*2.1. Irradiated Targets*

Yttrium, chromium, and molybdenum metal targets have been prepared by Spark Plasma Sintering (SPS) [21]. This technique allows the sintering of a pellet starting from powder, and bonding it to a different material without the need of a filler [35,36]. In this

work, Y targets were manufactured in one step: NatY disc (Ø 12 mm, thickness 150 µm, purity 99%, Goodfellow) was bonded to a Nb backing disc (Ø 23.5 mm, thickness 1.7 mm, purity 99.99%, Goodfellow). Chromium and Molybdenum targets were prepared in 3 steps: First, green pellets of Cr or Mo (Ø 10 mm, thickness 400 µm and 280 µm, respectively) were prepared starting from the powder form; then, an inert Au foil (Ø 20 mm, thickness 25 µm, purity 99.95%, Goodfellow) was bonded to an Oxygen-Free High thermal Conductivity (OFHC) Cu backing disc (Ø 23.5 mm, thickness 1.7 mm, purity 99.95%) by SPS; finally, Mo or Cr pellets were press-bonded to the backing plate system (Au/Cu) by SPS. SPS machine prototype at University of Pavia (Italy) and a commercial machine (Dr. SINTER® SPS1050, Sumitomo Coal & Mining Co. Ltd., now SPS Syntex Inc., Tokyo, Japan) were used. Manufactured targets are shown in Figure 1. work, Y targets were manufactured in one step: NatY disc (Ø 12 mm, thickness 150 µm, purity 99%, Goodfellow) was bonded to a Nb backing disc (Ø 23.5 mm, thickness 1.7 mm, purity 99.99%, Goodfellow). Chromium and Molybdenum targets were prepared in 3 steps: First, green pellets of Cr or Mo (Ø 10 mm, thickness 400 µm and 280 µm, respectively) were prepared starting from the powder form; then, an inert Au foil (Ø 20 mm, thickness 25 µm, purity 99.95%, Goodfellow) was bonded to an Oxygen-Free High thermal Conductivity (OFHC) Cu backing disc (Ø 23.5 mm, thickness 1.7 mm, purity 99.95%) by SPS; finally, Mo or Cr pellets were press-bonded to the backing plate system (Au/Cu) by SPS. SPS machine prototype at University of Pavia (Italy) and a commercial machine (Dr. SINTER® SPS1050, Sumitomo Coal & Mining Co. Ltd., now SPS Syntex Inc., Tokyo, Japan) were used. Manufactured targets are shown in Figure 1.

Yttrium, chromium, and molybdenum metal targets have been prepared by Spark Plasma Sintering (SPS) [21]. This technique allows the sintering of a pellet starting from powder, and bonding it to a different material without the need of a filler [35,36]. In this

*Molecules* **2021**, *26*, x FOR PEER REVIEW 3 of 11

**2. Materials and Methods** 

*2.1. Irradiated Targets* 

**Figure 1.** Mo (**a**), Cr (**b**), and Y (**c**) targets prepared with SPS technique, prior to irradiation. **Figure 1.** Mo (**a**), Cr (**b**), and Y (**c**) targets prepared with SPS technique, prior to irradiation.

The target sizes fit the target station of ACSI TR-19 Cyclotron, whose details can be found in [37] and is installed at SCDCH where the studies were performed. The target sizes fit the target station of ACSI TR-19 Cyclotron, whose details can be found in [37] and is installed at SCDCH where the studies were performed.

#### *2.2. Design of the Reactor Components 2.2. Design of the Reactor Components*

The reactor was devised so as to be compatible with the electro-mechanics of commercial synthesis modules. The developed system fundamentally consists of a series of adaptors able to exploit the original purpose of some components of commercial modules. The reactor was devised so as to be compatible with the electro-mechanics of commercial synthesis modules. The developed system fundamentally consists of a series of adaptors able to exploit the original purpose of some components of commercial modules.

The concept was tested on the Eckert & Ziegler (E&Z) Modular Lab and Trasis AllinOne commercial modules. These devices are based on disposable cassettes and have a suitable number of valves and components to implement the dissolution process together with the following purification and synthesis protocol. In particular, stepped motors and heated reactors are present. In the original modules' configuration, they are intended for the movement of syringe drivers/activity plunger and the kinetics regulation of the chemical process, respectively. In both modules these components are conveniently located to implement a dissolution process of solid targets: in the proposed configuration, the stepped motor is used for the movement of a dissolution vial by means of a vial-holder and mounting rods, while the reactor's heater is used to plug a target holder suitable for The concept was tested on the Eckert & Ziegler (E&Z) Modular Lab and Trasis AllinOne commercial modules. These devices are based on disposable cassettes and have a suitable number of valves and components to implement the dissolution process together with the following purification and synthesis protocol. In particular, stepped motors and heated reactors are present. In the original modules' configuration, they are intended for the movement of syringe drivers/activity plunger and the kinetics regulation of the chemical process, respectively. In both modules these components are conveniently located to implement a dissolution process of solid targets: in the proposed configuration, the stepped motor is used for the movement of a dissolution vial by means of a vial-holder and mounting rods, while the reactor's heater is used to plug a target holder suitable for coin-shaped targets.

coin-shaped targets. Hence, the design of the components was performed with the Computer Aided Design tool Solidworks®, after the geometry of the available modules had been reconstructed with the same software. All the parts were made of materials easily washable and as much as possible inert to the strong dissolution condition required for the radiometal isotope recovery. Since the system components are principally made of metallic materials, they were manufactured with Computerized Numerical Control machines. The pieces realized Hence, the design of the components was performed with the Computer Aided Design tool Solidworks®, after the geometry of the available modules had been reconstructed with the same software. All the parts were made of materials easily washable and as much as possible inert to the strong dissolution condition required for the radiometal isotope recovery. Since the system components are principally made of metallic materials, they were manufactured with Computerized Numerical Control machines. The pieces realized for this purpose are listed in Table 1, and a description of the various parts is hereafter reported.


for this purpose are listed in Table 1, and a description of the various parts is hereafter

**Table 1.** List of the dissolution system components. **Table 1.** List of the dissolution system components.

*Molecules* **2021**, *26*, x FOR PEER REVIEW 4 of 11

#### 2.2.1. Reactor Dissolution Vial 2.2.1. Reactor Dissolution Vial

This component, where the dissolution reaction process occurs, is most of the time in contact with strong acid solvents. For that reason, it must be made of inert material. In particular, three different materials were chosen for the proof of concept: This component, where the dissolution reaction process occurs, is most of the time in contact with strong acid solvents. For that reason, it must be made of inert material. In particular, three different materials were chosen for the proof of concept:


reported.

Indeed, these materials offer different inertness to acidic solutions. While PEEK vials could be machined in house, the ones in glass and quartz were manufactured by the French company Intellion S.a.r.l (Paris). The top of the vial was shaped to screw with the Vial Head for 3 connectors 1/4", shown in Figure 2b, provided as accessories of E & Z modules. This allows the reaction vial to be connected with the cassette by standard tubing and connectors used in these kinds of applications. By contrast, the vial bottom part has a cavity dedicated to installation of a 15.08 mm ID (Internal Diameter) × 2.62 mm thick O-ring, used to seal the reactor with the backing disc. In this way, only the target material will be dissolved, thanks to the inertness of the backing plate. Indeed, these materials offer different inertness to acidic solutions. While PEEK vials could be machined in house, the ones in glass and quartz were manufactured by the French company Intellion S.a.r.l (Paris). The top of the vial was shaped to screw with the Vial Head for 3 connectors 1/4'', shown in Figure 2b, provided as accessories of E & Z modules. This allows the reaction vial to be connected with the cassette by standard tubing and connectors used in these kinds of applications. By contrast, the vial bottom part has a cavity dedicated to installation of a 15.08 mm ID (Internal Diameter) × 2.62 mm thick O-ring, used to seal the reactor with the backing disc. In this way, only the target material will be dissolved, thanks to the inertness of the backing plate.

**Figure 2.** (**a**) Reaction vial made of borosilicate glass with mounted O-ring; (**b**) PEEK vial, with the PEEK Vial Head. **Figure 2.** (**a**) Reaction vial made of borosilicate glass with mounted O-ring; (**b**) PEEK vial, with the PEEK Vial Head.

#### 2.2.2. Vial-Holder and Mounting Rods 2.2.2. Vial-Holder and Mounting Rods

These components, made either in machined aluminium alloy 6082 or stainless steel in relation to the desired rigidity, were needed to connect the reactor vial to the stepping motor in order to perform the vial movement. Indeed, the vial could be kept suspended without slipping down owing to the contact of its holder with the cap, while it also allowed the vial to be held in contact with the target when pushed against it. Therefore, the component is structured in such manner as to facilitate the vial insertion and, in case of a transparent vessel, to allow some visibility inside it during the chemical attack. These components, made either in machined aluminium alloy 6082 or stainless steel in relation to the desired rigidity, were needed to connect the reactor vial to the stepping motor in order to perform the vial movement. Indeed, the vial could be kept suspended without slipping down owing to the contact of its holder with the cap, while it also allowed the vial to be held in contact with the target when pushed against it. Therefore, the component is structured in such manner as to facilitate the vial insertion and, in case of a transparent vessel, to allow some visibility inside it during the chemical attack.

Since the moving elements of the modules are not well aligned with the target holder platform, connecting elements have to be adopted. Thus, an assembly of two rods was Since the moving elements of the modules are not well aligned with the target holder platform, connecting elements have to be adopted. Thus, an assembly of two rods was realized to mount the vessel holder to the syringe actuator. The images in Figure 3 illustrate the parts manufactured for the E&Z module. Slots were applied in correspondence to the bolted joints for the correction of possible misalignments. Enough thickness was then provided in the design of these elements to avoid their bending during the reactor sealing,

*Molecules* **2021**, *26*, x FOR PEER REVIEW 5 of 11

*Molecules* **2021**, *26*, x FOR PEER REVIEW

which can cause solvent losses during operation. At the same time, their dimensions were adjusted to not cause collision with the modules' components. then provided in the design of these elements to avoid their bending during the reactor sealing, which can cause solvent losses during operation. At the same time, their dimensions were adjusted to not cause collision with the modules' components. then provided in the design of these elements to avoid their bending during the reactor sealing, which can cause solvent losses during operation. At the same time, their dimensions were adjusted to not cause collision with the modules' components.

realized to mount the vessel holder to the syringe actuator. The images in Figure 3 illustrate the parts manufactured for the E&Z module. Slots were applied in correspondence to the bolted joints for the correction of possible misalignments. Enough thickness was

realized to mount the vessel holder to the syringe actuator. The images in Figure 3 illustrate the parts manufactured for the E&Z module. Slots were applied in correspondence to the bolted joints for of possible thickness was

**Figure 3.** (**a**) Assembly of the vial holder; (**b**) mounting rods used for the E&Z module. **Figure 3.** (**a**) Assembly of the vial holder; (**b**) mounting rods used for the E&Z module. **a**) Assembly of the vial holder; **b**) mounting rods used for the

#### 2.2.3. Target Holder 2.2.3. Target Holder Target Holder

A dedicated target holder was developed in order to keep in position the target coin during the dissolution process. This component should have a good thermal conductivity, to efficiently heat the target when control on the reaction kinetics is desired. Its shape was devised as an extension of the reactor's heater to the outside, while a dedicated cavity on the holder's top allows the accommodation of the target. Moreover, as show in Figure 4, a groove surrounding the target slot is intended to confine possible losses from the vessel. A dedicated target holder was developed in order to keep in position the target coin during the dissolution process. This component should have a good thermal conductivity, to efficiently heat the target when control on the reaction kinetics is desired. Its shape was devised as an extension of the reactor's heater to the outside, while a dedicated cavity on the holder's top allows the accommodation of the target. Moreover, as show in Figure 4, a groove surrounding the target slot is intended to confine possible losses from the vessel. A dedicated target holder was developed in order to keep in position the target coin during the dissolution process. This component should have a good thermal conductivity, to efficiently heat the target when control on the reaction kinetics is desired. Its shape was devised as an extension of the reactor's heater to the outside, while a dedicated cavity on the holder's allows the accommodation of the target. Moreover, as show in Figure 4, a groove surrounding the target slot is intended to possible losses from the vessel.

**Figure 4.** (**a**) Target holder made for the E&Z module shown in lateral view (left), upside view (middle), and with a sample target inserted (right). (**b**) Target holder made for the Trasis AllinOne, with the sample target inserted. **Figure 4.** (**a**) Target holder made for the E&Z module shown in lateral view (left), upside view (middle), and with a sample target inserted **b**) Target holder made for the Trasis AllinOne, with the sample target **Figure 4.** (**a**) Target holder made for the E&Z module shown in lateral view (left), upside view (middle), and with a sample target inserted (right). (**b**) Target holder made for the Trasis AllinOne, with the sample target inserted.
