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It is urgent to develop functional nanocarriers for targeted drug therapy of cancer. This work developed a smart drug controlled release system based on the dendritic mesoporous silica nanoparticle (DMSN) for dual gatekeepers drug delivery. The DMSN-Cys grafted with disulfide bonds appeared as spheres of uniform size with a porous structure, which enabled a drug loading efficiency of 68.32%. Since the protonated amino groups of chitosan were responsive to pH and the disulfide bonds were sensitive to glutathione, the modified 5-Fu@DMSN-Cys/CS can be used for pH/GSH responsive drug delivery. Release behaviors showed excellent drug controlled release effects. Good biocompatibility and pronounced cytotoxicity of 5-Fu@DMSN-Cys/CS were confirmed by cytotoxicity test. Noted specially, the microcosmic adsorption interaction between drug molecules and DMSN-Cys has been evaluated through molecular dynamic simulation. Electrostatic potential and adsorption simulation confirmed that the driving force of 5-Fu adsorption was originated from electrostatic force and hydrogen bonding interaction between the nanocarriers and 5-Fu molecules. These results indicated that 5-Fu@DMSN-Cys/CS could be potential carriers for anticancer drug delivery. [ABSTRACT FROM AUTHOR]

Imidazolate-based ZIF-8 catalysts M@ZIF-8 (M = Au NR, Au@Ag NR, or Au@PtAg NRT; NR = nanorod, NRT = nanorattle), were assembled. Au NRs acted as the core for the epitaxial growth of the Ag shell, and oxidative etching of Au@Ag NRs led to Au@PtAg NRTs with K2PtCl4 aqueous solution. All metal nanorods (MNRs) and metal nanorattles (MNRTs) were well dispersed and fully encapsulated in ZIF-8. Au@PtAg NRTs encapsulated in ZIF-8 could lead to enhanced stability and selectivity for catalytic applications, combining the advantages of ZIF-8 (tailorable porosity) with the high surface area and improved optical sensitivity of rod-shaped NRTs. The catalyst Au@PtAg@ZIF-8 exhibited efficient catalytic activity and CO selectivity for the gas-phase photoreduction of CO2 with H2O. [ABSTRACT FROM AUTHOR]

Firstly, preparation of porous polyvinyl alcohol (PVA) spheres were investigated in detail by phase inversion method using N,N-dimethylacetamide (DMAc) and polyvinylpyrrolidone (PVP) as pore-forming additives. The morphology and pore structure of PVA spheres were characterized by SEM and BET measurements. It was found that the addition of DMAc and PVP increased the pore volume and the surface pore size of PVA sphere respectively. The maximum surface area of the porous PVA sphere reached 220 m2/g. Secondly; the synthesis of photoactive TiO2 NPs (anatase type) at the low temperature was developed by controlling the aging process of the TiO2 precursors. The crystallinity and photoactivity of TiO2 NPs increased with the aging time. Finally, TiO2 NPs/PVA composite spheres were prepared by immersing PVA sphere into TiO2 precursor solution. Their structures were characterized by XRD pattern, TEM and TGA measurement. It was found that TiO2 NPs were successfully immobilized into PVA spheres. The photodegradation of methyl orange (MO) under UV light by TiO2/PVA spheres showed a good photocatalytic efficiency. Moreover, TiO2/PVA spheres can be easily regenerated by the repeated immersion process. Overall, the porous TiO2/PVA sphere displays a good photoactive property and an advantage of easier recovery, which facilitates its application in large-scale wastewater treatment. [ABSTRACT FROM AUTHOR]

Using 316L stainless steel powder (SSP) with a nominal particle size of 25 μm, porous stainless steel hollow fibers (SSHFs) have been prepared via dry-wet spinning of a particle-loaded casting solution based on non-solvent induced phase inversion, followed by temperature programming sintering. The morphology and performances were characterized by the maximum/mean pore size, SEM, porosity, density, shrinkage, pure water flux and mechanical strength. Subsequently, SSHFs were modified by adding TiO, ZrO and SiO nano-particles for the first time. The morphology of SSHFs relied on not only the SSP contents, but also the contents of TiO, ZrO and SiO nano-particles. The corresponding results demonstrated that SSHFs with TiO nano-particles possessed excellent properties, especially for mechanical strength having a more than 100 % increase and a maximum pore size of 4.5 μm. What's more, nano-particles also reduced the defects of SSHFs' structure, which could be observed from SEM images. [ABSTRACT FROM AUTHOR]

The porous Polyvinylidene fluoride (PVDF) nanofibers were prepared by leaching method using polyethylene oxide (PEO) as porogen for the first time. The influences of the molecular weight (MW) and concentration of PEO, and the leaching solution on the morphology and the surface area of the porous PVDF nanofiber were systematically investigated. Polyethylene glycol 6000 (PEG6000) showed a better pore-forming effect. Optimized preparation parameters were obtained. With the ratio of PEG6000/PVDF reaching 1:1, the surface area of the resulting porous PVDF nanofiber was about three times higher than that of the pure PVDF nanofiber. Moreover, NaClO solution as leaching solution showed a very limited influence on the surface area of porous PVDF nanofiber. Afterwards, Ag NPs coated PVDF (Ag/PVDF) nanofiber was prepared by physical adsorption of Ag ions and in-situ reduction reaction using sodium borohydride as reductant. The photoactivity of Ag/PVDF nanofiber was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation. Ag/PVDF nanofiber showed a better photoactivity than PVDF-Ag nanofiber prepared by the ex-situ blending method. [ABSTRACT FROM AUTHOR]

The surface modification of poly (vinylidene fluoride) (PVDF) membrane was performed via a two-step polymerization reactions. Poly (acrylic acid) (PAAc) was first grafted onto the membrane surface for the preparation of PVDF-g-PAAc membrane, and then poly (ethylene glycol) 200 (PEG 200) was immobilized on the membrane surface by the esterification reaction for the fabrication of PVDF-g-PEGA membrane. Attenuated total reflectance (ATR) FTIR, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and protein adsorption, water flux, water content and dynamic contact angle were conducted to characterize the structures and performance of the resultant PVDF membranes. The experimental results showed that the adsorption of bovine serum albumin (BSA) on the PVDF-g-PEGA membrane decreased about 80% when the grafting ratio reached to 15 wt%, compared with the pristine PVDF membrane. Moreover, the water contact angle of the membrane dropped to 60.5°, while the membrane pore sizes remained little changed. [ABSTRACT FROM AUTHOR]

PAN/PAMAM blend nanofiber mats with different ratios were prepared by electrospinning process for the first time. Their structures were characterized by SEM, N adsorption/desorption and contact angle. It was found that PAN/PAMAM nanofiber with ratio of 12:3 has the highest surface area. The adsorption of methyl orange on blend nanofiber was investigated. With the ratio of PAMAM increasing in blend nanofiber, the adsorption capacity increased not very much. Overall the PAN/PAMAM nanofiber with ratio of 12:3 has the best property, its maximum adsorption capacity was found to be 120 mg/g although its surface area was only about 9.97 m/g. It still maintained an efficient adsorption capacity even at 5th experiment, indicating an effective adsorbent for dye removal. The adsorption isotherm and adsorption kinetics were further investigated. The Freundlich isotherm provided the best fit for dye adsorption and the dynamical data fitted well with the second-order kinetic model. The possible mechanism was discussed. [ABSTRACT FROM AUTHOR]

Porous stainless steel hollow fiber has been widely used due to its high mechanical strength, excellent thermal conductivity and good sealing properties compared with other porous supports. We successfully prepared porous stainless steel hollow fibers using polyacrylonitrile (PAN) as polymer via dry-wet spinning followed by sintering through temperature programming method. The PAN concentration had an obvious impact on the structure and property of porous stainless steel hollow fiber even if it would be burned off during sintering. The results showed that the morphology could be tuned by adjusting the concentration of PAN. With increasing PAN concentration in casting solution for spinning, the viscosity was increased dramatically, resulting in much compact structures with high pure water flux (higher than 3×10 L·m·h·Pa). A more dense structure could be obtained by adding additive polyvinylpyrrolidone (PVP) as viscosity enhancer. [ABSTRACT FROM AUTHOR]

Hydrophobic polydimethylsiloxane — polytetrafluoroethylene (PDMS-PTFE) flat-sheet membranes for pervaporation (PV) of chloroform from aqueous solution were successfully fabricated by solution casting method. The structures and the performance of the membranes was characterized by X-ray diffraction (XRD), scanning electron microscope combined with energy dispersive X-ray spectroscopy (SEM-EDXS), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and the tests of contact angle and mechanical properties. The adding of PTFE particles (<4 μm) in the PDMS matrix enhanced the crystallinity, hydrophobicity, mechanical strength and thermal stability of the membranes. The examinations showed that the PTFE filled PDMS membranes exhibited striking advantages in flux and separation factor as compared with unfilled PDMS membranes. All the filled PDMS membranes with different PTFE content showed excellent PV properties for the separation of chloroform from water. When the content of the PTFE additive in PDMS composite membrane was 30 wt%, membrane performance was the best at feed temperature 50 °C and permeate-side vacuum 0.101MPa. For the 30% PTFE-PDMS membrane, with the increase of the feed temperature from 30 to 60 °C, the total, water and chloroform fluxes as well as the separation factor increased, the apparent activation energy (ΔEa) of total, chloroform and water were 21.08, 66.65 and 11.49 KJ/mol, respectively, with an increase of chloroform concentration in the feed from 50 to 950 ppm, total, water and chloroform fluxes increased but the separation factor decreased. [ABSTRACT FROM AUTHOR]

The electrospinning of sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) and its blend with polyether sulfone (PES) were investigated and the blend nanofibers were applied as a catalyst in esterification. Attempts to electrospin pure SPPESK resulted in electrospraying rather than electrospinning. However, a blend polymer solution of SPPESK and PES resulted in smooth electrospinning when SPPESK content was lower than 9 wt%. The geometrical properties such as fiber diameter and distribution, surface chemical properties such as inter-molecular interaction and crystalline, mechanical properties were investigated by SEM, FTIR, XRD, etc. The catalytic activities of SPPESK-PES nanofibers were measured by esterification of ethanol with acetic acid. A pseudo-homogeneous model was established to describe the kinetics of esterification with nanofiber as a catalyst. The results showed that the SPPESK-PES blend nanofiber had a high specific surface area (46.7-58.9 m/g), good mechanical properties, good catalytic properties (ethanol conversion up to 80 % when reacted 8 h), and good forward rate constants (10.0 × 10-14.6 × 10 L/(mol∙min)). [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) membranes possessing interconnected bicontinuous structures with superior mechanical properties and improved hydrophilicity were obtained from PVDF/ N, N-dimethylacetamide (DMAc)/Tween 80/water systems via non-solvent induced phase separation (NIPS) with 60 °C and ambient temperature casting solution. Tween 80/HO mixtures were adopted as dopant; water/ethanol (50:50, mass ratio) and ethanol were chosen as coagulants. The effects of process parameters in terms of variations in dopant contents, casting solution temperatures, and coagulant compositions on the phase inversion process and performance of the resultant membranes were investigated. During the demixing process, water diffused from the interior of Tween 80 reverse micelles, resulting in an accelerated precipitation rate and surface segregation process of the polar head groups of Tween 80. The high temperature of the casting solution contributed to enhancing the diffusion rate of liquid-liquid demixing on crystallization. The coagulant compositions changed the liquid-liquid and solid-liquid demixing dynamics of the casting solutions. Ethanol coagulant contributed to crystallization of PVDF/DMAc/Tween 80/water systems prior to liquid-liquid demixing. This delayed demixing process favored the formation of porous foliage-type top structures with fibril or lath bicontinuous fine structure of membrane bulk, increasing flux, and significant hydrophilicity improvement. Casting solutions in water/ethanol coagulant exhibited a less delayed demixing process with both liquid-liquid demixing and crystallization, resulting in formation of fine structure in the form of strings or stripes and limited hydrophilicity improvement. The predominant typical α- and β-type crystallinity in PVDF was attributed to the existence of dopants, the high temperature of the casting solution, and water/ethanol coagulant. This was consistent with the superior mechanical properties of the corresponding PVDF membrane. The newly developed hydrophilic PVDF membranes with superior mechanical properties and low-fouling of bovine serum albumin (BSA) are anticipated to be suitable not only for wastewater treatment, but also for bioseparation. [ABSTRACT FROM AUTHOR]

Blend solutions of polyethersulfone (PES) and perfluorosulfonic acid (PFSA) resin were fabricated into nanofibers via electrospinning. Ethanol (EtOH) and isopropanol (IPA) were employed to investigate the effects of non-solvent (NS) on the structures and properties of the electrospun PES/PFSA nanofibers. Average diameters of the electrospun nanofibers increased with NS content while the water contact angles of the nanofiber membranes decreased. Although all the nanofiber membranes presented strong hydrophobicity initially, the water contact angle would drop to less than 90° within 30 min. Energy dispersive X-ray spectrums (EDS) showed that the nanofibers electrospun from solutions with more NS presented higher sodium content on the surface because more -SONa groups were on the external plane. N adsorption-desorption measurement revealed that increase of NS content in the solvent mixtures resulted in nanofibers with surface area much bigger in experiment than that in calculation, which meant rough structures occurred on the surface of electrospun nanofibers. These rough structures were beneficial to improve the frictional resistance between nanofibers and therefore enhanced the break strength and Young's modulus of the nanofiber membranes. [ABSTRACT FROM AUTHOR]

Polymer-nanoinorganic particles composite membranes present an interesting approach for improving the physical and chemical, as well as separation properties of polymer membranes, because they possess characteristics of both organic and inorganic membranes such as good permeability, selectivity, mechanical strength, thermal stability and so on. The preparations and structures of polymer-nanoinorganic particles composite membranes and their unique properties are reviewed. [ABSTRACT FROM AUTHOR]

Simulated comminution that the coal impact rigid wall using finite element software of explicit formulation based on dynamics model of elastic collision (Hamilton variationnal principle), the critical velocity of the coal impacting comminution was about 10 m/s, and validated the release effect of pressure in the coal impacting comminution, and then extend applied field of the finite element software of explicit formulation LS-DYNA analysing impact comminution of the elastic-plastic material. The simulation result has great guidance and reference value for understanding the impact comminution mechanics of coal and other material and manufacturing comminution equipment. [ABSTRACT FROM AUTHOR]

Using polysulfone (PSF) hollow fiber ultrafiltration membranes as the substrate, sodium alginate (SA) and polyvinyl alcohol (PVA) blend solutions as the coating solution, and maleic anhydride (MAC) as the cross-linked agent, SAPVA/PSF hollow fiber composite membranes were prepared for the dehydration of ethanol-water. The effects of different sodium alginate concentration in the coating solutions and different operating temperatures on pervaporation performance were investigated. The experimental results showed that pervaporation performance of the SA-PVA/PSF composite membranes for ethanol-water solution exhibited a high separation factor although they had a relatively low permeation flux. As SA concentration in SA-PVA coating solution was 66.7% and the operating temperature was 40 °C, SA-PVA/PSF hollow fiber composite membrane (PS4) had a separation factor of 886 and flux of 12.6 g/(m2·h). Besides, SA-PVA/PSF hollow fiber composite membranes (PS3 and PS4) were used for the investigation of the effect of ethanol concentration in the feed solution on pervaporation performance. [ABSTRACT FROM AUTHOR]

The effect of hollow fiber module positions (horizontal and vertical) on separation performance for PVA solution by using polyethersulfone (PES) hollow fiber ultrafiltration (UF) membrane with the molecular weight cut-off (MWCO) 30 000 has been discussed. Experimental results illustrated that the suitable operation conditions for PVA solution were as follows: trans-membrane pressure 2.1 bar, solution temperature 75 °C and feed velocity 0.32 m/s. Under these suitable operation conditions, the permeate flux is from 36.8 L/(m2·h· bar) to 42.9 L/(m2· h· bar) for the horizontal module and from 39.8 L/(m2· h· bar) to 66.6 L/(m2· h· bar) for the vertical module. Besides, the separation performance of PES hollow fiber UF membrane was better by using vertical hollow fiber module than by using horizontal hollow fiber module. When the trans-membrane pressure increased from 1 bar to 2.1 bar, solution temperature from 50 °C to 75 °C, feed solution velocity from 0.16 m/s to 0.32 m/s, the PVA rejection would increase from 95.8% to 99.7%, 95.4% to 98.6%, 95.8% to 99.2% for horizontal module respectively, and from 98.8% to 99.8%, 98.6% to 99.4%, 98.5% to 99.4% for vertical module respectively. Therefore, PVA rejection in PES hollow fiber UF process was more than 98.5% for vertical module, and it is suitable for PVA recovery from wastewater. [ABSTRACT FROM AUTHOR]

In an effort to find the effect of mass transfer, surface tension and drag forces on the velocity distribution, the mathematical model of the velocity profile of a nascent hollow fiber during membrane formation in the air gap region was numerically simulatec by using the Runge-Kutta method (fourth-order method). The effect of mass transfer on velocity distribution based on the complicatec function ( G( C )) was presented and the effects of a complicated function were studied in two cases: in the first case, ( G( C )) was constant; in the second, ( G( C )) was variable. The latter was done by varying with the concentration of solvent in a nascent hollow fiber through the air-gap region. One empirical equation was used to describe this change and the predicted values had a better agreement with the experimental values. To verify the model hypotheses, hollow fiber membranes were spun from 20:80 polybenzimi dazole/polyetherimide dopes with 25.6 wt% solid in N, N-dimethylacetamide (DMAc) using water as the external and internal coagulants. Based on the experimental results of dry-jet wet-spinning process for the fabrication of hollow fiber membranes, it is found tha the model calculated values were in a good agreement with the experimental values. [ABSTRACT FROM AUTHOR]

The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid (PFSA) and poly(vinyl alcohol) (PVA) were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of Δ B and µ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution. [ABSTRACT FROM AUTHOR]

A novel chitosan (CS)-piperazine (PIP) composite nanofiltration (NF) membrane with satisfied characteristics for brackish water and seawater desalination was successfully developed. PIP was mixed with CS during the interfacial polymerization (IP) process to enhance the NF membrane permeate flux. The resultant NF membranes were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM), contact angle. Effects of CS concentration, trimesoyl chloride (TMC) concentration, reaction time and the mixing ratio of CS/PIP on NF membrane performance were investigated thoroughly. When PIP in the aqueous phase monomers reached to 25% (w/w), the PWF (60.6 L·m−2·h−1) was synergistically improved by nearly 2 times without a significant reduction of Na2SO4 rejection (89.1%). Moreover, the NF membranes possessed excellent performance for the desalination of brackish water and seawater, which showed high potential to be applied in the desalination process for water treatment. [ABSTRACT FROM AUTHOR]