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AISI 316L stainless steel has received considerable attention as a common material for key ball valve components; however, its properties cannot be improved through traditional phase transformation, and fretting wears the contact interface between valve parts. A carburized layer was prepared on the surface of AISI 316L stainless steel by using double-glow low-temperature plasma carburization technology. This study reveals the effect of double-glow low-temperature plasma carburization technology on the fretting wear mechanism of AISI 316L steel under different normal loads and displacements. The fretting wear behavior and energy dissipation of the AISI 316L steel and the carburized layer were studied on an SRV-V fretting friction and wear machine with ball–plane contact. The wear mark morphology was analyzed by using scanning electron microscopy (SEM), the phase structure of the carburized layer was characterized with X-ray diffractometry (XRD), and the wear profile and wear volume were evaluated with laser confocal microscopy. The carburized layer contains a single Sc phase, a uniform and dense structure, and a metallurgically combined matrix. After plasma carburizing, the sample exhibited a maximum surface hardness of 897 ± 18 HV0.2, which is approximately four times higher than that of the matrix (273 ± 33 HV0.2). Moreover, the surface roughness was approximately doubled. The wear depth, wear rate, and frictional dissipation energy coefficient of the carburized layer were significantly reduced by up to approximately an order of magnitude compared with the matrix, while the wear resistance and fretting wear stability of the carburized layer were significantly improved. Under different load conditions, the wear mechanism of the AISI 316L steel changed from adhesive wear and abrasive wear to adhesive wear, fatigue delamination, and abrasive wear. Meanwhile, the wear mechanism of the carburized layer changed from adhesive wear to adhesive wear and fatigue delamination, accompanied by a furrowing effect. Under variable displacement conditions, both the AISI 316L steel and carburized layer mainly exhibited adhesive wear and fatigue peeling. Oxygen elements accumulated in the wear marks of the AISI 316L steel and carburized layer, indicating oxidative wear. The fretting wear properties of the AISI 316L steel and carburized layer were determined using the coupled competition between mechanical factors and thermochemical factors. Low-temperature plasma carburization technology improved the stability of the fretting wear process and changed the fretting regime of the AISI 316L steel and could be considered as anti-wearing coatings of ball valves. [ABSTRACT FROM AUTHOR]

Accurate soil management has long been the focus of research in agroecology. Crop productivity can be enhanced while reducing environmental threats from excessive fertilization by fully comprehending the spatial variability of soil properties and delineating management zones (MZs). A field investigation was carried out at experimental sites outside Hefei City's administrative districts in China to study the spatial variability of soil properties and the delineation of MZs. A total of 9601 soil samples were collected in the study area. A variety of soil properties were analyzed, including the pH, organic matter, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, available potassium, slowly released potassium, available sulfur, available boron, available copper, available zinc, available iron, and available manganese. The coefficient of variation for various soil properties exhibited a wide range, spanning from 12.2% to 100.5%. The geostatistical results show that most soil properties have moderate to strong spatial autocorrelation, and the ordinary kriging method is used to map the distribution of soil properties. The principal component analysis method was used to reduce the dimension of 13 soil properties to 4 principal components, and the fuzzy c-means clustering method was used to delineate MZs. The calculation results of the fuzzy performance index and normalized classification entropy show that the optimum number of MZs is five. In the study area, the western part exhibits the highest soil fertility, primarily attributed to its elevated organic matter content. Additionally, organic matter emerges as a key factor influencing sustainable agricultural production in this region. These results form the basis for soil managing areas outside the administrative districts of Hefei City. [ABSTRACT FROM AUTHOR]

Using agronomic measures to remediate heavy metal chromium (Cr) on farmland is the main measure to achieve the safe utilization of crops. This study was conducted under field trial conditions using locally formulated fertilizers (urea–ammonium phosphate–potassium chloride) as the control. Different fertilizer-type treatments such as ammonium sulfite, calcium magnesium phosphate, and diammonium phosphate were set up. Biochar and soil conditioner PX5B were chosen to compare the impacts of each to study the effects of different fertilizer types on maize yield, Cr content in each part, the bioconcentration factor, the translocation factor, and the available content of Cr in the soil. The results show that, compared with the formulated fertilizer, all treatments improved pH and soil organic matter and reduced the effective state of Cr content in the soil by 15.05% to 42.66%. The Cr content of maize grains under biochar and soil conditioner PX5B treatments were 0.80 mg·kg−1 and 0.88 mg·kg−1 with a 39.95% and 33.83% reduction, respectively, whereas the Cr content of maize grains under various fertilizer treatments was in the range of 0.82~1.32 mg·kg−1 with a 0.75%~38.19% reduction, respectively. Among the different fertilizer treatments, urea–calcium magnesium phosphate–potassium chloride, urea–diammonium phosphate–potassium chloride, ammonium sulfite–calcium magnesium phosphate–potassium chloride, and ammonium sulfite and urea–calcium magnesium phosphate–potassium chloride treatments reduced the Cr content of maize grains to within the range of the national food safety standard of China (1.0 mg·kg−1). The best reductions in the effective state Cr content of the soil and the Cr content of maize grains were achieved by ammonium sulfite–calcium magnesium phosphate–potassium chloride treatment, which was able to achieve similar reductions to the two conditioners. It also had a reduction effect on the Cr content of maize roots and straws, the aboveground bioconcentration factor (BCF), and the primary translocation factor (PTF). Therefore, the combination of ammonium sulfite and calcium magnesium phosphate is the best fertilizer combination to block the absorption of Cr by maize and has some implications for the fertilization of farmland under acidic soil conditions of Cr contamination. [ABSTRACT FROM AUTHOR]

Screening for low-accumulation varieties is an effective way to reduce the cadmium (Cd) content in crops and decrease human Cd intake. In this study, a field experiment was conducted to analyze the characteristics of Cd absorption and accumulation in 24 maize varieties at maturity in farmland with different levels of Cd pollution. Cluster analysis and Pareto analysis methods were used to screen for maize varieties with low Cd absorption. In addition, the environmental threshold of Cd in farmland in the study area was estimated based on the Species Sensitivity Distribution (SSD) characteristics of different maize Cd enrichment coefficients (1/BCF). The results showed that maize in the study area was subject to varying degrees of Cd pollution, with total soil Cd content ranging from 1.81 to 2.71 mg·kg−1 at test site 1 and from 0.95 to 1.76 mg·kg−1 at test site 2. Only the Cd content of heavy metals in maize kernels at test site 2 did not exceed China's national food safety standard (GB 2762-2022, 0.1 mg·kg−1), with the Cd content of different maize varieties at test site 2 ranging from 0.008 to 0.073 mg·kg−1 and the bioconcentration factor (BCF) of maize kernels for Cd ranging from 0.004 to 0.054. According to cluster analysis and Pareto analysis, the low-Cd accumulation maize varieties suitable for local planting were identified as Yufeng 303, Nongda 372, Jingnongke 728, MC121 (Fengda Seed Industry), and Jinyu 1233. In addition, the soil Cd environmental threshold for ensuring that 95% of maize would not be polluted by Cd in soil was derived as 1.39 mg·kg−1. [ABSTRACT FROM AUTHOR]

Effective, economical and feasible remediation technology of heavy metal pollution in farmland is an important research concentration in the field of farmland soil remediation. In order to investigate the remediation effects of formula fertilizer and biochar on cadmium (Cd)–plumbum (Pb) contaminated farmland, blank (CK), lime (SH), biochar (SWT), formula fertilizer (FL), and biochar + formula fertilizer (FS) were set up in Cd–Pb contaminated farmland. The results demonstrated the following: (1) Compared with CK, SWT and FS increased the yield by 11.21% and 15.00%, respectively, which was significantly higher than other treatments. (2) The concentrations of Cd and Pb in maize kernels under all treatments were lower than the limited value stipulated by GB 2762-2022 in China. Compared with CK, FS reduced the concentration of Cd and Pb in maize kernels by 24.96% and 31.46%, respectively, which were the most significant. All the treatments can reduce the concentrations of Cd and Pb in maize cob and straw and inhibit the transfer of Cd and Pb from the lower part of the maize field to the overground part. (3) FL, SWT, and FS increased soil pH by 0.17, 0.10, and 0.19 units, respectively. FS can reduce the concentrations of available cadmium (DTPA-Cd) and available lead (DTPA-Pb) significantly, which are 31.05% and 38.57% lower than CK, respectively. (4) Each treatment can reduce the extraction state and reducible state of weak acid Cd and Pb in soil, while increasing the proportion of oxidizable state and residual state. FL and FS significantly increased the percentage of residual Cd and Pb by 18.00% and 24.32%, respectively, and 33.33% and 37.76%, respectively. (5) FL (1.747) and FS (1.679) were relatively higher than CK in input/output. In conclusion, the combined application of biochar and formula fertilizer in Cd/Pb polluted farmland can effectively reduce the concentration of Cd and Pb in maize and has high economic benefits and practicability. [ABSTRACT FROM AUTHOR]

The acquisition of the timing and duration of metamorphic mineral growth is the key to understanding the evolution of metamorphic belts. Garnet Lu–Hf geochronology is becoming increasingly powerful in this aspect. It is believed that garnet Lu–Hf radiometric systems are preserved during low-temperature metamorphism. However, this hypothesis has not been systematically tested. To examine the Lu–Hf systematics of garnets during low-temperature metamorphism, we conducted radiometric dating on individual garnet crystals of different sizes from a single micaschist in the North Qilian orogenic belt. The garnet Lu–Hf dates correlate well with the grain sizes and their core Mn concentrations. The positive correlation between the ages and grain sizes suggests that grain size is a proxy for preserving garnet nucleation and growth history. Small grains nucleated and grew later than large crystals. The Lu–Hf date of the individual garnet crystals faithfully recorded the total growth time span. The date difference of ~16 Myr is the minimum duration of the total garnet growth. The age discrepancy between the micaschist and the eclogite indicates they may not have experienced the same subduction and exhumation in the North Qilian orogenic belt. [ABSTRACT FROM AUTHOR]

The accumulation of heavy metals in rice is bound to affect human health and safety. In order to ensure food security, this study explores the effect of leaf surface regulation of zinc (Zn) fertilizer on the safety of rice in cadmium (Cd)-plumbum (Pb) polluted farmland. Through field experiments, the leaf surface control treatment of zinc fertilizer was set up, and the effects of leaf surface control of zinc fertilizer on rice yield, Cd and Pb concentration in different parts and zinc, nitrogen, phosphorus and potassium concentration in brown rice were studied in the growing period of rice. The results showed as follows: (1) Spraying twice or more in the growth stage of rice could increase the yield by 6.77–7.29% compared with the blank, which was significantly higher than that of single spraying in a certain growth stage. (2) After spraying zinc fertilizer on the leaf surface, Cd and Pb concentration in brown rice decreased by 29.52–56.01% and 11.10–28.34%, respectively, compared with CK. Two or more times of spraying can make Cd concentration in brown rice meet the Chinese standard GB 2762-2022, and one time of spraying can make Pb concentration in brown rice meet the standard. (3) Leaf surface control of zinc fertilizer could reduce the Cd enrichment ability of rice plant parts, and the Cd enrichment coefficient of brown rice was significantly reduced by 28.18–55.02%. Leaf surface control of zinc fertilizer can reduce Cd and Pb concentration in brown rice by reducing the transport ability of heavy metal Cd and Pb in rice roots to straw and then to brown rice. (4) The zinc concentration in brown rice was 18.16–20.68 mg·kg−1, which was 18.21–34.64% higher than that in CK, and the zinc enrichment effect was the most significant after spraying three times. Meanwhile, the nitrogen, phosphorus and potassium concentration in brown rice also increased with the increase of spraying times. By comprehensive analysis, the leaf surface control of zinc fertilizer can reduce the Cd and Pb concentration in rice, and the Cd and Pb concentration in brown rice can meet the Chinese standard GB 2762-2022 by spraying twice. At the same time, it can improve the concentration of zinc, nitrogen, phosphorus and potassium in brown rice, is feasible and has high economic benefits. [ABSTRACT FROM AUTHOR]

Plant extraction is a thorough remediation method to remove heavy metals from soil. Chelating agents can enhance the extraction effect of heavy metals from soil by plants. In this study, low molecular weight organic acids (LMWOAs), such as citric acid (CA), tartaric acid (TA) and polyaspartate (PASP), were added to the farmland soil contaminated with Cd and Pb and combined with corn to enhance the absorption and extraction of Cadmium (Cd) and Plumbum (Pb). The effects of LMWOAs on the growth and yield of maize, Cd and Pb concentrations in each part of maize, rhizosphere soil pH, total cadmium and lead content and DTPA-Cd and Pb concentrations were studied. The enrichment, transport and extraction ability of maize were analyzed, and calcium chloride (CaCl2) was compared. The results showed that: (1) Exogenous LMWOAs increased the biomass and yield of maize compared with no material added (CK), and CA increased the yield of maize by 6.33%. (2) Exogenous LMWOAs promoted the uptake of Cd and Pb in all parts of maize, and the distribution of Cd and Pb in all organs was as follows: straws > roots > maize cobs > kernels and roots > straws > maize cobs > kernels. The Cd and Pb concentrations in maize kernels were in line with GB 13078-2017 in China, which could be used as feed maize. (3) Exogenous LMWOAs enhanced the enrichment of Cd and Pb in maize straws and roots. PASP had a good enrichment effect on Cd and Pb. CA and CaCl2 could enhance the transport capacity of Cd and Pb from maize roots to straw. (4) Compared with CK, the total amount of Cd and Pb in rhizosphere soil decreased by 6.93–26.99% and 2.74–6.79%, respectively. LMWOAs could promote the concentration of DTPA-Cd and Pb in rhizosphere soil, and PASP had the most significant increase in DTPA-Cd and Pb in rhizosphere soil. Compared with CK, the soil pH value decreased by 0.03–0.14 units. LMWOAs can enhance the removal of heavy metals from maize, and PASP has the most significant comprehensive effect. [ABSTRACT FROM AUTHOR]

Isolates of three endornavirus species were identified co-infecting an unidentified species of Ceratobasidium, itself identified as a symbiont from within the roots of a wild plant of the terrestrial orchid Pterostylis vittata in Western Australia. Isogenic lines of the fungal isolate lacking all three mycoviruses were derived from the virus-infected isolate. To observe how presence of endornaviruses influenced gene expression in the fungal host, we sequenced fungus-derived small RNA species from the virus-infected and virus-free isogenic lines and compared them. The presence of mycoviruses influenced expression of small RNAs. Of the 3272 fungus-derived small RNA species identified, the expression of 9.1% (300 of 3272) of them were up-regulated, and 0.6% (18 of 3272) were down-regulated in the presence of the viruses. Fourteen novel micro-RNA-like RNAs (Cer-milRNAs) were predicted. Gene target prediction of the differentially expressed Cer-milRNAs was quite ambiguous; however, fungal genes involved in transcriptional regulation, catalysis, molecular binding, and metabolic activities such as gene expression, DNA metabolic processes and regulation activities were differentially expressed in the presence of the mycoviruses. [ABSTRACT FROM AUTHOR]

Featured Application: This study aims to improve the absolute position error of robot manipulators for vehicle assembly line without using an expensive external apparatus. It is well known that most of the industrial robots have excellent repeatability in positioning. However, the absolute position errors of industrial robots are relatively poor, and in some cases the error may reach even several millimeters, which make it difficult to apply the robot system to vehicle assembly lines that need small position errors. In this paper, we have studied a method to reduce the absolute position error of robots using machine vision and neural network. The position/orientation of robot tool-end is compensated using a vision-based approach combined with a neural network, where a novel indirect calibration approach is presented in order to gather information for training the neural network. In the simulation, the proposed compensation algorithm was found to reduce the positional error to 98%. On average, the absolute position error was 0.029 mm. The application of the proposed algorithm in the actual robot experiment reduced the error to 50.3%, averaging 1.79 mm. [ABSTRACT FROM AUTHOR]