Microstructure and Optical Properties of ZnO-Doped CeO2 Thin Films Using Sol-Gel Method

This paper describes microstructure and optical characteristics of ZnO-doped CeO2thin films were deposited by sol-gel method with various preheating and annealing temperatures. Particular attention will be paid to the effects of an annealing treatment in air ambient on the physical properties. The deposited films were characterized using X-ray diffraction. The surface morphologies of annealed film were examined by scanning electron microscopy. Optical properties of the ZnO-doped CeO2thin films were obtained by UV-visible recording spectrophotometer. The dependence of the optical properties and microstructure characteristics on thermal treatment was also investigated.

Semiautomated Method for Determination of Serum Paraoxonase Activity Using Paraoxon as Substrate

Background: Serum paraoxonase (PON1) is an enzyme associated with HDL, and its ability to protect LDL from oxidation is one mechanism by which HDL protects against atherosclerosis. Low concentrations of PON1 are found in patients with type 2 diabetes or coronary heart disease. Serum PON1 activity may also be important in avoidance of organophosphate toxicity in industry. Methods: The generally accepted method for determining PON1 activity requires use of a recording spectrophotometer and is not suited to large numbers of samples; in addition, automation presents particular problems because of the extreme toxicity of substrates such as paraoxon. We established a relatively safe microtiter plate method that facilitates the determination of PON1 activity at a rate of 120 samples per hour. Results: PON1 activity was determined by the generally accepted method (x) and the new method (y); results correlated with a slope close to unity (y = 0.93x + 8; r = 0.97; P <0.0001; n = 101). Examination of differences by Bland–Altman plots showed a weak concentration-dependent difference (r = 0.33; P <0.0001; n = 101). The intra- and interassay sample CVs, obtained with samples with PON1 activities ranging from 41 to 348 nmol · min−1 · mL−1, were 3.5% and 2.7%, respectively (n = 16). Conclusion:The proposed method for determination of PON1 activity is simple, relatively safe, and inexpensive and is suitable for analysis of large numbers of samples.

Rounding error, an unexpected fault in the output from a recording spectrophotometer: implications for model discrimination

Although commonly ignored in discussions of experimental error, rounding may sometimes be the major source of error, especially with modern precision instruments: some recording spectrophotometers are optically and photometrically capable of making absorbance measurements with errors less than 0.0003, but provide no numerical information more precise than +/- 0.001. The problem may be diagnosed by a characteristic arrangement of points in a residual plot, which resembles the result of cutting a stroboscopic picture of a bouncing ball into several strips and modifying it by sliding the strips relative to one another to bring the points closer to the axis. Harmful effects of rounding error can be critical in experiments designed for model discrimination.

Psychophysical Relationship between Sweetness and Redness in Strawberry-Flavored Drinks

A consumer-like taste panel of 10 men and women, ages 22–50, evaluated the sweetness, pleasantness and color acceptability of five sweetened, strawberry-red colored beverages, containing 3.2% to 4.8% sucrose, using magnitude estimation. Five intensities of strawberry colors were formulated using increasing volumes of FD&C Red 40 and a constant volume of both FD&C Yellow 6 and imitation strawberry flavoring. Color measurements from the Gardner XL-23 colorimeter and the G. E. Recording Spectrophotometer were converted to L*, a*, b*. Sensory responses were evaluated against the value arctan (a*/b*), representing color intensity, and sucrose concentration, as percent sugar. Sweetness perception increased with increasing sucrose concentration, producing a slope greater than 2.00 (r2≥0.87) but produced an exponent less than 1.0 (r2<0.91) when evaluated against arctan (a*/b*). Sweetness increased approximately 2 to 12% with increasing color intensity in 4% sucrose solutions. Perceived sweetness was influenced by pleasantness effects and color acceptability. Color 3 samples were rated as the sweetest, most pleasant-tasting drinks and had the most acceptable color. The color-sweetness function was linear over a narrow color range.

Psychophysical Relationships Between Perceived Sweetness and Color in Cherry-Flavored Beverages

Sweetness of cherry-flavored and colored beverages, containing 3.2 to 4.8% sucrose, was quantified by a panel of 10 men and women, ages 22–50, using magnitude estimation. Five intensities of cherry colors were formulated using increasing volumes of Red 40 and a constant volume of both Blue 1 and imitation cherry flavoring. Color measurements from the Gardner XL-23 Colorimeter and the G. E. Recording Spectrophotometer were converted to L*, a* and b*. Sweetness was evaluated against sucrose concentration and arctan (a*/b*). Magnitude tests to evaluate color acceptability and pleasantness were also conducted. All magnitude estimates were normalized and subjected to a two-way ANOVA. Sweetness perception was highly correlated with increasing sucrose concentration (r2> .90), producing a power function exponent of 1.98. Sweetness increased approximately 3 to 13% with increasing color intensity in solutions containing 3.96 to 4.4% sucrose. The exponent describing the sweetness-color relationship was less than 1.0, and followed the power law over a narrow range of color intensities. Color 4 was the most acceptable color and color 3 containing 4.6% sucrose had the most pleasant taste. Color might be used to replace some sucrose and can optimize pleasurable taste sensations.

Enzymic determination of fructose in seminal plasma by initial rate analysis.

We describe a spectrophotometric assay for fructose in seminal plasma. The method is based on reduction of fructose by a commercially available preparation of sorbitol dehydrogenase (EC 1.1.1.14), with the concomitant oxidation of NADH. The initial rate of NADH oxidation, which is proportional to the fructose content of seminal plasma, can be measured either with a recording spectrophotometer or by conventional two-point kinetic assay. The method was as accurate, precise, and sensitive as, and more specific and rapid than, currently used colorimetric (resorcinol) methods for fructose determination. Values (mmol/L) for fructose in seminal plasma from several species are: man, 9 +/- 2 (SD); cynamolgus monkey (Macaca fasicicularis)., 108 +/- 19; bull, 30 +/- 1; and rabbit, 13 +/- 4. These values agree with previously published results. We believe the method is appropriate for both research and clinical use.

Quantitative Thin Layer Chromatographic Determination of Furazolidone and Nitrofurazone in Animal Feeds

A method is presented for determining the nitrofurans furazolidone and nitrofurazone in animal feeds. The sample is extracted with acetone, and aliquots of the concentrated extract are spotted on thin layer chromatographic fluorescent plates. After development in CHCl3-methanol (90+10), the bands containing the nitrofurans are detected under shortwave ultraviolet light, scraped from the plate, and extracted with ethanol. The centrifuged extracts are scanned from 500 to 300 nm on a recording spectrophotometer with a tungsten lamp, and the absorbance maxima near 360 nm are used for quantitation. To compensate for extraction and chromatographic losses and for other interferences, the nitrofuran not present in the sample is added as an internal standard. The method is generally not applicable at a level below 0.005% since detection of the bands becomes difficult.

Spectrophotometric Determination of Factor Xa Generation in Factor IX Concentrates

SummaryPrevious work from this department, concerned with testing the potential thrombogenicity of therapeutic factor IX concentrates, demonstrated that following recalcification of factor IX concentrates thrombin was generated within 3-30 minutes of incubation (Sas et al. 1975). The test developed (known as the TGt 50 test) is a two-stage assay and was thus found to be time consuming, tedious and tended to become inaccurate with long incubation periods and a large number of samples. A semiautomatic version of the test is reported in which the synthetic peptide Bz-ILE-GLU-GLY-ARG-pNA (S-2222) is added to recalcified, diluted factor IX concentrate in the micro-cuvette of a multiple sample recording spectrophotometer. Information can be obtained on (a) the amount of Xa (if any) present prior to recalcification (b) the initial amount of Xa formed and (c) the time taken to activate all factor X to Xa. Direct graphical interpretation shows a number of qualitative differences between commercial preparations, but by either of the criteria (b) or (c) above, it is possible to place the different products into “activated” and “non activated” groups such that both the Xa generation times and TGt 50 tests identify the same two groups of products. This agreement also indicates that the TGt 50 test is independent of the intrinsic factor V levels in the various concentrates.