CP violations in predictive neutrino mass structures

We study the CP-violation effects from two types of neutrino mass matrices with (i) \((M_\nu )_{ee}=0\), and (ii) \((M_\nu )_{ee}=(M_\nu )_{e\mu }=0\), which can be realized by the high-dimensional lepton number violating operators \(\bar{\ell }_R^c\gamma ^\mu L_L (D_\mu \Phi )\Phi ^2\) and \(\bar{\ell }_R^c l_R (D_\mu {\Phi })^2\Phi ^2\), respectively. In (i), the neutrino mass spectrum is in the normal ordering with the lightest neutrino mass within the range \(0.002\,\mathrm{eV}\lesssim m_0\lesssim 0.007\,\mathrm{eV}\). Furthermore, for a given value of \(m_0\), there are two solutions for the two Majorana phases \(\alpha _{21}\) and \(\alpha _{31}\), whereas the Dirac phase \(\delta \) is arbitrary. For (ii), the parameters of \(m_0\), \(\delta \), \(\alpha _{21}\), and \(\alpha _{31}\) can be completely determined. We calculate the CP-violating asymmetries in neutrino–antineutrino oscillations for both mass textures of (i) and (ii), which are closely related to the CP-violating Majorana phases.     

On the Relative Twist Formula of l-adic Sheaves

We propose a conjecture on the relative twist formula of l-adic sheaves, which can be viewed as a generalization of Kato—Saito's conjecture. We verify this conjecture under some transversal assumptions. We also define a relative cohomological characteristic class and prove that its formation is compatible with proper push-forward. A conjectural relation is also given between the relative twist formula and the relative cohomological characteristic class.     

缺中子Np新核素的α衰变研究

合成远离稳定线的新核素、探索原子核存在的极限是目前核物理研究的重要课题。在中子壳N=126的最丰质子一侧,极端缺中子的超铀核素处于质子滴线和中子壳的交叉位置,合成和研究该核区核素对研究N=126壳结构的演化性质具有重要意义。基于兰州重离子加速器上的充气反冲核谱仪装置(SHANS),利用36,40Ar+185,187Re熔合蒸发反应,合成了极缺中子的219,220,223,224Np新核素,在中子壳N=126附近首次建立了Np同位素链的$ \alpha$衰变系统性,获得了N=126壳效应在Np同位素链中依然存在的实验证据。依据单质子分离能的系统性分析,确定了Np同位素链中质子滴线的位置,219Np也成为目前已知的最重的质子滴线外核素。此外,基于实验测量的反应截面,并与理论模型的计算结果相比较,讨论了进一步合成该核区其它新核素218,221,222Np的可行性。     

An improved evaluation of the neutron background in the PandaX-Ⅱ experiment

In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.     

Anisotropic phononic crystal structure with low-frequency bandgap and heat flux manipulation

This study presents a two-dimensional phononic crystal with heat flux manipulation and wide bandgaps of out-of-plane modes within the low-frequency range. The anisotropic matrix made of spiral-multilayered materials with different thermal conductivities, and the coating layer inserted with metal are designed for heat flux manipulation. Rubber-coated metal cylinders are periodically embedded in the anisotropic matrix to obtain the low-frequency bandgaps of out-of-plane modes. Numerical simulation is carried out to validate the heat and elastic characteristics of the spiral-multilayered anisotropic structure and reveal the effects of the laying angle and temperature on the bandgaps. Subsequently, a spiral-multilayered plate with periodic structures is studied, which shows an obvious vibration attenuation in the frequency ranges of the bandgaps and a deflected heat flux from the initial propagation direction. In the experimental investigation, the multi-phase spiral-multilayered anisotropic plate is simplified to a single-phase anisotropic plate made of aluminum. The characteristics of this type of anisotropic phononic crystal structure may pave the way for the design of a new kind of thermo-acoustic metamaterial serving in combined thermal and acoustic environments.     

新冠疫情对我国信贷风险冲击的定量测算

文章建立了宏观经济传导模型和信贷风险传导模型,根据对GDP的估计,对新型冠状病毒感染肺炎疫情下的2020年全国和若干疫情严重省市的不良贷款率进行了定量测算.假设一季度内疫情得以控制,全年GDP增速下降至5.7％的情景下,预计全国年末不良贷款率约3％,不良贷款余额比2019年增加逾80％,接近2019年国内商业银行贷款损...     

开展化学实验技能竞赛促进实验教学

通过开展实验技能竞赛等措施 ,增强学生的动手能力 ,提高实验教学水平 ,促进实验教学 ,建立有工程特色的化学实验体系     

分辨力增强技术的频谱分析

离轴照明和衰减型相移掩模作为重要的分辨力增强技术,不仅可以提高光刻的分辨力,同时还可以改善成像焦深,扩大光刻工艺窗口,实现65~32 nm分辨成像。从频谱的角度分析了离轴照明和衰减型相移掩模对成像系统交叉传递函数和像场空间频率分布的影响,研究这两种技术的物理光学本质,由此进一步优化光学成像系统设计、分辨力增强技术和确定设备使用的参量。对分辨力增强技术的频谱分析研究表明,分辨力增强技术通过调整像场频谱分布,改善了光学光刻的图形质量。对于65 nm密集图形,离轴照明和相移掩模结合后可以使成像衬比度最高达到0.948,工艺窗口在5%曝光范围内焦深达到0.51μm。     

Fabrication of Sulfated Heterosaccharide/Poly (Vinyl Alcohol) Hydrogel Nanocomposite for Application as Wound Healing Dressing

Nowadays, natural polysaccharides-based hydrogels have achieved promising results as dressings to promote skin healing. In the present study, we prepared a novel hydrogel nanocomposite with poly(vinyl alcohol) (PVA) and sulfated heterosaccharide (UF), named UPH. The SEM results showed that the UPH had dense porous structures with a high porosity and a specific surface area. The UPH had a good swelling property, which can effectively adsorb exudate and keep the wound moist. The in vitro experiments results showed that the UPH was non-cytotoxic and could regulate the inflammatory response and promote the migration of fibroblasts significantly. The phenotypic, histochemistry, and Western blot analyses showed UPH treatment accelerated the wound healing and recovery of skin tissue at wound sites in a C57BL/6 mouse model. Furthermore, the UPH could promote the inflammation process to onset earlier and last shorter than that in a normal process. Given its migration-promoting ability and physicochemical properties, the UPH may provide an effective application for the treatment and management of skin wounds.     

Nonvolatile photorefractive holographic recording in Sc:Ce:Cu:LiNbO3

In this paper experimental studies of nonvolatile photorefractive holographic recording in Ce:Cu:LiNbO₃ crystals doped with Sc(0,1,2,3 mol%) were carried out. The Sc:Ce:Cu:LiNbO₃ crystals were grown by the Czochralski method and oxidized in Nb₂O₅ powders. The nonvolatile holographic recording in Sc:Ce:Cu:LiNbO₃ crystals was realized by the two-photon fixed method. We found that the recording time of Sc:Ce:Cu:LiNbO₃ crystal became shorter with the increase of Sc doping concentration, especially doping with Sc(3 mol%), which exceeds the so-called threshold, and there was little loss of nonvolatile diffraction efficiencies between Sc(3 mol%):Ce:Cu:LiNbO₃ and Ce:Cu:LiNbO₃ crystals.