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941.
The performance enhancement of 3D-printed electrode comprised of polylactic acid (PLA) and graphite (Gr) doped with graphene oxide (GO) was studied to detect five heavy metal ions in trace level. The pretreatment of PLA/Gr/GO electrode with potential cycling in H2SO4 solution achieved the most sensitive response. The characteristics of the composite electrodes were verified using XPS, FE-SEM, EDXS, Raman, and impedance spectroscopy. The experimental variables affecting the response current were optimized with respect to pH, deposition time, ratio of PLA/Gr/GO, and supporting electrolytes. The pretreated 3D-PLA/Gr/GO electrode showed a wide dynamic range from 0.5 ppb to 1.0 ppm with low detection limits of 0.039–0.13 ppb. The reliability of the PLA/Gr/GO electrode was evaluated by analyzing the reference samples of European Reference Materials. 相似文献
942.
Bifurcated halogen bonds are constructed with FBr and FI as Lewis acids, paired with NH3 and NCH bases. The first type considered places two bases together with a single acid, while the reverse case of two acids sharing a single base constitutes the second type. These bifurcated systems are compared with the analogous H-bonds wherein FH serves as the acid. In most cases, a bifurcated system is energetically inferior to a single linear bond. There is a larger energetic cost to forcing the single σ-hole of an acid to interact with a pair of bases, than the other way around where two acids engage with the lone pair of a single base. In comparison to FBr and FI, the H-bonding FH acid is better able to participate in a bifurcated sharing with two bases. This behavior is traced to the properties of the monomers, in particular the specific shape of the molecular electrostatic potential, the anisotropy of the orbitals of the acid and base that interact directly with one another, and the angular extent of the total electron density of the two molecules. 相似文献
943.
Polyphenols and omega-3 polyunsaturated fatty acids from fish oils, i.e., eicosapentaenoic and docosahexaenoic acids, are well-recognized nutraceuticals, and their single antioxidant and anti-inflammatory properties have been demonstrated in several studies found in the literature. It has been reported that the combination of these nutraceuticals can lead to three-fold increases in glutathione peroxidase activity, two-fold increases in plasma antioxidant capacity, decreases of 50–100% in lipid peroxidation, protein carbonylation, and urinary 8-isoprotanes, as well as 50–200% attenuation of common inflammation biomarkers, among other effects, as compared to their individual capacities. Therefore, the adequate combination of those bioactive food compounds and their single properties should offer a powerful tool for the design of successfully nutritional interventions for the prevention and palliation of a plethora of human metabolic diseases, frequently diet-induced, whose etiology and progression are characterized by redox homeostasis disturbances and a low-grade of chronic inflammation. However, the certain mechanisms behind their biological activities, in vivo interaction (both between them and other food compounds), and their optimal doses and consumption are not well-known yet. Therefore, we review here the recent evidence accumulated during the last decade about the cooperative action between polyphenols and fish oils against diet-related metabolic alterations, focusing on the mechanisms and pathways described and the effects reported. The final objective is to provide useful information for strategies for personalized nutrition based on these nutraceuticals. 相似文献
944.
Jia Min Lee Sean Kang Qiang Suen Wei Long Ng Wai Cheung Ma Wai Yee Yeong 《Macromolecular bioscience》2021,21(1)
Collagen is the most abundant extracellular matrix protein that is widely used in tissue engineering (TE). There is little research done on printing pure collagen. To understand the bottlenecks in printing pure collagen, it is imperative to understand collagen from a bottom‐up approach. Here it is aimed to provide a comprehensive overview of collagen printing, where collagen assembly in vivo and the various sources of collagen available for TE application are first understood. Next, the current printing technologies and strategy for printing collagen‐based materials are highlighted. Considerations and key challenges faced in collagen printing are identified. Finally, the key research areas that would enhance the functionality of printed collagen are presented. 相似文献
945.
Three isostructural lanthanide metal-organic frameworks (Ln-MOFs) were synthesized with uncoordinated N^N site, and the Ru(N^N)3 photosensitizer was introduced via coordination link. These functionalized frameworks showed excellent performance in the photocatalytic oxidation of sulfides with good conversion and high sulfoxide selectivity. 相似文献
946.
Dr. Xing Chen Lei Li Dr. Xiaoli Wang Prof. Kun Xie Prof. Yuqiao Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):9152-9159
Manganese oxides have attracted great interest in electrochemical energy storage due to high theoretical specific capacitance and abundant valence states. The multiple valence states in the redox reactions are beneficial for enhancing the electrochemical properties. Herein, three manganese microspheres were prepared by a one-pot hydrothermal method and subsequent calcination at different temperatures using carbon spheres as templates. The trivalent manganese of Mn2O3 exhibited multiple redox transitions of Mn3+/Mn2+ and Mn4+/Mn3+ during the intercalation/deintercalation of electrolyte ions. The possible redox reactions of Mn2O3 were proposed based on the cyclic voltammetry and differential pulse voltammogram results. Mn2O3 microsphere integrated the advantages of multiple redox couples and unique structure, demonstrating a high specific capacitance and long cycling stability. The symmetric Mn2O3//Mn2O3 device yielded a maximum energy density of 29.3 Wh kg−1 at 250 W kg−1. 相似文献
947.
《Mendeleev Communications》2021,31(5):664-666
Novel 3-azaxanthenes have been synthesized via acid-catalyzed one-pot Friedel–Crafts reaction of pyridoxal/pyridoxal-5'-phosphate with naphthols followed by dehydration of the intermediate bis(2-hydroxyaryl)-(pyridin-4-yl)methane derivatives. The cytotoxicity of the obtained 3-azaxanthenes against M-HeLa and HuTu-80 tumor cell lines is comparable to that of tamoxifen, whereas the cytotoxicity against normal cell line is absent in the tested concentrations range, which makes this class of compounds interesting for further studies. 相似文献
948.
《Mendeleev Communications》2021,31(6):859-861
Various N-(pyridin-2-yl)acrylamides bearing 4H-chromene fragment were synthesized via the condensation of 4H-chromene-3-carbaldehydes and their fused analogues with 2H-pyrido[1,2-a]pyrimidine-2,4(3H)-diones employing NH4OAc/AcOH system. Possible mechanism of this hetero- domino reaction involves the consecutive Knoevenagel condensation, oxa-6v-electrocyclization, aza-6v-electrocyclic ring-opening, nucleophilic addition, retro-Alder-ene reaction and oxa-6v-electrocyclic ring-disclosure. 相似文献
949.
A series of chalcone ligands and their corresponding vanadyl complexes of composition [VO (LI–IV)2(H2O)2]SO4 (where LI = 1,3‐Diphenylprop‐2‐en‐1‐one, LII = 3‐(2‐Hydroxy‐phenyl)‐1‐phenyl‐propenone, LIII = 3‐(3‐Nitro‐phenyl)‐1‐phenyl‐propenone, LIV = 3‐(4‐Methoxy‐phenyl)‐1‐phenyl‐propenone) have been synthesized and characterized using various spectroscopic (Fourier‐transform infrared, electrospray ionization mass, nuclear magnetic resonance, electron paramagnetic resonance, thermogravimetric analysis, vibrating sample magnetometer) and physico‐analytic techniques. Antidiabetic activities of synthesized complexes along with chalcones were evaluated by performing in vitro and in silico α‐amylase and α‐glucosidase inhibition studies. The obtained results displayed moderate to significant inhibition activity against both the enzymes by vanadyl chalcone complexes. The most potent complexes were further investigated for the enzyme kinetic studies and displayed the mixed inhibition for both the enzymes. Further, antioxidant activity of vanadyl chalcone complexes was evaluated for their efficiency to release oxidative stress using 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate assay, and two complexes (Complexes 2 and 4 ) have demonstrated remarkable antioxidant activity. All the complexes were found to possess promising antidiabetic and antioxidant potential. 相似文献
950.
Two new Zn2Dy2 complexes were constructed from Zn (II) salen‐type Schiff base complex fragment and 2,6‐pyridinedimethanol (H2pdm) or its Br‐substituted analogue (4‐bromopyridine‐2,6‐diyl)dimethanol (H2Brpdm); their molecular formulas are [Zn2Dy2(L)2(pdm)2(MeOH)2](ClO4)2 [ 1 , H2L = N, N′‐ bis(3‐methoxysalicylidene)‐1,3‐diaminopropane] and [Zn2Dy2(L)2(Brpdm)2(MeOH)2](ClO4)2 [ 2 ], the Dy (III) ions of which have a NO7 triangular dodecahedral coordination sphere. The two complexes show not only ferromagnetic interaction but also field‐induced single‐molecule magnet (SMM) behavior, which are rare Dy (III)‐containing cluster complexes with the NO7 triangular dodecahedral coordination sphere that can show good magnetic relaxation. The energy barrier value of complex 2 is higher than those of complex 1 and the Dy (III) complexes with the DyNO7 triangular dodecahedral coordination configuration reported in the literature. 相似文献