The free thermal vibration of functionally graded material (FGM) cylindrical shells containing porosities is investigated. Both even distribution and uneven distribution are taken into account. In ...addition, three thermal load types, i.e., uniform temperature rise (UTR), nonlinear temperature rise (NLTR), and linear temperature rise (LTR), are researched to explore their effects on the vibration characteristics of porous FGM cylindrical shells. A modified power-law formulation is used to describe the material properties of FGM shells in the thickness direction. Love’s shell theory is used to formulate the strain-displacement equations, and the Rayleigh-Ritz method is utilized to calculate the natural frequencies of the system. The results show that the natural frequencies are affected by the porosity volume fraction, constituent volume fraction, and thermal load. Moreover, the natural frequencies obtained from the LTR have insignificant differences compared with those from the NLTR. Due to the calculation complexity of the NLTR, we propose that it is reasonable to replace it by its linear counterpart for the analysis of thin porous FGM cylindrical shells. The present results are verified in comparison with the published ones in the literature.
A comprehensive analysis of both the molecular genetic and phenotypic responses of any organism to the space flight environment has never been accomplished because of significant technological and ...logistical hurdles. Moreover, the effects of space flight on microbial pathogenicity and associated infectious disease risks have not been studied. The bacterial pathogen Salmonella typhimurium was grown aboard Space Shuttle mission STS-115 and compared with identical ground control cultures. Global microarray and proteomic analyses revealed that 167 transcripts and 73 proteins changed expression with the conserved RNA-binding protein Hfq identified as a likely global regulator involved in the response to this environment. Hfq involvement was confirmed with a ground-based microgravity culture model. Space flight samples exhibited enhanced virulence in a murine infection model and extracellular matrix accumulation consistent with a biofilm. Strategies to target Hfq and related regulators could potentially decrease infectious disease risks during space flight missions and provide novel therapeutic options on Earth.
The vibration of a longitudinally moving rectangular plate submersed in an infinite liquid domain is studied analytically with the Rayleigh-Ritz method. The liquid is assumed to be incompressible, ...inviscid, and irrotational, and the velocity potential is used to describe the fluid velocity in the whole liquid field. The classical thin plate theory is used to derive mechanical energies of the traveling plate. As derivative of transverse displacement with respect to time in the compatibility condition equation exists, an exponential function is introduced to depict the dynamic deformation of the moving plate. It is shown that this exponential function works well with the Rayleigh- Ritz method. A convergence study shows a quick convergence speed for the immersed moving plate. Furthermore, the parametric study is carried out to demonstrate the effect of system parameters including the moving speed, the plate location, the liquid depth, the plate-liquid ratio, and the boundary condition. Results show that the above system parameters have significant influence on the vibration characteristics of the immersed moving plate. To extend the study, the method of added virtual mass incremental (AVMI) factor is used. The results show good agreement with those from the Rayleigh-Ritz method.
The success of using 2D Ruddlesden‐Popper metal halide perovskites (MHPs) in optoelectronic devices has ignited great interest as means for energy level tuning at the interface with 3D MHPs. Inter ...alia, the application of 2D phenylethylammonium lead quaternary iodide (PEA2PbI4)/3D MHPs interfaces has improved various optoelectronic devices, where a staggered type‐II energy level alignment is often assumed. However, a type‐II heterojunction seems to contradict the enhanced photoluminescence observed for 2D PEA2PbI4/3D MHP interfaces, which raises fundamental questions about the electronic properties of such junctions. In this study, using direct and inverse photoelectron spectroscopy, it is revealed that a straddling type‐I energy level alignment is present at 2D PEA2PbI4/3D methylammonium lead triiodide (MAPbI3) interfaces, thus explaining that the photoluminescence enhancement of the 3D perovskite is induced by energy transfer from the 2D perovskite. These results provide a reliable fundamental understanding of the electronic properties at the investigated 2D/3D MHP interfaces and suggest careful (re)consideration of the electronic properties of other 2D/3D MHP heterostructures.
A straddling type‐I energy level alignment is found for 2D/3D interfaces of phenylethylammonium lead quaternary iodide and methylammonium lead triiodide, enabling efficient energy transfer from the 2D to the 3D component.
ZrC and TiC have been proposed to be alternatives to SiC as fuel-cladding and structural materials in nuclear reactors due to their strong radiation tolerance and high thermal conductivity at high ...temperatures. To unravel how the presence of defects affects the thermo-physical properties under irradiation, first-principles calculations based on density function theory were carried out to investigate the mechanical and thermal properties of defective ZrC, TiC and SiC. As compared with the defective SiC, the ZrC and TiC always exhibit larger bulk modulus, smaller changes in the Young's and shear moduli, as well as better ductility. The total thermal conductivity of ZrC and TiC are much larger than that of SiC, implying that under radiation environment the ZrC and TiC will exhibit superior heat conduction ability than the SiC. One disadvantage for ZrC and TiC is that their Debye temperatures are generally lower than that of SiC. These results suggest that further improving the Debye temperature of ZrC and TiC will be more beneficial for their applications as fuel-cladding and structural materials in nuclear reactors.
Human protein arginine N-methyltransferase 2 (PRMT2, HRMT1L1) is a protein that belongs to the arginine methyltransferase family, and it has diverse roles in transcriptional regulation through ...different mechanisms depending on its binding partners. In this study, we provide evidences for the negative effect of PRMT2 on breast cancer cell proliferation in vitro and in vivo. Morever, cyclin D1, one of the key modulators of cell cycle, was found to be downregulated by PRMT2, and PRMT2 was further shown to suppress the estrogen receptor α-binding affinity to the activator protein-1 (AP-1) site in cyclin D1 promoter through indirect binding with AP-1 site, resulting in the inhibition of cyclin D1 promoter activity in MCF-7 cells. Furthermore, a positive correlation between the expression of PRMT2 and cyclin D1 was confirmed in the breast cancer tissues by using tissue microarray assay. In addition, PRMT2 was found to show a high absent percentage in breast caner cell nuclei and the nuclear loss ratio of PRMT2 was demonstrated to positively correlate with cyclin D1 expression and the increasing tumor grade of invasive ductal carcinoma. Those results offer an essential insight into the effect of PRMT2 on breast carcinogenesis, and PRMT2 nuclear loss might be an important biological marker for the diagnosis of breast cancer.
Abstract
There is an increasing expectation on the private sector to address biodiversity impacts and contribute towards global conservation goals. Appropriate evidence use can help businesses avoid ...biodiversity losses and realise gains, reduce ineffective or suboptimal action, whilst minimising biodiversity‐related risks and securing opportunities from engaging with biodiversity.
We review the status of evidence‐based action in the private sector, where previous studies have identified concerning trends, and explore the barriers that may currently be hindering practice.
To learn from this, and improve the status quo, we propose a set of principles for evidence‐based biodiversity impact mitigation. We outline tools and resources that can help businesses move towards evidence‐based practice and achieve each of these principles.
Meeting these principles would improve the biodiversity outcomes from businesses' biodiversity related actions. However, for business action to contribute more fully to global conservation goals, broader political and socio‐economic issues also need addressing.
In this study, an ab initio molecular dynamics method is employed to study low energy recoil events in zirconate pyrochlores (A2Zr2O7, A=La, Nd and Sm). It shows that both cations and anions in ...Nd2Zr2O7 and Sm2Zr2O7 are generally more likely to be displaced than those in La2Zr2O7. The damage end states mainly consist of Frenkel pair defects, and the Frenkel pair formation energies in Nd2Zr2O7 and Sm2Zr2O7 are lower than those in La2Zr2O7. These results suggest that the order-disorder structural transition more easily occurs in Nd2Zr2O7 and Sm2Zr2O7 resulting in a defect-fluorite structure, which agrees well with experimental observations. Our calculations indicate that oxygen migration from 48f and 8b to 8a sites is dominant under low energy irradiation. A number of new defects, including four types of cation Frenkel pairs and six types of anion Frenkel pairs, are revealed by ab initio molecular dynamics simulations. The present results may help to advance the fundamental understanding of the irradiation response behavior of zirconate pyrochlores.
Geometrically nonlinear oscillations are investigated on sigmoid functionally graded material （S-FGM） plates with a longitudinal speed. The material properties of the plates obey a sigmoid ...distribution rule along the thickness direction. Based on the D＇Alembert＇s principle, a nonlinear equation of motion is derived for the moving S-FGM plates, where the von K~rm~n nonlinear plate theory is adopted. Utilizing the Galerkin method, the equation of motion is discretized and solved via the method of harmonic bal- ance. The approximate analytical solutions are validated through the adaptive step-size fourth-order Runge-Kutta method. Besides, the stability of the steady-state solutions is examined. The results reveal that the mode interaction behavior can happen between the first two modes of the moving S-FGM plates, leading to a complex nonlinear frequency response. It is further found that the power-law index, the longitudinal speed, the exci- tation amplitude, and the in-plane pretension force can significantly affect the nonlinear frequency-response characteristics of longitudinally traveling S-FGM plates.
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