Microdetermination of proteins by enhanced Rayleigh light scattering spectroscopy with morin

Under acidic conditions, the reaction between 3,5,7,2′,4′-pentahydroxyflavone (morin) and proteins enhances the weak light scattering of morin drastically. The enhanced light scattering intensity is proportional to the content of proteins. This fact is the basis of a new method for the quantitative analysis of proteins. The linear range is 0.45–7.15 and 0.46–11.14 μg/mL for BSA and HSA, respectively. The relative standard deviation is 3.76% (n = 12) for BSA in the middle of the linear range. The results of this assay for human serum samples were comparable with those from the traditional method (CBB method). There is almost no interfere from amino acids and most of the metal ions. The scattering spectrum of morin was also discussed. Received: 11 October 1998 / Revised: 18 February 1999 / Accepted: 24 February 1999     

Morphological and Structural Studies of sPS/aPS Blends

Inrecentyears,thenewsedricrystallinepolymersyndiotacticp0lystyrene(sPS)hasat-ITactedmuchattentionduetoitsg0odchendcalresistanceandenhancedmechanicalperformanceatelevatedtemPeratUre.'H0wever,itexhibitshighbrittlenessandpoorimPact-resistanceandtCar-resistance.2Therefore,itisnecessarytomodifyitwithtougheningpolyIners.AsimPlemeth0dto0verc0methedriscibilityofatwo-phaseblendofsPSandatougheningpolymristotwrovetheinterfacialaffmity,wheretheadditionofablockcoP0lymerisconsideredtobemosteffective.3…     

On-line pretreatment and determination of Pb, Cu and Cd at the μg l level in drinking water by chelation ion chromatography

A novel, highly sensitive method for the simultaneous separation and determination of lead, copper, cadmium and other transition metals in drinking water was achieved by on-line sample pretreatment of chelation ion chromatography. Manganese, which coeluted with cadmium, was oxidized to permanganate by ammonium persulfate before injection. Permanganate, with bulk quantity of alkali, alkaline earth metals, iron and aluminum, was eliminated by pyrophosphoric acid–ammonium acetate buffer solution (pH 5.5), while retaining heavy and transition metals on a selective chelating resin (MetPac CC-1 column). Then, they were disabsorbed and transferred to a sulfonated cation exchanger (TMC-1 column). Finally, the concentrated trace metals were separated on a bifunctional ion-exchange column (CS5A) by a concentration gradient of oxalic acid and sodium nitrate eluents, coupled with post-column spectrophotometric detection with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol (5-Br-PADAP) at 560 nm. The separation and color-development conditions were optimized. The detection limits for the method (signal-to-noise ratio=3:1) were at or below the μg l⁻¹ level. The results of drinking water analyses were satisfactory.     

胺类对α-溴代萘/β-环糊精体系流体室温燐光的影响

首次研究了不同的胺对α-溴代萘(α-BrNp)/β-环糊精(β-CD)体系RTP发射的影响.发现胺能显著增强α-BrNp/β-CD体系的RTP,发射,RTP强度随着胺的烷基链的增长和支链的增加而增加,且当胺的用量是β-CD用量的一倍时,RTP强度最大.由此认为、胺的影响主要应归因于胺分别从β-CD的二端接近,胺的-NH_2基与β-CD的-OH基形成氢键,而其烷基从CD二端折向空腔,封住了CD的上、下端口.这不仅提高了CD腔内的疏水性,增大了发光体与CD间的包结常数,同时,对外部氧向CD腔内的扩散起着隔离作用,显著减小了三线态氧对腔内发光体激发态的猝灭作用.从而可在不除氧的条件下观察到发光体强的RTP,发射,且体系清澈透明.胺的作用属于超分子化学中的分子调控作用.     

热致液晶三元共聚酯酰亚胺的合成与表征

采用直接熔融缩聚方法由１ ,６ － 己撑－ 双（４ － 羟基酞酰亚胺）（ＢＨＰＩ） 、对羟基苯甲酸（ＰＨ ＢＡ） 和对苯二甲酸（ＴＰＡ） 合成一系列三元共聚酯酰亚胺。对聚合物进行示差扫描量热（ＤＳＣ） 、偏光显微镜（ＰＬＭ） 、广角Ｘ－ 射线衍射（ＷＡＸＤ） 等分析表征,结果表明该系列聚合物具有向列型液晶特征。     

Approaches to phenazine-derived N-isosteres of anthracyclinones

1-Hydroxyphenazine 5,10-dioxide showed antitumor properties against mouse leukemia P388. It also participated in biochemical mechanisms of quinoid antitumor agents, as indicated by inhibition of radiolabeled DNA-RNA precursors in cultured leukemia L1210 cells and by stimulation of oxygen consumption in mammalian microsomes. This suggests that the isosteric di-N-oxide system may be a biologically active substitute for 1,4-quinone, and that di-N-oxides of tetrahydrobenzo[b]phenazines can be explored as anthracyclinone N-isosteres. As potential synthetic intermediates, 7,8,9,10-tetrahydro-6,11-dihydroxybenzo[b]-phenazines have been prepared by 1) Diels-Alder addition of phenazine-1,4-quinone and 1-methoxy-3-(trimethylsilyloxy)-1,3-butadiene to give isolable but labile adducts and 2) condensation of 6,7-diamino-1,2,3,4-tetrahydro-2-hydroxy-5,8-dimethoxy-2-naphthoic acid with 3-methoxy-1,2-quinone. Attempts at N-oxidation gave instead oxidation of the 6,11-hydroquinone ring to quinone, regardless of hydroxyl protection. Despite previous literature indications, we have been unable to synthesize the 1,4-dihydroxyphenazine 5,10-dioxide system. We conclude that this hydroxyl substitution pattern (1,4) in an adjacent ring must be avoided in the redesign of anthracyclinone isosteres that have di N-oxide in place of quinone.