Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Rep ; 14(1): 2875, 2024 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-38311622

RESUMO

Space heating and cooling of buildings account for [Formula: see text] 30% of energy consumed globally. As a result, efforts to reduce the carbon footprint associated with building temperature regulation are crucial to achieving sustainability goals. Passive radiative cooling and sun heating are two promising innovations that can help reduce the energy consumption associated with building temperature regulation. However, these methods are constrained by factors such as climate zones and seasonal changes. In this work, we demonstrate numerically that bilateral photonic metamaterials enabled by vanadium dioxide (VO2) nanoparticles embedded into polyethylene nanogratings can achieve dynamically modulate solar absorptance at one side in winter and achieve radiative cooling on another side. In cold weather, the solar absorptance of this metastructure can change from 0.93 to 0.2 at a critical temperature when VO2 changes from a metallic to an insulating state. This metastructure consists of broadband transparent polyethylene (PE) gratings on the reflective silver (Ag) gratings with the same period and filling ratio. These gratings are deposited on top of the Polydimethylsiloxane (PDMS) thin film. The VO2 nanoparticles enable dynamic solar absorptance modulation for winter space heating, while the PDMS with strong infrared emittance derived from molecular vibrations over the atmospheric window for summer radiative cooling. Temperature response simulations validate that this bilateral design achieves   6 °C subambient temperature drop at noontime in the summer and stabilizes its temperature around 22 °C during the daytime in the winter. This passive dynamical thermal regulation technique can be deployed for energy-saving targets of buildings, vehicles, and greenhouses in areas with large temperature fluctuations.

2.
Plants (Basel) ; 12(5)2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36904053

RESUMO

Water level rise is considered an environmental filter for the growth and reproduction of aquatic plants in lakes. Some emergent macrophytes can form floating mats, enabling them to escape from the negative effects of deep water. However, an understanding of which species can be uprooted and form floating mats easily and what factors affect these tendencies remains greatly elusive. We conducted an experiment to determine whether the monodominance of Zizania latifolia in the emergent vegetation community in Lake Erhai was related to its floating mat formation ability and to try to find the reasons for its floating mat formation ability during the continuous increase in water level over the past few decades. Our results showed that both the frequency and biomass proportion of Z. latifolia were greater among the plants on the floating mats. Furthermore, Z. latifolia was more likely to be uprooted than the other three previously dominant emergent species due to its smaller angle between the plant and the horizontal plane, rather than the root:shoot or volume:mass ratios. The dominance of Z. latifolia in the emergent community in Lake Erhai is due to its easier ability to become uprooted, allowing it to outperform other emergent species and become the single dominant emergent species under the environmental filter of deep water. The ability to uproot and form floating mats may be a competitive survival strategy for emergent species under the conditions of continuous significant water level rise.

3.
Br J Radiol ; 96(1146): 20221006, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-36972072

RESUMO

OBJECTIVE: To evaluate the performance and robustness of a deep learning-based automatic fresh rib fracture detection and positioning system (FRF-DPS). METHODS: CT scans of 18,172 participants admitted to eight hospitals from June 2009 to March 2019 were retrospectively collected. Patients were divided into development set (14,241), multicenter internal test set (1612), and external test set (2319). In internal test set, sensitivity, false positives (FPs) and specificity were used to assess fresh rib fracture detection performance at the lesion- and examination-levels. In external test set, the performance of detecting fresh rib fractures by radiologist and FRF-DPS were evaluated at lesion, rib, and examination levels. Additionally, the accuracy of FRF-DPS in rib positioning was investigated by the ground-truth labeling. RESULTS: In multicenter internal test set, FRF-DPS showed excellent performance at the lesion- (sensitivity: 0.933 [95%CI, 0.916-0.949], FPs: 0.50 [95%CI, 0.397-0.583]) and examination-level. In external test set, the sensitivity and FPs at the lesion-level of FRF-DPS (0.909 [95%CI, 0.883-0.926], p < 0.001; 0.379 [95%CI, 0.303-0.422], p = 0.001) were better than the radiologist (0.789 [95%CI, 0.766-0.807]; 0.496 [95%CI, 0.383-0.571]), so were the rib- and patient-levels. In subgroup analysis of CT parameters, FRF-DPS were robust (0.894-0.927). Finally, FRF-DPS(0.997 [95%CI, 0.992-1.000], p < 0.001) is more accurate than radiologist (0.981 [95%CI, 0.969-0.996]) in rib positioning and takes 20 times less time. CONCLUSION: FRF-DPS achieved high detection rate of fresh rib fractures with low FP values, and precise positioning of ribs, thus can be used in clinical practice to improve the detection rate and work efficiency. ADVANCES IN KNOWLEDGE: We developed the FRF-DPS system which can detect fresh rib fractures and rib position, and evaluated by a large amount of multicenter data.


Assuntos
Aprendizado Profundo , Fraturas das Costelas , Humanos , Fraturas das Costelas/diagnóstico por imagem , Estudos Retrospectivos , Sensibilidade e Especificidade , Costelas/diagnóstico por imagem
4.
Microvasc Res ; 147: 104502, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36746363

RESUMO

The main pathological manifestation of coronary artery disease is myocardial injury caused by ischemia-reperfusion (IR) injury. Regular exercise reduces the risk of death during myocardial IR injury. The aim of this study was to describe the effects of various types of exercise on myocardial IR injury. Four electronic databases PubMed, Web of Science, Embase, and Cochrane Library were comprehensively searched from inception until February 2022, to identify studies relevant to the current review, using the method of combining subject and free words. Finally, 16 articles were included in the meta-analysis. Results showed that exercise training decreases the Myocardial infarct size compared to the control group (SMD = -2.6, 95 % CI [-3.53 to -1.67], P < 0.01); increasing the coronary blood flow (MD = 2.93, 95 % CI [2.41 to 3.44], P < 0.01), left ventricular developed pressure (SMD = 2.28, 95 % CI [0.12 to 4.43], P < 0.05), cardiac output (SMD = 1.22, 95 % CI [0.61 to 1.83], P < 0.01) compared to the control group. According to the descriptive analysis results also showed that exercise training increases the left ventricular ejection fraction, superoxide dismutase, manganese superoxide dismutase, glutathione peroxidase, copper-zinc superoxide dismutase, glutathione peroxidase, and decrease the creatine kinase, creatine kinase-MB, lactate dehydrogenase, Malondialdehyde, cardiac troponins T. Exercise can improve myocardial function after myocardial IR injury; however, further research is needed in combination with specific issues such as exercise mode, intensity, duration, and model issues.


Assuntos
Traumatismo por Reperfusão Miocárdica , Humanos , Traumatismo por Reperfusão Miocárdica/patologia , Volume Sistólico , Função Ventricular Esquerda , Superóxido Dismutase , Exercício Físico , Glutationa Peroxidase
5.
Bioorg Chem ; 93: 103316, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31585271

RESUMO

This study aimed to synthesize and screen tyrosinase inhibitors for delay fruit browning. A series of vanillyl cinnamate analogues were designed and synthesized by simple processes, and the inhibitory effects of all the synthesized derivatives on mushroom tyrosinase were evaluated. In the enzymatic activity test, compounds 21, 22, and 26 had significant (P < 0.05) effect on mushroom tyrosinase at a preliminary screening dose (1 mg/mL in vitro). IC50 analysis showed that the IC50 values of compounds 21, 22 and 26 were 268.5 µM, 213.2 µM and 413.5 µM, respectively. In the cytotoxicity evaluation, Cell Counting Kit-8 (CCK-8) assay showed that compounds 21, 22 and 26 had no significant effect on the proliferation of hepatocyte L02 and B16 melanoma cells at the dosage of 25-200 µM. Inhibition of tyrosinase activity and melanin content in B16 melanoma cells investigations indicated that compounds 21, 22 and 26 inhibited both cellular tyrosinase activity and melanin content dose-dependently and more strongly than the reference standard arbutin. The UV-visible spectra showed compound 22 inhibits the formation of dopamine quinone, further the molecular docking analysis of compound 22 with tyrosinase (PDB: 2Y9X) indicated that compound 22 interacted with the amino acid residues of tyrosinase. The results of anti-browning test showed that compounds 21, 22 and 26 had significant tyrosinase inhibition and anti-browning effects on fresh-cut apple slices at 4 °C in 48 h. Compound 22 could be used as novel tyrosinase inhibitor to delay fruit browning.


Assuntos
Cinamatos/metabolismo , Inibidores Enzimáticos/síntese química , Monofenol Mono-Oxigenase/antagonistas & inibidores , Agaricales/enzimologia , Animais , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cinamatos/química , Cinamatos/farmacologia , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Cinética , Melaninas/antagonistas & inibidores , Melaninas/metabolismo , Camundongos , Simulação de Acoplamento Molecular , Monofenol Mono-Oxigenase/metabolismo , Estrutura Terciária de Proteína , Relação Estrutura-Atividade
6.
Biotechnol Biofuels ; 11: 41, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29467819

RESUMO

BACKGROUND: The high cost of enzymes is one of the key technical barriers that must be overcome to realize the economical production of biofuels and biomaterials from biomass. Supplementation of enzyme cocktails with lytic polysaccharide monooxygenase (LPMO) can increase the efficiency of these cellulase mixtures for biomass conversion. The previous studies have revealed that LPMOs cleave polysaccharide chains by oxidization of the C1 and/or C4 carbons of the monomeric units. However, how LPMOs enhance enzymatic degradation of lignocellulose is still poorly understood. RESULTS: In this study, we combined enzymatic assays and real-time imaging using atomic force microscopy (AFM) to study the molecular interactions of an LPMO [TrAA9A, formerly known as TrCel61A) from Trichoderma reesei] and a cellobiohydrolase I (TlCel7A from T. longibrachiatum) with bacterial microcrystalline cellulose (BMCC) as a substrate. Cellulose conversion by TlCel7A alone was enhanced from 46 to 54% by the addition of TrAA9A. Conversion by a mixture of TlCel7A, endoglucanase, and ß-glucosidase was increased from 79 to 87% using pretreated BMCC with TrAA9A for 72 h. AFM imaging demonstrated that individual TrAA9A molecules exhibited intermittent random movement along, across, and penetrating into the ribbon-like microfibril structure of BMCC, which was concomitant with the release of a small amount of oxidized sugars and the splitting of large cellulose ribbons into fibrils with smaller diameters. The dividing effect of the cellulose microfibril occurred more rapidly when TrAA9A and TlCel7A were added together compared to TrAA9A alone; TlCel7A alone caused no separation. CONCLUSIONS: TrAA9A increases the accessible surface area of BMCC by separating large cellulose ribbons, and thereby enhances cellulose hydrolysis yield. By providing the first direct observation of LPMO action on a cellulosic substrate, this study sheds new light on the mechanisms by which LPMO enhances biomass conversion.

7.
Appl Microbiol Biotechnol ; 101(10): 4093-4101, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28197688

RESUMO

Endo-ß1,4-glucanases in glycosyl hydrolase family 5 (GH5) are ubiquitous enzymes in the multicellular fungi and are common components of enzyme cocktails for biomass conversion. We recently showed that an endo-glucanase of subfamily 5 of GH5 (GH5_5) from Sporotrichum thermophile (StCel5A) was more effective at releasing glucose from pretreated corn stover, when part of an eight-component synthetic enzyme mixture, compared to its closely related counterpart from Trichoderma reesei, TrCel5A. StCel5A and TrCel5A belong to different clades of GH5_5 (GH5_5_1 and GH5_5_2, respectively). To test whether the superior activity of StCel5A was a general property of all enzymes in the GH5_5_2 clade, StCel5A, TrCel5A, and two additional members of each subfamily were expressed in a common host that had been engineered to suppress its native cellulases (T. reesei Δxyr1) and compared against each other alone on pure substrates, in synthetic mixtures on pure substrates, and against each other in synthetic mixtures on real biomass. The results indicated that superiority is a unique property of StCel5A and not of GH5_5_2 generally. The six Cel5A enzymes had significant differences in relative activities on different substrates, in specific activities, and in sensitivities to mannan inhibition. Importantly, the behavior of the six endo-glucanases on pure cellulose substrates did not predict their behavior in combination with other cellulolytic enzymes on a real lignocellulosic biomass substrate.


Assuntos
Biomassa , Celulase/química , Celulase/metabolismo , Sporothrix/metabolismo , Trichoderma/metabolismo , Biotecnologia/métodos , Celulase/classificação , Celulose , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glucose/metabolismo , Hidrólise , Sporothrix/enzimologia , Trichoderma/enzimologia , Zea mays
8.
PLoS One ; 9(10): e109885, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25295862

RESUMO

Enzymatic conversion of lignocellulosic materials to fermentable sugars is a limiting step in the production of biofuels from biomass. We show here that combining enzymes from different microbial sources is one way to identify superior enzymes. Extracts of the thermophilic fungus Sporotrichum thermophile (synonym Myceliophthora thermophila) gave synergistic release of glucose (Glc) and xylose (Xyl) from pretreated corn stover when combined with an 8-component synthetic cocktail of enzymes from Trichoderma reesei. The S. thermophile extracts were fractionated and an enhancing factor identified as endo-ß1,4-glucanase (StCel5A or EG2) of subfamily 5 of Glycosyl Hydrolase family 5 (GH5_5). In multi-component optimization experiments using a standard set of enzymes and either StCel5A or the ortholog from T. reesei (TrCel5A), reactions containing StCel5A yielded more Glc and Xyl. In a five-component optimization experiment (i.e., varying four core enzymes and the source of Cel5A), the optimal proportions for TrCel5A vs. StCel5A were similar for Glc yields, but markedly different for Xyl yields. Both enzymes were active on lichenan, glucomannan, and oat ß-glucan; however, StCel5A but not TrCel5A was also active on ß1,4-mannan, two types of galactomannan, and ß1,4-xylan. Phylogenetically, fungal enzymes in GH5_5 sorted into two clades, with StCel5A and TrCel5A belonging to different clades. Structural differences with the potential to account for the differences in performance were deduced based on the known structure of TrCel5A and a homology-based model of StCel5A, including a loop near the active site of TrCel5A and the presence of four additional Trp residues in the active cleft of StCel5A. The results indicate that superior biomass-degrading enzymes can be identified by exploring taxonomic diversity combined with assays in the context of realistic enzyme combinations and realistic substrates. Substrate range may be a key factor contributing to superior performance within GH5_5.


Assuntos
Biomassa , Biotecnologia/métodos , Celulase/metabolismo , Sordariales/enzimologia , Trichoderma/enzimologia , Celulase/química , Glucose/química , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Filogenia , Conformação Proteica , Temperatura , Zea mays/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...