2018, Vol. 3, No. 1
Display Method:
2018, 3(1): 3-8.
doi: 10.21967/jbb.v3i1.164
Abstract:
Zwitterionic materials are now widely used to fabricate various functionalized surfaces for biomedical applications due to their excellent non-fouling properties. However, a newly-discovered zwitterionic material, choline phosphate (CP), was reported to be cell-adhesive, which makes it different from traditional non-fouling zwitterionic materials such as sulfobetaine, carboxybetaine and phosphorylcholine (PC). To further investigate the properties of CP, a comparative study was conducted and the widely-reported zwitterionic PC was employed as a control which has the same chemical component but opposite orientation of charged groups with CP. For this purpose, CP and PC-functionalized surfaces were prepared by surface-initiated atom transfer radical polymerization (Si-ATRP), and their non-fouling properties were probed by protein adsorption and eukaryotic cell adhesion measurement. Results showed that CP-functionalized surfaces exhibited almost equivalent amounts of adsorbed proteins to that of PC, but they were more beneficial to cells initial adhesion and further spreading in serum-free medium, indicating that CP had a promising prospect of application in tissue engineering.
Zwitterionic materials are now widely used to fabricate various functionalized surfaces for biomedical applications due to their excellent non-fouling properties. However, a newly-discovered zwitterionic material, choline phosphate (CP), was reported to be cell-adhesive, which makes it different from traditional non-fouling zwitterionic materials such as sulfobetaine, carboxybetaine and phosphorylcholine (PC). To further investigate the properties of CP, a comparative study was conducted and the widely-reported zwitterionic PC was employed as a control which has the same chemical component but opposite orientation of charged groups with CP. For this purpose, CP and PC-functionalized surfaces were prepared by surface-initiated atom transfer radical polymerization (Si-ATRP), and their non-fouling properties were probed by protein adsorption and eukaryotic cell adhesion measurement. Results showed that CP-functionalized surfaces exhibited almost equivalent amounts of adsorbed proteins to that of PC, but they were more beneficial to cells initial adhesion and further spreading in serum-free medium, indicating that CP had a promising prospect of application in tissue engineering.
2018, 3(1): 9-13.
doi: 10.21967/jbb.v3i1.108
Abstract:
Poplar wood chips were extracted in an acetic acid/sodium acetate (SA/AA) buffer solution at 180 ℃ for 60 minutes, with a solid-to-liquid ratio of 1:6, to investigate the effect of pH on the extraction performance in terms of chemical compositions of the extract. The pH was controlled by varying the concentrations of sodium acetate and acetic acid in the buffer system. Results showed that the SA/AA system could promote the dissolution of hemicellulose, obtaining more oligosaccharides and monosaccharides, and could also inhibit the excessive decomposition of monosaccharides. When extracting poplar wood chips in a SA/AA system of pH=3.7, the yield of oligosaccharides was the highest, while the contents of furfural and hydroxymethyl furfural decreased by 25% and 30%, respectively, compared to conventional water extraction systems. Moreover, the amount of lignin extracted in the S/AA process was also higher than that in a conventional hot water extraction process.
Poplar wood chips were extracted in an acetic acid/sodium acetate (SA/AA) buffer solution at 180 ℃ for 60 minutes, with a solid-to-liquid ratio of 1:6, to investigate the effect of pH on the extraction performance in terms of chemical compositions of the extract. The pH was controlled by varying the concentrations of sodium acetate and acetic acid in the buffer system. Results showed that the SA/AA system could promote the dissolution of hemicellulose, obtaining more oligosaccharides and monosaccharides, and could also inhibit the excessive decomposition of monosaccharides. When extracting poplar wood chips in a SA/AA system of pH=3.7, the yield of oligosaccharides was the highest, while the contents of furfural and hydroxymethyl furfural decreased by 25% and 30%, respectively, compared to conventional water extraction systems. Moreover, the amount of lignin extracted in the S/AA process was also higher than that in a conventional hot water extraction process.
2018, 3(1): 14-17.
doi: 10.21967/jbb.v3i1.123
Abstract:
Carbohydrate degradation is a serious problem in alkali-oxygen pulping due to the inherently oxidative reaction conditions. Hemicellulose and short-chain cellulose are particularly susceptible to degradation by oxidation, and thus have a great effect on the pulping yield, as well as the viscosity and crystallinity of resultant pulp in alkali-oxygen pulping. Removal of the low molecular weight substances by wet storage prior to alkali-oxygen pulping may increase the pulping yield and improve pulp properties, in addition to savings in pulping chemicals and energy. This paper investigated alkali-oxygen pulping of bagasse pretreated by wet storage, and results show that wet storage of bagasse had a significant effect on its alkali-oxygen pulping, in terms of pulping yield, pulp viscosity and crystallinity. The pH and time were found to be the two most important factors in wet storage on bagasse. Pulp crystallinity increased from 31.78% to 42.06% when the wet storage of bagasse was performed at pH 6.0 for 16 days. In addition, the screened pulp yield increased from 58 to 60%, and pulp viscosity increased from 650 to 700 mL/g. The improved pulping performance was attributed to increased pore volumes in bagasse due to dissolution of low molecular weight lignin and carbohydrates during wet storage, which in turn improved the selectivity of delignification in the alkali-oxygen pulping process.
Carbohydrate degradation is a serious problem in alkali-oxygen pulping due to the inherently oxidative reaction conditions. Hemicellulose and short-chain cellulose are particularly susceptible to degradation by oxidation, and thus have a great effect on the pulping yield, as well as the viscosity and crystallinity of resultant pulp in alkali-oxygen pulping. Removal of the low molecular weight substances by wet storage prior to alkali-oxygen pulping may increase the pulping yield and improve pulp properties, in addition to savings in pulping chemicals and energy. This paper investigated alkali-oxygen pulping of bagasse pretreated by wet storage, and results show that wet storage of bagasse had a significant effect on its alkali-oxygen pulping, in terms of pulping yield, pulp viscosity and crystallinity. The pH and time were found to be the two most important factors in wet storage on bagasse. Pulp crystallinity increased from 31.78% to 42.06% when the wet storage of bagasse was performed at pH 6.0 for 16 days. In addition, the screened pulp yield increased from 58 to 60%, and pulp viscosity increased from 650 to 700 mL/g. The improved pulping performance was attributed to increased pore volumes in bagasse due to dissolution of low molecular weight lignin and carbohydrates during wet storage, which in turn improved the selectivity of delignification in the alkali-oxygen pulping process.
2018, 3(1): 18-24.
doi: 10.21967/jbb.v3i1.161
Abstract:
Depolymerization of lignin is an important step to obtain lignin monomer for the synthesis of functional bio-polymers. In this paper, catalytic degradation/depolymerization of an alkali lignin was investigated in a supercritical ethanol system. The process conditions were optimized in terms of lignin monomer yield, and the liquid products and solid residue were characterized. Results show that the conversion rate of the alkali lignin was improved in both the Ni7Au3 catalyzed and Nickel-catalyzed systems with supercritical ethanol as the solvent. The maximum lignin conversion rate was 69.57% and 68% respectively for the Ni7Au3 and Nickel-based catalysis systems. Gas chromatography/mass spectroscopy (GC/MS) analysis indicated that the catalytic depolymerization products of alkali lignin were mainly monomeric phenolic compounds such as 2-methoxyphenol. The highest yield of 2-methoxyphenol (84.72%) was achieved with Ni7Au3 as the catalyst.
Depolymerization of lignin is an important step to obtain lignin monomer for the synthesis of functional bio-polymers. In this paper, catalytic degradation/depolymerization of an alkali lignin was investigated in a supercritical ethanol system. The process conditions were optimized in terms of lignin monomer yield, and the liquid products and solid residue were characterized. Results show that the conversion rate of the alkali lignin was improved in both the Ni7Au3 catalyzed and Nickel-catalyzed systems with supercritical ethanol as the solvent. The maximum lignin conversion rate was 69.57% and 68% respectively for the Ni7Au3 and Nickel-based catalysis systems. Gas chromatography/mass spectroscopy (GC/MS) analysis indicated that the catalytic depolymerization products of alkali lignin were mainly monomeric phenolic compounds such as 2-methoxyphenol. The highest yield of 2-methoxyphenol (84.72%) was achieved with Ni7Au3 as the catalyst.
2018, 3(1): 25-29.
doi: 10.21967/jbb.v3i1.89
Abstract:
Roll top formers are widely used for Fourdrinier paper machines, typically with a speed of less than 1200 m/min. In a roll top former, wet fiber web is dewatered by the extrusion force of two wires and the centrifugal force of the roll. The present work focuses on the dewatering and forming mechanisms of roll top formers and the governing factors relevant to the structural characteristics of the formers. This study would provide usefull information for the design and applications of roll top formers in paper mills.
Roll top formers are widely used for Fourdrinier paper machines, typically with a speed of less than 1200 m/min. In a roll top former, wet fiber web is dewatered by the extrusion force of two wires and the centrifugal force of the roll. The present work focuses on the dewatering and forming mechanisms of roll top formers and the governing factors relevant to the structural characteristics of the formers. This study would provide usefull information for the design and applications of roll top formers in paper mills.
2018, 3(1): 30-34.
doi: 10.21967/jbb.v3i1.142
Abstract:
Au nanoparticles (AuNPs) were prepared by reducing HAuCl4 with NaBH4, and then adsorbed uniformly on the surface of carboxylated nanocrystalline cellulose (CNCC). The obtained AuNPs/CNCC particles were doped into a conductive polymer of poly(3,4-ethylenedioxythiophene) (PEDOT) to yield a highly conductive nanocomposite, which was deposited onto a glassy carbon electrode (GCE) by an electrochemical method. The PEDOT/AuNPs/CNCC nanocomposite showed low electrochemical impedance and good electrocatalytic activity toward ascorbic acid. Based on this novel nanocomposite material, an amperometric sensor was developed for the detection of ascorbic acid with a detection limit as low as 0.29 μM. When operated at -0.15 V, the sensor detected ascorbic acid in the range of 0.88 μM to 15000 µM.
Au nanoparticles (AuNPs) were prepared by reducing HAuCl4 with NaBH4, and then adsorbed uniformly on the surface of carboxylated nanocrystalline cellulose (CNCC). The obtained AuNPs/CNCC particles were doped into a conductive polymer of poly(3,4-ethylenedioxythiophene) (PEDOT) to yield a highly conductive nanocomposite, which was deposited onto a glassy carbon electrode (GCE) by an electrochemical method. The PEDOT/AuNPs/CNCC nanocomposite showed low electrochemical impedance and good electrocatalytic activity toward ascorbic acid. Based on this novel nanocomposite material, an amperometric sensor was developed for the detection of ascorbic acid with a detection limit as low as 0.29 μM. When operated at -0.15 V, the sensor detected ascorbic acid in the range of 0.88 μM to 15000 µM.
2018, 3(1): 35-39.
doi: 10.21967/jbb.v3i1.110
Abstract:
Maintaining a constant chemical concentration (Iso-concentration, IC) has been found to be an effective method to improve peroxide bleaching efficiency for chemi-thermomechanical pulp (CTMP). In this study, the mechanism of IC bleaching was investigated. The concentrations of H2O2 and total alkali in IC bleaching were monitored and compared with those in conventional bleaching processes. Control experiments without pulp were carried out to explore the effects of bleaching additives on H2O2 decomposition. The results showed that the concentrations of H2O2 and the total alkali at the early and later stages of IC bleaching were relatively low and high, respectively; thus, undesired decomposition of H2O2 was inhibited, and brightness was improved. Moreover, the stabilizer played an important role in inhibiting the undesired H2O2 decomposition. This may explain why high bleaching efficiency was achieved in IC bleaching. These findings would provide valuable insight for the production of high-brightness bleached chemi-thermomechanical pulp (BCTMP).
Maintaining a constant chemical concentration (Iso-concentration, IC) has been found to be an effective method to improve peroxide bleaching efficiency for chemi-thermomechanical pulp (CTMP). In this study, the mechanism of IC bleaching was investigated. The concentrations of H2O2 and total alkali in IC bleaching were monitored and compared with those in conventional bleaching processes. Control experiments without pulp were carried out to explore the effects of bleaching additives on H2O2 decomposition. The results showed that the concentrations of H2O2 and the total alkali at the early and later stages of IC bleaching were relatively low and high, respectively; thus, undesired decomposition of H2O2 was inhibited, and brightness was improved. Moreover, the stabilizer played an important role in inhibiting the undesired H2O2 decomposition. This may explain why high bleaching efficiency was achieved in IC bleaching. These findings would provide valuable insight for the production of high-brightness bleached chemi-thermomechanical pulp (BCTMP).
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