## 4 Discussion  
In our previous studies, we demonstrated that under certain conditions, upon the pumping of water through an injector with a peristaltic pump in the drop-by-drop mode at 0.9 mL/min flowrate and a temperature of 38 \({}^{\circ}\)C, an accumulation of charge in the measuring cell has a linear-stepwise character [30]. The temperature of 38 \({}^{\circ}\)C is interesting, owing to the fact that it is near the viscosity-associated characteristic temperature point of water [33; 34]. In the present work, the research on charge accumulation in the flow-based system for atomic force microscopy (AFM)-based fishing has been continued, and the influence of flow rate has been studied in a wide range from 0.9 to 7.2 mL/min has been studied. Tables 1 and 2 summarize the data obtained herein. As seen from Table 1, a linear-stepwise increase in the amount of charge is observed over the entire range of water flow rates. At this point, a tendency for an increase in the amount of charge (\(\Delta q\)) accumulated in the measuring cell during the measurement time upon the transition from the \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & & & & & \\ \hline \hline  & Parameter & 0.9 mL/min & 1.8 mL/min & 2.7 mL/min & 3.6 mL/min & 5.4 mL/min & 7.2 mL/min \\ \hline  & Rate of charge accumulation in & & & & & & \\  & the cell (\(\Delta q\)/\(\Delta t\)) for linear section & & & & & & \\  & of a curve, & & & & & & \\  & nC/min & & & & & & \\ \hline  & Gradient of charge accumulation & & & & & & \\
2 & in the cell (\(\Delta q\)/\(\Delta t\)) for jumps, & 5 & 4 to 8 & 8 & 8 to 14 & 8 & 8 \\  & nC/min & & & & & & \\ \hline  & Amount of charge (\(\Delta q\)) & & 2.0 to 3.1 & 1.7 to 2.5 & 2.0 & 2.0 to 3.6 & 2.0 & 2.0 \\
3 & accumulated as a result of all & (1 to 2 jumps) & (1 jump) & (1 jump) & (1 to 2 jumps) & (1 jump) & (4 jumps) \\  & jumps in a curve, nC & & & & & & \\ \hline  & Absolute value of charge (\(\Delta q\)) & & & & & & \\
4 & accumulated in the cell during & 2.7 to 4.2 & 2.2 to 3.2 & 3.3 to 4.5 & 5.4 to 13.7 & 11.7 & 18.7 \\  & 7 min, nC & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Results of measurements of charge accumulated in the measuring cell at various flow rates of water. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Ratio of Charge Accumulation** & **0.9 mL/min** & **1.8 mL/min** & **2.7 mL/min** & **3.6 mL/min** & **5.4 mL/min** & **7.2 mL/min** \\ \hline  & [(\(\Delta q\)/\(\Delta t\))]/\(|\mathcal{N}\) for linear section of a curve, nC/min & & & & & \\ \hline
2 & [(\(\Delta q\)/\(\Delta t\))]/\(\mathcal{N}\) for jumps, nC/min & & & & & & \\ \hline
3 & [(\(\Delta q\))]/\(\mathcal{N}\) accumulated as a result of all jumps in a curve, nC & & & & & \\ \hline
4 & [(\(\Delta q\))]/\(\mathcal{N}\) accumulated in the cell during 7 min, nC & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Measurements of charge accumulated in the measuring cell, normalized per water flow rate (\(V\)). drop-by-drop injection mode to the jet one is observed (Table 1, row 4). That is, the absolute value of accumulated charge increases with the increasing flow rate. However, the magnitude of a separate jump of charge (\(\sim\)2 nC) remains constant in all the measurements (Table 1, row 2). Such a constancy in jumps'magnitude is observed even upon an eight-fold increase of the supply flow rate (Table 1, row 3). At the same time, an increase in the charge accumulation rate vs. water flow rate dependence is observed in the linear sections (Table 1, row 1). Table 2 lists the parameters of the obtained dependencies (listed in Table 1), normalized per the water flow rate. One can see that the stepwise change in the amount of charge, normalized per the flow rate, is significantly decreased with increasing the flow rate (Table 2, rows 2 and 3). As seen from Table 2, linear sections of the listed dependencies are virtually unchanged, with an eight-fold increase of the flow rate from 0.9 to 7.2 mL/min (Table 2, row 1).