The Development of Emergency Communication Device for Tianwen-1 Probe

Mars is one of the most valuable planets for space exploration.After entering the entry descent and landing(EDL)phase,the spacecraft would carry out a series of procedural deceleration operations and achieve soft landing on the surface of Mars.In the process of EDL,the landing platform would encounter a series of irreversible incidents within environmental unpredictability,making this process highly risky.The emergency communication device plays an important role if in the Mars Exploration Program.It can capture and store key dynamic parameters during EDL phase,enabling a high probability of survival in the occurrence of a faulty condition.It can also send the stored data to the Mars obit probe when the communication condition is met.This paper presents a scheme design for the emergency communication device based on its functionality and performance requirements.It includes the design proposal,simulation results,reliability analysis,technical risks and control measures,inheritance and performance compliance which verifies the rationality and correctness of the design.

The Mars orbiter magnetometer of Tianwen-1:in-flight performance and first science results

The Mars Orbiter MAGnetometer(MOMAG)is a scientific instrument onboard the orbiter of China’s first mission for Mars—Tianwen-1.Since November 13,2021,it has been recording magnetic field data from the solar wind to the magnetic pile-up region surrounding Mars.Here we present its in-flight performance and first science results,based on its first one and one-half months’data.Comparing these early MOMAG observations to the magnetic field data in the solar wind from NASA’s Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we report that the MOMAG magnetic field data are at the same level in magnitude,and describe the same magnetic structures with similar variations in three components.We recognize 158 clear bow shock(BS)crossings in these MOMAG data;their locations match well statistically with the modeled average BS.We also identify and compare five pairs of datasets collected when Tianwen-1’s orbiter and the MAVEN probe made simultaneous BS crossings.These BS crossings confirm the global shape of modeled BS,as well as the south-north asymmetry of the Martian BS.Two cases presented in this paper suggest that the BS is probably more dynamic at flank than near the nose.So far,MOMAG performs well,and provides accurate magnetic field vectors.MOMAG is continuously scanning the magnetic field surrounding Mars.Data from MOMAG’s measurements complement data from MAVEN and will undoubt edly advance our understanding of the plasma environment of Mars.

Phenomenology of plume-surface interactions and preliminary results from the Tianwen-1 landing crater on Mars

The plume-surface interaction(PSI)is a common phenomenon that describes the environment surrounding the landers resulting from the impingement of hot rocket exhaust on the regolith of planetary bodies.The PSI will cause obscuration,erosion of the planetary surface,and high-speed spreading of dust or high-energy ejecta streams,which will induce risks to a safe landing and cause damage to payloads on the landers or to nearby assets.Safe landings and the subsequent scientific goals of deep-space exploration in China call for a comprehensive understanding of the PSI process,including the plume flow mechanics,erosion mechanism,and ejecta dynamics.In addition,the landing crater caused by the plume provides a unique and insightful perspective on the understanding of PSI.In particular,the PSI can be used directly to constrain the composition,structure,and mechanical properties of the surface and subsurface soil.In this study,we conducted a systematic review of the phenomenology and terrestrial tests of PSI:we analyzed the critical factors in the PSI process and compared the differences in PSI phenomena between lunar and Martian conditions;we also reviewed the main erosion mechanisms and the evolution and development of terrestrial tests on PSI.We discuss the problems with PSI,challenges of terrestrial tests,and prospects of PSI,and we show the preliminary results obtained from the landing crater caused by the PSI of Tianwen-1.From analysis of the camera images and digital elevation model reconstructions,we concluded that the landing of Tianwen-1 caused the deepest crater(depth>40 cm)on a planetary surface reported to date and revealed stratigraphic layers in the subsurface of Martian soil.We further constrained the lower bounds of the mechanical properties of Martian soil by a slope stability analysis of the Tianwen-1 landing crater.The PSI may offer promising opportunities to obtain greater insights into planetary science,including the subsurface structure,mineral composition,and properties of soil.

Proton pitch angle distributions in the Martian induced magnetosphere: A survey of Tianwen-1 Mars Ion and Neutral Particle Analyzer observations

The pitch angle distributions of ions and electrons can be affected by various processes;thus,they can serve as an important indicator of the physical mechanisms driving the dynamics of space plasmas.From observations from the Mars Ion and Neutral Particle Analyzer onboard the Tianwen-1 orbiter,we calculated the pitch angle distributions of protons in the Martian induced magnetosphere by using information from the magnetohydrodynamically simulated magnetic field,and we statistically analyzed the spatial occurrence pattern of different types of pitch angle distributions.Even though no symmetrical features were seen in the dataset,we found the dominance of the field-aligned distribution type over the energy range from 188 to 6232 eV.Maps of the occurrence rate showed the preferential presence of a trapped-like distribution at the lower altitudes of the surveyed nightside region.Although our results are more or less restricted by the adopted magnetic field,they indicate the complexity of the near-Mars proton pitch angle distributions and infer the possibility of wave–particle interactions in the Martian induced magnetosphere.

Ground calibration of the Mars orbiter magnetometer onboard Tianwen-1

Ground calibration experiments of the Mars orbiter magnetometer(MOMAG)onboard the orbiter of Tianwen-1 were performed to determine the sensitivity,misalignment angle,and offset of the sensors.The linearity of the applied calibrated magnetic fields and the output from the sensors were confirmed to be better than 10^(-4),and the sensor axes were orthogonal to each other within 0.5 degrees.The temperature dependencies of the sensitivity and misalignment angle were examined,but no clear signatures of temperature dependencies could be seen.Sensor offset and the stability of sensor offset drift with a temperature change were also determined by the rotation method.The stability of the sensor offset drift was less than 0.01 nT/℃.The ground calibration of MOMAG determines all the calibration parameters of the sensors for accurate magnetic field measurements in orbit with the appropriate corrections.

Observations and interpretations of geomorphologic features in the Tianwen-1 landing area on Mars by using orbital imagery data

China’s first Mars exploration mission,Tianwen-1,successfully landed in southern Utopia Planitia on Mars on May 15,2021.This work presents a detailed investigation of the geologic context of the landing area surface for this mission based on orbital remotesensing data.We constructed a geomorphologic map for the Tianwen-1 landing area.Results of our detailed geomorphologic map show several major landforms within the landing area,including rampart craters,mesas,troughs,cones,and ridges.Analysis of materials on the landing area surface indicates that most of the landing area is covered by Martian dust.Transverse aeolian ridges are widely distributed within the landing area,indicating the surface contexts were(and still are)modified by regional winds.In addition,a crater counting analysis indicates the landing area has an absolute model age of~3.3 Ga and that a later resurfacing event occurred at~1.6 Ga.Finally,we outline four formational scenarios to test the formation mechanisms for the geomorphologic features on the landing area surface.The most likely interpretation to explain the existence of the observed surface features can be summarized as follows:A thermal influence may have played an important role in the formation of the surface geomorphologic features;thus,igneous-related processes may have occurred in the landing area.Water ice may also have been involved in the construction of the primordial surface configuration.Subsequent resurfacing events and aeolian processes buried and modified the primordial surface.

靶向程序性细胞死亡蛋白配体-1多肽类放射性核素标记分子探针研究进展

程序性细胞死亡蛋白配体-1(PD-L1)是一个重要的免疫检查点分子,在调节机体免疫反应方面发挥重要作用。临床研究表明,肿瘤组织中PD-L1的表达水平与免疫检查点抑制剂疗效密切相关。由于肿瘤的时空异质性,临床上常用的免疫组织化学方法不能全面准确地反映患者体内PD-L1的表达水平,而核医学分子影像技术可在分子水平上无创、实时、动态、可视化监测机体内PD-L1的表达水平。本文主要针对靶向PD-L1多肽类放射性分子探针的研究进行综述,为寻找新型免疫成像的多肽类分子探针及免疫治疗适宜患者的筛选和疗效评估等提供指导。

磁共振靶向成像检测心肌纤维化大鼠模型中TGF-β1表达的实验研究

目的构建载转化生长因子-β1(transforming growth factor beta-1,TGF-β1)的超小超顺磁性氧化铁(ultrasmall supperparamagnetic iron oxide,USPIO)靶向探针(USPIO-anti-TGF-β1),探究其表征及磁共振成像(magnetic resonance imaging,MRI)靶向检测大鼠心肌纤维化(myocardial fibrosis,MF)模型中TGF-β1表达的可行性。材料与方法选择40只雄性SD大鼠,其中30只采用异丙肾上腺素(isoprenaline,ISO)皮下注射法建立MF模型,另外10只作为健康对照组。通过超声评估大鼠模型建立情况。将造模成功的30只大鼠随机分为实验组、单纯对照组及空白对照组,每组10只;构建USPIO-anti-TGF-β1靶向探针,通过尾静脉注入实验组大鼠体内,单纯对照组及空白对照组分别注入相同剂量的USPIO和生理盐水,并于注射12 h后行T2序列扫描。扫描完成后取大鼠心肌标本行病理学分析。采用独立样本t检验对给药前后的MRI信号强度变化进行分析。结果MRI示实验组给药前心肌信号尚均匀,给药12 h后心内膜下心肌可见信号减低区,二者相对信号强度具有明显差异(0.72±0.12 vs.0.62±0.10,P<0.01);单纯对照组与空白对照组给药前后心肌信号未见明显减低(0.73±0.12 vs.0.71±0.12,P=0.81;0.70±0.13 vs.0.74±0.13,P=0.52)。普鲁士蓝染色显示实验组MF区域与给药后MRI所示信号减低区相符合,免疫组化可见MF区域TGF-β1的阳性表达,普鲁士蓝染色显示心肌细胞中有大量铁颗粒的沉积,证实USPIO-anti-TGF-β1靶向探针的存在。结论通过USPIO-anti-TGF-β1靶向探针进行MRI在体检测MF大鼠模型中TGF-β1的表达可行,为临床监测TGF-β1的表达及抗MF治疗方案的选择和疗效评估提供了实验依据。

牙周炎正畸患者的龈沟液HMGB1、sICAM-1、IL-33、TSLP水平变化以及与牙周指标的关联性分析

目的:探讨牙周炎正畸患者治疗前后龈沟液高迁移率族蛋白B1(High mobility group box-1 protein,HMGB1)、可溶性细胞间黏附分子-1(soluble Intercellular adhesion molecule-1,sICAM-1)、白细胞介素-33(Interleukin-33,IL-33)、胸腺基质淋巴细胞生成素(Thymic stromal lymphopoietin,TSLP)水平动态变化及与牙周指标的关联性。方法:选择2019年1月-2021年8月笔者医院就诊的124例牙周炎正畸治疗患者作为研究对象进行回顾性分析,根据患者的治疗效果分为疗效良好(n=104)与疗效不良(n=20)。对比不同疗效患者的临床资料、牙周指标、龈沟液指标水平,分析牙周炎正畸患者疗效影响因素及龈沟液指标与牙周指标的关联性,并绘制工作特征曲线(ROC)评价龈沟液指标对患者预后的评估价值。结果:疗效良好患者治疗后牙周指标[菌斑指数(Plaque index,PLI)、出血指数(Bleeding Index,BI)、探诊深度(Probing depth,PD)]均低于疗效不良患者,差异有统计学意义(P<0.05);疗效良好患者治疗后龈沟液HMGB1、sICAM-1、IL-33、TSLP水平均低于疗效不良患者,差异有统计学意义(P<0.05);Logistic回归分析可知,治疗后牙周指标PLI、PD、BI及龈沟液HMGB1、sICAM-1、IL-33、TSLP水平均为牙周炎正畸患者治疗效果不良的影响因素(P<0.05);牙周炎正畸患者龈沟液HMGB1、sICAM-1、IL-33、TSLP水平均与牙周指标PLI、PD、BI呈正相关(P<0.05);术后龈沟液HMGB1、sICAM-1、IL-33、TSLP水平联合评估牙周炎正畸治疗患者疗效的AUC(0.934)最大,具有较高评估效能。结论:牙周炎正畸患者治疗前后龈沟液HMGB1、sICAM-1、IL-33、TSLP水平变化与其牙周状态关系密切,联合检测可为临床评估治疗效果并积极完善治疗方案提供参考。

Tianwen-1 MINPA observations in the solar wind

The Mars Ion and Neutral Particle Analyzer(MINPA)is one of the three scientific instruments onboard the Tianwen-1 orbiter to investigate the Martian space environment.During Tianwen-1’s transfer orbit to Mars,the MINPA was switched on to measure the solar wind ions.Here,we present the first results of the MINPA observations in the solar wind.During cruise,nearly half of the MINPA ion field-of-view(FOV)was blocked by the lander capsule;thus only the solar-wind ions with azimuthal speeds pointing towards the unblocked FOV sectors could be detected.We perform a detailed comparison of the MINPA’s solar wind observations with data from Earth-based missions when MINPA reached its count-rate peak,finding a general consistency of the ion moments between them.The blocking effect due to the lander is evaluated quantitatively under varying solar-wind velocity conditions.Despite the blocking effect,the MINPA’s solar wind measurements during the transfer orbit suggest a good performance.

Mars Orbiter magnetometer of China’s First Mars Mission Tianwen-1

As one of the seven scientific payloads on board the Tianwen-1 orbiter,the Mars Orbiter Magnetometer(MOMAG)will measure the magnetic fields of and surrounding Mars to study its space environment and the interaction with the solar wind.The instrument consists of two identical triaxial fluxgate magnetometer sensors,mounted on a 3.19 meter-long boom with a seperation of about 90 cm.The dual-magnetometers configuration will help eliminate the magnetic field interference generated by the spacecraft platform and payloads.The sensors are controlled by an electric box mounted inside the orbiter.Each magnetometer measures the ambient vector magnetic field over a wide dynamic range(to 10,000 nT per axis)with a resolution of 1.19 pT.Both magnetometers sample the ambient magnetic field at an intrinsic frequency of 128 Hz,but will operate in a model with alternating frequency between 1 and 32 Hz to meet telemetry allocations.

The payloads of planetary physics research onboard China’s First Mars Mission (Tianwen-1)

Mars is not only our nearby but also the most Earth-like planetary neighbor.Scientific exploration of Mars is thus of crucial value to our understanding of the solar system.The existence of abundant evidence for the former presence of water on Mars demands further exploration for signs of life on our sister planet,and investigations that could shed light on conditions favorable to the origin of life.For nearly 60 years,humans have conducted orbitally-based remote sensing and in-situ surface exploration of Mars,leading to many significant scientific discoveries.But much remains to be done before we can be sure that we truly and fully understand Mars.Key research topics include the history of water on Mars and how that history relates to the planet’s habitable environment-past,present,and future;the distribution and evolution of waterbearing and evaporative salt minerals on the planet’s surface;the history of volcanic activity on Mars;the Martian magnetic field and its effect on the escape of water and atmosphere from the planet;interactions between the solar wind and the Martian atmosphere and ionosphere;atmospheric characteristics and climate change on Mars;and so on(Li CL et al.,2018;Liu JJ et al.,2018).Based on the above scientific questions about life,climate,and geology on Mars,the international planetary science community has formulated ambitious Mars exploration programs.

Overview of the Mars climate station for Tianwen-1 mission

The background and scientific objectives of the Mars Climate Station(MCS)for Tianwen-1 are introduced,accompanied by a comparative review of the status of related meteorological observation missions and of advanced sensing technologies.As one of the China Tianwen-1 Mission’s principal scientific payloads,the MCS contains four measurement sensors and one electronic processing unit that are specially designed to measure local temperature,pressure,wind,and sound on the Martian surface.The MCS’s measurement principles,technical schemes,ground calibration techniques,and adaptability evaluation to the Mars surface environment of MCS are introduced in details.The conclusion presents measurement performance specifications of the MCS,based on ground test results,that will provide guidance to future research based on data from the Tianwen-1 and later Mars missions.

Bias Effects on the Reynolds Stress Using the Multi-Purpose Probe in IR-T1 Tokamak

The effect of the positive bias on Reynolds stress （RS） and its effect on the radial turbulent transport at the edge plasma （r/a =0.9） and scrape-off layer （SOL） region of plasma in tokamak are investigated. The radial and poloidal electric fields （Sr, Ep） and ion saturation current （Is） are measured by multi-purpose probe （MPP）. This probe is fabricated and constructed for the first time in the IR-T1 tokamak. The most advantage of this probe is that the variations of Er and Ep can be measured in different radii at the single shot. Thus the information of different radii can be compared with high precision. The bias voltage is fixed at Vbias = 200 V and it has been applied with the limiter bias that is fixed in r/a = 0.9. Moreover, the phase difference between radial and poloidal electric fields, and temporal evolution of the RS .spectrum detected by MPP are calculated. RS magnitude on the edge （r/a = 0.9） is more than its value in the SOL （r/a = 1.02）. With the applied bias 200 V, ItS and the magnitude of the phase difference between Er and Ep are increased, while the radial turbulent transport is decreased simultaneously. Thus it can be concluded that RS affects radial turbulence. Temporal evolution of the RS spectrum shows that the frequency of RS is increased and reaches its highest value at r/a=0.9 in the presence of bias.

A First Principles Simulation Framework for the Interactions between a Si(001) Surface and a Scanning Probe

By means of total energy calculations within the framework of the local density approximation (LDA), the interactions between a silicon Si(001) surface and a scanning probe are investigated. The tip of the probe, comprising 4 Si atoms scans along the dimer lines above an asymmetric p(2 × 1) surface, at a distance where the chemical interaction between tip-surface is dominant and responsible for image resolution. At that distance, the tip causes the dimer to toggle when it scans above the lower atom of a dimer. The toggled dimers create an alternating pattern, where the immediately adjacent neighbours of a toggled dimer remain unchanged. After the tip has fully scanned across the p(2 × 1) surface, causes the dimers to arrange in a p(2 × 2) reconstruction, reproducing the images obtained in scanning probe experiments. Our modelling methodology includes simulations that reveal the energy input required to overcome the barrier to the onset of dimer toggling. The results show that the energy input to overcome this barrier is lower for the p(2 × 1) surface than that for the p(2 × 2) or c(4 × 2) surfaces.

A Novel Fluorescence Probe 9-(4-(1,2-diamine)benzeneN^1-phenyl)acridine for Nitric Oxide Determination

A novel fluorescent probe 9-（4-（1,2-diamine）benzene-N1-phenyl）acridine（DABPA） was synthesized for the detection of nitric oxide（NO） and characterized by IR, 1H-NMR and EI-MS spectroscopy. Based on a photoelectron transfer mechanism, the fl uorescence intensities of DABPA were investigated with the different concentrations of NO. Under the optimal experimental conditions, the fl uorescence intensity of DABPA had a good linear relationship（R2=0.9977） with NO concentration in the range from 1×10-7 to 1.5×10-6 mol/L with a detection limit of 1×10-8 mol/L. The cytotoxicity induced by DABPA was evaluated by the MTT（3-（4,5-dimethylthiazol-2-yl）-2,5diphenyl tetrazolium bromide） assay for biological application. Furthermore, the probe DABPA had also been successfully applied to real-time image NO produced in PC12 cells in the presence of L-arginine.

用于肼检测的新型芘基荧光分子探针的合成与性能

利用1-芘甲醛优良的荧光性质,将其作为母体进行基团修饰,经过^(1)H-NMR和HRMS对结构进行表征,证实成功构建了肼荧光分子探针PMIDO。在DMSO-H2O体系中,PMIDO只能显示弱的荧光;在加入肼后,在含水量70%的条件下,显示出强的蓝色荧光,呈现出开灯型的荧光探针特征,检出限可达1.41×10^(-7)mol/L。同时,该探针对肼的检测呈现出高选择性和稳定抗干扰性,适用于5~10的pH范围,并在30 s内完成响应。进一步阐述了其荧光检测机制,即与肼反应后生成腙,为反应型肼的荧光检测提供有益参考。

新型H_(2)S的荧光探针制备及其在水样中的应用

以2-(3,5,5-三甲基环己-2-烯-1-基)丙二腈(TCM)和4-羟基苯甲醛为原料合成TCM-OH作为荧光团,以7-硝基-1,2,3-苯并二唑胺(NBD)作为识别单元,设计并合成了一种新型的近红外荧光探针(TCM-NBD),用于检测水样中的H_(2)S。考察了不同pH对探针响应H_(2)S的影响、探针对H_(2)S浓度和时间响应、探针的选择性和灵敏度,并推测可能的响应机理。结果显示,探针TCM-NBD对H_(2)S可以实现快速响应(<10 min);在0~25μmol/L范围内,吸光度和荧光强度与H_(2)S浓度之间均呈良好的线性关系,相关性分别为0.9947和0.9926,检测限分别为0.28、0.84μmol/L。该探针抗干扰性强,灵敏度高,可以成功应用于环境水样中的H_(2)S测定。

TIMP-1在肝纤维化形成过程中的作用

目的 研究TIMP 1在肝纤维化形成过程中的作用。方法 皮下注射CCl4建立小鼠肝纤维化模型 ;RT PCR扩增TIMP 1cDNA片段 ,定向克隆到转录载体pSPT18上 ,构建pSPT18/TIMP 1重组质粒 ,转化E .coliJM10 9,进行质粒提取、酶切鉴定、序列分析、体外转录合成探针、原位杂交。结果 成功建立小鼠肝纤维化模型 ;获得的TIMP 1目的基因片段大小为 2 6 2bp ,与预期结果相同 ;经酶切鉴定和序列分析证实成功构建了pSPT18/TIMP 1重组质粒 ;原位杂交结果显示 ,TIMP 1主要在激活的肝星型细胞、内皮细胞、间质细胞以及正常肝细胞中表达 ,且随着肝纤维化的逐步形成 ,TIMP 1的表达逐渐升高。结论 TIMP 1参与肝纤维化的形成过程 。