Search Results

You are looking at 1 - 9 of 9 items for

  • Author or Editor: J. Nieto x
  • All content x
Clear All Modify Search

Abstract  

Several methods for the rapid determination of the degree of acetylation of chitin and related polymers have been evaluated, including the use of the infrared and the mass spectra.Chitin and chitosan have characteristic degradation temperatures and it is possible to determine the acetylation degree by the use of empirical correlations based on the weight losses associated with the main decomposition peaks.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Mestnik, J. Mengatti, W. Nieto, S. Yanagawa, L. Sumiya, C. Silva, and J. Osso

Abstract  

These studies had the purpose of establishing the optimal conditions for the production of123I through the124Te (p, 2n)123I reaction, using the CV-28 Cyclotron (Emax=24 MeV for protons) at IPEN-CNEN/SP. Two different targets (TeO2 and TeO2+2% Al2O3) were irradiated in order to check their physical resistance against beam current (up to 12 A) and length of irradiation (10 min — 2h), and to evaluate the recovery of the radioiodine produced, by a dry distillation process with a high frequency induction furnace. Later on, enriched124TeO2 (96.2%) targets were irradiated, and123I was produced routinely with a production yield of (3. 31±0.07) mCi/Ah, 1.7% of124I at EOB and radiochemically pure.

Restricted access

Abstract

We aimed to analyse the complexity and fractal nature of heartbeat during constant exercise, at three different intensities, and recovery.

Fourteen healthy men underwent 4 separate sessions. The first session was an incremental treadmill test to determine ventilatory thresholds (VT1 and VT2) and maximal aerobic speed (MAS). Each subject ran at VT1 and VT2 speeds and MAS (second, third and fourth day). The duration of VT1 and VT2 loads were selected in such a way that the product intensity-duration (training load) was the same. Sample Entropy (SampEn) and slope of Detrended Fluctuation Analysis (DFA α1) were measured during the whole session.

DFA α1 declines with exercise, being less in the VT1 trial than in the other two.

SampEn shows no significant change during exercise. The three tests induce the same decline in SampEn, but at the highest intensity (MAS) tends to decline during the exercise itself, whereas at lower intensities (VT1, VT2) the decline is delayed (10 min of recovery). Subsequently, SampEn at VT1 gradually recovers, whereas at VT2 and MAS it remains stable during recovery.

In conclusion, exercise produces a loss of heartbeat complexity, but not fractal nature, during recovery and it depends on intensity.

Restricted access
Cereal Research Communications
Authors: J.L. Zárate-Castrejón, C.L. Aguirre-Mancilla, E. Solís-Moya, J.E. Ruiz-Nieto, J.C. Raya-Pérez, J.G. Ramírez-Pimentel, and V. Montero-Tavera

Yellow rust is a wheat disease caused by Puccinia striiformis, this pathogen causes economic losses in susceptible materials, which represent up to 70% of wheat varieties. Currently, the incorporation of genetic resistance through molecular tools, is a process used in the generation of new varieties resistant to this pathogen. A strategy employed to identify genes involved in the resistance to yellow rust is to screen differential EST obtained by suppressive subtractive hybridization. In this research, cDNA was extracted from healthy and inoculated plants from the resistant line V-26 from INIFAP. A set of 200 differentially expressed EST were cloned and sequenced, and 31 of them were selected for expression profile analysis by RT-PCR; additionally, with the aim of validate RT-PCR results, five genes were selected for RT-qPCR analysis in genotypes inoculated by P. striiformis. The results showed high levels of expression of selected genes in genotypes classified as resistant in the field conditions (21, 143, 230, 242, 261 and 277), while in the susceptible genotype 16, few genes were induced by the rust. Expression profiles confirmed significant differences between resistant and susceptible lines.

Restricted access