CIELAB color coordinates versus relative proportions of myoglobin redox forms in the description of fresh meat appearance

This work examined changes in color that can be explained solely on the basis of the total myoglobin content and the relative proportions of deoxymyoglobin, oxymyoglobin (OMb) and metmyoglobin (MMb) during storage of meat. Meat color was evaluated for L*, a*, b*, C* and h_ab. Total pigment content was measured from the reflex attenuance at 525 nm (A₅₂₅). The relative proportions of each pigment was determined using two different methods: the Krzywicki method based on the reflex attenuance values at 473, 525, 572 and 700 nm and the KS method based on K/S ratios of the absorption and scattering coefficients (K/S)₄₇₄ ÷ (K/S)₅₂₅, (K/S)₅₇₂ ÷ (K/S)₅₂₅ and (K/S)₆₁₀ ÷ (K/S)₅₂₅. The study was performed on beef (Longissimus lumborum) samples measured after 1, 4 and 7 days of exposure to air. Result revealed that L* values can be fully explained by A₅₂₅ alone. C* and a* were well explained by those parameters related to OMb content. The other color parameters depended on pigment forms. The KS method gave better results. The parameters related to MMb content were relevant to classify samples according to the time of exposure to air. In any case, information provided by color and pigment parameters were complementary to each other.

Parámetros de color del jugo de granadilla (Passiflora edulis Sims): influencia de la época de cosecha de la fruta/ Color parameters of passion fruit juice (Passiflora edulis Sims): influence of harvest season

This study covers the evolution of color parameters (L*, a*, b*) of passion fruit juice from 2 different seasons (winter and summer) and its relation with carotenoid content and also the sensory evaluation of juices. Three different harvests were made during the two seasons, every 15-20 days. Soluble solids/acidity ratio was used as a maturity index. Winter maturity index was 3.5 and summer index was 6.6: The carotenoids content for winter fruit was higher than that for summer fruit (2.6 and 1.7 mg β-carotene/100ml respectively). Color differences between harvest seasons were observed; a* value for winter juices was higher than for summer juices (7.4 and 4.3 respectively). Furthermore, an increment of a* value was observed in the winter harvest rising from 5.0 to 10.3. A color difference was also detected through the sensory evaluation; the judges ranked the third harvest from winter with the highest degree. This sample had the highest carotenoid content (3.2 mg β-carotene/100 ml).

Influencia de la época de cosecha sobre las características de la granadilla morada (Passiflora edulis Sims) y su jugo/Influence of harvest season on the characteristics of purple passion fruit (Passiflora edulis Sims) and its juice

The effect of two different harvest seasons (winter and summer) on some characteristics of passion fruit and juice was studied. Three different harvests were made during the two seasons every 15-20 days. The soluble solids/acid ratio was used as a ripeness index. The weight, diameter, peel thickness and yield of juice and seeds were determined in the fruit. Soluble solids, pH, acidity, total and reduced sugars, starch, pectin and pectinesterase activity were determined in the juice. A sensory evaluation of the quality and intensity of aroma was made. Influence of the date of harvest on the technological characteristics of the fruit and juice were observed. Winter fruits showed higher weight, diameter and peel thickness and lower juice yield than those from the summer harvest. The juice from the summer harvest showed a higher content of soluble solids, less acidity, and a higher content in starch, pectin and sugars than that of the summer harvest. The sensory evaluation showed that the aroma of the juice from the summer harvest was better in intensity and quality than that of the winter fruit.

General expressions for the refractive indices of absorbing biaxial media as a function of the angle of incidence

In this work we obtain general expressions for the complex refractive indices of refracted waves as a function of the angle of incidence in the case of an electromagnetic wave propagating in a transparent isotropic medium that reaches an interface with a biaxial absorbing medium. The biaxial absorbing medium is only required to have a diagonalizable complex dielectric tensor. Obtained expressions can be applied to any orientation of the principal axes and can be specialized for isotropic, uniaxial or biaxial, or transparent or absorbing media. By using these expressions we have also obtained the surface of indices and the surface of absorption coefficients for an example of a biaxial absorbing medium.

Uniaxial absorbing media: conditions for refraction in the direction of the optical axis

When a plane wave is incident from an isotropic medium into a uniaxial transparent medium so that the ordinary wave propagates in the direction of the optical axis, the extraordinary wave will also propagate in the same direction and with the same refractive index. We will show that this is not the case when the second medium is a uniaxial absorbing material. In this work, we will state a clear and precise interpretation of the meaning of propagation in the direction of the optical axis in the case of uniaxial absorbing media. Assuming that the ordinary wave is refracted in the direction of the optical axis we will analyze the refraction of the extraordinary wave and we will compare it with the case of transparent media. The necessary conditions to have both ordinary and extraordinary waves refracted in the direction of the optical axis will be obtained.

Influence of absorption on the anomalous negative refraction in right-handed uniaxial absorbing dielectric media

In this work we study the anomalous negative refraction when a plane wave is incident from an isotropic medium to a uniaxial absorbing medium. We study the influence of the anisotropy on the refractive indices and the anisotropy on the absorption coefficients in the negative refraction of these materials. Negative refraction can occur for the ordinary and extraordinary waves for a wide range of values of the angle of incidence. The allowed values of the angle of incidence that lead to negative refraction are analyzed in detail as a function of the orientation of the optic axis and the values of the refractive indices and absorption coefficients.

Interface between transparent isotropic and uniaxial absorbing dielectric media: equations for ray tracing and for the direction of propagation

In this work we analyze the propagation of a plane wave that passes from an isotropic transparent medium to a uniaxial absorbing medium. Detailed expressions that give the real directions of propagation of the wave and the energy of the reflected and refracted ordinary and extraordinary waves are obtained. These expressions are valid for every orientation of the optic axis of the uniaxial medium and for every direction of propagation of the incident wave. Expressions are tested in the case of an interface between a transparent and an absorbing isotropic media and for the air-rutile (TiO2) interface. The effect of absorption has been evaluated by comparing the results obtained in rutile with the results obtained in a transparent uniaxial medium with the same real refractive indices. Results are presented for different values of the angle of incidence and the orientation of the plane of incidence.

Complex unitary vectors for the direction of propagation and for the polarization of electromagnetic waves in uniaxial and absorbing dielectric media

The propagation of inhomogeneous and elliptically polarized plane waves in absorbing uniaxial anisotropic media is described using complex unitary vectors to represent the direction of propagation and the direction of polarization. Detailed expressions for electric displacement, electric field, and magnetic field vectors are obtained for the ordinary and extraordinary waves, and their geometry is discussed. According to the complex direction of propagation, three particular cases are studied: the real case (homogeneous wave), the case perpendicular to the optical axis, and the case coplanar with the optic axis. The case of isotropic media is also analyzed.

Complex unitary vectors for the direction of propagation and for the polarization of electromagnetic waves in absorbing isotropic media

We introduce a formalism based on complex unitary vectors for the direction of propagation and for the polarization in order to describe in detail the propagation of inhomogeneous plane waves in absorbing isotropic media. We obtain analytic expressions for the displacement vector, the electric field, the magnetic field, and the Poynting vector, and we study their geometry in terms of the geometrical interpretation of the complex directions of propagation inside the material. We introduce a complex coordinate system based on complex unitary vectors, where the description of the polarization states of the field vectors and the Poynting vector becomes simpler. The physical meaning and the interpretation of the mathematical operations involving these complex unitary vectors is provided.

Analysis of airborne radon in an ultra-low background experiment

The contribution of 222Rn to the background in a low background experiment with a germanium detector has been estimated. We have also checked the efficacy of a standard radon cleaning system. The cleaning reduces the radon concentration two orders of magnitude with respect to the air in the laboratory. The residual 222Rn represents at most 12.5% of the background in the low energy region, a value low enough for the purpose of our experiment. A detailed study of the radioactive background is presented.

Risk factors for hepatotoxicity induced by antituberculosis drugs

To evaluate the risk factors involved in antituberculosis treatment-induced hepatotoxicity. In a retrospective study we analyzed the rate of drug-induced hepatotoxicity in a sample of 456 patients. Patients received a combination of drugs including isoniazid, rifampin, pirazinamide and streptomycin or ethambutol. The association among hepatotoxicity and several risk factors (age, sex, alcoholism and HIV infection) was studied by univariate methods, stratified analysis and the multiple logistic regression model. Signs of liver injury were found in 9.86% of the treated patients. In the logistic model, the adjusted odds ratios (OR) and significance were found as follows: a) for alcoholism, OR = 17.31 (95% CI: 6.35-47.16), p < 0.001; b) for HIV infection, OR = 3.23 (95% CI: 1.47-7.11), p = 0.003 and c) for female sex, OR = 2.44 (95% CI: 1.22-4.86), p = 0.011. Age was not significantly associated with hepatotoxicity. Alcoholism, HIV infection and female sex were associated with an increased risk of hepatotoxicity in this study.

Cactus pear fruit: a new source for a natural sweetner

The use of cactus pear (Opuntia ficus indica L.) to obtain a new natural liquid sweetener was studied. The juice of the fruit (16.5 degrees Brix) was clarified with enzymes, treated with active carbon to take out the color and vacuum concentrated to obtain a 60 degrees Brix syrup or liquid sweetener. Physical and chemical characteristics determined included: a(w); reducing sugars (as inverted sugar); glucose (%); ash content (%); sugar composition by TLC; OD (420 nm) and Y, x, y chromaticity coordinates; viscosity (cps) and density (g/ml). Sensory analyses to determine the relative sweetness were also conducted. Cactus pear syrup contained 52.38% reducing sugar. The syrup had a pH of 4.31, a viscosity of 27.05 cps, an Aw of 0.83, a density of 1.2900 g/ml, an acidity (as citric acid) of 0.74% and an ash content of 1.4%. Compared with traditional sweeteners such as fructose and glucose syrup, the acidity was greater than that of HFCS (high fructose corn syrup) of 0.035%, and the ash values were considered a little high compared to glucose syrup which is 1.0%; these disparities can be attributed to the different processing conditions employed. Sensory evaluation revealed the same relative sweetness for cactus pear syrup and glucose, but lower than fructose; cactus pear syrup had a relative sweetness value of 67 with respect to sucrose (100).

Rhinocerebral and systemic mucormycosis. Clinical experience with 36 cases

We analysed retrospectively our clinical experience with 36 cases of mucormycosis. They were seen during the last 15 years. The diagnosis suspected on clinical grounds, was confirmed in 31 cases by finding the hyphae in hematoxylin-eosin stained material obtained from aspirated or tissue biopsy or by isolation of the fungus in culture. Rhinocerebral mucormycosis was diagnosed in 22 patients. Diabetes was the underlying disorder in 20 cases, kidney failure in one and myelodysplastic syndrome in one. Nine had stable and 11 unstable diabetes (ketoacidosis in 10 and hyperosmolar coma in 1). The earliest sign was facial edema, followed by proptosis, chemosis and extraocular muscle paresis. They were treated by extensive surgical debridement, insulin and antifungal drugs with 69% of survival rate. The disseminated mucormycosis was diagnosed at the autopsy in 5 cases, acute leukemia was the underlying disease in 2 of them. Pulmonary mucormycosis was diagnosed in 2 cases, cutaneous form in 2, sinuorbital form in 4 and brain abscess in one patient. Eight of these 9 cases survived after therapy. We emphasize the importance of an early diagnosis. This can only be made in the presence of a typical clinical setting confirmed by finding the hyphae in tissue or culture. Antifungal drugs along with treatment of the underlying disorder and aggressive surgical debridement must follow.

Mucormycosis. Report of 11 cases

Mucormycosis is fulminant fungal infection that usually occurs in debilitated patients with an underlying pathologic condition. The common clinical types include rhinocerebral, pulmonary, disseminated, and intestinal forms. This report describes 11 cases seen in our institution since 1970. Of nine patients with underlying diabetes mellitus, eight developed rhinocerebral mucormycosis and one had the cutaneous form. Two additional patients with acute leukemia showed the disseminated and pulmonary forms of mucormycosis. In nine patients, the diagnosis was established by histologic appearance and by culture of infected tissue obtained by biopsy. In two patients the diagnosis was made during postmortem examination. Five patients survived. We have emphasized the importance of early diagnosis and prompt, appropriate medical and surgical therapy to obtain a significant survival rate in patients with this frequently fatal disease.