Su8010 field emission scanning electron microscope fe sem

HITACHI SU 8010 Field Emission Scanning Electron Microscope (FE-SEM) (HITACHI, Tokyo, Japan) was used to analyze the morphology of the precipitates and capsules in the in vitro tests and to obtain a clear visualization of the behavior of the CaAlg capsules after crack initiation and to observe the morphology of the precipitates in the cement paste and mortars. Conductive carbon tape was placed on the sample holder before placing the samples. Then, the samples were coated with platinum by sputtering to increase the conductivity of the samples. An accelerating voltage between 3 and 5 kV was used. SEM images were taken from capsules exposed to the cement environment in vitro, as well as from capsules placed in cement paste and mortars after self-healing.

Waters-1515 gel permeation chromatograph (GPC, Waters, MI, USA) was used to evaluate the molecular weight of the products. Fourier transform infrared (FT-IR) spectra were obtained using a Vertex 70v FT-IR spectrophotometer (Bruker, Karlsruhe, Germany). ¹H NMR spectra were recorded on an ASCEND 400 spectrometer (Bruker, Karlsruhe, Germany). X-ray diffraction (XRD) patterns were measured using a D8 advance X-ray diffractometer (Bruker, Karlsruhe, Germany); the relative intensity was recorded in the scattering range (2θ) of 5°–90°. X-ray photoelectron spectroscopy (XPS) spectra were obtained using PHI 5000CESCA System surface analysis equipment (PHI Co., Chanhassen, MN, USA) with Mg-K_α X-ray source (hγ = 1253.6 eV). Ultraviolet-Visible (UV-Vis) spectra were recorded in the range of 300–600 nm using UV2310II UV-Vis spectrophotometer (INESA, Shanghai, China). JEOL-2100F transmission electron microscopy (TEM, JEOL, Tokyo, Japan) was used to investigate the microstructure and size distribution of the Ag NPs. The size distribution was statistically analyzed for 300 randomly selected nanoparticles using the public software Image J. Surface morphology was observed via an SU8010 field emission scanning electron microscope (FESEM, Hitachi, Japan).

Samples for the SEM analysis were prepared according to the procedure that had been developed for barley roots^{61 (link)}. In brief, barley roots from seven-day-old seedlings that had been grown in a hydroponic culture in a 1/16 Hoagland medium (control plants) and in a 5 nm AuNPs solution (50 µg/ml concentration) were cut into 1 cm segments and fixed in 3% glutaraldehyde in a 0.1 M sodium phosphate buffer, pH 7.2 (24 h at RT). Next, the samples were washed three times for 15 min each with a phosphate buffer followed by post-fixation in 2% osmium tetraoxide for 2 h at RT. The material was subsequently washed three times in the same buffer and dehydrated in a graded ethanol/water series of 50%, 60%, 70%, 80%, 90%, 95% and 100% (10 min each step). Next, the samples were critical-point dried using carbon dioxide in a Pelco CPD2 apparatus (Ted Pella Inc., Redding, CA, USA) and then mounted on aluminium stubs with double-sided carbon tape and sputter coated with a thin film of gold in a Pelco SC-6 sputter coater (Ted Pella Inc., Redding, CA, USA). The samples were imaged using a Hitachi SU8010 field emission scanning electron microscope FE-SEM (Hitachi High-Technologies Corporation, Tokyo, Japan).