ELASTIC BEHAVIOR OF PROTEIN-LIKE SINGLE CHAIN

The conformational properties and elastic behaviors of protein-like single chains in the process of tensile elongation were investigated by means of Monte Carlo method. The sequences of protein-like single chains contain two types of residues: hydrophobic (H) and hydrophilic (P). The average conformations and thermodynamics statistical properties of protein-like single chains with various elongation ratio λ were calculated. It was found that the mean-square end-to-end distance r increases with elongation ratio,λ. The tensor eigenvalues ratio of : decreases with elongation ratio λ for short (HP)x protein-like polymers, however, the ratio of : increases with elongation ratioλ,especially for long (H)x sequence. Average energy per bond increases with elongation ratioλ, especially for(H)x protein-like single chains. Helmholtz free energy per bond also increases with elongation ratioλ. Elastic force (f), energy contribution to force (fU) and entropy contribution to force (fs) for different protein-like single chains were also calculated.These investigations may provide some insights into elastic behaviors of proteins.     

Measurement of the magnetic field-dependent refractive index of magnetic fluids in bulk

An optical alignment-free and highly accurate method is employed to measure the magnetic field-dependent refractive index of magnetic fluid(MF) in bulk.The measured refractive index decreases significantly with the increasing magnetic strength and then tends to saturate in the high intensity range.By applying a tunable magnetic field ranging between 0 and 1661 Oe,the maximum shift of the refractive index of MF in bulk iS found to be 0.0231.     

Holographic Storage Properties of In：Fe：Mn：LiNbO3 Crystals

In:Fe:Mn:LiNbO3(LN) crystals were grown in air atmosphere by Czochralski method with different concentration of In (0,1,2,3 mol%) in the melts,while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%,respectively. The location of doping ions was analyzed by Ultraviolet-visible absorption spectra and differential thermal analysis. The diffraction efficiency (η),writing time (τw) and erasure time (τe) of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt,the absorption edge of In:Fe:Mn:LN crystal shifts to the violet firstly and then makes the Einstein shift,the Curie temperature of crystal increases firstly and then decreases,the storage ratio speeds up,diffraction efficiency decreases,and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In:Fe: Mn:LN crystal with different doping concentration of In3+ was investigated,suggesting the In: Fe:Mn:LN crystals are excellent holographic storage materiel with better synthetical properties than Fe:Mn:LN crystals.     

Thermoelectric Properties of Czochralski GeSi Crystal

In order to discuss the application possibility of SiGe crystal in thermoelectric materials,we investigated the thermoelectric properties of several silicon-germanium alloys with different content,orientation and electric conductive type. As discussed in the experiment result,the absolute value of Seebeck coefficient fluctuates from 300 to 600 μV/K in the whole temperature range. In the present paper,the relationship of Seebeck coefficient against content,orientation and electric conductive type is summarized in detail. The Seebeck coefficient of the sample with <111> orientation is smaller than that in <100> at the same temperature. Absolute value of P-type is larger than that of N-type except pure Ge. But as the temperature increases,the absolute value of pure Ge decreases many times as quickly as that of other specimens. In addition,the specimens of bulk GeSi alloy crystals for experiment were grown by the Czochralski method through varying the pulling rate during the growing process.     

Signed words and permutations, V; a sextuple distribution

We calculate the distribution of the sextuple statistic over the hyperoctahedral group B _n that involves the flag-excedance and flag-descent numbers “fexc” and “fdes,” the flag-major index “fmaj,” the positive and negative fixed point numbers “ ” and “ ” and the negative letter number “neg.” Several specializations are considered. In particular, the joint distribution for the pair is explicitly derived.      

Annealing effects on residual stress of HfO2/SiO2 multilayers

HfO2/SiO2 multilayer films were deposited on BK7 glass substrates by electron beam evaporation method.The effects of annealing at the temperature between 200 and 400℃ on residual stresses have been studied.It is found that the residual stress of as-deposited HfO2/SiO2 multilayers is compressive.It becomes tensile after annealing at 200℃,and then the value of tensile stress increases as annealing temperature increases.And cracks appear in the film because tensile stress is too large when the sample is annealed at 400℃.At the same time,the crystallite size increases and interplanar distance decreases with the increase of annealing temperature.The variation of residual stresses is corresponding with the evolution of structures.     

Bipartite entanglement in spin-1/2Heisenberg model

The bipartite entanglement of the two-and three-spin Heisenberg model was investigated by using the concept of negativity.It is found that for the ground-state entanglement of the two-spin model,the negativity always decreases as B increases if A Δ＜y-1,and it may keep a steady value of 0.5in the region of B＜J[(Δ+1)2-y2]1/2if Δ＞y-1,while for that of the three-spin model,the negativity exhibits square wave structures if y=0 or Δ=0.For thermal states,there are two areas showing entanglement,namely,the main region and the sub-region.The main region exists only when Δ＞Δc(Δc1=and(y2-1)/2for the 2-and 3-spin model respectively)and extends in terms of B and T as Δ increases,while the sub-region survives only when y≠0 and shrinks in terms of B and T as Δ increases.     

EFFECT OF PROCESSING METHOD ON THE IMPACT STRENGTH OF POM/TPU/CaCO3 TERNARY COMPOSITES

Polyoxymethylene （POM）/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane （TPU） and inorganic filler, namely, CaCO3, were used to achieve balanced mechanical properties of POM. The dispersion and phase morphology of POM/elastomer/filler composites were found to depend largely on processing method, CaCO3 content in masterbatch and the filler size. Two processing methods were employed to prepare POM/elastomer/filler ternary composites. One is called the one-step method, in which elastomer and the filler directly melt blended with POM matrix. The other is called the two-step method, in which the elastomer and the filler were mixed to get masterbatch first, which was then melt blended with pure POM of different content. The effect of phase morphology and processing method on impact strength was investigated. It was found that the two-step method results in an increase in impact strength but not for the one-step method. Additionally, the impact strength of POM ternary composites decreases with the increase in the size of CaCO3 particles.     

VISCOMETRIC INVESTIGATIONS OF POLYVINYLPYRROLIDONE IN MIXED SOLVENTS AND WITH VARYING TEMPERATURE

The viscosity behavior of polyvinylpyrrolidone (PVP) has been determined at 25℃ in mixed solvents comprising water/dimethylformamide (DMF) and water /methanol (MeOH). Analysis of the data has considered the PVP as being both host and guest polymer in solution. The intrinsic viscosity of PVP in DMF is higher than in water and in MeOH, but also increases in a mixed solvent with high water content because of the effect of polymer-solvent interactions. It was also found that the intrinsic viscosity of PVP at finite concentration, [ηpvp]c decreases with an increase in the concentration of PVP in solution. The viscosity behavior of PVP in a mixed solvent is affected by the concentration-dependent intermolecular excluded volume effect, which can be quantitatively expressed by the parameter, bY, which reflects the shrinkage of PVP chain coils, resulting in a decrease of [ηpvp]c. The effect of temperature on the viscosity behavior of PVP in MeOH shows that the interaction parameter increases up to a maximum value, and then decreases after a certain temperature.     

SYNTHESIS AND CHARACTERIZATION OF COPOLYMER OF 2,5-BIS[（4-METHOXYPHENYL）OXYCARBONYL]STYRENE AND STYRENE WITH HIGH MOLECULAR WEIGHT

The random copolymers of styrene and 2,5-bis[(4-methoxyphenyloxycarbonyl)styrene] (MPCS) with different copolymerization ratio were synthesized by conventional free radical polymerization. The copolymer having high molecular weight was experimentally elucidated using a combination of proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The liquid crystalline behavior of the copolymer was studied using differential scanning calorimetry, X-ray diffractometry and polarized optical microscopy. It was found that the liquid crystalline behavior was dependent on the content of styrene. Experimental results show that the copolymer could turn into a liquid crystalline phase at about 180℃ when the content of styrene was less than 20%. The mechanical properties of the copolymer were also studied. Preliminary results indicate that the tensile strength decreases while the tensile modulus increases as the content of MPCS is increased.