Advanced Materials Research Vols. 779-780

Abstract: The recombinant Saccharomyces cerevisiae expressing human hepatic metallothionein (MT) was constructed for biosorption of cadmium (II). The gene sequence of mt was modified for codon preference of S. cerevisiae and synthesized using chemical method. The maximal biosorption capability of cadmium compounds Cd²⁺ of the recombinant increased more than 25.8% compared with the control. For MT-expressed recombinant strains, a rapid adsorption occurred within the first 30 min with a significant level of Cd²⁺ (55.75mg/g). For comparison, S. cerevisiae cells reach its maximal Cd²⁺ adsorption capacity (45.02 mg/g) until 2h. Furthermore, recombinant strain were able to withstand the toxicity of Cd²⁺ and grow. The results indicated that recombinant should be useful in enhancement the tolerance and biosorption of cadmium in practice.

Abstract: Ordered hexagonally mesoporous molecular sieve Al-MCM-41 with Si/Al (atom) ratio=9 was prepared by hydrothermal synthesis using raw kaolin. X-ray diffraction (XRD), Nitrogen adsorption desorption, Transmission Electron Microscope (TEM) and Energy Dispersive X-ray Detector (EDX) were employed to characterise raw kaolin, calcined kaolin, as-synthesized and calcined Al-MCM-41. The results indicated that characteristic reflections of raw kaolin disappeared after calcination, both of as-synthesized and calcined Al-MCM-41 exhibited well ordered hexagonally mesoporous molecular sieve structure.

Abstract: The microstructure and intergranular corrosion phenomenon were investigated by means of optical imaging,SEM and EDS. Hardness was conducted and electrochemical corrosion properties were researched in 3.5% Nacl solution by electrochemical tester.The result showed, there was no intergranular corrosion phenomenon when the samples underwent cold rolling and stabilization heat treatment;The intergranular corrosion was obviously when the samples were annealed at 180°C for 90h or 150h;The corrosion potential of TO1 state annealed at 180°C for 90h and TO2 state annealed at 180°C for 150h was lower than cold rolled and stabilization heat treatment samples，they were more susceptible to electrochemical corrosion.

Abstract: In order to explore intrinsic relation of continuous, interlocked-dense and gap gradation, this paper studied them by fractal regression analysis, by which a gradation distribution Cartesian coordinate system was established and slope of the gradation was proposed at the same time. In addition, this study adopted gradation fractal Cartesian coordinate system to analysis the internal relations of continuous, interlocked-dense and gap gradation, at the same time verified and analyzed the correlation between the slope of the gradation and asphalt mixture gradation by using reference experimental data. The results show that: the gradation range given by specification can be approximated by a line segment, and the slope of the line can quantitatively reflect the relative thickness of coarse and fine aggregate of asphalt mixture; the gradation range given by specification possess a small proportion in the gradation fractal Cartesian coordinate system, which can be further optimized, and interlocked-dense asphalt mixture is a transitional form of continuous gradation and gap one; for the SAC asphalt mixture gradation, gradation slope has correlation with the formation of gradation skeleton; the Suitable fractal evaluation model for continuous, gap and interlocked-dense gradation was proposed finally. Thereby, the gradation fractal Cartesian coordinate system can not only reflect the relation of continuous, interlocked-dense and gap gradation, but also make it possible that the gradation distribution range in the specification can be expressed in function.

Abstract: Due to the poor reproducibility of traditional plate method, the new knife-edge binding method is chosen to study the effects and the impact law in the crack resistance of the cement mortar with fiber in it. Mortar specimens with an equal volume of ash (0.1%) single-doped, mixed-doped polypropylene fiber and basalt fiber compared to the plain matrix mortar specimens on cracking performance tests within 24h. The results showed that: For the single-doped specimen, the longer the fiber the more excellent of its crack resistance, 30mm basalt fiber mortar improves the cracking performance by 99.1%; for the mixed-doped specimen, with the similar length of polypropylene fibers and basalt fiber mixed in have the optimal performance,the cracking performance improves 99.5%; With mixed fiber types (three kinds of fiber mixed-doped) increasing, although the specimen crack resistance decreased, but still increase the rate of 75.6% in the cracking performance.

Abstract: The article uses a original prefabricated steel bridge as example,briefly introduces the truss element calculation theory. Selecting different reinforcement, modeling of the reinforcement with the Midas / Civil program, emphatically analyze the stress and deflection of the full-bridge under each reinforcement, then comparison the results with the allowable value ,finally select a best reinforcement program,provides reinforcement and repair practical reference for fabricated steel truss bridge.

Abstract: Biodegradable poly (L-lactide-co-ε-caprolactone) (PLA-PCL) copolymers were synthesized via solution polymerization by varying the feed composition of L-lactide (LLA) and ε-caprolactone (ε-CL) (LLA/ ε-CL= 1/0, 1/1, 1/2, and 1/3). PLA-PCL film was produced by solution mixing. The films were characterized by thermal property, mechanical property, and barrier behavior tests to evaluate the effect of the PCL. The differential scanning calorimetry analyses revealed the micro-domain structure in the copolymer. The elongation at break of PLLA was improved significantly (p<0.05) in PLA-PCL copolymer while the tensile strength decreased significantly (p<0.05) with increase of PCL content. WVP of PLA-PCL films significantly decreased (p< 0.05) when compared with that of neat PLLA film. When the feed ratio of PLA-PCL copolymer increased from 1/0 to 1/3, WVP of PLA-PCL films increased from 1.85±0.15 (×10^-11 gm/m²sPa) to 2.83±0.26 (×10^-11 gm/m²sPa). The results showed that PLA-PCL copolymer can be a novel film for food packaging applications.

Abstract: Genome library of toxic Alexandium minutum were constructed. A 1014bp DNA reconstruction fragment was obtained and PCR method testified that this fragment had strong amplification signal in toxic strains while no signal in non-toxic strains. The external sequence of the DNA fragment was analyzed by inverse PCR method, and a 240bp nucleotide sequence which translated into proteins aminophenol was Methionine Aminopeptidase (MAP). The sequence of aminophenol was BLAST in NCBI, and found that it had 97% similarity with Alexandium fundyense. This sequence was exact uniform with the reported sequence in the coding region, but there were three bases mutated in non-coding region behind stop codon. Probably, in the course of growth metabolism of Alexandium minutum, MAP executed different physiological functions and controlled the production of the toxin. In the meantime, map gene induced encoding products of the related poisonous gene, and enabled it has active expressions to starting toxin synthesis.

Abstract: Atomic structures and properties of Ni nanowires are studied by using the generalized simulated annealing method with SuttonChen potential. Amorphous-like, helical, face-centered cubic and defect structures are found for different wire lengths. And from the analyses of the binding energy and angular correlation function (ACF), it is found that the helical structure of the Ni nanowires is the most stable form. With the compression and extension, the nanowires could transform from fcc [11 structure to fcc [110] one.

Abstract: The application of Bayesian estimation methods in the measurement of composite performance is studied in this paper. At first, the traditional measurement method of the composite performance and its disadvantages are described. In addition, the Bayesian method is reviewed and the Bayesian estimation theory is briefly introduced. Then the hardness of the compound interface of 42CrMo-ductile iron composite is obtained by applying the Bayesian estimation theory. In this way, the method has been extended.