公共危机次生型网络舆情危机产生的内在逻辑——基于40个案例的模糊集定性比较分析

论文旨在探究公共危机次生型网络舆情危机产生的核心影响因素及其共变逻辑。通过两层次扎根编码整合既有理论、提炼变量,爬虫技术获取数据,层次分析法进行数据降维,定性比较分析40个案例,以典型案例过程追踪进行理论饱和检验。研究发现:对于次生型网络舆情危机的爆发,没有单一因素是充分条件或必要条件;政府舆情处理、政府公共危机响应、政府自身因素与舆论讨论四个因素为核心因素,其组合路径可视为次生型网络舆情危机爆发的充分条件;次生群体性事件和公共危机元事件为次生型网络舆情危机爆发的次要因素,从自然因素到人为因素再到政府行为因素,引发次生型网络舆情危机的可能性依次递增;媒体影响力起舆情催化作用,不改变舆情演化方向。研究的理论价值在于,发现了网络舆情危机内外因素的耦合共变机制,为次生型网络舆情危机的爆发提供了一种整体性解释。

The production of biobased diamines from renewable carbon sources: Current advances and perspectives

Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the art of the synthesis of aliphatic and aromatic diamines from renewable biomass are considered.In the case of aliphatic diamines,we describe strategies for biologically producing diamines with different carbon numbers including 1,3-diaminopropane,1,4-butanediamine,1,5-pentanediamine,1,6-diaminohexane,1,8-diaminooctane,1,10-diaminodecane,and 1,12-diaminododecane.In addition,aromatic diamines produced from various kinds of renewable biomass,including lignin,cashew nut shell,and terpenoids,are reviewed here.Furthermore,the application of typical diamines in synthesis of polyurethane and polyamide are also reviewed.

Characterization and application of a recombinant dopa decarboxylase from Harmonia axyridis for the efficient biosynthesis of dopamine

Here,a dopa decarboxylase(DDC)from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine.For the production of recombinant DDC,the cultivation conditions including IPTG concentration,temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg^(-1) crude extracts.After the purification of DDC with a recovery yield of 68.79%,its activity was further characterized.The Vmax,Km,Kcat,and Kcat/Km of DDC for d ihyd roxy pheny la la nine(dopa)were 0.02 mmol·ml^(-1)·s^(-1),2.328 mmol·ml^(-1),10435.90 s^(-1) and4482.77 ml,mmol respectively.The highest DDC activity was observed at the condition of pH 7.5 and 45℃.With the purified DDC,the feasibility to produce dopamine from L-dopa was evaluated.The optimal yield was determined at the following bioconversion conditions:pH of 7,0,the reaction temperature of 40℃,0.4 mmol·L^(-1) of PLP and 4 g·L^(-1) of L-dopa,Subsequently,a fed-batch process for the production of dopamine was developed and the effect of oxygen was evaluated.The titer,yield and productivity of dopamine reached up to 21.99 g·L^(-1)80.88%and 14.66 g·L^(-1)·h^(-1) at 90 min under anaerobic condition.

Control Effect of UAV Low Volume Spray Technology on Thrips and Tomato Spotted Wilt Virus in Tobacco Field

[Objectives]The paper was to explore the influence of unmanned aerial vehicle(UAV)low volume spray technology on the control effect of viruliferous thrips and tomato spotted wilt virus(TSWV)under different pesticide concentrations,and to explore the effective control nodes and methods of thrips and TSWV.[Methods]According to the occurrence characteristics of thrips and TSWV,the field control effects of 4 pesticides on thrips and TSWV were tested by UAV with the thrips number and disease index as indicators,following the principle of regional and periodic control trials.[Results]In the groups of UAV and artificial prevention and control,4 agents were used alternatively,including 1%emamectin benzoate ME,1.7%abamectin imidacloprid ME,5%emamectin benzoate WDG,and 30%pyriproxyfen dinotefuran SL.There was no significant difference in the control effect of thrips and TSWV among treatment 1(recommended dosage of UAV agent),treatment 2(reduction of recommended dosage of UAV agent by 25%)and treatment 4(recommended dosage of artificial control agent),and the control effects on thrips were more than 83.16%in the 3 treatments.The disease index of TSWV in the 3 treatments decreased from 8.64±1.37 in the blank control group to less than 3,which reached the prevention and control threshold.But treatment 3(reduction of recommended dosage of UAV agent by 50%)did not reach the prevention and control threshold.The disease index of TSWV in the blank control area increased with the increase of the number of live nymphs of thrips,and there was a significant positive correlation,with good fitness.[Conclusions]UAV has a significant impact on the control effect of thrips and TSWV under different pesticide concentrations.In the actual flight control application,it is recommended that the amount of the pesticides is about 3/4 and not less than 1/2 of that of the artificial application.The control area should be extended to 100 m of the ridge of the tobacco field,and UAV is used periodically to control thrips and TSWV for 5 times from pre-transplanting stage to pre-squaring stage of flue-cured tobacco.The control effect is significantly different from the traditional artificial application.

Advance of tolerance engineering on microbes for industrial production

Industrial microbes have become the core of biological manufacturing,which utilized as the cell factory for production of plenty of chemicals,fuels and medicine.However,the challenge that the extreme stress conditions exist in production is unavoidable for cell factory.Consequently,to enhance robustness of the chassis cell lays the foundation for development of bio-manufacturing.Currently,the researches on cell tolerance covered various aspects,involving reshaping regulatory network,cell membrane modification and other stress response.In fact,the strategies employed to improve cell robustness could be summarized into two directions,irrational engineering and rational engineering.In this review,the metabolic engineering technologies on enhancement of microbe tolerance to industrial conditions are summarized.Meanwhile,the novel thoughts emerged with the development of biological instruments and synthetic biology are discussed.