Simulation on an Advanced Double-Sided Cooling Flip-Chip Packaging with Diamond Material for Gallium Oxide Devices.

Gallium oxide (Ga2O3) devices have shown remarkable potential for high-voltage, high-power, and low-loss power applications. However, thermal management of packaging for Ga2O3 devices becomes challenging due to the significant self-heating effect. In this paper, an advanced double-sided cooling flip-chip packaging structure for Ga2O3 devices was proposed and the overall packaging of Ga2O3 chips was researched by simulation in detail. The advanced double-sided cooling flip-chip packaging structure was formed by adding a layer of diamond material on top of the device based on the single-sided flip-chip structure. With a power density of 3.2 W/mm, it was observed that the maximum temperature of the Ga2O3 chip with the advanced double-sided cooling flip-chip packaging structure was 103 °C. Compared with traditional wire bonding packaging and single-sided cooling flip-chip packaging, the maximum temperature was reduced by about 12 °C and 7 °C, respectively. When the maximum temperature of the chip was controlled at 200 °C, the Ga2O3 chip with double-sided cooling packaging could reach a power density of 6.8 W/mm. Finally, by equipping the top of the package with additional water-cooling equipment, the maximum temperature was reduced to 186 °C. These findings highlight the effectiveness of the proposed flip-chip design with double-sided cooling in enhancing the heat dissipation capability of Ga2O3 chips, suggesting promising prospects for this advanced packaging structure.

Out-of-season spawning of largemouth bass in a controllable recirculating system.

Largemouth bass (LMB) production exceeded 0.7 million tons in 2021 and has become one of the most important freshwater aquaculture species in China. The stable and fixed culture cycle led to regular and drastic price fluctuation during the past decade. Strong price fluctuation provides opportunities and challenges for the LMB industry, and out-of-season spawning (OSS) and culture will provide technical support for the opportunities. To induce OSS at a low cost, we established a controllable recirculating system that allows precise thermo-photoperiod manipulation. In the system, four experimental groups were assigned, 18NP (18°C overwintering water temperature, natural photoperiod), 18CP (18°C overwintering water temperature, controlled photoperiod), 16CP (16°C overwintering water temperature, controlled photoperiod), and NTNP (natural water temperature and natural photoperiod), to determine the effects of chilling temperature and photoperiod on spawning performance. OSS was observed in all the experimental groups without significant differences, except NTNP. The manipulated broodstock can re-spawn 3 months later in the next spring in advance. Further analysis of the volume percentage of different stages of oocytes provides a base for excellent regression between the volume percentage of the primary growth stage, cortical alveoli stage, vitellogenesis/maturation stage, and gonadal development/maturation. The results suggest that the volume percentage of oocytes is a better indicator of gonadal development and maturation than the gonadosomatic index. We also found that LMB prefers palm fiber as a spawning nest over gravel. The findings of this work provide important technique guidance for practical OSS of the LMB aquaculture industry and standardization of ovary development and maturation in fish with asynchronous developmental oocytes.

A Simulation Optimization Factor of Si(111)-Based AlGaN/GaN Epitaxy for High Frequency and Low-Voltage-Control High Electron Mobility Transistor Application.

The effects of barrier layer thickness, Al component of barrier layer, and passivation layer thickness of high-resistance Si (111)-based AlGaN/GaN heterojunction epitaxy on the knee-point voltage (Vknee), saturation current density (Id-sat), and cut-off frequency (ft) of its high electron mobility transistor (HEMT) are simulated and analyzed. A novel optimization factor OPTIM is proposed by considering the various performance parameters of the device to reduce the Vknee and improve the Id-sat on the premise of ensuring the ft. Based on this factor, the optimized AlGaN/GaN epitaxial structure was designed with a barrier layer thickness of 20 nm, an Al component in the barrier layer of 25%, and a SiN passivation layer of 6 nm. By simulation, when the gate voltage Vg is 0 V, the designed device with a gate length of 0.15 µm, gate-source spacing of 0.5 µm, and gate-drain spacing of 1 µm presents a high Id-sat of 750 mA/mm and a low Vknee of 2.0 V and presents ft and maximum frequency (fmax) as high as 110 GHz and 220 GHz, respectively. The designed device was fabricated and tested to verify the simulation results. We demonstrated the optimization factor OPTIM can provide an effective design method for follow-up high-frequency and low-voltage applications of GaN devices.

Dynamics of transcriptome and chromatin accessibility revealed sequential regulation of potential transcription factors during the brown adipose tissue whitening in rabbits.

Brown adipose tissue (BAT) represents a valuable target for treating obesity in humans. BAT losses of thermogenic capacity and gains a "white adipose tissue-like (WAT-like)" phenotype (BAT whitening) under thermoneutral environments, which could lead to potential low therapy responsiveness in BAT-based obesity treatments. However, the epigenetic mechanisms of BAT whitening remain largely unknown. In this study, BATs were collected from rabbits at day0 (D0), D15, D85, and 2 years (Y2). RNA-sequencing (RNA-seq) and the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) were performed to investigate transcriptome and chromatin accessibility of BATs at the four whitening stages, respectively. Our data showed that many genes and chromatin accessible regions (refer to as "peaks") were identified as significantly changed during BAT whitening in rabbits. The BAT-selective genes downregulated while WAT-selective genes upregulated from D0 to Y2, and the de novo lipogenesis-related genes reached the highest expression levels at D85. Both the highly expressed genes and accessible regions in Y2 were significantly enriched in immune response-related signal pathways. Analysis of different relationships between peaks and their nearby genes found an increased proportion of the synchronous changes between chromatin accessibility and gene expression during BAT whitening. The synergistic changes between the chromatin accessibility of promoter and the gene expression were found in the key adipose genes. The upregulated genes which contained increased peaks were significantly enriched in the PI3K-Akt signaling pathway, steroid biosynthesis, TGF-beta signaling pathway, osteoclast differentiation, and dilated cardiomyopathy. Moreover, the footprinting analysis suggested that sequential regulation of potential transcription factors (TFs) mediated the loss of thermogenic phenotype and the gain of a WAT-like phenotype of BAT. In conclusion, our study provided the transcriptional and epigenetic frameworks for understanding BAT whitening in rabbits for the first time and might facilitate potential insights into BAT-based obesity treatments.

VAG: A Uniform Model for Cross-Modal Visual-Audio Mutual Generation.

Considering both audio and visual modalities is helpful for understanding a video. In the face of harsh environmental interference or signal packet loss, automatically compensating for audio and vision is a challenging task. We propose a dynamic cross-modal visual-audio mutual generation model (VAMG), which includes audio to visual conversion, visual to audio conversion, audio self-generation, and visual self-generation. VAMG jointly optimizes modal reconstruction and adversarial constraints, effectively solving the problems of structural alignment and signal compensation in incomplete videos. We conducted an instrument-oriented and pose-oriented cross-modal audio-visual mutual generation experiment on the sub-University of Rochester Musical Performance dataset to verify the effectiveness of the model.

Ultrastructural localization of ATPase in mature tracheary elements of rice (Oryza sativa L.) stamen.

The development of mature tracheary elements (TEs) of rice (Oryza sativa L. cv. Nongkeng 58s-SD) stamen from big-vacuole to trinucleate pollen stage was studied with lead phosphate--deposition technique. At big-vacuole pollen stage, mature TEs, both in filament and connective, were short of ATPase activity. However, ATPase activity appeared at binucleate pollen stage; in filament, one or two vascular bundle cell (s) next to TE degenerated earlier than the rest; and the plasma membrane of degenerating cell (DC) always exhibited high ATPase activity on condition that the adjoining TE was of fully stretched second wall; when the second wall only turned up far off DC, the plasma membrane of DC still showed high ATPase activity except on borderline between DC and TE; in connective at the same stage, TEs also exhibited high ATPase activity, but the vascular bundle cell(s) adjoining TEs degenerated much later than their counterparts in filament. At trinucleate pollen stage, materials, either with or without ATPase activity, were observed both in filament and connective TEs. The above results indicated that (some of the) materials in mature TEs come from filament DC.