Abstract Carbon family elements (Si, Ge, Sn, Pb) have attracted a lot of attention because of their unique structural features and potential applications in microelectronics industry. Here, the ...structure, chemical stability, electronic properties, and nonlinear optical properties of neutral and charged Au@X 20 H 20 (X=Si, Ge, Sn, Pb) clusters have been systematically studied using density‐functional theory calculations. Structurally, the neutral/anionic Au@X 20 H 20 (X=Si, Ge, Sn) as well as cationic Au@Pb 20 H 20 possess Au‐endohedral (XH) 20 unit, forming fullerene‐like framework, whereas other species are Au‐doped structures with hydrogen‐bridged bond. Analysis of binding energy and HOMO‐LUMO energy gaps reveals that the charged clusters possess high chemical stabilities due to closed‐shell structures. The charge transfers from X 20 cage to Au atom, and the Au atom acts as electron acceptor. The Au atom and charged states play an important role in the structural stability, and can effectively modulate the electronic properties of clusters. Interestingly, the neutral Au@X 20 H 20 (X=Si, Sn) clusters possess large first hyperpolarizabilities, especially for Au@Sn 20 H 20 , which has remarkably giant value (~5.65×10 8 a. u.), and the enhanced NLO behaviors can be further explained by the TDDFT calculation. The work may provide a theoretical reference for further applications considered as novel cluster‐assembled nanomaterials.
Strongly fluorescent graphene quantum dots (GQDs) have been prepared by one-step solvothermal method with PL quantum yield as high as 11.4%. The GQDs have high stability and can be dissolved in most ...polar solvents. Because of fine biocompatibility and low toxicity, GQDs are demonstrated to be excellent bioimaging agents.
Glioblastoma (GBM) is one of the deadliest primary brain malignant tumors with a bleak prognosis. Craniotomy surgical resection followed by radiotherapy and chemotherapy was still the standard ...therapeutic strategy for GBM. As a target alkylating agent, temozolomide (TMZ) was utilized in the therapy of GBM for decades. However, effective treatment for GBM is stymied by rapid acquired resistance and bone marrow suppression. Here, we synthesize a tetrahedral framework nucleic acid (tFNA) nanoparticle that can carry TMZ to enhance the lethality on four GBM cell lines via activating the cell apoptosis and autophagy pathway. Our nanoparticle, namely, tFNA-TMZ, shows a more obvious efficacy in killing TMZ-sensitive cells (A172 and U87) than single-agent TMZ. Besides, tFNA-TMZ was able to attenuate drug resistance in TMZ-resistant cells (T98G and LN-18) via downregulating the expression of O6-methylguanine-DNA-methyltransferase. Furthermore, we modified the tFNA with GS24, a DNA aptamer that can specially bind to transferrin receptor in the cerebral vascular endothelial cell of mouse and enable the tFNA nanoparticle to cross the blood-brain barrier. In summary, our results demonstrated that tFNA-TMZ has a promising role as a nanoscale vehicle to deliver TMZ to enhance the efficacy of GBM.
The radiation force of modified circular Airy beams (MCAB) exerted on both a high-refractive-index particle and a low-refractive-index particle are analyzed in this paper. Our results show that the ...two kinds of particles can be simultaneously stably trapped by MCAB at different positions. Compared with the common circular Airy beams (CAB) with the same parameters, trapping forces on the two kinds of particles are greatly increased because of the enhanced abruptly autofocusing property and the appearance of hollow region in MCAB. The trapping forces can be modulated by varying parameters of MCAB, and it is important to choose appropriate parameters to trap particles in practice.
Jujube is a crop highly resistant to drought and salinity, making it one of the main fruit trees in Xinjiang. The present study evaluated the changes in the physicochemical and antioxidant activities ...of jujube fruit of eight different cultivars from Xinjiang, China. The developmental stages were selected according to the days after full bloom and fruit peel colour during ripening; these stages included young (S1), fruit core-hardening (S2), green ripening (S3), half-red maturity (S4) and complete red. In present study, different cultivars of jujube fruit showed similar chemical profiles, but their amounts showed great variation. HZ had the highest content of sugars, and JY had the highest content of cAMP and cGMP, while relatively higher levels of ascorbic acid, catechin, epicatechin, rutin, proanthocyanidin and antioxidant activity were found in 'FS' than in other cultivars, indicating that 'FS' could be used as a potential natural antioxidant. Regarding the development stages of jujube fruit, the moisture, ascorbic acid, total polyphenol, catechin, epicatechin, proanthocyanidin and rutin contents decreased during the development of all jujube cultivars, while the fructose, glucose, sucrose, cAMP, and cGMP contents greatly increased. The antioxidant activity determined by DPPH and ABTS radical scavenging decreased as the fruits matured. Therefore, the results suggest that green jujube (S1) could be used for natural antioxidants (catechin, epicatechin, proanthocyanidin) and that the advanced ripening stage(S5) is the proper picking period for fresh fruit and commercial processing.
Road boundary detection is an important part of the perception of the autonomous driving. It is difficult to detect road boundaries of unstructured roads because there are no curbs. There are no ...clear boundaries on mine roads to distinguish areas within the road boundary line and areas outside the road boundary line. This paper proposes a real-time road boundary detection and tracking method by a 3D-LIDAR sensor.The road boundary points are extracted from the detected elevated point clouds above the ground point cloud according to the spatial distance characteristics and the angular features. Road tracking is to predict and update the boundary point information in real-time, in order to prevent false and missed detection. The experimental verification of mine road data shows the accuracy and robustness of the proposed algorithm.
We have proposed a kind of modified circular Airy beam (MCAB) based upon a modification of the Fourier spectrum of circular Airy beams (CAB) in this paper. Unlike most abruptly autofocusing beams, ...the position of peak intensity of MCAB can be moved to any rings behind. Two apodization parameters are introduced to describe the propagation characteristics of MCAB. It is found that the focal position, focal trajectory and the size of focal spot do not change with the apodization parameters; but the abruptly autofocusing property will be greatly enhanced if appropriately apodization parameters are chosen. Comparing with the common CAB and the previous blocked CAB, the MCAB shows better abruptly autofocusing property. It may have more applications in various fields.
Physical activity has been shown to impact mental health in in vitro fertilization-embryo transfer (IVF-ET) patients, but the relationship between domain-specific physical activity and mental health ...in this population remains unclear. In a cross-sectional observational study, 208 patients undergoing IVF-ET with long-term ovulation induction cycles were recruited from a reproductive center. The International Physical Activity Questionnaire and the symptom checklist 90 (SCL-90) were used to assess physical activity levels and mental health status, respectively. Analyses of variance and linear regression analyses were conducted to identify the relationship between physical activity and mental health. There were differences between different physical activity level in times of transfers, years of infertility, and times of abortions. Patients with high levels of physical activity had fewer symptoms than those with low levels of physical activity. Occupation, transport and household physical activity had significant negative correlations with the respective SCL-90 factor scores. Linear regression analysis revealed that occupation physical activity was associated with lower depression and anxiety, and transport physical activity and household physical activity were associated with lower obsessive-compulsive, interpersonal sensitivity, depression, anxiety, and psychoticism scores. The study indicates that increased engagement in physical activity, specifically activities related to occupation, transportation, and household, may be associated with improved mental health among IVF-ET patients.
Accurate geographic data of slums are important for handling urban poverty issues. Previous slum mapping studies using high-resolution or very-high-resolution (HR/VHR) remotely sensed (RS) images are ...commonly not suitable for city-wide scale tasks. This study aims to efficiently generate a slum map on a city-wide scale using freely accessed multispectral medium-resolution (MR) Sentinel-2 images. Composite slum spectral indices (CSSIs) were initially proposed based on the shapes of spectral profiles of slums and nonslums and directly represent slum characteristics. Specifically, CSSI-1 denotes the normalized difference between the shortwave infrared bands and the red edge band, while CSSI-2 denotes the normalized difference between the blue band and the green band. Furthermore, two methods were developed to test the effectiveness of CSSIs on slum mapping, i.e., the threshold-based method and the machine learning (ML)-based method. Experimental results show that the threshold-based method and the ML-based method achieve intersection over unions (IoU) of 43.89% and 54.45% in Mumbai, respectively. The accuracies of our methods are comparable to or even higher than the accuracies reported by existing methods using HR/VHR images and transfer learning. The threshold-based method exhibits a promising performance in mapping slums larger than 5 ha, while the ML-based method refines mapping accuracies for slum pockets smaller than 5 ha. The threshold-based method and the ML-based method produced the slum map in Mumbai in 2 and 28 min, respectively. Our methods are suitable for rapid large-area slum mapping owing to the high data availability of Sentinel-2 images and high computational efficiency.
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