Weak Acidic Conditions Research Articles

An Effective Synthesis of Acid-Sensitive Epoxides via Oxidation of Terpenes and Styrenes Using Hydrogen Peroxide under Organic Solvent-Free Conditions

An efficient epoxidation process for various terpenes and styrenesusing a hydrogen peroxide-tungsten catalytic system with organicsolvent- and halide-free conditions was developed. In the presenceof the catalytic system, Na 2 WO 4 , PhP(O)(OH) 2 ,and [Me( N-C 8 H 17 ) 3 N]HSO 4 ,and under weak acidic conditions, hydrogen peroxide successfullyepoxidized α-pinene to α-pinene oxide in 95% selectivityat 91% conversion, while the previously published conditionsutilizing NH 2 CH 2 P(O)(OH) 2 as apromoter provided no epoxide.

Preparation of cationic chitosan-polyacrylamide flocculant and its properties in wastewater treatment

Chitosan derived from crab shells, was used to prepare the graft polymer in aqueous solution with acrylamide (AM) and methacrylatoethyl trimethyl ammonium chloride (DMC) as raw materials and ceric ammonium nitrate (CAN) as initiator. The flocculation ability of the resulting polymer (PCAD) was studied in waste water treatment experiments. Its properties were determined on the basis of the transmittance of waste water after flocculation. The effects of chitosan and DMC content on PCAD’s flocculation ability were studied. Flocculation experiments were also undertaken under various pH conditions. According to the experimental data, the flocculation ability could be improved when chitosan content decreased in the raw material, but the monomer conversion would decrease obviously. When the chitosan’s content was more than 65%, AM and DMC groups were less on each chitosan molecule. So PCAD’s flocculation ability was poor. Similarly, high content of DMC would result in low monomer conversion and high flocculation ability. PCAD molecules with more DMC group had more positive charges. It was favorable to flocculation. However, monomer conversion would decrease with the increase of DMC content. The suitable conditions were that chitosan and DMC contents were 65% and 15–20%, respectively. The experiment data showed that PCAD had good flocculation ability under weak acidic condition. Its ability would be weakened by strong acidic or alkaline condition. The flocculation efficiency was the best at pH of 5.5 when PCAD’s dosage was 8mg·L−1. Compared with cationic polymer (the copolymer of AM and DMC, PAD), PCAD showed better flocculation ability under acid and neutral conditions, but worse ability under alkaline condition.

Aminoacid-derivatized oxidovanadium complexes: Synthesis, structure and bromination reaction activity

A new family of aminoacid-derivatized oxidovanadium complexes as potential functional model of vanadium haloperoxidases: [VVO(sal-phe)(OMe) (MeOH)] (1), [VIVO(sal-ala)(2,2′-bipy)]·H2O (2), [VIVO(sal-ala)(1,10-phen)]·0.5H2O (3) and [VIVO(sal-his)(1,10-phen)]·2MeOH (4) (H2sal-phe=Schiff base derived from salicylaldehyde and dl-β-phenylalanine, H2sal-ala=Schiff base derived from salicylaldehyde and dl-α-alanine, H2sal-his=Schiff base derived from salicylaldehyde and l-histidine) have been synthesized. All the complexes were characterized by elemental analysis, IR spectra and UV–Vis spectroscopy. In particular, molecular structures of three representative complexes (1, 2 and 3) were determined by X-ray crystallography. In addition, bromination reaction activity of the starting material and the complexes has been tested by a method with phenol red as organic substrate in the presence of H2O2, Br− and phosphate buffer, the studying results indicate that the vanadium complexes can catalyze the visible conversion of phenol red to bromophenol blue under weak-acid conditions and the different structural characterizations of the complexes exhibit different catalytic activity, therefore, the complexes can be considered as a potential functional model of VHPO.

One-pot synthesis of novel ferric cubic mesoporous silica (Im3m symmetry) and its highly efficient adsorption performance

A novel facile route, denoted here as I0HO∼COO−S+, was reported to synthesize cubic Im3m mesoporous silicas and metal substituted analogues for the first time by utilizing commercial conventional cationic surfactant cetyltrimethylammonium bromide (CTAB) to direct the mesostructures along with citric acid as the acid media to give a weak acidic condition. This weak acidic system favors not only the fine phase control but also the optimal incorporation of ferric ions, providing a skilful way to prepare the mesoporous composites with a surprising adsorption capability. UV-vis DRS and ESR spectra indicated that the majority of the metal ions inserted into the siliceous framework within the tetrahedral coordination environment. Owing to the controllable incorporation of ferric species that form a monolayer on the channel wall plus the three-dimensional cage-like mesostructure that generates a fine geometric confinement towards the adsorbate, the mesoporous composite overruns zeolite NaY in the instantaneous adsorption of volatile nitrosamines and 1,3-butadiene for the first time.

Helical opposition in poly(2‐methoxyaniline) doped with beta‐cyclodextrin sulfate: electrochemical polymerization and chiroptical properties

AbstractExcess one‐handed helical poly(2‐methoxyaniline) (PMOA) was synthesized by electrochemical polymerization of 2‐methyoxy aniline in the presence of CDS. PMOA prepared at strong acidic condition shared an opposite excess one‐handed helicity against to that prepared at weak acidic condition. Through studying helix‐inducing dynamic, mechanism for helical opposition was found originating from the dynamic transfer. While predominant dynamic transferred from electrostatic interaction to H‐bonding, PMOA selectively adsorbing the opposite excess one‐handed helix. Dynamic‐transferring tests were carried out by adjusting acid and salt concentration in reaction solution, respectively. Dedoping and redoping cycle was also performed in order to study the chiroptical properties of PMOA after dedoping. The electroactivity of PMOA was checked by cyclic voltammetry. At the same time, PMOA showed interesting chiroptical properties in the states of reduction and oxidation, respectively. ICD spectra indicated that helicity and handedness were well remained in PMOA backbone after redox cycle. Copyright © 2010 John Wiley & Sons, Ltd.

Effect of reduction on the stability of Pu(VI) hydrolysis species

AbstractThe chemical speciation of aqueous plutonium species has been performed by spectrophotometry. The main focus was concentrated on the effect of Pu(V) produced by the reduction of Pu(VI) on the stability of the Pu(VI) hydrolysis species. In order to detect the trace amounts of PuO2+ions, a liquid waveguide capillary cell with an optical path length of 100 cm was connected to a spectrophotometer. As a consequence of the improved detection sensitivity, an absorption band at 569 nm being indicative of Pu(V) was observed within one day after the sample preparation from the pure Pu(VI) solution. The first hydrolysis species was (PuO2)2(OH)22+, at plutonium concentrations of 0.1–0.12 mM and at weak acidic conditions (pH 5–6). The formation constant of (PuO2)2(OH)22+was determined to be log*β′22=−7.34±0.22 at 0.01 M NaClO4. This dinuclear hydroxide species was unstable and disappeared within one month after the sample preparation at the present experimental condition. In the neutral pH range, the second hydrolysis species was formed and remained for over one year. The samples showed different behavior for the reduction of Pu(VI). The time dependent distribution of plutonium species and their characteristic features in the absorption spectra are reported.

Catalytic hydrodechlorination of chlorophenols by Pd/Fe nanoparticles: Comparisons with other bimetallic systems, kinetics and mechanism

This study investigated dechlorination of 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP), and 2,4,6-trichlorophenol (246TCP) with Pd/Fe nanoparticles. The reaction rates were significantly faster than those achieved with Pt/Fe, Ni/Fe, Cu/Fe and Co/Fe nanoparticles. The chlorophenols (CPs) could be completely reduced to phenol by Pd/Fe following the pseudo-first-order kinetics, and the rates followed the order of 246TCP < 24DCP < 4CP. The 246TCP reduction rate with Pd/Fe increased with temperature and the estimated activation energy was 29.8 kJ/mol. The CPs dechlorination rate increased linearly with Pd loading, suggesting that Pd catalyst could be the only reactive site. Based on rigorous analysis of the transient formations and concentrations of various intermediates, a scheme of transformation pathways and the reaction mechanism was proposed to delineate 246TCP dechlorination to phenol. The influence of pH on the CPs dechlorination was investigated, and weak acidic condition is more favorable to the dechlorination reaction. H 2 evolution or iron corrosion rate initially followed the pseudo-first-order kinetics, and was reverted to the zero-order kinetics for prolonged reaction (>24 h).

ChemInform Abstract: Selective Determination of Trace Arsenic and Antimony Species in Natural Waters by Gas Chromatography with a Photoionization Detector.

Traces amounts of arsenic and antimony in water samples were determined by gas chromatography with a photoionization detector after liquidnitrogen cold trapping of their hydrides. The sample solution was treated with sodium hydroborate (NaBH4) under weak-acid conditions for arsenic(III) and antimony(III) determination, and under strong-acid conditions for arsenic(III+V) and antimony(III+V) determination. Large amounts of carbon dioxide (CO2) and water vapor obscured determination of arsine and stibine. Better separation from interference could be achieved by removing CO2 and water vapor in two tubes containing sodium hydroxide pellets and calcium chloride, respectively. The detection limits of this method were 1.8 ng dm−3 for arsenic and 9.4 ng dm−3 for antimony in the case of 100-cm3 sample volumes. Therefore, it is suitable for determination of trace arsenic and antimony in natural waters.

Rapid analysis of trace levels of flavins by pressurized capillary electrochromatography-laser induced fluorescence detection with sulfonated N-octadecyl methacrylate monolith

In this paper, pressurized capillary electrochromatography (pCEC) with laser induced fluorescence detection (LIF) was demonstrated as a viable approach for the separation and determination of trace flavins in human plasma, where flavins tend to be degraded ex vivo. Using a sulfonated N-octadecyl methacrylate monolithic column in isocratic pCEC separation, symmetrical peak shapes and rapid separation could be obtained in a weakly acidic mobile phase. Baseline separation of riboflavin, flavin mononucleotide and flavin adenine dinucleotide could be achieved within 4.5 min in a mobile phase containing 60% (v/v) acetonitrile and 40% (v/v) of 20 mmol L −1 phosphate buffer (pH 4.0), with −22 kV of applied voltage and 290 psi of supplementary pressure and 0.02 mL min −1 of flow rate. Based on a 473 nm laser diode double pumped solid state source, flavins could be determined by LIF with the detection limit (LOD) as low as 0.5 nmol L −1 (S/N = 3). The concentration ranges were 0.005–2 μmol L −1 for RF and FMN, and 0.02–40 μmol L −1 for FAD. Owing to the weakly acidic condition selected in this experiment, the high fluorescence quantum yields and good stability of flavins contributed to a preferable analysis. Combined with a simple clean-up procedure, this method has been proved to be effective for the rapid and selective analysis of trace levels of flavins in human plasma without sample preconcentration.

Simultaneous Determination of Valproic Acid and its Toxic Metabolites, 4-ene-VPA and 2,4-diene-VPA in Rat Plasma using a Gas Chromatographic-mass Spectrometric Method

− A gas chromatographic-mass spectrometric (GC-MS) method was developed for the simultaneous determination of valproic acid (VPA) and its toxic metabolites, 4-ene-VPA and 2,4-diene-VPA in rat plasma. Extraction was performed in weak acidic condition (pH 5.2) to avoid degradation of 4-ene-VPA and 2,4-diene-VPA. The recoveries for 4-eneVPA and 2,4-diene-VPA were more than 70% and that for VPA was 33-42%. R value for each compounds exceeded 0.998 in calibration curve during all the analysis. Accuracy and precision ranged from 88.3 to 113.2% and from 2.16 to 14.2%, respectively The method was successfully applied to monitor plasma concentrations of VPA, 4-ene-VPA and 2,4-diene-VPA after intravenous administration of VPA at the dose of 100 mg/kg, suggesting that these toxic metabolites may involved in the hepatotoxicity induced by VPA. Key words− valproic acid (VPA), 4-ene-VPA, 2,4-diene-VPA, quantitative analysis, GC-MS (gas chromatographic-mass spectrometry), pharmacokinetics Valproic acid (VPA, 2-propylpentanoic acid, Fig. 1) is a broad-spectrum antiepileptic agent that has a branched-chain carboxylic acid structure. VPA has been used to treat bipolar disorder, migraine, and neuropathic pain (Loscher et al., 1993; Murakami et al., 1992; Sugimoto et al., 1983), but it has been demonstrated to be associated with fatal liver toxicity (Perucca, 2002; Zimmerman et al., 1982; Zafrani et al., 1982; Bryant et al., 1986). Although the mechanism by which VPA leads to liver toxicity has not been fully elucidated, a large body of evidence suggests that reactive VPA metabolites (4ene-VPA; 2-propyl-4-pentanoic acid and its subsequent metabolite, 2,4-diene-VPA; 2-propyl-2,4-pentanoic acid) may mediate the hepatotoxicity by inhibiting mitochondrial fatty acid β-oxidation (Zimmerman et al., 1982; Gerber et al., 1979; Kassahun et al., 1991). Therefore it is important to monitor the plasma concentration of 4-ene-VPA and 2,4diene-VPA as well as VPA itself to evaluate effect and toxicity of VPA. In order to monitor plasma concentration of VPA and its toxic metabolites, it is necessary to have reliable and sensitive method for the simultaneous quantitative determination of those compounds. Because of structural similarity between fatty acid (non polar compound) and VPA, most of analytical method for VPA and/or its metabolite has been used GC-MS (gas chromatography-mass spectrometry) (Fisher et al., 1992; Yu et al., 1995; Leis et al., 2003). But those reports did not focus on the toxic metabolites, 4-ene-VPA and 2,4-diene-VPA, so it is very hard to evaluate pharmacokinetics of VPA and its toxic metabolites. Recently the method using HPLC-MS/MS (high performance liquid chromatography-tandem mass spectrometry) was reported to analyze VPA, however this method was developed only for the quantification of VPA and 4-eneVPA. Thus it is also not adequate to monitor plasma concentrations of VPA and its toxic metabolites (Cheng et al., 2007). Moreover, sample extraction with organic solvent was performed in the pH condition less than pH 3, which was not favorable condition for 4-ene-VPA and 2,4-diene-VPA since they could be degraded in acidic condition. In this study we developed adequate method for the quantitative analysis of VPA, 4-ene-VPA and 2,4-diene-VPA in rat plasma. We used mild pH condition to prevent degradation of the metabolites. This analytical method was validated and applied to evaluate pharmacokinetics of VPA and its metabolites after intravenous administration to rats. Corresponding Author : Tel : +82-2-958-5062, E-mail : jbhluck@kist.re.kr DOI : 10.4333/KPS.2010.40.3.155 156 Min Sun Lee, Young-Joo Lee, Bong Chul Chung and Byung Hwa Jung J. Pharm. Invest., Vol. 40, No. 3 (2010) Experimental

Biosorption of cadmium(II) from aqueous solutions by industrial fungus Rhizopus cohnii

An important filamentous industrial fungus, Rhizopus cohnii ( R. cohnii), was used as an efficient biosorbent for removing cadmium from wastewater. The sorption conditions, such as pH, the dose of biomass and the initial concentration of cadmium were examined. Two kinds of adsorption models were applied to simulate the biosorption data. The uptake of cadmium was higher in weak acid condition than in strong acid condition. Nearly no sorption of cadmium occurred when the pH value was lower than 2.0. Biosorption isothermal data could be well simulated by both Langmuir and Freundlich models. Langmuir simulation of the biosorption showed that the maximum uptake of cadmium was 40.5 mg/g (0.36 mmol/g) in the optimal conditions, which was higher than many other adsorbents, including biosorbents and activated carbon. In addition, the reusability results showed that after five times of sorption and desorption process, the sorption capacity of R. cohnii could still maintain nearly 80%, confirming its practical application in cadmium treatment. Fourier transform infrared spectrum revealed that carboxyl, amino and hydroxyl groups on biosorbent R. cohnii surface were responsible for the biosorption of cadmium.

Synthesis and characterisation of starch phosphates

Monostarch monophosphates with different phosphorus contents were prepared via reacting starch with a mixture of primary and secondary sodium phosphates under weak acidic conditions in a semi-dry process. For a structural characterisation of starch phosphates 31P NMR and FT Raman spectra were recorded. The degrees of substitution (DS P) of modified starch were determined using a standard wet chemistry method. By recording the FT Raman spectra of starch phosphates a characteristic band at ∼975 cm −1 was found whose intensity depends on the degree of phosphorylation of starch. The integrated areas of this C–O–P stretching vibration were plotted versus the degree of substitution DS P of starch phosphates obtained from standard photometric method. A strong linear correlation was derived which is suitable to determine the level of phosphorylation of starch phosphates with unknown DS P value by Raman spectroscopy as a rapid and non-destructive method.

Massive volcanic SO2 oxidation and sulphate aerosol deposition in Cenozoic North America

Volcanic eruptions release a large amount of sulphur dioxide (SO(2)) into the atmosphere. SO(2) is oxidized to sulphate and can subsequently form sulphate aerosol, which can affect the Earth's radiation balance, biologic productivity and high-altitude ozone concentrations, as is evident from recent volcanic eruptions. SO(2) oxidation can occur via several different pathways that depend on its flux and the atmospheric conditions. An investigation into how SO(2) is oxidized to sulphate-the oxidation product preserved in the rock record-can therefore shed light on past volcanic eruptions and atmospheric conditions. Here we use sulphur and triple oxygen isotope measurements of atmospheric sulphate extracted from tuffaceous deposits to investigate the specific oxidation pathways from which the sulphate was formed. We find that seven eruption-related sulphate aerosol deposition events have occurred during the mid-Cenozoic era (34 to 7 million years ago) in the northern High Plains, North America. Two extensively sampled ash beds display a similar sulphate mixing pattern that has two distinct atmospheric secondary sulphates. A three-dimensional atmospheric sulphur chemistry and transport model study reveals that the observed, isotopically discrete sulphates in sediments can be produced only in initially alkaline cloudwater that favours an ozone-dominated SO(2) oxidation pathway in the troposphere. Our finding suggests that, in contrast to the weakly acidic conditions today, cloudwater in the northern High Plains may frequently have been alkaline during the mid-Cenozoic era. We propose that atmospheric secondary sulphate preserved in continental deposits represents an unexploited geological archive for atmospheric SO(2) oxidation chemistry linked to volcanism and atmospheric conditions in the past.

Production of tetramethylpyrazine by batch culture of Bacillus subtilis with optimal pH control strategy

The effects of initial culture pH ranging from 5.0 to 7.5 on biomass content, precursor 3-hydroxy-2-butanone (HB) accumulation, and 2,3,5,6-tetramethylpyrazine (TTMP) formation by Bacillus subtilis CCTCC M 208157 were investigated in shake flask fermentation. Weak acidic conditions were found to favor cell growth and precursor HB accumulation, while TTMP could be synthesized more efficiently in conditions with initial pH towards neutrality. Batch bioprocess of TTMP fermentation by Bacillus subtilis CCTCC M 208157 at various controlled pH values ranging from 5.5 to 7.0 was then examined in 7.5-l fermentor. The results suggested that optimum pH for cell growth and precursor HB accumulation was 5.5 with maximum cell growth rate (Q (x)) and precursor HB accumulation rate (Q (HB)) of 0.833 g l(-1) h(-1) and 1.118 g l(-1) h(-1), respectively, while optimum pH for TTMP formation was 7.0 with maximum TTMP formation rate (Q (TTMP)) of 0.095 g l(-1) h(-1). A pH-shifted strategy was accordingly developed to improve TTMP production in bioreactor fermentation by shifting the culture pH from 5.5 to 7.0 after 48 h of cultivation. By applying the strategy, final TTMP concentration of 7.43 g l(-1) was obtained, being 22.2% greater than that of constant-pH fermentation.

The effects of vitamin C on ZnO crystal formation

We have studied the effects of L(+)-ascorbic acid (vitamin C) on the formation of ZnO crystals. We carried out a series of experiments under weak acidic to alkaline conditions. We obtained ZnO structures with various distinct morphologies by varying the concentration of vitamin C dissolved in the weak acidic and alkaline solutions. Under weak acidic conditions, if the concentration of added vitamin C exceeds 0.5 mM, mixed amorphous/crystalline vitamin C–ZnO (VitC–ZnO) nanostructures are obtained. We also found that the ZnO content of the VitC–ZnO nanostructures can be controlled by adjusting the concentration of vitamin C added to the reaction solution. On the basis of our results, we propose a mechanism for the formation of the various ZnO structures and VitC–ZnO nanostructures in the presence of vitamin C.

Synthesis and Properties Evaluation of Sodium Fatty Alcohol Polyoxyethylene Ether Sulfonate

Abstract Sodium salts of fatty alcohol polyoxyethylene ether sulfonates with different length of hydrophobic chain (CnE3SO3, n +; 14, 16, 18) were synthesized from sodium isethionate, then the structure was verified by IR. The temperature resistance, calcium-tolerant stability and salt tolerance were evaluated by pyrogenetic decomposition, phase separation and middle phase emulsion respectively. In addition the mixture of CnE3SO3 and heavy alkylbenzene sulfonate (HABS) was studied. The results showed that: (1) CnE3SO3 was very stable at 150°C especially in neutral, weak acid and weak alkaline conditions; (2) CnE3SO3 performed a good salt tolerance and have a rank of C18E3SO3 &gt; C16 E3SO3 &gt; C14E3SO3; (3) the calcium-tolerant stability of CnE3SO3 reached 8700 mg/L, 9500 mg/L and 10000 mg/L respectively; (4) CnE3SO3 was very good for improving the salt tolerance of mixture of CnE3SO3 and HABS. C18E3SO3 was the best in mixtures of Daqing crude oil/water containing C18E3SO3 and HABS in a ratio of ω(C18E3SO3):ω(HABS) = 3:7 and showed the strongest synergistic effect. The interfacial tension in the system Daqing crude oil/water reached a minimum in the order of 10–3 mN/m and was always below 10–2 mN/m for cNaCl from 0 to 15000 mg/L.

Hydrothermal Synthesis and Morphological Evolution of Mesoporous Titania−Silica

Mesoporous titania−silica (TiO2−SiO2) composites have been directly synthesized through a hydrothermal method in weak acidic conditions by using TiCl3 solution as a titanium source and triblock copolymer P123 (EO20PO70EO20) as a template with the assistance of zinc acetate. Characterizations by XRD, TEM, and N2 sorption measurements show that highly ordered mesostructured TiO2−SiO2 with the BET specific area of 882 m2/g was obtained with the Ti/Si molar ratio of 0.1. Morphology of the composites can be controlled by the incorporation of different amounts of titanium species. Highly curved shapes such as winding, worm-like, and wheat grain-like particles were obtained by this direct synthetic method. Acidity and zinc acetate concentration can also affect the morphology of the composites. UV−vis, FTIR and 29Si MAS NMR results display that titanium species exist both in the framework and extra-framework of the mesoporous SiO2. Wide angle XRD, Raman, and HRSEM results show that the outer surface of the SiO2 (probably Ti-doped) is decorated by round anatase nanocrystallites (probably Si-doped), whereas X-ray mapping results reveal that titanium species are highly dispersed on the final mesoporous composites. The formation mechanism of the mesophase was discussed based on characterization results. Photocatalytic results show that the TiO2−SiO2 composites prepared in this way have high catalytic activity in the photodegradation of isopropanol due to both framework and surface titanium species.

The synergetic effect between heavy oil components and emulsifier in heavy oil-in-water emulsion

Resin and asphaltene were extracted from Gudao and Liaohe heavy oil by using the adsorption chromatography. Toluene and n-dodecane were selected as model oil, sodium dodecylbenzene sulfonate was selected as emulsifier. The interfacial tension (IFT) was investigated without emulsifier and adding emulsifier, the effect of pH value on the interfacial tension was also investigated. The results show that the interaction between component and emulsifier lies on the interfacial activity of components, and the higher interfacial activity is, the stronger interaction is. And the influence of pH on IFT is great at acid and base conditions, but little at neutral condition. The synergetic effect between polar component and emulsifier is stronger in the neutral condition and weak acid and base conditions.

Evolution from hollow nanospheres to highly ordered FDU-12 induced by inorganic salts under weak acidic conditions

Sulfates have big influence on the structure and morphology of the mesoporous silicas synthesized under weak acidic conditions. The evolution from silica hollow nanospheres to doughnut-like nanoparticles, and to FDU-12 type mesoporous silicas with Fm 3 ¯ m symmetry can be induced by CuSO 4 during the condensation of TMOS around Pluronic F127 surfactant in weak acidic solution (pH = 3.25). It is noteworthy that doughnut-like nanoparticles can be obtained in the presence of lower amounts of CuSO 4. Similar to CuSO 4, other divalent sulfates, such as ZnSO 4, NiSO 4, and MgSO 4 can also induce the formation of Fm 3 ¯ m mesostructure. However, the presence of K 2SO 4 and Na 2SO 4 specially results in the formation of hollow nanospheres. Plausible mechanisms for the formation of FDU-12 and hollow nanospheres were also proposed.

Differences in functional properties and biochemical characteristics of congenetic rice proteins

Proteins in brown rice (BR), white rice (WR) and rice bran (RB) were extracted from the same paddy rice and investigated for their components, functional properties and chemical characteristics by SDS-PAGE methodology. BR and WR proteins possessed a poor solubility under weak acid conditions due to a high content of glutenin and richness in higher molecular-weight (MW) protein fractions. Rice bran protein contained significantly lower molecular-weight components (MWs < 50 kDa) than those in WR and BR. Nitrogen solubility, foaming and emulsification properties of their rice protein preparations were affected not only by pH (3–11), but also by the concentrations of NaCl (0.4–2.0%) and sucrose (4.0–20.0%). All of them, particularly rice bran protein, had favorable functional properties in the medium with a high salt or sugar concentration. Therefore, they have a good potential for development in the food industry.