Biologically active polymer - targeting polymeric antitumor agents-

To synthesize targeting polymeric antitumor agents, poly[(2-acetoxy-3,4-dihydro-2H-pyran)-alt-(maleic anhydride)] as polymer backbone, chlorophyll derivatives(CpD) extracted from silkworm excreta as targeting moiety and 5-fluorouracil and 6-mercaptopurine as pharmacons were selected. The polymer exhibited an antitumor activity comparable to that of cyclophosphamide in vivo. CpD as well as CpD-polymer conjugate were localized on tumor cells in vitro and delivered to tumor tissues in vivo specifically. The targeting polymeric antitumor agents were synthesized by coupling pharmacons and CpD on the polymer chain with the aid of reactions between functionalities of the reactants and anhydride groups on the polymer backbone. Various tests of their biological activities in vivo are in progress.     

Morphology of a Poly(imide siloxane) Segmented Copolymer/Silica Hybrid Composite

The role of polydimethylsiloxane (PDMS) as a compatibilizer of polyimide/silica hybrid composites was investigated. Introduction of PDMS into a polyimide matrix retards the phase separation of hybrid composites and also prevents the formation of high‐molecular‐weight silicate. PDMS interacts with silica because of the similarity of its structure with the sol‐gel glass matrix of the silica precursor, indicating that poly(imide siloxane)/silica might be a good candidate material for organic/inorganic hybrid composites.     

Coagulation Behavior of Antimony Oxyanions in Water: Influence of pH,Inorganic and Organic Matter on the Physicochemical Characteristics of Iron Precipitates

The presence of inorganic and organic substances may alter the physicochemical properties of iron (Fe) salt precipitates, thereby stabilizing the antimony (Sb) oxyanions in potable water during the chemical treatment process. Therefore, the present study aimed to examine the surface characteristics, size of Fe flocs and coagulation performance of Sb oxyanions under different aqueous matrices. The results showed that surface properties of Fe flocs significantly varies with pH in both Sb(III, V) suspensions, thereby increasing the mobility of Sb(V) ions in alkaline conditions. The negligible change in surface characteristics of Fe flocs was observed in pure water and Sb(III, V) suspension at pH 7. The key role of Van der Waals forces of attraction as well as hydration force in the aggregation of early formed flocs were found, with greater agglomeration capability at higher more ferric chloride dosage. The higher Sb(V) loading decreased the size of Fe flocs and reversed the surface charge of precipitates, resulting in a significant reduction in Sb(V) removal efficiency. The competitive inhibition effect on Sb(III, V) removal was noticed in the presence of phosphate anions, owing to lowering of ζ-potential values towards more negative trajectory. The presence of hydrophobic organic matter (humic acid) significantly altered the surface characteristics of Fe flocs, thereby affecting the coagulation behavior of Sb in water as compared to the hydrophilic (salicylic acid). Overall, the findings of this research may provide a new insight into the variation in physicochemical characteristics of Fe flocs and Sb removal behavior in the presence of inorganic and organic compounds during the drinking water treatment process.     

Identification of nematic lymoesophases with discotic and cylindrical micelles in lyotropic amphiphilic systems

Nematic lyomesophases with discotic (N _D) and cylindrical (N _C) micelles in complex multicomponent lyotropic systems based on alkyltrimethylammonium bromide detergents have been identified by the ¹H-²H-, and ¹³C-NMR methods and polarizationoptical microscopy. The difference in the structures of the N _D and N _C nematic phases is especially pronounced in the ¹³C-NMR spectra. Addition of chiral dopants to the lyomixture facilitates formation of the Ch _D and Ch _C cholesteric phases. According to the ¹³C-NMR spectra, the micellar mobility in the cholesteric lyomesophases decreases in comparison with the nematic ones. The alignment of lyocholesterics under the action of an external magnetic field is found.     

On equivariant slice knots

We suggest a method to detect that two periodic knots are not equivariantly concordant, using surgery on factor links. We construct examples which satisfy all known necessary conditions for equivariant slice knots- Naik's and Choi-Ko-Song's improvements of classical results on Seifert forms and Casson-Gordon invariants of slice knots - but are not equivariantly slice.

     

Direct intensity modulation of a rectangular ring laser with bidirectional lasing characteristics

The direct intensity modulation of a three-guide coupled rectangular ring laser having bidirectional lasing characteristics is reported for the first time. The rectangular laser cavity consists of four low loss total internal reflection mirrors and an output coupler made out of three passive coupled waveguides. The laser is fabricated using a total cavity length of 580 μm with active section lengths of 250 μm. For both the clockwise and counterclockwise circulating directions, a lasing threshold of around 38 mA is obtained at room temperature under continuous wave operation. A maximum 3-dB modulation bandwidth of approximately 3.2 GHz is observed in both circulating directions.     

Parameter identification by mixed spectral-pseudospectral approximations

1. IntroductionIn studying many problems arising in science and engineering, we need to estimate parameters in governing differential equations. Some theoretical results for this kind of inverseproblems can be found in various literatu-res, e.g., see [1-4]. Also, there have been a lot ofwork concerning their numerical approalmations, e.g., see [5-10]. One of numerical methods is the so-called optimization method as in is]. To do this, we first guess the unknownparameters in some ways, and the…     

Characteristics of Graph Braid Groups

We give formulae for the first homology of the n-braid group and the pure 2-braid group over a finite graph in terms of graph-theoretic invariants. As immediate consequences, a graph is planar if and only if the first homology of the n-braid group over the graph is torsion-free and the conjectures about the first homology of the pure 2-braid groups over graphs in Farber and Hanbury (arXiv:1005.2300 [math.AT]) can be verified. We discover more characteristics of graph braid groups: the n-braid group over a planar graph and the pure 2-braid group over any graph have a presentation whose relators are words of commutators, and the 2-braid group and the pure 2-braid group over a planar graph have a presentation whose relators are commutators. The latter was a conjecture in Farley and Sabalka (J. Pure Appl. Algebra, 2012) and so we propose a similar conjecture for higher braid indices.