Improved separation scheme for 44Sc produced by irradiation of natCa targets with 12.8 MeV protons

INTRODUCTION

⁴⁴Sc is of great interest as a positron emission tomography (PET) radionuclide due to its suitable nuclear characteristics: E_β⁺max = 1.47 MeV, branching ratio 94.3% and convenient half-life of 3.97 h. Here, ⁴⁴Sc was produced via the widely used reaction ⁴⁴Ca (p,n)⁴⁴Sc using natural calcium as a target.

METHODS

The irradiation was performed at TRIUMF using the 13 MeV cyclotron. The separation consisted of a combination of DGA branched resin and Dowex 50Wx8 (200-400 mesh). The distribution coefficients of Sc³⁺ on Dowex 50Wx8 (NH₄⁺ form, 200-400 mesh) with ammonium α-hydroxyisobutyrate (pH = 4.8) medium were determined in this study.

RESULTS AND CONCLUSION

The tested scheme allows both a reliable separation of ⁴⁴Sc from the target material as well as from the other competitive metals and a final fraction with high specific activity. The achieved radiochemical yield was 95 ± 3%.

1136 Polysomnography Is Feasible During Inpatient TBI Rehabilitation

Introduction

A recent meta-analytic report highlighted that obstructive sleep apnea was 12 times more prevalent in TBI (mixed severity) than in community-based samples. Recent studies highlight prevalent obstructive sleep apnea during acute inpatient rehabilitation which is a time of critical neural repair. Acute sleep disturbances are associated with therapy cooperation due to effects on daytime sleepiness and are associated with key rehabilitation outcomes. Given the high rates of OSA and risk for negative morbidity, this analysis sought to examine the feasibility of administering polysomnography (PSG) with EEG to diagnose sleep apnea during inpatient rehabilitation in persons with moderate to severe TBI.

Methods

This is a secondary analysis from a prospective diagnostic comparative effectiveness clinical trial (NCT03033901) that took place at six NIDILRR and one VA TBI Model System Centers. Participants were included if they met the TBI Model System case definition and slept at least 2 hours per night prior to PSG. PSG was conducted following AASM procedures in the participant’s hospital bed on the inpatient rehabilitation unit. Studies were scored by RPSGT staff and interpreted by a board certified sleep medicine physician at a centralized sleep scoring center in Tampa, FL.

Results

Of 896 potential TBI participants, 449 met initial eligibility and 345 consented for further screening; a final sample of 263 (76%) completed PSG during hospitalization. Primary reasons for not completing PSG included early discharge or medical instability (n=59) and last-minute withdrawal of consent for PSG (n=23). Of the 263 participants who completed PSG, 3 were excluded from analysis due to technical issues and 12 were excluded as the total sleep time (TST) was less than 120 minutes. Of the 248, 85.5% of the PSGs were rated as interpretable/scoreable by RPSGT and sleep physicians.

Conclusion

For a majority of participants, polysomnography is feasible during inpatient rehabilitation. Participants with shorter lengths of stay, medical instability, prolonged agitation may require polysomnography follow-up after discharge.

Support

Supported by PCORI (CER-1511-33005), VA TBIMS, DVBIC with subcontract from GDIT/GDHS (W91YTZ-13-C-0015, HT0014-19-C-0004), and NIDILRR (90DPTB00070, 90DPTB00130100, 90DPTB0008, 90DPT8000402, 90DPTB0001).

UHV application of spring-loaded Teflon seals

Large, bakeable, rotatable ultrahigh vacuum seals capable of operation at 10(-11) Torr are described. They employ doubly differentially pumped commercially available spring-loaded Teflon seals. A static version is very convenient for quick access as it requires nearly negligible sealing force other than atmospheric force.

Solid-dielectric compound parabolic concentrators: on their use with photovoltaic devices

Prototype solid dielectric compound parabolic concentrators have been made and tested. By means of the geometry and refractive properties of a transparent solid they provide a technique for increasing the power output of silicon solar cells exposed to the sun by an amount nearly equal to the increase in effective collecting area. The response is uniform over a large angle which eliminates the necessity of diurnal tracking of the sun. The technique can be applied to the construction of thin panels and has the potential for significantly reducing, their cost per unit area.