Preparation and evaluation of a large-volume radial flow monolithic column

In this study, a 38 mL monolith with homogeneous porous structure was produced by a single polymerization from glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) in the presence of porogens and an initiator. The uniform temperature distribution within the reaction system was achieved by adding reactant mixture continuously and enhancing the heat transfer ability of the polymerization system. Homogeneous porous structure in the monolith was proved by SEM and the pore size distribution profiles measured by mercury intrusion porosimetry. Experimental results from proteins separation indicated that the dynamic capacity and resolution of radial flow monolithic column were independent of flow rates. Furthermore, the pressure drop on the column was linearly dependent on the flow rate and did not exceed 1.7 MPa even at a flow rate of 50 mL/min, which proved that the prepared monolith could be used in the quick separation and preparation of biopolymers.     

A novel mimetic enzymatic fluorescence immunoassay for hepatitis B surface antigen by using a thermal phase separating polymer

Iron tetrasulfonatophthalocyanine (FeTSPc), a peroxidase mimic, was used as a labeling reagent and poly(N-isopropylacrylamide) (PNIP) as the separation support of the immune complex for the mimetic-enzymatic immunoassay of hepatitis B surface antigen (HBsAg). PNIP was precipitated from aqueous solution when the ambient temperature was higher than its lower critical solution temperature of 31 degrees C. In a sandwich immunoassay, the antigen (HBsAg) first reacted with mouse anti-human HBsAg antibody immobilized on PNIP (PNIP-antibody) and then further reacted with FeTSPc-labeled mouse anti-HBsAg antibody (antibody-FeTSPc) at room temperature in a homogeneous format. After changing the temperature to separate the PNIP-antibody-HBsAg-antibody-FeTSPc conjugate moiety, it was re-dissolved and determined by coupling with the fluorogenic reaction of hydrogen peroxide and p-hydroxyphenylpropionic acid. The sensitivity of this method (3 ng mL-1) was close to that of the traditional ELISA using the same reactants. However, the assay was much faster (the assay time decreased from 100-120 to 45 min). This method was applied to determine HBsAg in human serum with satisfactory results.     

Molecular modeling on recognition of sheared and normal DNA by novel metal complex Λ- and Δ-[Co(phen)2hpip]

Recognition of sheared and normal DNA by a novel metal complex [Co(phen)₂hpip]³⁺ (phen=1,10-phenanthroline, HPIP=2-(2-hydroxyphenyl)imidazole[4,5-f][1,10]phenanethroline) is studied by molecular modeling. Calculating results indicate that, this complex can specifically recognize DNA segment of sequence –MMNNMM– (M means mismatch base pairs and N means normal base pairs). Intercalating from minor groove between the middle normal duplex into the sheared DNA with the depth of 1.2 nm is of preference and enantioselectivity is observed. Comparison on the two DNA structures of optimal conformation and analysis on the interaction between DNA and the two tail ligands of the complex show that, the effect of the two neighboring mismatch duplexes on the structure of the middle normal base pairs and the steric interaction between the mismatch duplexes and the two tail ligands of the complex are the essential reason to the segment specificity. Investigation on the detailed energy terms indicate that, in effecting enantioselectivity, the electrostatic distribution of the complex is in the majority and steric interaction is at the next place. But, steric interaction is surely the only factor determining the intercalating from minor groove.     

Photochemical Reaction of Decacarbonyldirhenium with Thiophene and Crystal Structure of Tetradecacarbonylhydridotrirhenium

The photochemical reaction of Re₂(CO)₁₀ with thiophene in hexane solution was investigated under vacuum. Three rhenium clusters: H₂Re₃(CO)₁₂, HRe₃(CO)₁₄ and Re₃(CO)₁₄(OH)₄, were isolated. The structure of Fellmann-Kaesz cluster Complex HRe₃(CO)₁₄ was determined by use of the X-ray diffraction method. The three rhenium atoms form a plane of symmetry and L: Re₁Re₂Re₃ is 107°. The ten carbonyl groups bonded to the two terminal rhenium atoms Re₁ and Re₃, are staggered with respect to the central rhenium atoms. The bond lengths are 3.10 Å for Re₂-Re₃ and 3.34 Å for Re₁-Re₂. The bridging hydride is between Re₁ and Re₂.     

Hydroxide-promoted redox reactions in water of α-Phenyl-4-nitro-benzenemethanol, α-(p-Nitrophenyl)-4-pyridinemethanol,and α-(p-Nitrophenyl)-4-Pyridinemethanol N-Oxide steric inhibition of resonance

α-Phenyl-4-nitrobenzenemethanol ( 3 ) reacted with 1 M sodium hydroxide to yield 4, 4′-dibenzoyl-azoybenzene ( 5 ) (51%), 4-hydroxy-4′-benzoylazobenzene ( 6 ) and benzoic acid (12% each), and smaller amounts of 4-aminobenzophenone and 4-nitrobenzophenone. Both α-phenyl-2-nitrobenzenemethanol ( 9 ) and 3, 5-dimethyl-4-nitrobenzenemethanol ( 10a ) did not react with 1 M sodium hydroxide, presumably due to steric hindrance. α-(p-Nitrophenyl)-4-pyridinemethanol ( 14 ) and its N-oxide 11 with 1 M sodium hydroxide yielded 4,4′-diaroylazoxybenzenes 15a and 12a , respectively, 4,4′-diaroylazobenzenes 15b and 12b , respectively, as well as 4-hydroxy-4′-aroylazobenzenes 16 and 13 , respectively. The relative reaction rates were 11 > 14 > 3 . Studies with 11 showed that the nitro group is involved in the redox reaction in preference to the N-oxide group.     

What can we do with only a pair of rusty compasses?

Compasses are called rusty, if one can draw only the unit circle with them. We prove that from two points A and B, with only rusty compasses, one can draw the points of k-section of AB, and all the vertices of a regular n-gon which has a side AB, where k is any integer greater than 1, and n=3, 4, 5, 6, 8, 12, 17, 257, ..., etc. Generally, let A be (0, 0) and let B be (, 0), then one can draw all the points (x, y) where x and y are any elements in some regular 2 ^m -extension of the rational field, for m=1, 2, 3, ...