Properties of One-Dimensional Highly Polarized Fermi Gases

Using both the exact Bethe ansatz method and the variational method, we study properties of the one-dimensional Fermi polaron. We focus on the binding energy, effective mass, momentum distributions, Tan contact and correlation functions. As the attraction increases, the impurity is more tightly bound and correlated with the surrounding particles, and the size of formed polaron decreases. In addition, compared with the Bethe ansatz method, the variational method is totally qualified to study the one-dimensional Fermi polaron. The intrinsic reason is that the number of particle-hole excitations in a Fermi sea, caused by a single impurity, is always rather small. The variational method can be well extended to other impurity systems.     

QuEChERS-UPLC-MS/MS快速测定茶叶中23种真菌毒素

建立了QuEChERS(Quick、Easy、Cheap、Effective、Rugged、Safe)-超高效液相色谱-串联质谱法(Ultra-highperformance Liquid Chromatography-Tandem Mass Spectrometry,UPLC-MS/MS)快速测定茶叶中23种真菌毒素的分析方法。样品经过二次提取,十八烷基键合硅胶吸附剂(C₁₈)净化,以ACQUITY UPLC^TM BEH C₁₈色谱柱分离,采用超高效液相色谱-质谱多反应监测(MRM)模式进行检测,外标法定量。在优化的条件下,23种真菌毒素在各自的线性响应范围内线性关系良好,相关系数(r²)均大于0.995,在五种茶叶基质的三个不同加标水平下平均回收率为70.2%～112%,相对偏差(RSD)为1.50%～11.6%(n=6),方法检出限为0.02～9.08μg·kg^-1。此方法具有分析速度快、稳定性好、灵敏度高的特点,能够满足5大类茶叶中23种真菌毒素的快速检测需求。     

液相色谱-串联质谱法测定猪肉中咪唑类药物及其代谢物

建立了高效液相色谱-串联质谱同时测定猪肉中29种咪唑类药物及其代谢物残留的检测方法。样品采用乙酸乙酯提取,浓缩复溶后加入乙腈饱和正己烷净化除脂,以0.3%(体积分数)甲酸水溶液和乙腈为流动相,反相C_(18)色谱柱梯度洗脱分离,采用电喷雾正离子(ESI+)源多反应监测(MRM)模式进行检测。29种化合物在0.05~20.0μg/L范围内线性关系良好,相关系数r~20.99。在1.0~5.0μg/kg添加范围内,平均回收率为65.4%~103%,相对标准偏差(RSD)为1.3%~6.8%。方法检出限为0.02~0.3μg/kg,定量限为0.1~1μg/kg。该方法简便、快速、灵敏,适用于猪肉中咪唑类及其代谢物残留的检测。     

反相高效液相色谱法测定肉松制品中姜黄素的含量

建立了肉松制品中姜黄素含量的反相高效液相色谱测定方法。35℃下,以Ultimate XB-C18（4.6mm×150 mm,5μm）为分析柱,乙腈和0.1%磷酸水溶液（pH2.2）作流动相（体积比为50∶50）等度洗脱,流速1.0 mL/min,425 nm波长下检测。结果表明姜黄素在1.69~169μg/mL浓度范围内呈良好的线性关系,线性回归系数r=0.999 9,方法检出限为1.0 mg/kg,实际样品加标回收率范围为86.9%~94.5%,相对标准偏差为4.6%~7.8%（n=6）。该方法准确可靠、重复性好,可用于肉松制品中姜黄素含量测定。     

Quench dynamics of ultracold atoms in one-dimensional optical lattices with artificial gauge fields

We study the quench dynamics of noninteracting ultracold atoms loaded in one-dimensional(1D) optical lattices with artificial gauge fields, which are modeled by lattices with complex hopping coefficients. After suddenly changing the hopping coefficient, time evolutions of the density distribution, momentum distribution, and mass current at the center are studied for both finite uniform systems and trapped systems. Effects of filling factor, system size, statistics, harmonic trap, and phase difference in hopping are identified, and some interesting phenomena show up. For example, for a finite uniform fermionic system shock and rarefaction wave plateaus are formed at two ends, whose wave fronts move linearly with speed equaling to the maximal absolute group velocity. While for a finite uniform bosonic system the whole density distribution moves linearly at the group velocity. Only in a finite uniform fermionic system there can be a constant quasisteady-state current, whose amplitude is decided by the phase difference and filling factor. The quench dynamics can be tested in ultracold atoms with minimal modifications of available experimental techniques, and it is a very interesting and fundamental example of the transport phenomena and the nonequilibrium dynamics.