A class of BVPS for first order impulsive functional integro-differential equations with a parameter

This paper is concerned with a class of boundary value problems for the nonlinear impulsive functional integro-differential equations with a parameter by establishing new comparison principles and using the method of upper and lower solutions together with monotone iterative technique. Sufficient conditions are established for the existence of extremal system of solutions for the given problem. Finally, we give an example that illustrates our results

More ConvNets in the 2020s:Scaling up Kernels Beyond 51x51 using Sparsity

Transformers have quickly shined in the computer vision world since the emergence of Vision Transformers (ViTs). The dominant role of convolutional neural networks (CNNs) seems to be challenged by increasingly effective transformer-based models. Very recently, a couple of advanced convolutional models strike back with large kernels motivated by the local-window attention mechanism, showing appealing performance and efficiency. While one of them, i.e. RepLKNet, impressively manages to scale the kernel size to 31x31 with improved performance, the performance starts to saturate as the kernel size continues growing, compared to the scaling trend of advanced ViTs such as Swin Transformer. In this paper, we explore the possibility of training extreme convolutions larger than 31x31 and test whether the performance gap can be eliminated by strategically enlarging convolutions. This study ends up with a recipe for applying extremely large kernels from the perspective of sparsity, which can smoothly scale up kernels to 61x61 with better performance. Built on this recipe, we propose Sparse Large Kernel Network (SLaK), a pure CNN architecture equipped with sparse factorized 51x51 kernels that can perform on par with or better than state-of-the-art hierarchical Transformers and modern ConvNet architectures like ConvNeXt and RepLKNet, on ImageNet classification as well as a wide range of downstream tasks including semantic segmentation on ADE20K, object detection on PASCAL VOC 2007, and object detection/segmentation on MS COCO

Sustained Release of IGF-1 by 3D Mesoporous Scaffolds Promoting Cardiac Stem Cell Migration and Proliferation

Background/Aims: C-kit-positive cardiac stem cells (CSCs) may have potential as a treatment for cardiovascular disease. However, the low survival rates of c-kit-positive CSCs present a major challenge during the transplantation process. Methods: The hierarchical structure of the 3D cell scaffold was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 adsorption-desorption isotherms. Analyses of the proliferation and migration performances of the IGF-1 scaffold on c-kit-positive CSCs were conducted by experiments including QuantiT PicoGreen dsDNA and transwell assays. Results: In this study, we synthesized for the first time a novel hierarchical macro-mesoporous silica material (denoted MS15-c) in a one-pot procedure for the release of insulin-like growth factor-1 (IGF-1) and a three-dimensional (3D) cell scaffold. Both macropores and mesopores were visible in MS15-c and enabled the sustained release of IGF-1, extending its half-life and enhancing CSC proliferation and migration. Proliferation and migration were detected by QuantiT PicoGreen dsDNA and transwell assays, respectively. Moreover, an in vivo experiment was conducted to detect heart function with the addition of MS15-c. The new strategy proposed in this paper may extend the bio-applications of 3D cell scaffolds, thus permitting the sustained release of growth factors and efficient promotion of cell proliferation. Conclusion: This work successfully demonstrated an effective strategy for the construction of MS15-c cell scaffolds with hierarchical macro-mesoporous structures. The macro-mesoporous structures gave cell scaffolds the ability to release a growth factor to facilitate cell growth, while the scaffold structure promoted cell proliferation

Insights into the senescent mechanisms of harvested strawberry fruit at the physiological, molecular and metabolic levels

Strawberry (Fragaria × ananassa) is a worldwide cultivated horticultural crop, however, its short preservative life of the harvested fruit remains a challenge to be addressed. Currently, although much progress has been made toward understanding the senescence of harvested strawberry fruit, the defined mechanisms remain unclear. Therefore, we performed a series of morphological, physiological and biochemical, as well as transcriptome and proteome analyses using the widely-cultivated strawberry 'Benihoppe' during 0−8 d at room temperature. The results showed not only the shorter storage of harvested strawberry fruit resulted from the rapid perishability, softening, and water loss, but also an increase in soluble sugars within 2 d and a coordination of ABA with JA at the early stage, BR at the middle stage and ethylene at the later stage, respectively. The RNA-seq data highlighted on ABA with NCEDs and PYLs, auxin with IAAs and AUXs, ethylene with ACSs, EIN3 and ERFs, BR with BZRs, and JA with JMTs; while proteome data highlighted on ABA with PYL/SnRK2/ABF, JA with JAR1/JAZ, GA with GID1, BR with BSK, and ethylene with ETR/CTR/EIN2, suggesting an important role of ABA, JA, and ethylene in the senescence of harvested strawberries. Interestingly, higher contents of nerolidalyl caproate and threonine represented characteristic signs of ripening and senescence. Finally, a physiological, molecular and metabolic model for strawberry fruit senescence is proposed, providing comprehensive insights into the preservative mechanisms

Heat transfer enhancement by a focused ultrasound field

A focused ultrasound field is set up in a heat transfer cavity with an elliptical cross section. A sound source and a heat source are designed at the two focus points where the sound intensity is reinforced based on the interference and standing wave criteria. The sound intensities and heat transfer coefficients of the cavity with a focused ultrasonic field and an ordinary cavity with a rectangular cross section are measured under the natural convection heat transfer regime. The distribution of the heat transfer coefficient matches the distribution of the sound intensity. The heat transfer performance is then enhanced in the cavity with a focused ultrasonic field. The cavitations and acoustic streaming characteristics in the cavity with a focused ultrasonic field and the ordinary cavity are also studied. The velocity of acoustic streaming is larger in the cavity with a focused ultrasonic field than in the ordinary cavity, and no cavitation is observed in the ordinary cavity. Although the cavitation cloud around the heat source is unfavorable for the heat transfer in the cavity with a focused ultrasonic field, the cavitations collapse and the resulting high temperature, higher pressure, and microjet effects still contribute substantially to heat transfer.ISSN:2158-322

Heat transfer enhancement by a focused ultrasound field

A focused ultrasound field is set up in a heat transfer cavity with an elliptical cross section. A sound source and a heat source are designed at the two focus points where the sound intensity is reinforced based on the interference and standing wave criteria. The sound intensities and heat transfer coefficients of the cavity with a focused ultrasonic field and an ordinary cavity with a rectangular cross section are measured under the natural convection heat transfer regime. The distribution of the heat transfer coefficient matches the distribution of the sound intensity. The heat transfer performance is then enhanced in the cavity with a focused ultrasonic field. The cavitations and acoustic streaming characteristics in the cavity with a focused ultrasonic field and the ordinary cavity are also studied. The velocity of acoustic streaming is larger in the cavity with a focused ultrasonic field than in the ordinary cavity, and no cavitation is observed in the ordinary cavity. Although the cavitation cloud around the heat source is unfavorable for the heat transfer in the cavity with a focused ultrasonic field, the cavitations collapse and the resulting high temperature, higher pressure, and microjet effects still contribute substantially to heat transfer.ISSN:2158-322

Comparative Analysis of Sugar Production Cost in Guangxi and World Major Producing Countries

Guangxi is the largest sugar producing area in China and shoulders heavy responsibilities for the development of China’s sugar industry. In recent years, China’s sugar industry has been greatly impacted by the foreign low-cost sugar industry, and the planting area of ​​sugarcane has been declining. The development foundation of the sugar industry is the sugarcane seed industry. Under the impact of foreign low-price sugar, China’s sugarcane industry is under greater pressure for development, and the sugarcane seed industry shoulders more arduous responsibilities. In order to cope with international competition, the development of Guangxi's sugarcane industry urgently needs to establish a development model oriented towards improved varieties, scale and mechanization of sugarcane, so as to promote the high-quality development of Guangxi's sugarcane industry and effectively respond to the pressure of competition in the international sugarcane industry

How the Crosslinking Agent Influences the Thermal Stability of RTV Phenyl Silicone Rubber

In this work, a thermal degradation mechanism of room temperature vulcanized (RTV) phenyl silicone rubber that was vulcanized by different crosslinking agents was discussed. Firstly, RTV phenyl silicone rubber samples were prepared by curing hydroxyl-terminated polymethyldiphenylsiloxane via three crosslinking agents, namely, tetraethoxysilane (TEOS), tetrapropoxysilane (TPOS), and polysilazane. Secondly, the ablation properties of RTV phenyl silicone rubber were studied by the muffle roaster test and FT-IR. Thirdly, thermal stability of the three samples was studied by thermogravimetric (TG) analysis. Finally, to explore the thermal degradation mechanism, the RTV phenyl silicone rubber vulcanized by different crosslinking agents were characterized by TG analysis-mass spectrum (TG-MS) and pyrolysis gas chromatogram-mass spectrum (pyGC-MS). Results showed that the thermal stability of RTV phenyl silicone rubber is related to the amount of residual Si–OH groups. The residual Si–OH groups initiated the polysiloxane chain degradation via an ‘unzipping’ mechanism