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1.
Artigo em Inglês | MEDLINE | ID: mdl-33205268

RESUMO

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) concentrations and distributions, emission factors and amounts, and ambient air and soil potential sources were investigated by collecting flue gas, ambient air, and soil samples from ten sintering furnaces and two electric arc furnaces of eight iron and steel smelting industries (ISSI) in China. In flue gas, the concentrations of PCDD/Fs ranged from 0.05 to 2.93 ng I-TEQ Nm-3 (mass, from 0.38 to 30.67 ng Nm-3), with an average of 0.42 ng I-TEQ Nm-3 (mass, 4.99 ng Nm-3), respectively. In ambient air, the concentrations ranged from 0.05 to 0.35 pg I-TEQ m-3 (mass, from 0.66 to 5.66 pg m-3), with an average of 0.20 pg I-TEQ m-3 (mass, 2.96 pg m-3), respectively. In surface soil, the concentrations ranged from 1.80 to 21.02 ng I-TEQ kg-1 (mass, from 34.29 to 836.00 ng kg-1), with an average of 5.82 ng I-TEQ kg-1 (mass, 252.10 ng kg-1), respectively. In deep soil, the concentrations ranged from 1.17 to 12.00 ng I-TEQ kg-1 (mass, from 56.83 to 1488.00 ng kg-1), with an average of 7.76 ng I-TEQ kg-1 (mass, 433.20 ng kg-1), respectively. Compared with emission limits for PCDD/Fs, the compliance was 78.9% in flue gas, 100% in ambient air, and 77.3% in soil. In congener profiles, the contributions of PCDFs were much higher than those of PCDDs in flue gas and ambient air, but the opposite was observed in soil. In ten sintering furnaces, the emission factors ranged from 22.11 to 901.22 ng I-TEQ t-1, with an average of 373.80 ng I-TEQ t-1, respectively. In two electric arc furnaces, the emission factors were 1667.52 and 894.96 ng I-TEQ t-1, with an average of 1281.24 ng I-TEQ t-1. According to both principal component analysis and hierarchical cluster analysis, all ambient air samples were affected by the emissions of PCDD/Fs from ISSIs, but to different degrees. However, the concentrations of PCDD/Fs in most soil samples were not influenced by the ISSI emissions.

2.
Oral Oncol ; : 105092, 2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33189578

RESUMO

Mammary analog secretory carcinoma (MASC), or secretory carcinoma of the thyroid is an extremely rare disease harboring ETV6-NTRK3 gene fusion with TRK activation. Here we report the twelfth case of MASC of the thyroid worldwide. A 36-year-old female was diagnosed with poor-differentiated thyroid carcinoma (PDTC). Pathology consultant and immunochemical workups showed the tumor cells were negative for TTF1, TG, PAX8, positive for S100, Vimentin, GATA-3, and focally positive for mammaglobin. Fluorescence in situ hybridization (FISH) assay using a dual-color break-apart probe showed ETV6 translocation t(12p13) (ETV6) was present and established the diagnosis of MASC. Next-generation sequencing (NGS) of a 47-gene panel identified exon 1-5 of ETV6 gene were fused with exons 15-19 of NTRK3 gene. The patient experienced three loco-regional recurrences within 12 months and eventually developed inoperable local disease as well as bilateral lung metastasis. She is currently receiving anti-TRK treatment with a follow-up time of 33 months. A literature review of MASC in the thyroid was also conducted.

3.
Phytother Res ; 2020 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-33164233

RESUMO

The purpose of this study was to estimate the pharmacological effect of geniposide (GEN) on depression, caused by chronic unpredictable mild stress (CUMS), and explore its potential mechanism. During the 6 week CUMS procedure, the mice were treated with GEN (10, 40 mg/kg) by gavage once daily for 3 weeks. As a result, the GEN treatment remarkably improved the behavioral manifestations and suppressed the generations of inflammatory cytokines both in vivo and in vitro. The MDA level was significantly increased, while the activities of SOD, GSH-PX were decreased in CUMS-challenged mice and corticosterone-stimulated PC12 cells. GEN administration significantly inhibited those changes. Moreover, GEN treatment could downregulate the expressions of p-BTK, TLR4, MyD88, p-NF-κB proteins, and upregulate BDNF, p-TrkB generations in CUMS-induced mice. Moreover, GEN administration inhibited the protein levels of p-BTK, TLR4, MyD88, p-NF-κB in corticosterone-induced PC12 cell. In summary, the results suggested that GEN exerted a therapeutic effect on CUMS-induced depressive mice possibly through the regulation of BTK/TLR4/NF-κB and BDNF/TrkB signaling pathways.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33064460

RESUMO

Functional surfaces with broad-band ultralow optical reflection have many potential applications in areas like national defense and energy conversion. For efficient, high-quality manufacturing of material surfaces with antireflection features, a novel machining method for multiscale micro-nano structures is proposed. This method can enable the collaborative manufacturing of both microstructures via laser ablation and micro-nano structures with high porosity via in situ deposition, and it can simplify the fabrication process of multiscale micro-nano structures. As a result, substantially improved antireflection properties of the treated material surface can be realized by optimizing light trapping of the microstructures and enhancing the effective medium effect for the micro-nano structures with high porosity. In ultraviolet-visible-near-infrared regions, average reflectances, as low as 2.21 and 3.33%, are achieved for Si and Cu surfaces, respectively. Furthermore, the antireflection effect of the treated surface can also be extended to the mid-infrared wavelength range, where the average reflectances for the Si and Cu surfaces decrease to 5.28 and 5.18%, respectively. This novel collaborative manufacturing method is both simple and adaptable for different materials, which opens new doors for the preparation of broad-band ultra-low-reflectivity materials.

5.
J Affect Disord ; 277: 755-764, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33065814

RESUMO

BACKGROUND: The purpose of this study was to evaluate whether Esculin could improve the depressive symptom induced by LPS in mice and explore the role of CCR5 in its potential mechanism. METHODS: Mice were stimulated with LPS to establish depression model and treated with Esculin. The emotional alteration was assessed via behavior tests. The ELISA assay and western blot analysis were applied to detect the expressions of inflammatory cytokines and correlative proteins. RESULTS: As a result, Esculin played a protective role in LPS-induced depressive dysfunction, which was possible through the reduction of M1 microglia, and elevation of M2 microglia by inhibiting TLR4/NF-κB signaling pathway regulated by CCR5. Besides, Esculin led to up-regulation of the CREB/BDNF neuroprotective pathway, and suppression of inflammatory cytokines both in the central and peripheral system. BV2 cells were stimulated with LPS to further elucidate the accordant mechanism in vitro. Molecular docking results suggested that Esc bound to CCR5 at amino acid residues TYR187 and THR105 through hydrogen-bonding. LIMITATIONS: Transgenic animals might be useful for the further investigation. CONCLUSIONS: From the overall results, we concluded that Esculin might exert a beneficial effect on LPS-induced depression in mice and represent an effective treatment for depression.

6.
Stat Med ; 2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-33016376

RESUMO

Two-phase designs involve measuring extra variables on a subset of the cohort where some variables are already measured. The goal of two-phase designs is to choose a subsample of individuals from the cohort and analyse that subsample efficiently. It is of interest to obtain an optimal design that gives the most efficient estimates of regression parameters. In this article, we propose a multiwave sampling design to approximate the optimal design for design-based estimators. Influence functions are used to compute the optimal sampling allocations. We propose to use informative priors on regression parameters to derive the wave-1 sampling probabilities because any prespecified sampling probabilities may be far from optimal and decrease the design efficiency. The posterior distributions of the regression parameters derived from the current wave will then be used as priors for the next wave. Generalized raking is used in the final statistical analysis. We show that a two-wave sampling with reasonable informative priors will end up with a highly efficient estimation for the parameter of interest and be close to the underlying optimal design.

7.
Food Chem ; : 128309, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33051099

RESUMO

Redox imbalance and fungal infection are major causes for quality deterioration and postharvest decay of fruit. Therefore, it is crucial to activate intrinsic antioxidative capacity and disease responses for fruit quality maintenance. Although plant-derived flavonoids have been reported for health-promoting benefits, their roles in the maintenance of fruit quality remains largely unexplored. Here, we exogenously applied luteolin, a flavonoid substance, and further examined its efficacy in maintaining fruit quality and inhibiting fungal diseases in sweet cherry. The results showed that 100 or 200 mg/L luteolin maintained better organoleptic quality and decreased disease incidence during storage. Biochemical assays revealed that luteolin activated the phenylpropanoid metabolic pathway and improved antioxidative capacity, thereby elevating total anthocyanin and flavonoid contents. Notably, luteolin inhibited mycelial growth of fungal pathogens and reduced patulin yield by Penicillium expansum. Collectively, these results suggest that luteolin is a promising alternative for maintaining better fruit quality and ameliorating disease resistance.

8.
BMC Complement Med Ther ; 20(1): 301, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33028328

RESUMO

BACKGROUND: Pseudorabies virus (PRV) is an animal virus that is globally responsible for the high economic losses in the swine industry. Isatis root is a traditional Chinese medicinal herb that possesses immune-enhancing and antiviral properties. However, the molecular mechanisms underlying the effects of the active component of the isatis root polysaccharide (IRPS) extract on immature dendritic cells remain elusive. METHODS: In this study, we investigated the molecular changes in primary porcine peripheral blood monocyte-derived dendritic cells (MoDCs) during PRV infection, using enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription-polymerase chain reaction. Additionally, we studied the effect of IRPS on PRV-infected DCs. RESULTS: The results showed that IRPS stimulated the maturation of MoDCs, induced IL-12 secretion, and downregulated IL-6 expression. CONCLUSIONS: Collectively, these results suggest that IRPS is a promising candidate for promoting maturation of DCs and enhancing their secretory potential after PRV infection.

9.
PLoS Pathog ; 16(10): e1008953, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33048986

RESUMO

Borrelia burgdorferi, the Lyme disease pathogen causes persistent infection by evading the host immune response. Differential expression of the surface-exposed lipoprotein VlsE that undergoes antigenic variation is a key immune evasion strategy employed by B. burgdorferi. Most studies focused on the mechanism of VlsE antigen variation, but little is known about VlsE regulation and factor(s) that regulates differential vlsE expression. In this study, we investigated BB0025, a putative YebC family transcriptional regulator (and hence designated BB0025 as YebC of B. burgdorferi herein). We constructed yebC mutant and complemented strain in an infectious strain of B. burgdorferi. The yebC mutant could infect immunocompromised SCID mice but not immunocompetent mice, suggesting that YebC plays an important role in evading host adaptive immunity. RNA-seq analyses identified vlsE as one of the genes whose expression was most affected by YebC. Quantitative RT-PCR and Western blot analyses confirmed that vlsE expression was dependent on YebC. In vitro, YebC and VlsE were co-regulated in response to growth temperature. In mice, both yebC and vlsE were inversely expressed with ospC in response to the host adaptive immune response. Furthermore, EMSA proved that YebC directly binds to the vlsE promoter, suggesting a direct transcriptional control. These data demonstrate that YebC is a new regulator that modulates expression of vlsE and other genes important for spirochetal infection and immune evasion in the mammalian host.

10.
Waste Manag ; 119: 82-90, 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33049516

RESUMO

Inhibition mechanisms of sulfur-, nitrogen- and phosphorus- based inhibitors on the de novo synthesis of polychlorinated dibenzo-p-dioxins, and dibenzofurans (PCDD/F) were studied by exploring speciation evolution of carbon, chorine and copper in fly ash under laboratory-scale experiments. Significant inhibition of PCDD/Fs by thiourea (TUA) and ammonium dihydrogen phosphate (ADP) was observed as 97.2% and 98.2%, respectively, except for potassium dihydrogen phosphate (PDP). ADP and PDP exhibited better inhibition on PCDFs than on PCDDs, whereas TUA exhibited the opposite effect. After adding inhibitors, the proportion of C-O/C=O/O-C=O bonds at the surface of fly ash increased, and stronger oxidation of carbon occurred, together with the conversion from Cu2+ to Cu+ and the inhibition of organic chlorine formation. Kinetic model results indicated that TUA might either suppress the carbon gasification or promote the decomposition of PCDD/Fs, resulting in a remarkable inhibition of PCDD/Fs formation. Simulated chemical reaction equilibrium further comfirmed that catalytic metal could be deactivated into CuS and Cu2S by sulfur, and into Cu2P2O7 by phosphorus. Moreover, NH3, decomposed from TUA and ADP, was able to convert Cl2 into HCl, albeit with a weaker chlorination ability. This study of inhibition mechanisms is useful for the exploration and utilization of efficient inhibitors in full-scale incinerators.

11.
Int J Mol Sci ; 21(21)2020 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-33114219

RESUMO

As a member of the Catharanthus roseus receptor-like kinase 1-like (CrRLK1L) protein kinase subfamily, FERONIA (FER) has emerged as a versatile player regulating multifaceted functions in growth and development, as well as responses to environmental factors and pathogens. With the concerted efforts of researchers, the molecular mechanism underlying FER-dependent signaling has been gradually elucidated. A number of cellular processes regulated by FER-ligand interactions have been extensively reported, implying cell type-specific mechanisms for FER. Here, we provide a review on the roles of FER in male-female gametophyte recognition, cell elongation, hormonal signaling, stress responses, responses to fungi and bacteria, and present a brief outlook for future efforts.

12.
Plant Physiol ; 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32999005

RESUMO

Fruit ripening is a complex and genetically programmed process modulated by transcription factors, hormones, and other regulators. However, the mechanism underlying the regulatory loop involving the membrane-protein targets of RIPENING-INHIBITOR (RIN) remains poorly understood. To unravel the function of SlFERL (Solanum lycopersicum FERONIA Like), a putative MADS-box transcription factor target gene, we investigated and addressed the significance of SlFERL in fruit ripening by combining reverse genetics, biochemical, and cytological analyses. Here, we report that RIN and Tomato AGAMOUS-LIKE1 (TAGL1) directly bind to the promoter region of SlFERL and further activate its expression transcriptionally, suggesting a potential role of SlFERL in fruit ripening. Overexpression of SlFERL significantly accelerated the ripening process of tomato fruit, whereas RNAi knockdown of SlFERL resulted in delayed fruit ripening. Moreover, surface plasmon resonance assay coupled with tandem mass spectrometry (SPR-MS/MS) and protein interaction assay revealed that SlFERL interacts with the key enzyme S-adenosylmethionine synthetase 1 (SlSAMS1) in the ethylene biosynthesis pathway, leading to increased S-adenosylmethionine accumulation and elevated ethylene production. Thus, SlFERL serves as a positive regulator of ethylene production and fruit ripening. This study provides clues into the molecular regulatory networks underlying fruit ripening.

13.
Artigo em Inglês | MEDLINE | ID: mdl-33000173

RESUMO

CONTEXT: PD-1, CTLA-4, TIM-3, LAG-3 and TIGIT are considered as major immune co-inhibitory receptors (CIRs) and most promising immunotherapeutic targets in cancer treatment, but they are largely unexplored in medullary thyroid carcinoma (MTC). OBJECTIVE: We aimed to provide first evidence regarding the expression profiles and clinical significance of CIRs in a large cohort of MTCs. DESIGN AND PATIENTS: In total, 200 MTCs who received initial surgery in our hospital were included. Immunohistochemistry was performed to evaluate CIR expressions in tissue microarrays (TMA). Combined with the results of our previous PD-L1 study, clinicopathologic and prognostic correlations of these proteins were retrospectively analyzed. RESULTS: TIM-3, PD-1, CTLA-4, LAG-3 and TIGIT positivity was detected in 96 (48.0%), 27 (13.5%), 25 (12.5%), 6 (3.0%) and 6 (3.0%) patients, respectively, in which TIM-3, PD-1 and CTLA-4 expressions were positively correlated. Both log-rank tests and multivariate Cox analyses indicated that TIM-3, CTLA-4 expression and PD-1/PD-L1 coexpression were associated with worse structural recurrence-free survival. In addition, among 20 patients who developed advanced disease during follow-up, 12 (60%) showed TIM-3 positivity, wherein 6 cases also had concurrent moderate to strong PD-1, PD-L1 or CTLA-4 expression. CONCLUSIONS: Using the currently largest TMA cohort of this rare cancer, we delineated the CIR expression profiles in MTC, and identified TIM-3, CTLA-4 expression and PD-1/PD-L1 coexpression as promising biomarkers for tumor recurrence. Furthermore, a subset of advanced MTCs are probably immunogenic, for whom single or combined immunotherapy including TIM-3, PD-1, PD-L1 or CTLA-4 blockade may be potential therapeutic approaches in the future.

14.
Phys Chem Chem Phys ; 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33000812

RESUMO

A carbon phosphide (CP) monolayer, a 2D structure derived from the same 3-fold coordination found both in graphene and phosphorene, has been successfully synthesized in an experiment recently. In this paper, we investigated the modulation of electronic structures and transport characteristics of 2D nanosheets and quasi-1D nanoribbons of CP nanomaterials in the α-phase by using first-principles density functional theory simulation. The calculated band structures show that the band gap of 2D CP nanosheets progressively increases as the uniform biaxial strain changes from compression to stretching. However, the biaxial strain cannot change the indirect band gap behavior of the original 2D CP nanosheet. In addition, the band structures of quasi-1D nanoribbons with different styles of H-passivated zigzag edges have also been studied. The results show that the H-passivated zigzag PC ribbons with two P edges are semiconductors with indirect band gaps, and the gaps decrease with increasing width of ribbons. However, the H-passivated CP nanoribbons with one P-atom terminated edge in combination with one P-atom edge, and H-passivated CC nanoribbons with two C-atom terminated edges display metallic behaviors. The semi-conductive or metallic behaviors of zigzag CP nanoribbons can be explained by presenting the wave function of their energy band around the Fermi level. Finally, the electronic transport properties of different CP nanoribbon based nanojunctions are studied in which arise the interesting negative differential resistance or rectification effects in their current-voltage characteristic curves.

15.
Clin Chim Acta ; 511: 125-131, 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33058842

RESUMO

BACKGROUND: Increased serum and urinary mitochondrial DNA have been demonstrated in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Here we investigated the significance of serum nicotinamide adenine dinucleotide-ubiquinone oxidoreductase chain 6 (ND6), which is encoded by mtDNA and can attract neutrophils, in AAV. METHODS: Thirty-seven AAV patients (32 patients with positive myeloperoxidase-ANCA and 5 patients with proteinase 3-ANCA) were enrolled. Relationship between serum ND6 and clinico-laboratory characteristics were analyzed. RESULTS: The ND6 level of patients was higher than normal people (46.56 ± 23.67 pg/mL vs. 4.95 ± 2.45 pg/mL, P < 0.001) The ND6 levels of patients who needed hemodialysis at disease onset and who had pulmonary hemorrhage (PH) were higher than that of the corresponding controls (P = 0.004 and 0.044 respectively). The ND6 level negatively correlated with the percentages of normal glomeruli in kidney biopsy. The AUC of ROC curve to diagnose hemodialysis and PH was 0.804 and 0.750 respectively. ND6 level positively correlated with Birmingham Vasculitis Activity Score in active disease, and returned to normal after remission. Patients with higher serum ND6 had higher mortality (P = 0.023). CONCLUSIONS: Serum ND6 increases in active AAV, and its level correlates with the severity of disease. High ND6 level is associated with severe organ injury and predicts poor prognosis of AAV.

16.
Huan Jing Ke Xue ; 41(9): 4226-4233, 2020 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124304

RESUMO

A field experiment with an orthogonally designed experiment L9(34) was designed to investigate the effect of different N, P, and K levels on plant growth and Cd uptake by Hylotelephium spectabile. The results showed that the biomass of H. spectabile significantly increased with the N application rate. The highest dry weight in the shoot occurred in the treatments with a high level of N (337.5 kg ·hm-2), which was 0.86-2.00 times higher than the value with no fertilizer treatment. The addition of K contributed to promoting the Cd absorption of H. spectabile, while no effect was observed when N and P were added. Consequently, NPK fertilizers contribute to increasing the Cd uptake of H. spectabile, and the N and K fertilizer play important role in plant growth and Cd absorption respectively. Moreover, the effect of fertilizers on Cd uptake of H. spectabile was in the order of N > K > P, which indicated that N fertilizer was the main factor for promoting the Cd phytoextraction efficiency of H. spectabile by increasing the biomass. Therefore, the application of high levels of N combined with moderate levels of P and K will be an effective approach to improve the Cd phytoremediation efficiency of H. spectabile by promoting its growth, and the Cd uptake can be increased by a factor of 0.9-2.2 compared to no fertilizer treatment condition.


Assuntos
Cádmio , Poluentes do Solo , Biodegradação Ambiental , Cádmio/análise , Fertilizantes/análise , Nitrogênio , Nutrientes , Solo , Poluentes do Solo/análise
17.
Mol Biotechnol ; 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33047235

RESUMO

CRISPR/Cas9-mediated genome editing technology consists of a single-guide RNA (sgRNA), and the Cas9 endonuclease has the potential to treat genetic diseases in most tissues and organisms. In this system, the Cas9 protein can be directed to target genomic DNA sequences as "molecular scissors" with the guidance of sgRNAs. However, the target-specific activities of different sgRNAs are highly variable; thus, it is crucial to search for a simple, quick and economical method to screen for optimized sgRNAs with high target specificity. We have adopted and verified a newly developed white-to-blue colony formation assay to quickly screen for sgRNAs optimized for the EphA2 gene, which is highly expressed in hormone-resistant prostate cancer (PC-3) cells. This assay promises to screen for optimized sgRNAs more simply, rapidly, and efficiently. Our results suggest that the white-to-blue colony formation assay might be a useful screening strategy to quickly select for optimized sgRNAs.

18.
Drug Des Devel Ther ; 14: 3535-3545, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32921987

RESUMO

Background: Tamoxifen is the cornerstone of adjuvant therapy for hormone receptor-positive breast cancer. Despite its efficacy, limited drug sensitivity and endocrine resistance remain the important clinical challenges. The main objective of this study was to investigate fatostatin, which was found to sensitize breast cancer to the antitumour effect of tamoxifen both in vitro and in vivo. Methods: Fatostatin-induced ER degradation was detected by immunoprecipitation assay. The antitumour effect of fatostatin and tamoxifen on MCF-7 and T47D cells was assessed by MTT and colony forming assays. Cell cycle arrest was detected by flow cytometric analysis. Apoptosis was detected by annexin V/propidium iodide double staining and TUNEL assay. Autophagy was detected by MDC assay and acridine orange staining. Migration and invasion assays were performed using a Transwell system, and the efficacy of the synergistic use of fatostatin and tamoxifen in vivo was evaluated using an MCF-7 xenograft model in BALB/c nu/nu female mice. Results: The synergistic use of fatostatin and tamoxifen significantly suppressed cell viability and invasion, induced cell cycle arrest, and regulated apoptosis and autophagy in MCF-7 and T47D cell lines via PI3K-AKT-mTOR signalling. Additionally, the expression levels of Atg7/12/13, beclin and LC3B increased while p-mTOR and P62 expression levels decreased after treatment with fatostatin and tamoxifen. Tumor growth in the xenograft model was suppressed significantly with the synergistic treatment of fatostatin and tamoxifen. Conclusion: Fatostatin could induce ER degradation by K48-linked polyubiquitination, which was the key mechanism contributing to tamoxifen inhibition of PI3K-AKT-mTOR signalling in breast cancer. Fatostatin may have a promising clinical use for ER-positive breast cancer patients.

19.
Sci Total Environ ; 754: 142136, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32911157

RESUMO

Porous biochars have attracted tremendous interests in electrochemical applications. In this study, a family of biochars were prepared from cellulose subject to different carbonization temperatures ranging from 400 to 700 °C, and the biochars were in-situ activated by a molten salt (ZnCl2) to construct a hierarchically porous architecture. The activated porous biochars (ZnBC) were used as a carbocatalyst for electro-Fenton (EF) oxidation of organic contaminants. Results showed that high-temperature carbonization improved the activity of biochar for four-electron oxygen reduction reaction (ORR) due to the rich carbon defects, while the mild-temperature treatment regulated the species and distribution of oxygen functional groups to increase the production of hydrogen peroxide (H2O2) via a selective two-electron ORR pathway. ZnBC-550 was the best cathode material with a high ORR activity without compromise in H2O2 selectivity; a high production rate of H2O2 (796.1 mg/g/h) was attained at -0.25 V vs RHE at pH of 1. Furthermore, Fe(II) addition induced an electro-Fenton system to attain fast decomposition of various organic pollutants at -0.25 V vs RHE (reversible hydrogen electrode) and pH of 3 with a satisfactory mineralization efficiency toward phenolic pollutants. The EF system maintains its excellent stability for 10 cycles. Hydroxyl radicals were identified as the dominant reactive oxygen species based on in situ electron paramagnetic resonance (EPR) analysis and radical quenching tests. This study gains new insights into electrocatalytic H2O2 production over porous biochars and provides a low-cost, robust and high-performance electro-Fenton cathode for wastewater purification.

20.
Prep Biochem Biotechnol ; : 1-9, 2020 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-32967535

RESUMO

A new ion-exchange medium was prepared from magnetic particles of ∼1.0 µm through coating with small zwitterions and then functionalizing with ampholytic groups for the isoelectric point of ∼6.4 and denoted MSP-ZEWB. With Meyerozyma guilliermondii uricase (MGU) as the model of soluble proteins, the purification of a protein via ion-exchange was compared between MSP-ZEWB through elution in discontinuous mode and Toyopearl SP-650C as a classical ion-exchange medium through elution in continuous mode. MGU was adsorbed at pH 7.6 or 8.0 and eluted via competitive displacement by NaCl or electrostatic repulsions with an elution buffer at pH 10 to reverse the type of net charges of MGU. From MSP-ZEWB, MGU was eluted more rapidly with the elution percentages higher than those from Toyopearl SP-650C. For yielding a unit of MGU activity, MSP-ZEWB gave the elution solution volumes that were ∼50% of those obtained with Toyopearl SP-650C. The yields of MGU of the highest purity from MSP-ZEWB were higher than those from Toyopearl SP-650C, but the highest purification folds with both media were comparable. MSP-ZEWB regenerated for 16 times still showed the consistent purification efficacy. Therefore, the ion-exchange media bearing small zwitterion coats showed great promise for the purification of soluble proteins.

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