Single crystals of DPPH grown from diethyl ether and carbon disulfide solutions - Crystal structures, IR, EPR and magnetization studies

Single crystals of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) obtained from diethyl ether (ether) and carbon disulfide (CS2) were characterized by the X-ray diffraction, IR, EPR and SQUID magnetization techniques. The X-ray structural analysis and IR spectra showed that the DPPH form crystallized from ether (DPPH1) is solvent free, whereas that one obtained from CS2 (DPPH2) is a solvate of the composition 4DPPH.CS2. Principal values of the g-tensor were estimated by the X-band EPR spectroscopy at room and low (10 K) temperatures. Magnetization studies revealed the presence of antiferromagnetically coupled dimers in both types of crystals. However, the way of dimerization as well as the strength of exchange couplings are different in the two DPPH samples, which is in accord with their crystal structures. The obtained results improved parameters accuracy and enabled better understanding of properties of DPPH as a standard sample in the EPR spectrometry

Cystic lymphangioma of the pancreas mimicking pancreatic pseudocyst

Lymphangiomas are rare congenital benign tumors arising from the lymphatic system, and are mostly encountered in the neck and axillary regions of pediatric patients (95%). Lymphangioma of the pancreas is extremely rare accounting for less than 1% of these tumors. We report here on a case of pancreatic cystic lymphangioma. A 54-year-old woman presented with intermittent postprandial abdominal discomfort and radiating back pain. Abdominal computed tomography scan revealed 8 × 6.5 cm hypodense cystic mass arising from the tail of the pancreas without septa or solid component. The initial impression was a pancreatic pseudocyst. The patient underwent distal pancreatectomy with splenectomy. The histopathologic and immunohistochemical study helped make the diagnosis of a pancreatic cystic lymphangioma. Herein, we report a case of pancreatic cystic lymphangioma mimicking pancreatic pseudocyst and review the relevant medical literature

Volume element structure and roton-maxon-phonon excitations in superfluid helium beyond the Gross-Pitaevskii approximation

We propose a theory which deals with the structure and interactions of volume elements in liquid helium II. The approach consists of two nested models linked via parametric space. The short-wavelength part describes the interior structure of the fluid element using a non-perturbative approach based on the logarithmic wave equation; it suggests the Gaussian-like behaviour of the element's interior density and interparticle interaction potential. The long-wavelength part is the quantum many-body theory of such elements which deals with their dynamics and interactions. Our approach leads to a unified description of the phonon, maxon and roton excitations, and has noteworthy agreement with experiment: with one essential parameter to fit we reproduce at high accuracy not only the roton minimum but also the neighboring local maximum as well as the sound velocity and structure factor.Comment: 9 pages, 6 figure