Specord 210 plus

Chemical corrosion testing was performed, by dipping specimens in vanadium (V) and holding them at room temperature for 7 days. The samples were tested each day for changed mass, altered surface morphology, and changed vanadium concentration in the electrolyte. The vanadium concentration was characterized by a UV-Vis spectrophotometer (SPECORD 210 PLUS, ANALYTIK JENA, Jena, Germany). Samples were tested for electrochemical corrosion, by performing cyclic voltammetry using a potentiostat (VersaSTAT 4, AMETEK, Berwyn, PA, USA). The potential was scanned between 0.0 V to 2.0 V, at a scan rate of 5 mV/s. The system testing consisted of three-electrode cells, with the sample (either commercial graphite BP or laminated BP) used as a working electrode. The diameter of the working electrode was 12 mm. A platinum wire was used as a counter electrode. The reference electrode is Ag/AgCl. The electrolyte solution was 1.6 M VOSO₄ in 2.5 M H₂SO₄ [36 (link)]. The functional group on the surface of the sample was characterized by X-ray photoelectron spectroscopy (XPS, AXIS Ultra DLD, Kratos analytical Ltd., Manchester, UK).

Steady-state absorption and fluorescence measurements were carried out on Specord 210 plus (Analytik Jena AG) and Bruins Instruments Omega10 spectrophotometers as well as Spectronics Instruments 8100 and Horiba Jobin-Yvon Fluoromax-4P fluorometers, employing UV-spectroscopic solvents. For all measurements, the temperature was kept constant at 298 ± 1 K and, except where noted, dilute solutions with an absorbance of less than 0.1 at the absorption maximum were used, especially for fluorescence measurements. The latter were performed with a 90° standard geometry. The fluorescence quantum yields (Φ_f) of 1 was determined relative to oxazine 170 in ethanol (Φ_f = 0.58 ± 0.02)^{52 (link)}. The uncertainties of measurement were determined to ± 5 % (for Φ_f > 0.2).

The free radical scavenging activity was measured according to Brand-Williams et al. [76 (link)]. 1,1-diphenyl-2-picrylhydrazyl (DPPH) was used as the source of free radicals. A total of 100 mg of leaf and root material was ground with 2 mL 80% ethanol and the homogenate was centrifuged at 13,000× g at 4 °C for 30 min. Briefly, a freshly prepared DPPH reagent (1.99 mL) and extract solution (0.01 mL) were mixed, and the absorbance was measured at 515 nm (UV-VIS Specord 210 Plus, Analytic Jena, Jena, Germany). For the blank, methanol was used. The free radical scavenging activity was calculated from a standard curve made with known concentrations of Trolox. The results were presented on a dry weight basis as a mean (± SE) of n = 12.

For analysis of lipid peroxidation, MDA leaf material (0.5 g) was homogenized using 5% trichloracetic acid (TCA) (Sigma-Aldrich). The method of Hodges et al. with slight modifications was used to estimate MDA. The homogenates were centrifuged at 13 g for 17 min (centrifuge MPW-351 R) and the supernatant was added to 20% TCA containing 0.5% thiobarbituric acid (TBA) (Alfa Aesar). The homogenate was incubated in a heater at 95 °C for 30 min (Blockthermostat BT 200, Kleinfeld, Labortechnik) and subsequently cooled on ice. The optical density was measured at 532 and 660 nm using a spectrophotometer (Analytik Jena Specord 210 Plus, Analytik Jena, Jena, Germany)). The results were expressed in µmol g⁻¹ FW [63 (link)].

As a colorimetric test to quantify the microgel carbohydrate functionalization degree, the phenol sulfuric acid method was used. A calibration curve with α-d-methylmannose was established by a dilution series of 500, 350, 250, 150, 50, 25 and 0 μM (Supplementary MaterialsFigure S2). To 500 μL of each α-d-methylmannose solution, 250 μL of a 5 mass % phenol solution and 1.5 mL sulfuric acid were added. For carbohydrate quantification of the microgels, 500 μL of a 5 mg mL⁻¹ microgel solution was mixed with 250 μL of a 5 mass % phenol solution, and 1.5 mL 98% sulfuric acid. The mixtures were shaken for 30 min at room temperature. The absorbance was measured at 490 nm with UV–VIS spectroscopy (SPECORD 210 PLUS, Analytik Jena, Jena, Germany)

Antibacterial properties of the samples were investigated using shake flask method against Escherichia coli [21 (link)]. In order to obtain bacteria suspension, E. coli was cultured in Luria Broth (LB) solid medium for 24 h at 37 °C. A representative colony was cultured in LB liquid medium, followed by being incubated with shaking for 24 h at 37 °C. Bacterial cell concentration was estimated by measuring the absorbance of bacteria suspension. The bacteria suspension was diluted until the absorbance value of 600 nm was 0.1. The absorbance value was recorded using a UV-visible spectrophotometer (SPECORD 210 PLUS, Analytikjena, Jena, Germany). In total, 150 μL of bacterial solution was dropped into a conical flask containing 15 mL of liquid medium. Films (diameter = 1 cm) and powders (mass = 50 mg), were dipped into falcon tubes containing the above bacterial solution, respectively. After shaking vigorously in a shaking incubator for 24 h at 37 °C, each diluent was spread onto the agar plate. Finally, viable microbial colonies were counted after incubating the plate for 24 h at 37 °C. The unit of value obtained by the method is colony-forming units (CFU)/cm². Furthermore, the antibacterial activity of the samples was evaluated by the antibacterial rate, which was equal to [(control value − sample value)/control value] × 100% [22 (link)].