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Abstract Attaining high hydrogenation performance under mild conditions, especially at ambient pressure, remains a considerable challenge due to the difficulty in achieving efficient mass transfer at the gas-liquid-solid three-phase interface. Here, we present a zeolite nanoreactor with joint gas-solid-liquid interfaces for boosting H2 gas and substrates to involve reactions. Specifically, the Pt active sites are encapsulated within zeolite crystals, followed by modifying the external zeolite surface with organosilanes. The silane sheath with aerophilic/hydrophobic properties can promote the diffusion of H2 and the mass transfer of reactant/product molecules. In aqueous solutions, the gaseous H2 molecules can rapidly diffuse into the zeolite channels, thereby augmenting H2 concentration surround Pt sites. Simultaneously, the silane sheath with lipophilicity nature promotes the enrichment of the aldehydes/ketones on the catalyst and facilitates the hydrophilia products of alcohol rediffusion back to the aqueous phase. By modifying the wettability of the catalyst, the hydrogenation of aldehydes/ketones can be operated in water at ambient H2 pressure, resulting in a noteworthy turnover frequency up to 92.3 h−1 and a 4.3-fold increase in reaction rate compared to the unmodified catalyst.

Abstract Oryzias sinensis, also known as Chinese medaka or Chinese ricefish, is a commonly used animal model for aquatic environmental assessment in the wild as well as gene function validation or toxicology research in the lab. Here, a high-quality chromosome-level genome assembly of O. sinensis was generated using single-tube long fragment read (stLFR) reads, Nanopore long-reads, and Hi-C sequencing data. The genome is 796.58 Mb, and a total of 712.17 Mb of the assembled sequences were anchored to 23 pseudo-chromosomes. A final set of 22,461 genes were annotated, with 98.67% being functionally annotated. The Benchmarking Universal Single-Copy Orthologs (BUSCO) benchmark of genome assembly and gene annotation reached 95.1% (93.3% single-copy) and 94.6% (91.7% single-copy), respectively. Furthermore, we also use ATAC-seq to uncover chromosome transposase-accessibility as well as related genome area function enrichment for Oryzias sinensis. This study offers a new improved foundation for future genomics research in Chinese medaka.

AbstractWe used the Illumina MiSeq platform to sequence the complete mitochondrial genome of Triplophysa jianchuanensis (Cypriniformes: Cobitidae). The mitochondrial genome of T. jianchuanensis is 16,569 bp in length, and its genetic constitution and arrangement are consistent with those of the teleost taxon, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, an origin of light-strand replication, and a control region. The overall nucleotide base composition was 28.33% A, 27.25% T, 17.77% G, and 26.65% C. Phylogenetic analysis showed that T. jianchuanensis was grouped with T. venusta. These findings are valuable for further studies on the evolution, genetic diversity, and taxonomy of Triplophysa.

Salinity stress is one of the critical environmental drivers of soil organic matter (SOM) decomposition in coastal ecosystems. Although the temperature sensitivity (Q10) of SOM decomposition has been widely applied in Earth system models to forecast carbon processes, the impact of salinity on SOM decomposition by restructuring microbial communities remains uncovered. Here, we conducted a microcosm experiment with soils collected from the coastal salt marsh in the Yellow River Estuary, which is subjected to strong dynamics of salinity due to both tidal flooding and drainage. By setting a gradient of salt solutions, soil salinity was adjusted to simulate salinity stress and soil carbon emission (CO2) rate was measured over the period. Results showed that as salinity increased, the estimated decomposition constants based on first-order kinetics gradually decreased at different temperatures. Below the 20‰ salinity treatments, which doubled the soil salinity, Q10 increased with increasing salinity; but higher salinity constrained the temperature-related response of SOM decomposition by inhibiting microbial growth and carbon metabolisms. Soil bacteria were more sensitive to salinity stress than fungi, which can be inferred from the response of microbial beta-diversity to changing salinity. Among them, the phylotypes assigned to Gammaproteobacteria and Bacilli showed higher salt tolerance, whereas taxa affiliated with Alphaproteobacteria and Bacteroidota were more easily inhibited by the salinity stress. Several fungal taxa belonging to Ascomycota had higher adaptability to the stress. As the substrate was consumed with the incubation, bacterial competition intensified, but the fungal co-occurrence pattern changed weakly during decomposition. Collectively, these findings revealed the threshold effect of salinity on SOM decomposition in coastal salt marshes and emphasized that salt stress plays a key role in carbon sequestration by regulating microbial keystone taxa, metabolisms, and interactions.

Abstract Exploring the microhabitat determinants of organisms distribution and functional traits differences can help us better understand the importance of intraspecific variations in ecological niches. Investigations on animals functional niche primarily focused on differences among species and tended to neglect the potential variability within species, despite the fact that the ecological and evolutionary importance of intraspecific variations was widely recognized. In this study, we examined the influence of microhabitat features on the intraspecific variability of the distribution and functional traits of a highest elevational distributed lizard species Phrynocephalus erythrurus. To do so, field work was conducted between July and August, 2020 and August and September, 2021 in Namtso watershed in central Xizang, China. Specifically, 11 transects were sampled for P. erythrurus individuals, which were measured for a set of 10 morphological traits. Moreover, 11 microhabitat variables that potentially affect the distribution of lizards were also measured for each transect. Our results indicated that juveniles, males, and females exhibited different functional traits, allowing them to occupy distinct functional space. The distribution of juveniles, males, and females was determined by different microhabitat variables such as illuminance and air temperature. More importantly, these variables also determined the intraspecific functional traits variability in this lizard species. All of these results supported previous claims that intraspecific traits variation should be incorporated into functional ecological studies, and diverse microhabitat features should be conserved to maintain high intraspecific diversity. Future studies can focus on the food analysis to explore the linkage between functional traits and resources utilization within animal populations.

Dynamic voltage restorer (DVR) needs to turn off the anti-parallel bypass thyristor (SCR) at the output terminal when dealing with voltage sag phenomenon. When applying traditional methods to force the thyristor off, it is essential to determine the direction of thyristor current according to the sensor sampling information, which has the risk of misjudgment under actual conditions. A novel fast switching strategy (FSS) for DVR is proposed in this paper. DVR-FSS uses the current control algorithm to force off the bypass SCR, which can realize the smooth transition from bypass state to compensation state. Firstly, the basic working principle of the DVR-FSS is introduced based on which the FSS operating modes are analyzed in detail. And the mathematical model of DVR-FSS in key modes is established to analyze the influence of FSS control algorithm parameters on the dynamic or steady performance of DVR. Secondly, the modeling and quantitative analysis of the fundamental voltage drop introduced by DVR in the steady-state mode are used to explain that the impact of FSS on the primary side load supply voltage is within the acceptable range. Finally, the correctness and feasibility of the proposed FSS are fully verified by experiments, which indicate that FSS has strong robustness at the same time.

Because of the benefits of lower on-state resistance, higher operating voltage, and higher switching frequency, SiC-MOSFET has gradually become an ideal choice for the development of power converters operating in high voltage, temperature, and power density. However, the greater dv/dt and di/dt during fast switching transients in the bridge circuit may produce substantial crosstalk problems on the complementary device due to parasitic characteristics of the device itself and its package, and with the lower turn-on threshold voltage and reverse voltage withstand capability, the crosstalk voltage will directly threaten its safe operation. This paper presents the association between the crosstalk voltage and the parameters in driving circuit and device according to the theoretical analysis of the crosstalk mechanism in a half-bridge circuit and based on the analysis, a gate driver circuit using auxiliary low-power Si-MOSFET are proposed to suppress the crosstalk spike without additional negative gate–source voltage or control signal and can be implemented with low cost and less complexity. The operation principle and parameter design of the key components are analyzed later. Finally, the simulation and experiment results show that proposed active clamped gate driver is effective at suppressing crosstalk.

In this paper, a three-phase unbalance compensation device with two-module interleaved parallel structure is proposed, which can reduce the harmonic of output voltage and output ripple current. Meanwhile, by using SiC-MOSFET as the switching device, the switching frequency of the device has been increased to 50 kHz to increase the harmonic frequency of the output voltage. With the above two designs, only a single L filter can be used to effectively filter the output voltage harmonics of the inverters, and the detection and compensation accuracy is also optimized. A 50 kVA prototype has been fabricated based on the theories above, which is at least half smaller than a conventional device of the same capacity. The PI + repeat controller (RC) is used to achieve the none-static-error tracking of sinusoidal signals, so as to achieve a good compensation effect.

The interleaved inverter with simple structure, low output ripple, and flexible expansion has been widely used. A current control method for an interleaved active power filter (APF) with SiC-MOSFETs was proposed, which can compensate harmonic accurately with low output switching ripple. A mathematical model of a two-level interleaved inverter with two-module parallel was discussed. According to the mathematical model of the interleaved topology, a composite current controller with the fast repetitive control (FRC) as the outer loop and the PI controller as the inner loop is designed. The control method proposed is implemented on a 380V/75 A APF with a switching frequency of 50 kHz. In the experiments, The THD of grid current drops from 30.0% to 4.1%, and the time of dynamic full response is 10 ms that is half of the grid period, which verifies the feasibility of the interleaved APF and its control method.

Voltage sag is an important problem that causes power quality degradation, and the premise of solving the problem of voltage sag is to detect the depth of voltage sag accurately and quickly. Based on the past research on voltage sag detection, this paper proposes a voltage sag detection method that combines second order generalized integrator and delay transform method. Use the second order generalized integrator as the phase-locked loop and filter to extract the grid voltage phase angle and grid voltage fundamental wave, and then construct the quadrature component of the grid voltage fundamental wave by delaying a small angle. Square and square root calculation to quickly obtain voltage sag information. At the same time, the voltage sag information is used as the control signal of the second order generalized integrator to solve the problem of long response time of the second order generalized integrator. In this way, the interference of harmonics, zero-sequence and negative-sequence voltages on sag detection is excluded, and the rapidity of sag detection is ensured. Simulation and experiments show that the method can accurately and quickly determine the voltage sag depth.

Using clean solar energy to reduce CO2 into value-added products not only consumes the over-emitted CO2 that causes environmental problems, but also generates fuel chemicals to alleviate energy crises. The photocatalytic CO2 reduction reaction (PCO2RR) relies on the semiconductor photocatalysts that suffer from high recombination rate of the photo-generated carriers, low light harvesting capability, and low stability. This review explores the recent discoveries on the novel semiconductors for PCO2RR, focusing on the rational catalyst design strategies (such as surface engineering, band engineering, hierarchical structure construction, single-atom catalysts, and biohybrid catalysts) that promote the catalytic performance of semiconductor catalysts on PCO2RR. The advanced characterization techniques that contribute to understanding the intrinsic properties of the photocatalysts are also discussed. Lastly, the perspectives on future challenges and possible solutions for PCO2RR are presented.

Widely applied in medical, industrial, and military fields, the high-voltage power supply based on LCC resonant converter (LCC) is ought to establish tens kilovolts of output voltage within milliseconds according to many standards. And any overshoot during this start-up process is not allowed because of the issue or even deadly consequence it may lead. Traditional linear control schemes are powerless to fulfill these two conflicting requirements, especially for the LCC with nonlinear gain characteristics. In this paper, a multi-segment fuzzy control is proposed to tackle this problem. Firstly, the nonlinear gain curve of LCC is piecewise linearized based on its large-signal model, and the control requirements for different segments are determined. Then the control parameters for each part are selected by an off-line fuzzy algorithm. The allowed minimum frequency during the start-up is also piecewise linearized so that the gain ability of LCC is utilized. Finally, the proposed control scheme is verified with an 80kW/150kV X-ray power supply. A low-cost controller is used to implement the start-up control scheme since the control parameters can be pre-calculated and stored in the controller. Compared with the commonly used linear PI control, the non-overshoot start-up time with the proposed control scheme is reduced by more than 60%.

Battery energy storage system is an attractive solution for stand-alone microgrid to make up the intermittent power of renewable energy sources. However, most studies on energy management are focused on the one-battery-unit condition while two or more battery units are recommended for system redundancy. In this paper, a coordinated energy management scheme has been proposed for an islanded microgrid, which consists of multiple renewable energy sources, battery energy storage units with different capacity and auxiliary sources such as diesel generators. The scheme aims at global optimization for power control as well as the improvement of security and economy of system, which takes into account both the state of charge (SOC) constraint of battery units and the global optimization of maximum available power of distributed generations. In order to achieve the SOC balance, the idea of hierarchical processing is adopted that the multi-battery system has been classified into various charging/discharging priority based on the SOC and capacity of single unit. Furthermore, the maximal utilization of renewable energy and the minimal run time of auxiliary units are realized under the premise of satisfying the load demand. The effectiveness and functions of the proposed energy management scheme is verified by simulation results.

The switching frequency of traditional active power filter (APF) is usually between 10 kHz and 20 kHz. To better suppress switching subharmonics, the output filters of APFs usually use LCL-filters. However, LCL-filters not only have complex parameter design but also introduce resonance points, which complicate the design of the circuit and control algorithm of APFs. In this paper, SiC-MOSFET is used as the power device of APF, the switching frequency of APF is increased to 50 kHz. In this case, using L-filter instead of LCL-filter can also suppress the switch subharmonics to a smaller level, which simplifies the circuit design and control algorithm design at the same time. In addition, when the sampling frequency and switching frequency are higher, the sampling points and switching times in a power frequency cycle increase exponentially, so the accuracy of harmonic extraction and output current control will be higher. Then, the common harmonic extraction algorithms of APFs, sliding window discrete Fourier transform (SDFT) and current control algorithm, repetitive control (RC), are analyzed in the frequency domain. A modified half-cycle SDFT and half-cycle RC are proposed, which reduces the inherent delay of the algorithms by half, and reduces the dynamic response time of APFs from two to one power frequency cycle, thus improving the dynamic response performance of APFs.

It is necessary to design a heat sink according to the losses of chips in the application of power chips to maintain the temperature of the chip junction at a low level. Since multiple power chips are distributed on the same heat sink, the surface temperature of the heat sink is unevenly distributed, the chips located at the air outlet need to withstand higher temperatures. In order to describe the surface temperature of the heat sink accurately, a novel comprehensive thermal resistance of the forced air cooling system for multi-power chips was proposed. A temperature rise test by a static var generator (SVG) prototype was designed to prove the accuracy of the model proposed. The thermal resistance error of the model proposed in this paper is only 2%. Comparing with two traditional thermal models, the accuracy of the novel thermal resistance model is improved by more than 20%.

The relationship between Cd and soil phosphatase activity has been given some concerns due to serious soil Cd contamination. However, the effects of high-risk Cd pollution on the soil phosphorus mineralization process are still kept unclear in reclaimed coastal wetlands. Here, we investigated the impacts of Cd additions at three levels on phosphorus mineralization and phosphatase activities in reclaimed coastal wetland soils with different reclamation ages (e.g., 100-year, 40-year, and 10-year) in the Pearl River Estuary by a 40-day laboratory incubation experiment. The results showed that lower soil phosphatase activity was observed in the reclaimed wetlands with longer reclamation age, which led to the lower increase in cumulative net phosphorus mineralization and Occluded P. High Cd exposure facilitated the phosphatase activities and phosphorus mineralization through the promotion of Occluded P and Al/Fe-P contents in the 100-year and 10-year reclaimed wetland soils, respectively. The addition of the low-dose of Cd to the soil inhibited phosphorus mineralization in the middle of incubation in 40-year reclaimed wetland soils, while the high-dose Cd addition had little effect. The findings of this work indicate that the older reclaimed wetlands might have lower phosphorus mineralization potentials, while higher Cd pollution might lead to soil phosphorus loss by improving phosphorus mineralization in reclaimed coastal wetlands.

The giant freshwater prawn (GFP) Macrobrachium rosenbergii is a commercially important cultured species that originates from tropical and subtropical regions and has poor cold tolerance. This study investigated the species’ cold tolerance and regulation patterns of the related response genes, using GFP juveniles subjected to extreme low-temperature treatment. The water temperature was decreased from 26 °C at a rate of approximately 1 °C every 4 h until all prawns died. The temperatures resulting in lowest LT50 (lethal temperature at which 50% prawn die) and lowest lethal temperature were approximately 12.5 °C and 11.5 °C, respectively. Phenotypic traits and hardness of the exoskeleton generally had little effect on the cold tolerance of the prawns; however, two body-weight groups showed a highly significant difference (P

Selective harmonic elimination (SHE) technique has drawn tremendous interests for its superior harmonic performance, especially in high power devices where switching power loss and passive filter size are the main concerns. However, the drawbacks of slow dynamic response and difficulties in hardware implementation limit its engineering application. Based on a 3-level inverter, this paper analyzes the dynamic response of SHE. A system model is established and an improved method of updating the switching angles at sampling frequency is proposed. And a combination of notch filters and low-pass filter is designed to achieve a higher system bandwidth. The dynamic response and stability of the system are analyzed in detail. In addition, the influence of control errors on steady-state performance during hardware implementation is also discussed. A simple hardware structure of a DSP with a small-scale FPGA is adopted to realize the above method. Both dynamic response and steady-state response of the improved system are analyzed and compared with the regular SHE modulation and the widely used sinusoidal pulse width modulation (SPWM). Simulation and experimental results provided that the improved method proposed in this paper retains the excellent steady-state characteristics of the regular SHE modulation, and at the same time achieves as good dynamic performance as SPWM.

This paper performs parameter optimization of proportional-integral (PI) and repetitive controller (RC) with a new objective function by adding two degrees of freedom for a three-phase boost power factor correction (PFC) rectifier. The main objectives are to optimize the multiple control loop parameters for total harmonics distortion (THD) reduction and dynamic performance indices improvement, including overshoot, rise time, and zero steady-state error. The control parameters of the three-phase boost PFC rectifier are optimized through a standard genetic algorithm. After obtaining the optimal PI and RC parameters values, fast Fourier transform and dynamic response analysis were performed using MATLAB. Moreover, separate evaluation functions are used to validate the optimal results in terms of THD reduction and dynamic performance indices improvement. Furthermore, the results are compared with the existing objective functions to show the proposed objective function superiority. Simulation results demonstrated that our proposed objective function outperforms existing objective functions to achieve optimal PI and RC parameters value. Finally, simulation results are validated through experimental results. The experimental setup includes a 5kW three-phase PFC rectifier with DSP TMS320F28335 prototype hardware to verify controller parameter performance.

In order to decipher the functional genes and reveal the molecular mechanism of gonadal development in Macrobrachium rosenbergii, a comparative transcriptome analysis was performed on the testes and ovaries at different developmental stages. A total of 146,537 unigenes with an N50 of 2008 bp and an average length of 1144 bp were obtained from the sequencing raw data via quality control and denovo assembly. Identification of differentially expressed genes (DEGs) showed that there were 339 and 468 DEGs among the different developmental stages of testes and ovaries, respectively, and 7993 DEGs between the testes and ovaries. The KEGG enrichment analysis identified 13 candidate pathways related to gonadal development, including insulin synthesis, oocyte maturation, and steroid biosynthesis, which were involved in biological processes such as regulation of hormone metabolism, sex cell proliferation and development, and amino acid metabolism. The DEGs related to the above pathways such as insulin-like growth factor 1 receptor (IGF1R), heat shock protein 90 (Hsp 90), and cyclooxygenase (COX) genes were highly expressed during yolk protein synthesis, indicating that these genes might be involved in yolk accumulation and oogenesis. Meanwhile, calmodulin (CaM) and other genes were highly expressed during spermatogenesis, suggesting that these genes might play an important role in spermatogenesis. Ten differentially expressed genes in the KEGG signaling pathway, including CRQ, COX, APP, Cdc42, Hsd17b12, Art-1, Hsp70, Hsp90, PRMT1, and GP, were selected for real-time quantitative PCR (RT- qPCR) to validate the transcriptome data, and the results showed that RT- qPCR obtained consistent results with the RNA-Seq data. The present findings provide new insights into the molecular regulation mechanism of gonadal development in M. rosenbergii.

The giant freshwater prawn (GFP), Macrobrachium rosenbergii, is one of the largest freshwater shrimps in the world, being widely cultured because of its high economic value. In this study, complete mitogenomes of two GFP individuals from different selective breeding populations, ‘South Taihu No.2’ (ST) and ‘Shufeng’ (SF), were newly sequenced, compared with each other, and with those of other published Macrobrachium species. The total length is 15,767 bp (ST) and 15,766 bp (SF), including 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and one control region. The phylogenetic analyses based on whole mitogenome sequences suggest that ‘Shufeng’ has a slightly distant relationship with ‘South Taihu No.2’, with a pairwise genetic distance of 0.011. This study can provide a genetic background for the GFP selective breeding, and add significantly to the knowledgebase regarding crustacean biology and aquaculture as well.

Voltage sag detection is utilized to capture the sag occurrence moment and calculate the sag depth of power grid voltage in real time, so as to generate reference voltage for controlling voltage interactive equipment such as dynamic voltage restorers (DVRs). However, the traditional voltage sag detection methods based on synchronously rotating frames (SRFs) are unable to acquire high-precision sag information under nonideal grid conditions such as unbalance or harmonic interference. In order to enhance the immunity of the sag detection, a method based on a selective harmonic extraction algorithm (SHEA) is proposed in this paper. Firstly, the state-space model of SHEA is established using discrete orthogonal basis to decouple and separate the signal of target frequency and the signal of interference frequency. The controllability, stability and convergence of SHEA are analyzed theoretically and serve as the criteria for parameter tuning. Moreover, a gain compensator (GC) is used to improve the low and middle frequency gains of the voltage sag detection method based on SHEA so that the dynamic response speed for sag judgment can be optimized quantitatively. The simulation results indicate that the proposed voltage sag detection method has good dynamic and steady-state performance under nonideal power grid conditions such as unbalanced sag, frequency drift, phase variation and harmonic interference.

In this paper a high step-up dc-dc voltage converter is proposed. The proposed converter employs coupled inductors and voltage extension capacitors for obtaining a high voltage gain. The coupled inductors and extension capacitors are merged in traditional interleaved boost converters to get the additional advantage of high step-up voltage conversion ratio and reduced voltage stress on switches along with existing features of interleaved boost converters. The main operating principle of the proposed converter is discussed and the key principle waveforms and equations are analysed. A simulation in PSIM is carried out for the proposed converter as well as traditional interleaved boost converter for the same parameters which shows that the proposed converter has better performance as compared to the traditional interleaved boost converter. Finally, an experiment is carried on a 32 W, 20 V input, 160 V output prototype in the laboratory for experimental validation of the proposed converter. Important future directions have also been given for future research on the proposed topology.

The complete mitochondrial genome of Discogobio macrophysallidos was first determined and analyzed in this work. Its mitochondrial genome is 16,593 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a non-coding control region, and its gene order was consistent with other fishes. Phylogenetic analysis showed that D. macrophysallidos were clustered with other three species of Discogobio. The complete mitogenome of D. macrophysallidos provides new molecular data for the further phylogenetic study of the genus of Discogobio.

As a programmed necrotic cell death, necroptosis has the intrinsic initiators, including receptor-interacting serine/threonine-protein kinase 1 (RIPK1), RIPK3 and mixed-lineage kinase domain-like protein (MLKL), which combine to form necroptotic signaling pathway and mediate necroptosis induced by various necroptotic stimuli, such as tumor necrosis factor (TNF). Although chemical inhibition of RIPK1 blocks TNF-induced necroptosis, genetic elimination of RIPK1 does not suppress but facilitate necroptosis triggered by TNF. Moreover, RIPK3 has been reported to mediate the RIPK1-independent necroptosis, but the involved mechanism is unclear. In this study, we found that TRADD was essential for TNF-induced necroptosis in RIPK1-knockdown L929 and HT-22 cells. Mechanistic study demonstrated that TRADD bound RIPK3 to form new protein complex, which then promoted RIPK3 phosphorylation via facilitating RIPK3 oligomerization, leading to RIPK3-MLKL signaling pathway activation. Therefore, TRADD acted as a partner of RIPK3 to initiate necroptosis in RIPK1-knockdown L929 and HT-22 cells in response to TNF stimulation. In addition, TRADD was critical for the accumulation of reactive oxygen species (ROS), which contributed to RIPK1-independent necroptosis triggered by TNF. Collectively, our data demonstrate that TRADD acts as the new target protein for TNF-induced RIPK3 activation and the subsequent necroptosis in a RIPK1-independent manner.

Gallium nitride (GaN) high-electron-mobility transistor (HEMT) with the merits of the fast switch speed, low on resistance and low switch loss is applicable to high-frequency LLC converters. However, voltage stress and ringing problems during the fast switching transient have retarded the promotion of switch speed and prolonged the design cycles. This study proposed an economic and time-saving virtual prototype based LLC converter design method, based on which the voltage stress and ringing problem can be analysed and suppressed by iteration design. The virtual prototype comprises of compact GaN HEMT device model and accurate circuit model. The correctness and effectiveness of the virtual-prototype-based design method is verified with well matching simulation and experiment waveforms.

Aiming at the problems emerging in a pulse width modulation (PWM) drive system with long cables, the accurate modeling of power cables is the premise for predicting and analyzing these relevant phenomena, and a proper filter design is the key solution to these problems. This paper proposes high-frequency cable models to represent these frequency-dependent characteristics, especially for the high-frequency resistance of cables, which is an easily overlooked factor that determines the damping of overvoltage. The proposed models can be used for accurately representing the cable characteristics in a wide frequency range, and correctly simulating the differential mode (DM) overvoltage and common mode (CM) current, including the peak value, oscillation frequency, and damping of the transient waveform. In addition, improved filter networks are proposed to suppress the DM voltage and CM current, with the merit of low losses, small volume, and excellent abilities for suppressing overvoltage. The proposed cable models and the filter design were validated in a 750 W PWM drive system with 200 m power cables.

Research on applying selective harmonic elimination pulse width modulation (SHE-PWM) to high power converters has drawn tremendous interest, due to the advantages of low switching frequency and high output harmonic performance. In the fields of high power converters such as variable speed traction motor drives and static synchronous compensators (STATCOM), the adoption of high voltage but slow speed semiconductor devices, i.e., IGBT/IGCT, results in a longer dead time of several microseconds, which leads to a motor vibration in the former case or the distortion of grid current in the latter case. This paper analyzes in detail the mechanism of the dead-time effect on 3-level SHE-PWM with different operating conditions considered. For the first time, a general mathematical model describing the relationship between the dead time and harmonic distribution of SHE-PWM wave is established. Based on which an open-loop compensation method by inserting a margin time into the effective switching angles is proposed. Furthermore, a closed-loop controller that implements online adaptive adjustment of the margin time is designed in case of a variable frequency application. The effectiveness of the proposed method in different scenarios is verified through simulation results.

OBJECTIVE:The purpose of this study was to observe left ventricular function during acute high-altitude exposure in a large group of healthy young males. METHODS:A prospective trial was conducted in Szechwan and Tibet from June to August, 2012. By Doppler echocardiography, left ventricular function was examined in 139 healthy young Chinese men at sea level; within 24 hours after arrival in Lhasa, Tibet, at 3700 m; and on day 7 following an ascent to Yangbajing at 4400 m after 7 days of acclimatization at 3700 m. The resting oxygen saturation (SaO2), heart rate (HR) and blood pressure (BP) were also measured at the above mentioned three time points. RESULTS:Within 24 hours of arrival at 3700 m, the HR, ejection fraction (EF), fractional shortening (FS), stroke volume (SV), cardiac output (CO), and left ventricular (LV) Tei index were significantly increased, but the LV end-systolic dimension (ESD), end-systolic volume (ESV), SaO2, E/A ratio, and ejection time (ET) were significantly decreased compared to the baseline levels in all subjects. On day 7 at 4400 m, the SV and CO were significantly decreased; the EF and FS Tei were not decreased compared with the values at 3700 m; the HR was further elevated; and the SaO2, ESV, ESD, and ET were further reduced. Additionally, the E/A ratio was significantly increased on day 7 but was still lower than it was at low altitude. CONCLUSION:Upon acute high-altitude exposure, left ventricular systolic function was elevated with increased stroke volume, but diastolic function was decreased in healthy young males. With higher altitude exposure and prolonged acclimatization, the left ventricular systolic function was preserved with reduced stroke volume and improved diastolic function.

High step-up dc-dc converter is an essential part in several renewable energy systems. In this paper, a new topology of step-up dc-dc converter based on interleaved structure is proposed. The proposed converter uses three energy storing capacitors to achieve a high voltage gain. Besides the high voltage gain feature, the proposed converter also reduces the voltage stress across the semiconductor switches. This helps in using low rating switching devices which can reduce the overall size and cost of the converter. The operating principle of the proposed converter is discussed in detail and its principle waveforms are analyzed. An experiment is carried out on a 20 V input, 130 V output, and 21 W power prototype of the proposed converter in the laboratory to verify the performance of the proposed converter. An efficiency of 91.3% is achieved at the rated load.

Celastrol, a tripterine derived from the traditional Chinese medicine plant Tripterygium wilfordii Hook F. ("Thunder of God Vine"), has been reported to have multiple effects, such as anti-inflammation, suppression of tumor angiogenesis, inhibition of tumor growth, induction of apoptosis and protection of cells against human neurodegenerative diseases. However, the mechanisms that underlie these functions are not well defined. In this study, we reported for the first time that Celastrol could induce HIF-1α protein accumulation in multiple cancer cell lines in an oxygen-independent manner and that the enhanced HIF-1α protein entered the nucleus and promoted the transcription of the HIF-1 target genes VEGF and Glut-1. Celastrol did not influence HIF-1α transcription. Instead, Celastrol induced the accumulation of the HIF-1α protein by inducing ROS and activating Akt/p70S6K signaling to promote HIF-1α translation. In addition, we found that the activation of Akt by Celastrol was transient. With increased exposure time, inhibition of Hsp90 chaperone function by Celastrol led to the subsequent depletion of the Akt protein and thus to the suppression of Akt activity. Moreover, in HepG2 cells, the accumulation of HIF-1α increased the expression of BNIP3, which induced autophagy. However, HIF-1α and BNIP3 did not influence the cytotoxicity of Celastrol because the main mechanism by which Celastrol kills cancer cells is through stimulating ROS-mediated JNK activation and inducing apoptosis. Furthermore, our data showed that the dose required for Celastrol to induce HIF-1α protein accumulation and enhance HIF-1α transcriptional activation was below its cytotoxic threshold. A cytotoxic dose of Celastrol for cancer cells did not display cytotoxicity in LO2 normal human liver cells, which indicated that the novel functions of Celastrol in regulating HIF-1 signaling and inducing autophagy might be used in new applications, such as in anti-inflammation and protection of cells against human neurodegenerative diseases. Future studies regarding these applications are required.