再论各向异性单轴晶体的布儒斯特角

从各向同性介质和各向异性单轴晶体界面间的菲涅耳公式出发,进一步研究了当自然光从各向同性介质射向各向异性且光轴任意取向的单轴晶体界面上时,其反射光成为垂直入射面的线偏振光时所对应的入射角,即布儒斯特角是否存在的问题,并对该问题进行了较全面的论述,计算了相应条件下的布儒斯特角和有关参量的数值,得到了正确的结论,同时也指出了某些文献在论述该问题时的不妥之处.     

头孢地嗪钠与牛血清白蛋白相互作用研究

用荧光光谱法研究水溶液中头孢地嗪钠(CDZM)与牛血清白蛋白(BSA)的结合反应, 测定了头孢地嗪钠与牛血清白蛋白的结合常数和结合位点数, 探讨了其荧光猝灭机制. 根据热力学参数确定了头孢地嗪钠与牛血清白蛋白之间的作用力类型, 运用Föster偶极-偶极非辐射能量转移原理, 测定了头孢地嗪钠与牛血清白蛋白相互结合时其授体-受体间的距离, 采用同步荧光技术考察了头孢地嗪钠对牛血清白蛋白构象的影响.     

Photochemically-induced crystallization of protein

I demonstrate photochemically induced crystallization of metastable hen egg-white lysozyme solution by weak UV irradiation for several tens seconds. The most effective irradiation time range is 10–60 s, and in this range the enzyme activity is maintained. Intermediates, neutral radicals at tryptophan residual produced by one-photon absorption, enhance nucleation. When the intermediate is selectively excited by visible light, the intermediate is denatured. At that time the light-induced nucleation is inhibited. This result indicates the intermediate induces nucleation. The radical forms lysozyme dimer that is detected by an SDS-PAGE electrophoresis experiment. An addition of polyethylene glycol (PEG) greatly enhances light-induced nucleation. PEG affects to shorten the intermediate radical lifetime, which suggests that PEG assists to form dimer. We consider that the photochemical dimer behaves as smallest cluster to grow critical nucleus. The smallest cluster formation is the rate determining step in classical nucleation theory due to surface energy disadvantage. The photochemical dimer is formed by a covalent bond, and the nucleation is initiated from stable dimer. The nucleation enhancement is reasonably explained. The present researches results point out the development of a new method for controlling nucleation and growth that could be applied for structural genomics and pharmaceutical industry for instance.     

Efficient catalytic aza-Michael additions of carbamates to enones: revisited dual activation of hard nucleophiles and soft electrophiles by InCl3/TMSCl catalyst system

The aza-Michael reaction of a variety of chalcones with weaker nucleophilic carbamates catalyzed by InCl₃ in the presence of TMSCl via the entry of dual activation of both hard nucleophiles (carbamates) and soft electrophiles (enones) to provide the corresponding adducts in good yields. The first example of enantioselective aza-Michael reaction of chalcones with carbamates was also investigated in the presence of the present catalyst system.     

Polyamide thin film composite membrane prepared from m-phenylenediamine and m-phenylenediamine-5-sulfonic acid

Thin film composite (TFC) membranes based polyamide were prepared with m-phenylenediamine (MPD), m-phenylenediamine-5-sulfonic acid (SMPD) and trimesoyl chloride (TMC) through interfacial polymerization technique on the polysulphone supporting film. The membranes were characterized using permeation experiments with salt water, attenuated total reflectance infrared (ATR-IR) and X-ray photoelectronic spectroscopy (XPS) as well as scanning electronic microscopy (SEM). This study has shown that the active layer of TFC membrane is aromatic polyamide, including sulfuric acid function group (-SO₃H) according to the result of ATR-IR and XPS. The NaCl rejection of RO membranes decreased and the flux increased when W_SMPD/W_MPD increased from 0 to 1, and the linear part with pendant -COOH in membrane barrier layer increased with the increase of SMPD content, but the surface of membrane becoming smoother and smoother with the increase of SMPD content. So the membranes performance mainly was determined by chemical structure in their barrier layer.     

Stability of neutral and charged Si50 cage and stacked structure and in comparison with Si60 structures

We have performed calculations on the fullerene cage and stacked structures of neutral and ionic Si₅₀ cluster by full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO-MD) method. It is found that the neutral and charged fullerene cages relax into distorted structures resembling puckered balls. Their electronic structures are remarkably similar besides their geometrical structures. However, the relaxed cages are still not so stable as the stacked structure built from tricapped trigonal prism. By comparison, for the fullerene cages and stacked structures of neutral and ionic Si₆₀ cluster, similar characteristics are found.     

高效液相色谱-电喷雾电离三级四极杆质谱检测动物源食品中氯霉素、甲砜霉素、氟苯尼考残留量

建立了动物源产品中氯霉素、甲砜霉素、氟苯尼考残留量的高效液相色谱-电喷雾电离三级四极杆质谱(LC-ESI-MS/MS)的方法。前处理方法包括添加同位素内标氯霉素-d5,碱化乙酸乙酯提取,C18小柱净化。该方法采用负离子,多反应监测氯霉素四对离子(321.0/151.9,321.0/256.6,321.0/194.2,321.0/175.4),甲砜霉素两对离子(354.1/185.0,354.1/290.0),氟苯尼考两对离子(356.0/335.9,356.0/185.1)和同位素内标氯霉素-d5(326.0/157.1)。该方法线性范围为0.1~1.6μg/kg;对不同基质样品的加标回收率为80%~112.5%;相对标准偏差小于11%;方法的测定低限为0.1μg/kg。     

Synthesis of new heterocyclic compounds having 1,2,3‐triazole and isoxazole rings in a single molecule

Five series of new heterocyclic compounds of 1,2,4‐triazole Mannich bases, 1,3,4‐oxadiazole Mannich bases, 1,3,4‐oxadiazolines, 1,2,4‐triazolo[3,4‐b]1,3,4‐thiadiazines and 1,2,4‐triazolo[3,4‐b]1,3,4‐thiadiazoles, in which 1,2,3‐triazolyl and isoxazolyl have been united, were synthesized from the intermediate of 5‐methyl‐3‐(2‐phenyl‐2H‐1,2,3‐triazol‐4‐yl)isoxazole‐4‐carbohydrazide, Their structures were established by spectroscopy.     

液相色谱-串联质谱法同时测定大黄鱼中20种磺胺类药物残留

建立了一种液相色谱-电喷雾串联质谱同时测定大黄鱼中20种磺胺类药物残留的方法.均质样品先后用乙腈、二氯甲烷提取,合并提取液,取部分提取液经氮吹浓缩.残渣用1 mL流动相溶解,饱和正己烷脱脂净化.采用ZORBAX Eclipse XDB-C8色谱柱,以含0.2%乙酸的水溶液和甲醇(7: 3)为流动相,梯度洗脱,在电喷雾-多反应监测离子模式下,进行定量定性分析.方法的定量限为5 μg/kg;以标准加入法计算回收率,在10～40 μg/kg添加范围内,平均回收率为79.6%～109%;相对标准偏差为3.55%～16.5%.     

[Ni(dien)2]2[Mn(NCS)6]·H2O的合成、晶体结构

The crystal of [Ni(dien)₂]₂[Mn(NCS)₆]·H₂O was synthesized and the structure of its single crystal was determined by X-ray diffraction. The crystal is monoclinic system, space group P2₁/c with a=16.544(3),b=15.137(2), c=17.334(3)?, β=99.90(1)°, V=4276.3(12)?³, Z=4, D_c=1.479g·cm^-3, M_r=951.55, F(000)=1998, μ=1.489mm^-1, R=0.0399, R_w=0.0958. IR was also determined.