Gold nanoparticles are attractive as sensing materials because of their size and shape are related with their optical properties. The color change produced by the aggregation of functionalized AuNPs ...allows the detection of arsenic at low levels. A simple, cheap and fast analytical procedure to perform arsenic determination using functionalized gold nanoparticles (AuNPs) and VIS spectrometry as a detection technique is studied. Three different synthesis procedures to obtain the AuNPs and two different functionalization modes were studied. AuNPs functionalized with GSH-DTT-CYs-PDCA were selected as the most adequate. The correlation between the decrease in the absorbance signal and the arsenic concentration was good in the 2–20µgl−1interval. Repeatability, expressed as average of RSD (%), obtained for the different arsenic concentrations studied was 0.6%. The average value of the analytical recovery was 99.7%. The detection and quantifications limits were 2.5 and 8.4µgl−1 respectively. These limits are sufficient to detect World Health Organization’s guideline value of 10µgl−1.
•Gold nanoparticles functionalized with GSH-DTT-CYs-PDCA for arsenic determination.•VIS Spectroscopy to determine arsenic in water at ppb levels.•Advantages of the method: simplicity, low cost, sensitivity, precision and time.
Seagrasses, as key ecosystem engineers in coastal ecosystems, contribute to enhancing diversity in comparison with nearby bare areas. It has been proved mainly for epifauna, but data on infauna are ...still scarce. The present study addresses how seagrass structural complexity (i.e., canopy properties) affects the diversity of infaunal organisms inhabiting those meadows. Canopy attributes were achieved using seagrass mimics, which were used to construct in situ vegetation patches with two contrasting canopy properties (i.e., shoot density and morphology) resembling the two seagrass species thriving in the inner Cadiz Bay: Zostera noltei and Cymodocea nodosa. After three months, bare nearby areas, two mimicked seagrass patches (‘Zostera’ and ‘Cymodocea’), and the surrounding natural populations of Zostera noltei were sampled in a spatially explicit way. Shifts in organism diets were also determined using 15N and 13C analyses in available food sources and main infaunal organisms, mixing models, and niche metrics (standard ellipse area). Seagrass-mimicked habitats increased the species richness (two-fold), organism abundance (three to four times), and functional diversity compared with bare nearby areas. The clam Scrobicularia plana (deposit/filter feeder) and the worm Hediste diversicolor (omnivore) were dominant in all of the samples (> 85%) and showed an opposite spatial distribution in the reconstructed patches: whilst S. plana accumulated in the outer-edge parts of the meadow, H. diversicolor abounded in the center. Changes in the isotopic signature of both species depending on the treatment suggest that this faunal distribution was associated with a shift in the diet of the organisms. Based on our results, we concluded that facilitation processes (e.g., reduction in predation and in bioturbation pressures) and changes in food availability (quality and quantity) mediated by seagrass canopies were the main driving forces structuring this community in an intertidal muddy area of low diversity.
We use density functional theory to analyze the charge transfer between lithium or magnesium cations and a graphene wall beyond the predictions of classical Marcus theory. To that end, metal atoms ...are placed in three different kinds of environments: (i) in a vacuum, (ii) among fluorine atoms to simulate a molten salt, and (iii) in an ionic liquid. We prove that a complete charge transfer to the electrodes takes place in all of the studied environments and that the charge transfer process starts at longer distances from the electrode in the ionic liquid. Vertical ionization potentials and vertical electron affinities are studied, and they confirm that the nanoconfined region close to the electrode is a favorable environment for electronic exchange. No significant difference between monovalent and divalent cations was found. Our results suggest a certain catalyzing effect of ionic liquids regarding metal-electrode charge transfer in these densely ionic environments. Moreover, they show that ionic liquids can actually enhance charge transfer to electrodes in electrochemical devices without significantly altering the nature of the process.
The superoxide dismutase (SOD) is the principal antioxidant defense system in the body that is activated by a reactive oxygen species. Some variants of the SOD2 gene have been associated with cancer. ...The rs4880 variant was determined by PCR real-time and the rs5746136 variant by PCR-RFLP in healthy subjects and in breast cancer (BC) patients. The rs4880 and rs5746136 variants were associated with BC susceptibility when BC patients and the control group were compared for the CT, TT, CTCC, and the T alleles (p < 0.05). The CT genotype of the rs4880 variant showed significant statistical differences in patients and controls aged ≤ 45 years old, and with hormonal consumption (p < 0.05). The rs4880 variant was associated with BC patients with CTTT genotype and obesity, the presence of DM2-SAH, and a non-chemotherapy response (p < 0.05). Additionally, the rs5746136 variant was associated with susceptibility to BC with Ki-67 (≥20%), luminal A type BC, and a chemotherapy partial response (p < 0.05) in BC patients who carry TT, TC, and CTTT genotypes, respectively. The haplotype T/T (OR 1.98; 95% CI 1.20−3.26, p = 0.005) was observed to be a risk factor for BC. The rs4880 and rs5746136 variants in the SOD2 gene were associated with BC susceptibility.
Abstract The Dark Energy Spectroscopic Instrument (DESI) completed its 5 month Survey Validation in 2021 May. Spectra of stellar and extragalactic targets from Survey Validation constitute the first ...major data sample from the DESI survey. This paper describes the public release of those spectra, the catalogs of derived properties, and the intermediate data products. In total, the public release includes good-quality spectral information from 466,447 objects targeted as part of the Milky Way Survey, 428,758 as part of the Bright Galaxy Survey, 227,318 as part of the Luminous Red Galaxy sample, 437,664 as part of the Emission Line Galaxy sample, and 76,079 as part of the Quasar sample. In addition, the release includes spectral information from 137,148 objects that expand the scope beyond the primary samples as part of a series of secondary programs. Here, we describe the spectral data, data quality, data products, Large-Scale Structure science catalogs, access to the data, and references that provide relevant background to using these spectra.
Aim: Most analyses of end of life decisions in Neonatal Intensive Care Units (NICUs) have come from Europe/English‐speaking countries. Would decisions be different in Latin American NICUs? ...Therefore, we aim to evaluate the approach to dying infants/families in NICUs in Latin America.
Methods: Multinational descriptive study of all deaths in babies born at >22 weeks in eight NICUs in five Latin American countries. Deaths were categorized as: (i) no Cardiopulmonary Resuscitation (CPR) or life support offered; (ii) life support initiated but do not resuscitate (DNR) orders written or no CPR provided; (iii) full life support and CPR; and (iv) unclassifiable.
Results: There were 100 deaths, 81% in >27 weeks. Seventeen infants received no CPR/life support at birth, 10 died in DR and seven in NICU. There were 27 infants in group 2, 54 in group three and two in group 4. No baby had care withdrawn or care withdrawn/CPR withheld. Thirty‐two infants had ‘do not resuscitate’ order. Decisions without parents’ involvement in 15%, both parents present at death 24% and sedatives/narcotics documented 14%.
Conclusions: Latin American NICUs differ from those in Northern Europe/English‐speaking countries. More deaths are accompanied by full life support and CPR. DNR orders are rare. Withdrawal of life support is virtually non‐existent. Latin American’s doctors are more likely to make decisions without the objections of family about withholding life‐sustaining treatment.
In the present paper, we analyze the dependence of the second critical micelle concentration (second cmc) of ionic amphiphiles on the number of atoms in the hydrocarbon molecular chain,
n
c
. A ...molecular thermodynamic model for the interaction energy between the end caps of rodlike micelles,
g
(
N
)
, is introduced and the linear dependence of this object on
n
c
analyzed, thus leading to a Stauff-Klevens-like behavior of the second cmc. The predictions agree with previously reported data for
n-alkyldimethylbenzylammonium chloride (C
n
BACl) for
n-alkylpyridinium chloride (C
n
PyCl) and
n-alkyltrymethylammonium bromide (C
n
TABr) at 35 °C. These conclusions are reinforced by the conductivity, density, and ultrasound velocity measurements of the second cmc of several C
n
PyCl (
n
=
12
, 14, 16) and
n-alkylpyridinium bromides (C
n
PyBr,
n
=
12
, 14, 15, 16) presented in this paper.
A molecular thermodynamic model of micellar growth has been formulated and a Stauff-Klevens-like relation derived for the second cmc.
Trying to contribute to an overall picture of solvation in ionic liquids, we report a review of the main recent results in the field of molecular dynamics simulations of structural and dynamic ...properties of mixtures of ionic liquids with molecular cosolvents or salts. The majority of reported results indicate that solvation of neutral molecules and salt ions takes place selectively in the bulk nanoregions of the dense ionic solvents, fitting the parts of the solute's moieties to the similar regions of the dense ionic solvent, in what has been called nanostructured solvation Méndez-Morales et al. J. Phys. Chem. B 118 (2014) 761–770.
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