Preparation of electrospun silk fibroin/Cellulose Acetate blend nanofibers and their applications to heavy metal ions adsorption

Silk fibroin (SF)/Cellulose Acetate (CA) blend nanofibrous membranes were prepared by electrospinning and their heavy metal absorbabilities were examined in an aqueous solution after ethanol treatment. The electrospun nanofibrous membranes were comprised of randomly oriented ultrafine fibers of 100–600 nm diameters. As a result of field emission electron microscope (FEEM), the anti-felting properties of the blend nanofibrous membranes were markedly improved after treatment with 100 % ethanol when SF was blended with CA. Metal ion adsorption test was performed with Cu²⁺ as a model heavy metal ion in a stock solution. The SF/CA blend nanofiber membranes showed higher affinity for Cu²⁺ in an aqueous solution than pure SF and pure CA nanofiber membranes. Especially, the blend nanofibrous membranes with 20 % content of CA had an exceptional performance for the adsorption of Cu²⁺, and the maximum milligrams per gram of Cu²⁺ adsorbed reached 22.8 mg/g. This indicated that SF and CA had synergetic effect. Furthermore, the parameters affecting the metal ions adsorption, such as running time and initial concentration of Cu²⁺, had been investigated. The results showed that the adsorption of the Cu²⁺ sharply increased during the first 60 min, the amount of metal ions adsorbed increased rapidly as the initial concentration increased and then slope of the increase decreased as the concentration further increased. This study provides the relatively comprehensive data for the SF/CA blend nanofibrous membranes application to the removal of heavy metal ion in wastewater.     

Surface modified ployacrylonitrile nanofibers and application for metal ions chelation

Ployacrylonitrile (PAN) nanofibers were formed by electrospinning. Amidoxime ployacrylonitrile (AOPAN) nanofibers were prepared by reaction with hydroxylamine hydrochloride, which were used as the matrix for metal ions chelation. FTIR spectra of the PAN nanofibers and AOPAN nanofibers were recorded for analysis of the surface chemical structures. The AOPAN conventional fibers were also prepared for comparison, and surface morphologies of the modified PAN conventional fibers and PAN nanofibers were observed by FESEM. Metal ions concentrations were calculated by AAS. The chelated isothermal process and kinetics parameters of the modified PAN nanofibers and PAN conventional fibers were studied in this work. Results indicated that the saturated coordinate capacity of AOPAN nanofibers to Cu²⁺, Cd²⁺ was 3.4482 and 4.5408 mmol/g (dry fiber) respectively, nearly two times higher than that of AOPAN conventional fibers. Besides, the desorption rate of Cu²⁺ and Cd²⁺ from metal chelated AOPAN nanofibers was 87 and 92 % respectively in 1 mol/l nitric acid solution for 60 min. The isothermal processes were found to be in conformity with Langmuir model.     

Electrospun nanofibers of poly(NPEMA-co.-CMPMA): Used as Heavy metal ion remover and water sanitizer

Homo and copolymers of monomers 2-(N-phthalimido) ethylmethacrylate (NPEMA) and 4-Chloro-3-methyl phenyl methacrylate (CMPMA) were prepared in N,N-dimethyl formamide (DMF) solution at 70 °C using 2,2-azobisisobutyronitrile (AIBN) as initiator. The solution of poly(NPEMA-co.-CMPMA) in 20 % DMF was used to fabrication electrospun nanofiber by electrospinning technique. IR data were primarily employed to characterize polymers. The formation of nanofibers was identified by SEM study. The metal ion uptake capacity of copolymers and nanofibers were obtain by batch equilibrium method using different metal ion solution. The antimicrobial activity of the copolymers, Polymer nanocomposites and their nanofibers were tested against different microbial organisms by using quantitative method. The main objective of this investigation was to find whether nanofiber are better remover of metal ions compared to copolymers. It was also aimed to study the efficacy of nanofibers of copolymers and copolymer composite with nano Ag as water sanitizer.     

Manufacturing polymethyl methacrylate nanofibers as a support for enzyme immobilization

Nanofibers have a great potential for enzyme immobilization application due to their large surface area to volume ratio besides their porous structure. In this work, we produce polymethyl methacrylate (PMMA) nanofibers via electrospinning method in dimethylformamide (DMF) as solvent. Thereafter, we employ a chemical method on final PMMA nanofiberous web to covalently immobilize acetylcholinesterase (AChE) enzyme on membrane surface. Morphology and tensile properties of nanofibers are studied as first steps of characterization to make sure of obtaining a properly stable membrane for enzyme carrying application. Thereafter, the stability and activity of immobilized enzymes as two main characteristic parameters are tested and reported for different applications such as biosensor manufacturing.     

Facile fabrication of PVAc-g-PVDF coating on surface modified cotton fabric for applications in oil/water separation and heavy metal ions removal

Selective separation is an effective method for the removal of heavy metal ions and waste oil from wastewater. Polyvinylidene fluoride (PVDF) was functionalized with polyvinyl acetate (PVAc) by in-situ polymerization, and novel PVAc-g-PVDF coating on surface modified cotton fabric were prepared. The contact angle (CA), pure water flux (PWF) and self-cleaning ability of coated cotton fabric were investigated in detail. In addition, the separation performance of coated cotton fabric was reflected by the removal of heavy metal ions in simulated wastewater. The results revealed that the PVAc-g-PVDF-coated cotton fabric was free of waste oil adhesion and was self-cleaning from waste oil in aqueous environment. Meanwhile, this coated cotton fabric can effectively separate oil/water mixtures with a high flux and high oil rejection, and was easily recycled for long-term use. More importantly, the heavy metal ions rejection ratio and adsorption capacity of cotton fabric were also improved with the addition of PVAc-g-PVDF coating. PVAc-g-PVDF-coated cotton fabric exhibited excellent rejection stability and reuse performances after several times fouling and washing tests. It can be expected that the present work will provide insight into a scaled-up fabrication process of PVAc-g-PVDF coating for purifying wastewater.     

Mucoadhesive Chitosan Electrospun Nanofibers Containing Tetracycline and Triamcinolone as a Drug Delivery System

The mucoadhesive Chitosan (CS) nanofibers as a drug delivery system were developed. Chitosan was modified via the immobilization of thiol groups from L-cysteine as a mucoadhesive reagent. The mucoadhesive properties of the chitosan nanofibers were evaluated by tensiometer set and via tensile studies. Drug and mucoadhesive agent loading lead to decrease diameters and increased porous of nanofibers. The release of Tetracycline (Tet) and Triamcinolone (Tri) were increased with increasing immersion time and it became constant at long immersion times. Mucoadhesion studies were done at pH 2–7 and in pH 6 maximum mucoadhesive properties observed. Release studies demonstrated a sustained release of both drug continued up to 48 hours. Microbial studies were performed on the nanofibers. The drug delivery system represented a novel tool for improve the therapeutic efficacy of various drugs that are poorly absorbed from the gastrointestinal tract. Also it is an efficient system for treatment of oral ulceration.     

Marine Biopolymers as Bioactive Functional Ingredients of Electrospun Nanofibrous Scaffolds for Biomedical Applications

Marine biopolymers, abundantly present in seaweeds and marine animals, feature diverse structures and functionalities, and possess a wide range of beneficial biological activities. Characterized by high biocompatibility and biodegradability, as well as unique physicochemical properties, marine biopolymers are attracting a constantly increasing interest for the development of advanced systems for applications in the biomedical field. The development of electrospinning offers an innovative technological platform for the production of nonwoven nanofibrous scaffolds with increased surface area, high encapsulation efficacy, intrinsic interconnectivity, and structural analogy to the natural extracellular matrix. Marine biopolymer-based electrospun nanofibrous scaffolds with multifunctional characteristics and tunable mechanical properties now attract significant attention for biomedical applications, such as tissue engineering, drug delivery, and wound healing. The present review, covering the literature up to the end of 2021, highlights the advancements in the development of marine biopolymer-based electrospun nanofibers for their utilization as cell proliferation scaffolds, bioadhesives, release modifiers, and wound dressings.     

Ternary carboxymethyl chitosan-hemicellulose-nanosized TiO<Subscript>2</Subscript> composite as effective adsorbent for removal of heavy metal contaminants from water

A ternary composite consisting of carboxymethyl chitosan, hemicellulose, and nanosized TiO₂ (CHNT) was prepared by incorporating TiO₂ nanoparticles into the pre-synthesized carboxymethyl chitosan-hemicellulose polysaccharide network. The microstructure and chemical composition of the obtained CHNT was characterized by TEM, SEM, FTIR, and TGA. The adsorption of some toxic heavy metals including Ni(II), Cd(II), Cu(II), Hg(II), Mn(VII), and Cr(VI), onto the as-prepared CHNT composite was investigated. The effects of pH, temperature and contacting time on the adsorption process were studied. Results revealed that the CHNT composite exhibited efficient adsorption capacity of the above metal ions from aqueous solution due to its favorable chelating groups in structure. The adsorption process was best described by the pseudo-second-order kinetic model, while isotherm modeling revealed that the Langmuir equation better described the adsorption on CHNT as compared to Freundlich model. Moreover, the CHNT loaded metal ions can be easily regenerated with EDTA and reused repeatedly up to five cycles. The environmental friendly hybrids were expected to be a promising candidate for future practical application in heavy metal contaminated water treatment.     

Development of natural and ecological wastewater treatment system for decentralized community in Korea

A pilot study of the natural and ecological wastewater treatment system (NEWS) was performed to treat sewage in decentralized small rural communities in Korea. The absorbent-biofilter system (ABS) provided secondary level pretreatment and demonstrated high removal efficiency especially for SS and BOD₅ showing 88.5 and 82.9%, respectively. The influent and effluent concentrations of TN were 42.1 and 26.2 mg L⁻¹, respectively, with the removal efficiency of 37.8%. In case of TP, the removal efficiency was 45.1% with the influent and effluent concentrations of 3.1 and 1.7 mg L⁻¹. The ABS effluent could not meet the effluent standards, and the further treatment was required. The subsequent up- and down-flow constructed wetland (UDCW) provided further polishing of the ABS effluent and demonstrated effective removal of nutrients as well as SS and BOD₅ with over 70% removal rates. Overall performance of the NEWS, which was composed of ABS and UDCW, demonstrated remarkably high removal rates for BOD₅ (>95.7%), SS (>97.5%), TN (>91.8%) and TP (>90.1%) and met all the effluent standards stably independent of temperature and influent loading in the experimental range. The UDCW used light and porous granular substrate (∅ 5–10 mm, specific gravity of 1.2) with large surface area, and clogging problem was not observed during the study period. The system was cost effective and required minimal maintenance and negligible amount of electricity, and problems associated with noise, odor, files, and sludge were not observed. Considering characteristics of decentralized wastewater treatment systems, the NEWS system was found to be a practical alternative and its application is recommended up to 300 m³ day⁻¹. The NEWS system has an economic problem above 300 m³ day⁻¹, because of complicated equipment, higher operation costs, and maintenance specialists. The NEWS system was coast effective and required minimal maintenance and negligible amount of electricity, and problems associated with noise, odor, files, and sludge were not observed.     

Electrospun Poly-lactic Acid/Chitosan Nanofibers Loaded with Paclitaxel for Coating of a Prototype Polymeric Stent

Electrospun composite fibers of poly-lactic acid (PLA), chitosan (Ch) and paclitaxel (PTX) were fabricated for surface covering of a polymeric prototype PLA stent by means of single nozzle electrospinning approach to prepare a low cytotoxicity drug-eluting stent. Different concentrations of the drug (40 %, 60 %, 80 %, 100 % and 120 %) and chitosan (3 %, 5 %, 7 % and 9 %) were incorporated to reach the optimum composite fibers. The electrospun composite fibers were subjected to detailed analyses including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), tensile test, MTT assay, cell culture and in vitro drug release. Results have confirmed a proper physical encapsulation of PTX in the polymeric matrix in which no chemical bonding was detected between the polymers and the drug. Among the fabricated composite fibers, specimens including 40 % and 60 % drug also exhibited an excellent cytotoxicity and controlled drug release. SEM images have proved the effect of paclitaxel in resisting cell adhesion and propagation on the fibers. Findings from this study suggest a novel polymer/drug coating that could be potentially applicable in surface covering of polymeric stents e.g. PLA stents.     

Tobacco stems as a low cost adsorbent for the removal of Pb(II) from wastewater: Equilibrium and kinetic studies

Adsorption of Pb(II) ions from aqueous solution onto tobacco stems has been investigated to evaluate the effects of initial lead ion concentration, adsorbent dosage, contact time, pH and temperature on the removal of Pb(II) systematically. The optimal pH value for Pb(II) adsorption onto the tobacco stems was found to be 5.0. The removal of lead ions for concentrations 10, 30 and 50 mg L⁻¹ using 0.8 g adsorbent at contact time of 120 min and at temperature of 299 K were 94.37%, 92.10% and 90.43%, respectively. Thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were evaluated by applying the Van’t Hoff equation, which describes the dependence of equilibrium constant on temperature. The thermodynamics of Pb(II) adsorption onto the tobacco stems indicated that the adsorption was spontaneous and endothermic. Langmuir and Freundlich isotherms were used to analyze the equilibrium data at different temperatures and the equilibrium data were found to fit Freundlich isotherm equation better than Langmuir isotherm. The adsorption was analyzed using pseudo-second-order kinetic equation.     

The novel use of sodium borohydride as a protective agent for the chemical treatment of vegetable fibers

The vegetable fibers used as reinforcement for polymer matrix composites are usually treated to improve their adhesion with the matrix. The chemical treatment with sodium hydroxide (NaOH) is widely employed, but it may damage the fiber surface structure, reducing its strength. This novel study is related to the use of hydride ions (H^?) as protective agent for vegetable fibers, under alkaline treatment, as a way to promote their use in polymeric composites. Sisal fibers were modified by immersion in a NaOH aqueous solution (2, 5, and 10 % wt/vol) with or without the addition of sodium borohydride (NaBH₄) (1 % wt/vol) under different treatment conditions. The treated fibers were characterized via density and moisture content analyses and also using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The effectiveness of NaBH₄ to protect the sisal fiber was more pronounced in moderate NaOH concentrations (5 %) at room temperature or higher for shorter alkaline treatment times.     

Sprouting as a pre-processing for producing quinoa-enriched bread

The impact of 48 h sprouted quinoa (SQ) was assessed in bread-making. Wheat flour (WF) was replaced with SQ at different levels (i.e., 10:90, 20:80 and 30:70, SQ:WF ratio). Once the optimal replacement level of SQ was identified, the bread-making performance of this ingredient was compared with those of pearled quinoa (PQ), commonly used in bread-making.Starch pasting properties and gluten aggregation behavior were not strongly affected at 20:80 level. Regardless the replacement level, SQ caused an increase in dough water absorption and in softening degree, and a decrease in stability, suggesting weakening of the gluten network. During leavening, SQ improved dough development and gas production, due to increased sugar content (i.e. maltose, sucrose and D-glucose). The best bread-making performance (highest bread specific volume and lowest crumb firmness) was obtained at 20:80 replacement level. Compared to PQ, SQ exhibited the best leavening capacity (high dough development, gas production and gas retention) and bread properties (high specific volume and low crumb firmness), likely due to its higher sugar content. Moreover, 20SQ bread was characterized by a decreased bitterness assessed by electronic-tongue. In conclusion, sprouting might be considered a valid alternative to pearling to improve the characteristics of quinoa enriched bread     

重穗型杂交稻新组合Ⅱ优辐819高产制种技术

Ⅱ优辐819是福建省南平市农科所用Ⅱ-32A与南恢辐819配组育成的重穗型杂交稻新组合.该组合2000～2001年参加福建省水稻新组合区域试验,比对照汕优63增产7.58%,增产达极显著.米质经农业部稻米及制品检测中心测定:米质12项指标中有11项指标达二级以上优质米标准.2003年1月通过福建省农作物品种审定委员会审定.建阳市2003～2004年制种136hm2,平均每666.7m2产量200.8kg.其中制种户林建生制种0.47hm2,生产种子2 133.3kg,平均每666.7m2产量302.6kg.现将其高产制种技术介绍如下:     

Development of a tuned interfacial force field parameter set for the simulation of protein adsorption to silica glass

Adsorption free energies for eight host-guest peptides (TGTG-X-GTGT, with X = N, D, G, K, F, T, W, and V) on two different silica surfaces [quartz (100) and silica glass] were calculated using umbrella sampling and replica exchange molecular dynamics and compared with experimental values determined by atomic force microscopy. Using the CHARMM force field, adsorption free energies were found to be overestimated (i.e., too strongly adsorbing) by about 5-9 kcal/mol compared to the experimental data for both types of silica surfaces. Peptide adsorption behavior for the silica glass surface was then adjusted using a modified version of the CHARMM program, which we call dual force-field CHARMM, which allows separate sets of nonbonded parameters (i.e., partial charge and Lennard-Jones parameters) to be used to represent intra-phase and inter-phase interactions within a given molecular system. Using this program, interfacial force field (IFF) parameters for the peptide-silica glass systems were corrected to obtain adsorption free energies within about 0.5 kcal/mol of their respective experimental values, while IFF tuning for the quartz (100) surface remains for future work. The tuned IFF parameter set for silica glass will subsequently be used for simulations of protein adsorption behavior on silica glass with greater confidence in the balance between relative adsorption affinities of amino acid residues and the aqueous solution for the silica glass surface.     

Effectiveness of carbofuran applied to the soil and as a seed treatment for the control of aphids on wheat in Northwestern Mexico

The effectiveness of carbofuran 300 ST and 350 L applied to the soil and as a seed treatment was evaluated with two wheat cultivars ‘Genaro’ and ‘Sonoyta’ in the Valle del Yaqui, Ciudad Obregon, Sonora in Northwestern Mexico. Both the soil and seed treatment significantly (P < 0·05) reduced greenbug, Schizaphis graminum (Rondani) and corn leaf aphid, Rhopalosiphum maidis (Fitch) populations. Infestations of greenbugs and corn leaf aphids were 97·8% and 98·3% less, respectively, with the soil application of carbofuran 350 L in the Genaro wheat plots and 91% less for both aphids in the Sonoyta wheat plots than on the untreated controls. Greenbug and corn leaf aphid infestations in the seed treatment with carbofuran 300 ST on the Genaro wheat plots were 93·4% and 52·5% less, respectively, and in the Sonoyta wheat plots, infestations of greenbugs and corn leaf aphids were 92% and 78·9% less, respectively, than on the untreated controls. The wheat plots where carbofuran 350 L was applied to the soil had yields 18% and 16% greater for the Genaro and Sonoyta cultivars, respectively, than the untreated controls, while those plots where carbofuran 300 ST was applied as a seed treatment had yields 15% and 12% greater for the Genaro and Sonoyta cultivars, respectively, than the untreated controls.     

Wheat-flour dough extensibility as a discriminator for wheat varieties

The extension testing of wheat-flour dough has become one of the key cereal chemistry links to end product quality assessment, because of its perceived relevance to baking performance, and because of the various correlations that have been inferred and assumed since the extensibility of a dough was first investigated in the late 19th century. As a consequence, from a plant breeding perspective, there is a need to understand and interpret the extensibility of a dough in terms of the molecular dynamics occurring during its extension, not only as it relates to its baking, but also to the HMW/LMW glutenin and gliadin composition of the wheat. The focus of this paper is the direct measurement of extensibility on a micro-extension tester. The theoretical justification is that the resulting extensogram represents an encapsulation of the extensional rheology of the dough. The paper reports on a graphical and statistical analysis of extension tests performed on eight representative flours. They yield validation for the conclusion that the historic assessment of extensibility as Ext_Rupture should be replaced by Ext_Rmax and the difference Ext_Rupture−Ext_Rmax. It is relatively easy to obtain accurate estimates of R_max, Ext_Rmax and Ext_Rupture from electronically recorded extensograms. Among other things, it is established that, in terms of the glutenin classification of flours based on electrophoresis, HPLC or DNA markers, R_max yields a far better differentiation than is achieved with either Ext_Rupture or Ext_Rmax. It follows, as a corollary to such results, that the extensions to the earlier rheological phases in an extensogram are just as, if not more, important in identifying connections between the gluten composition of wheat varieties and the traditional Ext_Rupture and R_max. In particular, it is shown that, like R_max, the scaled difference R_max/(Ext_Rupture−Ext_Rmax) represents an alternative strategy to relate quality to the glutenin composition of wheat varieties, determined by electrophoresis, HPLC and DNA markers.