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1.
Proc Natl Acad Sci U S A ; 119(10): e2112063119, 2022 03 08.
Artículo en Inglés | MEDLINE | ID: mdl-35238660

RESUMEN

SignificanceTwo billion people across the planet suffer from nutrient deficiencies. Dietary diversification is key to solving this problem, yet many food and nutrition security policies, especially in low- and middle-income countries, still focus on increasing agricultural production and access to sufficient calories as the main solution. But calories are not all equal. Here, we show how deforestation in Tanzania caused a reduction in fruit and vegetable consumption (of 14 g per person per day) and thus vitamin A adequacy of diets. Using a combination of regression and weighting analyses to generate quasi-experimental quantitative estimates of the impacts of deforestation on people's food intake, our study establishes a causal link between deforestation and people's dietary quality.


Asunto(s)
Ingestión de Energía , Conducta Alimentaria , Frutas , Población Rural , Verduras , Femenino , Humanos , Masculino , Tanzanía
2.
Proc Natl Acad Sci U S A ; 113(50): 14261-14266, 2016 12 13.
Artículo en Inglés | MEDLINE | ID: mdl-27911774

RESUMEN

Simultaneously achieving high optical transparency and excellent charge mobility in semiconducting polymers has presented a challenge for the application of these materials in future "flexible" and "transparent" electronics (FTEs). Here, by blending only a small amount (∼15 wt %) of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) into an inert polystyrene (PS) matrix, we introduce a polymer blend system that demonstrates both high field-effect transistor (FET) mobility and excellent optical transparency that approaches 100%. We discover that in a PS matrix, DPP2T forms a web-like, continuously connected nanonetwork that spreads throughout the thin film and provides highly efficient 2D charge pathways through extended intrachain conjugation. The remarkable physical properties achieved using our approach enable us to develop prototype high-performance FTE devices, including colorless all-polymer FET arrays and fully transparent FET-integrated polymer light-emitting diodes.

3.
Chembiochem ; 16(1): 77-82, 2015 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-25477295

RESUMEN

Most lipases resolve secondary alcohols in accordance with the "Kazlauskas rule" to give the R enantiomers. In a similar manner to other lipases, Candida rugosa lipase (CRL) exhibits R enantioselectivity towards heptan-2-ol, although the enantiomeric ratio (E) is low (E=1.6). However, unexpected enantioselectivity (i.e., S enantioselectivity, E=58) of CRL towards 4-(tert-butoxycarbonylamino)butan-2-ol, which has a similar chain length to heptan-2-ol, has been observed. To develop a deeper understanding of the molecular basis for this unusual enantioselectivity, we have conducted a series of molecular modeling and substrate engineering experiments. The results of these computational and experimental analyses indicated that a hydrogen bond between the Ser450 residue and the nitrogen atom of the carbamate group is critical to stabilize the transition state of the S enantiomer.


Asunto(s)
Amino Alcoholes/química , Candida/química , Proteínas Fúngicas/química , Heptanol/química , Lipasa/química , Candida/enzimología , Enlace de Hidrógeno , Cinética , Modelos Moleculares , Proteínas Recombinantes/química , Estereoisomerismo , Relación Estructura-Actividad , Especificidad por Sustrato
4.
RSC Adv ; 12(28): 17682-17688, 2022 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-35765342

RESUMEN

Two kinds of donor-acceptor π-conjugated copolymer based on poly{[N-hexyl-dithieno(3,2-b:2',3'-d)pyrrole-2,6-diyl]alt-[isoindigo]} (PDTP-IID) and poly{[N-hexyl-dithieno(3,2-b:2',3'-d)pyrrole-2,6-diyl]alt-[thiazol-2,5-diyl]} (PDTP-Thz) were investigated. These copolymers were synthesized via a Stille coupling reaction. The results showed the structure-property relationships of different donor-acceptor (D-A) combinations. The polymer structures and photophysical properties were characterized by 1H NMR, TGA, DSC, UV-vis absorption spectroscopy, AFM, CV, and XRD measurement. Through UV-vis absorption and cyclic voltammetry (CV) measurements, it showed that the copolymers exhibit not only a low bandgap of 1.29 eV and 1.51 eV but also a deep highest occupied molecular orbital (HOMO) of -5.49 and -5.11 eV. Moreover, photovoltaic properties in combination with the fullerene derivatives were investigated. The device based on the copolymers with PC71BM exhibited higher maximum power conversion efficiency and higher maximum short-circuit current density of 0.23% with 1.64 mA cm-2 of PDTP-IID:PC71BM and 0.13% with 1.11 mA cm-2 of PDTP-Thz:PC71BM than those of the copolymers with PC61BM. Measurements performed for N-hexyl-dithieno(3,2-b:2',3'-d)pyrrole-based copolymers proved the potential of these polymers to be applied in optoelectronic applications.

5.
BMC Biotechnol ; 9: 73, 2009 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-19706197

RESUMEN

BACKGROUND: MPG is a cell-permeable peptide with proven efficiency to deliver macromolecular cargoes into cells. In this work, we examined the efficacy of MPG as an N-terminal tag in a fusion protein to deliver a protein cargo and its mechanism of transduction. RESULTS: We examined transduction of MPG-EGFP fusion protein by live imaging, flow cytometry, along with combination of cell biological and pharmacological methods. We show that MPG-EGFP fusion proteins efficiently enter various mammalian cells within a few minutes and are co-localized with FM4-64, a general marker of endosomes. The transduction of MPG-EGFP occurs rapidly and is inhibited at a low temperature. The entry of MPG-EGFP is inhibited by amiloride, but cytochalasin D and methyl-beta-cyclodextrin did not inhibit the entry, suggesting that macropinocytosis is not involved in the transduction. Overexpression of a mutant form of dynamin partially reduced the transduction of MPG-EGFP. The partial blockade of MPG-EGFP transduction by a dynamin mutant is abolished by the treatment of amiloride. MPG-EGFP transduction is also observed in the mammalian oocytes. CONCLUSION: The results show that the transduction of MPG fusion protein utilizes endocytic pathway(s) which is amiloride-sensitive and partially dynamin-dependent. Collectively, the MPG fusion protein could be further developed as a novel tool of "protein therapeutics", with potentials to be used in various cell systems including mammalian oocytes.


Asunto(s)
Amilorida/química , Proteínas de Unión al ADN/metabolismo , Dinaminas/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Transducción Genética , Animales , Citocalasina D/química , Proteínas de Unión al ADN/genética , Endocitosis , Endosomas/genética , Femenino , Citometría de Flujo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Células HeLa , Humanos , Ratones , Células 3T3 NIH , Oocitos/metabolismo , Transporte de Proteínas , Compuestos de Piridinio , Compuestos de Amonio Cuaternario , Proteínas Recombinantes de Fusión/genética , beta-Ciclodextrinas/química
6.
Biotechnol Lett ; 31(1): 107-11, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-18791662

RESUMEN

Polymer-coated magnetic beads have become widely used in biological applications because of their facile recovery and easily modifiable surface. Herein, we report the application of magnetic beads to in vitro refolding of B. cepacia lipase. Magnetic particles (Fe3O4) prepared by co-precipitation of Fe2+ and Fe3+ ions under basic conditions were subsequently coated with carboxylic acid-containing polystyrene by emulsion polymerization. The polymer-coated magnetic beads were then conjugated with molecular chaperone proteins to assist with refolding. The chaperone-conjugated magnetic beads efficiently refolded B. cepacia lipase and were easily reused. The beads showed comparable refolding activity to the soluble chaperone, and retained more than 95% of their refolding activity after five cycles of refolding B. cepacia lipase.


Asunto(s)
Burkholderia cepacia/enzimología , Conservación de los Recursos Naturales , Lipasa/metabolismo , Magnetismo , Microesferas , Chaperonas Moleculares/metabolismo , Pliegue de Proteína , Electroforesis en Gel de Poliacrilamida , Hidrólisis , Lipasa/química , Nanopartículas , Proteínas Recombinantes/metabolismo , Factores de Tiempo
7.
Environ Manage ; 43(4): 628-44, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18830739

RESUMEN

Site-specific estimates of the values of spatial configuration and forest composition are presented. Amenity values of forest patches are found to vary the most by urban and sprawling development patterns of specific areas and forest types. For example, smaller patches of deciduous forest are more highly valued in the urban and sprawling areas of Greensboro, North Carolina, whereas larger patches of deciduous forest are more highly valued in the urban and sprawling areas of Greenville, South Carolina. Within the Greenville and Greensboro areas, visible landscape complexity is highly valued for deciduous and evergreen forest patches, whereas lower visible landscape complexity, i.e., smoothly trimmed forest patch boundaries, is highly valued for mixed forest patches.


Asunto(s)
Monitoreo del Ambiente/métodos , Modelos Teóricos , Árboles , North Carolina , South Carolina , Estados Unidos
8.
Sci Adv ; 4(8): eaat3604, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-30128356

RESUMEN

Realizing industrial-scale, large-area photovoltaic modules without any considerable performance losses compared with the performance of laboratory-scale, small-area perovskite solar cells (PSCs) has been a challenge for practical applications of PSCs. Highly sophisticated patterning processes for achieving series connections, typically fabricated using printing or laser-scribing techniques, cause unexpected efficiency drops and require complicated manufacturing processes. We successfully fabricated high-efficiency, large-area PSC modules using a new electrochemical patterning process. The intrinsic ion-conducting features of perovskites enabled us to create metal-filamentary nanoelectrodes to facilitate the monolithic serial interconnections of PSC modules. By fabricating planar-type PSC modules through low-temperature annealing and all-solution processing, we demonstrated a notably high module efficiency of 14.0% for a total area of 9.06 cm2 with a high geometric fill factor of 94.1%.

9.
ACS Appl Mater Interfaces ; 9(1): 819-826, 2017 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-27990796

RESUMEN

Stretchable conductive materials have received great attention owing to their potential for realizing next-generation stretchable electronics. However, the simultaneous achievement of excellent mechanical stretchability and high electrical conductivity as well as cost-effective fabrication has been a significant challenge. Here, we report a highly stretchable and highly conducting polymer that was obtained by incorporating an ionic liquid. When 1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB) was added to an aqueous conducting polymer solution of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it was found that EMIM TCB acts not only as a secondary dopant but also as a plasticizer for PEDOT:PSS, resulting in a high conductivity of >1000 S cm-1 with stable performance at tensile strains up to 50% and even up to 180% in combination with the prestrained substrate technique. Consequently, by exploiting the additional benefits of high transparency and solution-processability of PEDOT:PSS, we were able to fabricate a highly stretchable, semitransparent, and wholly solution-processed alternating current electroluminescent device with unimpaired performance at 50% strain by using PEDOT:PSS/EMIM TCB composite films as both bottom and top electrodes.

10.
Nat Commun ; 6: 6503, 2015 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-25790133

RESUMEN

Despite nearly two decades of research, the absence of ideal flexible and transparent electrodes has been the largest obstacle in realizing flexible and printable electronics for future technologies. Here we report the fabrication of 'polymer-metal hybrid electrodes' with high-performance properties, including a bending radius <1 mm, a visible-range transmittance>95% and a sheet resistance <10 Ω sq(-1). These features arise from a surface modification of the plastic substrates using an amine-containing nonconjugated polyelectrolyte, which provides ideal metal-nucleation sites with a surface-density on the atomic scale, in combination with the successive deposition of a facile anti-reflective coating using a conducting polymer. The hybrid electrodes are fully functional as universal electrodes for high-end flexible electronic applications, such as polymer solar cells that exhibit a high power conversion efficiency of 10% and polymer light-emitting diodes that can outperform those based on transparent conducting oxides.

11.
Nanoscale ; 5(23): 11587-91, 2013 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-24121410

RESUMEN

Vertically self-assembled bilayers with an interfacial bottom layer and a photoactive top layer are demonstrated via a single coating step of a blend composed of an amine-containing nonconjugated polyelectrolyte (NPE) and an organic electron donor-acceptor bulk heterojunction composite. The self-assembled NPE layer reduces the work function of an indium tin oxide (ITO) cathode, which leads to efficient inverted organic solar cells without any additional interface engineering of the ITO.


Asunto(s)
Aminas/química , Nanoconjugados/química , Energía Solar , Electrólitos/química , Electrones , Compuestos de Organoselenio/química , Poliestirenos/química , Tiofenos/química , Compuestos de Estaño/química
12.
Science ; 353(6295): 131, 2016 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-27387941
13.
Chem Commun (Camb) ; 47(10): 2904-6, 2011 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-21240442

RESUMEN

Bioconjugation of functional proteins onto metal-organic frameworks (MOFs) has been achieved using activation of pendent linking groups of the organic linkers on the surface of MOFs. Fluorescent microscopy revealed successful conjugation of an enhanced fluorescent protein onto MOFs. In addition, Candida-antarctica-lipase-B-conjugated MOFs showed no loss of enantioselectivity and activity in transesterification of (±)-1-phenylethanol.


Asunto(s)
Compuestos Organometálicos/química , Proteínas/química , Proteínas/metabolismo , Biocatálisis , Proteínas Fúngicas , Proteínas Fluorescentes Verdes/química , Proteínas Fluorescentes Verdes/metabolismo , Lipasa/química , Lipasa/metabolismo , Modelos Moleculares , Conformación Proteica
14.
Dalton Trans ; 39(5): 1261-5, 2010 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-20104352

RESUMEN

Three new isostructural two-dimensional metal-organic frameworks (MOFs), [M(bpydc)(H(2)O).H(2)O](n) where M = Zn (1); Co (2); Ni (3) and the bpydc is 2,2'-bipyridine-5,5'-dicarboxylate), were prepared by various methods such as hydrothermal, ultrasonic and microwave-assisted synthetic methods. Microcrystalline could be obtained by using ultrasonification or microwave irradiation in a short time. Their solid-state structures were revealed by X-ray crystallography. The coordination environment of the metal ions is distorted octahedral geometry. The metal ions are coordinated by two nitrogen atoms from the bipyridyl moiety, two oxygen atoms from one carboxylate in a bidentate manner, one oxygen atom from another carboxylate in a monodentate manner, and one oxygen atom from the aqua ligand. The multiple coordination modes of the bpydc ligand led to a novel topologically interesting two-dimensional sheet structure; a 6-connected uninodal net with Schläfli symbol of 3(3).4(4).5(5).6(2).7. Thermal and luminescence properties of the three MOFs were also investigated. The weight maintained constant in the range 290-342 degrees C for 1, 250-470 degrees C for 2, and 275-470 degrees C for 3 after the initial weight loss related to the dehydration steps. In particular, [Zn(bpydc)(H(2)O).H(2)O](n) (1) displays strong solid state blue luminescence.


Asunto(s)
Metales/química , Compuestos Organometálicos/química , Cristalografía por Rayos X , Luminiscencia , Microondas , Conformación Molecular , Temperatura
15.
Chem Commun (Camb) ; (33): 5003-5, 2009 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-19668830

RESUMEN

Glucose-coated polymeric beads have been prepared and applied to delivery of a model protein (enhanced green fluorescent protein) into mouse embryonic stem cells as well as Hela cells.


Asunto(s)
Glucosa/química , Polímeros/química , Transporte de Proteínas , Animales , Línea Celular Tumoral , Células Madre Embrionarias/citología , Proteínas Fluorescentes Verdes/análisis , Proteínas Fluorescentes Verdes/química , Células HeLa , Humanos , Ratones , Transfección
16.
J Biosci Bioeng ; 107(3): 266-71, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19269590

RESUMEN

The application of rice wine on skin is known to have beneficial effects such as enhancement of the skin barrier function and skin whitening. In this study, we focused on examination of the anti-aging effects of rice wine. The treatment of fibroblasts with rice wine in vitro increased the expression of procollagen and laminin-5, a key basement membrane component in cultured human fibroblasts. Rice wine significantly reduced the expression of UV-induced matrix metalloproteinase-1 (MMP-1) in a dose-dependent manner in both cultured human fibroblasts and keratinocytes. In addition, treatment with rice wine decreased UV-induced tumor necrosis factor-alpha (TNF-alpha) production in human keratinocytes. An in vivo study using hairless mice showed that topical application of rice wine protected mouse skin from photoaging. Thus, we suggest that rice wine may have potential as an effective agent for the prevention and treatment of UV-induced skin aging.


Asunto(s)
Fibroblastos/efectos de los fármacos , Queratinocitos/efectos de los fármacos , Oryza , Envejecimiento de la Piel/efectos de los fármacos , Vino , Animales , Células Cultivadas , Fibroblastos/metabolismo , Fibroblastos/efectos de la radiación , Humanos , Queratinocitos/metabolismo , Queratinocitos/efectos de la radiación , Laminina/metabolismo , Metaloproteinasa 1 de la Matriz/biosíntesis , Ratones , Ratones Pelados , Procolágeno/metabolismo , Envejecimiento de la Piel/efectos de la radiación , Factor de Necrosis Tumoral alfa/metabolismo , Rayos Ultravioleta/efectos adversos
17.
Biotechnol Lett ; 30(4): 717-22, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17985077

RESUMEN

Increasing the expression yield of active Candida antarctica lipase B (CAL-B) in Escherichia coli was achieved by using a codon-optimized synthetic gene and by mutagenesis to introduce hydrophilic residues on the surface of CAL-B. Five residues (four leucines and one isoleucine) on the surface of CAL-B were selected and changed with aspartate after codon optimization. While the codon-optimized synthetic gene of CAL-B did not increase the expression yield, the mutation increased the activity of the enzyme three-fold (3.3 mg/l of culture) compared to the wild type. The mutant enzyme had similar hydrolytic activity toward hydrolysis of p-nitrophenyl acetate or p-nitrophenyl butyrate and enantioselectivity toward hydrolysis of (R, S)-1-phenylethyl acetate compared to the wild-type enzyme.


Asunto(s)
Escherichia coli/metabolismo , Lipasa/genética , Lipasa/metabolismo , Mutagénesis Sitio-Dirigida/métodos , Escherichia coli/genética , Proteínas Fúngicas , Interacciones Hidrofóbicas e Hidrofílicas , Lipasa/química , Modelos Moleculares , Estructura Molecular , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Mutación , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Especificidad por Sustrato
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