Shear-induced reinforcement in boehmite gels: a rheo-X-ray-scattering study

Boehmite, an aluminum oxide hydroxide $\gamma$-AlO(OH), is broadly used in the form of particulate dispersions in industrial applications, e.g., for the fabrication of ceramics and catalyst supports or as a binder for extrusion processes. Under acidic conditions, colloidal boehmite dispersions at rest form gels, i.e., space-spanning percolated networks that behave as soft solids at rest, and yet yield and flow like liquids under large enough deformations. Like many other colloidal gels, the solid-like properties of boehmite gels at rest are very sensitive to their previous mechanical history. Our recent work [Sudreau et al., J. Rheol. 66, 91-104 (2022), and Phys. Rev. Material 6, L042601 (2022)] has revealed such \textit{memory effects}, where the shear experienced prior to flow cessation drives the elasticity of boehmite gels: while gels formed following application of a shear rate $\dot\gamma_{\rm p}$ larger than a critical value $\dot\gamma_{\rm c}$ are insensitive to shear history, gels formed after application of $\dot\gamma_{\rm p}<\dot\gamma_{\rm c}$ display reinforced viscoelastic properties and non-negligible residual stresses. Here, we provide a microstructural scenario for these striking observations by coupling rheometry and small-angle X-ray scattering. Time-resolved measurements for $\dot\gamma_{\rm p} <\dot\gamma_{\rm c}$ show that scattering patterns develop an anisotropic shape that persists upon flow cessation, whereas gels exposed to $\dot\gamma_{\rm p}>\dot\gamma_{\rm c}$ display isotropic scattering patterns upon flow cessation. Moreover, as the shear rate applied prior to flow cessation is decreased below $\dot\gamma_{\rm c}$, the level of anisotropy frozen in the sample microstructure grows similarly to the viscoelastic properties, thus providing a direct link between mechanical reinforcement and flow-induced microstructural anisotropy.Comment: 13 pages, 10 figure

Melarsoprol cyclodextrin inclusion complexes as promising oral candidates for the treatment of human African trypanosomiasis

Human African trypanosomiasis (HAT), or sleeping sickness, results from infection with the protozoan parasites &lt;i&gt;Trypanosoma brucei&lt;/i&gt; (&lt;i&gt;T.b.&lt;/i&gt;) &lt;i&gt;gambiense&lt;/i&gt; or &lt;i&gt;T.b.rhodesiense&lt;/i&gt; and is invariably fatal if untreated. There are 60 million people at risk from the disease throughout sub-Saharan Africa. The infection progresses from the haemolymphatic stage where parasites invade the blood, lymphatics and peripheral organs, to the late encephalitic stage where they enter the central nervous system (CNS) to cause serious neurological disease. The trivalent arsenical drug melarsoprol (Arsobal) is the only currently available treatment for CNS-stage &lt;i&gt;T.b.rhodesiense&lt;/i&gt; infection. However, it must be administered intravenously due to the presence of propylene glycol solvent and is associated with numerous adverse reactions. A severe post-treatment reactive encephalopathy occurs in about 10% of treated patients, half of whom die. Thus melarsoprol kills 5% of all patients receiving it. Cyclodextrins have been used to improve the solubility and reduce the toxicity of a wide variety of drugs. We therefore investigated two melarsoprol cyclodextrin inclusion complexes; melarsoprol hydroxypropyl-&#846;-cyclodextrin and melarsoprol randomly-methylated-&#946;-cyclodextrin. We found that these compounds retain trypanocidal properties &lt;i&gt;in vitro&lt;/i&gt; and cure CNS-stage murine infections when delivered orally, once per day for 7-days, at a dosage of 0.05 mmol/kg. No overt signs of toxicity were detected. Parasite load within the brain was rapidly reduced following treatment onset and magnetic resonance imaging showed restoration of normal blood-brain barrier integrity on completion of chemotherapy. These findings strongly suggest that complexed melarsoprol could be employed as an oral treatment for CNS-stage HAT, delivering considerable improvements over current parenteral chemotherapy

CHAPTER 8. Arsenic-based Anticancer Agents

International audienceArsenic-based drugs were widely used in the treatment of infectious diseases in the 1900s, but cancer treatment has advanced with the marketing of Trisenox® (INN: arsenic trioxide) for treatment of acute promyelocytic leukemia in the 2000s. In this chapter, I first review the history of the treatment of cancer by arsenic. In the 17th century, some physicians were convinced that an external application of powder could reduce breast cancer cells. Those adventurous applications led only to tissue necrosis, and we now understand how dangerous it was for the patient. An important step forward was also made with Fowler's solution, which would be orally administered. Afterwards, Cutler and Bradford demonstrated that this solution drastically reduced the number of neutrophils in myelogenous leukemia. The more recent marketing of Trisenox® and its unique efficacy in the treatment of acute promyelocytic leukemia raised questions about the mechanism of action of arsenic in cancer treatment. Finally, this chapter summarizes the major mechanisms that lead to the reduction in growth and proliferation of cancer cells. At a molecular level, arsenic is thought to link to numerous proteins (i.e., via the thiol groups of the amino acid side-chains). We know now that some very specific targets exist that are worthy of study

Mise en place d'un projet d'étude des concentrations plasmatiques de pipéracilline-tazobactam administrée par perfusion continue ou discontinue lors d'un traitement d'exacerbations bronchiques aigues à Pseudomonas aeruginosa dans la mucoviscidose

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocNANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Le syndrome des jambes sans repos et les troubles du sommeil (prise en charge officinale)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF

Le syndrome des jambes sans repos et les troubles du sommeil (prise en charge officinale)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF

Evaluation des pratiques professionnelles (audit clinique ciblé sur l'antibioprophylaxie en chirurgie orthopédique, gynécologique et viscérale de première intention)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF

Nutrition parentérale et médicaments intraveineux au CHU de Nancy (enquête transversale sur la prescription, les modes d'administration et la comptabilité)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocNANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Les aspects réglementaires et organisationnels d'une banque de tumeur ou tumorothèque (application au Centre régional de lutte contre le cancer Alexis Vautrin)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocNANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Evolution de l'univers psychiatrique en France et en Italie (bilan aujourd'hui)

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF