: Exploiting the relationship between the stacking modes of molecules and room-temperature phosphorescence (RTP) performance is of great important to design afterglow materials. A series of coordination polymers base on carbazole–isophtalic acid are synthesized. These compounds exhibit stacking-dependent RTP. It reveals that the phosphorescence efficiency is not proportional to the overlap of p–p stacking, the triplet excited states of discrete dimer mode rather than H-aggregation can dominate the generation of room-temperature phosphorescence. Besides, compounds 1 and 2 exhibit obvious time-dependent RTP with the afterglow color from orange to green, and show white-light emission owing to fluorescence and phosphorescence dual emission. These results indicate that coordination induction is an efficient approach to regulate the aggregation of chromophores, further modulate the room-temperature phosphorescence.

Xaa-Pro dipeptidase (XPD, EC 3.4.13.9; also known as prolidase) catalyzes the hydrolysis of iminopeptide bond in the trans Xaa-Pro dipeptides (Xaa represents any amino acid except proline), which makes it find wide applications in food, medical and environmental protection fields. In the present study, a novel Xaa-Pro dipeptidase from Aspergillus phoenicis ATCC 14332 (ApXPD) was molecularly and biochemically characterized. Reclassification based on phylogenetic analysis and version 12.5 MEROPS database showed that this enzyme was the only fungal XPD in the unassigned subfamily which shared the highest sequence similarity with Xanthomonas campestris prolidase but not with that from the more related fungal species A. niudulans. As compared with other prolidases, ApXPD also contained an N-terminal tail (residues 81-89) and an additional region (PAPARLREKL), and used a different arginine residue for dipeptide selectivity. After heterologous expression and partial purification, recombinant ApXPD was highly active and stable over the alkaline range from 8.5 to 10.0, with a maximum activity at pH 9.0 and more than 80% activity retained after 1-h incubation at pHs of 8.5-10.0 (55oC). It also had an apparent optimum temperature of 55oC and remained stable at 20-30oC. Moreover, this enzyme was a cobalt dependent prolidase that only cleaved dipeptides Lys-Pro, Gly-Pro and Ala-Pro rather than other dipeptides, tripeptides and tetrapeptides. All these distinct features make A. phoenicis ATCC 14332 XPD unique among currently known prolidases, thus defining a novel Xaa-Pro dipeptidase subfamily.

This article addresses the problem of contact voltage increase caused by the low frequency oscillation of the train-grid system in the phase-separation process of the EMU. The article establishes the EMU-contact line-traction substation model, reveals the mechanism of low-frequency oscillation, and obtains the relationship between the separation phase angle of the pantograph with line and low-frequency oscillations. Methods to suppress the over-voltage during the low-frequency oscillation are proposed. The study shows that when the power phase angle of the pantograph-line separation is within the range of 60°~90° and 240°~270°, the voltage amplitude in the neutral zone is larger, the maximum amplitude can reach 52.2kV, and low-frequency oscillation will occur in the neutral zone. When low frequency oscillation occurs, the contact line voltage in the neutral zone is mainly 1/3 power frequency (16.7Hz). After installing an RC suppression device in the neutral zone, when the EMU enters the neutral zone, the absolute value of the voltage peak drops to below 20 kV. Compared with the situation where the suppression device is not connected, the absolute value of the voltage peak is reduced by nearly 60%. The study provides a basis for the design of the neutral zone of the contact line and the selection of the high-voltage equipment of the EMU.

Abstract: Circuit breakers are affected by multiple lightning strikes after the breaker has been tripped and can break down again, which will reduce the life of the circuit breaker and threaten the stable operation of the power system. Aiming at this problem, the paper obtained the temperature diffusion process of the inrush current process of circuit breaker opening and breaking through the schlieren technique, and combined with the existing image recognition technology to obtain the temperature characteristics of the airflow in the air gap of the contact, and the characteristics of the airflow flow. The results of the study show that the circuit breaker breakdown process generates a shock wave with a velocity approximately equal to the speed of sound under the same conditions. The maximum velocity of the airflow boundary diffusion is about 1/4 of the speed of sound under the same condition, and it decays very fast, reducing to the airflow drift velocity within 10ms after breakdown. The maximum temperature of the thermals is concentrated between 6000 and 8000 K and the temperature change is approximately inversely proportional to the square of time. The research provides the basis for the design of circuit breaker contact structure, opening speed optimization method, interrupter chamber and insulation design optimization.

This study aimed to develop extended–release tablets containing 25 mg IMM−H014, an original drug formulated by a direct powder pressing method based on pharmaceutical–grade hydrophilic matrix polymers, such as hydroxypropyl methylcellulose, to establish an in vitro−in vivo corre-lation (IVIVC) to predict bioavailability. The tablets’ mechanical properties and in vitro and in vivo performance were studied. The formulation was optimized using a single factor experiment and the reproducibility was confirmed. The in vitro dissolution profiles of the tablet were de-termined in five dissolution media, in which the drug released from the hydrophilic tablets fol-lowed Ritger–Peppas model kinetics in 0.01 N HCl medium for the first 2 h, and in phosphate buffer saline medium (pH 7.5) for further 24 h. Accelerated stability studies (40°C, 75% relative humidity) proved that the optimal formulation was stable for 6 months. The in vivo pharmaco-kinetics study in beagle dogs showed that compared to the IMM−H014 immediate release prep-aration, the maximum plasma concentration of the extended release (ER) preparation was sig-nificantly decreased, while the maximum time to peak and mean residence time were significantly prolonged. The relative bioavailability was 97.9% based on an area under curve, indicating that the optimal formulation has an obvious ER profile. And a good IVIVC was established, which could be used to predict in vivo pharmacokinetics from the formulation composition.

Acetamiprid is a broad-spectrum neonicotinoid insecticide used in agriculture to control aphids. While recent studies have documented resistance to acetamiprid in several aphid species, the underlying mechanisms are still not fully understood. In this study, we analyzed the transcriptome and metatranscriptome of a laboratory strain of the pea aphid, Acyrthosiphon pisum (Harris, 1776), with reduced susceptibility to acetamiprid after nine generations of exposure to identify candidate genes and the microbiome involved in the adaptation process. Sequencing of the transcriptome of both selected (RS) and non-selected (SS) strains allowed the identification of 14858 genes and 4938 new transcripts. Most of the differentially expressed genes were associated with catalytic activities and metabolic pathways involving carbon and fatty acids. Specifically, the alcohol-forming fatty acyl-CoA reductase (FAR) and acyl-CoA synthetase (ACSF2), both involved in the synthesis of epidermal wax layer components, were significantly upregulated in RS, suggesting that adaptation to acetamiprid involves the synthesis of a thicker protective layer. Metatranscriptomic analysis revealed subtle shifts in the microbiome of RS. These results contribute to a deeper understanding of acetamiprid adaptation by the pea aphid and provide new insights for aphid control strategies.