Drain placement in paediatric complicated appendicitis: a systematic review and meta-analysis.

Children undergoing appendicectomy for complicated appendicitis are at an increased risk of post-operative morbidity. Placement of an intra-peritoneal drain to prevent post-operative complications is controversial. We aimed to assess the efficacy of prophylactic drain placement to prevent complications in children with complicated appendicitis. A systematic review was performed in accordance with PRISMA guidelines. Cochrane, MEDLINE and Web of Science databases were searched from inception to November 2022 for studies directly comparing drain placement to no drain placement in children ≤ 18 years of age undergoing operative treatment of complicated appendicitis. A total of 5108 children with complicated appendicitis were included from 16 studies; 2231 (44%) received a drain. Placement of a drain associated with a significantly increased risk of intra-peritoneal abscess formation (odds ratio [OR] 1.61, 95% confidence interval [CI] 1.16-2.24, p = 0.004) but there was no significant difference in wound infection rate (OR 1.46, 95% CI 0.74-2.88, p = 0.28). Length of stay was significantly longer in the drain group (mean difference 2.02 days, 95% CI 1.14-2.90, p < 0.001). Although the quality and certainty of the available evidence is low, prophylactic drain placement does not prevent intra-peritoneal abscess following appendicectomy in children with complicated appendicitis.

Congenital intestinal malrotation presenting in octogenarians: a report of two cases.

Malrotation is part of a spectrum of small and large bowel positional and fixational abnormalities caused by the failure of the fetal intestine to complete a 270-degree rotation around the superior mesenteric artery axis. Rarely, it presents in the adult as a cause of acute small bowel obstruction. Chronic symptoms of malrotation in adults are subtle, and include intermittent abdominal pain, nausea and vomiting. We present two cases of malrotation in octogenarian men presenting acutely with small bowel obstruction. Both patients were treated with emergency surgery. In one case the chronic symptoms resolved postoperatively. Malrotation and midgut volvulus should be considered as a rare differential diagnosis for small bowel obstruction in adults. Suspicions should be increased when there is a history of recurrent presentations with similar symptoms.

Interatomic scattering in energy dependent photoelectron spectra of Ar clusters.

Soft X-ray photoelectron spectra of Ar 2p levels of atomic argon and argon clusters are recorded over an extended range of photon energies. The Ar 2p intensity ratios between atomic argon and clusters' surface and bulk components reveal oscillations similar to photoelectron extended X-ray absorption fine structure signal (PEXAFS). We demonstrate here that this technique allows us to analyze separately the PEXAFS signals from surface and bulk sites of free-standing, neutral clusters, revealing a bond contraction at the surface.

Cluster size effects in core excitons of 1s-excited nitrogen.

Cluster size effects in core excitons below the N 1s ionization energy of nitrogen clusters are reported in the energy regime 405-410 eV. These results are compared to the molecular Rydberg states as well as the corresponding bulk excitons of condensed nitrogen. The experimental results are assigned using ab initio calculations. It is found that the lowest excitons (N 1s-->3ssigma and N 1s-->3ppi) are blueshifted relative to the molecular Rydberg transitions, whereas others (N 1s-->3dpi and N 1s-->4ppi) show a redshift. Results from ab initio calculations on (N(2))(13) clearly indicate that the molecular orientation within a cluster is critical to the spectral shift, where bulk sites as well as inner- and outer-surface sites are characterized by different inner-shell absorption energies. These results are compared to the experimental spectra as well as previous work on site-selectively excited atomic van der Waals clusters, providing an improved spectral assignment of core exciton states in weakly bound molecular clusters and the corresponding condensed phase.

Dynamic stabilization in 1sigma(u)-->1pi(g) excited nitrogen clusters.

High-resolution 1s near-edge spectra of molecular nitrogen and variable size nitrogen clusters obtained using monochromatic synchrotron radiation from the high brilliance BESSY-II storage ring facility are reported. The vibrationally resolved 1sigma(u)-->1pi(g) core-to-valence excitation band of clusters shows a distinct redshift of 6+/-1 meV relative to the isolated molecule, but the vibrational structure and linewidths are essentially unchanged. This shift is assigned to dynamic stabilization of 1sigma(u)-->1pi(g) excited molecules in clusters, arising from the dynamic dipole moment generated by core-hole localization in the low-symmetry cluster field. This leads to changes in intermolecular interactions compared to the ground-state cluster. Such spectral shifts are expected to occur generally in molecular clusters and in the corresponding condensed phase.