2-μm singly resonant optical parameter oscillator

We experimentally realize a singly resonant optical parameter oscillator （OPO） which operates at the degenerate point of KTiOPOa （KTP） crystal. A thin film plate polarizer （TFP） is used as the output coupler to obtain linearly polarized 2.12 μm laser. A maximum output power of 2.2 W at 2.12 μm is obtained from a near-degenerate, type-II KTP OPO by utilizing a Q-switched diode-pumped Nd：YAG laser operating at 5 kHz.     

Design of the low energy beam transport line for the China spallation neutron source

The design of the China Spallation Neutron Source (CSNS) low-energy beam transport (LEBT) line, which locates between the ion source and the radio-frequency quadrupole (RFQ), has been completed with the TRACE3D code. The design aims at perfect matching, primary chopping, a small emittance growth and sufficient space for beam diagnostics. The line consists of three solenoids, three vacuum chambers, two steering magnets and a pre-chopper. The total length of LEBT is about 1.74m. This LEBT is designed to transfer 20mA of H-pulsed beam from the ion source to the RFQ. An induction cavity is adopted as the pre-chopper. The electrostatic octupole steerer is discussed as a candidate. A four-quadrant aperture for beam scraping and beam position monitoring is designed.     

Design of magnet and control of the beam emittance for Penning H－ ion source

The design requirement and principle of the deflection magnet for Magnetron and Penning H^－ ion source are discussed. It is proved that there exists a maximum emittance for the beam that may be transformed by the magnet into a state with equal Twiss parameters of α_r=α_y and β_r=β_y, which is the requisite condition to get a minimum emittance at the entrance of RFQ after transporting by a LEBT with solenoids. For this maximum emittance, the corresponding magnetic field gradient index is 1.     

A Continuous-Wave Diode-Side-Pumped Tm:YAG Laser with Output 51W

A compact diode-side-pumped Tm：YAG laser is presented, which can output 51 W of cw power at 2.02 μm. The Tm：YAG rod is side pumped by nine diode arrays with the central wavelength of 783nm and the with bandwidth of about 2.5 nm at 25^o C. To decrease the thermal effect on the both ends and dissipate the heat effectively, one composite Tm：YAG rod with the undoped YAG end caps and the screw threads on the side surface of the rod is used as the laser crystal. The maximum optical-to-optical conversion efficiency of the 2.02-μm laser output is 14.2%, with a slope effciency of 26.8%     

Standing Rankine-Hugoniot Shocks in Black Hole Accretion Discs

We study the problem of standing shocks in viscous disc-like accretion flows around black holes. For the first time we parametrize such a flow with two physical constants, namely the specific angular momentum accreted by the black hole j and the energy quantity K. By providing the global dependence of shock formation in the j- K parameter space, we show that a significant parameter region can ensure solutions with Rankine-Hugoniot shocks; and that the possibilities of shock formation are the largest for inviscid flows, decreasing with increasing viscosity, and ceasing to exist for a strong enough viscosity. Our results support the view that the standing shock is an essential ingredient in black hole accretion discs and is a general phenomenon in astrophysics, and that there should be a continuous change from the properties of inviscid flows to those of viscous ones.     

铱（Ⅰ）苯乙胺Schiff碱络合物催化苯乙酮的不对称氢转移反应

以光学活性的苯乙胺和吡啶－２－甲醛缩合而得到的Ｓｃｈｉｆｆ碱（ＰＰＥＩ）（ＰＰＥＩ＝２－「「Ｎ－（１－ｐｈｅｎｙｌｅｔｈｙ）ｉｍｉｎｏ」ｍｅｔｈｙｌ「ｐｙｒｉｄｉｎｅ中２－「「Ｎ－（１－苯乙基）亚胺」甲基「吡啶）为配体，进而与（Ｉｒ（ＣＯＤ）Ｃｌ」２（ＣＯＤ＝１，５环辛二烯）反应，合成了８个光学活性铱铬络合物，考察了它们在异丙醇存在下催化苯乙酮不对称氢转移反应的光学活性，发现「Ｉｒ（ＣＯＤ）（ＰＰ     

萃取-催化电势动力学法测定生物样品中痕量钼的研究

选H_2O_2-KI作为指示反应体系,以碘离子选择电极作跟踪体系电位变化的监测器,通过系统性实验,建立了生物样品中痕量钼的催化电势动力学分析法。该法可对试液中5×10~(-8)M以上,宽达3个数量级的Mo(Ⅵ)进行测定。对于生物样品中共存离子的干扰,采用萃取一掩蔽法排除。以乙酸乙酯代替惯用的毒性溶剂氯仿,取得满意的效果,对鳗饵及人发进行了实际分析及标准回收实验,回收率93.3～110.0%(n=2-3),相对平均偏差≤4.8%。     

铱(I)苯乙胺Schiff碱络合物催化苯乙酮的不对称氢转移反应

以光学活性的苯乙胺和吡啶－２－甲醛缩合而得到的Ｓｃｈｉｆ碱（ＰＰＥＩ）（ＰＰＥＩ＝２－［［Ｎ－（１－ｐｈｅｎｙｌｅｔｈｙｌ）ｉｍｉｎｏ］ｍｅｔｈｙｌ］ｐｙｒｉｄｉｎｅ或２－［［Ｎ－（１－苯乙基）亚胺］甲基］吡啶）为配体，进而与［Ｉｒ（ＣＯＤ）Ｃｌ］２（ＣＯＤ＝１，５－环辛二烯）反应，合成了８个光学活性铱络合物，考察了它们在异丙醇存在下催化苯乙酮不对称氢转移反应的光学活性，发现［Ｉｒ（ＣＯＤ）（ＰＰＥＩ）Ｉ］具有较好的立体选择性．其光学产率最高可达３５．７％ｅ．ｅ．．     

中國古代數學家關於圓周率研究的成就

此篇所述,除前三段及笔四段前半大致舆錢寶琮先生“中國古代算書中之圓周率研究”(載在“科學”第八卷笔二期,1923)類似外,第四段後半對於密率所提的意見。縱非“定論”,足資參考;第五段所談,雖舆鳋寶琮先生的見解(見前篇)不同,也一併刊出,希望大家研討。