Authors:Eva Natividad, M. Castro, R. Burriel, and L. Angurel
from 5 to 300 K the thermal conductance of different superconducting Bi-2212
thin rods and one superconducting module integrating a hybrid current lead
based on such rods. The conductance values of the rods are lower than the
measurable limits of the set-up and a detailed evaluation of the heat losses
is required. The analysis of the heat exchanges permits to introduce a correction
function to the measured values and allows to study low thermal conductivity
materials. The dependence of the thermal conductivity of Bi-2212 rods on the
sample microstructure is analyzed after this correction. We calculate analytically
the time required to reach the steady-state for long bars for which extended
relaxation times are expected. From the measured conductance data we estimate
the heat load introduced by the current lead into a cryogenic bath in static
Authors:J. Arocha, J. Jerónimo-Castro, L. Montejano, and E. Roldán-Pensado
In this paper the following is proved: letK ∈ ℝ2be a convex body and t ∈ [0, 1/4]. If the diameter of K is at least √37 times the minimum width, then there is a pair of orthogonal lines that partition K into four pieces of areas t, t, (1/2−t), (1/2−t) in clockwise order. Furthermore, if K is centrally symmetric, then we can replace the factor √37 by 3.
Authors:V. Maihara, P. Moura, M. Catharino, L. Castro, and R. Figueira
Arsenic and cadmium contents in eight edible mushroom species (Agaricus bisporus, Agaricus sp, Pleurotus ostreatus, Pleorotus florida, Pleorotus eryngui, Pleurotus osteatus, Pleurotus salmoneostramineus,
Lentinula edodes) consumed by Brazilian population were determined by instrumental neutron activation analysis (INAA) and graphite furnace
atomic absorption spectrometry (GF AAS), respectively. Arsenic concentrations varied from 0.009 mg/kg in P. eryngui to 0.210 mg/kg dry weight in L. edodoes and Cd from 0.011 g/kg in P. eryngui to 0.229 mg/kg dw in P. salmoneostramineus. The consumption of mushrooms in São Paulo-Brazil may be considered safe from a toxicological point of view as As and Cd
presented levels of ingestion are below the maximum levels recommended by the World Health Organization.
Authors:D. Palacios, D. Castro, M. Perez, F. Urbani, L. Sajo-Bohus, and J. LaBrecque
The concentrations of40K,226Ra,232Th and137Cs were determined in the upper layers of soils in the central coastal region of Venezuela. The activities of137Cs are higher in the areas where the forest is well developed, oriented towards the wind and at higher elevations. The origin
of the137Cs deposition is from water input from the clouds directly in the cloudforest and rainfall from the northeast trade winds.
Even though the values of137Cs are much higher in these areas, there is little or no significant increase in the health risk. The natural radioactivity
is correlated with the geology in the region except in the area of Urama. The values for the natural radiation background
are as follows: for potassium between 1–3%, for radium between 1–3 ppm and for thorium the range was 6–39 ppm. The corresponding
amounts of absorbed dose rates in air, the exposure rates and the annual effective dose equivalents are in the following ranges
respectively: 11–39 pGy/s, 4–16 uR/h and 0.25–0.86 mSv/y. The annual effective dose equivalents include the contribution of
the global average (2.57 mSv/y) of the rest of the natural sources of radiation. Finally, the largest natural radioactivity
background, was found near Chichiriviche as a result of the massive granite deposits in this area, but again there is no significant
Authors:C. Capetillo Leala, L. Ancona Méndez, C. Sandoval Castro, and G. Cetz Zapata
from Yucatan State, Mexico was compared with a local variety of
, in terms of chemical composition and amino acid profile. No differences were found (P=0.55) in crude protein content of
(20.2±0.15 vs. 20.3±0.16 g/100 g DM., respectively).
had a lower fiber and fat content (P<0.05). No difference was found in ash content (P>0.05).
has a higher proportion (P<0.05) of valine, isoleucine, phenylalanine, aspartate and alanine while
had higher proportion (P<0.05) of proline and glutamate, no difference was found in the remaining amino acids. Both species had a high proportion of aspartate and glutamate. In general, the human amino acid requirements for adults are satisfied, however, leucine and lysine might become limiting. It was concluded that
can be included in human diet in similar fashion as
Authors:M. Gonzalez-Castro, L. Ordoñez-Acevedo, Y. Herrera-Vazquez, J. Ramirez-Telles, and A. Leon-Rodriguez
Bisphenol A (BPA), bisphenol A dimethacrylate (BisDMA) and phthalic acid (PA) endocrine disruptors can migrate from the plastic lining of cans to foods producing serious health problems when they exceed allowable concentration limits for consumption. In this work, a method was assessed for the determination of BPA, BisDMA, and PA in vegetable food cans from Mexico using a food simulant. Those disruptors were determined by HPLC connected to an Evaporative Light Scattering Detector (ELSD), and simultaneous detection by UV-Vis detector was used for validation. The most frequently found disruptor in major concentration was PA over the range of 5.40 to 112.39 μg l−1. The samples analysed did not exceed the migration limit accepted by the US-FDA and US-EPA for bisphenols. Our results showed that HPLC-ELSD produces chromatograms with accurate signals and smaller detection limits than the UV-Vis detector for the substances analysed here.
Authors:Jesús Castro-Calvo, Rafael Ballester-Arnal, Marc N. Potenza, Daniel L. King, and Joël Billieux
In April 2018, the servers of the popular video game “Fortnite” crashed for 24 hr. During this period, Pornhub (a popular pornographic website) analyzed trends in pornography access, finding that: (a) the percentage of gamers accessing Pornhub increased by 10% and (b) the searches of pornographic videos using the key term “Fortnite” increased by 60%. In this letter, we discuss these observations in the context of ongoing debate regarding the validity of “withdrawal” when applied to problematic involvement in video gaming and the potential use of pornography as a “compensation behavior” during the periods of “forced abstinence” from gaming.
Authors:R. A. G. Silva, A. T. Adorno, A. G. Magdalena, T. M. Carvalho, M. Stipcich, A. Cuniberti, and M. L. Castro
In this study the effect of Ag additions on the thermal behavior of the Cu–22.55 at.%Al alloy was studied using electrical resistivity measurements, in situ X-ray diffractometry, differential scanning calorimetry, and optical microscopy. The results indicated that Ag additions do not change the phase transformations sequence in the studied alloys, but modify its critical temperatures due to a change on entropy of system. It was verified that at the cooling rate of 10 K/min the decomposition of β phase into (α + γ1) is incomplete, but for lower cooling rates than 1.0 K/min this reaction is completed.