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Self-healing properties of cement-based and alkali-activated slag-based fiber-reinforced composites
Nguyễ,n, Huy Hoà,ng,Choi, Jeong-Il,Song, Keum-Il,Song, Jin-Kyu,Huh, Jungwon,Lee, Bang Yeon Elsevier 2018 Construction and Building Materials Vol.165 No.-
<P><B>Abstract</B></P> <P>This paper presents an experimental study of the self-healing properties of cement-based and alkali-activated slag-based fiber-reinforced composites with controlled crack width. Two types of binder, i.e. cement and alkali-activated slag-based polyethylene fiber-reinforced composites with identical water-to-binder ratios, were designed. Compressive strength and uniaxial tension tests were performed to measure the mechanical properties of the composites, and the self-healing performance was investigated by observation of the crack width and by measuring resonance frequency. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were also adopted to analyze the morphology and chemical composition of the healing materials. The test results showed that alkali-activated slag-based composites have advantages compared to cement-based composites in terms of a reduction of relative crack width; however, cement-based composites have a higher resonant frequency recovery than alkali-activated slag-based composites. It is also observed that calcium carbonate is the dominant healing material of cement-based and slag-based composites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The self-healing properties of cement-based and slag-based fiber-reinforced composites are investigated. </LI> <LI> Slag-based composites have advantages in terms of a reduction of relative crack width. </LI> <LI> Slag-based composites have low resonant frequency recovery. </LI> <LI> Calcium carbonate is the dominant healing material for cement-based and slag-based composites. </LI> </UL> </P>
Ly, Nguyễ,n Hoà,ng,Nguyen, Thanh Danh,Joo, Sang-Woo Elsevier 2018 Colloids and Surfaces B Vol.171 No.-
<P><B>Abstract</B></P> <P>Zidovudine (AZT) adsorbed on colloidal gold nanoparticles (AuNPs) undergoes pH-induced conformational changes according to spectral changes in surface-enhanced Raman scattering (SERS). In acidic pH values conditions, AZT assumes the C<SUB>(2ʹ)</SUB>-endo conformer, which binds more weakly to AuNPs than under neutral and alkaline conditions. In this study, density functional theory (DFT) calculations were performed; these calculations also supported the conformation-dependent binding energies. A lactobionic acid-conjugated PEGylated (LA-PEG-SH; molecular weight: 3400) unit was attached to AuNPs to target the asialoglycoprotein receptors overexpressed in hepatocarcinoma cells of Huh7 and SNU-354. The loading efficiency values were measured to be ∼44–49% and ∼66–68% at pH values of 7 and 10, respectively. At an acidic pH of 4.5, they were estimated to be only ∼35–38%. pH-dependent spectral changes were observed for the asymmetric stretching modes of the azide (NNN) bands at 2183 cm<SUP>−1</SUP> (in acidic pH) and at 2129 cm<SUP>−1</SUP> (in basic pH). Cell viability analysis indicated that the LA-PEG-capped, AZT-coated AuNPs specifically inhibited the growth of the targeted hepatocarcinoma cells with better cancer cell killing efficiency than was observed with the LA-PEG-capped AuNPs without AZT.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zidovudine bound to colloidal gold nanoparticles undergoes pH-induced conformational changes. </LI> <LI> At acidic pH values, zidovudine assumes the C<SUB>(2ʹ)</SUB>-endo conformer, which binds weakly to gold. </LI> <LI> Cytotoxicity analysis indicated that the complex could inhibit the growth of the targeted hepatocarcinoma cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Conformational change-induced drug release of zidovudine from gold nanoparticles in acidic pH conditions was studied by Raman spectroscopy and density functional theory.</P> <P>[DISPLAY OMISSION]</P>