Room-Temperature Phosphorescence and Lifetime of Fossil Resins (Amber) from Dominican Republic, Mexico, Baltic Sea, Myanmar, and Fushun, China

Amber can emit room temperature phosphorescence(RTP)under the well-known 365 nm fluorescence ultraviolet light.This paper is devoted to the phosphorescence study of 20 pieces of amber materials from the Dominican Republic,Mexico,Baltic sea,Myanmar,and Fushun,China.The results show that amber from the same geographic origin has similar shape in phosphorescence spectra.However,the shape of the amber phosphorescence spectra varies depending on their different localities.Burmite(amber from Myanmar)and Fushun amber have a bright yellow phosphorescence with a long lifetime,while the Dominican and Mexican ones are weaker and last shorter.The irradiation of Baltic amber becomes faint or even inert.Phosphorescence spectral Gaussian fitting results suggest an emission maximum near 550 nm in most amber samples.Their phosphorescence lifetime,analyzed through the exponential function fitting,is up to 1 second in Burmite and Fushun samples,shorter in the Dominican and Mexican ones,about 0.230 s,and the shortest in Baltic amber,close to 0.151 s.These variations of phosphorescence lifetime and intensity are related to the relative geological ages of these amber.It indicated that the phosphorescence agent was probably formed during the long geological time.While the anomaly occurred in Baltic amber,the only one found in a sea secondary deposit form,it demonstrated that the terrestrial geological environment these amber preserved has prevented the phosphorescence agent to be deactivated.

Misalignment Angle Calculation Accuracy Analysis of Three-Axis Stabilized Geostationary Satellite

The most challenging problem of navigation in three-axis stabilized geostationary satellite is accurate calculation of misalignment angles, deduced by orbit measurement error, attitude measurement error, thermal elastic deformation, time synchronization error, and so on. Before the satellite is launched, the misalignment model must be established and validated. But there were no observation data, which is a non-negligible risk of yielding the greatest returns on investment. On the basis of misalignment modeling using landmarks and stars, which is not available between different organizations and is developed by ourselves, experimental data are constructed to validate the navigation processing flow as well as misalignment calculation accuracy. In the condition of using landmarks, the maximum misalignment calculation errors of roll, pitch, and yaw axis are 2, 2, and 104 micro radians, respectively, without considering the accuracy of image edge detection. While in the condition of using stars, the maximum errors of roll, pitch, and yaw axis are 1, 1, and 3 micro radians, respectively, without considering the accuracy of star center extraction. Results are rather encouraging, which pave the way for high-accuracy image navigation of three-axis stabilized geostationary satellite. The misalignment modeling as well as calculation method has been used in the new generation of geostationary meteorological satellite in China, FY-4 series, the first satellite of which was launched at the end of 2016.

A novel seal-flow multi-vortex friction stir lap welding of metal to polymer matrix composites

The friction stir lap welding(FSLW)of metal to polymer is a challenging work due to the unavoidable polymer overflowing.Facing this problem,a novel seal-flow multi-vortex friction stir lap welding(SM-FSLW)technology based on the subversively-designed multi-step pin was put forward.Choosing 7075 aluminum alloy and short glass fiber-reinforced polyether ether ketone(PEEK)as research subjects,the welding temperature,material flow,formation and tensile shear strength of dissimilar materials lap joint under the SM-FSLW were studied and compared with those under traditional FSLW based on the conical pin.The multi-step pin rather than the conical pin effectively hindered the polymer overflowing due to the formation of vortexes by the step,thereby attaining a joint with a smooth surface.Compared with traditional FSLW,the SMFSLW obtained the higher welding temperature,the more violent material flow and the larger area with high flow velocity,thereby producing the macro-mechanical and micro-mechanical interlockings and then heightening the joint loading capacity.The tensile shear strength of lap joint under SM-FSLW was 27.8% higher than that under traditional FSLW.The SM-FSLW technology using the multi-step pin provides an effective way on obtaining a heterogeneous lap joint of metal to polymer with the excellent formation and high strength.

Microstructure Evolution and Mechanical Properties of Friction Stir Welded Al-Cu-Li Alloy

The investigation concentrates on friction stir welded(FSW)Al-Cu-Li alloy concerning its local microstructural evolution and mechanical properties.The grain features were characterized by electron back scattered diffraction(EBSD)technology,while precipitate characterization was conducted by using transmission electron microscopy(TEM)aligned along[011]Al and[001]Al zone axes.The mechanical properties are evaluated through micro-hardness and tensile testing.It can be found that nugget zones exhibit finely equiaxed grains evolved through complete dynamic recrystallization(DRX),primarily occurring in continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX).In the thermal-mechanically affected zone(TMAZ),numerous sub-structured grains,exhibiting an elongated morphology,were created due to partial DRX,signifying the dominance of CDRX,DDRX,and geometric dynamic recrystallization(GDRX)in this region.T_(1)completely dissolves in the nugget zone(NZ)leading to the formation of Guinier-Preston zones and increase ofδ′,β′and S′.Conversely,T_(1)partially solubilizes in TMAZ,the lowest hardness zone(LHZ)and heat affected zone(HAZ),and the residual T_(1)undergoes marked coarsening,revealing various T_(1)variants.The solubilization and coarsening of T_(1)are primary contributors to the degradation of hardness and strength.θ′primarily dissolves and coarsens in NZ and TMAZ,whilst this precipitate largely coarsens in HAZ and LHZ.σ,TB,grain boundary phases(GBPs)and precipitate-free zone(PFZ)are newly generated during FSW.σexists in the TMAZ,LHZ and HAZ,whereas TB nucleates in NZ.GBPs and PFZ mostly develop in LHZ and HAZ,which can cause strain localization during tensile deformation,potentially leading to LHZ joint fracture.

一例患者经颈静脉肝内门体分流术术中碘克沙醇致过敏性休克后顺利完成手术及文献分析

河北医科大学第二医院消化内科收治一例68岁患者,局部麻醉下行经颈静脉肝内门体分流术(transjugular intrahepatic portosystem shunt,TIPS),使用碘克沙醇注射液高压造影,15分钟后患者出现血压下降、皮肤瘙痒等症状,考虑患者出现过敏性休克,立即给予抗过敏、抗休克等急救治疗措施。患者生命体征指标逐渐恢复,过敏性休克症状逐渐消失,手术继续且顺利完成,无并发症发生。现就此例经颈静脉肝内门体分流术术中碘克沙醇注射液致过敏性休克患者的抢救措施及治疗情况进行分析,旨在加强临床安全使用碘克沙醇的用药意识。当患者使用碘克沙醇注射液造影时,短时间内出现血压下降,皮肤瘙痒等问题时,可能发生了过敏性休克。术中应严密观察患者的病情,及时发现过敏症状并及时进行有效处理,是抢救过敏性休克的关键。

Achieving High‑Quality Aluminum to Copper Dissimilar Metals Joint via Friction Stir Double‑Riveting Welding

In order to achieve a high-quality joining of aluminum(Al)and copper(Cu)dissimilar metals,a new friction stir doubleriveting welding(FSDRW)with a Cu rod as the rivet was proposed,and the rotating tool with a large concave angle shoulder was specially designed.The results showed that under the thermal–mechanical effect of rotating tool,the Cu rod was deformed to be a double riveting heads structure with a Cu anchor at the upper surface of Al plate and an Al anchor above the lap interface of joint,and these two anchors greatly enhanced the mechanical interlocking of Al/Cu joint.The effective bonding interfaces were formed among the double riveting heads structure,the upper Al plate and the lower Cu plate,which contained the Cu/Cu interface and the Al/Cu interface.The Cu/Cu interface without the kissing bond and the Al/Cu interface with the rationally thin AlCu and Al_(2)Cu intermetallic compounds(IMCs)layers were beneficial to heightening the joint tensile shear strength.The maximum tensile shear load of the FSDRW joint achieved 5.52 kN,and the joint under different plunging depths of rotating tool presented a mixed mode of ductile fracture and brittle fracture.This novel FSDRW technique owns the advantages of strong mechanical interlocking and superb metallurgical bonding,and provides a new approach to acquiring a high-quality Al/Cu dissimilar metals joint.

H_(2)O_(2) actuated molybdenum oxide nanodots:Multi-enzyme-like activities,leverage of Fenton reaction,and dual-mode sensitive detection of alendronate sodium

Unexpected benefits to the catalytic performance of materials often originate from the presence of surface defects.Here,novel Dpenicillamine modified molybdenum oxide nanodots,with abundant oxygen vacancy defects,were fabrication by a mild,simple,and cost-effective method.Ultraviolet–visible(UV–Vis)absorption spectra analysis showed that the nanodots had peroxidaselike and catalase-like activities.The reactive oxygen species were probed by electronic paramagnetic resonance technique and spectroscopic methods,demonstrating that the nanodots also had oxidase-like activity.Interestingly,the peroxidase-like activity of nanodots was synergistically enhanced in the presence of ferrous ions or ferric ions.Remarkably,less than nanomolar levels of ferrous ions were required to display this phenomenon,meaning Fenton reagent acted as leverage.Based on this,a sensitive colorimetric and fluorescent dual-mode sensor for alendronate sodium was developed.The linear ranges for colorimetric and fluorescence analysis were 0.2–2.5 and 0.2–2.0μM,with detection limits of 31.21 and 71.84 nM,correspondingly.The method has a simple large-scale material preparation process with higher sensitivity and shorter reaction time,which can inspire and enlighten the design of nanozyme sensors.

Microstructural formation and mechanical performance of friction stir double-riveting welded Al-Cu joints

A novel friction stir double-riveting welding(FSDRW) technology was proposed in order to realize the high-quality joining of upper aluminum(Al) and lower copper(Cu) plates,and this technology employed a Cu column as a rivet and a specially designed welding tool with a large concave-angle shoulder. The formations, interfacial characteristics, mechanical properties and fracture features of Al/Cu FSDRW joints under different rotational velocities and dwell times were investigated. The results showed that the well-formed FSDRW joint was successfully obtained.The cylindrical Cu column was transformed into a double riveting heads structure with a Cu anchor at the top and an Al anchor at the bottom, thereby providing an excellent mechanical interlocking.The defect-free Cu/Cu interface was formed at the lap interface due to the sufficient metallurgical bonding between the Cu column and the Cu plate, thereby effectively inhibiting the propagation of crack from the intermetallic compound layer at the lap interface between the Al and Cu plates. The tensile shear load of joint was increased first and then decreased when the rotational velocity and dwell time of welding tool increased, and the maximum value was 5.52 k N. The FSDRW joint presented a mixed mode of ductile and brittle fractures.

HIV-1 Env三聚体抗原改造研究进展

HIV-1疫苗研发是当前艾滋病研究的一大热点,其病毒表面包膜糖蛋白Env三聚体介导病毒与细胞融合,是HIV-1疫苗研究的重要靶点。因此,设计并在体外表达类天然Env三聚体对HIV-1疫苗的研发具有重要的意义。近年来,Env三聚体研究取得了显著的进展。SOSIP、NFL2P、UFO等抗原改造方法实现了类天然Env三聚体的体外表达,逐步解决了改造抗原产量低、结构不稳定等问题,且表达的Env三聚体抗原能在动物免疫中诱导机体产生较高的中和抗体水平。Env三聚体改造方法促进了HIV-1疫苗的研究。文中综述了SOSIP、NFL2P、UFO三种HIV-1 Env三聚体抗原改造方法,对比各个改造方法优缺点,并结合自身工作提出相关建议,为后续HIV-1抗原的相关设计提供指导。

HIV-1 CAP2NC蛋白的表达及体外自组装

构建并表达HIV-1 CAP2NC蛋白,探索其体外自组装条件。通过PCR技术扩增HIV-1(NL4-3毒株)CAP2NC基因片段,并将其连接到原核表达载体pTO-T7,获得重组质粒pTO-T7-CAP2NC,然后转化至大肠杆菌BL21(DE3)菌株,经疏水层析纯化后获得重组蛋白CAP2NC。SDS-PAGE结果表明,重组蛋白CAP2NC可在大肠杆菌可溶高效表达,经纯化后纯度约为95%。ELISA检测表明重组蛋白CAP2NC可被HIV-1衣壳蛋白特异性单克隆抗体识别,具有较好反应活性。重组蛋白透析后在非原性SDS-PAGE中呈现为多种聚体形式。分子筛排阻层析分析CAP2NC蛋白透析后可进行组装,负染电镜进一步观察显示CAP2NC蛋白在RNA存在条件下,可形成空心管状颗粒,其形态结构与HIV-1病毒衣壳体外自组装形成的类似。上述结果表明HIV-1 CAP2NC蛋白具有体外自组装的性质,为进一步在体外研究非成熟病毒样颗粒结构奠定基础。

Effects of Combined Pre-straining and Pre-aging on Natural Aging and Bakehardening Response of an Al-Mg-Si Alloy

For a series of Al-0.34／%Mg-1.05／%Si-0.08／%Cu alloys, the effects of pre-treatment on natural aging, bake hardening response and plasticity were investigated using Vickers hardness test and tensile test. Differential scanning calorimetry （DSC） analysis was conducted to reveal corresponding precipitation mechanisms. The results showed that pre-straining and pre-aging alone couldn＇t completely suppress natural aging and improve bake hardening response simultaneously. The sensitivity of the pre-straining and pre-aging on the mechanical properties was evaluated. It was found that pre-aging was the main factor which greatly improved bake hardening response and pre-treatment had a weak influence on plasticity in pre-treated samples. DSC analysis showed that the dissolution trough of clusters disappeared in pre-treated samples, both β”and β＇ precipitation peak shifted to lower temperature and were reduced in pre-strained and pre-aged samples. It was concluded that the formation of Mg/Si clusters was replaced by the accelerated precipitation ofβ” andβ＇ phases, which caused the suppression of natural aging and the improvement of bake hardening response （BHR）.

Effect of microbial fermentation on the sensory characteristics and chemical compositions of Chinese sweet tea(Lithocarpus litseifolius(Hance)Chun)

Sweet tea,which has hundreds of years of use among in Chinese folk,is a traditional herbal tea with pleasant sweetness,bitterness and astringency.In the current study,we used traditional microbial fermentation to improve sensory characteristics of sweet tea,especially for the reduction of bitterness and astringency.The dynamic changes of non-volatile,volatile compounds and microbial community were investigated during microbial fermentation.The contents of polyphenols,flavonoids,soluble sugar,soluble protein,catechins and dihydrochalcones decreased significantly while the tea pigments,free amino acids and gallic acid content inversely increased during microbial fermentation.A total of 61 volatile compounds were identified and quantified in sweet tea,of which 20 key compounds were identified as odor active compounds(OAV),including 3 aldehydes,1 ketone,4 alcohols,9 esters,4 alkenes and 3 other compounds.In addition,eight fungi and four bacteria were considered as core microorganisms,such as Aspergillus,Alternaria,Cladosporium,Epicoccum,Itersonilia,Penicillium,Periconia,Wallemia,Aureimonas,Enterobacter,Klebsiella and Stenotrophomonas,which were significantly correlated with non-volatile compounds and flavor compounds.These results provided theoretical guidance for processing of fermented sweet tea.

基于网络药理学的策略研究溪黄草治疗炎症疾病的药理机制

溪黄草最重要的活性成分是对映贝壳杉烷二萜类化合物,此类化合物的主要作用是降低炎症的发生率,有助于发挥溪黄草的抗炎药理作用。本研究的目的是利用网络药理学分析的方法寻找溪黄草中的活性成分,将这些活性化合物与我们建立的二萜化合物库相匹配,找到并确定所有符合条件的对映贝壳杉烷二萜化合物。其次,在数据库中找到溪黄草的活性化合物的作用靶点以及人体内抗炎靶点,结合得到交集,这代表了溪黄草中活性化合物的潜在抗炎靶点。然后,将抗炎靶点和活性化合物靶点进行蛋白质-蛋白质相互作用网络合并,得到蛋白质相互作用网络交叉点和抗炎靶蛋白-相互作用网络中的核心基因。最后对溪黄草的抗炎靶点,进行了基因本体论(GO)和京都基因与基因组百科全书(KEGG)通路分析,以确认溪黄草对抗炎症的基因功能。最终,TCMSP分析从48种对映贝壳杉烷中鉴定出10种活性化合物。通路分析显示糖尿病并发症、小细胞肺癌和人巨细胞病毒感染中AGE-RAGE信号通路等不同通路富集,均与炎症有关。该方法清晰地鉴定了溪黄草中的对映-贝壳杉二萜类化合物,首次得到了溪黄草的活性化合物。中药定性分析与网络药理学相结合的方法可以发现潜在的中药材作用靶点,揭示中药材的生物学过程,并为今后的中医药研究开辟一种新方法。

An accurate and efficient radiative transfer model for simulating all-sky images from Fengyun satellite radiometers

Forward radiative transfer models(RTM)are an indispensable tool for quantitative applications of satellite radiometers,e.g.,for data calibration,instrument development,retrieval,and so on.In this study,we develop an accurate and efficient RTM for radiometers onboard Fengyun satellites,namely FYRTM(RTM for Fengyun Radiometers).Correlated k-distribution models are developed to improve the computational efficiency for gas absorption,and the effects of cloud and aerosol multiple scattering and emission are accelerated with pre-computed look-up tables.FYRTM is evaluated with a rigorous simulation based on discrete ordinate radiative transfer model(DISORT)as well as a popular fast forward model,i.e.,the Community Radiative Transfer Model(CRTM).Results indicate that FYRTM-based simulations are two to three orders of magnitudes faster than the DISORT-based simulations.Compared to the rigorous model,FYRTM relative errors are within 2%at solar channels,and brightness temperatures(BT)differences are within 1 K at infrared channels.Compared with CRTM,FYRTM is computationally similar at solar channels,but three times faster at infrared channels.Furthermore,simulated reflectances/BTs using FYRTM are in a good agreement with the satellite observations.Overall,FYRTM is capable to simulate satellite observations under different atmospheric conditions,and can be extended to other radiometers onboard the Fengyun satellites(both geostationary and polarorbiting satellites).It is expected to play important roles in future applications with Fengyun observations.

Spatiotemporal variation and source analysis of air pollutants in the Harbin-Changchun (HC) region of China during 2014e2020

This study analyzed the characteristics of air pollution and specific pollution periods within the HarbinChangchun(HC)metropolitan area during 2014e2020.Regarding annual,seasonal,and monthly variations of the six pollutants,the change trend in 11 cities of HC showed strong consistency in spatial distribution.The western cities(Songyuan,Daqing,and Siping)were vulnerable to dust storms from Inner Mongolia.The concentrations of all air pollutants,except O3-8h,showed downward fluctuation trends from 2014 to 2018 and remained stable from 2018 to 2020 in terms of annual variations.The interannual trend of significant reductions in SO2 and SO2/PM2.5 during the heating period indicated that strict emission reduction measures posed by the government were highly successful.The ratio of PM2.5/SO2 was used to identify open biomass burning(OBB),which showed a double peak(OctobereNovember(OcteNov),MarcheApril(MareApr)).The burning prohibition shifted the OBB from OcteNov to Mar eApr.