Towards the application of large mordenite particles as Positron Emission Particle Tracking tracers

MRS Advances ◽  
2018 ◽  
Vol 4 (1) ◽  
pp. 21-26
Author(s):  
Daniel S. Parsons ◽  
Andrew Ingram ◽  
Joseph A. Hriljac
Keyword(s):  
Ion Exchange ◽  
Particle Tracking ◽  
Ethanol Concentration ◽  
Particle Morphology ◽  
Cation Concentration ◽  
Positron Emission ◽  
The Relationship ◽  
Influence Of Ph

ABSTRACTIn this study, we report developments towards the application of large zeolite particles, with diameter ca. 40 μm, as tracers in Positron Emission Particle Tracking (PEPT) imaging using 68Ga. The influence of intrapore Na+ and TEA+ (tetraethylammonium) cation concentrations and framework Si/Al ratio on the morphology of mordenite particles has been investigated, advancing understanding of the relationship between these factors. Moreover, the influence of ethanol concentration in the gel during aging on intrapore cation concentration, Si/Al ratio and particle morphology has also been investigated. Additionally, facile ion-exchange between aqueous Ga3+ and intrapore H+ in mordenite has been demonstrated. The influence of pH and gallium speciation on ion-exchange has been investigated to determine favourable conditions for 68Ga3+ uptake by the zeolite.

scholarly journals The influence of demographic factors on subjective cognitive concerns and beta-amyloid

2016 ◽  
Vol 29 (4) ◽  
pp. 645-652 ◽  
Author(s):  
Sarah L. Aghjayan ◽  
Rachel F. Buckley ◽  
Patrizia Vannini ◽  
Dorene M. Rentz ◽  
Jonathan D. Jackson ◽  
...  
Keyword(s):  
Positron Emission Tomography Imaging ◽  
Demographic Factors ◽  
Cross Sectional Study ◽  
Mediation Effect ◽  
Aging Brain ◽  
Linear Regression Models ◽  
Cross Sectional ◽  
Clinically Normal ◽  
Positron Emission ◽  
The Relationship

ABSTRACTBackground:Converging evidence suggests that subjective cognitive concerns (SCC) are associated with biomarker evidence of Alzheimer's disease (AD) prior to objective clinical impairment. However, the sensitivity of SCC reports in early AD may be biased by demographic factors. Here, we sought to investigate whether age, education, and sex influence the relationship between SCC and amyloid (Aβ) burden.Methods:In this cross-sectional study, we examined 252 clinically normal (CN) individuals (57.7% females) enrolled in the Harvard Aging Brain Study, ages 63–90 years (mean 73.7±6) with 6–20 years of education (mean 15.8±3). SCC was assessed as a composite score comprising three questionnaires. Cortical Aβ burden was assessed with Pittsburgh compound B positron emission tomography imaging. A series of linear regression models assessed the potential modifying role of demographic variables with respect to Aβ burden and SCC. A post-hoc mediation model was implemented to further understand the relationship between Aβ burden and SCC via their relationship with education.Results:Age (β = −0.84, p = 0.36) and sex (β = −0.55, p = 0.22) did not modify the relationship between SCC and Aβ burden. Fewer years of education was correlated with greater SCC (r = −0.12, p = 0.05), but the relationship between Aβ burden and SCC was stronger in those with more education (β = 1.16, p < 0.05). A partial mediation effect was found of Aβ burden on SCC via education (b = −0.12, 95% CI [−0.31, −0.02]).Conclusions:These findings suggest that the association between SCC and Aβ burden becomes stronger with greater educational attainment. Thus, SCC may be of particular importance in highly educated CN individuals harboring amyloid pathology.

scholarly journals Coherent Precipitation and Strengthening in Compositionally Complex Alloys: A Review

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 878 ◽  
Author(s):  
Qing Wang ◽  
Zhen Li ◽  
Shujie Pang ◽  
Xiaona Li ◽  
Chuang Dong ◽  
...  
Keyword(s):  
Solid Solution ◽  
High Performance ◽  
Particle Morphology ◽  
Precipitation Strengthening ◽  
Second Phase ◽  
High Entropy ◽  
Second Phase Particles ◽  
Alloy Strength ◽  
Solid Solution Matrix ◽  
The Relationship

High-performance conventional engineering materials (including Al alloys, Mg alloys, Cu alloys, stainless steels, Ni superalloys, etc.) and newly-developed high entropy alloys are all compositionally-complex alloys (CCAs). In these CCA systems, the second-phase particles are generally precipitated in their solid-solution matrix, in which the precipitates are diverse and can result in different strengthening effects. The present work aims at generalizing the precipitation behavior and precipitation strengthening in CCAs comprehensively. First of all, the morphology evolution of second-phase particles and precipitation strengthening mechanisms are introduced. Then, the precipitation behaviors in diverse CCA systems are illustrated, especially the coherent precipitation. The relationship between the particle morphology and strengthening effectiveness is discussed. It is addressed that the challenge in the future is to design the stable coherent microstructure in different solid-solution matrices, which will be the most effective approach for the enhancement of alloy strength.

scholarly journals Determination of receptor occupancy in the presence of mass dose: [11C]GSK189254 PET imaging of histamine H3 receptor occupancy by PF-03654746

2016 ◽  
Vol 37 (3) ◽  
pp. 1095-1107 ◽  
Author(s):  
Jean-Dominique Gallezot ◽  
Beata Planeta ◽  
Nabeel Nabulsi ◽  
Donna Palumbo ◽  
Xiaoxi Li ◽  
...  
Keyword(s):  
Binding Sites ◽  
Human Subjects ◽  
Receptor Occupancy ◽  
Healthy Human ◽  
Positron Emission ◽  
Relationship Of ◽  
The Relationship ◽  
Pet Scans

Measurements of drug occupancies using positron emission tomography (PET) can be biased if the radioligand concentration exceeds “tracer” levels. Negative bias would also arise in successive PET scans if clearance of the radioligand is slow, resulting in a carryover effect. We developed a method to (1) estimate the in vivo dissociation constant Kd of a radioligand from PET studies displaying a non-tracer carryover (NTCO) effect and (2) correct the NTCO bias in occupancy studies taking into account the plasma concentration of the radioligand and its in vivo Kd. This method was applied in a study of healthy human subjects with the histamine H3 receptor radioligand [11C]GSK189254 to measure the PK-occupancy relationship of the H3 antagonist PF-03654746. From three test/retest studies, [11C]GSK189254 Kd was estimated to be 9.5 ± 5.9 pM. Oral administration of 0.1 to 4 mg of PF-03654746 resulted in occupancy estimates of 71%–97% and 30%–93% at 3 and 24 h post-drug, respectively. NTCO correction adjusted the occupancy estimates by 0%–15%. Analysis of the relationship between corrected occupancies and PF-03654746 plasma levels indicated that PF-03654746 can fully occupy H3 binding sites ( ROmax = 100%), and its IC50 was estimated to be 0.144 ± 0.010 ng/mL. The uncorrected IC50 was 26% higher.

Solid particle motion in a standpipe as observed by Positron Emission Particle Tracking

2009 ◽  
Vol 194 (1-2) ◽  
pp. 58-66 ◽  
Author(s):  
Chian W. Chan ◽  
Jonathan Seville ◽  
Xianfeng Fan ◽  
Jan Baeyens
Keyword(s):  
Solid Particle ◽  
Particle Tracking ◽  
Particle Motion ◽  
Positron Emission
Sign in / Sign up

Export Citation Format

Share Document