Magnetocaloric Properties in Rare-Earth-Based Metal-Organic Frameworks: Influence of Magnetic Density and Hydrostatic Pressure.

Magnetic refrigeration based on the magnetocaloric effect (MCE) in metal-organic frameworks (MOF) is regarded as an attractive approach to create more sustainable cooling systems with higher efficiency than traditional ones. Here, we report a study of the MCE in a series of rare-earth-based MOFs. We have considered the selection of the rare-earth cation by investigating materials belonging to the α-rare-earth polymeric framework-4 (α-RPF-4) MOF family, synthesized with different rare-earth cations, and observed that paramagnetic moment and saturation magnetization play an important role in enhancing the magnetic entropy change ΔSM. The effect of structural parameters has also been considered by investigating three classes of metal-organic Gd materials built up from different types of inorganic secondary building units, including clusters (as in Gd-UiO-66), one-dimensional (as in α-RPF-4), and layered (as in Gd-LRH) conformations. Moreover, the analysis of the hydrostatic pressure influence reveals a significant increase in the -ΔSM and relative cooling power (RCP) with values between 4.3 and 16.3 and 121-509 J/kg. Specifically, the RCPmax found was ∼683 J/kg for Gd-UiO-66, which is higher than the one recently observed for Gd2SiO5 (649.5 J/kg). The present study demonstrates that the engineering of metal-organic framework systems based on high Gd densities may favor enhancing of magnetocaloric responses even at low pressures, thus promoting a new design strategy for efficient cooling devices.

Influence of the Synthesis and Crystallization Processes on the Cation Distribution in a Series of Multivariate Rare-Earth Metal-Organic Frameworks and Their Magnetic Characterization.

The incorporation of multiple metal atoms in multivariate metal-organic frameworks is typically carried out through a one-pot synthesis procedure that involves the simultaneous reaction of the selected elements with the organic linkers. In order to attain control over the distribution of the elements and to be able to produce materials with controllable metal combinations, it is required to understand the synthetic and crystallization processes. In this work, we have completed a study with the RPF-4 MOF family, which is made of various rare-earth elements, to investigate and determine how the different initial combinations of metal cations result in different atomic distributions in the obtained materials. Thus, we have found that for equimolar combinations involving lanthanum and another rare-earth element, such as ytterbium, gadolinium, or dysprosium, a compositional segregation takes place in the products, resulting in crystals with different compositions. On the contrary, binary combinations of ytterbium, gadolinium, erbium, and dysprosium result in homogeneous distributions. This dissimilar behavior is ascribed to differences in the crystallization pathways through which the MOF is formed. Along with the synthetic and crystallization study and considering the structural features of this MOF family, we also disclose here a comprehensive characterization of the magnetic properties of the compounds and the heat capacity behavior under different external magnetic fields.

The Role of Laparoscopy in Abdominal Trauma: A 10-Year Review.

Laparoscopy is accepted in penetrating abdominal trauma (PAT), but its role in blunt trauma (BAT) remains a controversial one. Our study assessed the utility of diagnostic laparoscopy (DL) and therapeutic laparoscopy (TL) in abdominal trauma between December 2006 and January 2016. We analysed the indication for laparoscopy, type of lesions, TL, conversion rate, complications and length of hospital stay. 49 patients had a DL: 42 males and 7 females, with a mean age of 36.1+-13.3. We had 20 PAT and 30BAT. The indications for laparoscopy were: diagnosis of penetration in PAT, suspicion of hollow organ injury or diaphragm injury, active bleeding in organ injuries in BAT. 11/48 of preoperative ultrasounds and 4/48 of CT's were false negative. In 3 of 20 PAT, DL was negative and in 4 nontherapeutic. There were 4 TL's and 7 conversions. The main injuries in BAT were: 9 hollow organ perforations, 6 mesenteric lacerations, 2 diaphragmatic and 2 splenic injuries. There were 10 TL's, 9 conversions and 14 TL. The operative time and length of hospital stay was higher in the conversion group. There were 6 complications and 3 mortalities. There were no missed injuries. An unnecessary laparotomy was avoided in 18/49 cases (36.73%). In selected cases of PAT and BAT with equivocal clinical and imaging diagnosis, laparoscopy is a useful tool with therapeutic role, that reduces unnecessary laparotomies, complication rate and hospital stay.

Laparoscopic Repair of Small Ventral Hernias Using the "Ventralex™ Hernia Patch".

Laparoscopy of abdominal wall defects becomes more and more actual, considering the well-known advantages of minimally invasive surgery, and the reduced incidence of post-operative ventral infections and recurrence rates compared to the the open repair with or without mesh. We hereby present the technique of the laparoscopic repair of small ventral hernias (defect 2 centimetres), using the Ventralex mesh, which is bi-faceted, polypropylene and PTFE, circular preformed, it has 8 centimeters in diameter, fixated with 4 transparietal sutures. The mesh is created for open surgery but it is placed in the intraperitoneal cavity. This technique was used for 28 patients,16 women and 12 men, with an average age of 53,3 years (29-72 years), consisting of: 22 umbilical hernias (UH), 2 epigastric hernias (EH), one left-side Spiegelian hernia, one incisional hernia after an open surgery for an umbilical hernia with a Ventralex mesh, and 2 trocar eventrations (TE) after a laparoscopic cholecystectomy. Mean operating time was 52 minutes (42-70 minutes), post-operative hospital stay of 1,8 days (1-5 days). The main advantages are: circular preformed mesh, diameter of 8 centimeters, transfascial suture fixation, correct mesh placement and unfolding may be verified by laparoscopy, reduced costs. The technique is easy to reproduce.

[Pancreas divisum--a rare cause of chronic pancreatitis]. / Pancreas divisum--cauza rara de pancreatita cronica.

Pancreas divisum (P.D.) is a congenital anatomic variant, characterized by the nonunion of dorsal and ventral pancreatic ducts. A 20 years old man followed for 8 years with reccurent abdominal pain and relapsing acute pancreatitis develope chronic calcific pancreatitis. He was diagnosed with P.D. on endoscopic retrograde pancreatography and operative pancreatography. The patient was treated with longitudinal pancreatico-jejunostomy (PUESTOW-GILLESBY procedure). His pain resolved following surgical drainage of the pancreatic duct. Evaluation of the clinical course of this patient and critical review of other such cases in the literature support the role of compromised ductal drainage of the pancreas in the pathogenesis of chronic pancreatitis in P.D.