Distinguishing nanowire and nanotube formation by the deposition current transients

ABSTRACT: High aspect ratio Ni nanowires (NWs) and nanotubes (NTs) were electrodeposited inside ordered arrays of self-assembled pores (approximately 50 nm in diameter and approximately 50 um in length) in anodic alumina templates by a potentiostatic method. The current transients monitored during each process allowed us to distinguish between NW and NT formation. The depositions were long enough for the deposited metal to reach the top of the template and form a continuous Ni film. The overfilling process was found to occur in two steps when depositing NWs and in a single step in the case of NTs. A comparative study of the morphological, structural, and magnetic properties of the Ni NWs and NTs was performed using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry, respectively.     

Characterization of a multilayer film activated with Lactobacillus curvatus CRL705 bacteriocins

BACKGROUND: Bacteriocins produced by lactic acid bacteria offer enormous promise for food safety preservation. In this study an active multilayer film obtained by the incorporation of lactocin 705 and lactocin AL705, two bacteriocins produced by Lactobacillus curvatus CRL705 with antimicrobial activity against Lactobacillus plantarum CRL691 and Listeria innocua 7, respectively, was characterized for its potential application in active packaging technology. Film activity performance at different storage conditions, bacteriocins transfer into water and sunflower oil, and film surface properties were evaluated. RESULTS: Film activity against L. innocua 7 was maintained during 2, 4 and 6 weeks at 30, 10 and 5 °C respectively. At 30 and 10 °C, activity loss against L. plantarum CRL691 was observed on the second week of storage and after the fourth week at 5 °C. Results showed no significant difference for active multilayer film contact angle and seal properties compared to the control (without bacteriocins). A decrease in lactocin 705 inhibitory activity after sunflower oil contact was observed, while lactocin AL705 remained unaffected. After water contact, film activity was retained for both bacteriocins. CONCLUSIONS: As demonstrated by antimicrobial activity and physico‐mechanical properties retention, lactocin 705 and AL705 active multilayer film present potential for application in active packaging technology. Copyright © 2011 Society of Chemical Industry     

Poly(ether imide)s containing cyano substituents and thin films made from them

A series of poly(ether imide)s containing functional cyano groups has been prepared by polycondensation reaction of 2,6‐bis(m‐aminophenoxy)benzonitrile with different bis(ether dianhydride)s, such as 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]isopropane dianhydride, 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)‐phenyl]hexafluoroisopropane dianhydride, 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]cyclohexane dianhydride, and 3,3‐bis[4‐(3,4‐dicarboxyphenoxy) phenyl]phthalide dianhydride. The polymers were soluble in polar aprotic solvents and even in less polar solvents and were processed into thin films by casting their solutions. The properties of the polymers, particularly the crosslinking of macromolecular chains through cyano groups, were studied by using dynamic mechanical analysis (DMA), thermal stability, glass transition, and solubility measurements. Also, the molecular relaxations were evidenced by DMA and dielectric spectroscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Modeling and Optimization of Lactic Acid Production using Cashew Apple Juice as Substrate

The production of lactic acid by Lactobacillus casei B-442 was studied and modeled. Sugar feedstock was provided using cashew apple juice, an alternative glucose and fructose feedstock that proved to yield high concentrations of lactic acid. The fermentations were carried out in a 1-L fermenter under constant agitation (150 rpm) and controlled pH (6.5). Lactic acid production was evaluated through a dynamic study, varying the initial concentration of sugar in the range of 20 to 60 g/L. Biomass, reducing sugars, and lactic acid concentration were measured throughout the experiments. The highest production of lactic acid (59.3 g/L) was obtained operating the fermentation with 60 g/L of reducing sugar from the cashew apple juice. A rigorous kinetic model was developed for batch fermentation of cashew apple juice for lactic acid production by L. casei B-442. The growth of biomass and lactic acid production were affected by substrate limitation, substrate inhibition and lactic acid inhibition. The model assumed growth- and non-growth-associated lactic acid production and a term for microorganism death was also included in the model. Parameters of the kinetic model were determined based on experimental data by using the least mean squares method and Levenberg–Marquardt algorithm. The model validation was performed and the model was statistically able to fit the profiles for growth of biomass, sugar consumption and lactic acid production. The optimization of the process, using the model, was carried out and the optimum operating conditions aiming highest productivity, lowest production cost and highest gross profit are presented.     

Cashew Apple Juice as Substrate for Lactic Acid Production

The aim of the present work was to investigate the use of cashew apple juice as a low cost substrate for Lactobacillus casei B-442 cultivation and lactic acid production. Ammonium sulfate was employed as the only exogenous nitrogen source. The effect of cashew apple juice reducing sugars and ammonium sulfate concentration and the fermentation pH and temperature on biomass formation, lactic acid production, and productivity were evaluated. The highest productivity (2.36 g/L.h) was obtained applying 50 g/L of reducing sugar from the cashew apple juice supplemented with 6 g/L of ammonium sulfate. The process yield was about 95% when fermentation was carried out at 37 °C with pH controlled at pH 6.5 using NaOH (120 g/L).     

Maturation related phenolic compounds in cachaça aged in new oak barrels

Aging cachaça in wooden barrels improves its chemical and sensory profile and adds quality. Maturation of distilled spirits is influenced by factors such as the species of wood to make the barrels, degree of internal toasting, number of uses of the barrel and aging time. The level of maturation of distillates can be determined based on the concentration of age marker phenolic compounds extracted from the lignin of the wooden barrel, as well as their relationships with each other. This study characterises the aging process of cachaça by analysing the mechanism of lignin degradation during maturation in new oak barrels for up to 60 months in order to establish the relationship between the age of the distillate and the content of phenolic compounds extracted from the wood. The evaluation was based on the analyses of liginin derived compounds using high‐performance liquid chromatography. The level of maturation of aged cachaça can be characterised by evaluating the low molecular weight lignin‐derived phenolic substances. The total amount of benzoic acids (vanillic and syringic acids) can be taken into consideration for predicting the level of maturation of distillates. Based on the composition of maturation related congeners, it is likely that for cachaça, each year of aging in new oak barrels corresponds to approximately five years of aging for spirits in general. © 2020 The Institute of Brewing & Distilling     

Phenolic-rich extracts from Willowherb (Epilobium hirsutum L.) inhibit lipid oxidation but accelerate protein carbonylation and discoloration of beef patties

An extraction procedure of phenolics from Willowherb (Epilobium hirsutum L.) was optimized; extracts were characterized in terms of phenolic content, composition, and in vitro antioxidant activity. Additionally, the effect of 50, 200, and 800 ppm Willowherb extracts on the oxidative stability (formation of thiobarbituric acid-reactive substances, α-aminoadipic, and γ-glutamic semialdehydes) of beef patties was studied. Acetone (50 %) extract, rich in ellagic acid, myricetin, hydroxybenzoic, and hydroxycinnamic acids, had the highest phenolic content compared to methanol (25, 50, 75, and 100 %), acetone (100 %), or water extracts and displayed intense in vitro antioxidant properties. Lipid oxidation levels in processed beef patties with added Willowherb extract remained as similar to that of 100 ppm gallic acid. A dose-dependent effect of Willowherb extract was observed on protein carbonylation and myoglobin oxidation. The lack of correlation between lipid and myoglobin oxidation and the underlying mechanisms involved in the pro-oxidant action of phenolics on meat proteins are thoroughly discussed.