共查询到20条相似文献,搜索用时 15 毫秒
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Jae Wook Song Han Do Ghim Jin Hyun Choi Sohk-Won Ko Won Seok Lyoo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(10):1810-1816
To provide sodium alginate (SA) with an antimicrobial property, we introduced chito-oligosaccharide (COS) via chemical bonding in a two-step procedure. We reacted COS with N-methylol acrylamide (NMA) with N-methylol groups to prepare acrylamidomethyl chito-oligosaccharide (COS–NMA). SA with COS side chains (SA–COS) was produced through a subsequent reaction of SA with COS–NMA. The chemical structure of SA–COS was confirmed by IR spectroscopy and 1H NMR spectroscopy. With a two-step method, we successfully prevented insoluble-complex formation due to electrostatic attraction between chitosan and alginate. SA–COS showed excellent antimicrobial activity, with the growth of microorganisms completely suppressed by a small amount of COS (1.8 wt %). © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1810–1816, 2001 相似文献
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A new method for analysis of sodium ortho-, pyro-, and triphosphate is reported. This procedure consists of the measurement of three values which permit a simultaneous solution of three independent equations, yielding the relative amounts of linear phosphates present in the mixture. The measured quantities were: 1) pyrophosphate, gravimetrically determined as zinc pyrophosphate, reprecipitated at 19° and at a pH of 4.0 – 4.5, 2) silver phosphate, determined by a conductance titration at 12°, of standardized silver nitrate solution, and 3) total phosphate, determined after complete hydrolysis to orthophosphate in hot acid solution. 相似文献
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Degradation is often a critical property of materials utilized in tissue engineering. Although alginate, a naturally derived polysaccharide, is an attractive material due to its biocompatibility and ability to form hydrogels, its slow and uncontrollable degradation can be an undesirable feature. In this study, the degradation behavior of hydrogel based on oxidized sodium alginate (OSA) crosslinked with Ca2+ was studied in phosphate buffer solution (PBS, pH = 7.4) and Tris-(hydroxymethyl) aminomethane–HCl (Tris–HCl, pH = 7.4) at 37 °C. The degradation behavior of OSA hydrogels with different degrees of oxidation was evaluated as a function of degradation time by monitoring the changes of molecular weight and weight loss. It was found that the degradation behavior relied heavily on the degree of oxidation and the surrounding medium. This result indicates that the degradation rates of OSA hydrogels can be controlled by changing the degree of oxidation. 相似文献
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《Solid State Sciences》1999,1(1):15-24
Hydrothermal synthesis, IR characterization and X-ray single-crystal structure are reported for CaBa(HPO4)2. It crystallizes in the monoclinic system, space group P21/a (N∘14) with a = 9.470(2) Å, b = 7.930(1) Å, c = 9.865(1) Å, β = 115.78(1)°, V = 667.1(2) Å3 and Z = 4. The refinement of data leads to R = 0.0331 for 1131 observed reflections [I > 4σ(I)]. The crystal structure of CaBa(HPO4)2 is built up from corner-and/or edge-sharing BaO9 polyhedra, CaO7 pentagonal bipyramids and (H)PO4 tetrahedra giving rise to a three-dimensional network. The HPO42− groups are located in layers parallel to the ab plane at z ~ 0 and z ~ 1/2. Interleaved barium and calcium cations ensure the cohesion between these sheets. Hydrogen bonds contribute to the stability of the structure. 相似文献
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Suk Hang Chan Lillian Sze Man Lam Wing Tak Wong Wai Kin Chan 《Macromolecular rapid communications》2000,21(15):1075-1080
We report the synthesis of a polymer that contains the diaza‐18‐crown‐6 moiety on the polymer main chain. Metal containing polymers were obtained when the respective barium or strontium complexes were used as monomers. These polymers emitted greenish blue light in solution, and the metal had little influence on absorption and emission energies. In the solid state, the position of the emission peaks was different probably due to a different degree of aggregation. 相似文献
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Aleksey A. Sirotenko 《Mikrochimica acta》1955,43(1):153-154
Summary The titrimetric dry combustion method can be employed for micro-determination of sulfur in organic compounds containing both alkali metal or alkaline earth metal and sulfur.The residue of alkali or alkaline earth sulfate in the boat, formed during the combustion, is fused with 3 to 4 times its weight of boron trioxide, whereby sulfur trioxide is displaced by the boron trioxide.
Zusammenfassung Die Bestimmung des Schwefels durch Verbrennung und Titration der gebildeten Schwefelsäure kann mit organischen Verbindungen ausgeführt werden, die Alkalien oder alkalische Erden enthalten.Der Metallsulfate enthaltende Verbrennungsrückstand wird im Schiffchen mit der 3- bis 4fachen Menge Bortrioxyd versetzt. Beim darauffolgenden Erhitzen wird das Schwefeltrioxyd in Freiheit gesetzt.
Résumé On peut employer la méthode par combustion à sec et titrage pour le dosage du soufre dans des composés organiques contenant un métal alcalin ou un métal alcalino-terreux.Le résidu de sulfate alcalin ou alcalino -terreux formés pendant la combustion dans la nacelle est fondu avec trois ou quatre fois son poids de trioxyde de bore; l'anhydride sulfurique est déplacé par le trioxyde de bore.相似文献
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Dang-Ge Gao Chen Chen Jian-Zhong Ma Bin Lv Xiao-Li Jia 《Journal of Sol-Gel Science and Technology》2013,65(3):336-343
The zinc oxide sol containing quaternary ammonium salts (DMDAAC-ZnO) was synthesized by zinc acetate and dimethyldiallyl ammonium chloride via the sol–gel process. Effects of zinc acetate concentration, diethanolamine dosage and dimethyldiallyl ammonium chloride dosage on the absorbance-ratio and viscosity of the sol were investigated. Zinc oxide sols were characterized by XRD, TEM and FT-IR. DMDAAC-ZnO was applied to cotton samples and cotton samples treated were tested by antibacterial activity, UV resistance and breaking strength. The antibacterial activity and UV resistance of samples treated by zinc oxide sol containing quaternary ammonium salt were both better than sample treated by zinc oxide sol. 相似文献
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Somayeh Hosseini Amir Charkhi Abdolhamid Minuchehr Seyyed Javad Ahmadi 《Chemical Papers》2017,71(6):1143-1153
Pervaporation (PV) separation of water–acetonitrile mixture using sodium alginate (NaAlg) based mixed matrix membranes (MMM) comprising different amounts of nano NaA zeolite (10, 20 and 30 wt%) is investigated in various concentrations of water and temperatures. The prepared membranes are modified by sulfosuccinic acid (SSA) as a crosslinking agent. NaAlg-NaA/SSA membranes are synthesized by a solution casting technique. The process and membrane performance including separation factor, flux and activation energy of permeation are determined. Results reveal that adding of nano zeolite may lead to an increase in the flux and the separation factor of sodium alginate membrane up to 123 and 169%. In addition, using MMM in dehydration of a feed containing 30 wt% of water shows much better performance than alginate membrane. Furthermore, the activation energy of water permeation through MMM is predicted lower than sodium alginate membrane which reflects the facilitated permeation of water through MMM. 相似文献
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FTIR reflection spectra of molten chloroaluminates containing alkali earth chlorides showC
2v
andC
3v
perturbations of AlCl
4
–
. The splitting ofv
3(F
2) is proportional to the ionic potential of the counterion. The observation of anion-cation stretching vibrations allows the strength of the interaction to be evaluated. Molten NaAl2OCl5 is assumed to contain the Al4O2C1
10
2–
ion. 相似文献
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The abilities of the title ligands for alkali and alkaline earth cations are estimated by 1H and 13C NMR and by picrate extraction from water to methylene chloride. These ligands are shown to be excellent complexing agents for alkaline earth cations. Complexation occurs preferably at the ether and amide carbonyl groups. The stoichiometry of complexation is evaluated by 1H NMR. 相似文献
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The transport selectivity of carbonate ions relative to chloride ions \(\left( {P_{Cl^ - }^{CO_3^{2 - } } } \right)\) through an anion-exchange membrane during electrodialysis is investigated before and after the membrane was modified by the electrolytic precipitation of sodium alginate on its surface, as well as by pretreating the membrane in a solution of sodium alginate. It is established that the experimental value of \(P_{Cl^ - }^{CO_3^{2 - } } \) is appreciably smaller than the calculated value for the unmodified membrane at low values of current density. At large currents the calculated value of \(P_{Cl^ - }^{CO_3^{2 - } } \) is 0.83, and the experimental value is 0.64. During electrodialysis of the working solution, which contains sodium alginate at a concentration of 1–2 g l?1, \(P_{Cl^ - }^{CO_3^{2 - } } \) decreases by 2–3 times in the current-density range 0.25–1 A dm?2. Pretreatment of the membrane in a solution of sodium alginate having a concentration of 10 g l?1 for 72 h decreases \(P_{Cl^ - }^{CO_3^{2 - } } \) from 0.50 (unmodified membrane) to 0.35. 相似文献
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Starch and sodium humate were utilized as raw material for synthesizing starch‐g‐poly(acrylic acid)/sodium humate (St‐g‐PAA/SH) superabsorbent by graft copolymerization reaction of starch (St) and acrylic acid (AA) in the presence of sodium humate (SH) in aqueous solution. The effect of weight ratio of AA to St, initial monomer concentration, neutralization degree of AA, amount of crosslinker, initiator and SH on water absorbency of the superabsorbent were studied. The swelling rate and swelling behavior in NaCl solution as well as reswelling ability of the superabsorbent were systematically investigated. The results showed that the superabsorbent synthesized under optimal conditions with SH content of 7.7 wt% and St content of 11.5 wt% exhibits water absorbency of 1100 g/g in distilled water and 86 g/g in 0.9 wt% NaCl solution, respectively. Introducing SH into the St‐g‐PAA polymeric network can improved the swelling rate and reswelling capability of the superabsorbent. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Zr(O3PONa)2 · nH2O can be prepared as a single crystalline phase by direct precipitation in the presence of HF. This material is a powder. When a single crystal of -HZrP is exchanged with Na+, Zr(O3PONa)2 · nH2O is obtained as a powder-like crystal. The zero level Weisenberg photograph shows a monoclinic symmetry; the unit cell (a = 0.900 nm, b = 1.059 nm, c = 2.210 nm and β = 117.12°) contains eight formula units Zr(O3PONa)2 · 3H2O. This is doubled with respect to -HZrP. 相似文献
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Summary The thermal behavior of KH2PO4, NaH2PO4 and Na2HPO4 under non-isothermal conditions using TG method with different heating rates was studied. The values of the reaction rate were processed by means of Friedmans differential-isoconversional method. A dependence of the activation energy vs. conversion was observed. Therefore a procedure based on the compensation effect (suggested by Budrugeac and Segal) was applied. A less speculative data processing protocol was offered by the non-parametric kinetics method suggested by Serra, Nomen and Sempere. Three steps were observed by non-isothermal heating: a dehydration, a dimerization and a polycondensation. The differences in the intimate reaction mechanism are determined by the initial number of water molecules. 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1979,41(7):1069-1073
Solid state 1:1 complexes of divalent Mg, Ca, Sr and Ba with thiomalic acid(tma) have been isolated and characterised by elemental analysis, IR spectra and thermal studies. It is shown that tma coordinates to the metal ions through carboxylic oxygen atoms. Thermal studies of these complexes show that desulphurisation preceeds decarbonylation reaction leading to the formation of metal carbonates in all the cases except Mg where MgO is the end product. Thermal stability of the anhydrous thiomaltes follows the order Mg ∼ Ca > Sr > Ba. Structures have been proposed based on the information obtained from these studies. 相似文献
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《先进技术聚合物》2018,29(7):1895-1901
This study aimed to develop polyelectrolyte‐structured antimicrobial food packaging materials that do not contain any antimicrobial agents. Cationic hydroxyethyl cellulose was synthesized and characterized by Fourier‐transform infrared, 1H NMR, and 13C NMR spectroscopy. Its nitrogen content was determined by Kjeldahl method. Polyelectrolyte‐structured antimicrobial food packaging materials were prepared using hydroxyethyl cellulose, cationic hydroxyethyl cellulose, and sodium alginate. Antimicrobial activity of materials was defined by inhibition zone method (disc diffusion method). Thermal stability of samples was evaluated by thermal gravimetric analysis and differential scanning calorimetry. Surface morphology of samples was investigated by SEM. The obtained results prove that produced food packaging materials have good thermal and antimicrobial properties, and they can be used as food packaging material in many industries. 相似文献