Understanding Pressure Effects on Structural, Optical, and Magnetic Properties of CsMnF and Other 3d Compounds.

The pressure dependence of structural, optical, and magnetic properties of the layered compound CsMnF are explored through first-principles calculations. The structure at ambient pressure does not arise from a Jahn-Teller effect but from an orthorhombic instability on MnF units in the tetragonal parent phase, while there is a 4/ → 4 structural phase transition at = 40 GPa discarding a spin crossover transition from = 2 to = 1. The present results reasonably explain the evolution of spin-allowed d-d transitions under pressure, showing that the first transition undergoes a red-shift under pressure following the orthorhombic distortion in the layer plane.

Strain-Phonon Cooperation as a Necessary Ingredient to Understand the Jahn-Teller Effect in Solids.

Spatial degeneracy is the cause of the complex electronic, geometrical, and magnetic structures found in a number of materials whose more representative example is KCuF. In the literature the properties of this lattice are usually explained through the Kugel--Khomskii model, based on superexchange interactions. Here we provide rigorous theoretical and computational arguments against this view proving that structural and magnetic properties essentially arise from electron-vibration (vibronic) interactions.

Chemical Bonding, 10Dq Parameter and Superexchange in the Model Compound KNiF.

The cubic field splitting parameter, 10Dq, plays a central role in the ligand field theory on insulating transition metal compounds. Experimental data obtained in the last 50 years prove that 10Dq is highly dependent on changes of the metal-ligand distance, R, induced by chemical or applied pressures. Despite this fact has important consequences on optical and magnetic properties of such compounds, its actual origin is still controversial.

Red Shift in Optical Excitations on Layered Copper Perovskites under Pressure: Role of the Orthorhombic Instability.

The red shift under pressure in optical transitions of layered compounds with CuCl units is explored through first-principles calculations and the analysis of available experimental data. The results on Cu -doped (C H NH ) CdCl , that is taken as a guide, show the existence of a highly anisotropic response to pressure related to a structural instability, driven by a negative force constant, that leads to an orthorhombic geometry of CuCl units but with a hole displaying a dominant 3z -r character (z being the direction perpendicular to the layer plane). As a result of such an instability, a pressure of only 3 GPa reduces by 0.

Pressure Effects on 3d (n=4, 9) Insulating Compounds: Long Axis Switch in Na MnF not Due to the Jahn-Teller Effect.

The pressure-induced switch of the long axis of MnF units in the monoclinic Na MnF compound and Mn -doped Na FeF is explored with the help of first principles calculations. Although the switch phenomenon is usually related to the Jahn-Teller effect, we show that, due to symmetry reasons, it cannot take place in 3d (n=4, 9) systems displaying a static Jahn-Teller effect. By contrast, we prove that in Na MnF the switch arises from the anisotropic response of the low symmetry lattice to hydrostatic pressure.

New Ideas for Understanding the Structure and Magnetism in AgF : Prediction of Ferroelasticity.

In the search for new high-temperature superconductors, it has been proposed that there are strong similarities between the fluoroargentate AgF and the cuprate La CuO . We explored the origin of the possible layered structure of AgF by studying its parent high-symmetry phase and comparing these results with those of a seemingly analogous cuprate, CuF . Our findings first stress the large differences between CuF and AgF .

Ground State and Optical Excitations in Compounds with Tetragonal CuF Units: Insight into KAlCuF and CuFAsF.

It has been argued that AAlCuF (A = K, Cs) and CuFAsF are the only known crystals that exhibit compressed CuF units due to the Jahn-Teller effect. However, no grounds for this singular behavior have yet been reported. By means of first-principles calculations on such compounds and the isomorphous compounds involving Zn ions instead of Cu, we prove that neither the ground state nor the equilibrium geometry of CuF complexes in KAlCuF and CuFAsF is the result of a Jahn-Teller effect.

Understanding the Structure and Ground State of the Prototype CuF Compound Not Due to the Jahn-Teller Effect.

Insulating CuF is considered a prototype compound displaying a Jahn-Teller effect (JTE) which gives rise to elongated CuF units. By means of first-principles calculations together with an analysis of experimental data of both CuF and Cu-doped ZnF, we demonstrate that such an idea is not correct. For ZnF:Cu, we find that CuF units are compressed always along the Z local axis with a hole essentially in a 3 z- r antibonding orbital, in agreement with experimental EPR data that already underline the absence of a JTE.

Toxic epidermal necrolysis: a paradigm of critical illness.

Toxic epidermal necrolysis is an adverse immunological skin reaction secondary in most cases to the administration of a drug. Toxic epidermal necrolysis, Stevens-Johnson syndrome, and multiform exudative erythema are part of the same disease spectrum. The mortality rate from toxic epidermal necrolysis is approximately 30%.

Cervical cancer screening cotesting with cytology and MRNA HPV E6/E7 yields high rates of CIN2+ lesions in young women.

Background: European guidelines recommend primary HPV testing for cervical cancer screening. However, the starting age remains to be defined, with an undecided window between 30 and 35 years. This pilot study compares the effectiveness of primary HPV testing to that of cytology for the detection of high-grade (CIN2+) lesions stratified by age.

Large Differences in the Optical Spectrum Associated with the Same Complex: The Effect of the Anisotropy of the Embedding Lattice.

Transition-metal complexes with a well-defined geometry are usually considered to display almost the same properties independently of the system where they are embedded. Here we show that the above statement is not true depending on the anisotropy of the host lattice, which is revealed in the form of the electric field created by the rest of lattice ions over the complex. To illustrate this concept we analyze the origin of the surprisingly large differences in the d-d optical transitions of two systems containing square-planar CuF complexes, CaCuF, and center II in Cu-doped BaZnF, even though the Cu-Fdistance difference is just found to be 1%.

Significant HLA class I type associations with aromatic antiepileptic drug (AED)-induced SJS/TEN are different from those found for the same AED-induced DRESS in the Spanish population.

Aromatic antiepileptic drugs (AEDs) are among the drugs most frequently involved in severe cutaneous adverse reactions (SCARs), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reactions with eosinophilia and systemic symptoms (DRESS). This study investigated the associations between the genetic polymorphisms of HLA class-I and AED-induced SCARs in the Spanish population. HLA class-I genotypes were determined in AED (phenytoin[PHT],lamotrigine[LTG],carbamazepine[CBZ],phenobarbital[PB])-induced SJS/TEN (n=15) or DRESS (n=12) cases included in the Spanish SCAR registry, PIELenRed.

Cytological Diagnosis of Bilateral Breast Implant-Associated Lymphoma of the ALK-Negative Anaplastic Large-Cell Type. Clinical Implications of Peri-Implant Breast Seroma Cytological Reporting.

The cytological examination of peri-prosthetic breast effusions allowed the diagnosis of bilateral breast-implant ALK-negative anaplastic large cell lymphoma (BI-ALCL) in the case reported. Ten years after reconstructive surgery with bilateral breast implants, a large unilateral seroma developed and was cytologically analyzed. The presence of CD30 and CD4-positive large-sized atypical lymphoid cells exhibiting horseshoe-shaped nuclei and a brisk mitotic activity rendered the diagnosis of BI-ALCL.

A Genuine Jahn-Teller System with Compressed Geometry and Quantum Effects Originating from Zero-Point Motion.

First-principle calculations together with analysis of the experimental data found for 3d(9) and 3d(7) ions in cubic oxides proved that the center found in irradiated CaO:Ni(2+) corresponds to Ni(+) under a static Jahn-Teller effect displaying a compressed equilibrium geometry. It was also shown that the anomalous positive g∥ shift (g∥ -g0 =0.065) measured at T=20 K obeys the superposition of the |3 z(2) -r(2) ⟩ and |x(2) -y(2) ⟩ states driven by quantum effects associated with the zero-point motion, a mechanism first put forward by O'Brien for static Jahn-Teller systems and later extended by Ham to the dynamic Jahn-Teller case.

The HLA-B*15:02 allele in a Spanish Romani patient with carbamazepine-induced Stevens-Johnson syndrome.

The HLA-B*15:02 allele is a risk factor for carbamazepine (CBZ)-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in populations where the allele is prevalent. Han Chinese and Thai patients are advised to take a genetic test before introducing CBZ. Such testing is not recommended for patients of European descent.

Clear Cell Atypical Fibroxanthoma: Clinicopathological Study of 6 Cases and Review of the Literature With Special Emphasis on the Differential Diagnosis.

Atypical fibroxanthoma (AFX) is an uncommon dermal-based neoplasm arising on the sun-damaged skin of elderly people. Clear cell AFX is a rare variant with only 12 cases reported until the present date, all of them as case reports, except for 1 small series of 3 cases. The authors report 6 new cases and review the literature with special emphasis on the differential diagnosis.

Pleomorphic dermal sarcoma: a more aggressive neoplasm than previously estimated.

Background: Pleomorphic dermal sarcoma (PDS) is a rare neoplasm sharing pathological features with atypical fibroxanthoma, but adding tumor necrosis, invasion beyond superficial subcutis or vascular or perineural infiltration. Although its metastatic risk has been estimated to be less than 5%, its real outcome is presently uncertain because of its rarity and to the lack of homogeneous criteria used in reported cases.

Methods: Retrospective clinicopathological study of 18 cases of PDS.

Origin of the exotic blue color of copper-containing historical pigments.

The study of chemical factors that influence pigment coloring is a field of fundamental interest that is still dominated by many uncertainties. In this Article, we investigate, by means of ab initio calculations, the origin of the unusual bright blue color displayed by historical Egyptian Blue (CaCuSi4O10) and Han Blue (BaCuSi4O10) pigments that is surprisingly not found in other compounds like BaCuSi2O6 or CaCuO2 containing the same CuO4(6-) chromophore. We show that the differences in hue between these systems are controlled by a large red-shift (up to 7100 cm(-1)) produced by an electrostatic field created by a lattice over the CuO4(6-) chromophore from the energy of the 3z(2)-r(2) → x(2)-y(2) transition, a nonlocal phenomenon widely ignored in the realm of transition metal chemistry and strongly dependent upon the crystal structure.

A Practical Computational Approach to Study Molecular Instability Using the Pseudo-Jahn-Teller Effect.

Vibronic coupling theory shows that the cause for spontaneous instability in systems presenting a nondegenerate ground state is the so-called pseudo-Jahn-Teller effect, and thus its study can be extremely helpful to understand the structure of many molecules. While this theory, based on the mixing of the ground and excited states with a distortion, has been long studied, there are two obscure points that we try to clarify in the present work. First, the operators involved in both the vibronic and nonvibronic parts of the force constant take only into account electron-nuclear and nuclear-nuclear interactions, apparently leaving electron-electron repulsions and the electron's kinetic energy out of the chemical picture.

Myxoinflammatory fibroblastic sarcoma of the face.

Myxoinflammatory fibroblastic sarcoma (MIFS) is a rare low-grade tumor of modified fibroblasts, with tendency to local recurrence. This unusual entity typically presents as a slow-growing painless mass in the distal extremities of middle-aged subjects. A 48-year-old woman presented to our clinic with a painless subcutaneous mass in the right temporal region.

The giant magnetic anisotropy energy of Fe+ ions in SrCl2.

We show that values of the magnetic anisotropy energy (MAE), which are about two orders of magnitude larger than the usual ones for transition metal cations in insulators (approximately 0.01-1 cm(-1)), can be found for the less common ion Fe+. In SrCl2:Fe+, the MAE is 93 cm(-1) when calculated using second-order perturbation multi-configurational calculations (CASPT2) while a similar value is found using multi-reference density functional theory (MR-DFT).

Cytopathology of a primary follicular dendritic cell sarcoma of the liver of the inflammatory pseudotumor-like type.

Follicular dendritic cell (FDC) sarcoma is an exceedingly uncommon tumor of lymph nodes and extranodal tissues. The inflammatory pseudotumor (IPT)-like variant of FDC sarcoma of intraabdominal location is considered a separate entity, with different clinical and pathological features than those of the classic FDC tumor. There have been only 12 cytological reports of FDC sarcomas in the literature.

Pathology of acute lung injury and acute respiratory distress syndrome: a clinical-pathological correlation.

Clinical criteria cannot identify all patients who develop acute respiratory distress syndrome, which might indicate the need to develop new tools that improve reliability and diagnostic accuracy. Nevertheless, being conscious of the limitations of the American-European consensus conference criteria continues to be useful in clinical daily practice because these patients would benefit from treatments. This and other management strategies have been evaluated in patients who, fulfilling the clinical criteria of acute respiratory distress syndrome, could not have diffuse alveolar damage.

Acute respiratory distress syndrome: underrecognition by clinicians and diagnostic accuracy of three clinical definitions.

Objective: To determine and compare the diagnostic accuracy of three clinical definitions of acute respiratory distress syndrome (ARDS): (1) the American-European consensus conference definition; (2) the lung injury score; and (3) a recently developed Delphi definition. A second objective was to determine the accuracy of clinical diagnoses of ARDS made in daily practice.

Design: Independent comparison of autopsy findings with the daily status of clinical definitions, constructed with data abstracted retrospectively from medical records.

Comparison of clinical criteria for the acute respiratory distress syndrome with autopsy findings.

Background: The American-European Consensus Conference definition for the acute respiratory distress syndrome (ARDS) has never been validated.

Objective: To compare clinical criteria for ARDS with autopsy findings.

Design: Independent comparison of autopsy findings with clinical characteristics retrospectively abstracted from medical records.