Preparation and characterization of PHB/PBAT–based biodegradable antibacterial hydrophobic nanofibrous membranes

In this study, polyhydroxybutyrate/poly(butyleneadipate‐co‐terephthalate) (PHB/PBAT) nanofibrous membranes were produced by electrospinning the blends of biodegradable PHB and PBAT. The antibacterial hydrophobic nanofiber membranes were obtained by grafting 1‐allylhydantoin and perfluorooctyl acrylate onto the PHB/PBAT membranes. The prepared nanofibrous membranes were chlorinated with chlorine bleach and characterized by scanning electron microscopy, Fourier transform infrared, and thermogravimetric analysis. The chlorinated nanofibrous membranes exhibited efficient antimicrobial activity against Escherichia coli O157:H7 (ATCC 43895) and Staphylococcus aureus (ATCC 6538) with 6.08 and 5.78 log reduction, respectively. The contact angle of this antibacterial membrane was 123.1° ± 1.9°. The treated membranes showed good stability and durability towards UV‐A light exposure and storage. Therefore, our designed antibacterial hydrophobic nanofibrous membranes may have great potential for use in food packaging.     

Molecular identification of Asian lacquers from different trees using Py‐GC/MS and ToF‐SIMS

Traditional Asian lacquers are natural products with highly valued properties, including beauty, gloss, and durability. Pyrolysis‐gas chromatography/mass spectrometry is the technique of choice to study insoluble polymeric lacquer films. In the present study, pyrolysis‐gas chromatography/mass spectrometry results showed that the pyrolysis products of lacquer films were different for all of the studied trees, with urushiol derivatives detected in Toxicodendron vernicifluum from China, Japan, and Korea; laccol in Toxicodendron succedaneum from Vietnam; and thitsiol in Gluta usitata from Myanmar. Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) was also used to characterize the Asian lacquers, avoiding the time‐consuming and destructive processes of other techniques. The ToF‐SIMS spectra provided structural characterization of a series of urushiol, laccol, and thitsiol derivatives for T vernicifluum from China, Japan, and Korea; T succedaneum from Vietnam; and G usitata from Myanmar, respectively. To differentiate the ToF‐SIMS results for the different Asian lacquer films, principal component analysis was used because it can extract differences in the spectra and indicate what peaks are responsible for these differences. The results indicate that lacquer films from different lacquer trees can be very different. Therefore, ToF‐SIMS with principal component analysis is suitable for the characterization and differentiation of Asian lacquer films in cultural heritage applications.     

Studies of Japanese lacquer: Urushiol dimerization by the coupling reaction between urushiol quinone and a triolefinic component of urushiol

Previously, the formation of urushiol quinone from urushiol was demonstrated in the laccase-catalyzed oxidation process of the sap of the Japanese lacquer tree (Rhus vernicifera D.C.) or of lacquer formed from it. This paper presents the results of the investigation on the participation of urushiol quinone in the oxidative polymerization and crosslinking of the sap or the lacquer. The polymeric urushiol was obtained by the fractionation of the mildly oxidized sap (Japanese lacquer), and a specific dimeric urushiol was isolated from it by thin-layer chromatography (TLC). Structural analysis of the dimer illustrated that it has a conjugated triene structure and may be formed by a coupling reaction between urushiol quinone and a triolefinic component of urushiol. Further support for this was given by the spectroscopic study of the reaction between 4-tert-butyl-o-quinone and the triolefinic component of dimethylurushiol, and by the isolation and identification of the coupling product between them.     

Lipase bound cellulose nanofibrous membrane via Cibacron Blue F3GA affinity ligand

Cellulose (Cell) nanofibrous membranes were prepared by nucleophilic reaction of the cellulose hydroxyl with the triazinyl chloride of Cibacron Blue F3GA (CB) ligand and studied as affinity membranes for lipase enzyme. Cell nanofibrous membranes containing fibers with 200 nm average diameters were prepared by electrospinning of cellulose acetate (CA), followed by alkaline hydrolysis. The CB capacity of the Cell nanofibrous membranes was optimized by lengthening the nucleophilic reaction time and increasing CB concentration and ionic strength. The equilibrium adsorption isotherms of CB on the Cell nanofibrous membranes followed a typical Langmuir monolayer adsorption behavior. At 242 mg CB/g of Cell, the maximum lipase adsorption capacity (q_m) and the dissociation constant (K_d) values were 41.02 mg/g and 0.25 mg/mL, respectively. Optimal lipase adsorption capacity was obtained at pH 4.0, its isoelectric point, with added NaCl on Cell membranes 86 mg CB capacity per g of Cell. A facile lipase loading capacity of 16.21 mg/g of CB–Cell was achieved under moderated conditions and could be optimized to reach at least 150 mg/g. The CB–Cell bound lipase had similar catalytic rate and retained 86.2% activity as in its free form. These findings clearly show that the CB bound Cell nanofibrous membrane is a highly efficient ultra-high specific porous support for lipase enzyme and is potentially versatile for immobilizing other enzymes and as affinity membrane for proteins.     

漆树液精油化学成分的研究

用GPC、GC-MS-DS法对中国漆树液中漆酚与虫漆酚精油化学成分进行了研究。其主要成分为3-C₁₅和C₁₇烃基取代的邻苯二酚化合物,其中三烯漆酚和单烯虫漆酚含量最高。其它成分为4-C₁₅,C₁₇烃基取代的邻苯二酚及3-C₁₅和C₁₇烃基取代的单酚化合物。气相色谱分离鉴定组分占精油含量的98%以上。原始漆树液中内含7%～9%漆酚聚合物。     

Improved microfiltration and bacteria removal performance of polyethersulfone membranes prepared by modified vapor‐induced phase separation

Polyethersulfone (PES) microfiltration membranes were fabricated by a combined vapor‐induced phase separation and wet phase separation method. The effect of different non‐solvent additives in casting solution, ie, acetone, diethylene glycol, and triethylene glycol (TEG) was investigated on the membrane morphology and performance. Scanning electron microscopy images showed that the membrane containing TEG additive had a skinless symmetric structure with well interconnected pores. The permeability of the PES/PVP/TEG membranes increased by decreasing PES and TEG and increasing PVP concentration. Bacteria removal performance of the prepared membranes was investigated by the filtration of E. coli suspension. The membrane made from casting solution containing 15 wt.% PES, 16 wt.% PVP, and 20wt.% TEG showed a pure water flux of ~ 5370 L/m² h at low transmembrane pressure of 10 psi and 100% bacteria removal efficiency. The results of in vitro cytotoxicity test and cell viability assay showed non‐toxic nature of the prepared membranes.     

Development and Characterization of Laccol Lacquer Blended with Urushiol Lacquer

A lacquer blending urushiol and laccol was investigated. The blended lacquer with 30wt.% urushiol and 100wt.% laccol has a good drying property and film hardness. 2-D-NMR and FD-MS measurements of the lacquer dimer showed that a transfer of radicals between urushiol and laccol occurred during the enzymatic polymerization, and 4-4′ biphenyl, 4-6′ (4′-6), and 6-6 (6-6′) dibenzofuran structures were obtained.     

Electrospinning Preparation of β-Cyclodextrin/Glutaraldehyde Crosslinked PVP Nanofibrous Membranes to Adsorb Dye in Aqueous Solution

The insoluble β-cyclodextrin/glutaraldehyde crosslinked polyvinylpyrrolidone nanofibrous membranes were prepared by electrospinning technique. The membranes were extensively characterized by various techniques including attenuated total reflectance Fourier transform infrared spectroscopy（ATR-FTIR）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and UV-visible absorption to correlate membrane characteristics with their performance. The adsorption ability of the nanofibrous membranes was tested by performing extraction of Methyl orange（MO） dye in water. It was observed that β-cyclodextrin incorporated in polyvinylpyrrolidone provided the characteristics of high adsorption capacity of polyvinylpyrrolidone. Results of sorption experiments show that the nanofibrous membranes exhibited an adsorption rate of more than 95% for MO and the MO absorbent was 39.82 mg to per gram of fl-cyclodextrin glutaraldehyde（β-CDXFM） crosslinked PVP under the optimized experimental conditions.     

Green,ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal through incorporation of chitosan by various electrospinning ways

Rapid global industrialization has worsened the heavy metal contamination of aquatic ecosystems globally. In this study, green, ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal were obtained by incorporating chitosan (CS) and using conventional and core–shell electrospinning ways. The relationship between the parameters of the electrospinning solution, the micro-morphology and porosity, the chemically active sites, the thermal stability, and the adsorption performance of the biocomposite nanofibrous membranes were analyzed. The adsorption effects of the copper ions, including the initial concentration, solution pH, and interaction time, were investigated. The results show that the average diameters of the conventional and core–shell ultrafine nanofibers with 50% and 30% CS loading are 56.22 nm and 37.28 nm, respectively. The core–shell cellulose acetate (CA)/CS biocomposite nanofibrous membranes showed the weaker thermal stability with a 48.2 °C lower maximum thermal decomposition temperature and induced the surface aggregation of more copper ions compared to the conventional one. A more uniform distribution of the chemical adsorption sites is obtained by conventional single-nozzle electrospinning than by core–shell electrospinning, which effectively promotes the adsorption performance of copper ions and decreases the surface shrinkage of the nanofibrous membranes during adsorption. The 30% CS conventional nanofibrous membranes at an aqueous solution pH of 5 showed the optimum adsorption capacity of copper ions (86.4 mg/g). The smart combination of renewable biomass with effective chemical adsorption sites, electrospinning technology that produces an interwoven porous structure, and an adsorption method with low cost and facile operation shows a promising prospect for water treatment.

     

Fabrication and optimization of proton conductive polybenzimidazole electrospun nanofiber membranes

Phosphoric acid (PA)–doped polybenzimidazole (PBI) proton exchange membranes have received attention because of their good mechanical properties, moderate gas permeability, and superior proton conductivity under high temperature operation. Among PBI‐based film membranes, nanofibrous membranes withstand to higher strain because of strongly oriented polymer chains while exhibiting higher specific surface area with increased number of proton‐conducting sites. In this study, PBI electrospun nanofibers were produced and doped with PA to operate as high temperature proton exchange membrane, while changes in proton conductivity and morphologies were monitored. Proton conductive PBI nanofiber membranes by using the process parameters of 15 kV and 100 μL/h at 15 wt% PBI/dimethylacetamide polymer concentration were prepared by varying PA doping time as 24, 48, 72, and 96 hours. The morphological changes associated with PA doping addressed that acid doping significantly caused swelling and 2‐fold increase in mean fiber diameter. Tensile strength of the membranes is found to be increased by doping level, whereas the strain at break (15%) decreased because of the brittle nature of H‐bond network. 72 hour doped PBI membranes demonstrated highest proton conductivity whereas the decrease on conductivity for 96‐hour doped PBI membranes, which could be attributed to the morphological changes due to H‐bond network and acid leaking, was noted. Overall, the results suggested that of 72‐hour doped PBI membranes with proton conductivity of 123 mS/cm could be a potential candidate for proton exchange membrane fuel cell.     

漆酚铁聚合物的制备及性能研究

以生漆和三氯化铁反应制备漆酚铁聚合物,用红外光谱、涂膜鲜映性仪和光泽度仪等对聚合物结构和漆膜性能进行表征.结果表明,反应温度65℃,反应时间3h,漆酚和三氯化铁物质的量比为8∶1,所生成的漆酚铁聚合物性能较好.     

Investigation of Asian lacquer films using ToF‐SIMS and complementary analytical techniques

Lacquer has been used in Asian countries for thousands of years as a natural coating material owing to its durable, adhesive, decorative, and protective properties. Protection and restoration of lacquer‐coated cultural remains has become an important subject, and identification of the lacquer types in old lacquer‐wares has also become very important for conservation and restoration research. This paper provides identification of several molecular species of vegetal‐source Asian lacquers with the aim of providing a methodology for application in the field of cultural heritage. Several chemical markers of the vegetal species in Asian lacquers were identified using a methodology consistent with the sampling restrictions required for cultural‐heritage objects. Surface analytical methods such as time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), X‐ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize Korean, Chinese, and Vietnamese lacquers; avoiding time‐consuming and destructive extraction processes. These ToF‐SIMS results provided the structural characterization of a series of catechol derivatives. The ToF‐SIMS spectra of Rhus vernicifera from Korea and China, and Rhus succedanea from Vietnam indicated a series of urushiol and laccol repeat units, respectively, in the mass range of m/z 0–1800. Because of its sensitivity, specificity, and speed of analysis, the ToF‐SIMS technique can be used to investigate cultural lacquer‐coated treasures as well as to discriminate among different Asian lacquer coatings or binding mediums for the conservation or restoration of lacquer‐ware. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigation and analysis of Ryukyu lacquerwares decorated with wisteria vine by pyrolysis GC/MS and 87Sr/86Sr isotope ratio

Three lacquer trays decorated with wisteria vine (rattan) produced in the 18–19th century in Ryukyu Kingdom were analyzed by cross‐section, pyrolysis gas chromatography/mass spectrometry, strontium isotope ratios (⁸⁷Sr/⁸⁶Sr), radioactive carbon‐14 dating, and field emission scanning electron microscope with energy dispersive X‐ray spectrometry. One sample had only one red lacquer layer, and the other two samples had two layers with top red lacquer and a bottom layer of natural lacquer, respectively. The ⁸⁷Sr/⁸⁶Sr isotope ratios of three samples were 0.7091–0.7107, consistent with that of the Japanese mainland (<0.7110). The wood species of lacquer objects were identified as Japanese white pine, Japanese cedar, and Cunninghamia lanceolata, which grow in the Japanese islands. The carbon‐14 dating results showed that the lacquer films were about 1719–1785. In pyrolysis gas chromatography/mass spectrometry, 3‐heptylphenol (C7) and 3‐pentadecylphenol (C15) were detected in the mass chromatograms at m/z = 108 and palmitic acid and stearic acid were detected in the mass chromatograms at m/z = 60, implying that the coating material was sap collected from Toxicodendron vernicifluum lacquer tree and included a drying oil. Energy dispersive X‐ray spectrometry revealed that mainly mercury sulfide was used as red pigment in these three Ryukyu lacquerwares. Copyright © 2017 John Wiley & Sons, Ltd.     

Analysis and Characterization of Korean Lacquer

Three kinds of Korean lacquer saps were analyzed including chemical composition, enzymatic activity, molecular weight distribution, unsaturated degree of side chain, and drying property. The results were compared with Chinese and Japanese lacquer saps all collected in the same month (August 2012 and 2013) to investigate similarities and differences. Compared with Chinese and Japanese saps, the Korean lacquer sap contains the most lipids (84.9%) and urushiol triene (56.1%) components and the second highest enzyme activity after Chinese lacquer sap. In the drying and film hardness test, Korean and Chinese film reached a stronger hardness sooner than Japanese lacquer film; in 21 days the former reached 2H and the latter only H. The results of IR, NMR, and GC-MS analysis showed slight differences due to different growing conditions.     

Design of super-tough and antibacterial PPR/nano-ZnO composites based on the excellent dispersion of ZnO particles

Herein, polyvinyl pyrrolidone (PVP) dispersants are used to disperse and isolate zinc oxide (ZnO) particles. A high-pressure spray device is used to dry the dispersed nano-fillers quickly to achieve the structure of PVP chains wrapping and isolating ZnO particles. Scanning electron microscopy shows that most of the size of the agglomerated ZnO nanoparticles in polypropylene random (PPR, obtained by random copolymerization of propylene and ethylene) is maintained below 100 nm, and only a small amount of large agglomerates with a particle size less than 400 nm. An excellent dispersion of nano-ZnO fillers prepared by this method can greatly improve the toughness of PPR and endow it with good antibacterial properties. When the content of the ZnO nanoparticles is 3 wt%, the notched impact strength of PVZ3 increases to 48.85 kJ m⁻² (unbroken), which is 3.6 times than that of pure PPR. In addition, 3 phr ZnO nanoparticles give PPR excellent antibacterial properties, with an antibacterial rate of 99.9% (Escherichia coli and Staphylococcus aureus). The value of antibacterial activity (E. coli) of PVZ3 reached more than 6.0, which is nearly three times that of PZ.     

High flux nanofiltration membranes based on interfacially polymerized polyamide barrier layer on polyacrylonitrile nanofibrous scaffolds

Electrospun polyacrylonitrile (PAN) nanofibrous scaffold was used as a mid-layer support in a new kind of high flux thin film nanofibrous composite (TFNC) membranes for nanofiltration (NF) applications. The top barrier layer was produced by interfacial polymerization of polyamides containing different ratios of piperazine and bipiperidine. The filtration performance (i.e., permeate flux and rejection) of TFNC membranes based on electrospun PAN nanofibrous scaffold was compared with those of conventional thin film composite (TFC) membranes consisting of (1) a commercial PAN ultrafiltration (UF) support with the same barrier layer coating and (2) two kinds of commercial NF membranes (i.e., NF90 and NF270 from Dow Filmtec). The nanofiltration test was carried out by using a divalent salt solution (MgSO₄, 2000 ppm) and a cross-flow filtration cell. The results indicated that TFNC membranes exhibited over 2.4 times more permeate flux than TFC membranes with the same chemical compositions, while maintaining the same rejection rate (ca. 98%). In addition, the permeate flux of hand-cast TFNC membranes was about 38% higher than commercial NF270 membrane with the similar rejection rate.     

Polyetherimide/polyvinylpyrrolidone vapor permeation membranes. Physical and chemical characterization

Integrally skinned capillary tube membranes were prepared by the wet-phase inversion method. A series of polyetherimide (PEI, Ultem 1000) membranes were prepared with varying amounts of polyvinylpyrrolidone (PVP) in the casting solution. The surfaces of the membranes were analyzed by electron spectroscopy for chemical analysis (ESCA). It was found that the molecular structure of PEI, both with and without PVP, changes considerably during membrane preparation. The ESCA results indicated that the amount of PEI nitrogen remaining fully imidized at the surface varied in the range 63–86%. The PVP/PEI mass ratio at the membrane surface was found to increase linearly from 0 to 0.10 as the ratio was increased from 0 to 0.43 in the casting solution. The PVP/PEI mass ratio in the membrane bulk was determined by thermogravimetric analysis (TGA) to reach a maximum of 0.067. Vapor permeation experiments were done with a water/n-propanol mixture. The addition of PVP increased the membrane selectivity (α=P_A/P_B, A=water, B=1-propanol) from 76 to 810, while the permeance for water remained relatively constant at 1.3×10⁻⁶ mol/m² s Pa.     

Improvement in performance of a direct ethanol fuel cell: Effect of sulfuric acid and Ni-mesh

A direct ethanol fuel cell (DEFC) is developed with low catalyst loading at anode and cathode compared to that reported in the literature. Pt/Ru (40%:20% by wt.)/C and Pt-black were used as anode and cathode catalyst with loadings in the range of 0.5–1.2 mg/cm². The temperatures of anode and cathode were varied from 34 °C to 110 °C, and the pressure was maintained at 1 bar. Although low catalyst loading was used, the cell performance is enhanced by 40–50% with the use of low concentration of sulfuric acid in ethanol and Ni-mesh as current collector at the anode. The power density 15 mW/cm² at 32 mA/cm² of current density is obtained from the single cell with 0.5 mg/cm² loading of Pt–Ru/C at anode (90 °C) and Pt-black at cathode (110 °C). The performance of DEFC increases with the increase in ethanol and sulfuric acid concentrations, electrocatalyst loadings up to 1 mg cm⁻² at anode and cathode. However, the performance of DEFC decreases with further increase in electrocatalyst loading.     

Enhanced antifouling and anticoagulant properties of grafted biomolecule polyethersulfone membranes

Polyethersulfone (PES) has been widely used in membrane technology and used to purify water in water treatments application or as a dialyzer to purify blood in hemodialysis. In this work, PES was chemically modified by separately grafting two biomolecules, 4‐aminobenzenesulfonamide (ABS), and 4‐amino‐N‐(5‐methylisoxazol‐3‐yl)benzenesulfonamide (AMBS), on PES backbone, and these modified membranes were blended to unmodified PES, in 1:1 ratio, in order to obtain PES‐b‐PES‐ABS and PES‐b‐PES‐AMBS membranes. The first aim of this study is to measure the anticoagulant properties of the modified membrane by measuring the activated partial thromboplastin time (APTT) and prothrombin time (PT). The second aim of the study is to evaluate the antifouling properties of the modified PES membranes by examining its antimicrobial activity against two Gram‐negative bacteria, which are Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli); two Gram‐positive bacteria, which are Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus); and a fungus, which is Candida albicans (C. albicans). The results showed that grafting of ABS and AMBS improved overall the hydrophilicity properties of the modified PES membranes. PES‐b‐PES‐ABS membranes showed better anticoagulant properties with 13 seconds for PT and 38 seconds for APPT, in comparison with the control sample (pure plasma), which showed 12 seconds for PT and 30 seconds for APPT. For antimicrobial tests, both PES‐b‐PES‐ABS and PES‐b‐PES‐AMBS membranes did not show any antibacterial activity, but when zinc oxide (ZnO) nanoparticles were added to the modified PES membranes in concentrations between 3% to 5% w/w, PES‐b‐PES‐ABS‐ZnO (M‐4 and M‐5), and PES‐b‐PES‐AMBS‐ZnO (M‐8 and M‐9) nanocomposite membranes showed antibacterial activity against P. aeruginosa and S. aureus.     

Characterization of lipid components of Melanorrhoea usitata lacquer sap

The lipid component of Melanorrhoea usitata lacquer sap isolated by acetone was analyzed and compared to synthesized ω-phenylalkylcatechols and ω-phenylalkylphenols. In addition, laccol and urushiol analogues synthesized in our laboratory were used as standard materials to analyze the lipid component of the Myanmar lacquer sap. The GC and GC/MS measurements confirmed the results of Kumanotani and Du that neither ω-phenylalkylcatechol nor ω-phenylalkylphenol exist in the lacquer saps from Rhus vernicifera and R. succedanea.