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Bone marrow stem cells (BMSCs) are a promising source of seed cells in bone tissue engineering, which needs a great quantity of cells. Cell senescence occurs as they are passaged, which could affect the therapeutic effects of cells. Therefore, this study aims to explore the transcriptomic differences among the uncultured and passaged cells, finding a practical target gene for anti-aging. We sorted PαS (PDGFR-α+SCA-1+CD45-TER119-) cells as BMSCs by flow cytometry analysis. The changes in cellular senescence phenotype (Counting Kit-8 (CCK-8) assay, reactive oxygen species (ROS) test, senescence-associated β-galactosidase (SA-β-Gal) activity staining, expression of aging-related genes, telomere-related changes and in vivo differentiation potential) and associated transcriptional alterations during three important cell culture processes (in vivo, first adherence in vitro, first passage, and serial passage in vitro) were studied. Overexpression plasmids of potential target genes were made and examed. Gelatin methacryloyl (GelMA) was applied to explore the anti-aging effects combined with the target gene. Aging-related genes and ROS levels increased, telomerase activity and average telomere length decreased, and SA-β-Gal activities increased as cells were passaged. RNA-seq offered that imprinted zinc-finger gene 1 (Zim1) played a critical role in anti-aging during cell culture. Further, Zim1 combined with GelMA reduced the expression of P16/P53 and ROS levels with doubled telomerase activities. Few SA-β-Gal positive cells were found in the above state. These effects are achieved at least by the activation of Wnt/β-catenin signaling through the regulation of Wnt2. The combined application of Zim1 and hydrogel could inhibit the senescence of BMSCs during in vitro expansion, which may benefit clinical application.

The magnetic-field effect of the laser pulse is investigated in laser-assisted XUV ionization. By numerically solving the three-dimensional time-dependent Schr\"odinger equation, we find that the photoelectron momentum distribution is distorted by the magnetic-field effect of the IR streaking field. It results in a transverse-momentum- and time-delay-dependent longitudinal photoelectron momentum shift, which is further analytically confirmed by employing the nondipole corrected strong field approximation. We also demonstrate that the magnetic field does not affect the time shift retrieved from the streaking spectrum, although the streaking spectrum is apparently altered by the momentum shift induced by the magnetic-field effect. Our work reveals the time-resolved nondipole effect of the laser pulse by the attosecond streaking technique.

We theoretically demonstrate the quenching effect in below-threshold high harmonic generation (HHG) by using the time-dependent density-functional theory (TDDFT) and solving the time-dependent Schr\"{o}dinger equation (TDSE). It is shown that the HHG is substantially suppressed in particular harmonic orders in the below-threshold region when multi-electron interaction comes into play. The position of the suppression is determined by the energy gap between the highest occupied orbital and the higher-lying orbital of the target. We show that the quenching effect is due to a new class of multi-electron dynamics involving electron-electron energy transfer, which is analog to the fluorescence quenching owing to the energy transfer between molecules in fluorescent material. This work reveals the important role of the multi-electron interaction on HHG especially in the below-threshold region., Comment: 5 figures

Electromagnetic technologies, such as electromagnetic brake and electromagnetic stirring, are two efficient technologies to control the flow field in slab continuous casting mould. However, up to now there is still an important open problem to be answered firstly. It is that what kind of flow structure is our best choice to get good casting products when we use electromagnetic technologies ? We establish an physical model and an numerical model to study the flow field in slab continuous casting mold with electromagnetic stirring. During our physical experiments, we use liquid mercury as the analogue of liquid steel. In this study, we study the flow field under different casting parameters and stirring currents, respectively. At last, in order to evaluate the flow field in the mold, we propose two parameters. They are Mould Flux Entrapment Index and Velocity Uniform Index.Two parameters, named , are proposed in order to . Based on these two indexes, some optimized stirring parameters are proposed under different casting situations. These kinds of parameters are some reasonable criterions in order to find the optimized casting parameters when we use Electromagnetic flow control technologies.

In order to clarify the characteristics of a molten steel flow with or without the electromagnetic stirring under SEN clogging condition, a physical modeling system, which uses liquid mercury as the analog to simulate the flow of liquid steel in the continuous casting mold, has been developed. The liquid mercury velocity is measured by Ultrasonic Doppler velocity meter. The experiment results show that the SEN clogging will destroy the asymmetric of the flow in the mold and the uniform of the velocity in front of the initial solidifying shell. They will result in some products quality questions in the following process. The electromagnetic stirring is helpful to modify the flow field in the mold because the symmetry of the flow field can be optimized. If EMS current increases, the flow field will become more asymmetric and uniform.

We investigated electron emissions in strong field enhanced ionization of asymmetric diatomic molecules by quantum calculations. It is demonstrated that the widely-used intuitive physical pic- ture, i.e., electron wave packet direct ionization from the up-field site (DIU), is incomplete. Besides DIU, we find another two new ionization channels, the field-induced excitation with subsequent ionization from the down-field site (ESID), and the up-field site (ESIU). The contributions from these channels depend on the molecular asymmetry and internuclear distance. Our work provides a more comprehensive physical picture for the long-standing issue about enhanced ionization of diatomic molecules.

This is a Reply on the proceeding comment on our paper titled "Classical Simulations Including Electron Correlations for Sequential Double Ionization".

The role of nucleus in strong-field nonsequential double ionization of Ar atoms is investigated using three-dimensional classical ensembles. By adjusting the nuclear Coulomb potential, we can excellently reproduce the experimental correlated electron and ion momentum spectra with laser intensities above the recollision threshold [Phys. Rev. Lett. 93, 263001 (2004)] and below the recollision threshold [Phys. Rev. Lett. 101, 053001 (2008)] quantitatively. Analysis reveals the detailed electronic dynamics when the nuclear Coulomb attraction plays a key role in the recollision process of nonsequential double ionization of Ar atoms. Comparison between our results for Ar and those for He shows that atom species have a strong influence on nonsequential double ionization., 10 pages, 5 figures