Age-related differences in visual scanning at median-divided highway intersections in rural areas

The objective of this study was to examine age-related differences in visual scanning as drivers performed three separate maneuvers (going straight across, making a left and right turn) at two median-divided highway intersections with different crash frequencies. An on-road study was conducted with 60 drivers in three age groups: younger (18-25), middle-aged (35-55), and older (65-80). The study consisted of two between-subject (age and gender) and two within-subject variables (drive maneuver and intersection type). Drivers’ behavior was measured by the proportion of time they visually sampled towards the left, right and rearview mirror, and by an entropy rate representative of randomness in visual scanning. The results showed that older and younger drivers do not utilize their full scanning range when compared to middle-aged drivers, as indicated by lower entropy rate and the tendency to check fewer areas before executing a maneuver through the intersections. This trend was more obvious during left and right turn maneuvers indicating a greater likelihood to miss an unexpected event. Older drivers had a significantly smaller proportion of visual sampling to the left and right during intersection negotiations when compared to younger and middle-aged drivers. Older and younger drivers checked the rearview mirror significantly less when compared to middle-aged drivers.     

Miscibility of poly (etherimide) and poly (butylene naphthalate) blends

Summary Differential scanning calorimeter (DSC), optical microscopy (OM) and scanning electron microscopy (SEM) were performed to characterize the miscibility of a blend system comprising poly (butylene naphthalate) (PBN) and poly (ether imide) (PEI). DSC scans showed there was only one single Tg for each blend and the glass transitions increase monotonously with the increase of PEI content. The glass transition temperatures of the blends fitted the Fox equation well implying that the blends exhibited fine segmental scale of mixing. No lower critical solution temperature (LCST) was observed by OM for the blends. SEM micrographs showed the fracture surface of quenched sample exhibited a homogeneous structure. No obvious IR peak shift of C=O absorption at 1780 cm⁻¹ was observed suggesting a relatively low level of specific interaction between two molecules. It was concluded that these blends were miscible with non-specific intermolecular interactions. Received: 5 January 2001/Accepted: 27 February 2001     

Modification of poly(methyl methacrylate) by keV Ar deposition

Classical molecular dynamics simulations are used to examine 1 keV Ar atom bombardment on the surface of poly(methyl methacrylate) (PMMA), which induces sputtering and chemical modifications to the surface. The simulations are carried out at various surface temperatures that range from 200 to 600 K. The results indicate that different fragments of PMMA, as characterized by their mass, are preferentially sputtered from the surface at the various temperatures considered. In addition, the simulations predict that small fragments are produced by the high energy deposition process. However, larger sized fragments are generated when the surface temperature is close to the glass transition temperature of PMMA. The atomic-scale processes by which these occur are elucidated by the simulations.     

Fabrication and properties of degradable poly(amino acid)/nano hydroxyapatite bioactive composite

Poly(amino acid)/nano hydroxyapatite (PAA/n-HA) bioactive composite was prepared by in situ melting polymerization. The composition, structure and morphology as well as glass transition temperature (T_g), dynamic mechanical properties of the PAA/n-HA composite were characterized by infrared spectrometer, X-ray diffractometer, X-ray photoelectron spectroscopy, scanning electron microscope, differential scanning calorimeter, and dynamic mechanical analyzer. The results indicated that the n-HA particles were uniformly distributed into PAA matrix and some interactions were found at the interface between PAA and n-HA, and the crystallinity of PAA in the composite decreased with the increase of n-HA content. The T_g and storage modulus of the composite increased with increasing n-HA content, demonstrating that the n-HA content had obvious effects on the crystallization kinetic parameters and thermo properties of the PAA/n-HA composite. In addition, the n-HA amount had evident effects on the degradation of the PAA/n-HA composite in phosphate buffered saline (PBS), and the weight loss ratio of the composite decreased with the increase with n-HA content. The pH value of the medium was stable around 7.40 after the composite immersion into PBS for 8 weeks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Design of NPR DFT-Modulated Filter Banks via Iterative Updating Algorithm

In this paper, an efficient algorithm is proposed to design nearly-perfect-reconstruction (NPR) DFT-modulated filter banks. First, the perfect-reconstruction (PR) condition of the oversampled DFT-modulated filter banks in the frequency domain is transformed into a set of quadratic equations with respect to the prototype filter (PF) in the time domain. Second, the design problem is formulated as an unconstrained optimization problem that involves PR condition and stopband energy of the PF. With the gradient vector of the objective function, an efficient iterative algorithm is presented to design the PF, which is updated with linear matrix equations at each iteration. The algorithm is identified as a modified Newton’s method, and its convergence is proved. Numerical examples and comparison with many other existing methods are included to demonstrate the effectiveness of the proposed method.     

One‐step synthesis of polyaniline nanofibers decorated with silver

Polyaniline (PANI)/silver (Ag) nanocomposites containing PANI nanofibers decorated with well‐dispersed Ag nanoparticles were obtained with interfacial polymerization. It was interesting that silver nitride affected not only the diameter and crystallinity of the PANI nanofibers but also their room‐temperature conductivity. The conductivity increased with increasing Ag loading up to 10 (molar ratio of aniline to silver nitride), but the conductivity moderately decreased with further increasing Ag loading. Scanning electron microscopy and X‐ray diffraction analysis results indicate that the diameter of the PANI nanofibers became smaller and smaller, and their crystallinity got better and better with increasing Ag loading. However, Fourier transform infrared analysis proved that the balance of oxidized and reduced units of PANI became big with increasing Ag loading, which may have resulted in the decreasing conductivity of PANI. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

抗紫外线染料研究进展

简单介绍了紫外线对人体的影响和织物抗紫外线的机理。对近年来染料在纺织品抗紫外线方面的研究进行了综述。展望了抗紫外线染料的发展前景。     

酸性镀铜液中硫酸铜的自动电位滴定

研究了用自动电位滴定法测定酸性镀铜液中硫酸铜的条件和方法。实验结果表明,在pH=10的氨-铵缓冲介质中,在Ca-EDTA共存下,以EDTA作滴定剂,用钙离子选择性电极作指示电极,以饱和甘汞电极作参比电极,滴定Cu2+,具有明显的电位突跃和清晰的滴定终点,该方法具有较高的准确度和精密度。应用于酸性镀铜液中硫酸铜的分析,方法简便快捷,能在4min内打印出结果。     

Effect of annealing atmosphere on the structure and dielectric properties of unfilled tungsten bronze ceramics Ba4PrFe0.5Nb9.5O30

Unfilled tungsten bronze ceramics with the nominal formula Ba₄PrFe_0.5Nb_9.5O₃₀ were synthesized via the standard solid-state sintering route, and the effects of oxygen vacancies on the dielectric and electrical properties were investigated in addition to the structure. Room-temperature X-ray diffraction showed that the N₂-annealed sample had the largest cell volume. Low-temperature spectrum showed that N₂ annealing rendered the dielectric constant and dielectric loss more frequency dispersive, whereas O₂ annealing inhibited the frequency dispersion. The dc conductivity of all the samples originated from the electrons produced in the second ionization of oxygen vacancies and was most likely controlled by a mixed conduction mechanism of the electron and oxygen-vacancy ions. The N₂-annealed sample has the highest dc conductivity owing to its high concentration of oxygen vacancies. The broadening of the Raman lines and the decrease of Raman intensity for the N₂-annealed sample originated from a significant structural disorder. X-ray photoelectron spectra demonstrated that the increased oxygen vacancies caused by the change of valences of Fe and Pr ions contributed to the structural disorder.     

Evaluation on Dorsey Method in Surface Tension Measurement of Solder Liquids Containing Surfactants

With the purpose of developing a feasible approach for measuring the surface tension of solders containing surfactants, the surface tension of Sn–3Ag–0.5Cu–xP solder alloys, with various drop sizes as well as different phosphorus (P) content, was evaluated using the Dorsey method based on the sessile drop test. The results show that the accuracy of the surface tension calculations depends on both of sessile drop size and the liquid metal composition. With a proper drop size, in the range of 4.5 mm to 5.3 mm in equivalent spherical diameters, the deviation of the surface tension calculation can be limited to 1.43 mN·m^?1 and 6.30 mN·m^?1 for SnAgCu and SnAgCu–P, respectively. The surface tension of SnAgCu–xP solder alloys decreases quickly to a minimum value when the P content reaches 0.5 wt% and subsequently increases slowly with the P content further increasing. The formation of a P-enriched surface layer and Sn₄P₃ intermetallic phases is regarded to be responsible for the decreasing and subsequent increasing of surface tension, respectively.