Note on André's reflection principle

This note generalizes André's reflection principle to give a new combinatorial proof of a formula for the number of lattice paths lying within certain trapezoids.     

A structured light-based system for human heads

The 3-D modeling of heads by using optical triangulation techniques is of great interest in the context of virtual reality, telecommunication and computer animation. This paper presents a structured light-based system mainly for human heads. It is named “3-D Laser Color Scanner” (3DLCS). A 3-D model is obtained with a cylindrical scan. The laser beam is switched on and off using a “light valve” and two successive CCD frames are captured, one with the laser line showing and one without. We can simplify the laser line extracting by subtracting these two images.In this system, two CCD cameras are used to avoid occlusion problems. Color information is read from the CCD when the laser light is absent. Since traditional laser scanner will miss the range data in the low-reflectance areas such as the hair area of human head, a shape from silhouette algorithm is presented to overcome this problem. Finally, we give some results using our system. The resulting model is suitable for many applications.     

Binding of erbium(III) and holmium(III) to native and chemically modified alfalfa biomass: a spectroscopic investigation

Traditional treatment methods used to clean-up heavy metal contamination of soils and waters are cost intensive whereas more cost effective methods need to be developed. The use of plant materials to remediate heavy contamination has been studied for the past two decades. This technique has shown much promise for many of the common heavy metal contaminants, but few studies have focused on the lanthanide series elements. By investigating the binding and interactions of the lanthanide elements to alfalfa biomass, a more complete understanding of the binding mechanisms and the interactions of heavy metals with biomaterials can be obtained. Different chemical functional groups on the alfalfa biomass, carboxyl, amino, sulfur, and ester groups, were modified to investigate the binding mechanisms of erbium(III) and holmium(III). Batch experiments were performed with native and chemically modified alfalfa biomass suggesting that the carboxyl groups play a major role in the binding of erbium(III) and holmium(III) to the alfalfa biomass. In addition, X-ray absorption spectroscopy (XAS) studies corroborated the data obtained from the batch experiments.     

Novel optical film sensor design based on p-polarized reflectance

A new scheme of optical film sensor is presented. The sensor is based on p-polarized reflectance, consisting of a sensing coated substrate, is easily optimized for maximum sensitivity in different applications. The resolutions of refractive index n_f, extinction coefficient k_f and thickness h_f of the sensitive films are predicted to be 10⁻⁷, 10⁻⁵ and 10⁻³ nm, respectively. Experimentally, we selected the sol–gel derived SnO₂ films as gas-sensitive films and conducted preliminary gas-sensing test. The results indicate that novel optical film sensor scheme has higher sensitivity, and the detection sensitivity is available to 10⁻¹ ppm on the condition of optimum optical parameters and incident angle.     

Two types of the effective mass divergence and the Grüneisen ratio in heavy-fermion metals

The behavior of the specific heat c_p, effective mass M^*, and the thermal expansion coefficient of a Fermi system located near the fermion condensation quantum phase transition (FCQPT) is considered. We observe the first type behavior if the system is close to FCQPT: the specific heat , , while the thermal expansion coefficient . Thus, the Grüneisen ratio Γ(T)=/c_p does not diverges. At the transition region, where the system passes over from the non-Fermi liquid to the Landau Fermi liquid, the ratio diverges as . When the system becomes the Landau Fermi liquid, Γ(T,r)∝1/r, with r being a distance from the quantum critical point. Provided the system has undergone FCQPT, the second type takes place: the specific heat behaves as , M^*∝1/T, and =a+bT with a,b being constants. Again, the Grüneisen ratio diverges as .     

Standing waves, clustering, and phase waves in 1D simulations of kinetic relaxation oscillations in NO+NH3 on Pt(1 0 0) coupled by diffusion

The Lombardo–Imbihl–Fink (LFI) ODE model of the NO+NH₃ reaction on a Pt(1 0 0) surface shows stable relaxation oscillations with very sharp transitions for temperatures T between 404 and 433 K. Here we study numerically the effect of linear diffusive coupling of these oscillators in one spatial dimension. Depending on the parameters and initial conditions we find a rich variety of spatio-temporal patterns which we group into four main regimes: bulk oscillations (BOs), standing waves (SW), phase clusters (PC), and phase waves (PW). Two key ingredients for SW and PC are identified, namely the relaxation type of the ODE oscillations and a nonlocal (and nonglobal) coupling due to relatively fast diffusion of the kinetically slaved variables NH₃ and H. In particular, the latter replaces the global coupling through the gas phase used to obtain SW and PC in models of related surface reactions. The PW exist only under the assumption of (relatively) slow diffusion of NH₃ and H.     

Radiation induced decomposition of halogenated organic compounds in water

Decomposition by ionizing radiations of p-chlorophenol and tetrachloroethylene in synthetic water samples at about 2 mg Cl L⁻¹, has been studied on laboratory-scale experiments. Bicarbonate/carbonate and nitrate ions, at two concentration levels (20 and 200 mg HCO₃⁻¹ and 1 and 50 mg NO₃⁻L⁻) were added to synthetic samples in order to evaluate their influence on decomposition yield. At 5 kGy γ dose level, a quantitative degradation of p-chlorophenol is obtained whereas only qualitative consideration can be drawn on tetracholoroethylene. Comparative study with respect to degradation of p-cholophenol solutions (about 2 mg Cl L⁻¹) by γ-rays and electron beam irradiation treatment at 0.5 kGy dose level, are in progress; preliminary results indicate that irradiation with γ-rays seems to be more efficient in terms of removal efficiency respect to electron beams source.     

Gamma radiation effects on an amine antioxidant added in an ethylene-propylene copolymer

The aim of this work was to compare the gamma radiation induced effects on samples of an ethylene-propylene copolymer antioxidant free with samples loaded with an antioxidant characterised by the presence of an -NH functional group. The employed techniques were Electron Spin Resonance spectroscopy (ESR) and High Performance Liquid Chromatography (HPLC). Stable radicals R---NO° due to the interaction of free radicals produced in the irradiated polymer with the antioxidant have been observed by ESR at room temperature. The time evolution of the ESR signals following the irradiation was examined at different doses. The amount of antioxidant not involved in the oxidation reactions has been determined using HPLC.     

The practice for eight-year operation of the cobalt-60 irradiation facility at Beijing Radiation Application Research Center

The radiation facility was made by Sulzer Company in Switzerland. The designed capacity is 3.7 × 10¹⁶Bq( 1MCi) and 12.21 × 10¹⁵Bq(330kCi)of Cobalt -60 source was loaded at the first phase. Current cobalt -60 source-loading is 2.4 × 10¹⁶Bq(650kCi). The equipment assembling and installation regulating and testing were completed at the end of 1988. The facility was put into commissioning in 1989. It operates 7000–8000 hours per year. The facility has been utilized to carry out many research work and irradiate many kinds of items. Lots of economical benefits have been gained since then. Now it is becoming a radiation processing model base in China. This paper summarized the strong and weak points of the design of the facility through in eight years' practice and analysed the economical benefits.     

The effect of UV light on the thermooxidative stability of linear low density polyethylene films crosslinked by ionizing radiation

The effect of ultraviolet (UV) light on the thermooxidative stability of Linear Low Density Polyethylene(LLDPE) films was studied. LLDPE was stabilized with phenolic type antioxidant known as Irganox 1010, hindered amine light stabilizer known as Chimmasorb 944 and phenolic type gamma stabilizer. The influence of these additives on the thermooxidative stability of gamma and UV irradiated LLDPE were investigated by isothermal Differential Scanning Calorimeter (DSC). The oxidation induction time (OIT) experiments indicate that antirad free LLDPE films which contains antioxidant and UV stabilizer are more sensitive to gamma and UV radiation. On the other hand, films which contain antirad and irradiated to different doses of γ-radiation demonstrated improved thermooxidative stability.