The electropolymerization of pyrrole at a CuNi electrode: corrosion protection properties

Pyrrole was successfully electropolymerized at a copper–nickel electrode in a near-neutral sodium oxalate solution containing Cu²⁺ cations to generate a homogenous and adherent polypyrrole film. The presence of the Cu²⁺ ions increased both the rate of the electropolymerization reaction and the adherence of the polymer at the CuNi interface. In the absence of these cations, oxidation of the electrode occurred generating a nickel-rich layer that was not sufficiently conducting, under the electropolymerization conditions employed, to facilitate the electron-transfer reaction and the electropolymerization of pyrrole.These films remained stable and exhibited significant corrosion protection properties in acidified and neutral 0.1 mol dm⁻³ NaCl solutions even on polarization of the electrodes to high anodic potentials.     

Carbamazepine/betaCD/HPMC solid dispersions. I. Influence of the spray-drying process and betaCD/HPMC on the drug dissolution profile

The aim of this study was to compare carbamazepine (CBZ) solid dispersions prepared by spray-drying of aqueous dispersions with the corresponding physical mixtures. The influence of the association of β-cyclodextrin (βCD) and hydroxypropyl methylcellulose (HPMC) on the CBZ dissolution profile of the preparations was investigated. Results demonstrated that CBZ release from solid dispersions is dependent on the ratio of βCD and HPMC. The spray-drying process confers better homogeneity to CBZ polymeric dispersions than the physical mixture process. In summary, we demonstrated the feasibility of obtaining a homogeneous polymeric solid dispersion of CBZ from an aqueous media by spray-drying and a clear influence of the βCD:HPMC ratio on the release profile of CBZ.     

Dispersion characteristics of ring line through the conformal mapping approach

Dispersion characteristics of EH/sub 11/ and EH/sub 21/ modes in open ring lines are theoretically calculated using conformal mapping applied to a three dimensional problem. The validity of the solution is tested by comparison with experimental data.<>     

The effect of fat content on the microbiology and proteolysis in cheddar cheese during ripening dairy foods

We investigated the effect of incremental reduction in fat content, in the range 33 to 6% (wt/wt), on changes in the microbiology and proteolysis of Cheddar cheese, over a 225-d ripening period at 7 degrees C. A reduction of fat content resulted in significant increases in contents of moisture and protein and a decrease in the concentration of moisture in nonfat substance. Reduced fat had little effect on the age-related changes in the population of starter cells. The populations of nonstarter lactic acid bacteria decreased with fat content, and counts in the low fat cheese (6% wt/wt) were significantly lower than those in the full fat cheese (33% wt/wt) at ripening times >1 and <180 d. Proteolysis as measured by the percentage of total N soluble at pH 4.6 or in 70% ethanol decreased significantly as the fat content decreased. However, the content of pH 4.6 soluble N per 100 g of cheese was not significantly influenced by fat content. At ripening times >60 d, the content of 70% ethanol soluble N per 100 g of full fat (33% wt/wt) cheese was significantly lower than that in either the half fat (17% wt/wt) or low fat (6% wt/wt) cheeses. The concentration of AA N, as a percentage of total N, was not significantly affected by fat content. However, when expressed as a percentage of total cheese, amino acid N increased significantly with decreasing fat content. Analysis of pH 4.6 soluble N extracts by reverse phase- and gel permeation HPLC revealed that fat content affected the pattern of proteolysis, as reflected by the differences in peptide profiles.     

Thermal stability of soy protein isolate and hydrolysate ingredients

The objective of this study was to characterize the effects of pH, protein concentration and calcium supplementation on thermal stability, at 140 °C, of soy protein isolate (SPI) and soy protein hydrolysate (SPH) ingredients. Increasing pH between 6.4 and 7.5 led to significantly (p < 0.05) higher mean heat coagulation times (HCTs) at 140 °C, for all soy protein ingredients at 1.8, and 3.6% (w/v) protein. Increasing protein concentration from 1.8 to 7.2% (w/v) led to shorter HCTs for protein dispersions. Calcium supplementation up to 850 mg/L, except in the case of supplementation of SPI 1 with calcium citrate (CaCit), decreased HCT for soy protein ingredient dispersions, at pH 6.4 – 7.5. No significant differences (p < 0.05) were found in mean HCT for dispersions supplemented with calcium chloride (CaCl₂) and those supplemented with CaCit at 450, 650 and 850 mg/L Ca²⁺, in the pH range 6.4–7.5.     

Outdoor grazing of dairy cows on pasture versus indoor feeding on total mixed ration: Effects on gross composition and mineral content of milk during lactation

The influence of feeding system and lactation period on the gross composition, macroelements (Ca, P, Mg, and Na), and trace elements (Zn, Fe, Cu, Mo, Mn, Se, and Co) of bovine milk was investigated. The feeding systems included outdoor grazing on perennial ryegrass pasture (GRO), outdoor grazing on perennial ryegrass and white clover pasture (GRC), and indoors offered total mixed ration (TMR). Sixty spring-calving Holstein Friesian dairy cows were assigned to 3 herds, each consisting of 20 cows, and balanced with respect to parity, calving date, and pre-experimental milk yield and milk solids yield. The herds were allocated to 1 of the 3 feeding systems from February to November. Milk samples were collected on 10 occasions over the period June 17 to November 26, at 2 or 3 weekly intervals, when cows were on average 119 to 281 d in lactation (DIL). The total lactation period was arbitrarily sub-divided into 2 lactation periods based on DIL, namely mid lactation, June 17 to September 9 when cows were 119 to 203 DIL; and late lactation, September 22 to November 26 when cows were 216 to 281 DIL. With the exception of Mg, Na, Fe, Mo, and Co, all other variables were affected by feeding system. The GRO milk had the highest mean concentrations of total solids, total protein, casein, Ca, and P. The TMR milk had the highest concentrations of lactose, Cu, and Se, and lowest level of total protein. The GRC milk had levels of lactose, Zn, and Cu similar to those of GRO milk, and concentrations of TS, Ca, and P similar to those of TMR milk. Lactation period affected all variables, apart from the concentrations of Fe, Cu, Mn, and Se. On average, the proportion (%) of total Ca, P, Zn, Mn, or Se that sedimented with the casein on high-speed ultracentrifugation at 100,000 × g was ≥60%, whereas that of Na, Mg, or Mo was ≤45% total. The results demonstrate how the gross composition and elemental composition of milk can be affected by different feeding systems.     

A New Simplified and Stability Indicating Liquid Chromatography Method for Routine Analysis of Isoflavones Aglycones in Different Complex Matrices

In this work, a stability indicating method for routine analysis of isoflavones in different matrices was developed and validated. In order to simplify the analytical method, the glycosides were previously hydrolyzed to the corresponding aglycone forms. The separation of all isoflavone aglycones was achieved in 23 min, with a total time of analysis of 30 min, using trifluoroacetic acid 0.1 % (v/v) and acetonitrile:trifluoroacetic acid (100:0.01, v/v) as mobile phase. The LC method specificity was evaluated by the analysis of isoflavone standards submitted to acidic, alkali, neutral, oxidative, and photolytic stress conditions. The isoflavones degraded in alkali at 60 °C or in alkali under ulraviolet C (UVC) radiation, forming, in both conditions, three degradation products D1, D2, and D3 which were analyzed by liquid chromatography mass spectroscopy (LC-MS/MS). The method showed linearity higher than 0.999 with the concentration ranged from 0.1 to 10 μg ml^-1 for all isoflavone aglycones. The limits of quantitation obtained using calibration curves were from 0.28 to 0.37 μg ml^-1 and the intermediary precision at three levels (2, 6, and 10 μg ml^-1) showed RSD values between 0.03 and 0.25 %. After the performed validation, the LC method was applied to compare the isoflavone aglycones content in three different matrices: Glycine max beans, Glycine max dry extract, and isoflavone aglycone loaded nanoemulsion. The repeatability data showed RSD values between 0.02 and 1.41 % and the intermediary precision at three levels showed RSD values between 0.05 and 1.99 %. The recovery data of the isoflavone aglycones standards in the matrices at three levels were between 90.74 and 106.43 %.     

Effects of Processing on Wheat Tortilla Quality: Benefits of Hard White Wheat

Hard white wheat was established as a new wheat class by Grain Inspection, Packers and Stockyards Administra- tion in 1990. Originally supplying a domestic niche market, several states, Kansas in particular, have steadily increased production and investme…