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Abstract  

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to concurrently determine multiple long-lived (t1/2>104 y) actinide isotopes in soil leachates. Ultrasonic nebulization was found to maximize instrument sensitivity. Instrument detection limits for actinides in solution ranged from 50 mBq L–1 (239Pu) to 2Bq L–1 (235U). Hydride adducts of232Th and238U interfered with the determinations of233U and239Pu; thus, extraction chromatography was used to concentrate the analytes and separate uranium from the other actinides in advance of mass spectrometric determination. Alpha spectrometric determinations of230Th,239Pu, and the234U/238U activity ratio in soil leachates compared well with ICP-MS determinations; however, there were some small systematic differences (ca. 10%) between ICP-MS and -spectrometric determinations of234U and238U activities. These differences were attributed to the use of different isotope dilution spikes for ICP-MS and -spectrometry.

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Abstract  

An efficient analytical method for the determination of low-levels of226Ra and224Ra by alpha spectrometry is described. A cation exchange column was used to separate the analyte from other constituents in the sample (1–50 mL). After preconcentration and separation, the radium was electrodeposited onto a stainless steel disc from a solution of ammonium oxalate and hydrochloric acid. The electrodeposition was accomplished by the addition of platinum in microgram amounts. Linear responses were greater than two orders of magnitude. Detection limits of the procedure, taken as three times the standard deviation of several reagent blank analyses, were (1.8±0.3)×10–4 Bq and (2.9±0.3)×10–4 Bq for226Ra and224Ra, respectively. Recoveries of226Ra and224Ra ranged from 90% to 100% when samples of drinking water, well water, and dissolved bones were analyzed. Precision was calculated to be less than 5% for the determination of226Ra. Matrix effects were studied for salts of barium, magnesium, iron, and calcium.

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Abstract  

Liquid scintillation counting (LSC) is one of the most widely used methods for determining the activity of 241Pu. One of the main challenges of this counting method is the efficiency calibration of the system for the low beta energies of 241Pu (E max = 20.8 keV). In this paper we compare the two most frequently used methods, the CIEMAT/NIST efficiency tracing (CNET) method and the experimental quench correction curve method. Both methods proved to be reliable, and agree within their uncertainties, for the expected quenching conditions of the sources.

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Abstract  

Radioisotope X-ray fluorescence spectrometry, RIXRF, was used for the determination of vanadium in Venezuelan petroleum coke samples using a simple standardless method and fundamental parameter approach. The values obtained by this method were in agreement with values measured by graphite furnace atomic absorption spectrometry, GFAAS.

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Abstract  

Collection of uranium by salicyliden and glutariliden chitosans /Schiff's Bases/ was investigated to obtain information on uranium recovery from ores, especially carnotites. The collection of uranium by salicyliden /SDQ/ and glutariliden /GDQ/ chitosans was very rapid during the first 20 min and was affected by the pH of the solution, contact time and temperature. Uranium collected on SDQ and GDQ was easily eluted with diluted sodium bicarbonate solution. Also uranyl and vanadyl ions were separated from each other by using these biopolymers.

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Abstract  

Supercooling suppression of microencapsulated n-tetradecane was measured using differential scanning calorimetry. Results indicate that the degree of supercooling is positively affected by the amount and type of nucleating agent present in bulk and microencapsulated n-tetradecane which it is used as a phase change material (MPCM). Results also demonstrate that the melting point of the n-tetradecane is fairly independent of nucleating agent concentration (0 – 4%). Conversely, the latent heat of fusion of n-tetradecane decreases considerably with nucleating agent amount and the initiation of crystallization point is inversely proportional to cooling rate.

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Acta Alimentaria
Authors:
J. Montiel-Ventura
,
J.J. Luna-Guevara
,
M.A. Tornero-Campante
,
A. Delgado-Alvarado
, and
M.L. Luna-Guevara

The aim was to examine conditions of convective drying and spray-drying to improve preservation of lycopene content in tomatoes. The weight, size, colour, pH and °Brix values were evaluated in fresh fruit (FF) and colour (L, a, b), hue, and chrome indices were analysed from dried tomatoes, too. Tomato paste was dried (40, 50, 60, and 80 °C with times of 540, 390, 270, and 240 min) under convection conditions and pulverized. In the encapsulation treatments core material with tomato powders of 50, 60, and 70%, shell solution of maltodextrin/gum arabic 1:1, flow rate of 4, 6, 9, and 12 ml min–1, and inlet air T of 160, 170, and 180 °C were used. The physicochemical properties of FF corresponded to a degree of ripeness for consumption. The a, a/b, and hue values of dried tomatoes at 50 °C significantly correlated to red colouring and higher lycopene content (47.98±1.49 mg/100 g). The encapsulation with 50% and 60% of tomato powders, 170 °C and 9 ml min–1 treatments increased lycopene contents to 10.41 mg/100 g, 10.20 mg/100 g, and 11.51 mg/100 g, respectively. The results demonstrated that the physicochemical and functional properties were influenced by drying conditions, providing useful information for increasing the stability of lycopene in dried tomatoes.

Open access
European Journal of Microbiology and Immunology
Authors:
Dr. Cosme Alvarado-Esquivel
,
J. Hernández-Tinoco
,
L. F. Sánchez-Anguiano
,
A. Ramos-Nevárez
,
S. M. Cerrillo-Soto
,
L. Sáenz-Soto
, and
O. Liesenfeld

Abstract

Purpose:

The seroprevalence of infection with the parasite Toxoplasma gondii and the association with risk factors has not been determined in inmates. Through a case-control study, 166 inmates from a state correctional facility in Durango City, Mexico and 166 age- and gender-matched non-incarcerated subjects were examined for the presence of anti-T. gondii IgG and IgM antibodies using enzyme-linked immunoassays.

Results:

Seroprevalence of anti-T. gondii IgG antibodies was higher in inmates (35, 21.1%) than in controls (14, 8.4%) (OR = 2.90; 95% CI: 1.43–5.94; P = 0.001). Anti-T. gondii IgM antibodies were detected in two (1.2%) inmates and in seven (4.2%) controls (P = 0.17). Multivariate analysis of socio-demographic, incarceration, and behavioral characteristics of inmates revealed that T. gondii seropositivity was associated with being born out of Durango State (OR = 3.91; 95% CI: 1.29–11.79; P = 0.01). In addition, T. gondii seroprevalence was higher (P = 0.03) in inmates that had suffered from injuries (17/56: 30.4%) than those without such history (18/110: 16.4%).

Conclusions:

The seroprevalence of T. gondii infection in inmates in Durango City is higher than the seroprevalences found in the general population in the same city, indicating that inmates may represent a new risk group for T. gondii infection. Further research on T. gondii infection in inmates is needed.

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European Journal of Microbiology and Immunology
Authors:
Dr. Cosme Alvarado-Esquivel
,
S. J. Pacheco-Vega
,
J. Hernández-Tinoco
,
M. M. Centeno-Tinoco
,
I. Beristain-García
,
L. F. Sánchez-Anguiano
,
O. Liesenfeld
,
E. Rábago-Sánchez
, and
L. O. Berumen-Segovia

Abstract

Through a cross-sectional study design, 326 women with a history of miscarriage were examined for anti-Toxoplasma gondii IgG and IgM antibodies in Durango City, Mexico. Prevalence association with sociodemographic, clinical, and behavioral characteristics in women with miscarriage was also investigated.

Twenty-two (6.7%) of the 326 women studied had anti-T. gondii IgG antibodies and two (0.6%) were also positive for anti-T. gondii IgM antibodies. Seroprevalence of T. gondii infection was not influenced by age, birth place, occupation, educational level, or socioeconomic status. In contrast, logistic regression showed that T. gondii exposure was associated with consumption of raw or undercooked meat (OR = 6.84; 95% CI: 1.04–44.95; P = 0.04) and consumption of chicken brains (OR = 18.48; 95% CI: 1.26–269.43; P = 0.03).

This is the first study on the seroepidemiology of T. gondii infection in women with a history of miscarriage in Northern Mexico. Of interest, we also observed an association of T. gondii exposure with consumption of chicken brains. Contributing factors for T. gondii exposure found in the present study should be taken into consideration for public health measures to avoid infection with T. gondii and its sequelae.

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European Journal of Microbiology and Immunology
Authors:
C. Alvarado-Esquivel
,
S. J. Pacheco-Vega
,
M. Salcedo-Jaquez
,
L. F. Sánchez-Anguiano
,
J. Hernández-Tinoco
,
E. Rábago-Sánchez
,
M. M. Centeno-Tinoco
,
I. D. Flores-Garcia
,
A. Ramos-Nevarez
,
S. M. Cerrillo-Soto
,
C. A. Guido-Arreola
,
I. Beristain-García
,
O. Liesenfeld
,
L. O. Berumen-Segovia
,
L. Saenz-Soto
, and
A. Sifuentes-Álvarez

Through a cross-sectional study design, 150 women attending public health centers with a history of stillbirths were examined for anti-Toxoplasma gondii IgG and IgM antibodies in Durango City, Mexico. Bivariate and multivariate analyses were used to assess the association of T. gondii seropositivity with the characteristics of the women with stillbirth history.

Of the 150 women (mean age: 32.09 ± 9.16 years) studied, 14 (9.3%) had anti-T. gondii IgG antibodies and six (42.9%) of them were also positive for anti-T. gondii IgM antibodies. Multivariate analysis showed that T. gondii seropositivity was associated with high frequency (4–7 days a week) of eating meat (OR = 5.52; 95% CI: 1.48–20.59; P = 0.01), history of lymphadenopathy (OR = 4.52; 95% CI: 1.14–17.82; P = 0.03), and history of surgery (OR = 8.68; 95% CI: 1.04–72.15; P = 0.04).

This is the first study on the seroepidemiology of T. gondii infection in women with a history of stillbirths in Mexico. The association of T. gondii exposure with a history of surgery warrants for further research. Risk factors for T. gondii infection found in the present survey may help to design optimal educational programs to avoid T. gondii infection.

Open access