Natural history, dynamics, and ecology of human papillomaviruses in genital infections of young women: protocol of the PAPCLEAR cohort study.

Introduction: Human papillomaviruses (HPVs) are responsible for one-third of all cancers caused by infections. Most HPV studies focus on chronic infections and cancers, and we know little about the early stages of the infection. Our main objective is to better understand the course and natural history of cervical HPV infections in healthy, unvaccinated and vaccinated, young women, by characterising the dynamics of various infection-related populations (virus, epithelial cells, vaginal microbiota and immune effectors).

High-pressure synthesis and characterization of iridium trihydride.

We have performed in situ synchrotron x-ray diffraction studies of the iridium-hydrogen system up to 125 GPa. At 55 GPa, a phase transition in the metal lattice from the fcc to a distorted simple cubic phase is observed. The new phase is characterized by a drastically increased volume per metal atom, indicating the formation of a metal hydride, and substantially decreased bulk modulus of 190 GPa (383 GPa for pure Ir).

Mixed molecular and atomic phase of dense hydrogen.

We used Raman and visible transmission spectroscopy to investigate dense hydrogen (deuterium) up to 315 (275) GPa at 300 K. At around 200 GPa, we observe the phase transformation, which we attribute to phase III, previously observed only at low temperatures. This is succeeded at 220 GPa by a reversible transformation to a new phase, IV, characterized by the simultaneous appearance of the second vibrational fundamental and new low-frequency phonon excitations and a dramatic softening and broadening of the first vibrational fundamental mode.

High-pressure synthesis, amorphization, and decomposition of silane.

By compressing elemental silicon and hydrogen in a diamond anvil cell, we have synthesized polymeric silicon tetrahydride (SiH(4)) at 124 GPa and 300 K. In situ synchrotron x-ray diffraction reveals that the compound forms the insulating I4(1)/a structure previously proposed from ab initio calculations for the high-pressure phase of silane. From a series of high-pressure experiments at room and low temperature on silane itself, we find that its tetrahedral molecules break up, while silane undergoes pressure-induced amorphization at pressures above 60 GPa, recrystallizing at 90 GPa into the polymeric crystal structures.

Correlation between structural and semiconductor-metal changes and extreme conditions materials chemistry in Ge-Sn.

High pressure and temperature experiments on Ge-Sn mixtures to 24 GPa and 2000 K reveal segregation of Sn from Ge below 10 GPa whereas Ge-Sn agglomerates persist above 10 GPa regardless of heat treatment. At 10 GPa Ge reacts with Sn to form a tetragonal P4(3)2(1)2 Ge(0.9)Sn(0.

Synthesis of a nitrogen-stabilized hexagonal Re(3)ZnN(x) phase using high pressures and temperatures.

High pressure can induce profound changes in solids. A significant barrier to new alloys and ceramics, however, is that targeted starting materials may not react with each other, even with the help of pressure. We use nitrogen, in a new capacity, to incorporate two otherwise unreactive elements, Re and Zn, in the same structure when pressure alone does not suffice, without nitrogen altering the resulting backbone structure.

Tuning between mixing and reactivity in the Ge-Sn system using pressure and temperature.

No bulk GeSn crystal existed prior to this work. Near 10 GPa the two elements resemble each other both electronically and structurally. Synthesis experiments at 10 GPa and 1500 K followed by annealing at 770 K using Ge and Sn starting materials and ex-situ analysis using transmission electron microscopy, scanning electron microscopy, and X-ray diffraction document the recovery of a Ge(0.

On the structure of high-pressure high-temperature eta-O2.

In situ high-pressure high-temperature x-ray diffraction and optical studies have been conducted on solid oxygen between 10 and 20 GPa and up to 700 K. Optical observations and Raman spectroscopic studies have been utilized to confirm the existence of eta-O(2) and to identify phase behavior and phase boundaries of beta-, epsilon- and eta-O(2) at elevated temperatures. Subsequent single-crystal synchrotron x-ray diffraction studies yielded the structure of the eta-O(2) phase at 15.

Structural diversity of sodium.

Sodium exhibits a pronounced minimum of the melting temperature at approximately 118 gigapascals and 300 kelvin. Using single-crystal high-pressure diffraction techniques, we found that the minimum of the sodium melting curve is associated with a concentration of seven different crystalline phases. Slight changes in pressure and/or temperature induce transitions between numerous structural modifications, several of which are highly complex.