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Abundant landslide deposits were triggered by the Wenchuan earthquake, providing a rich source of material for subsequent debris flows or slope failures under rainfall conditions. A good understanding of the physical and mechanical properties of the landslide deposits is very important to the research on slope failure mechanisms and the initiation of debris flow. Laboratory biaxial compression tests are used to study the material compositions and water content impacts on the mechanical properties of landslide deposits, and a discrete element method (a bond-contact model) is used to study the particle stiffness, bond force, friction coefficient and confining stress impact on the mechanical behaviors and the relationships between the numerical and experimental parameters. The experimental results show that the failure stress of landslide deposits is decreased with increasing content of fine particles and also with increased water content, especially at the initial increasing stage. Cohesion of the saturated landslide deposits is increased, but the friction angle is decreased with the increase in the fine particle content. Shear strength parameters (the cohesion and friction angle) are decreased with the increasing water content at the initial increasing stage, and then, they slowly decrease. There is a critical value of the water content at 5%-7% (in weight) for the failure stress and shear strength parameters of the landslide deposits. Quadratic equations are presented to describe the relation between the bond force and cohesion, and the numerical friction coefficient and the experimental friction angle. [ABSTRACT FROM AUTHOR]

A crack will propagate under biaxial loading conditions forming wing cracks, where there is a plastic core region at the crack tip. In this paper, mixed mode cracks are divided into two types: tension cracks and compression-shear cracks. A computational method for determining the stress intensity factors at the crack tip is established based on the crack tip elastic stresses. The stress intensity factors under different tensile and compressive loading conditions are computed. The friction effect at the crack surface is considered for the crack initiation and propagation problem of a compression-shear crack. The minimum J2 (second invariant variable of the stress deviation) yield function is used to determine the crack initiation angle of a mixed mode crack. Computed results show that the crack initiation angle is influenced by the crack inclination, loading pattern, loading ratio and the friction effect of crack surface. [ABSTRACT FROM AUTHOR]

Elastic bicomponent networks with shape memory effect were obtained via cross-linking reactions of unsaturated polyester with methacrylates. Unlike conventional shape memory polymers, the new material is transparent, rubbery, and can be tailored to various transition temperatures by macromolecular engineering. Various unsaturated copolymers of α-methylene-γ-butyrolactone and ε-caprolactone were synthesized by ring-opening mechanism. Depending on the composition of the unsaturated polyester materials, their mechanical properties and glass transition temperature were varied. [ABSTRACT FROM AUTHOR]

We report on the synthesis of poly( l-lysine- b-caprolactone) block copolymers via an original and elegant approach whereby Z- l-lysine is first polymerized in the presence of allylamine and the resulting amino-terminated poly(Z- l-lysine) is then used in situ as macroinitiator for the polymerization of ε-caprolactone in the presence of tin(II) octanoate as catalyst. A range of poly(ester- b-peptide)s were obtained by varying the ratio of polypeptide to polycaprolactone units. After removal of the Z group of l-lysine units, the copolymers were soluble in water and their solution behavior was examined. They spontaneously form micelle-like objects in solution with sizes around 10 and 70 nm depending on the block lengths of the hydrophilic and hydrophobic sequences. The smaller size particles would adopt a core−shell morphology while the larger particles would be more in line with a vesicle morphology. [ABSTRACT FROM AUTHOR]

3,5,5‘-Trimethylcaprolactone and 3,3‘,5-trimethylcaprolactone are characterized with various spectroscopic methods. Their ability of ring-opening is correlated with semiempirical calculations and is compared to unsubstituted lactones of different ring sizes. The results of the computations are verified by measurements of reaction kinetics of the polymerizations. [ABSTRACT FROM AUTHOR]

Sedum plumbizincicola is a cadmium (Cd) and zinc hyperaccumulator that can activate Cd by rhizosphere acidification. However, there is little understanding of the Cd leaching risk from polluted soil during phytoextraction process. Here, pot and column experiments were conducted to monitor soil Cd leaching characteristics under different rainfall simulation conditions during S. plumbizincicola phytoextraction. Soil Cd leaching increased significantly with increasing simulated rainfall intensity. Compared with normal rainfall (NR), weak rainfall (WR) resulted in a 34.3% decrease in Cd uptake by S. plumbizincicola and also led to a 68.7% decline in Cd leaching. In contrast, Cd leaching under heavy rainfall (HR) was 2.12 times that of NR in the presence of S. plumbizincicola. After two successive growing periods, phytoextraction resulted in a 53.5-66.4% decline in the amount of soil Cd leached compared with controls in which S. plumbizincicola was absent. Even compared with maize cropping as a control, S. plumbizincicola did not instigate a significant increase in Cd leaching. The contribution of Cd leaching loss to the decline in soil total Cd concentration was negligible after phytoextraction in the pot experiment. Overall, the results contribute to our understanding of soil Cd leaching risk by phytoextraction with S. plumbizincicola. [ABSTRACT FROM AUTHOR]

Physiologically aged lungs are prone to senescence-associated pulmonary diseases (SAPD). This study aimed to determine the mechanism and subtype of aged T cells affecting alveolar type II epithelial (AT2) cells, which promote the pathogenesis of senescence-associated pulmonary fibrosis (SAPF). Cell proportions, the relationship between SAPD and T cells, and the aging- and senescence-associated secretory phenotype (SASP) of T cells between young and aged mice were analyzed using lung single-cell transcriptomics. SAPD was monitored by markers of AT2 cells and found to be induced by T cells. Furthermore, IFNγ signaling pathways were activated and cell senescence, SASP, and T cell activation were shown in aged lungs. Physiological aging led to pulmonary dysfunction and TGF-ß1/IL-11/MEK/ERK (TIME) signaling-mediated SAPF, which was induced by senescence and SASP of aged T cells. Especially, IFNγ was produced by the accumulated CD4+ effector memory T (TEM) cells in the aged lung. This study also found that physiological aging increased pulmonary CD4+ TEM cells, IFNγ was produced mainly by CD4+ TEM cells, and pulmonary cells had increased responsiveness to IFNγ signaling. Specific regulon activity was increased in T cell subclusters. IFNγ transcriptionally regulated by IRF1 in CD4+ TEM cells promoted the epithelial-to-mesenchymal transition by activating TIME signaling and cell senescence of AT2 cells with aging. Accumulated IRF1+CD4+ TEM produced IFNγ in lung with aging and anti-IRF1 primary antibody treatment inhibited the expression of IFNγ. Aging might drive T cell differentiation toward helper T cells with developmental trajectories and enhance cell interactions of pulmonary T cells with other surrounding cells. Thus, IFNγ transcribed by IRF1 in CD4+ effector memory T cells promotes SAPF. IFNγ produced by CD4+ TEM cells in physiologically aged lungs could be a therapeutic target for preventing SAPF. [ABSTRACT FROM AUTHOR]

Cleavage and polyadenylation specificity factor (CPSF) is a protein complex that plays an essential biochemical role in mRNA 3′-end formation, including poly(A) signal recognition and cleavage at the poly(A) site. However, its biological functions at the organismal level are mostly unknown in multicellular eukaryotes. The study of plant CPSF73 has been hampered by the lethality of Arabidopsis (Arabidopsis thaliana) homozygous mutants of AtCPSF73-I and AtCPSF73-II. Here, we used poly(A) tag sequencing to investigate the roles of AtCPSF73-I and AtCPSF73-II in Arabidopsis treated with AN3661, an antimalarial drug with specificity for parasite CPSF73 that is homologous to plant CPSF73. Direct seed germination on an AN3661-containing medium was lethal; however, 7-d-old seedlings treated with AN3661 survived. AN3661 targeted AtCPSF73-I and AtCPSF73-II, inhibiting growth through coordinating gene expression and poly(A) site choice. Functional enrichment analysis revealed that the accumulation of ethylene and auxin jointly inhibited primary root growth. AN3661 affected poly(A) signal recognition, resulted in lower U-rich signal usage, caused transcriptional readthrough, and increased the distal poly(A) site usage. Many microRNA targets were found in the 3′ untranslated region lengthened transcripts; these miRNAs may indirectly regulate the expression of these targets. Overall, this work demonstrates that AtCPSF73 plays important part in co-transcriptional regulation, affecting growth, and development in Arabidopsis. [ABSTRACT FROM AUTHOR]

RNA N6-methyladenosine (m6A) modification is involved in diverse biological processes. However, its role in spinal cord injury (SCI) is poorly understood. The m6A level increases in injured spinal cord, and METTL3, which is the core subunit of methyltransferase complex, is upregulated in reactive astrocytes and further stabilized by the USP1/UAF1 complex after SCI. The USP1/UAF1 complex specifically binds to and subsequently removes K48-linked ubiquitination of the METTL3 protein to maintain its stability after SCI. Moreover, conditional knockout of astrocytic METTL3 in both sexes of mice significantly suppressed reactive astrogliosis after SCI, thus resulting in widespread infiltration of inflammatory cells, aggravated neuronal loss, hampered axonal regeneration, and impaired functional recovery. Mechanistically, the YAP1 transcript was identified as a potential target of METTL3 in astrocytes. METTL3 could selectively methylate the 3′-UTR region of the YAP1 transcript, which subsequently maintains its stability in an IGF2BP2-dependent manner. In vivo, YAP1 overexpression by adeno-associated virus injection remarkably contributed to reactive astrogliosis and partly reversed the detrimental effects of METTL3 knockout on functional recovery after SCI. Furthermore, we found that the methyltransferase activity of METTL3 plays an essential role in reactive astrogliosis and motor repair, whereas METTL3 mutant without methyltransferase function failed to promote functional recovery after SCI. Our study reveals the previously unreported role of METTL3-mediated m6A modification in SCI and might provide a potential therapy for SCI. [ABSTRACT FROM AUTHOR]

Cracks in rock mass have always posed a big threat on the durability of fractured rocks in shear zone. Cracking of rock mass in shear zone is a random process, highly variable and influenced by many factors. Cracks in fractured rocks can be repaired by injection of epoxy resin in order to bond the crack and restore its structural integrity. Epoxy resins are used to repairing the shear zone at the Jinping Hydropower Station. An improved polymer grouting material is adopted and the polymerization process is determined. The polymer grouting materials is consisted of resin (component A) and hardener (component B). Polarizing microscopy (PM) tests and mechanical experiments are adopted to evaluate the filling situation of epoxy resin in rock and the mechanical properties of epoxy-repaired rock, respectively. Experimental test results show that, the cracks and pores are filled by epoxy resin, and also the crack surface are boned. The mechanical properties of epoxy-repaired rock are improved by the polymer grouting and the permeability coefficient is decreased. [ABSTRACT FROM AUTHOR]