Abstract:Visible femtosecond laser is shown to be capable of selectively inactivating a wide spectrum of microorganisms in a wavelength and pulse width dependent manner.However, the mechanism of how visible femtosecond laser affects the viability of different microorganisms is still elusive. In this report, the cellular surface properties, membrane integrity and metabolic rate of Escherichia coli (E.coli) irradiated by a visible femtosecond laser (λ=415nm, pulse width=100fs) with different exposure time were investigated. Our results showed that femtosecond laser treatment for 60 minutes (min) led to cytoplasmic leakage, protein aggregation and alternation of the physical properties of E. coli cell membrane. In comparison, a 10 min exposure of bacteriatofemtosecond laser irradiation induced an immediate reduction of 75% of the glucose-dependent respiratory rate, while the cytoplasmic leakage was not detected.Results from enzymatic assays showed that oxidases and dehydrogenases involving in E.coli respiratory chain exhibited divergent susceptibility after laser irradiation. This early commencement of respiratory inhibition after a short irradiation is presumed to play a dominant effect on the early stage of bacteria inactivation.
Dysprosium(Dy)-doped zinc oxide (Dy:ZnO) thin films were fabricated on c-oriented sapphire substrate by pulsed-laser deposition with doping concentration ranging from 1 to 10 at. %. X-ray diffraction (XRD), Raman-scattering, optical transmission spectroscopy, and spectroscopic ellipsometry revealed incorporation of Dy into ZnO host matrix without secondary phase. Solubility limit of Dy in ZnO under our deposition condition was between 5 and 10 at. % according to XRD and Raman-scattering characteristics. Optical transmission spectroscopy and spectroscopic ellipsometry also showed increase in both transmittance in ultraviolet regime and band gap of Dy:ZnO with increasing Dy density. Zinc vacancies and zinc interstitials were identified by photoluminescence spectroscopy as the defects accompanied with Dy incorporation. Magnetic investigations with a superconducting quantum interference device showed paramagnetism without long-range order for all Dy:ZnO thin films, and a hint of antiferromagnetic alignment of Dy impurities was observed at highest doping concentration—indicating the overall contribution of zinc vacancies and zinc interstitials to magnetic interaction was either neutral or toward antiferromagnetic. From our investigations, Dy:ZnO thin films could be useful for spin alignment and magneto-optical applications.
Superconducting properties were studied on high quality superconductors Ba x (N H 3 )F e 2 Se 2 (T c = 39 K) and Sr x (N H 3 )F e 2 Se 2 (T c = 44 K) prepared by intercalating Ba/Sr atoms into tetragonal β-FeSe by liquid ammonia. The elongated c-axis and almost unchanged a-axis of Ba x (N H 3 )F e 2 Se 2 , comparing with β-FeSe, suggested an unchanged intra-F e 2 Se 2 -layer structure and the T c enhancement is due to a 3D to 2D-like Fermi surface transformation. The superconducting coherent lengths ξ(0), Ginzburg-Landau parameters κ and penetration depths λ(0) obtained from the extrapolated lower and upper critical fields B c1 (0) and B c2 (0) indicates that both compounds are typical type-II superconductors. The temperature dependence of 1/λ 2 (T) of Ba x (N H 3 )F e 2 Se 2 deduced from the low field magnetic susceptibility shows a two-gap s-wave behaviour with superconducting gaps of ∆ 1 = 6.47 meV and ∆ 2 = 1.06 meV.
The purpose of this study was to construct a knowledge-based CAD/KBE system for the optimal design of golf heads. The inability of conventional CAD systems to identify existing knowledge during design and manufacturing processes is a current development bottleneck. Therefore, this study attempted to effectively introduce and integrate KBE technology into a CAD system, so as to achieve the objective of knowledge driven automation (KDA). This study selected golf iron heads with a complex-design surface as the research subject, adopted commercial CAD software (UG/NX) and its secondary development environment as a platform and applied perturbation vectors in the control of NURBS free-form surfaces. We changed the CAD’s entity shapes and physical properties, integrated the optimal principle of design with a CAD solid model, to automatically drive the CAD solid model of golf iron heads according to the design objectives, and constructed a knowledge-based optimal CAD design technology.
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