RESUMEN
Preparation of a specific quantum state is a required step for a variety of proposed quantum applications. We report an experimental demonstration of optical quantum state inversion in a single semiconductor quantum dot using adiabatic rapid passage. This method is insensitive to variation in the optical coupling in contrast with earlier work based on Rabi oscillations. We show that when the pulse power exceeds a threshold for inversion, the final state is independent of power. This provides a new tool for preparing quantum states in semiconductor dots and has a wide range of potential uses.
RESUMEN
Following investigation of a large number of new ligands based upon propylene amine oxime (PnAO) the d,l-diastereoisomer of hexamethyl propyleneamine oxime (HM-PAO) was selected as the preferred ligand for 99mTc as a tracer for cerebral perfusion imaging. The neutral, lipophilic 99mTc complex of d,l-HM-PAO was formed in high yield by stannous reduction of 99Mo/99mTc generator eluate using a kit formulation of the ligand. Two minutes following i.v. administration of this complex in rats, 2.25% of the injected dose appears in the brain. Little washout of the tracer is observed up to 24 hr postinjection. By qualitative autoradiographic comparison with iodoantipyrine this new radiopharmaceutical displays blood flow dependent brain uptake with little redistribution of the tracer over time. The lipophilic 99mTc complex converts slowly in vitro to a secondary complex. This conversion process may account for the ability of [99mTc]d,l-HM-PAO to be retained within the brain without redistribution.
Asunto(s)
Encéfalo/diagnóstico por imagen , Circulación Cerebrovascular , Oximas , Tecnecio , Tomografía Computarizada de Emisión , Animales , Autorradiografía , Femenino , Marcaje Isotópico/métodos , Masculino , Modelos Moleculares , Oximas/síntesis química , Oximas/metabolismo , Conejos , Ratas , Ratas Endogámicas , Estereoisomerismo , Tecnecio/síntesis química , Tecnecio/metabolismo , Exametazima de Tecnecio Tc 99m , Distribución TisularRESUMEN
A new radiopharmaceutical, 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HM-PAO) has shown considerable promise for single photon emission tomographic (SPECT) imaging of the brain. In animal biodistribution studies this complex demonstrates good brain uptake with prolonged retention of activity in brain. Further improvement of these properties, resulting in higher brain uptake with very slow washout and fixed regional distribution has been achieved following the isolation of the d,1-diastereoisomer of HM-PAO.
