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1.
Polymers (Basel) ; 14(18)2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36145872

RESUMO

The development of a simple and efficient synthetic methodology to engineer functional polymer materials for gas adsorption is necessary due to its relevance for various applications. Herein, we report the synthesis of metalorganic poly(vinylene sulfide) copolymers CTP1-3 with iron(II) clathrochelate of various side groups connected by tetraphenylbenzene units. CTP1-3 were subsequently oxidized into their respective poly(vinylene sulfone) copolymers CTP4-6 under green reaction conditions. The target copolymers CTP1-6 were characterized using various instrumental analysis techniques. Examination of the iodine adsorption properties of the copolymers revealed high iodine uptake properties, reaching 2360 mg g-1 for CTP2, and whose reusability tests proved its efficient regeneration, thus proving the importance of iron(II) clathrochelate polymers in iodine capture.

2.
Proc Natl Acad Sci U S A ; 119(15): e2119429119, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35377791

RESUMO

Charge density waves (CDWs) have been observed in nearly all families of copper-oxide superconductors. But the behavior of these phases across different families has been perplexing. In La-based cuprates, the CDW wavevector is an increasing function of doping, exhibiting the so-called Yamada behavior, while in Y- and Bi-based materials the behavior is the opposite. Here, we report a combined resonant soft X-ray scattering (RSXS) and neutron scattering study of charge and spin density waves in isotopically enriched La1.8−xEu0.2SrxCuO4 over a range of doping 0.07≤x≤0.20. We find that the CDW amplitude is temperature independent and develops well above experimentally accessible temperatures. Further, the CDW wavevector shows a nonmonotonic temperature dependence, exhibiting Yamada behavior at low temperature with a sudden change occurring near the spin ordering temperature. We describe these observations using a Landau­Ginzburg theory for an incommensurate CDW in a metallic system with a finite charge compressibility and spin-CDW coupling. Extrapolating to high temperature, where the CDW amplitude is small and spin order is absent, our analysis predicts a decreasing wavevector with doping, similar to Y and Bi cuprates. Our study suggests that CDW order in all families of cuprates forms by a common mechanism.

3.
Biomed Mater Eng ; 32(1): 39-52, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33164919

RESUMO

BACKGROUND: Merging stem cells with biomimetic materials represent an attractive approach to tissue engineering. The development of an alternative scaffold with the ability to mimic the extracellular matrix, and the 3D gradient preventing any alteration in cell metabolism or in their gene expression patterns, would have many medical applications. OBJECTIVE: In this study, we introduced the use of RGD (Arg-Gly-Asp) bio-conjugated cotton to promote the growth and proliferation of mesenchymal stem cells (MSCs). METHODS: We measured the expression of stem cell markers and adhesion markers with Q-PCR and analyzed the transcriptomic. The results obtained showed that the MSCs, when cultured with bio-conjugated cotton fibers, form aggregates around the fibers while proliferating. The seeded MSCs with cotton fibers proliferated in a similar fashion to the cells seeded on the monolayer (population doubling level 1.88 and 2.19 respectively). RESULTS: The whole genome sequencing of cells adhering to these cotton fibers and cells adhering to the cell culture dish showed differently expressed genes and pathways in both populations. However, the expression of the stem cell markers (Oct4, cKit, CD105) and cell adhesion markers (CD29, HSPG2 and CD138), when examined with quantitative RT-PCR, was maintained in both cell populations. CONCLUSION: These results clearly show the ability of the cotton fibers to promote MSCs growth and proliferation in a 3D structure mimicking the in vivo environment without losing their stem cell phenotype.


Assuntos
Proliferação de Células , Fibra de Algodão , Diferenciação Celular , Células Cultivadas , Células-Tronco Mesenquimais , Oligopeptídeos , Tecidos Suporte
4.
J Org Chem ; 85(15): 9928-9935, 2020 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-32674572

RESUMO

A family of three spatially directional resorcin[4]arene cavitand glycoconjugates (RCGs) have been applied as efficient recoverable and reusable inverse phase transfer catalysts for eco- and environmentally friendly thiocyanation and 2-amino-1,3-thiazole formation reactions in water. The results show that RCGs (1 mol %) were capable of hosting and catalyzing various water-insoluble bromo/thiocyanato substrates in water without the use of any co-organic solvents. The recoverability and reusability of RCG catalytic systems, that is, RCG1 and RCG3, were also examined upon a simple extraction of the desired products using DCM or ethyl acetate, followed by subjecting the recovered aqueous solution containing the RCG catalysts to the next reaction cycles.

5.
Molecules ; 25(7)2020 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-32225079

RESUMO

: Detecting tissue pH in vivo is extremely vital for medical diagnosis and formulation of treatment decisions. To this end, many investigations have been carried out to develop an accurate and efficient method of in vivo pH measurement. Most of the techniques developed so far suffer from inadequate accuracy, due to poor sensitivity at low concentration of the target or nonspecific interactions within the tissue matrix. To overcome these issues, we describe herein the development of a simple, yet reliable, way to estimate pH with high precision using a Gd(III)-DOTA-silyl-based acid-labile group as a pH-sensitive contrast agent with Magnetic Resonance Imaging (MRI). With this method, a change in T1 weighted image intensity of the newly developed pH-sensitive contrast is directly linked to the proton concentration in the media. As a result, we were able estimate the pH of the target with 95% reliability.


Assuntos
Meios de Contraste/química , Gadolínio/química , Concentração de Íons de Hidrogênio , Imageamento por Ressonância Magnética , Animais , Técnicas de Química Sintética , Meios de Contraste/síntese química , Meios de Contraste/metabolismo , Modelos Animais de Doenças , Gadolínio/metabolismo , Humanos , Imageamento por Ressonância Magnética/métodos , Camundongos , Modelos Químicos , Estrutura Molecular , Neoplasias/diagnóstico por imagem , Neoplasias/metabolismo , Especificidade de Órgãos , Distribuição Tecidual
6.
Sci Adv ; 5(8): eaax3346, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31453340

RESUMO

Charge order is universal among high-T c cuprates, but its relation to superconductivity is unclear. While static order competes with superconductivity, dynamic order may be favorable and even contribute to Cooper pairing. Using time-resolved resonant soft x-ray scattering at a free-electron laser, we show that the charge order in prototypical La2-x Ba x CuO4 exhibits transverse fluctuations at picosecond time scales. These sub-millielectron volt excitations propagate by Brownian-like diffusion and have an energy scale remarkably close to the superconducting T c. At sub-millielectron volt energy scales, the dynamics are governed by universal scaling laws defined by the propagation of topological defects. Our results show that charge order in La2-x Ba x CuO4 exhibits dynamics favorable to the in-plane superconducting tunneling and establish time-resolved x-rays as a means to study excitations at energy scales inaccessible to conventional scattering techniques.

7.
RSC Adv ; 9(18): 10109-10116, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-35520904

RESUMO

The Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) in aqueous media using resorcin[4]arene glycoconjugate (RG) is reported. The eight ß-d-glucopyranoside moieties constructed on the resorcin[4]arene upper rim provide a pseudo-saccharide cavity that offers a suitable host environment for water-insoluble hydrophobic azido and/or alkyne substrates in water. The utility of RG was established as an efficient inverse phase transfer catalyst for the CuAAC in water as a green approach for the synthesis of 1,4-disubstituted 1,2,3-triazole species. The catalytic utility of RG (1 mol%) was demonstrated in a multicomponent one-pot CuAAC for various azido/alkyne substrates. The RG acts as a molecular host and a micro-reactor resulting in the 1,4-disubstituted 1,2,3-triazoles in excellent yield.

8.
Science ; 358(6368): 1314-1317, 2017 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-29217574

RESUMO

Bose condensation has shaped our understanding of macroscopic quantum phenomena, having been realized in superconductors, atomic gases, and liquid helium. Excitons are bosons that have been predicted to condense into either a superfluid or an insulating electronic crystal. Using the recently developed technique of momentum-resolved electron energy-loss spectroscopy (M-EELS), we studied electronic collective modes in the transition metal dichalcogenide semimetal 1T-TiSe2 Near the phase-transition temperature (190 kelvin), the energy of the electronic mode fell to zero at nonzero momentum, indicating dynamical slowing of plasma fluctuations and crystallization of the valence electrons into an exciton condensate. Our study provides compelling evidence for exciton condensation in a three-dimensional solid and establishes M-EELS as a versatile technique sensitive to valence band excitations in quantum materials.

9.
Chemistry ; 22(18): 6223-7, 2016 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-26933945

RESUMO

The synthesis of novel spatially directional multivalent resorcin[4]arene cavitand glycoconjugates (RCGs) and their ability to catalyze organic reactions is reported. The ß-d-glucopyranoside moieties on the upper rim of the "bowl"-shaped resorcin[4]arene cavitand core are capable of multiple hydrogen-bond interactions resulting in a pseudo-cavity, which has been investigated for organic transformations in aqueous media. The RCGs have been demonstrated to catalyze thiazole formation, thiocyanation, copper(I)-catalyzed azide alkyne cycloaddition (CuAAC), and Mannich reactions; they impart stereoselectivity in the three-component Mannich reaction. Thermodynamic values obtained from (1) H diffusion-ordered spectroscopy (DOSY) experiments suggest that the upper saccharide cavity of the RCG and not the resorcin[4]arene cavity is the site of the complexation event.


Assuntos
Alcinos/química , Azidas/química , Calixarenos/química , Glicoconjugados/química , Fenilalanina/análogos & derivados , Catálise , Cobre/química , Reação de Cicloadição , Fenilalanina/química , Termodinâmica
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