报道了室温下基于循环级联的高效率Er∶YAG中红外脉冲激光器,采用循环级联谐振腔,通过优化晶体长度提高光束交叠效率,获得高效率中红外激光输出。实验中使用两种掺杂浓度(原子数分数分别为25%和10%)的长度为2 mm Er∶YAG晶体作为增益介...报道了室温下基于循环级联的高效率Er∶YAG中红外脉冲激光器,采用循环级联谐振腔,通过优化晶体长度提高光束交叠效率,获得高效率中红外激光输出。实验中使用两种掺杂浓度(原子数分数分别为25%和10%)的长度为2 mm Er∶YAG晶体作为增益介质,测得波长为2937 nm的中红外激光的输出斜效率分别为37.2%和36.5%,均突破了33.2%的Stokes极限。据我们所知,这是首次在室温下使用较低掺杂浓度(原子数分数为10%)的Er∶YAG晶体获得了超过Stokes极限的高效率3μm中红外激光输出。展开更多
With the increasing maritime activities,a great demand of wide-area maritime digital data services is needed.Therefore,Narrowband Internet of Things(NB-IoT)that can provide wide coverage has been expected as an applic...With the increasing maritime activities,a great demand of wide-area maritime digital data services is needed.Therefore,Narrowband Internet of Things(NB-IoT)that can provide wide coverage has been expected as an application for maritime communication networks(MCNS).In this paper,we aim to enhance the spectral efficiency in NB-IoT by reducing the cyclic prefix(CP)overhead in random access signal without causing interference.The key point of the proposed scheme is the symbols transmitted for multiple times repeatedly in NB-IoT.Specifically,all CP are removed and multi-path fading effect is eliminated by using a repeated symbol to cover the disturbed symbol to construct a circular convolution structure of the channel with the same effect as adding CP.In addition,a single-tap equalization is still appropriate.To validate the effectiveness of the proposed scheme,simulation results are carried out with respect to the bit error ratio(BER).展开更多
文摘目的探究绿原酸(chlorogenic acid,CGA)氧化形成的CGA醌与氨基酸侧链基团在不同pH条件下的反应效率,为CGA与蛋白质共价互作反应位点的调控提供理论依据。方法利用循环伏安法研究了酸性(pH 5.0)、中性(pH 7.0)和碱性(pH 8.0)条件下CGA与氨基酸侧链基团的反应效率,采用超高效液相色谱-四极杆飞行时间串联质谱法(ultra performance liquid chromatography-quadrupole time of flight-tandem mass spectrometry,UPLC-QTOF-MS/MS)对反应产物进行结构鉴定。结果在pH7.0、扫描速率10mV/s,0.20mmol/LCGA与10.00mmol/L封闭α-氨基的氨基酸的反应效率依次为Nα-乙酰-L-半胱氨酸(~100.00%)≈Nα-乙酰-L-色氨酸(~100.00%)>Nα-乙酰-L-酪氨酸(39.20%±2.19%)>Nα-乙酰-L-赖氨酸(10.25%±0.83%)>Nα-boc-L-组氨酸(~0.00%)≈Nα-乙酰-L-精氨酸(~0.00%);在其他反应条件相同的情况下,缩小扫描电压范围至-0.4~0.4V,CGA与Nα-乙酰-L-半胱氨酸、Nα-乙酰-L-色氨酸及Nα-乙酰-L-酪氨酸的共价互作效率分别为~100%、12.83%±1.16%及~0%;pH 7.0或8.0时,GCA与氨基酸残基的共价互作效率高于pH 5.0;CGA醌与Nα-乙酰-L-赖氨酸、Nα-乙酰-L-精氨酸的反应产物以氧化态的醌-氨基酸形式存在,而CGA醌与Nα-乙酰-L-半胱氨酸、Nα-boc-L-组氨酸、Nα-乙酰-L-色氨酸的反应产物以还原态的酚-氨基酸形式存在。结论CGA氧化形成的CGA醌可与蛋白质中半胱氨酸、色氨酸、赖氨酸、组氨酸及精氨酸残基发生反应,其中半胱氨酸残基是CGA醌与蛋白质共价互作的主要位点,可通过调整食品体系的pH和绿原酸醌浓度实现绿原酸-蛋白质共价互作位点的调控。
文摘报道了室温下基于循环级联的高效率Er∶YAG中红外脉冲激光器,采用循环级联谐振腔,通过优化晶体长度提高光束交叠效率,获得高效率中红外激光输出。实验中使用两种掺杂浓度(原子数分数分别为25%和10%)的长度为2 mm Er∶YAG晶体作为增益介质,测得波长为2937 nm的中红外激光的输出斜效率分别为37.2%和36.5%,均突破了33.2%的Stokes极限。据我们所知,这是首次在室温下使用较低掺杂浓度(原子数分数为10%)的Er∶YAG晶体获得了超过Stokes极限的高效率3μm中红外激光输出。
文摘With the increasing maritime activities,a great demand of wide-area maritime digital data services is needed.Therefore,Narrowband Internet of Things(NB-IoT)that can provide wide coverage has been expected as an application for maritime communication networks(MCNS).In this paper,we aim to enhance the spectral efficiency in NB-IoT by reducing the cyclic prefix(CP)overhead in random access signal without causing interference.The key point of the proposed scheme is the symbols transmitted for multiple times repeatedly in NB-IoT.Specifically,all CP are removed and multi-path fading effect is eliminated by using a repeated symbol to cover the disturbed symbol to construct a circular convolution structure of the channel with the same effect as adding CP.In addition,a single-tap equalization is still appropriate.To validate the effectiveness of the proposed scheme,simulation results are carried out with respect to the bit error ratio(BER).
