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Biology is playing an increasingly important role in the chemical engineering curriculum. We describe a set of experiments we have implemented in our Undergraduate Laboratory course giving students practical insights into membrane separation processes for protein processing. The goal of the lab is to optimize the purification and concentration of a protein by hollow-fiber, tangential-flow ultrafiltration. Experiments guide the students to an appreciation for concentration polarization, i.e. the buildup of a concentrated layer of solute on the membrane surface resulting from opposing processes of convection to the membrane surface and removal from the surface by diffusion and tangential flow. The experiment draws upon concepts the students will have seen in fluid mechanics, mass transfer, and separations courses. Optimization, the process of compromising between opposing phenomena, is demonstrated by having the students design a purification and concentration process that minimizes processing time.

Metal-aluminum oxide–hafnium aluminum oxide‒silicon oxide–silicon (hereafter MAHAOS) devices can be candidates for ionizing radiation sensor applications. In this work, MAHAOS devices (SONOS-like structures with high k stack gate dielectric) were studied regarding the first known characterization of the ionization radiation sensing response. The change of threshold voltage VT for a MAHAOS device after gamma ray exposure had a strong correlation to the total ionization dose (TID) of gamma radiation up to at least 5 Mrad TID. In this paper, the gamma radiation response performances of the pre-programmed and virgin (non-pre-programmed) MAHAOS devices are presented. The experimental data show that the change of VT for the pre-programmed MAHAOS device with gamma irradiation is very significant. The data of pre-programmed MAHAOS devices written by 5 Mrad TID of gamma radiation was also stable for a long time with data storage. The sensing of gamma radiation by pre-programmed MAHAOS devices with high k stack gate dielectric reported in this study has demonstrated their potential application for non-volatile ionizing radiation sensing technology in the future.

Fluorine-treated titanium nitride–silicon oxide–hafnium oxide–silicon oxide–silicon devices (hereafter F-MOHOS) are candidates for total ionization dose (TID) radiation sensor applications. The main subject of the study reportedherein is the performance improvement in terms of TID radiation-induced charge generation effect and charge-retention reliability characterization for F-MOHOS devices. In the case of F-MOHOS TID radiation sensors, the gamma radiation induces a significant decrease of threshold voltage VT and the radiation-induced charge density is nearly six times larger than that of standard metal–oxide–nitride–oxide–silicon MONOS devices. The decrease of VT for F-MOHOS after gamma irradiation has a strong correlation to the TID up to 5 Mrad gamma irradiation as well. The improvement of charge retention loss for F-MOHOS devices is nearly 15% better than that of metal–oxide–hafnium oxide–oxide–silicon MOHOS devices. The F-MOHOS device described in this study demonstrates better feasibility for non-volatile TID radiation sensing in the future.

Silicon-oxide-nitride-oxide-silicon (SONOS) capacitor devices with an oxy-nitride as the charge-trapping layer (O-SONOS) could be candidates for UV total dose (TD) nonvolatile sensors. UV radiation induces a significant increase in the threshold voltage VT of the O-SONOS UV TD nonvolatile radiation sensors. The experimental results indicate that the UV-induced increase in VT for the O-SONOS capacitor device under positive gate bias stress (PGBS) is nearly 2 V after 100 mW·s/cm² TD UV radiation. The change in VT for the O-SONOS capacitor after UV irradiation is also correlated with UV TD up to 100 mW·s/cm2 irradiation. The charge-retention loss of the nonvolatile O-SONOS capacitor after a 10-year retention is below 10%. The UV TD information can be permanently stored and accumulated in nonvolatile O-SONOS capacitor devices. The O-SONOS capacitor device used in this study has demonstrated the feasibility of nonvolatile UV TD sensing. [ABSTRACT FROM AUTHOR]

The titanium nitride-aluminum oxide-silicon nitride-silicon oxide-silicon devices with a high-k aluminum oxide as a charge-blocking layer (TANOS) could be candidates for nonvolatile total ionization dose (TID) radiation sensors. Gamma radiation induces a significant decrease in the threshold voltage VT of TANOS and the radiation-induced VT decrease of TANOS is nearly 1.5 times that on a standard titanium nitride-silicon oxide-silicon nitride-silicon oxide-silicon (TONOS) device after 10 Mrad TID gamma irradiation. The change in VT of TANOS after gamma irradiation also has a strong correlation to the TID up to 10 Mrad gamma irradiation. The VT retention characteristics of TANOS devices can be improved before gamma irradiation and after 10 Mrad gamma irradiation. Moreover, the VT retention characteristics of TANOS devices can be markedly improved and are nearly 10% better than those of standard TONOS devices after 10 Mrad gamma irradiation. Therefore, the TANOS device in this study has demonstrated the possibility of its use for high response and good TID data retention for nonvolatile TID radiation sensing. [ABSTRACT FROM AUTHOR]

Metal-oxide-nitride-oxide-silicon devices with Si-rich nitride and oxy-nitride as a bi-layer stack charge-trapping layer (hereafter STOB-MONOS) could be candidates for nonvolatile total ionizing dose (TID) radiation sensors. In the case of STOB-MONOS nonvolatile TID radiation sensors, gamma radiation induces a significant decrease in the threshold voltage VT, which is nearly 2 times larger than that of a standard MONOS device. The change in VT for STOB-MONOS after gamma irradiation also has a strong correlation to TID up to 10 Mrad gamma irradiation. The reliability characteristics of VT retention time before and after gamma irradiation for STOBMONOS devices can be markedly improved and is nearly 12% better than that of a standard MONOS device. The STOB-MONOS device in this study has demonstrated the possibility of improved the feasibility of non-volatile high TID radiation sensing. [ABSTRACT FROM AUTHOR]

The nitrogen-implanted titanium nitride-silicon oxide-hafnium oxide-silicon oxide-silicon (hereafter, N-TOHOS) device can be a candidate for total ionizing dose (TID) radiation sensor application. In this study, we mainly focus on N implantation for the improvement of the TID radiation-induced charging effect performance of the N-TOHOS device. The TID radiation-induced charging effect performance of the N-TOHOS device is improved by the implantation of nitrogen in the HfO2 trapping layer. Experimental data show that the radiation-induced charge density of a typical N-TOHOS device is approximately 4-5 times that of a conventional metal-oxide-nitride- oxide-silicon (MONOS) device reported previously. The charge retention reliability after 5 mrad gamma irradiation of the N-TOHOS device with a high implantation dose and a low implantation energy can be improved. The N-TOHOS device described in this study has demonstrated its potential for nonvolatile TID radiation sensing application in the future. [ABSTRACT FROM AUTHOR]

The article describes a laboratory experiment for college students that focuses on ultrafiltration of protein solutions.