长碳链聚醚酰胺永久型抗静电剂的制备与性能

以自制的长碳链聚醚酰胺弹性体(TPAE)为基体,通过加入不同种类的碱金属钠盐与锂盐,采用熔融挤出加工的方法制备了聚醚酰胺永久型抗静电剂。重点研究了不同含量的高氯酸锂(LiClO_4)对TPAE性能的影响,采用高阻计、扫描电镜、红外光谱对抗静电剂的表面电阻率、淬断面结构、化学结构进行了表征,并对其拉伸性能和耐漂洗性等进行了研究。结果表明,LiClO_4的质量分数为6%时,其在TPAE中分布均匀,抗静电效果较好,表面电阻率可以达到2×10~7Ω/sq,断裂伸长率在600%以上,而且抗静电性不会因为漂洗而失去,抗静电效果持久,是一种性能优异的永久型抗静电剂。

Significant salinity increase in subsurface waters of the South China Sea during 2016–2017

The South China Sea(SCS) is the largest semi-enclosed marginal sea in the North Pacific. Salinity changes in the SCS play an important role in regional and global ocean circulation and the hydrological cycle. However, there are few studies on salinity changes over the SCS due to lack of high-quality and long-term observations. In the past decade, the deployment of floats from the Argo program in the SCS and their accumulated temperature and salinity profiles have made it possible for us to examine salinity changes over the entire basin. In this study,salinity changes were investigated with Argo and underwater glider temperature and salinity observations and gridded temperature–salinity objective analyses(UK Met Office Hadley Centre EN4.2.1 objective analysis and China Argo Real-time Data Center BOA_Argo). The results indicated that the subsurface water in the entire SCS became significantly saltier during 2016–2017. The most significant salinity increase was found during 2016 in the northeastern SCS. The subsurface water in the northeastern SCS exhibited a salinity maximum above 35, which was recorded by three Argo floats during 2015–2016. Such high salinity water was rarely observed and reported prior to the Argo era. Average salinity of 2016–2017 along the 25.5σ_θ–23.5σ_θ isopycnal surfaces in the whole SCS is 0.014-0.130 higher than the climatology. Increases in subsurface salinity started from the northeastern SCS and extended southwestward gradually. Moreover, the subsurface salinity changes, especially in the northern SCS,exhibited a semiannual lead behind the subsurface Luzon Strait transport. Further analysis indicated that the predominance of advection, driven by subsurface Luzon Strait transport, led to salinification along the western boundary of the SCS. In other parts of the SCS, negative wind stress curl trends tended to preserve the high salinity characteristics of the subsurface water.

Using triple oxygen isotopes and oxygen-argon ratio to quantify ecosystem production in the mixed layer of northern South China Sea slope region

Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross primary production and net community production of the mixed layer zone,respectively.Although there is a substantial advantage in refining the gas exchange term and water column vertical mixing calibration,application of mixed layer depth history to the gas exchange term and its contribution to reducing indices error are unclear.Therefore,two cruises were conducted in the slope regions of the northern South China Sea in October 2014(autumn)and June 2015(spring).Discrete water samples at Station L07 in the upper 150 m depth were collected for the determination ofδ^(17)0,δ^(18)O,and the O_(2)/Ar ratio of dissolved gases.Gross oxygen production(GOP)was estimated using the triple oxygen isotopes of the dissolved O_(2),and net oxygen production(NOP)was calculated using O_(2)/Ar ratio and O_(2)concentration.The vertical mixing effect in NOP was calibrated via a N_(2)O based approach.GOP for autumn and spring was(169±23)mmol/(m^(2)·d)(by O_(2))and(189±26)mmol/(m^(2)·d)(by O_(2)),respectively.While NOP was 1.5 mmol/(m^(2)·d)(by O_(2))in autumn and 8.2 mmol/(m^(2)·d)(by O_(2))in spring.Application of mixed layer depth history in the gas flux parametrization reduced up to 9.5%error in the GOP and NOP estimations.A comparison with an independent O_(2)budget calculation in the diel observation indicated a26%overestimation in the current GOP,likely due to the vertical mixing effect.Both GOP and NOP in June were higher than those in October.Potential explanations for this include the occurrence of an eddy process in June,which may have exerted a submesoscale upwelling at the sampling station,and also the markedly higher terrestrial impact in June.

Three-dimensional circulation in northern South China Sea during early summer of 2015

Using the hydrographic data obtained during two nearly simultaneous surveys in June 2015,we carried out semi-diagnostic calculations with the help of a finite element model and a modified inverse method,to study the circulation in the northern South China Sea(NSCS)during the early summer of 2015.A number of new circulation features were found.(1)In most of the observation region,a large,basin-scale anticyclonic gyre appeared south of the 50-m isobath,which contained anticyclonic eddies.One anticyclonic eddy existed from the sea surface to 50-m depth,whose center showed no tilt,while the center of another eddy tilted eastward from the sea surface to 500-m depth.In the eastern part of the observation region,which is west of the Dongsha Islands,there was a sub-basin-scale cyclonic gyre containing a cyclonic eddy whose center tilted southward from the sea surface to 200-m depth.(2)There was a cross-continental slope current(CCSC)in the area southwest of the Dongsha Islands.Its volume transport was about 2.0×10^(6) m^(3)/s.(3)From the estimated order of magnitude of the stream function equation,the joint effect term of the baroclinity and relief(JEBAR)andβ-effect term are two important dynamic mechanisms affecting the variation of the circulation in the NSCS.(4)The JEBAR,as a transport-generating term,resulted in the dynamic mechanism determining the pattern of the depth-averaged flow across the contours of potential vorticity fH–1.Furthermore,we show that the negative values of the JEBAR were the most dominant dynamic mechanism,causing the CCSC southwest of the Dongsha Islands to deflect from the isobaths and veer toward the deep water.The CCSC around the Dongsha Islands was located further southwest during the early summer of 2015 than during the fall of 2005(revealed by a published study),which suggests that the location of the CCSC around the Dongsha Islands may vary with season.