171 research outputs found
Práticas de literacia familiar em benguela (angola): Um estudo exploratório.
As investigações mostram que a aprendizagem da linguagem escrita começa muito
antes do ensino formal e que as práticas e o ambiente de literacia familiar influenciam a literacia
emergente e o desenvolvimento da linguagem escrita. Mas, se estes estudos são desenvolvidos no
Ocidente, em África pouco se tem feito e em Angola não se conhece nenhum estudo. Com base nos
estudos existentes, em diversos contextos culturais, verifica-se que a literacia familiar existe,
podendo as práticas variar no tipo e frequência uma vez que o que se passa num contexto, pode não
ser igual ao que se passa noutra realidade cultural diferente. Neste sentido este trabalho, procura
caraterizar as práticas e o ambiente familiar de literacia em 11 famílias de Benguela com um filho a
frequentar o início da escolaridade. Os dados foram recolhidos através de uma entrevista informal
aos pais. Os resultados mostram que as práticas de literacia familiar são essencialmente práticas
formais, muito ligadas à escola e às tarefas escolares. No mesmo sentido verificámos que a
responsabilidade pela aprendizagem da linguagem escrita é atribuída à escola, e a explicadores.
Apesar de surgirem algumas referências do uso da literacia associado a práticas religiosas, poucas
referências foram feitas a práticas informais ou lúdicas. Foi clara a quase inexistência de materiais
de leitura (jornais, livros, revistas) para além dos escolares. A falta de tempo, a escassez de
bibliotecas públicas e livrarias, a falta dos recursos financeiras para aquisição do material de literacia
e a iliteracia foram apontados como obstáculos para o desenvolvimento de outro tipo de práticasinfo:eu-repo/semantics/publishedVersio
Versatile Fabrication of Ultralight Magnetic Foams and Application for Oil–Water Separation
Ultralow-density (<10 mg cm<sup>–3</sup>) materials have many important technological applications; however, most of them were fabricated using either expensive materials or complicated procedures. In this study, ultralight magnetic Fe<sub>2</sub>O<sub>3</sub>/C, Co/C, and Ni/C foams (with a density <5 mg cm<sup>–3</sup>) were fabricated on the centimeter scale by pyrolyzing commercial polyurethane sponge grafted with polyelectrolyte layers based on the corresponding metal acrylate at 400 °C. The ultralight foams consisted of 3D interconnected hollow tubes that have a diameter of micrometer and nanoscale wall thickness, forming hierarchical structures from macroscopic to nanometer length scales. More interesting was that the wall thickness and morphology of the microtubes could be tuned by controlling the concentrations of acrylic acid and metallic cations. After modification with low-surface-energy polysiloxane, the ultralight foams showed superhydrophobicity and superoleophilicity, which quickly and selectively absorbed a variety of oils from a polluted water surface under magnetic field. The oil absorption capacity reached 100 times of the foams’ own weight, exhibiting one of the highest values among existing absorptive counterparts. By controlling the composition and conformation of the grafted polyelectrolyte layers, the present approach is extendable to fabricate a variety of ultralow-density materials desirable for absorptive materials, electrode materials, catalyst supports, <i>etc</i>
Mussel-Inspired Self-Healing of Ultralight Magnetic Frameworks
Ultralight materials have many important
applications, but most
of them are unable to spontaneously recover their microstructure and
functions after physical damage or abuse. Here we report an ultralight
magnetic framework that can repair its broken microstructure autonomously
via a mussel-inspired strategy. The self-healable framework consists
of three-dimensionally (3D) interconnected Fe<sub>3</sub>O<sub>4</sub>/C microtubes wrapped with nanoshells of nitrocatechol-substituted
chitosan. The framework spontaneously recovers its configuration integrity
and mechanical properties during all 6 breaking/healing cycles through
pH-induced coordination between Fe<sup>3+</sup> and catecholic moieties.
On the basis of the self-healable property, the framework can even
be tailored into complicated patterns. The investigation offers a
strategy to fabricate multifunctional ultralight materials with a
self-healable property and tailorability, which have potential applications
in adsorption, energy-storage, and catalysis, and so on
Arsenic Incorporation in Synthetic Struvite (NH<sub>4</sub>MgPO<sub>4</sub>·6H<sub>2</sub>O): A Synchrotron XAS and Single-Crystal EPR Study
Struvite,
a common biomineral and increasingly important fertilizer
recovered from wastewater treatment plants, is capable of sequestering
a wide range of heavy metals and metalloids, including arsenic. Inductively
coupled plasma mass spectrometric (ICPMS) analyses and microbeam synchrotron
X-ray fluororescence (μ-SXRF) mapping show that struvite formed
under ambient conditions contains up to 547 ± 15 ppm As and that
the uptake of As is controlled by pH. Synchrotron As K-edge XANES
spectra measured at 20 K show that As<sup>5+</sup> is the predominant
oxidation state in struvite, irrespective of Na<sub>2</sub>HAsO<sub>4</sub>·7H<sub>2</sub>O or NaAsO<sub>2</sub> as the source for
As. Modeling of As K-edge EXAFS data suggest that local structural
distortion associated with the substitution of As<sup>5+</sup> for
P<sup>5+</sup> in struvite reaches up to 3.75 Å. Single-crystal
electron paramagnetic resonance (EPR) spectra of gamma-ray-irradiated
struvite disclose five [AsO<sub>3</sub>]<sup>2–</sup> radicals
and one [AsO<sub>4</sub>]<sup>2–</sup> radical. These arsenic-centered
oxyradicals are all readily attributed to form from diamagnetic [AsO<sub>4</sub>]<sup>3–</sup> precursors during irradiation, providing
further support for exclusive incorporation and local structural expansion
beyond the first shell of As<sup>5+</sup> at the P site in struvite
Forecasting Directions, Dates, And Causes of Future Technological Revolutions concerning the Growth of Human Capital
Technology forecasting is an important and critical issue that determines the starting point of planning and is considered as a management tool directly related to the future. In the previous research items, the development of renewable energy technologies was of concern. Moreover, due to the increasing need of countries to produce electricity and facing the lack of resources, this research focuses on forecasting photovoltaic technology. Accordingly, in this paper, for technological research in the field of solar energy, the patents extracted from one of the most famous renewable energy databases in the United States (US patent database) between 200 and 2020 were examined. Next, research gaps were analyzed by using the artificial neural network clustering method and also by analyzing covered and uncovered compounds. The results show that in the future, photovoltaic technology research will move towards the third generation of technology (organic materials) as well as focus on environmental parameters and their effects on the performance of photovoltaic systems.</p
Time series of grass cover, annual rainfall, and data to trends of early warning signals for critical and stochastic transitions needed to produce Figure 3
"data_cn.csv" includes data of gras cover and annual rainfall.
"Chenetal-theory-ews-cric-stochastic.nb" computes trends of early warning signals for critical and stochastic transitions needed to produce Figure 3 of the manuscript
Effect of a cell recycle strategy on accumulation of acetate and glucose conversion rate of L-tryptophan in L-tryptophan fermentation by TRTHBPA (<i>P</i><0.05).
<p>Effect of a cell recycle strategy on accumulation of acetate and glucose conversion rate of L-tryptophan in L-tryptophan fermentation by TRTHBPA (<i>P</i><0.05).</p
Analysis of process parameters in L-tryptophan production by using the strain TRTHB (<i>P</i><0.05).
<p>Analysis of process parameters in L-tryptophan production by using the strain TRTHB (<i>P</i><0.05).</p
Supporting Information from Fluorimetric detection of reserpine in mouse serum through online post-column electrochemical derivatization
Supplementary materials included figures that made the work complete
Why Superhydrophobicity Is Crucial for a Water-Jumping Microrobot? Experimental and Theoretical Investigations
This study reported for the first time a novel microrobot
that
could continuously jump on the water surface without sinking, imitating
the excellent aquatic locomotive behaviors of a water strider. The
robot consisted of three supporting legs and two actuating legs made
from superhydrophobic nickel foam and a driving system that included
a miniature direct-current motor and a reduction gear unit. In spite
of weighing 11 g, the microrobot jumped 14 cm high and 35 cm long
at each leap. In order to better understand the jumping mechanism
on the water surface, the variation of forces exerted on the supporting
legs was carefully analyzed and calculated based on numerical models
and computational simulations. Results demonstrated that superhydrophobicity
was crucial for increasing the upward force of the supporting legs
and reducing the energy consumption in the process of jumping. Although
bionic microrobots mimicking the horizontal skating motions of aquatic
insects have been fabricated in the past years, few studies reported
a miniature robot capable of continuously jumping on the water surface
as agile as a real water strider. Therefore, the present finding not
only offers a possibility for vividly imitating and better understanding
the amazing water-jumping capability of aquatic insects but also extends
the application of porous and superhydrophobic materials to advanced
robotic systems
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