The largest exponential gain coefficient(Γ=250 cm^(-1)),to our knowledge,is obtained in thin(d=0.20mm)iron-doped LiNbO_(3) crystal.The dependence of two-beam coupling coefficients on beam crossing angle are measured ...The largest exponential gain coefficient(Γ=250 cm^(-1)),to our knowledge,is obtained in thin(d=0.20mm)iron-doped LiNbO_(3) crystal.The dependence of two-beam coupling coefficients on beam crossing angle are measured and compared in two samples fabricated from the same material with different values of thickness.The explanation based on light climbing effect is given.展开更多
文摘目的:基于超高效液相色谱串联四极杆飞行时间质谱(UHPLC-QTOF-MS^(E))分析并经数字量化处理,结合随机森林(Random Forest,RF)算法构建数据辨识模型,以实现中华草龟、巴西龟、台湾龟、鳄鱼龟、鳖甲基原的数字化鉴定。方法:经样品预处理后,对不同来源、不同批次的龟甲进行UPLC-QTOF-MS^(E)分析,并以混合样品为基准进行峰位校正、提取并经量化处理,获取反映多肽离子信息的精确质量数-保留时间数据对(Exact Mass Retention Time,EMRT)。然后基于信息增益率的特征筛选获取重要多肽离子信息,结合随机森林(RF)算法进行数据建模,同时基于内部交叉验证中的准确率(Acc)、精确率(P)、曲线下面积(AUC)等参数进行模型评价。最后基于最优模型进行龟甲基原的鉴定验证分析。结果:基于信息增益率的特征筛选,得到71个特征多肽信息,建立的RF模型具有优秀的辨识效果,准确率、精确率以及AUC均大于0.950且外部鉴定验证的正确率为100.0%。结论:基于UHPLC-QTOF-MS^(E)分析,并结合RF算法能够高效准确地实现不同来源龟甲基原的数字化鉴定,可为龟甲的质量控制及基原考证提供参考和帮助。
文摘The largest exponential gain coefficient(Γ=250 cm^(-1)),to our knowledge,is obtained in thin(d=0.20mm)iron-doped LiNbO_(3) crystal.The dependence of two-beam coupling coefficients on beam crossing angle are measured and compared in two samples fabricated from the same material with different values of thickness.The explanation based on light climbing effect is given.