Physical model test and numerical simulation on the failure mechanism of the roadway in layered soft rocks

To explore the failure mechanism of roadway in layered soft rocks,a physical model with the physically finite elemental slab assemblage(PFESA)method was established.Infrared thermography and a video camera were employed to capture thermal responses and deformation.The model results showed that layered soft roadway suffered from large deformation.A three-dimensional distinct element code(3 DEC)model with tetrahedral blocks was built to capture the characteristics of roadway deformation,stress,and cracks.The results showed two failure patterns,layer bending fracture and layer slipping after excavation.The layer bending fracture occurred at positions where the normal direction of layers pointed to the inside of the roadway and the layer slipping occurred in the ribs.Six schemes were proposed to investigate the effects of layered soft rocks.The results showed that the deformation of ribs was obviously larger than that of the roof and floor when the roadway passed through three types of strata.When the roadway was completely in a coal seam,the change of deformation in ribs was not obvious,while the deformation in the roof and floor increased obviously.These results can provide guidance for excavation and support design of roadways in layered soft rocks.

Effects of mid-passage gap with a variable surface angle on a turbine vane endwall’s aerothermal and film cooling performances

The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured individually.The coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall’s coverage area and reducing the endwall’s thermal load by applying the mid-passage gap with variable surface angles is carried out in this paper.The endwall’s aerothermal and film cooling performances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically investigated.Results indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can’t stick to the endwall.Thus,cooling failure occurs,and the endwall’s thermal load is badly increased.The film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45surface angle due to the secondary vortex being suppressed.In addition,when applying the mid-passage gap of a 135surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side endwall is enlarged significantly.The best film cooling performance is achieved when the upstream surface angle is 135and the downstream surface angle is 45due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side endwall.When the mass flow ratio is 1.5%,the coverage area is enlarged by 43%,and the area-averaged adiabatic film cooling effectiveness is increased by 37%,when compared with those under the traditional mid-passage mode.

A polarized^(3)He system based on metastability-exchange optical pumping

Hyperpolarized^(3)He nuclei have emerged as a significantly important approach in quantum precision measurement techniques,with extensive applications in fundamental physics,magnetometry,metrology,and beyond.In this study,we report on the design and implementation of a^(3)He polarization system at the China Mianyang Research Reactor(CMRR),utilizing the metastabilityexchange optical pumping(MEOP)method.We employed a Merritt coil system consisting of four square coils to furnish a uniform holding field.We deployed a 2 W fiber laser to pump the metastable^(3)He atoms and conducted free induction decay(FID)detection of the polarized^(3)He nuclei using both pickup coil and optical methods.For the optical method,we used a50 m W linearly polarized distributed Bragg reflector(DBR)laser as the probe.We applied transverse light absorption polarimetry to measure the absolute nuclear polarization of the ground-state^(3)He.We have developed cell fabrication capabilities at the CMRR,and cells at various pressures ranging from 100 to 1000 Pa have been fabricated and evaluated.For a typical borosilicate cell with 100 Pa pressure,the absolute polarization is measured as Pn≈70%,and the transverse relaxation time is estimated as T2≈0.5 s.Moreover,we constructed a few aluminosilicate cells,each carefully filled with pure^(3)He at a pressure of 100 Pa.Subsequently,we conducted a comprehensive evaluation of their performance in the context of MEOP.

氮掺杂Ti_(3)C_(2)T_(x)MXene纳米片包覆的SiO_(x)实现储锂性能提升

构建具有快速反应动力学和优异循环稳定性的SiO_(x)基负极材料是获取高性能锂离子电池的关键和挑战.本文中,我们利用三聚氰胺辅助的球磨和退火方法,合成了氮掺杂的Ti_(3)C_(2)T_(x)MXene超薄片层(NTS)包覆的SiO_(x)复合材料.通过对比实验和理论计算,我们论证了三聚氰胺剥离MXene的作用机理.SiO_(x)与NTS之间强烈的界面相互作用(Si-O-Ti键)可以有效地增强电子转移,确保电极的稳定性.此外,具有丰富表面基团的NTS使复合材料具有赝电容性能,有利于快速储锂.因此,该复合材料展现出了长循环寿命(在1.0 A g^(-1)的电流密度下,循环800次后比容量保持为~700 mA h g^(-1))和优越的倍率性能(在5 A g^(-1)的电流密度下,比容量为596.4 mA h g^(-1)).更重要的是,在高负载量下,该复合材料在半电池和全电池中均表现出较高的面积比容量和良好的循环稳定性,展现出了良好的应用潜力.

基于形变相对论连续谱Hartree-Bogoliubov理论构建高精度原子核质量表

质量是原子核最基本的物理量之一,是理解核子间相互作用、揭示壳结构演化和确定滴线位置的关键,是研究核反应和核衰变的基本信息,同时也是探索元素起源等问题必需的核物理输入量,对粒子物理与核物理、天体物理和宇宙学等学科至关重要.尽管短寿命原子核质量的测量工作已经取得很大进展,但是在可预见的将来,大部分远离稳定谷的奇特原子核质量仍依赖理论模型预言和计算.本文介绍了原子核质量模型的重要发展历程、相对论密度泛函理论描述原子核现象的成功、基于相对论连续谱Hartree-Bogoliubov理论构建的目前唯一考虑连续谱效应的原子核质量表,以及拟基于形变相对论连续谱Hartree-Bogoliubov理论建立高精度原子核质量表的最新进展和展望.

5-Formyluracil targeted biochemical reactions with proteins inhibit DNA replication,induce mutations and interference gene expression in living cells

Covalent DNA–protein cross-links are toxic DNA lesions that interfere with essential biological processes,which can cause serious biological consequences,such as genomic instability and protein misexpression.5-Formyluracil(5 fU) as an important modification in DNA,which is mainly from oxidative damage,exists in a variety of cells and tissues.We have reported that 5 fU mediated DNA–protein conjugates could exist in human cells [Zhou et al.CCS Chem.2(2020) 54–63].We now aimed to explore its potential biological effects in vitro and in vivo.In this paper,we firstly reported that 5 fU intermediated DNA–peptide or DNA–protein conjugates(both were called DPCs) could inhibit different polymerases bypass or cause mutations.Then we further investigated the functional impacts caused by 5 fU-mediated DPCs,which appeared in different gene expression components [in the promoter sequence or 50-untranslated regions(UTR)].These results together may contribute to a broader understanding of DNA–protein interactions as well as the biological functions associated with 5 fU.

Boron-, Sulfur- and Nitrogen-Doped Tridecacyclic Aromatic Emitters with Multiple Resonance Effect for Narrowband Red Emission

Two novel boron(B),sulfur(S),nitrogen(N)-doped polycyclic aromatic hydrocarbon multiple resonance emitters(DBNS and DBNS-tBu)are designed and synthesized for narrowband red emission by embedding two pairs of S and N atoms and two B atoms in para-positions of central benzene rings within a tridecacyclic aromatic skeleton to form donor-π-donor(D-π-D)and acceptor-π-acceptor(A-π-A)structures,which not only exhibit emission maximum at 641 nm with small full width at half maximum of 39 nm,but also combine high photoluminescent quantum efficiency(85%)and rapid reverse intersystem crossing(kRISC=2.2×10^(5) s^(−1)).

Regulable DNA–Protein Interactions in Vitro and Vivo at Epigenetic DNA Marks

5-Formyluracil(5fU)is a vital DNA marker that is widely distributed in the cells of organisms.A unique feature of 5fU is the possession of a potentially reactive aldehyde group in its structure that could realize addition and condensation reactions.However,the biological functional details of 5fU remain mostly elusive,especially,regarding its relatedness with proteins.In this current study,we show that 5fU bases have a strong affinity toward nucleosome core particles,and that could yield regulable DNA–protein conjugates(DPCs)via chemical interactions between amino and aldehyde groups,and reductants could be applied to stabilize or dissociate the interactions.Besides,we developed a photocaged method to exploit the relationship between 5fU and nucleosomes.Finally,by applying a combination of the existence of 5fU–histone interactions in vivo by ChIP analysis of histone H4 with liquid chromatography–mass spectrometry(LC–MS),we probed further,the DPCs’influence on nucleosome and enzyme.Collectively,our results showed that the 5fU–protein interactions increase the occupancy and stability of nucleosomes,affect enzyme recognition,and block DNA replication.These might imply that,in vivo,the DPCs between 5fU and nucleosome core particles might play a key role in 5fU-associated pathways such as DNA repair,transcriptional regulation,or development.