螯合自组装制备生物基阻燃牛皮纸及作用机理

提高木质纤维材料的阻燃性能、减少对石化基氮磷阻燃剂的使用,在拓展木基材料的同时提高改性木质材料的环保性能具有重要的研究意义。文中利用植酸与壳聚糖,结合无机金属离子Ca螯合的形式在纸张表面以层层螯合自组装制备了生物基高效阻燃涂层。层层螯合阻燃处理后,牛皮纸K-7在垂直燃烧测试时形成了长度仅为29.5 mm的炭层,其极限氧指数相对于对照组提高了17.9%,总热释放量降低了15.4 k J/g,阻燃处理后样品在600℃时的残炭质量显著提高,且阻燃处理后牛皮纸的挺度与撕裂度均得到提升;其燃烧后形成了含有P,N,Ca等元素高石墨化程度的阻燃层,其中含有P=O,P_(2)O_(7)^(2-)等特征官能团。植酸、壳聚糖及Ca^(2+)通过静电吸附及螯合作用在纸张表面形成了层状生物基阻燃层,避免了阻燃处理对纸张强度的影响,减少了亲水基团的暴露,从而降低了阻燃处理造成的材料的吸湿性。在受热时,阻燃层通过气相和凝固相阻燃相结合的方式发挥阻燃功效,有效地赋予了木质纤维材料的阻燃性能,避免了对石化基阻燃剂的依赖。

Repairing damaged reputations through targeted poverty alleviation:Evidence from private companies’strategies to deal with negative media coverage

When negative media coverage causes reputational crises,companies must find suitable tools to repair their reputation and reverse their negative image.As a CSR activity with political-and livelihood-related implications,targeted poverty alleviation may be an effective tool.Using data on negative media coverage of Chinese A-share private listed companies,we examine whether companies engage in targeted poverty alleviation in response to reputational crises caused by negative media coverage.We find that negative media coverage leads private companies to engage more actively and intensively in targeted poverty alleviation because of the significant increase in public attention to the bad news.These companies must urgently rebuild their positive image using targeted poverty alleviation to resolve their public opinion crisis.Further analyses suggest that original and in-depth negative media coverage is more likely to cause companies’active participation in targeted poverty alleviation.In addition,negative media coverage is more likely to lead companies to engage in targeted poverty alleviation when they are in heavily polluting industries or face greater pressure from external investors.Finally,we find that active involvement in targeted poverty alleviation helps companies improve their market reputation and thus effectively manage public relations crises caused by negative media coverage.

长痛还是短痛?——金融危机期间经济刺激政策的长短期效应研究

尽管"四万亿"经济刺激政策导致大量银行信贷流入国有企业,但在经济刺激期和经济刺激政策退出后,国有企业的业绩均显著更差。研究发现,经济刺激政策引致的信贷膨胀更多流入了国有企业中盈利能力最差,甚至是无法按期偿还贷款本息的企业。资源的严重错配还造成国有企业在经济刺激期雇用了更多劳动力,主营业务上也表现为通过降价和提供更宽松的商业信用而非通过创新活动来维持销售增长,非主营业务上则突出表现为房地产投资的大幅增长。本文研究有助于进一步厘清政府和市场在经济危机中的作用。

产业政策何以更有效?——基于海量媒体报道数据与研发操纵现象的证据

高新技术企业认定中普遍存在为获得税收减免而进行研发操纵的现象,本文研究发现,媒体报道能够通过提高网民对公司的关注度而抑制企业的研发操纵行为。区分新闻报道属性发现,原创报道和深入报道更能抑制公司的研发操纵行为;区分媒体自身属性发现,网络媒体和权威媒体对公司研发操纵行为的监督作用更强。此外,对于民营企业、分析师覆盖较多的企业、政府质量较高以及市场化水平较高地区的企业,媒体报道对公司研发操纵行为的监督作用更强。最后,媒体关注还能提高公司研发绩效。