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1.
J Neuroinflammation ; 21(1): 138, 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38802927

RESUMO

Sepsis-associated encephalopathy (SAE) is a significant cause of mortality in patients with sepsis. Despite extensive research, its exact cause remains unclear. Our previous research indicated a relationship between non-hepatic hyperammonemia (NHH) and SAE. This study aimed to investigate the relationship between NHH and SAE and the potential mechanisms causing cognitive impairment. In the in vivo experimental results, there were no significant abnormalities in the livers of mice with moderate cecal ligation and perforation (CLP); however, ammonia levels were elevated in the hippocampal tissue and serum. The ELISA study suggest that fecal microbiota transplantation in CLP mice can reduce ammonia levels. Reduction in ammonia levels improved cognitive dysfunction and neurological impairment in CLP mice through behavioral, neuroimaging, and molecular biology studies. Further studies have shown that ammonia enters the brain to regulate the expression of aquaporins-4 (AQP4) in astrocytes, which may be the mechanism underlying brain dysfunction in CLP mice. The results of the in vitro experiments showed that ammonia up-regulated AQP4 expression in astrocytes, resulting in astrocyte damage. The results of this study suggest that ammonia up-regulates astrocyte AQP4 expression through the gut-brain axis, which may be a potential mechanism for the occurrence of SAE.


Assuntos
Aquaporina 4 , Astrócitos , Eixo Encéfalo-Intestino , Hiperamonemia , Encefalopatia Associada a Sepse , Animais , Camundongos , Aquaporina 4/metabolismo , Aquaporina 4/genética , Aquaporina 4/biossíntese , Astrócitos/metabolismo , Hiperamonemia/metabolismo , Encefalopatia Associada a Sepse/metabolismo , Masculino , Eixo Encéfalo-Intestino/fisiologia , Camundongos Endogâmicos C57BL , Amônia/metabolismo , Amônia/sangue , Encéfalo/metabolismo , Transplante de Microbiota Fecal
2.
Phys Rev Lett ; 132(5): 056203, 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38364171

RESUMO

Friction is responsible for about one-third of the primary energy consumption in the world. So far, a thorough atomistic understanding of the frictional energy dissipation mechanisms is still lacking. The Amontons' law states that kinetic friction is independent of the sliding velocity while the Prandtl-Tomlinson model suggests that damping is proportional to the relative sliding velocity between two contacting objects. Through careful analysis of the energy dissipation process in atomic force microscopy measurements, here we propose that damping force is proportional to the tip oscillation speed induced by friction. It is shown that a physically well-founded damping term can better reproduce the multiple peaks in the velocity-dependent friction force observed in both experiments and molecular dynamics simulations. Importantly, the analysis gives a clear physical picture of the dynamics of energy dissipation in different friction phases, which provides insight into long-standing puzzles in sliding friction, such as velocity weakening and spring-stiffness-dependent friction.

3.
Biomacromolecules ; 24(11): 5105-5115, 2023 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-37800273

RESUMO

The reluctance of a polyester with high glass transition temperature (Tg) and mechanical properties to hydrolyze is a well-known fact, for instance, the high hydrolysis resistance of aromatic polyesters based on terephthalic acid and 2,5-furandicarboxylic acid (FDCA). The synthesis of polyesters that have a high Tg (>100 °C) and a fast hydrolytic degradation quality at the same time is a valuable topic. Herein, a renewable rigid diester, N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-methyl carboxylate) (CBPC), was obtained via Michael addition. CBPC was copolymerized with FDCA and ethylene glycol to prepare a series of copolyesters PECxEFy with a high Mn over 30 kDa. PECxEFy showed a Tg range of 75.2-109.2 °C which outdistanced the most biobased polyesters. The thermal stability of all PECxEFy remained unchanged with the introduction of CBPC. Moreover, PECxEFy presented superior mechanical performances which were matching or exceeding those of commercial polyethylene terephthalate (PET) and polylactic acid (PLA). PECxEFy was stable in air but was able to undergo noticeable hydrolytic degradation, proving their enhanced degradability. And the regulation between CBPC and FDCA composition can be leveraged to adjust the degradation and environmental durability of PECxEFy, up to practical applications. Computational studies systematically revealed the relationship between CBPC with a tricyclic structure and the improved Tg and hydrolyzation properties. The outstanding thermal and mechanical performances and hydrolysis of these copolyesters appear to be promising candidates for renewable alternatives to industrial petrochemical polyesters.


Assuntos
Ácidos Dicarboxílicos , Poliésteres , Temperatura de Transição , Hidrólise , Poliésteres/química , Ácidos Dicarboxílicos/química
4.
Macromol Rapid Commun ; 44(19): e2300263, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37435986

RESUMO

Non-isocyanate polyurethanes (NIPUs) are widely studied as sustainability potential, because they can be prepared without using toxic isocyanates in the synthesis process. The aminolysis of cyclic carbonate to form NIPUs is a promising route. In this work, a series of NIPUs is prepared from renewable bis(6-membered cyclic carbonates) (iEbcc) and amines. The resulting NIPUs possess excellent mechanical properties and thermal stability. The NIPUs can be remolded via transcarbamoylation reactions, and iEbcc-TAEA-10 (the molar ratio of tris(2-aminoethyl)amine in amines is 10%) still get a recovery ratio of 90% in tensile stress after three cycles of remolding. In addition, the obtained materials can be chemically degraded into bi(1,3-diol) precursors with high purity (>99%) and yield (>90%) through alcoholysis. Meanwhile, the degraded products can be used to regenerate NIPUs with similar structures and properties as the original samples. The synthetic strategy, isocyanate-free and employing isoeugenol and carbon dioxide (CO2 ) as building blocks, makes this approach an attractive pathway to NIPU networks taking a step toward a circular economy.

5.
Biomacromolecules ; 23(4): 1733-1744, 2022 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-35107271

RESUMO

The lack of selectivity between tumor and healthy cells, along with inefficient reactive oxygen species production in solid tumors, are two major impediments to the development of anticancer Ru complexes. The development of photoinduced combination therapy based on biodegradable polymers that can be light activated in the "therapeutic window" would be beneficial for enhancing the therapeutic efficacy of Ru complexes. Herein, a biodegradable Ru-containing polymer (poly(DCARu)) is developed, in which two different therapeutics (the drug and the Ru complex) are rationally integrated and then conjugated to a diblock copolymer (MPEG-b-PMCC) containing hydrophilic poly(ethylene glycol) and cyano-functionalized polycarbonate with good degradability and biocompatibility. The polymer self-assembles into micelles with high drug loading capacity, which can be efficiently internalized into tumor cells. Red light induces the generation of singlet oxygen and the release of anticancer drug-Ru complex conjugates from poly(DCARu) micelles, hence inhibiting tumor cell growth. Furthermore, the phototherapy of polymer micelles demonstrates remarkable inhibition of tumor growth in vivo. Meanwhile, polymer micelles exhibit good biocompatibility with blood and healthy tissues, which opens up opportunities for multitherapeutic agent delivery and enhanced phototherapy.


Assuntos
Antineoplásicos , Neoplasias , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Portadores de Fármacos , Humanos , Micelas , Neoplasias/tratamento farmacológico , Fototerapia , Cimento de Policarboxilato , Polietilenoglicóis/uso terapêutico , Polímeros
6.
Nano Lett ; 21(11): 4615-4621, 2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34018741

RESUMO

Friction represents a major energy dissipation mode, yet the atomistic mechanism of how friction converts mechanical motion into heat remains elusive. It has been suggested that excess phonons are mainly excited at the washboard frequency, the fundamental frequency at which relative motion excites the interface atoms, and the subsequent thermalization of these nonequilibrium phonons completes the energy dissipation process. Through combined atomic force microscopy measurements and atomistic modeling, here we show that the nonlinear interactions between a sliding tip and the substrate can generate excess phonons at not only the washboard frequency but also its harmonics. These nonequilibrium phonons can induce resonant vibration of the tip and lead to multiple peaks in the friction force as the tip sliding velocity ramps up. These observations disclose previously unrecognized energy dissipation channels associated with tip vibration and provide insights into engineering friction force through adjusting the resonant frequency of the tip-substrate system.

7.
Langmuir ; 36(18): 4964-4974, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32308004

RESUMO

Chitosan is a natural polymer with good biocompatibility, biodegradability, and bioactivity that has great potential for biomedical and industrial applications. Like other natural sugar-based polymers, chitosan molecules own versatile adhesion abilities to bind with various surfaces, owing to multiple functional moieties contained in the chain. To develop the promising biomaterials based on the chitosan chemistry, it is fundamentally important to figure out its adhesion mechanism under a certain condition, which leaves us numbers of open questions. In this work, we characterized the chitosan films adsorbed on a mica substrate in acidic solution and investigated the effects of multivalent salts on the cohesive behaviors of the films by means of the surface forces apparatus. The results showed that the cohesion capacities of chitosan films were reduced to around 30% of their original states after the addition of 10-7 M LaCl3 into 150 mM acetic acid, which could be partially recovered by holding the films at the contact position for a longer time. Surprisingly, the cohesion loss in the films exhibited the dependence on the properties of the metal cations including valance and concentration. The topography of the chitosan-coated surface also showed obvious aggregation in the presence of submicromolar of the salts. Here, we attributed these phenomena regarding cohesion loss to the mechanisms involved in the absorption of metal cations by the chitosan chains, which not only consumed the binding sites but also induced conformation change in the polymer network. Our findings may offer a suggestion for the production of chitosan-based materials to notice the potential impacts of ultralow concentrated salts that are usually neglected even under acidic conditions.

8.
Electrophoresis ; 40(16-17): 2104-2111, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30861157

RESUMO

Silver nanoparticles (AgNPs) are evaporatively self-assembled into the 3D surface enhanced Raman scattering (SERS) hotspot matrix with the assistant of glycerol to improve the spectral reproducibility in direct DNA detection. AgNPs and DNA in the glycerol-stabilized 3D SERS hotspot matrix are found to form flexible sandwich structures through electrostatic interaction where neighboring AgNPs create uniform and homogeneous localized surface plasmon resonance coupling environments for central DNA. Nearly two orders of magnitude extra SERS enhancement, more stable peak frequency and narrower peak full width at half maximum can therefore be obtained in DNA SERS spectra, which ensures highly stable and reproducible SERS signals in direct detection of both single strand DNA and double strand DNA utilizing the 3D SERS hotspot matrix. By normalizing the SERS spectra using phosphate backbone as internal standard, identification of single base variation in oligonucleotides, determination of DNA hybridization events and recognition of chemical modification on bases (hexanethiol-capped at 5' end) have been demonstrated experimentally. This proposed 3D SERS hotspot matrix opens a novel perspective in manipulating plasmonic nanoparticles to construct SERS platforms and would make the surface enhanced Raman spectroscopy a more practical and reliable tool in direct DNA detection.


Assuntos
DNA/análise , Análise Espectral Raman/métodos , Desenho de Equipamento , Nanopartículas Metálicas/química , Prata/química , Propriedades de Superfície
9.
Langmuir ; 35(48): 15795-15804, 2019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31246031

RESUMO

An evaporative self-assembly strategy for constructing a long-life 3D surface-enhanced Raman scattering (SERS) hot spot matrix is proposed with the assistance of glycerol to improve the spectral sensitivity and reproducibility. Different from the traditional wetting-state or drying-state methods, silver nanoparticles (AgNPs) in the glycerol-stabilized 3D SERS hot spot matrix can be maintained in the translation state for more than 7 days with the maximal uniformity of the interparticle distance. Brownian dynamics simulations reveal that more hot spots emerge in the glycerol-stabilized AgNPs matrix, and the distances between the AgNPs are not fixed but balanced in a small range by the interplay of the van der Waals attraction and the electrostatic repulsion. A 2 orders of magnitude extra SERS enhancement, more stable peak frequencies, and a narrower peak full width at half-maximum (fwhm) can therefore be obtained, which ensure extremely stable and reproducible SERS signals. Single-molecule detection sensitivity utilizing the glycerol-stabilized 3D SERS hot spot matrix has been demonstrated by collecting the SERS spectra of dye molecules at a concentration of as low as 0.5 aM (5 × 10-19 M) with a good signal-to-noise ratio. A long lifetime, ultrahigh SERS enhancement, and extremely stable peak shape make the 3D SERS hot spot matrix a sensitive, practical, and reliable tool for the detection and analysis of analytes at ultralow concentration or even at the single-molecule level in complex matrixes.

10.
Biomacromolecules ; 20(10): 3952-3968, 2019 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-31490668

RESUMO

A facile method in combination of "grafting from" and "end-functionalization" was developed for the synthesis of fluorescent highly branched poly(l-lactide)s (PLLA-COU) via ring opening polymerization (ROP) and esterification end-capping. These resulting PLLA-COU with four kinds of architectures, including linear, star, linear-comb, and star-comb structures, were subjected to characterization and application as fluorescent visible paclitaxel-loaded microspheres. The mutual effects of architecture and end-groups on thermal and fluorescence properties, enzymatic degradation, and drug release behaviors were focused. Contrast to linear and star PLLA-COU, two comb-shaped analogues demonstrated higher fluorescence quantum yield, faster drug release, and lower enzymatic degradation rate. All the fluorescent microspheres could maintain fluorescence traceability. The fluorescent PLLA-COU displayed negligible toxicity and good biocompatibility. This work highlights that the fluorescent highly branched poly(l-lactide)s are properties-tailored and used as fluorescent visible drug delivery systems (DDS) for potential theranostic applications.


Assuntos
Corantes Fluorescentes/química , Paclitaxel/química , Poliésteres/química , Animais , Materiais Biocompatíveis/química , Linhagem Celular , Sistemas de Liberação de Medicamentos/métodos , Camundongos , Microesferas , Polimerização
11.
Public Health Nutr ; 21(13): 2409-2416, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29717687

RESUMO

OBJECTIVE: Data on dietary patterns in relation to the risk of metabolic syndrome (MetS) in a middle-aged Chinese population are sparse. The present study was performed to determine the major dietary patterns among a population aged 45-59 years and to evaluate their associations with MetS risk in China. DESIGN: Cross-sectional examination of the association between dietary patterns and MetS. Face-to-face interviews were used to assess dietary intake using a validated semi-quantitative FFQ. OR and 95 % CI for MetS were calculated across quartiles of dietary pattern scores using multivariate logistic regression analysis models. SETTING: City of Linyi, Shandong Province, China. SUBJECTS: Adults (n 1918) aged 45-59 years. RESULTS: Three major dietary patterns were identified: traditional Chinese, animal food and high-energy. After adjustment for potential confounders, individuals in the highest quartile of the traditional Chinese pattern had a reduced risk of MetS relative to the lowest quartile (OR=0·72, 95 % CI 0·596, 0·952; P<0·05). Compared with those in the lowest quartile, individuals in the highest quartile of the animal food pattern had a greater risk of MetS (OR=1·28; 95 % CI 1·103, 1·697; P<0·05). No significant association was observed between the high-energy pattern and risk of MetS. CONCLUSIONS: These findings indicate that the traditional Chinese pattern was associated with a reduced risk, while the animal food pattern was associated with increased risk of MetS. Given the cross-sectional nature of our study, further prospective studies are warranted to confirm these findings.


Assuntos
Povo Asiático/estatística & dados numéricos , Dieta/efeitos adversos , Síndrome Metabólica/etiologia , China/epidemiologia , Estudos Transversais , Dieta/etnologia , Dieta/métodos , Comportamento Alimentar/etnologia , Feminino , Humanos , Modelos Logísticos , Masculino , Síndrome Metabólica/epidemiologia , Síndrome Metabólica/etnologia , Pessoa de Meia-Idade , Fatores de Risco
12.
Nano Lett ; 17(6): 3550-3555, 2017 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-28481541

RESUMO

Nanowires of complex morphologies, such as kinked wires, have been recently synthesized and demonstrated for novel devices and applications. However, the effects of these morphologies on thermal transport have not been well studied. Through systematic experimental measurements, we show that single-crystalline, defect-free kinks in boron carbide nanowires can pose a thermal resistance up to ∼30 times larger than that of a straight wire segment of equivalent length. Analysis suggests that this pronounced resistance can be attributed to the combined effects of backscattering of highly focused phonons and required mode conversion at the kink. Interestingly, it is also found that instead of posing resistance, structural defects in the kink can actually assist phonon transport through the kink and reduce its resistance. Given the common kink-like wire morphology in nanoelectronic devices and required low thermal conductivity for thermoelectric devices, these findings have important implications in precise thermal management of electronic devices and thermoelectrics.

13.
Med Sci Monit ; 23: 470-478, 2017 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-28125566

RESUMO

BACKGROUND We specifically designed this study to determine the relationship between levels of IL-8 and carotid intima-media thickness (cIMT) in patients with type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS A total of 149 diabetic patients at different stages of diabetic nephropathy and 72 matched controls were recruited in this study. A wide range of parameters were measured: IL-18 (by ELISA), urinary albumin excretion rates (UAER), and carotid intima-media thickness (cIMT, by pulse wave velocity [PWV]). All the diabetic patients were treated by alprostadil. RESULTS ELISA indicated that the level of IL-18 in the patient group was significantly higher compared with that in the control group. The level of IL-18 apparently increased in the higher cIMT group in T2DM patients. Serum IL-18 levels were positively correlated with cIMT in patients with T2DM, the level of IL-18 was negatively correlated with cIMT, and IL-18 levels were positively correlated to age. Moreover, IMT was positively correlated with hemoglobin A1C (HbA1C) and IL-18 levels were significantly associated with cIMT (all P<0.05). CONCLUSIONS IL-18 levels were positively correlated with atherosclerotic burden in patients with T2DM and it may be considered as a significant therapeutic target.


Assuntos
Espessura Intima-Media Carotídea , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/patologia , Nefropatias Diabéticas/sangue , Nefropatias Diabéticas/patologia , Interleucina-18/sangue , Idoso , Alprostadil/uso terapêutico , Aterosclerose/sangue , Biomarcadores/sangue , Doenças das Artérias Carótidas/sangue , Estudos de Casos e Controles , Angiopatias Diabéticas/sangue , Angiopatias Diabéticas/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Onda de Pulso , Fatores de Risco
14.
Cell Biol Int ; 39(3): 300-9, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25319137

RESUMO

We have explored the role of Chondromodulin-I (ChM-I) in chondrogenesis of bone marrow-derived mesenchymal stem cells (BMSCs) in 3-dimensional (3D) scaffold for cartilage tissue engineering. BMSCs of Sprague Dawley (SD) rats were cultured on poly-(L-lactic acid) [PLLA] scaffolds with different pore sizes (80-200 µm, 200-450 µm) with or without surface modification by chitosan. Cell viability, proliferation, and morphology were measured using confocal microscope and the CCK-8 method. Untransfected BMSCs, BMSCs expressing pcDNA3.1(+), BMSCs expressing plasmid pcDNA3.1 (+)/ChM-I were cultured on 3D scaffolds in standard growth medium or transforming growth factor-ß1 (TGF-ß1) supplemented chondrogenic induction medium in vitro for 3 weeks and the expression of collagen type II was determined. Cell-scaffolds constructs were implanted subcutaneously for 3 months in vivo. BMSCs had a higher viability and proliferation in PLLA scaffolds of pore size 200-450 µm than that of 80-200 µm, and surface modification with chitosan did not enhance cell attachment. The ChM-I gene enhanced chondrogenesis and increased collagen type II synthesis. Immunohistochemistry from in vivo study showed enhanced cartilage regeneration in BMSCs expressing pcDNA3.1 (+)/ChM-I on 3D PLLA scaffolds. It also demonstrated that TGF-ß1 might promote chondrogenesis of rat BMSCs by synergizing with the ChM-I gene. ChM-I could be beneficial to future applications in cartilage repair.


Assuntos
Células da Medula Óssea/citologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas de Membrana/metabolismo , Células-Tronco Mesenquimais/metabolismo , Polilisina/química , Engenharia Tecidual , Animais , Cartilagem/metabolismo , Cartilagem/fisiologia , Técnicas de Cultura de Células , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células , Células Cultivadas , Condrogênese/efeitos dos fármacos , Colágeno Tipo II/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Proteínas de Membrana/genética , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Ratos , Ratos Sprague-Dawley , Regeneração/efeitos dos fármacos , Alicerces Teciduais , Transfecção , Fator de Crescimento Transformador beta1/farmacologia
15.
Water Sci Technol ; 72(8): 1257-65, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26465294

RESUMO

The collaborative and mutually reinforcing phosphorus removal in domestic wastewater in a sponge iron and microorganisms system was studied through a laboratory and a pilot scale experiment. The results showed that the total phosphorus concentration of the effluent of less than 0.5 mg/L could be achieved. The results also support that the biochemical reaction accelerated the iron electrochemical corrosion. As a driving force, iron bacteria strengthened the chemical oxidation of Fe(II) to Fe(III). The chemical precipitation of Fe(III) is the main form of phosphorus removal. In addition, there exists adsorption phosphorus removal by phosphate-accumulating organisms. The mechanism of the enhanced phosphorus removal by microbial-collaborating sponge iron was thus proposed.


Assuntos
Reatores Biológicos , Ferro/química , Fósforo/isolamento & purificação , Purificação da Água/métodos , Adsorção , Precipitação Química , Corrosão , Compostos Férricos/química , Ferro/metabolismo , Oxirredução , Fosfatos/metabolismo , Fósforo/metabolismo , Projetos Piloto , Águas Residuárias/química
16.
Int J Biol Macromol ; 274(Pt 1): 133365, 2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38914410

RESUMO

PLA is widely known as biodegradable plastics whose further application in fields such as automotive and architectural is still constrained by its flammability and unsatisfactory crystallization properties. To address the aforementioned concerns, a novel biomass phosphonamide PDPA was synthesized with chemical structure confirmed by FTIR, NMR and elemental analysis tests. Immediately thereafter, PLA/PDPA composites were prepared by melting blending, with a focus on flame retardancy, crystallization properties and flame-retardant mechanism. As expected, PDPA efficiently enhanced both the flame retardancy and crystallization properties of PLA. Specifically, the PLA/4.0PDPA obtained UL-94 V-0 grade and the LOI value increased to 28.6 % with only 4 wt% PDPA added, which comes down to the superior free radical capture and dilution effect of PDPA in the vapor phase and the melting droplet effect. More appealingly, the crystallinity of PLA/4.0PDPA was significantly enhanced to 43.4 % from 2.5 % of PLA, and the shortest t1/2 was 4 mins in the isothermal crystallization process due to the excellent heterogeneous nucleation of PDPA. Moreover, PLA/PDPA composites maintain almost the same mechanical performance as pure PLA. In brief, this work provides a green strategy for the preparation of PLA composites with excellent comprehensive performance and shows great potential in engineering materials.

17.
J Hazard Mater ; 471: 134349, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38653140

RESUMO

Concerns over worldwide plastic pollution have led to the development of biodegradable polyester materials with excellent physical and chemical properties through the copolymerization of poly(butylene oxalate) (PBOx). As a result, poly(butylene oxalate-co-terephthalate)s (PBOTs) with varying compositions, were prepared by incorporating aromatic units. Studies have indicated that PBOT-47 (with a 47% molar terephthalate), exhibits exceptional mechanical properties. With an elongation at break of 1160% and a tensile strength that remains above 30 MPa, similar to or even better than those of the commercial biodegradable plastic poly(butylene adipate-co-terephthalate) PBAT-47 (47% molar terephthalate). Moreover, the permeability coefficients of PBAT-47 for H2O, CO2 and O2 were 5.8, 50.6 and 5.6 times higher than that of PBOT-47, revealing the superior barrier properties of PBOT. Through experimental research and theoretical simulation, the mechanism of the copolymer hydrolysis was elucidated. The readily hydrolytic nature of the oxalate unit endows it with the capacity for rapid degradation, possessing the potential to be a short-term degradable material with physical properties similar to PBAT.

18.
Int J Biol Macromol ; 263(Pt 2): 130435, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38408585

RESUMO

Currently, it has long been considered a challenge to provide sustainable additives for polylactide (PLA) in green way to endow it excellent comprehensive properties. Given the flammability and unsatisfactory crystallization performance of PLA, a furan-based phosphate furfurylamine trimethylphosphate (FATMP) was synthesized from 2-furfurylamine and amino trimethylphosphonic acid by a simple hydration reaction, and the PLA/FATMP composites were prepared by melting blending process. The tensile performance, crystallization behaviors, flame retardancy, and flame-retardant mechanism received special attention. Results showed that the incorporation of only 3 wt% FATMP could indeed increase the LOI value of PLA from 19.8 to 27.3 %, and simultaneously acquired V-0 rating in the vertical burning test owing to the favorable synergistic effect between the vapor phase and the condensed phase. Additionally, the half-crystallization time of PLA was decreased from 12.4 to 5.1 mins with the addition of FATMP, which acted as a nucleating agent. More appealingly, the tensile performance of PLA/FATMP composites was also well maintained. In general, the PLA/FATMP composites we proposed could be promising candidates in application fields where favorable flame retardancy and crystallization ability are required.


Assuntos
Organofosfatos , Fosfatos , Poliésteres , Aminoácidos , Furanos
19.
Int J Biol Macromol ; 254(Pt 1): 127701, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37907179

RESUMO

3D-printing provides a feasible technique for realizing new materials into structural and intelligent parts. In this work, biomass furan-based polyesters poly (ethylene furanoate) (PEF), poly (trimethylene furanoate) (PTF), and poly (butylene furanoate) (PBF) were successfully synthesized in a 5 L reactor through the melt polycondensation process and fabricated into 3D-printing feedstocks. It was demonstrated that the three furan-based polyesters were additively-manufactured into complicated structures. Besides, the mechanical and thermal properties of furan-based polyesters could be tailored by the chain length of diol monomer. The mechanical performance of 3D-printed PEF, PTF and PBF were characterized and compared with commercial filaments. The tensile strength of PEF and PTF could reach 74.6 and 63.8 MPa respectively, which exhibited superior tensile property to poly(ether-ether-ketone) (PEEK), polyamide (PA) and polylactic acid (PLA). Meanwhile, the compression results demonstrated that the PEF and PTF possessed comparable energy absorption capacity with PEEK and PLA respectively, which indicated excellent mechanical properties of furan-based polyesters. It was interesting to find that the 3D-printed structures including solid cube, bionic flower and lattice structures were employed to prove that the PTF possessed excellent shape memory properties. Therefore, the proposed biomass furan-based polymers would offer more freedom in the field of 3D-printing.


Assuntos
Poliésteres , Polímeros , Biomassa , Éteres , Impressão Tridimensional
20.
Front Microbiol ; 15: 1296059, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38322313

RESUMO

Objective: This study aimed to evaluate the clinical value of dynamic monitoring of neutrophil/lymphocyte ratio (NLR), APACHE II (Acute Physiology and Chronic Health Evaluation II) score, and Sequential Organ Failure Assessment (SOFA) score in predicting 28-day prognosis and drug resistance in patients with bloodstream infection with Acinetobacter baumannii-calcoaceticus complex (Abc complex). Patients and methods: In this research, individuals admitted to Tianjin Medical University General Hospital from January 2017 to March 2023 with bloodstream infections and a minimum of one Abc complex positive blood culture were chosen. The risk factors for the 28-day prognosis and drug resistance were analyzed using logistic regression. The NLR, APACHE II score, and SOFA score were evaluated for predicting 28-day prognosis and drug resistance using an ROC curve analysis. The data were analyzed using R Studio to find correlations and conduct survival analysis with the Kaplan-Meier method. Results: The final statistical analysis included a total of 129 patients with bloodstream infections caused by Abc complex. Independent risk factors predicting mortality within 28 days were identified as follows: the SOFA score and APACHE II scores at 24 h, and APACHE II scores at 72 h after the onset of blood infection (p < 0.05). NLR, SOFA score, and APACHE II score did not predict drug resistance. Patients with Carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex (CRAB) had shorter survival times than those with carbapenem-sensitive strains (40.77 days vs. 47.65 days, respectively, p = 0.0032). Conclusion: The prognosis of Abc complex bloodstream infection is affected by both SOFA and APACHE II scores. Both scoring systems have similar prognostic values at different time points after infection, but for computational convenience, it is recommended to use the SOFA score. NLR exhibits limited effectiveness in predicting mortality within 28 days. Carbapenem-resistant individuals with Abc complex experience significantly reduced survival time. None of the three factors-SOFA score, APACHE II score, and NLR-can early predict the occurrence of CRAB infections effectively.

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