Icap 7000

According to previous reports [62 (link)], ion contents in white rice and soil were detected by using a Digital Block Sample Digestion System (LabTech ED54 DigiBlock). The metal ions contents were determined by an Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES, iCAP 7000, Thermo Fisher).

We grinded and homogenized the dried leaf samples and determined total organic carbon (C) and nitrogen (N) concentrations with a C/N elemental analyzer (Vario EL III, Hanau). To obtain the phosphorus (P) concentration, the material was digested with 65% HNO₃ at 195°C for 8 h and then assessed using the ICP‐OES technique (inductively coupled plasma optical emission spectrometry, iCAP 7000, Thermo Fisher Scientific).

Photosynthesis of the leaf and the water content was tested. Net photosynthetic rate, intercellular carbon dioxide concentration and stomatal conductance were measured by a portable photosynthesis system (LI-6800; LI-COR, Lincoln, NE, USA). For leaf chamber environment, chamber temperature, relative humidity and CO₂ concentration were set at 25 °C, 70%, and 400 μmol mol⁻¹·s⁻¹, each experiment was repeated 10 times. MDA content was analyzed through the TAB method (Banga & Lengyel, 1980) with MDA assay kit (sigma). Proline content, antioxidant capacity and ion content were measured as previously described [62 (link)] with test kits (Jiancheng Bioengineering Institute, Nanjing, China). Element content analysis was performed using inductively coupled plasma-optical emission spectrophotometry ICP-OES (ICAP 7000, Thermo Scientific, Waltham, MA, USA).

Soil pH and EC were measured in a 1:2.5 water suspension mixture using a glass electrode pH meter (PHS–2F, INESA, Shanghai, China). The soil water content (SWC) was calculated based on the losses of 20.00 g of fresh soil dried to a constant weight in an oven at 105° C [27 (link)]. SOM was determined using the Walkley–Black method [28 ]. The contents of NH₄⁺–N and NO₃⁻–N in the soil were extracted with 2 M KCl and determined on a continuous segmented flow analyser (AutoAnalyzer Ⅲ, SEAL Analytical, Fareham, UK). Soil TN was detected via the semi-micro Kjeldahl digestion method (Automatic Kjeldahl Apparatus K9860, Hanon, Jinan, China) [29 ]. Soil AP was estimated through extraction with sodium bicarbonate and measured on a spectrophotometer (UV –5500PC, Shjingmi, Shanghai, China) [30 ]. AK was extracted with 1 M ammonium acetate and measured on an Inductively Coupled Plasma–Optical Emission Spectrometer (iCAP–7000, Thermo Fisher, Waltham, MA, USA). The value of CEC was determined using a solution of barium chloride (ISO 11260–1994). To control the analytical quality, reference soil (GBW07413a) from the National Research Centre for the Certified Reference Materials of China was used in the detection processes of all indices [31 (link)]. The detected values of the standard samples fell within their accepted ranges, with a deviation of less than 5%.

Muscle and tumor samples weighing 52–950 mg (average 260 mg) were prepared for quantitative estimation of their iron concentration using inductively coupled plasma optical emission spectrometry ICP-OES (Thermo Scientific iCAP 7000) [21] . Tissues were dried in oven at 60°C for 12 hrs, and then the temperature was raised to 105°C for at least 6 hrs to determine the dry weight. Then the sample was placed in the muffle at 650°C for at least 12 hrs. Then the formed ash was digested with concentrated hydrochloric acid. The amount of iron was calculated from the linear portion of the generated standard curve.

The XPS spectra were acquired using a Nexsa (ThermoFisher Scientific) instrument with a Microfocus monochromatic Al-Kα X-ray source. The HR-TEM was performed on a JEM-F200 (JEOL) electron microscope with 200 kV acceleration voltage. EDS mapping were analyzed by JEOL Dual SDD system with 200 kV. The ICP-OES was measured by iCAP 7000 (Thermo Scientific) to analyze the presence of Pt metal impurities in the catalyst and electrolytes.