Differential rotation in F stars

Differential rotation can be detected in single line profiles of stars rotating more rapidly than about v sin i = 10km s-1 with the Fourier transform technique. This allows to search for differential rotation in large samples to look for correlations between differential rotation and other stellar parameters. I analyze the fraction of differentially rotating stars as a function of color, rotation, and activity in a large sample of F-type stars. Color and rotation exhibit a correlation with differential rotation in the sense that more stars are rotating differentially in the cooler, less rapidly rotating stars. Effects of rotation and color, however, cannot be disentangled in the underlying sample. No trend with activity is found. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

比表面积氮气吸附法在蒙脱石碱性溶蚀表征中的应用

蒙脱石矿物颗粒粒径小、比表面积大、水敏性强,易堵塞储层孔隙和喉道,是影响油田储层质量的主要黏土矿物,碱性条件下蒙脱石的溶蚀特征是油田开发中普遍关注的问题。对于蒙脱石溶蚀特征的表征,前人常用的方法有反应前后质量对比法、X射线衍射法、溶液离子浓度分析法及pH值分析法,质量对比法操作复杂,X射线衍射图谱计算人为误差大,溶液离子浓度法对难熔元素的检测误差大,pH值法受温度变化的影响。本文应用比表面积氮气吸附法测量蒙脱石在不同氢氧化钠浓度条件下的比表面积、孔容、孔径变化及吸附脱附曲线来表征其碱性溶蚀特征,优选出适合油田开发的氢氧化钠溶液浓度及充注时间(反应时间)等实验条件,确定了最佳溶蚀浓度为0.05 mol/L氢氧化钠溶液,最佳反应时间为3 h。实验表明,比表面积氮气吸附法测得的比表面积、孔容、孔径及吸附脱附曲线表征的蒙脱石溶蚀特征,与反应后溶液pH值及离子(如Si4+)浓度变化所得的结论相同,验证了该方法的正确性,且具有直观、准确、可靠的特点,可应用于比表面积较大的多孔矿物溶蚀研究。     

Eocene migmatite formation and diachronous burial revealed by petrochronology in NW Himalaya,Zanskar

In this contribution, we highlight the importance of in-situ monazite geochronology linked to P−T modelling for identification of timescales of metamorphic processes. Barrovian-type micaschists, migmatites and augengneiss from the Gumburanjun dome in the southeastern extremity of the Gianbul dome, NW Himalaya, have been studied in order to correlate the early stages of Himalayan metamorphism at different crustal levels and infer the timing of anatexis. P−T−t paths are constrained through combined pseudosection modelling and in-situ and in-mount monazite and xenotime laser ablation–split-stream inductively coupled plasma-mass spectrometry. Petrography and garnet zoning combined with pseudosection modelling show that garnet-staurolite schists record burial from ~530 to 560°C and 5.5 kbar to ~630 to 660°C and 7 kbar; staurolite-kyanite schists from ~530 to 560°C and 5 kbar to ~670 to 680°C and 7−9 kbar; and garnet-kyanite migmatites from 540−570°C and 5 kbar to ~680 to 750°C and 7−10 kbar, probably also to >750°C and >9 kbar above the muscovite stability field. The decompression paths of garnet-staurolite schists indicate cooling on decompression, while garnet rim chemistry and local sillimanite growth point to a stage of re-equilibration at ~600 to 670°C and 4−6 kbar in some of the staurolite-kyanite schists, and at ~670 to 700°C and 6 kbar in garnet-kyanite migmatites. Some of the staurolite-kyanite schists and garnet-kyanite migmatites also contain andalusite or andalusite-cordierite. Monazite and xenotime were analysed in thin sections in garnet, staurolite and kyanite, and in the matrix; and in mounts. BSE images and compositional maps of monazite (xenotime was too small) show variable internal structures from homogeneous through patchy zoning with embayed to sharp boundaries. Two groups of samples can be identified on the basis of the presence or absence of c. 44 − 37 Ma ages. The first group of samples—two garnet-staurolite schists—recorded only c. 31 − 27 Ma ages in porphyroblasts and no c. 40 Ma ages. The second group (samples of staurolite-kyanite schist, garnet-kyanite migmatites, augengneiss) have both the older, c. 44 − 37 Ma monazite ages in porphyroblasts and younger ages down to c. 22 Ma. These significantly different ranges of ages from porphyroblasts of 44−37 Ma, and 31−27 Ma, are interpreted as the duration of prograde P−T paths in Eocene and Oligocene, and indicate diachronous two-stage burial of rocks. Early migmatization occurred at 38 Ma. The c. 29 Ma is interpreted as the time when rocks from the lower and middle crustal levels were partially exhumed and came in to contact with rocks that were downgoing at this time. Localized monazite recrystallization is as young as 26−24 Ma. The youngest ages of 23−22 Ma are related to leucogranite emplacement.     

温泉水中H2S对游离C02检测的影响

在实验室条件下模拟温泉水中H2S和游离C02来研究温泉水中H2S对游离C02现场检测的影响,以及现场检测时如何消除H2s的影响。实验结果证明：温泉水中H2S对游离C02的测定存在影响,其影响结果随H2S含量的不同而不同;采用扣除法可以很好的消除温泉水中H2S对游离CO2测定的影响。     

文山铝土矿A12O3测试中半二甲酚橙的作用

一水硬铝石及含刚玉（A12O3）铝土矿的测试较困难。NaF置换滴定法以二甲酚橙及半二甲酚橙较敏锐。可用半二甲酚橙（变色酸度在PH=5～6）直接调节酸度,再用作滴定的指示剂,效果较好。     

高温燃烧水解-离子色谱法测定植物样品中的氟

建立了高温燃烧水解-离子色谱测定植物样品中不同含量范围氟的分析方法,色谱条件为Dionex IonPacAS18分离柱(4 mm×250 mm),Dionex IonPac AG18保护柱(4 mm×50 mm),ASRS ULTRAⅡ自动再生微膜抑制器,电导检测器。采用纯水作为吸收介质,使样品溶液与标准溶液基体一致,过滤后可直接测定。样品溶液中常见的Cl-、NO3-、SO24-、PO43-、CO23-、HCO3-等阴离子不干扰F-的测定。为消除样品热解过程中产生的乙酸干扰,对氟含量较高(xx～xxxμg/g)的样品,采用20 mmol/L的NaOH淋洗液等度淋洗,进样体积为25μL;对氟含量较低的样品(0.x～xμg/g),进样体积为100μL。方法具有较宽的线性范围和较好的稳定性,检出限为0.5 mg/kg,适用于痕量分析;应用于灌木枝叶和茶叶等4个氟含量较高(xx～xxxμg/g)的植物标准物质的测定,相对标准偏差(RSD)<6%(n=6);应用于低氟的小麦粉和大米粉样品测定,加标回收率为90%～110%,可以满足不同氟含量植物样品中氟测定的需要,具有自动化程度高、操作简单、对环境友好等特点。     

应用间溴偶氮羧—m光度法测定碳酸盐岩石及粮食中的铝

本文提出了用碳酸钠和氢氧化钠熔矿，在熔矿，提取过程中分离钙、镁、铁、锰等绝大部分干扰元素，应用间溴偶氮羧－ｍ作显色剂测定碳酸盐岩石及粮食中的铝的分光光度法，结果准确，重现性好。     

Scientific detector workshop 2022 on-sky performance verification of near-infrared e−APD technology for wavefront sensing and demonstration of e−APD pixel performance to improve the sensitivity of large science focal planes

Near-infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high-speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state-of-the-art conventional CMOS technology of near-infrared arrays as has been attempted previously. A total of five near-infrared SAPHIRA 320 × 256 pixel HgCdTe e⁻APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is m_k = 19, which is made possible with ADP technology. New avalanche photo-diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10⁻³ e⁻/s have been demonstrated with 1Kx1K e⁻APD arrays and 2Kx2K e⁻APD arrays have already been developed, the possibilities and adaptations of e⁻APD technology to provide noiseless large-format science-grade arrays for long integration times are also discussed.