Stability and orientation of cecropin P1 on maleimide self-assembled monolayer (SAM) surfaces and suggested functional mutations

One of the main challenges of biosensor design is to understand the protein or peptide stability on the chip in high resolution structural detail.Since conventional experimental methods are limited by the resolution for their applications on surface tethered peptides/proteins,a recently developed coarse grained simulation method is employed to explore the peptide/surface interaction in residue-level resolution.This work shows how the coarse grained model successfully describes peptide–surface interactions by evaluating thermal stability of the peptide cecropin P1 in bulk solution and on surfaces by physical adsorption and chemical tethering.The simulation also reproduces observations of peptide orientations on the self-assembled monolayer surface from earlier experimental work.Additionally,using knowledge obtained from the simulations,specific mutations are suggested and the desired structure and pose on the surface is obtained.In summary,this work sheds a light on the reasonable biosensor design that is guided by simulations.     

Different mechanism of capacitance change for gas detection using semiconducting and metallic single-walled carbon nanotubes

Semiconducting single-walled carbon nanotubes (s-SWCNTs) with lower absorption energy of NO₂ gas exhibited higher sensitivity than metallic SWCNTs. The result originated from quantum capacitance of s-SWCNTs, which was readily affected by charge transfer, whereas that of m-SWCNTs showed no change with even more transferred charges. However, m-SWCNT that were aligned polarize adsorbed gases on the surface by a local field that contributed the capacitance changes of m-SWCNT networks. This is a newly introduced detection mechanism of gas sensing using m-SWCNTs.     

Hierarchical crystalline structures induced by temperature profile in HDPE bars during melt penetration process

The hierarchical crystalline morphologies and orientation structures across the thickness direction in high-density polyethylene(HDPE) molded bars were investigated via a novel melt-penetrating processing method named multi-melt multi-injection molding(M3IM). The samples with various mold temperatures(20, 40 and 60 °C) were prepared, and the effects of the external temperature profile on the evolution of crystalline microstructures were studied. With scanning electron microscopy(SEM), the transition of crystalline morphology from ring-banded structure to oriented lamellae was observed with decreasing mold temperature, and the oriented lamellae were formed at the sub-skin layer of the samples at the lowest mold temperature, which was further testified by differential scanning calorimetry(DSC). With the decline of mold temperature, the degree of orientation, obtained from two-dimensional small angle X-ray scattering(2D-SAXS), was increased and long periods rose a little. Thus, decreasing mold temperature was beneficial to the formation of orientation structures because the relaxation of chains was weakened.     

Ti-doping induced antiferroelectric to ferroelectric phase transition and electrical properties in Sm-PbZrO3 thin films

The antiferroelectric (Pb_0.985Sm_0.01) (Zr_1-xTi_x)O₃ (Ti-PSZO) thin films were synthesized on Pt(111)/Ti/SiO₂/Si substrates using a chemical solution deposition method. The films were crystallized in the perovskite phase with a preferential orientation along (111) direction. With Ti doping in PSZO, a gradual transformation from antiferroelectric to ferroelectric phase transition was noticed at room temperature owing to the Ti doping induced lattice distortion. The phase transition has been confirmed through the P - E hysteresis loops, X-ray diffraction (peak shifting), capacitance-voltage measurements, and Raman scattering analysis. The thin film with Ti = 0.15 doping displayed a ferroelectric behavior with high dielectric constant and large dielectric tunability of about 62%. Also, Ti doping altered the Curie temperature (T_c) and enhanced the order of dielectric diffuseness. It is believed that Ti-doping in PSZO is an effective way to induce an antiferroelectric - ferroelectric phase transition and to tailor the electrical characteristics of PSZO thin films.     

Modeling flow induced crystallization in film casting of polypropylene

Data from iPP film casting experiments served as a basis to model the effect of flow on polymer crystallization kinetics. These data describe the temperature, width, velocity and crystallinity distributions along the drawing direction under conditions permitting crystallization along the draw length.In order to model the effect of flow on crystallization kinetics, a modification of a previously defined quiescent kinetic model was adopted. This modification consisted in using a higher melting temperature than in the original quiescent model. The reason for the modification was to account for an increase of crystallization temperature due to entropy decrease of the flowing melt. This entropy decrease was calculated from the molecular orientation on the basis of rubber elasticity theory applied to the entangled and elongated melt. The evolution of molecular orientation (elongation) during the film casting experiments was calculated using a non-linear dumbbell model which considers the relaxation time, obtained from normal stress difference and viscosity functions, to be a function of the deformation rate.The comparison between experimental distributions and model based crystallinity distributions was satisfactory.     

On reorienting graphs by pushing down maximal vertices—II

We provide a new proof of Propp's Theorem that the set of orientations of a graph G with a given flow difference can be made into a distributive lattice by allowing all vertices except a distinguished sink vertex to be pushed down. The method used allows us to determine the irreducible elements of this lattice and describe how the lattice changes if the sink varies.     

Synthesis and properties of the octaethylporphyrin-dihexylbithiophene-pyridine system (OEP-DHBTh-Py) connected with diacetylene linkage. Proton-mediated and heat-driven spectral changes

Orientational isomers of the octaethylporphyrin-dihexylbithiophene-pyridine system (OEP-DHBTh-Py) connected with the diacetylene linkage were synthesized. The spectral measurements were performed under neutral and acidic conditions, clearly proving that the orientation of DHBTh affects not only the electronic structures of OEP-DHBTh-Py but also their proton-mediated spectral changes.     

Methodologies for the characterisation of glass fibre orientation and distribution in large components moulded from sheet molding compounds (SMC)

Sheet Moulding Compounds (SMC) made of unsaturated polyester resin and other additives, reinforced with glass fibres, have emerged as a substitute for steel automotive outer panels. For a better understanding of the compression moulding of SMC, it is necessary to characterise the flow of material and particularly of the glass fibres. The aim of this work is to develop methodologies for characterising local mass fraction and orientation of short glass fibres in compression moulded composite components such as SMC. Pyrolysis, photographs by transmission of visible light and X-ray photographs analysed with homemade software for characterising the orientation give valuable and interesting information concerning the flow of fibres.     

Enantiomeric excess measurements in weakly oriented chiral liquid crystal solvents through 2D H selective refocusing experiments

In this article, a simple and robust method is proposed for simplifying the analysis of proton spectra of molecules dissolved in weakly oriented chiral media. The NMR approach investigated is based on the use of proton selective refocusing 2D experiments (SERF) to measure proton–proton dipolar couplings from unresolved lines. This technique is applied to the case of enantiomers dissolved in chiral polypeptide liquid crystals. It is shown that an accurate determination of enantiomeric excess is possible within a short experimental time.     

可定向闭曲面上保定向的周期映射

讨论可定向闭曲面上保定向周期映射的共轭类分类问题.Kulkarni(1997)指出:亏格g大于3时,曲面上任意周期大于或等于4g的周期映射共轭于两类周期映射中某个映射的幂.之后Hirose(2010)得到:亏格g大于12时,曲面上任意周期大于或等于3g的周期映射共轭于4类周期映射中某个映射的幂.本文在此基础上研究了周期大于或等于3(g-1)的情形:当亏格g大于21时,得到了和Hirose相似的结论,且找出了更多不能被包含在前面所讲的4类周期映射中的情形.