Assembly of a water-insoluble strontium metal–organic framework with luminescent properties

A new strontium metal–organic framework, [Sr₂(BTEC)(H₂O)₄]?2H₂O (1) (H₄BTEC = benzene-1,2,4,5-tetracarboxylic acid), has been successfully synthesized by mixing the starting reagents. The single-crystal structure analysis showed that compound 1 displayed three-dimensional structures containing inorganic motifs with two-dimensional layers pillar-connected through organic linkers and forming water-coordinated neutral framework. Further studies revealed that compound 1 was insoluble in water and that it emitted strong luminescence at approximately 437 nm after dehydration.     

Thermodynamic Model for Prediction of Phase Equilibria of Clathrate Hydrates in the Presence of Water-Insoluble Organic Compounds

A thermodynamic model for the prediction of pressure–temperature phase diagrams of structures II and H clathrate hydrates of methane, carbon dioxide, or hydrogen sulfide in the presence of “water-insoluble” organic componds is presented. The model is based on the equality of water fugacity in the aqueous and hydrate phases. The solid solution theory of van der Waals–Platteeuw (vdW–P) is used for calculation of the fugacity of water in the hydrate phase. The Peng–Robinson (PR) equation of state (EoS) is employed to calculate the fugacity of the components in the gas phase. It is assumed that the gas phase is water and promoter free and the organic compounds do not have marked effects on water activity in the aqueous phase. The results of this model are compared to existing experimental data from the literature. Acceptable agreement is found between the model predictions and the investigated experimental data.     

Insoluble fiber-rich fractions derived from Averrhoa carambola: hypoglycemic effects determined by in vitro methods

The hypoglycemic effects of several insoluble fiber-rich fractions (FRFs) including insoluble dietary fiber, alcohol-insoluble solid, and water-insoluble solid isolated from the pomace of Averrhoa carambola were investigated by some in vitro methods. This study evidenced that these three insoluble FRFs could effectively adsorb glucose, retard glucose diffusion, postpone the release of glucose from starch, and inhibit the activity of α-amylase to different extents. All of these mechanisms might create a concerted function in lowering the rate of glucose absorption and as a result decrease the postprandial serum glucose concentration. Our results revealed that the hypoglycemic effects of these insoluble FRFs were significantly (P<0.05) stronger than that of cellulose. Therefore, it was suggested that they could be incorporated as low-calorie bulk ingredients in high-fiber foods to reduce calorie level and help control blood glucose concentration.     

Mechanism of removing chlorophenolic compounds from solution by a water-insoluble cationic starch

The removal of three chlorophenolic compounds from solutions using highly crosslinked cationic starch containing a tertiary amine group was investigated. The three chlorophenolic compounds were 2-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. The adsorption process predominated over the initial pH = 2∼6 for 2-chlorophenol, and predominated over the initial pH = 2 to 4 range for 2,4-dichlorophenol and 2,4,6-trichlorophenol. The ion-exchange process predominated at initial pH = 12 for 2-chlorophenol, and predominated over the initial pH = 10 to 12 range for 2,4-dichlorophenol and 2,4,6-trichlorophenol. Both processes coexist over the initial pH=8 to 10 range for 2-chlorophenol, and coexist over the initial pH = 6∼8 for 2,4-dichlorophenol and 2,4,6-trichlorophenol. Experimental results indicate that the adsorption process is initially pH-independent, and the ion-exchange process is initially pH-dependent. The adsorption and ion-exchange processes are concentration-dependent and correspond to the Langmuir isothermal adsorption. They are endothermic for 2-chlorophenol and 2,4-chlorophenol, and are exothermic for 2,4,6-chlorophenol. The ion-exchange capacity is larger than the adsorption capacity. Moreover, the order of the amount of three chlorophenolic compounds removed by the cationic starch is 2,4,6-chlorophenol > 2,4-dichlorophenol > 2-chlorophenol.     

Preparation and antibacterial character of a water-insoluble antibacterial material of grafting polyvinylpyridinium on silica gel

Micron-sized silica gel particles were modified with the coupling agent of 3-methacryloylpropyl trimethoxysilane (MPS), then the copolymer of 4-vinyl pyridine and acrylamide (P (4VP-co-AM), PVA) was grafted onto the surface of modified silica gel particles by adopting the “grafting from” way, and the grafted particles PVA/SiO₂ were obtained. Finally, PVA on the particles PVA/SiO₂ were quaternarized by using benzyl chloride or dimethyl sulfate as quaternization reagents, and a kind of water-insoluble antibacterial material QPVA/SiO₂ with pyridinium-type was prepared. In this paper, the antibacterial property of QPVA/SiO₂ was mainly investigated by using Escherichia coli (E. coli) as model bacterium and by the colony count method, the effects of the grafting degree of pyridinium and the variety of quaternization reagents on the antibacterial property of QPVA/SiO₂were examined, and the antibacterial mechanism of QPVA/SiO₂ was explored using the method of measuring the activities of β-d-galactosidase and TTC-dehydrogenase. The experiment results show that QPVA/SiO₂ possesses strong antibacterial ability, and the antibacterial ratio of QPVA/SiO₂ with 2.3 mmol/g of grafting degree of pyridinium can reach 100% for bacterium suspension of 10⁹ CFU/mL with the dosage of 20 g/L and for 10 min of contact time. The greater the grafting degree of pyridinium is, the stronger the antibacterial ability, and the antibacterial property of the QPVA/SiO₂ prepared using benzyl chloride as quaternization reagent is stronger than that of the QPVA/SiO₂ prepared using dimethyl sulfate. The experimental results of two kinds of enzyme activity measurements reveal that the antibacterial effect of QPVA/SiO₂ is based on a sterilization process and not only based on a restraining action.     

Comparison of the characteristics, functional properties, and in vitro hypoglycemic effects of various carrot insoluble fiber-rich fractions

Fiber-rich fractions (FRFs) including insoluble dietary fiber (IDF), alcohol-insoluble solid (AIS), and water-insoluble solid (WIS) were isolated from carrot pomace via different methods. This study revealed that carrot pomace was rich in insoluble FRFs (50.1-67.4 g/100 g), which were mainly composed of pectic polysaccharides, hemicellulose, and cellulose. These insoluble FRFs, especially WIS, were found to have significantly (P<0.05) higher functional properties, glucose-adsorption capacity, and amylase-inhibition activity than those of cellulose. The ability of these FRFs to adsorb glucose and reduce amylase activity implied that they might help control post-prandial serum glucose level. Moreover, it was shown that the yield, composition, functional properties, and in vitro hypoglycemic effects among the three FRFs would be affected by their preparation methods. Our results recommended the consumption of these insoluble FRFs, especially WIS, as sources of food fibers or low calorie bulk ingredients in food applications requiring oil and moisture retention.     

Preparation of novel bio-matrix by the complexation of DNA and metal ions

Large amounts of DNA-enriched biomaterials, such as salmon milts and shellfish gonads, are discarded as industrial waste around the world. We could convert the discarded DNA into a novel bio-matrix by the hybridization of DNA and metal ions, such as Al³⁺, Cr³⁺, Fe²⁺, Fe³⁺, Cu⁺, Cu²⁺, Zn²⁺, and Cd²⁺. These water-insoluble DNA-metal ion matrices could be created in various desirable forms, such as a gel, capsule, film, or fiber. DNA-Al³⁺ matrices were found to maintain a B-form DNA structure, which was the native double-stranded DNA structure in water. The DNA-Al³⁺ fiber showed flexibility with the molecular orientation in the direction of drawing. When a DNA-Cu²⁺ matrix was incubated in an aqueous hydroquinone or ascorbic acid solution, benzoquinone or dehydroascorbic acid was produced, respectively, by the oxidative effect of Cu²⁺ in the DNA-metal ion matrix. These results suggest that metal ions in the DNA-metal matrix maintained the oxidative function. The water-insoluble DNA-metal ion matrices may have a potential utility as a functional bio-material, such as an antibacterial, oxidative, bio-sensor, and ion conductive materials.     

Phase behavior of water-insoluble simvastatin drug in supercritical mixtures of chlorodifluoromethane and carbon dioxide

Phase behavior data are presented for simvastatin, a water-insoluble drug, in supercritical solvent mixtures of chlorodifluoromethane (CHClF₂) and carbon dioxide (CO₂). The solubilities of the simvastatin drug in the solvent mixtures of CHClF₂ and CO₂ were determined by measuring the cloud point pressures using a variable-volume view cell apparatus as functions of temperature, solvent composition, and amount of the drug loaded into the solution. The cloud point pressure increased with increasing the system temperature. As the CHClF₂ composition in the solvent mixture increased, the cloud point pressure at a fixed temperature decreased. Addition of CHClF₂ to CO₂ caused an increase of the dissolving power of the mixed solvent for the simvastatin drug due to the increase of the solvent polarity. CHClF₂ acted as a solvent for simvastatin, while CO₂ acted as an anti-solvent. The cloud point pressure increased as the amount of the simvastatin drug in the solvent mixture increased. Consequently, the solubility of the simvastatin drug in the solvent mixture of CHClF₂ and CO₂ decreased with increasing the CO₂ content in the solvent mixture as well as with increasing the system temperature.     

The interaction between water-insoluble pentosan and gluten of the whole wheat

The water-insoluble pentosan (WIP) and gluten were extracted, and the interactions of WIP and gluten at different water level and ionic strength were measured by small amplitude oscillation tests and atomic force microscopy (AFM), and visualized by scanning electron micrographs (SEM). The results showed that the viscoelasticity of gluten and gluten-WIP mixtures greatly increased with the increase of water level, and decreased when water level was higher than 50%. The WIP significantly (p < 0.0001) improves viscoelasticity of gluten. The G′ and G″ of gluten and gluten-WIP mixtures were significantly (p < 0.0001) increased with the increase of NaCl concentration, and reached maximum when NaCl concentration was 4.0%. The SEM observations showed that the network of gluten-WIP mixtures was homogeneous and rather dense with a regular structure compared with that of gluten. From AFM detection, it was found that the single-molecule bond rupture force between the WIP and gluten proteins was strengthened with the increase of NaCl concentration, which can partly explain the rheological property and microstructure changes of WIP-gluten mixtures.