Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Int J Biol Macromol ; 256(Pt 2): 128233, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38040166

RESUMO

In this work, we report an environmentally friendly renewable nanocomposite magnetic lignin-based palladium nanoparticles (Fe3O4-lignin@Pd-NPs) for efficient wastewater treatment by decorating palladium nanoparticles without using any toxic reducing agents on the magnetic lignin abstracted from Poplar. The structure of composite Fe3O4-lignin@Pd-NPs was unambiguously confirmed by XRD, SEM, TEM, EDS, FTIR, and Zeta potential. After systematic evaluation of the use and efficiency of the composite to remove toxic organic dyes in wastewater, some promising results were observed as follows: Fe3O4-lignin@Pd-NPs exhibits highly active and efficient performance in the removal of toxic methylene blue (MB) (up to 99.8 %) wastewater in 2 min at different concentrations of MB and different pH values. Moreover, except for toxic MB, the other organic dyes including Rhodamine B (RhB), Rhodamine 6G (Rh6G), and Methyl Orange (MO) can also be removed efficiently by the composite. Finally, the easily recovered composite Fe3O4-lignin@Pd-NPs exhibits well stability and reusability, and catalytic efficiency is maintained well after ten cycles. In conclusion, the lignin-based magnetism Pd composite exhibits powerful potential practical application in industrial wastewater treatment.


Assuntos
Nanopartículas Metálicas , Nanocompostos , Purificação da Água , Lignina , Nanopartículas Metálicas/química , Paládio/química , Águas Residuárias , Corantes
2.
ACS Appl Mater Interfaces ; 14(49): 54885-54894, 2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36459636

RESUMO

Regulation of the exciton generation, diffusion, and carrier transport, as well as optimization of the non-radiative energy loss could further overcome the power conversion efficiency limitation of organic solar cells. However, the relationship between exciton properties and non-radiative energy loss has seldom been investigated. Herein, taking D18-series devices as the research model, the exciton diffusion length (LD) and hole transfer dynamics can be remarkably improved by the variation of electron-withdrawing halogen and the non-radiative energy loss simultaneously can be suppressed. By combining the analysis results of hole transfer, exciton diffusion, charge separation, and recombination, this work demonstrates that the photo-induced exciton in the chlorinated polymer donor can diffuse to a longer distance within the effective exciton lifetime, suppress the exciton recombination, and enhance device performance. The results define the relationship between the exciton behaviors and non-radiative energy loss and further reveal the significance of controlling the bulk heterojunction with superior photo-physical properties.

3.
Org Lett ; 24(45): 8283-8288, 2022 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-36331137

RESUMO

In this work, we successfully explored an unexpected dehydrogenation triggered by Pd/Cu-catalyzed C(sp3)-H arylation and intramolecular C-N coupling of amides to synthesize the bioactive 1,2-dihydroquinoline scaffold with good regioselectivity and good compatibility of functional groups. This strategy provides an alternative route to realize molecular complexity and diversity from simple and readily available molecules via multiple C-H bond activation. Preliminary mechanistic studies demonstrated that ß,γ-dehydrogenation is triggered by the arylation of the C(sp3)-H bond and the intramolecular C-N coupling.


Assuntos
Amidas , Paládio , Amidas/química , Paládio/química , Catálise , Estrutura Molecular
4.
Chem Sci ; 13(34): 9914-9920, 2022 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-36128249

RESUMO

Singlet exciton fission (SF) is believed to have the potential to break the Shockley-Queisser limit for third-generation solar cell devices, so it has attracted great attention. Conventional linear acene based SF materials generally suffer from low triplet energy and poor photostability. We report herein two flavanthrene derivatives, EH-Fla and TIPS-Fla, as new photostable singlet exciton fission materials. These N-doped two-dimensional angular fused acenes have three sets of aromatic Clar sextets, making them significantly more stable than linear acenes with only one sextet. Time-resolved spectroscopy characterization reveals that the SF process occurs in the polycrystalline films of EH-Fla and TIPS-Fla, with maximal triplet yields of 32% and 159%, respectively. The SF processes of these two molecules are mediated by excimer states. In EH-Fla, the low-lying excimer prevents the SF process from occurring effectively, resulting in a low triplet yield. In contrast, the excimer state in TIPS-Fla is mixed with strong CT coupling, which prompts efficient SF and results in a high triplet yield. Our results show that flavanthrene is a promising SF chromophore for photoenergy conversion applications, while a fine-tune of the intermolecular interaction is crucial for achieving high SF efficiency.

5.
Eur Radiol ; 32(1): 205-212, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34223954

RESUMO

OBJECTIVES: Early recognition of coronavirus disease 2019 (COVID-19) severity can guide patient management. However, it is challenging to predict when COVID-19 patients will progress to critical illness. This study aimed to develop an artificial intelligence system to predict future deterioration to critical illness in COVID-19 patients. METHODS: An artificial intelligence (AI) system in a time-to-event analysis framework was developed to integrate chest CT and clinical data for risk prediction of future deterioration to critical illness in patients with COVID-19. RESULTS: A multi-institutional international cohort of 1,051 patients with RT-PCR confirmed COVID-19 and chest CT was included in this study. Of them, 282 patients developed critical illness, which was defined as requiring ICU admission and/or mechanical ventilation and/or reaching death during their hospital stay. The AI system achieved a C-index of 0.80 for predicting individual COVID-19 patients' to critical illness. The AI system successfully stratified the patients into high-risk and low-risk groups with distinct progression risks (p < 0.0001). CONCLUSIONS: Using CT imaging and clinical data, the AI system successfully predicted time to critical illness for individual patients and identified patients with high risk. AI has the potential to accurately triage patients and facilitate personalized treatment. KEY POINT: • AI system can predict time to critical illness for patients with COVID-19 by using CT imaging and clinical data.


Assuntos
COVID-19 , Inteligência Artificial , Humanos , Estudos Retrospectivos , SARS-CoV-2 , Tomografia Computadorizada por Raios X
6.
Nanoscale Horiz ; 6(11): 918-927, 2021 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-34490855

RESUMO

Low dimensional tellurium is currently of great interest for potential electronic applications due to the experimentally observed Weyl fermions and the excellent carrier mobility, on/off ratios and current-carrying capacity in devices. However, the optical properties of Te nanostructures are not well explored, especially in the field of nonlinear optics. Here, we prepared a series of Te nanostructures by electrochemical exfoliation and liquid phase exfoliation methods, including one-dimensional (1D) Te nanowires (NWs), quasi-1D Te nanorods (NRs), zero-dimensional (0D) Te nanodots (NDs) and two-dimensional (2D) Te nanosheets (NSs). Femtosecond Z-scan measurements reveal unique dimension-dependent nonlinear optical (NLO) properties. 1D Te NWs and quasi-1D Te NRs exhibited higher saturable absorption behavior than 0D Te nanostructures, while the 2D Te NSs are a high performance optical limiting material. Ultrafast transient absorption spectroscopy revealed the dimension-dependent exciton dynamics. The reverse saturable absorption of 2D Te NSs is derived from faster exciton relaxation and stronger excited state absorption. This work paves the way for the design of saturable absorbers with high performance and broadens the application of 2D Te in the field of laser protection and other novel ultrafast photonics.

8.
Nanoscale Horiz ; 5(10): 1420-1429, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32856666

RESUMO

Sb nanosheets, also known as antimonene, have received ever-growing consideration as a promising new type of two-dimensional (2D) material due to their many attractive properties. However, how their nonlinear optical (NLO) properties are affected by their nanosheet structure and measurement conditions remains unclear. Herein, we report a successful size-selective production method for Sb nanosheets, which is based on a combination of lithium ion intercalation, solvent exfoliation and size selection centrifugation. This high-yield and size-selective preparation method enables fundamental investigation on the relation of the intrinsic optical properties of Sb nanosheets. Nanosecond Z-scan measurements revealed a unique size-dependent broadband NLO response. When the average size is reduced from 3 micrometers to 50 nanometers, the Sb nanosheets exhibit a clear transition from saturable absorption to reversed saturable absorption. Ultrafast transient absorption spectroscopic investigation indicated that exciton cooling is significantly faster in a small nanosheet than in large ones, revealing that the different exciton relaxation dynamic plays key roles in the distinct size-tunable nonlinear optical response. This work paves new ways towards the mass production and practical application of antimonene.

9.
Radiology ; 296(3): E156-E165, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32339081

RESUMO

Background Coronavirus disease 2019 (COVID-19) and pneumonia of other diseases share similar CT characteristics, which contributes to the challenges in differentiating them with high accuracy. Purpose To establish and evaluate an artificial intelligence (AI) system for differentiating COVID-19 and other pneumonia at chest CT and assessing radiologist performance without and with AI assistance. Materials and Methods A total of 521 patients with positive reverse transcription polymerase chain reaction results for COVID-19 and abnormal chest CT findings were retrospectively identified from 10 hospitals from January 2020 to April 2020. A total of 665 patients with non-COVID-19 pneumonia and definite evidence of pneumonia at chest CT were retrospectively selected from three hospitals between 2017 and 2019. To classify COVID-19 versus other pneumonia for each patient, abnormal CT slices were input into the EfficientNet B4 deep neural network architecture after lung segmentation, followed by a two-layer fully connected neural network to pool slices together. The final cohort of 1186 patients (132 583 CT slices) was divided into training, validation, and test sets in a 7:2:1 and equal ratio. Independent testing was performed by evaluating model performance in separate hospitals. Studies were blindly reviewed by six radiologists without and then with AI assistance. Results The final model achieved a test accuracy of 96% (95% confidence interval [CI]: 90%, 98%), a sensitivity of 95% (95% CI: 83%, 100%), and a specificity of 96% (95% CI: 88%, 99%) with area under the receiver operating characteristic curve of 0.95 and area under the precision-recall curve of 0.90. On independent testing, this model achieved an accuracy of 87% (95% CI: 82%, 90%), a sensitivity of 89% (95% CI: 81%, 94%), and a specificity of 86% (95% CI: 80%, 90%) with area under the receiver operating characteristic curve of 0.90 and area under the precision-recall curve of 0.87. Assisted by the probabilities of the model, the radiologists achieved a higher average test accuracy (90% vs 85%, Δ = 5, P < .001), sensitivity (88% vs 79%, Δ = 9, P < .001), and specificity (91% vs 88%, Δ = 3, P = .001). Conclusion Artificial intelligence assistance improved radiologists' performance in distinguishing coronavirus disease 2019 pneumonia from non-coronavirus disease 2019 pneumonia at chest CT. © RSNA, 2020 Online supplemental material is available for this article.


Assuntos
Inteligência Artificial , Infecções por Coronavirus/diagnóstico por imagem , Pneumonia Viral/diagnóstico por imagem , Radiologistas , Tomografia Computadorizada por Raios X/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Betacoronavirus , COVID-19 , Criança , Pré-Escolar , China , Diagnóstico Diferencial , Feminino , Humanos , Lactente , Recém-Nascido , Pulmão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Pandemias , Philadelphia , Pneumonia/diagnóstico por imagem , Radiografia Torácica , Radiologistas/normas , Radiologistas/estatística & dados numéricos , Estudos Retrospectivos , Rhode Island , SARS-CoV-2 , Sensibilidade e Especificidade , Adulto Jovem
10.
Org Lett ; 21(6): 1668-1671, 2019 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-30801191

RESUMO

In this letter, we successfully explored a cascade Pd/Cu-catalyzed intermolecular C(sp3)-H arylation of amides and intramolecular C-N coupling reaction. This method provides a one-pot strategy to synthesize 3,4-2 H-quinolinone with good regioselectivity of C-H arylation and C-N coupling from C-I and C-X bonds from readily available starting materials.

11.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-777961

RESUMO

Objective To investigate the characteristics of sleep patterns and their effects on the risk of diabetes mellitus (DM) among adults in Guangzhou. Methods A retrospective study was conducted using data collected by the lifestyle survey and health outcomes of 5 666 employees from Guangzhou who underwent physical examination between November 2012 and October 2013 at Guangdong Provincial People's Hospital. Sleep patterns and their distribution profiles were analysed using latent class analysis (LCA). Multiple logistic regression models were performed to investigate the association between sleep patterns and DM. Results LCA identified five sleep patterns: “very short sleep duration with insomnia” (class 1, 5.6%), “sleep insufficiency with mild daytime dysfunction” (class 2, 20.4%), “normal sleep” (class 3, 47.7%), “sleep insufficiency with daytime functioning complaints” (class 4, 4.7%) and “sleep insufficiency with poor nocturnal sleep” (class 5, 21.6%). After adjustment for the confounding factors, subjects of class 1 (OR=2.28, 95% CI: 1.51-3.43, <0.001), class 4 (OR=2.48, 95% CI: 1.54-4.00, P<0.001) and class 5 (OR=1.31, 95% CI: 1.01-1.71, P=0.045) had a higher risk of DM when compared with those of class 3. Conclusions There were significant associations between various sleep-related factors, leading to distinct sleep behavioral patterns among adults. Poor sleep patterns could increase the risk of DM.

12.
World J Gastroenterol ; 22(22): 5201-10, 2016 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-27298563

RESUMO

AIM: To explore the preventive and therapeutic effects of Faecalibacterium prausnitzii (F. prausnitzii) supernatant on dextran sulfate sodium (DSS) induced colitis in mice. METHODS: Forty C57BL/6J male mice were randomly divided into four groups: control group, model group, treatment group, and prevention group. Mice were weighed daily. On day 10, the colon length was measured, the colorectal histopathologic damage score (HDS) was assessed, and plasma interleukin (IL)-17A, IL-6, and IL-4 levels were detected by enzyme-linked immunosorbent assay. The expression of transcription factor retinoic acid-related orphan receptor-γt (RORγt) and IL-17A in colon inflammatory mucosa tissue were determined by immunohistochemical assay, and the expression levels of RORγt mRNA, IL-17A mRNA, and IL-6 mRNA were detected by real-time quantitative polymerase chain reaction (PCR). The proportion of Th17 in mononuclear cells in spleen was assayed by fluorescence activated cell sorter. RESULTS: When compared with the model group, the colon length (P < 0.05) and body weight (P < 0.01) in the treatment and prevention groups were significantly increased, and the colon HDS was decreased (P < 0.05 and P < 0.01). There was no statistical difference between the treatment group and prevention group. After treatment with F. prausnitzii supernatant, the plasma levels of IL-17A and IL-6 (P < 0.05), the protein and mRNA expression of IL-17A and RORγt, and the Th17 cell ratio of spleen cells (P < 0.01) were significantly decreased compared to the model group. Plasma IL-4 level in the prevention group was significantly higher than that in the model group (P < 0.05), but there was no significant difference between these two groups in the expression of IL-6 in both the plasma and colon mucosa tissues. CONCLUSION: F. prausnitzii supernatant exerts protective and therapeutic effects on DSS-induced colitis in mice, probably via inhibition of Th17 differentiation and IL-17A secretion in the plasma and colon mucosa tissues. It can also improve colitis in mice by downregulating IL-6 and prevent colitis by upregulating IL-4.


Assuntos
Anti-Inflamatórios/farmacologia , Colite/prevenção & controle , Colo/efeitos dos fármacos , Suplementos Nutricionais , Faecalibacterium prausnitzii/metabolismo , Fármacos Gastrointestinais/farmacologia , Células Th17/efeitos dos fármacos , Animais , Colite/sangue , Colite/induzido quimicamente , Colite/imunologia , Colo/imunologia , Colo/metabolismo , Colo/patologia , Sulfato de Dextrana , Mediadores da Inflamação/sangue , Interleucina-17/sangue , Interleucina-17/genética , Interleucina-4/sangue , Interleucina-6/sangue , Interleucina-6/genética , Masculino , Camundongos Endogâmicos C57BL , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Células Th17/imunologia , Células Th17/metabolismo , Fatores de Tempo
13.
Org Lett ; 18(9): 2040-3, 2016 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-27074521

RESUMO

In this letter, we report an efficient and concise protocol for Cu-catalyzed cross-coupling of unactivated alkyl halides/peusudohalides with terminal alkynes to afford internal alkynes with the assistance of various amides as directing groups. Different alkyl halides/pseudohalides exhibited excellent reactivities, and the inactivated alkyl chlorides and sulfonates showed better reactivity than bromides/iodides. This is the first successful example to apply alkyl chlorides and sulfonates directly in cross-coupling with terminal alkynes in the absence of any additives. A Cu catalyst was found to be more effective than other transition metal catalysts. This reaction also exhibited a broad substrate scope with respect to terminal alkynes.

14.
J Am Chem Soc ; 137(46): 14586-9, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26523735

RESUMO

Selective cleavage of an inert C-C bond followed by C-O/N bond formation through a long-distance aryl migration from a carbon to a nitrogen center via Ag catalysis is reported. The migration products were easily converted into γ-hydroxy amines and tetrahydroquinoline derivatives in quantitative yields. Preliminary mechanistic studies indicated a radical pathway.

15.
Angew Chem Int Ed Engl ; 54(18): 5478-82, 2015 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-25757707

RESUMO

A rhodium(III)-catalyzed cross-coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (CH, CS, OH) and the formation of two bonds (CC, CO). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double CH activation, the first of such examples in cross-oxidative coupling.

16.
Angew Chem Int Ed Engl ; 52(40): 10598-601, 2013 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-23940082

RESUMO

Dibenzopyranones were synthesized by a palladium-catalyzed phenol-directed C-H activation/carbonylation of 2-phenylphenol derivatives in the presence of CO. Pd(OAc)2 was used as a catalyst and Cu(OAc)2 as a catalytic oxidant in the presence of air.


Assuntos
Benzopiranos/síntese química , Paládio/química , Fenol/química , Benzopiranos/química , Catálise , Estrutura Molecular , Carbonilação Proteica , Estereoisomerismo
17.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-315002

RESUMO

This study aims to explore HIV traditional Chinese medicine (TCM) syndrome distribution and TCM syndrome evolution. The 485 cases of HIV/AIDS patients from 10 major regions of the AIDS epidemic in HIV. In this study, the interpretation of experts to explore the TCM syndromes in different routes of infection, different stage of disease, with syndrome distribution under different interventions. The results showed that Yang deficiency of spleen and kidney and liver Qi stagnation is the most common type in the patients who with sexually transmitted infections. TCM syndrome type most commonly seen in patients infected by the blood collection is yang deficiency of spleen and kidney and spleen deficiency wet-sheng. Including Yang deficiency of spleen and kidney with the highest frequency in patients with AIDS, people who with sexually transmitted infections and patients that treated with simple HAART were prone to liver-stagnation and spleen-deficiency syndrome. In short, such as Yang deficiency of spleen and kidney, liver Qi stagnation, deficiency of both Qi and Yin, deficiency-weakness of spleen-Qi, syndrome of damt-heat ftagnation were the main AIDS syndrome types.


Assuntos
Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Síndrome da Imunodeficiência Adquirida , Diagnóstico , Seguimentos , Medicina Tradicional Chinesa
18.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-314987

RESUMO

This article reviews the research reports of Chinese herbal compound on AIDS immune reconstitution for nearly 20 years, found that Chinese herbal compound has exact clinical efficacy for AIDS immune reconstitution. Therefore, we should give full play to the unique advantages of Chinese herbal compound in improving immunity, thus improving symptoms and improve quality of life, to achieve optimal clinical treatment of AIDS.


Assuntos
Animais , Humanos , Química Farmacêutica , Ensaios Clínicos como Assunto , Medicamentos de Ervas Chinesas , Química , Farmacologia , Usos Terapêuticos , Infecções por HIV , Tratamento Farmacológico , Alergia e Imunologia
19.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-314985

RESUMO

Highly active antiretroviral therapy (HAART) for the treatment of HIV infection had a revolutionary impact, with the universal application of the anti-retroviral drugs, HAART-related adverse reactions have attracted more and more attention. HAART-related hyperlipidemia is one of the common adverse reactions with more and more scholars study the pathogenesis and therapy of hyperlipidemia in recent years. This article elaborated the latest research of Chinese medicine treatment of HAART-related hyperlipidemia.


Assuntos
Animais , Humanos , Terapia Antirretroviral de Alta Atividade , Química Farmacêutica , Hiperlipidemias , Terapêutica , Medicina Tradicional Chinesa , Métodos
20.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-314982

RESUMO

Highly active antiretroviral combination therapy significantly reduced the mortality, but in the high-speed copying, high genetic variation and drug selection pressure under the effect of the increasingly serious problem of drug resistance greatly weakened the role of HAART inhibit viral replication and reduce antiviral treatment. This paper reports the latest trends in HIV drug-resistance in order to develop anti-HIV drugs in clinical programs, research and development of new guidance anti-HIV-1 strategy to bring guidance.


Assuntos
Humanos , Fármacos Anti-HIV , Farmacologia , Descoberta de Drogas , Farmacorresistência Viral , HIV , Internacionalidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...