Design and analysis of the Macao Science Satellite-1's laser retro-reflector array

The origin and spatial-temporal variation of the Earth’s magnetic field(EMF)is one of the important scientific problems that has long been unsolved.The Macao Science Satellite-1(MSS-1)under construction is China’s first high-precision EMF measurement satellite.To satisfy the highly precise requirements of the MSS-1 orbit measurement,a light,high-precision,four-prism laser retroreflector array was designed.It weighs approximately 285 g,its effective reflection area is greater than 1.77 cm^(2),and its size is 100×100×41 mm.The laser retro-reflector array has excellent performance,and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging.It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration.The MSS-1 is planned to be brought into the International Laser Ranging Service observations.More than 31satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs,which will support the scientific mission of high-precision EMF exploration.

The progress of laser ranging technology at Shanghai Astronomical Observatory

As an important station of International Laser Ranging Service(ILRS),Shanghai Astronomical Observatory(SHAO)has upgraded Satellite Laser Ranging(SLR)system with high repetition rate and achieved some technological progress,There are a lot of improvements for overall system performance,such as annual observation passes,measurement precision and quality of observation data.SLR technology with repetition rate of 10 kHz is accomplished firstly in China,and space debris laser ranging technology with200 Hz laser is promoted and proved to be more detective for weak echo,which lead to successful measurement for 40,000 km satellites and space debris within 3000 km.At the same time,SLR based on multi-telescopes and 1064 nm wavelength are planned to make a breakthrough of detection capabilities,and also to expand its application fields.These progresses will be introduced in this paper in detail.

Effect of Cooling History on Yield Ratio of Fine-grain Ferrite/Pearlite Steel

Effect of different cooling history on yield ratio of HP295 steel for welded gas cylinder was studied and the result implied that both fine microstructure and good mechanical properties can be attained by using two-stage cooling and controlling the coiling temperature. The yield ratio of HP295 steel sheet was reduced to less than 0.8 by twostage cooling process. The pass percent of yield ratio was enhanced from less than 90% to 100%. The mechanical properties satisfied the criteria of GB6653-1994.

Study on Eco-climate Type Regionalization of Wheat Growing Areas in Yunnan Province

In order to provide an objective and scientific theoretical basis for rational distribution of wheat growth in Yunnan Province,according to the relationship between Yunnan weather conditions and wheat growth adaptability,a study on eco-climate type regionalization of wheat growing areas in Yunnan was conducted using principal component analysis and GIS technology. The results show that Yunnan Province could be divided into four types,namely southern warm and humid wheat growing area,central semi-arid wheat growing area,central semi-humid wheat growing area and north-central cold wheat growing area.

Single-wavelength-excited fluorogenic nanoprobe for accurate realtime ratiometric analysis of broad pH fluctuations in mitophagy

Mitophagy has a critical role in maintaining cellular homeostasis through acidic lysosomes engulfing excess or impaired mitochondria,thereby pH fluctuation is one of the most significant indicators for tracking mitophagy.Then such precise pH tracking demands the fluorogenic probe that has tailored contemporaneous features,including mitochondrial-specificity,excellent biocompatibility,wide pH-sensitive range of 8.0–4.0,and especially quantitative ability.However,available molecular probes cannot simultaneously meet all the requirements since it is extremely difficult to integrate multiple functionalities into a single molecule.To fully address this issue,we herein integrate two fluorogenic pH sensitive units,a mitochondria-specific block,cellpenetrating facilitator,and biocompatible segments into an elegant silica nano scaffold,which greatly ensures the applicability for real-time tracking of pH fluctuations in mitophagy.Most significantly,at a single wavelength excitation,the integrated pHsensitive units have spectra-distinguishable fluorescence towards alkaline and acidic pH in a broad range that covers mitochondrial and lysosomal pH,thus enabling a ratiometric analysis of pH variations during the whole mitophagy.This work also provides constructive insights into the fabrication of advanced fluorescent nanoprobes for diverse biomedical applications.

Space debris laser ranging with a 60 W single-frequency slab nanosecond green laser at 200 Hz

Space debris laser ranging was achieved with a 60 W, 200 Hz, 532 nm nanosecond slab, single-frequency green laser at the Shanghai Astronomical Observatory's 60 cm satellite laser ranging systern. There were 174 passes of space debris measured in 2017, with the minimum radar cross section (RCS) being 0.25 m2 and the highest ranging precision up to 13.6 cm. The RCS of space debris measured with the farthest distances in 174 passes was analyzed. The results show that the farthest measurement distance (R) and RCS (S) were fitted to R = 1388.159S024312, indicating that this laser can measure the distance of 1388.159 km at an RCS of 1 m2, which is very helpful to surveillance and research on low-Earth-orbit space debris.

Real-time quantification of nuclear RNA export using an intracellular relocation probe

Nuclear RNA export into the cytoplasm is one of the key steps in protein expression to realize biological functions.Despite the broad availability of nucleic acid dyes,tracking and quantifying the highly dynamic process of RNA export in live cells is challenging.When dye-labeled RNA enters the cytoplasm,the dye molecules are released upon degradation of the RNA,allowing them to re-enter the cell nucleus.As a result,the ratio between the dye exported with RNA into the cytoplasm and the portion staying inside the nucleus cannot be determined.To address this common limitation,we report the design of a smart probe that can only check into the nucleus once.When adding to cells,this probe rapidly binds with nuclear RNAs in live cells and reacts with intrinsic H_(2)S.This reaction not only activates the fluorescence for RNA tracking but also changes the structure of probe and consequently its intracellular localization.After disassociating from exported RNAs in cytoplasm,the probe preferentially enters lysosomes rather than cell nucleus,enabling real-time quantitative measurement of nuclear RNA exports.Using this probe,we successfully evaluated the effects of hormones and cancer drugs on nuclear RNA export in live cells.Interestingly,we found that hormones inhibiting RNA exports can partially offset the effect of chemotherapy.