Determination of density and concentration from fluorescent images of a gas flow

A fluorescent image analysis procedure to determine the distribution of species concentration and density in a gas flow is proposed. The fluorescent emission is due to the excitation of atoms/molecules of a gas that is intercepted by an electron blade. The intensity of the fluorescent light is proportional to the local number density of the gas. When the gas flow is a mixture of different species, this proportionality can be exploited to extract the contribution associated to the species from the spectral superposition acquired by a digital camera. This yields a method that simultaneously reveals species concentrations and mass density of the mixture. The procedure is applied to two under-expanded sonic jets discharged into a different gas ambient - Helium into Argon and Argon into Helium - to measure the concentration and density distribution along the jet axis and across it. A comparison with experimental and numerical results obtained by other authors when observing under-expanded jets at different Mach numbers is made with the density distribution along the axis of the jet. This density distribution appears to be self-similar.Comment: New figures in portable .eps forma

Luminescence properties of mechanochemically synthesized lanthanide containing MIL-78 MOFs

Three metal–organic framework (MOF) compounds, Ln0.5Gd0.5{C6H3(COO)3}; Ln = Eu, Tb, and Dy with a MIL-78 structure, have been synthesized by a solvent-free mechanochemical method from stoichiometric mixtures of benzene 1,3,5-tricarboxylic acid, C6H3(COOH)3, also known as trimesic acid, and the respective lanthanide carbonates, Ln2(CO3)3·xH2O, Ln = Eu, Gd, Tb and Dy. MIL-78 (Ln0.5Gd0.5) shows the characteristic red, green, and yellow luminescence of Eu3+, Tb3+, and Dy3+, respectively. Efficient intramolecular energy transfer from the ligand triplet state to the excited states of Ln3+ ions can be observed. The lifetimes and quantum yields of these compounds are studied and discussed in detail. Among the three compounds, the Tb3+ containing compound shows the longest lifetime and highest quantum yield due to a smaller contribution from non-radiative decay pathways and better matching of the lowest triplet energy level of the benzenetricarboxylate ligand and the resonance level of Tb3+

Lumen-apposing stents versus plastic stents in the management of pancreatic pseudocysts: a large, comparative, international, multicenter study

BACKGROUND: Larger caliber lumen-apposing stents (LAMSs) have been increasingly used in the management of pancreatic fluid collections, specifically when solid debris is present; however, their advantages over smaller caliber plastic stents in the management of pancreatic pseudocysts are unclear. The aim of this study was to investigate the safety and efficacy of LAMS specifically in the management of pancreatic pseudocysts compared with double-pigtail plastic stents (DPPSs). METHODS: We performed a multicenter, international, retrospective study between January 2012 and August 2016. A total of 205 patients with a diagnosis of pancreatic pseudocysts were included, 80 patients received LAMSs and 125 received DPPSs. Measured outcomes included clinical success, technical success, adverse events, stent dysfunction, pancreatic pseudocyst recurrence, and need for surgery. RESULTS: Technical success was similar between the LAMS and the DPPS groups (97.5 % vs. 99.2 %; P = 0.32). Clinical success was higher for LAMSs than for DPPSs (96.3 % vs. 87.2 %; P = 0.03). While the need for surgery was similar between the two groups (1.3 % vs. 4.9 %, respectively; P = 0.17), the use of percutaneous drainage was significantly lower in the LAMS group (1.3 % vs. 8.8 %; P = 0.03). At 6-month follow-up, the recurrence rate was similar between the groups (6.7 % vs 18.8 %, respectively; P = 0.12). The rate of adverse events was significantly higher in the DPPS group (7.5 % vs. 17.6 %; P = 0.04). There was no difference in post-procedure mean length of hospital stay (6.3 days [standard deviation 27.9] vs. 3.7 days [5.7]; P = 0.31). CONCLUSION: When compared to DPPSs, LAMSs are a safe, feasible, and effective modality for the treatment of pancreatic pseudocysts and are associated with a higher rate of clinical success, shorter procedure time, less need for percutaneous interventions, and a lower overall rate of adverse events

Correction: Lumen-apposing stents versus plastic stents in the management of pancreatic pseudocysts: a large, comparative, international, multicenter study

Correction to: Lumen-apposing stents versus plastic stents in the management of pancreatic pseudocysts: a large, comparative, international, multicenter stud