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Electrostatic compaction of double stranded DNA induced by a positively charged poly(amidoamine) (PAMAM) dendrimer of generation four (G4) was found to produce two unique types of DNA mesophases, in which the DNA bent into superhelices packed in a tetragonal or hexagonal lattice. The structure formed at a lower dendrimer charge density was three-dimensionally (3D) ordered, as characterized by the P41212 space group with a 41 screw axis in a tetragonal arrangement, showing that the weakly bent DNA superhelices with a pitch length of ca. 5.0 nm possessed both identical handedness and phase conservation. The 3D ordered structure transformed into a 2D mesophase at a higher dendrimer charge density, wherein the strongly bent superhelices with a pitch length of ca. 4.0 nm organized in a hexagonal lattice without lateral coherence of helical trajectory. The counterion valency of the protonic acid that is used to charge the dendrimer was found to influence the phase diagram. Under a given dendrimer charge density, the complex with a multivalent acid-protonated dendrimer tended to form structures with less curved DNA, attesting that the driving force of charge matching was reduced by increasing the counterion valency of the dendrimer.

Polyamidoamine (PAMAM) dednrimer bearing a well-defined number of amine groups can be protonated under physiological or acidic condition to generate the macrocations capable of forming electrostatic complex (called “dendriplex”) with DNA for gene delivery. Using small-angle X-ray scattering (SAXS) and small angle neutron scattering (SANS), here we constructed the morphological map of the complex of DNA with PAMAM dendrimer of generation four (G4) in terms of the dendrimer charge density and the nominal N/P ratio given by the feed molar ratio of dendrimer amine group to DNA phosphate group. With the increase of dendrimer charge density under a given nominal N/P ratio, the structure was found to transform from square columnar phase (in which the DNA chains packed in square lattice were locally straightened) to hexagonally-packed DNA superhelices (in which the DNA chains organizing in a hexagonal lattice twisted moderately into superhelices) and finally to beads-on-string structure (in which DNA wrapped arou...

The purpose of this study was to modify the surface characteristics of CB so as to prevent the aggregation of CB to provide the dispersibilities in either H 2 O or organic solvent. In this study, five kinds of hydrophilic TEMPO-terminated polymer, hydrophobic TEMPO-terminated polymer and amphiphilic TEMPO-terminated block copolymer were synthesized. The five kinds of TEMPO-terminated polymers were: (1) poly(4-acetoxystyrene) (PAS-T), (2) poly(4-hydroxystyrene) (PHS-T), (3) polystyrene (PS-T), (4) poly(4-acetoxystyrene)- block -polystyrene (PAS- b -PS-T), (5) poly(4-hydroxystyrene)- block -polystyrene (PHS- b -PS-T). These TEMPO-terminated polymers with desired molecular weights and specific structures were synthesized by using the method of living radical polymerization in the presence of 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO). These TEMPO-terminated polymers and TEMPO-terminated block copolymers were grafted onto the surface of CB through a reaction of polymer radicals trapped by CB, so as to obtain the TEMPO-terminated polymer/CB and TEMPO-terminated block copolymer/CB composite nanoparticles. Various variables such as reaction time, reaction temperature, amount of TEMPO-terminated polymer, molecular weight of TEMPO-terminated polymer and amount of CB all of which influenced the grafting efficiency were investigated. Besides, the stability of the composite nanoparticles, which dispersed in H 2 O or organic solvent, was investigated by laser light scattering. The amphiphilic composite nanoparticles, PHS-T/CB and PHS- b -PS-T/CB, which dispersed well in both H 2 O and organic solvent, were synthesized successfully in this work.

The crystallization behavior and morphological structure of isothermally melt-crystallized and cold-crystallized poly(ethylene/trimethylene terephthalate) (ET) copolyesters were investigated by differential scanning calorimetry, wide-angle X-ray diffraction, and small-angle X-ray scattering. At a given crystallization temperature, the rate of cold crystallization was found to be faster than that of melt crystallization. The Avrami analysis revealed that the nuclei formed rapidly during the cooling process. This suggests that the nuclei formed during rapid cooling and that the athermal nucleation mechanism contributes to the cold-crystallization process of ET copolyesters. The crystal thickness (l c ), amorphous layer thickness (l a ), and long period (L) of ET53 and ET82 between the isothermal melt-crystallization and cold-crystallization had no significant difference. The values of the linear crystallinity (ϕ c lin) for PET, PTT, and ET copolyesters under isothermal melt-crystallization and cold-crystallization conditions were similar. This means that the random distribution of the constitutional repeating unit in the molecular chain of ET copolyesters was not exclusively in the lamella formation.

Mammalian target of rapamycin (mTOR) is an important regulator of protein translation, biosynthesis, cell growth and cell proliferation, is over-activated in various human malignancies, but very few studies have yet to explore the mTOR activity in oral squamous cell carcinoma (OSCC), which is the 7th leading death of malignancy in Taiwan. We collect tissue samples of 58 OSCC patients from Taipei veteran general hospital during along with their clinical parameters. Immunohistochemical (IHC) staining was performed on the tissues for investigating active mTOR (p-mTOR) expression level with the use of tissue microarray (TMA) technique. The results revealed p-mTOR expression level in OSCC tissues are significantly higher than in normal oral mucosal tissues ( p p = 0.0391) and higher tumor recurrence after adjuvant cisplantin treatment ( p = 0.0159). Although positive group shows a relatively rapid descent on survival curves, no significant difference between positive and negative group in over-all survival rate ( p = 0.1064), cancer specific survival rate ( p = 0.0914) and disease free survival rate ( p = 0.0509). p-mTOR expression level in OSCC correlates to tumor recurrence, possible poorer survival rate and may even associate with cisplantin resistance in our study. A scale-up study in the future may further elucidate the role of mTOR in OSCC.

This paper addresses the problem of controlling a vehicle motion system by continuously adjusting the brake torque. A full-order model which consists of the vehicle motion subsystem, wheel dynamics, and servo-valve hydraulic actuator is under consideration. Based on the varying dynamic structure of the system, the controllers are designed for two cases. The first case, i.e., when the slip rate is small, considers the trajectory tracking control for stopping of vehicle motion, and an adaptive control scheme is developed. In the second case, i.e., when the slip rate is large, rapid reduction of slip rate is deemed as the control target so that an adaptive sliding mode control is proposed to achieve such a goal. Finally, due to unknown changing condition, a composite form of the above-mentioned controllers is then constructed by applying the fuzzy composition concept. Asymptotic stability of the overall system is confirmed via Lyapunov stability theorem and is also demonstrated by computer simulations.