Calcium Chloride, Anhydrous

For the determination of the fragmentation patterns, we adapted a procedure described in the literature.13 Individual VOC solutions were prepared in de‐ionized water at concentrations ranging from 0.03 to 1% (v/v) for the aldehydes and fatty acids and at 100 mg/L for the phenols. A 500‐mL glass bottle, equipped with a Drechsel head, was filled with 100‐mL de‐ionized water and kept in a water bath at 37°C. A flow of clean air was generated by means of a pump, connected to a hydrocarbon trap (Supelco Supelpure HC, Sigma Aldrich). An airflow of approximately 500 sccm was applied to the bottle. Measurements were conducted employing a commercial PTR‐MS instrument (PTR‐TOF 1000, Ionicon Analytik GmbH, Innsbruck, Austria). At the beginning of the measurement, drift tube conditions were: temperature 110°C, pressure 2.30 mbar, and voltage 600 V, resulting in an E/N of 144 Td (1 Townsend = 10⁻¹⁷ V cm²). The PTR‐MS inlet was connected to the bottle head with a flow of 40 sccm, letting the excess flow out by means of a t‐piece. The inlet consisted of a PEEK tubing heated at 110°C. Once temperature and signal were stable, 1 mL of standard solution was added to the bottle by means of a syringe: several mass peak traces rapidly increased following addition and subsequently decreased, showing a time evolution pattern that was characteristic for each parent compound. This allowed to attribute unambiguously, for each compound and set of conditions, parent ion, and relative fragments or adducts. After standard solution addition and the initial equilibration phase, E/N was decreased in a stepwise fashion, with 1‐min steps. The voltage applied were as follows: 600, 550, 500, 450, 400, 350, 300, and 200 V, resulting in E/N = 144, 132, 120, 108, 96, 84, 72, and 48 Td, respectively. At the end of each experiment, the reagent ion was switched, and a new measurement was started using a fresh bottle, employing the same protocol and standard solution.
The effect of the reduction in air water content on fragmentation patterns was studied by employing the same experimental setup. The measurement was started using water‐saturated air and setting the instrument drift voltage at 350 V. Once steady conditions were reached, the switch to dry conditions were achieved by connecting a CaCl₂ cartridge in between the Drechsel bottle and the PTR‐MS inlet. The cartridge consisted of a 10‐mL glass vial equipped with a PTFE septum, filled with anhydrous calcium chloride (CaCl₂, Sigma‐Aldrich). After cartridge connection, approximately 30 seconds were required to re‐establish steady conditions. Since the volume of the cartridge was relatively low compared with the inlet flow, no measurable retention of analytes onto the cartridge could be observed. Measurement was then continued for approximately 1 minute, allowing to establish fragmentation patterns under dry conditions.

The apparatus designed for hygrotactic studies was made of a culture dish (ϕ55 mm; height, 10 mm) covered with a 100 mesh nylon net. 50 flies aged between four and six days were placed inside the apparatus, and were then dehydrated in a chamber with anhydrous calcium chloride (25°C; relative humidity, ~10%) for the times indicated. The apparatus with dehydrated flies was then placed above a water-containing vial (ϕ10 mm). The distance between the nylon net and water surface was 1 mm. The locomotion of dehydrated flies was record by a digital camera. Hygrotactic behavior assays were performed at 25°C with a relative humidity of 40~50%.
To quantify the hygrotactic behavior, we defined a circular region (ϕ25 mm) in the center of the dish and counted the number of flies in the region during the test. The aggregation values at different time points during the test were calculated using the following formula: (NO_t—NO₀) / NO_sum. Here, NO_t is the number of flies in the defined region at the moment; NO₀ is the number of flies in the region at the beginning of test; the total number of flies (NO_sum) in our tests was 50. The hygrotaxis index is defined as the average of all aggregation values measured at five-second intervals within each five-minute test.
To examine the behavioral responses towards other volatile compounds in dehydrated flies, water was replaced by selected volatile compound. Other experimental conditions were the same as described above.
Unless otherwise indicated, flies used in the hygrotaxis assays were female.

In a 100 mL beaker, 50 g anhydrous calcium chloride (particle size of 2 mm) was added. Uniform smooth films without holes or wrinkles were selected. Subsequently, they were measured to determine their thicknesses, sealed at the mouth with molten paraffin, placed in a dryer with 100% relative humidity, measured at 25 °C, and removed from the dryer, and weighed every 24 h. Three parallel experiments were continuously performed for one week, and the results were presented as the arithmetic mean of each group.
WVP=Δm×d/(A×t×ΔP),
where WVP is the water permeability coefficient (g·mm/m²·d·KPa), Δm is the steady mass increment (g), d is the film thickness (mm), A is the effective measured area (m²), T is the time interval (days) of the measurement, and ΔP is the vapor pressure difference (KPa) on both sides of the sample.
The film sealing was measured by placing approximately 5 mL salad oil in a test tube and then sealing it with the film. The oil was further placed upside down on a filter paper for a week to calculate the average oil permeability coefficients of the three samples.
Poil=Δm×d/A×T,
where P_oil is the oil permeability coefficient (g·m/m²·d), Δm is the change in the filter paper quality (g), d is the film thickness (mm), A is the film area (m²), and T is the placement time (days).

THC (lot no. ZL20180816, purity 99.08%) was obtained from the Zhonglan industry (Zhonglan Industry, Shandong, China). TDG (purity 99.71%) was synthesized and characterized as previously reported [21 (link)]. Tetrahydrocurcumin-monoglutaric acid (TMG) was synthesized and assayed for purity (see Supplementary Materials, Figure S1). All reagents were at least of analytical grade and were procured from commercial sources. Formic acid was obtained from Carlo Erba (Val de Reuil, France). The HPLC grade of acetonitrile (ACN) was purchased from Fisher Scientific (Soul, South Korea). Hydrochloric acid and sodium hydroxide were obtained from QRëc (Auckland, New Zealand) and Carlo Erba (Val de Reuil, France), respectively. Bile, bovine serum albumin, lipase, mucin, pancreatin, α-amylase, and pepsin were obtained from Sigma-Aldrich Co., Ltd. (St. Louis, MO, USA). Calcium chloride anhydrous powder was purchased from Carlo-Erba (Val de Reuil, France). The ultrapure water (18.2 MΩ-cm) used throughout the study was produced in-house using a Milli-Q^® integral water purification system (Millipore, S.A.S, France).

The soil pH was measured in a soil/deionized water slurry at a ratio of 1:2.5 using a pH-EC meter (Accumet Excel XL60; Fisher Scientific Inc., Hampton, NH, USA). The available phosphorus in soil samples was extracted using hydrochloric acid in ammonium fluoride and its content determined using molybdenum–antimony anti-colorimetry. Soil nitrate-nitrogen (NO₃⁻-N) and ammonium-nitrogen (NH₄⁺-N) were extracted using 0.01 mol/L anhydrous calcium chloride and quantified using a flow injection autoanalyzer. The soil total carbon content (TC), total nitrogen content (TN), and total sulfur content were measured using an elemental analyzer (Vario MAX CNS; Elementar Analysensysteme GmbH, Berlin, Germany). Heavy metals such as lead (Pb), chromium (Cr), zinc (Zn), nickel (Ni), copper (Cu), Cadmium (Cd) and arsenic (As) were digested by microwave-assisted acid digestion using trace-pure nitric acid (2.5 mL), hydrofluoric acid (1.5 mL), and a closed-vessel high-pressure microwave digester–Multiwave GO (Anton Paar, Graz, Austria), according to Chen et al. [32 (link)]. Finally, the metal concentrations were determined by inductively coupled plasma optical emission spectrometry (Optima 7000DV; PerkinElmer, Waltham, MA, USA). Physiochemical properties of sampled soils are presented in Table 1.