Zero-Semidistributive Inverse Semigroups

An inverse semigroup S is said to be 0-semidistributive if its lattice ?F (S) of full inverse subsemigroups is 0-semidistributive. We show that it is sufficient to study simple inverse semigroups which are not groups. Our main theorem states that such a simple inverse semigroup S is 0-semidistributive if and only if (1) S is E-unitary, (2) S is aperiodic, (3) for any a,b ∈ S/σ with ab ≠ 1, there exist nonzero integers n and m such that (ab) ^m  = a ⁿ or (ab) ^m  = b ⁿ , where σ is the minimum group congruence on S.     

On Complete Lie Algebras

In this article, the author gives two methods to construct complete Lie algebras. Both methods show that the derivation algebras of some Lie algebras are complete.     

Iterative Multireference Configuration Interaction

Iterative multireference configuration interaction (IMRCI) is proposed. It is exploited to compute the electronic energies of H\begin{document}$_2$\end{document}O and CH\begin{document}$_2$\end{document} (singlet and triplet states) at equilibrium and non-equilibrium geometries. The potential energy curves of H\begin{document}$_2$\end{document}O, CH\begin{document}$_2$\end{document} (singlet and triplet states) and N\begin{document}$_2$\end{document} have also been calculated with IMRCI as well as the M?ller Plesset perturbation theory (MP2, MP3, and MP4), the coupled cluster method with single and double substitutions (CCSD), and CCSD with perturbative triples correction (CCSD(T)). These calculations demonstrate that IMRCI results are independent of the initial guess of configuration functions in the reference space and converge quickly to the results of the full configuration interaction. The IMRCI errors relative to the full configuration interaction results are at the order of magnitude of 10\begin{document}$^{-5}$\end{document} hartree within just 2-4 iterations. Further, IMRCI provides an efficient way to find on the potential energy surface the leading electron configurations which, as correct reference states, will be very helpful for the single-reference and multireference theoretical models to obtain accurate results.     

Oxidation-Reduction Molecular Junction Covalent Organic Frameworks for Full Reaction Photosynthesis of H2O2

The full reaction photosynthesis of H₂O₂ that can combine water-oxidation and oxygen-reduction without sacrificial agents is highly demanded to maximize the light-utilization and overcome the complex reaction-process of anthraquinone-oxidation. Here, a kind of oxidation-reduction molecular junction covalent-organic-framework (TTF-BT-COF) has been synthesized through the covalent-coupling of tetrathiafulvalene (photo-oxidation site) and benzothiazole (photo-reduction site), which presents visible-light-adsorption region, effective electron-hole separation-efficiency and photo-redox sites that enables full reaction generation of H₂O₂. Specifically, a record-high yield (TTF-BT-COF, ≈276 000 μM h⁻¹ g⁻¹) for H₂O₂ photosynthesis without sacrificial agents has been achieved among porous crystalline photocatalysts. This is the first work that can design oxidation-reduction molecular junction COFs for full reaction photosynthesis of H₂O₂, which might extend the scope of COFs in H₂O₂ production.     

New experimental evidence of the structural modification in single crystal Bi2Sr2CaCu2Oy by X-ray diffraction observation

The variations of the high angle 00 peak-shape by means of X-ray l scans of the 00l fundamental reflections were investigated in detail for a highly oriented Bi₂Sr₂CaCu₂O_y (Bi2212) crystal with sufficiently small intrinsic mosaicity and the same crystal annealed in air at 250, 300, 400, 600, and 750°C for 20 h in consequence. For the first time, we observed a new additional reflection almost overlapped original 00l fundamental reflection at annealing temperature below 400°C by X-ray diffraction measurement, which shows that there coexisted two sets of lattice periodicity in the c-direction of the annealed crystal. The new additional reflection appeared at 250°C and disappeared at 400°C. Its intensity was increased at 300°C. The measurements of the AC susceptibility, c-axis parameter and full width at half maximum (FWHM) of the 00 peaks showed that the new additional reflection was associated with the oxygen diffusion in CuO₂ planes and the changes of strain field. The results provide the new experimental evidence that the structural distortion is more sensitive to the oxygen diffusion in CuO₂ planes than to that in Bi–O layers.     

(s)-多沙唑嗪的核磁共振理论和实验研究

报道了(s)-多沙唑嗪的1H、13C、DEPT、1H-1H COSY等的NMR波谱数据, 并对1H、13C NMR信号进行了指认. (s)-多沙唑嗪分子中含有9个季碳原子, 其中绝大部分通过常规实验的方法难以指认. 应用量子化学规范不变原子轨道(GIAO)的Becke-3-Lee-Yang-Parr(B3LYP)和Hartree-Fock(HF)方法, 分别在6-21G基组下计算了标题化合物的13C NMR化学位移值. 计算结果表明, 理论计算数据与实验结果吻合较好, 可以帮助对(s)-多沙唑嗪季碳原子NMR位移信号进行指认.     

Prediction of hydrodynamic performance of an FLNG system in side-by-side offloading operation

Floating liquefied natural gas (FLNG) is a type of liquefied natural gas (LNG) production system that shows prospects in exploitation of stranded offshore gas fields. The dynamic performance of an FLNG system in side-by-side configuration with a LNG carrier under the combined actions of wave, current and wind can be quite complex. This paper presents a comprehensive study on the hydrodynamics of an FLNG system with a focus on the nonlinear coupling effects of vessels and connection systems based on the concept FLNG prototype recently designed for South China Sea. In this study, the hydrodynamic characteristics of the two floating vessels connected through hawsers and fenders are investigated using a state-of-the-art time-domain simulation code SIMO, considering their mechanical and hydrodynamic coupling effects. The simulation model consisting of FLNG and LNG carrier is developed and calibrated by a series of model tests including a tuned damping and viscous levels. The hydrodynamic performances of the two floating vessels under an extreme sea state during side-by-side offloading operation are obtained, and their relative motions and the force responses of the connection hawsers and fenders are analyzed. Sensitivity studies are conducted to clarify contributions from the pretension and the stiffness of the connection hawsers. The effects on the hydrodynamic performance of the vessels and on the loads of the connection system are also investigated.     

Zeolitic imidazolate framework-67 (ZIF-67) rhombic dodecahedrons as full-spectrum light harvesting photocatalyst for environmental remediation

The inferior utilization efficiency of light is the main obstacle to the practical application of traditional photocatalysts such as TiO₂ and ZnO. In this regard, the development of novel photocatalysts with the capability of harvesting full spectrum light (from ultraviolet (UV) to near-infrared (NIR)) energy is a promising solution for solar energy conversion and environmental remediation. Here, we report the discovery of a single material that can harvest UV, visible (VIS), and NIR radiations to decompose heavy metal contaminants in aqueous solution. Zeolitic imidazolate framework-67 (ZIF-67) rhombic dodecahedrons were synthesized through a facile solution approach and employed in the reduction of Cr(VI) under UV−VIS−NIR pulsed laser irradiation, which was generated from the fundamental, second and third harmonics of Nd:YAG laser, respectively. The nanostructures showed efficient Cr(VI) reduction under UV, VIS and NIR laser irradiation and the measured reduction efficiency (%) was 71.22%, 69.52%, and 40.79%, respectively after 120 min. A possible explanation for the photocatalytic activity in Cr(VI) reduction was proposed. This is the first study of its kind where pulsed laser and ZIF-67 rhombic dodecahedrons capable of harvesting full spectrum light energy have been employed for the removal of Cr(VI) from water. The extraordinary capacity of harvesting full-spectrum light and long-term stability make ZIF-67 a potential photocatalyst for environmental remediation.     

超声全矩阵数据联合稀疏重构的多测量向量模型应用

针对单测量向量模型(Single Measurement Vector,SMV)等传统压缩感知方法处理超声全矩阵数据时,存在重构精度低和重构耗时长等问题,本文研究了多测量向量模型(Multiple Measurement Vectors,MMV)应用的可行性。针对铝合金试块中不同深度的φ2 mm横通孔,分别使用MMV模型中的多测量稀疏贝叶斯(Multiple Sparse Bayesian Learning,MSBL)算法和SMV模型中的稀疏贝叶斯(Sparse Bayesian Learning,SBL)算法进行超声全矩阵数据重构,并实施全聚焦成像。随后,引入归一化均方误差和阵列性能因子评价图像和信号的重构效果。实验结果表明,SBL算法在25%采样率时的归一化均方误差为1.9%,而MSBL算法仅需15%采样率即可达到相似效果且耗时更少。     

Separation of diisopropylnaphthalene isomers

The separation of diisopropylnaphthalenes was reinvestigated. The application of GC × GC appears to be a clear and necessary improvement over the use of single column techniques, with a polar (CP-Wax-52) column as reference technique, and a non-polar (CP-Sil-8) column as an alternative. Both qualitative and quantitative separations of DIPN isomers showed to be superior on GC × GC. The composition of both a DIPN mixture resulting from a typical experiment with a zeolite catalyst and a commercial one could be quantitatively determined in this way.