PRODUCTS OF CHLOROPHYLL PHOTODEGRADATION–1. DETECTION and SEPARATION

Abstract— The photodegradative fate of ¹⁴C-radiolabelled phaeophytin a adsorbed on hydrophobic particles in an aqueous suspension is followed. An approximate mass balance is made for the hydrophilic, hydrophobic and CO, fractions. In addition, components of the colourless hydrophilic fraction produced from photodegrading chlorophyll a, phaeophytin a, phaeophorbide a and chlorophyll b are detected and separated using reverse-phase ion-pair and ion-exclusion HPLC with UV detection. The increase in the hydrophilic molecules and the decrease in chlorophyll a are measured as the photodegradation proceeds.     

Polyaniline decorated graphene oxide on sulfonated poly(ether ether ketone) membrane for direct methanol fuel cells application

In direct methanol fuel cells (DMFC), methanol crossover is a major issue which has reduced the performance of polymer electrolyte membrane (PEM) for energy generation. In this study, graphene oxide (GO) and conductive polyaniline decorated GO (PANI-GO) were used as additives in fabrication of sulfonated poly(ether ether ketone) (SPEEK) nanocomposite PEM membrane to reduce methanol crossover. PANI-GO was synthesized by in situ polymerization method and the formation of PANI coated GO nanostructures was confirmed by surface morphology and crystallinity analysis. The membrane morphology and topography analysis confirmed that GO and PANI-GO were well dispersed on the surface of SPEEK membrane. 0.1 wt% PANI-GO modified SPEEK nanocomposite membrane exhibited the highest water uptake and ion exchange capacity of 40% and 1.74 meq g^?1, respectively. The oxidative stability of the nanocomposite membranes also improved. Lower methanol permeability of 4.33 × 10^?7 cm^?2S^?1 was noticed for 0.1 wt% PANI-GO modified SPEEK membrane. PANI-GO modified SPEEK membrane enhanced the proton conductivity, which was due to the existence of acidic and hydrophilic group present in PANI and GO. PANI-GO modified SPEEK membrane held higher selectivity of 1.94 × 10⁴ S cm^?3 s^?1. Overall, these studies revealed that PANI-GO modified SPEEK membrane is a potential material for DMFC applications.     

Recent Studies on Berry Bioactives and Their Health-Promoting Roles

Along with the increased knowledge about the positive health effects of food bioactives, the eating habits of many individuals have changed to obtain higher nutritional benefits from foods. Fruits are among the most preferred food materials in this regard. In particular, berry fruits are important sources in the diet in terms of their high nutritional content including vitamins, minerals, and phenolic compounds. Berry fruits have remedial effects on several diseases and these health-promoting impacts are associated with their phenolic compounds which may vary depending on the type and variety of the fruit coupled with other factors including climate, agricultural conditions, etc. Most of the berries have outstanding beneficial roles in many body systems of humans such as gastrointestinal, cardiovascular, immune, and nervous systems. Furthermore, they are effective on some metabolic disorders and several types of cancer. In this review, the health-promoting effects of bioactive compounds in berry fruits are presented and the most recent in vivo, in vitro, and clinical studies are discussed from a food science and nutrition point of view.     

Comparative study on the performance of co-extruded hollow fiber solid oxide fuel cell fuelled with hydrogen and methane

Journal of Solid State Electrochemistry - In this study, the effects of two fuel types, i.e., hydrogen and methane on the electrochemical performance of the co-extruded triple layer hollow fiber,...     

Star polymers by photoinduced copper‐catalyzed azide–alkyne cycloaddition click chemistry

Well‐defined star polymers consisting of tri‐, tetra‐, or octa‐arms have been prepared via coupling‐onto strategy using photoinduced copper(I)‐catalyzed 1,3‐dipolar cycloaddition click reaction. An azide end‐functionalized polystyrene and poly(methyl methacrylate), and an alkyne end‐functionalized poly(ε‐caprolactone) as the integrating arms of the star polymers are prepared by the combination of controlled polymerization and nucleophilic substitution reactions; whereas, multifunctional cores containing either azide or alkyne functionalities were synthesized in quantitatively via etherification and ring‐opening reactions. By using photoinduced copper‐catalyzed azide–alkyne cycloaddition (CuAAC) click reaction, reactive linear polymers are simply attached onto multifunctional cores to form corresponding star polymers via coupling‐onto methodology. The chromatographic, spectroscopic, and thermal analyses have clearly demonstrated that successful star formations can be obtained via photoinduced CuAAC click reaction. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1687–1695     

Prevention of Enzymatic Browning by Natural Extracts and Genome-Editing: A Review on Recent Progress

Fresh fruits and vegetable products are easily perishable during postharvest handling due to enzymatic browning reactions. This phenomenon has contributed to a significant loss of food quality and appearance. Thus, a safe and effective alternative method from natural sources is needed to tackle enzymatic browning prevention. The capabilities of natural anti-browning agents derived from plant- and animal-based resources in inhibiting enzymatic activity have been demonstrated in the literature. Some also possess strong antioxidants properties. This review aims to summarize a recent investigation regarding the use of natural anti-browning extracts from different sources for controlling the browning. The potential applications of genome-editing in preventing browning activity and improving postharvest quality is also discussed. Moreover, the patents on the anti-browning extract from natural sources is also presented in this review. The information reviewed here could provide new insights, contributing to the development of natural anti-browning extracts and genome-editing techniques for the prevention of food browning.     

Performance enhancement of Absolute Polar Duty Cycle Division Multiplexing with Dual-Drive Mach-Zehnder-Modulator in 40 Gbit/s optical fiber communication systems

We modeled and analyzed a method to improve receiver sensitivity of the Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) transmission system by using Dual-Drive Mach-Zehnder-Modulator (DD-MZM). It is found that by optimizing the bias voltage in DD-MZM, the sensitivity of the AP-DCDM can be improved. The optimizations lead towards the larger eye opening. As opposed to the previous work, in terms of receiver sensitivity and dispersion tolerance, similar performance for all channels was achieved. In comparison to the previously reported AP-DCDM system, this work resulted in almost 3.6 dB improvement of the receiver sensitivity, came together with acceptable chromatic dispersion tolerance.     

Continuum reconstruction of the pore scale microstructure for Fontainebleau sandstone

A stochastic geometrical modeling technique is used to reconstruct a laboratory scale Fontainebleau sandstone with a sidelength of 1.5 cm. The model reconstruction is based on crystallite properties and diagenetic parameters determined from two-dimensional images. The three-dimensional pore scale microstructure of the sandstone is represented by a list of quartz crystallites defined geometrically and placed in the continuum. This allows generation of synthetic μ-CT images of the rock model at arbitrary resolutions. Quantitative microstructure comparison based on Minkowski functionals, two-point correlation function and local porosity theory indicates that this modeling technique can provide more realistic and accurate models of sandstones than many existing techniques used currently. Synthetic μ-CT images at different resolutions from a laboratory scale model of Fontainebleau sandstone are made available to the scientific community for resolution dependent petrophysical analysis.     

Time delay reduction in low power ultrashort pulse and pulse stream propagation with overlapping soliton pair

Propagation of temporal 50 femtosecond pulse and pulse stream, which is realized by substituting each input pulse with reduced-order overlapping soliton pair, is investigated through short standard single-mode fiber. For the pulse stream the initial inter-pulse delay is selected to be 227 fs and the pulses are to be perturbed to avoid collision with the neighboring pulses. This method reduces the pulse time delay and properly retains the amplitude despite tradeoff between these two. This is a significant improvement in the low power femtosecond pulse and pulse stream propagation.