Facile Synthesis of Rigid Binuclear Manganese Complexes for Magnetic Resonance Angiography and SLC39A14-Mediated Hepatic Imaging.

Manganese(II)-based contrast agents (MBCAs) are potential candidates for gadolinium-free enhanced magnetic resonance imaging (MRI). In this work, a rigid binuclear MBCA (Mn2-PhDTA2) with a zero-length linker was developed via facile synthetic routes, while the other dimer (Mn2-TPA-PhDTA2) with a longer rigid linker was also synthesized via more complex steps. Although the molecular weight of Mn2-PhDTA2 is lower than that of Mn2-TPA-PhDTA2, their T1 relaxivities are similar, being increased by over 71% compared to the mononuclear Mn-PhDTA. In the presence of serum albumin, the relaxivity of Mn2-PhDTA2 was slightly lower than that of Mn2-TPA-PhDTA2, possibly due to the lower affinity constant. The transmetalation reaction with copper(II) ions confirmed that Mn2-PhDTA2 has an ideal kinetic inertness with a dissociation half-life of approximately 10.4 h under physiological conditions. In the variable-temperature 17O NMR study, both Mn-PhDTA and Mn2-PhDTA2 demonstrated a similar estimated q close to 1, indicating the formation of monohydrated complexes with each manganese(II) ion. In addition, Mn2-PhDTA2 demonstrated a superior contrast enhancement to Mn-PhDTA in in vivo vascular and hepatic MRI and can be rapidly cleared through a dual hepatic and renal excretion pattern. The hepatic uptake mechanism of Mn2-PhDTA2 mediated by SLC39A14 was validated in cellular uptake studies.

Nutrient Uptake Potential of Nonleguminous Species and Its Interaction with Soil Characteristics and Enzyme Activities in the Agro-ecosystem.

The potential nutrient uptake abilities of a plant are essential for improving the yield and quality. Green manures can take up a huge amount of macronutrients from the soil. The mechanisms underlying the differences in nutrient uptake capacity among different nonlegume species remain unclear. The plot experiments were conducted to investigate the performance of nonlegume species including forage radish (Raphanus raphanistrum subsp. sativus), oil radish (Raphanus sativus var. Longipinnatus), February orchid (Orychophragmus violaceus L), and rapeseed (Baricca napus), while a ryegrass (Lolium perenne L.) species was used as a control. The study results showed that forage radish had the highest nutrient uptake (N and P), i.e., 322 and 101% in Hunan and 277 and 469% in the Sichuan site, respectively, compared with the control. While the greatest K uptake was found in forage radish, i.e., 123%, and February orchid, 243%, in the Hunan and Sichuan sites. Forage radish also presented higher phosphorus use efficiency in both experimental areas: Hunan by 301% and Sichuan by 633% compared to the control. Significant modifications were found in nutrient availability and enzyme activities after the cultivation of various species. The oil radish enhanced the ß-glucosidase (BG) and leucine-aminopeptidase enzyme activities by 324 and 367%, respectively, while forage radish developed the highest phosphatase (Phase) and N-acetyl-glucosaminidase (NAG) activities compared to the ryegrass in Hunan. In the Sichuan site, the oil radish promotes enzyme activities such as Phase (126%), BG (19%), and NAG (17%), compared to the control. It is concluded that forage radish, oil radish, and February orchid can easily improve soil nutrient quality in green manuring practices and provide valuable nutrient management systems.

Enhanced outcomes in residual or recurrent craniopharyngioma: evaluating combined gamma knife and phosphorus-32 brachytherapy.

BACKGROUND: Managing residual and recurrent craniopharyngioma effectively is crucial for improving patient outcomes. This study evaluates the combined use of gamma knife and phosphorus-32 brachytherapy, offering insights into alternative, less invasive treatment strategies. METHODS: We conducted a retrospective analysis of 97 patients treated from 2010 to 2016 for residual and recurrent craniopharyngioma using gamma knife and phosphorus-32 brachytherapy. We classified these patients into three groups: superficial solid (Group A), simple cystic (Group B), and mixed cystic-solid (Group C). We assessed the treatment's effectiveness by the tumor control rates and evaluated safety by monitoring vision, endocrine function improvements, and complication rates. RESULTS: The treatment achieved complete and adequate control rates of 49.5% and 87.6%, respectively. We observed improvements in vision or visual fields in 55.1% of the patients. The morbidity rate was 15.5%. The study found no significant differences in tumor control rates among the various lesion types. CONCLUSION: The combination of gamma knife and phosphorus-32 brachytherapy presents a viable, minimally invasive alternative for treating residual and recurrent craniopharyngioma. It offers high tumor control and functional improvement rates, suggesting its potential as a preferred strategy in some instances.

Green manuring reduces cadmium accumulation in rice: Roles of iron plaque and dissolved organic matter.

In southern China, winter green manure is widely used in rice cropping systems for improving grain yields and soil fertility. Cd pollution has recently been reported in some of these paddy fields. Research on the in-depth understanding of how green manuring affects Cd absorption in rice is limited. This study aimed to investigate the impacts of different green manures, including single plantation and mixed plantation on the absorption of Cd by rice and explore the underlying mechanisms. Pot experiments demonstrated that compared with winter fallow-rice, green manuring treatments considerably decreased rice Cd content, promoted the conversion of bioavailable Cd fraction into a more stable form, induced the formation of iron plaque, and increased the content of humic-like fraction (HF) in soil dissolved organic matter (DOM). Treatment with mixed plantation resulted in a greater decrease in rice Cd content and an increase in HF and iron plaque contents than single plantation. Hydroponic experiments confirmed that both iron plaque and green manure-derived DOM significantly reduced the Cd content in rice seedlings. In conclusion, green manure incorporation is an efficient measure for the safe utilization of Cd-contaminated soil, and mixed plantation of different green manures exerts stronger effects.

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging.

Effective vascular and hepatic enhancement and better safety are the key drivers for exploring gadolinium-free hepatobiliary contrast agents. Herein, a facile strategy proposes that the high lipophilicity may be favorable to enhancing sequentially vascular and hepatobiliary signal intensity based on the structure-activity relationship that both hepatic uptake and interaction with serum albumins partly depend on lipophilicity. Therefore, 11 newly synthesized derivatives of manganese o-phenylenediamine-N,N,N',N'-tetraacetic acid (MnLs) were evaluated as vascular and hepatobiliary agents. The maximum signal intensities of the heart, liver, and kidneys were strongly correlated with log P, a key indicator of lipophilicity. The most lipophilic agent, MnL6, showed favorable relaxivity when binding with serum albumin, good vascular enhancement, rapid excretion, and reliable hepatobiliary phases comparable to a classic hepatobiliary agent, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for in vivo liver tumor imaging. Inhibition experiments confirmed the hepatic targeting of MnL6 is mediated by organic anion-transporting polypeptides.

Dynamic Transformation of Nano-MoS2 in a Soil-Plant System Empowers Its Multifunctionality on Soybean Growth.

Molybdenum disulfide (nano-MoS2) nanomaterials have shown great potential for biomedical and catalytic applications due to their unique enzyme-mimicking properties. However, their potential agricultural applications have been largely unexplored. A key factor prior to the application of nano-MoS2 in agriculture is understanding its behavior in a complex soil-plant system, particularly in terms of its transformation. Here, we investigate the distribution and transformation of two types of nano-MoS2 (MoS2 nanoparticles and MoS2 nanosheets) in a soil-soybean system through a combination of synchrotron radiation-based X-ray absorption near-edge spectroscopy (XANES) and single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS). We found that MoS2 nanoparticles (NPs) transform dynamically in soil and plant tissues, releasing molybdenum (Mo) and sulfur (S) that can be incorporated gradually into the key enzymes involved in nitrogen metabolism and the antioxidant system, while the rest remain intact and act as nanozymes. Notably, there is 247.9 mg/kg of organic Mo in the nodule, while there is only 49.9 mg/kg of MoS2 NPs. This study demonstrates that it is the transformation that leads to the multifunctionality of MoS2, which can improve the biological nitrogen fixation (BNF) and growth. Therefore, MoS2 NPs enable a 30% increase in yield compared to the traditional molybdenum fertilizer (Na2MoO4). Excessive transformation of MoS2 nanosheets (NS) leads to the overaccumulation of Mo and sulfate in the plant, which damages the nodule function and yield. The study highlights the importance of understanding the transformation of nanomaterials for agricultural applications in future studies.

Green manuring relocates microbiomes in driving the soil functionality of nitrogen cycling to obtain preferable grain yields in thirty years.

Fertilizers are widely used to produce more food, inevitably altering the diversity and composition of soil organisms. The role of soil biodiversity in controlling multiple ecosystem services remains unclear, especially after decades of fertilization. Here, we assess the contribution of the soil functionalities of carbon (C), nitrogen (N), and phosphorus (P) cycling to crop production and explore how soil organisms control these functionalities in a 33-year field fertilization experiment. The long-term application of green manure or cow manure produced wheat yields equivalent to those obtained with chemical N, with the former providing higher soil functions and allowing the functionality of N cycling (especially soil N mineralization and biological N fixation) to control wheat production. The keystone phylotypes within the global network rather than the overall microbial community dominated the soil multifunctionality and functionality of C, N, and P cycling across the soil profile (0-100 cm). We further confirmed that these keystone phylotypes consisted of many metabolic pathways of nutrient cycling and essential microbes involved in organic C mineralization, N2O release, and biological N fixation. The chemical N, green manure, and cow manure resulted in the highest abundances of amoB, nifH, and GH48 genes and Nitrosomonadaceae, Azospirillaceae, and Sphingomonadaceae within the keystone phylotypes, and these microbes were significantly and positively correlated with N2O release, N fixation, and organic C mineralization, respectively. Moreover, our results demonstrated that organic fertilization increased the effects of the network size and keystone phylotypes on the subsoil functions by facilitating the migration of soil microorganisms across the soil profiles and green manure with the highest migration rates. This study highlights the importance of the functionality of N cycling in controlling crop production and keystone phylotypes in regulating soil functions, and provides selectable fertilization strategies for maintaining crop production and soil functions across soil profiles in agricultural ecosystems.

Investigation on the effect of ulinastatin on the apoptosis of vascular smooth muscle cells in rats with aortic dissection based on the Sirt1/FoxO3a pathway.

This study aimed to investigate the effects of ulinastatin on the apoptosis and (Sirt1/FoxO3a) pathway of vascular smooth muscle cells (VSMC) in aortic dissection (AD) rats. For this purpose a rat model of aortic dissection (AD) was constructed by giving drinking water containing 0.08% ß-aminopropionitrile (BAPN) to rats, HE staining was used to observe the pathological changes of the aorta in AD rats; the diseased blood vessels of AD rats were taken for primary culture and passage of VSMCs, the morphology of VSMCs was observed, and VSMCs were identify with immunofluorescence staining; VSMCs were treated with culture media containing 0, 1000, 2000, 3000, 4000, 5000, 6000, 7000 U/mL ulinastatin, and MTT kit was used to determine the effect of ulinastatin on VSMC proliferation in AD rats; the VSMC of AD rats were divided into blank group (normal culture), ulinastatin group (medium containing 5000 U/mL ulinastatin), Sirt1 inhibitor group (medium containing 1 µmol/L EX527), ulinastatin + Sirt1 inhibitor group (medium containing 5000 U/mL ulinastatin, 1 µmol/L EX527), flow cytometry was used to detect the VSMC apoptosis in each group, WB was used to detect the expression of VSMC apoptosis-related proteins and Sirt1/FoxO3a pathway-related proteins in each group. Findings suggested that the aortic wall of AD rats was thickened, and the dissection false cavity appeared; VSMC mostly presented different shapes such as triangles and stars, the immunofluorescence staining results showed that α-SMA was arranged in the cytoplasm in the form of myofilaments, showing green fluorescence, and the nucleus showed blue fluorescence, and the rate of positive cells was more than 95%; various doses of ulinastatin had a certain inhibitory effect on the proliferation of VSMC, and 5000 U/mL ulinastatin had a higher proliferation inhibition rate; compared with the blank group, the VSMC apoptosis rate, Caspase-3, Bax protein, Sirt1/FoxO3a pathway related protein expression in the ulinastatin group were significantly increased, and the Bcl-2 protein expression was significantly decreased (P<0.05), the VSMC apoptosis rate, Caspase-3, Bax protein, Sirt1/FoxO3a pathway related protein expression in the Sirt1 inhibitor group were significantly decreased, and the Bcl-2 protein expression was significantly increased (P<0.05); compared with the ulinastatin group, the VSMC apoptosis rate, Caspase-3, Bax protein, Sirt1/FoxO3a pathway related protein expression in the ulinastatin + Sirt1 inhibitor group were significantly decreased, and the Bcl-2 protein expression was significantly increased (P<0.05). It was concluded that ulinastatin can inhibit the proliferation of VSMCs in AD rats and promote their apoptosis, which may be achieved by activating the Sirt1/FoxO3a pathway.

Exploring site-specific N application rate to reduce N footprint and increase crop production for green manure-rice rotation system in southern China.

Milk vetch (Astragalus sinicus L.) is leguminous green manure (GM) which produces organic nitrogen (N) for subsequent crops and is widely planted and utilized to simultaneously reduce the use of synthetic N fertilizer and its environmental costs in rice systems. Determination of an optimal N application rate specific to the GM-rice system is challenging because of the large temporal and spatial variations in soil, climate, and field management conditions. To solve this problem, we developed a framework to explore the site-specific N application rate for the low-N footprint rice production system in southern China based on multi-site field experiments, farmer field survey, and process-based model (WHCNS_Rice, soil water heat carbon nitrogen simulator for rice). The results showed that a process-based model can explain >83.3% (p < 0.01) of the variation in rice yield, aboveground biomass, crop N uptake, and soil mineral N. Based on the scenario analysis of the tested WHCNS_Rice model, the simple regression equation was developed to implement site-specific N application rates that considered variations in GM biomass, soil, and climatic conditions. Simulation evaluation on nine provinces in southern China showed that the site-specific N application rate reduced regional synthetic N fertilizer input by 29.6 ± 17.8% and 65.3 ± 23.0% for single and early rice, respectively; decreased their total N footprints (NFs) by 23.4% and 49.3%, respectively; and without reduction in rice yield, compared with traditional farming N practices. The reduction in total NF was attributed to the reduced emissions from ammonia volatilization by 35.2%, N leaching by 28.4%, and N runoff by 32.7%. In this study, we suggested a low NF rice production system that can be obtained by combining GM with site-specific N application rate in southern China.

Relaxivity Enhancement of Hybrid Micelles via Modulation of Water Coordination Numbers for Magnetic Resonance Lymphography.

Considerable efforts have been made to develop nanoparticle-based magnetic resonance contrast agents (CAs) with high relaxivity. The prolonged rotational correlation time (τR) induced relaxivity enhancement is commonly recognized, while the effect of the water coordination numbers (q) on the relaxivity of nanoparticle-based CAs gets less attention. Herein, we first investigated the relationship between T1 relaxivity (r1) and q in manganese-based hybrid micellar CAs and proposed a strategy to enhance the relaxivity by increasing q. Hybrid micelles with different ratios of amphiphilic manganese complex (MnL) and DSPE-PEG2000 were prepared, whose q values were evaluated by Oxygen-17-NMR spectroscopy. Micelles with lower manganese doping density exhibit increased q and enhanced relaxivity, corroborating the conception. In vivo sentinel lymph node (SLN) imaging demonstrates that DSPE-PEG/MnL micelles could differentiate metastatic SLN from inflammatory LN. Our strategy makes it feasible for relaxivity enhancement by modulating q, providing new approaches for the structural design of high-performance hybrid micellar CAs.

Endoscopic cadaveric analysis of the origin of the ophthalmic artery.

PURPOSE: The ophthalmic artery is often involved in suprasellar and parasellar surgeries, but the anatomical structure where the ophthalmic artery originates has not been fully clarified from the perspective of an endoscopic endonasal approach (EEA). METHODS: A total of 10 fresh cadaveric heads (20 sides) were dissected through an EEA, and the origin of the bilateral ophthalmic arteries and their adjacent structures were observed from a ventral view. The origin of the ophthalmic artery in 50 healthy people was retrospectively studied on computed tomography angiography imaging. RESULTS: The ophthalmic artery originated from the intradural segment (75%), paraclinoid segment (15%), or parasellar segment (10%) of the internal carotid artery. The cross-sectional view of the internal carotid artery through the EEA showed that the ophthalmic artery originated from the middle 1/3 (75%) or medial 1/3 (25%) of the upper surface of the internal carotid artery. On computed tomography angiography, the ophthalmic artery originated from the middle 1/3 (77%) and medial 1/3 (22%) of the upper surface of the internal carotid artery. All ophthalmic arteries were near the level of the distal dural ring (DDR) of the internal carotid artery, that is, within 3 mm above or below the DDR. CONCLUSIONS: The ophthalmic artery usually originates in the middle 1/3 of the upper surface of the intradural segment of the internal carotid artery within 3 mm of the DDR. The ophthalmic artery can be protected to the utmost extent after its origin is identified through an EEA.

Plk1 promotes renal tubulointerstitial fibrosis by targeting autophagy/lysosome axis.

The prevalence of chronic kidney disease (CKD) has been increasing over the past decades. However, no effective therapies are available for delaying or curing CKD. Progressive fibrosis is the major pathological feature of CKD, which leads to end-stage renal disease (ESRD). The present study showed that Polo-like kinase 1 (Plk1) was upregulated in the kidneys of CKD patients and mice subjected to unilateral ureteral obstruction (UUO) with location in proximal tubules and tubulointerstitial fibroblasts. Pharmacological inhibition, genetic silencing or knockout of Plk1 attenuated obstructive nephropathy due to suppressed fibroblast activation mediated by reduced autophagic flux. We found Plk1 plays a critical role in maintaining intralysosomal pH by regulating ATP6V1A phosphorylation, and inhibition of Plk1 impaired lysosomal function leading to blockade of autophagic flux. In addition, Plk1 also prevented partial epithelial-mesenchymal transition (pEMT) of tubular epithelial cells via autophagy pathway. In conclusion, this study demonstrated that Plk1 plays a pathogenic role in renal tubulointerstitial fibrosis by regulating autophagy/lysosome axis. Thus, targeting Plk1 could be a promising strategy for CKD treatment.

Molybdenum Nanofertilizer Boosts Biological Nitrogen Fixation and Yield of Soybean through Delaying Nodule Senescence and Nutrition Enhancement.

Soybean (Glycine max) is a crop of global significance and has low reliance on N fertilizers due to its biological nitrogen fixation (BNF) capacity, which harvests ambient N2 as a critical ecosystem service. BNF can be severely compromised by abiotic stresses. Enhancing BNF is increasingly important not only to alleviate global food insecurity but also to reduce the environmental impact of agriculture by decreasing chemical fertilizer inputs. However, this has proven challenging using current genetic modification or bacterial nodulation methods. Here, we demonstrate that a single application of a low dose (10 mg/kg) of molybdenum disulfide nanoparticles (MoS2 NPs) can enhance soybean BNF and grain yield by 30%, compared with conventional molybdate fertilizer. Unlike molybdate, MoS2 NPs can more sustainably release Mo, which then is effectively incorporated as a cofactor for the synthesis of nitrogenase and molybdenum-based enzymes that subsequently enhance BNF. Sulfur is also released sustainably and incorporated into biomolecule synthesis, particularly in thiol-containing antioxidants. The superior antioxidant enzyme activity of MoS2 NPs, together with the thiol compounds, protect the nodules from reactive oxygen species (ROS) damage, delay nodule aging, and maintain the BNF function for a longer term. The multifunctional nature of MoS2 NPs makes them a highly effective strategy to enhance plant tolerance to abiotic stresses. Given that the physicochemical properties of nanomaterials can be readily modulated, material performance (e.g., ROS capturing capacity) can be further enhanced by several synthesis strategies. This study thus demonstrates that nanotechnology can be an efficient and sustainable approach to enhancing BNF and crop yield under abiotic stress and combating global food insecurity.

Carbonic Anhydrase IX Targeting Mn(II)-Based Magnetic Resonance Molecular Imaging Probe for Hypoxia Tumors.

Physiological hypoxic conditions in the tumor microenvironment and consequential overexpression of carbonic anhydrase IX (CA IX) are two characteristics shared by numerous types of solid malignant tumors. Early detection with hypoxia assessment is crucial to improve the prognosis and therapy outcomes of hypoxia tumors. Herein, using acetazolamide (AZA) as a CA IX-targeting moiety, we design and synthesize an Mn(II)-based MR imaging probe (named AZA-TA-Mn) incorporating AZA and two Mn(II) chelates of Mn-TyEDTA on a rigid triazine (TA) scaffold. The per Mn relaxivity of AZA-TA-Mn is 2-fold higher than its monomeric Mn-TyEDTA, which allows it for low-dose imaging of hypoxic tumors. In a xenograft mice model of esophageal squamous cell carcinoma (ESCC), a low dosage of AZA-TA-Mn (0.05 mmol/kg) can selectively produce prolonged and stronger contrast enhancement in the tumor compared to the non-specific Gd-DTPA (0.1 mmol/kg). A competition study of co-injection of free AZA and Mn(II) probes confirms the in vivo tumor selectivity of AZA-TA-Mn, resulting in a more than 2.5-fold decreased tumor-to-muscle contrast-to-noise ratio (ΔCNR) at 60 min post-injection. MR imaging results were further supported by the quantitative analysis of Mn tissue levels, as the co-injection of free AZA resulted in significantly reduced Mn accumulation in tumor tissues. Finally, immunofluorescence staining of tissue sections confirms the positive correlation between the tumor accumulation of AZA-TA-Mn and CA IX overexpression. Hence, using CA IX as the hypoxia biomarker, our results illustrate a practical strategy for the development of novel imaging probes for hypoxic tumors.

Association between mixed exposure of polycyclic aromatic hydrocarbons and telomere length in general population: NHANES 2001-2002.

Although an association between single polycyclic aromatic hydrocarbons (PAHs) adult exposure and telomere length has been reported, the evidence of mixed PAHs (1-napthol, 2-napthol, 3-fluorene, 2-fluorene, 3-phenanthrene, 1-phenanthrene, 2-phenanthrene, and 1-pyrene) exposure and telomere length in the adult general population is still not clear. A total of 1460 adults over the age of 20 years provided urine information on 8 PAHs and selected covariates from the 2001-2002 National Health and Nutrition Examination Survey (NHANES). Bayesian nuclear machine regression (BKMR) was conducted to analyze these associations of telomere length in multiple PAH-exposed environments. Linear regression is mainly used for correlation analysis of PAHs with selected covariate adjustments. Restricted cubic spline (RCS) is used to estimate the correlation between selected PAHs and telomere length. After adjusting for potential covariates, PAHs mixed exposure was negatively associated with telomere length. The linear regression results showed that 2-napthol and 2-fluorene were negatively correlated with telomere length. Telomere length decreased by 1.0% in the fully adjusted model per increment of one unit in the base-10-logarithm-transformed 2-napthol and 2-fluorene concentrations (P = 0.030 and 0.049, respectively). However, the other 6 PAH metabolites were not significantly different. In addition, RCS results showed that 2-napthol has a marginal dose effect relationship with telomere length. Our present study suggested that PAHs are negatively associated with telomere length in the general population of the USA. Considering that the low level of PAHs exposure in the general population can also induce reduced telomere length and potential health risks, future research is needed to explore potential mechanisms.

[Effects of Chinese Milk Vetch Returning Incorporated with Chemical Fertilizer Reduction on the Composition and Function of Soil Bacterial Communities in Paddy Fields].

Chinese milk vetch (Astragalus sinicus L.) is an important organic nutrient resource in the southern Henan rice-growing area. Thus, the effects of Chinese milk vetch (MV) returning incorporated with reduced chemical fertilizer on the physicochemical properties and bacterial community characteristics in paddy soil were studied. These results can provide a certain theoretical basis for the improvement of soil fertility and reduction of chemical fertilizer in this area. A field experiment was conducted for 12 consecutive years, involving six fertilization treatments (blank control, CK; 100% chemical fertilizer, F100; 80% chemical fertilizer+22.5 t·hm-2 MV, MV1F80; 80% chemical fertilizer+45 t·hm-2 MV, MV2F80; 60% chemical fertilizer+22.5 t·hm-2 MV, MV1F60; and 60% chemical fertilizer+45 t·hm-2 MV, MV2F60). The high-throughput sequencing method was used to compare the effects of different fertilization treatments on soil bacterial community diversity, composition, and structural characteristics. The FAPROTAX function prediction method was used to analyze the abundance differences of functional groups between different fertilization treatments. Additionally, combined with soil physicochemical properties and bacterial community characteristics, we explored the key soil environmental factors that changed the structure and functional characteristics of the soil bacterial community. Compared with that under CK, the soil bulk density (BD) under the MV returning incorporated with reduced chemical fertilizer treatment was decreased, whereas soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK) were increased by 12.7%-35.5%, 38.2%-65.7%, 66.7%-95.2%, and 20.3%-31.6%, respectively. Compared with that under the F100 treatment, the Sobs index and Shannon diversity index of the bacterial community under the MV returning incorporated with reduced chemical fertilizer were decreased, and the Sobs index and Shannon diversity index were significantly positively correlated with BD (P<0.05) but significantly negatively correlated with SOC and TN (P<0.05). Compared with that under the F100 treatment, the relative abundances of Firmicutes under the MV1F80 and MV2F60 treatments were significantly increased by 82.2% and 67.4% (P<0.05), but the relative abundances of Acidobacteria were significantly reduced by 32.6% and 40.5% (P<0.05), respectively. The relative abundance of Actinobacteria under the MV2F60 treatment was significantly increased by 30.0% (P<0.05) compared with that under the F100 treatment. According to RDA analysis, soil SOC, TN, and TK were the main soil environmental factors that significantly affected bacterial community (P<0.05). Compared with that under CK and the F100 treatment, the abundance of functional groups of chemoheterotrophy, nitrogen fixation, fermentation, and ureolysis under the MV returning incorporated with reduced chemical fertilizer treatment were improved, whereas the abundance of functional groups of animal parasites or symbionts, all human pathogens, and human pathogen pneumonia were reduced, particularly under MV1F80 and MV2F60. To summarize, the long-term MV returning to the field incorporated with reduced chemical fertilizer improved the soil physical and chemical properties, thus changing the structure and functional characteristics of the soil bacterial communities, contributing to the improvement in the soil fertility, stability, and health of micro-ecosystems in paddy fields, thus ensuring the green and sustainable development of regional agriculture.

Study on the relationships between the accumulation and translocation of dry matter and nitrogen and flower/pod development into seeds and seed yields in Chinese milk vetch.

Further improvements to the yield potential of Chinese milk vetch seed are essential for the planting demand of green manure. Flower and pod development directly determines the number of seeds and the seed yield of Chinese milk vetch. However, the accumulation and translocation of dry matter and nitrogen between plant organs directly affects flower and pod development and morphological formation. There are few studies that analyse the relationship between the accumulation and transport of dry matter and nitrogen and the number of flowers, pods, grains and seed yield during Chinese milk vetch's critical development period. This study aimed to determine the seed yield response to dry matter and nitrogen accumulation and translocation during the Chinese milk vetch growth period and to quantify the relationship between these factors to predict Chinese milk vetch seed yield. Experiments were performed during the 2017-2018 and 2018-2019 growing seasons at the Dayuzhuang experimental field. The first experiment involved five foliar application stages (late wintering stage, returning green stage, squaring stage, pre-flowering stage, and 5 days after flowering) and six foliar application concentrations of borate solution (0, 500, 1000, 2000, 4000, and 6000 mg L-1). Experiment 2 included five foliar application stages (late wintering stage, returning green stage, squaring stage, pre-flowering stage, and 5 days after flowering) and six foliar application concentrations of paclobutrazol (0, 200, 300, 400, 500, and 600 mg L-1). When the dry matter mass in the full flowering stage was 3500-4500 kg hm-2, the seed yield reached more than 800 kg hm-2. When the translocated assimilates were stored in the vegetative organs before flowering, the assimilate translocation rate and their contributions to seed yield were 1500-1800 kg hm-2, 30-35%, and 28-38%, respectively, and the Chinese milk vetch seed yield was predicted to reach 800-1000 kg hm-2 at maturity. When the nitrogen translocation amount in the vegetative organs before flowering, the nitrogen translocation rate, and the contribution rate to the seed yield were 68-78 kg hm-2, 65-75%, and 75-85%, respectively, the Chinese milk vetch seed yield was predicted to reach 800-1000 kg hm-2 at maturity. If the accumulation and translocation index values of dry matter and nitrogen were lower or higher than the above ranges, the seed yield was lower than 800 kg hm-2. The results of this study revealed the mechanism by which dry matter and nitrogen accumulation and translocation affect the Chinese milk vetch seed yield. These findings enrich the seed yield formation theory of Chinese milk vetch. They provide an early determination and quantitative regulation of high and stable seed yield for Chinese milk vetch in the field and aid researchers to integrate multiple production technologies for the sustainable production of Chinese milk vetch.

Winter Green Manure Decreases Subsoil Nitrate Accumulation and Increases N Use Efficiencies of Maize Production in North China Plain.

Planting a deep-rooted green manure (GM) (more than 1.0 m depth) greatly improves soil fertility and reduces the loss of nutrients. However, few studies have examined the response of soil nitrogen (N) distribution in the soil profile and subsoil N recovery to the long-term planting and incorporation of deep-rooted GM. Based on a 12-year (2009−2021) experiment of spring maize-winter GMs rotation in the North China Plain (NCP), this study investigated the effects of different GMs that were planted over the winter, including ryegrass (RrG, Lolium L.) (>1.0 m), Orychophragmus violaceus (OrV, Orychophragmus violaceus L.) (>0.8 m), and hairy vetch (VvR, Vicia villosa Roth.) (>1.0 m), on the spring maize yield, N distribution in the deep soil profile, N use efficiencies, functional gene abundances involving soil nitrification−denitrification processes and N2O production. Compared with the winter fallow, the maize yield significantly increased by 11.6% after 10 years of green manuring, and water storage in 0−200 cm soil profile significantly increased by 5.0−17.1% at maize seedling stage. The total N content in the soil layer at 0−90 cm increased by 15.8−19.7%, while the nitrate content in the deep soil layer (80−120 cm) decreased by 17.8−39.6%. Planting GM significantly increased the N recovery rate (10.4−32.7%) and fertilizer N partial productivity (4.6−13.3%). Additionally, the topsoil N functional genes (ammonia-oxidizing archaea amoA, ammonia-oxidizing bacterial amoA, nirS, nirK) significantly decreased without increasing N2O production potential. These results indicated that long-term planting of the deep-rooted GM effectively reduce the accumulation of nitrates in the deep soil and improve the crop yield and N use efficiencies, demonstrating a great value in green manuring to improve the fertility of the soil, increase the crop yield, and reduce the risk of N loss in NCP.

Prediction Model of VCA Formed by the Packing of Hybrid Lithological Coarse Aggregates Used in SMA.

The voids in coarse aggregate (VCA) is an important volumetric index in the mineral aggregate gradation design of stone matrix asphalt (SMA) mixtures. To explore the law of variation for VCA formed by the packing of basalt and lime coarse aggregates, a uniform design method and vibrating compaction tests were used to establish the prediction model. Based on the test results and stepwise regression analysis, a reliable prediction model of VCA was obtained. There is a multiple nonlinear relationship between the VCA and the proportion of each coarse aggregate in the mixture. Regardless of the type of coarse aggregates used, the rule of VCA with different forms of aggregate gradation curves has universal significance. This conclusion can help to determine the aggregate gradation in the design of SMA mixtures.