Carry-through effect

Antioxidants should satisfy several requirements before being accepted for incorporation into food products.5 The antioxidant should be soluble in fats it should not impart a foreign colour, odour or flavour to the fat even on long storage it should be effective for a least one year at a temperature of between 25 and 30°C it should be stable to heat processing and protect the finished product (carry-through effect) it should be easy to incorporate and it should be effective at low concentrations. 

For food applications, synthetic antioxidants must be sufficiently active to be used at low concentrations (below 0.02%) and cannot be toxic. To be effective in foods, synthetic antioxidants must partition favorably between the oil-air interfaces in bulk oil systems, and between oil-water interfaces in emulsion systems (Chapter 10). Food antioxidants must also be stable to processing and cooking conditions. The term carry through effect refers to the ability of antioxidants to withstand the thermal treatments of frying or baking to be absorbed by the food and have sufficient activity to stabilize the fried or baked food. Compared to natural antioxidants, synthetic antioxidants are generally more effective and can be used at lower concentrations they are less expensive, can be prepared with consistent quality without effect on flavor, color and aroma of the final product. 

In order to be used as an antioxidant, a synthetic compound has to meet the following requirements it should not be toxic it has to be highly active at low concentrations (0.01-0.02%) it has to concentrate on the surface of the fat or oil phase. Therefore, strongly lipophilic antioxidants are particularly suitable (with low HLB values, e. g. BHA, BHT or tocopherols, dodecylgallate) for o/w emulsions. On the other hand, the more polar antioxidants, such as TBHQ and propyl gallate, are very active in fats and oils since they are enriched at the surface of fat and come in contact with air. Antioxidants should be stable under the usual food processing conditions. This stability is denoted as the carry through effect. Some of the synthetic antioxidants used worldwide are ... 

The ion transport number is defined as the fraction of current carried through the membrane by counterions. If the concentration of fixed charges in the membrane is high compared to the concentration of the ambient solution, then the mobile ions in the IX membrane are mosdy counterions, co-ions are effectively excluded, and the ion transport number then approaches 1. Commercial membranes have ion transport numbers in dilute solutions of ca 0.85—0.95. The relationship between ion transport number and current efficiency is shown in Figure 3 where is the fraction of current carried by the counterions (anions) through the AX membrane and is the fraction of current carried by the counterions (cations) through the CX membrane. The remainder of the current (1 — in the case of the AX membranes and (1 — in the case of the CX membranes is carried by co-ions and... 

The method using GC/MS with selected ion monitoring (SIM) in the electron ionization (El) mode can determine concentrations of alachlor, acetochlor, and metolachlor and other major corn herbicides in raw and finished surface water and groundwater samples. This GC/MS method eliminates interferences and provides similar sensitivity and superior specificity compared with conventional methods such as GC/ECD or GC/NPD, eliminating the need for a confirmatory method by collection of data on numerous ions simultaneously. If there are interferences with the quantitation ion, a confirmation ion is substituted for quantitation purposes. Deuterated analogs of each analyte may be used as internal standards, which compensate for matrix effects and allow for the correction of losses that occur during the analytical procedure. A known amount of the deuterium-labeled compound, which is an ideal internal standard because its chemical and physical properties are essentially identical with those of the unlabeled compound, is carried through the analytical procedure. SPE is required to concentrate the water samples before analysis to determine concentrations reliably at or below 0.05 qg (ppb) and to recover/extract the various analytes from the water samples into a suitable solvent for GC analysis. 

Fortunately, few of these variables are truly independent. Geochemists have developed a variety of numerical schemes to solve for equilibrium in multicomponent systems, each of which features a reduction in the number of independent variables carried through the calculation. The schemes are alike in that each solves sets of mass action and mass balance equations. They vary, however, in their choices of thermodynamic components and independent variables, and how effectively the number of independent variables has been reduced. 

Conductance of a solution is a measure of its ionic composition. When potentials are applied to a pair of electrodes, electrical charge can be carried through solutions by the ions and redox processes at the electrode surfaces. Direct currents will result in concentration polarization at the electrodes and may result in a significant change in the composition of the solution if allowed to exist for a significant amount of time. Conductance measurements are therefore made using alternating currents to avoid the polarization effects and reduce the effect of redox processes if they are reversible. 

The minimal basis calculation on the hydrogen molecule is a well-worn but eminently suitable example for our purposes. It has a convenient symmetry element and orbital basis calculations can be carried through which are quantitatively acceptable and yet not prohibitively unwiedly to report. We give below variational calculations on the H2 molecule using the familiar simplest AO basis in the one-electron-group (MO) model and the electron-pair (VB) model. These calculations have been performed explicitly to investigate the effect of symmetry constraints . 

ANP, BNP, CNP, and DNP are vasoactive agents that alter renal salt and water excretion through effects on vascular tone and cardiac output. Many clinical studies of these agents have been carried out, but there is still no consensus on precisely when they should be used and whether they have beneficial or even deleterious effects on renal function. Work that is in progress may answer these questions. 

Design and development are carried out through effective quality planning. Both products and services are considered, with particular reference to customer focus. 

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