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Switching shunt capacitor banks is a challenging task for vacuum circuit breakers (VCBs). The objective of this article is to experimentally investigate the prestrike characteristics of single-break VCBs with cup-type axial magnetic field (AMF) contacts and spiral-type transverse magnetic field (TMF) contacts under inrush current conditions in four ways. These four aspects are: the prestrike gap probability distributions, the inrush current interruption phenomena, the prestrike electric field, and the contact erosion. The contact erosion is represented by the field enhancement factor $\beta $ , which is obtained by the field emission current. The experimental results show that compared with the cup-type AMF VCB, the spiral-type TMF VCB is more effective since it can reduce 47.4% of the 50% prestrike gap, $d_{50}$ , and 28.6% of the scatter in prestrike gaps, which is mainly because the spiral-type TMF VCB can effectively reduce the contact erosion caused by inrush current. The spiral-type TMF VCB can significantly reduce the occurrence probabilities of inrush current interruption. The spiral-type TMF VCB can reduce 48.6% of the 50% prestrike arc time, $t_{a50}$ . The 50% prestrike electric field, $E_{\mathrm {pre50}}$ , of the spiral-type TMF VCB is 125% higher than that of the cup-type AMF VCB. For the controlled switching of capacitor banks, the spiral-type TMF VCB is superior to the cup-type AMF VCB.

The thermal and chemical state of the early Archaean deep mantle is poorly resolved due to the rare occurrences of early Archaean magnesium-rich volcanic rocks. In particular, it is not clear whether compositional heterogeneity existed in the early Archaean deep mantle and, if it did, how deep mantle heterogeneity formed. Here we present a geochronological and geochemical study on a Palaeoarchaean ultramafic–mafic suite (3.45-Gyr-old) with mantle plume signatures in Longwan, Eastern Hebei, the North China Craton. This suite consists of metamorphosed cumulates and basalts. The meta-basalts are iron rich and show the geochemical characteristics of present-day oceanic island basalt and unusually high mantle potential temperatures (1,675 °C), which suggests a deep mantle source enriched in iron and incompatible elements. The Longwan ultramafic–mafic suite is best interpreted as the remnants of a 3.45-Gyr-old enriched mantle plume. The first emergence of mantle-plume-related rocks on the Earth 3.5–3.45 billion years ago indicates that a global mantle plume event occurred with the onset of large-scale deep mantle convection in the Palaeoarchaean. Various deep mantle sources of these Palaeoarchaean mantle-plume-related rocks imply that significant compositional heterogeneity was present in the Palaeoarchaean deep mantle, most probably introduced by recycled crustal material. Deep mantle heterogeneity and large-scale deep mantle convection has been operating since the Palaeoarchaean, according to enriched plume signatures found in a 3.45-billion-year-old ultramafic–mafic suite from the North China Craton.

Knowledge gaps of mercury (Hg) biogeochemical processes in the tropical rainforest limit our understanding of the global Hg mass budget. In this study, we applied Hg stable isotope tracing techniques to quantitatively understand the Hg fate and transport during the waterflows in a tropical rainforest including open-field precipitation, throughfall, and runoff. Hg concentrations in throughfall are 1.5–2 times of the levels in open-field rainfall. However, Hg deposition contributed by throughfall and open-field rainfall is comparable due to the water interception by vegetative biomasses. Runoff from the forest shows nearly one order of magnitude lower Hg concentration than those in throughfall. In contrast to the positive Δ199Hg and Δ200Hg signatures in open-field rainfall, throughfall water exhibits nearly zero signals of Δ199Hg and Δ200Hg, while runoff shows negative Δ199Hg and Δ200Hg signals. Using a binary mixing model, Hg in throughfall and runoff is primarily derived from atmospheric Hg0inputs, with average contributions of 65 ± 18 and 91 ± 6%, respectively. The combination of flux and isotopic modeling suggests that two-thirds of atmospheric Hg2+input is intercepted by vegetative biomass, with the remaining atmospheric Hg2+input captured by the forest floor. Overall, these findings shed light on simulation of Hg cycle in tropical forests.

Blockade of PD-1/PD-L1 interactions using PD-1/PD-L1 pathway modulators has shown unprecedented clinical efficacy in various cancer models. Current PD-1/PD-L1 modulators approved by FDA are exclusively dominated by therapeutic antibodies. Nevertheless, therapeutic antibodies also exhibit several disadvantages such as low tumor penetration, difficulty in crossing physiological barriers, lacking oral bioavailability, high manufacturing costs, inaccessible to intracellular targets, immunogenicity, immune-related adverse events (irAEs). Modulation of PD-1/PD-L1 pathway using small molecules may be an alternative approach to mobilize immune system to fight against cancers. In this review, we focus on summarizing the recently disclosed chemical structures and preliminary structure-activity relationships (SARs) of small molecules as PD-1/PD-L1 modulators for cancer immunotherapy.

Background: The recent regulatory approvals of immune checkpoint protein inhibitors, such as ipilimumab, pembrolizumab, nivolumab, atezolizumab, durvalumab, and avelumab ushered a new era in cancer therapy. These inhibitors do not attack tumor cells directly but instead mobilize the immune system to re-recognize and eradicate tumors, which endows them with unique advantages including durable clinical responses and substantial clinical benefits. PD-1/PD-L1 inhibitors, a pillar of immune checkpoint protein inhibitors, have demonstrated unprecedented clinical efficacy in more than 20 cancer types. Besides monoclonal antibodies, diverse PD- 1/PD-L1 inhibiting candidates, such as peptides, small molecules have formed a powerful collection of weapons to fight cancer. Methods: The goal of this review is to summarize and discuss the current PD-1/PD-L1 inhibitors including candidates under clinical development, their molecular interactions with PD-1 or PD-L1, the disclosed structureactivity relationships of peptides and small molecules as inhibitors. Results: Current PD-1/PD-L1 inhibitors under clinical development are exclusively dominated by antibodies. The molecular interactions of therapeutic antibodies with PD-1 or PD-L1 have been gradually elucidated for the design of novel inhibitors. Various peptides and traditional small molecules have been investigated in preclinical model to discover novel PD-1/PD-L1 inhibitors. Conclusion: Peptides and small molecules may play an important role in immuno-oncology because they may bind to multiple immune checkpoint proteins via rational design, opening opportunity for a new generation of novel PD-1/PD-L1 inhibitors.

Oxamide is a potential slow-release nitrogen (N) fertilizer, especially under waterlogged conditions, due to its low solubility in water and the slow-release of ammonium by soil amidases. To investigate the effects of oxamide granules (2.00–2.38 mm in diameter) after a single basal fertilization on rice growth, soil properties, and N use efficiency in terms of N recovery efficiency (NRE), we conducted field experiments in two different types of paddy soils over two rice-growing seasons. Results showed that the fertilization effects of oxamide granules varied in the two types of paddy soil. In the red clayey paddy soil, the grain yields for both rice-growing seasons were high with a significantly higher NRE in the oxamide treatment than in the urea treatment. However, in the alluvial sandy paddy soil, the grain yield in the oxamide treatment was slightly lower than in the urea treatment. Furthermore, oxamide produced little improvement in NRE in the alluvial sandy paddy soil. Soil incubation experiments over 98 d were also carried out to evaluate the factors affecting the N release behavior of oxamide granules in the two types of paddy soil. We found that the amidase activities were higher and, therefore, the oxamide hydrolysis rates were faster in the alluvial sandy paddy soil, which had a higher soil pH value and organic matter content. The faster N release and the longer growth period resulted in a mismatch between N supply by oxamide and rice demand, which, in turn, led to little improvement in NRE and a decreased grain yield in the alluvial sandy paddy soil, especially in the reduced oxamide treatment. These results could help select the appropriate size of oxamide granules for use as a slow-release N fertilizer depending on the soil properties and growth period of rice.