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1.
Biochem Biophys Res Commun ; 717: 150021, 2024 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-38718565

RESUMO

Mesenchymal stem cells (MSCs) are ubiquitous multipotent cells exhibiting significant therapeutic potential for various diseases. It is generally accepted that clinical application requires massive expansion of MSCs, which is often accompanied by the occurrence of replicative senescence. Additionally, senescent MSCs exhibit significantly reduced proliferation, differentiation, and therapeutic potential. The scale-up of MSCs production and cellular senescence are major challenges for translational applications. This study first collected extracellular vesicles (EVs) from gingival MSCs (GMSCs) under hypoxia preconditioning combined with 3D dynamic culture (obtained EVs designed as H-3D-EVs). Subsequently, we further explored the effects and mechanisms of H-3D-EVs on aging-GMSCs. The results showed that H-3D-EVs improved the proliferation ability and cell activity of aging-GMSCs, and ameliorated their senescence. mRNA sequencing reveals transcriptomic changes in aging-GMSCs. It was found that H-3D-EVs up-regulated genes related to mitochondrial dynamics, cell cycle, and DNA repair, while down-regulated aging-related genes. Furthermore, we verified that H-3D-EVs corrected the mitochondrial dysfunction of aging-GMSCs by improving mitochondrial dynamics. In summary, this study provides a promising strategy for improving the culture methods of GMSCs and avoiding its senescence in large-scale production.


Assuntos
Senescência Celular , Vesículas Extracelulares , Células-Tronco Mesenquimais , Mitocôndrias , Vesículas Extracelulares/metabolismo , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/citologia , Mitocôndrias/metabolismo , Humanos , Hipóxia Celular , Células Cultivadas , Proliferação de Células , Envelhecimento/metabolismo , Envelhecimento/genética , Dinâmica Mitocondrial
2.
J Transl Med ; 22(1): 392, 2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38685026

RESUMO

BACKGROUND: Epidemiological evidence links a close correlation between long-term exposure to air pollutants and autoimmune diseases, while the causality remained unknown. METHODS: Two-sample Mendelian randomization (TSMR) was used to investigate the role of PM10, PM2.5, NO2, and NOX (N = 423,796-456,380) in 15 autoimmune diseases (N = 14,890-314,995) using data from large European GWASs including UKB, FINNGEN, IMSGC, and IPSCSG. Multivariable Mendelian randomization (MVMR) was conducted to investigate the direct effect of each air pollutant and the mediating role of common factors, including body mass index (BMI), alcohol consumption, smoking status, and household income. Transcriptome-wide association studies (TWAS), two-step MR, and colocalization analyses were performed to explore underlying mechanisms between air pollution and autoimmune diseases. RESULTS: In TSMR, after correction of multiple testing, hypothyroidism was causally associated with higher exposure to NO2 [odds ratio (OR): 1.37, p = 9.08 × 10-4] and NOX [OR: 1.34, p = 2.86 × 10-3], ulcerative colitis (UC) was causally associated with higher exposure to NOX [OR: 2.24, p = 1.23 × 10-2] and PM2.5 [OR: 2.60, p = 5.96 × 10-3], rheumatoid arthritis was causally associated with higher exposure to NOX [OR: 1.72, p = 1.50 × 10-2], systemic lupus erythematosus was causally associated with higher exposure to NOX [OR: 4.92, p = 6.89 × 10-3], celiac disease was causally associated with lower exposure to NOX [OR: 0.14, p = 6.74 × 10-4] and PM2.5 [OR: 0.17, p = 3.18 × 10-3]. The risky effects of PM2.5 on UC remained significant in MVMR analyses after adjusting for other air pollutants. MVMR revealed several common mediators between air pollutants and autoimmune diseases. Transcriptional analysis identified specific gene transcripts and pathways interconnecting air pollutants and autoimmune diseases. Two-step MR revealed that POR, HSPA1B, and BRD2 might mediate from air pollutants to autoimmune diseases. POR pQTL (rs59882870, PPH4=1.00) strongly colocalized with autoimmune diseases. CONCLUSION: This research underscores the necessity of rigorous air pollutant surveillance within public health studies to curb the prevalence of autoimmune diseases.


Assuntos
Poluentes Atmosféricos , Doenças Autoimunes , Estudo de Associação Genômica Ampla , Humanos , Doenças Autoimunes/genética , Poluentes Atmosféricos/efeitos adversos , Análise da Randomização Mendeliana , Predisposição Genética para Doença , Material Particulado/efeitos adversos
3.
BMC Microbiol ; 14: 204, 2014 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-25098921

RESUMO

BACKGROUND: Selenium (Se) is an essential trace element in most organisms but has to be carefully handled since there is a thin line between beneficial and toxic concentrations. Many bacteria have the ability to reduce selenite (Se(IV)) and (or) selenate (Se(VI)) to red elemental selenium that is less toxic. RESULTS: A strictly aerobic bacterium, Comamonas testosteroni S44, previously isolated from metal(loid)-contaminated soil in southern China, reduced Se(IV) to red selenium nanoparticles (SeNPs) with sizes ranging from 100 to 200 nm. Both energy dispersive X-ray Spectroscopy (EDX or EDS) and EDS Elemental Mapping showed no element Se and SeNPs were produced inside cells whereas Se(IV) was reduced to red-colored selenium in the cytoplasmic fraction in presence of NADPH. Tungstate inhibited Se(VI) but not Se(IV) reduction, indicating the Se(IV)-reducing determinant does not contain molybdenum as co-factor. Strain S44 was resistant to multiple heavy and transition metal(loid)s such as Se(IV), As(III), Cu(II), and Cd(II) with minimal inhibitory concentrations (MIC) of 100 mM, 20 mM, 4 mM, and 0.5 mM, respectively. Disruption of iscR encoding a transcriptional regulator negatively impacted cellular growth and subsequent resistance to multiple heavy metal(loid)s. CONCLUSIONS: C. testosteroni S44 could be very useful for bioremediation in heavy metal(loid) polluted soils due to the ability to both reduce toxic Se(VI) and Se(IV) to non-toxic Se (0) under aerobic conditions and to tolerate multiple heavy and transition metals. IscR appears to be an activator to regulate genes involved in resistance to heavy or transition metal(loid)s but not for genes responsible for Se(IV) reduction.


Assuntos
Comamonas testosteroni/isolamento & purificação , Comamonas testosteroni/metabolismo , Ácido Selenioso/metabolismo , Poluentes do Solo/metabolismo , Aerobiose , China , Citoplasma/metabolismo , Farmacorresistência Bacteriana , Metais Pesados/toxicidade , Testes de Sensibilidade Microbiana , NADP/metabolismo , Nanopartículas/metabolismo , Oxirredução , Microbiologia do Solo , Espectrometria por Raios X , Elementos de Transição/toxicidade
4.
Environ Sci Pollut Res Int ; 31(17): 25964-25977, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38492144

RESUMO

Solidification/stabilization technology is commonly used in the rehabilitation of dredged sediment due to its cost-effectiveness. However, traditional solidification/stabilization technology relies on cement, which increases the risk of soil alkalization and leads to increased CO2 emissions during cement production. To address this issue, this study proposed an innovative approach by incorporating bentonite and citrus peel powder as additives in the solidifying agent, with the aim of reducing cement usage in the dredged sediment solidification process. The research results showed that there is a significant interaction among cement, bentonite, and citrus peel powder. After response surface methodology (RSM) optimization, the optimal ratio of the cementitious mixture was determined to be 14.86 g/kg for cement, 5.85 g/kg for bentonite, and 9.31 g/kg for citrus peel powder. The unconfined compressive strength (UCS) of the solidified sediments reached 3144.84 kPa. The reaction products of the solidification materials, when mixed with sediment, facilitated adsorption, gelation, and network structure connection. Simultaneously, the leaching concentration of heavy metals was significantly decreased with five heavy metals (Zn, As, Cd, Hg, and Pb) leaching concentrations decreasing by more than 50%, which met the prescribed thresholds for green planting. This study demonstrated the ecological benefits of employing bentonite and citrus peel powder in the solidification process of dredged sediment, providing an effective solution for sediment solidification.


Assuntos
Mercúrio , Metais Pesados , Bentonita/química , Pós , Metais Pesados/química , Adsorção
5.
Mil Med Res ; 11(1): 48, 2024 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-39034405

RESUMO

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra (SN). Activation of the neuroinflammatory response has a pivotal role in PD. Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic approach for various nerve injuries, but there are limited reports on their use in PD and the underlying mechanisms remain unclear. METHODS: We investigated the effects of clinical-grade hypoxia-preconditioned olfactory mucosa (hOM)-MSCs on neural functional recovery in both PD models and patients, as well as the preventive effects on mouse models of PD. To assess improvement in neuroinflammatory response and neural functional recovery induced by hOM-MSCs exposure, we employed single-cell RNA sequencing (scRNA-seq), assay for transposase accessible chromatin with high-throughput sequencing (ATAC-seq) combined with full-length transcriptome isoform-sequencing (ISO-seq), and functional assay. Furthermore, we present the findings from an initial cohort of patients enrolled in a phase I first-in-human clinical trial evaluating the safety and efficacy of intraspinal transplantation of hOM-MSC transplantation into severe PD patients. RESULTS: A functional assay identified that transforming growth factor-ß1 (TGF-ß1), secreted from hOM-MSCs, played a critical role in modulating mitochondrial function recovery in dopaminergic neurons. This effect was achieved through improving microglia immune regulation and autophagy homeostasis in the SN, which are closely associated with neuroinflammatory responses. Mechanistically, exposure to hOM-MSCs led to an improvement in neuroinflammation and neural function recovery partially mediated by TGF-ß1 via activation of the anaplastic lymphoma kinase/phosphatidylinositol-3-kinase/protein kinase B (ALK/PI3K/Akt) signaling pathway in microglia located in the SN of PD patients. Furthermore, intraspinal transplantation of hOM-MSCs improved the recovery of neurologic function and regulated the neuroinflammatory response without any adverse reactions observed in patients with PD. CONCLUSIONS: These findings provide compelling evidence for the involvement of TGF-ß1 in mediating the beneficial effects of hOM-MSCs on neural functional recovery in PD. Treatment and prevention of hOM-MSCs could be a promising and effective neuroprotective strategy for PD. Additionally, TGF-ß1 may be used alone or combined with hOM-MSCs therapy for treating PD.


Assuntos
Modelos Animais de Doenças , Células-Tronco Mesenquimais , Mucosa Olfatória , Doença de Parkinson , Fator de Crescimento Transformador beta1 , Animais , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Transplante de Células-Tronco Mesenquimais/métodos , Doença de Parkinson/complicações , Doença de Parkinson/terapia , Recuperação de Função Fisiológica , Fator de Crescimento Transformador beta1/metabolismo
6.
Front Public Health ; 11: 1268502, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38145067

RESUMO

Background: Previous studies have examined the impact of greenway interventions on physical activity (PA); however, the results have been inconclusive. In order to address this issue, our study conducted a systematic review with meta-analysis to thoroughly evaluate the evidence and determine the effectiveness of greenway interventions in promoting PA. Methods: We conducted a comprehensive search of literature databases, such as Web of Science, EMBASE, PubMed (via Medline), Cochrane Library, and Scopus, up to June 15, 2023. To synthesize the available evidence, we performed a meta-analysis using a random effects model. The quality of the included studies was assessed using the criteria developed by the Agency for Healthcare Research and Quality and the Newcastle-Ottawa Scale. Results: A total of 9 publications were identified, involving 6, 589 individuals. The overall quality of most included studies was rated as moderate to high. Our study found that the greenway was effective in promoting PA among participants. Specifically, active travel (AT) showed a standard mean difference (SMD) of 0.10 [95% confidence interval (CI): 0.04 to 0.17], moderate-to-vigorous PA had an SMD of 0.11 (95% CI: 0.02 to 0.20), and total PA had an SMD of 0.14 (95% CI: 0.06 to 0.21). We also observed significant differences in AT levels among participants based on greenway characteristics, exposure distance, exposure duration, and male-to-female ratio. Discussion: Newly developed or upgraded greenways have been shown to effectively promote PA. Additionally, research suggests that the longer a greenway has been in existence, the greater the benefits it provides for PA. As a result, the construction of greenways should be recognized as an effective public health intervention.


Assuntos
Exercício Físico , Parques Recreativos , Humanos , Estados Unidos , Promoção da Saúde
7.
Nanoscale ; 15(27): 11582-11591, 2023 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-37376992

RESUMO

Real-time acquisition of the morphological information of nanomaterials is crucial to achieving morphological controllable synthesis, albeit being challenging. A novel device was designed, which integrated dielectric barrier discharge (DBD) plasma synthesis and simultaneous in situ spectral monitoring of the formation of metal-organic frameworks (MOFs). Important dynamic luminescence behaviors such as coordination induced emission (CIE), antenna effect (AE), and red-blue shift were continuously captured to reveal the spectral emission mechanism and energy transfer progress and verify the correlation with the morphological evolution of the MOFs. The prediction and control of morphology were successfully achieved with Eu(TCPP) as a model MOF. The proposed method will shed new light on exploring the spectral emission mechanism, energy conversion and in situ morphology monitoring of other luminescent materials.

8.
Food Chem X ; 18: 100634, 2023 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-36968312

RESUMO

A miniaturized/portable dual-mode colorimetric analytical system was established for inorganic arsenic determination in honey and drinking water samples. Hydride generation (HG) was utilized as a sampling technique for this colorimetric system, because of its high generation efficiency and efficient matrix separation. AsH3 was generated via HG and then reacted with HAuCl4, gold nanoparticles (Au NPs) were formed on the paper sheet, leading the paper color changed from light yellow to dark blue, it could be readout by naked-eye (visual colorimetric mode) and a smartphone (RGB readout mode) simultaneously. The accuracy and potential application for field analysis were further confirmed by the analysis of two water samples, four honey samples and two certified reference water samples (BWB2440-2016 and GBW08650), good recoveries (90-116%) were obtained for those samples and their spiked samples.

9.
Anal Chim Acta ; 1229: 340324, 2022 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-36156216

RESUMO

A miniaturized atomic absorption spectrometer (AAS) was proposed with a planar dielectric barrier discharge (DBD) microplasma as an atomizer, a charge coupled device (CCD) spectrometer as a spectral detector, and a hydride generation (HG) unit as a sampler, and the potential analytical capability was evaluated through the determination of cadmium. Auxiliary hydrogen was added to enhance the atomic absorption signals and the potential mechanism of enhancement effect was studied by use of various techniques. The HG-DBD-AAS was further applied to the determination of Cd, yielding a 1.7-fold enhancement in AAS response with added hydrogen and a limit of detection (LOD) of 0.3 µg L-1 under optimized conditions. Good agreement with the certified values, and desirable spike recoveries ranging between 98% and 108%, were obtained for two certified reference materials and several real water samples, respectively. It can be useful in field analysis of many trace elements with high detectability.


Assuntos
Cádmio , Oligoelementos , Hidrogênio , Espectrofotometria Atômica/métodos , Água
10.
Chem Commun (Camb) ; 58(35): 5419-5422, 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35416210

RESUMO

A novel system was designed, which integrated in situ spectral monitoring with facile synthesis of lanthanide metal-organic frameworks in dielectric barrier discharge (DBD) plasma. It features miniaturization, cost-effectiveness and universality, for in situ spectral information of scattering and luminescence to gain insight into the reactive processes.

11.
Talanta ; 233: 122516, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215131

RESUMO

A fast, low-cost and sensitive method for the determination of trace cadmium was developed by using a miniaturized dielectric barrier discharge microplasma atomic emission spectrometer coupled with a tungsten coil (W-coil) for on-line hydride generation trapping-electrothermal vaporization. Total sample throughput can be greatly improved through the adoption of a horizontally fixed W-coil and the flow injection mode. In addition, the horizontally fixed W-coil and an inserted quartz capillary for on-line trapping contributed to stable and good signal even at a high gas flow rate when volatile cadmium species were trapped, and less sample-consuming and time-saving can be realized in this work. Compared to direct injection, the sensitivity and the LOD were improved by 29- and 38-fold, respectively. The proposed method provides a promising approach to develop a miniaturized instrumentation for highly sensitive detection of trace elements.


Assuntos
Cádmio , Oligoelementos , Espectrofotometria Atômica , Oligoelementos/análise , Tungstênio , Volatilização
12.
Anal Chim Acta ; 1163: 338502, 2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34024418

RESUMO

A tungsten coil (W-coil) as an electrothermal vaporizer (ETV) was interface-free integrated with a point discharge (PD) microplasma as an excitation source for a miniaturized optical emission spectrometer (OES). The PD microplasma and the W-coil ETV were vertically arranged in one quartz tube, and the W-coil was directly placed just under the PD without any physical interface. Working gas flow could sweep them successively to carry analytes released from the W-coil to the PD microplasma, and exhaust out of the quartz tube. The W-coil firstly acted as an ETV for sampling, on which pipetted with a tiny amount of sample solution (typically 10 µL), followed by a heating program for eliminating sample moisture and matrix. Vapor of analytes was subsequently released from the W-coil at a high temperature and immediately swept into the PD microplasma for excitation of atoms to obtain their optical emission spectra. Due to the high temperature of the W-coil, the released analyte species from the W-coil probably had been already atomized/excited partly and partially maintained prior to entering into the PD microplasma, thus saving the energy in the PD for sample evaporation and dissociation. In other words, the W-coil indirectly provided extra energy to the PD microplasma, thus its excitation capability was intensified. Under optimal experimental conditions, simultaneous determination of Ag, As, Bi, Cd, Cu, In, Pb, Sb and Zn was achieved, with LODs of 0.6, 45, 40, 0.08, 15, 8, 8, 41 and 5 µg L-1, respectively, and RSDs all less than 4.5% (n = 3, at corresponding concentrations of 5, 250, 250, 0.5, 100, 50, 50, 250 and 25 µg L-1). The accuracy validation of the proposed technique was demonstrated by successfully analyzing Certified Reference Materials (CRMs, including water, soil, stream sediment and biological samples), and preliminarily analyzing one CRM with direct slurry injection, both with satisfactory results, which had no significant difference with the certificated values at a confidence level of 95% by t-test.

13.
J Am Assoc Lab Anim Sci ; 60(6): 655-660, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-34470695

RESUMO

The number of zebrafish in biomedical research has increased exponentially over the past decades, leading to pressure on the laboratory animal community to develop and refine techniques to monitor zebrafish health so that suitable stocks can be maintained for research. The water filtration assay is a promising technique in which water from a zebrafish system is filtered, and the filter analyzed by PCR. In the present report, we studied how the volume of water tested and the concentration of bacterial pathogens affected test results. To do so, we used stock solutions of 3 zebrafish pathogens: Edwardsiella ictaluri, Aeromonas hydrophila, and Mycobacterium marinum. We used these stocks to create solutions with known concentrations of each pathogen, ranging between 10² and 107 Colony Forming Units (CFU) per ml. One, 2, and 3 L of each solution was filtered using positive pressure, and the filters were submitted to a commercial lab for PCR testing. Results were fit with a logistic regression model, and the probability of obtaining a positive result were calculated. Test sensitivity varied by organism, but in general, test results were positively correlated with the volume of the water filtered and with the concentration of bacteria in solution. We conclude that a positive result can be expected for E. ictaluri at 105 CFU per mL, A. hydrophila at 106 CFU per ml, and M. marinum at 106 CFU per mL, when 3 L of solution are filtered.


Assuntos
Água , Peixe-Zebra , Animais , Bactérias , Edwardsiella ictaluri , Filtração
14.
Nanoscale ; 13(48): 20592-20600, 2021 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-34874030

RESUMO

In the field of catalysis, the design and construction of nanomaterials is an efficient way to optimize the catalytic activity of catalysts. This study presents the synthesis of PtCu tripod nanocrystals with branching structures and high purity prepared using a simple hydrothermal method. The dendritic PtCu triangular nanocrystals were successfully synthesized by regulating the amount of I- ions to achieve different degrees of branching on PtCu nanocrystals, and the process was systematically studied and analyzed. Meanwhile, dumbbell nanocrystals of PtCu were successfully synthesized through slight adjustments to synthesis conditions. In electrochemical tests, the obtained dendritic PtCu triangular nanocrystals exhibited prominent electrocatalytic activity and long-term stability for ethylene glycol, methanol, and ethanol oxidation reactions due to the unique nanostructures as well as alloyed virtue, and were much better than commercial Pt/C. In addition, this study provides a general strategy for designing novel branched Pt-based nanomaterials with high electrocatalytic performance.

15.
Polymers (Basel) ; 11(11)2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31652826

RESUMO

A facile, economical, and one-step hydrothermal method was used to prepare highly luminescent nitrogen-doped carbon quantum dots (N-CQDs) with chitosan as both carbon and nitrogen sources. The as-prepared N-CQDs have an average size of 2 nm and exhibit excitation wavelength-dependent fluorescence with a maximum excitation and emission at 330 and 410 nm, respectively. Furthermore, due to the effective quenching effect of Fe3+ ions, the prepared N-CQDs can be used as a fluorescent sensor for Fe3+ ion-sensitive detection with a detection limit of 0.15 µM. The selectivity experiments revealed that the fluorescent sensor is specific to Fe3+ even with interference by high concentrations of other metal ions. Most importantly, the N-CQD-based Fe3+ ion sensor can be successfully applied to the determination of Fe3+ in real water samples. With excellent sensitivity and selectivity, such stable and cheap carbon materials are potentially suitable for the monitoring of Fe3+ in environmental application.

16.
Nanomaterials (Basel) ; 9(8)2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31405095

RESUMO

The development of Ir-based catalyst with high efficiency for oxygen evolution reaction (OER) in acidic conditions is of great significance to the development of clean energy, but it still remains a significant challenge for shape controlled synthesis of Ir-based catalysts. This article presented a facile one-pot synthesis method that is based on polyol method for preparing IrCu microspheres. In the process of synthesis, formaldehyde solution and ethylene glycol were used as reducing agent and solvent, respectively, while poly(vinylpyrrolidone) was used as surfactant and dispersant, and all of them played important roles in the successful synthesis of Ir-Cu microspheres. The Ir-Cu microspheres, as synthesized, showed well sphere shape and smooth surface, while their alloy features were quite clear and the composition could be adjusted. Benefitting from the synergistic electronic effect between the Iridium and Cupric atoms from the alloy, the IrCu0.77 microspheres exhibited excellent electrocatalytic activity towards OER in 0.1 M HClO4 electrolyte, and to achieve 10 mA cm-2, IrCu0.77 microspheres only required the overpotential of 282 mV, which was much lower than that of commercial Ir/C catalysts.

17.
Carbohydr Polym ; 226: 115290, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31582072

RESUMO

This article reported a simple, green approach for preparing uniform gold nanoparticles (AuNPs) with chitosan as reducing and stabilizing agent in aqueous media. Furthermore, a simple, rapid, sensitive colorimetric method was developed for the detection of Ag+ ions using the as-prepared chitosan functionalized gold nanoparticles (CS-AuNPs) as a probe. The added Ag+ could first interact with the Au core to form a metallic bond, and then reduced by chitosan and deposited on the surface of AuNPs, leading to the formation of alloy Au-Ag core-shell NPs. The characteristic surface plasmon resonance (SPR) peak of CS-AuNPs at 520 nm was blue-shifted and the color of the solution changed from pink to orange with the Ag+ addition. Ag+ could be well determined ranging from 1.0 to 100 µM with detection limit of 0.13 µM. Additionally, this method displayed high sensitivity, selectivity and could be applied to the detection of Ag+ ions in water samples.

18.
Nanomaterials (Basel) ; 9(3)2019 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-30841612

RESUMO

This article presents a facile, one-pot method using the aqueous phase for the synthesis of high-quality Pd nanocubes. In this study, Pd chloride was used as the precursor, sodium iodide as capping agent, and poly(vinylpyrrolidone) as surfactant and reducing agent. The effects of different halogens on the morphology of Pd nanocrystals were investigated. The results showed that, in this synthesis system, the selection and proper amount of sodium iodide was essential to the preparation of high-quality Pd nanocubes. When iodide was replaced by other halogens (such as bromide and chloride), Pd nanocrystals with cubic morphology could not be obtained. In addition, we have found that NaBH4 can be used to efficiently remove inorganic covers, such as iodide, from the surface of Pd nanoparticles as synthesized. The Pd nanoparticles obtained were employed as electro-catalysts for formic acid oxidation, and they exhibited excellent catalytic activity and good stability towards this reaction.

19.
Nanomaterials (Basel) ; 9(1)2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30626034

RESUMO

Cubic Iridium nanoparticles without any surfactants on the surface have been synthesized successfully in this work. The process of synthesis was quite simple by just injecting one drop of 400 µL solution containing Iridium precursor onto Cu foil (1 cm × 1 cm), and through galvanic reaction between the Ir precursor and Cu foil, the cubic Iridium nanoparticle could be obtained quite quickly (<30 s). The Cu foil played the roles of both reducing agent and substrate. This method could also be employed to synthesize cubic nanoparticles of other Pt-group metals such as Rh. By employing this method, cubic metal nanoparticles with surfactant-free surfaces could be produced economically and efficiently, and as a result, a realistic relationship between structure and catalytic activity could be established.

20.
Polymers (Basel) ; 11(12)2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31801227

RESUMO

The worldwide applications of polyurethane (PU) and polystyrene (PS) sponge materials have been causing massive non-renewable resource consumption and huge loss of property and life due to its high flammability. Finding a biodegradable and regenerative sponge material with desirable thermal and flame retardant properties remains challenging to date. In this study, bio-based, renewable calcium alginate hybrid sponge materials (CAS) with high thermal stability and flame retardancy were fabricated through a simple, eco-friendly, in situ, chemical-foaming process at room temperature, followed by a facile and economical post-cross-linking method to obtain the organic-inorganic (CaCO3) hybrid materials. The microstructure of CAS showed desirable porous networks with a porosity rate of 70.3%, indicating that a great amount of raw materials can be saved to achieve remarkable cost control. The sponge materials reached a limiting oxygen index (LOI) of 39, which was greatly improved compared with common sponge. Moreover, with only 5% calcium carbonate content, the initial thermal degradation temperature of CAS was increased by 70 °C (from 150 to 220 °C), compared to that of calcium alginate, which met the requirements of high-temperature resistant and nonflammable materials. The thermal degradation mechanism of CAS was supposed based on the experimental data. The combined results suggest promising prospects for the application of CAS in a range of fields and the sponge materials provide an alternative for the commonly used PU and PS sponge materials.

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