Leaf anatomical traits play key roles in plant functions and display evolutionary adaptive changes to suit the surrounding environment. To reveal the adaptive mode and mechanisms of plants in ...response to global warming, we analyzed leaf morphology and anatomical structures in three different species, Epilobium amurense Hausskn., Pedicularis densispica Franch., and Potentilla fulgens Wall. ex Hook., growing along an elevational gradient (3,000–4,600 m) in the Yulong Mountains. The results showed leaf length and width decreased, whereas leaf thickness increased with increasing altitude in all three species. Thickness of leaf upper epidermis, lower epidermis, palisade and spongy mesophyll, and main vein increased with rising altitude. Stomatal density in each species increased with rising elevation. These results illustrate that plants can adapt to the environmental changes that accompany high altitudes by decreasing leaf area and increasing leaf thickness, mesophyll tissue thickness, and stomatal density. Such morphological and anatomical plasticity would lead to lower transpiration rates, enhanced internal temperature and water status, and improved photosynthetic capability.
With increasing altitude, leaf length and width decreased in all three species, whereas leaf thickness increased. Stomatal density in each species also increased with increasing altitude; however, both stoma length and width decreased. Thickness of the leaf upper epidermis, lower epidermis, palisade and spongy mesophyll, and midrib increased with increasing altitude.
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•The T85 treated Al-Cu-Li alloy was systematically investigated under thermal exposure at 100–300 °C for up to 1000 h.•The evolution of precipitation characteristics during thermal ...exposure was revealed.•Fracture toughness was greatly affected by the morphology and distribution of grain boundary precipitates.•The qualitative relationship between mechanical properties and multiscale microstructure was established.
In this study, the T85-treated Al-3.78Cu-1.17Li-0.7 Mg-0.32Ag-0.25Mn-0.33Zn-0.12Zr alloy thermally exposed at a series of temperatures (100–300 °C) for 100 h, 500 h, and 1000 h was systematically investigated. The results show that the thermal stability of the alloy is more closely correlated with thermal exposure temperature than with exposure duration. Excellent thermal stability in strength is obtained below 150 °C, which can be linked to the diameter and number density of T1 (Al2CuLi) precipitates continually increasing with a thickness less than 2 nm. However, the widened precipitation-free zones (PFZs) associated with continuous grain boundary precipitates (GBPs) benefit intergranular fracture, contributing to a decrease in toughness and elongation. In the window of 175–200 °C, T1 precipitates tend to thicken and are gradually substituted by coarse θ′-Al2Cu and S-Al2CuMg with elevating temperature. Simultaneously, the continuous GBPs transverse to discrete circle-like shapes, and thus intergranular ductile fracture becomes dominant. Therefore, the related hardness and strength decrease, while the electrical conductivity and toughness are the opposite. At temperatures over 250 °C, thermal exposure can reduce the dislocation density and dissolve T1 phases to form T2-Al6Cu(Li, Mg)3 and cubic C phases, leading to a dramatic decrease in strength and toughness.
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•Major nano precipitates and composite precipitates in Al-Li alloys, are surveyed from atomic structure, orientation relationship with matrix and evolution.•Precipitate-dislocation ...interaction mechanisms of different precipitates in Al-Li alloys are summarized, and the possible main strengthening mechanisms are discussed.•Issues that have hindered the development of nano precipitates in Al-Li alloys and corresponding research directions are proposed.
Application aspects in aerospace have led to extensive explores and researches on the Al-Li alloys. Advance of alloy properties and balance of comprehensive performances depend largely on regulation of nano precipitates. However, introduction of further solute elements in Al-Li alloys leads to a greater complexity of precipitation behavior of nano second phase. A pivotal step in understanding the strengthening mechanism is to determine the crystal structure and the evolution pattern of nano precipitate. In this critical review, several major nano precipitates and precursors, as well as composite nano precipitates in Al-Li alloys, are surveyed from composition, atomic structure and orientation relationship with matrix. Nucleation mechanism and evolution process are then discussed. Based on a proper understanding of crystallography, great details are provided on precipitate-dislocation interactions by analyzing the interfacial structure between precipitate and matrix. Finally, the review offers a summary of advances in this field and some inspirations for future research directions.
Nonalcoholic steatohepatitis (NASH) is a serious liver disease associated with obesity. Characterized by metabolic syndrome, hepatic steatosis, and liver inflammation, NASH is believed to be under ...the influence of the gut microflora. Here, the composition of gut bacterial communities of NASH, obese, and healthy children was determined by 16S ribosomal RNA pyrosequencing. In addition, peripheral blood ethanol was analyzed to monitor endogenous ethanol production of patients and healthy controls. UniFrac‐based principle coordinates analysis indicated that most of the microbiome samples clustered by disease status. Each group was associated with a unique pattern of enterotypes. Differences were abundant at phylum, family, and genus levels between healthy subjects and obese patients (with or without NASH), and relatively fewer differences were observed between obese and the NASH microbiomes. Among those taxa with greater than 1% representation in any of the disease groups, Proteobacteria, Enterobacteriaceae, and Escherichia were the only phylum, family and genus types exhibiting significant difference between obese and NASH microbiomes. Similar blood‐ethanol concentrations were observed between healthy subjects and obese non‐NASH patients, but NASH patients exhibited significantly elevated blood ethanol levels. Conclusions: The increased abundance of alcohol‐producing bacteria in NASH microbiomes, elevated blood‐ethanol concentration in NASH patients, and the well‐established role of alcohol metabolism in oxidative stress and, consequently, liver inflammation suggest a role for alcohol‐producing microbiota in the pathogenesis of NASH. We postulate that the distinct composition of the gut microbiome among NASH, obese, and healthy controls could offer a target for intervention or a marker for disease. (HEPATOLOGY 2013)
•Mg1 and 1060Al were successfully joined by vacuum diffusion bonding.•Microstructure and phase structures evolutions revealed the forming process of bonded joints.•Growth kinetic equations of the ...IMCs were developed and verified by experiments.•Interdiffusion coefficients of Mg were calculated for each phase.
Mg/Al was bonded successfully via vacuum diffusion bonding in this paper. Microstructure evolution, the growth kinetic of IMCs, diffusion behaviors and mechanical properties were investigated, and their relations were discussed. The results indicate that, the multi-layer diffusion couple at the joint consisted of Al-based solid solution (α), Al3Mg2 layer (β), Al12Mg17 layer (γ), and Mg-based solid solution (δ). In addition, Mg/Al vacuum diffusion bonding was a diffusion-controlled process. Growth kinetic equations of the intermetallic phases were developed and the calculation results were in good agreement with the experimental data. The different interdiffusion coefficients calculated could characterize the nature of the differences in growth-rate. Microhardness was measured by the nanoindentation hardness tester. The result showed that the microhardness of the transition layer was higher than those of Al and Mg base metals due to intermetallic phases. Mechanical properties of the bonded joints were investigated by shear strength, the graphs of shear fracture showed a brittle fracture which occurred at the joint interface.
Pathogenesis of nonalcoholic steatohepatitis Liu, Wensheng; Baker, Robert D.; Bhatia, Tavleen ...
Cellular and molecular life sciences : CMLS,
05/2016, Volume:
73, Issue:
10
Journal Article
Peer reviewed
Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease and a risk factor for cirrhosis and hepatocellular carcinoma. The pathological features of NASH include ...steatosis, hepatocyte injury, inflammation, and various degrees of fibrosis. Steatosis reflects disordered lipid metabolism. Insulin resistance and excessive fatty acid influx to the liver are two important contributing factors. Steatosis is also likely associated with lipotoxicity and cellular stresses such as oxidative stress and endoplasmic reticulum stress, which result in hepatocyte injury. Inflammation and fibrosis are frequently triggered by various signals such as proinflammatory cytokines and chemokines, released by injuried hepatocytes and activated Kupffer cells. Although much progress has been made, the pathogenesis of NASH is not fully elucidated. The purpose of this review is to discuss the current understanding of NASH pathogenesis, mainly focusing on factors contributing to steatosis, hepatocyte injury, inflammation, and fibrosis.
•Cr addition is beneficial for the formation of Laves phase in ZrTiNbMo HEA.•ZrTiNbMo HEA can be strengthened by Cr addition.•Excessive Cr addition is detrimental to ductility.•Cr2 HEA has the ...maximum compressive strength and retains high compressive strain.•Thermal stability and hydrogen desorption capacity decrease with Cr addition.
Phase constitution, mechanical properties and hydrogen desorption behaviors of the as-cast (ZrTiNbMo)100-xCrx (x = 0, 2, 5, 10, 15, 20) high entropy alloys (HEAs) have been investigated. ZrTiNbMo alloy has a body-centered cubic (BCC) single phase structure, and the Cr addition leads to the formation of Laves phase. The HEAs can be strengthened by Cr addition due to more formation of Laves phase and solution strengthening. Zr20Ti20Nb20Mo20Cr20 HEA shows the maximum Vickers hardness of 564 HV and maximum compressive yield strength of 1479 MPa, respectively. In contrary, the ductility can be retained when x = 2, but obviously decreases with further increasing Cr content. Thermal stability and hydrogen desorption capacity of the hydrogenated HEAs decreases with Cr addition, which may be mainly ascribed to the reduction of cell volume and much less stability of hydrogen atoms in solid solution with increasing Cr content.
FBW7 functions as a tumor suppressor by targeting oncoproteins for degradation. Our previous study found FBW7 was low expressed in pancreatic cancer due to sustained activation of Ras-Raf-MEK-ERK ...pathway, which destabilized FBW7 by phosphorylating at Thr205. MicroPET/CT imaging results revealed that FBW7 substantially decreased 18F-fluorodeoxyglucose uptake in xenograft tumors. Mechanistically, FBW7 inhibited glucose metabolism via c-Myc/TXNIP axis. But in these studies, we observed FBW7 down-regulated genes were widely involved in redox reaction and lipid metabolism. Here we reanalyzed previous gene expression profiling and conducted targeted cell metabolites analysis. Results revealed that FBW7 regulated lipid peroxidation and promoted ferroptosis, a non-apoptotic form of cell death. Mechanistically, we found FBW7 inhibited the expression of stearoyl-CoA desaturase (SCD1) via inhibiting nuclear receptor subfamily 4 group A member 1 (NR4A1). SCD1 was reported to inhibit both ferroptosis and apoptosis, which was consistent with the function of FBW7 and NR4A1, another FBW7 down-regulated gene in the gene expression profiling. Moreover, FBW7 potentiated cytotoxic effect of gemcitabine via activating ferroptosis and apoptosis. Combination ferroptosis inducers and apoptosis activators could also significantly potentiated cytotoxic effect of gemcitabine in pancreatic cancer. Therefore, our findings might provide new strategies for the comprehensive treatment of pancreatic cancer.
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•Ferroptosis possesses great potential in pancreatic cancer therapy.•FBW7 synchronously induces apoptosis and ferroptosis.•Activation of apoptosis and ferroptosis potentiates cytotoxic effect of gemcitabine.
2A14 aluminum alloy was subjected to multidirectional forging (MDF) with a constant strain rate at 350°C, to different cumulative strain. The effects of cumulative strain on microstructure and ...mechanical properties of 2A14 aluminum alloy were investigated. The inhomogeneity of deformation during MDF was improved and grains of the alloy were gradually refined by increasing cumulative strain, while dislocation density first increased and then decreased with increasing cumulative strain in the range 0.4–7.2. After subsequent T6 aging, fine and equiaxed recrystallization grains with large-angle grain boundaries were more easily formed at relatively higher cumulative strain, and the optimized mechanical properties were achieved when cumulative strain was up to 3.6, with ultimate tensile strength of 505MPa, yield strength of 435MPa, Vickers hardness of 178Hv and elongation of 16.8% at room temperature. The improvement in mechanical properties of the alloy was attributed to the presence of fine recrystallized grains which are uniformly distributed and high dislocation density, as well as precipitation strengthening.
UHRF1 (ubiquitin like with plant homeodomain and ring finger domains 1) is an epigenetic modifier that is overexpressed in some cancers, including pancreatic cancer, and mediates silencing of tumor ...suppressor genes. However, the role of UHRF1 in regulating pancreatic cancer metabolism and metastasis is not clear. In the present study, we demonstrated that silencing UHRF1 significantly inhibited aerobic glycolysis in pancreatic cancer cells. Furthermore, we demonstrated that UHRF1 knockdown decreased hypoxia inducible factor (HIF)1α levels and HIF1α targeted glycolytic genes. The Cancer Genome Atlas dataset analysis supported this observation. The Sirtuin (SIRT) family members regulate aerobic glycolysis in many cancers. We analyzed the correlation between UHRF1 and SIRT3–5 expression and found a significant negative correlation between UHRF1 and SIRT4. Further transcriptional and functional analysis demonstrates that SIRT4 is a downstream target of UHRF1 and negatively regulated aerobic glycolysis, cell proliferation and tumor growth. Our study identified a novel UHRF1/SIRT4 axis in regulation of pancreatic cancer cell proliferation, metabolism, and metastasis.
•UHRF1 predicts worse prognosis of pancreatic cancer.•UHRF1 regulates pancreatic cell proliferation and aerobic glycolysis.•UHRF1 suppresses SIRT4 expression.•SIRT4 is a tumour suppressor in pancreatic cancer.•SIRT4 negatively regulates aerobic glycolysis in pancreatic cancer.
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