A comprehensive investigation of dye–chitosan blended films for green chemistry applications

In this paper, the ability of chitosan film to remove dyestuff from wastewater was evaluated for environmental applications, using three commercial direct azo dyes. Two chitosan films were adopted: the standard one prepared following a well‐known procedure to form it, and a novel one, with a weakly acidic character. Moreover, to improve the adsorption process, the hydrophobic character of the films was investigated. The pH of the dye solutions was also changed, showing an excellent ability in dye removal at pH 12. The films were characterized by means of spectroscopic and morphologic methods to better understand the nature of interactions between dyes and chitosan chains. Swelling ratio measurements were also performed. All analyses suggest that all dyes showed a strong affinity to chitosan polymer chains, with the presence of extended hydrogen bonds and Van der Waals forces perturbing the chitosan network. Interestingly, very good results were obtained in recycling experiments related to the dyeing capacities of chitosan blended films in the presence of textiles. An ecofriendly application is thus presented in this paper. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45945.     

Latest developments in GaN-based quantum devices for infrared optoelectronics

In this work, we summarize the latest progress in intersubband devices based on GaN/AlN nanostructures for operation in the near-infrared. We first discuss the growth and characterization of ultra-thin GaN/AlN quantum well and quantum dot superlattices by plasma-assisted molecular-beam epitaxy. Then, we present the performance of nitride-based infrared photodetectors and electro-optical modulators operating at 1.55 μm. Finally, we discuss the progress towards intersubband light emitters, including the first experimental observation of intersubband photoluminescence in nitride nanostructures.     

Light and Strong SiC Networks

The directional freezing of microfiber suspensions is used to assemble highly porous (porosities ranging between 92% and 98%) SiC networks. These networks exhibit a unique hierarchical architecture in which thin layers with honeycomb‐like structure and internal strut length in the order of 1–10 μm in size are aligned with an interlayer spacing ranging between 15 and 50 μm. The resulting structures exhibit strengths (up to 3 MPa) and stiffness (up to 0.3 GPa) that are higher than aerogels of similar density and comparable to other ceramic microlattices fabricated by vapor deposition. Furthermore, this wet processing technique allows the fabrication of large‐size samples that are stable at high temperature, with acoustic impedance that can be manipulated over one order of magnitude (0.03–0.3 MRayl), electrically conductive and with very low thermal conductivity. The approach can be extended to other ceramic materials and opens new opportunities for the fabrication of ultralight structures with unique mechanical and functional properties in practical dimensions.     

<Emphasis Type="Italic">Myzus persicae</Emphasis> is Arrested More by Blends Than by Individual Compounds Elevated in Headspace of PLRV-Infected Potato

Volatiles from potato plants (Solanum tuberosum L.) infected with Potato leaf roll virus (PLRV) attract and arrest the principal vector of PLRV, the green peach aphid, Myzus persicae (Sulzer), more strongly than volatiles from non-infected plants. The total concentration of volatiles detectable in the headspace of PLRV-infected plants is greater than that in the headspace of non-infected controls, and the relative composition is altered. To determine the basis of the aphid response to PLRV-infection-induced volatiles from potato, behavioral bioassays were conducted. We measured arrestment of aphids by individual components, by synthetic blends of these, and by a naturally occurring blend by using an emigration rate bioassay, and quantified observations of the behavior of individual aphids. The components tested were those elevated at least twofold in response to PLRV infection. Before conducting the behavioral bioassays, electroantennograms confirmed the electrophysiological responses of aphids to the components of the blend. For bioassays, individual compounds or blends were tested by applying them in solution to paper strips at concentrations designed to mimic those present in the headspace of the plants. All bioassays were conducted by placing aphids on fine-mesh screening positioned above treated paper strips. Arrestment was measured by placing groups of 30 aphids directly over the treated strips and counting the number moving away at 10-min intervals for 50 min. Among the individual compounds tested, only β-pinene was a mild arrestant. The other compounds did not elicit significant changes in arrestment or behavior at a range of physiologically relevant concentrations. In contrast, synthetic blends that mimicked the concentration and composition present in headspace of PLRV-infected potato plants arrested aphids significantly more strongly than blends mimicking volatiles from the headspace of non-infected plants. The naturally occurring blend collected from headspace of PLRV-infected plants also arrested M. persicae more strongly than the blend collected from headspace of non-infected plants. Aphid behavior was quantified by directly observing individual aphids and recording their activities during a 5-min period on screening above strips treated with test materials. Few differences in time budgets were observed among aphids exposed to individual components, but synthetic blends and trapped headspace volatiles from PLRV-infected plants resulted in significantly less time spent walking by aphids than synthetic blends and trapped headspace from non-infected controls. Our results indicate that arrestment of M. persicae by PLRV-infected plants requires the blend of volatile organic compounds released by these plants and is not produced in response to a single compound.     

The Drying of Pyridine Hydrobromide

1 INTRODUCTIONThe drying of fine chemicals and pharmaceuticals is dominated by a number of special factorscompared to the drying of bulk chemicals.These include:very high value of product;lowthroughputs(typically,100 kg·h~(-1));materials that frequently possess toxic properties andare often sticky,pasty and difficult to handle when wet;the moisture to be evaporated ofteninvolves solvents;and multipurpose processing plants.     

Role of fermentative and antioxidant metabolisms in the induction of core browning in controlled‐atmosphere stored pears

Pears (Pyrus communis L cv Blanquilla) were stored at various CO₂ concentrations to induce core browning. The severity of core browning and the products and enzymes associated with fermentative and antioxidant metabolisms were determined immediately after harvest and in healthy and damaged fruits after storage. The incidence and severity of brown core increased with CO₂ concentration. Acetaldehyde and ethanol concentrations and alcohol dehydrogenase (ADH, EC 1.1.1.1) activity increased in all fruits during storage, but more in fruits with brown core than in healthy fruits. Pyruvate decarboxylase (PDC, EC 4.1.1.1) activity decreased slightly during this time. Ascorbate contents decreased whereas glutathione concentrations increased during storage in fruits with brown core compared to the same fruits at harvest. Superoxide dismutase (SOD, EC 1.15.11) activity increased during storage but was not affected by brown core. In contrast, a significant increase in both ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2) activities and a significant decrease in catalase (CAT, EC 1.11.1.6) activity were found in damaged fruits. Malonaldehyde (MDA) and 4‐hydroxyalkenal (4‐HNE) contents increased significantly in the damaged fruits as a result of peroxidation. Collectively, our results suggest that brown core in pears is indirectly correlated with fermentation and involves oxidative damage which may be a causal factor in brown core development. © 2001 Society of Chemical Industry     

Changes in chemical composition and nutritional quality of fried sardine (Clupea pilchardus) produced by frozen storage and microwave reheating

Modifications in proximate composition, fatty acids, amino acids and –SH groups content, as well as changes in solubility and nutritional quality of protein, were studied in fillets of sardine (Clupea pilchardus) that had been successively pan-fried, frozen stored and reheated by two different means, namely conventional oven and microwave oven. Upon pan-frying in olive oil the sardine absorbed C18: 1(n-9) and C18: 2(n-6) and lost saturated (SFA) and polyunsaturated fatty acids (PUFA); this loss continued upon reheating, and as a consequence the percentage of MUFA increased compared to the just-fried sardine. A loss of water was observed during all processes. Upon frying there was a decrease of cyst(e)ine. Upon reheating by both microwave and conventional oven, methionine decreased; however, cyst(e)ine only decreased with the use of a conventional oven. A loss of –SH groups was recorded during frying and this phenomenon continued upon reheating. Biological value (BV) together with net protein utilisation (NPU) decreased upon both frying and reheating. © 1997 SCI.