Mussel-inspired polydopamine (PDA) modification of membrane is an effective alternative for improving permeation flux and anti-fouling performance. Meanwhile, efficient method for oil-water emulsions ...separation is still highly desired. However, problems, such as time-consuming process and low utilization ratio of expensive raw material, have always been stumbling block to application of this strategy. In this study, inkjet printing of dopamine (DA) followed by UV light irradiation to modify mussel-inspired polyvinylidene fluoride (PVDF) membrane was proposed. Accordingly, PVDF membrane was inkjet printed by alternately using DA inks and alkaline tris (hydroxymethyl) aminomethane (Tris) ink. The resultant membrane was then subjected to photopolymerization under UV irradiation to form a PDA layer. Successful formation of PDA layer on membrane surface was verified by series of physical and chemical methods. The optimized membrane (DA80-60/PVDF) exhibited superior oil/water separation performance with 1.5 times permeate flux higher than that of the pristine PVDF membrane and above 99% oil rejection rate. Meanwhile, the modified membranes showed satisfactory stability in aqueous solution with wide pH range (pH 2.0–7.0). The novel membrane modification method proposed in this study is facile, cost-saving and environment-friendly, serving as a competitive candidate for fabrication of efficient membranes for oil-water emulsion separation.
Display omitted
•A new method integrating inkjet printing of PDA and UV irradiation was proposed.•Successful formation of PDA layer on membrane surface was verified.•The optimized membrane had superior oil-water separation performance.•The proposed membrane modification method is facile, cost-saving and environment-friendly.
Display omitted
Inspired by the mussel adhesion mechanism, plant polyphenol tannic acid (TA) with abundant catechol groups and hydrophilic Jeffamine (JA) containing amino groups were used in a ...layer-by-layer (LBL) process to fabricate composite nanofiltration (NF) membranes in this study. Alternately immersing a polyacrylonitrile substrate into individual TA and JA buffer solutions could readily construct a NF membrane selective layer without any pre-treatment to the substrate. The optimised membrane showed a high pure water permeance of 37 L m−2 h−1 bar−1 whilst maintaining rejections higher than 90% towards various dyes with molecular weights ranging from 269 to 1017 g mol−1. Particularly, the obtained membrane exhibited excellent anti-fouling and long-term performance attributed to the hydrophilic membrane surface and covalent bonds in the selective layer. The novel strategy inherited the advantages of a mussel-inspired dopamine material but overcame its disadvantages. The results disclosed in this study not only provide a novel strategy to prepare composite NF membranes, but also facilitate the mussel-inspired LBL design of advanced materials for environmental applications.
Though sludge foaming often occurs and thus causes serious membrane fouling in membrane bioreactors (MBRs), the fouling mechanisms related with the foaming phenomenon have not been well addressed, ...hindering better understanding and solving foaming problem. In this work, it was interestingly found that, the foulants during the foaming period possessed extremely high specific filtration resistance (SFR) (over 1016 m kg−1) and strong adhesion ability to membrane surface. Chemical characterization showed that the proteins (178.57 mg/L) and polysaccharides (209.21 mg/L) in the foaming sample were about 6.4 times and 5.4 times of those in the supernatant sample, suggesting existence of a mechanism permitting continuous production of these foulants in the MBR during the foaming period. It was revealed that the fouling caused by foams was associated with gel layer filtration process, and the extremely high SFR can be interpreted by chemical potential change in the gel filtration process depicted in Flory-Huggins theory. Meanwhile, analyses by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory showed that the strong adhesion ability stemmed from the high interaction energy between the foaming foulants and membrane surface. In addition, 16S rDNA gene sequencing identified that the abundance of the foaming related bacteria species in the sludge suspension during the foaming period was more than 10 times of that during the non-foaming period. This study offered new mechanism insights into foaming fouling in MBRs.
Display omitted
•Foaming foulants had a high specific filtration resistance (SFR) of 1.11 × 1016 m kg−1•There is a mechanism permitting continuous production of foaming foulants in the MBR.•High foaming SFR was related with gel filtration and caused by chemical potential gap.•The strong adhesion ability of foams stemmed from the high interaction energy.•Abundance of foaming related bacteria is 10 times of that during non-foaming period.
•PANI/CA membrane was studied for adsorbing Hg(II) and Cr(VI).•The new membrane preparation method is convenient, does not use toxic solvent.•The doping agent-Phytic acid improved the adsorptive ...capacity.•PANI-PA/CA membrane possesses higher BET surface area and electrical conductivity.•PANI-PA/CA membrane has high adsorptive capacity for Hg(II) and Cr(VI).
Conductive composite membrane—phytic acid (PA) doped polyaniline (PANI)/cellulose acetate (CA) (PANI-PA/CA) was prepared in a simple and environmental-friendly method, in which aniline was blended with CA/PA solution and polymerized before the phase conversion. The resultant composite membranes were characterized by SEM, EDX, FTIR-ATR, BET and electrical resistance measurements. When used as adsorbent for Hg(II) and Cr(VI) ions, the prepared composite membrane exhibits excellent adsorption capability. The adsorption of Hg(II) and Cr(VI) follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model, with the maximum adsorption capacity reaching 280.11 and 94.34mgg−1, respectively. The heavy metal loaded composite membrane can be regenerated and reused after treatment with acid or alkali solution, making it a promising and practical adsorbent for Hg(II) and Cr(VI) removal. Tests with river water were also carried out, indicating good performance and application.
This paper presents a drowsiness on-line detection system for monitoring driver fatigue level under real driving conditions, based on the data of steering wheel angles (SWA) collected from sensors ...mounted on the steering lever. The proposed system firstly extracts approximate entropy (ApEn)featuresfromfixedslidingwindowsonreal-timesteeringwheelanglestimeseries. Afterthat, this system linearizes the ApEn features series through an adaptive piecewise linear fitting using a given deviation. Then, the detection system calculates the warping distance between the linear features series of the sample data. Finally, this system uses the warping distance to determine the drowsiness state of the driver according to a designed binary decision classifier. The experimental data were collected from 14.68 h driving under real road conditions, including two fatigue levels: "wake" and "drowsy". The results show that the proposed system is capable of working online with an average 78.01% accuracy, 29.35% false detections of the "awake" state, and 15.15% false detections of the "drowsy" state. The results also confirm that the proposed method based on SWA signal is valuable for applications in preventing traffic accidents caused by driver fatigue.
The contrast sensitivity function (CSF) is routinely assessed in clinical evaluation of vision and is the primary limiting factor in how well one sees. CSF improvements are typically brought about by ...correction of the optics of the eye with eyeglasses, contact lenses or surgery. We found that the very act of action video game playing also enhanced contrast sensitivity, providing a complementary route to eyesight improvement.
While polyphenol-based coating has been regarded as a promising alternative to functionalize membrane surface, it usually suffers from problems of low-efficient procedure and low utilization rate of ...the polyphenolic compounds, hindering its large-scale implementations. To solve these problems, this study provided a first report on inkjet printing of polyphenols (catechol (CA) or tannic acid (TA)) and sodium periodate (SP) on a polyvinylidene fluoride (PVDF) membrane to improve membrane performance. A series of analyses showed the efficient formation of homogenous films on the PVDF membrane surface and the improvement of hydrophilicity by the inkjet printing technique. The PVDF membranes decorated with the optimized polyphenolic coating exhibited a promising oil/water separation efficiency (higher than 99%) with a high average water permeation flux of 5.2 times higher than that of the pristine membrane. Meanwhile, the modified membranes illustrated a good stability under acidic conditions (pH = 2–7). The novel method proposed in this study is facile, cost-saving and environment-friendly. The advantages of the proposed method and the modified membranes demonstrated the great significance of the proposed method in practical applications.
Display omitted
•a new method of inkjet printing of polyphenol-based coating on membrane was proposed.•This method can efficiently coat homogenous films on the PVDF membrane surface.•The optimized membrane showed 99% oil/water separation with 5.2 times enhanced flux.•The modified membranes illustrated good stability under acidic conditions (pH = 2–7).•The proposed method is facile, cost-saving and environment-friendly.
Polyvinylidene fluoride (PVDF) is rarely used as substrate membrane for thin film composite polyamide (PA) nanofiltration (NF) membrane due to its hydrophobic surface pushes water away during ...interfacial polymerization. According to Jurin's law, the pressure of membrane surface pushed water away is inversely proportional to the radius of membrane pore. In this study, a series of commercial PVDF membranes with pores ranging from 25 to 450 nm were used as substrates in a traditional interfacial polymerization. This preparation process does not need any pre-modification on substrate or specific equipment. It was found that the PVDF substrate pore size greatly influences the morphologies and surface properties of the corresponding TFC PA NF membrane. Only when a PVDF substrate has moderate pore size, such as 50 and 100 nm, could a continuous and defect-free PA layer will be formed, as verified through SEM characterization. The TFC membrane prepared with the PVDF substrate of 100 nm exhibits a 27.0 L m-2 h-1 bar-1 pure water permeance, and a 96.2% Na2SO4 rejection. The facile and effective method demonstrated in this study provides a new thought for the preparation of PVDF substrate supported PA NF membrane.
Display omitted
•Hydrophobic PVDF membranes were used as substrates for TFC membrane preparation.•Substrate pore size influences membrane morphology and separation performance.•Continuous and defect-free polyamide layers were formed at pore size of 50 and 100 nm.•No pre-modification or harsh condition was needed in membrane preparation.
The present study reviewed the relevant recent literature regarding the development and application of oblique lumbar interbody fusion (OLIF), with a particular focus on its application and ...associated complications. The study evaluated the rationality of this technique and demonstrated the direction of future research by collecting data on previous operative outcomes and complications. A literature search was performed in Pubmed and Web of Science, including the following keywords and abbreviations: anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), direct lateral interbody fusion (DLIF), extreme lateral interbody fusion (XLIF), oblique lateral interbody fusion (OLIF), adjacent segment disease (ASD), and adult degenerative scoliosis (ADS). A search of literature published from January 2005 to January 2019 was conducted and all studies evaluating development and application of OLIF were included in the review. According to the literature, the indications for OLIF are various. OLIF has excellent orthopaedic effects in degenerative scoliosis patients and the incidence of bony fusion is higher than for other approaches. It also provides a better choice for revision surgery. It has various advantages in many aspects, but the complications cannot be ignored. As a new minimally invasive technique, the advantages of OLIF are obvious, but further evaluation is needed to compare its operation‐related data with that of traditional open surgery. In addition, more prospective studies are required to compare minimally invasive and open spinal surgery to confirm its specific efficacy, risk, advantages, learning curve, and ultimate clinical efficacy.
User-generated content (UGC) on social media platforms plays a significant role in conveying individual sentiments that are effective in predicting image sentiments by evaluating its contents to ...excavate the behaviour and cognition of image producers at attraction-level tourist destinations. In this study, we aim at the attraction-level study of the spatiotemporal behavior of photo-taking tourists. We used the deep convolutional neural network model DeepSentiBank (DSB) for sentiment prediction of Flickr photos. Then, Latent Dirichlet Allocation (LDA) was employed to categorize these sentiment predictions according to the noun content of specified distinct groups. Next, Kernel Density Estimation (KDE) was used as a spatial analysis tool to determine the spatial distribution characteristics of tourists' behaviors. The photo-taking behavioural patterns of different tourist types are analyzed from the individual preferences of tourists and depicted in terms of both visual semantics and spatiotemporal behavioral features. It is observed that the proportion of landscape preferences of the thematic tourists are not significantly affected by seasons but by the aggregate activities of thematic tourists that significantly vary in autumn. The findings obtained from the analysis hold immense significance in the realm of tourism and hospitality management which can play a significant role in the development of facility management, regional tourism, and prospects.
PDF
