Response to the Lomagundi-Jatuli Event in the southwestern margin of the Yangtze Plate:Evidence from the carbon and oxygen isotopes of the Paleoproterozoic Yongjingshao Formation

The Lomagundi-Jatuli Event(LJE)refers to the significant positive carbon isotope excursion in seawater constituents that occurred immediately after the increase in atmospheric oxygen content during the Paleoproterozoic(2.22-2.06 Ga).Theδ^(13)C values of 46 dolostone samples collected from the Paleoproterozoic Yongjingshao Formation varied in the range of 0.05‰-4.95‰(V-PDB;maximum:4.95‰)in this study,which may be related to the multicellular eukaryotes in the Liangshan Formation in the Yimen Group.They are much higher than theδ^(13)C values of marine carbonates(-1.16‰on average).Theδ^(13)C values of other formations in the Paleoproterozoic Yimen Group are negative.The notable positive carbon isotope anomalies of the Yongjingshao Formation indicate the response to the LJE at the southwestern margin of the Yangtze Block,which is reported for the first time.Furthermore,they are comparable to theδ^(13)C values of carbonates in the Dashiling Formation of the Hutuo Group in the Wutaishan area in the North China Craton,the Wuzhiling Formation of the Songshan Group in the Xiong'er area,Henan Province,and the Dashiqiao Formation of the Liaohe Group in the Guanmenshan area,Liaoning Province.Therefore,it can be further concluded that the LJE is a global event.This study reveals that LJE occurred in Central Yunnan at 2.15-2.10 Ga,lasting for about 50 Ma.The macro-columnar,bean-shaped,and microfilament fossils and reticular ultramicrofossils of multicellular eukaryotes in this period were discovered in the Liangshan Formation of the Yimen Group.They are the direct cause for the LJE and are also the oldest paleontological fossils ever found.The major events successively occurring in the early stage of the Earth include the Great Oxygenation Event(first occurrence),the global Superiortype banded iron formations(BIFs),the Huronian glaciation,the Great Oxygenation Event(second occurrence),the explosion of multicellular eukaryotes,the positive carbon isotope excursion,and the global anoxic and selenium-rich sedimentary event.The authors think that the North China Craton and the Yangtze Craton were possibly in different tectonic locations of the same continental block during the Proterozoic.

Restraint Effect of Filaments on Applied Voltage in Atmospheric Pressure Glow Discharge

In this study, argon and nitrogen were used as the discharge gases in radio-frequency （RF： 13.56 MHz） powered dielectric barrier atmospheric plasma. It was noticed that in single dielectric barrier discharge （DBD） with nitrogen as the discharge gas, or in argon plasma with a high applied power, micro-filament channels were easily formed. The channels in these two kinds of discharge were both constrictive on the bare metallic electrode and expansive on the opposite electrode covered with a quartz layer. The number of micro-channels was increased along with the input power, which caused the change in the I-V curve shape, i.e., the current kept increasing and the voltage fluctuated within a confined range. With double dielectric layers, however, no micro-channels appeared in the ICCD images, and the I-V curve demonstrated a totally different shape. It was assumed that micro-filaments exhibited a restraining effect on the discharge voltage. The mechanism of this restraining effect was explored in this work.

SEGMENTAL DISTRIBUTION OF AFFERENT ELECTRO-ACUPUNCTURE SIGNALS FROM ACUPOINTS OF THE PERICARDIUM MERIDIAN IN THE RAT

Objective: To observe the segmental distribution of afferent Electroacupuncture (EA) signals from acupoints of the Pericardium (PC) Meridian and try to analyze the relative specificity of running route of PC Meridian.Methods: A total of 85 Wistar rats anesthetized with mixed solution of Chloralose (5 mg/100 g) and Urethane (42 mg/100g) were used in this study. Under microscopic observation, the micro-filaments of the distal end of the dorsal root were carefully separated after tearing the spinal pia mater to attach to a recording electrode. The reference electrode was placed beneath the skin of the incision. Two caudal and two rostral dorsal roots near the recorded one were cut off separately. Electrical activity of the isolated micro-filaments was observed before and after EA of "Daling" (PC 7) -"Jianshi" (PC 5), "Quze" (PC 3) of PC Meridian, "Yangchi"(TE 4)- "Zhigou" (TE 6), "Tianjing" (TE 10)-" Qin-glengyuan" (TE 11) of the Triple Energizer (TE) Meridian with electric current 1 mA and 2 mA and double pulses. Results: ① After EA (1 mA) of "Daling"(PC 7)-"Jianshi"(PC 5), the firing rates of 3 out of 10 (33.3%) micro-filaments in C5 segment, 5 out of 10 (50.0%) in C6, 7 out of 10 (70.0%) in 07, 3 out of 10 (30.0%) in C8 and 3 out of 13 (23. 1%) in T1 increased considerably；and after EA of "Quze" (PC 3), those of 3/10 of C5, 4/10 of C6, 6/10 of C7, 3/10 of C8, and 3/10 of T1 increased significantly. ② After EA (1 mA) of "Yangchi"(TE 4)- "Zhigou" (TE 6) and "Tianjing" (TE 10)- "Qinglengyuan" (TE 11). the firing rates of 2/10, 2/10 of micro-filaments In C5, 7/10, 3/10 of C6, 5/10 and 4/10 of C7, 1/10 and 1/10 of C8, and 2/13 and 1/10 of T1 increased significantly. It indicates that C7 dorsal root may play the first important role in conveying EA signals from PC Meridian acupoints to the spinal cord, while C6 and C7 may be mainly responsible for conveying EA signals from TE Meridian acupoints to the spinal cord. Conclusion: The peripheral afferent pathway for transmitting EA signals from PC Meridian acupoints probably has a relative specificity.