Constitutive memory equations for auxetic materials

This paper proposes the new methodology for geometrical properties identification of step‐wise deformed closed‐cell aluminum alloy foam. The change of internal structure of cylindrical foam specimens during deformation is ex situ recorded by a micro computed tomography scanner. The geometry of five specimens is analyzed in un‐deformed and several deformed states until 70% of engineering strain. The obtained CT images is used to construct the 3D computer models of un‐deformed/deformed foam specimens. These are then subjected to an automated analysis of the geometrical properties of internal structure to determine the size, distribution, and orientation of the pores. The results provide the basis for further analysis of the variation in internal structure during the deformation process. The internal structure of un‐deformed specimens exhibits a pore orientation dependent on the fabrication process. Significant changes of internal pore structure is observed during the deformation process, where the specimens with small spatial variation of porosity sustains larger strains until failure under compressive load. The specimens with larger spatial variation of porosity and larger pore concentrations disintegrate earlier.

An attempt is made to reconcile disparate findings as to the effect on item difficulty of variations in the internal structure of items. The critical factor seems to be whether a given alteration in internal structure entails the utilisation of quantitatively or qualitatively-different solution processes. Instances are cited where variations in internal structure lead to qualitatively different processes being used. In no such instance did there fail to be a concomitant change in item difficulty.

In 1825 J. de C. Sowerby described and figured as Spirifer lineatus a brachiopod from the “ Wenlock Limestone ” of Dudley, choosing three syntypes; later he changed the specific name to radiatus. Of subsequent descriptions those of Hall (1852), Davidson (1866), Beecher and Clarke (1889), and Hall and Clarke (1894) are the most important. The present study is based on topotype material, while additional specimens for comparison have been collected by the writer from the Wenlock Shale of Malvern (Colwall Tunnel Tip Heap), from the Woolhope Limestone of Suckley, from the Wenlock Limestone of May Hill, and from the Tickwood beds and Wenlock Limestone on Wenlock Edge (railway cuttings near Presthope and Lilleshall Quarry). These, together with specimens from the Sedgwick Museum Collection, from the Birmingham University Collection, and from the British Museum (Natural History), have provided material adequately representative of variations in shape and size. Study has been made of external features, but more particularly of internal characters. The method of investigating the internal structures consists in grinding down the specimen either from the umbones, or from the lateral margin, and taking serial cellulose transfers at regular intervals, from which enlarged scale models may be constructed. Five specimens have been so treated, and as well as the construction of models, use has been made of perspective scale drawings to show the variations in internal structure. Growth lines are preserved on the transfers, but have in addition been examined in thin sections; specimens from Haverfordwest and Rubery preserved as casts have served to throw light on the muscle system, while finally the ventral valves of specimens preserved in shale, have been prepared to show the variations in internal structure.

The stomach in the bivalvia

Unit bars are relatively large bedforms that develop in rivers over a wide range of climatic regimes. Unit bars formed within the highly‐variable discharge Burdekin River in Queensland, Australia, were examined over three field campaigns between 2015 and 2017. These bars had complex internal structures, dominated by co‐sets of cross‐stratified and planar‐stratified sets. The cross‐stratified sets tended to down‐climb. The development of complex internal structures was primarily a result of three processes: (i) superimposed bedforms reworking the unit bar avalanche face; (ii) variable discharge triggering reactivation surfaces; and (iii) changes in bar growth direction induced by stage change. Internal structures varied along the length and across the width of unit bars. For the former, down‐climbing cross‐stratified sets tended to pass into single planar cross‐stratified deposits at the downstream end of emergent bars; such variation related to changes in fluvial conditions whilst bars were active. A hierarchy of six categories of fluvial unsteadiness is proposed, with these discussed in relation to their effects on unit bar (and dune) internal structure. Across‐deposit variation was caused by changes in superimposed bedform and bar character along bar crests; such changes related to the three‐dimensionality of the channel and bar geometry when bars were active. Variation in internal structure is likely to be more pronounced in unit bar deposits than in smaller bedform (for example, dune) deposits formed in the same river. This is because smaller bedforms are more easily washed out or modified by changing discharge conditions and their smaller dimensions restrict the variation in flow conditions that occur over their width. In regimes where unit bar deposits are well‐preserved, their architectural variability is a potential aid to their identification. This complex architecture also allows greater resolution in interpreting the conditions before and during bar initiation and development.

Simulating the future evolution of the internal land use structure of rural settlements (RSILUS) is vital for rural land management. However, previous simulation studies have mostly regarded rural settlements as a whole, thereby ignoring their internal structural variations. In this paper, as an example, we select Pinggu District, which has experienced the impact of rapid urbanization and has an unstable rural land use structure (LUS); then, we examine the driving factors of the changes in the RSILUS, construct a cellular automata (CA)–Markov simulation model specifying the RSILUS, and simulate its changes in 2025. The results indicate the following. (1) The influencing factors of various land use changes in rural settlements in Pinggu District differ significantly. Basic land, such as living functional land, is greatly influenced by natural resources, whereas production functional land is subject to socioeconomic factors. (2) The simulation results demonstrate that from 2015 to 2025, the production and living functional land areas of rural settlements will decrease as a whole. Accordingly, the distribution of rural public service land (RPSL) will tend to remain stable, and the trends of land use abandonment and functional degradation will continue as rural areas continue to recede. Our study enriches the research on rural land use systems by refining the simulation of rural settlements to focus on their internal structure. The differentiation and complexity of the changes in rural LUS types further suggests that rural planning and renewal should adapt to the changing conditions of the RSILUS, and the LUS should be adjusted to improve the constructed environment in human settlements and equalize urban and rural areas.

The basic principles behind a theory of scaling in cartography are outlined and illustrated with a large number of examples. The following levels of scaling are used in the transformation of “(objective) empirical systems of relationships” to “abstract systems of relationships” for the purpose of their graphic representation: nominal, ordinal, interval, proportional or ratio, and absolute. While the first four levels (nominal, ordinal, interval, and ratio) are similar to those widely identified in the West, the absolute level represents what would be considered a special type of ratio scaling in Western practice. The paper includes criticism of certain graphic methods supposedly used by Western cartographers on maps employing the different levels of scaling (use of symbols differentiated by variations in internal structure, failure to correctly differentiate between interval, ratio, and absolute scaling, etc.). Measurement for mapping purposes should be based on careful analysis of the structure of relati...

The recent clinical and commercial success of lipid nanoparticles (LNPs) for nucleic acid delivery has incentivized the development of new technologies to manufacture LNPs. As new technologies emerge, researchers must determine which technologies to assess and how to perform comparative evaluations. In this article, we use a quality-by-design approach to systematically investigate how the mixer technology used to form LNPs influences LNPstructure. Specifically, a coaxial turbulent jet mixer and a staggered herringbone microfluidic mixer were systematically compared via matched formulation and process conditions. A full-factorial design-of-experiments study with three factors and three levels was executed for each mixer to compare process robustness in the production of antisense oligonucleotide (ASO) LNPs. ASO-LNPs generated with the coaxial turbulent jet mixer were consistently smaller, had a narrower particle size distribution, and had a higher ASO encapsulation as compared to the microfluidic mixer, but had a greater variation in internal structure with less ordered cores. A subset of the study was replicated for mRNA-LNPs with comparable trends in particle size and encapsulation, but more frequent bleb features for LNPs produced by the coaxial turbulent jet mixer. The study design used here provides a road map for how researchers may compare different mixer technologies (or process changes more broadly) and how such studies can inform process robustness and manufacturing control strategies.

Auxetics are materials that contract laterally when compressed, rather than expand, in contrast to common experience. Here we show that common metals and plastics can be rendered auxetic through the introduction of a regular array of holes. Under compression, these hard holey materials bypass localized failure modes, such as shear banding, and instead deform via a global pattern transformation previously reported in elastomeric structures. Despite significant variations in internal structure, the pattern transformation responsible for auxetic behaviour in both metals and plastics is governed by the buckling of the slender struts that comprise the microarchitecture. Furthermore, in contrast to elastomeric structures, holey sheets made from hard materials exhibit significant negative post-buckling stiffness. This suggests that, beyond the geometrical nonlinearities associated with topological modifications, material nonlinearities which arise during plastic deformation offer further potential for altering the material properties of the constituent.

Coaxial electrospinning allows easy and cost-effective realization of composite fibers at the nano- and microscales. Different multifunctional materials can be incorporated with distinct localization to specific regimes of the fiber cross section and extended internal interfaces. However, the final composite properties are affected by variations in internal structure, morphology, and material separation, and thus, nanoscale control is mandatory for high-performance application in devices. Here, we present an analysis with unprecedented detail of the cross section of liquid core-functionalized fibers, yielding information that is difficult to reveal. This is based on focused ion beam (FIB) lift-out and allowing HR-TEM imaging of the fibers together with nanoscale resolution chemical analysis using energy dispersive X-ray spectroscopy (EDS). Unexpectedly, core material escapes during spinning and ends up coating the fiber exterior and target substrate. For high core injection rate, a dramatic difference in fiber morphology is found, depending on whether the surface on which the fibers are deposited is hydrophobic or hydrophilic. The latter enhances postspinning extraction of core fluid, resulting in the loss of the functional material and collapsed fiber morphology. Finally, in situ produced TiO2 nanoparticles dispersed in the polymer appear strikingly different when the core fluid is present compared to when the polymer solution is spun on its own.

In soilless culture, control of nutrient solution is very important for production of the high quality tomato fruits. The control will be efficient by taking the information of internal properties of growing fruits into account. Therefore, nondestructive measurement method for these properties is highly required. Nondestructive near infrared (NIR) methods have already been used effectively in many crops such as mango, apple, peach, however, no studies have been reported on growing tomato fruit. In addition, tomato fruit has a great variation in internal structure that consists of flesh and pulp. It causes ununiformity in texture and chemical compositions within a fruit and hence significantly affects NIR spectra. Therefore, specially assembled NIR instrument is required for accurate nondestructive determination of constituents in the fruit. Three halogen lamps as a light source of the instrument illuminated almost the whole fruit surface from the upper side. Then the spectrum of transmitted light through the bottom of the sample was measured by spectrometer. The performance of this instrument was investigated by developing calibration model for determination of the soluble solids content (SSC) in the whole fruit from the spectrum. This method successfully determined the SSC of tomato fruits with correlation coefficient between predicted and actual values (r) of 0.91, standard error of performance (SEP) of 0.73%, and bias of 0.17%.

Tendons and ligaments play key roles in the musculoskeletal system in both man and animals. Both tissues can undergo traumatic injury, age‐related degeneration and chronic disease, causing discomfort, pain and increased susceptibility to wider degenerative joint disease. To date, tendon and ligament ultrastructural biology is relatively under‐studied in healthy, non‐diseased tissues. This information is essential to understand the pathology of these tissues with regard to function‐related injury and to assist with the future development of tissue‐engineered tendon and ligament structures. This study investigated the morphological, compositional and extracellular matrix protein distribution differences between tendons and ligaments around the non‐diseased canine stifle joint. The morphological, structural characteristics of different regions of the periarticular tendons and ligaments (the intra‐articular anterior cruciate ligament, the extra‐articular medial collateral ligament, the positional long digital extensor tendon and energy‐storing superficial digital flexor tendons) were identified using a novel semi‐objective histological scoring analysis and by determining their biochemical composition. Protein distribution of extracellular matrix collagens, proteoglycans and elastic fibre proteins in anterior cruciate ligament and long digital extensor tendon were also determined using immunostaining techniques. The anterior cruciate ligament was found to have significant morphological differences in comparison with the other three tissues, including less compact collagen architecture, differences in cell nuclei phenotype and increased glycosaminoglycan and elastin content. Intra‐ and interobserver differences of histology scoring resulted in an average score 0.7, indicative of good agreement between observers. Statistically significant differences were also found in the extracellular matrix composition in terms of glycosaminoglycan and elastin content, being more prominent in the anterior cruciate ligament than in the other three tissues. A different distribution of several extracellular matrix proteins was also found between long digital extensor tendon and anterior cruciate ligament, with a significantly increased immunostaining of aggrecan and versican in the anterior cruciate ligament. These findings directly relate to the different functions of tendon and ligament and indicate that the intra‐articular anterior cruciate ligament is subjected to more compressive forces, reflecting an adaptive response to normal or increased loads and resulting in different extracellular matrix composition and arrangement to protect the tissue from damage.

Corn grits blended with defatted soy flour (30‐50%) and apple pomace (0‐20%) were extrusion cooked. The effect of apple pomace levels and processing conditions (extrusion temperature, screw speed and moisture content) on the extrudates' textural properties, cellular structure and molecular conformation were studied. Results show that increase in the apple pomace level (0 to 20%) and extrusion temperature (100 to 140°C) decreased the hardness of the extrudates. The hardness ranged between 7.57 and 15.23 N. Lower hardness was associated with higher crispness and brittleness. SEM examination revealed that higher temperature and shear were responsible for the damage of the cellular structure of the extrudates. Presence of air cells indicated crisper extrudates. FTIR showed that there were significant changes in the components in the formulation due to extrusion. This study showed the variation in internal structure and molecular bonds and their effect on the texture of the extrudates containing apple pomace.Practical applicationsTextural and structural properties of extrudates containing novel blend of apple pomace, defatted soy flour and corn grits were examined. The information generated from this research will help in formulating extruded products with high levels of protein and fiber.

Rock glaciers are cryo‐conditioned downslope‐creeping landforms in high mountains. Their dynamics are changing due to external factors influenced by climate change. Although there has been a growing scientific interest in mountain permafrost and thus in rock glaciers in recent years, their historical development, especially before the first alpine‐wide aerial image flights in the 1950s, has hardly been researched. Therefore, we utilize a historical stereophotogrammetric map from 1922 and historical flow velocity profiles (1938–1953) and relate them to data derived from historical aerial photographs and airborne laser scanning data in several time slices between 1953 and 2021. By doing so, the development of flow velocity, surface elevation changes, and frontal advance of the two lobes of the composite rock glacier Inner Ölgrube, Kaunertal, Austria, is analyzed and compared over almost a century. Results indicate an increased frontal advance in the laterally confined area of one lobe and a severe subsidence in the upper area of both lobes between 1922 and 1953. Whereas the former could be explained by a combination of the short warm phase in the 1940s and 1950s and the (subsurface) topography, the latter might be attributed to the strong melting of superimposed debris‐covered dead ice bodies, a relict of the Little Ice Age (LIA) glaciation. Both factors might also contribute to the increased flow velocities between 1938 and 1953, which are still recognizable in the 1953–1970 time step. Although both lobes follow a general similar trend, which is in line with the alpine‐wide trend of flow velocity acceleration in the 1990s, differences in the geomorphic development of the two lobes were identified. In addition to a slightly varying evolution of the flow velocities, the timing and magnitude of the volume changes are different. Furthermore, both lobes display a dissimilar mechanism of frontal advance over the entire study period. Because the external forcing is identical, the varying development might be attributed to variations in internal structure, bedrock topography, or upslope connection of the lobes. Due to the lateral constriction, the subsurface topography, and the LIA maximum extent of the glacier, it is assumed that the geomorphic development of the Innere Ölgruben rock glacier, particularly before 1953, represents a special case, and the results are not simply transferable to other rock glaciers.

Pinealocytes of female pigs were studied electron-microscopically and compared with those of other mammals. A prominent Golgi apparatus forming dense-cored vesicles was widely dispersed in the cytoplasm of the cell body. A very characteristic feature of the pig pinealocytes was the presence of membrane-bounded bodies showing wide variations in internal structure. Possible roles of the dense-cored vesicles and membrane-bounded bodies in secretory processes of pinealocytes are discussed.