The resistance of an ordered 3D-Bi
Te
nanowire nanonetwork was studied at low temperatures. Below 50 K the increase in resistance was found to be compatible with the Anderson model for localization, ...considering that conduction takes place in individual parallel channels across the whole sample. Angle-dependent magnetoresistance measurements showed a distinctive weak antilocalization characteristic with a double feature that we could associate with transport along two perpendicular directions, dictated by the spatial arrangement of the nanowires. The coherence length obtained from the Hikami-Larkin-Nagaoka model was about 700 nm across transversal nanowires, which corresponded to approximately 10 nanowire junctions. Along the individual nanowires, the coherence length was greatly reduced to about 100 nm. The observed localization effects could be the reason for the enhancement of the Seebeck coefficient observed in the 3D-Bi
Te
nanowire nanonetwork compared to individual nanowires.
The resistance of an ordered 3D-Bi2Te3 nanowire nanonetwork was studied at low temperatures. Below 50 K the increase in resistance was found to be compatible with the Anderson model for localization, ...considering that conduction takes place in individual parallel channels across the whole sample. Angle-dependent magnetoresistance measurements showed a distinctive weak antilocalization characteristic with a double feature that we could associate with transport along two perpendicular directions, dictated by the spatial arrangement of the nanowires. The coherence length obtained from the Hikami–Larkin–Nagaoka model was about 700 nm across transversal nanowires, which corresponded to approximately 10 nanowire junctions. Along the individual nanowires, the coherence length was greatly reduced to about 100 nm. The observed localization effects could be the reason for the enhancement of the Seebeck coefficient observed in the 3D-Bi2Te3 nanowire nanonetwork compared to individual nanowires.
Introducción: A partir de un análisis de la literatura y de la experiencia de las autoras en este ámbito, este artículo describe el diseño y aplicación, un plan estratégico de incidencia ...psicoafrontativo. El objetivo fue estructurar una estrategia para poder aplicarla como entrenamiento en servidores migrantes de primera línea con la posibilidad de hacer incidencia para que puedan mirar los problemas de sus usuarios desde otra perspectiva y facilitarles nuevas herramientas para que los migrantes puedan afrontar sus vivencias emocionales por el proceso de movilidad. La metodología que se siguió fue One Single Session Therapy adaptado culturalmente e integrado estructuralmente con técnicas tomadas de la Terapia de Arte, con miras de hacer de los espacios como albergues, casas migrantes, entre otras, espacios Ethos. Resultados: Debido a que éste es un modelo contextual y una práctica curativa socialmente situada que se esfuerza por activar los propios recursos habilidades y fortalezas de los participantes, se presenta también el cómo llevarlo a cabo a modo capacitación, vivencial primero en un grupo de servidores y con ello observar la posibilidad de replicarlo en sus espacios de trabajo. Discusión: Los encuentros son no intrusivos, educativos, lúdicos. Funcionan como procesos restaurativos para contrarrestar la vulnerabilidad extrema.
Abstract
Background
SARS-CoV-2 infection had specific characteristics in the pediatric population described in previous studies. These clinical features included specific COVID-19 presentation, ...antibiotic usage, and predictors of disease severity. In addition to patient related factors, external influences could affect COVID-19 outcomes. The features of children with COVID-19 of five Latin American countries were described. Study participants were members of the Prevencionistas e Infectólogos para Cáncer Pediátrico en América Latina (PRINCIPAL) Network of the Global Infectious Diseases Program at St Jude Children's Research Hospital. This study aims to analyze the differences between patients with non-severe and severe disease when the circulation of the Delta variant was predominant, and few children had received SARS-CoV-2 vaccines.
Methods
This is a retrospective, observational, multinational study that included children with a confirmed diagnosis of COVID-19 between January 2021 and January 2022. Epidemiological, clinical, and treatment characteristics are described and compared between patients with severe and non-severe disease. Frequencies and percentages are presented as well as median and interquartile ranges (IQR). Comparisons were made using the chi-squared test for proportions and the Wilcoxon test for nonparametric quantitative variables.
Results
745 patients were included. Patients had a median age of 51 (13-139) months, 194 (26%) had comorbidities, and 701 (94%) presented with symptomatic disease. Fever was present in 524 (74.8%) patients, respiratory symptoms in 550 (78.5%), followed by gastrointestinal manifestations in 218 (31.1%). X-ray findings were abnormal in 175/362 patients, with interstitial infiltrates being the most common finding, 123 (70.7%). Almost a third of patients (29%) received an antibiotic; ceftriaxone was most frequently prescribed in 123/216 cases. Of 745 patients, 526 (70.8%) were hospitalized, of which 165 (31.4%) required PICU admission. Patients presenting with severe disease and requiring PICU admission we more likely to have a comorbidity, 128 (22%) vs. 66 (40%), p<0.001. Mucocutaneous findings or adenitis were more frequently described in severe cases, 19 (11.5) vs. 18 (5.0%), p=0.007. Regarding laboratory results, low lymphocytes 2445 vs. 1676 (p<0.001) and low platelets 294,000 vs. 250,000 (p=0.0002) were most common in patients with severe disease. The proportion of patients with lymphocytopenia was also higher in those with severe disease, 39% vs. 52% p= 0.010. Not surprisingly, antibiotic usage (broad and narrow spectrum) was higher in patients admitted to the PICU (32 vs. 16.5%) p=0.001, despite no significant difference in the frequency of bacterial coinfection (5.56% vs. 9.7% p=0.081) when compared to patients with non-severe disease. Specific treatment strategies were more frequent in PICU patients (39.1% vs. 72.1%) p<0.001, and steroids were the most frequently used drug, 35.2% vs. 70.7% (p<0.001). Table 1.
Conclusions
Regardless of the variant, COVID-19 is an important cause of hospitalization in children. Fever, respiratory and gastrointestinal symptoms are the most frequent manifestations in children. Despite the low frequency of bacterial coinfection, a high proportion of antibiotic usage is described. Compared to recent publications, mucocutaneous involvement, lower lymphocyte and platelet counts, and higher inflammatory markers were more frequently found in admissions to the PICU. Currently, with higher vaccine coverage and more comprehensive knowledge of the disease, optimization of pediatric COVID-19 management is expected, especially concerning antibiotic use. It is essential to continue multicenter surveillance of the behavior of COVID-19 in the pediatric population.
Anodic porous alumina (AAO) templates, also known as nanoporous anodic alumina (NAA) platforms or membranes, are widely used as templates in nanoscience and nanotechnology. During fabrication, ...characterization, or device performance, they are sometimes exposed to heat treatments. We have found that the thermal conductivity of AAO is strongly dependent on the temperature at which the sample is exposed, showing a certain variation even at very low temperatures, such as 50 °C. Because of this, we have performed a study of the thermal conductivity (
k
) variation for different AAO templates using 3ω-Scanning Thermal Microscopy (3ω-SThM) as a function of the annealing temperature. The AAOs studied in this work were produced in the most common electrolytes - sulfuric, oxalic, and phosphoric acids, and heated from RT up to 1100 °C. To explain these variations in an in-depth and enlightening manner, structural characterization of the different nanoporous aluminas has been performed. It is shown that even at low temperatures, below 100 °C, the AAOs lose water, which explains the reduction of their thermal conductivity. The minimum value of thermal conductivity can be found for AAO samples prepared in sulfuric acid and heated at 100 °C (0.78 ± 0.19 W m
−1
K
−1
), which corresponds to a 50% reduction from the original value. It has also been found that for AAO annealed above 950 °C, the variations in the thermal conductivity are mainly related to phase transitions from amorphous to crystalline alumina and gas evolution of CO
2
, or SO
2
and SO, depending on the electrolyte used during the anodization. This is also an indication that the counter ions are trapped inside the alumina template during the anodization process. And, their presence determines the crystallization temperatures at which the different crystalline phases are formed. And so, the variations in thermal conductivity are measured. The thermal conductivity values of the AAO can reach values as high as 4.82 ± 0.36 W m
−1
K
−1
for AAO samples prepared in oxalic acid and heated up to 1300 °C. We consider that the understanding of the changes in their thermal conductivity can explain the different values in the thermal conductivity of the AAO template found in the literature and draw some attention to the importance of the history of the AAO platforms that are to be used or measured, since it may change the final thermal properties of the template or device.
An important variation in the thermal conductivity of porous alumina membranes has been observed from RT up to 1300 °C. This is due to the water loss at low temperatures or phase transitions at higher temperatures.
En Colombia, varias comunidades, cuyo acceso al servicio de agua potable es limitado o precario, recolectan aguas lluvias para diferentes usos domésticos. Este artículo presenta los resultados de ...análisis de calidad de aguas lluvias de escorrentía sobre tejados, en barrios de Kennedy (Bogotá) y del municipio de Soacha (Cundinamarca), con miras a evaluar su adaptabilidad para satisfacer usos domésticos, en dichas comunidades. De acuerdo a los resultados obtenidos, el agua muestreada no es apta para ninguno de los usos de las comunidades estudiadas, debido principalmente a altos valores de turbiedad y altas concentraciones de Sólidos Suspendidos Totales, Demanda Bioquímica de Oxígeno a los cinco días y metales pesados; sin embargo, se detectó una alta variabilidad espacial y temporal de los resultados, así como en función de los materiales de los techos de las casas. En algunos casos y condiciones especiales, el agua lluvia de escorrentía sobre tejados, se podría adaptar para ser utilizada como fuente alternativa para satisfacer algunos usos domésticos.
Introducción. En Colombia la obesidad es un problema de salud pública que el gobierno debe abordar mediante iniciativas de acción de política (IAP), es decir, acciones gubernamentales que pueden ...estar implementadas o no.
Objetivo. Identificar, mediante la metodología del marco NOURISHING, las IAP y las evaluaciones de acción de política (EAP) contra la obesidad formuladas en Colombia desde 2005.
Materiales y métodos. La búsqueda se realizó entre marzo y agosto de 2019, con una actualización en agosto de 2020, de la siguiente manera: IAP: en sitios web del gobierno y de organizaciones de la sociedad civil; EAP: en PubMed, SciELO y el repositorio Sinergia. Las IAP se clasificaron en las áreas de política de NOURISHING.
Resultados. Se encontraron 42 IAP con 82 líneas de actuación: 16 (24 líneas) implementadas, 17 (37 líneas) no implementadas, y 9 (21 líneas) sin información suficiente para determinar su implementación (21 líneas). Las IAP abordan todas las áreas de política del marco NOURISHING. Las IAP implementadas tienen más líneas en el área “Habilitar acciones multisectoriales y de suministro de alimentos” (8/24), mientras que las no implementadas, en “Restringir la publicidad de alimentos y bebidas” (10/37). Se identificaron 13 EAP, donde la mayoría fueron sobre IAP en seguridad alimentaria orientadas al suministro de alimentos (4/13).
Conclusiones. Colombia tiene IAP que abarcan todas las áreas de política del marco NOURISHING. Las IAP implementadas se enfocan en el suministro de alimentos y las no implementadas, en medidas regulatorias. Urge promulgar IAP regulatorias, con una evaluación y seguimiento adecuados, que permitan mejorar los hábitos alimentarios de la población colombiana y prevenir la tendencia creciente de obesidad.
Self-standing Bi₂Te₃ networks of interconnected nanowires were fabricated in three-dimensional porous anodic alumina templates (3D⁻AAO) with a porous structure spreading in all three spatial ...dimensions. Pulsed electrodeposition parameters were optimized to grow highly oriented Bi₂Te₃ interconnected nanowires with stoichiometric composition inside those 3D⁻AAO templates. The nanowire networks were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Raman spectroscopy. The results are compared to those obtained in films and 1D nanowires grown under similar conditions. The crystalline structure and composition of the 3D Bi⁻Te nanowire network are finely tuned by controlling the applied voltage and the relaxation time off at zero current density during the deposition. With this fabrication method, and controlling the electrodeposition parameters, stoichiometric Bi₂Te₃ networks of interconnected nanowires have been obtained, with a preferential orientation along 1 1 0, which makes them optimal candidates for out-of-plane thermoelectric applications. Moreover, the templates in which they are grown can be dissolved and the network of interconnected nanowires is self-standing without affecting its composition and orientation properties.
Scanning thermal microscopy (SThM) is a powerful technique for thermal characterization. However, one of the most challenging aspects of thermal characterization is obtaining quantitative information ...on thermal conductivity with nanoscale lateral resolution. We used this technique with the cross-point calibration method to obtain the thermal contact resistance,
R
c
, and thermal exchange radius,
b
, using thermo-resistive Pd/Si
3
N
4
probes. The cross-point curves correlate the dependence of
R
c
and
b
with the sample's thermal conductivity. We implemented a 3
ω
-SThM method in which reference samples with known thermal conductivity were used in the calibration and validation process to guarantee optimal working conditions. We achieved values of
R
c
= 0.94 × 10
6
± 0.02 K W
−1
and
b
= 2.41 × 10
−7
± 0.02 m for samples with a low thermal conductivity (between 0.19 and 1.48 W m
−1
K
−1
). These results show a large improvement in spatial resolution over previously reported data for the Wollaston probes (where
b
∼ 2.8 μm). Furthermore, the contact resistance with the Pd/Si
3
N
4
is ∼20× larger than reported for a Wollaston wire probe (with 0.45 × 10
5
K W
−1
). These thermal parameters were used to determine the unknown thermal conductivity of thermoelectric films of Ag
2
Se, Ag
2−
x
Se, Cu
2
Se (smooth
vs.
rough surface), and Bi
2
Te
3
, obtaining, in units of W m
−1
K
−1
, the values of 0.63 ± 0.07, 0.69 ± 0.15, 0.79 ± 0.03, 0.82 ± 0.04, and 0.93 ± 0.12, respectively. To the best of our knowledge, this is the first time these microfabricated probes have been calibrated using the cross-point method to perform quantitative thermal analysis with nanoscale resolution. Moreover, this work shows high-resolution thermal images of the
V
1
ω
and
V
3
ω
signals, which can offer relevant information on the material's heat dissipation.
Scanning thermal microscopy is a powerful technique to study thermal properties at the nanoscale. Pd/Si
3
N
4
thermo-resistive probes has largely improved the spatial resolution compared to Wollaston probes, facilitating the analysis of nanoscale thermal heterogeneities.
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