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1.
Food Chem ; 306: 125625, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31606635

RESUMO

A novel ultrasonic-assisted vacuum drying technique for dehydrating garlic slices to give high quality products was developed. Garlic slices were dried at 60 °C using four methods: ultrasonic-assisted vacuum drying (USVD), vacuum drying (VD), ultrasonic-assisted drying (USD), and convective drying (CD, the control with no vacuum or ultrasonic applied). Drying kinetics, water-content changes, and properties of the garlic slices were assessed. Univariate linear and partial-least-squares regression models were used to predict the properties from low-field nuclear magnetic resonance parameters. USVD gave the shortest drying time (180 min less than CD) and provided a better garlic color and texture, and allicin retention rate than the other methods. Higher correlations between low-field nuclear magnetic resonance parameters and quality properties were found by partial-least-squares regression (PLSR) than by univariate analysis, with the analysis results being credible. Overall, ultrasonic-assisted vacuum drying produced high-quality products with its properties predicted well by low-field nuclear magnetic resonance.

2.
J Hazard Mater ; 382: 121091, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472465

RESUMO

In this study, we proposed to apply an integrated process which is comprised of in situ ozonation, ceramic membrane filtration (CMF) and biologically active carbon (BAC) filtration to wastewater reclamation for indirect potable reuse purpose. A pilot-scale (20 m3/d) experiment had been run for ten months to validate the prospect of the process in terms of treatment performance and operational stability. Results showed that the in situ O3 + CMF + BAC process performed well in pollutant removal, with chemical oxygen demand, ammonia, nitrate nitrogen, total phosphorus and turbidity levels in the treated water being 5.1 ±â€¯0.9, 0.05 ±â€¯0.01, 10.5 ±â€¯0.8, <0.06 mg/L, and <0.10 NTU, respectively. Most detected trace organic compounds were degraded by>96%. This study demonstrated that synergistic effects existed in the in situ O3 + CMF + BAC process. Compared to pre-ozonation, in situ ozonation in the membrane tank was more effective in controlling membrane fouling (maintaining operational stability) and in degrading organic pollutants, which could be attributed to the higher residual ozone concentration in the tank. Because of the removal of particulate matter by CMF, water head loss of the BAC filter increased slowly and prolonged the backwashing interval to 30 days. BAC filtration was also effective in removing ammonia and N-nitrosodimethylamine from the ozonated water.

3.
J Ethnopharmacol ; 247: 112284, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31604137

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Herb pair, the most fundamental and simplest form of herb compatibility, serves as the basic building block of traditional Chinese medicine formulae. The Danshen-Honghua herb pair (DH), composed of Salviae Miltiorrhizae Radix et Rhizoma (Danshen in Chinese) and Carthami Flos (Honghua in Chinese), has remarkable clinical efficacy to cure cardio-cerebrovascular diseases. This study was designed to investigate the pharmacodynamics of DH in comparison with single herbs and pharmacokinetics of DH relative to Danshen in acute myocardial ischemic injury. MATERIALS AND METHODS: Sixty male Wistar rats were divided into control, model and drug treated groups. The acute myocardial ischemia rat model was induced by administering 85 mg/kg/d isoproterenol (ISO) subcutaneously for two consecutive days. For pharmacodynamic study, histopathological and biochemical analysis were performed to assess the anti-myocardial ischemic effects. While for pharmacokinetic study, a UPLC-MS/MS method was developed for determination of nine main active ingredients, namely danshensu, protocatechuic acid, protocatechualdehyde, caffeic acid, lithospermic acid, rosmarinic acid, salvianolic acid B, salvianolic acid A and salvianolic acid C in rat plasma. RESULTS: The histopathological and biochemical analysis revealed that DH exerted enhanced anti-myocardial ischemic effects against the ISO-induced myocardial ischemia compared with single herbs. The pharmacokinetic study indicated that DH could significantly increase the t1/2z of danshensu, Tmax, AUC0-∞ and MRT0-t of protocatechuic acid in comparison with Danshen alone in normal rats, but more importantly elevate systemic exposure level and prolong t1/2z of protocatechualdehyde, caffeic acid, Tmax of danshensu in acute myocardial ischemia rats. CONCLUSIONS: Our findings demonstrated the greater effects of DH after the compatibility in ISO-induced acute myocardial ischemia rats at pharmacodynamic and pharmacokinetic levels and provided valuable information for clinical application of herb pairs.

4.
Chemosphere ; 238: 124640, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524609

RESUMO

Triclosan (TCS) is a kind of chronic toxicity to aquatic organisms. Due to its highly effective antimicrobial, TCS has been widely applied in personal-care products, which naturally poses a potential risk to the ecological system and human health since its release into water-ecological environment. Therefore, it urgently demands a selective, easily separated, recyclable, and low-cost adsorbent to remove the residues of TCS from aquatic environments. In this study, a novel magnetic molecularly imprinted nano-polymers (TMIPs) were prepared for selective adsorption and convenient collection of TCS in aquatic samples, based on a core-shell technique using TCS as template molecule and SiO2-coated Fe3O4 nanoparticles as the support substrate. The functional groups, particle size, morphology and magnetic property of TMIPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy and vibrating sample magnetometer, respectively. The obtained TMIPs possessed excellent adsorption capacity (Qe = 53.12 mg g-1), speedy adsorption equilibrium time (2 min) and high selectivity (k' = 6.321) for TCS. Moreover, the pH-tolerance and stability tests manifested that the adsorption capacity of TMIPs for TCS was acid-resistance and could retain 94.2% of the maximum Qe after 5 times removal-regeneration cycles. The feature of magnetically susceptibility can simplify the procedures of sample handling in TCS determination, because the TMIPs of TCS are easy to be recycled from aquatic samples. As an application demonstration, the toxicity test in microalgae confirmed that a tiny amount of TMIPs could significantly eliminate the toxic effect of TCS on Chlamydomonas reinhardtii via the efficient binding with TCS.

5.
J Nanosci Nanotechnol ; 20(4): 2598-2602, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492282

RESUMO

AlN nanowires macro-array were successfully fabricated on Si substrate by double template method and chemical vapour deposition. The research shows that AlN nanowires array with different diameter, length and coverage can be prepared by controlling the experimental conditions. The as-prepared AlN nanowires array were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, the Ultraviolet absorption of AlN nanowires array as a sensors was investigated and calculated with the first principle.

6.
J Nanosci Nanotechnol ; 20(5): 3013-3018, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31635641

RESUMO

Molybdenum disulfide (MoS2) was synthesized via hydrothermal process under the assistance of citric acid, which exhibited high photocatalytic property in the application of methylene blue (MB) degradation. The flower ball microstructure of MoS2 changed with different amounts of citric acid. X-ray diffraction (XRD), Scanning electron microscope (SEM), UV-Vis diffuse reflectance spectra have been employed to characterize the samples. It improved the photocatalytic efficiency nearly 19.77% compared to MoS2 without citric acid. When H2O2 was added, the synergistic effect of MoS2 and hydrogen peroxide (H2O2) was observed in photocatalytic reaction system, which degraded MB completely within 40 min under visible light irradiation.

7.
Gene ; 722: 144057, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31430519

RESUMO

OBJECTIVE: Fork head domain-containing transcription factor family (FOX), is comprised of >20 members. Members of FOX family have been implicated in a wide range of physiological and/or diseased conditions. Many of FOX members have been shown to be involved in tumorigenesis and progression. The potential roles in carcinogenesis of FOXN4, a member as one of the vast FOX family, remains relatively unknown. METHOD: Here, we explored the potential involvement of FOXN4 in breast cancer. RESULTS: First, observed that a higher FOXN4 was identified in the normal adjacent breast tissue as compared to that in the breast cancer samples; an increased FOXN4 level was associated with a better prognosis in patients with breast cancer. In addition, ectopically expression of FOXN4 led to the decreased cell proliferation, reduced colony formation and metastatic abilities (EMT, migration and invasion) in breast cancer cell lines. Furthermore, we showed the direct interaction between FOXN4 and TP53 and FOXN4 binding led to the increased activity of TP53. Silencing FOXN4 led to reduced TP53 and increased expression of Dll4, Notch and survivin, providing a link between FOXN4 and Notch signaling. Finally, we used patient-derived xenograft mouse model to demonstrate the tumor inhibitory effects of Notch-inhibitor, PF-3084014. We found that PF-3084014 treatment led to a significantly smaller tumor burden and higher survival ratio in patient-derived xenograft mice as compared to the vehicle. This tumor suppressive effect was accompanied by the increased expression of TP53, FOXN4 and decreased Dll4 and Notch. CONCLUSION: Collectively, our data strongly suggested the tumor suppressive roles of FOXN4 in breast tumorigenesis via the activation of TP53 while suppressing Notch signaling. Future studies are warranted to explore the clinical application of PF-3084104 (Notch inhibitor) for the treatment of breast cancer patients.


Assuntos
Neoplasias da Mama/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Adulto , Animais , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Carcinogênese , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Fatores de Transcrição Forkhead/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Neoplasias Mamárias Experimentais/tratamento farmacológico , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/metabolismo , Camundongos , Metástase Neoplásica , Prognóstico , Receptores Notch/antagonistas & inibidores , Receptores Notch/metabolismo , Transdução de Sinais , Tetra-Hidronaftalenos/uso terapêutico , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Proteínas Supressoras de Tumor/genética , Valina/análogos & derivados , Valina/uso terapêutico
8.
Artigo em Inglês | MEDLINE | ID: mdl-31671247

RESUMO

Fluorescent materials exhibiting the characteristics of strong two-photon absorption (TPA) are extensively used for nonlinear optics, bio-imaging and phototherapy. One practical approach to obtain fluorescent materials with high TPA performance is to polymerize molecular chromophores to form π-conjugated structure. This leads to the increase in TPA cross-section per chromophore, however, efforts to towards this direction was capped by the lack of long-range ordering in the structure and the strong π-π stacking between the chromophores. Here, we reported the rational design of benzothiadiazole-based covalent organic framework (COF) for promoting TPA performance and obtaining the efficient two-photon excited fluorescence. Structure characterizations and spectroscopic studies revealed that the enhancement in TPA performance was attributed to the donor-π-acceptor-π-donor (D-π-A-π-D) configuration of the chromophore, long-range order, and large π-conjugation domain of COF crystals. The structural slipping in TPA-COF not only attenuates the π-π stacking interaction between the layers, but more importantly, overcomes the aggregation-caused emission quenching of the chromophores for improving near-infrared two-photon excited fluorescence imaging.

9.
Langmuir ; 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31671941

RESUMO

While contact angle is a well applied indicator of membrane hydrophobicity and surface energy, the interference of surface roughness and porosity in contact angle measurement and surface energy calculation has been long neglected in the field of porous membrane study. We propose an improved method to straightforwardly derive the surface energy of porous membrane from contact angles with the interference effect corrected. A linearized model was established combining the Young-Dupré and Cassie-Baxter equations, from which the surface energy (Lifshitz-van der Waals and Lewis acid/base components) and roughness index (surface area difference) can be solved simultaneously at a given porosity using contact angles measured with a set of standard polar/nonpolar test liquids. The model solution was examined using hydrophilic microfiltration membranes with different pore morphologies (including perforated plate-like PCTE, irregular particulate bed-like PVDF and fibrous mesh-like PTFE membranes), with the robustness of the results evaluated via Monte Carlo simulation. In comparison with the verified results of the model solution, it was found that the Lifshitz-van der Waals, Lewis acid and base energy values for the tested membranes would deviate by 50-87%, 30-160% and 52-97% respectively if surface roughness and porosity were neglected in the calculation. The profound effect of roughness and porosity on surface energy determination was further confirmed via theoretical analysis of the Young-Dupré and Cassie-Baxter relationships. This improved approach may apply to the surface energy characterization of hydrophilic rough porous membranes (e.g. hydrophilic microfiltration membranes).

10.
Mol Cancer Res ; 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31672701

RESUMO

The programmed death-ligand 1/programmed death-1 (PD-L1/PD-1) pathway plays a pivotal role in the immune escape of tumours. Many tumour cells show "glutamine dependence". However, the relationship between glutamine metabolism and PD-L1 expression has not been reported. In this study, changes in PD-L1 expression in renal carcinoma cells were evaluated during glutamine deprivation and recovery. Although PD-L1 expression differed in two renal cancer cell lines, both cell lines upregulated PD-L1 during glutamine deprivation, and the upregulated PD-L1 was restored to normal after glutamine recovery. Mechanistically, glutamine deprivation resulted in activation of epidermal growth factor receptor (EGFR) signaling via extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and c-Jun. Additionally, treatment of renal cancer cells with EGF also induced PD-L1 expression and ERK1/2 phosphorylation. Finally, inhibitors of EGFR, ERK, and c-Jun all inhibited phosphorylation of c-Jun and downregulated PD-L1 expression induced by glutamine deprivation. Taken together, the data suggest that glutamine regulates the expression of PD-L1 through the EGFR/ERK/c-Jun pathway in renal cancer. Implications: This study reveals glutamine deprivation induces PD-L1 expression via activation of EGFR/ERK/c-Jun signaling in renal cancer and provides novel markers for the treatment of renal cancer.

11.
Dalton Trans ; 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31674607

RESUMO

A novel metal-organic framework with the formula [Zn3(DDB)(DPE)]·H2O (1) (H5DDB = 3,5-di(2',4'-dicarboxylphenyl)benzoic acid and DPE = 1,2-di(4-pyridyl)ethylene) has been solvothermally synthesized by employing a rigid carboxylate ligand H5DDB to assemble with Zn(ii) ions in the presence of a flexible bis(pyridyl) linker DPE. The Zn-MOF is a 3D framework with six-nuclear clusters and possesses remarkable water stability and pH stability. Interestingly, complex 1 can sensitively and selectively sense Fe(iii), Cr(iii), Cr(vi), Mn(vii) and the pesticide 2,6-Dich-4-NA with low detection limits in aqueous solution. Moreover, complex 1 also exhibits selectivity for 2,6-Dich-4-NA detection in real samples including carrot, grape and nectarine extracts, and its detection ability is almost unchanged in the presence of the surfactant sodium dodecyl sulfate (SDS). The possible mechanisms of luminescence quenching have been explained by the weak affinity of nitrogen atoms, resonance energy transfer, and photoinduced electron transfer. To our knowledge, this is the first example of a MOF-based multiresponsive fluorescent probe for the simultaneous detection of Fe(iii), Cr(iii/vi), Mn(vii) and the pesticide 2,6-Dich-4-NA in aqueous solution.

12.
Compr Psychiatry ; 95: 152127, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31669791

RESUMO

OBJECTIVES: To explore help-seeking behaviours of Chinese persons managing depressive symptoms and factors that influence these behaviours. METHODS: A survey of residents living in communities in Wuhan, China was conducted using stratified random sampling. The Patient Health Questionnaire (PHQ-2), the Actual Help-Seeking Questionnaire (AHSQ) and a socio-demographic questionnaire were completed by participants. Descriptive statistics were analyzed. A multiple linear regression model was used to explore factors associated with help-seeking behaviours. RESULTS: Of the 1785 respondents, 672 (37.6%) reported that they experienced depressive symptoms during the past year, and of these respondents, 517 (76.9%) indicated that they sought assistance. Among help-seeking sources utilized by participants, informal help was sought most frequently (72.9%), followed by hotline/Internet assistance (14.3%), mental health professionals (MHPs) (7.9%) and general physicians (GPs) (3.7%). The results of multilinear regression analysis showed that participants who were adults (aged 25-64 years), attended junior and high school (7-12 years education), and lived in urban areas were more likely to seek additional assistance for their depressive symptoms. CONCLUSION: Mental health promotion and education efforts are needed to improve the public's mental health literacy and to promote appropriate utilization of informal sources of assistance in managing depressive symptoms such as a hotline or the Internet. Further interventions need to be considered to reinforce use of social supports and mental health professionals, especially in rural areas.

13.
Artigo em Inglês | MEDLINE | ID: mdl-31677790

RESUMO

A failure of bone marrow mesenchymal stem cells (BM-MSCs) to adhere to hematopoietic cells is an essential cause of the progression of chronic myelogenous leukemia and is also a cause of failure of bone marrow (BM) transplantation, but the exact mechanisms of this have not been fully elucidated. Recent studies have indicated that microRNAs (miRNAs) are contained in leukemia-derived exosomes and are involved in modulating the BM microenvironment. In this study, we found that K562 cell-derived exosomes transfer miR-711 to BM-MSCs and suppress the adhesive function of BM-MSCs. Using qRT-PCR, we also confirmed a significantly higher level of miR-711 in exosomes derived from K562 cells than in exosomes derived from parental cells. The BM-MSCs co-cultured with exosomes derived from K562 cells showed a lower adhesion rate than did controls. We further demonstrated that exosomal transfer of miR-711 induced decreased adhesive abilities by inhibiting expression of adhesion molecule CD44 in BM-MSCs. In conclusion, our study reveals that K562 cell-derived exosomal miR-711 can be transferred to BM-MSCs and weaken adhesive abilities by silencing the expression of the adhesion molecule CD44.

14.
Anal Chim Acta ; 1091: 69-75, 2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31679576

RESUMO

Nanozymes have emerged as promising alternatives to overcome the high cost and low stability issues of natural enzymes. Particularly, those with peroxidase-like activities have been extensively studied to construct versatile biosensors. In this article, we demonstrate that the modification of the graphitic carbon nitride nanosheets (g-C3N4 nanosheets) by plasmonic gold nanoparticles (AuNPs) greatly enhances its catalytic performance as peroxidase mimetic. In the presence of H2O2, the AuNPs@g-C3N4 nanosheets can catalyze the redox reaction of 3,3',5,5'- tetramethylbenzidine (TMB) to produce a blue color. Based on the observation, a colorimetric sensing method for glucose is further developed with the assistance of glucose oxidase (GOx). The linear range for glucose is from 5 to 100 µmol L-1 (R2 = 0.9967) and the limit of detection (LOD) is 1.2 µmol L-1. The LOD can be further lowered down to 0.75 µmol L-1 by using H2SO4 as termination agent and measuring the absorbance of the yellow product at λ = 451 nm. Moreover, the practical usefulness of AuNPs@g-C3N4 nanosheets as a peroxidase nanozyme for glucose determination in human serum and urine is also demonstrated.

15.
Inorg Chem ; 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31682430

RESUMO

The syntheses of 4'-substituted chiral 2,2':6',2″-terpyridine (tpy) ligands with predetermined configurations and directionalities are rather limited in the supramolecular chemistry field. In this study, a carbazole-linked ditopic chiral ligand L was synthesized using 4'-bromo-substituted pineno-fused tpy 5 as the precursor. Upon complexation with Cd(NO3)2·4H2O and Zn(NO3)2·6H2O, two enantiomerically pure metallosupramolecules, [Cd3L3] and [Zn4L4], have been self-assembled and characterized by NMR, electrospray ionization-mass spectrometry, traveling wave ion mobility-mass spectrometry, and DOSY analysis. In addition, their optical properties are characterized by UV-vis, fluorescence, circular dichroism, and circularly polarized luminescence, suggesting an efficiency transmission and amplification of chirality from the ligand to metal center via self-assembly.

16.
Opt Express ; 27(20): A1490-A1505, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31684501

RESUMO

For photon-counting lidars, the classical theoretical rate of the noise photons reflected by the Earth's surface is under the assumption that the Earth's surface is a Lambert reflector, which is obviously not suitable for the water surface. In this paper, the specular reflection theorem is introduced to derive an analytical expression of noise photons arising from the water surface reflection. The verification uses the mean noise rate over water surface, calculated by the raw data photons measured by the Multiple Altimeter Beam Experiment Lidar (MABEL) near the East Coast in the North Carolina, USA. The measured result coincides well with the theoretical noise rate, as both of them equal to 8.4 kHz. In addition, the background noise model also indicates that the background noise rate over the land surface is one order of magnitude larger than that over the water surface, in certain conditions. Hence, a new method, based on the noise rates, is proposed for the Earth's surface type classification and it performs well in distinguishing all water surfaces from land surfaces in the coastal area. For space-borne or airborne photon-counting lidars, this paper not only fills the gap of theoretical rate of noise photons from the water surface but also provides a fast and effective method to classify the Earth's surface types. This method is also suitable for distinguishing ice and water in high-latitude sea-ice covered regions, which is the area of most interest of the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) mission.

17.
Opt Express ; 27(20): 29297-29308, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31684666

RESUMO

We investigate theoretically the generation and enhancement of sum sideband in a quadratically coupled optomechanical system with parametric interactions. It is shown that the generation of frequency components at the sum sideband stems from the nonlinear optomechanical interactions via two-phonon processes in the quadratically coupled optomechanical system, while an optical parametric amplifier (OPA) inside the system can considerably improve the sum sideband generation (SSG). The dependence of SSG on the system parameters, including the power of the control field, the frequency detuning of the probe fields and the nonlinear gain of OPA are analyzed in detail. Our analytic calculation indicates that the SSG can be obtained even under weak driven fields and greatly enhanced via meeting the matching conditions. The effect of SSG may have potential applications for achieving measurement of electric charge (or other weak forces) with higher precision and on-chip manipulation of light propagation.

18.
J Chromatogr A ; : 460657, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31685246

RESUMO

Aristolochic acids (AAs), the major components in Aristolochia manshuriensis Kom stems (AMK), may cause Chinese herb nephropathy during clinical application. Therefore, it is necessary to distinguish AMK from other herbs and Chinese medicines using AAs with high purity as standards. So, an efficient method for separation and purification of AAs is required because of their similar structures. In this study, six AAs with purities of >98% were obtained by pH-zone-refining counter-current chromatography (PZRCCC) in a single run. The optimum two-phase solvent system was petroleum ether-ethyl acetate-methanol-water (3:7:3:7, v/v). Triethylamine (10 mM) was added to the aqueous mobile phase and trifluoroacetic acid (10 mM) to the organic stationary phase. As a result, 9.7 mg aristolochic acid IIIa, 12.0 mg aristolochic acid IVa, 32.2 mg aristolochic acid II, 103.7 mg aristolochic acid I, 24.6 mg aristolic acid II, and 26.1 mg aristolic acid I were obtained from 800 mg AAs crude extract. The elution order of AAs during PZRCCC separation corresponded with the pKa values and hydrophobicities of the target compounds. PZRCCC is an efficient method for isolation of AAs with similar structures.

19.
J Chromatogr A ; : 460660, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31685247

RESUMO

Pyrethrum extract is a natural insecticide that has been used worldwide for centuries, with pyrethrins being considered active ingredients. Their purification is difficult due to their chemical structural similarity and instability to light. In the present study, a coordination complex high-speed counter-current chromatography was used to separate pyrethrins from pyrethrum extract. The two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (10:2:10:2, v/v/v/v) with 0.30 mol/L silver nitrate was selected for separation. As a result, five pyrethrins including cinerin II (31.2 mg), pyrethrin II (43.9 mg), jasmalin II (39.1 mg), pyrethrin I (32.4 mg), and jasmalin I (16.0 mg) were obtained from 400 mg crude extract in 6 h by one-step HSCCC separation, with purities over 95%. The isolated compounds were identified by MS, 1H-NMR and 13C-NMR spectroscopy. The results demonstrated that the addition of silver nitrate in the two-phase solvent system of HSCCC significantly increased the HSCCC separation factor of pyrethrins. HSCCC is a rapid method for purification of pyrenthrins from pyrethrum extract. The established method may also be applied to separate analogous compounds from natural products in which the chemical structure differs in the position or numbers of alkenes.

20.
Sci Rep ; 9(1): 15965, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31685920

RESUMO

The design and fabrication of intricate hollow architectures as cost-effective and dual-function electrocatalyst for water and urea electrolysis is of vital importance to the energy and environment issues. Herein, a facile solvothermal strategy for construction of Prussian-blue analogue (PBA) hollow cages with an open framework was developed. The as-obtained CoFe and NiFe hollow cages (CFHC and NFHC) can be directly utilized as electrocatalysts towards oxygen evolution reaction (OER) and urea oxidation reaction (UOR) with superior catalytic performance (lower electrolysis potential, faster reaction kinetics and long-term durability) compared to their parent solid precursors (CFC and NFC) and even the commercial noble metal-based catalyst. Impressively, to drive a current density of 10 mA cm-2 in alkaline solution, the CFHC catalyst required an overpotential of merely 330 mV, 21.99% lower than that of the solid CFC precursor (423 mV) at the same condition. Meanwhile, the NFHC catalyst could deliver a current density as high as 100 mA cm-2 for the urea oxidation electrolysis at a potential of only 1.40 V, 24.32% lower than that of the solid NFC precursor (1.85 V). This work provides a new platform to construct intricate hollow structures as promising nano-materials for the application in energy conversion and storage.

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