RESUMO
Graphene with defects is a vital support material since it improves the catalytic activity and stability of nanoparticles. Here, a density functional theory study was conducted to investigate the stability, energy, and reactivity properties of NinPdn (n = 1-3) clusters supported on graphene with different defects (i.e., graphene with monovacancy and pyridinic N-doped graphene with one, two, and three N atoms). On the interaction between the clusters and graphene with defects, the charge was transferred from the clusters to the modified graphene, and it was observed that the binding energy between them was substantially higher than that previously reported for Pd-based clusters supported on pristine graphene. The vertical ionization potential calculated for the clusters supported on modified graphene decreased compared with that calculated for free clusters. In contrast, vertical electron affinity values for the clusters supported on graphene with defects increased compared with those calculated for free clusters. In addition, the chemical hardness calculated for the clusters supported on modified graphene was decreased compared with free clusters, suggesting that the former may exhibit higher reactivity than the latter. Therefore, it could be inferred that graphene with defects is a good support material because it enhances the stability and reactivity of the Pd-based alloy clusters supported on PNG.
RESUMO
BACKGROUND: Retrocaval ureter is a rare congenital anomaly with an incidence of approx. 1/1000 live births. Recently, the laparoscopic approach has become the gold standard for treatment, relegating open surgery as a second option. CLINICAL CASE: We present the case of a 27-year-old male with a 2-year history of colicky pain in the right flank radiating to the ipsilateral thigh and genital region. The patient was initially treated with a right double-pigtail catheter stent due to obstructive uropathy as evidenced by ultrasound. He underwent laparoscopic ureteral anteposition with a successful outcome and has remained asymptomatic during a 12-month follow-up. CONCLUSIONS: Retrocaval ureter is a rare entity that requires a high grade of suspicion for initial diagnosis to provide adequate and opportune treatment that will have repercussions on kidney function and quality of life for the patient. Open surgery has traditionally been the treatment of choice; however, in recent decades laparoscopic surgery has been practiced more during this era of minimally invasive therapy, without yet displacing open surgery in our country.