Hierarchical Levels Of Organization Research Articles

The Layer Cake Model of the World and Non-Reductive Physicalism

Abstract In this paper I argue that non-reductive physicalism (NRP) continues to rely on the ontological aspect of the layer cake model of the world (LCM). NRP is a post-unity account of the relationship between phenomena in the world in the sense that it has been developed in response to the perceived failure of the unity of science thesis. The LCM constitutes a framework for the organisation of phenomena in the world. It articulates the idea that phenomena in the world are organised into levels. Specifically, that phenomena are layered into distinct, hierarchical levels of organisation. Historically, the unity of science thesis and the LCM have been intertwined; the LCM being the framework within which a unity of science might be possible. My argument will demonstrate that, despite a move away from unity of science positions, the LCM persists in post-unity accounts. In order to argue for this thesis, I present a close analysis of Oppenheim & Putnam's classic presentation of the LCM; picking out the principle of hierarchic compositionality which, I argue, captures the ontological aspect of the LCM. I then demonstrate how NRP continues to rely upon the principle and, as a result, continues to support the ontological aspect of the LCM. This result is significant. It shows that whilst the rejection of the reductionist aspect of the thesis has served as the basis for post-unity positions these positions do not engage directly with the framework within which reduction might be facilitated - the LCM. Furthermore, it demonstrates that pluralist or disunity accounts of the relationship between phenomena in the world will also have to engage directly with the framework of the LCM in order to avoid being merely anti-reductionist.

An alternative perspective on interpretation of the secondary motor symptoms of Parkinson's disease

Objectives: Secondary motor symptoms of Parkinson disease, including slurred speech, swallowing dysfunction, masked face, reduced eye movement and micrographia, which observed in distal motor repertories (hands, fingers, jaw, mouth and feet), manifest an alteration of patterns of mechanical structure-function relationships of the system with the disrupted tensegrity equilibrium. Secondary motor symptoms indicate rigidity of minor parts of the body, decreased speed and amplitude. We propose that both cardinal and secondary motor symptoms, that find its manifestation in the different parts of the body and different levels of hierarchical organization, can be unified under the umbrella of rigidity. Tremor, which observed in distal motor repertories (hands, fingers, jaw, mouth and feet) indicate a disruption of tensegrity equilibrium, that may began in the lower level of hierarchy (autonomic organs) with a continuing progression to the higher levels of hierarchy.

An alternative perspective on interpretation of the secondary motor symptoms of Parkinson disease

Objectives: Secondary motor symptoms of Parkinson disease, including slurred speech, swallowing dysfunction, masked face, reduced eye movement and micrographia, which observed in distal motor repertories (hands, fingers, jaw, mouth and feet), manifest an alteration of patterns of mechanical structure-function relationships of the system with the disrupted tensegrity equilibrium. Secondary motor symptoms indicate rigidity of minor parts of the body, decreased speed and amplitude. We propose that both cardinal and secondary motor symptoms, that find its manifestation in the different parts of the body and different levels of hierarchical organization, can be unified under the umbrella of rigidity. Tremor, which observed in distal motor repertories (hands, fingers, jaw, mouth and feet) indicate a disruption of tensegrity equilibrium, that may began in the lower level of hierarchy (autonomic organs) with a continuing progression to the higher levels of hierarchy.

Ecological classification and mapping for landscape management and science

There is growing demand for biogeographical landscape classifications and ecological maps that describe patterns of spatially co-varying biotic and abiotic ecosystem components. This demand is fuelled by increasing data availability and processing capacity, by institutional practices of land and water resource management and planning and by the growth of transdisciplinary science that requires the development of a shared conceptual framework through which to view landscape character and behaviour. Despite the widespread use of ecological maps, and the extent to which they have become embedded in institutional practice, policy and law, no standard approach to ecosystem mapping has emerged, such that there are many valid ways of mapping the same landscape. Consensus is possible only when there is agreement on the spatial entities to be mapped. We propose a way of defining such entities and identifying them in any given landscape. Landscapes are conceived in terms of a conceptual biophysical template that constrains a wide range of ecological processes at various hierarchical levels. The template is conceived as comprising co-evolved associations of soils, vegetation, topography and hydrology that form a dynamic mosaic characteristic of a particular topographic, climatic and geological context that is continually being shaped by many perturbations. We synthesise themes from vegetation, soil and river sciences, using hierarchy theory to frame a perspective that facilitates the definition of mappable landscape entities at three hierarchical levels of organisation. These entities are conceived as archetypal structural-functional units, with form and process linked in conceptual models that underpin each archetype. We describe how our approach has been used to map ecological entities in Kruger National Park, South Africa, showing how the proposed framework integrates key system components, providing transparent foundations for transdisciplinary approaches to landscape management and science.

The Role of Water Compartments in the Material Properties of Cortical Bone.

Comprising ~20% of the volume, water is a key determinant of the mechanical behavior of cortical bone. It essentially exists in two general compartments: within pores and bound to the matrix. The amount of pore water-residing in the vascular-lacunar-canalicular space-primarily reflects intracortical porosity (i.e., open spaces within the matrix largely due to Haversian canals and resorption sites) and as such is inversely proportional to most mechanical properties of bone. Movement of water according to pressure gradients generated during dynamic loading likely confers hydraulic stiffening to the bone as well. Nonetheless, bound water is a primary contributor to the mechanical behavior of bone in that it is responsible for giving collagen the ability to confer ductility or plasticity to bone (i.e., allows deformation to continue once permanent damage begins to form in the matrix) and decreases with age along with fracture resistance. Thus, dehydration by air-drying or by solvents with less hydrogen bonding capacity causes bone to become brittle, but interestingly, it also increases stiffness and strength across the hierarchical levels of organization. Despite the importance of matrix hydration to fracture resistance, little is known about why bound water decreases with age in hydrated human bone. Using (1)H nuclear magnetic resonance (NMR), both bound and pore water concentrations in bone can be measured ex vivo because the proton relaxation times differ between the two water compartments, giving rise to two distinct signals. There are also emerging techniques to measure bound and pore water in vivo with magnetic resonance imaging (MRI). The NMR/MRI-derived bound water concentration is positively correlated with both the strength and toughness of hydrated bone and may become a useful clinical marker of fracture risk.

Higher-Order Architecture of Rhodopsin in Intact Photoreceptors and Its Implication for Phototransduction Kinetics

The visual pigment rhodopsin belongs to the family of G protein-coupled receptors that can form higher oligomers. It is controversial whether rhodopsin forms oligomers and whether oligomers are functionally relevant. Here, we study rhodopsin organization in cryosections of dark-adapted mouse rod photoreceptors by cryoelectron tomography. We identify four hierarchical levels of organization. Rhodopsin forms dimers; at least ten dimers form a row. Rows form pairs (tracks) that are aligned parallel to the disk incisures. Particle-based simulation shows that the combination of tracks with fast precomplex formation, i.e. rapid association and dissociation between inactive rhodopsin and the G protein transducin, leads to kinetic trapping: rhodopsin first activates transducin from its own track, whereas recruitment of transducin from other tracks proceeds more slowly. The trap mechanism could produce uniform single-photon responses independent of rhodopsin lifetime. In general, tracks might provide a platform that coordinates the spatiotemporal interaction of signaling molecules.

Four Levels of Hierarchical Organization, Including Noncovalent Chainmail, Brace the Mature Tumor Herpesvirus Capsid against Pressurization

Like many double-stranded DNA viruses, tumor gammaherpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus withstand high internal pressure. Bacteriophage HK97 uses covalent chainmail for this purpose, but how this is achieved noncovalently in the much larger gammaherpesvirus capsid is unknown. Our cryoelectron microscopy structure of a gammaherpesvirus capsid reveals a hierarchy of four levels of organization: (1) Within a hexon capsomer, each monomer of the major capsid protein (MCP), 1,378 amino acids and six domains, interacts with its neighboring MCPs at four sites. (2) Neighboring capsomers are linked in pairs by MCP dimerization domains and in groups of three by heterotrimeric triplex proteins. (3) Small (∼280 amino acids) HK97-like domains in MCP monomers alternate with triplex heterotrimers to form a belt that encircles each capsomer. (4) One hundred sixty-two belts concatenate to form noncovalent chainmail. The triplex heterotrimer orchestrates all four levels and likely drives maturation to an angular capsid that can withstand pressurization.

Implementation of Business Process Reengineering in Human Resource Management

The whole business of an organization is carried out through business processes. The process is a set of interconnected activities with interactions, which are transforming the object (as its input) into a result (as its output), where employees are adding a certain procedural values, using the resources of the organization. There are permanent requirements for the changes in performances, innovations, increasing flexibility and improving the economic performance of the company trough the process orientation.The main objective of this paper was to explore possibilities for improvement of important business processes, such as human resource management, in petroleum industry with the technique of business process reengineering and business process improvement. In this paper the authors presented the improvement process of one of the most important function in each organization – human resources function, by using management tools of BPR supported with the lean tools such as value stream mapping VSM. Methodology used in this paper included step approach in line with the Harvard Business School Business (HBS, 2010) process improvement supported with value stream mapping (VSM) lean tools.In the first part of the paper, the authors presented a theoretical review of the literature of business process reengineering and human resource management (HRM), with a special focus on the function of human resources in large companies where the research was done. After the theoretical review, business process improvement (BPI) of HRM in specific company was presented trough comparison of the state of HR function before restructuring and the state of the performances of the HR function after the BPI implementation with all the characteristics and efficiency indicators.Based on the obtained results, it can be concluded that the combination of HBS methodology and VSM tools can contribute to the improvement in the form of the reductions of hierarchical levels in organization within the company and in the form of advancement of work processes within the company. This was primarily reflected in the increase of the effectiveness and efficiency, in reducing of the time required for the execution of the processes, and saving resources.This paper presents one year case study, where the research was made to point out the significance of BPR of HR function in large companies. The authors tried to explain the main areas of HR process in a large production companies so as the improvements could be achieved by using BPR techniques supported by VSM lean tools.DOI: http://dx.doi.org/10.5755/j01.ee.25.2.4590

Three-dimensional structure of human lamellar bone: The presence of two different materials and new insights into the hierarchical organization

Lamellar bone is the most common bone type in humans. The predominant components of individual lamellae are plywood-like arrays of mineralized collagen fibrils aligned in different directions. Using a dual-beam electron microscope and the Serial Surface View (SSV) method we previously identified a small, but significantly different layer in rat lamellar bone, namely a disordered layer with collagen fibrils showing little or no preferred orientation. Here we present a 3D structural analysis of 12 SSV volumes (25 complete lamellae) from femora of 3 differently aged human individuals. We identify the ordered and disordered motifs in human bone as in the rat, with several significant differences. The ordered motif shows two major preferred orientations, perpendicular to the long axis of the bone, and aligned within 10–20° of the long axis, as well as fanning arrays. At a higher organizational level, arrays of ordered collagen fibrils are organized into ‘rods’ around 2 to 3μm in diameter, and the long axes of these ‘rods’ are parallel to the lamellar boundaries. Human bone also contains a disordered component that envelopes the rods and fills in the spaces between them. The disordered motif is especially well-defined between adjacent layers of rods. The disordered motif and its interfibrillar substance stain heavily with osmium tetroxide and Alcian blue indicating the presence of another organic component in addition to collagen. The canalicular network is confined to the disordered material, along with voids and individual collagen fibrils, some of which are also aligned more or less perpendicular to the lamellar boundaries. The organization of the ordered fibril arrays into rods enveloped in the continuous disordered structure was not observed in rat lamellar bone. We thus conclude that human lamellar bone is comprised of two distinct materials, an ordered material and a disordered material, and contains an additional hierarchical level of organization composed of arrays of ordered collagen fibrils, referred to as rods. This new structural information on human lamellar bone will improve our understanding of structure–mechanical function relations, mechanisms of mechano-sensing and the characterizations of bone pathologies.

Multi-scale integrated analysis of rural Laos: Studying metabolic patterns of land uses across different levels and scales

This paper presents an application of the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) approach to the analysis of rural land uses. Using secondary data on farming systems in Laos, we illustrate how the concept of metabolic pattern can be used to establish links between the various indicators of performance of rural systems. To this purpose, we characterize the socioeconomic activities in rural Laos by a series of quantitative indicators defined across: (i) different hierarchical levels of organization described at different scales (i.e. households, rural villages, administrative regions and the whole country) and (ii) different dimensions of analysis, including economic, agronomic, social, biophysical, and ecological analysis. The MuSIASEM approach simultaneously employs two non-equivalent criteria for quantification. The observed rural system is described in terms of an integrated set of flow elements (money, food, energy, water, fertilizer and other materials), which are mapped against two distinct fund elements: (i) a multi-level matrix of human activity (flows being expressed in terms of intensity per hour) and (ii) a multi-level matrix of land uses (flows being expressed as density per hectare). Our case study shows that in this way it is possible to move across different hierarchical levels, scales and dimensions, to arrive at an integrated representation of the metabolic pattern of farming systems.

Kiron System, an Integration of Living and Artificial Systems (Buildings Case)

Simultaneously satisfying human and environmental demands requires overarching concepts to facilitate the conciliation of such demands. These concepts are particularly necessary in certain regions where, as a result of rapid population growth, a large demand for housing impinges upon vital and sensitive ecosystems. The object of the present paper is to focus on the building concept in natural and rarely disturbed environments. Starting with the organizational logic that underlies living systems, this paper proposes a new hierarchical level of organization or hypothetical Kiron System (KS) that lies between the ecosystem and the human biosystem. The hypothetical system would serve to reconcile the requirements of both systems. From within this new hierarchical level, it is possible to extract the entire concept of the artificial sub‐system (the building) that would make such hypothetical system possible. Finally, the effects of this concept on the various functions of the building are analysed. Copyright © 2012 John Wiley & Sons, Ltd.

Hierarchical Dragonfly Wing: Microstructure-Biomechanical Behavior Relations

The dragonfly wing, which consists of veins and membrane, is of biological hierarchical material. We observed the cross-sections of longitudinal veins and membrane using Environmental Scanning Electron Microscopy (ESEM). Based on the experiments and previous studies, we described the longitudinal vein and the membrane in terms of two hierarchical levels of organization of composite materials at the micro- and nano-scales. The longitudinal vein of dragonfly wing has a complex sandwich structure with two chitinous shells and a protein layer, and it is considered as the first hierarchical level of the vein. Moreover, the chitinous shells are concentric multilayered structures. Clusters of nano-fibrils grow along the circumferential orientation embedded into the protein layer. It is considered as the second level of the hierarchy. Similarly, the upper and lower epidermises of membrane constitute the first hierarchical level of organization in micro scale. Similar to the vein shell, the membrane epidermises were found to be a paralleled multilayered structure, defined as the second hierarchical level of the membrane. Combining with the mechanical behavior analysis of the dragonfly wing, we concluded that the growth orientation of the hierarchical structure of the longitudinal vein and membrane is relevant to its biomechanical behavior.

On the evolution of morphogenetic models: mechano‐chemical interactions and an integrated view of cell differentiation, growth, pattern formation and morphogenesis

In the 1950s, embryology was conceptualized as four relatively independent problems: cell differentiation, growth, pattern formation and morphogenesis. The mechanisms underlying the first three traditionally have been viewed as being chemical in nature, whereas those underlying morphogenesis have usually been discussed in terms of mechanics. Often, morphogenesis and its mechanical processes have been regarded as subordinate to chemical ones. However, a growing body of evidence indicates that the biomechanics of cells and tissues affect in striking ways those phenomena often thought of as mainly under the control of cell-cell signalling. This accumulation of data has led to a revival of the mechano-transduction concept in particular, and of complexity in general, causing us now to consider whether we should retain the traditional conceptualization of development. The researchers' semantic preferences for the terms 'patterning', 'pattern formation' or 'morphogenesis' can be used to describe three main 'schools of thought' which emerged in the late 1970s. In the 'molecular school', the term patterning is deeply tied to the positional information concept. In the 'chemical school', the term 'pattern formation' regularly implies reaction-diffusion models. In the 'mechanical school', the term 'morphogenesis' is more frequently used in relation to mechanical instabilities. Major differences among these three schools pertain to the concept of self-organization, and models can be classified as morphostatic or morphodynamic. Various examples illustrate the distorted picture that arises from the distinction among differentiation, growth, pattern formation and morphogenesis, based on the idea that the underlying mechanisms are respectively chemical or mechanical. Emerging quantitative approaches integrate the concepts and methods of complex sciences and emphasize the interplay between hierarchical levels of organization via mechano-chemical interactions. They draw upon recent improvements in mathematical and numerical morphogenetic models and upon considerable progress in collecting new quantitative data. This review highlights a variety of such models, which exhibit important advances, such as hybrid, stochastic and multiscale simulations.

Biomimetic self-templating supramolecular structures

In nature, helical macromolecules such as collagen, chitin and cellulose are critical to the morphogenesis and functionality of various hierarchically structured materials. During tissue formation, these chiral macromolecules are secreted and undergo self-templating assembly, a process whereby multiple kinetic factors influence the assembly of the incoming building blocks to produce non-equilibrium structures. A single macromolecule can form diverse functional structures when self-templated under different conditions. Collagen type I, for instance, forms transparent corneal tissues from orthogonally aligned nematic fibres, distinctively coloured skin tissues from cholesteric phase fibre bundles, and mineralized tissues from hierarchically organized fibres. Nature's self-templated materials surpass the functional and structural complexity achievable by current top-down and bottom-up fabrication methods. However, self-templating has not been thoroughly explored for engineering synthetic materials. Here we demonstrate the biomimetic, self-templating assembly of chiral colloidal particles (M13 phage) into functional materials. A single-step process produces long-range-ordered, supramolecular films showing multiple levels of hierarchical organization and helical twist. Three distinct supramolecular structures are created by this approach: nematic orthogonal twists, cholesteric helical ribbons and smectic helicolidal nanofilaments. Both chiral liquid crystalline phase transitions and competing interfacial forces at the interface are found to be critical factors in determining the morphology of the templated structures during assembly. The resulting materials show distinctive optical and photonic properties, functioning as chiral reflector/filters and structural colour matrices. In addition, M13 phages with genetically incorporated bioactive peptide ligands direct both soft and hard tissue growth in a hierarchically organized manner. Our assembly approach provides insight into the complexities of hierarchical assembly in nature and could be expanded to other chiral molecules to engineer sophisticated functional helical-twisted structures.

Basic Information Processing Effects from Perceptual Learning in Complex, Real-World Domains

Basic Information Processing Effects from Perceptual Learning in Complex, Real-World Domains Khanh-Phuong Thai (kpthai@ucla.edu) Everett Mettler (mettler@ucla.edu) Philip J. Kellman (kellman@psych.ucla.edu) Department of Psychology, 405 Hilgard Avenue, Los Angeles, CA 90095 USA Abstract mathematics and science (e.g., Goldstone, Landy & Son, 2008; Kellman et al., 2008). In recent research, Kellman and colleagues have shown that PL can be systematically engineered and accelerated using appropriate computer-based technology (e.g., Kellman, Massey & Son, 2010). Their approach to PL methods takes the form of perceptual learning modules (PLMs). Rather than focusing on memorization of instances, PLMs employ unique instances and systematic variations in the learning set to promote the learning of invariant or diagnostic structures characterizing a category or concept. Learners engage in short, interactive episodes focused on discrimination or classification. Because specific instances seldom or never repeat in PLMs, learners pick up structural invariance and can generalize it to new instances (Kellman et al., 2010). Recent work suggests that relatively brief PLM interventions can produce dramatic learning gains in challenging mathematical domains, such as fraction learning and algebra problem solving (Kellman et al., 2008; Kellman et al., 2010). Recent research indicates that perceptual learning (PL) interventions in real-world domains (i.e., mathematics, science) can produce strong learning gains, transfer, and fluency. Although results on domain-relevant assessments suggest characteristic PL effects, seldom have real-world PL interventions been explicitly tested for their effects on basic information extraction. We trained participants to classify Chinese characters, based on either (1) overall configurations (structures), (2) featural relations (components), or (3) non- relational information (stroke-count control). Before and after training, we tested for changes in information extraction using a visual search task. Search displays contained all novel exemplars, involved manipulations of target-distractor similarity using structures and components, and included heterogeneous and homogeneous distractors. We found robust improvements in visual search for structure and component PL training relative to the control. High-level PL interventions produce changes in basic information extraction, and sensitivity induced by PL for both relational structure and specific components transfers to novel structural categories. Purpose of Current Work Keywords: perceptual learning; educational technology; visual search; categorization. In applying PL to complex, symbolic, real-world learning domains, a critical question arises - how do we tell that the driver in these effects is really PL? Kellman, Massey & Son (2010) set out characteristic design features of perceptual learning interventions and some signature effects that implicate PL. Yet, realistic learning domains are complex and involve synergies between conceptual knowledge and perception of structure. Here we sought evidence of PL effects in a high-level, realistic learning domain, by explicitly testing after PLM use for basic changes in information extraction. We trained PL for complex patterns in Chinese characters using a paradigm similar to that used to train PL in math and science learning (Kellman et al., 2010). Since Chinese characters are logographic and have both local and global structure, we were able to train participants to recognize characters at 3 different levels of hierarchical organization: stroke, component, and structure. Participants in two PL conditions matched characters by component (featural relations) or overall structure (global configuration). Importantly, in the case of matching by structure, local components were free to vary. Other studies have shown that an expert’s ability to use relevant ‘chunks’ based on components and configural structure has to be nourished by literacy development and cannot be obtained solely through Introduction Research on expertise has shown that experts effortlessly attend to relevant features and relations (Gibson, 1969), that experts extract larger “chunks” of information, discover higher-order invariance, and do so with low attentional load (Gibson, 1969; Schneider & Shiffrin, 1977). Such changes in information extraction as a result of experience constitute perceptual learning (Gibson, 1969; for a recent review, see Kellman & Garrigan, 2009). Much contemporary research on perceptual learning (PL) has focused on basic sensory discriminations; however, PL effects are not confined to low-level tasks (Garrigan & Kellman, 2008; Kellman & Garrigan, 2009). In fact, the natural function of PL is to improve the extraction of information from complex objects and events (Kellman & Garrigan, 2009). PL also likely involves discovery of abstract relational structures. Such high-level PL is a crucial component of expertise in many domains including reading (Baron, 1978; Yeh et al., 2003), chess (Chase & Simon, 1973), and X-ray interpretation (Chi, Feltovich & Glaser, 1981). In addition, recent research indicates an important role for PL in high-level symbolic domains, such as

Deformation and Fracture Mechanisms of Bone and Nacre

Bone and nacre are the most-known biological hard tissues to materials researchers. Although highly mineralized, both bone and nacre are amazingly tough and exhibit remarkable inelasticity, properties that are still beyond the reach of many modern ceramic materials. Very interestingly, the two hard tissues seem to have adopted totally different structural strategies for achieving mechanical robustness. Starting from a true nanocomposite of the mineralized collagen fibril and following up to seven levels of hierarchical organization, bone is built on a structure with extreme complexity. In contrast, nacre possesses a structure of surprising simplicity. Polygonal mineral tablets of micrometer size are carefully cemented together into a macroscopic wonder. A comparative analysis of the structure-property relations in bone and nacre helps us to unveil the underlying mechanisms of this puzzling phenomenon. In this review, we critically compare the various levels of structures and their mechanical contributions between bone and nacre, with a focus on inelasticity and the toughening process. We demonstrate that, although nacre and bone differ from each other in many aspects, they have adopted very similar deformation and toughening mechanisms.

Information as a Manifestation of Development

Information manifests a reduction in uncertainty or indeterminacy. As such it can emerge in two ways: by measurement, which involves the intentional choices of an observer; or more generally, by development, which involves systemically mutual (‘self-organizing’) processes that break symmetry. The developmental emergence of information is most obvious in ontogeny, but pertains as well to the evolution of ecosystems and abiotic dissipative structures. In this review, a seminal, well-characterized ontogenetic paradigm—the sea urchin embryo—is used to show how cybernetic causality engenders the developmental emergence of biological information at multiple hierarchical levels of organization. The relevance of information theory to developmental genomics is also discussed.

Raman and mechanical properties correlate at whole bone- and tissue-levels in a genetic mouse model

The fracture resistance of bone arises from the composition, orientation, and distribution of the primary constituents at each hierarchical level of organization. Therefore, to establish the relevance of Raman spectroscopy (RS) in identifying differences between strong or tough bone and weak or brittle bone, we investigated whether Raman-derived properties could explain the variance in biomechanical properties at both the whole bone and the tissue-level, and do so independently of traditional measurements of mineralization. We harvested femurs from wild-type mice and mice lacking matrix metalloproteinase 2 because the mutant mice have a known reduction in mineralization. Next, RS quantified compositional properties directly from the intact diaphysis followed by micro-computed tomography to quantify mineralization density (Ct.TMD). Correlations were then tested for significance between these properties and the biomechanical properties as determined by the three-point bending test on the same femurs. Harvested tibia were embedded in plastic, sectioned transversely, and polished in order to acquire average Raman properties per specimen that were then correlated with average nanoindentation properties per specimen. Dividing the ν 1 phosphate by the proline peak intensity provided the strongest correlation between the mineral-to-collagen ratio and the biomechanical properties (whole bone modulus, strength, and post-yield deflection plus nanoindentation modulus). Moreover, the linear combination of ν 1 phosphate/proline and Ct.TMD provided the best explanation of the variance in strength between the genotypes, and it alone was the best explanatory variable for brittleness. Causal relationships between Raman and fracture resistance need to be investigated, but Raman has the potential to assess fracture risk.

Multiscale structure-functional modeling of lamellar bone.

Bone is a natural example of achieving a unique combination and variability of stiffness and strength. One of the striking features of bone tissue is the ability to adapt to variable loading conditions by multiple but well organized structural arrangements of mineralized collagen fibrils at several levels of hierarchical organization. A profound understanding of the structure-function relations in bone requires both experimental assessment of heterogeneous elastic and structural parameters and theoretical modeling of the elastic deformation behavior. A bottom-up approach for experimental assessment and numerical modeling of the hierarchical structure from the nanoscale to the macroscale will be presented. Experimental data are obtained by scanning acoustic microscopy between 50 MHz and 1.2 GHz and provide anisotropic elastic and structural information at the lamellar (nanoscale) and at the tissue matrix (microscale) level. These data are directly translated into a finite element mesh. By numerical deformation analyses, the homogenized elastic stiffness tensor of the next hierarchical levels (microscale to macroscale) is derived. At each level the numerical results are cross-validated by experimental data. It will be shown that local variations in elastic anisotropy within the femoral shaft are related to an inhomogeneous strain distribution resulting from external stresses by weight and muscle forces.

Template-free synthesis of hierarchical spindle-like γ-Al2O3 materials and their adsorption affinity towards organic and inorganic pollutants in water

Hierarchical spindle-like γ-Al2O3 materials were prepared in the form of fray ended bundles of twisted nanoflakes by a non-template hydrothermal synthesis and sequential calcination route using aluminium nitrate or aluminium chloride as precursors and urea as precipitating agent. The microstructures, morphologies and textural properties of the resulting materials were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and N2 adsorption–desorption techniques. It was found that the spindle-like γ-Al2O3 particles are composed of at least three levels of hierarchical organization: polycrystalline γ-Al2O3 at the nanoscale, oriented nanoflakes and uniform spindle-like assemblies. The hierarchical γ-Al2O3 particles prepared from aluminium nitrate show a slightly smaller size, fewer self-organized nanoplatelets and better textural properties than γ-Al2O3 prepared from aluminium chloride, due to the larger aqueous ionic radius of NO3− than that of Cl−. The reported experiments allowed us to propose the mechanism of formation of the spindle-like assemblies, which involves self-transformation of metastable amorphous aluminium hydroxide particles and their sequential cooperative assembly. The as-prepared γ-Al2O3 was found to be effective adsorbent for the removal of selective pollutants from wastewater as a result of its unique hierarchical structure and high specific surface area, indicating a promising potential of this material for environmental remediation.