锑掺杂对钒钛系催化剂低温脱硝活性的影响

用浸渍法制备Sb-V₂O₅-TiO₂催化剂,在质量分数3%V₂O₅-TiO₂催化剂基础上,研究锑的负载量、焙烧温度对催化剂活性的影响。结果表明,锑的负载量为11%（质量分数）,500 ℃焙烧的催化剂具有最佳的SCR活性,在进口浓度为0.07% NO_x、O₂体积分数5%、空速27 000 h^-1的条件下,170 ℃时脱硝活性可达92%。对催化剂进行H₂-TPR表征,发现锑修饰后的催化剂氧化能力增强,使催化剂效率上升。通过XPS和NH₃-TPD表征测试,催化剂表面的锑主要以五价的形式存在且随着锑负载量的增加催化剂表面酸性增强。考察SO₂和H₂O对催化剂的影响发现,加锑催化剂具有一定的抗硫抗水性能。通过FT-IR、TG、孔隙结构测试表明,锑的加入可以有效地抑制硫酸铵盐在催化剂表面的聚集,从而延长催化剂的寿命。     

非晶态MnO_x/TiO_2催化剂的制备及其低温NH_3-SCR性能

采用自发沉积法、共沉淀法及浸渍法制备MnO_x/TiO_2催化剂,通过XRD、TEM、N2吸附-脱附、XPS、H_2-TPR、NH_3-TPD等一系列表征手段研究MnO_x/TiO_2催化剂的结构与性质,并考察MnO_x/TiO_2催化剂低温NH_3-SCR性能。结果表明,自发沉积法制备的MnO_x/Ti O2(s)催化剂具有完全非晶态结构,Mn和Ti之间存在强相互作用,较共沉淀法制备的MnO_x/TiO_2(c)及浸渍法制备的MnO_x/Ti O2(i)表现出更强的氧化还原能力。MnO_x/TiO_2(s)具有较高的比表面积、较多的表面酸量,有利于NH_3的吸附与活化。且表面高浓度的Mn4+离子及吸附氧,有利于将NO氧化为NO2,促进发生"fast-SCR"反应,进而使其表现出优异的低温脱硝性能。MnO_x/TiO_2(s)催化剂在150℃时NO的转化率高达92.8%,在150-350℃NO的转化率保持在90%以上,此外其还具备较强的抗H_2O和SO_2毒化能力。     

高残炭硼酚醛树脂的制备

酚醛树脂(PF)因其具有良好的耐热性能和机械性能而被广泛应用。但其耐热性能已经满足不了现代航空航天技术的需求,研究发现,采用硼酸对酚醛树脂进行改性,可以制得具有优良耐高温性能的硼酚醛树脂(BPF)。采用硼酸酯法合成硼酚醛树脂,n(苯酚)∶n(甲醛)=1∶1.5时耐热性最佳。热分析结果表明,合成的BPF在1000℃条件下的残炭率为78%,其耐热性能明显优于传统的酚醛树脂。同时讨论了不同硼酸含量对BPF耐热性能的影响,当n(硼酸)∶n(苯酚)0.33∶1时,残炭率趋于稳定。此外,利用差示扫描量热仪(DSC)方法确定BPF预固化温度为160℃,后固化温度为220℃。     

Analysis of an elasto-piezoelectric system of hemivariational inequalities with thermal effects

In this paper we prove the existence and uniqueness of a weak solution for a dynamic electo-viscoelastic problem that describes a contact between a body and a foundation. We assume the body is made from thermoviscoelastic material and consider nonmonotone boundary conditions for the contact. We use recent results from the theory of hemivariational inequalities and the fixed point theory.     

Surface analysis of ripple pattern on PS and PEN induced with ring‐shaped mask due to KrF laser treatment

The approach for ripple nanopattern construction on surface of two polymer substrates [polyethylene naphthalate (PEN) and polystyrene (PS)] exposed by a KrF pulse excimer UV laser through a contact lithographic mask with circular slit was proposed in this paper. Thin layer of gold was deposited on samples after the laser treatment. Changes in the morphology of the surface of both the shielded and exposed areas of the substrates, as well as the dimensions of the laser‐induced periodic surface structures, were determined (by atomic force microscopy, laser confocal microscopy and scanning electron microscopy), compared with observations and measurements made on samples treated directly (without a contact mask) under the same conditions. The morphology of the interface between the treated and untreated regions was also closely studied. Surface chemistry of treated samples was studied in detail by X‐ray Photoelectron Spectroscopy. The detailed study of surface chemistry of modified PEN and PS revealed a significant increase of oxygen concentration for laser treated PS and increase of carboxyl groups in case of PEN. The potential application of this research can be found in biotechnology, micro technology and several other fields. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of cold plasma process on the surface wettability of NBR and the kerosene resistance of NBR/PTFE composites

In this study, first the acrylonitrile‐butadiene rubber (NBR5080) was modified by argon (Ar), air, and oxygen plasma at low temperature, and the effect of plasma process (power, time, and pressure) on the surface properties of NBR5080, the interfacial properties, physical properties, and the mechanical properties of NBR5080/polytetrafluoroethylene (PTFE) composites were investigated. The state contact angle and the surface free energy were applied to characterize the surface wettability of NBR5080. The scanning electron microscope and the atomic force microscope were used to observe the surface morphology of the NBR5080. The chemical changes on the NBR5080 surface were verified by X‐ray photoelectron spectroscopy. The average water contact angle the NBR5080 declined obviously when NBR5080 was treated by Ar (100 W/600 s/30 Pa). The active oxygen groups were introduced onto the surface of NBR5080 by cold plasma treatment and more active group containing oxygen were observed on the samples treated by Ar plasma. The peel strength between the NBR5080 and the PTFE was increased obviously, which increased from 0 to 44.2 N?m^?1 for Ar plasma treatment. The mass and the dimension of NBR5080 increase sharply after immersing in kerosene, whereas the NBR5080/PTFE composites changed a little. The mechanical properties of NBR5080 and NBR5080/PTFE composites decreased as the immersion time in kerosene increased, but the decreased degree of NBR5080 is higher than NBR5080/PTFE composites.     

Well Oriented ZnO Nanorods Array: Negative Resistance and Optical Switching

Well‐oriented ZnO nanorods (NRs) arrays were grown on Si, alumina, quartz, and FTO substrates through a ZnO seed layer followed by low temperature wet chemical process. The influence of sputtered ZnO seed layer thickness (100, 50, 32, and 16 nm), annealing temperature and CuO_x coverage on the characteristics of ZnO NRs were investigated in this study. The crystalline structural, chemical, morphological, optical, and electrical properties of ZnO NRs arrays were studied by X‐ray diffraction (XRD), field emission‐ scanning electron microscopy equipped by energy dispersive X‐ray spectroscopy (FE‐SEM/EDX), Raman scattering, UV/Vis ‐ near IR absorption spectroscopy and current‐voltage characteristic. XRD and Raman spectra measurement revealed that the synthesize ZnO displayed hexagonal wurtzite structure. The individual rod diameter, density, and orientation can be controlled by varying the seed layer thickness. The mean diameter and maximum length of ZnO NRs are around 55–66 nm and 282 nm, respectively. ZnO NRs/ ZnO thin film structure shows optical switching and negative differential resistance behavior as applicable to ON/OFF gate and memory devices.     

Damage resistance of carbon fibre reinforced epoxy laminates subjected to low velocity impact: Effects of laminate thickness and ply-stacking sequence

A major concern affecting the efficient use of composite laminates is the effect of low velocity impact damage on the structural integrity [1–3]. The aim of this study is to characterize and assess the effect of laminate thickness, ply-stacking sequence and scaling technique on the damage resistance of CFRP laminates subjected to low velocity impact. Drop-weight impact tests are carried out to determine impact response. Ultrasonic C-scanning and cross-sectional micrographs are examined to assess failure mechanisms of the different configurations.It is observed that damage resistance decreases as impact energy increases. In addition, thicker laminates show lower absorbed energy but, conversely, a more extensive delamination due to higher bending stiffness. Thinner laminates show higher failure depth. Furthermore, quasi-isotropic laminates show better performance in terms of damage resistance. Finally, the results obtained demonstrate that introducing ply clustering had a negative effect on the damage resistance and on the delamination area.     

Utilizing Paper-Based Devices for Antimicrobial-Resistant Bacteria Detection

Antimicrobial resistance (AMR), the ability of a bacterial species to resist the action of an antimicrobial drug, has been on the rise due to the widespread use of antimicrobial agents. Per the World Health Organization, AMR has an estimated annual cost of USD 34 billion in the US and is predicted to be the number one cause of death worldwide by 2050. One way AMR bacteria can spread, and by which individuals can contract AMR infections, is through contaminated water. Monitoring AMR bacteria in the environment currently requires that samples be transported to a central laboratory for slow and labor intensive tests. We have developed an inexpensive assay using paper-based analytical devices (PADs) that can test for the presence of β-lactamase-mediated resistance. To demonstrate viability, the PAD was used to detect β-lactam resistance in wastewater and sewage and identified resistance in individual bacterial species isolated from environmental water sources.     

Fluorinated PEG‐Polypeptide Polyplex Micelles Have Good Serum‐Resistance and Low Cytotoxicity for Gene Delivery

A novel PEGylation polypeptide, poly(ethylene glycol)‐b‐poly(l ‐lysine)‐b‐poly(l ‐cysteine) (PEG‐PLL‐PCys) triblock copolymer is synthesized via the sequential ring‐opening polymerization of amino acid N‐carboxyanhydrides initiated by methoxypolyethylene glycol amine (mPEG‐NH₂, M _w is 2 kDa). Subsequently, the obtained polypeptide is partially conjugated with fluorocarbon chains via disulfide exchange reaction. PLL segment can condense plasmid DNA through an electrostatic force to form a complex core, PEG segment surrounding the complex like a corona can prevent the complex from precipitation and reduce the adsorption of serum, while PCys segment with fluorocarbon can enhance the cellular uptake and the stability of the formed polyplex micelles in physiological conditions. Experiment results exhibit that the fluorinated polypeptides have low cytotoxicity and good gene transfection efficiency even in the presence of 50% fetal bovine serum.