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1.
Opt Express ; 31(4): 6917-6924, 2023 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-36823937

RESUMO

Fiber-optic sensors are an indispensable element of modern sensing technologies by virtue of their low cost, excellent electromagnetic immunity, and remote sensing capability. Optical Vernier effect is widely used to enhance sensitivity of fiber-optic sensors but requires bulky and complex cascaded interferometers. Here we propose and experimentally demonstrate an ultracompact (∼2 mm by ∼2 mm) Vernier-effect-improved sensor by only using a single microfiber-knot resonator. With the Vernier effect achieved by controlling the optical beating with the spectral ripple of a super light emitting diode (SLED), we show ∼20x sensitivity enhancement for quantitative temperature monitoring. Our sensor creates a new practical method to realize Vernier effect in fiber-optic sensors and beyond.

2.
J Nanosci Nanotechnol ; 16(4): 3930-4, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27451740

RESUMO

Metal tungstates, expressed by the general formula of MWO4, have important properties and applications in photoluminescence, microwave applications, optical fibers, scintillator materials, humidity sensors, magnetic properties, and catalysts. In this paper, we report a successful synthesis of CaWO4:Eul+ crystals with various morphologies in mild hydrothermal conditions with surfacntant including sodium citrate, CTAB, PEG and citrate acid (CA). The formation of the crystals are strongly dependent on the employment of surfactant. The surfactant concentration has been found significant influence in the resulting morphologies due to different properties of each one. Extensive characterization have been performed by using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) in search of the formation mechanism of multi-morphological CaWO4:Eu3+ crystals. The growth mechanism of monodispersed CaWO4:EuS+ crystal are proposed. And the photoluminescence properties were investigated.

3.
Chem Commun (Camb) ; 50(13): 1564-6, 2014 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-24382579

RESUMO

A new and efficient metal-free cascade cyclization of 1,6-enynes with aldehydes is developed for the synthesis of tricyclic fluorene derivatives. The reaction involves a radical process and one C(sp(2))-C(sp(2)) and two C(sp(2))-C(sp(3)) bonds are formed simultaneously in one pot by using PivOH and TBHP.


Assuntos
Aldeídos/química , Alcenos/química , Alcinos/química , Fluorenos/síntese química , Ciclização , Fluorenos/química , Radicais Livres/química
4.
Chem Commun (Camb) ; 49(86): 10190-2, 2013 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-24056675

RESUMO

Palladium-catalyzed carbene migratory insertion-cyclization reactions were reported, delivering dihydronaphthalene and indene derivatives in moderate to good yields. A three-component cross-coupling was also developed. The reactions are easy to handle, under mild conditions and various functional groups are tolerated.


Assuntos
Carbono/química , Hidrazonas/química , Paládio/química , Compostos de Tosil/química , Catálise , Indenos/química , Estrutura Molecular , Naftalenos/química
5.
Chem Commun (Camb) ; 49(50): 5687-9, 2013 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-23682357

RESUMO

A mild and efficient copper-catalyzed trifluoromethylation reaction which involves the cyclization of oximes has been developed. This method provides a convenient access to a variety of useful CF3-containing 4,5-dihydroisoxazoles by constructing a C-CF3 bond and a C-O bond in one step.


Assuntos
Cobre/química , Hidrocarbonetos Fluorados/química , Isoxazóis/química , Oximas/química , Catálise , Ciclização , Metilação
6.
Chem Commun (Camb) ; 49(31): 3254-6, 2013 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-23482942

RESUMO

Isoindolines are synthesized by palladium-catalyzed coupling reaction of N-(2-iodobenzyl) anilines with α,ß-unsaturated N-tosylhydrazones. The reaction has several potential advantages: (1) toleration of a wide range of functional groups, (2) easy to handle and with mild conditions, (3) enriches the isoindoline family, (4) two new bonds form in one step.


Assuntos
Hidrazonas/química , Indóis/química , Paládio/química , Aldeídos/química , Compostos de Anilina/química , Catálise , Indóis/síntese química
7.
Chem Commun (Camb) ; 49(6): 561-3, 2013 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-23208611

RESUMO

Two different cyclic amino esters are synthesized by palladium-catalyzed cross-coupling reaction of diazoesters with N-substituted-2-iodoanilines. Aryldiazoacetates lead to cyclic α-amino esters with an α-quaternary carbon centre in the presence of CO. Additionally, arylvinyldiazoacetates afford cyclic α,ß-unsaturated γ-amino esters.


Assuntos
Cetonas/química , Paládio/química , Compostos de Anilina/química , Compostos Azo/química , Catálise , Ciclização , Ésteres , Iodetos/química
10.
Org Biomol Chem ; 9(14): 5028-33, 2011 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-21643590

RESUMO

A useful method to construct highly substituted tetrahydroquinolines has been developed through an iron(III) chloride-mediated domino Mannich and intramolecular Friedel-Crafts alkylation followed by intermolecular Friedel-Crafts alkylation reactions of aliphatic aldehydes with aromatic amines.


Assuntos
Aldeídos/química , Aminas/química , Cloretos/química , Compostos Férricos/química , Quinolinas/síntese química , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Quinolinas/química , Estereoisomerismo
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