Structure of an amorphous calcium carbonate phase involved in the formation of shells.

Some mollusc shells are formed from an amorphous calcium carbonate (ACC) compound, which further transforms into a crystalline material. The transformation mechanism is not fully understood but is however crucial to develop bioinspired synthetic biomineralization strategies or accurate marine biomineral proxies for geoscience. The difficulty arises from the simultaneous presence of crystalline and amorphous compounds in the shell, which complicates the selective experimental characterization of the amorphous fraction.

Sub-micrometric spatial distribution of amorphous and crystalline carbonates in biogenic crystals using coherent Raman microscopy.

In living organisms, calcium carbonate biomineralization combines complex bio-controlled physical and chemical processes to produce crystalline hierarchical hard tissues (usually calcite or aragonite) typically from an amorphous precursor phase. Understanding the nature of the successive transient amorphous phases potentially involved in the amorphous-to-crystalline transition requires characterization tools, which are able to provide a spatial and spectroscopic analysis of the biomineral structure. In this work, we present a highly sensitive coherent Raman microscopy approach, which allows one to image molecular bond concentrations in post mortem shells and living animals, by exploiting the vibrational signature of the different carbonates compounds.

Amorphous-to-crystal transition in the layer-by-layer growth of bivalve shell prisms.

Biomineralization integrates complex physical and chemical processes bio-controlled by the living organisms through ionic concentration regulation and organic molecules production. It allows tuning the structural, optical and mechanical properties of hard tissues during ambient-condition crystallisation, motivating a deeper understanding of the underlying processes. By combining state-of-the-art optical and X-ray microscopy methods, we investigated early-mineralized calcareous units from two bivalve species, Pinctada margaritifera and Pinna nobilis, revealing chemical and crystallographic structural insights.

Molecular Pathways and Pigments Underlying the Colors of the Pearl Oyster var. (Linnaeus 1758).

The shell color of the Mollusca has attracted naturalists and collectors for hundreds of years, while the molecular pathways regulating pigment production and the pigments themselves remain poorly described. In this study, our aim was to identify the main pigments and their molecular pathways in the pearl oyster -the species displaying the broadest range of colors. Three inner shell colors were investigated-red, yellow, and green.

Interventions to increase the distribution of vaccines in Sub-Saharan Africa: a scoping review.

Achieving universal access to immunization, as envisioned in the global vaccine action plan continues to be a challenge for many countries in Sub-Saharan Africa. Weak immunization supply chain (iSC) has widely been recognized as a key barrier, hindering progress towards vaccination targets in this region. These iSCs, which were designed in the 1980s, have become increasing fragile and are now considered outdated.

Acceptability and Feasibility of Delivering Pentavalent Vaccines in a Compact, Prefilled, Autodisable Device in Vietnam and Senegal.

Background: Prefilled syringes are the standard in developed countries but logistic and financial barriers prevent their widespread use in developing countries. The current study evaluated use of a compact, prefilled, autodisable device (CPAD) to deliver pentavalent vaccine by field actors in Senegal and Vietnam.

Methods: We conducted a logistic, programmatic, and anthropological study that included a) interviews of immunization staff at different health system levels and parents attending immunization sessions; b) observation of immunization sessions including CPAD use on oranges; and c) document review.

The Benin experience: How computational modeling can assist major vaccine policy changes in low and middle income countries.

While scientific studies can show the need for vaccine policy or operations changes, translating scientific findings to action is a complex process that needs to be executed appropriately for change to occur. Our Benin experience provided key steps and lessons learned to help computational modeling inform and lead to major policy change. The key steps are: engagement of Ministry of Health, identifying in-country "champions," directed and efficient data collection, defining a finite set of realistic scenarios, making the study methodology transparent, presenting the results in a clear manner, and facilitating decision-making and advocacy.

One size does not fit all: The impact of primary vaccine container size on vaccine distribution and delivery.

Background: While the size and type of a vaccine container (i.e., primary container) can have many implications on the safety and convenience of a vaccination session, another important but potentially overlooked consideration is how the design of the primary container may affect the distribution of the vaccine, its resulting cost, and whether the vial is ultimately opened.