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Selective Lanthanide Sensing with Gold Nanoparticles and Hydroxypyridinone Chelators.
The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au3+ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides
ENOBIO - First tests of a dry electrophysiology electrode using carbon nanotubes
We describe the development and first tests of Enobio, a dry electrode sensor
concept for biopotential applications. In the proposed electrodes, the tip of
the electrode is covered with a forest of multi-walled CNTs that can be coated
with Ag/AgCl to provide ionic-electronic transduction. The CNT brush-like
structure is to penetrate the outer layers of the skin improving electrical
contact as well as increae the contact surface area. In this paper, we report
the results of the first tests of this concept -- immersion on saline solution
and pig skin signal detection. These indicate performance on a par with state
of the art research-oriented wet electrodes.Comment: Submitted and accepted at the 28th IEEE EMBS International
Conference, New York City, August 31st-September 3rd, 2006. Figures updated
with proper filtering and averagin
La justificación racional de los derechos humanos en los redactores de la Declaración Universal de los Derechos Humanos
Suele pensarse que la falta de acuerdo en los
‘por qué’ de los derechos humanos, llevó a los redactores
de la Declaración Universal de 1948, a evitar cualquier intento
de justificación racional de los derechos humanos
o al menos prescindir de afirmaciones de tipo metafÃsico.
Este trabajo intenta mostrar cómo es que los redactores
de la Declaración construyeron un argumento cerrado
pero incompleto de justificación racional de los derechos
humanos, al articular una descripción de un ‘ser’, que es
posible ‘conocer’ del que se sigue un ‘deber’. El acuerdo
práctico al que llegaron los redactores sólo es posible si se
afirman unas verdades metafÃsicas mÃnimas
¿Es eficaz la formación en la Administración pública española?: Evaluación de la transferencia de los aprendizajes con el modelo FET
Is training in Spanish Public Administration effective?: evaluation of transfer of learning using the FET model». This paper analyses the efficacy of the continuous training attended by the Spanish public administration employees, in terms of learning transfer at the work- place. The analysis was conducted using the FET (Factors to Evaluate Transfer) model. Two questionnaires were applied to 1.148 trainees of training actions organized by four Spanish public administration schools; the data analysis included testing hypothesis and multiple regression models. Main results demonstrate that learning transfer is related to factors of the training and workplace context, and not to variables related to trainees’ profile
Global sensitivity analysis of leaf-canopy-atmosphere RTMs: Implications for biophysical variables retrieval from top-of-atmosphere radiance data
Knowledge of key variables driving the top of the atmosphere (TOA) radiance over a vegetated surface is an important step to derive biophysical variables from TOA radiance data, e.g., as observed by an optical satellite. Coupled leaf-canopy-atmosphere Radiative Transfer Models (RTMs) allow linking vegetation variables directly to the at-sensor TOA radiance measured. Global Sensitivity Analysis (GSA) of RTMs enables the computation of the total contribution of each input variable to the output variance. We determined the impacts of the leaf-canopy-atmosphere variables into TOA radiance using the GSA to gain insights into retrievable variables. The leaf and canopy RTM PROSAIL was coupled with the atmospheric RTM MODTRAN5. Because of MODTRAN's computational burden and GSA's demand for many simulations, we first developed a surrogate statistical learning model, i.e., an emulator, that allows approximating RTM outputs through a machine learning algorithm with low computation time. A Gaussian process regression (GPR) emulator was used to reproduce lookup tables of TOA radiance as a function of 12 input variables with relative errors of 2.4%. GSA total sensitivity results quantified the driving variables of emulated TOA radiance along the 400-2500 nm spectral range at 15 cm-1 (between 0.3-9 nm); overall, the vegetation variables play a more dominant role than atmospheric variables. This suggests the possibility to retrieve biophysical variables directly from at-sensor TOA radiance data. Particularly promising are leaf chlorophyll content, leaf water thickness and leaf area index, as these variables are the most important drivers in governing TOA radiance outside the water absorption regions. A software framework was developed to facilitate the development of retrieval models from at-sensor TOA radiance data. As a proof of concept, maps of these biophysical variables have been generated for both TOA (L1C) and bottom-of-atmosphere (L2A) Sentinel-2 data by means of a hybrid retrieval scheme, i.e., training GPR retrieval algorithms using the RTM simulations. Obtained maps from L1C vs L2A data are consistent, suggesting that vegetation properties can be directly retrieved from TOA radiance data given a cloud-free sky, thus without the need of an atmospheric correction
First human trials of a dry electrophysiology sensor using a carbon nanotube array interface
Fatigue, sleepiness and disturbed sleep are important factors in health and
safety in modern society and there is considerable interest in developing
technologies for routine monitoring of associated physiological indicators.
Electrophysiology, the measurement of the electrical activity of biological
origin, is a key technique for the measurement of physiological parameters in
several applications, but it has been traditionally difficult to develop
sensors for measurements outside the laboratory or clinic with the required
quality and robustness. In this paper we report the results from first human
experiments using a new electrophysiology sensor called ENOBIO, using carbon
nanotube arrays for penetration of the outer layers of the skin and improved
electrical contact. These tests, which have included traditional protocols for
the analysis of the electrical activity of the brain--spontaneous EEG and
ERP--indicate performance on a par with state of the art research-oriented wet
electrodes, suggesting that the envisioned mechanism--skin penetration--is
responsible. No ill side-effects have been observed six months after the tests,
and the subject did not report any pain or special sensations on application of
the electrode
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