Graft copolymerization of acrylamide onto rayon by chemical and radiation methods

The inherent properties of rayon fibre have been changed with additional properties through graft copolymerization of acrylamide, AAm, by chemical method using ceric ammonium nitrate/nitric acid, (CAN/HNO₃), as a redox initiator and γ-radiation induced mutual method. Reaction conditions such as monomer and initiator concentration, liquor ratio, temperature and time of reaction, amount of radiation dose have been optimized with respect to percentage of grafting. Maximum percentage of grafting (Pg), (40 %) using CAN/HNO₃ was obtained at [CAN]=31.92×10^?3 moles/l, [HNO₃]=79.36×10^?2 moles/l, [AAm]=14.07×10² moles/l in 20 ml of H₂O at 45 °C within 120 min while in case of radiation induced method, maximum Pg (30 %) was obtained at higher monomer concentration (28.14×10^?2 moles/l) and time (180 min) in 10 ml of H₂O at room temperature with total dose exposure of 11.178 kGy. The graft copolymers were characterized by FTIR, thermogravimetric and scanning electron micrographic analysis. Swelling behaviour in water, methanol, ethanol, acetone and DMF and dyeing and flame retarding properties of rayon fibre and grafted rayon fibre were investigated. Percent dye uptake (71.8 %) was found to be higher than that observed for the pristine fibre (57.4 %) and the grafted fibre after post phosphorylation reaction showed excellent flame retarding properties.     

外源硫诱导玉米镉胁迫耐性的生理机制研究

采用水培试验,研究根部施加外源SO_4~(2-)对Cd胁迫下玉米幼苗相关关键生理指标的影响,并分析Cd在玉米组织和亚细胞分布情况,探究外源硫S对玉米响应镉(Cd)胁迫的影响机制。结果表明,外源SO_4~(2-)处理,可显著降低Cd胁迫下玉米叶片与根中的丙二醛含量、相对电导率和抗氧化酶(SOD、CAT)活性。同时,根中抗坏血酸、非蛋白硫醇、植物螯合素含量在外源SO_4~(2-)处理后显著上升,在叶片中的变化不显著。外源SO_4~(2-)处理可降低玉米叶片中Cd含量,提升在根中的含量。根细胞壁和液泡中的Cd含量显著上升,从而减少Cd向地上部分的运输量。根细胞液泡膜中Cd运输专一性基因HMA3在外源SO_4~(2-)处理后,表达水平显著增强。因此,外源S可以通过提升Cd胁迫处理下玉米根细胞壁中Cd含量和抗坏血酸的保护作用,同时促进液泡的区室化作用,降低Cd向玉米地上部位的转运,以增强玉米对Cd胁迫的耐受性。     

Hydrogen peroxide increases potato tuber and stem starch content, stem diameter, and stem lignin content

Field-grown potato plants were sprayed twice weekly, from 21 to 90 days after planting, with 5 or 50 mM hydrogen peroxide (H₂O₂) solutions. Relative to water-sprayed controls, the H₂O₂ treatments significantly enhanced tuber starch accumulation by between 6.7% and 30%, as determined by specific gravity or the anthrone spectrophotometric method. Pronounced effects of similar H₂O₂ treatments on aerial stem anatomy and starch content were also found in glasshouse experiments. H₂O₂ treated stems were up to 27% thicker than controls, mainly due to enlarged medullar parenchyma cells. Histochemical observations indicated that there were more starch grains in cortex and pith tissue of H₂O₂-treated stems. H₂O₂ also increased the number and size of xylem tracheary elements in the vascular bundles and the number of interfascicular fibers. Quantification using image analysis confirmed that stems of H₂O₂ treated plants contained up to 3.4-fold more starch and 62% more lignin. This new chemical treatment to promote starch accumulation has potential utility in potato crop production and research.     

Comparison between isotope dilution and acetylene reduction methods to estimate N2 fixation rate of white clover in grass/clover swards

In two field experiments acetylene (C₂H₂) reduction by white clover in mixed swards was compared to N₂-fixed measured by ¹⁵N dilution. In both experiments, samples for C₂H₂ reduction were 7.5 cm diameter turves taken from plots within which microplots of 24 cm diameter were delimited and to which ¹⁵N was applied as ammonium sulphate (¹⁵NH₄)²SO⁴). C₂H₂ reduction was assayed every 6–7 d. The rate of C₂H₂ reduction per unit length of stolon was applied to the estimated stolon length within the appropriate microplot at the time of assay, and the amount of C₂H₂ that would have been reduced within the microplot was estimated by integration. In experiment 1, turves taken from grass/clover swards to which 0, 1·5, 3·0, 4·5 or 6·0 g N m^?2 had been applied were incubated in sealed chambers (10% C₂H₂, 90% air). The mean ratio of C2H2 reduced to N2 fixed during 5 weeks was 0.74:1. Application of N fertilizer lowered the proportion of assimilated N derived from N₂ fixation from 95% in unfertilized swards to 83% in those receiving 6 g N m^?2 (60 kg N ha^?1). In experiment 2, clover roots and stolons from plots that previously had been grazed were dissected from turves and incubated in a stream of C₂H₂ and air (i.e. the open system). The maximum rate of ethylene (C²H⁴) produced during the first 12 min was taken as a measure of true nitrogenase activity. The relationship between C₂H₂ reduced and N₂ fixed was significant (r=0.80**). The mole ratio was 0.55:1 for the 6 weeks duration of the experiment, the low ratio possibly being due to disturbance of the nodules adversely affecting acetylene reduction. Mole ratios from both experiments were well short of the theoretical 4·3:1. Using the open system does not, therefore, overcome the shortcomings of the acetylene reduction technique for measuring N₂ fixation of white clover in mixed swards.     

Radical Polymerization and Kinetics of N,N-diallyl-N,N-dimethylammonium Chloride and Vinyl Ether of Monoethanolamine

N,N-diallyl-N,N-dimethylammonium chloride (DADMAC) and vinyl ether of monoethanolamine copolymer (VEMEA) was synthesized by radical polymerization in aqueous media using ammonium persulfate as initiator. Copolymers synthesis was carried out by varying monomer composition at low conversion level. The viscosity of high molecular weight products was measured in aqueous 1 M NaCl solution and it was increased with increasing DADMAC amounts in the copolymer due to increasing positive charge. The structure of the product was identified by FTIR, ¹H, ¹³C-NMR spectroscopies and conductometric titration methods. We calculated monomer reactivity ratios with help of Finemann-Ross, Kelen-Tudos, and inverted Finemann-Ross methods. It was found that DADMAC is more reactive than VEMEA, therefore the amount of DADMAC in the copolymers always dominated regardless of the initial monomer ratio in solution and it was shown that the monomers are connected randomly in the polymer chain. The effect of various parameters such as monomer [M], initiator [I] concentrations, ratio of comonomers, etc. on polymerization was investigated systematically. So, the polymerization rate (R_p) equation was found to be R_p=k[M]^2.6[I]^0.6 where molar fractions of DADMAC and VEMEA was 90:10 and the temperature was 65 °C. Degree of polymerization was examined by using various monomers and initiator concentrations via the dilatometeric method. It was found that the polymerization rate increased directly with total monomer concentration and initiator content.     

不同氮肥对污染土壤玉米生长和重金属Cu、Cd吸收的影响

采用盆栽试验研究污染红壤不同氮肥处理对玉米生长和吸收重金属Cu和Cd的影响。结果表明,尿素和硝酸钙处理玉米生物量高于低硫酸铵用量处理和对照处理。在污染土壤中施入高氮量的尿素较其他处理有利于玉米生长和降低玉米植株体内重金属含量。与对照相比,尿素和硫酸铵的施用降低土壤pH值,从而增加红壤水溶态以及盐提取态Cu、Cd含量;硝酸钙处理升高土壤的pH值,降低盐提取态Cu含量。用1.0 mol/L NH₄NO₃盐提取态或水溶态根区土壤重金属含量能够很好地预测玉米对Cu和Cd的吸收。在Cu和Cd污染的酸性土壤上种植玉米,施加高用量尿素或者低用量硝酸钙来促进玉米生长和降低重金属含量,避免硫酸铵氮肥的施用。     

Comprehensive utilization of the hydrolyzed productions from rice hull

The study based on pretreatment, hydrolyzation and separation processes with the raw material rice hull, provides a comprehensive utilization of the hydrolyzed productions, such as glucose (C₆H₁₂O₆) from cellulose, silica (SiO₂), and byproduct crystalline sodium sulfate (Na₂SO₄·10H₂O). The optimum hydrolysis conditions are as follows: the concentration of H₂SO₄ is 72% (wt.%), the temperature is 50 °C, the ratio of H₂SO₄ solution volume (mL) to the rice hull mass (g) is 10:1 and the time is 5 min, the glucose yield rate reaches 45.6% (wt.%). The concentration of glucose solution could be 0.1 g/mL after neutralization measured by ultraviolet spectrophotometer (UV-VIS). Silica powder was below 50 nm characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The main byproduct crystalline sodium sulfate was featured by XRD and photographs.     

Convenient Agarose Preparation with Hydrogen Peroxide and Desulfation Process Analysis

Agarose is a natural seaweed polysaccharide and widely used in the medicine, food, and biological fields because of its high gel strength, non-toxicity, and electrical neutrality. The sulfate group is one of the main charged groups that affect the performance of agarose. In the present study, a simple, eco-friendly, and efficient method was explored for agarose preparation. After desulfation with hydrogen peroxide (H₂O₂), the sulfate content of agar reached 0.21%. Together with gel strength, electroendosmosis, gelling and melting temperature, the indicators of desulfated agar met the standards of commercially available agarose. Notably, the desulfated agar can be used as an agarose gel electrophoresis medium to separate DNA molecules, and the separation effect is as good as that of commercially available agarose. Further, the H₂O₂ desulfation process was analyzed. The addition of a hydroxyl radical (HO•) scavenger remarkably decreased the H₂O₂ desulfation rate, indicating that HO• has a certain role in agar desulfation. Sulfate content detection indicated that sulfur was removed from agar molecules in the form of sulfate ions (SO₄²⁻) and metal sulfate. The band absence at 850 cm⁻¹ indicated that the sulfate groups at C-4 of D-galactose in sulfated galactan were eliminated.     

Rheological behavior of magnetic carbon nanotubes and their application as kevlar coating

Carbon nanotube (CNT)/magnetite (Fe₃O₄) nanocomposites were successfully fabricated by nanocoating. When the CNT/Fe₃O₄ nanocomposites were added to a carbonyl (CI) based magnetorheological fluid (MRF), the magnetic rheological properties of the MRF were enhanced. Such enhancement in magnetic rheological properties of the CI-CNT/Fe₃O₄ MRF is considered to be attributable to both the superparamagnetic property of the magnetic layer covering the CNT surface and the high length to diameter ratio of the CNT/Fe₃O₄ nanocomposite. Impact properties for CI-CNT/Fe₃O₄ MRF treated Kevlar fabrics were also tested, and improved impact properties were observed with external magnetic fields compared to CI-MRF treated Kevlar fabrics.     

利用秸秆和肥料增殖木霉及对玉米茎基腐病的生物防治

以玉米秸秆为基质,筛选对木霉增殖有利的营养物质,对生防制剂的田间应用提供依据。利用Plack-ett-Burman试验设计筛选影响木霉产孢的主要营养物,采用最陡爬坡试验测定3种营养物的最适浓度范围;通过Box-Benhnken试验设计,对3种营养物浓度进行优化;盆栽试验检测木霉在土壤中的存活情况防治玉米茎基腐病。结果表明,筛选对木霉产孢影响较大的3个营养物质(氯化铵、硫酸钾、七水硫酸亚铁),最佳配方为氯化铵0.97 g/L,硫酸钾0.92 g/L,七水硫酸亚铁0.97 g/L,在此配方条件下孢子产量为2.61×10~9个/g。盆栽试验表明,利用木霉结合秸秆还田和肥料施用,可增强其存活能力和降低玉米茎基腐病的发生率和病情指数。     

不同品种鲜食玉米的营养成分及抗氧化活性比较

测定6个不同鲜食玉米品种的粗脂肪、蛋白质、淀粉、还原糖和总酚含量,对脂肪酸组成进行气相色谱分析。通过比较玉米浸膏的Fe~(3+)还原力和羟自由基(·OH)、超氧阴离子(O_2-·)、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率,评价其抗氧化活性,探讨抗氧化活性与玉米总酚的相关性。结果表明,鲜食玉米含粗脂肪6.17%~13.63%、蛋白质9.57%~15.30%、淀粉58.90%~69.52%、还原糖33.51%~42.12%、总酚1.52~2.68 mg/g。迪甜6号、晋超甜1号和超甜1825的粗脂肪、蛋白质、还原糖、总酚含量较高;京科糯2000、美玉糯13和都市丽人淀粉含量较高;美玉糯13饱和脂肪酸含量较高;晋超甜1号不饱和脂肪酸含量较高。超甜1825的Fe~(3+)还原力最强,迪甜6号清除·OH、O_2-·、DPPH自由基能力较强,抗氧化活性与玉米总酚含量呈正相关。     

Potato starch factory waste effluents I. Recovery of potassium and other inorganic cations

A process for recovery of valuable constituents from potato starch factory waste water is under development. Recovery of protein, amino acids, organic acids and a potash fertilizer should reduce the BOD markedly and provide a more economic waste treatment. Fertilizers containing 32–42% K₂SO₄, 53–56% (NH₄)₂SO₄, and 1% amino acids as well as trace elements from the tuber can be made as a byproduct of the amino acid recovery process. Data needed for design of the potash recovery part of the process are given, including: C/C₀ curves, exhaustion and regeneration rates, resin capacities and product recoveries, and a flow sheet for a proposed process.     

不同氮效率小麦品种苗期根系氮代谢及其吸收能力差异分析

为了解不同氮效率小麦品种根系氮代谢特征及其吸收能力的差异,明确小麦氮高效利用的生理机制,在水培条件下,研究了氮高效小麦品种漯麦18和氮低效小麦品种西农509的根系氮代谢特征和对NO-3、NH+4吸收的动力学特征。结果表明,漯麦18的根系GS活性、硝酸还原酶活性、游离氨基酸含量、可溶性蛋白质含量均高于西农509;而西农509的根系硝态氮和铵态氮含量高于漯麦18;漯麦18根系对NO-3、NH+4吸收的最大吸收速率(Vmax)显著高于西农509;漯麦18根系对NO-3、NH+4的亲和力(以Km的倒数衡量)低于西农509。结果说明,氮高效型小麦品种根系对NO-3、NH+4的吸收能力和同化能力均显著高于氮低效型小麦品种;小麦根系对NO-3、NH+4的吸收和同化是相互促进的关系。     

Co-migration of phytate with cereal β-glucan and its role in starch hydrolysis in-vitro

This study investigated the mechanisms of the co-migration of phytic acid during β-glucan isolation and its contribution to the retardation of starch hydrolysis in vitro. During the isolation, phytic acid precipitated together with β-glucan when ethanol was added as the precipitation solvent. The precipitation of phytic acid was reduced by lowering the pH or the ethanol concentration. When 20% (NH₄)₂SO₄ was used as the precipitation solvent, only minor phytic acid was found in isolated β-glucan, because phytic acid did not precipitate by this solvent. In the in vitro starch hydrolysis test, the isolated oat β-glucan (OBG) containing 3.9% co-migrated phytic acid showed better retardation effect than OBG containing 0.6% phytic acid. Therefore, we concluded that the co-migration of phytic acid was dependent on the chosen isolation procedure and conditions, and both intrinsic phytic acid and viscosity contributed to the retardation of starch hydrolysis.     

Studies on the macromolecular components of nonwood available in Bangladesh

The structural feature of macromolecular component of dhaincha, cotton stalks, jute fiber, rice straw and wheat straw, which are commonly used in paper pulp production in forest deficient countries, was thoroughly studied. Lignin was isolated by classical Bjorkman method and characterized by elemental and methoxyl analysis, alkaline nitrobenzene oxidation, FTIR and ¹H NMR spectroscopy. The C₉ formulas for cotton stalks, jute fiber, dhaincha, rice straw and wheat straw were C₉H_8.95O_3.53(OCH₃)_1.00, C₉H_8.12O_4.03(OCH₃)_1.65, C₉H_8.10O_4.65(OCH₃)_1.32, C₉H_8.58O_3.74(OCH₃)_1.23 and C₉H_8.31O_3.54(OCH₃)_1.23, respectively. The alkaline nitrobenzene oxidation products showed that syringyl to vanilin ratio of these nonwood varied from 1.1 to 2.9. Jute fiber showed the highest syringyl to vanilin ratio that are consistent with C₉ formula. The β-O-4 units in these nonwood lignins had predominately erythro stereochemistry type. The crystalline structure of these nonwood cellulose was also studied using X-ray diffraction and FTIR spectroscopy. The proportions of crystallinity, crystal size were varied from plant to plant. Jute fiber showed the highest proportion of crystallinity (73.4%) and crystal size (4.2 nm). The degree of polymerization of these nonwoods cellulose has also been studied. Degree of polymerization of jute cellulose was also the highest (3875). FTIR spectroscopy showed that these nonwoods cellulose was monoclinic unit cell structure (I_β). Carbohydrate analysis showed that the main sugar component in the hydrolyzates of these nonwoods were xylose apart from glucose.     

Modification of guar gum through grafting of acrylamide with potassium bromate/thiourea redox initiating system

In the present work, graft copolymers of acrylamide onto guar gum were synthesized by free radical polymerization using potassium bromate/thiourea redox initiating system. The guar gum and guar gum-g-polyacrylamide were characterized by infrared spectroscopy and thermogravimetric analysis. It was found that the guar gum-g-polyacrylamid was thermally more stable than pure guar gum. The grafting ratio, grafting efficiency, add-on, and conversion increased with the concentration of bromate and acrylamide, whereas they decreased with increasing the concentration of guar gum. The grafting ratio and grafting efficiency showed maximum value at the concentration of thiourea and hydrogen ions of 3.2×10^-3 mol dm^-3 and 4.0×10^-3 mol dm^-3, respectively, but decreased with further increasing the thiourea and hydrogen ions concentrations. The increase in temperature from 30 to 45 °C resulted in increasing the grafting ratio while decreasing the conversion. The optimum reaction time for the graft copolymerization was found to be 2 h. Compared to the parent guar gum, the graft copolymer showed higher water swelling capacity and metal ion sorption, as well as better flocculant behaviors.     

Seasonal changes in properties of abandoned terraced paddy field soil incubated under different water content conditions

The chemical properties of soil samples collected in August and November from an abandoned terraced paddy field dominated by reeds were examined by in vitro incubation under normal moisture and flooded conditions. Soil pH extracted with water [pH(H₂O)] was higher in soil samples collected from a depth of 0–10 cm in November than in samples collected in August; a high pH(H₂O) was maintained even during nitrification under normal moisture conditions. When soil samples collected in August from a depth of 0–10 cm were incubated under flooded conditions, a significant decrease in reduction potentials (Eh) and an increase in total Fe²⁺ concentrations were observed. Reductive conditions during sampling were strong in soil samples collected in August from a depth of 40–50 cm. Moreover, under normal moisture conditions, soil samples collected in August showed significant decreases in pH(H₂O) and significant production of water-soluble SO₄ ^2? than those collected in November. Glucose addition to soil samples collected from a depth of 0–10 cm caused nitrogen immobilization under normal moisture conditions, increases in exchangeable Fe²⁺ and Mn²⁺, and decreases in exchangeable bases (Ca²⁺, Mg²⁺, K⁺, and Na⁺) under flooded conditions. Seasonal changes in soil properties were probably due to microbial activity and vegetation phenology; thus, the timing of soil sampling influenced incubation experiment results. When abandoned terraced paddy fields are created as biotopes, seasonal changes in reductive soil conditions and slope position must be considered to prevent soil acidification and base cation elution.     

Controlling the Properties of OPEFB/PLA Polymer Composite by Using Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> for Microwave Applications

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe₂O₃) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S₁₁ and coefficient of transmission S₂₁ of the composites for various Fe₂O₃ filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe₂O₃) reduces the crystallinity of the composites. SEM data indicated that Fe₂O₃ filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8–12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe₂O₃ embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe₂O₃ filler content. Theoretical simulation studied the relation between ε′ and ε″ of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe₂O₃/OPEFB/PLA, the unique dielectric characteristics of Fe₂O₃ cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe₂O₃ filler in the composites.     

Copolymerization of 4′-vinylbenzo-15-crown-5 with Di(ethylene glycol) ethyl ether acrylate

Radical copolymerization behavior of 4′-vinylbenzo-15-crown-5, a vinyl monomer having apendant 15-membered crown ether unit (VCE) with di(ethylene glycol) ethyl ether acrylate (DEGEEA) was carried out in toluene solution using 2,2-azobisisobutyronitrile (AIBN) as an initiator. The copolymers were characterized by means of FT-IR,¹H-NMR, and¹³C-NMR. The reactivity ratio of VCE and DEGEEA, determined by Fineman-Ross and Kelen-Tudos method, gave values 0.55 for VCE, and 0.11 for DEGEEA respectively.     

Improvement of growth and gymnemic acid production by altering the macro elements concentration and nitrogen source supply in cell suspension cultures of Gymnema sylvestre R. Br

Gymnema sylvestre is an important medicinal plant which bears bioactive compound namely gymnemic acids. The present work deals with optimization of cell suspension culture system of G. sylvestre for the production of biomass and gymnemic acid and we investigated effects of macro elements (NH₄NO₃, KNO₃, CaCl₂, MgSO₄ and KH₂PO₄ - 0.0, 0.5, 1.0, 1.5 and 2.0× strength) and nitrogen source [NH₄⁺/NO₃⁻ ratio of: 0.00/18.80, 7.19/18.80, 14.38/18.80, 21.57/18.80, 28.75/18.80, 14.38/0.00, 14.38/9.40, 14.38/18.80, 14.38/28.20 and 14.38/37.60 (mM)] of Murashige and Skoog medium on accumulation of biomass and gymnemic acid content. The highest accumulation of biomass (165.00 g l⁻¹ FW and 15.42 g l⁻¹ DW) was recorded in the medium with 0.5× concentration of NH₄NO₃ and the highest production of gymnemic acid content was recorded in the medium with 2.0× KH₂PO₄ (11.32 mg g⁻¹ DW). The NH₄⁺/NO₃⁻ ratio also influenced cell growth and gymnemic acid production; both parameters were greater when the NO₃⁻ concentration was higher than that of NH₄⁺. Maximum biomass growth (159.72 g l⁻¹ of FW and 14.95 g l⁻¹ of DW) was achieved at an NH₄⁺/NO₃⁻ ratio of 7.19/18.80, and gymnemic acid production was also greatest at the same concentration of NH₄⁺/NO₃⁻ ratio (11.35 mg g⁻¹ DW).