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1.
Langmuir ; 38(32): 9751-9759, 2022 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-35921602

RESUMEN

Interfacial properties of polymeric materials are significantly influenced by their architectural structures and spatial features, while such a study of topologically interesting macromolecules is rarely reported. In this work, we reported, for the first time, the interfacial behavior of catenated poly(l-lactide) (C-PLA) at the air-water interface and compared it with its linear analogue (L-PLA). The isotherms of surface pressure-area per repeating unit showed significant interfacial behavioral differences between the two polymers with different topologies. Isobaric creep experiments and compression-expansion cycles also showed that C-PLA demonstrated higher stability at the air-water interface. Interestingly, when the films at different surface pressures were transferred via the Langmuir-Blodgett method, successive atomic force microscopy imaging displayed distinct nanomorphologies, in which the surface of C-PLA exhibited nanofibrous structures, while that of the L-PLA revealed a smoother topology with less fiber-like structures.


Asunto(s)
Aire , Agua , Microscopía de Fuerza Atómica , Poliésteres/química , Polímeros/química , Propiedades de Superficie , Agua/química
2.
Small ; 17(24): e2101704, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33977641

RESUMEN

Imperceptible electronics will make next-generation healthcare and biomedical systems thinner, lighter, and more flexible. While other components are thoroughly investigated, imperceptible energy storage devices lag behind because the decrease of thickness impairs the area-specific energy density. Imperceptible supercapacitors with high area-specific capacitance based on reduced graphene oxide/polyaniline (RGO/PANI) composite electrodes and polyvinyl alcohol (PVA)/H2 SO4 gel electrolyte are reported. Two strategies to realize a supercapacitor with a total device thickness of 5 µm-including substrate, electrode, and electrolyte-and an area-specific capacitance of 36 mF cm-2 simultaneously are implemented. First, the void volume of the RGO/PANI electrodes through mechanical compression is reduced, which decreases the thickness by 83% while retaining 89% of the capacitance. Second, the PVA-to-H2 SO4 mass ratio is decreased to 1:4.5, which improves the ion conductivity by 5000% compared to the commonly used PVA/H2 SO4 gel. Both advantages enable a 2 µm-thick gel electrolyte for planar interdigital supercapacitors. The impressive electromechanical stability of the imperceptible supercapacitors by wrinkling the substrate to produce folds with radii of 6 µm or less is demonstrated. The supercapacitors will be meaningful energy storage modules for future self-powered imperceptible electronics.


Asunto(s)
Electrólitos , Alcohol Polivinílico , Capacidad Eléctrica , Conductividad Eléctrica , Electrodos
3.
Zhongguo Zhong Yao Za Zhi ; 40(15): 2909-14, 2015 Aug.
Artículo en Zh | MEDLINE | ID: mdl-26677686

RESUMEN

The physiological effects of Panax notoginseng seedlings under simulated drought stress by PEG 6000 on antioxidant enzymes, osmotic substances and root activities were studied. The results showed that the activity of POD and APX in roots and leaves kept rising with increasing processing concentration and time. However, on the one hand, at the same processing time, SOD in roots and leaves firstly increased and then decreased with the increase of processing concentration. On the other hand, at the same processing concentration, SOD kept rising with the extension of processing time. In addition, the activity of CAT in roots and leaves tended to increase with the increasing concentration at the same processing time, while it increased at first and then decreased with the extension of time at the same concentration. The activity of SOD and APX in stem did not change obviously, whereas CAT activity in stem increased with the increasing processing time and concentration. With the increase of processing concentration and the extension of processing time, the MDA, soluble protein, proline content and root activity in leaves and roots apparently rose. Moreover, fluorescence signal of H2O2 and NO in root tip enhanced as the processing concentration increased after treated for 1 d. In summary, P. notoginseng seedlings could deal with drought stress by means of adjusting the system of antioxidant enzyme, permeating stress substances and impeded stress signal substances. Thus, when the concentration of PEG 6000 was more than 5%, it would have harm on P. notoginseng seedlings.


Asunto(s)
Sequías , Panax notoginseng/fisiología , Plantones/fisiología , Estrés Fisiológico/fisiología , Relación Dosis-Respuesta a Droga , Panax notoginseng/efectos de los fármacos , Polietilenglicoles/farmacología , Plantones/efectos de los fármacos , Superóxido Dismutasa/metabolismo
4.
Chem Asian J ; 11(5): 687-90, 2016 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-26699200

RESUMEN

A novel pyrene-functionalized polynorbornene (P1) bearing sulfonamide NH and triazolium donors has been synthesized for ratiometric fluorescence sensing of PPi in aqueous solution. In addition, P1 is also used to monitor intracellular PPi and to detect PPi released during polymerase chain reaction.


Asunto(s)
Difosfatos/análisis , Colorantes Fluorescentes/química , Plásticos/química , Pirenos/química , Células HeLa , Humanos , Microscopía Confocal , Imagen Óptica , Espectrometría de Fluorescencia/métodos
5.
Adv Mater ; 28(4): 722-8, 2016 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-26618615

RESUMEN

A stretchable and multiple-force-sensitive electronic fabric based on stretchable coaxial sensor electrodes is fabricated for artificial-skin application. This electronic fabric, with only one kind of sensor unit, can simultaneously map and quantify the mechanical stresses induced by normal pressure, lateral strain, and flexion.


Asunto(s)
Piel Artificial , Electrodos , Electrónica , Nanocables/química , Poliuretanos/química , Povidona/química , Presión , Plata/química
6.
Dalton Trans ; 44(16): 7470-6, 2015 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-25803003

RESUMEN

A hydroxyquinoline functionlized polynorbornene (P1) was designed and synthesized. In an aqueous solution, P1 shows a "turn-on" fluorescence response for Zn(2+) and Cd(2+) with a 50 nm blue shift. Furthermore, both P1-Zn(2+) and P1-Cd(2+) complexes were found to respond to pyrophosphate (PPi) over other important biological anions via a fluorescence quenching effect. P1 is also capable of monitoring intracellular Zn(2+) and PPi in real time.


Asunto(s)
Cadmio/química , Difosfatos/análisis , Plásticos/química , Espectrometría de Fluorescencia , Zinc/química , Aniones/química , Complejos de Coordinación/síntesis química , Complejos de Coordinación/química , Complejos de Coordinación/metabolismo , Células Hep G2 , Humanos , Microscopía Fluorescente , Agua/química
7.
Adv Mater ; 25(46): 6692-8, 2013 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-24027108

RESUMEN

A fractured microstructure design: A new type of piezoresistive sensor with ultra-high-pressure sensitivity (0.26 kPa(-1) ) in low pressure range (<2 kPa) and minimum detectable pressure of 9 Pa has been fabricated using a fractured microstructure design in a graphene-nanosheet-wrapped polyurethane (PU) sponge. This low-cost and easily scalable graphene-wrapped PU sponge pressure sensor has potential application in high-spatial-resolution, artificial skin without complex nanostructure design.


Asunto(s)
Grafito/química , Nanoestructuras/química , Poliuretanos/química , Óxidos/química , Presión , Propiedades de Superficie , Transistores Electrónicos
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