Search Results

You are looking at 1 - 6 of 6 items for

  • Author or Editor: A. Hernández-Martínez x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Both poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) were radiation grafted onto polypropylene films (PP) using gamma radiation from a 60Co source. PP was pre-irradiated by gamma ray for modification following by grafted PDMAEMA and PEGMEMA by a one step method. Grafting was studied as a function of the pre-irradiation dose between 20 and 180 kGy, dose rate of 10.4 kGy/h, and monomer concentration 50% of PDMAEMA/PEGMEMA (1/1) in different solvents (toluene, acetone, and methanol). FTIR-ATR, TGA, and DSC were carried out in the characterization of the graft copolymer obtained. Stimuli-responsive behavior and critical pH point were studied by swelling in water. pH and thermo-responsive films of PE-g-(DMAEMA/PEGMEMA) presented a lower critical solution temperature (LCST) of 50 °C and critical pH point around 8.7.

Restricted access
Reaction Kinetics, Mechanisms and Catalysis
Authors:
A. Martínez-de la Cruz
,
D. B. Hernández-Uresti
,
Leticia M. Torres-Martínez
, and
S. W. Lee

Abstract

PbMoO4 oxide with scheelite structure was obtained by hydrothermal synthesis in the absence of additives. The material was characterized by X-ray powder diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and adsorption–desorption N2 isotherms. The organic dyes rhodamine B (rhB), indigo carmine (IC), orange G (OG), and methyl orange (MO) were selected as molecules model to study its photocatalytic degradation over PbMoO4 oxide under UV irradiation. Total organic carbon analysis of samples irradiated revealed that mineralization of organic dyes by the action of PbMoO4 was feasible in 80 % (rhB), 69 % (IC), 71 % (MO), and 65 % (OG) after 96 h of UV irradiation.

Restricted access
Acta Phytopathologica et Entomologica Hungarica
Authors:
J. Hernández
,
P. Díaz-Vivancos
,
M. Rubio
,
E. Olmos
,
M. Clemente
,
A. Ros-Barceló
, and
P. Martínez-Gómez

The effect of Plum pox virus (PPV) infection on the response of some antioxidant enzymes was studied in Prunus species showing different susceptibility to PPV. PPV infection produced changes in the antioxidant systems from the Prunus species at subcellular level. In general, in PPV susceptible plants, the infection produced a decrease in some antioxidant enzymes, mainly in chloroplasts. However, in peach cv GF305 (PPV-susceptible) also an increase in class I APX in the three compartments studied as well as an increase in POX took place. In contrast, the PPV-resistant plants showed a general increase of antioxidant enzymes in soluble, chloroplast and apoplastic fractions. Long-term PPV infection produced an oxidative stress only in susceptible plants, as observed by the increase in leaf lipid peroxidation, protein oxidation and electrolyte leakage as well as in apoplastic H 2 O 2 . This H 2 O 2 increase was much higher in the PPV-susceptible than in the PPV-resistant plants. In peach, the increase in apoplastic H 2 O 2 correlated with the rise in NADH-POX and PPO activities. However, in apricot leaves, no increases in apoplastic NADH-POX were observed, and the increases in apoplastic H 2 O 2 correlated with increase in PPO activity in both cv. Real Fino (100%) and cv. SEO (40%), where a rise in SOD was detected, too. The specific inhibitor of NADPH oxidase, diphenylene iodonium (DPI), had only small effects on NADH oxidation, whereas it was inhibited almost completely by 1 mM KCN. Therefore, most of the NADH oxidation in the apoplastic space of Prunus species is due to NADH-POX and not NAD(P)H oxidase. In previous studies and by means of 2D electrophoresis, we showed that PPV infection produced the induction of a thaumatin-like protein as well as the decrease of mandelonitrile lyase (MDL) in peach apoplast. Mandelonitrile lyase catalyses the breakdown of mandelonitrile into benzaldehyde and cyanide. Benzaldehyde can be oxidised easily in vivo to produce benzoic acid, the precursor of salicylic acid. It was suggested that decreased MDL activity may result in a decreased SA biosynthesis in PPV-infected peach plants. It is also possible that a decline in antioxidant enzymes and an increase in ROS could be necessary for the establishment of infection and the replication and spread of some plant viruses, in agreement with results described by other authors. Results suggest that the higher antioxidant capacity showed by resistant SEO plants in comparison to PPV-susceptible plants could be associated, among other factors with their resistance to PPV.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
J. Santana Romero
,
F. Martínez Luzardo
,
E. Codorniú Hernández
,
L. Vargas Guerra
,
P. Melo Cala
,
M. García Guillén
,
K. Isaac Olivé
,
P. Estevez
,
A. Roque Córdoba
, and
M. Benítez

Abstract  

Vegetable tannins are polyphenolic plants secondary metabolites, widely distributed in all parts of trees and herbs. The role of these substances in many metabolic processes is very important. Vegetable tannins have been implicated as probable antinutritional factors, decreasing the assimilation of diet protein assimilation by cattle. On the other hand, protective antioxidant and antimutagenic properties have been ascribed for these compounds. Characterization of vegetable tannins is important in order to find new sources of natural raw materials with medical and pharmaceutical applications. Protein precipitation capacity as a function of pH, competitive protein and ADN binding assays and the determination of tannins concentration are described. Radioisotope labeled protein and tannins were used in all of the determinations.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
A. Perera
,
C. Perez
,
M. Torres
,
A. Henandez
,
F. Heres
,
T. Moreira
,
A. Gutierrez
,
A. Gigato
,
I. Hernandez
,
L. Alberti
,
O. Marrero
,
L. Martinez
,
J. Sanfiz
,
E. Sanchez
,
J. Rodriguez
,
L. Marrero
, and
G. Parra

Abstract  

The aim of this work was to obtain a freeze-dried kit for direct99mTc-labeling of human polyclonal IgG. The labeling procedure was carried out by Schwarz's method. The best yields of99mTc-IgG were obtained by using sodium pyrophosphate decahydrate as a weak chelating agent. Performed tests showed the stability of the radiopharmaceutical up to 24 hours. Plasma clearance in rats was fitted to a biexponential curve withT 1/2α=(0.1 ±0.9) h andT 1/2β=(10±3) h. The organs with higher uptake of radiopharmaceutical were lung, kidneys and blood. In a rabbit model the abscess target/background ratio was 3–6 according to time of the scintigraphic images. Thirty patients with musculoskeletal infection were studied. Twenty-one lesions were detected and confirmed by culture/biopsy.

Restricted access
Journal of Behavioral Addictions
Authors:
Guilherme Borges
,
Ricardo Orozco
,
Corina Benjet
,
Kalina I. Martínez Martínez
,
Eunice Vargas Contreras
,
Ana Lucia Jiménez Pérez
,
Alvaro Julio Peláez Cedrés
,
Praxedis Cristina Hernández Uribe
,
María Anabell Covarrubias Díaz Couder
,
Raúl A. Gutierrez-Garcia
,
Guillermo E. Quevedo Chavez
,
Yesica Albor
,
Enrique Mendez
,
Maria Elena Medina-Mora
,
Philippe Mortier
, and
Hans-Juergen Rumpf

Background and aims

DSM-5 includes Internet gaming disorder (IGD) as a condition for further study. While online and offline gaming may produce undesired negative effects on players, we know little about the nosology of IGD and its prevalence, especially in countries with emerging economies.

Methods

A self-administered survey has been employed to estimate prevalence of DSM-5 IGD and study the structure and performance of an instrument in Spanish to measure DSM-5 IGD among 7,022 first-year students in 5 Mexican universities that participated in the University Project for Healthy Students (PUERTAS), part of the World Health Organization’s World Mental Health International College Student Initiative.

Results

The scale for IGD showed unidimensionality with factor loadings between 0.694 and 0.838 and a Cronbach’s α = .816. Items derived from gaming and from substance disorders symptoms mixed together. We found a 12-month prevalence of IGD of 5.2% in the total sample; prevalence was different for males (10.2%) and females (1.2%), but similar for ages 18–19 years (5.0%) and age 20+ (5.8%) years. Among gamers, the prevalence was 8.6%. Students with IGD were more likely to report lifetime psychological or medical treatment [OR = 1.8 (1.4–2.4)] and any severe role impairment [OR = 2.4 (1.7–3.3)]. Adding any severe role impairment to the diagnostic criteria decreased the 12-month prevalence of IGD to 0.7%.

Discussion and conclusions

Prevalence of DSM-5 IGD and the performance of diagnostic criteria in this Mexican sample were within the bounds of what is reported elsewhere. Importantly, about one in every seven students with IGD showed levels of impairment that would qualify them for treatment under DSM-5.

Open access