Effect of oxide nanoparticles on the morphology and fluidity of phospholipid membranes and the role of hydrogen bonds

Engineered oxide nanoparticles (NPs) are widely applied in insulators, catalyzers, paints, cosmetic products, textiles and semiconductors. Their attachment on cell membrane may lead to cytotoxicity. The effects of Al₂O₃, Fe₂O₃, SiO₂, TiO₂ and ZnO NPs on membrane integrity and fluidity were studied using giant or small unilamellar vesicles in this study. Al₂O₃ and SiO₂ NPs disrupted the oppositely charged membrane, indicating the important role of electrostatic attraction. However, Fe₂O₃, TiO₂ and ZnO NPs did not cause serious membrane disruption as Al₂O₃ and SiO₂ NPs. Membrane fluidity was evaluated by the generalized polarity (GP) values of Laurdan fluorescent emission. SiO₂ NPs induce the membrane gelation of both positively and negatively charged membrane. Al₂O₃ and ZnO NPs induced the gelation of the oppositely charged membrane, but did not cause obvious membrane gelation to the like charged membrane. The phospholipid molecular structural changes after NP exposure were analyzed by Fourier transform infrared (FT-IR) spectroscopy. FT-IR spectra revealed the hydrogen bond formation between NPs and the carbonyl/phosphate groups of phospholipids. Al₂O₃ and SiO₂ NPs showed strongest evidence of hydrogen bonding on their FT-IR spectra. It was consistent with the microscopic observation and fluorescent data that Al₂O₃ and SiO₂ NPs caused more serious membrane disruption and gelation. This study on membrane damage provides further knowledge on the cytotoxicity of nanomaterials and the safety of NP application.     

台州市大气PM_(2.5)中PAHs的污染特征与毒性评价

使用中流量颗粒物采样器采集台州市2015—2016年大气PM_(2.5)样品,利用气相色谱-质谱仪对样品中16种多环芳烃(PAHs)进行分析,研究PAHs的污染特征及可能来源。结果显示:PAHs总浓度为(20.69±4.84)ng/m3,浓度季节变化大小顺序依次为冬季>春季>秋季>夏季,空间变化为商住区>工业区>背景点。PM_(2.5)中PAHs以高环为主(≥4环),占86%。不同季节商住区和工业区PAHs(4环)含量均略高于背景点,PAHs(5~6环)的含量商住区略高于工业区和背景点。PAHs环数分布和比值法结果表明台州市大气PM_(2.5)中PAHs的主要来源是机动车尾气和燃煤。成年人和儿童的终生超额致癌风险(ILCR)分别为8.02×10-7和5.61×10-7,表明台州市PM_(2.5)中PAHs对人体健康影响在可接受范围内。     

碳酸钙改性硅藻土处理电解锌漂洗废水实验研究

铅锌矿在我国储存量大,电解法生产锌过程中可产生含Zn~(2+)、Pb~(2+)、Cd~(2+)、As5+和Cu~(2+)等重金属离子的漂洗废水。以硅藻土精土为基体,用碳酸钙作为改性剂制备改性硅藻土,对电解锌漂洗废水进行吸附实验研究。结果表明:在反应时间为150 min,碳酸钙改性硅藻土用量为3 g/L,pH为5.46,温度为25℃条件下,对废水进行吸附实验,吸附后废水中的Cu~(2+)和As5+离子浓度低于仪器检测线(0.01 mg/L和0.09 mg/L),Pb~(2+)浓度为0.16 mg/L,吸附后废水中Cu~(2+)、As5+和Pb~(2+)离子浓度均满足GB 25466—2010《铅锌工业污染物排放标准》的排放要求。同时,采用SEM、FTIR、XRD等对碳酸钙改性硅藻土进行表征,进一步探讨了碳酸钙改性硅藻土对重金属的吸附机理。     

一种简便高效的土壤石油烃提取方法的建立

通过开展单因子实验与正交实验,考察不同参数下超声萃取法对土壤中总石油烃(TPH)的提取效率,并对比了超声萃取法、超声-索氏萃取法及传统索氏萃取法对不同原油污染土壤的提取效果。结果表明:超声萃取法的最优工作参数为20 m L二氯甲烷,超声10 min,4000 r/min离心10 min,萃取4次。3种提取方法中,超声萃取法对石油烃平均回收率最高,为100.95%,而传统的索氏萃取法最低,仅为94.54%。可见,超声萃取法操作简单,效率高,可广泛用于土壤中总石油烃含量的提取测定。     

有机质对p,p′-DDE在土壤中的吸附影响

为研究有机质对p, p′-DDE在土壤中的吸附影响因素,采用批量试验方法,分析p, p′-DDE在包气带土壤及含水层土壤上吸附量的变化及有机质对p, p′-DDE在土壤中的吸附影响.结果表明,p, p′-DDE在土壤中的吸附均符合先快后慢、最后达到吸附平衡的规律;其吸附动力学曲线用一级和二级反应动力学方程均能较好拟合,说明p, p′-DDE在这两种物质中的吸附以简单吸附为主,同时包含表面吸附、颗粒内部扩散等过程.包气带土壤和含水层土壤等温吸附线的拟合相关系数(R2)均大于0.95,符合Freundlich模型和线性模型,而含水层样品与Freundlich模型拟合得更好,表明p, p′-DDE在包气带土壤中的吸附以单分子层吸附为主,而在含水层土壤中的吸附还伴随着多分子层吸附的复杂过程;去除内源DOM(溶解性有机质)后,样品对p, p′-DDE的吸附量呈增加趋势,按吸附增加量由小到大的排序为1-1(0~10 cm) < 1-2(120~150 cm) < 2-4(100~120 cm),说明内源DOM的存在总体上抑制了p, p′-DDE的吸附,并且w(DOM)越高,其抑制作用越强;外源DOM的加入抑制了土壤对p, p′-DDE的吸附;去除有机质后样品对p, p′-DDE的吸附量与w(黏土矿物)具有正相关性.研究显示,有机质对土壤中有机污染物的吸附迁移研究对土壤修复有重要意义,需要对有机质影响土壤的吸附机制进行更深层次的研究.      

Construction of vesicle CdSe nano-semiconductors photocatalysts with improved photocatalytic activity: Enhanced photo induced carriers separation efficiency and mechanism insight

Visible-light-driven photocatalysis as a green technology has attracted a lot of attention due to its potential applications in environmental remediation. Vesicle Cd Se nano-semiconductor photocatalyst are successfully prepared by a gas template method and characterized by a variety of methods. The vesicle Cd Se nano-semiconductors display enhanced photocatalytic performance for the degradation of tetracycline hydrochloride, the photodegradation rate of78.824% was achieved by vesicle Cd Se, which exhibited an increase of 31.779% compared to granular Cd Se. Such an exceptional photocatalytic capability can be attributed to the unique structure of the vesicle Cd Se nano-semiconductor with enhanced light absorption ability and excellent carrier transport capability. Meanwhile, the large surface area of the vesicle Cd Se nano-semiconductor can increase the contact probability between catalyst and target and provide more surface-active centers. The photocatalytic mechanisms are analyzed by active species quenching. It indicates that h+and UO_2~-are the main active species which play a major role in catalyzing environmental toxic pollutants. Simultaneously, the vesicle Cd Se nano-semiconductor had high efficiency and stability.     

In-situ synthesis of TiO2 rutile/anatase heterostructure by DC magnetron sputtering at room temperature and thickness effect of outermost rutile layer on photocatalysis

TiO_2 rutile/anatase heterostructure thin films with varying rutile thickness have been in-situ synthesized via DC magnetron sputtering with Ar gas at room temperature. The crystal texture, surface morphology, energy gap and optical properties of the films have been investigated by X-ray diffraction meter, grazing incidence X-ray diffraction meter, Raman spectroscopy, scanning electron microscopy, and UV–visible spectrophotometer, which indicates that the rutile/anatase heterostructure films are successfully fabricated. The further degradation experiments display that the photocatalytic activity can be dramatically affected by the thickness of the outmost rutile layer and the 100 nm thickness exhibits the best performance in all of the TiO_2 thin films. With the increase of the outmost rutile layer, the optical band gap of TiO_2 film displays a systematic decrease slightly. However,the change in photocatalytic activity does not coincide with that in the band gap. The photoresponse and electrochemical properties of the thin films have been characterized to understand the mechanism of the varied photocatalytic activity.     

流体剪切与超声空化破解剩余污泥的参数优化

为提高剩余污泥的破解效果并降低能耗,采用FS（fluid shear,流体剪切）、UC（ultrasonic cavitation,超声空化）、FS和UC联合工艺（FS-UC,UC-FS）破解剩余污泥,并应用单因素试验结合响应面法对联合工艺进行优化.结果表明:FS对剩余污泥破解效果一般,只在开始阶段具有较好效果,随作用时间延长,破解效果未有显著提高甚至下降.UC对剩余污泥破解效果明显,随作用时间延长,破解效果显著提升,但能耗也随之增大,EDR（energy disintegration ratio,效能比）明显下降.相同作用时间下,UC破解效果优于FS破解效果,UC破解剩余污泥的DD_COD（degree of disintegration,破解率）与EDR均明显高于FS方法.单因素试验得出的较优FS作用时间范围为2~8 min,较优UC作用时间范围为5~15 min.响应面法试验结果显示,联合工艺的剩余污泥破解效果和能量利用率均优于单一方法,联合工艺中FS-UC工艺的破解效果优于UC-FS工艺.FS-UC工艺的最佳参数:FS处理5.6 min再UC处理15.0 min,该条件下剩余污泥实际DD_COD为50.8%,EDR为26.8%.UC-FS工艺的最佳参数:先UC作用15.0 min再FS作用7.8 min,该条件下剩余污泥实际DD_COD为36.5%,EDR为17.1%.研究显示,以DD_COD和EDR为指标,4种工艺的高效性顺序为FS-UC > UC-FS > UC > FS,其中FS-UC工艺具有能耗低、破解效率高的特点,是4种工艺中剩余污泥破解效果最好的一种工艺.      

海洋功能区划保留区管控要求解析及政策建议

本文基于保留区选划的原因和分类,结合新一轮全国和省级海洋功能区划编制,汇总和比较全国、省级保留区管控规定,分析了目前各省保留区个数、面积、岸线长度、离岸距离等设置情况。据此,依据保留区内涵将保留区划分为五类,即功能待定区、发展预留区、整治修复预留区、保护缓冲区以及特殊功能预留区,分别提出五类保留区的使用管理要求和环境保护要求。最后,文章从保留区用海现状处理方式、开发利用条件、用海活动管理等方面提出政策建议。总体来说,保留区不允许随意利用但并不完全禁止利用,在不改变海域自然属性的前提下,当用海活动符合保留区用途及环境保护要求,不影响周边海域功能正常发挥的情况下允许进行开发利用。     

自适应智能电磁防护材料测试方法研究

目的在强电磁场环境下研究自适应智能电磁防护材料的相变特性。方法针对自适应智能电磁防护材料相变前后电导率的变化范围大、需要强场激励状况,考虑测试系统强场生成、大动态范围、测试精度以及相应的绝缘性和较高的安全性要求,采用电容充放电原理设计强场激励测试电路,搭建绝缘环境,确保操作的安全性和测试数据的可靠性。结果利用测试系统对现有商业化电阻器进行验证试验,得到的特性曲线与理论相一致。结论测试系统能够满足自适应智能电磁防护材料相变特性试验的需求,可获取有效且可靠的测试数据。