Comparative studies of bioactive organosulphur compounds and antioxidant activities in garlic (Allium sativum L.), elephant garlic (Allium ampeloprasum L.) and onion (Allium cepa L.)

We evaluated organosulphur compounds in Allium vegetables, including garlic, elephant garlic and onion, using high-performance liquid chromatography. Among organosulphur compounds, elephant garlic had considerable γ-glutamyl peptides, and garlic had the highest alliin content. Onion had low level of organosulphur compounds than did elephant garlic and garlic. In addition, antioxidant capacities were evaluated by oxygen radical absorbance capacity (ORAC) values and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay. The results showed that garlic had the highest antioxidant capacity, followed by elephant garlic and onion. Furthermore, a positive correlation was observed between antioxidant activities and organosulphur compounds (R > 0.77). Therefore, our results indicate that there was a close relationship between antioxidant capacity and organosulphur compounds in Allium vegetables.     

Room-Temperature Phosphorescence from a Series of 3-Pyridylcarbazole Derivatives

Exploration of pure metal-free organic molecules that exhibit strong room-temperature phosphorescence (RTP) is an emerging research topic. In this regard, unveiling the design principles for an efficient RTP molecule is an essential, but challenging, task. A small molecule is an ideal platform to precisely understand the fundamental role of each functional component because the parent molecule can be easily derivatized. Here, the RTP behaviors of a series of 3-pyridylcarbazole derivatives are presented. Experimental studies in combination with theoretical calculations reveal the crucial role of the n orbital on the central pyridine ring in the dramatic enhancement of the intersystem crossing between the charge-transfer-excited singlet state and the locally excited triplet states. Single-crystal X-ray crystallographic studies apparently indicate that both the pyridine ring and fluorine atom contribute to the enhancement of the RTP because of the restricted motion owing to weak C−H⋅⋅⋅N and H⋅⋅⋅F hydrogen-bonding interactions. The single crystal of the fluorine-substituted derivative shows an ultra-long phosphorescent lifetime (τ_P) of 1.1 s and a phosphorescence quantum yield (Φ_P) of 1.2 %, whereas the bromine-substituted derivative exhibits τ_P of 0.15 s with a Φ_P of 7.9 %. We believe that this work provides a fundamental and universal guideline for the generation of pure organic molecules exhibiting strong RTP.     

Distance versus Capillary Flow Dynamics-Based Detection Methods on a Microfluidic Paper-Based Analytical Device (μPAD)

In recent years, there has been high interest in paper-based microfluidic sensors or microfluidic paper-based analytical devices (μPADs) towards low-cost, portable, and easy-to-use sensing for chemical and biological targets. μPAD allows spontaneous liquid flow without any external or internal pumping, as well as an innate filtration capability. Although both optical (colorimetric and fluorescent) and electrochemical detection have been demonstrated on μPADs, several limitations still remain, such as the need for additional equipment, vulnerability to ambient lighting perturbation, and inferior sensitivity. Herein, alternative detection methods on μPADs are reviewed to resolve these issues, including relatively well studied distance-based measurements and the newer capillary flow dynamics-based method. Detection principles, assay performance, strengths, and weaknesses are explained for these methods, along with their potential future applications towards point-of-care medical diagnostics and other field-based applications.     

Efficient preparation of UCl3 by ZnCl2 mediated chlorination

Journal of Radioanalytical and Nuclear Chemistry - U chlorination is demonstrated using electrochemical and chemical reactions with ZnCl2 in LiCl–KCl molten salts. Voltammetric studies...     

Self‐emulsion polymerization of amphiphilic monomers—a green route to synthesis of polymeric nanoscaffolds

Self‐emulsion polymerization (SEP), a green route developed by us for the polymerization of amphiphilic monomers, does not require any emulsifier or an organic solvent except that the water‐soluble initiators such as 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)propane]dihydrochloride (VA‐044) and potassium persulfate (KPS) are only used. We report here the polymer nanoscaffolds from a number of amphiphilic monomers, which can be used for in situ encapsulation of a variety of nanoparticles. As a demonstration of the efficacy of these nanoscaffolds, the synthesis of a biocompatible hybrid nanoparticle (nanohybrid), prepared by encapsulating Fe₃O₄ magnetic nanoparticle (Fe₃O₄ MNPs) in poly(2‐hydroxyethyl methacrylate) in water, for MRI application is presented. The nanohybrid prepared following the SEP in the form of an emulsion does not involve the use of any stabilizing agent, crosslinker, polymeric emulsifier, or surfactant. This water‐soluble, spherical, and stable nanohybrid containing Fe₃O₄ MNPs of average size 10 ± 2 nm has a zeta potential value of ?41.89 mV under physiological conditions. Magnetic measurement confirmed that the nanohybrid shows typical magnetic behavior having a saturation magnetization (Ms) value of 32.3 emu/g and a transverse relaxivity (r2) value of 29.97 mM^?1 s^?1, which signifies that it can be used as a T2 contrast agent in MRI. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019     

Exfoliation of 2D Materials for Energy and Environmental Applications

The fascinating properties of single-layer graphene isolated by mechanical exfoliation have inspired extensive research efforts toward two-dimensional (2D) materials. Layered compounds serve as precursors for atomically thin 2D materials (briefly, 2D nanomaterials) owing to their strong intraplane chemical bonding but weak interplane van der Waals interactions. There are newly emerging 2D materials beyond graphene, and it is becoming increasingly important to develop cost-effective, scalable methods for producing 2D nanomaterials with controlled microstructures and properties. The variety of developed synthetic techniques can be categorized into two classes: bottom-up and top-down approaches. Of top-down approaches, the exfoliation of bulk 2D materials into single or few layers is the most common. This review highlights chemical and physical exfoliation methods that allow for the production of 2D nanomaterials in large quantities. In addition, remarkable examples of utilizing exfoliated 2D nanomaterials in energy and environmental applications are introduced.