[Pt(en)(5-Fu)2]Cl2配合物的合成及抗肿瘤活性

为寻求高效低毒的新型顺铂类抗肿瘤药物,用K2PtCl4、乙二胺(en)、氟尿嘧啶(5-Fu)为原料,设计合成了顺铂类似物[Pt(en))(5-Fu)2]Cl2配合物,由元素分析、红外光谱和质谱分析初步证实了其化学结构,用改良MTT、SRB法,选用K562、A549、Bel-7402、BIU-87、Bcap-37细胞株对其进行体外抗肿瘤活性测定。结果表明,所合成的配合物除在浓度为0．01、0．1／μg／mL时对K562细胞株抗肿瘤活性大于顺铂和氟尿嘧啶外,其它情况下的抗肿瘤活性均小于顺铂和氟尿嘧啶。该配合物仍有进一步研究的价值。     

Nordic teleradiology development.

In the Nordic countries there are several reasons why teleradiology has been an interesting topic of research during the last years. The distances in rural areas are long, and radiology expert service is not available in every health centre which is able to provide X-rays. Also, the telecommunication network is on a very advanced level in the Nordic countries. The staff is well educated and they are used to operating with computers. This all means that the infrastructure to develop and use systems like teleradiology exists. This paper describes two separate systems developed in Norway and Finland. Their development has been in many respects the same. The common hardware and software features, as well as the differences and the clinical experiences, are discussed in this paper.     

Design and development of the mars observer camera

The Mars Observer Camera (MOC) consists of three integrated optical subassemblies (one narrow-angle and two wide-angle cameras) with common electronics, designed to take high-spatial-resolution pictures of the surface of Mars and lower-spatial-resolution, synoptic coverage of the planet's surface and atmosphere. It incorporates several advanced technologies, including the use of graphite/epoxy structural materials, 32-bit microprocessors, 10⁸-bit digital buffers, and high-speed custom integrated circuits. The cameras use the “push broom” technique to build pictures, one line at a time, as the spacecraft orbits the planet. The narrow-angle camera can acquire images of areas ranging from 2.9 × 2.9 km² to 2.9 × 25.2 km² at a resolution of 1.4 m/pixel. Additionally, lowerresolution pictures (to a lowest resolution of about 11 m/pixel) can be acquired through the narrow-angle camera by pixel averaging; these images can be much longer (up to 2.9 × 500 km at 11 m/pixel). The wide-angle cameras are capable of viewing Mars from horizon to horizon and, in a single 24-hour period, can acquire a complete global image of the planet at a resolution of at least 7.5 km/pixel. Regional areas (covering hundreds of kilometers on a side) may be photographed at a resolution of better than 250 m/pixel at the nadir. The two wide-angle cameras image through a different spectral filter, allowing the construction of color images. The MOC is a cylinder 88 cm in length and about 40 cm in diameter; the redundant electronics, equivalent in complexity and computational power to two engineering workstations, fit within a volume 40 cm in diameter and 10 cm long behind the narrow-angle primary mirror. NASA's Mars Observer mission has adopted a distributed operations philosophy: all uplink and downlink activities for the MOC and the other payload experiments will occur remote from the Jet Propulsion Laboratory's command centers. Following its year-long flight to Mars (launch is scheduled for 16 September 1992), Mars Observer is planned to acquire data for one Mars year (687 Earth days). During that time, MOC will acquire about 2 × 10¹² bits of image and engineering data. During the last three months of the mission, Mars Observer will use a French-supplied relay system to acquire an additional 2 × 10⁹ bits of data from balloons deployed as part of the Soviet Mars '94 mission. These data will be collected and transferred to the Earth through the MOC electronics.     

Noncovalent binding of a reaction intermediate by a designed helix-loop-helix motif-implications for catalyst design

In our search for a catalyst for the transamination reaction of aspartic acid to form oxaloacetate, twenty-five forty-two-residue sequences were designed to fold into helix-loop-helix dimers and form binding sites for the key intermediate along the reaction pathway, the aldimine. This intermediate is formed from aspartic acid and the cofactor pyridoxal phosphate. The design of the binding sites followed a strategy in which exclusively noncovalent forces were used for binding the aldimine. Histidine residues were incorporated to catalyse the rate-limiting 1,3 proton transfer reaction that converts the aldimine into the ketimine, an intermediate that is subsequently hydrolysed to form oxaloacetate and pyridoxamine phosphate. The two most efficient catalysts, T-4 and T-16, selected from the pool of sequences by a simple screening procedure, were shown by CD and NMR spectroscopies to bind the aldimine intermediate with dissociation constants in the millimolar range. The mean residue ellipticity of T-4 in aqueous solution at pH 7.4 and a concentration of 0.75 mM was -18500 deg x cm(2) dmol(-1). Upon addition of 6 mm l-aspartic acid and 1.5 mM pyridoxal phosphate to form the aldimine, the mean residue ellipticity changed to -19900 deg x cm(2) dmol(-1). The corresponding mean residue ellipticities of T-16 were -21200 deg x cm(2) dmol(-1) and -24000 deg x cm(2) dmol(-1). These results show that the helical content increased in the presence of the aldimine, and that the folded polypeptides bound the aldimine. The (1)H NMR relaxation time of the imine CH proton of the aldimine was affected by the presence of T-4 as was the (31)P NMR resonance linewidth. The catalytic efficiencies of T-4 and T-16 were compared to that of imidazole and found to be more than three orders of magnitude larger. The designed binding sites were thus shown to be capable of binding the aldimine in close proximity to His residues, by noncovalent forces, into conformations that proved to be catalytically active. The results show for the first time the design of well-defined catalytic sites that bind a reaction intermediate with enzyme-like affinities under equilibrium conditions and represent an important advance in de novo catalyst design.     

Changes in electrical properties of polystyrene films under the influence of electrical discharges in gases

This paper describes changes of the following electrical properties of polystyrene films dielectrical permeability, ε, dielectrical loss, tan σ, and conductivity under the influence of electrical discharges in air and nitrogen. It is shown, that under the influence of electrical discharges there occurs an increase in conductivity and dielectrical permeability; furthermore, there appears a new range of losses, tan σ, and a shift of dipole-elastic losses, tan σ (alphaprocess), to higher temperatures, the latter meaning an increase in the relaxation time of the kinetic fragments. The changes observed in the electrical properties are due to changes in the polymer structure resulting from simultaneously occurring processes of crosslinking degradation and oxidation of polystyrene macromolecules. These processes also lead to changes in mechanical strength and molecular weight of the polymer. The presence of oxygen strongly accelerates these proccesses that proceed on polystyrene films under the influence of electrical discharges.     

The effect of prandtl number on conjugate heat transfer from rectangular fins

The problem of conjugate heat transfer from rectangular fins is treated numerically. Results are provided for the three Prandtl numbers (three fluids) 0.021, 0.7 and 5.0 and convection - conduction parameters meters in the range of 0 ≤ √Re k_fL/k_sb = CCP ≤ 5. The results indicated great effects of both CCP and Pr. Comparisons with the simple conventional fin theory show that concerning the fin efficiency, the simple theory yields acceptable results while the temperature variation and local heat flux distributions are not correctly predicted.     

Molten and solid metal-iodide-doped trialkylsulphonium iodides and polyiodides as electrolytes in dye-sensitized nanocrystalline solar cells

The conductivity and solar cell performance of metal-iodide-doped trialkylsulphonium iodides and polyiodides have been investigated as electrolytes in dye-sensitized nanocrystalline solar cells (DNSCs). Nine different metal-iodide-containing (R₂R′S)I with additional iodine provided overall solar-to-electric energy conversion efficiencies of over 2%, while used as electrolytes in DNSCs in simulated AM 1.5 solar light at the light intensity of 100 W m⁻². The highest overall conversion efficiency, 3.1%, was achieved by using the electrolyte (Bu₂MeS)I:AgI:I₂ in the proportions (1:0.03:0.05). The effects from 4-tert-butylpyridine treatment of the electrodes were studied. The effects of metal-iodide doping were also investigated with respect to speciation in the electrolytes and potential influence on electrochemical conductivity.     

Indoor phthalate exposure and contributions to total intake among pregnant women in the SELMA study

Phthalates are widely used in consumer products. Exposure to phthalates can lead to adverse health effects in humans, with early-life exposure being of particular concern. Phthalate exposure occurs mainly through ingestion, inhalation, and dermal absorption. However, our understanding of the relative importance of different exposure routes is incomplete. This study estimated the intake of five phthalates from the residential indoor environment for 455 Swedish pregnant women in the SELMA study using phthalate mass fraction in indoor dust and compares these to total daily phthalate intakes back-calculated from phthalate metabolite concentrations in the women's urine. Steady-state models were used to estimate indoor air phthalate concentrations from dust measurements. Intakes from residential dust and air made meaningful contributions to total daily intakes of more volatile di-ethyl phthalate (DEP), di-n-butyl phthalate (DnBP), and di-iso-butyl phthalate (DiBP) (11% of total DEP intake and 28% of total DnBP and DiBP intake combined). Dermal absorption from air was the dominant pathway contributing to the indoor environmental exposure. Residential exposure to less volatile phthalates made minor contributions to total intake. These results suggest that reducing the presence of low molecular weight phthalates in the residential indoor environment can meaningfully reduce phthalate intake among pregnant women.