initiator behaves, and presents a powerful tool to predict the polymer properties for different operating conditions. Simulations and experimental results showed that polymers with high molecular weight and low PDI can be simultaneously obtained using 2,2,2‐tribromoethanol as initiator. For all operational conditions, the reaction was fast and polydispersity values kept lower than 1.4, confirming the “living”/controlled characteristic. The polymers produced contain hydroxyl as functional group and in some operating conditions, PDI values of 1.1 was obtained, even at high monomer conversion. POLYM. ENG. SCI., 55:2270–2276, 2015. © 2015 Society of Plastics Engineers     

A general hybrid semi-parametric process control framework

A general hybrid semi-parametric process control framework is proposed in this study. The motivation was the integration of different levels of knowledge systems into a general hybrid semi-parametric control structure, of which the general linear controller or the PID controller are, for instance, particular cases.Several hybrid semi-parametric control structure variants and tuning methods are benchmarked in relation to a simulated bioprocess control problem, namely closed-loop control of the biomass concentration through manipulation of the substrate feeding rate, coupled with the closed-loop control of the dissolved oxygen concentration through the stirring velocity. The results demonstrate that (i) due to the hybrid approach the control loop can be closed without any additional identification experiments; (ii) the incorporation of different types of knowledge can enhance the controller performance, when compared to structures without a priori knowledge; (iii) knowledge incorporation seems to facilitate the tuning of the controller; and (iv) the control action can be analyzed in relation to structural information incorporated into the hybrid controller.     

Assessment of multifunctional activity of bioactive peptides derived from fermented milk by specific Lactobacillus plantarum strains

Milk-derived bioactive peptides with a single activity (e.g., antioxidant, immunomodulatory, or antimicrobial) have been previously well documented; however, few studies describe multifunctional bioactive peptides, which may be preferred over single-activity peptides, as they can simultaneously trigger, modulate, or inhibit multiple physiological pathways. Hence, the aim of this study was to assess the anti-inflammatory, antihemolytic, antioxidant, antimutagenic, and antimicrobial activities of crude extracts (CE) and peptide fractions (<3 and 3–10 kDa) obtained from fermented milks with specific Lactobacillus plantarum strains. Overall, CE showed higher activity than both peptide fractions (<3 and 3–10 kDa) in most of the activities assessed. Furthermore, activity of <3 kDa was generally higher, or at least equal, to the 3 to 10 kDa peptide fractions. In particular, L. plantarum 55 crude extract or their fractions showed the higher anti-inflammatory (723.68–1,759.43 μg/mL of diclofenac sodium equivalents), antihemolytic (36.65–74.45% of inhibition), and antioxidant activity [282.8–362.3 µmol of Trolox (Sigma-Aldrich, St. Louis, MO) equivalents]. These results provide valuable evidence of multifunctional role of peptides derived of fermented milk by the action of specific L. plantarum strains. Thus, they may be considered for the development of biotechnological products to be used to reduce the risk of disease or to enhance a certain physiological function.     

Imaging Upconverting Polymersomes in Cancer Cells: Biocompatible Antioxidants Brighten Triplet–Triplet Annihilation Upconversion

Light upconversion is a very powerful tool in bioimaging as it can eliminate autofluorescence, increase imaging contrast, reduce irradiation damage, and increase excitation penetration depth in vivo. In particular, triplet–triplet annihilation upconverting (TTA‐UC) nanoparticles and liposomes offer high upconversion efficiency at low excitation power. However, TTA‐UC is quenched in air by oxygen, which also leads to the formation of toxic singlet oxygen. In this work, polyisobutylene‐monomethyl polyethylene glycol block copolymers are synthesized and used for preparing polymersomes that upconvert red light into blue light in absence of oxygen. In addition, it is demonstrated that biocompatible antioxidants such as l ‐ascorbate, glutathionate, l ‐histidine, sulfite, trolox, or even opti‐MEM medium, can be used to protect the TTA‐UC process in these polymersomes resulting in red‐to‐blue upconversion under aerobic conditions. Most importantly, this approach is also functional in living cells. When A549 lung carcinoma cells are treated with TTA‐UC polymersomes in the presence of 5 × 10^?3 m ascorbate and glutathionate, upconversion in the living cells is one order of magnitude brighter than that observed without antioxidants. These results propose a simple chemical solution to the issue of oxygen sensitivity of TTA‐UC, which is of paramount importance for the technological advancement of this technique in biology.     

Retrieving middle-infrared reflectance for burned area mapping in tropical environments using MODIS

The ephemeral character of the radiative signal together with the presence of aerosols imposes severe limitations on the use of classical approaches, e.g. based on red and near-infrared, to discriminate between burned and unburned surfaces in tropical environments. Surface reflectance in the middle-infrared (MIR) has been used to circumvent these difficulties because the signal is virtually unaffected by the presence of aerosols associated to biomass burning. Retrieval of the MIR reflected component from the total signal is, however, a difficult problem because of the presence of a diversity of radiance sources, namely the surface reflected solar irradiance and the surface emitted radiance that may reach comparable magnitude during daytime. The method proposed by Kaufman and Remer (1994) to retrieve surface MIR reflectance presents the advantage of not requiring auxiliary datasets (e.g. atmospheric profiles) nor major computational means (e.g. for solving radiative transfer models). Nevertheless, the method was specifically designed to retrieve MIR reflectance over dense dark forests in the middle latitudes and, as shown in the present study, severe problems may arise when applying it beyond the range of validity, namely for burned area mapping in tropical environments. The present study consists of an assessment of the performance of the method for a wide range of atmospheric, geometric and surface conditions and of the usefulness of extracted surface reflectances for burned area discrimination. Results show that, in the case of tropical environments, there is a significant decrease in performance of the method for high values of land surface temperature, especially when associated with low sun elevation angles. Burned area discrimination is virtually impaired in such conditions, which are often present when using data from instruments on-board polar orbiters, namely MODIS in Aqua and Terra, to map burned surfaces over the Amazon forest and “cerrado” savanna regions.     

Brillouin Optical Time-Domain Analysis of Fiber-Optic Parametric Amplifiers

We carried out distributed measurements of the longitudinal gain of fiber-optical parametric amplifiers using a novel sensing technique based on Brillouin optical time-domain analysis. Using this technique, we successfully characterized different gain behaviors in the linear and the saturation regimes. In addition, we demonstrated the recently predicted gain reciprocity at opposite ends of the amplifier span     

Rapid method for the determination of organic acids in wine by capillary electrophoresis with indirect UV detection

A capillary electrophoresis method for organic acids in wine was developed and validated. The optimal electrolyte consisted of 10 mmol/L 3,5-dinitrobenzoic acid (DNB) at pH 3.6 containing 0.2 mmol/L cetyltrimethylammonium bromide as flow reverser. DNB was chosen because it has an effective mobility similar to the organic acids under investigation, good buffering capacity at pH 3.6, and good chromophoric characteristics for indirect UV-absorbance detection at 254 nm. Sample preparation involved dilution and filtration. The method showed good performance characteristics: Linearity at 6 to 285 mg/L (r > 0.99); detection and quantification limits of 0.64 to 1.55 and 2.12 to 5.15 mg/L, respectively; separation time of less than 5.5 min. Coefficients of variation for ten injections were less than 5% and recoveries varied from 95% to 102%. Application to 23 samples of Brazilian wine confirmed good repeatability and demonstrated wide variation in the organic acid concentrations.