Optical properties of individual CdS/CdSe/CdS nanocrystals: spherical quantum wells as single-photon sources.

We have synthesized CdS(1.3 nm)/CdSe(1.7 nm)/CdS(3.4 nm) spherical quantum wells (SQWs) with a diameter of 13 nm and demonstrated the first photon-antibunching from their emission, labelling them as single-photon sources. Antibunching survives even at high excitation intensities, ruling-out strong emission from the bi-exciton. For the largest intensities, antibunching coupled to spectral measurements reveal the signature of a blue-shifted emission, associated to an irreversible photo-aging effect. A statistical analysis over 26 SQWs demonstrates a moderate correlation between the energy of the main and the blue-shifted emission. Intensity-timetraces recorded on 28 single SQWs show weak blinking, with a median time spent in the bright state of 89%. Their emission decay reveals a complex dynamic with either three or four exponential components. We assigned three of them to the neutral and singly-charged excitons and the slowest to defect emission. While SQWs have been initially designed for laser-oriented applications, we demonstrate that they can serve as efficient single-photon sources.

[Neonatal asphyxia: neurologic outcome]. / Prognosi neurologica dell'asfissia neonatale.

AIM: The neonatal asphyxia is recognized as an important cause of morbidity and mortality during the pediatric age. The objective of this study was to evaluate the correlation between some neonatal variables and neurological outcome at two years of life in infants with asphyxia, in order to produce a correct prognosis and to grant a rapid and targeted therapy. METHODS: We have recruited 63 patients whose history and neuroimages suggested a neonatal asphyxia, and we have analysed their clinical- instrumental parameters every three months until two years of life. A correlation study was carried out in order to find a statistical significance indicated by p-value < 0,05. The correlation was made by means of Chi-square and ANOVA (analysis of variance) test. RESULTS: Only one patient developed isolated epilepsy, 17 developed CP associated to epilepsy (14 of them were term infants, 3 were preterm); 25 patients, 13 term and 12 preterm, developed only CP; 20 patients, 11 preterm and 9 term infants, developed a psychomotor delay. The most severe clinical picture (CP associated with epilepsy) appeared in 12 infants of adequate weight and in 5 LBW children; the CP appeared in 14 NW patients, 5 LBW, 4 VLBW and 2 ELBW. Psychomotor delay was developed by 8 NW children, 2 LBW and 10 ELBW. Most patients with severe CP presented severe neurological symptoms at birth. Moderate CP involved those who had a mild neurological or systemic symptoms. Furthermore an association emerged between early epilepsy and CP onset and their severity. CONCLUSION: Neonatal seizures are not related to an increased risk to develop epilepsy. Epilepsy alone is a rare event and it usually complicates CP picture. Most subject with both epilepsy and CP are term infants with adequate weight. Preterm VLBW infants have a greater risk to develop a psychomotor delay. Clinical conditions at birth are related to CP severity (several neonatal neurological signs are the greater risk factors). Severely pathological neonatal EEG (background activity) is related to CP severity and an early symptomatic epilepsy onset is related with both epilepsy and CP severity.

[Procedural pain perception of preterm newborn in neonatal intensive care unit: assessment and non-pharmacological approaches]. / Percezione del dolore procedurale del nato pretermine in terapia intensiva neonatale: valutazione e tecniche non farmacologiche d'intervento.

AIM: The aim of this study was to evaluate the reaction to the procedural pain of preterm newborn and to demonstrate the different effectiveness of the two analgesic and not pharmacological techniques of recent clinical acquisition, the use of glucose solution and the sensorial saturation, in order to identify an optimal strategy for the prevention and pain treatment. METHODS: We take a sample of 28 preterm newborns of 30-35 weeks. The subjects are divided in two randomized groups following the kind of analgesia used during the hematic sample from heel: the first group (group A) included 14 subjects, who received glucose solution associated to no nutritive suction; the second group (group B) included 14 subjects who received the sensorial saturation. The symptoms associated with pain at the moment of venous sample are measured through premature infant pain profile (PIPP) scale. RESULTS: Results show that the score was lower in the group treated with sensorial saturation (media 6.52; P<0.001) than in the group treated with glucose (media 13.80; P<0.05). CONCLUSION: The use of "care" techniques (in our case sensorial saturation) ameliorates the quality of life in NICU and reduces the pain threshold perceived by newborn, reducing therefore the exposition to the pain stimulus and the possibility that some consequences due to an inadequate pain treatment in neonatal age could develop.