Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
1.
Macromol Rapid Commun ; 45(6): e2300613, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38157222

RESUMO

Hydrogels are ideal materials for flexible electronic devices based on their smooth ion channels and considerable mechanical flexibility. A substantial volume of aqueous solution is required to enable the smooth flow of ions, resulting in the agony of low-temperature freezing; besides, long-term exposure to bending/tensile tress triggers fatigue issues. Therefore, it is a great challenge to prepare hydrogels with both freeze-resistance and long-term durability. Herein, a polyacrylic acid-based hydrogel with both hydrophobic interaction and dynamic reversible covalent bonding cross-linking networks is preparing (DC-hydrogel) by polymerizing a bi-functional imidazole-type ionic liquid monomer with integrated disulfide and alkene bonds (DS/DB-IL) and an octadecyl methacrylate, achieving self-healing. The DS/DB-IL anchored into the polymer backbone has a high affinity with water, reducing the freezing point of water, while the DS/DB-IL with free ions provides superior ionic conductivity to the DC-hydrogel. The polyacrylic acid with abundant carboxyl gives hydrogel good self-adhesiveness to different substrates. Ionotronics with resistance-type sensors with stable output performance are fabricated and explored its application to joint motion and health information. Moreover, hydrogel-based sensing arrays with high resolution and accuracy are fabricated to identify 2D distribution of stress. The hydrogels have great promise for various ionotronics in many fields.


Assuntos
Alcenos , Hidrogéis , Dissulfetos , Condutividade Elétrica , Água
2.
Molecules ; 29(11)2024 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-38893322

RESUMO

The Mediterranean diet well known for its beneficial health effects, including mood enhancement, is characterised by the relatively high consumption of extra virgin olive oil (EVOO), which is rich in bioactive phenolic compounds. Over 200 phenolic compounds have been associated with Olea europaea, and of these, only a relatively small fraction have been characterised. Utilising the OliveNetTM library, phenolic compounds were investigated as potential inhibitors of the epigenetic modifier lysine-specific demethylase 1 (LSD1). Furthermore, the compounds were screened for inhibition of the structurally similar monoamine oxidases (MAOs) which are directly implicated in the pathophysiology of depression. Molecular docking highlighted that olive phenolics interact with the active site of LSD1 and MAOs. Protein-peptide docking was also performed to evaluate the interaction of the histone H3 peptide with LSD1, in the presence of ligands bound to the substrate-binding cavity. To validate the in silico studies, the inhibitory activity of phenolic compounds was compared to the clinically approved inhibitor tranylcypromine. Our findings indicate that olive phenolics inhibit LSD1 and the MAOs in vitro. Using a cell culture model system with corticosteroid-stimulated human BJ fibroblast cells, the results demonstrate the attenuation of dexamethasone- and hydrocortisone-induced MAO activity by phenolic compounds. The findings were further corroborated using human embryonic stem cell (hESC)-derived neurons stimulated with all-trans retinoic acid. Overall, the results indicate the inhibition of flavin adenine dinucleotide (FAD)-dependent amine oxidases by olive phenolics. More generally, our findings further support at least a partial mechanism accounting for the antidepressant effects associated with EVOO and the Mediterranean diet.


Assuntos
Simulação de Acoplamento Molecular , Inibidores da Monoaminoxidase , Monoaminoxidase , Olea , Fenóis , Humanos , Inibidores da Monoaminoxidase/farmacologia , Inibidores da Monoaminoxidase/química , Monoaminoxidase/metabolismo , Monoaminoxidase/química , Olea/química , Fenóis/farmacologia , Fenóis/química , Histona Desmetilases/antagonistas & inibidores , Histona Desmetilases/metabolismo , Depressão/tratamento farmacológico , Azeite de Oliva/química , Simulação por Computador
3.
Fa Yi Xue Za Zhi ; 38(5): 579-583, 2022 Oct 25.
Artigo em Inglês, Zh | MEDLINE | ID: mdl-36727172

RESUMO

OBJECTIVES: To study the cooling reaction kinetic characteristics of the temperature difference between cadaver temperature and ambient temperature (hereinafter referred to as "cadaver temperature difference") according to the reaction kinetics method. METHODS: Thirty rabbits were randomly divided into 5 groups with 6 rabbits in each group. The rabbits were injected with 10% potassium chloride solution intravenously. After death, the rabbits were placed at 5 ℃, 10 ℃, 15 ℃, 20 ℃ and 25 ℃ environment condition, respectively, and the rectal temperature was measured every minute for 20 hours. The measured cadaver temperature was subtracted from ambient temperature, and the cadaver temperature difference data was calculated using the reaction kinetics formula. The linear regression equation was fitted for analysis, and the experimental results were applied to the temperature difference data of human body after death for verification. RESULTS: Under different environmental conditions, the linear coefficient determination of temperature difference -ln(C/C0) in rabbits was 0.99, showing a good linear relationship with time t. The application of human body temperature data after death was consistent with the results of animal experiments. CONCLUSIONS: Under stable conditions, the temperature difference cooling process after death in rabbits is a first-order kinetic response. The method can also be used to study the temperature difference in human body after death.


Assuntos
Temperatura Corporal , Animais , Humanos , Coelhos , Temperatura , Cinética , Cadáver
4.
J Am Chem Soc ; 143(26): 9972-9981, 2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34170661

RESUMO

Surface chemistry is a major factor that determines the wettability of materials, and devising broadly applicable coating strategies that afford tunable and selective surface properties required for next-generation materials remains a challenge. Herein, we report fluorinated metal-organic coatings that display water-wetting and oil-repelling characteristics, a wetting phenomenon different from responsive wetting induced by external stimuli. We demonstrate this selective wettability with a library of metal-organic coatings using catechol-based coordination and silanization (both fluorinated and fluorine-free), enabling sensing through interfacial reconfigurations in both gaseous and liquid environments, and establish a correlation between the coating wettability and polarity of the liquids. This selective wetting performance is substrate-independent, spontaneous, durable, and reversible and occurs over a range of polar and nonpolar liquids (60 studied). These results provide insight into advanced liquid-solid interactions and a pathway toward tuning interfacial affinities and realizing robust, selective superwettability according to the surrounding conditions.

5.
Clin Infect Dis ; 71(Suppl 4): S379-S385, 2020 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-33367578

RESUMO

BACKGROUND: Handwashing sinks can become contaminated by carbapenem-resistant Klebsiella (CRK), including carbapenem-resistant Klebsiella pneumoniae (CRKP) and carbapenem-resistant Klebsiella oxytoca (CRKO), but whether they are major sources of CRK infections remains unknown. METHODS: We performed a prospective multicenter study in 16 intensive care units (ICUs) (9 general and 7 neonatal) at 11 hospitals. All sinks at these locations were sampled to screen CRK. All CRK clinical isolates recovered between 2 weeks before and 3 months after sampling in ICUs with CRK-positive sinks or other participating ICUs at the same hospital were collected. Whole-genome sequencing of all isolates was performed. Isolates of the same sequence type (ST) were assigned to clones by calling single-nucleotide polymorphisms. RESULTS: Among 158 sinks sampled, 6 CRKP and 6 CRKO were recovered from 12 sinks in 7 ICUs, corresponding to a 7.6% CRK contamination rate. Twenty-eight clinical isolates were collected, and all were CRKP. The 34 CRKP isolates belonged to 7 STs, including ST789 (n = 14, all had blaNDM-5); ST11 (n = 12, 5 belonged to KL64 and 7 to KL47, all had blaKPC-2); ST709 (n = 4, all had blaNDM-5); and ST16, ST20, ST1027, and ST2407 (n = 1 each). One particular ST789 clone caused an outbreak and contaminated a sink. ST11_KL47 sink isolates were likely the source of a cluster of clinical isolates. Two ST11_KL64 isolates belonged to a common clone but were from 2 hospitals. CONCLUSIONS: Contaminated sinks were not the major source of CRK in our local settings. ST789 blaNDM-5-carrying CRKP might represent an emerging lineage causing neonatal infections.


Assuntos
Carbapenêmicos , Infecções por Klebsiella , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Desinfecção das Mãos , Humanos , Unidades de Terapia Intensiva , Klebsiella , Infecções por Klebsiella/epidemiologia , Infecções por Klebsiella/prevenção & controle , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Estudos Prospectivos , beta-Lactamases
7.
Angew Chem Int Ed Engl ; 55(16): 5028-34, 2016 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-26991543

RESUMO

A novel method for the preparation of transparent Al2O3 coatings of polymers is presented. An environmental-friendly sol-gel method is employed, which implies mild conditions and low costs. A thermoresponsive brush is chosen as a model surface. X-ray photoelectron spectroscopy is used to characterize the samples during the conversion of the precursor Al(OH)3 into oxide and to prove the mildness of the protocol. The study evidences a relation between lateral homogeneity of alumina and the wettability of the polymer surface by the precursor solution, while morphology and elasticity are dominated by the polymer properties. The study of the swelling behavior of the underneath brush reveals the absence of water uptake, proving the impermeability of the alumina layer. The broad chemical and structural variety of polymers, combined with the robustness of transparent alumina films, makes these composites promising as biomedical implants, protective sheets and components for electric and optical devices.

8.
Polymers (Basel) ; 16(4)2024 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-38399919

RESUMO

The emergence of novel e-textile materials that combine the inherent qualities of the textile substrate (lightweight, soft, breathable, durable, etc.) with the functionality of micro/nano-electronic materials (conductive, dielectric, sensing, etc.) has resulted in a trend toward miniaturization, integration, and intelligence in new electronic devices. However, the formation of a conductive network by micro/nano-conductive materials on textiles necessitates high-temperature sintering, which inevitably causes substrate aging and component damage. Herein, a bis-hydroxy-imidazolium chloride salt as a hard segment to synthesize a waterborne polyurethane (WPU) adhesive is designed and prepared. When used in nano-silver-based printing coatings, it offers strong adherence for coatings, reaching 16 N cm-1; on the other hand, the introduction of chloride ions enables low-temperature (60 °C) chemical sintering to address the challenge of secondary treatment and high-temperature sintering (>150 °C). Printed into flexible circuits, the resistivity can be controlled by the content of imidazolium salts anchored in the molecular chain of the WPU from a maximum resistivity of 3.1 × 107 down to 5.8 × 10-5 Ω m, and it can conduct a Bluetooth-type finger pulse detector with such low resistivity. As a flexible circuit, it also offers high stability against washing and adhesion, which the resistivity only reduces less than 20% after washing 10 times and adhesion. Owing to the adjustability of the resistivity, we fabricated an all-textile flexible pressure sensor that accurately differentiates different external pressures (min. 10 g, ~29 Pa), recognizes forms, and detects joint motions (finger bending and wrist flexion).

9.
Dig Dis Sci ; 58(7): 1863-70, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23504349

RESUMO

BACKGROUND: miR-21 is overexpressed in esophageal squamous cell carcinoma (ESCC) and is thought to be correlated with the development of the cancer. The target gene of miR-21 including FASL, TIMP3 and RECK is revealed by researchers. miR-21 may be involved in the tumorgenesis of ESCC by targeting FASL, TIMP3 and RECK. AIMS: The purpose of this study was to explore the mechanism of miR-21 in the development of ESCC. METHODS: miR-21 expression in ESCC and the matched non-malignant adjacent tissues (NMATs) was examined by qRT-PCR. Cell growth, cell apoptosis and cell invasion ability of EC9706 and EC-1 cells was examined after the cells were transfected with miR-21 inhibitor. The potential target genes of miR-21 including FASL, TIMP3 and RECK were examined by western blot and Luciferase reporter assay. RESULTS: miR-21 expression was increased significantly in ESCC tissues compared with NMAT. miR-21 down-regulation inhibits cell growth, cell invasion and induces cells to apoptosis. FASL, TIMP3 and RECK are direct targets of miR-21. CONCLUSIONS: miR-21 down-regulation inhibits cell growth, invasion and induces cells to apoptosis by targeting FASL, TIMP3 and RECK genes.


Assuntos
Biomarcadores Tumorais/metabolismo , Carcinoma de Células Escamosas/metabolismo , Neoplasias Esofágicas/metabolismo , Proteína Ligante Fas/metabolismo , Proteínas Ligadas por GPI/metabolismo , MicroRNAs/metabolismo , Inibidor Tecidual de Metaloproteinase-3/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Apoptose , Western Blotting , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Proliferação de Células , Regulação para Baixo , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/patologia , Carcinoma de Células Escamosas do Esôfago , Feminino , Humanos , Masculino , MicroRNAs/antagonistas & inibidores , Pessoa de Meia-Idade , Invasividade Neoplásica , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Regulação para Cima
10.
J Colloid Interface Sci ; 633: 703-711, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36481425

RESUMO

Photocatalytic nitrogen fixation opens new opportunities for sustainable and healthier futures, and developing effective and inexpensive photocatalysts is the key. We use the ligand 3,3',5,5'-azomellitic acid (H4abtc) to connect with Fe clusters and Zr clusters to form stable metal-organic frameworks (MOFs) Fe-abtc and Zr-abtc, both of which are responsive to visible lights for nitrogen fixation. It is worth noting that the presence of NN in the ligand makes it respond to visible lights. The tetracarboxyl group is connected to the metal cluster to form a stable structure. The field-only surface integral method verified that the ligands were successfully applied into the synthesized MOF particles, which expanded the photoresponse range and enhanced the photonic interactions of the synthesized photocatalysts compared with pure MOF particles. The best photocatalytic nitrogen fixation performance of Fe-abtc and Zr-abtc is 49.8 µmol·g(cat.)-1·h-1 and 35.7 µmol·g(cat.)-1·h-1, respectively, the apparent quantum efficiency (AQY) of the sample Fe-abtc is 0.56 %, and the reliability of the source of N element is proved by the isotope 15N2. This work provides a new idea for the design of cheap and effective MOFs for photocatalytic nitrogen fixation.


Assuntos
Estruturas Metalorgânicas , Luz Solar , Ligantes , Fixação de Nitrogênio , Reprodutibilidade dos Testes
11.
ACS Mater Au ; 2(5): 576-595, 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36855625

RESUMO

The lack of freshwater has been threatening many people who are living in Africa, the Middle East, and Oceania, while the discovery of freshwater harvesting technology is considered a promising solution. Recent advances in structured surface materials, metal-organic frameworks, hygroscopic inorganic compounds (and derivative materials), and functional hydrogels have demonstrated their potential as platform technologies for atmospheric water (i.e., supersaturated fog and unsaturated water) harvesting due to their cheap price, zero second energy requirement, high water capture capacity, and easy installation and operation compared with traditional water harvesting methods, such as long-distance water transportation, seawater desalination, and electrical dew collection devices in rural areas or individual-scale emergent usage. In this contribution, we highlight recent developments in functional materials for "passive" atmospheric water harvesting application, focusing on the structure-property relationship (SPR) to illustrate the transport mechanism of water capture and release. We also discuss technical challenges in the practical applications of the water harvesting materials, including low adaptability in a harsh environment, low capacity under low humidity, self-desorption, and insufficient solar-thermal conversion. Finally, we provide insightful perspectives on the design and fabrication of atmospheric water harvesting materials.

12.
Bioresour Technol ; 320(Pt B): 124393, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33202344

RESUMO

A simple low-temperature partial-oxidation process was demonstrated as an effective technology for reed straw modification towards environmental remediation. At an optimal temperature of 180 °C, the straw materials exhibited a remarkable colour change from light yellow to dark brown, increased methylene blue (MB) uptake by 1.8 times, enhanced removal efficiency from 34.5% to 92.8%, and a high yield of 77.2%. Spectroscopic characterization and Boehm titration proved that the amount of surface oxygen (O)-containing functional groups significantly increased after modification. A strong linear correlation (R2 = 0.93) existed between total amounts of O-containing functional groups and MB uptake for modification temperatures below 180 °C, whereas blockage of the pore entrances and competition with metallic cations must be taken into account for samples generated from excess heating (>180 °C). These results provided insights into designing promising technologies for sustainable environmental management through reutilization of agricultural waste.


Assuntos
Recuperação e Remediação Ambiental , Poluentes Químicos da Água , Adsorção , Agricultura , Azul de Metileno
13.
mSphere ; 5(3)2020 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-32581071

RESUMO

The contamination of patients' surroundings by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains understudied. We sampled the surroundings and the air of six negative-pressure non-intensive care unit (non-ICU) rooms in a designated isolation ward in Chengdu, China, that were occupied by 13 laboratory-confirmed coronavirus disease 2019 (COVID-19) patients who had returned from overseas travel, including 2 asymptomatic patients. A total of 44 of 112 (39.3%) surface samples were positive for SARS-CoV-2 as detected by real-time PCR, suggesting extensive contamination, although all of the air samples were negative. In particular, in a single room occupied by an asymptomatic patient, four sites were SARS-CoV-2 positive, highlighting that asymptomatic COVID-19 patients do contaminate their surroundings and impose risks for others with close contact. Placement of COVID-19 patients in rooms with negative pressure may bring a false feeling of safety, and the importance of rigorous environment cleaning should be emphasized.IMPORTANCE Although it has been well recognized that the virus SARS-CoV-2, the causative agent of COVID-19, can be acquired by exposure to fomites, surprisingly, the contamination of patients' surroundings by SARS-CoV-2 is largely unknown, as there have been few studies. We performed an environmental sampling study for 13 laboratory-confirmed COVID-19 patients and found extensive contamination of patients' surroundings. In particular, we found that asymptomatic COVID-19 patients contaminated their surroundings and therefore imposed risks for other people. Environment cleaning should be emphasized in negative-pressure rooms. The findings may be useful to guide infection control practice to protect health care workers.


Assuntos
Infecções Assintomáticas/epidemiologia , Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/epidemiologia , Exposição Ambiental , Microbiologia Ambiental , Pneumonia Viral/epidemiologia , COVID-19 , Contenção de Riscos Biológicos/métodos , Infecções por Coronavirus/patologia , Meio Ambiente , Humanos , Pandemias , Pneumonia Viral/patologia , SARS-CoV-2
14.
ACS Omega ; 4(8): 13577-13584, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31460487

RESUMO

Copper(I) oxide (Cu2O) nanoparticles (NPs) are selectively prepared in high yields under continuous flow in a vortex fluidic device (VFD), involving irradiation of a copper rod using a pulsed laser operating at 1064 nm and 600 mJ. The plasma plume generated inside a glass tube (20 mm O.D.), which is rapidly rotating (7.5 k rpm), reacts with the enclosed air in the microfluidic platform, with then high mass transfer of material into the dynamic thin film of water passing up the tube. The average size of the generated Cu2ONPs is 14 nm, and they are converted to copper(II) oxide (CuO) nanoparticles with an average diameter of 11 nm by heating the as-prepared solution of Cu2ONPs in air at 50 °C for 10 h.

15.
ACS Appl Bio Mater ; 2(1): 488-494, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-35016312

RESUMO

Cellulose immobilized palladium (0) nanoparticles (PdNPs) were prepared for the use in scalable catalytic reactions in flow. Preparation of the catalyst is remarkably simple and fast, where a palladium acetate solution is drop-casted onto cellulose paper and then exposed to 1 atm of hydrogen for a mere 90 s to produce embedded Pd(0) nanoparticles. This catalyst system is efficient in the hydrogenation of alkenes, nitroarenes, ketones, and enamides, with products formed in high yields, under ambient pressure and temperature. The system is also effective for transfer hydrogenation using ammonium formate as an alternative hydrogen source. A high catalyst stability and reusability are demonstrated along with the chemoselective and scalable synthesis of industrially important fine chemicals, including the biobased molecule cyrene.

16.
Nanoscale Adv ; 1(7): 2495-2501, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-36132736

RESUMO

Two-dimensional graphene has remarkable properties that are revolutionary in many applications. Scrolling monolayer graphene with precise tunability would create further potential for niche applications but this has proved challenging. We have now established the ability to fabricate monolayer graphene scrolls in high yield directly from graphite flakes under non-equilibrium conditions at room temperature in dynamic thin films of liquid. Using conductive atomic force microscopy we demonstrate that the graphene scrolls form highly conducting electrical contacts to highly oriented pyrolytic graphite (HOPG). These highly conducting graphite-graphene contacts are attractive for the fabrication of interconnects in microcircuits and align with the increasing interest in building all sp2-carbon circuits. Above a temperature of 450 °C the scrolls unravel into buckled graphene sheets, and this process is understood on a theoretical basis. These findings augur well for new applications, in particular for incorporating the scrolls into miniaturized electronic devices.

17.
Org Lett ; 7(19): 4071-4, 2005 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-16146354

RESUMO

[reaction: see text] A series of novel nanosized pi-conjugated molecules based on both truxene and porphyrin moieties with high fluorescence quantum yields have been prepared via the Suzuki cross-coupling and the Lindsey reactions. The investigation of optical properties demonstrates that various aryl groups as the antenna efficiently enhance the intramolecular and intermolecular energy transfer. These nanosized macromolecules emitting intense red light might be good candidates for photonic and electronic devices.

18.
Pak J Biol Sci ; 16(18): 969-75, 2013 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24502157

RESUMO

It is undeniable that environmental sonic vibration can affect our emotions and mood, but so far the study of physical stimuli provoked by audible wave on single cells has been rarely concerned. To investigate the response of E. coli to audible wave exposure, the growth status and alterations in antioxidant enzyme activity were studied in liquid culture. The data showed that the growth of E. coli was promoted in the treatments of different frequencies sound wave. The most significant effect on growth promotion appeared when sound wave was maintained at 100 dB and 5000 Hz. Simultaneously, sonic vibration evoked significantly increases the level of total protein content contents. And the changes of activities of Super Oxide Dismutase (SOD) and catalase (CAT) were observed obviously. The results suggested that the growth promotion effect of audible sound may be non-linear and shows obvious frequency and intensity peculiarities. Moreover, the increase in activity of antioxidant enzymes implied that a number of active oxygen species generated in bacterial cell under the exposure of audible sound. We speculate that the audible sound may cause a secondary oxidative stress. Further studies are needed to elucidate the mechanisms of active oxygen species generation induced by audible sound.


Assuntos
Escherichia coli/crescimento & desenvolvimento , Mecanotransdução Celular , Som , Antioxidantes/metabolismo , Catalase/metabolismo , Escherichia coli/enzimologia , Proteínas de Escherichia coli/metabolismo , Estresse Oxidativo , Pressão , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Vibração
19.
PLoS One ; 8(7): e67893, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23874463

RESUMO

The molecular organization of the epicuticle (the outermost layer) of insect wings is vital in the formation of the nanoscale surface patterns that are responsible for bestowing remarkable functional properties. Using a combination of spectroscopic and chromatographic techniques, including Synchrotron-sourced Fourier-transform infrared microspectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) depth profiling and gas chromatography-mass spectrometry (GCMS), we have identified the chemical components that constitute the nanoscale structures on the surface of the wings of the dragonfly, Hemianax papuensis. The major components were identified to be fatty acids, predominantly hexadecanoic acid and octadecanoic acid, and n-alkanes with even numbered carbon chains ranging from C14 to C30. The data obtained from XPS depth profiling, in conjunction with that obtained from GCMS analyses, enabled the location of particular classes of compounds to different regions within the epicuticle. Hexadecanoic acid was found to be a major component of the outer region of the epicuticle, which forms the surface nanostructures, and was also detected in deeper layers along with octadecanoic acid. Aliphatic compounds were detected throughout the epicuticle, and these appeared to form a third discrete layer that was separate from both the inner and outer epicuticles, which has never previously been reported.


Assuntos
Odonatos/anatomia & histologia , Asas de Animais/química , Asas de Animais/ultraestrutura , Absorção , Animais , Cromatografia/métodos , Nitrogênio/química , Oxigênio/química , Análise Espectral/métodos , Propriedades de Superfície
20.
J Org Chem ; 71(12): 4400-10, 2006 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-16749767

RESUMO

A series of large, rigid, new, well-defined, D-pi-B-A compounds with three chromophores (truxene moieties at the core, conjugated oligothiophenes as the branch bridges, and [60]pyrrolidinofullerene (C60) segments as the end-capped groups) have been facilely developed in this contribution. Oligothiophene-functionalized truxene derivatives 1-29 are prepared by the Suzuki, the Sonogashira, and the Negishi cross-coupling reactions catalyzed by Pd(PPh3)4 as well as the McMurry reaction, respectively. The 1,3-dipolar cycloaddition of the oligomers with C60 and N-methylglycine yields a new family of star-shaped D-pi-B-A derivatives end-capped with pyrrolidinofullerene moieties as the active materials for photovoltaic devices in which one, two, three, or four C60 moieties are allocated at the peripheral position of well-defined compounds, respectively. We also investigate the UV-vis and photoluminescence behaviors of these pyrrolidinofullerene-functionalized derivatives. The emission is obviously quenched after the inducement of the C60 moieties. We also observe that the emission intensity is decreased with the increase in the number of C60 moieties.


Assuntos
Fulerenos/química , Substâncias Macromoleculares/síntese química , Nanopartículas , Hidrocarbonetos Aromáticos/química , Luminescência , Pirrolidinas , Análise Espectral , Tiofenos
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa