Enantio- and Diastereoselective Desymmetrization of 1,1'-Biaryl-2,6-Dicarbaldehydes by Copper-Catalyzed 1,2-Addition of Silicon Nucleophiles.

A desymmetrizing 1,2-addition of silicon nucleophiles to biaryl derivatives containing an 2,6-dicarbaldehyde-1-yl unit is reported. The reaction is catalyzed by copper with a triazolium-ion-derived N-heterocyclic carbene as the chiral ligand and makes use of an Si-B reagent as the silicon pronucleophile. The practical methodology furnishes axially chiral aromatic carbaldehydes decorated with a centrally chiral α-hydroxysilane moiety in moderate to good yields and with high enantio- as well as excellent diastereoselectivities. The silicon nucleophile always attacks at the diastereotopic face of either carbonyl group away from the ortho substituent on the phenyl ring at C1 of the 2,6-dicarbaldehyde-1-yl fragment. The resulting axially and centrally chiral products can be further converted into valuable biaryl compounds with hardly any erosion of the enantiomeric excess.

Enantioselective Dearomatization of Pyridinium Salts by Copper-Catalyzed C4-Selective Addition of Silicon Nucleophiles.

A copper-catalyzed C4-selective addition of silicon nucleophiles released from an Si-B reagent to prochiral pyridinium triflates is reported. The dearomatization proceeds with excellent enantioselectivity using Cu(CH3CN)4PF6 as the precatalyst and (R,R)-Ph-BPE (1,2-bis[(2R,5R)-2,5-diphenylphospholan-1-yl]ethane) as the chiral ligand. A carbonyl group at C3 is required for this, likely acting a weak donor group to preorganize and direct the nucleophilic attack towards C4. The resulting 4-silylated 1,4-dihydropyridines can be further converted into functionalized piperidine derivatives.

Copper-Catalyzed Highly Enantioselective Addition of a Silicon Nucleophile to 3-Substituted 2H-Azirines Using an Si-B Reagent.

3-Substituted 2H-azirines can be considered strained cyclic ketimines, and highly enantioselective addition reactions of silicon nucleophiles to either acyclic or cyclic ketimines have been elusive so far. The present work closes this gap for those azirines by means of a copper-catalyzed silylation using a silyl boronic ester as a latent silicon nucleophile. The resulting C-silylated, unprotected (N-H) aziridines are obtained in high yields and with excellent enantioselectivities and can be further converted into valuable compounds with hardly any erosion of the enantiomeric excess.

Boosting the Enantioselectivity of Conjugate Borylation of α,ß-Disubstituted Cyclobutenones with Monooxides of Chiral C2 -Symmetric Bis(phosphine) Ligands.

Chiral bis(phosphine) monooxides (BPMOs) derived from C2 -symmetric bis(phosphines) have been found to induce superior levels of enantioselection in copper-catalyzed conjugate borylation of α,ß-disubstituted cyclobutenones. More precisely, enantiomeric excesses as well as chemical yields are exceedingly high with (R,R)-Bozphos as the chiral ligand while these values are low with parent (R,R)-Me-Duphos. A similar yet less pronounced effect was seen in the corresponding 1,6-addition to para-quinone methides.

MicroRNA-200a Affects the Proliferation of Airway Smooth Muscle Cells and Airway Remodeling by Targeting FOXC1 via the PI3K/AKT Signaling Pathway in Ovalbumin-Induced Asthmatic Mice.

BACKGROUND/AIMS: The etiology of asthma, which is a complicated disorder with various symptoms, including wheezing, coughing, and airflow obstruction, remains poorly understood. In addition, the effects of microRNAs (miRs) have not been explored. This study explored the effect of microRNA-200a (miR-200a) on airway smooth muscle cells (ASMCs) and airway remodeling in asthmatic mice. Furthermore, we speculated that miR-200a achieves its effect by targeting FOXC1 via the PI3K/AKT signaling pathway based on differentially expressed gene screening, target miR predictions and a bioinformatics analysis. METHODS: Eighty mice were assigned to a saline group or an ovalbumin (OVA) group, and the OVA group was transfected with a series of inhibitors, activators, and siRNAs to test the established mouse model. Airway reactivity and the ratio of eosinophils (EOSs) to leukocytes were detected. An ELISA was adopted to measure the levels of interleukin (IL)-4, IL-6, IL-8, tumor necrosis factor (TNF)-α, and immunoglobulin E (IgE). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to determine the expression of FOXC1, PI3K, AKT, NF-κB, cyclin D1, TGF-ß1 and p-AKT in ASMCs. Finally, CCK-8 assays were performed to detect cell proliferation and flow cytometry to detect apoptosis and cell cycle entry. RESULTS: The bioinformatics analysis indicated that miR-200a mediated the PI3K/AKT signaling pathway by targeting FOXC1. In addition, mouse models of asthma were established. An elevated expression of miR-200a, a decreased mRNA and protein expression of FOXC1, PI3K, AKT, NF-κB, cyclin D1 and TGF-ß1, a decreased expression of p-AKT, suppressed cell proliferation, accelerated apoptosis, and an increased number of cells at the G0/G1 phase were observed following the upregulation of miR-200a and downregulation of FOXC1. CONCLUSION: The overexpression of miR-200a may downregulate FOXC1, thereby inhibiting the activation of the PI3K/AKT signaling pathway and ultimately suppressing ASMC proliferation and airway remodeling in asthmatic mice. This evidence supports the potential that miR-200a represents a new approach to treating asthma.

[Effects of Long-term Combined Application of Organic and Inorganic Fertilizers on Soil Carbon Pool and Greenhouse Gas Emissions in Orchards].

Applying organic fertilizer can increase the contents of soil organic carbon (SOC) and active organic carbon, which are crucial for strengthening soil quality and fertility. Four treatments were established:no fertilization (CK), single application of organic fertilizer (M), single application of chemical fertilizer (NPK), and combined application of organic and inorganic fertilizers (MNPK). The changes in SOC and active components under long-term combined application of organic and inorganic fertilizers were investigated, as were the effects of various fertilization measures on greenhouse gas emissions. Moreover, we evaluated the variation in the soil carbon pool management index (CPMI). Total organic carbon (TOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), easily oxidized organic carbon (EOC), and particulate organic carbon (POC) increased by 82.84%, 66.30%, 21.12%, 93.28%, and 145.80%, respectively, when compared to those in the CK treatment. The NPK treatment had no discernible effect on SOC and organic carbon components. The combined application of organic and inorganic materials could enhance LI, CPI, and the soil carbon pool management index, with the increase in LI and CPI being the primary reason for the increase in CPMI. Correlation analyses revealed that soil organic carbon components and CPMI were significantly positively correlated with greenhouse gas emissions. The combined application of organic and inorganic materials enhanced cumulative CO2 emissions and warming potential (GWP) but decreased GHGI and yielded a maximum of 56365 kg·hm-2. Compared with that in the CK treatment (29073 kg·hm-2), apple yield in MNPK increased by 93.87%. Therefore, applying organic and inorganic fertilizers in dryland apple orchards can improve the accumulation of organic carbon and stabilize the soil carbon pool, which is more beneficial to the sustainable development of orchards.

[Seasonal Regulation of Soil Microbial Carbon and Phosphorus Metabolisms in an Apple Orchard: Evidence from the Enzymatic Stoichiometry Method].

Soil microbial carbon (C), nitrogen (N), and phosphorus (P) nutrient requirements and metabolic limitations are closely related to the availability of environmental nutrients. However, it is unclear how manure and chemical fertilization shift nutrient limitations for microbes in terms of the soil enzymatic stoichiometry in an apple orchard. Therefore, based on the long-term experiment located in an apple orchard established in 2008, this study applied the theory and method of soil enzyme stoichiometry to systematically investigate the effects of the combined application of manure and chemical fertilizers on soil C, N, and P turnover-related enzyme activities (ß-1,4-glucosidase, BG; leucine aminopeptidase, NAG; ß-1,4-N-acetylglucosaminidase, LAP; and acid or alkaline phosphatase, PHOS) and their stoichiometric characteristics and analyzed their relationships with environmental factors and microbial carbon use efficiency. The experiment was designed with four treatments, such as, no fertilization input as the control (CK), single application of chemical fertilizer (NPK), combined application of manure and chemical fertilizer (MNPK), and single application of manure (M). The results revealed that:① at different growth stages of fruit trees, the soil microbial biomass C (microC) content of manure fertilizer treatments (MNPK and M) was significantly higher than that of no manure fertilizer treatments (CK and NPK). The content of microbial biomass N (microN) in the NPK, MNPK, and M treatments increased by 89%, 269%, and 213%, respectively, compared with that in CK (P<0.05). ② Compared with those in the fertilization treatments, CK had higher leaf N and P contents (29.8 g·kg-1 and 2.17 g·kg-1) at the germination stage, and the leaf P content at the germination stage alone was significantly negatively correlated with soil available phosphorus (AP) content. ③ Soil enzyme stoichiometry analysis demonstrated that all data points in this study were above the 1:1 line, indicating that microbial communities had a strong phosphorus limitation. The range of vector length and angle was 0.56-0.79 and 59.3°-67.7°, respectively, in the growth period of fruit trees, and the vector angle was >45° in this study, which also reflected the strong phosphorus limitation of microorganisms. ④ RDA and random forest model analysis showed that organic carbon and available nitrogen (AN) were the main physical and chemical factors affecting vector length; AP, AN, and soil water content were the main physical and chemical factors affecting vector angle. Combined with SEM analysis, AN and dissolved organic carbon (DOC) directly affected microC and microN, AP directly affected microP and microN, DOC and AP directly affected vector length, and AP and microN directly affected vector angle. In addition, microbial carbon utilization was positively correlated with vector length and negatively correlated with vector angle. In summary, the combined application of manure and chemical fertilizers regulated microbial carbon and phosphorus metabolism by affecting soil carbon and phosphorus content at different growth stages of fruit trees, thereby affecting microbial carbon utilization. This study provides a scientific basis for manure and chemical fertilizers to improve soil quality and maintain soil health.

Heart Rate Response Predicts 6-Minutes Walking Distance in Pulmonary Arterial Hypertension.

Because the 6-minute walking test (6MWT) is a self-paced submaximal test, the 6-minute walking distance (6MWD) is substantially influenced by individual effort level and physical condition, which is difficult to quantify. We aimed to explore the optimal indicator reflecting the perceived effort level during 6MWT. We prospectively enrolled 76 patients with pulmonary arterial hypertension and 152 healthy participants; they performed 2 6MWTs at 2 different speeds: (1) at leisurely speed, as performed in daily life without extra effort (leisure 6MWT) and (2) an increased walking speed, walking as the guideline indicated (standard 6MWT). The factors associated with 6MWD during standard 6MWT were investigated using a multiple linear regression analysis. The heart rate (HR) and Borg score increased and oxygen saturation (SpO2) decreased after walking in 2 6MWTs in both groups (all p <0.001). The ratio of difference in HR before and after each test (ΔHR) to HR before walking (HRat rest) and the difference in SpO2 (ΔSpO2) and Borg (ΔBorg) before and after each test were all significantly higher in both groups after standard 6MWT than after leisure 6MWT (all p <0.001). Multiple linear regression analysis revealed that ΔHR/HRat rest was an independent predictor of 6MWD during standard 6MWT in both groups (both p <0.001, adjusted R2 = 0.737 and 0.49, respectively). 6MWD and ΔHR/HRat rest were significantly lower in patients than in healthy participants (both p <0.001) and in patients with cardiac functional class III than in patients with class I/II (both p <0.001). In conclusion, ΔHR/HRat rest is a good reflector of combined physical and effort factors. HR response should be incorporated into 6MWD to better assess a participant's exercise capacity.

Polymorphisms in chicken extracellular fatty acid binding protein gene.

In this study, we report the investigation of extracellular fatty acid binding protein gene (Ex-FABP) genetic polymorphism in a sample of 360 chicken individuals. The screening of the coding regions with their intron-exon boundaries and the proximal flanking regions was performed through a PCR-SSCP strategy. Following sequence analysis revealed 35 novel single nucleotide polymorphisms (SNPs) of chicken Ex-FABP gene. Among the 35 SNPs, twenty-five were found in the introns. And the remaining seven and three SNPs were in the coding region and the 5'UTR, respectively. Two SNPs in the coding region caused two missense mutants and the other five did not result in any amino acid changes. The nature and the distribution of Ex-FABP mutations in three chicken breeds were analyzed. Variations detected here might have an impact on Ex-FABP activity and function and underpin the development of gene markers for chicken fatty deposition and metabolism. The polymorphism, generated by C4715T mutation in exon5, was significantly associated with thickness of subcutaneous fat plus skin in cocks. Subcutaneous fat plus skin of cocks was more thick in TT genotype than in CC genotype (P < 0.05). The Ex-FABP gene could be a candidate locus or linked to a QTL that significantly affects fatty deposition and metabolism in chicken.

[Pattern evolution and impact factor of Jiuduansha Wetland at the Yangtze Estuary during 1989-2020]. / 1989­2020å¹´é•¿æ±Ÿå£ä¹æ®µæ²™æ¹¿åœ°æ ¼å±€æ¼”å˜åŠå½±å“å› ç´ .

Affected by the changes of drainage basin and marine environment and human activities, estuarine wetland is fragile, sensitive, and complex in evolution. Jiuduansha Wetland is the largest estuarine shoal wetland in the Yangtze Estuary, and is undergoing rapid changes due to the reduction of sediment inputs and the invasion of alien species Spartina alterniflora. In this study, the changes of Jiuduansha Wetland from 1989 to 2020 were analyzed through remote sensing interpretation, field investigation, and topographic data analysis. The impacts of watershed sediment reduction and S. alterniflora invasion on Jiuduansha Wetland were analyzed based on the hydrological data of Datong station and the invasion history of S. alterniflora. The results showed that the total area of Jiuduansha Wetland (above -5 m) first increased and then decreased since 1991, reaching its maximum in 2005 (421.16 km2). The area of tidal flat wetland (above 0 m) and wetland vegetation increased continuously from 1989 to 2020, with 1.5 times and 47.1 times increases, respectively. The decreases of sediment supply led to a decrease in the total area of Jiuduansha Wetland (above -5 m) and a decrease growth rate of tidal flat wetland area above 0 m and vege-tation area. The invasive species S. alterniflora had expanded rapidly, occupied the space of native species, and became the dominant species in Jiuduansha Wetland since it was introduced in 1997. Sediment reduction and S. alterniflora invasion had led to the rapid changes of Jiuduansha Wetland structure. In order to avoid the degradation of ecological service, wetland protection and restoration should be taken to maintain the stability and health of Jiu-duansha Wetland.

Biosynthesis of silver nanoparticle composites based on hesperidin and pectin and their synergistic antibacterial mechanism.

Silver nanoparticles (AgNPs) were widely used in the antibacterial field because of their excellent antibacterial properties. In this study, we used hesperidin and pectin as reductants and stabilizers, and prepared uniform and stable Hesperidin-Pectin AgNPs (HP-AgNPs) by a simple microwave-assisted process. Increasing the proportion of hesperidin, P-AgNPs, HP-AgNPs1, HP-AgNPs2 and H-AgNPs were obtained respectively. With the increase of hesperidin ratio, the mean particle size and zeta potential increased gradually. Fourier transform infrared spectroscopy (FTIR) analysis showed that Ag+ was reduced by hesperidin and pectin. Antibacterial tests showed that HP-AgNPs2 showed the MIC values of 66.7 µg/mL against E. coli. In addition, HP-AgNPs2 was selected to clarify its antibacterial mechanism against E. coli. Morphological experiments showed that HP-AgNPs2 stress caused damage to the cell wall of E. coli, as well as leakage of its contents and an increase in reactive oxygen species (ROS). On the other hand, the release of Ag+ during cell co-culture was studied and the results showed that most of the Ag+ released was taken up by E. coli. The synergistic effect of hesperidin and pectin resulted in a significant enhancement of the antibacterial properties of AgNPs. These preliminary data suggest that HP-AgNPs has good antibacterial activity and may be developed as an effective antibacterial nanomaterial.

Morphology and Phylogeny Reveal Five Novel Species in the Genus Cordyceps (Cordycipitaceae, Hypocreales) From Yunnan, China.

The current study was aimed to introduce five new species of Cordyceps from Yunnan, with morphological descriptions, illustrations, color photographs, phylogenetic placement, associated host, and a comparison with allied taxa. The five new species were morphologically distinct from all other Cordyceps sensu lato species, and it was also suggested that they should differ from other species in the genus Cordyceps based on combined multigene analyses. Employing DNA nucleotide sequences of the nrLSU, nrSSU, tef-1α, rpb1, and rpb2, the five new species were recognized in the clade of Cordyceps by using molecular phylogenetic analyses, including five well-supported subclades: three new species, Cordyceps bullispora, Cordyceps longiphialis, and Cordyceps nabanheensis, were found in the subclade of C. pruinosa, and two new species, Cordyceps pseudotenuipes and Cordyceps simaoensis, were located in the subclade of C. tenuipes. The five novel species shared similar morphologies to other species in the genus Cordyceps, with fleshy and brightly pigmented stromata; perithecia superficial to completely immersed, ordinal in arrangement; and hyaline asci, with thickened cylindrical ascus apex. The morphological characteristics of 66 species in Cordyceps sensu stricto, namely, 5 novel species and 61 known taxa, were also compared.

Loss of function of CMPK2 causes mitochondria deficiency and brain calcification.

Brain calcification is a critical aging-associated pathology and can cause multifaceted neurological symptoms. Cerebral phosphate homeostasis dysregulation, blood-brain barrier defects, and immune dysregulation have been implicated as major pathological processes in familial brain calcification (FBC). Here, we analyzed two brain calcification families and identified calcification co-segregated biallelic variants in the CMPK2 gene that disrupt mitochondrial functions. Transcriptome analysis of peripheral blood mononuclear cells (PBMCs) isolated from these patients showed impaired mitochondria-associated metabolism pathways. In situ hybridization and single-cell RNA sequencing revealed robust Cmpk2 expression in neurons and vascular endothelial cells (vECs), two cell types with high energy expenditure in the brain. The neurons in Cmpk2-knockout (KO) mice have fewer mitochondrial DNA copies, down-regulated mitochondrial proteins, reduced ATP production, and elevated intracellular inorganic phosphate (Pi) level, recapitulating the mitochondrial dysfunction observed in the PBMCs isolated from the FBC patients. Morphologically, the cristae architecture of the Cmpk2-KO murine neurons was also impaired. Notably, calcification developed in a progressive manner in the homozygous Cmpk2-KO mice thalamus region as well as in the Cmpk2-knock-in mice bearing the patient mutation, thus phenocopying the calcification pathology observed in the patients. Together, our study identifies biallelic variants of CMPK2 as novel genetic factors for FBC; and demonstrates how CMPK2 deficiency alters mitochondrial structures and functions, thereby highlighting the mitochondria dysregulation as a critical pathogenic mechanism underlying brain calcification.

[Monitoring the sewage degradation by analyzing optic fiber SPR spectrum character].

The working principle of the optic fiber SPR sensor was discussed in the present paper at first. The feasibility of using it to monitor the degradation process of the environmental sewage represented by the methyl orange was studied. Finally, the optic fiber SPR sensor was adopted to monitor the change in degradation concentration represented by the original methyl orange solution on the base of 50 mL initial concentration 30 mg x L(-1), and the optic fiber SPR spectrum character of degradation process was analyzed in detail. Meanwhile the UV spectrophotometer was used to measure the change in concentration in the course of the degradation. The measurement data were analyzed and compared at large. The research work indicates that both the methods have consistent results, as the degradation time increases, the absorbance and concentration of the environmental sewage represented by the methyl orange solution decrease by and by, and the resonant wavelength of the optic fiber SPR sensor blue shifts step by step, as compared to the original standardization methyl orange solution resonant spectrum. It was shown that the methyl orange solution was degraded, and the rate of degradation was up to about 73 percent within two hours. The comparative results illustrate that it is feasible to use the optic fiber SPR sensor to monitor the environmental sewage degradation. The research result not only provides a new monitoring method for the degradation process of the environmental sewage, but also promotes the technique of the SPR sensor combined to the environment monitor by a long way.

[A new noise filtering method of the SPR optical fiber sensor spectrum].

According to the characters of SPR optical fiber sensor spectrum and the requirement of real-time monitoring, a new noise filtering method, mobile lifting wavelet analysis, is presented in this paper. This method is not based on Fourier transform, but on an algorithm of dividing a complicated noise filtering process into a number of reversible simple processes. It is very fast, correct and does not use additional memory. A model of actual SPR optical fiber sensor spectrum is constructed by superposing a certain intensity of Gaussian white noise on the theoretical spectrum, of which the resonant wavelength is 557.70 nm. It applies noise filtering to the simulative spectrum with mobile lifting wavelet analysis based on Haar, CDF(3,1), DD(4,2) and 5/3 mother wavelet respectively and calculates the resonant wavelengths again The results are 556.45, 564.06, 557.27 and 557.91 nm corresponding to each method listed. So a relative error of 0.037 7 percent, obtained after noise filtering with new method based on 5/3 mother wavelet, is the minimum one. It is also lower than 0.430 3 percent obtained after noise filtering with traditional symlet11 wavelet analysis that has been proved to be effective for SPR optical fiber sensor spectrum. At different time gather several spectra of one SPR optical fiber sensor detective system were gathered and mobile lifting wavelet analysis based on 5/3 mother wavelet was done. The result shows that, the standard deviation of resonant wavelengths is reduced to 1.560 8 from 4.186 7 nm, which is calculated before noise filtering. As expected, this result is better than doing the same experiment with traditional symlet11 wavelet analysis, which only reduces the standard deviation to 2.725 3 from 4.186 7 nm. The research shows that mobile lifting wavelet analysis significantly suppresses the system noises, reduces noise influence on the gathering of resonant wavelength information from SPR optical fiber sensor spectrum and gives a guarantee to actual accurate detection with SPR optical fiber sensor.

[Impact of Land Use Type on the Stability and Organic Carbon Content of Soil Aggregates in the Weibei Dryland].

Soil aggregates are important indicators of soil quality and sustainable land utilization, and impact the retention abilities of water and fertilizers and the release of nutrients in soil. This study aimed to understand the effects of two land use types (an orchard and farmland) on the distribution, stability, and organic carbon content of soil aggregates, and provides a theoretical basis for the optimal management of the soil carbon pool in the Weibei Dryland of the Loess Plateau. We examined the soils from an orchard and from farmland by simultaneous sampling and wet sieving; the proportions of large macroaggregates (>2 mm), small macroaggregates (0.25-2 mm), microaggregates (0.053-0.25 mm), and silt and clay (<0.053 mm) were then determined; the content of organic carbon in each aggregate fraction at soil depths of 0-40 cm were also measured, and the total organic carbon content of all aggregates fractions was determined for each soil. The results showed that the type of agricultural land use had a significant effect on the distribution and stability of soil aggregates in the 0-20 cm soil layer, with the relative proportions of the different sized aggregates (>2, 0.25-2, 0.053-0.25, and<0.053 mm) being 12.9%, 51.3%, 28.8%, and 7.0% in the orchards, respectively, and 8.3%, 49.7%, 33.6%, and 8.4% on the farmland, respectively. The proportion of macro-aggregates (>0.25 mm) was significantly higher in the orchard soils than in the farmland soils. Mean weight diameter (MWD) and geometric mean diameter (GMD) are important indicators of the soil aggregate stability; the MWD and GWD of the farmland soils were significantly lower than the orchard soils in the 0-40 cm depth zone (P<0.05). The effects of different land use types on the organic carbon content of soil aggregates was most marked in the 0-10 cm layer. Compared with farmland, the organic carbon content in the large aggregates, intermediate aggregates, micro-aggregates, and the silt and clay fraction of orchard soils were relatively increased by 56.0% (P<0.05), 57.1% (P<0.05), 40.8% (P>0.05), and 13.0% (P>0.05), respectively. Organic carbon storage in each aggregate class (excluding the<0.053 mm fraction) in the orchard soils was higher than in the farmland soils. In the orchard soils, the proportion of soil macro-aggregates (>0.25 mm) and the associated organic carbon content was elevated, damage to aggregates was reduced, and the organic carbon stability was enhanced. In general, the soil aggregate stability and organic carbon content of orchard soils were higher than for the farmland soils. Orchards appear to enhance the physical stability of aggregates with respect to soil organic carbon, contribute to soil organic carbon accumulation, and thus promote soil carbon sequestration.

Bis[2-(2-pyridylmethyl-eneamino)benzene-sulfonato-κN,N',O]zinc(II) dihydrate.

In the title complex, [Zn(C(12)H(9)N(2)O(3)S)(2)]·2H(2)O, the Zn(II) ion lies on a crystallographic inversion center and is coordinated by four N atoms and two O atoms from two tridentate 2-(2-pyridylmethyl-eneamino)benzene-sulfonate ligands in a slightly distorted octa-hedral environment. In the crystal structure, the complex forms a two-dimensional network through inter-molecular O-H⋯O and C-H⋯O hydrogen bonds.

[Soil moisture variation under different water and fertilization managements in apple orchard of Weibei dryland, China]. / 渭北旱塬苹果园不同水肥管理模式下的土壤水分差异.

To evaluate the variations of soil moisture under different water and fertilizer treatments in apple orchard in the Weibei dryland, a field experiment was carried out in 2013-2016 at Tianjiawa Village, Baishui County, Shaanxi Province. There were three treatments, i.e., farmers traditional model (only addition of NPK chemical fertilizer, FM), extension model (swine manure and NPK chemical fertilizer combined with black plastic film in tree row space, EM), and optimized model (swine manure and NPK chemical fertilizer combined with black plastic film in tree row space and planting rape in the inter-row of apple trees, OM). The results showed that OM treatment significantly increased soil water storage capacity in 0-200 cm soil layer. Water content of 0-100 cm soil layer was increased by 5.6% and 15.3% in the dry season compared with FM and EM treatment, respectively. Moreover, the soil water relative deficit index of OM was lower than that of EM in 200-300 cm soil layer. The rainfall infiltration in the dry year could reach 300 cm depth under OM. Meanwhile, OM stabilized soil water content and efficiently alleviated the desiccation in deep soil layer. Compared with FM and EM, the 4-year average yield of OM was increased by 36.6% and 22.5%, respectively. In summary, OM could increase water use efficiency through increasing the contents of available soil water and improving the soil water condition in shallow and deep layers, which help alleviate the soil deficit in deep layer and increase yield.

[Effects of grass cover combined with different fertilization regimes on soil nutrients and enzyme activities in apple orchard in Weibei dryland, China.] / æ¸­åŒ—æ—±åœ°è‹¹æžœå›­ç”Ÿè‰è¦†ç›–ä¸‹ä¸åŒè‚¥æ–™é æ–½å¯¹åœŸå£¤å »åˆ†å’Œé ¶æ´»æ€§çš„å½±å“.

The split-plot design was adopted in this experiment, with main treatments of grass cover and control and sub-treatments included four fertilization regimes: no fertilization, CK; manure, M; N,P and K fertilizer, NPK; and NPK fertilizer combined with manure, MNPK. Microplate fluorimetry was used to study the effects of grass cover combined with different fertilization regimes on the enzyme activities in apple orchard. The results showed that after mowing the grass (the residues were left on the soil surface as mulch), the soil water content, available P, nitrite nitrogen and the activities of ßX, NAG, ßG, CBH were increased compared to the control, with no significant differences for total nitrogen, soil organic carbon, and AKP activity. For grass cover treatment, the total nitrogen, soil organic carbon, and the activities of ßX, NAG, ßG, CBH, AKP were both improved before and after mowing the grass. However, the soil water content, available phosphorus, and nitrate nitrogen of grass cover treatment were lower than that of the control before mowing the grass. Under grass cover condition, the total nitrogen, available P, and soil organic carbon of M and MNPK were higher than that of CK and NPK in both before and after mowing the grass periods, with the activities of ßX, NAG, ßG, CBH, AKP of MNPK higher than that of NPK. Under the control condition, the available P, soil organic carbon (SOC), nitrite nitrogen, total nitrogen and the activities of ßG, CBH, AKP of MNPK higher than that of CK and NPK before and after mowing the grass. Redundancy analysis showed that the activities of soil enzymes were significantly correlated with the soil nutrients, and could reflect the soil fertility. Thus, grass cover combined with MNPK significantly increased the soil nutrient contents and soil enzyme activities, and was an important practice to prevent the decrease of soil fertility and benefit the sustainability of local apple industry.

[Alternative stable states in coastal intertidal wetland ecosystems of Yangtze estuary, China]. / 长江口滨海湿地潮间带生态系统的多稳态特征.

Alternative stable states phenomenon widely exists in a variety of ecosystems and is closely related to ecosystem health and sustainable development. Although alternative stable states research has become the focus and hotspot of the ecology researches, only a few empirical evidences supported its behavior and mechanisms in coastal wetland ecosystems up to now. In our study, ta-king the intertidal wetland ecosystem in Chongming Dongtan Nature Reserve as study area, we aimed to: 1) test the existence of alternative stable states based on judgment conditions (bimodal characteristic and threshold effect) and determine the relative stable state types; 2) explore the formation mechanisms of alternative stable states by monitoring hydrological conditions, sediment accretion dynamics as well as vegetation growth parameters and analyzing the positive feedbacks between saltmarsh vegetation and sedimentary geomorphology. Our results showed that: 1) Normalized difference vegetation index (NDVI) frequentness distribution revealed obvious bimodality at saltmarsh pioneer zone. Propagule biomass threshold limited the establishment of plant patches representing the "saltmarsh" state. The presence of bimodality and biomass threshold demonstrated there are "mudflat" stable state and "saltmarsh" stable state with distinct structure and function in intertidal wetland ecosystem. 2) Current velocities, turbidities and direction perpendicular to the vegetation zone were the most important factors responsible for the sediments rapid accretion at saltmarsh pioneer zone in spring and summer. Sediments accretion significantly promoted the growth of saltmarsh plant. The positive feedbacks between plant growth and sediments accretion resulted in the formation of alternative stable states. 3) The expansion pattern of saltmarshes in the Chongming Dongtan intertidal wetland ecosystem also suggested that increases of sediments accretion could trigger the formation of "mudflat" stable state and "saltmarsh" stable state on landscape scale. The results from this study could enrich regime shift mechanisms researches and provide the scientific supports for coastal zone protection, restoration and comprehensive management, which could have important theoretical and practical meaning.