带有非负非线性源的拟线性双曲方程BV解的存在唯一性

主要研究了一类带有非负的非线性源的拟线性双曲守恒律方程的Cauchy问题,其中初值为有限Borel测度.克服了初值和非线性项带来的阻碍,得到了局部BV解的存在唯一性.     

主流烟气中甲胺和乙胺离子色谱法测定

建立了用0.01 mol·L-1盐酸水溶液吸收,离子色谱法测定卷烟主流烟气中甲胺和乙胺的方法。该方法采用Ion Pac CS16(4×250 mm)分离柱和CG16(4×50 mm)保护柱,10mmol·L-1甲烷基磺酸(MSA)水溶液等梯度洗脱,在柱温60℃、流速1.0 m L·min-1的条件下,实现了甲胺和乙胺的有效分离。方法的线性关系良好,RSD均小于5%,甲胺检出限为0.04μg/支,加标平均回收率为92.7%~94.3%,乙胺检出限为0.05μg/支,加标平均回收率为93.5%~103.0%。该方法灵敏度高、准确性好、前处理简单,有良好的可靠性和实用性。     

顶空固相微萃取-气相色谱-质谱法快速测定酱油中的挥发性风味成分

建立了一种快速简便地测定酱油中挥发性风味成分的顶空固相微萃取（HS-SPME）-气相色谱-质谱法(GC-MS)。以2-辛醇为内标,考察了萃取头、萃取时间、离子强度、萃取温度对酱油样品中挥发性风味物质萃取的影响。该方法对酱油中常见挥发性风味成分的测定有良好的重复性和回收率,对常见挥发性物质的定量比较准确。优化的HS-SPME条件为：涂层厚度为85 μm聚丙烯酸酯(PA)萃取纤维头,于45 ℃、NaCl质量浓度为250 g/L下对酱油样品顶空吸附40 min,于250 ℃下解吸2 min后进行GC-MS分离鉴定。酱油样品的分析结果表明,其挥发性风味物质中含量较高的是醇、酸、酯和酚类,此外还有一些羰基化合物和杂环化合物。     

Fabrication of honeycomb AuTe monolayer with Dirac nodal line fermions

Two-dimensional honeycomb lattices show great potential in the realization of Dirac nodal line fermions (DNLFs). Here, we successfully synthesized a gold telluride (AuTe) monolayer by direct tellurizing an Au(111) substrate. Low energy electron diffraction measurements reveal that it is (2×2) AuTe layer stacked onto (3×3) Au(111) substrate. Moreover, scanning tunneling microscopy images show that the AuTe layer has a honeycomb structure. Scanning transmission electron microscopy reveals that it is a single-atom layer. In addition, first-principles calculations demonstrate that the honeycomb AuTe monolayer exhibits Dirac nodal line features protected by mirror symmetry, which is validated by angle-resolved photoemission spectra. Our results establish that monolayer AuTe can be a good candidate to investigate 2D DNLFs and provides opportunities to realize high-speed low-dissipation devices.