Background Breast cancer (BRCA) is one of the most common cancers worldwide. Abnormal alternative splicing (AS) frequently observed in cancers. This study aims to demonstrate AS events and signatures ...that might serve as prognostic indicators for BRCA. Methods Original data for all seven types of splice events were obtained from TCGA SpliceSeq database. RNA-seq and clinical data of BRCA cohorts were downloaded from TCGA database. Survival-associated AS events in BRCA were analyzed by univariate COX proportional hazards regression model. Prognostic signatures were constructed for prognosis prediction in patients with BRCA based on survival-associated AS events. Pearson correlation analysis was performed to measure the correlation between the expression of splicing factors (SFs) and the percent spliced in (PSI) values of AS events. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were conducted to demonstrate pathways in which survival-associated AS event is enriched. Results A total of 45,421 AS events in 21,232 genes were identified. Among them, 1121 AS events in 931 genes significantly correlated with survival for BRCA. The established AS prognostic signatures of seven types could accurately predict BRCA prognosis. The comprehensive AS signature could serve as independent prognostic factor for BRCA. A SF-AS regulatory network was therefore established based on the correlation between the expression levels of SFs and PSI values of AS events. Conclusions This study revealed survival-associated AS events and signatures that may help predict the survival outcomes of patients with BRCA. Additionally, the constructed SF-AS networks in BRCA can reveal the underlying regulatory mechanisms in BRCA. Keywords: Alternative splicing, Breast cancer, The Cancer genome atlas, Prognosis
Large-scale brain activity mapping is important for understanding the neural basis of behaviour. Electrocorticograms (ECoGs) have high spatiotemporal resolution, bandwidth, and signal quality. ...However, the invasiveness and surgical risks of electrode array implantation limit its application scope. We developed an ultrathin, flexible shape-changing electrode array (SCEA) for large-scale ECoG mapping with minimal invasiveness. SCEAs were inserted into cortical surfaces in compressed states through small openings in the skull or dura and fully expanded to cover large cortical areas. MRI and histological studies on rats proved the minimal invasiveness of the implantation process and the high chronic biocompatibility of the SCEAs. High-quality micro-ECoG activities mapped with SCEAs from male rodent brains during seizures and canine brains during the emergence period revealed the spatiotemporal organization of different brain states with resolution and bandwidth that cannot be achieved using existing noninvasive techniques. The biocompatibility and ability to map large-scale physiological and pathological cortical activities with high spatiotemporal resolution, bandwidth, and signal quality in a minimally invasive manner offer SCEAs as a superior tool for applications ranging from fundamental brain research to brain-machine interfaces.
This work aims to understand the microstructural change mechanism of high-density polyethylene (HDPE) exposed at five national standard natural exposure stations (at Qionghai, Ruoqiang, Lhasa, ...Qingdao, and Hailar) for four years, which represented the five typical climates over China. It was found that the natural weathering of HDPE was the synergistic result of multi-factors such as temperature, irradiation, oxygen, etc. Based on the carbonyl index, the degradation degree in decreasing order was Ruoqiang, Qionghai, Lhasa, Qingdao and Hailar, but the microstructural change mechanism of HDPE was similar. The molecular structure was modified and mass molecular defects formed such as carbonyl and hydrogen groups during the degradation. The new freed molecular chains released from the amorphous region self-nucleated, and then formed new imperfect crystals because of the suppression of molecular defects. With the deposition of molecular defects, the chemi-crystallization ceased. Positron annihilation lifetime spectroscopy indicated the free volume hole shrank continually with exposure time mainly due to the interaction between molecular defects, and a part of amorphous region transformed into crystalline region by chemi-crystallization. In addition, the crystallization and re-melting behavior of degraded HDPE samples had been investigated in order to promote the recycling of waste degraded polymer materials. The results indicated that the crystalline temperature and the second melting temperature decreased with exposure time.
The hierarchical microstructure evolution of polypropylene during creep was explored via various methods, such as differential scanning calorimetry (DSC), scanning electron microscope (SEM), ...two-dimensional small-angle X-ray scattering (2D-SAXS), two-dimensional wide angle X-ray diffraction (2D-WAXD) and positron annihilation lifetime spectroscopy (PALS). The results revealed a correlation among the changes of micron-scale spherulites, nano-scale lamellae, crystalline blocks, atomic scale free volume and the deformation of polypropylene during creep. The elongation of micron-scale spherulites along the creep direction, accompanying with the increase of nano-scale lamellar long spacing, as well as the enlargement and amalgamation of atomic scale free volume were observed at ε below 17%; the imperfect fibrillar crystallites with polymer chains preferentially oriented along the creep direction, formed in the stress-induced crystalline block disaggregation–recrystallization process, were proved by SEM and 2D-SAXS results when ε was between 17% and 55%; the further orientation of polypropylene chains led to a higher degree of orientation and crystallinity. The molecular deformation mechanism of polypropylene during creep included three stages: the intralamellar slipping of crystalline blocks, accompanying with the enlargement and amalgamation of free volume, was activated at small strain (ε ≤ 17%); whereas the stress-induced crystalline block disaggregation–recrystallization process as well as the rearrangement and orientation of chains were proceeded at medium strain (17% < ε ≤ 55%); at last, orientation-induced crystallization occurred at larger strain (ε > 55%).
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•The molecular deformation mechanism of polypropylene during creep including three stages is proposed.•The mechanism explains the transition point during creep deformation.•Positron annihilation lifetime spectroscopy is a powerful microanalytical technique to explore the microstructure changes.•The disaggregation–recrystallization process would lead the free volume to increase in number while decrease in size.
An important background to the liquid argon detectors is that they are caused by the diffusion of radioactive isotopes in a scintillator (liquid phase). This radioactive isotope is produced in ...argon’s surrounding devices, such as circulation pipelines and liquid argon containers. The solid argon as a scintillation material in the detector can inhibit the diffusion and drift of radioactive isotopes in a solid phase scintillator. Additionally, the structure of a solid argon detector is simple and reduces the total source of radioactive background. In the CDEX-300 detection system, solid argon could substitute for liquid argon as the veto detector, preventing radioactive isotopes drifting to the central main detector (HPGe detectors array) surface to reduce backgrounds. Therefore, solid argon has great potential in the experiments since it is especially helpful to get the lower background in a larger active volume than liquid argon required in those low background detection experiments. This work introduces the preparation process and device of the large volume transparent crystalline argon, the acquisition of scintillation light, and the pulse amplitude spectrum of 137Cs obtained from a prototype detector of transparent solid argon crystal. The results show that the scheme proposed in this study can successfully produce a large volume transparent crystalline argon detector, the scintillation light signals can be effectively obtained from the solid argon scintillator, and the corresponding pulse amplitude spectrum is given. This work indicates that it is feasible to develop a solid argon crystal scintillation detector by using our approach.
The data presented in this paper are related to the research paper entitled “Bremsstrahlung spectra produced by kilovolt electron impact on thick targets” 1. The dataset includes our measured ...bremsstrahlung spectra on Al, Ti, Zr, Mo, and W thick targets at 5, 10, 15, 20, and 25 keV electron impact. In this paper we present the experimental method and make the dataset publicly available to enable extended analyses or reuse. The dataset is available on mendeley data public repository at http://dx.doi.org/10.17632/5zx3459bj3.1
•Absolute measurement of bremsstrahlung spectra for conductive compounds is made.•Monte Carlo simulations and measured spectra are in good agreement.•Additivity approximation in Monte Carlo ...simulations is feasible.•Previous disagreement for insulating samples does not appear.
Absolute measurements were conducted to obtain the bremsstrahlung spectra from ∼5–25 keV electrons incident on three thick solid conductive compounds of MoSi2, TiB2 and ZrB2. The additivity approximation was applied in the Monte Carlo PENELOPE simulations for compounds and mixtures. The results in this paper showed that in general the experimental bremsstrahlung spectra were in good agreement with the PENELOPE simulation results, suggesting the feasibility of the additivity approximation used in Monte Carlo simulations for the studied cases even in the absolute measurements, and the significant differences between experiments and Monte Carlo simulations near the Duane-Hunt limit for insulating targets in previous studies do not appear in the present studies.
•The bremsstrahlung DDCSs are measured at 90° with 5–25 keV electrons for C and Al.•The bremsstrahlung photons are measured down to 1–2 keV.•The measured DDCSs are compared with OB and SA ...theories.•It is found that the discrepancies between the measured data and the theories exist.
Absolute measurements of the bremsstrahlung double differential cross sections (DDCSs) for photons radiated at 90° generated by the collisions of 5–25 keV electrons and down to 1–2 keV photon energy with two thin targets C (Z = 6) and Al (Z = 13) are presented. A parallelized version of the PENELOPE Monte Carlo program has been used to correct the effects of electron multiple scattering and the backscattering from the target substrate on the experimental results. Comparisons between the experiments and the theories reveal some discrepancies between the measured data and the theoretical bremsstrahlung predictions.
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