Ne 1000 syringe pump

A two-electrode setup (a working electrode versus a quasi Ag/AgCl reference electrode) was utilized in a custom flow injection cell for FSCV experiments. A self-constructed potentiostat with a variable gain headstage (50 nA/V, 100 nA/V, 200 nA/V, 500 nA/V, 1 µA/V) was connected to the electrode to carry out measurements. Data were collected using a NI-6363 data acquisition card and HDCV software (Version 4, Department of Chemistry, University of North Carolina, Chapel Hill, NC, USA) [40 (link)]. For all experiments, the flow injection system used a TTL voltage-controlled source to switch a six-way HPLC valve to introduce a bolus of test analyte. A flow rate of 0.75 mL min⁻¹ was used to deliver aCSF buffer by a NE-1000 syringe pump (New Era Pump Systems, Inc., Farmingdale, NY, USA).

The graded glucose infusion protocol was evaluated in the same 12 young monkeys described above—eight young monkeys that were previously enrolled in the study to evaluate the effects of age on glucose tolerance and four additional monkeys to replace those that were no longer available for follow‐up evaluation. After overnight fasting and sedation as described above, two catheters were placed, again one in the arm (cephalic vein) for dextrose injection and one in the leg (saphenous vein) for blood sampling, except in those instances where the femoral vein was employed when saphenous access was compromised. A 50% dextrose solution was used during the graded glucose infusion protocol. At 0 minute (Dose 1), dextrose solution was infused at 5 mg/kg/min (0.6 mL/kg/h) for 20 minutes using a NE‐1000 syringe pump (New Era Pump Systems Inc., Farmingdale, NY). Immediately after the 20‐minute blood sample was taken, the rate of glucose infusion was increased to 10 mg/kg/min (1.2 mL/kg/h) for 20 minutes (Dose 2). Immediately after the 40‐minute blood sample was taken, the rate of glucose infusion was increased to 25 mg/kg/min (3 mL/kg/h) for 20 minutes (Dose 3). Serial blood samples were collected twice prior to dosing (−5 and 0 minutes) and at 10, 15, 20, 30, 35, 40, 50, 55, and 60 minutes after initiation of glucose infusion.

Glass microchips with laser-engraved microchannels were placed in stainless-steel holders, which provided leak-free connections (Micronit Microfluidics B.V., Enschede, The Netherlands). Experiments were performed in microchannels with the following dimensions: width/height/length = 250 μm: 150 μm: 55.3 mm. The microchannels were equipped with static teardrop micromixers. Emulsion droplets were generated in a borosilicate glass microfluidic device. Two syringe pumps (NE -1000 Syringe Pump, New Era Pump Systems, New York, NY, USA) with high-pressure stainless-steel syringes (8 mL, Harvard Apparatus) were used for solution delivery. Two phases, oil and aqueous mint extract, were introduced separately into microchannels through a fused silica connection (375 µm o.d., 150 µm i.d., Micronit Microfluidics B.V., Enschede, The Netherlands). The emulsification experiments were performed according to the design of experiments previously described by Grgić et al. [39 (link)] (Table 1).

Before inoculation of cells to a microfluidic chip, 0.1% (w/v) bovine serum albumin (BSA, Sigma-Aldrich, MO) is added to an overnight liquid culture (OD₆₀₀ > 0.8). The cells are then concentrated 100 times in the same medium. About 2 μl of the concentrated culture is injected into the microfluidic device using a pipette and left at 28°C. After a satisfactory amount of dead-end channels are filled with at least one cell (requires a minimum of 20 min), tubing will be connected to the device, and the flow of fresh M9 medium is started. The medium that is used is the same as for the overnight culture, but with 0.1% BSA added to prevent cells from sticking to the main channel surfaces. The medium contains no antibiotics. The flow of this medium is maintained at 4.5 μl/min by an NE-1000 Syringe Pump (New Era Pump Systems, NY). The micro-cultures are grown at 28°C for at least 14 h before imaging is started.