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In archaeology, heat treatment of stone is the process of “making” a new material for tool production. Its invention in the African Middle Stone Age was an important step in the evolution of transformative technologies and the cultural evolution of early humans in general. Although the chemical and crystallographic transformations in silica rocks, the only material class heat-treated in the Stone Age, begin to be well known, many of the mechanical transformations and their chemical origins remain a subject of controversy. The difference between different silica rock categories is also only poorly understood. In this paper, we investigate the thermally induced changes of three mechanical properties in the two silica rock types chert and silcrete: fracture strength, indentation fracture resistance (approximating fracture toughness) and elastic modulus. These tests are complemented by statistical analyses (Weibull modulus) and a quantitative fracture surface analysis. The results show that heat treatment transforms these silica rocks in terms of their fracture toughness and the uniformity of fracture. A comparison with published data on the structural transformations in the same samples identified the loss of chemically bound water and subsequent defect healing to be the chemical mechanism behind these mechanical transformations. These findings have important implications for the study of the interactions between chemical and structural processes and the mechanics of natural rocks or ceramics.

In archaeology, lithic heat treatment is the process of modifying a rock for stone tool production using fire. Although the earliest known cases of heat treatment come from South Africa and involved silcrete, a microcrystalline pedogenic silica rock, its thermal transformations remain poorly understood. We investigate the ‘water’-related transformations in silcrete using direct transmission near-infrared spectroscopy. We found that SiOH is noticeably lost between 250 and 450 °C and hydroxyl reacts with H 2 O, part of which is trapped in the structure of the rocks. This water can only be evaporated through heat-induced fracturing at high temperatures, imposing maximum temperatures for silcrete heat treatment of approximately 500 °C. Between 250 and 450 °C new siloxane bonds are formed according to the reaction 2SiOH → Si–O–Si + H 2 O, which can be expected to transform the rock’s mechanical properties. The tolerance of silcrete for relatively fast ramp rates can be explained by its pore volume and low SiOH content, ensuring good water evaporation. These results shed light on the processes taking place in silcrete during heat treatment and allow for a better understanding of the parameters needed for it.

What can we learn from nature?The study of the physical, chemical and structural properties of well-known minerals in the geo- and biosphere creates new opportunities for innovative applications in technology, environment or medicine.

Now the federal budget is out we all know who is guilty. Yes Cathy Lawery, (\"We know who!\" Feb. 20), it is the federal Liberal party.

When I moved to Ottawa I was shocked to find that 50 per cent of my taxes went towards schools.

In his Feb. 6 column, \"Tories should enter B.C.'s open door\", Peter Calamai states: \"Unless freedom of information thrives across this country, democracy itself is in serious jeopardy.

Mitochondria play a significant role in several cellular activities and their function in health and disease has become an important area of research. Since the brain is a high-energy-demanding organ, it is particularly vulnerable to mitochondrial dysfunction. This has been implicated in several brain disorders including neurodegenerative, psychiatric and neurological disorders, e.g., Parkinson’s disease and schizophrenia. Significant efforts are underway to develop mitochondria-targeting pharmaceutical interventions. However, the complex mitochondrial membrane network restricts the entry of therapeutic compounds into the mitochondrial matrix. Nanoparticles (NPs) present a novel solution to this limitation, while also increasing the stability of the therapeutic moieties and improving their bioavailability. This article provides a detailed overview of studies that have investigated the treatment of mitochondrial dysfunction in brain disorders using either targeted or non-targeted NPs as drug delivery systems. All the NPs showed improved mitochondrial functioning including a reduction in reactive oxygen species (ROS) production, an improvement in overall mitochondrial respiration and a reversal of toxin-induced mitochondrial damage. However, the mitochondrial-targeted NPs showed an advantage over the non-targeted NPs as they were able to improve or rescue mitochondrial dynamics and biogenesis, and they required a lower concentration of the in vivo therapeutic dosage of the drug load to show an effect. Consequently, mitochondria-targeted NPs are a promising therapeutic approach. Future studies should exploit advances in nanotechnology, neuroscience and chemistry to design NPs that can cross the blood-brain barrier and selectively target dysfunctional mitochondria, to improve treatment outcomes.

The goal of the Complex Trait Consortium is to promote the development of resources that can be used to understand, treat and ultimately prevent pervasive human diseases. Existing and proposed mouse resources that are optimized to study the actions of isolated genetic loci on a fixed background are less effective for studying intact polygenic networks and interactions among genes, environments, pathogens and other factors. The Collaborative Cross will provide a common reference panel specifically designed for the integrative analysis of complex systems and will change the way we approach human health and disease.