Kinetic study of vibrational energy transfer from a wide range of vibrational levels of O2(X(3)Sigma(g)-, v = 6-12) to CF4

A wide range of vibrational levels of O2(X(3)Sigma(g)(-), v = 6-13) generated in the ultraviolet photolysis of O3 was selectively detected by the laser-induced fluorescence (LIF) technique. The time-resolved LIF-excited B(3)Sigma(u)(-)-X(3)Sigma(g)(-) system in the presence of CF4 has been recorded and analyzed by the integrated profiles method (IPM). The IPM permitted us to determine the rate coefficients k(v)(CF4) for vibrational relaxation of O2(X(3)Sigma(g)(-), v = 6-12) by collisions with CF4. Energy transfer from O2 (v = 6-12) to CF4 is surprisingly efficient compared to that of other polyatomic relaxation partners studied so far. The k(v)(CF4) increases with vibrational quantum number v from [1.5 +/- 0.2(2sigma)] x 10(-12) for v = 6 to [7.3 +/- 1.5(2sigma)] x 10(-11) for v = 12, indicating that the infrared-active nu3 vibrational mode of CF4 mainly governs the energy transfer with O2(X(3)Sigma(g)(-), v = 6-12). The correlation between the rate coefficients and fundamental infrared intensities has been discussed based on a comparison of the efficiency of energy transfer by several collision partners.     

Adsorption of fluoride ions onto carbonaceous materials

The characteristics of fluoride ion adsorption onto carbonaceous materials were derived as adsorption isotherms at different temperatures and in different pH solutions. The fluoride ion was adsorbed into pores in carbonaceous materials produced from wood; the larger the specific surface area, the more fluoride ions adsorbed. Bone char was the most effective adsorbent. The composition of bone char includes calcium phosphate, calcium carbonate, and so on. This suggests that the phosphate ion in bone char was exchanged with a fluoride ion. Moreover, the mechanism of fluoride ion adsorption onto bone char is clearly chemical in nature because the amount of fluoride ion adsorbed onto bone char increased with increasing temperature and decreasing pH. The amount of fluoride ion adsorbed onto bone char was also shown to depend on the concentration of sodium chloride in solution because of the "salting-out" effect. The adsorption of fluoride ion onto bone char is endothermic. Bone char can be utilized to remove fluoride ions from drinking water.     

Molecular Shape Selectivity for Polycyclic Aromatic Compounds on a Core–Shell Octadecylsilica Stationary Phase at Subambient Column Temperatures

Molecular shape selectivity for polycyclic aromatic compounds on a core–shell-type octadecylsilica (ODS) phase at subambient column temperatures was studied in reversed-phase liquid chromatography. The plate height on the core–shell ODS column was relatively stable at subambient column temperatures when compared with that of a conventional ODS column. In order to compare the sample diffusivities in the conventional and core–shell ODS columns, van Deemter plots were prepared. The plate height of the core–shell column was significantly lower than that of conventional column, suggesting an advantageous feature of the core–shell-type stationary phase especially at a high flowrate of the mobile phase. An enhanced molecular shape recognition capability of the core–shell ODS phase was also confirmed at subambient column temperature. The result could be consistent with an improved shape selectivity as normally observed on conventional ODS phases at low temperatures, however, the enhanced molecular shape recognition capability of the core–shell phase enables a good separation between benz[a]anthracene and chrysene at subambient column temperatures. Similar improved shape selectivities for terphenyl isomers were also confirmed on the core–shell phase.     

Determination of Gaseous Formic and Acetic Acids by a Needle-Type Extraction Device coupled to a Gas Chromatography-Barrier Discharge Ionization Detector

Gaseous formic acid (FA) and acetic acid (AA) were concentrated by a needle-type extraction device, and the extracted analytes were determined using a gas chromatography-barrier discharge ionization detector. An activated carbon particle showed good extraction/desorption performance for FA and AA. The limit of quantification for FA and AA was 900 and 180 ng L^?1 at sample volumes of 100 mL, and 150 and 30 ng L^?1 at a sample volume of 600 mL, respectively. The storage performance of the analytes in the extraction needle was quantitatively evaluated at different temperatures, and the applicability of the proposed method to determine FA and AA in air samples was demonstrated.     

Crazing and shear deformation of polymer alloys

Crazing and/or shear yielding mechanisms in multiphase polymer alloys play a critical role in toughening. The present paper describes the use of finite element models (FEM) to simulate the crazing and shear deformation behaviour around the particles embedded in brittle or ductile matrices. The FEM simulation results on the stress distribution reveal that the dilatational stress within the rubber particles is high enough to cavitate. The stability of craze growth can be reached when the compliant particle is incorporated in a brittle matrix. On the other hand, shear yielding around the particle occurs in the equator of the particle/matrix interface when the stress locally exceeds the yield stress of the matrix. This yield-initiation stress increases with the increase in the elastic modulus and Poisson's ratio of the particles. The toughening mechanism, that cavitation occurs first followed by shear yielding to form a neck between the particles, is discussed based on the simulation results for the two-particle model.     

Analog Integrated Circuit for Motion Detection of Approaching Object Based on the Insect Visual System

A network for detection of an approaching object was proposed and fabricated based on the transient response of a descending contralateral movement detector (DCMD) existing in the brain of locusts. The proposed network was constructed with simple analog circuits. The experimental results of a test chip fabricated with a 1.2 $mUm complementary metal-oxide-semiconductor (CMOS) process and the results with a simulation program with integrated circuit emphasis (SPICE) showed that the proposed network is able to detect the approach by generating a peak current just before collision; the peak current allows detection of the approaching velocity and direction without collision. The proposed network could be applied to two-dimensional arrays for three-dimensional motion detection.     

Synthesis of a soluble conjugated cumulene polymer: poly(biphenyl‐4,4′‐diyl‐1,4‐bis(4‐dodecyloxyphenyl)‐buta‐1,2,3‐triene‐1,4‐diyl)

A conjugated polymer with a butatriene segment in the main chain, poly(biphenyl‐4,4′‐diyl‐1,4‐bis(4‐dodecyloxyphenyl)buta‐1,2,3‐triene‐1,4‐diyl), was synthesized from 1,4‐bis(4‐bromophenyl)‐1,4‐bis(4‐dodecyloxyphenyl)buta‐1,2,3‐triene by dehalogenative polycondensation using Ni(cod)₂. The polymer was well soluble in usual organic solvents such as CHCl₃ and THF. Structural analyses and characterizations were carried out by IR, NMR, UV‐Vis, PL, and Raman spectroscopy, as well as electrical conductivity. It is suggested that π‐conjugation is extended to some degree through biphenylylene and butatrienylene linkages.     

Design and control of morphology for high performance polymer alloys

Ductile polymers are significantly toughened by the addition of an elastomeric phase. The rubber phase acts as a stress concentrator, cavitates during the loading process and initiates localized plastic deformation in matrix. This paper deals with the simulation of the deformation behavior of rubber toughened polycarbonate and the fracture process of the embedded rubber particle. A two-dimensional one particle- and two-particle model with varying surface-to-surface interparticle distances are established. The calculation showed that the polymer matrix has plastically deformed before cavitation for the one-particle model whereas cavitation occurs in the elastic state of the matrix for the two-particle model. Cavitation itself is proved to be a change from the particle-system towards a void-system for both cases. The toughness of the post-cavitated void-system is shown to be dependent on the surface-to-surface interparticle distance and the strain-hardening characteristic of the matrix polymer.