Comparative Study of Structure and Property Changes in Corrosive Media for Self-cleaning Superhydrophobic Magnesium Alloys

Magnesium alloys with superhydrophobicity are constructed by controlling rough surface structure and grafting long hydrophobic alkyl chains. Changes of morphology, phase structure, chemical composition as well as wettability, corrosion resistance of superhydrophobic magnesium alloy upon immersing in corrosive media are investigated comparatively. Meanwhile, the contaminating particles on as-prepared superhydrophobic surfaces can be taken away easily by rolling water droplets. Therefore, the results show that as-prepared superhydrophobic magnesium alloys exhibit enhanced corrosion resistance and self-healing performance. Finally, anti-corrosion and self-cleaning mechanisms are deduced. It can be concluded that it is an effective strategy of preparing superhydrophobic surfaces for improving the corrosion resistance and selfcleaning performance of magnesium alloys.

Application of Sol Self-Clean Bonded Al_2O_3-SiC-C Castable for Iron Runner

The properties and microstructure of sol self-clean bonded Al2O3-SiC-C castable in iron runner were studied, and the relation between the amount of sol self- clean binder and the properties of castable were discussed. It is believed that the addition of sol self-clean binder can improve the compressive strength, but has little effect on the bulk density and the apparent porosity, which enable the castable to be applicable in different conditions.

Superhydrophobic Micro/Nanostructured Copper Mesh with Self-Cleaning Property for E ective Oil/Water Separation

In this work, a simple method was carried out to successfully fabricate superoleophilic and superhydrophobic N-dodecyltrimethoxysilane@tungsten trioxide coated copper mesh. The as-fabricated copper mesh displayed prominent superoleophilicity and superhydrophobicity with a huge water contact angle about 154.39° and oil contact angle near 0° Moreover, the coated copper mesh showed high separation efficiency approximately 99.3%, and huge water flux about 9962.3 L·h^-1·m-2, which could be used to separate various organic solvents/ water mixtures. Furthermore, the coated copper mesh showed favorable stability that the separation efficiency remained above 90% after 10 separation cycles. Benefiting from the excellent photocatalytic degradation ability of tungsten trioxide, the coated copper mesh possessed the self-cleaning capacity. Therefore, the mesh contaminated with lubricating oil could regain superhydrophobic property, and this property of self-cleaning permitted that the fabricated copper mesh could be repeatedly used for oil and water separation.

Self-Cleaning Properties of Vanadium Doped TiO₂Sol-Gel Derived Thin Films

In this study, vanadium doped TiO2 thin films were deposited on glass substrates using a sol-gel dip-coating process. X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectrophotometer were used to characterize the structural, chemical and the optical properties of the thin films. The photo-catalytic activities of films were investigated by methylene blue degradation. Water contact angle on the film surfaces was measured by a water contact angle analyzer. The results indicated that vanadium doping had a significant effect on the self-cleaning properties of TiO2 thin films.

A simple way to fabricate an aluminum sheet with superhydrophobic and self-cleaning properties

A superhydrophobic aluminum sheet is fabricated via a hot water immersing process and subsequently surface modification with heptadecafluorodecyltrimethoxy-silane （HTMS）. As revealed by the scan electron microscopy （SEM）, X-ray diffraction （XRD）, and Fourier-transform infrared spectrophotometer （FTIR） results, a rough pseudoboehmite film is formed on the aluminum sheet, and HTMS molecules are grafted on the film surface successfully. These two factors make the treated aluminum sheet present superhydrophobicity with a water contact angle larger than 160° and sliding angle less than 5°, and possess a self-cleaning property. Furthermore, the flexible superhydrophobic aluminum sheet could be pasted to a cylinder surface without destroying its superhydrophobicity. At the end, the effect of hot water treatment time on superhydrophobicity is investigated.

Sol-Gel Preparation of TiO2/SiO2 Nanocomposites and Their Application in Self- cleaning Textiles

The present study involves the preparation of TiO 2/ SiO 2nanocrystals and their application in self-cleaning wool-polyester fabrics.The TiO 2/ SiO 2nanocrystals were successfully synthesized and deposited onto wool-polyester fabrics using the low-temperature sol-gel technique.The as-prepared nanocomposites and the nanocomposites coated samples were characterized by X-ray diffraction( XRD) and scanning electron microscopy( SEM),respectively.The XRD and SEM results showed that the single-phase anatase nanocrystallites were formed and loaded on the fabric surface successfully.The photocatalytic activities of TiO 2-coated and TiO 2/ SiO 2-coated wool-polyester fabrics were measured by studying photodegradation of methylene blue dye.Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2/ SiO 2modified sample with respect to that of pure TiO 2modified sample.Our observations indicate that by applying this technique to the fabrics,self-cleaning materials can be designed for practical application.

Self-cleaning performance of a self-cleaning pre-coated steel sheet in an industrial environment

A type of self-cleaning pre-coated steel sheet with excellent self-cleaning performance was developed using hydrophilic surface treatment technology. To understand the self-cleaning properties of this pre-coated steel sheet in an industrial environment, the Jiangjin natural environmental test station was chosen as the outdoor exposure test to be conducted, and the self-cleaning performance of the steel sheet was studied by measuring the water contact angle, stain resistance factor, color difference, and gloss of the steel sheet during the outdoor exposure test. The water contact angle of the self-cleaning steel sheet quickly decreased from 84° to 29° during the outdoor exposure test, and the steel sheet showed excellent hydrophilic properties, which were beneficial to the spread of rain drops and detrimental to the accumulation of the surface pollutants. After an outdoor exposure of 12 months,the self-cleaning steel sheet had a higher stain resistance and cleaner surface than the comparison sample sheet, demonstrating its excellent self-cleaning properties. Moreover, the color difference and gloss rate of the self-cleaning steel ＇sheet were similar to those of the pre-coated steel sheet without hydrophilic surface treatment. Therefore, the hydrophilic surface treatment technology used in this study did not affect the anti-aging property of the self-cleaning steel sheet.

Self Ear Cleaning: Prevalence and Profile among School Children in Ekiti, Nigeria

Background: Self-cleaning of ears with different objects is a common practice among school children with scanty report in literature. Aim: The aim of this study was to determine the prevalence and profile of self-ear cleaning among school children. Methods: It was a cross-sectional institutional-based study which was carried out among school children in Ekiti, south western Nigeria from January 2017, to March 2017. Results: A total of 174 students participated in this study. Their age ranged between 13 and 17 years. The highest number of participant was found at the age of 15 years. One hundred and eighteen (67.8%) of them had carried out self ear cleaning. Personal hygiene was the commonest reason for self ear cleaning in 28.8% of the students. Cotton buds were mostly used by the respondents in 51.7% of them. Injury to the external auditory canal (EAC) was the most recorded complications. Conclusion: The outcome of this study shows that self-ear cleaning practices were common among school children with a prevalence of 67.8%. Cotton buds were the commonest objects used. Avoidable complications were reported among respondents. There is a need to intensify efforts on public enlightenment programme and the establishment of school health programme in our various schools.

Rendering of Cellulose Acetate Fabrics Self-Cleaning through Treatment with TiO₂Nano Particles

Finishing using TiO2-nanosol treatment of cellulose acetate (CA) fabrics before and after the latter were pretreated with H2O2was undertaken with a view to impart unique properties to CA fabrics, notably, self-cleaning. Finishing was performed as per the pad-dry-cure method. The finishing treatment involved dispersing the nano-sized TiO2particles in a mixture of water and ethylene glycol (1:1) and application of the dispersions to CA fabrics was made under a variety of conditions. Self cleaning ability of the fabrics is favored by 1) increasing the concentration of TiO2-nanosol to certain limit;2) prolongation of curing time up to 15 second;3) raising the microwave power from 80% to 100% but with the certainty that power of 90% is the most proper. Besides, exposure time-to UV radiation-up to 90 minutes is essential to have remarkable self cleaning properties while keeping other technical properties, namely, strength, roughness and wettability practically unaltered. Incorporation of binder in the finishing pad-bath helps stabilizing the deposition of TiO2 with excellent self-cleaning. Pretreatment of CA fabrics with H2O2 is a pre requisite to guarantee excellent self-cleaning ability. Thermofixation and microwave fixation produces fabrics with very comparable technical properties.

Sociodemographic Characteristics and Prevalence of Self Ear Cleaning in Sokoto Metropolis

Background: Self ear cleaning with cotton buds and other objects is a common practice. Objective: To determine the sociodemographic characteristics and the prevalence of self ear cleaning habit among patients attending a family medicine clinic in a teaching hospital in Sokoto metropolis. Materials and Methods: This was a 4 weeks prospective study carried out between May and June, 2013 at Usmanu Danfodiyo University Teaching Hospital and Specialist Hospital Sokoto. A structured self response questionnaire containing items on sociodemographic characteristics, frequency of administering objects into the ear and complications of self ear cleaning was administered to the respondents after institutional research ethical clearance. The data were analysed using SPSS for windows version 16.0. P-value was considered significantly if less than 0.05. Results: A total of 200 subjects were included in this study, comprising of 93 (46.5%) males and 107 (53.5%) females. Their ages ranged from 18-57 years with the mean age being 30.29 years (±8.70). Eighty percent (160) of the respondents practise self ear cleaning. Types of objects included writing objects and cotton buds. For many of the subjects, the frequency of insertion was once daily and both ears were frequently cleaned. Complications that have arisen due to the practice included otitis externa. Conclusion: Self ear cleaning was prevalent in the subjects. Considering the complications that may arise, ear cleaning is better done by trained health personnel.

基于超疏水、超亲水自清洁涂层的研究及其多功能应用

固体材料因其表面积聚的灰尘、污垢、油脂等污染物而受到污染,进而导致材料的失效和故障等问题。通过涂覆超亲水、超疏水的特殊润湿性自清洁涂层是解决这些问题的有效方法。从固体表面润湿性理论出发,阐述了理论润湿模型、润湿性参数以及润滑行为;介绍了超疏水性、超亲水性自清洁功能的工作原理。同时,介绍了国内外关于超疏水、超亲水自清洁涂层的相关制备方法及其优缺点,以及涂层在光伏发电、防冰防霜、金属防腐领域的多功能应用。最后指出,存在对涂层稳定性、抗脱落性等综合性能的评估不足,缺乏对适用环境因素的考量等问题,并对其研究前景进行了展望。

基于阿基米德螺旋转轮的自清洗泵前过滤器设计与试验

为提高泵前过滤器自清洗性能,解决过滤系统频繁中断问题,该研究将阿基米德螺旋转轮应用于泵前过滤器自清洗过程,通过数值仿真与物理试验,结合相关性分析和线性回归分析,探究叶片螺距、叶片角度、叶片数量对阿基米德螺旋转轮转速的影响规律。结果表明:转轮转速随螺距的增加逐渐下降,且降低幅度逐渐上升,随叶片角度和叶片数量的增加转轮转速的提升较小且提升幅度不断减小,对转轮转速影响程度由大到小为螺距、叶片角度和叶片数量。通过TOPSIS法(technique for order preference by similarity to an ideal solution)综合评价得到最佳结构参数组合为:螺距133 mm,叶片角度90°,叶片数量1。优化后水驱式自清洗泵前过滤器开展自清洗试验,结果显示流量经过最初下降阶段后稳定在294.9~296.6 m^(3)/h区间,流量降幅仅为1.13%~1.70%,利用水力驱动阿基米德螺旋转轮带动自清洗装置的滤网清洗效果良好。研究结果可为水驱式自清洗泵前过滤器的结构设计和优化提供参考。

UV接枝聚硅氧烷-TiO_(2)复合棉织物的制备及性能

通过紫外辐射3-(异丁烯酰氧)丙基三甲氧基硅烷对棉织物进行接枝聚合改性,然后与钛酸四丁酯共水解,形成Si—O—Ti化学键,通过化学键合的形式引入TiO_(2)层。由于Si元素位于棉织物和二氧化钛之间,阻断TiO_(2)光催化降解棉织物。化学键合TiO_(2)与棉织物的结合强度高,提高了耐久性。TiO_(2)对棉织物的整体结构未造成改变,但棉织物的抗紫外线能力显著提升,禁带宽度变小,光催化自清洁能力增强。

光催化技术在纺织领域的研究及应用进展

太阳能光催化技术因环保、低成本的特点备受研究者青睐,将光催化技术应用于纺织领域的研究已取得一定的成果。半导体光催化剂在光辐照下吸收光子能量并激发出具有强氧化还原能力的活性自由基,以此分解有机污染物。综述光催化材料的常用载体以及其在纺织品上的负载方法,归纳其赋予纺织品的特殊功能。研究表明,光催化材料处理纺织印染废水具有很好的应用前景;经过光催化剂整理的织物可获得自清洁、抗菌以及防紫外线的功能,减少纺织品的洗涤次数,有效保护人体皮肤健康;将光催化剂负载于纤维或织物上有效提升其可回收利用性。

分体式自清洗工业废气余热回收装置设计

为解决化纤生产废气余热回收装置运行一段时间后因污垢层积而换热效率下降的问题,提出一种分体式自清洗工业废气余热回收装置。设计了分体式换热器,采用PLC控制刷洗机构、拉板小车和高压喷头,实现了换热翅片管排的自动分合和清洗功能。测试结果显示,分体式自清洗工业废气余热回收装置能维持较高的换热效率,较原有整体式装置效率提升大约5%,清洗时间由10h缩短为2.5h。该余热回收装置可提高能源利用效率,降低生产成本,减少维护时间,为低品位热能回收利用提供了参考。

新型射孔动态仿真模拟及适用性评价

射孔完井技术的发展与完善对油气田的高效测试和开采具有重要的现实意义和实用价值。但低渗透储层(如低渗煤层)采用常规聚能射孔完井时,存在压实损坏带,导致渗流阻力大、产能降低等问题。为改善低渗透储层的开发效果,提出了自清洁、后效体等新型射孔技术,但其射孔效果、适用性等问题尚不明确。基于LS-DYNA的显示时间积分算法及流固耦合机理,形成地层-水泥环-套管-射孔弹动态射孔有限元模型建立方法,制定了不同射孔技术条件下动态射孔数值模拟方案,建立了不同射孔技术的有限元模型,并开展了不同射孔技术动态射孔仿真模拟研究,基于数值模拟研究结果,对2种射孔技术的适用性进行了分析研究。结果表明:自清洁和后效体射孔较常规射孔孔深有所下降,但孔径较常规射孔扩大15%左右。孔深和孔径与抗压强度、弹性模量、围压成反比,与孔隙率成正比,负压对单一射孔效果的影响较小。针对中孔低渗、低孔低渗油气藏,自清洁、后效体射孔技术孔道容积较常规分别增大9.55%、12.23%左右,射孔效果突出。上述研究结果可为自清洁与后效体射孔技术的设计与应用提供理论支撑,对两种射孔技术的发展及其对低渗储层(如低渗煤层)油气井的增产有着重要的意义。

高透光纳米SiO_(2)/碱性有机硅低聚物复合自清洁涂层的制备

制备了一种具备高透光性的SiO_(2)/碱性有机硅低聚物超疏水复合自清洁涂层。首先以正硅酸乙酯(TEOS)为原料、全氟癸基三甲基氧硅烷(PFDT)为改性剂,通过Stober法得到SiO_(2)改性粒子溶液,然后以TEOS与γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560)为预聚物、PFDT为改性剂,在碱性条件下制备出改性的机硅低聚物溶液。将改性的SiO_(2)溶液与改性的碱性有机硅低聚物溶液按比例混合,最后将混合溶液喷涂于载玻片上,室温下静置6h得到透明超疏水自清洁涂层。探究了有机硅低聚物中TEOS、KH560以及氨水的量对复合涂层的影响。结果表明:当氨水、TEOS、KH560的量分别为1mL、6mL、0.4g,SiO_(2)改性溶液与碱性有机硅低聚物量的比值为2∶1时,涂层的接触角达到150°,透光率为91%,附着力为1级。涂层具有良好的自清洁性能,在经过300℃的高温加热后仍保持其疏水性。涂层制备工艺简单,适用于大规模工业生产。

基于有机硅改性聚氨酯/二氧化硅的超疏水棉织物制备及其性能分析

为提高水性聚氨酯整理棉织物的疏水性,采用侧链型聚二甲基硅氧烷与硅烷偶联剂KH550制备交联型水性有机硅改性聚氨酯(WSPU)乳液,然后将疏水二氧化硅(SiO_(2))粒子的分散液喷涂在经WSPU浸轧整理的棉织物表面,制备得到基于WSPU/SiO_(2)的超疏水棉织物。考察KH550的质量分数对WSPU乳液烘干后所得乳胶膜性能的影响,探讨了WSPU与SiO_(2)复合整理棉织物的结构与性能之间的关系。结果表明:当KH550的质量分数为3.0%时,WSPU乳胶膜具有良好的机械性能与疏水性。当SiO_(2)分散液的质量分数为1.0%时,WSPU与SiO_(2)复合整理后的棉织物表面富集硅元素且具有微纳复合结构,织物水接触角达151.8°,滚动角为4.8°,呈现较好的自清洁性能与抗黏附性能;由于复合涂层与纤维间存在物理作用及化学键合,WSPU与SiO_(2)复合整理棉织物具有优异的耐水洗牢度,经20次水洗后水接触角仅下降3.0°。该研究为制备性能稳定的超疏水织物提供了参考。

基于自监督的主动标签清洗

主动标签清洗利用主动学习来进行标签噪声处理,以降低人工标注成本。现有的主动标签清洗方法仍然存在人工额外标注成本较高的问题,即挑选出的可疑样本中正确样本所占比例较高。为了缓解这一问题,提出了一种基于核心集的自监督主动标签清洗方法。首先利用自监督任务进行表征学习,随后将数据映射到特征空间中,并利用贪婪的K-Center集合覆盖方法挑选出可疑样本,最后根据不确定性筛选出标签噪声样本进行重标注。并同时考虑到了样本的代表性与不确定性,能够有效降低可疑样本中正确样本的比例。在含有不同比例标签噪声的公开数据集上的实验结果表明,在各迭代轮次中明显地降低了人工额外标注成本,同时也在一定程度上缓解了冷启动问题。此外,还通过消融实验证明了方法中自监督核心集采样模块和不确定性预测模块的有效性。

玻璃表面超疏水自清洁SiO_(2)聚氨酯复合膜制备研究

采用高稳定性SiO_(2)溶胶、聚氨酯树脂、长链烷基硅烷偶联剂等制备一种用于自清洁玻璃的高分子镀膜液,可在玻璃表面形成自清洁涂层。SiO_(2)溶胶粒子能提高涂料的耐高温和耐磨性,涂层的耐久性好。SiO_(2)溶胶是以含氟改性剂为核制得的核壳型溶胶颗粒,尺寸均一,在涂料中不易团聚,相容性好,贮存稳定性高;将SiO_(2)溶胶和聚氨酯混合,硅氧键经催化水解后进一步对高稳定性SiO_(2)溶胶与聚氨酯接枝,形成复合粒子。采用呼吸图法在光学玻璃表面采用简便的一步法原位制备仿荷叶结构多孔状的功能高分子自清洁膜,实现超疏水性,达到自清洁的效果。接触角为153.1°,耐沾污4%,孔径在700nm左右,在400-800nm波长范围内平均透光率在91.5%左右,稳定性高,贮存时间长,形成的涂膜稳定性好,能满足日常透光需求。