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This article presents an experiment of rocket-triggered lightning to 10 kV power distribution lines and the characteristics of lightning current at Guangzhou Field Experiment Site for Lightning Research and Testing during 2018–2019. The return strokes (RSs) current of the triggered-lightning flashes in this study exhibits a shorter half-peak width and similar risetime and peak current compared with those of subsequent strokes current from natural lightning. The peak current of RSs shows strong power function correlations with charge transfer within 1 ms and action integral within 1 ms of RSs, with R2 of 0.80 and 0.92, respectively. Besides, the peak current of RSs is proportional to the average rate rise of RSs (dI/dt). We recommend the double HEIDLER function to simulate the RS current and provide accurate raw data for the study of lightning protection.

Heterogeneous catalysts have made outstanding advancements in pollutants elimination as well as energy and materials production over the past decades. Single-atom alloys (SAAs) are novel environmental catalysts prepared by dispersing single metal atoms on other metals. Integrating the advantages of single atom and alloys, SAAs can maximize atom utilization, reduce the use of noble metals and enhance catalytic performances. The synergistic, electronic and geometric effects of SAAs are effective to modulate the activation energy and adsorption strength, consequently breaking linear scaling relationship as well as offering an excellent catalytic activity and selectivity. Moreover, SAAs possess clear atomic structure, active sites and reaction mechanisms, providing an opportunity to tailor catalytic properties and develop effective environmental catalysts. In this review, we provide the recent progress on synthetic strategies, catalytic properties and catalyst design of SAAs. Furthermore, the applications of SAAs in environmental catalysis are introduced towards catalytic conversion and elimination of different air pollutants in many important reactions including (electrochemical) oxidation of volatile organic compounds (VOCs), dehydrogenation of VOCs, CO2 conversion, NOx reduction, CO oxidation, SO3 decomposition, etc. Finally, challenges and opportunities of SAAs in a broad environmental field are proposed.

Conventional diffraction gratings are designed so that most of the light striking the grating is diffracted toward the “first-order beam” direction, but in practice, some of the light may be diffracted towards the “second-order beam” direction, so that the light striking a particular sensor pixel may be a combination of both first- and second-order components. This causes errors in the output of diffraction-grating based UV–visible spectrometers. A new method has been developed to correct such errors by calibrating the optical system with a UV-excluded standard (such as an orange tile) and a UV-included standard (such as a white tile). These two calibrations can predict the relationship between first-order-only signals and first-and-second-order combined signals at sensor pixels (nominal wavelengths) where there is second-order light, and thus help correct the second-order diffraction error. This compensation method applied on the reflectance measurement of a set of color ceramic tiles showed significant improvement on the accuracy of the result. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 189–192, 2017

Comparative therapeutic significance of tendon-derived stem cells (TDSCs) and bone marrow mesenchymal stem cells (BMSCs) transplantation to treat ruptured Achilles tendon was studied. Three groups of SD rats comprising 24 rats each, designated as TDSCs and BMSCs, and nontreated were studied for regenerative effects through morpho-histological evaluations and ultimate failure load. For possible mechanism in tendon repair/regeneration through TDSCs and BMSCs, we measured Collagen-I (Col-I), Col-III gene expression level by RT-PCR, and Tenascin-C expression via immunofluorescent assay. TDSCs showed higher agility in tendon healing with better appearance density and well-organized longitudinal fibrous structure, though BMSCs also showed positive effects. Initially the ultimate failure load was considerably higher in TDSCs than other two study groups during the weeks 1 and 2, but at week 4 it attained an average or healthy tendon strength of 30.2 N. Similar higher tendency in Col-I/III gene expression level during weeks 1, 2, and 4 was observed in TDSCs treated group with an upregulation of 1.5-fold and 1.1-fold than the other two study groups. Immunofluorescent assay revealed higher expression of Tenascin-C in TDSCs at week 1, while both TDSCs and BMSCs treated groups showed detectable CM-Dil-labelled cells at week 4. Compared with BMSCs, TDSCs showed higher regenerative potential while treating ruptured Achilles tendons in rats.

By investigating the second-harmonic generation (SHG) of the bulk PbO/B 2 O 3 glass samples with different compositions after thermal poling, it was found that there was an optimal poling temperature for each sample with different compositions and there was also a relation between optimal poling temperature and glass transition temperature. At their own optimal poling temperatures, the samples had different frequency doubling efficiencies with the same applied voltage. We also found that the frequency doubling efficiency of PbO/B 2 O 3 glass increased with the increase of poling voltage. An induced dipole model was proposed to explain the super-quadratic relation between the SHG intensity and the poling voltage.

Polyetherketone (PEK-c) guest–host polymer thin films doped with 3-(1,1-dicyanothenyl)-1-phenyl-4, 5-dihydro-1H-pryazole (DCNP) were prepared. The poling profiles of the polymer film were investigated by using the in situ second-harmonic generation (SHG) measurement. The corona poling condition was optimized by the poling profiles. The second-order nonlinear optical (NLO) coefficient χ 33 (2) =20.86 pm/V at λ=1064 nm was determined by using the Maker fringe method after poling under the optimal poling condition. The temperature stability of the second-order optical properties of the poled polymer film was measured by the in situ SHG intensity probing. Moreover, the relaxation of the electric field-induced polar orientation of the chromophores in the poled polymer film was measured by the thermally stimulated discharge current (TSDC) technique.

The real-time monitoring of the second-harmonic generation (SHG) was used to optimize the poling condition and to study the nonlinear optical (NLO) properties of the polyetherketone (PEK-c) guest-host polymer films. The high second-order NLO coefficient chi(33)((2)) = 11.02 pm/v measured at 1.064 mu m was achieved when the weight percent of DR1 guest in the polymer system is 20%. The NLO activity of the poled DR1/PEK-c polymer film can maintain more than 80% of its initial value when temperature is under 100 degrees C, and the normalized second-order NLO coefficient can maintain more than 85% after 2400 s at 80 degrees C. (C) 2000 Elsevier Science Ltd. All rights reserved.

The innovation and entrepreneurship education emphasizes the cultivation of innovation and entrepreneurship spirit, paying attention to improve the overall quality of innovation and entrepreneurship. Based on the features of Independent college students, this essay tries to start from the training objectives, top-level design, and what’s more in virtue of various types innovative practice carrier within and outside class, through the effective quality assurance system, it is possible to build innovative entrepreneurship education that suit for the Independent college’s practical teaching system.

Second-order nonlinearity (SON) of thermally poled PbO/B2O3 glass was investigated. The SON distribution within the glass was obtained by repeatedly grinding the poled glass and measuring its Maker fringes. After grinding away up to one third of the thickness of the poled sample, i.e., about 300 μm, clear fringes with the interference minimum not equal to zero could still be observed, indicating that the area of SON was not confined within thin layers near the two surfaces. Cathode side grinding and anode side grinding had quite different influences on the SON of the poled sample. A model of the anode-charge-layer dependent bulk electric field distribution was proposed and this electric field was regarded as playing a key role in the generation of a nonuniform bulk SON distribution in PbO/B2O3 glass.

The optical nonlinearity of organic dye-doped poly(methyl methacrylate) (PMMA)–silica-gel hybrid material was investigated by second-harmonic-generation measurement. We found that incorporation of in situ polymerized solgel precursors into the organic dye-doped PMMA significantly improved the nonlinear optical stability of the system. However, improvement of thermal stability occurred only when a sufficient amount of silica gel was incorporated. A structural phase transition from pure polymer to a hybrid system was found near a 10-mol.% silica-gel concentration. The optimum polymer/tetraethoxysilane molar ratio is 2:1 to 1:1.

The uniformity of two-lens illumination system with extended light sources was analyzed. It was found that the using of different focal-length front lens follows the same uniformity-efficiency trend curve.

Sol-gel method was used to prepare SiO2-GeO2 films. By investigating the second-harmonic generation (SHG) signal of the films after plate poling and corona poling, it was found that the SHG intensity of the samples increases with the plate poling voltage. A model of effectivedipole- inducing was proposed to explain the super-quadratic relation between the SHG intensity and the plate poling voltage.

Two stilbene derivatives, DANS (4'-N,N-dimethylamino-nitrostilbene) and CNDS (c-cyano-4'-nitro-4-N,N- dimethyistilbene), were synthesized. The optical properties of organic doped PMMA (polymethyl methacrylate) poledpolymer films were investigated with in situ second-harmonic generation (SHG) measurement and UV-Visible absorptionmeasurement. Optimum corona poling temperatures ofthe polymer films were studied. The second-order susceptibilityof CNDS/PMMA is larger than that of DANS/PMMA, although CNDS molecules in PMMA is less ordered than DANS.The molecular second-order polarizability 3 ofthe CNDS was estimated to be about 1.4x1028esu. The relaxation of SHGintensity of CNDS/PMMA was slower than that of DANSIPMMA. It is concluded that CNDS is a better dopant thanDANS as second-order nonlinear-optical material.Key words: SHG, doped polymer film, corona poling 1. INTRODUCTION Poled polymer films with nonlinear optical (NLO) properties have been extensively studied in the past decade. They haveadvantages of large intrinsic nonlinearities, high damage thresholds, low dielectric constants, ultra fast response speed, andease of processing, which show potential uses in integrated optical devices, such as frequency doubling devices and fastwaveguide electrooptic modulators'. Electric field poling is one of the most commonly used methods to align the guestNLO molecules orderly in host matrices. Both the contact (or parallel plate) poling'3 and corona discharge poling4'5 arefrequently used. Usually, polymer film is first heated to a temperature several degrees above glass transition temperatures,a high voltage is then applied to polymers and kept until the temperature is lowered to room temperature. The polymerthus poled will show second-order optical nonlinearity. Hitherto, many efforts were spend on obtaining large second-ordernonlinear susceptibility and long-term stability by investigation on the guest/host polymeric film system or system of theNLO molecules covalently bonded to the polymer back bone23. In the present paper, in order to investigate the influencesof cyano-group to the nonlinear optical properties of organic molecule, a new organic molecule called a'-cyano-4'-nitro-4