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1.
Angew Chem Int Ed Engl ; : e202413105, 2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39209733

RESUMO

Additive engineering plays a pivotal role in achieving high-quality light-absorbing layers for high-performance and stable perovskite solar cells (PSCs). Various functional groups within the additives exert distinct regulatory effects on the perovskite layer. However, few additive molecules can synergistically fulfill the dual functions of regulating crystallization and passivating defects. Here, we custom-synthesized 2-ureido-4-pyrimidone (UPy) organic small molecules with diverse functional groups as additives to modulate crystallization and defects in perovskite films via the Michael addition reaction. Theoretical and experimental investigations demonstrate that the -OH groups in UPy exhibit significant effects in fixing uncoordinated Pb2+ ions, passivation of lead-iodide antisite defects, alleviating hysteresis, and reducing non-radiative recombination. Furthermore, the enhanced C=O and -NH2 motifs interact with the A-site cation via hydrogen bonding, which relieves residual strain and adjusts crystal orientation. This strategy effectively controls perovskite crystallization and passivates defects, ultimately enhancing the quality of perovskite films. Consequently, the open-circuit voltage of the UPy-based p-i-n PSCs reaches 1.20 V, and the fill factor surpasses 84%. The champion device delivers a power conversion efficiency of 25.75%. Remarkably, the unencapsulated device maintained 96.9% and 94.5% of its initial efficiency following 3,360 hours of dark storage and 1,866 hours of 1-sun illumination, respectively.

2.
J Sci Food Agric ; 103(15): 7702-7711, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37439120

RESUMO

BACKGROUND: Spleen deficiency syndrome (SDS) is associated with elevated inflammatory factors and dysregulation of gastrointestinal motility hormones and intestinal microbiota. Qushi decoction (QD), a traditional formula, has not been reported using modern scientific research methods for changes in its probiotic fermented QD (FQD) composition and its potential mechanisms to alleviate SDS. Therefore, the aim of this study was to investigate the splenic protection of FQD in SDS rats by modulating gastrointestinal motility hormones and intestinal microbiota. RESULTS: The results showed that FQD increased total polysaccharides, total protein, total flavonoids and the other active ingredients compared to QD, effectively improved splenic inflammation and apoptosis in SDS rats, and modulated gastrointestinal motility hormones to alleviate diarrhea and other symptoms. In addition, the dysregulation of the gut microbiota was reversed by increasing the levels of Bifidobacterium and decreasing the levels of Escherichia-Shigella and Proteobacteria, which may be related to the regulation of bacterial metabolites to alleviate SDS. CONCLUSION: These results suggest that FQD is an effective formula for improving SDS. Our findings show that FQD beneficial to the implications for the treatment of SDS. © 2023 Society of Chemical Industry.


Assuntos
Microbioma Gastrointestinal , Probióticos , Esplenopatias , Ratos , Animais , Disbiose/induzido quimicamente , Disbiose/tratamento farmacológico , Reserpina/efeitos adversos , Probióticos/farmacologia , Esplenopatias/induzido quimicamente , Esplenopatias/tratamento farmacológico , Hormônios/efeitos adversos
3.
Entropy (Basel) ; 23(4)2021 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-33918833

RESUMO

Electroencephalography neurofeedback (EEG-NFB) training can induce changes in the power of targeted EEG bands. The objective of this study is to enhance and evaluate the specific changes of EEG power spectral density that the brain-machine interface (BMI) users can reliably generate for power augmentation through EEG-NFB training. First, we constructed an EEG-NFB training system for power augmentation. Then, three subjects were assigned to three NFB training stages, based on a 6-day consecutive training session as one stage. The subjects received real-time feedback from their EEG signals by a robotic arm while conducting flexion and extension movement with their elbow and shoulder joints, respectively. EEG signals were compared with each NFB training stage. The training results showed that EEG beta (12-40 Hz) power increased after the NFB training for both the elbow and the shoulder joints' movements. EEG beta power showed sustained improvements during the 3-stage training, which revealed that even the short-term training could improve EEG signals significantly. Moreover, the training effect of the shoulder joints was more obvious than that of the elbow joints. These results suggest that NFB training can improve EEG signals and clarify the specific EEG changes during the movement. Our results may even provide insights into how the neural effects of NFB can be better applied to the BMI power augmentation system and improve the performance of healthy individuals.

4.
Sensors (Basel) ; 20(21)2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-33182271

RESUMO

A power-assisted exoskeleton should be capable of reducing the burden on the wearer's body or rendering his or her work improved and efficient. More specifically, the exoskeleton should be easy to wear, be simple to use, and provide power assistance without hindering the wearer's movement. Therefore, it is necessary to evaluate the backdrivability, range of motion, and power-assist capability of such an exoskeleton. This evaluation identifies the pros and cons of the exoskeleton, and it serves as the basis for its subsequent development. In this study, a lightweight upper-limb power-assisted exoskeleton with high backdrivability was developed. Moreover, a motion capture system was adopted to measure and analyze the workspace of the wearer's upper limb after the exoskeleton was worn. The results were used to evaluate the exoskeleton's ability to support the wearer's movement. Furthermore, a small and compact three-axis force sensor was used for power assistance, and the effect of the power assistance was evaluated by means of measuring the wearer's surface electromyography, force, and joint angle signals. Overall, the study showed that the exoskeleton could achieve power assistance and did not affect the wearer's movements.


Assuntos
Exoesqueleto Energizado , Extremidade Superior , Fenômenos Biomecânicos , Eletromiografia , Humanos , Movimento , Amplitude de Movimento Articular
5.
Microb Cell Fact ; 18(1): 87, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-31109314

RESUMO

BACKGROUND: Saccharomyces cerevisiae AN120 osw2∆ spores were used as a host with good resistance to unfavorable environment. This work was undertaken to develop a new yeast spore-encapsulation of Candida parapsilosis Glu228Ser/(S)-carbonyl reductase II and Bacillus sp. YX-1 glucose dehydrogenase for efficient chiral synthesis in organic solvents. RESULTS: The spore microencapsulation of E228S/SCR II and GDH in S. cerevisiae AN120 osw2∆ catalyzed (R)-phenylethanol in a good yield with an excellent enantioselectivity (up to 99%) within 4 h. It presented good resistance and catalytic functions under extreme temperature and pH conditions. The encapsulation produced several chiral products with over 70% yield and over 99% enantioselectivity in ethyl acetate after being recycled for 4-6 times. It increased substrate concentration over threefold and reduced the reaction time two to threefolds compared to the recombinant Escherichia coli containing E228S and glucose dehydrogenase. CONCLUSIONS: This work first described sustainable enantioselective synthesis without exogenous cofactors in organic solvents using yeast spore-microencapsulation of coupled alcohol dehydrogenases.


Assuntos
Oxirredutases do Álcool/metabolismo , Bacillus/metabolismo , Candida parapsilosis/metabolismo , Composição de Medicamentos/métodos , Glucose 1-Desidrogenase/metabolismo , Saccharomyces cerevisiae/metabolismo , Esporos Fúngicos/metabolismo , Solventes
6.
Zhongguo Zhong Yao Za Zhi ; 42(1): 192-197, 2017 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-28945048

RESUMO

Glass transition theory is an important theory in polymer science, which is used to characterize the physical properties. It refers to the transition of amorphous polymer from the glassy state to the rubber state due to heating or the transition from rubber state to glassy state due to cooling. In this paper, the glassy state and glass transition of food and the similar relationship between the composition of Chinese medicine extract powder and food ingredients were described; the determination method for glass transition temperature (Tg) of Chinese medicine extract powder was established and its main influencing factors were analyzed. Meanwhile, the problems in drying process, granulation process and Chinese medicine extract powder and solid preparation storage were analyzed and investigated based on Tg, and then the control strategy was put forward to provide guidance for the research and production of Chinese medicine solid preparation.


Assuntos
Medicamentos de Ervas Chinesas/química , Transição de Fase , Pós , Temperatura de Transição , Química Farmacêutica , Dessecação
7.
Microb Cell Fact ; 15(1): 143, 2016 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-27534936

RESUMO

BACKGROUND: Candida parapsilosis (R)-carbonyl reductase (RCR) and (S)-carbonyl reductase (SCR) are involved in the stereoconversion of racemic (R,S)-1-phenyl-1,2-ethanediol (PED) to its (S)-isomer. RCR catalyzes (R)-PED to 2-hydroxyacetophenone (2-HAP), and SCR catalyzes 2-HAP to (S)-PED. However, the stereoconversion efficiency of racemic mixture to (S)-PED is not high because of an activity imbalance between RCR and SCR, with RCR performing at a lower rate than SCR. To realize the efficient preparation of racemic mixture to (S)-PED, an in situ expression of RCR and a two-stage control strategy were introduced to rebalance the RCR- and SCR-mediated pathways. RESULTS: An in situ expression plasmid pCP was designed and RCR was successfully expressed in C. parapsilosis. With respect to wild-type, recombinant C. parapsilosis/pCP-RCR exhibited over four-fold higher activity for catalyzing racemic (R,S)-PED to 2-HAP, while maintained the activity for catalyzing 2-HAP to (S)-PED. The ratio of k cat /K M for SCR catalyzing (R)-PED and RCR catalyzing 2-HAP was about 1.0, showing the good balance between the functions of SCR and RCR. Based on pH and temperature preferences of RCR and SCR, a two-stage control strategy was devised, where pH and temperature were initially set at 5.0 and 30 °C for RCR rapidly catalyzing racemic PED to 2-HAP, and then adjusted to 4.5 and 35 °C for SCR transforming 2-HAP to (S)-PED. Using these strategies, the recombinant C. parapsilosis/pCP-RCR catalyzed racemic PED to its (S)-isomer with an optical purity of 98.8 % and a yield of 48.4 %. Most notably, the biotransformation duration was reduced from 48 to 13 h. CONCLUSIONS: We established an in situ expression system for RCR in C. parapsilosis to rebalance the functions between RCR and SCR. Then we designed a two-stage control strategy based on pH and temperature preferences of RCR and SCR, better rebalancing RCR and SCR-mediated chiral biosynthesis pathways. This work demonstrates a method to improve chiral biosyntheses via in situ expression of rate-limiting enzyme and a multi-stage control strategy to rebalance asymmetric pathways.


Assuntos
Oxirredutases do Álcool/genética , Aldeído Redutase/genética , Aldeído Redutase/metabolismo , Candida/genética , Etilenoglicóis/química , Etilenoglicóis/metabolismo , Oxirredutases do Álcool/química , Aldeído Redutase/química , Candida/enzimologia , Candida/metabolismo , Clonagem Molecular , Etilenoglicol/metabolismo , Expressão Gênica , Redes e Vias Metabólicas/genética
8.
Wei Sheng Wu Xue Bao ; 55(12): 1593-9, 2015 Dec 04.
Artigo em Chinês | MEDLINE | ID: mdl-27101702

RESUMO

OBJECTIVE: To realize efficient biotransformation of (S)-1-phenyl-1,2-ethanediol by recombinant (S)-carbonyl reductase II, we expressed (S)- carbonyl reductase II from Candida parapsilosis CCTCC M203011 and embedded it in the spores of Saccharomyces cerevisiae AN120. METHODS: (S)-carbonyl reductase II gene was cloned from C. parapsilosis genome and expressed in S. cerevisiae AN120 by PCR amplification. When cultured with potassium acetate as the sole carbon source, the yeast spores were produced, and embedded the recombinant (S)-carbonyl reductase II. Using 10% W/V spores as biocatalysts, 6 g/L 2-hydroxyacetophenone as substrate, the biotransformation was carried out and the optical purity and yield of products were analyzed by HPLC. During the biotransformation of 2-hydroxyacetophenone to (S)-1-phenyl-1,2-ethanediol, the optimal temperature and pH, stability and reusability of the recombinant spores were determined. RESULTS: The recombinant yeast spores showed excellent performance to give (S)-1-phenyl-1,2- ethanediol with a high optical purity of 99.3% and a high yield of 99.0% at the optimal temperature (40 °C) and pH (6.0). Compared with the recombinant Escherichia coli, the spores improved the yield of (S)-1-phenyl-1,2-ethanediol from 89.7% to 99.0%, and shortened the biotransformation duration from 48 h to 4 h. After being reused for 10 times, the recombinant spores biotransformed (S)-1-phenyl-1,2-ethanediol with a stable optical purity of about 99% and a yield over 85%. CONCLUSION: The heterologous expression of oxidoreductases was first realized in yeast spores, which laid a solid foundation for efficient preparation of chiral compounds.


Assuntos
Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Candida/enzimologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Saccharomyces cerevisiae/genética , Esporos Fúngicos/genética , Oxirredutases do Álcool/química , Candida/química , Candida/genética , Clonagem Molecular , Estabilidade Enzimática , Proteínas Fúngicas/química , Expressão Gênica , Concentração de Íons de Hidrogênio , Saccharomyces cerevisiae/metabolismo , Esporos Fúngicos/metabolismo , Temperatura
9.
Health Promot Chronic Dis Prev Can ; 44(7-8): 349, 2024 Aug.
Artigo em Inglês, Francês | MEDLINE | ID: mdl-39141619

RESUMO

The Maternal and Infant Health Section of the Public Health Agency of Canada (PHAC) is pleased to announce an update to the Perinatal Health Indicators (PHI) Data Tool. The interactive Data Tool on the PHAC Infobase website presents statistics on maternal, fetal and infant health in Canada based on data from the Canadian Institute for Health Information's (CIHI) Discharge Abstract Database (DAD), the Canadian Community Health Survey (CCHS), and the Canadian Vital Statistics (birth, stillbirth and death databases). The data include 20 indicators grouped into four key health domains: health behaviours and practices, health services, maternal outcomes, and infant outcomes. For this update, five new indicators were added and three existing ones were modified. To access the latest Perinatal Health Indicators Data Tool, visit https://health-infobase.canada.ca/phi/.


RÉSUMÉ: Résumé : La Section de la santé maternelle et infantile de l'agence de la santé publique du Canada (ASPC) a le plaisir d'annoncer une mise à jour de données sur les indicateurs de la santé périnatale (ISP). L'outil de données interactif se trouve sur le site Web de l'Infobase de l'ASPC et présente les statistiques sur la santé maternelle, foetale et infantile au Canada fondées sur les données de la Base de données sur les congés des patients (BDCP) de l'Institut canadien d'information sur la santé (ICIS), de l'Enquête sur la santé dans les collectivités canadiennes (ESCC) et de la Base canadienne de données de l'état civil (bases de données sur les naissances, les mortinaissances et les décès). Les données comprennent 20 indicateurs regroupés en quatre principaux domaines de la santé: comportements et pratiques en santé, services de santé, santé maternelle et santé infantile. Dans le cadre de cette mise à jour, cinq nouveaux indicateurs ont été ajoutés et trois indicateurs existants ont été modifiés. Pour accéder au plus récent outil de données sur les indicateurs de la santé périnatale, consultez le : https://sante-infobase.canada.ca/isp/.


Assuntos
Indicadores Básicos de Saúde , Humanos , Canadá/epidemiologia , Feminino , Gravidez , Recém-Nascido , Assistência Perinatal/métodos , Assistência Perinatal/normas , Assistência Perinatal/organização & administração , Saúde do Lactente , Saúde Materna , Comportamentos Relacionados com a Saúde , Lactente , Bases de Dados Factuais
10.
RSC Adv ; 14(30): 21398-21410, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38979454

RESUMO

Formaldehyde adsorption on intrinsic La2O3 surface, four-fold coordinated oxygen vacancy (VO4c), six-fold coordinated oxygen vacancy (VO6c), and iridium-doped La2O3(001) surface was studied by the first-principles method. The results show that formaldehyde adsorption on the Ir-doped La2O3(001) surface with VO6c is the strongest because of the directional movement of electrons caused by the interaction of the Ir-5d orbitals and internal oxygen vacancy, wherein the adsorption energy is 3.23 eV. This model showed a significant increase in adsorption energy, indicating that Ir doping improves the formaldehyde adsorption capacity of the La2O3(001) surface. The energy band analysis shows that iridium doping introduces impurity energy levels into the intrinsic La2O3 energy band, which enhances the interaction between the La2O3(001) surface and formaldehyde molecules. Density of state analysis indicated that the adsorption of formaldehyde molecules on the La2O3(001) surface is mainly due to the interaction between the O-2p, C-2p orbitals of formaldehyde and the Ir-5d orbital of iridium atoms. Furthermore, the existence of VO4c and VO6c defects has no effect on the position and shape of the valence and conduction bands. The effects of oxygen vacancy and iridium doping on the optical properties mainly appeared in the low-energy infrared and visible regions, making the O-2p, C-2p orbitals of formaldehyde and the Ir-5d, O-2p orbitals of the La2O3(001) surface become hybridized near the Fermi level and the electronic transition from the valence band to conduction band more likely to occur. The La2O3 material can be used as an ideal photocatalytic material for formaldehyde degradation.

11.
J Affect Disord ; 367: 219-228, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39226938

RESUMO

BACKGROUND: Enhancing psychosocial functioning is crucial for reducing relapse in depression, but methods for monitoring and recovery are unclear. METHOD: A 1-year follow-up study assessed psychosocial functioning in 182 patients with remitted depression at baseline (T0) as well as at 1, 2, 6, 9, and 12 months post-remission (T1-T5). Using generalized estimating equations (GEE) and multiple linear regression (MLR), we analyzed the impact of changes in psychosocial functioning on relapse/recurrence risk, and assessed the influence of various factors. RESULTS: An increase in psychosocial functioning significantly lowered relapse/recurrence odds by 54.2 %, averaging a risk reduction of 3.1 %. GEE analyses indicated subjective depressive symptoms (ß = -0.315) most significantly impacted psychosocial functioning, followed by social support (ß = 0.236), positive coping (ß = 0.225), and negative automatic thoughts (ß = -0.183). Negative coping and expressed emotion exhibited non-significant effects. MLR revealed that the impact of negative automatic thoughts was most significant at initial remission, but the relative importance of residual subjective depressive symptoms, positive coping, and social support on psychosocial functioning remained stable over time. LIMITATIONS: Predetermined follow-up assessments may not fully capture psychosocial functioning at relapse/recurrence, and the inclusion of factors might not be sufficiently comprehensive. CONCLUSIONS: Recovery of psychosocial functioning significantly reduces relapse risk in post-remission patients with depression more than residual subjective depressive symptoms. The degree of influence of factors on psychosocial functioning can change with the length of remission time.

12.
ACS Omega ; 8(1): 1206-1219, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36643490

RESUMO

Natural fractures (NFs) and bedding planes (BPs) are well developed in shale reservoirs. The propagation of hydraulic fractures (HFs) and the opening of NFs and BPs can produce induced stress fields (ISFs) within the fracturing process, causing interference to the in situ stress field. Aiming at the "stress shadow" effect among HFs in horizontal wells, the calculation models of HFs, BPs, and NFs for induced stress distributions are established based on displacement discontinuity theory, which can quantitatively characterize the composite ISF of the three under different connecting states. In addition, the interference coefficient of stress intensity factor (ICSIF) is introduced to quantitatively evaluate the interference degree of the composite ISF to the propagation of HFs. The results show that: (1) the ISF forms a "tensile stress concentration zone" near the fracture surface to promote the HFs opening and a "compressive stress concentration zone" at the fracture tips to suppress the propagation of HFs; (2) the ISF forms an elliptical effective swept area around the fracture, which is affected by the propagation height of HFs, while NFs or BPs generate local disturbances to the ISF; (3) the in situ stress reverses in the swept area, and the stress reversal interval is related to the in situ stress difference, fracture propagation height, Poisson's ratio, fracture net pressure, and fracture spacing; (4) the reasonable fracture spacing and fracture propagation height of horizontal wells can be determined by the ICSIF. The study can provide theoretical guidance for optimizing the fracture spacing and promoting the uniform propagation of multiple fractures in staged fracturing of horizontal wells.

13.
Adv Sci (Weinh) ; 10(35): e2304733, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37828594

RESUMO

Flexible perovskite solar cells (f-PSCs) as a promising power source have grabbed surging attention from academia and industry specialists by integrating with different wearable and portable electronics. With the development of low-temperature solution preparation technology and the application of different engineering strategies, the power conversion efficiency of f-PSCs has approached 24%. Due to the inherent properties and application scenarios of f-PSCs, the study of strain in these devices is recognized as one of the key factors in obtaining ideal devices and promoting commercialization. The strains mainly from the change of bond and lattice volume can promote phase transformation, induce decomposition of perovskite film, decrease mechanical stability, etc. However, the effect of strain on the performance of f-PSCs has not been systematically summarized yet. Herein, the sources of strain, evaluation methods, impacts on f-PSCs, and the engineering strategies to modulate strain are summarized. Furthermore, the problems and future challenges in this regard are raised, and solutions and outlooks are offered. This review is dedicated to summarizing and enhancing the research into the strain of f-PSCs to provide some new insights that can further improve the optoelectronic performance and stability of flexible devices.

14.
Adv Mater ; 34(50): e2206812, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36269022

RESUMO

Organic molecules have been considered promising energy-storage materials in aqueous zinc-ion batteries (ZIBs), but are plagued by poor conductivity and structural instability because of the short-range conjugated structure and low molecular weight. Herein, an imine-based tris(aza)pentacene (TAP) with extended conjugated effects along the CN backbones is proposed, which is in situ injected into layered MXene to form a TAP/Ti3 C2 Tx cathode. Theoretical and electrochemical analyses reveal a selective H+ /Zn2+ co-insertion/extraction mechanism in TAP, which is ascribed to the steric effect on the availability of active CN sites. Moreover, Ti3 C2 Tx , as a conductive scaffold, favors fast Zn2+ diffusion to boost the electrode kinetics of TAP. Close electronic interactions between TAP and Ti3 C2 Tx preserve the structural integrity of TAP/Ti3 C2 Tx during the repeated charge/discharge. Accordingly, the TAP/Ti3 C2 Tx cathode delivers a high reversible capacity of 303 mAh g-1 at 0.04 A g-1 in aqueous ZIBs, which also realizes an ultralong lifetime over 10 000 cycles with a capacity retention of 81.6%. Furthermore, flexible Zn||TAP/Ti3 C2 Tx batteries with a quasi-solid-state electrolyte demonstrate potential application in wearable electronic devices. This work offers pivotal guidance to create highly stable organic electrodes for advanced ZIBs.

15.
Front Pharmacol ; 13: 913935, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35860024

RESUMO

Background: Lithium is an effective medication approved for the treatment of bipolar disorder (BD). It has a narrow therapeutic index (TI) and requires therapeutic drug monitoring. This study aimed to conduct a population pharmacokinetics (PPK) analysis of lithium and investigate the appropriateness of the dosing regimen according to different patient characteristics. Methods: A total of 476 lithium concentrations from 268 patients with bipolar disorder were analyzed using nonlinear mixed-effects modeling. Monte Carlo simulations were employed to investigate the influence of covariates, such as weight, creatinine clearance, and daily doses of lithium concentrations, and to determine the individualized dosing regimens for patients. Results: Lithium PK was described by a one-compartment model with first-order absorption and elimination processes. The typical estimated apparent clearance was 0.909 L/h-1 with 16.4% between-subject variability in the 62 kg patients with 116 ml/min creatinine clearance and 600 mg daily doses. To achieve a target trough concentration (0.4-0.8 mmol/L) in the maintenance phase, the regimen of 500 mg than 750 mg daily dose was recommended for patients with renal insufficiency and weighing 100 kg. Conclusion: A PPK model for lithium was developed to determine the influence of patient characteristics on lithium pharmacokinetics. Weight, creatinine clearance, and total daily dose of lithium can affect the drug's clearance. These results demonstrate the nonlinear renal excretion of lithium; hence, dosage adjustments are recommended for patients with renal insufficiency.

16.
Materials (Basel) ; 13(6)2020 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-32204342

RESUMO

Low surface energy coatings have gained considerable attention due to their superior surface hydrophobic properties. However, their abrasion resistance and sustainability of surface hydrophobicity are still not very satisfactory and need to be improved. In this work, a series of utraviolet (UV)-curable fluorosiloxane copolymers were synthesized and used as reactive additives to prepare polyurethane acrylate coatings with low surface energy. The effect of the addition of the fluorinated graft copolymers on the mechanical durability and surface hydrophobicity of the UV-cured hybrid films during the friction-annealing treatment cycles was investigated. The results show that introducing fluorosiloxane additives can greatly enhance surface hydrophobicity of the hybrid film. With addition of 2 wt.% fluorosiloxane copolymers, the water contact angle (WCA) value of the hybrid film was almost tripled compared to that of the pristine PU film, increasing from 58° to 144°. The hybrid film also showed enhanced abrasion resistance and could withstand up to about 60 times of friction under a pressure of 20 kPa. The microstructure formed in the annealed film was found to contribute much to achieve better surface hydrophobicity. The polyurethane acrylate/fluorinated siloxane resin hybrid film prepared in this study exhibits excellent potential for applications in the low surface energy field.

17.
Materials (Basel) ; 13(24)2020 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-33371424

RESUMO

Due to their excellent mechanical and thermal properties and medium resistance, epoxy/carbon nanotubes and nanocomposites have been widely used in many fields. However, the conventional thermosetting process is not only time- and energy-consuming, but also causes the agglomeration of nanofillers, which leads to unsatisfactory properties of the obtained composites. In this study, multi-walled carbon nanotubes (MWCNTs)/epoxy nanocomposites were prepared using UV photoinduced frontal polymerization (PIFP) in a rapid fashion. The addition of MWCNTs modified by a surface carboxylation reaction was found to enhance the impact strength and heat resistance of the epoxy matrix effectively. The experimental results indicate that with 0.4 wt % loading of modified MWCNTs, increases of 462.23% in the impact strength and 57.3 °C in the glass transition temperature Tg were achieved. A high-performance nanocomposite was prepared in only a few minutes using the PIFP approach. Considering its fast, energy-saving, and environmentally friendly production, the PIFP approach displays considerable potential in the field of the fast preparation, repair, and deep curing of nanocomposites and coatings.

19.
J Mater Chem B ; 7(44): 7006-7013, 2019 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-31626265

RESUMO

Non-enzymatic glucose sensors are attracting significant attention owing to their low cost, storage convenience and reusability; however, their poor anti-interference caused by their weak selectivity towards glucose limits their practicability. In the present study, a MIL-53(NiFe) metal-organic framework (MOF) was prepared on Ni foam to serve as a self-supported electrode for non-enzymatic glucose detection. Due to the abundant active sites in the MIL-53(NiFe) MOF and its good stability in an alkaline solution, the sensors exhibited a high sensitivity (41.95 mA mM-1 cm-2) and a low detection limit (0.67 µM). Moreover, the molecular sieve effect of the MIL-53(NiFe) MOF led to a remarkable anti-interference ability, even at the interference concentrations of up to 20% glucose, a higher value than that in human serum. In addition, a heat treatment was carried out to remove the residual terephthalic acid in the MOF tunnels, and this promoted the detection linear range to 2-1600 µM. The reusability, reproducibility and long-term stability of the sensors were also studied, and the results implied good practicability of the MIL-53(NiFe) MOF-based sensors. Furthermore, the good practicability of the sensors was verified by testing human serum samples. The results showed the relative standard deviation of 2.73% from the hospital results, and the standard recovery was nearly 100%.


Assuntos
Técnicas Eletroquímicas/instrumentação , Glucose/química , Estruturas Metalorgânicas , Humanos , Difração de Raios X
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