Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.147
Filtrar
1.
Inorg Chem ; 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33213142

RESUMO

Actinium-225 (225Ac) is an excellent candidate for targeted radiotherapeutic applications for treating cancer, because of its 10-day half-life and emission of four high-energy α2+ particles. To harness and direct the energetic potential of actinium, strongly binding chelators that remain stable in vivo during biological targeting must be developed. Unfortunately, controlling chelation for actinium remains challenging. Actinium is the largest +3 cation on the periodic table and has a 6d05f0 electronic configuration, and its chemistry is relatively unexplored. Herein, we present theoretical work focused on improving the understanding of actinium bonding with macrocyclic chelating agents as a function of (1) macrocycle ring size, (2) the number and identity of metal binding functional groups, and (3) the length of the tether linking the metal binding functional group to the macrocyclic backbone. Actinium binding by these chelators is presented within the context of complexation with DOTA4-, the most relevant Ac3+ binding agent for contemporary radiopharmaceutical applications. The results enabled us to develop a new strategy for actinium chelator design. The approach is rooted in our identification that Ac3+-chelation chemistry is dominated by ionic bonding interactions and relies on (1) maximizing electrostatic interactions between the metal binding functional group and the Ac3+ cation and (2) minimizing electronic repulsion between negatively charged actinium binding functional groups. This insight will provide a foundation for future innovation in developing the next generation of multifunctional actinium chelators.

2.
J Clin Lab Anal ; : e23654, 2020 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-33210392

RESUMO

BACKGROUND: Geriatric patients with coronavirus disease (COVID-19) are at high risk of developing cardiac injury. Identifying the factors that affect high-sensitivity cardiac troponin I may indicate the cause of cardiac injury in elderly patients, and this could hopefully assist in protecting heart function in this patient population. METHODS: One hundred and eighty inpatients who were admitted for COVID-19 were screened. Patients older than 60 years were included in this study, and the clinical characteristics and laboratory results of the cohort were analyzed. The correlation between cardiac injury and clinical/laboratory variables was statistically analyzed, and further logistic regression was performed to determine how these variables influence cardiac injury in geriatric patients. RESULTS: Age (p < 0.001) significantly correlated with cardiac injury, whereas sex (p = 0.372) and coexisting diseases did not. Rising procalcitonin (p = 0.001), interleukin-2 receptor (p < 0.001), interleukin 6 (p = 0.001), interleukin 10 (p < 0.001), tumor necrosis factor α (p = 0.001), high-sensitivity C-reactive protein (p = 0.001), D-dimer (p < 0.001), white blood cells (p < 0.001), neutrophils (p = 0.001), declining lymphocytes (p < 0.001), and natural killer cells (p = 0.005) were associated with cardiac injury and showed predictive ability in the multivariate logistic regression. CONCLUSION: Our results suggest that age and inflammatory factors influence cardiac injury in elderly patients. Interfering with inflammation in this patient population may potentially confer cardiac protection.

3.
Dis Aquat Organ ; 142: 13-21, 2020 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-33150871

RESUMO

Nocardia seriolae is the causative agent of nocardiosis in both marine and freshwater fish. Here, we report on multiple outbreaks of nocardiosis associated with elevated mortality (23-35%) in farmed largemouth bass in Sichuan, China, from 2017 to 2018. A total of 9 strains isolated from diseased largemouth bass were identified as N. seriolae by phenotypic characterization, 16S rRNA and hsp65 gene sequence analysis. The clinical signs of infected largemouth bass included hemorrhage, skin ulcers and prominent tubercles varying in size in the gill, liver, spleen and kidney. Experimental infection indicated that these isolates were the pathogens responsible for the mortalities. In vitro antibacterial activities of 12 antibiotics against N. seriolae isolates were determined as minimum inhibitory concentrations. Histopathological observation of diseased fish infected with N. seriolae showed necrotizing granulomatous hepatitis, nephritis, splenitis, epithelial hypertrophy and hyperplasia with degenerative changes of the epithelium in the gill. Large quantities of bacterial aggregates were found in the necrotic area of the granuloma by Lillie-Twort Gram stain and immunocytochemistry. Our findings indicated that N. seriolae is a serious threat to the largemouth bass Micropterus salmoides industry in Southwest China.


Assuntos
Bass , Doenças dos Peixes , Nocardia , Animais , China/epidemiologia , Doenças dos Peixes/epidemiologia , Nocardia/genética , Filogenia , RNA Ribossômico 16S/genética
4.
Immunol Lett ; 228: 93-102, 2020 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-33132183

RESUMO

BACKGROUND: The pathogenesis of airway allergic disorders (AAD) needs to be further investigated. Eosinophils (Eos) are the canonical effector cells in AAD attacks. Bcl2 like protein-12 (Bcl2L12) is an apoptosis inhibitor and an immune regulator. Eos have the defects of apoptosis. This study aims to investigate the role of Bcl2L12 in the AAD pathogenesis by regulating Eo activities. METHODS: Human nasal lavage fluids (NLF) and mouse bronchoalveolar lavage fluids (BALF) was collected. Eos in NLF and BALF were analyzed by flow cytometry. A murine AAD model was developed with ovalbumin as a specific antigen. RESULTS: We found that Eos isolated from NLF or BALF of AAD subjects expressed high levels of Bcl2L12 and showed defects of apoptosis. The Bcl2L12 expression in Eos was positively correlated with the AAD response. High lipopolysaccharide levels were detected in the AAD airways, that promoted the Bcl2L12 expression in Eos. Bcl2L12 mediated the LPS-induced autocrine eotaxin 1 expression in Eos through activating the MAPK p38/STAT6/NF-κB signal pathway. Depletion of Bcl2L12 in Eos suppressed experimental AAD in mice. CONCLUSIONS: AAD Eos express high levels of Bcl2L12, the latter is associated with AAD response by regulating the autocrine eotaxin 1 in Eos. Depletion of Bcl2L12 in Eos attenuates experimental AAD, suggesting that to suppress the Bcl2L12 Eos has the translational potential in the treatment of AAD.

5.
J Mol Med (Berl) ; 98(12): 1795-1807, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33159537

RESUMO

SUMOylation has long been recognized to regulate multiple biological processes in pancreatic beta cells, but its impact on proinsulin disulfide maturation and endoplasmic reticulum (ER) stress remains elusive. Herein, we conducted comparative proteomic analyses of SUMOylated proteins in primary mouse/human islets following proinflammatory cytokine stimulation. Cytokine challenge rendered beta cells to undergo a SUMOylation turnover manifested by the changes of SUMOylation substrates and SUMOylation levels for multiple substrates. Our data support that SUMOylation may play a crucial role to regulate proinsulin misfolding and ER stress at least by targeting Protein Disulfide Isomerase a3 (Pdia3). SUMOylation regulates Pdia3 enzymatic activity, subcellular localization, and protein binding ability. Furthermore, SUMOylation of Pdia3 exacerbated proinsulin misfolding and ER stress, and repressed Stat3 activation. In contrast, disruption of Pdia3 SUMOylation markedly rescued the outcomes. Collectively, our study expands the understanding how SUMOylation regulates ER stress in beta cells, which shed light on developing potential strategies against beta cell dysfunction.

6.
Mol Immunol ; 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33229073

RESUMO

Polymorphonuclear neutrophils (PMN) are one fraction of the major inflammatory cells in allergic asthma (asthma, in short); the role of PMN in the asthma pathogenesis is not fully understood yet. This study aims to investigate the effects of specific Ag-guiding exosomes on suppressing the neutrophil-dominant airway inflammation. In this study, BALB/c mice were immunized with ovalbumin plus complete Freund adjuvant to induce an asthma model featured with neutrophil-dominant lung inflammation. The Ag specific PMN (sPMN)-targeting exosomes (tExo), that were exosomes carrying a complex of specific Ag/anti-CD64 Ab and Fas ligand, were constructed to be used to alleviate neutrophilic asthma in mice. We found that sPMNs were the major cellular component in bronchoalveolar lavage fluid (BALF) in asthma mice, while less than 3% PMNs in naive control mice. The sPMNs expressed higher levels of CD64, which formed complexes with Ag-specific IgG (sIgG). The sIgG/CD64 complex-carrying PMNs could be activated upon exposing to specific Ags. Exposure to tExos induced Ag-specific PMNs apoptosis. Administration of tExos efficiently suppressed experimental asthma. We conclude that a fraction of sPMN was identified in the airway of asthma mice. The sPMNs could be activated upon exposure to specific Ags. tExos could induce sPMNs apoptosis, that show the translational potential in the treatment of asthma.

7.
Endocrine ; 2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-33169290

RESUMO

PURPOSE: Anti-Müllerian hormone (AMH) is crucial for folliculogenesis. Prenatal exposure to AMH in mice produces a phenocopy of polycystic ovary syndrome (PCOS) in the adult female offspring. The aim of this study was to determine whether genetic variation in AMH gene contribute to PCOS in women of Chinese ancestry. METHODS: We conducted a case-control genetic study in 383 PCOS case and 433 control women of Chinese ancestry. The exons and the 5' flanking region of AMH were sanger sequenced. Bioinformatic prediction of variant deleteriousness was performed. RESULTS: Seven novel heterozygous variants along with 15 rare known variants in AMH were identified in women with PCOS but not in controls. The novel variants included one frameshift variant (c.125_129delACTTG), one synonymous variant (c.1095C>T), one variant (c.-14T>C) in the 5'-untranslated region (UTR), four variants(c.-775C>T, c.-682C>T, c.-333A>G, c.-137A>T) in 5' flanking sequence. Of all the AMH variants identified in women with PCOS, eight were predicted to be deleterious by bioinformatic analysis. The PCOS carriers of predicted-to-be-deleterious PCOS-specific AMH variants had increased total follicle numbers compared to PCOS noncarriers (p = 0.021). CONCLUSIONS: Our findings suggest the AMH plays a role in the development of PCOS. The exact mechanisms by which the predicted-to-be-deleterious novel and rare AMH variants described in our study affect AMH function requires further study.

8.
Artigo em Inglês | MEDLINE | ID: mdl-33169329

RESUMO

Plant-specific TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTORS 1/2 (TCP) transcription factors have known roles in inflorescence architecture. In barley, there are two family members INTERMEDIUM-C (INT-c/HvTB1-1) and COMPOSITUM 1 (COM1/HvTCP24) which are involved in the manipulation of spike architecture, whereas the participation of TCP family genes in selection from wild (Hordeum vulgare subsp. spontaneum, Hs) to cultivated barley (Hordeum vulgare subsp. vulgare, Hv) remains poorly investigated. Here, by conducting a genome-wide survey for TCP-like sequences in publicly-released datasets, 22 HsTCP and 20 HvTCP genes encoded for mature proteins were identified and assigned into two classes (I and II) based on their functional domains and the phylogenetic analysis. Each counterpart of the orthologous gene in wild and cultivated barley usually represented a similarity on the transcriptional profile across the tissues. The diversity analysis of TCPs in 90 wild barley accessions and 137 landraces with geographically-referenced passport information revealed the detectable selection at three loci including INT-c/HvTB1-1, HvPCF2, and HvPCF8. Especially, the HvPCF8 haplotypes in cultivated barley were found correlating with their geographical collection sites. There was no difference observed in either transactivation activity in yeast or subcellular localization in Nicotiana benthamiana among these haplotypes. Nevertheless, the genome-wide diversity analysis of barley TCP genes in wild and cultivated populations provided insight for future functional characterization in plant development such as spike architecture.

9.
Int J Clin Exp Pathol ; 13(10): 2599-2607, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33165428

RESUMO

Sclerosing pneumocytoma (SP) is a rare and benign tumor predominantly occurring in Asian women, easily misdiagnosed by imaging and pathologic frozen diagnosis during surgery because of its diverse histomorphology (4 structures, 2 types of cells). It may form multiple tumors. When SP is combined with carcinoid, adenoma, or other tumors (although rare), diagnosis is more complicated. SP mixed with carcinoid tumor is rare. At present, only 4 cases have been reported in English literature. Here, we report a case of sclerosing pneumocytoma combined not only with carcinoid, but also with clear cell adenoma of the lung. The patient was a 52-year-old female and CT found a nodule in the middle lobe of the right lung. SP was not excluded by intraoperative frozen section diagnosis. The above 3 components formed a 1.4 cm nodule. The related literature is reviewed to strengthen the understanding of SP, and aid clinicopathological diagnosis.

10.
J Phys Chem A ; 124(46): 9674-9682, 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33164521

RESUMO

We present an optimized density-functional tight-binding (DFTB) parameterization for iron-based complexes based on the popular trans3d set of parameters. The transferability of the original and optimized parameterizations is assessed using a set of 50 iron complexes, which include carbonyl, cyanide, polypyridine, and cyclometalated ligands. DFTB-optimized structures predicted using the trans3d parameters show a good agreement with both experimental crystal geometries and density functional theory (DFT)-optimized structures for Fe-N bond lengths. Conversely, Fe-C bond lengths are systematically overestimated. We improve the accuracy of Fe-C interactions by truncating the Fe-O repulsive potential and reparameterizing the Fe-C repulsive potential using a training set of six isolated iron complexes. The new trans3d*-LANLFeC parameter set can produce accurate Fe-C bond lengths in both geometry optimizations and molecular dynamics (MD) simulations, without significantly affecting the accuracy of Fe-N bond lengths. Moreover, the potential energy curves of Fe-C interactions are considerably improved. This improved parameterization may open the door to accurate MD simulations at the DFTB level of theory for large systems containing iron complexes, such as sensitizer-semiconductor assemblies in dye-sensitized solar cells, that are not easily accessible with DFT approaches because of the large number of atoms.

11.
Inorg Chem ; 2020 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-33202122

RESUMO

Copper dissolution in nitric acid is a historic reaction playing a central role in many industrial processes, particularly for metal recovery from the electronics to nuclear industries. The mechanism through which this process occurs is debated. In order to better understand this process, quantum chemical calculations were performed to elucidate the key steps in the mechanism of copper dissolution in nitric acid. We combine both Kohn-Sham density functional theory and ab initio molecular dynamics simulations to understand the mechanism of the formation of the key products: NO2, HNO2, and NO. Our calculations suggest that the mechanisms of formation of NO2, HNO2, and NO are interconnected.

12.
Avian Dis ; 64(3): 286-293, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33205173

RESUMO

The present study was designed to analyze the histologic and cytologic changes of lymphocyte homing in noninfected and duck Tembusu virus (DTMUV)-infected duck spleens. At first, we investigated the noninfected structure that facilitates lymphocyte homing. Under light and electron microscopy, results showed that sheath capillaries were located in the white pulp of the spleen, and the endothelial cells of sheath capillaries were cuboidal in shape, which is a typical characteristic of high endothelial venules. To monitor the lymphocyte homing, 5,6-carboxy fluoresceindiacetate succinimidyl ester (CFSE)-labeled lymphocytes that were intravenously injected into noninfected ducks appeared in the periellipsoidal sheaths (PELS), which proved that lymphocytes can return to the spleen through sheath capillaries. Furthermore, proteoglycans (PGs) associated with homing factors were positively observed in sheath capillaries and PELS by colloidal iron staining. This suggests that PGs are associated with lymphocyte homing. The results of the DTMUV infection experiment showed that PELS appeared vacuolized at 3 dpi. The spleen tissue gradually recovered at 5 and 7 dpi. In addition, the lymphocytes increased around sheath capillaries, and the expression of PGs in sheath capillaries increased after virus infection. Meanwhile, the gaps between endothelial cells were enlarged, and the lymphocytes were mainly in the lumen and basement membrane. In conclusion, lymphocytes could recruit into the spleen through sheath capillaries, and PGs participated and promoted the lymphocyte homing, suggesting that the unique high endothelial capillaries favor lymphocyte homing, which promotes tissue repair and antigen clearance in the duck.

13.
Artigo em Inglês | MEDLINE | ID: mdl-33175678

RESUMO

Capacitive micromachined ultrasonic transducers (CMUTs) are promising in the emerging fields of personalized ultrasonic diagnostics, therapy and noninvasive three-dimensional biometric. However, previous theories describing their mechanical behavior rarely consider multi-layer and anisotropic material properties, resulting in limited application and significant analysis errors. This paper proposes closed-form expressions for the static deflection, collapse voltage, and resonant frequency of circular-microplate-based CMUTs, which consider both aforementioned properties as well as the effects of residual stress and hydrostatic pressure. These expressions are established by combining the classical laminated thin plate (CLTP) theory, Galerkin method, a partial expansion approach for electrostatic force, and an energy equivalent method. A parametric study based on finite element method simulations shows that considering the material anisotropy can significantly improve analysis accuracy (˜25 times higher than the theories neglecting the material anisotropy). These expressions maintain accuracy across almost the whole working voltage range (up to 96% of collapse voltages) and a wide dimension range (diameter-to-thickness ratios of 20˜80 with gap-to-thickness ratios of ˜2). Furthermore, their utility in practical applications is well verified using numerical results based on more realistic boundary conditions and experimental results of CMUTs chips. Finally, we demonstrate that the high accuracy of these expressions at thickness-comparable deflection results from the extended applicable deflection range of the CLTP theory when it is used for electrostatically actuated microplates.

14.
J Med Virol ; 2020 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-33073361

RESUMO

Hyperglycemia commonly occurs in severe cases with COVID-19. In this study, we explored the associations between admission fasting plasma glucose (FPG) and 28-day mortality in COVID-19 patients. In this single centre retrospective study, 263 adult patients with COVID-19 were included. Demographic and clinical information were collected and compared between patients with and without diabetes. Cox regression analyses were used to investigate the risk factors of 28-day mortality in hospitals. Of 263 patients, 161 (61.2%) were male, 62 (25.6%) had a known history of diabetes, and 135 (51.3%) experienced elevated FPG (>7.0 mmol/L) at hospital admission. The median FPG in patients with diabetes was much higher than in patients without diabetes (12.79 vs. 6.47 mmol/L). Patients with diabetes had higher neutrophil count and D-dimer, less lymphocyte count, lower albumin level, and more fatal complications. Multivariable Cox regression analyses showed that age (per 10-year increase) (hazard ratio [HR], 1.41; 95% confidence interval [CI], 1.13-1.74), admission FPG between 7.0 and 11.0 and ≥11.1 mmol/L (HR, 1.90; 95% CI, 1.11-3.25 and HR, 2.09; 95% CI, 1.21-3.64, respectively), chronic obstructive pulmonary disease (HR, 2.89; 95% CI, 1.31-6.39), and cardiac injury (HR, 2.14; 95% CI, 1.33-3.47) were independent predictors of 28-day mortality in COVID-19 patients. Hyperglycemia on admission predicted worse outcome in hospitalized patients with COVID-19. Intensive monitoring and optimal glycemic control may improve the prognosis of COVID-19 patients.

15.
J Inorg Biochem ; 213: 111248, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33011623

RESUMO

Three aroylhydrazone ligands ((Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-2-hydroxybenzohydrazide, HL1; (Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-3-hydroxybenzohydrazide, HL2; and (Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-4-hydroxybenzohydrazide, HL3) and their complexes with nickel (Ni(L1)2, 1; Ni(L2)2, 2; Ni(L3)2∙DMF, 3) were synthesized and characterized by ESI-MS, NMR, IR, UV-vis and elemental analysis techniques. The molecular structure of ligand (HL2) and complexes 1-3 was confirmed by single crystal X-ray crystallography. The single crystal X-ray structure of complexes 1-3 showed a distorted square planar geometry around the metal center, and the ligands adopt a bidentate chelating mode. The interaction of calf thymus (ctDNA) with nickel(II) complexes was explored using absorption, emission spectrum, viscosity, and circular dichroism methods. These complexes exhibited moderate affinity for ctDNA through groove binding modes. The most efficient DNA binder was complex 2. The interaction of the complexes with DNA has also been supported by molecular docking study and molecular dynamics simulation. An in vitro cytotoxicity study of the complexes found low activity against human cervical (Hela) and breast (MCF-7) cancer cell lines, with the best results for complex 2, where IC50 values are 86 µM and 92 µM respectively.

16.
Artigo em Inglês | MEDLINE | ID: mdl-33108472

RESUMO

BACKGROUND: The development of tumor tissue-infiltrating regulatory T cell (Treg) is incompletely understood. This study investigates the role of retinoblastoma cell (Rbc)-derived Twist­related protein 1 (Twist) in the Treg development. METHODS: The surgically removed Rb tissues were collected. Rbcs were cultured with CD4+ T cells to assess the role of Rbc-derived Twist in the Treg generation. RESULTS: We found that more than 90% Rbcs expressed Twist. Foxp3+ Tregs were detected in the Rb tissues that were positively correlated with the Twist expression in Rbcs, negatively associated with Rb patient survival and sight survival. Treating Rbcs with hypoxia promoted the Twist expression that could be detected in the cytoplasm, nuclei and on the cell surface. Twist activated CD4+ T cells by binding the TLR4/myeloid differentiation factor 2 complex and promoted the transforming growth factor-ß-inducible early gene 1 product and Foxp3 expression. These Rbc-induced Foxp3+ Tregs showed immune-suppressive function on CD8+ T cell proliferation. CONCLUSIONS: Rbcs express Twist, that induces IL-4+ Foxp3+ Tregs; the latter can inhibit CD8+ cytotoxic T cell activities. Therefore, Twist may play an important role in the pathogenesis of Rb.

17.
Metallomics ; 12(11): 1802-1810, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33084705

RESUMO

The tachykinin neuropeptide of neurokinin B (NKB) is a copper-binding amyloid peptide with important roles in the regulation of physiological functions and pathophysiological processes in the central and peripheral nervous systems. In this work, the formation of a NKB-Cu2+ complex in a 1 : 1 stoichiometry was confirmed by mass spectrometry. The self-assembly of NKB and its mutant species was investigated by Thioflavin T (ThT) fluorescence assay and atomic force microscopy (AFM), and at the same time, the effect of Cu2+ on the aggregation of NKB was studied. As evidenced by cyclic voltammetry, the redox potential of NKB-Cu2+ was determined to be 0.77 V (vs. Ag/AgCl). It has been demonstrated that NKB at low concentrations exerts its neuroprotective function by inhibiting Cu2+-mediated reactive oxygen species (ROS) production in the presence of ascorbic acid (AA). In comparison with equivalent Cu2+, the peptide-Cu2+ aggregates aggravated the viability of PC-12 cells more seriously in the absence of AA. These results should be extremely valuable for understanding the NKB/Cu2+ interactions and the toxicity mechanism of Cu2+ associated with neurodegenerative diseases.

18.
Spectrochim Acta A Mol Biomol Spectrosc ; 247: 119029, 2020 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-33120123

RESUMO

A series of Ag/AgX (X = Cl, Br, I; X = Cl, Br, or X = Cl, I, or X = Br, I; X = Cl, Br, and I) composite photocatalysts were synthesized via a facile photoreduction. The several characterization methods of X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS) mapping and X-ray photoelectron spectroscopy (XPS) were characterized the samples. Through evaluation the photocatalytic activity of degradation rhodamine, methyl orange, and phenol, Ag-AgCl1/3Br1/3I1/3 exhibited the superior selective photocatalytic activities than other photocatalysts. The reason for improved photocatalytic property of Ag-AgCl1/3Br1/3I1/3 was attributed to the multifarious halogen atoms with the synergistic effect and the surface plasmon resonance (SPR) effect of Ag0. Furthermore, the recycle experiments were conducted to reveal the stability and reusability, the trapping experiments confirmed the active species of Ag-AgCl1/3Br1/3I1/3.

19.
Environ Sci Technol ; 54(22): 14192-14203, 2020 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-33118825

RESUMO

Coastal reservoirs are potentially CH4 emission hotspots owing to their biogeochemical role as the sinks of anthropogenic carbon and nutrients. Yet, the fine-scale spatial variations in CH4 concentrations and fluxes in coastal reservoirs remain poorly understood, hampering an accurate determination of reservoir CH4 budgets. In this study, we examined the spatial variability of diffusive CH4 fluxes and their drivers at a subtropical coastal reservoir in southeast China using high spatial resolution measurements of dissolved CH4 concentrations and physicochemical properties of the surface water. Overall, this reservoir acted as a consistent source of atmospheric CH4, with a mean diffusive flux of 16.1 µmol m-2 h-1. The diffusive CH4 flux at the reservoir demonstrated considerable spatial variations, with the coefficients of variation ranging between 199 and 426% over the three seasons. The shallow water zone (comprising 23% of the reservoir area) had a disproportionately high contribution (56%) to the whole-reservoir diffusive CH4 emissions. Moreover, the mean CH4 flux in the sewage-affected sectors was significantly higher than that in the nonsewage-affected sectors. The results of bootstrap analysis further showed that increasing the sample size from 10 to 100 significantly reduced the relative standard deviation of mean diffusive CH4 flux from 73.7 to 3.4%. Our findings highlighted the role of sewage in governing the spatial variations in reservoir CH4 emissions and the importance of high spatial resolution data to improve the reliability of flux estimates for assessing the contribution of reservoirs to the regional and global CH4 budgets.

20.
J Pharm Biomed Anal ; 192: 113680, 2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33120306

RESUMO

Both classical androgens and 11-oxygenated androgens play important roles in polycystic ovarian syndrome (PCOS). Therefore, high-quality measurements of androgens are very important. In the present study, a highly sensitive and specific method was developed and validated for the simultaneous determination of three classical androgens and five 11-oxygenated androgens in human serum, using a high- performance liquid chromatography-differential mobility spectrometry tandem mass spectrometry (HPLC-DMS/MS/MS). Serum samples were extracted with the mixture of ethyl acetate/tert-butyl methyl ether (1/1, v/v) prior to analysis with the HPLC-DMS/MS/MS system. Stable isotopes were used as the internal standards. Separation was performed on a Poroshell SB C18 column (150 × 2.1 mm, 2.7 µm), with a differential mobility spectrometry (DMS) component, which was used to enhance the resolution. The gradient mobile phase consisted of acetonitrile and ammonium formate buffer with 0.1 % formic acid in both solvents. The sensitivity of the majority of the androgens was improved following addition of the DMS component. Under the optimal conditions, the trace amount of the target androgens in the serum was quantified accurately. The lower limit of quantification of the different analytes ranged from 0.05 to 0.2 ng/mL. The method was validated prior to its application to the assay of the clinical samples.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA