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1.
Ultrason Sonochem ; 87: 106052, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35660275

RESUMO

In this study, chitosan(CS), nano-silicon aerogels(nSA) and tea polyphenols(TP) were used as film-forming materials and processed with ultrasonication to form films using the tape-casting method. The effects of ultrasonication time, temperature and frequency on the properties of CS/nSA/TP film were explored via material property testing. The results of response surface showed that the maximum tensile strength of the film was 4.036 MPa at ultrasonication time(57.97 min), temperature(37.26 °C) and frequency(30 kHz). The maximum elongation at break of the film was 279.42 % at ultrasonication time(60.88 min), temperature(39.93 °C) and frequency(30 kHz). Due to cavitation and super-mixing effects, ultrasonication may make the surface of the film smoother and easier to degrade. After ultrasonication, TPs were protected by the 3D network structure composed of CS and nSA. Ultrasonication improved the antioxidant and antibacterial properties of the film. These results show that ultrasonication is an effective method to improve the properties of films.


Assuntos
Quitosana , Quitosana/química , Embalagem de Alimentos/métodos , Polifenóis/química , Dióxido de Silício , Chá , Resistência à Tração
2.
Exp Ther Med ; 24(1): 440, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35720620

RESUMO

Lung adenocarcinoma (LA), the primary histological type of non-small cell lung cancer, is still incurable; its diagnosis and treatment remain a major clinical challenge. A previous study by our group examined the microRNA (miRNA/miR) expression profile in the extracellular vesicles from patients with LA and healthy controls and indicated that miR-382-3p levels were reduced in patients with LA. However, the precise roles of miR-382-3p in LA have so far remained elusive. In the present study, the miR-382-3p levels in tumor and adjacent non-tumor control samples from 78 patients with LA were examined and it was identified that miR-382-3p expression was reduced in LA tumor samples compared with that in adjacent non-tumor control tissues (P=0.022). Furthermore, miR-382-3p overexpression inhibited LA growth in a xenograft mouse model. Prediction results indicated that miR-382-3p may regulate protein ubiquitination and SUMOylation. Small ubiquitin-like modifier (SUMO)1 activating enzyme subunit 1 (SAE1), one of the key components of the SUMO-activating complex, was identified as a direct target of miR-382-3p via dual-luciferase and immunoblotting assays. In patients with LA, miR-382-3p expression was negatively correlated with SAE1 protein levels (r=-0.39, P<0.05) and higher SAE1 expression contributed to poor prognosis (P<0.01). Using immunoprecipitation, it was identified that miR-382-3p reduction-induced SAE1 overexpression upregulated AKT SUMOylation, which further promoted AKT phosphorylation and activated the AKT signaling pathway. miR-382-3p inhibition promoted proliferation and inhibited apoptosis in LA cell lines, which was restored by SAE1 knockdown. In conclusion, the present study revealed that downregulation of miR-382-3p contributed to the carcinogenesis of LA via upregulation of SAE1 and promotion of AKT SUMOylation, providing a candidate target for LA treatment.

3.
Environ Sci Technol ; 2022 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-35730737

RESUMO

The hygroscopicity of marine aerosols may largely impact particle optical properties, cloud activation ability, and consequently the global climate system. This study highlights findings from real-time hygroscopicity and chemical composition measurements in three open-ocean cruises over the Atlantic Ocean. Spatial variations in hygroscopicity (κ) for marine boundary layer particles (≤300 nm) were provided for the first time covering nearly 100° of the latitude over the Atlantic Ocean, ranging from 0.14 to 1.06. Externally mixed particles with remarkably low hygroscopicity (0.14-0.16) were observed near the equator influenced by biomass burning emissions transported from Africa. For marine aerosols, a positive linear correlation evidently existed between κ and wind speed within a range of 5-15 m/s even for nanometer particles. A closure study shows that the measured κ of 300 nm particles is well explained by the bulk chemical composition. A good negative correlation between measured κ and the organic mass fraction in PM1 for marine aerosols was found (slope = -2.26, R2 = 0.44), while a different linear relationship appeared for continental aerosols at several sites (slope = -0.47, R2 = 0.77). Accordingly, we provide a parameterization method to estimate bulk aerosol hygroscopicity both in continental and marine environments using particulate organic fractions.

4.
J Gastric Cancer ; 22(2): 120-134, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35534449

RESUMO

PURPOSE: This study aimed to identify prognostic factors for patients with distant lymph node-involved gastric cancer (GC) using a machine learning algorithm, a method that offers considerable advantages and new prospects for high-dimensional biomedical data exploration. MATERIALS AND METHODS: This study employed 79 features of clinical pathology, laboratory tests, and therapeutic details from 289 GC patients whose distant lymphadenopathy was presented as the first episode of recurrence or metastasis. Outcomes were measured as any-cause death events and survival months after distant lymph node metastasis. A prediction model was built based on possible outcome predictors using a random survival forest algorithm and confirmed by 5×5 nested cross-validation. The effects of single variables were interpreted using partial dependence plots. A contour plot was used to visually represent survival prediction based on 2 predictive features. RESULTS: The median survival time of patients with GC with distant nodal metastasis was 9.2 months. The optimal model incorporated the prealbumin level and the prothrombin time (PT), and yielded a prediction error of 0.353. The inclusion of other variables resulted in poorer model performance. Patients with higher serum prealbumin levels or shorter PTs had a significantly better prognosis. The predicted one-year survival rate was stratified and illustrated as a contour plot based on the combined effect the prealbumin level and the PT. CONCLUSIONS: Machine learning is useful for identifying the important determinants of cancer survival using high-dimensional datasets. The prealbumin level and the PT on distant lymph node metastasis are the 2 most crucial factors in predicting the subsequent survival time of advanced GC. TRIAL REGISTRATION: ChiCTR Identifier: ChiCTR1800019978.

5.
Environ Sci Technol ; 2022 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-35559607

RESUMO

Here, we investigated the use of breath-borne volatile organic compounds (VOCs) for rapid monitoring of air pollution health effects on humans. Forty-seven healthy college students were recruited, and their exhaled breath samples (n = 235) were collected and analyzed for VOCs before, on, and after two separate haze pollution episodes using gas chromatography-ion mobility spectrometry (GC-IMS). Using a paired t-test and machine learning model (Gradient Boosting Machine, GBM), six exhaled VOC species including propanol and isoprene were revealed to differ significantly among pre-, on-, and post-exposure in both haze episodes, while none was found between clean control days. The GBM model was shown capable of differentiating between pre- and on-exposure to haze pollution with a precision of 90-100% for both haze episodes. However, poor performance was detected for the same model between two different clean days. In addition to gender and particular haze occurrence influences, correlation analysis revealed that NH4+, NO3-, acetic acid, mesylate, CO, NO2, PM2.5, and O3 played important roles in the changes in breath-borne VOC fingerprints following haze air pollution exposure. This work has demonstrated direct evidence of human health impacts of haze pollution while identifying potential breath-borne VOC biomarkers such as propanol and isoprene for haze air pollution exposure.

6.
BMJ Open ; 12(5): e049225, 2022 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-35501092

RESUMO

INTRODUCTION: The evidence on predictive value of lifestyle behaviours and dietary pattern on the prognosis of heart failure (HF) is limited. Our aim is to identify these factors in the setting of secondary prevention of HF. METHODS AND ANALYSIS: The Metabolic Abnormalities, Lifestyle and Dietary Pattern in Heart Failure study is an ongoing, prospective cohort, single-centre study that aims to recruit 1500 patients with HF from June 2016 to June 2021. At baseline, each participant completes a questionnaire on demographic characteristics, medical history, lifestyle behaviours, sleep duration and quality, bowel movements and regular diet. Biochemical measurements, blood pressure, carotid ultrasound, echocardiography, electrocardiography and cardiac magnetic resonance are obtained and analysed. Muscle strength is assessed using the handgrip dynamometer and the MicroFet2 hand-held dynamometer. Each patient is followed for 5 years or until the occurrence of death. The primary outcome is a composite of cardiovascular mortality or hospitalisation due to worsening heart failure. The secondary end points are cardiovascular deaths and the hospitalisations due to worsening HF. The incidence of mortality and cardiovascular events is documented biennially. ETHICS AND DISSEMINATION: The study protocol has been approved by the Ethics Committee of the Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, and follows the norms of the World's Association Declaration of Helsinki. The results of this study will be disseminated in peer-reviewed journals and academic conferences. TRIAL REGISTRATION NUMBER: NCT03951311.


Assuntos
Força da Mão , Insuficiência Cardíaca , China/epidemiologia , Dieta , Insuficiência Cardíaca/epidemiologia , Humanos , Estilo de Vida , Estudos Prospectivos
7.
PLoS One ; 17(4): e0266241, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35390037

RESUMO

The impact-induced fragmentation of rock is widely and frequently encountered when natural hazards occur in mountainous areas. This type of fragmentation is an important and complex natural process that should be described. In this study, laboratory impact tests under different impact velocities were first conducted using a novel gas-driven rock impact apparatus. The three-dimensional digital image correlation (3D DIC) technique was used to monitor the dynamic fragmentation process upon impact. Then, coupled 3D finite-discrete element method (FDEM) numerical simulations were performed to numerically investigate the energy and damage evolutions and fragmentation characteristics of the sample under different impact velocities. The laboratory test results show that as the impact velocity increases, the failure pattern of the rock sample gradually changes from shear failure to splitting failure, and the fragmentation intensity increases obviously. The strain localization area gradually increases as the impact velocity increases and as the location gradually deviates away from the impacting face. In the numerical simulation, the proposed model is validated by quasi-static uniaxial compression tests and impact tests. The numerical simulations clearly show the progressive fracture process of the samples, which agrees well with the experimental observations. The evolutions of energy and damage variables were also derived based on the simulation results, which are markedly affected by the impact velocity. The fragment size distributions based on mass and number can be well fitted using a generalized extreme value law. Finally, the distribution of the fragment flying velocity and angle are analyzed.


Assuntos
Simulação por Computador , Dióxido de Silício
8.
Phys Chem Chem Phys ; 24(17): 10514-10523, 2022 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-35441631

RESUMO

Viscosity is a fundamental physicochemical property of aerosol particles that influences chemical evolution, mass transfer rates, particle formation, etc. and also changes with ambient relative humidity (RH). However, the viscosity of real individual aerosol particles still remains less understood. Here, we developed a novel optical system based on dual optical tweezers to measure the viscosity of single suspending aerosol droplets under different RH conditions. In our experiment, a pair of quasi atmospheric aerosol droplets composed of organic and inorganic chemical substances were trapped and levitated by dual laser beams, respectively, and then collided and coalesced. The backscattering light signals and bright-field images of the dynamic coalescence process were recorded to infer the morphological relaxation time and the diameter of the composited droplet. Then, the viscosity of the droplet was calculated based on these measured values. The ambient RH of the aerosol droplets was controlled by varying the relative flow rates of dry and humidified nitrogen gas in a self-developed aerosol chamber. The viscosities of single aqueous droplets nebulized with solutes of sucrose, various sulfates and nitrates, and organic/inorganic mixtures were measured over the atmospheric RH range. Besides, the viscosities of the proxies of actual ambient aerosols in Beijing were investigated, which reasonably interpreted the aerosol chemistry transforming from sulfate dominating to nitrate dominating at the PM10 (particulate matter with an aerodynamic diameter of less than 10 µm) level in the last decade in Beijing. Furthermore, the hygroscopicity of droplets with a solute of organic/inorganic mixtures was researched to obtain a deep insight into the relationship between the viscosity and mass transfer process. Hence, we provide a robust approach for investigating the viscosity and hygroscopicity of the actual individual liquid PM10 aerosols.

9.
J Environ Sci (China) ; 114: 249-258, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35459490

RESUMO

Herein, we use an oxidation flow reactor, Gothenburg: Potential Aerosol Mass (Go: PAM) reactor, to investigate the secondary organic aerosol (SOA) formation from wheat straw burning. Biomass burning emissions are exposed to high concentrations of hydroxyl radicals (OH) to simulate processes equivalent to atmospheric oxidation of 0-2.55 days. Primary volatile organic compounds (VOCs) were investigated, and particles were measured before and after the Go: PAM reactor. The influence of water content (i.e. 5% and 11%) in wheat straw was also explored. Two burning stages, the flaming stage, and non-flaming stages, were identified. Primary particle emission factors (EFs) at a water content of 11% (∼3.89 g/kg-fuel) are significantly higher than those at a water content of 5% (∼2.26 g/kg-fuel) during the flaming stage. However, the water content showed no significant influence at the non-flaming stage. EFs of aromatics at a non-flaming stage (321.8±46.2 mg/kg-fuel) are larger than that at a flaming stage (130.9±37.1 mg/kg-fuel). The OA enhancement ratios increased with the increase in OH exposure at first and decreased with the additional increment of OH exposure. The maximum OA enhancement ratio is ∼12 during the non-flaming stages, which is much higher than ∼ 1.7 during the flaming stages. The mass spectrum of the primary wheat burning organic aerosols closely resembles that of resolved biomass burning organic aerosols (BBOA) based on measurements in ambient air. Our results show that large gap (∼60%-90%) still remains to estimate biomass burning SOA if only the oxidation of VOCs were included.


Assuntos
Poluentes Atmosféricos , Compostos Orgânicos Voláteis , Aerossóis/análise , Poluentes Atmosféricos/análise , Biomassa , Compostos Orgânicos Voláteis/análise , Água
10.
Arch Toxicol ; 96(6): 1751-1766, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35384471

RESUMO

Approximately 70-90% of mushroom poisoning deaths are caused by α-amanitin-induced liver injury resulting from RNA polymerase II (RNAP II) inhibition. Liver regeneration ability may contribute greatly to individual survival after α-amanitin poisoning. However, it is unclear what cellular pathways are activated to stimulate regeneration. We conducted dose-effect and time-effect studies in mice that were intraperitoneally injected with 0.33-0.66 mg/kg α-amanitin to establish a poisoning model. The liver/body weight ratio, serological indices, and pathology were evaluated to characterize the liver injury. In the time-effect study, the liver transcriptome was analyzed to explore the mRNA changes resulting from RNAP II inhibition and the underlying pathways associated with recovery. Based on the two animal studies, we established a poisoning model with three sequential liver states: early injury, regulation, and recovery. The mRNA changes reflected by the differentially expressed genes (DEGs) in the transcriptome could be used to illustrate the inhibition of RNAP II by α-amanitin. DEGs at four key time points were well matched with the three liver states, including 8-h downregulated genes in the early injury state, 16-h and 72-h upregulated genes in the regulation state, and 96-h upregulated/downregulated genes in the recovery state. By clustering analysis, the mTOR signaling pathway was screened out as the most promising potential pathway promoting recovery. The results of our investigations of the pathways and events downstream of the mTOR pathway indicated that the activation of mTOR probably contributes crucially to liver regeneration, which could be a promising basis for drug development.


Assuntos
Agaricales , Alfa-Amanitina , Fígado , Intoxicação Alimentar por Cogumelos , Transcriptoma , Alfa-Amanitina/envenenamento , Animais , Perfilação da Expressão Gênica , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Intoxicação Alimentar por Cogumelos/metabolismo , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Serina-Treonina Quinases TOR/metabolismo
11.
Environ Pollut ; 304: 119072, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35301034

RESUMO

Many studies revealed the rapid decline of atmospheric PM2.5 in Beijing due to the emission control measures. The variation of particle number concentration (PN) which has important influences on regional climate and human health, however, was rarely reported. This study measured the particle number size distributions (PNSD) in 3-700 nm in winter of Beijing during 2013-2019. It was found that PN decreased by 58% from 2013 to 2017, but increased by 29% from 2017 to 2019. By Positive matrix factorization (PMF) analysis, five source factors of PNSD were identified as Nucleation, Fresh traffic, Aged traffic + Diesel, Coal + biomass burning and Secondary. Overall, factors associated with primary emissions were found to decrease continuously. Coal + biomass burning dominated the reduction (65%) among the three primary sources during 2013-2017, which resulted from the great efforts on emission control of coal combustion and biomass burning. Fresh traffic and Aged traffic + Diesel decreased by 43% and 66%, respectively, from 2013 to 2019, as a result of the upgrade of the vehicle emission standards in Beijing-Tianjin-Hebei area. On the other hand, the contribution from Nucleation and Secondary decreased with the reduction of gaseous precursors in 2013-2017, but due to the increased intensity of new particle formation (NPF) and secondary oxidation, they increased by 56% and 70%, respectively, from 2017 to 2019, which led to the simultaneously increase of PN and particle volume concentration. This study indicated that NPF may play an important role in urban atmosphere under continuous air quality improvement.


Assuntos
Poluentes Atmosféricos , Idoso , Poluentes Atmosféricos/análise , Pequim , China , Carvão Mineral/análise , Monitoramento Ambiental , Humanos , Tamanho da Partícula , Material Particulado/análise , Emissões de Veículos/análise
12.
Chemosphere ; 298: 134297, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35283143

RESUMO

Photocatalytic elimination of antibiotic pollutant is an appealing avenue in response to the water contamination, but it still suffers from sluggish charge detachment, limited redox capacity as well as poor visible light utilization. Herein, a particular S-scheme FeOOH/MgIn2S4 heterojunction with wide visible light absorption was triumphantly constructed by in-situ growth of MgIn2S4 nanoparticles onto the surface of FeOOH nanorods, and employed as a high-efficiency visible light driven photocatalyst for removing tetracycline (TC). Conspicuously, the as-obtained FeOOH(15 wt%)/MgIn2S4 elucidated the optimal TC removal rate of 0.01258 min-1 after 100 min of visible light illumination, which was almost 33.1 and 6.6 times larger than those of neat FeOOH and MgIn2S4, separately. The exceptional degradation performance was principally put down to the establishment of S-scheme heterojunction between FeOOH and MgIn2S4, which could not merely accelerate the detachment of photogenerated carriers, but also retain the powerful reducing ability of photoinduced electrons for MgIn2S4 and high oxidizing capacity of photoexcited holes for FeOOH, strongly driving the generation of plentiful active species including holes, superoxide and hydroxyl radicals. Additionally, the possible degradation mechanism and pathways of TC were also speculated. This work offers a valuable perspective for constructing high-efficiency S-scheme heterojunction photocatalysts for eradicating antibiotics.


Assuntos
Antibacterianos , Poluentes Ambientais , Catálise , Oxirredução , Tetraciclina
13.
ACS Appl Mater Interfaces ; 14(6): 8095-8105, 2022 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-35113524

RESUMO

Halide solid electrolytes have been considered as the most promising candidates for practical high-voltage all-solid-state lithium-ion batteries (ASSLIBs) due to their moderate ionic conductivity and good interfacial compatibility with oxide cathode materials. Aliovalent ion doping is an effective strategy to increase the ionic conductivity of halide electrolytes. However, the effects of ion doping on the electrochemical stability window of halide electrolytes and carbon additive on electrochemical performance are still unclear by far. Herein, a series of Zr-doped Li3-xEr1-xZrxCl6 halide solid electrolytes (SEs) are synthesized through a mechanochemical method and the effects of Zr substitution on the ionic conductivity and electrochemical stability window are systematically investigated. Zr doping can increase the ionic conductivity, whereas it narrows the electrochemical stability window of the Li3ErCl6 electrolyte simultaneously. The optimized Li2.6Er0.6Zr0.4Cl6 electrolyte exhibits both a high ionic conductivity of 1.13 mS cm-1 and a high oxidation voltage of 4.21 V. Furthermore, carbon additives are demonstrated to be beneficial for achieving high discharge capacity and better cycling stability and rate performance for halide-based ASSLIBs, which are completely different from the case of sulfide electrolytes. ASSLIBs with uncoated LiCoO2 cathode and carbon additives exhibit a high discharge capacity of 147.5 mAh g-1 and superior cycling stability with a capacity retention of 77% after 500 cycles. This work provides an in-depth understanding of the influence of ion doping and carbon additives on halide solid electrolytes and feasible strategies to realize high-energy-density ASSLIBs.

14.
Adv Mater ; 34(14): e2108543, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35104922

RESUMO

Li- and Mn-rich layered oxides (LMROs) are considered the most promising cathode candidates for next-generation high-energy lithium-ion batteries. The poor cycling stability and fast voltage fading resulting from oxygen release during charging, however, severely hinders their practical application. Herein, a strategy of introducing an additional redox couple is proposed to eliminate the persistent problem of oxygen release. As a proof of concept, the cycling stability of Li1.2 Ni0.13 Co0.13 Mn0.54 O2 , which is a typical LMRO cathode, is substantially enhanced with the help of the S2- /SO3 2- redox couple, and the capacity shows no decay with a retention of 100% after 700 cycles at 1C, far superior to the bare counterpart (61.7%). The surface peroxide ions (O2 2- ) are readily chemically reduced back to immobile O2- by S2- during charging, accompanied by the formation of SO3 2- , which plays a critical role in stabilizing the oxygen lattice and eventually inhibiting the release of oxygen. More importantly, the S2- ions are regenerated during the following discharging process and participate in the chemical redox reaction again. The findings shed light on a potential direction to tackle the poor cycling stability of high-energy anion-redox cathode materials for rechargeable metal-ion batteries.

15.
Sci Total Environ ; 824: 153849, 2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35176389

RESUMO

A non-parametric ensemble model was proposed to estimate the long-term (2015-2019) particle surface area concentrations (SA) over China for the first time on basis of a vilification dataset of measured particle number size distribution. This ensemble model showed excellent cross-validation R2 value (CV R2 = 0.83) as well as a relatively low root-mean-square error (RMSE = 195.0 µm2/cm3). No matter in which year, considerable spatial heterogeneity of SA was found over China with higher SA in Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Middle Lower Reaches of Yangtze River (MLYR). From 2015 to 2019, SA significantly decreased in representative city clusters. The reduction rates were 140.1 µm2·cm-3·a-1 in BTH, 110.7 µm2·cm-3·a-1 in Pearl River Delta (PRD), 105.2 µm2·cm-3·a-1 in YRD, and 92.4 µm2·cm-3·a-1 in Sichuan Basin (SCB), respectively. Even though such quick reduction, high SA (ranged from ~800 µm2/cm3 to ~1750 µm2/cm3) during the heavy pollution period (PM2.5 > 75 µg/m3) still existed in the above-mentioned city clusters and may provide rich reaction vessels for multiphase chemistry. A dichotomy of enhanced annual 4th maximum daily 8-h average O3 concentrations (4MDA8 O3) and decreased SA during summertime was found in Shanghai, a representative city of YRD. In Chengdu (SCB), increased 4MDA8 O3 concentration was associated with a synchronous increase of SA from 2017 to 2019. Differently, 4MDA8 O3 concentrations enhanced in Beijing (BTH) and Guangzhou (PRD), while not significant for SA before 2018. This work will greatly deepen our understanding of the historical variation and spatial distributions of SA over China.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Pequim , China , Monitoramento Ambiental/métodos , Aprendizado de Máquina , Material Particulado/análise
16.
Carbohydr Polym ; 281: 119080, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35074131

RESUMO

In this work, chitosan/lignosulfonate composite micelles (CS-LS) were successfully prepared through polyelectrolyte self-assembly. Curcumin was encapsulated in CS-LS to obtain CUR-CS-LS. The results showed that the average diameter of CS-LS and CUR-CS-LS were 239 nm and 286 nm, respectively. The results show that the aromatic rings of lignosulfonate are assembled into the hydrophobic core of micelles through π-π interactions, and chitosan binds outside the hydrophobic core as a hydrophilic shell through electrostatic interactions. Curcumin is encapsulated in the hydrophobic core through hydrophobic interactions. Encapsulation improves the thermal stability and pH stability of curcumin. Compared with free curcumin, the retention efficiency of curcumin in CUR-CS-LS increased by approximately 6.66 and 6.46 times under the same heat treatment and pH conditions, respectively. Encapsulation also increases the antioxidant activity of curcumin in aqueous solution. In addition, the release mechanism of curcumin is diffusion and matrix swelling. These findings explain that CS-LS may be an effective promising delivery system for encapsulating hydrophobic biologically active substances.


Assuntos
Quitosana , Curcumina , Nanopartículas , Antioxidantes , Quitosana/química , Curcumina/química , Portadores de Fármacos/química , Micelas , Nanopartículas/química , Tamanho da Partícula
17.
Sci Total Environ ; 811: 151364, 2022 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-34740668

RESUMO

Atmospheric particles are important reaction vessels for multiphase chemistry. We conducted a meta-analysis of previous field observations in various environments (includes ocean, urban and rural regions), showing that particle hygroscopicity inhomogeneity (PHI) is ubiquitous for the continental atmospheric particles, in which a considerable part of the particulate matters is hydrophobic (10%-33% on average). However, the effects of PHI in quantifying the uptake process of reactive gases are still unclear. Here, taking N2O5 uptake as an example, we showed that using a laboratory-based parameterization scheme without considering the PHI might result in a misestimation of uptake rate coefficient, especially under low ambient relative humidity (RH). Such misestimation may be caused by the differences of the uptake coefficients, as well as the proportion of surface area concentration (SA) between hydrophilic and hydrophobic particles. We suggested that the PHI should be well-considered in establishing the reactive traces gases heterogeneous uptake parameterizations.


Assuntos
Gases , Material Particulado , Aerossóis , Umidade , Material Particulado/análise , Molhabilidade
18.
Sci Total Environ ; 808: 152122, 2022 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-34871687

RESUMO

Formaldehyde (HCHO) can possibly be taken by atmospheric particles due to its moderate solubility. Although previous model studies have proposed that uptake by particles was a large sink for HCHO, direct observation of HCHO partitioning and estimation of HCHO uptake coefficient (γ) for tropospheric conditions are still limited. In this work, online measurements of gaseous HCHO (HCHOg) and particulate HCHO (HCHOp) were carried out simultaneously at an urban site in Beijing in winter and spring. The results indicated that the average concentrations of HCHOp ranged from 0.15 to 0.4 µg m-3, accounting for 1.2% to 10% of the total HCHO (i.e., HCHOg + HCHOp). The median values of estimated γ based on the measured data were in the range of about 1.09 ∗ 10-5-2.42 ∗ 10-4, with lower values during PM2.5 pollution episodes. Besides, the pH and liquid water content of aerosols that are mainly determined by ambient relative humidity (RH) and inorganic salt composition were identified as the main influencing factors of γ. We propose that the HCHO uptake process was mainly driven by hydrone and hydrogen ions in particles.


Assuntos
Poluentes Atmosféricos , Gases , Poluentes Atmosféricos/análise , Poeira , Monitoramento Ambiental , Formaldeído/análise , Gases/análise , Material Particulado/análise
20.
Materials (Basel) ; 14(23)2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-34885578

RESUMO

As an important parameter for concrete, fracture energy is difficult to accurately measure in high loading rate tests due to the limitations of experimental devices and methods. Therefore, the utilization of numerical methods to study the dynamic fracture energy of concrete is a simple and promising choice. This paper presents a numerical investigation on the influence of loading rate on concrete fracture energy and cracking behaviors. A novel rate-dependent cohesive model, which was programmed as a user subroutine in the commercial explicit finite element solver LS-DYNA, is first proposed. After conducting mesh sensitivity analysis, the proposed model is calibrated against representative experimental data. Then, the underlying mechanisms of the increase in fracture energy due to a high strain rate are determined. The results illustrate that the higher fracture energy during dynamic tension loading is caused by the wider region of the damage zone and the increase in real fracture energy. As the loading rate increases, the wider region of the damage zone plays a leading role in increasing fracture energy. In addition, as the strain rate increases, the number of microcracks whose fracture mode is mixed mode increases, which has an obvious effect on the change in real fracture energy.

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