案例教学法在分析化学理论教学中的实践研究

研究了案例教学法在分析化学理论教学中的实践,内容包括案例选材、设计、实施和案例模型评估。案例教学法模式在促进学生扎实学习理论知识的同时,改进学生对于分析化学课程的认知,提高学生的专业技能。案例教学法在分析化学理论教学中的实践可以在教师教学和学生学习之间建立良好的互动关系,并最终改善分析化学课程教学。     

Cu取代对水滑石前驱物及其衍生氧化物性能的影响

The coprecipitation method was used to prepare a series of different oxides (CuO: 0, 5%, 10%, 15%, 20%, 30% and 40%) derived from Cu substituted Mg/Al mixed anionic clay precursors (hydrotalcites) at the ratio of M2+/M3+ =3. In order to study influences of Cu and Mg content upon the performance of these materials, such characterization techniques as X-ray diffraction, thermogravimetrical analysis, differential scanning calorimetry, temperature programmed reaction and Fourier transform infrared reflectance spectra, were used. The results showed that complete structure of hydrotalcite precursors could be formed when CuO≤30%. When CuO≥40%, Cu(OH)2 phase appeared. Homogeneous composite oxides can be obtained by high temperature calcination at CuO≤20%. When CuO>20%, CuO phase was isolated. The content of Cu and Mg had significant influences on thermal stability of materials. The reduction ability of materials was related to calcination temperatures and material composition.     

Experimental measurement of the induced dipole moment of an isolated molecule in its ground and electronically excited states: indole and indole-H2O

Reported here are measurements of the magnitude and orientation of the induced dipole moment that is produced when an indole molecule in its ground S(0) and electronically excited S(1) states is polarized by the attachment of a hydrogen bonded water molecule in the gas phase complex indole-H(2)O. For the complex, we find the permanent dipole moment values mu(IW)(S(0)) = 4.4 D and mu(IW)(S(1)) = 4.0 D, values that are substantially different from calculated values based on vector sums of the dipole moments of the component parts. From this result, we derive the induced dipole moment values mu(I) (*)(S(0)) = 0.7 D and mu(I) (*)(S(1)) = 0.5 D. The orientation of the induced moment also is significantly different in the two electronic states. These results are quantitatively reproduced by a purely electrostatic calculation based on ab initio values of multipole moments.     

Obesity and genetic polymorphism of ERCC2 and ERCC4 as modifiers of risk of breast cancer

To evaluate the relationship of genetic polymorphisms of ERCC2 and ERCC4 genes, both involved in nucleotide excision repair (NER), and the risk of breast cancer, a hospital-based case-control study was conducted in Korea. Histologically confirmed breast cancer cases (n = 574) and controls (n = 502) with no present or previous history of cancer were recruited from three teaching hospitals in Seoul during 1995-2001. Information on selected characteristics was collected by interviewed questionnaire. ERCC2 Asp(312)Asn (G>A) was genotyped by single-base extension assay and ERCC4 Ser(835)Ser (T>C) by dynamic allele-specific hybridization system. Although no significant association was observed between the genetic polymorphisms and the risk of breast cancer, women with both ERCC2 A allele- and ERCC4 C allele-containing genotypes showed a 2.6-fold risk (95% CI: 1.02-6.48) of breast cancer compared to women concurrently carrying the ERCC2 GG and ERCC4 TT genotypes. The breast cancer risk increased as the number of "at risk" genotypes increased with a borderline significance (P for trend = 0.07). Interactive effect was also observed between ERCC4 genotype and body mass idnex (BMI) for the breast cancer risk; the ERCC4 C allele containing genotypes posed a 1.7-fold (95% CI: 0.96-2.93) breast cancer risk in obese women (BMI>25 kg/m(2)) with a borderline significance. Our finding suggests that the combined effect of ERCC2 Asp(312)Asn and ERCC4 Ser(835)Ser genotypes might be associated with breast cancer risk in Korean women.     

Morphology control of soap-free seeded P(St-EA-AA) latex particles

Soap-free poly(styrene-ethyl acrylate-acrylic acid) latex particles with narrow size distribution and with surface carboxyl groups were synthesized by semicontinuous emulsion polymerization, and the particles with homogeneous multihollow structure were obtained after alkali posttreatment. Effects of treatment conditions and crosslinking agents on particle morphology were investigated. Results showed that the multihollow structure can be formed inside the uncrosslinked particles only when the treatment temperature exceeded 50 °C, the pH was higher than 10.0, the amount of 2-butanone was more than 3.0 ml and the treatment time was longer than 30 min. Furthermore, the volume expansion of the particles increased with the temperature increased to 90 °C, the pH to 12.5 or the amount of 2-butanone to 7.0 ml, and this value increased first and then decreased with the treatment time prolonged. Fine pores can be generated in the shell of particles crosslinked by 0.2 g of ethyl glycol dimethylacrylate (EGDMA), while no hollow structure formed inside particles when 0.4 g of EGDMA or 0.2 g of divinyl benzene was used.     

Superhydrophobic CFx coating via in-line atmospheric RF plasma of He-CF4-H2

Stable superhydrophobic coatings on various substrates are attained with an in-line atmospheric rf plasma process using CF4, H2, and He. The coating layer is composed of CFx nanoparticulates and has an average roughness of approximately 10 nm. This roughness is much smaller than other surfaces reported for superhydrophobicity in the literature. The superhydrophobic coatings are produced on both metallic and insulating substrates without any need of separate microroughening or vacuum lines.     

Performance of hollow-fiber flow field-flow fractionation in protein separation

Since hollow-fiber flow field-flow fractionation (HF FIFFF) utilizes a cylindrical channel made of a hollow-fiber membrane, which is inexpensive and simple in channel assembly and thus disposable, interests are increasing as a potential separation device in cells, proteins, and macromolecules. In this study, performance of HF FIFFF of proteins is described by examining the influence of flow rate conditions and length of fiber (polyacrylonitrile or PAN in this work) on sample recovery as well as experimental plate heights. The interfiber reproducibility in terms of separation time and recovery was also studied. Experiments showed that sample recovery was consistent regardless of the length of fiber when the effective field strength (equivalent to the mean flow velocity at the fiber wall) and the channel void time were adjusted to be equivalent for channels of various fiber lengths. This supported that the majority of sample loss in HF FIFFF separation of apoferritin and their aggregates may occur before the migration process. It is finally demonstrated that HF FIFFF can be applied for characterizing the reduction in Stokes' size of low density lipoproteins from blood plasma samples obtained from patients having coronary artery disease and from healthy donors.     

组蛋白翻译后修饰无标定量方法可靠性的比较

组蛋白翻译后修饰是一种表观遗传学修饰,参与调控细胞的新陈代谢等重要生理过程。蛋白质组学发展迅速,使监控组蛋白翻译后修饰的动态变化成为可能。目前主要有3种无标定量方法（谱图计数法、峰面积积分法和信号强度法）,但何种定量方法更可靠尚未见系统性的详细报道。在稳定同位素标记细胞培养技术（SILAC）基础上,对去乙酰化酶抑制剂（SAHA）调控细胞乙酰化修饰水平的定量数据进行对比,比较3种无标定量方法对组蛋白翻译后修饰进行的定量分析,利用定量结果的标准差（SD）评估定量的可靠性,最终发现基于峰面积积分法定量的结果可靠性最高。该研究对难以进行同位素标记实验的样本分析,尤其对临床样本、大样本的组蛋白修饰谱分析具有重要参考意义。     

Cost‐Effective,High‐Performance Porous‐Organic‐Polymer Conductors Functionalized with Sulfonic Acid Groups by Direct Postsynthetic Substitution

We demonstrate the facile microwave‐assisted synthesis of a porous organic framework 1 and the sulfonated solid ( 1S ) through postsubstitution. Remarkably, the conductivity of 1S showed an approximately 300‐fold enhancement at 30 °C as compared to that of 1 , and reached 7.72×10⁻² S cm⁻¹ at 80 °C and 90 % relative humidity. The superprotonic conductivity exceeds that observed for any conductive porous organic polymer reported to date. This material, which is cost‐effective and scalable for mass production, also revealed long‐term performance over more than 3 months without conductivity decay.