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1.
J Org Chem ; 86(3): 2827-2839, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33467848

RESUMO

A protocol for the preparation of 7-amido indoles via regioselective C-H bond functionalization has been first accomplished under Ru(II) catalysis. Indole derivatives and 4-aryl/heteroaryl/benzyl/alkyl dioxzaolines containing various substituents were applicable for this transformation, readily providing the amidated indoles in moderate to good yields. This novel process has many advantages, including good compatibility with diverse functional groups, broad substrate scopes, and mild reaction conditions. Deuteration studies and control experiments have been performed to understand the mechanism of this transformation.


Assuntos
Rutênio , Catálise , Indóis , Fenômenos de Química Orgânica , Temperatura
2.
Int Heart J ; 62(3): 647-657, 2021 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-33994507

RESUMO

Bioinformatics analysis showed that miR-448-5p expression in the myocardial tissue of rats with myocardial infarction significantly increased, suggesting that it may participate in myocardial cell apoptosis in myocardial infarction. This study aimed to explore the protective effects of miR-448-5p on hypoxic myocardial cells.H9C2 cells were cultured and subjected to anoxia for 2, 4, and 8 hours to establish a hypoxia model. MiR-448-5p mimic and inhibitor were transfected into the cells; then, a dual-luciferase experiment was conducted to verify the targeting relationship between miR-448-5p and VEGFA. Cell viability and apoptosis was detected by cell counting kit-8 and flow cytometry, respectively. The expressions of apoptosis-related proteins, miR-448-5p, FAS, and FAS-L were measured using western blotting and quantitative reverse transcription-polymerase chain reaction (qRT-PCR).Hypoxia-reduced H9C2 cell viability and promoted apoptosis. MiR-448-5p expression was increased after H9C2 cell hypoxia. MiR-448-5p mimic significantly inhibited the viability and promoted the apoptosis of hypoxia-induced model cells. Hypoxia promoted the expression of apoptosis-related protein B-cell lymphoma-2 (Bcl-2) and inhibited the expressions of Bcl-2-associated x protein (Bax), cleaved caspase-3, and caspase-3, whereas the effect of inhibitor on hypoxia-reduced H9C2 cell and apoptotic protein expression were opposite to miR-448-5p mimic. MiR-448-5p targeted VEGFA and regulated its expression. Silenced VEGFA expression significantly inhibited inhibitor effect on increasing cell viability and promoted apoptosis. In addition, miR-448-5p mimic inhibited the effect of hypoxia on promoting the expressions of FAS and FAS-L of H9C2 cells. Inhibitors had the opposite effect on cell hypoxia model.The miR-448-5p/VEGFA axis could protect cardiomyocytes from hypoxia through inhibiting the FAS/FAS-L signaling pathway.


Assuntos
Hipóxia/metabolismo , MicroRNAs/metabolismo , Miócitos Cardíacos/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor fas/metabolismo , Animais , Apoptose , Linhagem Celular , Proteína Ligante Fas/metabolismo , Ratos , Transdução de Sinais
3.
Molecules ; 26(8)2021 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-33920289

RESUMO

Constructing polymeric materials with stretchable and self-healing properties arise increasing interest in the field of tissue engineering, wearable electronics and soft actuators. Herein, a new type of supramolecular cross-linker was constructed through host-guest interaction between pillar[5]arene functionalized acrylate and pyridinium functionalized acrylate, which could form supramolecular polymeric material via photo-polymerization of n-butyl acrylate (BA). Such material exhibited excellent tensile properties, with maximum tensile strength of 3.4 MPa and strain of 3000%, respectively. Moreover, this material can effectively dissipate energy with the energy absorption efficiency of 93%, which could be applied in the field of energy absorbing materials. In addition, the material showed self-healing property after cut and responded to competitive guest.

4.
J Nat Prod ; 79(5): 1354-64, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27140807

RESUMO

Nine unexpected new flavonol glycoside cyclodimers in the truxinate (1-7, biginkgosides A-G, respectively) or truxillate [biginkgosides H (8) and I (9)] forms were isolated as minor components from the extract of Ginkgo biloba leaves. The new dimers possess an unusual cyclobutane ring formed by a [2+2]-cycloaddition between two symmetric (for compounds 1-5 and 7-9) or nonsymmetric (for 6) flavonol coumaroyl glucorhamnosides. A plausible biosynthetic pathway for these new compounds based on the frontier molecular orbital theory of cycloaddition reactions is briefly discussed. An antineuroinflammatory screening revealed that biginkgosides E (5) and H (8) inhibited nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells, with IC50 values of 2.91 and 17.23 µM, respectively. Additionally, biginkgoside F (6) showed a significant neuroprotective effect (34.3% increase in cell viability at 1 µM) against Aß25-35-induced cell viability decrease in SH-SY5Y neuroblastoma cells.


Assuntos
Peptídeos beta-Amiloides/farmacologia , Medicamentos de Ervas Chinesas/isolamento & purificação , Medicamentos de Ervas Chinesas/farmacologia , Flavonóis/isolamento & purificação , Flavonóis/farmacologia , Ginkgo biloba/química , Glicosídeos/isolamento & purificação , Glicosídeos/farmacologia , Fármacos Neuroprotetores/farmacologia , Folhas de Planta/química , Peptídeos beta-Amiloides/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Medicamentos de Ervas Chinesas/química , Ésteres , Flavonóis/química , Glicosídeos/química , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Estrutura Molecular , Neuroblastoma/tratamento farmacológico , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/isolamento & purificação , Óxido Nítrico/biossíntese , Ressonância Magnética Nuclear Biomolecular , Fragmentos de Peptídeos/efeitos dos fármacos , Extratos Vegetais/farmacologia
5.
Parasitol Res ; 114(7): 2639-47, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25895062

RESUMO

More than 40 kinds of mammals in China are known to be naturally infected with Schistosoma japonicum (S. japonicum) (Peng et al. Parasitol Res 106:967-76, 2010). Compared with permissive BALB/c mice, rats are less susceptible to S. japonicum infection and are considered to provide an unsuitable microenvironment for parasite growth and development. MicroRNAs (miRNAs), via the regulation of gene expression at the transcriptional and post-transcriptional levels, may be responsible for developmental differences between schistosomula in these two rodent hosts. Solexa deep-sequencing technology was used to identify differentially expressed miRNAs from schistosomula isolated from Wistar rats and BALB/c mice 10 days post-infection. The deep-sequencing analysis revealed that nearly 40 % of raw reads (10.37 and 10.84 million reads in schistosomula isolated from Wistar rats and BALB/c mice, respectively) can be mapped to selected mirs in miRBase or in species-specific genomes. Further analysis revealed that several miRNAs were differentially expressed in schistosomula isolated from these two rodents; 18 were downregulated (by <2-fold) and 23 were up-regulated (>2-fold) (expression levels in rats compare with those in mice). Additionally, three novel miRNAs were primarily predicted and identified. Among the 41 differentially expressed miRNAs, 4 miRNAs had been identified with specific functions in schistosome development or host-parasite interaction, such as sexual maturation (sja-miR-1, sja-miR-7-5p), embryo development (sja-miR-36-3p) in schistosome, and pathogenesis of schistosomiasis (sja-bantam). Then, the target genes were mapped, filtered, and correlated with a set of genes that were differentially expressed genes in schistosomula isolated from mice and rats, which we identified in a S. japonicum oligonucleotide microarray analysis in a previous study. Gene Ontology (GO) analysis of the predicted target genes of 13 differentially expressed miRNAs revealed that they were involved in some important biological pathways, such as metabolic processes, the regulation of protein catabolic processes, catalytic activity, oxidoreductase activity, and hydrolase activity. The study presented here includes the first identification of differentially expressed miRNAs between schistosomula in mice or rats. Therefore, we hypothesized that the differentially expressed miRNAs may affect the development, growth, and maturation of the schistosome in its life cycle. Our analysis suggested that some differentially expressed miRNAs may impact the survival and development of the parasite within a host. This study increases our understanding of schistosome development and host-parasite interactions.


Assuntos
Regulação da Expressão Gênica , Interações Hospedeiro-Parasita , MicroRNAs/genética , Schistosoma japonicum/genética , Esquistossomose Japônica/parasitologia , Animais , Biologia Computacional , Feminino , Biblioteca Gênica , Estágios do Ciclo de Vida , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Ratos , Ratos Wistar , Schistosoma japonicum/fisiologia , Análise de Sequência de DNA
6.
Org Lett ; 26(15): 3230-3234, 2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38563564

RESUMO

A novel and metal-free [3 + 2] annulation of tetraalkylthiuram disulfide with alkynes/alkenes has been developed using Selectfluor at room temperature. The formed 1,3-dithiol-2-ylium/1,3-dithiolan-2-ylium salts can be easily transformed into the corresponding 1,3-dithiol-2-ylidenes/1,3-ditholan-2-ylidenes by one-pot subsequent condensation with malononitrile. The present protocol features the use of easily accessible starting materials, mild reaction conditions, good tolerance with diverse functional groups, easy scale-up, and a wide substrate scope, affording the desired products in good yields. Importantly, this method is suitable for the late-stage modification of bioactive molecules. Furthermore, 1,3-dithiol-2-ylium salt can also be easily converted into various 1,3-dithiole derivatives by condensation, reduction, or hydrolysis. Mechanism studies show that this transformation involves radical annulation. Of note, this method presented a novel example using tetraalkylthiuram disulfide as a sulfur synthon in annulation, which greatly enriches the application of tetraalkylthiuram disulfides in organic synthesis. Biological evaluation indicates that these prepared compounds are promising candidates in terms of their antitumor activity.

7.
Mater Horiz ; 10(9): 3622-3630, 2023 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-37337709

RESUMO

Self-adaptive adhesion is essential for hydrogel sensors. However, the traditional protocol involves covering a pre-prepared hydrogel sensor on a tested surface. As a result, the sensor cannot achieve self-adaptive adhesion owing to an air-layer hindrance between the sensor and tested surface, which inevitably leads to the loss of critical biological signals. To address the issue of air-layer hindrance, this work proposes an in situ permeation method that enables the self-adaptive adhesion of hydrogel biosensors on various surfaces. After applying a liquid solution of poly(methacrylamido propyl trimethyl ammonium chloride-co-acrylamide) (poly(MPTAC-co-AM)) on the testing surface, a thin film of poly(acrylic aminoethane sulfonic acid-co-acrylamide) (poly(AASA-co-AM)) is applied, where the electrostatic interaction between -SO3- and -Me3N+ facilitates rapid permeation of the solution into the solid film, leading to the formation of a hydrogel layer in situ. The coating of liquid poly(MPTAC-co-AM) sweeps away the air layer and works as a natural glue, enabling a strong bonding interaction between the hydrogel layer and the tested surface. Such a hydrogel layer is very thin (microscale), and can retain its self-adaptive adhesion even with deformation of the tested surface. When it is applied on the surface of an active frog heart, the weak heartbeats can be transduced to electrical signals. Moreover, this self-adaptive adhesion can work on both soft and hard surfaces including biological tissues, metals, rubbers, ceramics, and glass. Therefore, this in situ permeation method enables the hydrogel layer to detect weak dynamic changes on various soft and hard surfaces, which might offer a new pathway for physiological signal monitoring.

8.
ACS Appl Mater Interfaces ; 14(2): 3591-3600, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-34986636

RESUMO

Information camouflage and decryption on hydrogels rely on chemical stimuli such as pH, ultraviolet light, and chemical reactions, in which the cyclability is limited. This work develops a simpler yet effective physical method that can achieve the information camouflage on hydrogels by water swelling and decrypt it under white light. The information camouflage and decryption can proceed with unlimited cycles. To successfully reach the information camouflage, the hydrogel is synthesized with the water swelling ratio in weight as high as 250, which is enabled by the strong electrostatic repulsion of cationic moieties inside the network. At such a high water-swollen state, the hydrogel is still robust and elastic, which provides a mechanical basis to maintain the stability of the camouflaged information. We write information on the hydrogel surface by laser cutting. Upon immersing the hydrogel in water, the high swelling results in huge expansion of the hydrogel, thus inducing the information camouflage. With exposure to white light, the information can be decrypted and becomes visible again. Our protocol utilizes a simple physical process to enable the camouflage and decryption of complex information, which might open an alternative pathway for the development of hydrogel materials in the application of informatics.

9.
Chem Commun (Camb) ; 58(82): 11555-11558, 2022 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-36165048

RESUMO

A novel and versatile method for peri-C-H selenylation of aromatic compounds bearing ketone groups, including chromones, xanthones, acridinones, quinolinones and naphthoquinones with diselenides under Ru(II) catalysis is presented. Various chromones and diselenides are applicable for this transformation, affording 5-selenyl chromones in a highly regioselective manner in good to excellent yields. This transformation is easy to scale up and the desired products can be further modified. Most importantly, this transformation allows the late-stage selenylation of bioactive compounds. Mechanistic studies show that radicals may be involved in this novel transformation.


Assuntos
Naftoquinonas , Quinolonas , Xantonas , Catálise , Cromonas , Cetonas
10.
Front Mol Biosci ; 7: 603701, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33505988

RESUMO

Background: Lung cancer is one of the most common types of cancer, and it has a poor prognosis. It is urgent to identify prognostic biomarkers to guide therapy. Methods: The immune gene expression profiles for patients with lung adenocarcinomas (LUADs) were obtained from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO). The relationships between the expression of 45 immune checkpoint genes (ICGs) and prognosis were analyzed. Additionally, the correlations between the expression of 45 biomarkers and immunotherapy biomarkers, including tumor mutation burden (TMB), mismatch repair defects, neoantigens, and others, were identified. Ultimately, prognostic ICGs were combined to determine immune subgroups, and the prognostic differences between these subgroups were identified in LUAD. Results: A total of 11 and nine ICGs closely related to prognosis were obtained from the GEO and TCGA databases, respectively. CD200R1 expression had a significant negative correlation with TMB and neoantigens. CD200R1 showed a significant positive correlation with CD8A, CD68, and GZMB, indicating that it may cause the disordered expression of adaptive immune resistance pathway genes. Multivariable Cox regression was used to construct a signature composed of four prognostic ICGs (IDO1, CD274, CTLA4, and CD200R1): Risk Score = -0.002* IDO1+0.031* CD274-0.069* CTLA4-0.517* CD200R1. The median Risk Score was used to classify the samples for the high- and low-risk groups. We observed significant differences between groups in the training, testing, and external validation cohorts. Conclusion: Our research provides a method of integrating ICG expression profiles and clinical prognosis information to predict lung cancer prognosis, which will provide a unique reference for gene immunotherapy for LUAD.

11.
Chem Sci ; 11(15): 3852-3861, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-34122853

RESUMO

The development of catalyst-controlled stereodivergent asymmetric catalysis is important for providing facile access to all stereoisomers of chiral products with multiple stereocenters from the same starting materials. Despite progress, new design strategies for diastereodivergent asymmetric catalysis are still highly desirable. Here we report the potency of H-bond donors as the governing factor to tune diastereoselectivity in a highly diastereoselective switchable enantioselective Michael addition of α-azido ketones to nitroolefins. While a newly developed bifunctional tertiary amine, phosphoramide, preferentially afforded syn-adducts, an analogous squaramide catalyst selectively gave anti-adducts. The resulting multifunctional tertiary azides can be converted to spiro-pyrrolidines with four continuous stereocenters in a one-pot operation. Mechanistic studies cast light on the control of diastereoselectivity by H-bond donors. While the squaramide-catalyzed reaction proceeded with a transition state with both squaramide N-H bonds binding to an enolate intermediate, an unprecedented model was proposed for the phosphoramide-mediated reaction wherein an amide N-H bond and an alkylammonium ion formed in situ interact with nitroolefins, with the enolate stabilized by nonclassical C-H⋯O hydrogen-bonding interactions.

12.
Nat Commun ; 11(1): 5500, 2020 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-33127898

RESUMO

Alkene hydrodifluoroalkylation is a fruitful strategy for synthesizing difluoromethylated compounds that are interesting for developing new medicinal agents, agrochemicals, and advanced materials. Whereas the anti-Markovnikov hydrodifluoroalkylation to linear-type products is developed, employing radical-based processes, the Markovnikov synthesis of branched adducts remains unexplored. Herein, we describe acid-catalyzed processes involving carbocation intermediates as a promising strategy to secure the Markovnikov regioselectivity. Accordingly, the Markovnikov hydrodifluoroalkylation of mono-, di-, tri-, and tetrasubstituted alkenes using difluoroenoxysilanes, catalyzed by Mg(ClO4)2·6H2O, is achieved. This allows the diversity-oriented synthesis of α,α-difluoroketones with a quaternary or tertiary carbon at the ß-position that are otherwise difficult to access. The method is applied to the modification of natural products and drug derivatives. The resulting α,α-difluorinated ketones could be converted to the corresponding α,α-difluorinated esters or alcohols, or organofluorine compounds featuring a CF2H or CF2CF2Ph moiety. Mechanistic studies support that Mg(ClO4)2·6H2O functions as a hidden Brønsted acid catalyst.

13.
Org Lett ; 22(5): 2099-2104, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32105089

RESUMO

We report that phosphorane can activate (salen)TiCl2 complex to achieve unprecedented excellent enantioselectivity and a broad substrate scope in the cyanation of nitroolefins. Our cyanating reagent Me2(CH2Cl)SiCN proves to be more active than TMSCN in this reaction, allowing 11 ß-aliphatic nitrolefins and 12 ß-CF3 nitroolefins (either ß-aryl or aliphatic) to work well to give the corresponding tertiary or quaternary ß-nitronitriles with high to excellent enantioselectivity.

14.
J Neurosurg Anesthesiol ; 32(4): 359-366, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31107683

RESUMO

BACKGROUND: Ketamine, a commonly used nonbarbiturate anesthetic drug, possesses antidepressant properties at subanesthetic doses; however, the underlying mechanisms remain unclear. MATERIALS AND METHODS: The analgesic and antidepressant effects of ketamine were explored using a complete Freund adjuvant (CFA)-induced peripheral inflammatory pain model in vivo. Mice were first divided into sham or CFA injection group randomly, and were observed for mechanical hyperalgesia, depression-like behavior, and mRNA expression of caveolin-1. Then ketamine was administered in CFA-treated mice at day 7. RESULTS: The behavioral testing results revealed mechanical hyperalgesia and depression in mice from days 7 to 21 after CFA injection. Ketamine reversed depression-like behaviors induced by CFA injection. It also restored the brain-regional expression levels of caveolin-1 in CFA-treated mice. In addition, caveolin-1 mRNA and protein expression were increased in the prefrontal cortex and nucleus accumbens of CFA-treated mice. However, ketamine reversed the increase in caveolin-1 expression in the ipsilateral and contralateral prefrontal cortex and nucleus accumbens, supporting the distinct roles of specific brain regions in the regulation of pain and depression-like behaviors. CONCLUSIONS: In CFA-treated mice that exhibited pain behavior and depression-like behavior, ketamine reversed depression-like behavior. The prefrontal cortex and nucleus accumbens are the important brain regions in this regulation network. Despite these findings, other molecules and their mechanisms in the signal pathway, as well as other regions of the brain in the pain matrix, require further exploration.


Assuntos
Analgésicos/farmacologia , Comportamento Animal/efeitos dos fármacos , Caveolina 1/sangue , Depressão/prevenção & controle , Hiperalgesia/prevenção & controle , Ketamina/farmacologia , Analgésicos/sangue , Animais , Caveolina 1/efeitos dos fármacos , Depressão/sangue , Modelos Animais de Doenças , Adjuvante de Freund , Ketamina/sangue , Camundongos
15.
RSC Adv ; 9(30): 16967-16976, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-35519875

RESUMO

Curing malignant carcinomas is a grand ambition in the development of human health. Over the past decades, targeted therapies have become one of the most successful ways of achieving this. Of these approaches, small molecule inhibitors and monoclonal antibodies are two major methods, however several barriers to their development and clinical use still exist. The use of proteolysis-targeting chimeras (PROTACs) is a new technology through utilizing a intracellular ubiquitin-proteasome system to induce targeted protein degradation, is receiving much attention in the field of targeted therapies. Hetero-bifunctional PROTACs have the potential to eliminate the "undruggable" proteome that comprises about 85% of human proteins, which indicates their great prospects in therapeutic fields. However, there are some hurdles preventing current PROTACs moving from bench to clinic, such as delivery and bioavailability. This review provides an overview of the development of PROTAC technology and will briefly summarize the future possible directions of this approach.

16.
ACS Macro Lett ; 8(12): 1588-1593, 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-35619394

RESUMO

Regulating the conductivity of conducting polymers has spurred increasing studies, aiming at meeting different demands in various fields, including chemosensors, photovoltaic cells, and so on. Herein, linear pillar[5]arene-containing conjugated polymers were designed and synthesized via metathesis cyclopolymerization of pillar[5]arene-functionalized 1,6-heptadiyne. Upon addition of an ionic guest, such polymers could form inclusion complexes, of which the glass transition temperature decreased dramatically. With the aid of ionic guest and host-guest complexations between the pendant pillararenes and guest, these supramolecular materials exhibited tunable conductivity from 10-12 to 10-3 S·cm-1 at 30 °C. In addition, compared with the polymers without pendant pillar[5]arenes, such polymers showed better compatibility with the ionic guest, which could prevent the leakage of the latter one and was good for the conductivity of the material.

17.
ACS Appl Mater Interfaces ; 11(20): 18746-18754, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31038302

RESUMO

Hollow hydrogel tubes that are capable of maintaining their flexibility and structural stability in extreme temperature conditions have potential for use in biomedical scaffolds, carriers, and soft robotics over a wide temperature range. However, the preparation of hollow hydrogel tubes still remains challenging because it normally requires templates or complex devices and it is hard to endow the hollow tubes with antifreezing heat-resistant capabilities. We report a protocol that does not require a template or complex devices, in which sodium alginate film strips are immersed in an aqueous mixture of CaCO3, CaCl2, NaHCO3, and HCl, which results in the manufacture of hollow tubes in 30 min. These hollow tubes are functionalized by glycerol and poly(ethylene glycol), which provides the tubes with antifreezing heat-resistant performances and enables them to keep their flexibility and hollow structures from -70 to 120 °C. This is the first report on antifreezing heat-resistant hollow hydrogel tubes, to the best of our knowledge. Such hollow tubes as carriers can control the sublimation of a mothball at a rate of 1.1 mg/h, which is one-tenth of the sublimating rate of an unloaded mothball. This sublimating rate reduces the hazard to environments along with maintaining the repellent effects. As the tube is a honey carrier, it enables the sustainable release of the honey over 800 min with a high efficacy for tricking and capturing ants. The simple applications demonstrate that the antifreezing heat-resistant hollow tubes might be feasible as carriers for the controlled release in extremely cold/hot environments.

18.
ACS Appl Mater Interfaces ; 11(14): 13491-13498, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30880387

RESUMO

The fast evolution of metal halide perovskite solar cells has opened a new chapter in the field of renewable energy. High-quality perovskite films as the active layers are essential for both high efficiency and long-term stability. Here, the perovskite films with enlarged crystal grain size and decreased defect density are fabricated by introducing the extremely low-cost and green polymer, ethyl cellulose (EC), into the perovskite layer. The addition of EC triggers hydrogen bonding interactions between EC and the perovskite, passivating the charge defect traps at the grain boundaries. The long chain of EC further acts as a scaffold for the perovskite structure, eliminating the annealing-induced lattice strain during the film fabrication process. The resulting devices with the EC additive exhibit a remarkably enhanced average power conversion efficiency from 17.11 to 19.27% and an improvement of all device parameters. The hysteresis index is found to decrease by three times from 0.081 to 0.027, which is attributed to suppressed ion migration and surface charge trapping. In addition, the defect passivation by EC significantly improves the environmental stability of the perovskite films, yielding devices that retain 80% of their initial efficiency after 30 days in ambient air at 45% relative humidity, whereas the pristine devices without EC fully degrade. This work provides a low-cost and green avenue for passivating defects that improves both the efficiency and operational stability of perovskite solar cells.

19.
Chin Med J (Engl) ; 121(10): 932-8, 2008 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-18706209

RESUMO

BACKGROUND: Right ventricular function plays an important role in the hemodynamic derangement during off-pump coronary artery bypass (OPCAB) surgery. Pressure-volume loops have been shown to provide load-independent information of cardiac function. Therefore, the aim of this study was to investigate the feasibility of construction of right ventricular pressure-volume loops with pressure and volume data measured by a volumetric pulmonary artery catheter (PAC) and to evaluate right ventricular systolic and diastolic function by end-systolic elastance (E(ES)) and end-diastolic stiffness (E(ED)) in OPCAB surgery. METHODS: Twenty-eight patients who underwent OPCAB surgery were included. After anesthesia induction, a volumetric PAC was placed via the right internal jugular vein. Data were recorded at: anesthesia steady-state before skin incision (T1); 5 minutes after the stabilizer device was placed for anastomosis on the heart's anterior wall (T2), lateral wall (T3), posterior wall (T4), respectively; after sternal closure (T5). Three sets of data were collected at each time point: first, hemodynamic variables were measured; second, right ventricular E(ES) and E(ED) were calculated; third, right ventricular pressure-volume loops were constructed with pressure and volume data measured from end-diastole point, end-isovolumic systole point, peak-ejection point, end-systole point and end-isovolumic diastole point. RESULTS: Right ventricular pressure-volume loops generally shifted to the left during OPCAB surgery. Especially, the end-diastolic point shifted upward and to the left at T2-T5 compared with that at T1. Decrease in right ventricular ejection fraction, stroke volume index and end-diastolic volume index occurred (P < 0.05) at T4 compared with values at T1. Pulmonary vascular resistance index at T4 increased relatively compared with that at T2 and T3. The change of E(ES) was not statistically significant during operation. Right atrial pressure increased only during coronary anastomoses (T2-T4, P < 0.05), whereas E(ED) increased throughout OPCAB surgery (P < 0.05). CONCLUSIONS: Right ventricular pressure-volume loops can be constructed using a volumetric PAC. Right ventricular systolic dysfunction occurred during anastomoses on the heart's posterior wall not due to impaired myocardial contractility but as a result of reduced preload and a relative increase in afterload. Right ventricular diastolic function was impaired throughout OPCAB surgery.


Assuntos
Ponte de Artéria Coronária sem Circulação Extracorpórea/métodos , Função Ventricular Direita/fisiologia , Idoso , Pressão Sanguínea , Feminino , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade
20.
Chem Commun (Camb) ; 51(83): 15320-3, 2015 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-26340600

RESUMO

A new type of insulating-conductive block copolymer was synthesized by metathesis polymerization. The copolymer can self-assemble into unique nanostructures of micelles or hollow spheres. It exhibits a high dielectric constant, low dielectric loss, and high stored/released energy density due to the strong dipolar and nano-interfacial polarization contributions.

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