A Trigonal‐Pyramidal Erbium(III) Single‐Molecule Magnet

Given the recent advent of mononuclear single‐molecule magnets (SMMs), a rational approach based on lanthanides with axially elongated f‐electron charge cloud (prolate) has only recently received attention. We report herein a new SMM, [Li(THF)₄[Er{N(SiMe₃)₂}₃Cl]?2 THF, which exhibits slow relaxation of the magnetization under zero dc field with an effective barrier to the reversal of magnetization (ΔE_eff/k_B=63.3 K) and magnetic hysteresis up to 3 K at a magnetic field sweep rate of 34.6 Oe s^?1. This work questions the theory that oblate or prolate lanthanides must be stabilized with the appropriate ligand framework in order for SMM behavior to be favored.     

Rare-Earth Single Erbium Atoms for Enhanced Photocatalytic CO2 Reduction

The solar-driven photocatalytic reduction of CO₂ (CO₂RR) into chemical fuels is a promising route to enrich energy supplies and mitigate CO₂ emissions. However, low catalytic efficiency and poor selectivity, especially in a pure-water system, hinder the development of photocatalytic CO₂RR owing to the lack of effective catalysts. Herein, we report a novel atom-confinement and coordination (ACC) strategy to achieve the synthesis of rare-earth single erbium (Er) atoms supported on carbon nitride nanotubes (Er₁/CN-NT) with a tunable dispersion density of single atoms. Er₁/CN-NT is a highly efficient and robust photocatalyst that exhibits outstanding CO₂RR performance in a pure-water system. Experimental results and density functional theory calculations reveal the crucial role of single Er atoms in promoting photocatalytic CO₂RR.     

高能质子源靶用氢化铒薄膜制备过程影响因素

 采用两步法制备了高能质子源靶用氢化铒薄膜。并研究了氢化时间、氢化速度等因素对氢化铒薄膜质量的影响。XRD结果显示,只有氢化时间超过24 h才能获得较纯净的氢化铒薄膜。将氢化反应温度和氢气压力控制在适当范围内,使得铒薄膜缓慢被氢化并使得氢化过程所产生的应力缓慢释放,可获得较完整的氢化铒薄膜。所获得的5~15 μm氢化铒薄膜已经应用于高能质子束的产生实验,取得了良好的实验结果。     

香豆素-3-羧酸铒（Ⅲ）一维配位聚合物[Er（CCA）_3（H_2O）_2]_n·2nH_2O的溶剂热法合成、晶体结构及与牛血清白蛋白（BSA）的相互作用

利用溶剂热法合成了一维配位聚合物[Er（CCA）3（H2O）2]n·2nH2O（HCCA=香豆素-3-羧酸）,通过元素分析和IR对配合物进行了表征,用X-射线单晶衍射技术测定了其晶体结构.标题配合物晶体属于单斜晶系,P21/c空间群：a=0.6310（1）nm,b=1.4165（2）nm,c=3.1731（3）nm;β...     

Ultraviolet resonance Raman spectroscopy of locked single‐stranded oligo(dA) reveals conformational implications of the locked ribose in LNA

We report here the first UV resonance Raman spectroscopic (UVRRS) study on locked nucleic acid (LNA) oligomers. Locking a base in nucleic acid (NA) oligomers produces a conformational change in the glycosyl bond between backbone and base. We present evidence of this change in LNAs when compared to their natural analogs using UVRRS. Wavenumber downshifts and peak amplitude increases, especially of the ∼1481 cm⁻¹ peak that is a spectral marker for part of the glycosyl bond, correlate with the fraction of locked bases when single‐stranded oligomers incorporating up to three locked bases were examined. By varying the position of the locked base within a fixed length sequence, we conclude that one, or at most two bases, on either side of the lock is affected. We further conclude from these data, and previously published reports, that the conformation of LNA is determined by imidazole–imidazole and pyrimidine–pyrimidine repulsion and imidazole–pyrimidine attraction in contrast to dispersion attraction‐dependent aggregation in the B conformation of DNA. Copyright © 2009 John Wiley & Sons, Ltd.     

Tunable dual wavelength fiber laser incorporating AWG and optical channel selector by controlling the cavity loss

In this paper, we propose and demonstrated a dual wavelength fiber laser (DWFL) based on the use of an erbium doped fiber (EDF) gain medium as well as an 1 × 24 Arrayed Waveguide Grating (AWG) together with two optical channel selectors (OCS) to provide channel spacing tunability. The output power of the two wavelengths is equalized by controlling the cavity loss in the DWFL using two Programmable Optical Attenuators (POAs). The widest spacing obtained from the DWFL is 18.13 nm while the narrowest spacing is 0.8 nm. The DWFL has good stability with only minor power fluctuations of less than 1.5 dB and a Side Mode Suppression Ratio (SMSR) of approximately 69.1 dB with peak fluctuations of less than 2.3 dB.     

Molecular structure of ErCl<Subscript>3</Subscript> and YbCl<Subscript>3</Subscript> according to the data of the simultaneous electron diffraction and mass spectrometric experiment

The saturated vapors of ErCl₃ and YbCl₃ were studied in a simultaneous electron diffraction and mass spectrometric experiment at 1165 K and 1170 K, respectively. In the vapors of these compounds, we found up to 3 mol.% dimers along with the monomers. The parameters of the r _g effective configuration of the monomer molecules were determined. For ErCl₃ and YbCl₃, the internuclear distances r _g(Ln-Cl) were 2.436(5) Å and 2.416(5) Å, and the bond angles ∠_g(Cl-Ln-Cl) were 117.0(10)° and 117.2(10)°, respectively. The equilibrium configurations and vibration frequencies of the monomer and dimer molecules were calculated by the HF, B3LYP, and MP2 methods using the combination of the ECP_D energy-consistent quasirelativistic core potential, including 4f electrons [Kr4d ¹⁰4f ⁿ ], and the contracted [5s4p3d] valence basis set for Er and Yb atoms and the MIDIX [4s3p1d] basis set for Cl atoms. The parameters of the effective r _g configuration of the monomer molecules corresponding to the temperature of the experiment were calculated. The difference between the calculated equilibrium r _e(Ln-Cl) and temperature-averaged r _g(Ln-Cl) distances was found to be 0.001–0.002 Å and did not exceed the error of the r _g(Ln-Cl) parameter determined in the electron diffraction experiment. The experimental parameters of the r _g structure were shown to be consistent with the idea about the planar equilibrium geometrical configuration of ErCl₃ and YbCl₃ molecules.     

Comparison of the fragmentation behavior of DNA and LNA single strands and duplexes

DNA and locked nucleic acid (LNA) were characterized as single strands, as well as double stranded DNA‐DNA duplexes and DNA‐LNA hybrids using tandem mass spectrometry with collision‐induced dissociation. Additionally, ion mobility spectrometry was carried out on selected species. Oligonucleotide duplexes of different sequences — bearing mismatch positions and abasic sites of complementary DNA 15‐mers — were investigated to unravel general trends in their stability in the gas phase. Single‐stranded LNA oligonucleotides were also investigated with respect to their gas phase behavior and fragmentation upon collision‐induced dissociation. In contrast to the collision‐induced dissociation of DNA, almost no base loss was observed for LNAs. Here, backbone cleavages were the dominant dissociation pathways. This finding was further underlined by the need for higher activation energies. Base losses from the LNA strand were also absent in fragmentation experiments of the investigated DNA‐LNA hybrid duplexes. While DNA‐DNA duplexes dissociated easily into single stranded fragments, the high stability of DNA‐LNA hybrids resulted in predominant fragmentation of the DNA part rather than the LNA, while base losses were only observed from the DNA single strand of the hybrid.     

脉冲发电机电源宽频变化情况下锁相技术仿真

针对在基波频率变化情况下传统锁相环无法进行正确锁相的问题,提出了基于同步参考坐标系的追踪型三相软件锁相环。三相电压信号(V_a、V_b、V_c)经同步坐标变换后,得到两相静止坐标(V_α、V_β)信号,再经过旋转坐标变化后获得(V_d、V_q)信号;V_q信号经过低通滤波后,进行动态信号延迟,其延迟的时间由输出的频率信号获得;把延迟前后的信号做差,经过PID调节后输出为角频率,对角频率积分后获得稳定基波正序相位。为了验证该算法,基于matlab建立了仿真模型。仿真结果表明,该锁相环在电源基波频率线性变化情况下其相移时间小于0.2ms,在脉冲发电机电压基波频率非线性变化情况下需要经过一个周波也能获得精准地锁相,其运用于有源电力滤波器有效地抑制了脉冲发电机的输出谐波。     

基于高精细度光腔锁频激光的分子吸收光谱测量

利用高精细度光腔锁定激光频率,实现了对分子吸收光谱的高精度测量.光腔采用低热膨胀系数的殷钢结构设计和温度控制,实现了腔长度的稳定;通过将激光频率锁定在光腔纵模上,实现了高频率精度和高灵敏度的光腔衰荡光谱测量.利用该装置示范性地测量了二氧化碳分子在6470.42 cm~(-1)附近的光腔衰荡光谱和色散光谱,得到了高精度的谱线参数,并和数据库谱线参数进行了对比.