2023, 12(5):1-11. DOI: 10.12146/j.issn.2095-3135.20221027001
Abstract:The progress on the integrated circuits promotes the development of chips towards high integration and high performance. The resulting high heat flux brings serious challenges to the thermal management of chips. Polymers are favored to be used as materials for the purpose of heat dissipation since they have the advantages of excellent mechanical properties characteristic of softness and the ease of processibility. Limited to the low intrinsic thermal conductivity of polymers, filling highly thermally conductive fillers to fabricate polymer-based composites with high thermal conductivity is the currently main approach to realize the commercial applications. This paper reviewed the advances and applications in liquid metal-filled polymer-based thermally conductive materials. Based on the previous work, the distribution of liquid metal in the polymer matrix can be classified into three classes including discontinuous distribution, unidirectional continuous distribution and three-dimensional continuous distribution. The heat transfer mechanism of thermal interface materials, polymer-based liquid metals, methods of fabrication, thermally conductive properties and technical bottleneck of these composites with different distribution of liquid metal have been introduced. At last, the outlook on the future studies on the liquid metal-filled polymer-based thermally conductive materials has also been proposed.
2023, 12(5):12-26. DOI: 10.12146/j.issn.2095-3135.20221103001
Abstract:After low temperature sintering, nano Cu paste produces the homogeneous interconnection structure with high temperature resistant, high electrical conductivity and thermal conductivity, which can not only avoid service reliability with the bridging problems caused by short circuit and electromigration of tin based solder layer and sintered Ag layer, but also solve the problem of thermal expansion coefficient mismatch of heterogeneous interconnection structure, and has important application value in integrated circuits and power device packaging. In recent years, the sintering interconnection technology of nano Cu paste has made significant research progress in the stability of Cu nanoparticles and low-temperature sintering performances. However, compared with the sintering interconnection technology of nano Ag paste, it still has much room for improving the stability, low temperature sintering performance and reliability of nano Cu paste. This paper describes the important research progress of nano Cu paste sintering interconnection technology from the sintering interconnection mechanism, sintering process optimization, Cu nanoparticle surface modification, nano Cu based composite paste, interconnection reliability, and packaging application, and prospects the follow-up technology development and research ideas.
2023, 12(5):27-40. DOI: 10.12146/j.issn.2095-3135.20221208001
Abstract:The integration and miniaturization of semiconductor devices have led to a significant increase in heat dissipation issues. The continuous accumulation of heat threatens the performance, stability and lifespan of electronics, making it imperative to enhance the heat dissipation capability of electronic devices to ensure their stable operation. In recent years, diamond has emerged as a highly efficient heat dissipation substrate with numerous unparalleled advantages. This paper provides a comprehensive review of the latest research on diamond as a heat sink for high-power semiconductor devices and briefly discusses the methods of connecting diamond to semiconductor devices. Additionally, the current technical challenges and promising development direction for diamond-based semiconductor devices are discussed.
2023, 12(5):41-50. DOI: 10.12146/j.issn.2095-3135.20230331001
Abstract:A thermoelectric energy conversion system could realize a direct conversion between thermal and electrical energy. The thermoelectric module composes a thermal resistance network with the hot and cold side heat exchangers within an integrated thermoelectric system. The heat transfer between the network and the heat source/sink is critical to the system performance. In this paper, the effect of external heat transfer on the system internal temperature distribution is analyzed based on the coupled heat transfer relationship among different nodes in the thermal resistance network, and a set of analytical formulae of the system performance in practical thermal environments is derived. Furthermore, a direct relationship between the external heat transfer conditions and the peak output power of the system is uncovered, and a general strategy for quickly designing thermoelectric energy conversion systems is proposed.
2023, 12(5):51-61. DOI: 10.12146/j.issn.2095-3135.20230403001
Abstract:Chemerin, derived from tazarotenib-induced gene 2 (TIG2), is an endogenous ligand for the orphan G protein-coupled receptor chemokine-like receptor 1 (CMKLR1). Chemerin/CMKLR1 signaling system plays an important role in multiple tissues and organs, and there are multiple chemerin isoforms in vivo due to the C-terminal proteolysis by several proteases. This paper predicted and modeled the structure of six isoforms of chemerin by Alphafold2, and modeled three active isoforms in complex with CMKLR1, to elucidate the different binding sites of different isoforms. Additionally, the known small molecule antagonist of CMKLR1, 2-(α-naphthoyl) ethyltrimethylammonium iodide (α-NETA), was also modeled to dock with CMKLR1, and the binding sites of α-NETA with CMKLR1 were analyzed. From the protein molecular structure level, our results provide: (1) The mode of interaction between active chemerin and CMKLR1；(2) The mode of interaction between α-NETA and CMKLR1. This study provides theoretical basis and experimental basis for the design of targeted drugs for CMKLR1.
2023, 12(5):62-75. DOI: 10.12146/j.issn.2095-3135.20230104001
Abstract:The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to notable advancements in the pharmaceutical sector regarding the development of mRNA vaccines. These vaccines have gained considerable attention given their straightforward production process, improved safety profile compared to DNA vaccines, and efficient expression of mRNA-encoded antigens within cells. In addition, mRNA vaccines offer the advantage of not requiring transcription within the nucleus, thereby eliminating the risk of integration into the host genome. Nevertheless, mRNA vaccines also have limitations, such as possible allergy, kidney failure, and other serious side effects, or may rapidly degrade after injection or cause a cytokine storm. These factors present substantial challenges concerning the immunogenicity and delivery of mRNA vaccines. The purpose of this article is to primarily focus on the molecular design, delivery systems, and current clinical status of mRNA vaccines, aiming to provide valuable insights for future advancements in this field.
2023, 12(5):76-91. DOI: 10.12146/j.issn.2095-3135.20230215001
Abstract:As a representative low-level vision problem, image super-resolution (SR) aims to reconstruct the high-resolution image from its low-resolution counterpart. For a long time, the analysis of SR tasks is based on the whole image, while little works observe the input partition. In this paper, we find that the restoration quality of a certain position is inseparable from its surrounding image background. This phenomenon provides us a new perspective to explain the networks by splitting the input image. We construct a new hybrid dataset, of which the foreground and background contain only one kind of texture information. And then, we prove that the similar background could benefit the network restoration. By analyzing similarity and difference between the attention mechanism and the traditional CNN network, we show that the attention structure could help the network focus on long-range effective information. Moreover, a data enhancement method to improve the network final performance and potential future works are also proposed.
2023, 12(5):92-106. DOI: 10.12146/j.issn.2095-3135.20221212001
Abstract:Patient-ventilator asynchrony (PVA) commonly occurs during mechanical ventilation. Considering the developing trend of physiological loop ventilation and weak generalization and high complexity of public methods, this paper firstly mixes different ventilation modes simultaneously as sample, and then two cross validations, Hold-out and Leave One Subject Out, are introduced to verify the feasibility of the task that classifying PVAs under hybrid ventilation modes. To solve the drawback of current models, the phase-space reconstruction-based convolutional neural network (PSR-CNN) model is proposed. During model selection, zeropadded and down sampling are applied in order to ensure that all experiments could be conducted smoothly. Results suggest that the performances of PSR-CNN have a higher accuracy and a F1-score than other algorithms. In addition, PSR-CNN shows a shorter time with regard to average training consumption. Overall, this study indicates that the proposed model has a stronger generalization and a decrease in the complexity, which shows application value and provides reference for the intelligent promotion of ventilators in engineering.
2023, 12(5):107-114. DOI: 10.12146/j.issn.2095-3135.20221228001
Abstract:This review focuses at reviewing the progress of brain-computer interface techniques that have been developed over the past several decades. In the process of translating research achievements in brainmachine interfaces into clinical medical devices, new challenges will be encountered. so the characteristics of electroencephalogram, electrocortical graph, and intracortical electrical signal commonly used in braincomputer interfaces are introduced at first. Afterwards, the decoding capability and the bidirectional closedloop of information, the stability and biocompatibility problems of designing commercial brain-computer interface products are all analyzed. Finally, the synergistic development issues of policy, funding, and technological roadmap in the industrialization process of the transformation of implantable brain-machine interfaces into medical devices are briefly reviewed.
2023, 12(5):115-124. DOI: 10.12146/j.issn.2095-3135.20230414001
Abstract:Major science and technology infrastructure is the “national weight” of China’s construction of a world science and technology power, which can sustainably promote the output of major original achievements, accelerate the integration of innovative elements and breakthrough of high-end industries. With the development of a new round of scientific and technological revolution and the advancement of economic globalization, international competition has become increasingly complex, and the development of major scientific and technological infrastructure has entered a new stage and faced new challenges. By combing and analyzing the new development situation of major science and technology infrastructure and the challenges faced by operation and management, this paper discusses the operation and management path of major science and technology infrastructure in the new era, which has reference significance for improving the construction and operation and management level of major science and technology infrastructure.