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A full scale water-cooled Passive Residual Heat Removal System was designed and built for a 2 MW Molten Salt Reactor. In the process of heating the water tank, the heat transfer characteristics of the condenser in the system had an important impact on the temperature distribution and the development of thermal stratification in the water tank. Therefore, the heat transfer characteristics of the condenser at single-phase natural convection stage need to be experimentally researched and theoretically analyzed. Aiming at the condenser in the system, a series of experiments were carried out. Considering the influence of tube bundle effect on natural convection heat transfer, a set of theories using hydraulic diameter as characteristic length were put forward and applied to analyze the experimental results, which indicated the good agreement with the previous correlations consequently. This study can provide theoretical feasibility and experimental reference for the design of commercial molten salt reactor system in the future.

Fluorescence quenching of carbon dots (CDs) occurs in their aggregated state ascribed to direct π-π interactions or excessive resonance energy transfer (RET). Thus, CDs have been severely restricted for applications requiring phosphors that emit in the solid state, such as the fabrication of white light-emitting diodes (WLEDs). In this report, novel CDs with bright solid-state fluorescence (SSF) were synthesized by simple microwave-assisted synthesis method, using 1,4,7,10-tetraazacyclododecane (cyclen) and citric acid as precursors. Under 365 nm UV light, these CDs emit bright yellow SSF, indicating they successfully overcome the aggregation-induced fluorescence quenching (ACQ) effect. When the excitation wavelength (λ ex ) is fixed at 450 nm, the emission peak of the CDs is centered at 546 nm with the Commission Internationale de l'Eclairage chromaticity (CIE) coordinates of (0.43, 0.55), which means that they can be combined with a blue-emitting chip in order to fabricate WLEDs. More importantly, the absolute quantum yield (QY) of these CDs powder reached 48% at λ ex of 450 nm, which was much higher than many previously reported SSF-emitting CDs and indicating their high light conversion ability in solid-state. Thanks to the excellent optical property of these CDs powder, they were successfully used in the preparation of high-performance WLEDs. This study not only enriches SSF-emitting CD-based nanomaterials with good prospects for application, but also provides valuable reference for subsequent research on the synthesis of solid-state fluorescent CDs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

The popularity of novel nanoparticles coated capillary column has aroused widespread attention of researchers. Metal organic frameworks (MOFs) with special structure and chemical properties have received great interest in separation sciences. This work presents the investigation of HKUST-1 (Hong Kong University of Science and Technology-1, called Cu 3 (BTC) 2 or MOF-199) nanoparticles as a new type of coating material for capillary electrochromatography. For the first time, three layers coating (3-LC), five layers coating (5-LC), ten layers coating (10-LC), fifteen layers coating (15-LC), twenty layers coating(20-LC) and twenty-five layers coating (25-LC) capillary columns coated with HKUST-1 nanoparticles were synthesized by covalent bond with in situ, layer-by-layer self-assembly approach. The results of scanning electron microscopy (SEM), X-ray diffraction (XRD) and plasma atomic emission spectrometry (ICP-AES) indicated that HKUST-1 was successfully grafted on the inner wall of the capillary. The separating performances of 3-LC, 5-LC, 10-LC, 15-LC, 20-LC and 25-LC open tubular (OT) capillary columns were studied with some neutral small organic molecules. The results indicated that the neutral small organic molecules were separated successfully with 10-LC, 15-LC and 20-LC OT capillary columns because of the size selectivity of lattice aperture and hydrophobicity of organic ligands. In addition, 10-LC and 15-LC OT capillary columns showed better performance for the separation of certain phenolic compounds. Furthermore, 10-LC, 15-LC and 20-LC OT capillary columns exhibited good intra-day repeatability with the relative standard deviations (RSDs; %) of migration time and peak areas lying in the range of 0.3-1.2% and 0.5-4.2%, respectively. For inter-day reproducibility, the RSDs of the three OT capillary columns were found to be lying in the range of 0.3-5.5% and 0.3-4.5% for migration time and peak area, respectively. The RSDs of retention times for column-to-column for three batches of 10-LC, 15-LC and 20-LC OT capillary columns were in the range from 2.3% to 7.2%. Moreover, the fabricated 10-LC, 15-LC and 20-LC OT capillary columns exhibited good repeatability and stability for separation, which could be used successively for more than 120 runs with no observable changes on the separation efficiency., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Combinations of antioxidants are believed to be more effective than single antioxidant because when antioxidants are combined they support each other synergistically to create a magnified effect. Discovering the enhancer effects or synergies between bioactive components is valuable for resisting oxidative stress and improving health benefits. The aim of this study was to investigate a possible cooperation of natural antioxidant caffeic acid phenethyl ester (CAPE) with synthetic antioxidant Trolox in the model systems of chemical generation of free radicals, lipid peroxidation of microsomes and radiation-induced oxidative injury in L929 cells. Based on the intermolecular interaction between CAPE and Trolox, the present study shows a synergistic effect of CAPE and Trolox in combination on elimination of three different free radicals and inhibition of lipid peroxidation initiated by three different systems. CAPE and Trolox added simultaneously to the L929 cells exerted an enhanced preventive effect on the oxidative injury induced by radiation through decreasing ROS generation, protecting plasma membrane and increasing the ratios of reduced glutathione/oxidized glutathione and the expression of key antioxidant enzymes mediated by nuclear factor erythroid 2 p45-related factor 2 (Nrf2). Our results showed for the first time that administration of CAPE and Trolox in combination may exert synergistic antioxidant effects, and further indicate that CAPE and Trolox combination functions mainly through scavenging ROS directly, inhibiting lipid peroxidation and promoting redox cycle of GSH mediated by Nrf2-regulated glutathione peroxidase and glutathione reductase expression., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Two new flavanones with a C15 isoprenoid group, japonicasins A and B (1 and 2), were isolated from the leaves of Sophora japonica. This is the first report on the presence of the (2E,7E)-6-isopropyl-3,9-dimethyldeca-2,7,9-trien-1-yl group (C15 isoprenoid group) in isoprenylated flavonoids. Their structures were determined by spectroscopic methods, including UV, IR, 1D and 2D NMR, HRESIMS, and CD experiments. In addition, the antioxidant activities of compounds 1 and 2 were determined through DPPH radical scavenging assays. They exhibited potential antioxidant activities, with IC50 values of 35.1±0.8 μM and 88.7±1.1 μM for compounds 1 and 2, respectively., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A novel coated capillary was prepared by immobilizing graphene oxide (GO) on the fused-silica capillary (75 μm i.d.) which was derivatized by 3-aminopropyl-trimethoxysilane (APTMS). The bare capillary, APTMS modified capillary (NH2-capillary) and GO coated capillary (GO-capillary) were characterized by streaming potentials (SPs), fluorescence microscope and scanning electron microscope (SEM). The results indicated that the capillary was successfully modified with GO sheets via covalent bonding and electrostatic effect. Compared with bare capillary, greater separation efficiency was achieved by GO-capillary column as a result of the increasing interactions between the small organic molecules and the inner wall of the GO-capillary column originated from the π-π electrostatic stacking. For three consecutive runs, the intra-day relative standard deviations (RSDs) of migration time and peak areas were 0.6-4.3% and 2.8-9.3%, respectively. The inter-day relative standard deviations of migration time and peak areas were 0.2-8.3% and 4.5-9.6%. Additionally, one GO-capillary column could be used for more than 100 runs with no observable changes on the separation efficiency., (Copyright © 2013 Elsevier B.V. All rights reserved.)

This paper for the first time describes the development of micelle to solvent stacking (MSS) to nonaqueous capillary electrophoresis (NACE). In this proposed MSS-NACE, sodium dodecyl sulfate (SDS) micelles transport, release, and focus analytes from the sample solution to the running buffer using methanol as their solvent. After the focusing step, the focused analytes were separated via NACE. The focusing mechanism and influencing factors were discussed using berberine (BBR) and jatrorrhizine (JTZ) as model compounds. And the optimum condition was obtained as following: 50 mM ammonium acetate, 6% (v/v) acetic acid and 10 mM SDS in redistilled water as sample matrix, 50 mM ammonium acetate and 6% (v/v) acetic acid in pure methanol as the running buffer, -20 kV focusing voltage with 30 min focusing time. Under these conditions, this method afforded limits of detection (S/N=3) of 0.002 μg/mL and 0.003 μg/mL for BBR and JTZ, respectively. In contrast to conventional NACE, the concentration sensitivity was improved 128-153-fold., (Copyright © 2011 Elsevier B.V. All rights reserved.)

In this paper, the co-solvent of methanol-water was used to facilitate the sodium dodecyl sulfate (SDS) micelles collapse, thereby inducing the on-line sample focusing technique of micelle to solvent stacking (MSS). To demonstrate this stacking method, the mechanism of micelles collapse in co-solvent was discussed. The details of the required conditions were investigated and the optimized conditions were: running buffer, 20mM H(3)BO(3) and 20mM NaH(2)PO(4) solution (pH 4.0); micellar sample matrix, 20mM SDS, 20mM H(3)BO(3) and 20mM NaH(2)PO(4) solution (pH 4.0); co-solvent buffer, 20mM H(3)BO(3) and 20mM NaH(2)PO(4) in methanol/water (90:10, v/v). The validity of the developed method was tested using cationic alkaloid compounds (ephedrine and berberine) as model analytes. Under the optimized conditions, this proposed method afforded limits of detection (LODs) of 0.5 and 1.1ng/mL with 300 and 1036-fold improvements in sensitivity for ephedrine and berberine, respectively, within 15min., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Oleanolic acid (OA) is a natural triterpenoid, which has been used in Chinese medicine for the treatment of liver disorders for many years. Its pharmacological activities have been the focus of intense research in recent years. However, there is little research on the antioxidant activities of OA. In the present study, we aim to investigate whether OA produces its protective effects mainly through antioxidant mechanisms and whether OA plays as an antioxidant through quenching reactive oxygen species (ROS), inhibiting lipid peroxidation or stimulating cellular antioxidant defenses. In the in vitro antioxidant activity-assessing models, OA acted as not only a free radical-scavenger through direct chemical reactions but also a biological molecule, which may enhance the antioxidant defenses. tert-Butyl hydroperoxide (tBHP) induced ROS generation, damaged plasma membrane and decreased cell viability and the expression of key antioxidant enzymes and MAP kinases in QZG cells. OA ameliorated the oxidative injury induced by tBHP through increasing the generation of antioxidant (glutathione) and the expression of key antioxidant enzymes mediated by nuclear factorerythroid 2 p45-related factor 2 (Nrf2), in which process, activation of JNK and ERK, but not p38, was involved. The present study, for the first time, investigated the antioxidant activities of OA systematically. OA probably functions mainly through indirect biological effect and protects QZG cells against cytotoxicity induced by tBHP through increasing the generation of antioxidant and the expression of oxidative stress sensitive transcription factor-Nrf2, and MAP kinases, mainly JNK and ERK. These findings may significantly better the understanding of OA and advance therapeutic approaches to the diseases which are associated with oxidative stress.

Unlabelled: Paeoniflorin (PF), a chief active ingredient in the root of Paeonia lactiflora Pall (family Ranunculaceae), is effective in relieving colorectal distention (CRD)-induced visceral pain in rats with visceral hyperalgesia induced by neonatal maternal separation (NMS). This study aimed at exploring the underlying mechanisms of PF's analgesic effect on CRD-evoked nociceptive signaling in the central nervous system (CNS) and investigating whether the adenosine A(1) receptor is involved in PF's anti-nociception., Results: CRD-induced visceral pain as well as phosphorylated-extracellular signal-regulated protein kinase (p-ERK) and phospho-cAMP response element-binding protein (p-CREB) expression in the CNS structures of NMS rats were suppressed by NMDA receptor antagonist dizocilpine (MK-801) and ERK phosphorylation inhibitor U0126. PF could similarly inhibit CRD-evoked p-ERK and c-Fos expression in laminae I-II of the lumbosacral dorsal horn and anterior cingulate cortex (ACC). PF could also reverse the CRD-evoked increased glutamate concentration by CRD as shown by dynamic microdialysis monitoring in ACC, whereas, DPCPX, an antagonist of adenosine A(1) receptor, significantly blocked the analgesic effect of PF and PF's inhibition on CRD-induced p-ERK and p-CREB expression. These results suggest that PF's analgesic effect is possibly mediated by adenosine A(1) receptor by inhibiting CRD-evoked glutamate release and the NMDA receptor dependent ERK signaling.

This study presented a capillary zone electrophoresis (CZE) method for the analysis of trace amount of neurotransmitters glutamate (Glu) and aspartate (Asp) in the microdialysates of rat periaqueductal gray matter (PAG). Glu and Asp were derivatized with the fluorescent agent 5-carboxyfluorescein N-succinimidyl ester (CFSE) for the first time and detected by laser-induced fluorescence (LIF) after separation by CZE. The concentration detection limits (S/N=2) were 6.9x10(-10)M and 8.1x10(-10)M for Glu and Asp, respectively. The repeatability (expressed as RSD) of the migration times of CFSE-amino acid were better than 0.5%, and not higher than 1.5% even over the period of 1 month. This method was applied to quantify Glu and Asp in rat PAG microdialysates with the treatment of formalin injection, and the measured basal concentrations of Glu and Asp were (22.4+/-1.6)x10(-6)M and (0.9+/-0.1)x10(-6)M, respectively.