固相萃取-气相色谱-质谱法测定木制家具中氯酚类及菊酯类防腐剂

建立了固相萃取-气相色谱-质谱(SPE-GC-MS)检测含氯酚类化合物(2,4-二氯苯酚、2,4,6-三氯苯酚、2,4,5-三氯苯酚、2,3,4,6-四氯苯酚、五氯苯酚、林丹)和菊酯类化合物(氯菊酯、氟氯氰菊酯、氯氰菊酯、溴氰菊酯)等10种木材防腐剂的方法。对家具样品采用超声萃取法、以甲醇为提取剂在室温下反复提取2次,提取液经浓缩后,加入碳酸钾和乙酰酐衍生化,将衍生化后的溶液通过Oasis HLB固相萃取柱净化,用乙酸乙酯洗脱并收集检测。采用该方法实现了家具中10种木材防腐剂的分离检测,该方法中氯酚类防腐剂定量限为1 mg/kg、菊酯类防腐剂定量限为5 mg/kg,平均回收率为76.0%～108.8%。应用该方法对市场上销售的木制家具进行了检测,在部分家具中检出含有少量林丹。实验结果证明,该方法准确、灵敏,可有效地应用于木制家具中防腐剂的实际检验工作中。     

随机电报过程引起的光失相的计算

本文计算了红宝石中Al核自旋跳变引起的R₁[⁴A₂(S=-3/2)→²E(S=-1/2)]回波衰减。用随机电报过程描述每个Al核自旋(i)跳变引起Cr共振频率的起伏Δi,这个过程对光子回波衰减的贡献〈E_i(t₂₁)〉可以用解析式表示。首先计算核自旋(i)跳变的总速率Wi及它引起的Δi,求出〈E_i(t₂₁)〉。设对Cr光失相起主要贡献的每个Al核自旋跳变近似是独立的,所以总的回波强度是所有Al引起的〈E_i(t)₂₁〉的乘积。计算得到非指数的回波衰减,以I=I₀exp〔-(4t/t_m)^x〕拟合,x=2.56,t_m=50.6μs,与实验及计算机模拟的结果一致.     

MO／PVA薄膜材料在Ar^＋激光488.0nm线预辐照下的红光多重全息存贮

报道了甲基橙偶氮染料掺杂的聚乙烯醇薄膜材料在Ａｒ＾＋激光４８８．０ｎｍ线辐照下，用正交线偏振的６３２．８ｎｍ光作为写入光，通过旋转样品，在同一光斑内形成多个取向不同的相位光栅，实现了多重全息存贮的实验结果。在三重图象的存贮中，通过控制每次的写入时间、得到了三个均匀明亮的衍射图像，其平均衍射效率为０．１％。     

Electronic transitions of the Soret band of reaction centers from Rhodobacter sphaeroides studied by femtosecond transient absorbance spectroscopy

The Soret band of reaction centers from Rhodobacter sphaeroides has been systematically studied using femtosecond transient absorption spectroscopy. When the excitation wavelength was scanned over the entire Soret band, the approximate absorption spectra of the bacteriochlorophyll dimer, the monomer bacteriochlorophylls, and the bacteriopheophytins within the Soret band were determined by analyzing the ground state bleaching with about 100 fs resolution. The main contribution of H is on the blue end of the spectrum, peaking near 350 nm, P absorbs mostly on the red side of the spectrum, but probably has multiple bands, and the main absorbance of B likely lies between H and P, overlapping with P on the red side (particularly near 390 nm). The energy transfer from B to P in the QY band takes about 300 fs when Soret-band excitation is used and the time constant of overall energy transfer from H to B to P in the QY band when H is specifically excited near 350 nm is about 500 fs. Internal conversion after Soret-band excitation is the rate-limiting step for the energy-transfer process. The time constant of internal conversion for B and P is less than 300 fs, and for H it is about 500 fs.     

Femtosecond dynamics of flavin cofactor in DNA photolyase: radical reduction, local solvation, and charge recombination

We report here our femtosecond studies of the photoreduction dynamics of the neutral radical flavin (FADH) cofactor in E. coli photolyase, a process converting the inactive form to the biologically active one, a fully reduced deprotonated flavin FADH(-). The observed temporal absorption evolution revealed two initial electron-transfer reactions, occurring in 11 and 42 ps with the neighboring aromatic residues of W382 and F366, respectively. The new transient absorption, observed at 550 nm previously in photolyase, was found from the excited-state neutral radical and is probably caused by strong interactions with the adenine moiety through the flavin U-shaped configuration and the highly polar/charged surrounding residues. The solvation dynamics from the locally ordered water molecules in the active site was observed to occur in approximately 2 ps. These ultrafast ordered-water motions are critical to stabilizing the photoreduction product FADH(-) instantaneously to prevent fast charge recombination. The back electron-transfer reaction was found to occur in approximately 3 ns. This slow process, consistent with ultrafast stabilization of the catalytic cofactor, favors photoreduction in photolyase.     

970nmLD激发Tm^3＋,Yb^3＋掺杂的MFT玻璃材料上转换发光的研究

设计并制备了一种Ｔｍ＾３＋、Ｙｂ＾３＋共掺杂的多氟化物调整碲酸盐（ＭＦＴ）玻璃材料,其组份为５０ＴｅＯ２－１４．ＰｂＦ２－１０ＡｌＦ３－１０ＢａＦ２－１０ＮａＦ－０．１Ｔｍ２Ｏ３－５Ｙｂ２Ｏ３。测量了该玻璃系统的Ｒａｍａｎ散射光谱,在９７０ｎｍＬＤ激发下裸眼可以观察到很强的蓝色我,光谱测量证实这个蓝色发射（４７６ｎｍ）来源于＾１Ｇ４→＾３Ｈ６的跃迁,同时,还有两个较弱的红色发射源于＾１Ｇ４→＾３Ｈ     

用Eu3+作探针研究硼铅玻璃材料

利用Eu^3 离子探针技术对所设计的尔组分为（79.5-x)BO3/2-(20 x)PbF2-0.5Eu2O3(x=0,10,20,30,40)玻璃体系进行了研究。测量了不同组份玻璃的激发光谱,得到了各个配比玻璃样品的声子边带（PSB）谱,计算了电声子耦合常数g,讨论了g对组份的依赖关系。在此基础上讨论了该基质中稀土离子的无辐射跃迁行为。测量了在362nm激发下不同配比样品^5Do→^7Fo,^7F1,^7F2,的发射光谱,并利用发射光计算了Eu^3 离子在该玻璃体系中光学跃迁的J-O参量Ω2,进而讨论了其结构特性。     

低雷诺数下串列布置双圆柱涡激振动特性研究

基于四步半隐式特征线分裂算子有限元方法,对串列布置双圆柱双自由度涡激振动问题进行了数值模拟计算,并分析了间距比、剪切率、频率比以及折减速度4个参数对圆柱结构动力响应的影响.研究发现:不同固有频率比与剪切率对下游圆柱振动幅值影响较大,然而对上游圆柱振动幅值影响较小.上游圆柱在两个自由度方向达到最大值的折减速度不同,然而下...     

Micelle-induced multiple performance improvement of fluorescent probes for H2S detection

In this paper, two colorimetric and turn-on fluorescent probes N-[2-(2-hydroxy)-ethoxy] ethyl-4-azido-1,8-naphthalimide (SS1) and N-butyl-4-azido-1,8-naphthalimide (SS2) for selective recognition of H₂S were designed and synthesized. The probes were constructed by incorporating an azido group into the naphthalimide fluorophore as a specifical reaction group for sulfide utilizing its reducing property. Once treated with H₂S, the azido groups of the probes were converted to amino groups and the solutions’ color changed from colorless to yellow companied with a strong yellow-green fluorescence. Rapid and sensitive responses of the probes towards H₂S were achieved in the presence of cationic surfactant cetyltrimethyl ammonium bromide (CTAB): the reaction was completed within 10 min in CTAB compared to more than 4 h in buffer solution, and the detection limit decreased from 0.5 μM to 20 nM. High selectivity and good competition of both probes towards H₂S over other 11 ions and 2 reducing agents were realized in CTAB micelle. An overall linear concentration range of 0.05 μM to 1 mM was achieved with the assistance of differently charged surfactants CTAB and sodium dodecyl sulfate (SDS). The probes were applied to rapidly and sensitively detect H₂S levels in fetal bovine serum without any pretreatment of the sample.     

频率受随机电报过程调制的系统的相干瞬态过程

由随机电报过程的性质出发,给出了频率受一个随机电报过程调制系统的Bloch方程,得到了这种系统中的自由感应衰减和光子回波衰减.