No abstract

Economic instruments such as extended producer responsibility(EPR) and green purchasing network (GPN) are conducive to environmentally sound and sustainable development in our society. The implementation of EPR and GPN would require tool such as environmental labels and declarations(EL). EL has been used to encourage the demand for and supply of those products that cause less stress on the environment, thereby stimulating the potential for market-driven continuous environmental improvement. However, EL may act as potential trade barriers. Harmonization of EL by international organization for standardization(ISO) results in EL standards termed the ISO 14020 series. The contents of the ISO 14020 series and its implications on the market are discussed.

No abstract

No abstract

Second harmonic Maker-fringe signals, measured for determination of second-order nonlinear coefficients of arrayed ZnO nanorods, were analyzed with an improved method. In this analysis, multiple reflections and interferences of fundamental and second harmonic waves were taken into account within ZnO nanorod layer, which thickness approaches the wavelength of the incident beam. Nanostructured semiconducting materials possess unique photonic and electronic properties due to their quantum size effects and field enhancements. Such materials, exhibiting large optical nonlinearities and fast response times, have been extensively studied for potential photonic applications [1,2]. Especially, ZnO is a wide bandgap (-3.4 eV) semiconductor, which can be grown with nanostructures using different techniques [2][3][4]. The well-known Maker-fringe technique, in which polarization-dependent second harmonic waves are detected in dependence of the incident angle of fundamental waves, is often used to evaluate second-order nonlinear optical coefficients of various materials. Unlike thick bulk materials, multiple reflections and FabryPerot interferences of fundamental and second harmonic (SH) waves can not be neglected more if the thickness of the sample is close to the wavelength of incident fundamental waves.In the present work, we estimated second-order nonlinear optical coefficients of three different ZnO nanorod layers by analyzing angular-dependent SH signals, which could not be fitted by conventional equations, with an improved method using propagation and density matrices. The sample was regarded as a multi-layered medium consisting of air, ZnO nanorods, ITO, glass substrate and air. Multiple reflections and interferences of reflected waves at each boundary surface were taken into account. The schematic of propagation of fundamental and SH waves in the multi-layered sample is depicted in Fig. 1.