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1.
Chem Rec ; 23(11): e202300184, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37495934

RESUMO

Traditional energy from fossil fuels like petroleum and coal is limited and contributes to global environmental pollution and climate change. Developing sustainable and eco-friendly energy is crucial for addressing significant challenges such as climate change, energy dilemma and achieving the long-term development of human society. Biomass hydrogels, which are easily synthesized and modified, have diverse sources and can be designed for different applications. They are being extensively researched for their applications in artificial intelligence, flexible sensing, biomedicine, and food packaging. The article summarizes recent advances in the preparation and applications of biomass-based photothermal conversion hydrogels, discussing the light source, photothermal agents, matrix, and preparation methods in detail. It also explores the use of these hydrogels in seawater desalination, photothermal therapy, antibacterial agents, and light-activated materials, offering new ideas for developing sustainable, efficient, and advanced photothermal conversion biomass hydrogel materials. The article concludes with suggestions for future research, highlighting the challenges and prospects in this field and paving the way for developing of long-lasting, efficient energy materials.


Assuntos
Inteligência Artificial , Hidrogéis , Humanos , Antibacterianos/farmacologia , Materiais Biocompatíveis , Biomassa
2.
Environ Res ; 227: 115803, 2023 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-37003546

RESUMO

Marine sediments are the world's largest known reservoir of methane. In many coastal regions, methane is trapped in sediments buried at depths ranging from centimeters to hundreds of meters below the seafloor, in the forms of gas pockets, dispersed gas bubbles and dissolved gas, also known as shallow gas (methane-dominated gas mixture). The existence of shallow gas affects the engineering geological environment and threatens the safety of artificial facilities. The escape of shallow gas from sediments into the atmosphere can even threaten ecosystem security and affect global climate change. However, until now, shallow gas has remained a mystery to the scientific community. For example, how it is generated, how it distributes and migrates in sediments, and what are the factors that influence these processes that are still unclear. In the context of increasingly intense offshore development and global warming, there is a huge gap between existing scientific understanding of shallow gas and the need to develop scientific solutions for related problems. Based on this, this paper systematically collects the information on all aspects of shallow gas mentioned above, comprehensively summarizes the current scientific understanding, and analyzes the existing shortcomings, which will provide systematic references for the research on environmental disaster prevention, engineering technology, climate change, and other fields.


Assuntos
Ecossistema , Metano , Mudança Climática , Aquecimento Global , Atmosfera , Sedimentos Geológicos
3.
Analyst ; 147(21): 4657-4673, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36155993

RESUMO

Biomass materials have abundant natural resources, renewability and good biochemical compatibility, so biomass-based fluorescent materials prepared from biomass materials have gradually become a research hotspot. In particular, the low cost and environmentally friendly properties of chitosan have been widely used in the field of functional materials. Chitosan-based functional materials have attracted extensive attention in the detection and removal of organic and inorganic pollutants. They have been widely used in biological imaging, environmental detection, drug carriers and other fields. This paper reviews the preparation and application of chitosan-based fluorescent probes, including chitosan-derived fluorescent probe materials and chitosan-based carbon quantum dots. At the same time, it focuses on the application research of chitosan-based carbon quantum dots in the fields of environmental detection, cell imaging, drug carriers, photocatalysis, etc. In addition, it provides new ideas and application prospects for the development and application of chitosan-based fluorescent materials in the future.


Assuntos
Quitosana , Poluentes Ambientais , Pontos Quânticos , Corantes Fluorescentes/química , Quitosana/química , Pontos Quânticos/química , Carbono/química , Portadores de Fármacos
4.
Biofouling ; 38(2): 173-185, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35196921

RESUMO

Previous studies have demonstrated the antibacterial activity of paeonol against bacterial pathogens, but its anti-biofilm activities against Staphylococcus aureus and Listeria monocytogenes remain largely unexplored. Here, the antibacterial and anti-biofilm activities of paeonol against S. aureus and L. monocytogenes were examined using the crystal violet staining assay (CVSA), field emission scanning electron microscopy (FESEM), and confocal laser scanning microscopy (CLSM) analysis. Paeonol effectively inhibited the growth of S. aureus and L. monocytogenes with a minimum inhibitory concentration (MIC) of 500 and 125 µg ml-1, respectively, and disrupted the integrity of cell membranes. Moreover, sub-MIC paeonol exhibited an inhibitory effect on the attachment of S. aureus and L. monocytogenes to the abiotic surface and biofilm formation. Further, paeonol effectively destroyed cell membranes within biofilms, and dispersed mature biofilms of both strains. The results indicate that paeonol might be a promising antibacterial and anti-biofilm agent for combating infections caused by S. aureus and L. monocytogenes.


Assuntos
Listeria monocytogenes , Infecções Estafilocócicas , Acetofenonas , Antibacterianos/farmacologia , Biofilmes , Humanos , Staphylococcus aureus
5.
Polymers (Basel) ; 16(2)2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38256988

RESUMO

In this work, acrylic cellulose hydrogel, a typical natural polymer adsorbent, was modified using MXene through in situ polymerization to create a synthetic inorganic-polymer composite known as MXene/cellulose hydrogel. FTIR, XRD, SEM, and thermogravimetric analyses were applied to characterize the chemical structure and micromorphology. The MXene/cellulose hydrogel was utilized for the removal of Pb2+ from wastewater. Under optimal experimental conditions (initial Pb2+ concentration of 0.04 mol/L, adsorption time of 150 min, pH = 5.5, and MXene doping content of 50% at 30 °C), a maximum adsorption capacity of 410.57 mg/g was achieved. The MXene/cellulose hydrogel corresponded with the pseudo-second-order kinetic equation model and exhibited a better fit with the Freundlich isotherm model.

6.
Int J Biol Macromol ; 270(Pt 1): 132088, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38723821

RESUMO

Chitosan, as a natural biomass material, is green, recyclable, sustainable and well biocompatible. The molecular chain is rich in active groups such as amino and hydroxyl groups, and its preparation of fluorescent probes has the advantages of biocompatibility and efficient detection performance. In this study, a bis(benzaldehyde) (BHD) fluorescent functional molecule was designed. Then a series of fluorescent chitosan-based hydrogel films (CSBHD) were prepared using chitosan as raw material and BHD as cross-linking agent. As a fluorescent probe for metal ions, CSBHD was able to efficiently detect Fe2+ with a linear correlation of fluorescence intensity in the range of 0-160 µM, and the limit of detection (LOD) was 0.55 µM. Moreover, it has excellent adsorption performance for Fe2+ ions, with a maximum adsorption capacity of 223.5 g/mg at 500 mg/L Fe2+ concentration. Finally, we characterised the structure and microscopic morphology of CSBHD films and found that CSBHD as a hydrogel film has a high cross-linking density, good water resistance, excellent thermal stability, strong resistance to swelling, and excellent stability in cycling tests. Hence, it has great potential for application in adsorption and detection of Fe2+ ions. It also provides a good strategy for the application of chitosan based fluorescent probe materials in environmental monitoring and heavy metal ion adsorption.


Assuntos
Benzaldeídos , Quitosana , Corantes Fluorescentes , Hidrogéis , Ferro , Quitosana/química , Adsorção , Hidrogéis/química , Ferro/química , Benzaldeídos/química , Corantes Fluorescentes/química , Reagentes de Ligações Cruzadas/química , Limite de Detecção , Membranas Artificiais , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
7.
J Thorac Dis ; 16(7): 4693-4701, 2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-39144344

RESUMO

This study aimed to design a standardised bronchoscopic holmium laser ablation continuous cryoablation for the treatment of airway stenosis caused by tissue hyperplasia after tracheal intubation and to retrospectively analyse its safety and feasibility. We collected the data of patients who had undergone bronchoscopic holmium laser ablation continuous cryoablation due to airway stenosis caused by tracheal mucosal tissue hyperplasia after tracheal intubation. The patients' baseline characteristics, ablation effects, surgical complications and other data were analysed. In total, 16 patients were enrolled in this study. On average, airway stenosis occurred 96.00 (interquartile range, 69.75-152.50) days after tracheal intubation and bronchoscopic holmium laser ablation continuous cryoablation took an average of 90.38 minutes (standard deviation: 16.78). After the first continuous cryoablation, 75.0% (12/16) of the patients had complete ablation of hyperplastic tissue, and 25.0% (4/16) had most of the hyperplastic tissue (>50%) removed. Altogether, 18.75% (3/16) and 6.25% (1/16) of the patients had complete ablation of hyperplastic tissue after the second and third cryoablation, respectively. Moreover, one patient (6.25%) had minimal wound bleeding postoperatively, and no other surgical complications occurred. No airway stenosis was found in all enrolled patients during follow-up 1 and 6 months after the last cryoablation. According to the above results of our small sample study indicated that bronchoscopic holmium laser ablation continuous cryoablation seems safe and effective for treating airway stenosis caused by tissue hyperplasia after tracheal intubation.

8.
Int J Biol Macromol ; 280(Pt 1): 135649, 2024 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-39284472

RESUMO

The objective of this study was to prepare an active packaging film using phosphorylated soy protein isolate (PPS) and Artemisia sphaerocephala Krasch. gum (ASKG) as film matrices, with the incorporation of pomegranate peel extract (PPE) to preserve fresh-cut apples. The results showed that PA-PPE (PPS/ASKG-PPE) films significantly increased thickness by 24.47 %, tensile strength by 58.76 %, and elongation at break by 30.48 %. Additionally, water vapor permeability and oxygen permeability decreased significantly to 6.17 × 10-13 and 0.62 × 10-13 Kg•m•m-2•s-1•Pa-1, respectively. FTIR, XRD, and SEM analyses confirmed the formation of intermolecular hydrogen bonds between PPS, ASKG, and polyphenols extracted from pomegranate peel, indicating excellent compatibility. Furthermore, radical scavenging activity experiments demonstrated that these films exhibited a remarkable ability to scavenge DPPH and ABTS+ radicals up to 70.44 % and 74.28 %, respectively, when the PPE content was at 3 wt%. Moreover, PPS could achieve a sustained release effect on polyphenols with a relatively low release rate (63.83 %) even after seven days' time elapsed. Finally, the PA-PPE film displayed superior performance in reducing the weight loss and browning index of fresh-cut apples within 24 h of storage. The development of PA-PPE film could promote sustainable resource protection and demonstrate promising prospects in the field of fresh-cut fruit packaging.

9.
Environ Sci Pollut Res Int ; 30(17): 49905-49916, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36787067

RESUMO

Foam concrete possesses low density and excellent thermal insulation properties and has been widely used in construction industry. Considering the recycling and reusing of coal gasification slag (CGS), a solid waste product in the coal chemical industry, CGS was used as the supplementary cementations material to prepare foam concrete (CGS-FC) in this work. The influence of the CGS content and water-binder ratio on the pore structure, mechanical and thermal properties was investigated. The results show that the CGS content and water-binder ratio directly impact the fluidity of the slurry, which affects the internal pore structure of the specimens after molding. And a CGS-FC with a compressive strength of 6.89 MPa, thermal conductivity of 0.24 W/m K, and a bulk density of 867 kg/m3 was successfully produced when the CGS content was 30% and water-binder ratio was 0.5. In particular, the utilization of CGS to prepare foam concrete product has recycling efficiency and environmental benefit.


Assuntos
Cinza de Carvão , Carvão Mineral , Resíduos Sólidos , Força Compressiva , Água
10.
Int J Biol Macromol ; 253(Pt 4): 127082, 2023 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-37769762

RESUMO

The design and development of a rapid and quantitative method for the detection of heavy metal ions is of great importance for environmental protection. We have prepared a 1,8-Naphthalimide modified cellulose composite fluorescent hydrogel (CENAEA/PAA) with a stereo double network structure. Characterized by excellent hydrogel functional structure and fluorescence detection performance, it can efficiently and selectively identify and detect Cr(VI) with linear quenching in the range of 0-400 µmol/L and detection limit of 0.58 µmol/L for Cr(VI). The results show that the CENAEA/PAA can effectively adsorb Cr(VI) with a maximum adsorption capacity of 189.04 mg/g. Finally, the morphological characteristics, chemical structure, fluorescence properties and adsorption behavior of CENAEA/PAA were analyzed and fitted well with the pseudo-second-order model and Freundlich model. Thus, the present work provides a green and sustainable approach for the synthesis of a functional material that can be used for the detection and adsorption of heavy metal ions.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Naftalimidas , Corantes Fluorescentes , Hidrogéis , Cromo/química , Íons , Celulose/química , Adsorção , Poluentes Químicos da Água/química , Cinética , Concentração de Íons de Hidrogênio
11.
Anal Methods ; 15(48): 6716-6721, 2023 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-38050678

RESUMO

Fe3+ is essential for humans, and its deficiency or excess can be harmful to human health; thus, it is crucial to detect Fe3+. Herein, a novel 1,8-naphthylimide rhodamine-based fluorescent probe (NA-RhBEA) was prepared from rhodamine B, anhydrous ethylenediamine, and 1,8-naphthoic anhydride. This fluorescent probe complexes Fe3+ with N and O on the carboxyl groups of its spironolactam structure and part of the 1,8-naphthalenedicarboxylic anhydride structure, which results in spironolactam ring-opening and fluorescence. NA-RhBEA has high selectivity for Fe3+ in ethanol/buffer solution (4 : 1, v/v), and fluorescence is detected at an excitation wavelength λEX = 500 nm, an absorption peak appears at 585 nm, and a significant color change appears. The effect of the fluorescence intensity of Fe3+ under a series of different concentration conditions was investigated, and it was concluded that the fluorescence intensity increased with increasing Fe3+ concentration in the range of 0-500 µmol, and its detection limit was 0.84 µmol L-1. In addition, we explored the detection ability of NA-RhBEA in solutions with different pH values, mixed metal ions, and different solvents, and the results showed that the fluorescent sensor also has good anti-interference properties and some practical applicability.

12.
Materials (Basel) ; 16(10)2023 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-37241455

RESUMO

A new pH-sensitive film was developed using Artemisia sphaerocephala Krasch. gum (ASKG), soybean protein isolate (SPI), and natural anthocyanin extracted from Lycium ruthenicum Murr. The film was prepared by adsorbing anthocyanins dissolved in an acidified alcohol solution on a solid matrix. ASKG and SPI were used as the solid matrix for the immobilization of the Lycium ruthenicum Murr. anthocyanin extract, which was absorbed into the film as a natural dye using the facile-dip method. Regarding the mechanical properties of the pH-sensitive film, the tensile strength (TS) values increased approximately 2-5-fold, but the elongation at break (EB) values decreased significantly by about 60% to 95%. With the increase in anthocyanin concentration, the oxygen permeability (OP) values first decreased by about 85%, and then increased by about 364%. The water vapor permeability (WVP) values increased by about 63%, and then decreased by about 20%. Colorimetric analysis of the films revealed variations in color at different pH values (pH 2.0-10.0). Fourier-transform infrared (FT-IR) spectra and XRD patterns indicated compatibility among ASKG, SPI, and anthocyanin extracts. In addition, an application test was conducted to establish a correlation between film color change and carp meat spoilage. At storage temperatures of 25 °C and 4 °C, when the meat was totally spoiled, the TVB-N values reached 99.80 ± 2.53 mg/100 g and 58.75 ± 1.49 mg/100 g, and the film's color changed from red to light brown and from red to yellowish green, respectively. Therefore, this pH-sensitive film could be used as an indicator to monitor the freshness of meat during storage.

13.
Int J Biol Macromol ; 242(Pt 2): 124915, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37211080

RESUMO

Chitosan is a kind of natural polysaccharide biomass with the second highest content in nature after cellulose, which has good biological properties such as biocompatibility, biodegradability, hemostasis, mucosal adsorption, non-toxicity, and antibacterial properties. Therefore, hydrogels prepared from chitosan have the advantages of good hydrophilicity, unique three-dimensional network structure, and good biocompatibility, so they have received extensive attention and research in environmental testing, adsorption, medical materials, and catalytic supports. Compared with traditional polymer hydrogels, biomass chitosan-based hydrogels have advantages such as low toxicity, excellent biocompatibility, outstanding processability, and low cost. This paper reviews the preparation of various chitosan-based hydrogels using chitosan as raw material and their applications in the fields of medical materials, environmental detection, catalytic carriers, and adsorption. Some views and prospects are put forward for the future research and development of chitosan-based hydrogels, and it is believed that chitosan-based hydrogels will be able to obtain more valuable applications.


Assuntos
Quitosana , Quitosana/química , Materiais Biocompatíveis/química , Hidrogéis/química , Polissacarídeos/química , Celulose
14.
Artigo em Inglês | MEDLINE | ID: mdl-38092062

RESUMO

OBJECTIVES: The aim of this study was to assess the impact of postoperative chest tube drainage (CTD) on safety and postoperative recovery by comparing patients with pulmonary nodule undergoing uniportal video-assisted thoracoscopic pulmonary wedge resection with and without postoperative CTD. METHODS: We retrospectively analysed the data of patients who underwent video-assisted thoracoscopic pulmonary wedge resection for pulmonary nodule at our hospital between 2018 and 2022. In cases where a 12-Fr chest tube was used following the procedure, the tube was not usually removed until the day after surgery. Therefore, the eligible patients were categorized into the drainage tube or the no-drainage tube group according to the use of postoperative CTD. Propensity score matching at a ratio of 1:1 was performed using clinicopathologic and demographic variables. The highest postoperative pain score, postoperative complication rate, postoperative length of stay and hospitalization costs were compared between the 2 groups. RESULTS: A total of 275 eligible patients, including 150 and 125 patients in the drainage tube and no-drainage tube groups, respectively, were included in the study. After propensity score matching, there were 102 patients in each group. The postoperative complication rate during hospitalization and at 1 week and 1 month after discharge were not significantly different between the 2 groups (P > 0.05 for all). The highest postoperative pain score was significantly lower in the no-drainage tube group than in the drainage tube group [2.02 (standard deviation: 0.81) days vs 2.31 (standard deviation: 0.76) days, P = 0.008]. The postoperative length of stay was significantly shorter in the no-drainage tube group than in the drainage tube group {3.00 [interquartile ranges (IQRs): 2.00-4.00] days vs 2.00 (IQRs: 1.00-3.00) days, P < 0.001}. Similarly, the total hospitalization costs were significantly lower in the no-drainage tube group than in the drainage tube group [33283.74 (IQRs: 27098.61-46718.56) yuan vs 26598.67 (IQRs: 22965.14-29933.67) yuan, P < 0.001]. CONCLUSIONS: Omission of postoperative CTD was safe and feasible in patients with pulmonary nodule undergoing wedge resection. The no-postoperative-drainage policy can substantially shorten the length of hospital stay and reduce the postoperative pain and hospitalization costs without increasing the risk of postoperative complications.

15.
Materials (Basel) ; 15(16)2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36013876

RESUMO

Cow hair, a by-product of tannery waste, is usually stockpiled on a large scale as waste, which leads to serious environmental impacts. In this paper, cow hair was used as a reinforcement fiber to improve the mechanical strength of iron tailing-based foam concrete. The effects of the amount of cow hair fiber on the apparent density, compressive strength, and flexural strength of foam concrete were investigated by a series of characterization methods. Meanwhile, Image-Pro Plus software was used to analyze the porosity, average pore size, roundness, and other parameters of the specimens with different amounts of cow hair fiber. Results revealed that a proper amount of cow hair fiber can form a stable three-dimensional network structure inside the foam concrete and promote a uniform distribution and size of the pore structure inside the test piece. This could effectively improve the compressive strength, flexural strength, and crack resistance of the foam concrete, and when the fiber content was 0.2 wt%, the foam concrete exhibited the best mechanical properties, with a compressive strength of 11.19 MPa and a flexural strength of 3.58 MPa. The present work was in agreement with the strategic objective of resource recycling and solid waste utilization, which was conducive to the development of the circular and green economy.

16.
Thorac Cancer ; 13(20): 2879-2889, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36058556

RESUMO

BACKGROUND: Accurate localization of pulmonary nodules is the main difficulty experienced in wedge resection. Commonly used localization methods have their own advantages and disadvantages. However, clinical work has demonstrated that intraoperative indocyanine green localization under electromagnetic navigation bronchoscopy/virtual navigation bronchoscopy (VNB) is more advantageous than conventional methods for patients with multiple pulmonary nodules undergoing simultaneous surgery, especially for those undergoing bilateral lung surgery. METHODS: Data of patients undergoing simultaneous surgery for multiple pulmonary nodules with preoperative methylene blue localization by computed tomography (CT)-guided percutaneous lung puncture (methylene blue group) or intraoperative indocyanine green localization under VNB (virtual navigation group) were retrospectively analyzed. Patient characteristics, pulmonary nodule features, localization time, preoperative location time, location success rate, operation time, complication incidence, visceral pleural staining rate after localization, and pulmonary nodule primary resection success rate were compared between the two groups. RESULTS: The methylene blue and virtual navigation groups comprised 39 and 20 patients with 119 and 67 pulmonary nodules resected, respectively. Sex, age, number of pulmonary nodules resected simultaneously, unilateral/bilateral lung surgery, pulmonary nodule size, distance between pulmonary nodules and the visceral pleura, pulmonary nodule consolidation-to-tumor ratio, location of pulmonary nodules in the pulmonary lobe, postoperative pathology, visceral pleura staining rate, primary pulmonary nodule resection success rate, and surgical duration did not differ significantly between the groups (p > 0.05). The localization time of the virtual navigation group was significantly shorter than that of the methylene blue group (p < 0.05), regardless of unilateral or bilateral multiple nodules. In the methylene blue group, 25.64% (10/39) of patients presented complications, all of which were pneumothorax, whereas no complications were found in the virtual navigation group. CONCLUSIONS: For patients with multiple pulmonary nodules undergoing simultaneous surgery, indocyanine green injection under VNB can achieve a similar effect on pulmonary nodule localization as classical methylene blue injection under CT-guided percutaneous lung puncture, with shorter localization time and fewer complications.


Assuntos
Neoplasias Pulmonares , Nódulos Pulmonares Múltiplos , Nódulo Pulmonar Solitário , Broncoscopia/métodos , Humanos , Verde de Indocianina , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/cirurgia , Azul de Metileno , Nódulos Pulmonares Múltiplos/diagnóstico por imagem , Nódulos Pulmonares Múltiplos/patologia , Nódulos Pulmonares Múltiplos/cirurgia , Estudos Retrospectivos , Nódulo Pulmonar Solitário/diagnóstico por imagem , Nódulo Pulmonar Solitário/patologia , Nódulo Pulmonar Solitário/cirurgia , Cirurgia Torácica Vídeoassistida/métodos
17.
Materials (Basel) ; 15(1)2021 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-35009444

RESUMO

Graphene-based composite aerogel (GCA) refers to a solid porous substance formed by graphene or its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), with inorganic materials and polymers. Because GCA has super-high adsorption, separation, electrical properties, and sensitivity, it has great potential for application in super-strong adsorption and separation materials, long-life fast-charging batteries, and flexible sensing materials. GCA has become a research hotspot, and many research papers and achievements have emerged in recent years. Therefore, the fabrication, structure, performance, and application prospects of GCA are summarized and discussed in this review. Meanwhile, the existing problems and development trends of GCA are also introduced so that more will know about it and be interested in researching it.

18.
Nanomaterials (Basel) ; 8(12)2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30469503

RESUMO

This study focused on the uniform distribution of graphene oxide (GO) nanosheets in cement composites and their effect on microstructure and performance. For this, three polymer dispersants with different level of polar groups (weak, mild, and strong) poly(acrylamide-methacrylic acid) (PAM), poly(acrylonitrile-hydroxyethyl acrylate) (PAH), and poly(allylamine-acrylamide) (PAA) were used to form intercalation composites with GO nanosheets. The results indicated that GO nanosheets can exist as individual 1⁻2, 2⁻5, and 3⁻8 layers in GO/PAA, GO/PAH, and GO/PAM intercalation composites, respectively. The few-layered (1⁻2 layers) GO can be uniformly distributed in cement composites and promote the formation of regular-shaped crystals and a compact microstructure. The compressive strengths of the blank, control, GO/PAM, GO/PAH, and GO/PAA cement composites were 55.72, 78.31, 89.75, 116.82, and 128.32 MPa, respectively. Their increase ratios relative to the blank sample were 40.54%, 61.07%, 109.66%, and 130.29%, respectively. Their corresponding flexural strengths were 7.53, 10.85, 12.35, 15.97, and 17.68 MPa, respectively, which correspond to improvements of 44.09%, 64.01%, 112.09%, and 134.79%.

19.
Nanomaterials (Basel) ; 7(12)2017 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-29258271

RESUMO

Original graphene oxide (GO) nanosheets were prepared using the Hummers method and found to easily aggregate in aqueous and cement composites. Using carboxymethyl chitosan (CCS) as a dispersant, few-layered GO nanosheets (1-2 layers) were obtained by forming CCS/GO intercalation composites. The testing results indicated that the few-layered GO nanosheets could uniformly spread, both in aqueous and cement composites. The cement composites were prepared with GO dosages of 0.03%, 0.05% and 0.07% and we found that they had a compact microstructure in the whole volume. A special feature was determined, namely that the microstructures consisted of regular-shaped crystals created by self-crosslinking. The X-ray diffraction (XRD) results indicated that there was a higher number of cement hydration crystals in GO/cement composites. Meanwhile, we also found that partially-amorphous Calcium-Silicate-Hydrate (C-S-H) gel turned into monoclinic crystals. At 28 days, the GO/cement composites reached the maximum compressive and flexural strengths at a 0.05% dosage. These strengths were 176.64 and 31.67 MPa and, compared with control samples, their increased ratios were 64.87% and 149.73%, respectively. Durability parameters, such as penetration, freeze-thaw, carbonation, drying-shrinkage value and pore structure, showed marked improvement. The results indicated that it is possible to obtain cement composites with a compact microstructure and with high performances by introducing CCS/GO intercalation composites.

20.
Materials (Basel) ; 10(1)2017 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-28772419

RESUMO

Graphene oxide nanosheets (GONs)/carboxymethyl chitosan (CMC)/Fe3O4 magnetic composite microspheres (MCMs) were prepared by enclosing Fe3O4 particles with CMC and GONs in turn. The microstructures of GONs and GONs/CMC/Fe3O4 MCMs were characterized by FTIR, XRD, TEM, and SEM. The effects of GON content, pH value, and adsorption time on the adsorption capacity of the MCMs were investigated. The results show that the GONs/CMC/Fe3O4 MCMs have a greater specific surface area and a strong adsorption capacity for dye wastewater. Meanwhile, the adsorption mechanism was investigated, and the results accorded with the pseudo-second-order kinetic model and the Freundlich isotherm model. The search results indicate that GONs/CMC/Fe3O4 MCMs can be used to purify dye wastewater and has an important potential use in the practical purification of dye wastewater.

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