High-pressure structural and vibrational properties of monazite-type BiPO4, LaPO4, CePO4, and PrPO4

Monazite-type BiPO₄, LaPO₄, CePO₄, and PrPO₄ have been studied under high pressure by ab initio simulations and Raman spectroscopy measurements in the pressure range of stability of the monazite structure. A good agreement between experimental and theoretical Raman-active mode frequencies and pressure coefficients has been found which has allowed us to discuss the nature of the Raman-active modes. Besides, calculations have provided us with information on how the crystal structure is modified by pressure. This information has allowed us to determine the equation of state and the isothermal compressibility tensor of the four studied compounds. In addition, the information obtained on the polyhedral compressibility has been used to explain the anisotropic axial compressibility and the bulk compressibility of monazite phosphates. Finally, we have carried out a systematic discussion on the high-pressure behavior of the four studied phosphates in comparison to results of previous studies.

Experimental and theoretical study on the optical properties of LaVO4 crystals under pressure

We report optical absorption and luminescence measurements in pure and trivalent neodymium (Nd³⁺) doped LaVO₄ crystals up to 25 GPa. We also present the theoretical framework to accurately explain the observed experimental results.

Consensus guidelines for diagnosis, treatment and follow-up of patients with pancreatic cancer in Spain

The management of patients with pancreatic cancer has advanced over the last few years. We convey a multidisciplinary group of experts in an attempt to stablish practical guidelines for the diagnoses, staging and management of these patients. This paper summarizes the main conclusions of the working group. Patients with suspected pancreatic ductal adenocarcinoma should be rapidly evaluated and referred to high-volume centers. Multidisciplinary supervision is critical for proper diagnoses, staging and to frame a treatment plan. Surgical resection together with chemotherapy offers the highest chance for cure in early stage disease. Patients with advanced disease should be classified in treatment groups to guide systemic treatment. New chemotherapeutic regimens have resulted in improved survival. Symptomatic management is critical in this disease. Enrollment in a clinical trial is, in general, recommended.

Structural and vibrational properties of corundum-type In2O3 nanocrystals under compression

This work reports the structural and vibrational properties of nanocrystals of corundum-type In₂O₃ (rh-In₂O₃) at high pressures by using angle-dispersive x-ray diffraction and Raman scattering measurements up to 30 GPa. The equation of state and the pressure dependence of the Raman-active modes of the corundum phase in nanocrystals are in good agreement with previous studies on bulk material and theoretical simulations on bulk rh-In₂O₃. Nanocrystalline rh-In₂O₃ showed stability under compression at least up to 20 GPa, unlike bulk rh-In₂O₃ which gradually transforms to the orthorhombic Pbca (Rh₂O₃-III-type) structure above 12-14 GPa. The different stability range found in nanocrystalline and bulk corundum-type In₂O₃ is discussed.

High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO4 and TmPO4

Zircon-type holmium phosphate (HoPO₄) and thulium phosphate (TmPO₄) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures. Furthermore, the elastic anisotropy is enhanced upon compression. Finally, the calculations indicate that the possible causes that make the zircon structure unstable are mechanical instabilities and the softening of a silent B _1u mode.

ScVO4 under non-hydrostatic compression: a new metastable polymorph

The high-pressure (HP) behaviour of scandium vanadate (ScVO₄) is investigated under non-hydrostatic compression. The compound is studied by means of synchrotron-based powder x-ray diffraction (XRD) and optical-absorption techniques. The occurrence of a non-reversible phase transition is detected. The transition is from the zircon structure to the fergusonite-type structure and takes place around 6 GPa with nearly 10% volume discontinuity. XRD measurements on the pressure cycled sample confirm for the first time that the fergusonite-type ScVO₄ can be recovered as the metastable phase at ambient conditions. Raman spectroscopic measurements verify the metastable phase to be of a fergusonite-type phase. Theoretical calculations also corroborate the experimental findings. The fergusonite phase is found to be stiffer than the ambient-pressure zircon phase, as indicated by the observed experimental and theoretical bulk moduli. The optical properties and lattice-dynamics calculation of the fergusonite ScVO₄ are discussed. At ambient pressure the band gap of the zircon (fergusonite)-type ScVO₄ is 2.75 eV (2.3 eV). This fact suggests that the novel metastable polymorph of ScVO₄ can have applications in green technologies; for instance, it can be used as photocatalytic material for hydrogen production by water splitting.

Arsenolite: a quasi-hydrostatic solid pressure-transmitting medium

This study reports the experimental characterization of the hydrostatic properties of arsenolite (As4O6), a molecular solid which is one of the softest minerals in the absence of hydrogen bonding. The high compressibility of arsenolite and its stability up to 15 GPa have been proved by x-ray diffraction measurements, and the progressive loss of hydrostaticity with increasing pressure up to 20 GPa has been monitored by ruby photoluminescence. Arsenolite has been found to exhibit hydrostatic behavior up to 2.5 GPa and a quasi-hydrostatic behavior up to 10 GPa at room temperature. This result opens the way to explore other molecular solids as possible quasi-hydrostatic pressure-transmitting media. The validity of arsenolite as an insulating, stable, non-penetrating and quasi-hydrostatic medium is explored by the study of the x-ray diffraction of zeolite ITQ-29 at high pressure.

Aortography Delays Surgery of CT Proven Acute Traumatic Rupture of the Thoracic Aorta

A case of acute traumatic rupture of the thoracic aorta was diagnosed by dynamic CT. Angiographic confirmation was required, delaying surgical repair and contributing to the fatal outcome. If reliable findings of acute traumatic rupture of the thoracic aorta are shown by CT, we question the usefulness of angiographic confirmation in such cases.

PGA1-induced apoptosis involves specific activation of H-Ras and N-Ras in cellular endomembranes

The cyclopentenone prostaglandin A₁ (PGA₁) is an inducer of cell death in cancer cells. However, the mechanism that initiates this cytotoxic response remains elusive. Here we report that PGA₁ triggers apoptosis by a process that entails the specific activation of H- and N-Ras isoforms, leading to caspase activation. Cells without H- and N-Ras did not undergo apoptosis upon PGA₁ treatment; in these cells, the cellular demise was rescued by overexpression of either H-Ras or N-Ras. Consistently, the mutant H-Ras-C118S, defective for binding PGA₁, did not produce cell death. Molecular analysis revealed a key role for the RAF-MEK-ERK signaling pathway in the apoptotic process through the induction of calpain activity and caspase-12 cleavage. We propose that PGA₁ evokes a specific physiological cell death program, through H- and N-Ras, but not K-Ras, activation at endomembranes. Our results highlight a novel mechanism that may be of potential interest for tumor treatment.

DNA repair pathways to regulate response to chemoradiotherapy in patients with locally advanced head and neck cancer

Platinum-based chemoradiotherapy (CRT) is a preferred standard of care for locally advanced head and neck cancer (HNC). However, survival benefit is small, with substantial toxicity and biomarkers of CRT resistance that could guide treatment selection and spare morbidity. Increased DNA repair in solid tumors may contribute to cancer cells' ability to survive in genotoxic stress environments afforded by therapy. We assessed mRNA expression levels of DNA repair-related genes BRCA1, RAP80, 53 binding protein 1 (53BP1), mediator of DNA damage checkpoint 1 (MDC1), and RNF8. We correlated our findings with response and overall survival in 72 head and neck patients treated with weekly carboplatin AUC 2 and radiotherapy. Complete response (CR) to CRT was 50 % in patients with low levels of 53BP1 compared to 6.3 % in patients with high levels (p = 0.0059). Of high BRCA1 mRNA expressors, 41.2 % had CR compared to 29.4 % of low expressors (p = 0.72). For a small group of patients with low 53BP1 and either high BRCA1 or RAP80, CRs were 66.7 and 71.4 %, respectively. A trend for better overall survival (OS) was found for patients with low 53BP1 (15 vs 8 m; p = 0.056). Our findings highlight the potential usefulness of 53BP1 mRNA as a predictive biomarker of response and overall survival in HNC patients treated with chemoradiotherapy. Those with high 53BP1 expression could derive only a meager benefit from treatment. Analysis of BRCA1 and RAP80 could further reinforce the predictive value of 53BP1. Although this was a retrospective study with small sample size, it could inform larger translational studies in HNC.