VEGETATION CHANGES OF THE TAIHANG MOUNTAINS SINCE THE LAST GLACIAL

The vegetation of the Taihang Mountains was dominated by grass with less than 10％ forested area during the last pleniglacial. During the period of 17 000－ 10 000 a B.P. the forested area reached to 20％ － 30％ , and reached to 20％ － 40％ during the Early Holocene in the period of 10 000－ 8 000 a B.P. followed by the temperature increasing rapidly. But the northern part had more forested area than that of the southern part. During the period of 8000－ 5000 a B.P. forests developed further to 50％ or more. It was the highest period of the forest cover degree. After then, the forests began to be destroyed first in the southern part of the Taihang Mountains by people. Since 2500 a B.P. the forests were destroyed deadly. The forest cover decreased to less than 5％ before 1949. Since 1949 , although the government hold the policy of close hillsides to facilitate afforestation, the forest cover of Taihang Mountains could not exceed 11.6％ . So afforestation is an important work to keep economic and ecological sustainable development.

Uncovering the prominent role of satellite cells in paravertebral muscle development and aging by single-nucleus RNA sequencing

To uncover the role of satellite cells(SCs)in paravertebral muscle development and aging,we constructed a single-nucleus transcriptomic atlas of mouse paravertebral muscle across seven timepoints spanning the embryo(day 16.5)to old(month 24)stages.Eight cell types,including SCs,fast muscle cells,and slow muscle cells,were identified.An energy metabolism-related gene set,TCA CYCLE IN SENESCENCE,was enriched in SCs.Forty-two skeletal muscle disease-related genes were highly expressed in SCs and exhibited similar expression patterns.Among them,Pdha1 was the core gene in the TCA CYCLE IN SENESCENCE;Pgam2,Sod1,and Suclg1 are transcription factors closely associated with skeletal muscle energy metabolism.Transcription factor enrichment analysis of the 42 genes revealed that Myod1 and Mef2a were also highly expressed in SCs,which regulated Pdha1 expression and were associated with skeletal muscle development.These findings hint that energy metabolism may be pivotal in SCs development and aging.Three ligand-receptor pairs of extracellular matrix(ECM)-receptor interactions,Lamc1-Dag1,Lama2-Dag1,and Hspg2-Dag1,may play a vital role in SCs interactions with slow/fast muscle cells and SCs self-renewal.Finally,we built the first database of a skeletal muscle single-cell transcriptome,the Musculoskeletal Cell Atlas(http://www.mskca.tech),which lists 630,040 skeletal muscle cells and provides interactive visualization,a useful resource for revealing skeletal muscle cellular heterogeneity during development and aging.Our study could provide new targets and ideas for developing drugs to inhibit skeletal muscle aging and treat skeletal muscle diseases.

Fatigue crack growth behavior of 2624-T39 aluminum alloy with different grain sizes

The microstructure of 2624-T39 aluminum alloy was analyzed by means of metallographic(OM), scanning electron microscope(SEM) and transmission electron microscope(TEM). The effects of different microstructure characteristics on the tensile properties and fatigue crack growth rate of 2624-T39 aluminum alloy were studied.Results showed that the grain size of the alloy was a typical fiber structure along the rolling direction, and the main second phase was the A_(l2)CuMg phase. The grain size of the alloy had an obvious influence on the fatigue crack growth rate, and the alloy showed a lower fatigue crack growth rate due to the larger grain size. The crack initiation zone on the fracture surface of alloys with lower fatigue crack growth rate was relatively rough, the crack propagation zone had obvious fatigue striations, and the transient fracture zone had a large number of smaller dimples.

MONOSACCHARIDE COMPOSITION OF POLYSACCHARIDES THROUGH HILIC-UPLC-TQ-MS/MS

A simple,sensitive and direct method was developed for compositional analysis of plant polysaccharides using hydrophilic interaction ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry(HILIC-UPLC-TQ-MS/MS)in multiple-reaction monitoring(MRM).The effects of chromatographic columns,scan time,additive types,