LINX联手微软 NAB上首次演示HDTV移动接收

4月7～9日,笔者应邀参加了在美国LasVegas举行的美国“全国广播业者协会”(NAB)2003年度的年会。会上参观了LINX犤注1犦和微软联手进行的HDTV移动接收演示,现将要点报道如下。1微软和LINX合作演示HDTV移动接收两个公司在新闻发布中都提及这是国际上首次演示HDTV的移动接收犤注2犦。1)微软工作人员介绍的有关参试设备及其技术参数(1)收发系统的总体集成由SpectraRep公司(广播业者合办的公司)负责。(2)发射机(Acrodyne公司):Sinclair广播集团下属的LasVegasKFBT-DT电视台,第29频道(UHF波段,频带560～566MHz)。ERP=1MW(若天…     

Anodic oxidation of wastewater containing the Reactive Orange 16 Dye using heavily boron-doped diamond electrodes

Boron-doped diamond (BDD) films grown on the titanium substrate were used to study the electrochemical degradation of Reactive Orange (RO) 16 Dye. The films were produced by hot filament chemical vapor deposition (HFCVD) technique using two different boron concentrations. The growth parameters were controlled to obtain heavily doped diamond films. They were named as E1 and E2 electrodes, with acceptor concentrations of 4.0 and 8.0 × 10²¹ atoms cm⁻³, respectively. The boron levels were evaluated from Mott-Schottky plots also corroborated by Raman's spectra, which characterized the film quality as well as its physical property. Scanning Electron Microscopy showed well-defined microcrystalline grain morphologies with crystal orientation mixtures of (1 1 1) and (1 0 0). The electrode efficiencies were studied from the advanced oxidation process (AOP) to degrade electrochemically the Reactive Orange 16 azo-dye (RO16). The results were analyzed by UV/VIS spectroscopy, total organic carbon (TOC) and high-performance liquid chromatography (HPLC) techniques. From UV/VIS spectra the highest doped electrode (E2) showed the best efficiency for both, the aromaticity reduction and the azo group fracture. These tendencies were confirmed by the TOC and chromatographic measurements. Besides, the results showed a direct relationship among the BDD morphology, physical property, and its performance during the degradation process.     

地面国标C=3780固定接收业务中嵌入C=1移动接收业务

在发射功率不变时,利用:1)地面数字电视的固定接收可使用增益高达15 dBi的方向性天线;2)地面国标C=1的现场测试C/N门限值与C=3 780相比要低约3.5 dB;探讨在C=3 780固定接收业务中嵌入C=1移动接收业务的可行性.     

Individual cell lag time distributions of Cronobacter (Enterobacter sakazakii) and impact of pooling samples on its detection in powdered infant formula

Cells of six strains of Cronobacter were subjected to dry stress and stored for 2.5 months at ambient temperature. The individual cell lag time distributions of recovered cells were characterized at 25 °C and 37 °C in non-selective broth. The individual cell lag times were deduced from the times taken by cultures from individual cells to reach an optical density threshold. In parallel, growth curves for each strain at high contamination levels were determined in the same growth conditions. In general, the extreme value type II distribution with a shape parameter fixed to 5 (EVIIb) was the most effective at describing the 12 observed distributions of individual cell lag times. Recently, a model for characterizing individual cell lag time distribution from population growth parameters was developed for other food-borne pathogenic bacteria such as Listeria monocytogenes. We confirmed this model’s applicability to Cronobacter by comparing the mean and the standard deviation of individual cell lag times to populational lag times observed with high initial concentration experiments. We also validated the model in realistic conditions by studying growth in powdered infant formula decimally diluted in Buffered Peptone Water, which represents the first enrichment step of the standard detection method for Cronobacter. Individual lag times and the pooling of samples significantly affect detection performances.     

Use of titanium dioxide (TiO2) photocatalysts as alternative means for Listeria monocytogenes biofilm disinfection in food processing

The aim of this work was to study the photocatalytic activity of titanium dioxide (TiO₂) against Listeria monocytogenes bacterial biofilm. Different TiO₂ nanostructured thin films were deposited on surfaces such as stainless steel and glass using the doctor-blade technique. All the surfaces were placed in test tubes containing Brain Heart (BH) broth and inoculated with L. monocytogenes. Test tubes were then incubated for 10 days at 16 °C in order to allow biofilm development. After biofilm formation, the surfaces were illuminated by ultraviolet A light (UVA; wavelength of 315-400 nm). The quantification of biofilms was performed using the bead vortexing method, followed by agar plating and/or by conductance measurements (via the metabolic activity of biofilm cells). The presence of the TiO₂ nanoparticles resulted in a fastest log-reduction of bacterial biofilm compared to the control test. The biofilm of L. monocytogenes for the glass nanoparticle 1 (glass surface modified by 16% w/v TiO₂) was found to have decreased by 3 log CFU/cm² after 90 min irradiation by UVA. The use of TiO₂ nanostructured photocatalysts as alternative means of disinfecting contaminated surfaces presents an intriguing case, which by further development may provide potent disinfecting solutions. Surface modification using nanostructured titania and UV irradiation is an innovative combination to enhance food safety and economizing time and money.     

再议家用级（普及型）数字电视大有可为

在专稿的基础上，本文从我国电视接收机和广大观众接收电视图像主机质量的现状出发，再次议论：家用级数字电视在我国是大有可为的。     

韩国的数字广播

韩国信息与通信部(Ministry of Informationand Communication，MIC)认识到数字广播工业发展的潜力后，从1990年开始启动数字广播的准备工作。韩国数字广播的发展相关事件如下。     

新的数字电视体系中的视频编解码

新的数字电视体系中的视频编解码·新技术论坛·北京大学徐孟侠１新的数字电视体系正在诞生［１，２］１．１数字电视的发展简史１９４８提出电视（和声音）信号的数字化１９８０ＣＣＩＲ（现ＩＴＵ－Ｒ）６０１建议１９８２（德国ＩＴＴ集团）ＰＡＬ接收机的一套电视信号...