Mechanism studies for relativistic attosecond electron bunches from laser-illuminated nanotargets.

To find a way to control the electron-bunching process and the bunch-emitting directions when an ultraintense, linearly polarized laser pulse interacts with a nanoscale target, we explored the mechanisms for the periodical generation of relativistic attosecond electron bunches. By comparing the simulation results of three different target geometries, the results show that for nanofoil target, limiting the transverse target size to a small value and increasing the longitudinal size to a certain extent is an effective way to improve the total electron quantity in a single bunch. Then the subfemtosecond electronic dynamics when an ultrashort ultraintense laser grazing propagates along a nanofoil target was analyzed through particle-in-cell simulations and semiclassical analyses, which shows the detailed dynamics of the electron acceleration, radiation, and bunching process in the laser field. The analyses also show that the charge separation field produced by the ions plays a key role in the generation of electron bunches, which can be used to control the quantity of the corresponding attosecond radiation bunches by adjusting the length of the nanofoil target.

LncRNA LINC00963 promotes proliferation and migration through the miR-124-3p/FZD4 pathway in colorectal cancer.

OBJECTIVE: Long noncoding RNAs (lncRNAs) have been identified in various malignant tumors and determined to play an essential role in terms of cancer progression. In this study, we aimed at exploring the molecular mechanism of LINC00963 in colorectal cancer (CRC). PATIENTS AND METHODS: The mRNA expressions of LINC00963, miR-124-3p and FZD4 in CRC tissues and cells were detected by qRT-PCR. CCK-8 and transwell assay were chosen to measure the CRC cell vitality. Western blot analysis was performed to assess the expression level of FZD4 in CRC. The correlation between LINC00963 and miR-124-3p or miR-124-3p and FZD4 was appraised by Dual-Luciferase reporter assay. RESULTS: In this study, LINC00963 was significantly upregulated in CRC tissues and cells. Functionally, LINC00963 knockdown inhibited cell progression in CRC. The results verified that LINC00963 can restrain the expression of miR-124-3p. Moreover, FZD4 restored the inhibitory effect of miR-124-3p on the progression of CRC cells. Besides that, we preliminarily verified that FZD4 was a direct target gene of LINC00963/miR-124-3p axis in CRC. CONCLUSIONS: Our study demonstrated that LINC00963/miR-124-3p/FZD4 played a curial role in cell proliferation and migration in CRC. In addition, LINC00963 can be a possible therapeutic and diagnostic target for CRC treatment.

Towards high-energy, high-resolution computed tomography via a laser driven micro-spot gamma-ray source.

Computed Tomography (CT) is a powerful method for non-destructive testing (NDT) and metrology awakes with expanding application fields. To improve the spatial resolution of high energy CT, a micro-spot gamma-ray source based on bremsstrahlung from a laser wakefield accelerator was developed. A high energy CT using the source was performed, which shows that the resolution of reconstruction can reach 100 µm at 10% contrast. Our proof-of-principle demonstration indicates that laser driven micro-spot gamma-ray sources provide a prospective way to increase the spatial resolution and toward to high energy micro CT. Due to the advantage in spatial resolution, laser based high energy CT represents a large potential for many NDT applications.

Enhancing expression of SSU1 genes in Saccharomyces uvarum leads to an increase in sulfite tolerance and a transcriptome profile change.

Saccharomyces uvarum is a good wine yeast species that may have great potential for the future. However, sulfur tolerance of most S. uvarum strains is very poor. In addition there is still little information about the SSU1 gene of S. uvarum, which encodes a putative transporter conferring sulfite tolerance. In order to analyze the function of the SSU1 gene, two expression vectors that contained different SSU1 genes were constructed and transferred into a sulfite-tolerant S. uvarum strain, A9. Then sulfite tolerance, SO2 production, and PCR, sequencing, RT-qPCR and transcriptome analyses were used to access the function of the S. uvarum SSU1 gene. Our results illustrated that enhancing expression of the SSU1 gene can promote sulfite resistance in S. uvarum, and an insertion fragment ahead of the additional SSU1 gene, as seen in some alleles, could affect the expression of other genes and the sulfite tolerance level of S. uvarum. This is the first report on enhancing the expression of the SSU1 gene of S. uvarum.

A novel approach to correct the coded aperture misalignment for fast neutron imaging.

Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, "residual watermark," certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used to determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 µm. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.

Obtaining point spread function of penumbral encoding aperture with "expectation maximization" algorithm based on matched source-image pair experiment.

A source penumbral image reconstruction method with linear mapping principle for geometrical optics is established. The ideal binary point spread function (PSF) can be obtained using a geometrical optics model. The system PSF with certain sharpness was obtained using a Monte Carlo (MC) model. Considering other factors besides the transportation of the x (gamma)-rays or particles (fusion neutrons) in the penumbral encoding aperture in MC model, such as the scattering background and the systematic error, the PSF from MC model "source-image pair matching" experiments with a large area standard oval shape source were processed. A method for correcting and calibrating the PSF by the expectation maximization adaptive algorithm was established and the optimized PSF with 22.30 microm sharpness was achieved. This is more consistent with the real system PSF despite the increased noise level of the two-dimensional PSF and large irregularity in the PSF profile.