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1.
Medicine (Baltimore) ; 103(42): e40162, 2024 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-39432623

RESUMO

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder affecting women of reproductive age, affecting reproductive health, and increasing the incidence of diabetes mellitus and hypertension. Metabolic syndrome (MetS) is the most common metabolic disorder. Although clinical studies have shown a close association between PCOS and MetS, the molecular mechanisms are unknown. In this study, datasets of PCOS and MetS were obtained from the Gene Expression Omnibus database; differential expression analysis and weighted gene coexpression network analysis (WGCNA) were performed; and gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses also performed of differentially expressed genes (DEGs). The PCOS- and MetS-coexpressed DEGs were subsequently intersected with the coexpressed genes in the WGCNA module to obtain the core genes. By constructing receiver operating characteristic curves, we verified the predictive effects of the core genes. We also validated the expression of the core genes in the datasets. Finally, we verified the expression of the core genes by quantitative polymerase chain reaction in human follicular fluid granulosa cells. In addition, we used Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts to analyze the immune infiltration of immune cells in PCOS and MetS. Finally, we obtained 52 coexpressed DEGs of PCOS and MetS and 3 coexpressed genes in the WGCNA module. By taking the intersection of coexpressed DEGs and coexpressed genes of the WGCNA module, we get ELOVL fatty acid elongase 7 (ELOVL7) as the core gene. Receiver operating characteristic curve analysis showed that ELOVL7 is a reliable biological marker for PCOS and MetS. The expression level of ELOVL7 in human follicular fluid granulosa cells from PCOS patients was significantly higher than that of controls, as verified by quantitative polymerase chain reaction. This study provides the first evidence of the role of ELOVL7 in developing PCOS and MetS. This gene may serve as a potential diagnostic marker and therapeutic target for both conditions.


Assuntos
Síndrome Metabólica , Síndrome do Ovário Policístico , Síndrome do Ovário Policístico/genética , Humanos , Feminino , Síndrome Metabólica/genética , Curva ROC , Perfilação da Expressão Gênica/métodos , Redes Reguladoras de Genes , Células da Granulosa/metabolismo , Líquido Folicular/metabolismo , Adulto
2.
Adv Sci (Weinh) ; 11(31): e2402889, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38894560

RESUMO

The inefficiency of electrocatalysts for water splitting in neutral media stems from a comprehensive impact of poor intrinsic activity, a limited number of active sites, and inadequate mass transport. Herein, hierarchical ultrathin NiCo2Se4 nanosheets are synthesized by the selenization of NiCo2O4 porous nanoneedles. Theoretical and experimental investigations reveal that the intrinsic hydrogen evolution reaction (HER) activity primarily originate from the NiCo2Se4, whereas the high oxygen evolution reaction (OER) performance is related to the NiCoOOH due to the structural reconstruction. The abundant Se and O vacancies introduced by atomically thin nanostructure modulate the electronic structure of NiCo2Se4 and NiCoOOH, thereby improving the intrinsic HER and OER activities, respectively. COMSOL simulation demonstrate the edges of extended nanosheets from the main body significantly promote the charge aggregation, boosting the reduction and oxidation current during HER/OER process. This charge aggregation effect notably exceeds the tip effect for the nanoneedle, highlighting the unique advantage of the hierarchical nanosheet structure. Benefiting from abundant vacancies and unique nanostructure, the hierarchical ultrathin nanosheet simultaneously improve the thermodynamics and kinetics of the electrocatalyst. The optimized samples display an overpotential of 92 mV for HER and 214 mV for OER at 100 mA cm-2, significantly surpassing the performance of currently reported HER/OER catalysts in neutral media.

3.
Nanomicro Lett ; 16(1): 196, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38753068

RESUMO

Phase change materials (PCMs) offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization. However, for organic solid-liquid PCMs, issues such as leakage, low thermal conductivity, lack of efficient solar-thermal media, and flammability have constrained their broad applications. Herein, we present an innovative class of versatile composite phase change materials (CPCMs) developed through a facile and environmentally friendly synthesis approach, leveraging the inherent anisotropy and unidirectional porosity of wood aerogel (nanowood) to support polyethylene glycol (PEG). The wood modification process involves the incorporation of phytic acid (PA) and MXene hybrid structure through an evaporation-induced assembly method, which could impart non-leaking PEG filling while concurrently facilitating thermal conduction, light absorption, and flame-retardant. Consequently, the as-prepared wood-based CPCMs showcase enhanced thermal conductivity (0.82 W m-1 K-1, about 4.6 times than PEG) as well as high latent heat of 135.5 kJ kg-1 (91.5% encapsulation) with thermal durability and stability throughout at least 200 heating and cooling cycles, featuring dramatic solar-thermal conversion efficiency up to 98.58%. In addition, with the synergistic effect of phytic acid and MXene, the flame-retardant performance of the CPCMs has been significantly enhanced, showing a self-extinguishing behavior. Moreover, the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs, relieving contemporary health hazards associated with electromagnetic waves. Overall, we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs, showcasing the operational principle through a proof-of-concept prototype system.

4.
Bioresour Technol ; 394: 130268, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38154737

RESUMO

The complexity of biomass components leads to significant variations in the performance of biomass-based carbon dots (CDs). To shed light on this matter, this study presents a comparative analysis of the fluorescence properties of CDs using pure cellulose, lignin, and protein as models. Three CDs showed different fluorescent properties, resulting from the structure difference and carbonization behavior in the hydrothermal. The relatively gentle thermal degradation of proteins allows the macromolecular structure of amino acids to be preserved. This preservation results in a more regular lattice structure, a larger sp2 domain size, and N-doping, which contribute to the highest quantum yield (QY) of 8.7% of the CDs. In contrast, cellulose undergoes more severe thermal degradation with large amounts of small molecules generated, resulting in the CDs with fewer surface defects, more irregular lattice structures, and lower QY. These results provide a guideline for the design of carbon dots from different biomass.


Assuntos
Celulose , Lignina , Celulose/química , Carbono/química , Biomassa , Fluorescência , Corantes , Corantes Fluorescentes/química
5.
BMC Genomics ; 24(1): 710, 2023 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-37996781

RESUMO

Colletotrichum siamense is a hemibiotrophic ascomycetous fungus responsible for mango anthracnose. The key genes involved in C. siamense infection remained largely unknown. In this study, we conducted weighted gene co-expression network analysis (WGCNA) of RNA-seq data to mine key genes involved in Colletotrichum siamense-mango interactions. Gene modules of Turquoise and Salmon, containing 1039 and 139 respectively, were associated with C. siamense infection, which were conducted for further analysis. GO enrichment analysis revealed that protein synthesis, organonitrogen compound biosynthetic and metabolic process, and endoplasmic reticulum-related genes were associated with C. siamense infection. A total of 568 proteins had homologs in the PHI database, 370 of which were related to virulence. The hub genes in each module were identified, which were annotated as O-methyltransferase (Salmon) and Clock-controlled protein 6 (Turquoise). A total of 24 proteins exhibited characteristics of SCRPs. By using transient expression in Nicotiana benthamiana, the SCRPs of XM_036637681.1 could inhibit programmed cell death (PCD) that induced by BAX (BCL-2-associated X protein), suggesting that it may play important roles in C. siamense infection. A mango-C. siamense co-expression network was constructed, and the mango gene of XM_044632979.1 (auxin-induced protein 15A-like) was positively associated with 5 SCRPs. These findings help to deepen the current understanding of necrotrophic stage in C. siamense infection.


Assuntos
Colletotrichum , Mangifera , Mangifera/genética , Mangifera/microbiologia , Redes Reguladoras de Genes , Perfilação da Expressão Gênica , Colletotrichum/genética
6.
Int J Biol Macromol ; 245: 125511, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37356693

RESUMO

Large bone defects have presented a significant challenge in orthopedic treatments, and the emergence of tissue-engineered scaffolds has introduced new avenues for treatment. Nonetheless, the clinical application of such scaffolds has been hindered by drawbacks like inadequate mechanical properties, and deficient osteogenesis. Herein, a biocompatible polylactic acid (PLA) based composite was proposed to emulate cancellous bone's morphology by incorporating nano-hydroxyapatite (nHA). In addition, a quantity of Mg2+ and chitosan (CS) as active osteogenic factors were adopted to imitate the bone marrow mesenchymal components in vivo. Using a pre-evaporated solvent and sacrificial multi-template techniques, the cellular PLA-based tissue engineering scaffolds containing macropores larger than 100 µm and micropores smaller than 10 µm were developed. The scaffold's bionic structure, osteogenic active component, and multi-scale cellular make it comparable to cancellous bone, with favorable mechanical properties and hydrophilicity. Vitro tests using Sprague-Dawley (SD) rat bone marrow mesenchymal stem cells (rBMSCs) demonstrated the scaffold's excellent biocompatibility to induce high efficiency of osteogenic differentiation. The bionic porous scaffold with multi-scale cellular structure also can recruit rBMSCs, promote bone regrowth and osteogenic differentiation, and facilitate the regeneration of defective bone tissue for repair. This contribution presented a promising strategy for future advancements in bone tissue engineering.


Assuntos
Biônica , Osteogênese , Ratos , Animais , Ratos Sprague-Dawley , Alicerces Teciduais/química , Osso e Ossos , Poliésteres/farmacologia , Poliésteres/química , Engenharia Tecidual/métodos , Diferenciação Celular , Regeneração Óssea
7.
Small ; 19(36): e2301378, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37127873

RESUMO

Flexible piezoresistive sensors with biological structures are widely exploited for high sensitivity and detection. However, the conventional bionic structure pressure sensors usually suffer from irreconcilable conflicts between high sensitivity and wide detection response range. Herein, a triple periodic minimum surface (TPMS) structure sensor is proposed based on parametric structural design and 3D printing techniques. Upon tailoring of the dedicated structural parameters, the resulting sensors exhibit superior compression durability, high sensitivity, and ultra-high detection range, that enabling it meets the needs of various scenes. As a model system, TPMS structure sensor with 40.5% porosity exhibits an ultra-high sensitivity (132 kPa-1 in 0-5.7 MPa), wide detection strain range (0-31.2%), high repeatability and durability (1000 cycles in 4.41 MPa, 10000 s in 1.32 MPa), and low detection limit (1% in 80 kPa). The stress/strain distributions have been identified using finite element analysis. Toward practical applications, the TPMS structural sensors can be applied to detect human activity and health monitoring (i.e., voice recognition, finger pressure, sitting, standing, walking, and falling down behaviors). The synergistic effects of MWCNTs and MXene conductive network also ensure the composite further being utilized for electromagnetic interference shielding applications.

8.
Environ Technol ; 44(5): 631-646, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34516358

RESUMO

The adsorption of chlorinated aromatic compounds (CACs) on pristine biochar was often limited. Surface modification can greatly improve the adsorption capacity of biochar. In this work, by pyrolysis activation of rubber-seed shell wastes, nitrogen auto-doped biochar (RSS-NBC) was synthesized and used for purifying CACs-containing wastewater. Systematic characterization results showed that after proper treatment, the as-prepared RSS-NBC had high specific surface area, abundant surface oxygen- and nitrogen-containing functional groups, and nano-scale pore structure. Batch adsorption experiments were conducted with using three typical CACs probing pollutants, i.e. 1,2-dichlorobenzene (1,2-DCB), 2,4-dichlorophenol (2,4-DCP) and 2,4-dichlorobenzoic acid (2,4-DCBA). The adsorption experiments results showed that the maximum adsorption amounts of 1, 2-DCB, 2,4-DCP, and 2,4-DCBA could reach 2284, 1921, and 1142 mg/g at 298.15 K. Moreover, 90% of the equilibrium adsorption amount can be reached within 0.5 h. The adsorption kinetic results showed that the adsorption processes of the three CACs followed the pseudo-second-order rate model and were dominated by chemisorption. Also, the adsorption isotherms of 1, 2-DCB and 2, 4-DCP belonged to the Freundlich model and were valid for multilayer adsorption, while the adsorption of 2,4-DCBA followed Langmuir model and single-layer adsorption. The thermodynamics data indicated that the spontaneous adsorption process of 1, 2-DCB and 2, 4-DCP was endothermic while that of 2,4-DCBA was exothermic. After 5 cycles of adsorption-regeneration, the removal efficiency of RSS-NBC particles still remained more than 80% for the three typical CACs, indicating that it could be reused as an effective and retrievable adsorbent in the treatment of CACs-containing effluents.


Assuntos
Borracha , Poluentes Químicos da Água , Adsorção , Pirólise , Carvão Vegetal/química , Água , Cinética
9.
Environ Technol ; 44(7): 936-947, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34605717

RESUMO

With the decrease in the phosphate rock grade, the minor element ratios (MER) [(Fe2O3 wt% + Al2O3 wt% + MgO wt%)/P2O5 wt%] of wet-process phosphoric acid (WPA) exhibits a linear upward trend. This can lead to a huge challenge for the high-quality production of feed calcium phosphate salt (FCPS). In the present study, we proposed a novel and economical strategy to precipitate Al3+ and Mg2+ via the formation of aluminofluoride complexes (NaMgAlF6·H2O) with the anhydrous sodium sulfate (Na2SO4) and hydrofluoric acid (HF) as precipitation agents. Because of the low solubility of the complexes in WPA, the removal efficiencies of Al3+ and Mg2+ ions could reach 99.5% and 64.8%, respectively. The maximum mass loss of P2O5 was less than 0.5%. The precipitates could be separated and converted into the HF and Na2SO4 for reuse, thus further decreasing the cost of WPA purification.


Assuntos
Fosfatos , Ácidos Fosfóricos
10.
Environ Technol ; : 1-9, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35938293

RESUMO

As a byproduct of the industrial synthesis of phosphoric acid, there was a large quantity of phosphor gypsum (PG) accumulation, which needs enormous storage space and endangers the environment. The preparation of calcium sulfate whisker (CSW) from waste PG could solve the large amounts of PG accumulation and substitute the plant-based pulp fiber, reducing the pollution of wastewater in paper and pulp industries. In this work, the CSW, which length could reach 230 µm, was fabricated from the PG in a glycerol-water solution. It could be found that the glycerol-water volume ratio of 4:6 was the best ratio that could reduce the water activity and accelerate the phase transition from calcium sulfate dihydrate (CSD) to CSW. Meanwhile, the CSW, after calcination, could prepare the anhydrous calcium sulfate whisker (ACSW) with low solubility in water; when the ACSW substitution rate reached 50%, the property of the complex paper could still satisfy the standard of mechanical and optical for offset book paper.

11.
J Thorac Dis ; 14(12): 4773-4784, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36647491

RESUMO

Background: Study have shown that atrial fibrillation (AF) is a disease with genetic risk, and its pathogenesis is still unclear. This study sought to screen the gene microarray data of AF patients and to perform a bioinformatics analysis to identify AF signature diagnostic genes. Methods: The AF gene sets from the Gene Expression Omnibus (GEO) database were screened, and the differentially expressed genes (DEGs) were identified after the normalization of the data set by R software. We conducted a gene set enrichment analysis, a protein-protein interaction (PPI) network analysis, a gene-gene interaction (GGI) network analysis, and an immuno-infiltration analysis. The core genes were identified from the DEGs, and base on receiver operating characteristic, the top 5 core genes in the 2 data sets were selected as diagnostic factors and a nomogram was constructed. The miRNA of the core genes were predicted and an immune cell correlation analysis was performed. Results: A total of 20 DEGs were identified. The functions of these DEGs were mainly related to muscle contraction, autophagosome, and bone morphogenetic protein (BMP) binding, and focused on the calcium signaling pathway, ferroptosis, the extracellular matrix-receptor interaction, and other pathways. A total of 5 core genes [i.e., GPR22 (G protein-coupled receptor 22), COG5 (component of oligomeric golgi complex 5), GALNT16 (polypeptide N-acetylgalactosaminyltransferase 16), OTOGL (otogelin-like), and MCOLN3 (mucolipin 3)] were identified, and a linear model for risk prediction was constructed, which has good prediction ability. Plasma cells and Macrophages M2 were significantly increased in AF, while T cells follicular helper and Dendritic cells activated were significantly decreased. Conclusions: In our study, we identified 5 potential diagnostic key genes (i.e., GPR22, COG5, GALNT16, OTOGL, and MCOLN3). Our findings may provide a theoretical basis for susceptibility analyses and target drug development in AF.

12.
J Colloid Interface Sci ; 606(Pt 1): 223-235, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34390990

RESUMO

Recently, two-dimensional MXene demonstrated promising advantages to improve the flame-retardant performance of composites; however, its compatibility with polymer matrix is a great concern. In this study, MXene was first functionalized with phosphorylated chitosan (PCS) to obtain the PCS-MXene nanohybrid. The resulting nanohybrid was introduced into the thermoplastic polyurethane (TPU) matrix via solution mixing followed by the hot-pressing method, affording TPU/PCS-MXene nanocomposite. The resulting nanohybrid exhibited superior compatibility with the TPU matrix, enhancing mechanical performance of the TPU/PCS-MXene nanocomposite compared to the pristine TPU and TPU/MXene nanocomposite. Besides, the flame-retardant performance of TPU/PCS-MXene nanocomposite was greatly enhanced, while the smoke emission was effectively suppressed. As only 3 wt% PCS-MXene was introduced, peak heat release rate, total heat release, and total smoke production of the composite decreased by 66.7%, 21.0%, and 27.7%, respectively, compared to the pristine TPU. Systematical characterization was then carried out to investigate the enhancement mechanism of PCS-MXene, highlighting the crucial role of PCS combined with the catalytic effect of MXene. In brief, the compatibility issues of MXene were effectively addressed, and its flame-retardancy enhanced greatly via the PCS modification, the bio-based characteristic of which, in turn greatly benefits the further development of MXene-polymer composite.


Assuntos
Quitosana , Retardadores de Chama , Nanocompostos , Poliuretanos , Fumaça
13.
Biomass Convers Biorefin ; : 1-13, 2021 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-34549016

RESUMO

Numerous studies have shown that patients with COVID-19 have a high incidence of renal dysfunction. However, the dialysis supplies, including dialysates, are also severely inadequate in hospitals at the pandemic centers. Therefore, there is an urgent need to develop materials that can efficiently and rapidly remove toxins and thus regenerate dialysate to make this vital resource remains readily available. In this work, by simple carbonization and activation treatment, the porous activated carbon from waste rubber seed shell (RAC) was prepared. The adsorption results showed that the maximum adsorption capacities of the obtained RAC for creatinine and uric acid were 430 mg/g and 504 mg/g, respectively. Significantly, the adsorption process can be close to the equilibrium state within 0.5 h, which proved the ultra-fast adsorption response capacity of RAC. Further, the thermodynamics analysis results showed that both the creatinine and uric acid adsorption processes were monolayer, exothermic, and spontaneous. The adsorption kinetics results indicated that the adsorption process of the two uremic toxins followed the pseudo-second-order rate model and was dominated by chemisorption. The instrument analysis results reflected the efficient adsorption of the RAC for the above uremic toxins which might be due to the dipole-dipole interaction between the dipolar oxygen-containing groups of the surface of RAC and the dipoles of the toxins. Moreover, the formed hydrogen bonds between the oxygen groups and the toxins also played an important role. In all, the as-prepared RAC has the potential to efficiently remove major toxins from the dialysate and can be used in in vitro dialysis of numerous patients during the current COVID-19 pandemic.

14.
J Nanosci Nanotechnol ; 19(12): 7943-7946, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31196313

RESUMO

A facile synthesis approach of urchin-like and bouquet-like silver nanoparticles (AgNPs) using gas assisted wet chemistry method with silver nitride as source materials, ascorbic acid as reducing agent, polyvinylpyrrolidone (PVP) as passivator and NO2/O2 as ventilation mixture is proposed It was demonstrated that the urchin-like and bouquet-like AgNPs evolved from spherical nanoparti cles and/or clusters of Ag as a result of strong adsorption and passivation of newly-formed Ag {100} facets by PVP, which effectively boost preferential growth. The NO2/O2 as the ventilation mixture provides an equilibrium of aggregation and detachment of Ag atoms on the surface, thus confining the shapes of AgNPs generated. This study provides an alternative approach for synthesis AgNPs in specific shapes and facilitates their applications.

15.
Polymers (Basel) ; 11(1)2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30960072

RESUMO

A simple and versatile route for industrial scale synthesis of adipicdihydrazide (ADH)/polymer hybrids with excellent performance of formaldehyde degradation is proposed in this paper. The ADH compound is uniformly dispersed in poly(methyl methacrylate-butyl acrylate-methacrylic acid) (P(MMA-BA-MAA)) latex, which is validated by UV and dispersibility tests. The results illustrate that ADH has excellent compatibility and dispersion stability without affecting the film formation of the polymer latex. Furthermore, scanning electron microscope (SEM) and mapping analysis of the hybrid films also demonstrate that ADH is homogenously dispersed in the polymer matrix. Compared with neat polymers, the thermal properties of hybrid films are improved, for example, T0.5 increases by 8.3 °C. According to qualitative tests of the 4-amino-3-hydrazino-5-mercapto-1,2,4-triazol-red/green/blue (AHMT-RGB) method, the hybrid films demonstrate high formaldehyde removal efficiency. On the basis of the semi-quantitative test of Fourier Transform infrared spectroscopy (FTIR) measurements, the rate of formaldehyde degradation can reach 1.034 × 10² mol/(h·m³) for the hybrid film with 5 wt% ADH.

16.
Polymers (Basel) ; 11(2)2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30960177

RESUMO

A simple and novel route is developed for fabricating BP-based composite materials to improve the thermo-stability, flame retardant performances, and mechanical performances of polymers. Black phosphorene (BP) has outstanding flame retardant properties, however, it causes the mechanical degradation of waterborne polyurethane (WPU). In order to solve this problem, the graphene is introduced to fabricate the black phosphorene/graphene (BP/G) composite material by high-pressure nano-homogenizer machine (HNHM). The structure, thermo-stability, flame retardant properties, and mechanical performance of composites are analyzed by a series of tests. The structure characterization results show that the BP/G composite material can distribute uniformly into the WPU. The addition of BP/G significantly improves the residues of WPU in both of TG analysis (5.64%) and cone calorimeter (CC) test (12.50%), which indicate that the BP/G can effectively restrict the degradation of WPU under high temperature. The CC test indicates that BP/G/WPU has a lower peak release rate (PHRR) and total heat release (THR), which decrease by 48.18% and 38.63%, respectively, than that of the pure WPU, respectively. The mechanical analysis presents that the Young's modulus of the BP/G/WPU has an increase of seven times more than that of the BP/WPU, which indicates that the introduce of graphene can effectively improve the mechanical properties of BP/WPU.

17.
Polymers (Basel) ; 10(3)2018 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30966262

RESUMO

Black phosphorene-waterborne polyurethane (BPWPU) composite polymer with 0.2 wt % of black phosphorene was synthesized. Scanning electron microscopy (SEM) was used to observe the morphology of phosphorene in polyurethane matrix, which indicated that the phosphorene distributes uniformly in the PU matrix. The flammability measurements were carried out to investigate the flame-resistant performances of phosphorene, which indicated that phosphorene could effectively restrict the degradation of the PU membrane. Compared by the pure WPU, the limiting oxygen index (LOI) of BPWPU increased by 2.6%, the heat flow determined by thermal analysis significantly decreased by 34.7% moreover, the peak heat release rate (PHRR) decreased by 10.3%.

18.
Soft Matter ; 12(27): 5876-82, 2016 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-27334421

RESUMO

A general methodology has been developed for preparing nanocomposites with uniform, random distribution of fillers in polymer matrices, purely based on intense shear-driven aggregation, while avoiding filler aggregation. This procedure is demonstrated for a binary colloid composed of graphene oxide (GO) sheets and poly-vinylidene fluoride (PVDF) nanoparticles (NPs), both negatively charged and stable at rest. On the other hand, the PVDF NPs are shear-active (i.e. aggregation occurs under intensive shear), while the GO sheets are shear-inactive. It is found that when the two suspensions are mixed and the resulting binary colloid is forced to pass through a microchannel (MC) device (at a very high shear rate, G = 1.2 × 10(6) s(-1)), the shear-inactive GO sheets are captured and well distributed inside the PVDF NP clusters or gels. In addition, it is shown that in order to have 100% capture efficiency for the GO sheets, a minimum solid content of the binary colloid is required, which can be identified experimentally as the minimum leading to gelation after passing through the MC only one time.

19.
ACS Macro Lett ; 5(2): 174-176, 2016 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-35614694

RESUMO

Red blood cell (RBC)-like particles have shown great interest as a model for the understanding of the cell behavior and as promising biomaterials in targeted drug delivery. In this study, a simple and versatile route was proposed for the large-scale synthesis of monodisperse and well-defined RBC-like PS particles using divinylbenzene (DVB) as the cross-linker and ethanol as reaction medium. RBC-like particles were obtained due to the asymmetric shrinkage of a cross-linked network during the phase separation process. An ordered self-assembly monolayer with the concave facing up at the air-water interface was also demonstrated.

20.
Phys Chem Chem Phys ; 14(41): 14374-82, 2012 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-23011512

RESUMO

The effect of polymeric surfactants, copolymers of n-butyl acrylate (BA) and acrylic acid (AA), on shear-induced gelation of a colloidal system in the absence of additional electrolytes is studied. One random (PBA-co-PAA) and two block copolymer (PBA-b-PAA, with different PAA lengths) surfactants have been synthesized by ATRP and used in this work. The colloidal system is composed of strawberry-like particles with a rubbery core, partially covered by a few grafted plastic patches. In the absence of any surfactant, as the colloidal system passes through a microchannel at a Peclet number of 220 and a particle volume fraction of 0.15, shear-induced gelation occurs and the particles coalesce partially, due to the rubbery core, leading to a fractal dimension of the clusters constituting the gel equal to 2.78. On the other hand, in the presence of any of the three polymeric surfactants, shear-induced gelation occurs only in the range of low surfactant surface density. Meanwhile, the fractal dimension of the clusters decreases with adsorption of the two block surfactants, reaching a plateau value of about 2.58, while for the random surfactant it remains constant and equal to 2.78, like in the absence of any surfactant. This indicates that adsorption of the block surfactants can reduce the particle coalescence, while adsorption of the random surfactant cannot. Moreover, for all three surfactants, as their surface density increases progressively, a transition from solid-like gel to a liquid-like state occurs and finally no shear-induced gelation or even aggregation occurs. Since the three surfactants comprise carboxylic groups, considering also the results in the literature (Zaccone et al., J. Phys. Chem. B, 2008, 112, 1976; 6793), we can reach a general conclusion that carboxylic groups on the particle surface not only stabilize the particles through electrostatic repulsion, but also generate very short-range, strongly repulsive (e.g. hydration, steric) forces, which when high enough protect the particles from intense shear-activated aggregation.

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