Formation mechanism of incubation layers in the initial stage of microcrystalline silicon growth by PECVD

The incubation layers in microcrystalline silicon films （μc-Si：H） are studied in detail. The incubation layers in μc- Si：H films are investigated by biracial Raman spectra, and the results indicate that either decreasing silane concentration （SC） or increasing plasma power can reduce the thickness of incubation layer. The analysis of the in-situ diagnosis by plasma optical emission spectrum （OES） shows that the emission intensities of the SiH＊（412 nm） and Hα （656 nm） lines are time-dependent, thus SiH＊/Hα ratio is of temporal evolution. The variation of SiH＊/Hα ratio can indicate the variation in relative concentration of precursor and atomic hydrogen in the plasma. And the atomic hydrogen plays a crucial role in the formation of μc-Si：H; thus, with the plasma excited, the temporal-evolution SiH＊/Hα ratio has a great influence on the formation of an incubation layer in the initial growth stage. The fact that decreasing the SC or increasing the plasma power can decrease the SIH＊/Hα ratio is used to explain why the thickness of incubation layer can reduce with decreasing the SC or increasing the plasma power.

Tuning Effect of N_2 on Atmospheric-Pressure Cold Plasma CVD of TiO_2 Photocatalytic Films

To deposit TiO2 films through plasma CVD, the partial pressure ratio of O2 to TIC14 should be greater than the stoichiometric ratio （PO2/PTiCl4 〉 1）. However, this may lead to the formation of powder instead of film on the substrate when using volume dielectric barrier discharge （volume-DBD） at atmospheric pressure. In this study, by adding N2 into the working gas Ar, TiO2 photocatalytic films were successfully fabricated in the presence of excess O2 （PO2/PTiC14 = 2.6） by using a wire-to-plate atmospheric-pressure volume-DBD. The tuning effect of N2 on the deposition of TiO2 film was studied in detail. The results showed that by increasing the N2 content, the deposition rate and particle size of the TiO2 film were reduced, and its photocatalytic activity was enhanced. The tuning mechanism of N2 is further discussed.

Preparation of Copper Nanoparticles Using Dielectric Barrier Discharge at Atmospheric Pressure and its Mechanism

Dielectric barrier discharge （DBD） cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide （CuO）. Power X-ray diffraction （XRD） was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra （OES） were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen （H） radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles.

OH and O radicals production in atmospheric pressure air/Ar/H_2O gliding arc discharge plasma jet

Atmospheric pressure air/Ar/H_2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic（OES） diagnostic technique is used for the characterization of plasmas and for identifications of OH and O radicals along with other species in the plasmas. The OES diagnostic technique reveals the excitation Tx？≈？5550–9000 K, rotational Tr？≈？1350–2700 K and gas Tg？≈？850–1600 K temperatures, and electron density n？（1.1-1.9） ′101 4 cm^（-3） e under different experimental conditions. The production and destruction of OH and O radicals are investigated as functions of applied voltage and air flow rate. Relative intensities of OH and O radicals indicate that their production rates are increased with increasing Ar content in the gas mixture and applied voltage. nereveals that the higher densities of OH and O radicals are produced in the discharge due to more effective electron impact dissociation of H_2O and O_2 molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced n e.The productions of OH and O are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties. Besides, Tgsignificantly reduces with the enhanced air flow rate. This investigation reveals that Ar plays a significant role in the production of OH and O radicals.

Atmospheric Pressure Plasma Jet in Organic Solution:Spectra,Degradation Effects of Solution Flow Rate and Initial pH Value

The organic compounds of p-nitrophenol （PNP） solution was treated by the active species generated in a stirred reactor by an atmospheric pressure plasma jet （APPJ）. The emission intensities of hydroxyl （OH）, oxygen （O）, nitric oxide （NO）, hydrogen （H） and molecular （N2） were measured by optical emission spectroscopy （OES）. The relations between the flow rates of the PNP solution and degradation, the degradation effects and initial pH value of the solution were also investigated. Experimental results show that there exist intense emissions of O （777.1 nm）, N（337.1 nm）, OH （306-310 nm） and NO band （200-290 nm） in the region of plasma. Given the treatment time and gas flow rate, the degradation increased as a function of discharge energy and solution flow rate, respectively. The solution flow rate for the most efficient degradation ranged from 1.414 m/s to 1.702 m/s, and contributed very little when it exceeded 2.199 m/s. This indicates the existence of diffusion-controlled reactions at a low solution flow rate and activation- controlled reactions at a high solution flow rate. Moreover, increasing or decreasing the initial pH value of neutral PNP solution （pH=5.95） could improve the degradation efficiency. Treated by APPJ, the PNP solutions with different initial pH values of 5.95, 7.47 and 2.78 turned more acidic in the end, while the neutral solution had the lowest degradation efficiency. This work clearly demonstrates the close coupling of active species, photolysis of ultraviolet, the organic solution flow rate and the initial pH value, and thus is helpful in the study of the mechanism and application of plasma in wastewater treatment.

套圈在腹腔镜下子宫肌壁间肌瘤剔除术中的应用

目的探讨套圈应用于腹腔镜下子宫肌壁间肌瘤剔除术的安全性和有效性。方法对我院2008年10月～2010年3月腹腔镜子宫肌壁间肌瘤剔除术中子宫切口两种处理方法的手术时间、术中出血量、术后恢复情况进行对比分析。2009年7月15日前43例均行子宫切口常规缝合,剔除肌瘤,子宫切口双层缝合,先缝合内1/2肌层关闭瘤腔,再缝合外1/2浆肌层;以后46例先套圈再缝合,分离肌瘤约1/2,用1-0可吸收线自制套圈,套于瘤体基底部,抽紧,分离瘤体,在分离过程中逐步抽紧套圈线,直至瘤体完全切除,子宫切口单层缝合。结果与常规缝合组相比,先套圈再缝合组出血量少[(112.0±29.5)ml vs.(176.6±40.4)ml,t=8.665,P=0.000],手术时间短[(73.3±13.9)min vs.(91.8±15.2)min,t=5.977,P=0.000]。2组术后发热比例差异无显著性。结论腹腔镜下子宫肌壁间肌瘤剔除术中子宫切口先套圈再缝合更省时,更安全。

腹腔镜下套圈法行外突型子宫肌壁间肌瘤剔除术的临床研究

目的探讨腹腔镜下套圈法行外突型子宫肌壁间肌瘤剔除术的临床价值。方法选取我院2015年1月至2017年6月收治的50例外突型子宫肌壁间肌瘤患者,随机分为套圈组和缝合组各25例。比较两组患者的手术成功率、手术时间、术中出血量、住院时间、术后并发症发生率。结果两组患者的手术成功率、住院时间比较差异均无统计学意义(P>0.05)。套圈组的手术时间和术中出血量分别为(50.9±12.4)min、(31.7±10.8)m L,明显优于对照组的(91.2±16.5)min、(80.3±17.6)m L(P<0.05)。套圈组术后并发症发生率为8.0%,明显低于缝合组的36.0%(P<0.05)。结论腹腔镜下套圈法行外突型子宫肌壁间肌瘤剔除术,可缩短手术时间,减少术中出血量,降低术后并发症发生率,安全有效,值得推广应用。

Optical emission spectroscopy diagnosis of energetic Ar ions in synthesis of SiC polytypes by DC arc discharge plasma

Silicon carbides are basilic ceramics with proper bandgaps （2.4-3.3 eV） and unique optical properties. SiC@C monocrystal nanocapsules with different morphologies, sizes, and crystal types were synthesized via the fast and facile direct current （DC） arc discharge plasma method. The influence of Ar atmosphere on the formation of nanocrystal SiC polytypes was investigated by optical emission spectroscopy （OES） diagnoses on the arc discharge plasma. Boltzmann＇s plot was used to estimate the temperatures of plasma containing different Ar concentrations as 10,582 K （in 2 × 10^4 Pa of Ar partial pressure） and 14,523 K （in 4 × 10^4 Pa of Ar partial pressure）. It was found that higher energy state of plasma favors the ionization of carbon atoms and promotes the formation of α-SiC, while β-SiC is generally coexistent. Heat-treatment in air was applied to remove the carbon species in as-prepared SiC nanopowders. Thus, the intrinsic characters of SiC polytypes reappeared in the ultraviolet-visible （UV-vis） light absorbance. It was experimentally revealed that the direct bandgap of SiC is 5.72 eV, the indirect bandgap of β-SiC （3C） is 3.13 eV, and the indirect bandgap of α-SiC （6H） is 3.32 eV; visible quantum confinement effect is predicted for these polytypic SiC nanocrystals.