Microwave promoted methylation of plant polysaccharides

O-Methylation is of outstanding importance in structural polysaccharide chemistry. A novel method for the methylation of polysaccharides using microwave (MW) irradiation is described. Seed gum from Cyamopsis tetragonolobus (Guar) was fully methylated with dimethyl sulphate and sodium hydroxide using 100% microwave power for 4 min in 68% yield. The completely methylated seed gum thus obtained was hydrolyzed by 70% formic acid followed by 0.5N H₂SO₄ under full microwave power for 1.16 and 1.66 min, respectively. The partially methylated monosaccharides were separated and identified.     

Synthesis and characterization of guar gum‐graft‐polyacrylonitrile

Cerium(IV) mediated grafting of polyacrylonitrile on to guar gum was studied. Grafting parameters were studied gravimetrically, as a function of temperature, initiator concentration and Guar to acrylonitrile ratio. Higher temperatures resulted in higher monomer conversion and homopolymer formation. Both monomer conversion and extent of grafting increased with increase in cerium ion concentration in the range studied (0.91–9.12 mmol/l). Similar results were obtained with increase in monomer to guar gum ratio from 1 to 5. Grafting with this initiator was found to be generally good with high grafting efficiencies and low homopolymer formation for most experiments. The copolymers obtained were subjected to alkaline hydrolysis to convert nitrile groups in to carboxylic acid groups and the water absorbency of the resulting anionic guar gum was studied. Materials with water absorption up to 300 g/g could be obtained from this study. Copyright © 2003 John Wiley & Sons, Ltd.     

两性田菁胶在处理生活污水中的助凝作用

研究了以聚合硫酸铁为主凝剂、两性田菁胶(ASG)为助凝剂处理城市生活废水的各种影响因素.实验结果表明:聚合硫酸铁和两性田菁胶分别以200mg/L和10mg/L的复配浓度、pH值接近7时混凝效果最佳,CODCr去除率达到近80%,处理后废水CODCr达到国家排放标准.     

Superoxes,high temperature universal phases in (GC)2

Most of the common classes of organic compounds chromatograph normally on Superoxes. There is no tailing or adverse effect from excessively different activity different activity coefficients. Superoxes are therefore universal phases for gas chromatography. This is also expressed by a wide useful temperature range from ～50° to ～300°. High MW Superox-4 has a MAOT about 20° higher than the lower MW Superox-0.1. Several applications illustrating the versatility of Superox phases in (GC)² are presented.     

Graft copolymerisation of acrylamide onto cashew gum

The synthesis of cashew gum-g-polyacrylamide was carried out at 60 °C by a radical polymerisation using potassium persulphate as the redox initiator under N₂ atmosphere. A series of graft copolymers, varying in acrylamide concentration and keeping the concentration of the initiator and polysaccharide constant, was prepared. These graft copolymers were characterised by elemental analysis, infrared and ¹³C NMR spectroscopy, rheological studies, differential scanning calorimetry and thermogravimetric analysis. Comparisons amongst grafting parameters of the reaction of various natural polysaccharides with polyacrylamide (PAM) were carried out. High percentages of acrylamide conversion (%C) and grafting efficiency (%E) were obtained for cashew gum (CG), even with a low acrylamide/gum ratio. All copolymers had intrinsic viscosity and thus the hydrodynamic volume much higher than the CG value and closer to the PAM. The CG-g-PAM solution had an absolute viscosity at 2.5% concentration (wt./vol.) up to 33 and 3.3 times the CG and PAM values, respectively. Grafting of PAM chains onto the polysaccharide enhances its thermal stability.     

Found in the Folds: A Rediscovery of Ancient Egyptian Pleated Textiles and the Analysis of Carbohydrate Coatings

Charles T. Currelly, first director of the Royal Ontario Museum, participated in excavations of the tomb of King Nebhepetre, now known as Mentuhotep II, (Dynasty XI) in Deir el-Bahri, Egypt in 1906. He brought to Canada many objects from the excavations, and objects that he purchased while in Egypt; these formed the initial collection of the museum. Among the objects were seven fragments of fine linen cloth with intricate pleat patterns. Recently, the cloths became the subject of a study to learn how they had retained their pleats for 4000 years. Samples were examined and analysed using polarised light microscopy, scanning electron microscopy-electron dispersive X-ray spectrometry, gas chromatography-mass spectrometry, and pyrolysis-gas chromatography-mass spectrometry. Three of the cloths were likely fragments of clothing re-purposed as bandages and were found to be saturated in mummification balms composed of Pinaceae resin, Pistacia resin, and an essential oil characterised by a high abundance of cedrol, possibly originating from a juniper species. All seven of the cloths were found to have traces of polysaccharides from two probable sources: an arabinogalactan gum such as gum arabic or a fruit gum, and a polyglucoside, possibly starch.     

In Vitro Evaluation of Curcumin Encapsulation in Gum Arabic Dispersions under Different Environments

Biopolymers, especially polysaccharides (e.g., gum Arabic), are widely applied as drug carriers in drug delivery systems due to their advantages. Curcumin, with high antioxidant ability but limited solubility and bioavailability in the body, can be encapsulated in gum Arabic to improve its solubility and bioavailability. When curcumin is encapsulated in gum Arabic, it is essential to understand how it works in various conditions. As a result, in Simulated Intestinal Fluid and Simulated Gastric Fluid conditions, we investigated the potential of gum Arabic as the drug carrier of curcumin. This study was conducted by varying the gum Arabic concentrations, i.e., 5, 10, 15, 20, 30, and 40%, to encapsulate 0.1 mg/mL of curcumin. Under both conditions, the greater the gum Arabic concentration, the greater the encapsulation efficiency and antioxidant activity of curcumin, but the worse the gum Arabic loading capacity. To achieve excellent encapsulation efficiency, loading capacity, and antioxidant activity, the data advises that 10% is the best feasible gum Arabic concentration. Regarding the antioxidant activity of curcumin, the findings imply that a high concentration of gum Arabic was effective, and the Simulated Intestinal Fluid brought an excellent surrounding compared to the Simulated Gastric Fluid solution. Moreover, the gum Arabic releases curcumin faster in the Simulated Gastric Fluid condition.     

Effect of Coconut Protein and Xanthan Gum,Soybean Polysaccharide and Gelatin Interactions in Oil-Water Interface

We report on our study of the interactions between coconut protein extracted from coconut meat and three hydrocolloids (gelatin, xanthan gum, and soybean polysaccharide) and their interfacial adsorption and emulsification properties. We used Zeta potential, fluorescence spectroscopy scanning and ITC to investigate the interactions between a fixed concentration (1%) of coconut protein and varying concentrations of hydrocolloid. Through the interfacial tension and interfacial viscoelasticity, the interfacial properties of the hydrocolloid and coconut protein composite solution were explored. The physical stability of the corresponding emulsion is predicted through microstructure and stability analysis. Xanthan gum forms a flocculent complex with coconut protein under acidic conditions. Soy polysaccharides specifically bind to coconut protein. Under acidic conditions, this complex is stabilized through the steric hindrance of soy polysaccharides. Due to gelatin-coconut protein interactions, the isoelectric point of this complex changes. The interfacial tension results show that as time increases, the interfacial tensions of the three composite solutions decrease. The increase in the concentration of xanthan gum makes the interfacial tension decrease first and then increase. The addition of soybean polysaccharides reduces the interfacial tension of coconut protein. The addition of xanthan gum forms a stronger elastic interface film. Emulsion characterization showed that the gelatin-added system showed better stability. However, the addition of xanthan gum caused stratification quickly, and the addition of soybean polysaccharides also led to instability because the addition of polysaccharides led to a decrease in thermodynamic compatibility. This research lays the foundation for future research into coconut milk production technology.     

Photopolymeritation of Methyl Methacrylate and Styrene by Sulfur Ylides

The photoinitiating ability of some sulfur ylides was studied. Diphenylsulfonium bis (methoxycarbony1)methylide (DPSY) could photoinitiate methyl methacrylate and styrene. A free radical mechanism was confirmed by a kinetic study, the inhibiting effect of benzoquinone, and the copolymer composition. From an analysis of the photodecomposition products it is suggested that the phenyl radical generated from the bond fission between the sulfur atom and the phenyl group participates in the initiation of this free radical polymerization. Methylphenylsulfonium bis (methoxycarbonyl) methylide, as well as DPSY, served as a photoinitiator, but dimethylsulfonium bis (methoxycarbony1)methylide did not. The differences are explained based on UV spectra.     

Polymers Derived from 4-Substituted Salicylic Acids as Antifungal Agents

4-Amino-, chloro-, and bromo-substituted salicylic acid-formaldehyde polymers and their metal chelates were screened for their antifungal activity. Various copolymers prepared from 4-chloro-(bromo)salicylic acid, formaldehyde, and other comonomers were also screened for their antifungal activity. All these polymers, copolymers, and polychelates were found active against several fungi Their fungicidal activities are compared with those of the corresponding monomers and monomeric chelates.