0.35μm激光与金靶耦合发射X光能谱分析

 利用改进后的More模型计算Au等离子体各电离度离子的Einstein系数和线发射强度。在0.35μm激光与金平面靶耦合产生晕区等离子体条件下,求解离子模型定态速率方程组得到离子布居概率,从而求出X光线发射能谱。将此能谱与JB19程序计算得到的出系统外边界光子能谱进行了比较。     

Raman scattering by hot polaritons in NaClO3

Summary By nonlinear mixing of IR and visible radiation,i.e. coherent Raman scattering by polaritons driven by a CO₂ laser, it has been possible to get high-resolution spectra for theF-modes of a NaClO₃ crystal in the region (907÷957) cm⁻¹, where several isotopic modes are present. The obtained independent measurement of the refractive index and absorbance allows an accurate determination of the polariton dispersion curve and its width inq-space. The experimental data confirm the existence of a localized isotopic mode at 931 cm⁻¹ and a strongly damped isotopic mode near 960 cm⁻¹. Finally, an accurate measurement of the dispersion of the second-order nonlinear polarizability in the same energy region has been obtained for the first time. This work was supported by the Italian Consiglio Nazionale delle Ricerche and Ministero della Pubblica Istruzione.     

Raman spectra of crystalline iron perchlorate hexahydrate

Raman studies of crystalline iron perchlorate hexahydrate (Fe(ClO₄)₂·6H₂O) in the region of lattice and anion internal modes were carried out in the temperature range 80–385 K. The temperature‐dependent Raman results are consistent with those from previous works, showing that two phase transitions occur around 336 and 245 K. The transition at 336 K may be considered as an order–disorder transformation, while the one at 245 K is associated with the configurational disorder of the tetrahedron of the perchlorate ions. Copyright © 2008 John Wiley & Sons, Ltd.     

荧光材料Y_2O_3:Eu变温拉曼光谱分析

本文用显微拉曼谱仪在波长为785 nm的激光激发下,对Y2O3:Eu陶瓷在温度83-473 K间进行了系统的变温拉曼实验研究。实验发现Y2O3:Eu的一些振动模在低温下没有出现,只有当温度达到一定值之后才可以被观察到,分析表明这是由于温度变化引起的简并振动模式分裂。此外,Y2O3:Eu的拉曼峰位、半高全峰宽(FWHM)也是温度的非线性函数,且不同的拉曼峰遵循不同的函数关系,本文分析这是由于晶格的各向异性导致的。     

Fine-structure energy levels, oscillator strengths and lifetimes in Co XV

Excitation energies from ground state for 97 fine-structure levels as well as oscillator strengths and radiative decay rates for all electric-dipole-allowed and intercombination transitions among the fine-structure levels of the terms belonging to the (1s ²2s ²2p ⁶)3s ²3p, 3s ³ p ², 3s ²3d, 3p ³, 3s3p3d, 3p ²3d, 3s3d ², 3s ²4s, 3s ²4p, 3s ²4d, 3s ²4f, and 3s3p4s configurations of Co XV are calculated, using extensive configuration-interaction (CI) wave functions, obtained with the CIV3 computer code of Hibbert. The important relativistic effects in intermediate coupling are included through the Breit-Pauli approximation via spin-orbit, spin-other-orbit, spin-spin, Darwin and mass correction terms. Small adjustments to the diagonal elements of the Hamiltonian matrices have been made. Our calculated excitation energies, including their ordering, are in excellent agreement with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology (NIST) wherever available. The mixing among several fine-structure levels is found to be very strong, with most of the strongly mixed levels belonging to the (1s ²2s ²2p ⁶)3p ²3d and 3s3d ² configurations. The strong mixing among several fine-structure levels makes it very difficult to identify them uniquely. Perhaps, that may be the reason for the lack of both experimental and theoretical results for these levels. We believe that our extensive calculated values can guide experimentalists in identifying the fine-structure levels in their future work. From our radiative decay rates we have also calculated radiative lifetimes of some fine-structure levels. In this calculation we also predict new data for several fine-structure levels where no other theoretical and/or experimental results are available.     

Spectral luminescence properties of hydroporphyrazine metallo complexes

We have studied the spectral luminescence properties of a zinc complex of dibenzobarreleno-substituted tetraazaisobacteriochlorin (a synthetic tetrapyrrole pigment which is the structural analog of the biologically important chromophore isobacteriochlorin) and a palladium complex of dibenzobarreleno-substituted tetraazachlorin. We have shown that despite the substantial effect of aza-substitution on the electronic structure and the electronic spectra of the tetrapyrrole molecules, the effect of hydrogenation of adjacent pyrrole rings on the spectral luminescence properties is similar in compounds with nitrogen and carbon bridges. As in the free base case, the fluorescence of the studied zinc complex is strongly quenched at 293 K but flares up at 77 K (temperature and viscosity-dependent quenching). To study the substituted Zn-tetraazaisobacteriochlorin, we determined the position of the 0-0 band of the low-intensity transition S₀ → S₂ and showed that the S₂ → S₁ energy difference increases with bridge aza substitution. For the Pd complex of dibenzobarreleno-substituted tetraazachlorin, we could not detect phosphorescence in the near IR region (to 1150 nm); we detected weak fluorescence. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 700–707, September–October, 2008.     

Chemical modification of poly(lactic acid) induced by thermal decomposition of N‐acetoxy‐phthalimide during extrusion

Chemical modification of poly(lactic acid) (PLA) with N‐acetoxy‐phthalimide (NAPI) was performed in the melt by reactive extrusion, without using any peroxide initiator. The aminyl and nitroxide radicals produced from the NAPI thermal degradation, were, respectively, used (a) to create PLA macroradicals, and (b) to functionalize the PLA samples through nitroxide radical coupling. Depending on the extrusion temperature and the initial NAPI concentration, grafting rates up to 0.24 mol % were measured, modifying the PLA optical properties. This study represents an original new way of modification of PLA without the use of conventional peroxide initiators. Indeed, the undesirable side reactions (PLA branching or crosslinking) usually observed when using peroxides to initiate the radical grafting of PLA were avoided when using NAPI. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 120–129     

Dextramabs: A Novel Format of Antibody-Drug Conjugates Featuring a Multivalent Polysaccharide Scaffold

Antibody-drug conjugates (ADCs) are multicomponent biomolecules that have emerged as a powerful tool for targeted tumor therapy. Combining specific binding of an immunoglobulin with toxic properties of a payload, they however often suffer from poor hydrophilicity when loaded with a high amount of toxins. To address these issues simultaneously, we developed dextramabs, a novel class of hybrid antibody-drug conjugates. In these architectures, the therapeutic antibody trastuzumab is equipped with a multivalent dextran polysaccharide that enables efficient loading with a potent toxin in a controllable fashion. Our modular chemoenzymatic approach provides an access to synthetic dextramabs bearing monomethyl auristatin as releasable cytotoxic cargo. They possess high drug-to-antibody ratios, remarkable hydrophilicity, and high toxicity in vitro.     

LiB6Si: An indirect band gap semiconductor

Using first-principle calculations, mechanical properties, electronic structure, and Raman spectra of LiB₆Si structure were investigated. The band structures calculated by GGA-PBE and HSE06 methods reveal that LiB₆Si is an indirect band gap semiconductor. The band gap estimated by HSE06 method is about 2.24 eV, which is in good agreement with that of experimental value 2.27 eV. The calculated tensile stress-strain curves of LiB₆Si reveal that [010] direction is the cleavage direction under tensile strains. The calculated Raman spectra of LiB₆Si are also in good agreement with that of measured. The position of the band gap may provide a basis for further photocatalysis research on LiB₆Si.     

Synthesis of Polymers Containing Potassium Acyltrifluoroborates (KATs) and Post-polymerization Ligation and Conjugation

We report the synthesis of monomers for atom-transfer radical polymerization (ATRP) and a reversible addition-fragmentation chain transfer (RAFT) agent bearing trifluoroborate iminiums (TIMs), which are quantitatively converted into potassium acyltrifluoroborates (KATs) after polymerization. The resulting KAT-containing polymers are suitable for rapid amide-forming ligations for both post-polymerization modification and polymer conjugation. The polymer conjugation occurs rapidly, even under dilute (micromolar) aqueous conditions at ambient temperatures, thereby enabling the synthesis of a variety of linear and star-shaped block copolymers. In addition, we applied post-polymerization modification to the covalent linking of a photocaged cyclic antibiotic (gramicidin S) to the side chains of the KAT-containing copolymer. Cellular assays revealed that the polymer–antibiotic conjugate is biocompatible and provides efficient light-controlled release of the antibiotic on demand.