Fiber Bragg grating hydrophone with high sensitivity

A fiber Bragg grating （FBG） hydrophone with high sensitivity was demonstrated. This hydrophone used a rubber diaphragm and a copper hard core as the sensing element. To compensate the hydrostatic pressure, a capillary tube was fixed at the end of the hydrophone. Theoretical analysis of the acoustic pressure sensitivity was given in this letter. Experiments were carried out to test the frequency response of the hydrophone. The result shows that when the Young＇s modulus of the diaphragm is higher, a flatter frequency response will be obtained.     

外电场辅助化学气相沉积方法制备网格状β-Ga2O3纳米线及其特性研究

利用外电场辅助化学气相沉积（CVD）方法,在蓝宝石衬底上制备出了由三组生长方向构成的网格状β-Ga₂O₃纳米线.研究了不同外加电压大小对β-Ga₂O₃纳米线表面形貌、晶体结构以及光学特性的影响.结果表明：外加电压的大小对样品的表面形貌有着非常大的影响,有外加电场作用时生长的β-Ga₂O₃纳米线取向性开始变好,只出现了由三组不同生长方向构成的网格状β-Ga₂O₃纳米线;并且随着外加电压的增加,纳米线分布变得更加密集、长度明显增长.此外,采用这种外电场辅助的CVD方法可以明显改善样品的结晶和光学质量.     

Characterization of relativistic electrons generated by a cone guiding laser pulse

We demonstrated the interaction of a gold cone target with a femto second(fs) laser pulse above the relativistic intensity of 1.37×10 18 μm 2 W/cm 2.Relativistic electrons with energy above 2 MeV were observed.A 25%-40% increase of the electron temperature is achieved compared to the case when a plane gold target is used.The electron temperature increase results from the guiding of the laser beam at the tip and the intense quasistatic magnetic field in the cone geometry.The behavior of the relativistic electrons is verified in our 2D-PIC simulations.     

北京谱仪中的μ计数器

描述了北京谱仪中μ子鉴别器的总体性能和安排,报道了μ计数器的气体放大特性、计数率坪特性、漂移时间、探测效率、电荷分配定位精度等一系列性能的测量结果.     

等差数列的前n项和(第一课时)

1　 创设情景 ,引入新课生活中的一个问题 :校园摆放花盆 :学校为美化校园 ,决定在道路旁摆放盆景 .从校门口取出花盆到距校门 1m处开始摆放 ,每隔 1m摆放一盆 ,学生小王每次拿 2盆 ,若要完成摆放 30盆的任务 ,最后返回校门处 ,问小王走过的总路程是多少 ?[情境学习理论认为 :数学学习总是与一定的知识背景 ,即“情境”相联系 .在实际情境下进行学习 ,可以使学生利用自己的原有认知结构中有关知识和经验“同化”和“索引”出当前要学习的新知识 ,促进对新知识的意义建构 .]尝试与感知1.1　画出示意图图 11.2　问题化归即求 4 8 12 … 6 0…     

超痕量铱的催化荧光分析新方法研究

在０．１ｍｏｌ／Ｌ Ｈ２ＳＯ４介质及加热条件下，超痕量Ｉｒ强烈催化ＫＩＯ４氧化罗丹明Ｂ生成一种绿色荧光产物，藉自来水冷却中止反应，研究了催化荧光法测定超痕量铱的影响因素，建立了一个检出限和测定范围分别为０．００５ｎｇ／ｍＬ和０．０１－２ｎｇ／ｍＬ铱的催化荧光分析新方法，并探讨了催化反应的机理。     

超高效液相色谱-串联质谱法分析贝母药材中5种生物碱

建立了贝母药材中贝母辛、西贝母碱、贝母素乙、贝母素甲和西贝母碱苷的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。样品经碱化甲醇-三氯甲烷提取,用Acquity UPLC BEH C_(18)色谱柱分离,乙腈-0.1%甲酸溶液为流动相梯度洗脱,多反应监测(MRM)模式检测,外标法定量。结果表明,5种生物碱在0.000 5～0.05 mg/L范围内线性良好(r0.999),在1.0、2.5、5.0 mg/kg加标水平下,回收率为78.6%～93.1%,相对标准偏差不大于8.6%。5种生物碱的检出限(LOD)为0.03 mg/kg,定量下限(LOQ)为0.1 mg/kg。该方法操作简便,灵敏度高,准确可靠,适用于贝母中上述5种生物碱的同时测定。     

室温固相反应制备Keggin结构K_3PW_(12)O_(40)·10H_2O纳米粒子

采用室温固相反应制备 Keggin结构钨磷酸钾纳米粒子 ,并通过元素分析、红外光谱、X射线衍射、电镜等进行了表征     

Status of CSNS H- ion source

A new H^- ion source has been installed successfully and will be used to serve the China Spallation Neutron Source (CSNS). In this paper, we report various components of the ion source, including the discharge chamber, temperature, cooling system, extraction electrodes, analyzing magnet, remote control system and so on. Compared to the previous experimental ion source, some improvements have been made to make the ion source more compact and convenient. In the present arrangement, the Penning field is generated by a pair of pole tip extensions on the 90° analyzing magnet instead of by a separate circuit. For the remote control system, F3RP61-2L is applied to the accelerator online control system for the first time. In the running of the ion source, a stable pulse H^- beam with a current of 50 mA at an energy of 50 keV is produced. The extraction frequency and pulse width is 25 Hz and 500 μs, respectively. Furthermore, an emittance scanner has been installed and measurements are in progress.     

Quantum path control using attosecond pulse trains via UV-assisted resonance enhance ionization

We theoretically investigate the quantum path selection in an ultraviolet(UV)-assisted near-infrared field with an UV energy below the ionization threshold. By calculating the ionization probability with different assistant UV frequencies, we find that a resonance-enhanced ionization peak emerges in the region Euv < Ip, where Euv is the photon energy and Ip is the ionization energy. With an attosecond pulse train(APT) centered in the resonance region, we show that the short quantum path can be well selected in the continuum case. By performing the electron trajectory analysis, we have further explained the physical mechanism of the quantum path selection. Moreover, we also demonstrate that in the resonance region, the harmonic emission from the selected paths is more efficient than that with the APT energy above the ionization threshold.