[Identification and characterization of a novel polyamide hydrolase].

The widespread use of non-naturally degradable plastics is causing increasingly serious harm to the environment. Reducing plastic pollutants has become the core of ecological and environment management. Biological methods such as enzymes demonstrate advantages in depolymerizing plastics with mild reaction conditions and recycling of depolymerization products. However, there are few reports on the biological depolymerization of polyamide plastics. In this study, by using 4-nitropropionanilide as the model substrate, we screened against our plastic depolymerase library and obtained a Meiothermus ruber-derived enzyme (MrABH) that can hydrolyze the polyamide bond. We expressed this enzyme in Escherichia coli and purified the protein by affinity chromatography. Furthermore, we investigated the catalytic properties, enzymatic properties, and catalytic products of this enzyme with polyamide as the substrate. MrABH had good stability at pH 8.0-10.0, with the optimal performance at pH 9.0 and 30 ℃. The catalytic performance of this enzyme for ester bonds and amide bonds was similar. MrABH can catalyze the depolymerization of PA6 and PA66 to produce monomers and oligomers, demonstrating the potential to be used in the depolymerization and recycling of polyamide.

[Rainwater harvesting effect of biocrusted soil-surfaces and the key influencing factors in the hilly region of Chinese Loess Plateau]. / é»„åœŸä¸˜é™µåŒºç”Ÿç‰©ç»“çš®é›†é›¨é¢çš„é›†é›¨æ•ˆæžœåŠå ¶å ³é”®å½±å“å› å­.

In the hilly region of Chinese Loess Plateau, rainwater harvesting is a common ecological engineering measure utilized to reduce soil erosion and amplify the efficiency of water resource utilization. However, the effects on rainwater harvesting and the chief influencing factors of biocrusts as a potential material are unclear. In this study, we conducted a field simulation experiment with intensities of 40, 60, 80, and 100 mm·h-1 between bare soil and biocrusts developed in aeolian soils, with bare soil as a control to explore the differences of the initial abstraction time, cumulative rainfall amount, and rainfall harvesting efficiency. We further analyzed the influencing factors of the rainwater harvesting effect. The results showed that the biocrusted soil-surfaces significantly decreased the initial abstraction time. When compared with the cyano biocrusts and bare soil, the reduction of the initial abstraction time of moss biocrusts was decreased by 49.7%-77.5% and 89.7%-110.0% when the rainfall intensities ranged from 40 to 100 mm·h-1 and the slope was 40°. In addition, biocrusted soil surfaces significantly increased the cumulative rainfall amount and rainfall harvesting efficiency. These differences were considerable amongst the dissimilar surface cover types. In comparison to bare soil, when the rainfall intensity was 100 mm·h-1 and the slope was 40°, the cumulative rainfall harvesting efficiency of moss and cyano biocrusts was increased by 29.6% and 7.8%, respectively. Both moss and cyano biocrusts increased rainfall harvesting efficiency of 25.7% and 6.8%, respectively. Variance analysis demonstrated that the rainfall harvesting efficiency was appreciably affected by surface cover type, slope, and rainfall intensity. The interaction between these factors was considerable except for slope and rainfall intensity. Additionally, important considerations for the actual construction included slope length, slope, and biocrust cultivation. In conclusion, biocrusted soil-surfaces have a high rainfall harvesting efficiency, but moss biocrusts have a much greater rain-collecting effect that improves even more as the slope and intensity of the rain increases.

Lanthanide-Based Molecular Magnetic Semiconductors.

Magnetic semiconductors, with integrated properties of ferromagnets and semiconductors, are significant for developing next-generation spintronic devices. Herein two atomically precise clusters of dysprosium(III) tellurides, formulated respectively as [Na2(15-crown-5)3(py)][(η5-Cp*Dy)5(Te)6](py)4 (Dy5Te6, Cp* = pentamethylcyclopentadienyl; py = pyridine) and [K(2,2,2-cryptand)]2[(η5-Cp*Dy)6(Te3)(Te2)2(Te)3] (Dy6Te10), are reported. Crystallographic studies revealed the presence of multifarious tellurido ligands within the polyhedral cluster cores. Spectroscopic and magnetic studies showed that both clusters are single-molecule magnets exhibiting slow magnetic relaxation behaviors at low temperatures and semiconductors with optical bandgaps comparable to benchmark semiconductors. These clusters represent probably the first lanthanide-based molecular magnetic semiconductors.

Application of Directed Evolution and Machine Learning to Enhance the Diastereoselectivity of Ketoreductase for Dihydrotetrabenazine Synthesis.

Biocatalysis is an effective approach for producing chiral drug intermediates that are often difficult to synthesize using traditional chemical methods. A time-efficient strategy is required to accelerate the directed evolution process to achieve the desired enzyme function. In this research, we evaluated machine learning-assisted directed evolution as a potential approach for enzyme engineering, using a moderately diastereoselective ketoreductase library as a model system. Machine learning-assisted directed evolution and traditional directed evolution methods were compared for reducing (±)-tetrabenazine to dihydrotetrabenazine via kinetic resolution facilitated by BsSDR10, a short-chain dehydrogenase/reductase from Bacillus subtilis. Both methods successfully identified variants with significantly improved diastereoselectivity for each isomer of dihydrotetrabenazine. Furthermore, the preparation of (2S,3S,11bS)-dihydrotetrabenazine has been successfully scaled up, with an isolated yield of 40.7% and a diastereoselectivity of 91.3%.

Structure-based reshaping of a new ketoreductase from Sphingobacterium siyangense SY1 toward α-haloacetophenones.

Ketoreductases play an indispensable role in the asymmetric synthesis of chiral drug intermediates, and an in-depth understanding of their substrate selectivity can improve the efficiency of enzyme engineering. In this endeavor, a new short-chain dehydrogenase/reductase (SDR) SsSDR1 identified from Sphingobacterium siyangense SY1 by gene mining method was successfully cloned and functionally expressed in Escherichia coli. Its activity against halogenated acetophenones has been tested and the results illustrated that SsSDR1-WT exhibits high activity for 3,5-bis(trifluoromethyl)acetophenone (1f), an important precursor in the synthesis of aprepitant. In addition, SsSDR1-WT showed obvious substrate preference for acetophenones without α-halogen substitution compared to their α-halogen analogs. To explore the structural basis of substrate selectivity, the X-ray crystal structures of SsSDR1-WT in its apo form and the complex structure with NAD were resolved. Taking 2-chloro-1-(3, 4-difluorophenyl) ethanone (1i) as the representative α-haloacetophenone, the key sites affecting substrate selectivity of SsSDR1-WT were identified and through the rational remodeling of the cavities C1 and C2 of SsSDR1, an excellent mutant I144A/S153L with significantly improved activity against α-halogenated acetophenones was obtained. The asymmetric catalysis of 1f and 1i was performed at the scale of 50 mL, and the space-time yields (STY) of the two were 1200 and 6000 g/L∙d, respectively. This study not only provides valuable biocatalysts for halogenated acetophenones, but also yields insights into the relationship between the substrate-binding pocket and substrate selectivity.

Prognostic implications of preoperative, postoperative, and dynamic changes of alpha-fetoprotein and des-gamma (γ)-carboxy prothrombin expression pattern for hepatocellular carcinoma after hepatic resection: a multicenter observational study.

Background: The utility of pre- and post-operative alpha-fetoprotein (AFP) and des-gamma (γ)-carboxy prothrombin (DCP) expression patterns and their dynamic changes as predictors of the outcome of hepatic resection for hepatocellular carcinoma (HCC) has yet to be well elucidated. Methods: From a multicenter database, AFP and DCP data during the week prior to surgery and the first post-discharge outpatient visit (within 1-2 months after surgery) were collected from patients with HCC who underwent hepatectomy. AFP-DCP expression patterns were categorized according to the number of positive tumor markers (AFP ≥ 20ng/mL, DCP ≥ 40mAU/mL), including double-negative, single-positive, and double-positive. Changes in the AFP-DCP expression patterns were delineated based on variations in the number of positive tumor markers when comparing pre- and post-operative patterns. Results: Preoperatively, 53 patients (8.3%), 337 patients (52.8%), and 248 patients (38.9%) exhibited double-negative, single-positive, and double-positive AFP-DCP expression patterns, respectively. Postoperatively, 463 patients (72.6%), 130 patients (20.4%), and 45 patients (7.0%) showed double-negative, single-positive, and double-positive AFP-DCP expression patterns, respectively. Survival analysis showed a progressive decrease in recurrence-free (RFS) and overall survival (OS) as the number of postoperative positive tumor markers increased (both P < 0.001). Multivariate analysis showed that postoperative AFP-DCP expression pattern, but not preoperative AFP-DCP expression pattern, was an independent risk factor for RFS and OS. Further analysis showed that for patients with positive preoperative markers, prognosis gradually improves as positive markers decrease postoperatively. In particular, when all postoperative markers turned negative, the prognosis was consistent with that of preoperative double-negative patients, regardless of the initial number of positive markers. Conclusions: AFP-DCP expression patterns, particularly postoperative patterns, serve as vital sources of information for prognostic evaluation following hepatectomy for HCC. Moreover, changes in AFP-DCP expression patterns from pre- to post-operation enable dynamic prognostic risk stratification postoperatively, aiding the development of individualized follow-up strategies.

Asymmetric Synthesis of ß-Hydroxyphosphonates via a Chemoenzymatic Cascade.

Chiral ß-hydroxyphosphonates are essential building blocks for organophosphorus compounds. However, the asymmetric synthesis of these units remains a significant challenge. Herein, we describe a one-pot chemoenzymatic cascade process to access chiral ß-hydroxyphosphonates, which combines photo-oxidative chemical reactions and bioreductions. The incorporation of photooxidation in the chemical reaction resulted in up to 92% yield and >99% enantiomeric excess (ee) of ß-hydroxyphosphonates in the cascade. In addition, the scale-up of diethyl (S)-(2-hydroxy-2-phenylethyl)phosphonate demonstrates the potential application of this strategy.

A Bis-Cyclopentadienyl Ligand-Supported Di-Iron Trihydride Motif as a Synthon for Access to Heterobimetallic Trinuclear Complexes.

Herein, we report the synthesis of a flexible bis-cyclopentadienyl ligand L (the doubly deprotonated form of H2L (1,3-bis(2,4-di-tert-butylcyclopentadienyldimethylsilyl)benzene)), demonstrating its ability to stabilize a series of di-iron hydrido complexes. Notably, this ligand facilitates the isolation of an unprecedented anionic cyclopentadienyl ligand-supported di-iron trihydride complex, LFe2(µ-H)3Li(THF) (2), functioning as a synthon for the [Fe2(µ-H)3]- core and providing access to heterobimetallic complexes 4-6 with coinage metals.

Three-Dimensional Analysis of Bone Remodeling After Closed Treatment for Mandibular Condylar Head Fracture.

Closed treatment of mandibular condylar fractures has been used for its indications based on the fracture site, fracture status, and patient age. Posttreatment mandibular condyle size is associated with mandibular function; however, a few studies have reported bone remodeling patterns and volume changes in the condyle and glenoid fossa after mandibular condylar head fractures (CHFs). Therefore, volumetric changes in the mandibular condyle and glenoid fossa were analyzed in the present study, and bone remodeling patterns were evaluated after mandibular CHFs. The present study included 16 condyles from 12 patients who received closed treatment for CHF. After reconstruction of a 3-dimensional skull model, including the mandible, using computed tomography data taken immediately after injury and 6 months after treatment, volume changes in the mandibular condyle and glenoid fossa were analyzed. The condylar volume increased by 0.32±0.66 cm3 during the 6-month healing period without statistical significance (P=0.093). Regarding the glenoid fossa, the fossa showed a statistically significant volume increase of 0.41±0.59 cm3 (P=0.021), and 12 glenoid fossae (75%) showed downward bone apposition; however, no change or only mild bone resorption was observed in 4 glenoid fossae (25%). The results of this study indicated that the volume changes in the mandibular condyle after closed treatment of a mandibular CHF are not significant, and the glenoid fossa adapts to the displaced mandibular condyle through downward growth accompanied by volume increase.

A Cubic Tinkertoy-like Heterometallic Cluster with a Record Magnetocaloric Effect.

Clusters showing a giant magnetocaloric effect (MCE) are of interest as molecular coolants for magnetic refrigeration. Herein, we report two heterometallic clusters, denoted as Gd152Ni14@Cl24 and Sm152Ni8, just to highlight their inorganic core motifs, obtained by ligand-controlled co-hydrolysis of Ni2+ and Ln3+ (Ln = Gd, Sm) in the presence of N-(2-hydroxyethyl)iminodiacetic acid (H2HEIDA). Both clusters display fascinating cubic Tinkertoy-like structures, with the core motifs being built of multiple metallic shells of Platonic and Archimedean polyhedra. The isothermal magnetic entropy change─a direct measurement of MCE─was determined to be 52.65 J·kg-1·K-1 at 2.5 K and 7.0 T for the Gd-containing cluster; this value is the highest known for any molecular clusters so far reported.

A tetravalent praseodymium complex with field-induced slow magnetic relaxation.

Herein the synthesis, structural characterization, and magnetic properties of a Pr(IV) complex [Pr(OSiPh3)4(L)] (1, L = 4,4'-dimethoxy-2,2'-bipyridine) are reported. The stability of the Pr(IV) complex significantly enhanced with the use of the bidentate ligand L. Slow magnetic relaxation was observed at low temperatures, indicating that the complex may be the first single-ion magnet with a tetravalent lanthanide ion being the magnetic center.

RNA sequencing and proteomic profiling reveal alterations by MPTP in chronic stomach mucosal injury in tree shrew Chinese (Tupaia belangeri chinensis).

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that can cause gastrointestinal ulcers by affecting dopamine levels. Therefore, MPTP has been considered a toxic substance that causes gastric ulcer disease in experimental animals. In this study, tree shrews were used as the animal model of gastric mucosa injury, and MPTP was intraperitoneally injected at a lower MPTP dosage 2 mg/kg/day for 13 weeks, while tree shrews were not injected as the control group. Under the light microscope, local congestion or diffuse bleeding points of gastric mucosa and multiple redness and swelling bleeding symptoms on the inner wall were observed in the treatment group, as well as immune cell infiltration was found in HE staining, but no such phenomenon was observed in the control group. In order to explore the molecular basis of changes in MPTP induced gastric mucosa injury, the transcriptome and proteome data of gastric mucosa were analyzed. We observed significant differences in mRNA and protein expression levels under the influence of MPTP. The changes in mRNA and proteins are related to increased immune infiltration, cellular processes and angiogenesis. More differentially expressed genes play a role in immune function, especially the candidate genes RPL4 and ANXA1 with significant signal and core role. There are also differentially expressed genes that play a role in mucosal injury and shedding, especially candidate genes GAST and DDC with certain signaling and corresponding functions. Understanding the factors and molecular basis that affect the expression of related genes is crucial for coping with Emotionality gastric mucosa injury disease and developing new treatment methods to establish the ability to resist disease.

Unveiling transient current response in bilayer oxide-based physical reservoirs for time-series data analysis.

Physical reservoirs employed to map time-series data and analyze extracted features have attracted interest owing to their low training cost and mitigated interconnection complexity. This study reports a physical reservoir based on a bilayer oxide-based dynamic memristor. The proposed device exhibits a nonlinear current response and short-term memory (STM), satisfying the requirements of reservoir computing (RC). These characteristics are validated using a compact model to account for resistive switching (RS) via the dynamic evolution of the internal state variable and the relocation of oxygen vacancies. Mathematically, the transient current response can be quantitatively described according to a simple set of equations to correlate the theoretical framework with experimental results. Furthermore, the device shows significant reliability and ability to distinguish 4-bit inputs and four diverse neural firing patterns. Therefore, this work shows the feasibility of implementing physical reservoirs in hardware and advances the understanding of the dynamic response.

Substituent Positioning Effects on the Magnetic Properties of Sandwich-Type Erbium(III) Complexes with Bis(trimethylsilyl)-Substituted Cyclooctatetraenyl Ligands.

Lanthanide complexes with judiciously designed ligands have been extensively studied for their potential applications as single-molecule magnets. With the influence of ligands on their magnetic properties generally established, recent research has unearthed certain effects inherent to site differentiation due to the different types and varying numbers of substituents on the same ligand platform. Using two new sandwich-type Er(III) complexes with cyclooctatetraenyl (COT) ligands featuring two differently positioned trimethylsilyl (TMS) substituents, namely, [Li(DME)Er(COT1,5-TMS2)2]n (Er1) and [Na(DME)3][Er(COT1,3-TMS2)2] (Er2) [COT1,3-TMS2 and COT1,5-TMS2 donate 1,3- and 1,5-bis(trimethylsilyl)-substituted cyclooctatetraenyl ligands, respectively; DME = 1,2-dimethoxyethane], and with reference to previously reported [Li(DME)3][Er(COT1,4-TMS2)2] (A) and [K(DME)2][Er(COT1,4-TMS2)2] (B), any possible substituent position effects have been explored for the first time. The rearrangement of the TMS substituents from the starting COT1,4-TMS2 to COT1,3-TMS2 and COT1,5-TMS2, by way of formal migration of the TMS group, was thermally induced in the case of Er1, while for the formation of Er2, the use of Na+ in the placement of its Li+ and K+ congeners is essential. Both Er1 and Er2 display single-molecule magnetic behaviors with energy barriers of 170(3) and 172(6) K, respectively. Magnetic hysteresis loops, butterfly-shaped for Er1 and wide open for Er2, were observed up to 12 K for Er1 and 13 K for Er2. Studies of magnetic dynamics reveal the different pathways for relaxation of magnetization below 10 K, mainly by the Raman process for Er1 and by quantum tunneling of magnetization for Er2, leading to the order of magnitude difference in magnetic relaxation times and sharply different magnetic hysteresis loops.

Association of hepatitis B virus DNA levels with efficacy and safety outcomes in patients with hepatitis B virus-associated advanced hepatocellular carcinoma receiving tyrosine kinase inhibitor plus anti-PD-1 antibody: a multicenter propensity-matched study.

BACKGROUND: The efficacy and safety of tyrosine kinase inhibitors (TKIs) combined with anti-PD-1 antibodies (α-PD-1) in advanced hepatocellular carcinoma (HCC) with high hepatitis B virus (HBV) DNA levels (>500 IU/mL) remain unclear. METHODS: We retrospectively assessed patients from seven medical institutions diagnosed with HBV-related HCC, undergoing treatment with TKIs and α-PD-1 in conjunction with antiviral therapies. Based on HBV-DNA levels, patients were categorized into either high (HHBV-DNA, >500 IU/mL) or low HBV-DNA (LHBV-DNA, ≤500 IU/mL) cohorts Propensity score matching (PSM) was used to minimize baseline imbalance between groups. RESULTS: 149 patients were included, with 66 patients exhibiting HBV-DNA > 500 IU/mL and 83 patients presenting HBV-DNA ≤ 500 IU/mL. Compared with the LHBV-DNA cohort, the HHBV-DNA cohort had a greater incidence of serum HBeAg positivity, tumor diameter ≥ 10 cm, and vascular invasion. Following PSM, 57 individuals were enrolled in each group. Oncological outcomes were comparable between HHBV-DNA and LHBV-DNA cohorts before and after PSM. Before PSM, the median PFS and OS were 6.1 months and 17.5 months in the HHBV-DNA cohort and 6.7 months and 19.3 months in the LHBV-DNA cohort (all P > 0.05). After PSM, the median PFS and OS were 6.0 months and 19.5 months in the HHBV-DNA cohort and 6.0 months and 17.1 months in the LHBV-DNA cohort, respectively (all P > 0.05). Safety profiles were equivalent across cohorts with no fatal incidents reported. Seven patients (4.7 %) had HBV reactivation. 1 (0.7 %) from HHBV-DNA and 6 (4.0 %) from LHBV-DNA (P = 0.134). Only one patient developed HBV-related hepatitis. CONCLUSIONS: The effectiveness and safety of TKIs plus α-PD-1 in advanced HCC with HBV-DNA > 500 IU/mL were not compromised in the context of concomitant antiviral therapy.

Hsa_circ_0001687 Function as a ceRNA to Facilitate Hepatocellular Carcinoma Progression via miR-140- 3p/FOXQ1 Axis.

BACKGROUND: Increasingly convincing evidence has revealed that circular RNAs (circRNAs) are critical regulatory components of hepatocellular carcinoma (HCC) genesis. However, the expression of circRNAs in HCC and the relevance of circRNAs to HCC progression remain largely unexplained. METHODS: qRT-PCR or western blotting was utilized to confirm circ_0001687, miR-140-3p, and Forkhead Box q1 (FOXQ1) levels in HCC tissues or cells. Cell proliferation ability was evaluated via CCK-8 and colony formation assay. The correlation of circ_0001687 or FOXQ1 and miR-140- 3p was determined using dual luciferase reporter assay. Nude mice xenograft tumor model was constructed to verify the effect of circ_0001687 on tumor growth. RESULTS: Circ_0001687 was elevated in HCC. Function assays and the nude mice xenograft tumor model indicated that circ_0001687 acts as a promoting gene in HCC to regulate the proliferation of the tumor cell and foster tumor growth. Further mechanistic exploration revealed that the tumor growth-promoting mechanism of circ_0001687 relied on blocking the inhibitory effect of miR-140- 3p on FOXQ1 and activating FOXQ1 expression. CONCLUSION: This research indicated the role of circ_0001687/miR-140-3p/FOXQ1 network in regulating HCC development. These may provide new insights into the treatment of HCC.

Asymmetric Plasmonic Moth-Eye Nanoarrays with Side Opening for Broadband Incident-Angle-Insensitive Antireflection and Absorption.

Plasmonic absorbers with broadband angle-insensitive antireflection have attracted intense interests because of its wide applications in optical devices. Hybrid surfaces with multiple different sub-wavelength array units can provide broadened antireflection, while many of these antireflective surfaces only work for specific angles and require high complexity of nanofabrication. Here, a plasmonic asymmetric nanostructure composed of the moth-eye dielectric nanoarray partially modified with the top Ag nanoshell providing a side opening for broadband incident-angle-insensitive antireflection and absorption, is rationally designed by nanoimprinting lithography and oblique angle deposition. This study illustrates that the plasmonic asymmetric nanostructure not only excites strong plasmonic resonance, but also induces more light entry into the dielectric nanocavity and then enhances the internal scattering, leading to optimized light localization. Hence, the asymmetric nanostructure can effectively enhance light confinement at different incident angles and exhibit better antireflection and the corresponding absorption performance than that of symmetric nanostructure over the visible wavelengths, especially suppressing at least 16.4% lower reflectance in the range of 645-800 nm at normal incidence.Moreover, the reflectance variance of asymmetric nanostructure with the incident angle changing from 5° to 60° is much smaller than that of symmetric nanostructure, making our approach relevant for various applications in photocatalysis, photothermal conversion, and so on.

Boost immunizations with NA-derived peptide conjugates achieve induction of NA inhibition antibodies and heterologous influenza protections.

Neuraminidase is suggested as an important component for developing a universal influenza vaccine. Targeted induction of neuraminidase-specific broadly protective antibodies by vaccinations is challenging. To overcome this, we rationally select the highly conserved peptides from the consensus amino acid sequence of the globular head domains of neuraminidase. Inspired by the B cell receptor evolution process, a reliable sequential immunization regimen is designed to result in immuno-focusing by steering bulk immune responses to a selected region where broadly protective B lymphocyte epitopes reside. After priming neuraminidase protein-specific antibody responses in C57BL/6 or BALB/c inbred mice strains by immunization or pre-infection, boost immunizations with certain neuraminidase-derived peptide-keyhole limpet hemocyanin conjugates significantly strengthened serum neuraminidase inhibition activities and cross-protections. Overall, this study provides proof of concept for a peptide-based sequential immunization strategy for achieving targeted induction of cross-protective antibody response, which provides references for designing universal vaccines against other highly variable pathogens.

Electron Paramagnetic Resonance Spectra of Pentagonal Bipyramidal Gadolinium Complexes.

Gadolinium is a special case in spectroscopy because of the near isotropic nature of the 4f7 configuration of the +3 oxidation state. Gd3+ complexes have been studied in several symmetries to understand the underlying mechanisms of the ground state splitting. The abundance of information in Gd3+ spectra can be used as a probe for properties of the other rare earth ions in the same complexes. In this work, the zero-field splitting (ZFS) of a series of Gd3+ pentagonal bipyramidal complexes of the form [GdX1X2(Leq)5]n+ [n = 1, X = axial ligands: Cl-, -OtBu, -OArF5 or n = 3, X = tBuPO(NHiPr)2, Leq = equatorial ligand: Py, THF or H2O] with near fivefold symmetry axes along X1-Gd-X2 was investigated. The ZFS parameters were determined by fitting of room-temperature continuous wave electron paramagnetic resonance (EPR) spectra (at X-, K-, and Q-band) to a spin Hamiltonian incorporating extended Stevens operators compatible with C5 symmetry. Examination of the acquired parameters led to the conclusion that the ZFS is dominated by the B20 term and that the magnitude of B20 is almost entirely dependent on, and inversely proportional to, the donor strength of the axial ligands. Surveying the continuous shape measure and the X1-Gd-X2 angle of the complexes showed that there is some correlation between the proximity of each complex to D5h symmetry and the magnitude of the B65 parameter, but that the deformation of the X1-Gd-X2 angle is more significant than other distortions. Finally, the magnitude of B20 was found to be inversely proportional to the thermal barrier for the reversal of the magnetic moment (Ueff) of the corresponding isostructural Dy3+ complexes.

Effects of cyanobacteria- and moss-biocrusts on soil aggregate stability and splash erosion in croplands of the China Mollisols area.

To investigate the effects of biocrusts development on aggregate stability and splash erosion of Mollisols and to understand its function in soil and water conservation, we collected biocrusts (cyano crust and moss crust) samples in croplands during the growing season and measured the differences in aggregate stability between biocrusts and uncrusted soil. The effects of biocrusts on reduction of raindrop kinetic energy were determined and splash erosion amounts were obtained with single raindrop and simulated rainfall experiments. The correlations among soil aggregate stability, splash erosion characteristics, and fundamental properties of biocrusts were analyzed. The results showed that compared to uncrusted soil, the cyano crust and the moss crust decreased the proportion of soil water-stable aggregates <0.25 mm by 10.5% and 21.8%, respectively, while their soil water-stable aggregates 5-10 mm were 4.0 and 8.8 times as that of uncrusted soil. In contrast to uncrusted soil, the macroaggregate content (R0.25), mean weight diameter (MWD), and geometric mean diameter (GMD) of biocrusts were 31.5%, 76.2%, and 33.5% higher, respectively. In addition, biocrusts reduced raindrop kinetic energy by an average of 0.48 J compared to uncrusted soil. The breakthrough raindrop kinetic energy of cyano crust and moss crust were 2.9 and 26.2 times as that of uncrusted soil, while the reduction of raindrop kinetic energy by cyano crust with high biomass was 1.3 and 6.6 times as that of medium and low biomass, respectively. Under the single raindrop and simulated rainfall conditions, biocrusts reduced splash erosion amounts by 47.5% and 79.4%, respectively. The proportion of aggregates >0.25 mm in the splash soil particles of biocrusts (37.9%) was 40.3% lower than that of uncrusted soil, while the proportion of aggregates >0.25 mm decreased as biocrust biomass increased. Moreover, the aggregate stability, splash erosion amount, and fundamental properties of biocrusts were significantly correlated. The MWD of aggregates was significantly and negatively correlated with the splash erosion amount under single raindrop and simulated rainfall conditions, indicating that the improved aggregate stability of surface soil caused by biocrusts accounted for reducing splash erosion. The biomass, thickness, water content, and organic matter content of biocrusts had significant effects on aggregate stability and splash characteristics. In conclusion, biocrusts significantly promoted soil aggregate stability and reduced splash erosion, which had great significance to soil erosion prevention and the conservation and sustainable utilization of Mollisols.