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1.
ACS Nano ; 2024 Aug 26.
Article in English | MEDLINE | ID: mdl-39186676

ABSTRACT

Photodetectors are in huge demand in multiple fields, such as remote sensing, chemical detection, security, and medical imaging. Carbon nanotubes (CNTs) are promising candidates for high-performance photodetectors due to their extraordinary optical and electrical properties. However, the performance of previously reported CNT-based photodetectors is far from the intrinsic photoelectrical properties of CNTs because of the noncontinuous lengths, structural defects, and unsatisfactory structural design of the previously used short CNTs. The key to improving the performance of CNT-based photodetectors is to increase the length and structural quality of the CNTs. Herein, high-performance photodetectors were fabricated by using high-density suspended ultralong CNTs (SUCNTs). The suspended structures of ultralong CNTs not only reduced the electron-phonon interactions generated by substrates but also largely avoided bolometric effects through efficient heat dissipation. Moreover, the characteristics of high areal density and defect-free structures of SUCNTs could increase the effective absorption areas and improve their carrier mobility, resulting in enhanced photoconductive responses. Consequently, compared with the nonsuspended short CNTs, the SUCNT-based photodetectors achieved significantly improved photodetection performance, such as high responsivity (0.181 A W-1), detectivity (1.20 × 109 cm Hz1/2 W-1), ultrafast response (0.13 ms), and broad detection range (405-850 nm).

2.
J Acoust Soc Am ; 156(2): 1048-1057, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39136634

ABSTRACT

Broadband adjustable sound absorbers are desired for controlling the acoustic conditions within enclosed spaces. Existing studies on acoustic absorbers, either passive or active, aim to maximize the sound absorption coefficients over an extended frequency band. By contrast, this paper introduces a tunable acoustic absorber, whose working frequency band and sound absorption characteristics can be defined by users for different applications. The approach leverages an error signal that can be synthesized using a standing wave separation technique. The error signal encodes different target reflection coefficients, leading to arbitrary absorption coefficients between 0 and 1. Experimental validation is conducted in a one-dimensional standing wave tube, demonstrating that the proposed active absorber achieves near-perfect absorption within the 150-1600 Hz frequency range, boasting an average absorption coefficient of 0.98. Adjustable absorption is demonstrated across three octave bands, aligning closely with theoretical predictions. Furthermore, when coupled with a shaping filter, the absorber exhibits spectrally tunable broadband absorption capabilities, selectively reflecting specific frequency bands while effectively absorbing others. These outcomes underscore the versatile tunability of the proposed active acoustic absorber, which is expected to pave the way for personalized regulating of the indoor acoustic environment.

3.
Angew Chem Int Ed Engl ; : e202413369, 2024 Aug 20.
Article in English | MEDLINE | ID: mdl-39162070

ABSTRACT

The rational design of carbon-supported transition metal single-atom catalysts necessitates precise atomic positioning within the precursor. However, structural collapse during pyrolysis can occlude single atoms, posing significant challenges in controlling both their utilization and coordination environment. Herein, we present a surface atom adsorption-flash heating (FH) strategy, which ensures that the pre-designed carbon nanofiber structure remains intact during heating, preventing unforeseen collapse effects and enabling the formation of metal atoms in nano-environments with either tetra-nitrogen or penta-nitrogen coordination at different flash heating temperatures. Theoretical calculations and in situ Raman spectroscopy reveal that penta-nitrogen coordinated cobalt atoms (Co-N5) promote a lower energy pathway for oxygen reduction and oxygen evolution reactions compared to the commonly formed Co-N4 sites. This strategy ensures that Co-N5 sites are fully exposed on the surface, achieving exceptionally high atomic utilization. The turnover frequency (65.33 s-1) is 47.4 times higher than that of 20% Pt/C under alkaline conditions. The porous, flexible carbon nanofibers significantly enhance zinc-air battery performance, with a high peak power density (273.8 mW cm-2), large specific capacity (784.2 mA h g-1), and long-term cycling stability over 600 h. Additionally, the flexible fiber-shaped zinc-air battery can power wearable devices, demonstrating significant potential in flexible electronics applications.

4.
Int J Biol Macromol ; 277(Pt 2): 134280, 2024 Oct.
Article in English | MEDLINE | ID: mdl-39084421

ABSTRACT

Spiders spin high performance silks with diverse mechanical properties for specific biological functions. Of these spider silk types, pyriform silk stands out as a unique combination of wet glue and dry fibers. Investigation of self-assembly process of spider silk proteins is necessary for elucidating the silk formation mechanism. However, the functions of nonrepetitive domains in the silk formation of pyriform spidroins from liquid proteins to solid fibers are still unclear, making it difficult to achieve efficient biomimetic preparations of pyriform silk with good mechanical properties. In this study, we investigate the roles of the N-linker repeat (NLR) and both terminal domains of pyriform spidroin 1 (PySp1) in the silk formation. We demonstrate for the first time that the PySp1 NLR alone is sufficient to self-assemble into high strength fibers. Moreover, we showed that the ability to promote the pyriform silk formation by the addition of the NLR. We also found that the pH-sensitive dimerization property for N-terminal domain and the liquid-liquid phase separation (LLPS) coupled with acidification triggers the self-assembly mediated by the C-terminal domain. Overall, our results provide new insight into the role of nonrepetitive domains in the pyriform silk formation mechanism and the basis for producing new protein-based materials derived from spider pyriform silk.


Subject(s)
Fibroins , Silk , Spiders , Fibroins/chemistry , Animals , Silk/chemistry , Protein Domains , Hydrogen-Ion Concentration , Protein Multimerization , Phase Separation
5.
Int J Biol Macromol ; 274(Pt 2): 133464, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38945331

ABSTRACT

Diabetic skin wound healing is compromised by bacterial infections, oxidative stress, and vascular disruption, leading to delayed recovery and potential complications. This study developed an antibacterial, antioxidant, and adhesive hydrogel dressing that promotes rapid bacterial-infected diabetic wound healing using the biological macromolecule of polydopamine (PDA). This hydrogel comprised PDA-armored zeolitic imidazolate framework-8 nanoparticles (PDA@ZIF-8 NPs) combined with a second armor of zwitterionic polymer network (poly(acrylamide-co-sulfobetaine methacrylate); PAS), realizing low concentration Zn2+ release, good adhesion (14.7 kPa for porcine skin), and improved tensile strength (83.2 kPa). The hydrogel exhibited good antibacterial efficacy against both Staphylococcus aureus (S. aureus, 92.8 %), Escherichia coli (E. coli, 99.6 %) and methicillin-resistant S. aureus (MRSA, 99.2 %), which was attributed to the properties of the incorporated PDA@ZIF-8 NPs. Notably, in vitro, the PDA@ZIF-8 PAS hydrogel not only promoted fibroblast proliferation and migration but also facilitated endothelial cell angiogenesis. In vivo, the PDA@ZIF-8 PAS hydrogel retained its Zn2+-releasing function and effectively suppressed bacterial growth in infected wounds, thereby accelerating the regeneration of both normal and diabetic wounds. This multiarmored hydrogel is a promising sustained-release carrier for functional metal ions and drugs, making it applicable for not only skin healing, but potentially the regeneration of other complex tissues.


Subject(s)
Anti-Bacterial Agents , Hydrogels , Indoles , Metal-Organic Frameworks , Polymers , Wound Healing , Indoles/chemistry , Indoles/pharmacology , Wound Healing/drug effects , Animals , Polymers/chemistry , Polymers/pharmacology , Hydrogels/chemistry , Hydrogels/pharmacology , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Metal-Organic Frameworks/chemistry , Metal-Organic Frameworks/pharmacology , Staphylococcus aureus/drug effects , Escherichia coli/drug effects , Mice , Zeolites/chemistry , Zeolites/pharmacology , Methicillin-Resistant Staphylococcus aureus/drug effects , Zinc/chemistry , Zinc/pharmacology , Humans , Swine , Nanoparticles/chemistry , Fibroblasts/drug effects , Cell Proliferation/drug effects
6.
Curr Microbiol ; 81(7): 216, 2024 Jun 08.
Article in English | MEDLINE | ID: mdl-38850425

ABSTRACT

Haloferax and Halobellus are the representatives of the family Haloferacaceae and they are dominant in hypersaline ecosystems. Some Haloferax and Halobellus species exhibit a close evolutionary relationship. Genomic, phylogenetic (based on 16S rRNA gene sequence), and phylogenomic analysis were performed to evaluate the taxonomic positions of the genera Haloferax and Halobellus. Based on the results we propose to reclassify Halobellus ramosii as a later heterotypic synonym of Halobellus inordinatus; Haloferax lucentense and Haloferax alexandrinum as later heterotypic synonyms of Haloferax volcanii.


Subject(s)
Phylogeny , RNA, Ribosomal, 16S , RNA, Ribosomal, 16S/genetics , Haloferax/genetics , Haloferax/classification , Sequence Analysis, DNA , DNA, Archaeal/genetics , DNA, Archaeal/chemistry
7.
Curr Microbiol ; 81(7): 186, 2024 May 22.
Article in English | MEDLINE | ID: mdl-38775831

ABSTRACT

The Exiguobacterium genus comprises Gram-stain-positive and facultatively anaerobic bacteria. Some Exiguobacterium species have previously shown significant high 16S rRNA gene sequence similarities with each other. This study evaluates the taxonomic classification of those Exiguobacterium species through comprehensive genome analysis. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were determined for various Exiguobacterium species pairs. The ANI and dDDH values between Exiguobacterium enclense and Exiguobacterium indicum, Exiguobacterium aquaticum and Exiguobacterium mexicanum, Exiguobacterium soli and Exiguobacterium antarcticum, and Exiguobacterium sibiricum and Exiguobacterium artemiae were above the cut-off level (95-96% for ANI and 70% for dDDH) for species delineation. Based on the findings, we propose to reclassify Exiguobacterium enclense as a later heterotypic synonym of Exiguobacterium indicum, Exiguobacterium aquaticum as a later heterotypic synonym of Exiguobacterium mexicanum, Exiguobacterium soli as a later heterotypic synonym of Exiguobacterium antarcticum and Exiguobacterium sibiricum as a later heterotypic synonym of Exiguobacterium artemiae.


Subject(s)
DNA, Bacterial , Exiguobacterium , Genome, Bacterial , Phylogeny , RNA, Ribosomal, 16S , RNA, Ribosomal, 16S/genetics , DNA, Bacterial/genetics , Exiguobacterium/genetics , Exiguobacterium/classification , Sequence Analysis, DNA , Nucleic Acid Hybridization , Bacterial Typing Techniques
8.
Microorganisms ; 12(5)2024 May 08.
Article in English | MEDLINE | ID: mdl-38792780

ABSTRACT

The degradation of farmland in China underscores the need for developing and utilizing saline-alkali soil. Soil health relies on microbial activity, which aids in the restoration of the land's ecosystem, and hence it is important to understand microbial diversity. In the present study, two Gram-stain-positive strains HR 1-10T and J-A-003T were isolated from saline-alkali soil. Preliminary analysis suggested that these strains could be a novel species. Therefore, the taxonomic positions of these strains were evaluated using polyphasic analysis. Phylogenetic and 16S rRNA gene sequence analysis indicated that these strains should be assigned to the genus Halalkalibacter. Cell wall contained meso-2,6-diaminopimelic acid. The polar lipids present in both strains were diphosphatidyl-glycerol, phosphatidylglycerol, and an unidentified phospholipid. The major fatty acids (>10%) were anteiso-C15:0, C16:0 and iso-C15:0. Average nucleotide identity and digital DNA#x2013;DNA hybridization values were below the threshold values (95% and 70%, respectively) for species delineation. Based on the above results, the strains represent two novel species of the genus Halalkalibacter, for which the names Halalkalibacter flavus sp. nov., and Halalkalibacter lacteus sp. nov., are proposed. The type strains are HR 1-10T (=GDMCC 1.2946T = MCCC 1K08312T = JCM 36285T), and J-A-003T (=GDMCC 1.2949T = MCCC 1K08417T = JCM 36286T).

9.
Nano Lett ; 24(18): 5498-5505, 2024 May 08.
Article in English | MEDLINE | ID: mdl-38619556

ABSTRACT

Revealing low-dimensional material growth dynamics is critical for crystal growth engineering. However, in a practical high-temperature growth system, the crystal growth process is a black box because of the lack of heat-resistant imaging tools. Here, we develop a heat-resistant optical microscope and embed it in a chemical vapor deposition (CVD) system to investigate two-dimensional (2D) crystal growth dynamics. This in situ optical imaging CVD system can tolerate temperatures of ≤900 °C with a spatial resolution of ∼1 µm. The growth of monolayer MoS2 crystals was studied as a model for 2D crystal growth. The nucleation and growth process have been imaged. Model analysis and simulation have revealed the growth rate, diffusion coefficient, and spatial distribution of the precursor. More importantly, a new vertex-kink-ledge model has been suggested for monolayer crystal growth. This work provides a new technique for in situ microscopic imaging at high temperatures and fundamental insight into 2D crystal growth.

10.
Article in English | MEDLINE | ID: mdl-38597816

ABSTRACT

Airflow sensors are in huge demand in many fields such as the aerospace industry, weather forecasting, environmental monitoring, chemical and biological engineering, health monitoring, wearable smart devices, etc. However, traditional airflow sensors can hardly meet the requirements of these applications in the aspects of sensitivity, response speed, detection threshold, detection range, and power consumption. Herein, this work reports high-performance airflow sensors based on suspended ultralong carbon nanotube (CNT) crossed networks (SCNT-CNs). The unique topologies of SCNT-CNs with abundant X junctions can fully exhibit the extraordinary intrinsic properties of ultralong CNTs and significantly improve the sensing performance and robustness of SCNT-CNs-based airflow sensors, which simultaneously achieved high sensitivity, fast response speed, low detection threshold, and wide detection range. Moreover, the capability for encapsulation also guaranteed the practicality of SCNT-CNs, enabling their applications in respiratory monitoring, flow rate display and transient response analysis. Simulations were used to unveil the sensing mechanisms of SCNT-CNs, showing that the piezoresistive responses were mainly attributed to the variation of junction resistances. This work shows that SCNT-CNs have many superiorities in the fabrication of advanced airflow sensors as well as other related applications.

11.
BMC Surg ; 24(1): 38, 2024 Jan 28.
Article in English | MEDLINE | ID: mdl-38281928

ABSTRACT

BACKGROUND: The purpose of this study was to create a mathematical model to precalculate the acreage change in the abdominal median sagittal plane (ac-AMSP) of patients with ankylosing spondylitis (AS) for whom two-level pedicle subtraction osteotomy (PSO) was planned. METHODS: A single-centre retrospective review of prospectively collected data was conducted among 11 adults with AS. Acreage of the abdominal median sagittal plane (a-AMSP) was performed. The distances and angles between the osteotomy apexes, anterosuperior edge of T12, xiphoid process, superior edge of the pubis, and anterosuperior corner of the sacrum were measured on preoperative thoracolumbar computed tomography. A mathematical model was created using basic trigonometric functions in accordance with the abdominal parameters. Planned osteotomized vertebra angles (POVAs) were substituted into the mathematical model, and the predictive ac-AMSP (P-AC) was obtained. A paired sample t test was performed to determine the differences between the P-AC and actual ac-AMSP (A-AC) and between the predictive acreage change rate (P-CR) and actual acreage change rate (A-CR). RESULTS: The mean age and GK were 44.4 ± 8.99 years and 102.9° ± 19.17°, respectively. No significant difference exists between A-CR and P-CR via mathematical modeling (p > 0.05). No statistically significant difference existed between POVA and actual osteotomized vertebra angles (AOVA) (p > 0.05). A statistically significant difference was observed between preoperative and postoperative measurements of LL, SVA, and GK variables (p < 0.001). CONCLUSIONS: The novel mathematical model was reliable in predicting the ac-AMSP in AS patients undergoing two-level PSO.


Subject(s)
Kyphosis , Spondylitis, Ankylosing , Adult , Humans , Spondylitis, Ankylosing/diagnostic imaging , Spondylitis, Ankylosing/surgery , Kyphosis/diagnostic imaging , Kyphosis/etiology , Kyphosis/surgery , Osteotomy/methods , Retrospective Studies , Sacrum , Lumbar Vertebrae/surgery , Treatment Outcome , Thoracic Vertebrae/diagnostic imaging , Thoracic Vertebrae/surgery
12.
Phys Rev Lett ; 131(23): 234001, 2023 Dec 08.
Article in English | MEDLINE | ID: mdl-38134795

ABSTRACT

Diffraction sets a natural limit for the spatial resolution of acoustic wave fields, hindering the generation and recording of object details and manipulation of sound at subwavelength scales. We propose to overcome this physical limit by utilizing nonlinear acoustics. Our findings indicate that, contrary to the commonly utilized cumulative nonlinear effect, it is in fact the local nonlinear effect that is crucial in achieving subdiffraction control of acoustic waves. We theoretically and experimentally demonstrate a deep subwavelength spatial resolution up to λ/38 in the far field at a distance 4.4 times the Rayleigh distance. This Letter represents a new avenue towards deep subdiffraction control of sound, and may have far-reaching impacts on various applications such as acoustic holograms, imaging, communication, and sound zone control.

13.
ACS Biomater Sci Eng ; 9(12): 6670-6682, 2023 Dec 11.
Article in English | MEDLINE | ID: mdl-38019679

ABSTRACT

Orb-weaving spiders can use an array of specialized silks with diverse mechanical properties and functions for daily survival. Of all spider silk types, aciniform silk is the toughest silk fiber that combines high strength and elasticity. Although aciniform spidroins (AcSp) are the main protein in aciniform silks, their complete genes have rarely been characterized until now. Moreover, the structural and physical properties of AcSp variant proteins within the species are also unclear. Here, we present three full-length AcSp genes (named AcSp1A, AcSp1B, and AcSp2) from the orb-weaving spider Neoscona theisi and investigate the structural and mechanical features of these three AcSp repetitive domains. We demonstrate that all three AcSp proteins have mainly α-helical structural features in neutral solution and high thermal stability. Significantly, the AcSp2 repetitive domain shows a pH-dependent structural transition from α to ß conformations and can self-assemble into amyloid fibrils under acidic conditions, which is the first reported AcSp repetitive domain with pH-dependent self-assembly capacity. Compared with the other two AcSp spidroins, AcSp2 demonstrated the lowest expression level in the aciniform gland but had the highest strength for its silk fiber. Collectively, our findings provide new insight into the physical properties of each component of aciniform silk and expand the repertoire of known spidroin sequences for the synthesis of artificial silk materials.


Subject(s)
Fibroins , Silk/chemistry , Silk/genetics , Elasticity , Hydrogen-Ion Concentration
14.
RSC Adv ; 13(49): 34464-34474, 2023 Nov 22.
Article in English | MEDLINE | ID: mdl-38024984

ABSTRACT

Alloying can effectively modify electronic and optical properties of two-dimensional (2D) transition metal dichalcogenides (TMDs). However, efficient and simple methods to synthesize atomically thin TMD alloys need to be further developed. In this study, we synthesized 25 monolayer MoxW(1-x)S2ySe2(1-y) alloys by using a new liquid phase edge epitaxy (LPEE) growth method with high controllability. This straightforward approach can be used to obtain monolayer materials and operates on a self-limiting growth mechanism. The process allows the liquid solution to come into contact with the two-dimensional grains only at their edges, resulting in epitaxy confined only along the in-plane direction, which produces exclusively monolayer epitaxy. By controlling the weight ratio of MoS2/WSe2 (MoSe2/WS2), 25 monolayer MoxW(1-x)S2ySe2(1-y) alloys with different atomic ratios can be obtained on sapphire substrates, with band gap ranging from WS2 (1.55 eV) to MoSe2 (1.99 eV) and a continuously broad spectrum ranging from 623 nm to 800 nm. By adjusting the alloy composition, the carrier type and carrier mobility of alloy-based field-effect transistors can be modulated. In particular, the adjustable conductivity of MoxW(1-x)S2ySe2(1-y) alloys from n-type to bipolar type is achieved for the first time. This general synthetic strategy provides a foundation for the development of monolayer TMD alloys with multiple components and various 2D materials.

15.
Huan Jing Ke Xue ; 44(10): 5587-5598, 2023 Oct 08.
Article in Chinese | MEDLINE | ID: mdl-37827775

ABSTRACT

Herein, a CuNiFe LDHs/BiO2-x composite photocatalyst was successfully synthesized using a hydrothermal method and applied to activate peroxymonosulfate to degrade ciprofloxacin under visible light irradiation. Owing to the synergistic effect of photocatalysis and PMS activation, a high removal efficiency of CIP up to 88.3% was achieved. The prepared photocatalysts were characterized using XRD, FT-IR, SEM, XPS, UV-Vis DRS, and other methods. The optimal loading amount of CuNiFe LDHs was determined, and the effects of PMS dosage, initial pH value, and inorganic anions (Cl-, CO32-, and NO3-) on the degradation were investigated. Electron paramagnetic resonance and free radical trapping experiments demonstrated that·OH and h+ were the main active species for degrading CIP, and the possible degradation mechanism of the system was proposed.

16.
J Coll Physicians Surg Pak ; 33(10): 1188-1193, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37804028

ABSTRACT

OBJECTIVE: To analyse the clinical characteristics of thoracolumbar fractures combined with posterior column injury, and explore its intraoperative reduction technique with clinical efficacy. STUDY DESIGN: Descriptive study.                                   Place and Duration of the Study: Department of Orthopaedics, Fuyang People's Hospital, Anhui, China, from December 2017 to 2021. METHODOLOGY: A total of 60 patients met the inclusion criteria, they were divided into two categories according to injury mechanism and imaging characteristics: flexion-distraction injury (FDI) and burst fracture with lamina fracture (BFLF), and their clinical characteristics were analysed. All patients were treated with posterior pedicle screw internal fixation, and different intraoperative reduction methods were adopted for reduction. Measurements of anterior vertebral heights (AVH), local kyphotic angles (LKA), visual analog scale (VAS) and oswestry disability index (ODI) were evaluated preoperative, after operation, and the last follow-up. RESULTS: The two groups of thoracolumbar fractures combined with posterior column injury had different clinical characteristics, and there were significant differences in preoperative imaging related parameters (p<0.05). All patients in the two groups successfully completed the operation, and there were no direct complications related to the operation. The patients were followed up for 12-24 months. Compared with those before the operation, the AVH, LKA, VAS, and ODI immediately after the operation and at the last follow-up were significantly improved (p<0.05). Bone fusion was achieved in all patients. CONCLUSION: Careful and comprehensive preoperative clinical data analysis is the key to diagnosis of thoracolumbar fractures combined with posterior column injury. According to the type of fracture, reasonable selection of intraoperative reduction technique can obtain satisfactory clinical results. KEY WORDS: Burst fracture, Pedicle screw, Internal fixation, Thoracic, Lumbar.


Subject(s)
Fractures, Bone , Pedicle Screws , Spinal Fractures , Humans , Spinal Fractures/diagnostic imaging , Spinal Fractures/surgery , Thoracic Vertebrae/diagnostic imaging , Thoracic Vertebrae/surgery , Lumbar Vertebrae/diagnostic imaging , Lumbar Vertebrae/surgery , Lumbar Vertebrae/injuries , Fracture Fixation, Internal/methods , Treatment Outcome , Retrospective Studies
17.
Langmuir ; 39(34): 12216-12225, 2023 Aug 29.
Article in English | MEDLINE | ID: mdl-37581507

ABSTRACT

To unveil the intricacies surrounding the interaction between microplastics (MPs) and pollutants, diligent investigation is warranted to mitigate the environmental perils they pose. This exposition delves into the sorption behavior and mechanism of diclofenac sodium (DCF), a contaminant, upon two distinct materials: polystyrene (PS) and poly(butylene adipate-co-terephthalate) (PBAT). Experimental adsorption endeavors solidify the observation that the adsorption capacity of DCF onto the designated MPs amounts to Q(PBAT) = 9.26 mg g-1 and Q(PS) = 9.03 mg g-1, respectively. An exploration of the factors governing these discrepant adsorption phenomena elucidates the influence of MPs and DCF properties, environmental factors, as well as surfactants. Fitting procedures underscore the suitability of the pseudo-second-order kinetic and Freundlich models in capturing the intricacies of the DCF adsorption process onto MPs, corroborating the notion that the mentioned process is characterized by non-homogeneous chemisorption. Moreover, this inquiry unveils that the primary adsorption mechanisms of DCF upon MPs encompass electrostatic interaction, hydrogen bonding, and halo hydrogen bonding. An additional investigation concerns the impact of commonly encountered surfactants in aqueous environments on the adsorption of DCF onto MPs. The presence of surfactants elicits modifications in the surface charge properties of MPs, consequently influencing their adsorption efficacy vis-à-vis DCF.

18.
Chemosphere ; 340: 139806, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37574090

ABSTRACT

Microplastics (MPs) and dye pollutants are widespread in aquatic environments. Here, the adsorption characteristics of anionic dye methyl orange (MO) and cationic dye malachite green (MG) on polyamide 6 (PA6) and polyamide 66 (PA66) MPs were investigated, including kinetics, isotherm equilibrium and thermodynamics. The co-adsorption of MO and MG under different pH was also evaluated. The results reveal that the adsorption process of MO and MG is suitably expounded by a pseudo-second-order kinetic model. The process can be characterized by two stages: internal diffusion and external diffusion. The isothermal adsorption equilibrium of MO and MG can be effectively described using the Langmuir model, signifying monolayer adsorption. Furthermore, the thermodynamic results indicated that the adsorption was spontaneous with exothermic and endothermic properties, respectively. The results of binary systems reveal that MO dominates the adsorption at low pH (2-5), while MG dominates at high pH (8-10). Strong competitive adsorption was observed between MO and MG in neutral conditions (pH 6-8). The desorption experiments confirm that PA6 and PA66 could serve as potential carriers of MO and MG. The interaction between dyes and polyamide MPs is primarily mediated through hydrogen bonds and electrostatic attraction. The results reveal that PA6 formed more hydrogen bonds with the dyes, resulting in higher adsorption capacity than that of PA66. This difference can be attributed to the disparities in the synthesis process and polymerization method. Our study uncovered the adsorption mechanism of dye pollutants on PA6 and PA66, and provided a more comprehensive theoretical basis for the risk assessment concerning different types of polyamide MPs in aquatic environments.


Subject(s)
Microplastics , Water Pollutants, Chemical , Nylons , Plastics , Adsorption , Hydrogen Bonding , Hydrogen-Ion Concentration , Thermodynamics , Coloring Agents/chemistry , Kinetics , Water Pollutants, Chemical/chemistry
19.
Waste Manag ; 171: 32-42, 2023 Aug 27.
Article in English | MEDLINE | ID: mdl-37643482

ABSTRACT

Although there have been many research results on the chemical activation of fly ash (FA) as a supplementary cementitious material (SCM) in cementitious materials. However, there is a lack of research on the use of CO2 foaming agent (sodium bicarbonate and potassium aluminum sulfate) to activate fly ash. In this experiment, the effects of CO2 foaming agent, sodium bicarbonate, and potassium aluminum sulfate on the activity of FA mixed paste were investigated. The mechanism of FA activation by activator was revealed by selective acid dissolution, QXRD, BSE-EDS statistical analysis, and quantitative analysis of TGA. The results showed that the remaining fly ash amounts of MG, SBG, and PASG after 28 days were 17.5%, 25.9%, and 43.3% lower than those of the control group, respectively. In addition, potassium aluminium sulphate promoted hydration to generate more CH to activate the FA. Sodium bicarbonate promoted hydration and produces more CH to activate FA by generating nano-CaCO3. The mixture of sodium bicarbonate and potassium aluminum sulfate took advantage of both nano-CaCO3 and potassium aluminum sulfate to promote silicate hydration to provide CH. As a result, the two synergistically activate FA. The above results show that CO2 foaming agents can be used not only as foaming agents to prepare lightweight materials, but also as chemical activators to activate solid waste. This will have a high practical application value.

20.
Ecotoxicol Environ Saf ; 264: 115400, 2023 Oct 01.
Article in English | MEDLINE | ID: mdl-37651796

ABSTRACT

Microplastics (MPs) can enrich pollutants after being released into the environment, and the contaminants-loaded MPs are usually ingested by organisms, resulting in a potential dual biotoxic effect. In this paper, the adsorption behavior of Sulfamethoxazole (SMX) on Polyamide 6 (PA6) MPs was systematically investigated and simulated by the kinetic and isotherm models. The effect of environmental conditions (pH, salinity) on the adsorption process was studied, and the desorption behavior of SMX-loaded PA6 MPs was focused on simulating the seawater, ultrapure water, gastric and intestinal fluids. We found that lower pH and solubilization of SMX by gastrointestinal components (bovine serum albumin (BSA), sodium taurocholate (NaT), and pepsin) can reduce the electrostatic interaction between the surface charge of PA6 MPs and SMX. The result will lead to an increase in the desorption capacity of SMX-loaded PA6 MPs in gastrointestinal fluids and therefore will provide a reasonable mechanism for the desorption of SMX-loaded PA6 MPs in the gastrointestinal fluids. This study will provide a theoretical reference for studying the desorption behavior of SMX-loaded PA6 MPs under gastrointestinal conditions.


Subject(s)
Microplastics , Plastics , Stomach , Sulfamethoxazole
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