This work studies the structural, microstructural, and magnetic properties of carbon nanotubes with magnetic iron carbide nanoparticles attached to their walls. The samples were fabricated in a ...single step using a modified chemical vapor deposition (CVD) method. The proposed method allows to obtain carbon nanotubes with iron carbide nanoparticles partially immersed in their walls. The carbon nanotubes were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Results show that the obtained carbon nanotubes are multi-walled with a bamboo-like structure. They have an average diameter of 40 nm and inner cavities of 20 nm in diameter. The magnetic nanoparticles are firmly fixed to the nanotubes, and they have an average diameter of 15 nm with rounded borders. The iron carbide nanoparticles exhibit a ferromagnetic behavior with high magnetic saturation resulting from their morphological characteristics and their location on the walls of the nanotubes, which prevent their agglomeration and reduce dipolar interactions.
Lead sulfide (PbS) nanocrystals anchored on nitrogen-doped multiwalled carbon nanotubes (CNx) have been synthesized employing an environmentally friendly and inexpensive wet chemistry process. ...CNx/PbS composites have been examined by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. Theorical ab initio calculations have been developed to determine the samples structural, morphological and optical properties to explain the experimental evidences. The PbS nanoparticles exhibit of 4 nm to 27 nm particle size with a face-centered cubic crystal structure and are homogeneously distributed along the carbon nanotubes. The nitrogen-doped CNTs acts as binding sites for the PbS clusters as ab initio theoretical study suggests.
Ionizing radiation dosimetry with thermoluminescence (TL) materials based on silicon or glass can be interesting in its potential use in radiation monitoring as the solution to the constant looking ...of development of new radiation detectors. In this work, TL characteristics of sodium silicate exposed to beta radiation effects were studied. TL response beta irradiated exhibited a glow curve with two peaks centered at 398 K and 473 K. Samples showed linearity from 0.55 to 13.2 Gy. TL readings after 10 times showed a repeatability with an error of less than 1%. Remain information showed significant losses during the first 24 h, but its information was almost constant after 72 h of storage. The Tmax-Tstop method exhibited three peaks which were mathematically analyzed with a general order deconvolution finding kinetic orders close to the second order for the first peak, meanwhile the kinetic order for the second peak and third peak are close to second order. Finally, the VHR method showed anomalous TL glow curve behavior with an increasing intensity TL as the heating rate increased.
•Sodium Silicate Glass is good candidate for beta radiation monitoring applications.•Tl glow curve has two main peaks. They are composed of shallow and deep traps.•Trivalent ions Pr3+ modified the TL intensity of Sodium Silicate Glass.•TL glow curve deconvolution shows three peaks.•TL behavior observed is anomalous when varying the heating rate VHR.
Eisenia arborea
(sensu
Ecklonia arborea
) is the kelp with the greatest latitudinal distribution on the Northeastern Pacific Coast. It is harvested in Mexico in small amounts for abalone farm fodder ...and occasionally exported to Asia for human consumption. Because the high-energy environment where it naturally grows limits its sustainable harvest, we explored the domestication and cultivation of this kelp on the west coast of Baja California, Mexico. The life history of
E. arborea
was completed in the laboratory following traditional methods for kelp cultivation. Gametophytes became reproductive approximately 50 days after spore release and sporophytes were visible to the naked eye after 80 days. When sporophytes reached 2–3 cm, they were transplanted to two sites on long-line systems: in an open bay (Todos Santos Bay) and in a shallow coastal lagoon (San Quintín Bay). At both sites, full differentiation occurred 6 to 8 months after deployment, with fertile blades occurring within a year. Once individuals reached maximum size, blades were harvested by pruning. Monthly, regrowth of pruned blades and new blade addition were measured. Pruned individuals reached the same weight as controls in three months. On the basis of these results, a seasonal seeding program was implemented at a third site where the presence of natural
Eisenia
is rare due to the lack of hard substrate but was hypothesized to provide appropriate conditions for kelp cultivation (Santa María Bay). Cultures were deployed at three different depths and growth was correlated with season, depth, and temperature. Only cultures seeded in winter developed successfully at this site. This study shows that the culture of
E. arborea
in a variety of ocean conditions is possible; however, site selection and seasonality are important considerations. Because
E. arborea
is perennial, it can be harvested periodically during the year thereby increasing yield, and because it is the warmest tolerant kelp species, it is an ideal target for ocean farming and commercial cultivation, considering climate change.
Bacteria of the genus Brucella are facultative intracellular parasites that cause brucellosis, a severe animal and human disease. Recently, a group of taxonomists merged the brucellae with the ...primarily free-living, phylogenetically related
spp. in the genus Brucella. This change, founded only on global genomic analysis and the fortuitous isolation of some opportunistic
spp. from medically compromised patients, has been automatically included in culture collections and databases. We argue that clinical and environmental microbiologists should not accept this nomenclature, and we advise against its use because (i) it was presented without in-depth phylogenetic analyses and did not consider alternative taxonomic solutions; (ii) it was launched without the input of experts in brucellosis or
; (iii) it applies a non-consensus genus concept that disregards taxonomically relevant differences in structure, physiology, population structure, core-pangenome assemblies, genome structure, genomic traits, clinical features, treatment, prevention, diagnosis, genus description rules, and, above all, pathogenicity; and (iv) placing these two bacterial groups in the same genus creates risks for veterinarians, medical doctors, clinical laboratories, health authorities, and legislators who deal with brucellosis, a disease that is particularly relevant in low- and middle-income countries. Based on all this information, we urge microbiologists, bacterial collections, genomic databases, journals, and public health boards to keep the Brucella and
genera separate to avoid further bewilderment and harm.
The reaction of 2-bromo-5-(1H-pyrazol-1-yl)pyrazine (LI) and bromotricarbonyl(tetrahydrofuran)-rhenium(i) dimer leads to the monometallic complex (2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br (I), ...which displays a non-regular octahedral geometry around the ReI center, a fac-correlation for carbonyls, with the pyrazine and pyrazolyl rings being highly coplanar. I experiences one irreversible oxidation at Ep,a = 1.067 V and two irreversible reductions at Ep,c = −1.445 V and −1.675 V. DFT supports that the oxidation is a metal-centered process but the first reduction wave should be a ligand-centered process. Comparison with related complexes suggests that the second reduction is metal centered (ReI/Re0). Three absorption bands were observed for I around 260, 315 and 400 nm, and the first two were assigned to the intraligand (IL) π → π* transitions while the band around 400 nm corresponds to a metal-to-ligand charge transfer (MLCT) transition. Excitation of I at 280 nm leads to two emission bands at 360 nm and 640 nm, and the first one is attributed to the 1IL transition and the second to 3MLCT. The 3MLCT emission decays with lifetimes of 17 and 44 ns in MeCN and DCM, respectively. Addition of trifluoroacetic acid to the solution leads to its reaction with the 3MLCT excited state, giving rise to a long-lived and very oxygen sensitive species, 3ILH+. This behaviour makes I a potential sensor for protons and possibly other cations in solution.
Recent progress in the domestication of Eisenia arborea lead us to test this species as an alternative to feed red abalone (Haliotis rufescens) instead of Macrocystis pyrifera, which is the main ...seaweed used to feed farmed abalone in Baja California, Mexico. E. arborea is the kelp with the largest and most southerly latitudinal distribution on the North Pacific East Coast capable of growing at higher temperatures and in relatively low nutrient conditions. The availability of M. pyrifera is frequently uncertain because it is strongly affected by El Niño events. In order to test E. arborea as a diet for farmed abalone, animals of two different sizes (6 and 2 cm) were fed separately for 12 months with these two seaweed species. The abalones were cultured in cages in an integrated multi-trophic aquaculture farm within San Quintín Bay, Baja California, Mexico. Seaweed was collected for chemical analysis, and every 3 months, animals were measured and weighed to estimate growth. Small size abalone doubled their size on both diets, with an average increase in length of 2.2 mm month⁻¹. No significant differences were observed between both treatments. Large abalone fed with M. pyrifera had slighter higher growth rates compared to those fed with E. arborea (0.57 and 0.50 % day⁻¹, respectively). Although M. pyrifera appeared to be a better diet for large animals, the growth rates obtained with E. arborea and the fact that this species could be cultivated in warmer conditions makes this seaweed species a good candidate to feed farmed abalone.
This work reports the persistent luminescence (PersL) properties of the commercial LiF:Mg,Ti (TLD-100) dosimeter and its performance in dosimetry applications. The thermoluminescence (TL) glow curve ...of the TLD-100 exhibits a peak at 96 °C that rapidly vanishes at room temperature, enabling the PersL phenomenon. The TLD-100 was exposed to beta particle irradiation within in the range of 0.22–32 Gy. The resulting PersL intensity was measured and found to increase as the irradiation dose increased. Notably, there was no saturation of the PersL intensity within this dose range with linear dependence from 0.55 to up 32 Gy. The TLD-100 showed good repeatability with a deviation of 0.1% after seven irradiation-readout cycles for twenty irradiations. The calculated lower detection limit was 2 mGy. Our results indicate that the TLD-100 can be used as a PersL and TL dosimeter for dosimetry applications, with the advantages of fast post-irradiation measurements.
•The persistent luminescence of a commercial TLD-100 dosimeter after beta particle irradiation is presented.•The persistent luminescence intensity increased with increasing irradiation dose from 0.55 to 32 Gy with linear dependence.•The calculated lower detection limit was 2 mGy for TLD-100 using persistent luminescence phenomenon.•The persistent luminescence could be complementing the traditional TL dosimetry method.
Ionizing radiation dosimetry with thermoluminescence (TL) materials based on silicon or glass can be interesting in its potential use in radiation monitoring as the solution to the constant looking ...of development of new radiation detectors. In this work, TL characteristics of sodium silicate exposed to beta radiation effects were studied. TL response beta irradiated exhibited a glow curve with two peaks centered at 398 K and 473 K. Samples showed linearity from 0.55 to 13.2 Gy. TL readings after 10 times showed a repeatability with an error of less than 1%. Remain information showed significant losses during the first 24 h, but its information was almost constant after 72 h of storage. The T
-T
method exhibited three peaks which were mathematically analyzed with a general order deconvolution finding kinetic orders close to the second order for the first peak, meanwhile the kinetic order for the second peak and third peak are close to second order. Finally, the VHR method showed anomalous TL glow curve behavior with an increasing intensity TL as the heating rate increased.
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