Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Más filtros












Base de datos
Intervalo de año de publicación
1.
Sci Data ; 11(1): 528, 2024 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-38777888

RESUMEN

Due to the lack of direct assessment metrics, existing studies on the intensity of agricultural policies often utilize indicators such as Gross Domestic Product (GDP) of agriculture or the quantity of agricultural policies as measures. Optimizing methods for analyzing the intensity of agricultural policies will significantly impact parameter selection in agricultural policy research and the evaluation of policy effectiveness. In this study, we constructed a Chinese Agricultural Policy Corpus using agricultural policies released by various governmental agencies at the national level in China from 1982 to April 2023. We quantified the values of agricultural domain terms in the corpus and evaluated the intensity of each agricultural policy document. The validation results of this study indicate a strong correlation between the intensity of agricultural policies and agricultural GDP. The trend in agricultural GDP changes lags behind policy intensity by 2.5 years (at a 95% confidence level), thus validating the rationality of our constructed corpus, agricultural policy scoring dataset, and methodology.

2.
Int J Biol Macromol ; 266(Pt 2): 130715, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38462108

RESUMEN

With an aging population, the patients with valvular heart disease (VHD) are growing worldwide, and valve replacement is a primary choice for these patients with severe valvular disease. Among them, bioprosthetic heart valves (BHVs), especially BHVs trough transcatheter aortic valve replacement, are widely accepted by patients on account of their good hemodynamics and biocompatibility. Commercial BHVs in clinic are prepared by glutaraldehyde cross-linked pericardial tissue with the risk of calcification and thrombotic complications. In the present study, a strategy combines improved hemocompatibility and anti-calcification properties for BHVs has been developed based on a novel non-glutaraldehyde BHV crosslinker hexakis(hydroxymethyl)melamine (HMM) and the anticoagulant fucoidan. Besides the similar mechanical properties and enhanced component stability compared to glutaraldehyde crosslinked PP (G-PP), the fucoidan modified HMM-crosslinked PPs (HMM-Fu-PPs) also exhibit significantly enhanced anticoagulation performance with a 72 % decrease in thrombus weight compared with G-PP in ex-vivo shunt assay, along with the superior biocompatibility, satisfactory anti-calcification properties confirmed by subcutaneous implantation. Owing to good comprehensive performance of these HMM-Fu-PPs, this simple and feasible strategy may offer a great potential for BHV fabrication in the future, and open a new avenue to explore more N-hydroxymethyl compound based crosslinker with excellent performance in the field of biomaterials.


Asunto(s)
Anticoagulantes , Bioprótesis , Prótesis Valvulares Cardíacas , Polisacáridos , Polisacáridos/química , Polisacáridos/farmacología , Anticoagulantes/química , Anticoagulantes/farmacología , Animales , Coagulación Sanguínea/efectos de los fármacos , Humanos , Conejos , Ensayo de Materiales , Trombosis/prevención & control , Materiales Biocompatibles/química , Materiales Biocompatibles/farmacología , Reactivos de Enlaces Cruzados/química , Calcificación Fisiológica/efectos de los fármacos
3.
Int Immunopharmacol ; 118: 110008, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36989899

RESUMEN

Diabetic cardiomyopathy (DCM) is a kind of idiopathic heart disease, which is one of the main complications of diabetes and seriously threatens the life of diabetic patients. Rubiadin, an anthraquinone compound extracted from the stems and roots of rubiaceae, has been widely discussed for its anti-diabetes, anti-oxidation and other pharmacological effects. However, Rubiadin can cause drug-induced liver injury. Therefore, A-cycloglycosylated derivative of Rubiadin (ACDR) was obtained by modifying its structure. The purpose of this study was to investigate the effect of ACDR on DCM cardiac injury and its mechanism. The DCM animal model was established by streptozotocin, and the success of DCM was verified by blood glucose level, echocardiographic evidence of impaired myocardial functions along with enhanced myocardial fibrosis. We performed liver function tests, morphological staining of the heart and tests for oxidative stress to evaluate cardiac functional and structural changes. Finally, the expression of Na+/H+ exchanger (NHE1) protein was analyzed by immunohistochemistry and western bolt, and the expression of hairy/enhancer-of-split related with YRPW motif 1 (Hey1) and P-p38 protein was detected by immunofluorescence chemistry and western blotting. The results showed that ACDR can improve cardiac dysfunction, reduce myocardial injury, reduce oxidative stress, and protect the liver in DCM rats. Interestingly, all variations were countered by LiCl. Our study suggests that, along with controlling hyperglycemia, ACDR may improve DCM by reducing NHE1 expression, further inhibiting P-p38 activity and increasing Hey1 expression to reduce oxidative stress.


Asunto(s)
Diabetes Mellitus Experimental , Cardiomiopatías Diabéticas , Ratas , Animales , Cardiomiopatías Diabéticas/etiología , Diabetes Mellitus Experimental/metabolismo , Miocardio/metabolismo , Estrés Oxidativo , Antraquinonas/farmacología
4.
Opt Express ; 29(12): 19193-19201, 2021 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-34154160

RESUMEN

Perfect absorbers are highly desired in many engineering and military applications, including radar cross section (RCS) reduction, cloaking devices, and sensor detectors. However, most types of present absorbers can only absorb space propagation waves, but absorption for surface waves has not been researched intensively. Surface waves are easily excited on the interfaces between metal and dielectrics for electronic devices, which decreases their working performances due to the electromagnetic disturbances. Thus, it is of great significance to design appropriate absorbers to dissipate undesirable surface waves. Here, we propose the concept of a surface wave absorber, analyze its working principle, and prove its good performances experimentally. To demonstrate our concept, we design and fabricate a realistic surface wave absorber that is fixed on a metal surface. Experiments are performed to verify its electromagnetic characteristics. The results show that our designed meta-absorber can achieve an excellent surface wave absorption within a wide frequency window (5.8-11.2 GHz) and exhibit a very high efficiency over than 90%, but only with the thickness of 1 mm (0.028 λ). Our device can help to solve the issues of absorption at large angles, and it can find wide applications in large antenna array design and other communication systems.

5.
Opt Express ; 29(5): 7558-7567, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33726255

RESUMEN

Perfect absorbers are highly desired in many engineering and military applications, including radar cross section (RCS) reduction, cloaking devices, and sensor detectors. However, most types of present absorbers can only absorb space propagation waves, yet absorption for the surface wave (SW) has not been researched intensively. In reality, when the space wave illuminates on the metal under large oblique angles, surface waves can be excited on the interface between metal and dielectric and thus would increase the RCS and influence the stealth performance. Here, based on the wave vector and impedance matching theories, we propose a broadband absorber for the surface wave under spoof surface plasmon polariton (SSPP) mode. The former theory ensures that surface waves can enter the absorber efficiently, and the latter guarantees perfect absorption. The experimental results indicate that our absorber can achieve a broadband (9.4-18 GHz) performance with an absorption ratio better than 90%, which is in great agreement with the simulations. Therefore, our device can be applied in RCS reduction for the metal devices, antenna array decoupling and many other applications. Also, this work provides a unique methodology to design new types of broadband surface wave absorbers.

6.
Opt Express ; 27(22): 32835-32845, 2019 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-31684488

RESUMEN

Absorbers have potential applications in the stealth field. However, limited bandwidth and low absorption rate persist in existing methods. Moreover, absorbers working in the low frequency range (1-4 GHz) with small size are much more difficult to realize. In this paper, we propose a novel absorption structure, which combines indium tin oxide film and metal resonator. The former realizes impedance matching with free space in a broad bandwidth at moderate frequency range while the latter shows the resonant property at low frequency. Based on this absorption structure, we design the zigzag-shaped structure to realize high-efficiency and ultra-broadband absorption. To demonstrate the feasibility of our method, we fabricate a sample and perform measurements. The measurement results show that our sample can achieve ultra-broadband absorption with high-efficiency of over 90% from 1 GHz to 18 GHz, which is in good agreement with simulation results. Our findings provide a valuable technique for broadband device design, which could bring about a wide range of applications in cloaking technology.

7.
Opt Express ; 27(10): 14942-14950, 2019 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-31163935

RESUMEN

A perfect absorber is highly desired in many engineering applications, including cloaking devices and sensor detectors, but most types of absorbers with chirality-dependence have limited bandwidth. In this paper, we propose a novel broadband and chirality-dependent metasurface absorber that consists of an array of planar spiral elements. The spiral orientation can determine the absorption polarization, such as counterclockwise for right circular polarization (RCP) absorption and clockwise for left circular polarization (LCP) absorption. Three steps are adopted to enhance the absorption bandwidth: carefully optimizing the spiral turns, impedance of load resistor, and introducing a matching layer. To demonstrate our concept, we have designed and fabricated a realistic metasurface absorber. The numerical simulations are in good agreement with the experimental results. The simulation and measurement results demonstrate that this device can achieve a broadband (8.3-18 GHz) absorption for RCP incidence, while reflecting the LCP incident waves between 9 GHz to 17.8 GHz without changing its chirality. Our findings explore a novel way to realize broadband absorption and simultaneously provide a new strategy to design chirality-dependent multi-functional meta-devices.

8.
Opt Express ; 27(3): 2844-2854, 2019 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-30732316

RESUMEN

Achieving asymmetric transmission effects, especially in an ultra-broadband frequency region, is of particular importance in communication systems. Currently available asymmetric transmission metasurfaces are limited to narrow bands and low efficiencies because of the inherently dispersion effects and large transmission fluctuations. In this paper, we propose a new strategy to realize high efficiency and ultra-broadband asymmetric transmission in an ultra-thin profile by using the topologically coding optimization method. The meta-atom consists of two outer orthogonal gratings and a central lattice particle optimized by genetic algorithm. The optimized central lattice suppresses the transmission fluctuations by tuning the coupling among different metallic layers, resulting in very broad band and high transmissions. Experimental results show that our metasurface achieved perfect reflection over 95% and high cross-polarization transmission over 80% for y- and x-polarized incidence from 5.3 GHz to 16.7 GHz, respectively. Our findings pave a way to high-performance and broadband polarization transformers and polarization-controlled devices working in different frequency domains.

9.
Exp Biol Med (Maywood) ; 241(11): 1195-201, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-27048556

RESUMEN

Nicotinic acid (NA) acting as the precursor of NAD(+)/NADH and NADP(+)/NADPH, participates in many biochemical processes, e.g. lipid metabolism. The main purpose of this study was to investigate the effects of dietary NA on carcass traits, meat quality, blood metabolites, and fat deposition in Chinese crossbred finishing steers. Sixteen steers with the similar body weight and at the age of 24 months were randomly allocated into control group (feeding basal diet) and NA group (feeding basal diet + 1000 mg/kg NA). All experimental cattle were fed a 90% concentrate diet and 10% forage straw in a 120-day feeding experiment. The results showed that supplemental NA in diet increased longissimus area, intramuscular fat content (17.14% vs. 9.03%), marbling score (8.08 vs. 4.30), redness (a*), and chroma (C*) values of LD muscle, but reduced carcass fat content (not including imtramuscular fat), pH24 h and moisture content of LD muscle, along with no effect on backfat thickness. Besides, NA supplementation increased serum HDL-C concentration, but decreased the serum levels of LDL-C, triglyceride, non-esterified fatty acid, total cholesterol, and glycated serum protein. In addition, NA supplementation increased G6PDH and ICDH activities of LD muscle. These results suggested that NA supplementation in diet improves the carcass characteristics and beef quality, and regulates the compositions of serum metabolites. Based on the above results, NA should be used as the feed additive in cattle industry.


Asunto(s)
Dieta/métodos , Grasas/metabolismo , Hipolipemiantes/administración & dosificación , Metabolismo de los Lípidos , Carne/análisis , Niacina/administración & dosificación , Animales , Bovinos , Suplementos Dietéticos , Carne Roja
10.
Exp Biol Med (Maywood) ; 240(9): 1152-7, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25526906

RESUMEN

An experiment was conducted to determine the effects of soy isoflavone daidzein on carcass characteristics, fat deposition, meat quality, and blood metabolites in finishing steers. Fourteen crossbred steers were used in a 120-d finishing study. These steers were stratified by weight into groups and randomly allotted by group to one of two dietary treatments: (1) control and (2) daidzein (500 mg/kg concentrate). The steers were fed a 90% concentrate diet. Supplemental daidzein did not affect slaughter weight, hot carcass weight, and dressing percentage, but tended to reduce fat proportion (not including intramuscular fat) in carcass and backfat thickness of steers. The carcass bone proportion was greater in steers fed daidzein diets than those fed control diets. Daidzein supplementation reduced pH at 24 h after slaughtered and moisture content and increased isocitrate dehydrogenase activity, fat content (16.28% and 7.94%), marbling score (5.29 and 3.36), redness (a*), and chroma (C*) values in longissimus muscle relative to control treatment. The concentrations of blood metabolites including glucose, blood urea nitrogen, triglyceride, total cholesterol, non-esterified fatty acid, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were all lower in steers fed daidzein diets than those fed control diets. Current results suggest that supplemental daidzein can affect lipid metabolism, increase intramuscular fat content and marbling score, and improve meat quality in finishing steers. Daidzein should be a promising feed additive for production of high-quality beef meat.


Asunto(s)
Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/crecimiento & desarrollo , Bovinos/crecimiento & desarrollo , Bovinos/metabolismo , Suplementos Dietéticos , Calidad de los Alimentos , Isoflavonas/administración & dosificación , Carne , Tejido Adiposo/metabolismo , Alimentación Animal , Animales , Isocitrato Deshidrogenasa/metabolismo , Lípidos/sangre , Lipogénesis/efectos de los fármacos , Masculino , Carne/análisis , Carne/normas , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/crecimiento & desarrollo , Músculo Esquelético/metabolismo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...