The Paleolithic diet excludes two major sources of fibre, grains and legumes. However, it is not known whether this results in changes to resistant starch (RS) consumption. Serum trimethylamine-N-oxide (TMAO) is produced mainly from colonic fermentation and hepatic conversion of animal protein and is implicated in CVD, but changes in RS intake may alter concentrations. We aimed to determine whether intake of RS and serum concentrations of TMAO varied in response to either the Paleolithic or the Australian Guide to Healthy Eating (AGHE) diets and whether this was related to changes in food group consumption. A total of thirty-nine women (mean age 47 (sd 13) years, BMI 27 (sd 4) kg/m2) were randomised to AGHE (n 17) or Paleolithic diets (n 22) for 4 weeks. Serum TMAO concentrations were measured using liquid chromatography–MS; food groups, fibre and RS intake were estimated from weighed food records. The change in TMAO concentrations between groups (Paleolithic 3·39 μmv. AGHE 1·19 μm, P = 0·654) did not reach significance despite greater red meat and egg consumption in the Paleolithic group (0·65 serves/d; 95 % CI 0·2, 1·1; P <0·01, and 0·22 serves/d; 95 % CI 0·1, 0·4, P <0·05, respectively). RS intake was significantly lower on the Paleolithic diet (P <0·01) and was not associated with TMAO concentrations. However, the limited data for RS and the small sample size may have influenced these findings. While there were no significant changes in TMAO concentrations, increased meat consumption and reduced RS intake warrant further research to examine the markers of gastrointestinal health of Paleolithic diet followers and to update Australian food databases to include additional fibre components.

In nature, biological structures often exhibit complex geometries that serve a wide range of specific mechanical functions. One such example are the ammonites, a large group of extinct mollusks, which produced elaborate, fractal-like hierarchical suture interface patterns. This report experimentally explores the influence of hierarchical suture interface designs on mechanical behavior by taking advantage of additive manufacturing and its ability to fabricate complex geometries. In addition, structure/property relationships of additively manufactured multi-material prototypes are investigated. It is shown that increasing the order of hierarchy amplifies stiffness by more than an order of magnitude. Tensile strength can also be tailored by changing the order of hierarchy, which alters the normal to shear stress ratio of the interfacial layer. The addition of failure mechanisms with increased order of hierarchy also significantly increases the toughness. Therefore, hierarchical suture interfaces can be used to diversify the mechanical behavior of additively manufactured materials.

Biological materials have developed hierarchical and heterogeneous material microstructures and nanostructures to provide protection against environmental threats that, in turn, provide bioinspired clues to improve human body armor. In this study, we present a multiscale experimental and computational approach to investigate the anisotropic design principles of a ganoid scale of an ancient fish, Polypterus senegalus, which possesses a unique quad-layered structure at the micrometer scale with nanostructured material constituting each layer. The anisotropy of the outermost prismatic ganoine layer was investigated using instrumented nanoindentations and finite element analysis (FEA) simulations. Nanomechanical modeling was carried out to reveal the elastic-plastic mechanical anisotropy of the ganoine composite due to its unique nanostructure. Simulation results for nanoindentation representing ganoine alternatively with isotropic, anisotropic, and discrete material properties are compared to understand the apparent direction-independence of the anisotropic ganoine during indentation. By incorporating the estimated anisotropic mechanical properties of ganoine, microindentation on a quad-layered FEA model that is analogous to penetration biting events (potential threat) was performed and compared with the quad-layered FEA model with isotropic ganoine. The elastic-plastic anisotropy of the outmost ganoine layer enhances the load-dependent penetration resistance of the multilayered armor compared with the isotropic ganoine layer by (i) retaining the effective indentation modulus and hardness properties, (ii) enhancing the transmission of stress and dissipation to the underlying dentin layer, (iii) lowering the ganoine/dentin interfacial stresses and hence reducing any propensity toward delamination, (iv) retaining the suppression of catastrophic radial surface cracking, and favoring localized circumferential cracking, and (v) providing discrete structural pathways (interprism) for circumferential cracks to propagate normal to the surface for easy arrest by the underlying dentin layer and hence containing damage locally. These results indicate the potential to use anisotropy of the individual layers as a means for design optimization of hierarchically structured material systems for dissipative armor.

In this work we present a micromechanical model for two-phase ductile/brittle laminates that captures the macroscopic behavior, as well as the underlying micro-mechanisms of deformation and failure, in particular the synergy between the inelastic deformation mechanisms of crazing and shear yielding. The finite element implementation of our model considers a three-dimensional representative volume element (RVE), and incorporates continuum-based physics-inspired descriptions of shear yielding and crazing, along with failure criteria for the ductile and brittle layers. The interface between the ductile and brittle layers is assumed to be perfectly bonded. The model successfully explains the volume fraction effect on the micro and macromechanics of ductile/brittle microlaminates subjected to uniaxial tension.

Many proteins have been experimentally observed to exhibit a force-extension behavior with a characteristic repeating pattern of a nonlinear rise in force with imposed displacement to a peak, followed by a significant force drop upon reaching the peak (a “saw-tooth” profile) due to successive unfolding of modules during extension. This behavior is speculated to play a governing role in biological and mechanical functions of natural materials and biological networks composed of assemblies of such protein molecules. In this paper, a constitutive model for the finite deformation stress-strain behavior of crosslinked networks of modular macromolecules is developed. The force-extension behavior of the individual modular macromolecule is represented using the Freely Jointed Chain (FJC) statistical mechanics model together with a two-state theory to capture unfolding. The single molecule behavior is then incorporated into a formal continuum mechanics framework to construct a constitutive model. Simulations illustrate a relatively smooth “yield”-like stress-strain behavior of these materials due to activate unfolding in these microstructures.

The mechanical behavior of the membrane of the red blood cell is governed by two primary microstructural features: the lipid bilayer and the underlying spectrin network. The lipid bilayer is analogous to a 2D fluid in that it resists changes to its planar area, yet poses little resistance to planar shear. A skeletal network of spectrin molecules is crosslinked to the lipid bilayer and provides the shear stiffness of the membrane. Here, a continuum level constitutive model of the large stretch behavior of the red blood cell membrane that directly incorporates the microstructure of the spectrin network is developed. The resemblance of the spectrin network to a triangulated network is used to identify a representative volume element (RVE) for the model. A strain energy density function in terms of an arbitrary planar deformation field is proposed using the RVE. Differentiation of the strain energy density function provides expressions for the general multiaxial stress-stretch behavior of the material. The stress-strain behavior of the membrane when subjected to uniaxial loading conditions in different directions is given, showing the capabilities of the proposed microstructurally-detailed constitutive modeling approach in capturing the evolving anisotropic nature of the mechanical behavior.

The mechanical behavior of the red blood cell membrane is governed by the lipid bilayer which resists changes in surface area and the underlying spectrin network which resists changes in shape. The spectrin network can be modeled as an idealized triangulated network. Each spectrin chain consists of folded domains along the length of the chain which can unfold during stretching of the chain. A domain will completely unfold under the application of a chain force of 20 to 35 pN depending on the rate of imposed chain stretch. During macroscopic stretch of a network, individual chains within the network will experience different levels of chain stretch since the network chains will collectively stretch and rotate to accommodate the imposed stretch. Hence, the stretch on any individual chain will depend on the magnitude and state of macroscopic strain. A microstructurally informed continuum level constitutive model is developed which tracks individual chain deformation behavior as a function of macroscopic strain and also determines the overall macroscopic network stress-strain behavior. Using the introduced continuum approach and statistical mechanics based models of individual chain force-extension behavior, the stress-stretch behavior of the membrane under uniaxial tension is simulated at large stretches and the behavior of the constituent chains is monitored. Domain unfolding occurs within constituent chains during network deformation and the effects of this domain unfolding on the overall macroscopic stress-strain behavior of the network subject to deformation at different strain rates is revealed.

Highly oriented, near single-crystal lamellar triblock copolymer films with alternating rubbery-glassy layer morphology possess an interesting anisotropy in their mechanical behavior, which can prove to be attractive for various applications. Here, the deformation micromechanics of highly oriented styrene-butadiene-styrene (SBS) lamellar triblock copolymers are investigated. The competing roles of the glassy (PS) and rubbery (PB) phases in the layered configuration are studied with micromechanical finite element based representative volume element (RVE) models subjected to tensile loading at different directions to the lamellar plane. The calculated material response is compared to x-ray and microscopy data from the literature, and proves to be successful in linking the macroscopic material response to the underlying physics of the microstructural evolution. Moreover, the RVE simulations are successful in reproducing the mechanical behavior of highly oriented nano-clay block copolymer nanocomposites. The response of layered-silicate models having 2wt% clay content is compared to the behavior of the respective neat block copolymer (BCP) and to existing experimental data. The ultimate objective is to facilitate these micromechanical models to design hierarchically ordered materials with properties, which will be optimally tailored for different classes of applications.

It is some time since a book has been published which focuses entirely on Sasanian Zoroastrianism, and one from Professor Shaul Shaked, who has studied the religion at this period for many years, is sure of eager attention. The Sasanian epoch naturally attracts scholars approaching Zoroastrian studies from the Persian or Semitic fields; and the author points moreover to its interest for students of religions more generally, since this was a time when a number of other faiths were jostling for place within Iran, from Judaism, Buddhism and Christianity to the ill-fated but then vigorously expanding Manichaeism, and lesser ones of diverse hues. All this, and ‘an openness to Greek scientific and philosophical ideas’, made for as ‘lively and diversified a period of intellectual and religious activity as could ever be found in ancient Iran’ (p. 12).

The Yazata of the benediction known as the Dahma Āfriti is a figure whose importance in the Zoroastrian pantheon has been obscured, it seems for two main reasons. One is that, although she was apparently originally accorded a place among the thirty ‘calendar’ divinities, she subsequently lost this, probably in an Achaemenian calendar reform. The other is that later still her identity became confused through her name acquiring several Middle Persian forms: Dahm Yazad, Dahmān Āfrīn, Dahmān, the last, since it is a formal plural, causing some misunderstandings in her veneration locally.

The Avestan adjective dahma is understood to have meant originally ‘instructed’, that is, in the Zoroastrian faith; but, to judge from its use in context, it developed the sense of ‘pious, devout’, occurring frequently with ašavan as a term for a good Zoroastrian. The name of the benediction is accordingly generally rendered as the ‘Pious Blessing’. Much power was attributed by Zoroastrians to solemnly pronounced words, and the compilers of the extended yasna liturgy set the ‘Pious Good Blessing’, Dahṃa VaohviĀfriti, after the Ahuna Vairya, Ašəm Vohū and Yenhē hātąm as the fourth of the mighty utterances which crush and destroy Anra Mainyu and his hordes (Y.61:l–2). (The other three form a group because together they precede the Gāthās, and together are the subject of the commentary which forms (Y. 19–21.)

This short article is dedicated to a friend and scholar who has greatly promoted the study of Pahlavi by his masterly work on texts and manuscripts, and, earning thereby the gratitude of all, by his truly admirable Pahlavi dictionary. Pahlavi is a language notorious for the challenges it makes to the lexicographer, not the least of which are to be found in the field of technical religious terms. Since priests, setting down instructions for their fellow-priests, could assume a common basic knowledge of the rituals concerned, they felt evidently no need for a precise or consistent use of terms, but relied on context to make their meaning plain. There was moreover a marked tendency, in written as in spoken usage, to abbreviate common phrases and to deal casually with grammatical forms, while among the Gujarati-speaking Parsis Persian technical terms were sometimes given additional or quite new meanings. A student of religion can hope, therefore, by considering perplexing linguistic usages in the light of observances to contribute a little to the lexicographer's pursuit, a small return for the large debt which all such students owe to the work of philologists

It is about three-quarters of a century since the maryannu (maryanni) of Mitanni and its dependencies, appearing in Hittite and Egyptian records of the second millennium B.C., were first discussed in connexion with the IndoIranians. In 1910 H. Winckler interpreted the word as a title belonging to Aryan infiltrators from the north, who had come to form an aristocracy among the Hurrians; and he recorded the suggestion by F. C. Andreas connecting it with Vedic márya ‘ young man, man, hero ’. Subsequently W. F. Albright presented a carefully documented case for considering the maryannu to be primarily ‘chariot-warriors’, arguing that from about 1700 to 1200 B.C. ‘chariots played the same role in warfare that cavalry did later, and the chariot-warriors occupied the same social position that was held by the⃛ feudal knights of the Middle Ages’. He further pointed out, with regard to Vedic márya, that a semantic development from ‘young man’ to ‘warrior’ is widely attested. Thereafter R. T. O'Callaghan adduced yet more evidence from Egyptian and cuneiform sources to confirm that ‘from the mid-fifteenth century to the midtwelfth century B.C., and from the Mitanni kingdom down through Palestine beyond Ascalon, the term maryannu is to be understood primarily as a noble who is a chariot-warrior’. The area was one where Indo-Aryan names occur at about the same period; and in the fourteenth-century Kikkuli treatise from Boghaz-köy, on the training of chariot-horses, Indo-Aryan technical terms appear. There were solid grounds therefore for thinking that Indo-Aryans, bringing with them horses from the Asian steppes, had played a leading part in developing chariotry in the Near East at that time, and that it was this which enabled a group of them to become locally dominant there.