Search results for "article"

Learning to read for the first time as adult immigrants in Finland : Reviewing pertinent research of low-literate or non-literate learners’ literacy …

2018

Against the backdrop of increasing global humanitarian migration to highly literate countries and the resulting necessity and challenge to provide language and literacy education to non-literate or low-literate adult second language (L2) learners, this article calls for more research on a new population of late literacy learners, particularly in Finland. The article begins by outlining the pressing necessity for research on this special group of L2 learners who has traditionally been ignored by Second Language Acquisition (SLA) research. It will then go on to illuminate essential components of developing reading literacy, drawing on relevant previous research on pre-literates. Further, the …

Structural properties of core and surface of silica nanoparticles investigated by Raman spectroscopy

2013

We studied the experimental Raman spectra of various commercial silica nanoparticles of average diameter from 7 to 40 nm and specific surface from 50 to 380 m^2/g. We found that the peculiarities of the particles Raman spectra systematically depend on their specific surface. In detail, the peak position of the R band at about 440 cm ^-1 shifts towards high wavenumbers following an almost linear dependence on the specific surface. Similarly, the amplitudes of the D1 and D2 bands, at about 495 and 605 cm ^-1, respectively, increase linearly with the same quantity. Our results are interpreted in the frame of the shell model for the nanoparticles clarifying that the network of the core of the n…

Thioflavin-T doped silica nanoparticles by basic-catalyzed sol-gel synthesis

2014

We developed a basic-catalyzed sol-gel procedure that allows to synthesize silica nanoparticles functionalized with Thioflavin-T (ThT). During the synthesis, the formation of the doped silica nanoparticles was monitored by absorbance spectra indicating that the catalyst does not cause the total hydroxylation of the dye. Fluorescence measurements carried out on the ThT doped silica nanoparticles proved the attachment of ThT on silica and Raman spectroscopy provided information about the dye structure.

Visible luminescence of nanosilica: slow and fast contributions

2010

Luminescence properties induced by sintering of silica nanoparticles

2014

The effect of sintering on the optical properties of silica nanoparticles, a mean diameter of ~14 nm, are investigated by absorption and luminescence experiments. The sintering is induced by a thermal treatment of 1000 °C for 272 hours; after that the sample is transparent, and emits a bright luminescence under UV excitation. Time resolved photoluminescence spectra excited by a tunable laser source allows to evidence four bands around 2.0 eV, 2.4 eV, 2.7 eV and 3.4 eV, peculiar to defects induced by the sintering.

Bright blue emission of synthesized silica nanoparticles conferred by surface defects

2013

Charge Transport Mechanisms in Heavy-Ion Driven Leakage Current in Silicon Carbide Schottky Power Diodes

2016

Under heavy-ion exposure at sufficiently high reverse bias voltages silicon carbide (SiC) Schottky diodes are observed to exhibit gradual increases in leakage current with increasing ion fluence. Heavy-ion exposure alters the overall reverse current-voltage characteristics of these diodes, leaving the forward characteristics practically unchanged. This paper discusses the charge transport mechanisms in the heavy-ion damaged SiC Schottky diodes. A macro model, describing the reverse current-voltage characteristics in the degraded SiC Schottky diodes is proposed. peerReviewed

Wpływ dodatku bioaktywnych mikrocząstek srebra na właściwości użytkowe tynków mineralnych

2013

Aktywność mikroorganizmów, a przede wszystkim bakterii i grzybów w istotny sposób wpływa na swoiste cechy i wartość użytkową materiałów budowlanych. Jest to rodzaj korozji biologicznej, stanowiącej szczególny przypadek korozji chemicznej, która powoduje obniżenie lub utratę właściwości użytkowych materiału. Oprócz korozji biologicznej, grzyby mogą również stwarzać zagrożenie dla zdrowia użytkowników zasiedlonych obiektów. Ich toksyczne oddziaływanie na zdrowie ludzi i zwierząt uważa się za znacznie groźniejsze w skutkach od biokorozji materiałów. Stosowane obecnie środki biobójcze w postaci biocydów i nanocząstek srebra również mogą stanowić zagrożenie. W prezentowanej pracy przedstawiono w…

Impact of Different Washing Conditions on the Release of Ag Species from Textiles

2016

The paper investigates the Ag release from textiles (socks available in shops, cotton and viscose filled with Ag nanoparticles–AgNPs) into a washing solution under different conditions. The released Ag amount depended on various factors, such as test media (chemical composition, temperature and water volume), metal contents, and textile impregnation conditions. Furthermore, it turned out that the textile type and colour were the main parameters affecting the Ag release. The Ag concentration in the washing solution ranged between 0.015 μg/l and 4.44 μg/l (socks) and between 0.61 μg/l and 103 μg/l (AgNPs–filled cotton). The total Ag percentage released into water during one washing varied con…

Temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes uploaded with silver nanoparticles

2022

New temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes (HNTs) containing grafted polymer brushes with silver nanoparticles have been successfully fabricated. We used a three steps process including synthesis of the initiating coatings onto HNTs surface, fabrication of the POEGMA – poly(oligo(ethylene glycol)ethyl ether methacrylate) grafted brushes and synthesis of the silver nanoparticles (AgNPs). The synthesis and properties of hybrid nanomaterials were studied by FT-IR, TGA and DLS methods. It is shown that the introduction of AgNPs, formed from 0.005 M AgNO3 solution leads to a significant reduction of low critical solution temperature (LCST) of the polym…