Comparative study of ion milling techniques for the preparation of ceramic fibers in transmission electron microscopy.

Sample preparation, essential to any analysis, remains an under-documented step. Preparation methods for transmission electron microscopy (TEM) are complex and lead to artifacts that need to be identified to avoid wrong conclusions about the sample's microstructure. Ion milling techniques are increasingly becoming the reference techniques to prepare thin foils. The possibilities of different ion beam processes for milling samples will be shown and compared, using ceramic carbon/carbide fibers, a material applied in many industrial applications, as a test specimen. This overview of ion milling preparation techniques will enable us to identify the advantages, disadvantages and parameters in order to best prepare these thin samples. It will be carried out for the community, and will also highlight a new preparation method for ceramic fibers to minimize the artefacts inherent in these techniques.

The rocky road to organics needs drying.

How simple abiotic organic compounds evolve toward more complex molecules of potentially prebiotic importance remains a missing key to establish where life possibly emerged. The limited variety of abiotic organics, their low concentrations and the possible pathways identified so far in hydrothermal fluids have long hampered a unifying theory of a hydrothermal origin for the emergence of life on Earth. Here we present an alternative road to abiotic organic synthesis and diversification in hydrothermal environments, which involves magmatic degassing and water-consuming mineral reactions occurring in mineral microcavities. This combination gathers key gases (N2, H2, CH4, CH3SH) and various polyaromatic materials associated with nanodiamonds and mineral products of olivine hydration (serpentinization). This endogenous assemblage results from re-speciation and drying of cooling C-O-S-H-N fluids entrapped below 600 °C-2 kbars in rocks forming the present-day oceanic lithosphere. Serpentinization dries out the system toward macromolecular carbon condensation, while olivine pods keep ingredients trapped until they are remobilized for further reactions at shallower levels. Results greatly extend our understanding of the forms of abiotic organic carbon available in hydrothermal environments and open new pathways for organic synthesis encompassing the role of minerals and drying. Such processes are expected in other planetary bodies wherever olivine-rich magmatic systems get cooled down and hydrated.

Study of Molecular-Level Dispersion of Pristine Graphene in Aqueous Media via Polyvinyl Alcohol Coil Physisorption.

Graphene has been widely used as a nanofiller in advanced electronic devices and nanocomposite materials to achieve enhanced electronic, mechanical, and barrier properties. Adequate polymers play the role of the composite matrix and can assist in the liquid-phase exfoliation of pristine graphene without any heavy chemical modification and the detriment of the properties of graphene. This stabilization mechanism is generally attributed to the steric forces formed between the polymer-adsorbed adsorbent. However, the key influence of the polymer concentration on the maximum graphene content in the colloidal solutions is still unclear. In this study, three different molar weights of water-soluble polyvinyl alcohol (PVA) were used for graphene dispersion. The influence of the PVA concentration on the graphene dispersion was systematically studied. Based on Flory's theory, we first proposed a model to describe the polymer adsorption process in the graphene/PVA/water ternary system in the "dilute" regime and simulated the adsorption-free energy changes during this transformation. This model is in good agreement with the experimental results and explains the critical polymer concentration, Cc, allowing the optimization of the graphene/polymer ratio. This fundamental understanding of polymer physisorption on 2D materials provides a simple method for producing nanocomposites with controlled nanosheet/polymer ratios and structures, which are of great interest for energy devices and biomaterials.

Incorporation of Manganese Complexes within Hybrid Resol-Silica and Carbon-Silica Nanoparticles.

The incorporation of a luminescent probe into a nano-vector is one of the approaches used to design chemosensors and nanocargos for drug delivery and theranostics. The location of the nano-vector can be followed using fluorescence spectroscopy together with the change of environment that affects the fluorescence properties. The ligand 9-anthracene carboxylate is proposed in this study as a luminescent probe to locate two types of manganese complexes inside three series of porous nanoparticles of different composition: resol-silica, carbon-silica and pure silica. The manganese complexes are a tetranuclear MnIII cluster [MnIII4(µ-O)2(µ-AntCO2)6(bpy)2(ClO4)2] with a butterfly core, and a MnII dinuclear complex [{MnII(bpy)(AntCO2)}2(µ-AntCO2)2(µ-OH2)]. The magnetic measurements indicate that both complexes are present as dinuclear entities when incorporated inside the particles. Both the Mn complexes and the nanoparticles are luminescent. However, when the metal complexes are introduced into the nanoparticles, the luminescent properties of both are altered. The study of the fluorescence of the nanoparticles' suspensions and of the supernatants shows that MnII compounds seem to be more retained inside the particles than MnIII compounds. The resol-silica nanoparticles with MnII complexes inside is the material that presents the lowest complex leaching in ethanol.

Identification of inorganic particles resulting from degradation of ESSURE® implants: Study of 10 cases.

OBJECTIVE: Approximately 750,000 women worldwide have undergone ESSURE hysteroscopic sterilization since 2002. In 2015, an increase in adverse effects was noted, with gynaecological and systemic symptoms reported. Scanning electron microscopy (SEM) analysis of fallopian tube and uterine horn tissues and implants, after hysterectomy or salpingectomy, revealed the presence of inorganic particles resulting from implant degradation. STUDY DESIGN: Ten patients (age 42-53 years) were included in this study. Of these, eight patients had undergone hysterectomy and two patients had undergone salpingectomy. Mean exposure time was 85.5 months (standard deviation 26.8 months, range 34-105 months). Mineralogical analyses were performed on 13 tissue biopsies and four implants by SEM coupled with energy dispersive x-ray spectrometry. RESULTS: In five of the 10 patients, tin particles were observed in fallopian tube or uterine horn tissues with inflammatory cell reactions. In the other five cases, iron, chromium, nickel or platinum particles were observed. For implants, major deterioration of the weld zone was observed with either destroyed appearance or the presence of an organic coating containing numerous particles. DISCUSSION AND CONCLUSION: Analysis of the preclinical studies performed by the manufacturer suggests that degradation of the tin weld plays a major role in these adverse events, with increasing leaching and corrosion between 3 and 6 months for an intratubal insert that si designed to remain in an woman's body for her entire life. For patients with gynaecological symptoms (e.g. pain, metrorragies) needing explantation, these findings raise the question of a causal relationship between tin particles from implant degradation and the inflammatory tissue response. For patients with systemic symptoms (e.g. blurred vision, headache, asthenia, myalgia), the hypothesis that these symptoms may be related to the formation of organotin (chemical compounds based on tin with hydrocarbon substituents) in the body has yet to be proven. Tin levels in blood have to be measured before and after explantation. To the authors' knowledge, this is the first study to report significant degradation of the ESSURE implant weld, evidenced by the detection of tin particles in the uterine tissue of patients and comparison of the welding zone between unused and used implants.