LED照明节律效应随年龄的变化

研究了不同色温LED照明时节律效应随年龄的变化规律。在节律因子计算公式中,引入不同年龄人眼的透射谱,分析LED色温和年龄对节律因子的影响。然后,测量了12名老年和18名青年男性在黑暗状态下以及照度为500 lx、不同色温LED照明时的心率,采用黑暗状态与照明状态的心率变化表征节律效应,来验证所得的理论规律。结果表明:色温为6 500,5 500,4 500,3 500 K的LED照明时,青年人(20岁)的节律因子分别为1.1,0.7,0.5,0.44,不同色温LED照明时心率变化率差异明显;老年人(65岁)的节律因子分别为0.5,0.3,0.25,0.2,不同色温下心率变化较小。在同一色温LED照明时,节律效应随着年龄的增加而减小。LED色温不同时,青年人节律因子的变化较大,老年人则变化较小。     

几丁质发酵液的生物活性

鞘氨醇单胞菌CJ-5菌株在以几丁质为碳源的培养基上生长,既产生几丁质酶又产生壳聚糖酶.利用其发酵液进行抑制真菌,促进植物生长等生物活性的研究及作用机理的探讨,发现CJ-5菌株的几丁质发酵液具有抑制番茄枯萎病菌,促进水稻扩叶生根的效果,显示了潜在的防治植物病原菌及促进植物生长的能力.     

过氧亚硝酸的细胞生物学效应及其分析方法研究进展

对过氧亚硝酸的细胞生物学效应做了简单阐述，全面回顾和总结了近年来用于过氧亚硝酸测定的各种分析方法，并对各种方法的优缺点及其适用范围进行了比较．过氧亚硝酸的相关研究已取得很大进展，但其在线准确检测仍存在一定困难．     

含吡啶(噻唑)甲基的哌嗪类化合物的合成及生物活性

采用活性基团拼接原理, 分别以2-氯-5-氯甲基吡啶和2-氯-5-氯甲基噻唑为原料, 经过氮烷基化和加成反应, 得到系列含吡啶甲基或噻唑甲基的哌嗪类化合物. 初步测试结果表明: 部分化合物表现出较弱的除草活性和杀豆蚜活性, 但对孑孓显示出较高的的杀灭活性, 其中4f在50 mg/L的浓度下对孑孓的杀死率可达100%.     

Thermodynamics of natural selection

It is shown that biological-natural-selection-like behavior can occur, as a general type of time evolution, in a statistical system where detailed balance is violated owing to the presence of metastable energy states. A model of a non-equilibrium phase transition corresponding to the spontaneous origin of self-reproduction in the system is suggested. After a phase transition, the system passes from one quasistationary distribution of self-reproducing subsystems to another, with an increase in the total organization, as long as the growth of the energy flow through the system or a reduction of energy dissipation in the system is possible. The entropy production is calculated for this process in terms of selective values of Eigen's theory for self-organization in autocatalytic systems. Correspondence of the extremal principle of Eigen's theory with the criterion of evolution in Prigogine's thermodynamics is established.     

生物组织电穿孔中的热效应研究

本文对生物组织电穿孔中的热效应问题进行了计算研究。结果表明生物组织电穿孔过程中,选用不当的脉冲电压参数,会对组织造成严重的热损伤。若采用相同的烧伤阈值来描述热损伤范围,则相同电脉冲参数条件下在体组织比离体组织受到的热损伤更大。     

Radiobiological response of human hepatoma and normal liver cells exposed to carbon ions generated by Heavy Ion Research Facility in Lanzhou

Human hepatoma and normal liver cells were irradiated with ¹²C⁶⁺ ion beams (LET = 96.05 keV/μm) and γ-rays at Heavy Ion Research Facility in Lanzhou (HIRFL). The chromatid breaks and break types were detected using the premature chromosome condensation technique. Our experimental results showed that chromatid breaks seem to have a good relation with ¹²C⁶⁺ absorbed dose and ¹²C⁶⁺ are more effective to induce chromatid breaks as compared to the γ-rays. For ¹²C⁶⁺ ion irradiation the major break was isochromatid break, while chromatid breaks were dominant for γ-ray irradiation. We also observed that the Relative Biology Effectiveness (RBE) of ¹²C⁶⁺ ion is about 2.5 times higher than that of γ-rays.     

MALDI-MS of drugs: Profiling,imaging, and steps towards quantitative analysis

Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique which can be used in mass spectrometry to produce ions from biomolecules without inducing the fragmentation associated with traditional methods of ionization. When used with small molecules, the lack of fragmentation allows identification of specific molecules against a background of alternative signals; thus, for example, the presence of drug molecules and metabolites can be distinguished from a range of alternative biomolecules present within a tissue sample. Using highly collimated lasers in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) allows imaging of a tissue sample whereby the laser is rastered across the sample and individual mass spectra are collected in a serial manner. Thus, the distribution of the molecules within the tissue sample can be presented in the form of a 2D image. While the detection of specific drug molecules and metabolites within biological samples has its uses, quantification of those same molecules would be of greater benefit in a clinical setting. However, accurate quantification presents additional challenges. We present an overview of the MALDI-MS technique followed by recent progress in profiling drugs and their metabolites through imaging drug distributions within tissues and finish with recent developments in the quantification of drugs in tissues by MALDI-MSI.     

Optical diffraction tomography microscopy with transport of intensity equation using a light-emitting diode array

Optical diffraction tomography (ODT) is an effective label-free technique for quantitatively refractive index imaging, which enables long-term monitoring of the internal three-dimensional (3D) structures and molecular composition of biological cells with minimal perturbation. However, existing optical tomographic methods generally rely on interferometric configuration for phase measurement and sophisticated mechanical systems for sample rotation or beam scanning. Thereby, the measurement is suspect to phase error coming from the coherent speckle, environmental vibrations, and mechanical error during data acquisition process. To overcome these limitations, we present a new ODT technique based on non-interferometric phase retrieval and programmable illumination emitting from a light-emitting diode (LED) array. The experimental system is built based on a traditional bright field microscope, with the light source replaced by a programmable LED array, which provides angle-variable quasi-monochromatic illumination with an angular coverage of ±37 degrees in both x and y directions (corresponding to an illumination numerical aperture of ∼0.6). Transport of intensity equation (TIE) is utilized to recover the phase at different illumination angles, and the refractive index distribution is reconstructed based on the ODT framework under first Rytov approximation. The missing-cone problem in ODT is addressed by using the iterative non-negative constraint algorithm, and the misalignment of the LED array is further numerically corrected to improve the accuracy of refractive index quantification. Experiments on polystyrene beads and thick biological specimens show that the proposed approach allows accurate refractive index reconstruction while greatly reduced the system complexity and environmental sensitivity compared to conventional interferometric ODT approaches.     

时间延迟对基因调节回路中生物记忆影响研究

生物记忆是广泛存在于各种生物子系统的一种重要的效应. 基于一个双反馈的基因调节回路模型, 采用数值模拟的方法研究了局部反馈中存在的时间延迟对生物记忆时间的影响. 结果发现, 小量的延迟能够很大地提高生物记忆时间. 并且, 生物记忆随延迟时间呈线性增加. 这种增强模式与噪声对生物记忆时间的提高完全不同. 延迟和噪声对生物记忆的提高可以进行相互的控制增强, 但不会影响对方的增强模式.