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Determining the similarity between short texts plays an important role in natural language processing applications such as search, query suggestion and automatic summary, which has attracted widespread attention. Unlike traditional long texts, short texts present the characteristics of short length, weak signal, and high ambiguity. Researchers have proposed many methods, from simple vector space models to more sophisticated distributed semantics. However, these methods only consider the literal meaning of words, ignoring the impact of word ambiguity and the semantic information contained in the structure of the short text. Additionally, words on their own are often insufficient for expressing semantics, as many terms are composed of multiple words. In this paper, we propose a method based on semantic and syntactic information for short text similarity calculations by using knowledge and corpora to express the meaning of the term to solve polysemy, and using a constituency parse tree to capture the syntactic structure of short texts. Additionally, the proposed method uses terms as semantic units. Experimental results on ground-truth datasets demonstrate that the proposed method outperforms baseline methods.

In this study, hydroxyethyl cellulose (HEC) was cross-flow deposited on flat-sheet polypropylene (PP) porous support and insolubilized by cross-linking using glutaraldehyde (GA) to fabricate cost-effective thin-film composite membrane for aqueous and non-aqueous nanofiltration. Membrane physico-chemical property, permeation performance, as well as tolerance to acid, alkaline and organic solvents were systematically characterized. The obtained HEC/PP composite membrane was found to be effectively modulated in pore size via changing HEC and GA contents and possessed good fabrication reproducibility. The desired HEC/PP composite membrane with an average pore diameter of around 2.21 nm exhibited high fluxes of 41.0 and 8.2 L/m2 h to pure water and ethanol, respectively, and removals of 99.9%, 99.9% and 96.7% to 50 mg/L dye aqueous solutions of methyl blue, Congo red and sunset yellow, respectively. Soaking tests revealed that the HEC/PP composite membrane possessed good tolerance to acid, alkali and organic solvents of tetrahydrofuran, ethyl acetate and ethanol. Continuous filtration of dye/ethanol solution demonstrated that the HEC/PP membrane possessed excellent long-term durability in ethanol solution, maintaining a stable flux higher than 4.6 L/m2 h and removals of 95.4% and 84.2% to methyl blue and Congo red, respectively, during the whole filtration of 110 h.

User identification has been attracting considerable attention from academia. Due to the uniqueness and difficulty of faking friendship networks, some friendship-based methods have been presented to improve the identification performance. However, the information redundancies in k-hop (k > 1) neighbors and their contributions to user identification have not been fully analyzed in the existing work. Addressing these two issues helps to understand the problem of friendship-based user identification and to propose more effective solutions. In this paper, we first obtain ground-truth friendship networks across three popular social sites; then, we analyze the similarities of k -hop neighbors to fully characterize the information redundancies in the friendship network. We apply these information redundancies in several classifiers to study their contributions to user identification. Furthermore, we apply the friendship-based information redundancies jointly with the display-name-based information redundancies to perform user identification. The experiments show that (1) the similarities related to the 1-hop neighbors contribute to user identification much more than do the other similarities; (2) the information redundancies in the k-hop (k > 1) neighbors are also very useful for user identification; and (3) jointly applying display-name-based information redundancies can provide better performance and improve the universality of the identification method.

This paper aims to validate the feasibility of hairwork dyeing effluent (HDE) reclamation using an ultrafiltration (UF)-reverse osmosis (RO) integrated membrane system combined with coagulation-flocculation and sedimentation acquiring the highest possible product water recovery rate along with both satisfactory separation performance and well controlled membrane fouling. Under the circumstance of only physical cleaning involved, the laboratory-scale test yielded a higher and satisfactory reuse ratio of 76% for HDE, and the corresponding RO product as reclaimed water contained only 223 mg·L−1 of TDS, 3.87 mg·mL−1 of DOC and 10.3 mg·mL−1 of total hardness, which was obviously better than the quality of existing feedwater in hairwork dyeing process. After each processing unit, the distributions of fulvic (region III) and humic (region V) organics decreased continuously, while an overall rising trend in distribution of protein-like organics (regions I and II) was observed. Contact angle for the fouled UF and RO membranes significantly increased by 19.5° and decreased by 19.7°, respectively, which suggested that different polarity of organic or inorganic adsorption rather than membrane roughness was the main factors affecting wetting properties of the fouled employed membranes. Both ATR-FTIR and XPS spectra indicated that organic fouling on UF membrane surface under harsh condition (RUF = 90%) was mild and tolerable, whereas a surprising amount of hydrophilic micromolecular organics riched in carboxyl and hydroxyl functional groups were absorbed on RO membrane surface after permeation.

As a result of distinctive nanopores of two-dimensional material, graphene oxide (GO) has emerged as a new-generation membrane for high performance water separation. However, GO-based composed membrane applied to dye desalting gains less attention. A series of novel ultrathin and stable polydopamine/graphene oxide (PGO) membranes has been successfully fabricated via intercalation polymerization of dopamine using triple vacuum filtration. The polymerized dopamine (PDA) via intercalation polymerization in the interspace between the lamellar layers is used to simultaneously improve the stability of GO film and rapid passage of ions. The high permeation of pure water of as-prepared PGO membranes is investigated through adjusting the thickness (9–126 nm) of modified layers. In addition, the values decrease from 24.2 to 0.65 L m−2 h−1 bar−1 with increasing the layer. With the ultrafast ion transport and dyes rejection under cross-flow condition, the stability PGO membranes show a good capability for desalination dyes and concentration of dye (11.6 times of the initial dye solution).

The performance of nanofiltraton (NF) membranes are characterized by a high selectivity for multivalent anions, whereas poor selective separation capacity for multivalent cations and heavy metal ions. In this work, a new positively charged NF membrane was prepared by using 2-chloro-1-methyliodopyridine as an active agent to graft polyimide polymer onto the membrane surface via covalent bonding with surface carboxylic groups. The results showed that the prepared membranes had a high selective separation for divalent and monovalent salts (MgCl2 97.1%, CaCl2 96.8%, Na2SO4 83.5%, MgSO4 87.3%, NaCl 49%, LiCl 32%), and also exhibited a high removal efficiency for toxic heavy metal ions and dyes (CuCl2 96%, NiCl2 95.8%, CrCl3 98.0%, Tropaeolin O 98.3%, Victoria blue B 99.2%, Semixylenol orange 99%, Neutral 98.2%).

Most thin film nanocomposite (TFN) membranes with higher permeability are related to hydrophilic nanocomposites. Nevertheless, in nature, water permeates faster in hydrophobic pores (e.g. aquaporin) because of less affinity between water and wall of the pore. Here we show hydrophobic methyltrichlorosilane (MeSiCl3, MTS) functionalized polyamide TFN can be used to construct highly efficient desalination membranes. The TFN membranes were synthesized through the interfacial polymerization of aqueous amine and organic MTS/acyl chloride solutions. Both the water flux and water/salt selectivity increased. The water flux increased by more than a factor of 1.96, from 2.4 to 4.7 LMH/bar, as the fraction of MTS increased from 0 to 0.1 mM in the organic solution. Importantly, the water/salt selectivity ratio increased from 11.4 to 18.5 bar−1. Thus, MeSiCl3 imparted narrow water channels to the polyamide matrix with higher flow rate and better selectivity. The enhanced compatibility and interactions between MTS and the polyamide polymers were attributed to their covalent (Si N) and hydrogen (O…H) bonds. MTS modified TFN membranes also show high water flux and recovery ratio in the bovine serum albumin (BSA) solution. This facile in situ modification provides a new insight into the high performance of hydrophobic TFN membranes.

Surface-initiated atom transfer radical polymerization (SI-ATRP) can precisely control the graft length and graft density of polymers. In this work, nonfouling nanofiltration membrane with tunable zwitterionic layer was fabricated by grafting sulfobetaine methacrylate (SBMA) on the surface of 2-bromoisobutyryl bromide (BIBB) -immobilized polyamide membranes (PA-Brs) via SI-ATRP. Zwitterionic layer with different graft length and graft density can be adjusted by varying the BIBB concentration or ATRP time, which can thus tune water flux and antifouling property of the membranes. When BIBB concentration is 1.00 wt% and ATRP time is 0.2 h, the optimal flux is 63.9 L m−2 h−1. In addition, the amount of foulant adsorbed on membrane is less than 20 μg cm−2. Flux decline ratio is about 5% and flux recovery ratio is more than 98% when humic acid is used for dynamic test, suggesting a nonfouling performance of zwitterionic membrane with SBMA graft content above 26 mol%.

Evaporation is significantly important for the preparation of isoporous membranes from self-assembly and non-solvent induced phase separation (SNIPS). Unfortunately, the time of solvent evaporation that retains isoporous structures is usually rather short, which causes many challenges to fabricate membranes with repeatable and controllable isoporous structures. In the current work, we used organic acids to tailor and enlarge the time window that led to isoporous structures, and their effects on membrane formation were investigated. It was found that binary and ternary organic acids all worked effectively and were able to extend the time window that produced isopores to longer than 200 s. In previous publications, this time duration was commonly in the range from several to tens of seconds. The nuclear magnetic resonance (NMR) determination implied that molecular cross-linking between acids and copolymers was existed in solution, and results from small angle X-ray scattering (SAXS) analysis demonstrated that the microphase separation of the block copolymer in casting solution was enhanced by the selected acids. The results proved that binary and ternary acids added to casting solution had not only enhanced the microphase separation but also stabilized the phase separated domains, which was ascribed as the reason for the extension of the time window. The effectiveness of organic acids on broadening the time window was also found for casting solutions of different concentrations and solvent compositions. Besides the role on stabilization of isoporous structure, the flux of isoporous membrane was also greatly increased by the organic acids.

The ridge-and-valley roughness structure of a polyamide reverse osmosis (RO) membrane has a paramount impact on its separation performance. We show that this surface roughness appearance was shaped by gas nanobubbles confined between the polyamide rejection layer and the substrate. Performing interfacial polymerization (IP) under alternative confinement conditions led to drastically different surface morphologies, e.g., smooth polyamide surface formed at support-free aqueous/organic interfaces whereas crater-like features formed in inversed IP. For the first time, we demonstrated the collapse of fully hydrated balloon-like nodules into dehydrated leaf-like and donut-like roughness features during membrane drying by performing an in-situ atomic force microscopic characterization. Deformation of roughness features caused by dehydration was not fully reversible, which correlates well with the dramatic reduction of membrane permeability upon drying. Our study provides a fundamental framework for the surface roughness formation in RO membranes, which is critical for advancing roughness control technologies with enhanced membrane performance.

In this study, a new type of polyimide (PI) composite material was synthesized by a two-step method using 2,3,5,6-tetramethyl-1,4-phenylenediamine (TMPDA), 4,4′-methylenedianiline (MDA), and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA). The PI material was then used to prepare an ultrafiltration (UF) membrane by phase inversion method. The membrane showed a dense surface layer, a porous sublayer, and fully developed finger-like macrovoids at the bottom, which had excellent hydrophilicity and antifouling property. In the recovery experiments with a protein solution, the PI membrane displayed a satisfactory water flux recovery ratio of 90.03%. The PI membrane can operate stably in 1 mol L−1 hydrochloric acid solution, and the retention rate of BSA remains at 93%. In addition, the flux of the membrane is 325.60 L m−2 h−1 and the BSA retention rate the retention rate is still higher than 95% after soaking in various solvents for 7 days.

An excellent positively charged nanofiltration (NF) membrane is of great significance for water softening. In this work, a novel positively charged composite PEI/TMA NF membrane was prepared by gradient cross-linking polyethyleneimine (PEI) with trimesic acid (TMA) on polyethersulfone ultrafiltration (PESU) membrane. The effects of concentration of PEI and TMA, the cross-linking reaction temperature and reaction time on membrane structure and performance were investigated in detail. The effects of PEI and TMA, reaction temperature and time on the membrane structure, composition and performance were investigated. The optimized preparation conditions of PEI/TMA NF membrane were fixed at 0.6% (m/v) PEI, 0.1% (m/v) TMA, 0.15% (m/v) SDS at 90 °C for 10 min. The as-prepared membrane exhibited a pure water flux of 19.1 L m−2 h−1 bar−1 and a rejection of MgCl2 93.0%, NaCl 38.2%, MgSO4 20.4%, and Na2SO4 8.8%. The functional layer is ultra-thin. Its high selectivity mainly results from Donnan effect. The long-term testing of our PEI/TMA NF membrane show a high stability. Compared with other positively charged membranes, the PEI/TMA NF membrane had unique advantages in the production process and a comprehensive performance.

Hollow porous nanoparticles were proposed to transform the skin layer structure for enhancing the performance of reverse osmosis (RO) membrane in this work. Amino-modified hollow mesoporous silica nanospheres (AHMSS) with a size from 110 to 130 nm were successfully prepared via the hard template method. AHMSS were added in the organic phase and then incorporated into the RO membrane skin layer after the interfacial polymerization process. The hydrophilicity of RO membrane was improved by AHMSS. The performance evaluation results showed that AHMSS improved the RO membrane flux (improved by 41.5%) with rejection decreasing slightly. Amino-modified mesoporous silica nanospheres without hollow cores were also prepared and incorporated into the RO membrane skin layer to investigate the effects of the hollow cores of AHMSS on the membrane performance. The results showed that the hollow cores of AHMSS contributed to the improvement of membrane performance. This work demonstrates that AHMSS have huge potential in preparing RO membranes with both high flux and high rejection.

The removal of boron from seawater remains a challenge and now receives increasing attention worldwide. Boron removal rates offered by conventional reverse osmosis membranes through one-pass desalination processes are not sufficient to achieve WHO standard. In this paper, the UiO-66 nanoparticles, a metal-organic framework (MOF), are proposed to incorporate into the polyamide (PA)-based thin film nanocomposite (TFN) reverse osmosis (RO) membrane for boron removal due to their inherent porous structure, narrow pore size, and strong adsorption to boron. At an optimum blending concentration of 0.05% (w/v), The UiO-66 TFN membrane showed a ∼50% increase in water flux and a marginal increase in rejection compared with the benchmark thin film composite (TFC) membrane in the brackish water desalination test. In a simulated seawater desalination test, the UiO-66 blended TFN membrane promotes the boron rejection by ∼11% compared with the benchmark membrane. The simultaneous increase of water flux and boron rejection at low blending concentrations are likely attributed to the highly porous structure which provides additional pathways for water transport and the strong adsorption to boron which indued a further pore narrowing effect to its intrinsic pore size of ∼6.1 A. Therefore, this work provides a new and facile approach to enhance the boron removal rate of the polyamide-based RO membrane via the incorporation of UiO-66 nanoparticles.

Environmental stimuli-responsive membranes have many latent applications in numerous fields, for example, chemical/biological separations, water treatment, drug delivery, self-cleaning material and chemical sensor. In this study, a pH-responsive membrane with in-situ assembled stimuli-responsive microgels on membrane surface and internal channels wall was fabricated by the coagulation step of the phase-inversion process. Interestingly, it was found that poly(4-vinyl pyridine) (P4VP) microgel can be mobilized onto the membrane surface by using an acidic coagulation bath. Meanwhile, the membrane-based materials with different hydrophobic properties showed a great effect on the migration of microgel onto the channel surface. The inner pores of these responsive membranes can self-adjust its size with the changes of outside pH stimulus. Moreover, the gate-controlled water permeability of pH-responsive membranes was explored at the pH interval from pH 2 to pH 6. Investigations revealed that the P4VP microgel-assembled membrane had excellent pH-responsive performance. In addition, these pH-responsive membranes with embedded microgels on surface and inner pores wall also exhibited excellent reversible behaviors and self-cleaning properties.

Exploring a desirable cross-linker applied in cation exchange membranes (CEMs) to improve dimensional stability as well as electrochemical performance has a great signifcance for the current membrane science and technology. In this investigation, a sequence of crosslinked sulphonated polysulfone (SPSF) CEMs has been prepared to explore the influence of the crosslinking functionality on the dimensional stability and electrodialysis (ED) performance of modified membranes. Different cross-linker structures were obtained according to the cross-linker agent content added during the synthesis route. As expected, the membrane surface became smoother with increasing cross-linker content, presumably as result of the denser structure established. The dimension stability increases according to the crosslinking degree applied, whereas the permselectivity of membranes depends on the conjunction of many important and interlinked factors, including the formation of narrow ion transport channels and the variations in the exchanges sites concentration. It was observed that the optimized CEM (60SPSF-C2#) showed the highest NaCl removal ratio (91.7%) during the desalination experiments and exhibited the higher current efficiency (95.7%) and lowest energy consumption (6.55 kWh kg−1). These results suggest the formation of the optimum three-dimensional network configuration for the membrane structure determined by the functionality of cross-liker selected in this investigation.

GO is of great interesting for membrane materials due to its unique properties including antimicrobial activity and antifouling property. However, the differences between GO nanosheets and layered GO membranes gained little attention. Herein, we fabricated GO membranes that have a thickness of around 30 nm and a void d-spacing of 0.67 nm (wet state) with single layer GO nanosheets of 10–75 nm in lateral size and investigated their antimicrobial and antifouling potential for practical use. It exhibits typical nanofiltration performance, with the rejections of 65.23%, 17.79%, 42.10% and 12.47% to Na2SO4, NaCl, Mg2SO4 and MgCl2, respectively. The antimicrobial test demonstrated that GO nanosheets lose their antimicrobial activity after they stacked together. A 14-day test showing that GO membrane has excellent resistance for organic fouling, with reversible fouling of more than 98%. But when it comes to tapwater, the proportion of irreversible fouling is surging to more than fifty percent even after cleaning with 2000 mg/L of sodium hypochlorite. Thus, we suggested that there are more details should be investigated before put layered GO membrane into practical use. Surprisingly, GO membrane exhibits excellent mechanical stability during the 14-day test, showing its exciting potential in water treatment.

The development of high performance membrane is crucial for enhanced separation efficiency of nanofiltration process in treating wastewaters from dye and textile industries. In this work, a novel thin-film composite nanofiltration membrane with an asymmetric separation layer composed of relatively compact skin and loose body was designed and fabricated for improved perm-selectivity and antifouling property. Nascent composite membrane with loose poly(piperazine amide) (PA) separation layer was interfacially synthesized and performed with secondary surface reaction using an aqueous tannic acid (TA) solution. Membrane characterizations verified the formation of compact TA skin on top of the loose PA layer through forming covalent bonds via esterification reaction. Compared with the composite nanofiltration membrane with PA symmetric separation layer having the same glucose rejection of about 82.0%, the permeability to pure water of the composite membrane with PA/TA asymmetric separation layer was higher by 28.0%, the water fluxes to aqueous solutions dissolved with model anionic dyes of alizarin yellow R, sunset yellow and Congo red under steady state were higher by 50.3, 43.9 and 36.1%, and the steady-state flux declines were lowered by 27.8, 43.4 and 23.5%, respectively. Furthermore, the PA/TA-based membrane also exhibited better antifouling property and rejection ability to alizarin yellow R.

The industrial products or wastewater rich in the mixed salts (Cl−/SO42−) not only causes the environmental damage, but also induces waste of resource. In this study, an ED stack with monovalent selective AEMs and conventional CEMs was employed to separate the Cl− and SO42− from simulated wastewater. The effect of current density and mass fraction percentage was investigated in order to optimize the experimental conditions during ED process. It was found that at a concentration ratio between NaCl and Na2SO4 of 95/5 (wt%/wt%) and a current density of 40 mA·cm−2, a current efficiency of 72%, an energy consumption of 1.6 kW·h·kg−1 NaCl and a Cl−/SO42− concentration (67.5/3.5 g·L−1) were obtained. Hence, it is appropriate and effective to separate Cl− and SO42− by ED using the monovalent selective AEMs.

Membrane capacitive deionization (MCDI) is an effective water purification technology. In this work, a monovalent selective cation exchange membrane (CIMS) was assembled in MCDI system (denoted as MSCDI) to separate lithium from magnesium. The effects of feed water quality and operating conditions on the lithium removal selectivity were systematically investigated. Specifically, in optimized conditions, the lithium selectivity coefficient reached 2.95. Furthermore, a custom-made large MSCDI module was applied to the selective removal of lithium. The removal rates of Li+ and Mg2+ in large module reached 38.4% and 19.2%, respectively. It is worth noting that the specific energy consumption was 0.0018 kWh mol−1, which is much lower than that of electrodialysis (0.04–0.27 kWh mol−1). Therefore, relying on its low energy consumption and environmental friendliness, MSCDI has considerable economic benefits for the efficient lithium extraction.

This paper reports a novel class of thin film composite (TFC) membranes for forward osmosis (FO) desalination. The TFC membranes were fabricated via interfacial polymerization (IP) of aqueous mixture of polyethyleneimine (PEI) and graphene quantum dots (GQDs) with organic solution of trimesoyl chloride (TMC) on modified polyacrylonitrile (PAN) ultrafiltration substrates. The chemical structures and morphologies of the synthesized GQDs and the GQDs-incorporated membranes were studied by various characterization techniques. The synthesized GQDs exhibited a narrow size distribution of 1.0–4.0 nm with an average size of 2.19 nm, and the thickness were one to three graphene layers. The results showed that GQDs nanoparticles were covalently bonded to the polyamide chains. The optimized TFC membrane with 0.050 wt% GQDs loading exhibited quite hydrophilic and neutrally charged membrane surface, along with an enhanced water flux of 12.9 L m−2 h−1 and a comparable reverse salt flux of 1.41 g m−2 h−1 when DI water and 0.5 M MgCl2 were used as the feed solution and the draw solution, respectively. Also, the optimized GQDs-incorporated TFC membrane presented an especially good anti-fouling performance. Thus, incorporating the novel graphene nanomaterial into polymer membranes may present its great potential application in desalination, purification and wastewater treatment.

Chemical pretreatment partially modified the structure of lignocellulose to enhance saccharification, leaving unaltered factors to limit further hydrolysis. To overcome these limitations, a biostrategy involving co-pretreatment combining bacteria with a chemical process was developed. A significant complementary effect was observed in specific co-pretreatments, e.g., ligninolytic bacteria enhanced acid pretreatment and saccharolytic bacteria enhanced alkaline pretreatment. Specifically, the ligninolytic bacterium Pandoraea sp. B-6 selectively removed the acidolysis-caused residual lignin and enhanced sugar release by 40.9% to 772.0 mg g−1 compared with that of acid-treated rice straw. After most of the lignin was removed, sugar release from alkali-treated RS was further improved by 31.8% to 820.2 mg g−1 via the saccharolytic bacterium Acinetobacter sp. B-2 through decrystallization. In the complementary mechanism, the active sites produced by chemical cleavage facilitated the bioprocess and further enhanced saccharification. This complementary mechanism provides a novel foundation for designing a rational combination pretreatment.

In situ improvement of fouling resistance of the state-of-the-art polyamide reverse osmosis membrane module on the basis of the fouling characteristic of the fluid to be treated is of great practical significance. In this work, in situ modification was performed with the spiral wound polyamide reverse osmosis membrane module for improved fouling resistance to specific foulant. Small molecular monomers of amidosulfonic acid (ASA), diethanolamine (DEA) and piperazine (PIP) were grafted onto the surface of the flat-sheet polyamide-based thin-film composite membrane within the module separately through 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-activated amidation of carboxyl groups. The results of fouling experiments indicated that the fouling resistance of the polyamide reverse osmosis membrane module to the model foulants of bovine serum protein (BSA), sodium alginate (SA) and dodecyl trimethyl ammonium bromide (DTAB) could be effectively improved through grafting monomers ASA, DEA and PIP, respectively, showing significant reduction in declines of membrane flux to aqueous BSA, SA and DTAB solutions by 47.2%, 41.3% and 34.4%. The changes of membrane surface hydrophilicity and negative charge were in charge of the improved antifouling property. The in-situ modification was also found to slightly enhance membrane salt rejection and have nearly no influence on membrane water flux.