Microscale Changes Research Articles

MRI-based quantification of cardiac-driven brain biomechanics for early detection of neurological disorders.

We present a pipeline to quantify biomechanical environment of the brain using solely MRI-derived data in order to elucidate the role of biomechanical factors in neurodegenerative disorders. Neurological disorders, like Alzheimer's and Parkinson's diseases, are associated with physical changes, including the accumulation of amyloid-β and tau proteins, damage to the cerebral vasculature, hypertension, atrophy of the cortical gray matter, and lesions of the periventricular white matter. Alterations in the external mechanical environment of cells can trigger pathological processes, and it is known that AD causes reduced stiffness in the brain tissue during degeneration. However, there appears to be a significant lag time between microscale changes and macroscale obstruction of neurological function in the brain. Here, we present a pipeline to quantify the whole brain biomechanical environment to bridge the gap in understanding how underlying brain changes affect macroscale brain biomechanics. This pipeline enables image-based quantification of subject-specific displacement field of the whole brain to subject-specific strain, strain rate, and stress across 133 labeled functional brain regions. We have focused our development efforts on utilizing solely MRI-derived data to facilitate clinical applicability of our approach and have emphasized automation in all aspects of our methods to reduce operator dependance. Our pipeline has the potential to improve early detection of neurological disorders and facilitate the identification of disease before widespread, irreversible damage has occurred.

Limitations of poromechanical first-order computational homogenization for the representation of micro-scale volume changes

Limitations of poromechanical first-order computational homogenization for the representation of micro-scale volume changes

High-resolution three-dimensional micro-computed tomography assessment of micro-architectural patterns in non-adults with cribra orbitalia: Correlation between macro- and micro-scale bone features.

Skeletal porous lesions such as cribra orbitalia (CO) have long been of interest to bioanthropologists worldwide, mainly due to their high prevalence in osteological material. Previous studies considered CO as an external morphological manifestation, and therefore, research has mainly focused on visible (macroscopic) CO patterns. However, the understanding of CO-induced micro-scale bone changes is still scarce. Therefore, we performed high-resolution micro-computed tomography imaging to investigate three-dimensional CO-induced micro-architectural patterns in non-adults, with a particular focus on the correlation between macroscopic and micro-architectural orbital features. Cortical and trabecular micro-architectural changes in the orbital roof were analyzed in non-adults younger than 15 years, using orbital roof samples with and without macroscopic traces of CO (n = 28). A widely accepted five-grade macroscopic CO scoring system was applied to analyze CO severity. Areas affected with CO (area 1) and areas without macroscopic CO traces (area 2) were analyzed separately. The conducted high-resolution analysis showed that cortical and trabecular micro-architecture varied with CO presence, lesion severity (CO grade), and the analyzed area. Inter-grade comparisons suggested that most of the analyzed micro-architectural parameters were not significantly different between adjacent CO grades. Based on the micro-architectural evaluation of areas 1 and 2, the porous lesions were much more extensive than revealed by gross examination. In addition, micro-architectural differences were particularly pronounced in younger non-adults. In summary, our pilot study suggests that the macroscopic examination of CO reflects only the tip of the iceberg, as the micro-architectural changes seem to be much larger than macroscopically identified. RESEARCH HIGHLIGHTS: Cribra orbitalia (CO) represents orbital porous lesions. A high-resolution microscopic assessment of CO-induced changes in non-adults was done by micro-computed tomography. The microarchitecture was affected by CO presence, CO grade, area, and age.

Thermomechanical and Morphological Properties of Loligo vulgaris Squid Sucker Ring Teeth.

Climate change is accelerating the increase of temperatures across the planet and resulting in the warming of oceans. Ocean warming threatens the survival of many aquatic species, including squids, and has introduced physiological, behavioral, and developmental changes, as well as physical changes in their biological materials composition, structure, and properties. Here, we characterize and analyze how the structure, morphology, and mechanical properties of European common squid Loligo vulgaris sucker ring teeth (SRT) are affected by temperature. SRT are predatory teethed structures located inside the suction cups of squids that are used to capture prey and are composed of semicrystalline structural proteins with a high modulus (GPa-range). We observed here that this biological material reversibly softens with temperature, undergoing a glass transition at ∼35°C, to a MPa-range modulus. We analyzed the SRT protein nanostructures as a function of temperature, as well as microscale and macroscale morphological changes, to understand their impact in the material properties. The results suggested that even small deviations from their habitat temperatures can result in significant softening of the material (up to 40% in modulus loss). Temperature changes following recent global climate trends and predictions might affect environmental adaptation in squid species and pose emerging survival challenges to adapt to increasing ocean temperatures.

Experimental investigation of microscale mechanical alterations in shale induced by fracturing fluid contact

Understanding the changes in the mechanical properties of shale exposed to fracturing fluids is crucial for optimizing parameters in hydraulic fracturing. However, the dynamic alterations in mechanical properties still need to be disclosed due to the high heterogeneity of shale, particularly at the microscale. This paper aims to in-situ unravel the microscale changes in the dynamic mechanical properties of shale affected by fracturing fluids. A combination of nanoindentation, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrum (EDS) techniques was employed. The nanoindentation results demonstrate a rapid initial decrease followed by a slower decline after 4 days in both Young's modulus and the hardness of shale exposed to fracturing fluids. Specifically, the average Young's modulus of shale ranges from 62.45 GPa to 56.275 GPa, 52.575 GPa, 40.15 GPa, and 39.5 GPa while the average hardness modulus varies from 3.305 GPa to 2.2125 GPa, 1.8175 GPa, 1.24 GPa and 1.1525 GPa with the treatment time of 0, 1, 2, 4, and 7 days, respectively. An exponential expression well describes the relationship between mechanical properties with the treatment time. XRD analysis shows carbonate and clay mineral content decrease, while quartz content increases. Moreover, in-situ SEM results highlight the emergence of many dissolution pores when shale is exposed to fracturing fluid. Further pH testing and EDS analysis indicates a corrosion effect, with hydrogen ions reacting with carbonate minerals in shale, leading to a significant reduction in calcite and dolomite. Consequently, the corrosion-induced dissolution pores weaken the stability of the shale matrix, leading to a reduction in mechanical properties. This study sheds light on the mechanism behind the dynamic mechanical properties of rock and provides valuable insights for optimizing the soaking time for fracturing fluids.

The Effects of Freezing on the Nutritional Composition of Fish

The degradation of fish in the storage condition of the freezer is influenced by several factors which include the fishing species, the rate at which the fish is frozen, the temperature at which it is stored, the duration of storage, the type of freezing applied, and enzymatic processes. The freezing and frozen storage lead to macro- and microscale changes of fish muscles, with major changes being lipid oxidation inducing rancidity, protein denaturation and aggregation causing toughness, red color fading and freezer burn. The process of freezing involves transforming water to ice which in turn results into an increase in the concentration of dissolved substances, adjusting the acid-base balance. It can lead to pH changes of up to 1 unit, often towards acidity and in some cases up to 10 units due to salt and other compounds precipitation. The described changes permanently alter the properties of the physical-chemical nature of frozen fish including the convenience and storage conditions of the food, thereby directing attention to the necessity of new approaches in technologies. Keywords: Frozen storage, fish degradation, nutritional composition, enzymatic processes, freezing effects.

Elucidating fungal decomposition of organic matter at sub-micrometer spatial scales using optical photothermal infrared (O-PTIR) microspectroscopy.

In microbiological studies, a common goal is to link environmental factors to microbial activities. Both environmental factors and microbial activities are typically derived from bulk samples. It is becoming increasingly clear that such bulk environmental parameters poorly represent the microscale environments microorganisms experience. Using infrared (IR) microspectroscopy, the spatial distribution of chemical compound classes can be visualized, making it a useful tool for studying the interactions between microbial cells and their microenvironments. The spatial resolution of conventional IR microspectroscopy has been limited by the diffraction limit of IR light. The recent development of optical photothermal infrared (O-PTIR) microspectroscopy has pushed the spatial resolution of IR microspectroscopy beyond this diffraction limit, allowing the distribution of chemical compound classes to be visualized at sub-micrometer spatial scales. To examine the potential and limitations of O-PTIR microspectroscopy to probe the interactions between fungal cells and their immediate environments, we imaged the decomposition of cellulose films by cells of the ectomycorrhizal fungus Paxillus involutus and compared O-PTIR results using conventional IR microspectroscopy. Whereas the data collected with conventional IR microspectroscopy indicated that P. involutus has only a very limited ability to decompose cellulose films, O-PTIR data suggested that the ability of P. involutus to decompose cellulose was substantial. Moreover, the O-PTIR method enabled the identification of a zone located outside the fungal hyphae where the cellulose was decomposed by oxidation. We conclude that O-PTIR can provide valuable new insights into the abilities and mechanisms by which microorganisms interact with their surrounding environments.IMPORTANCEInfrared (IR) microspectroscopy allows the spatial distribution of chemical compound classes to be visualized. The use of conventional IR microspectroscopy in microbiological studies has been restricted by limited spatial resolution. Recent developments in laser technology have enabled a new class of IR microspectroscopy instruments to be developed, pushing the spatial resolution beyond the diffraction limit of IR light to approximately 500 nm. This improved spatial resolution now allows microscopic observations of changes in chemical compounds to be made, making IR microspectroscopy a useful tool to investigate microscale changes in chemistry that are caused by microbial activity. We show these new possibilities using optical photothermal infrared microspectroscopy to visualize the changes in cellulose substrates caused by oxidation by the ectomycorrhizal fungus Paxillus involutus at the interface between individual fungal hyphae and cellulose substrates.

Double-edged effect of frequent freeze-thaw on the stability of zero-valent iron after heavy metal remediation

Freeze-thaw cycles (FTCs) cause dynamic microscale changes in ions and solvents. During freezing, heavy metals adsorbed on zero-valent iron (M-ZVI) and protons are excluded by ice crystals and concentrated in the liquid-like grain boundary region. The high proton concentration in this region leads to the dissolution of the passivation layer of ZVI. To assess the environmental risks of M-ZVI during FTCs, this study evaluated the stability of M-ZVI in this scenario from both microscale and macroscale perspectives. The results showed that the dissolution of the passivation layer had a dual effect on the stability of M-ZVI, which depends on the by-products of M-ZVI. The dissolution of the passivation layer was accompanied by the leaching of heavy metals, such as Ni-ZVI, but it also enhanced the reactivity of ZVI, causing it to re-react with desorbed heavy metals. The stability of Cr-ZVI and Cd-ZVI was improved due to frequent FTCs. Furthermore, changes in the surrounding environment (water dipole moment, ion concentration, etc.) of ZVI affected the crystallization of Fe oxides, increasing the content of amorphous Fe oxide. As low-crystallinity Fe oxides could facilitate ion doping, Ni2+ was doped into Fe3O4 lattice during FTCs, which reduced the mobility of heavy metals. Contrary to traditional views that freezing temperatures slow chemical reactions, this study provides new insights into the application of iron-based materials in cold environments.

Progressive microstructural evolution characteristics and weakening mechanism of coal exposed to acid mine drainage (AMD)

This study aims to analyze the extent of softening structural deterioration of coal pillars over time when exposed to acid mine drainage (AMD) from abandoned pits. The research involves using microscopic recognition techniques on coal samples and hydrochemistry tests in solution to identify changes in mineral compositions and microstructure parameters quantitatively. The study examines the micro-scale changes in microstructural hydro-chemical damage processes in coal samples. Based on the findings, the decrease in pH of the acidic pit effluent leads to degradation in the physical microstructural characteristics of the coal. Specifically, there is a 6.90% increase in the fractal dimension and a 23.33% rise in the area porosity. Similarly, the chemical parameters of the coal also undergo significant changes. The thickness of the aromatic layer in the coal decreases significantly, while the average diameter of the aromatic layer increases by 16.9%. The aromaticity of the coal increases, indicating noticeable deterioration of the matrix layer, particularly fragmentation. Moreover, the solution characteristics reflect the progressive coal deterioration, including increased metal ions in the soaking solution, the transformation of divalent iron to trivalent iron, and a continuous rise in sulfate content. These results have implications for assessing and maintaining load-bearing structures in underground abandoned pits subjected to long-term immersion.

Promotion effect of foam formation on the degradation of polyvinyl alcohol by ozone microbubble

Polyvinyl alcohol (PVA), extensively utilized in diverse industries, presents a challenge in terms of degradation. The combination of ozone (O3) with microbubbles enhances ozone's residence time and oxidation efficiency, offering a promising avenue for effective PVA degradation. This study investigated PVA degradation using ozone microbubble (MB/O3) and oxygen microbubble (MB/O2). Bubbles evolving into remarkably resistant foam was observed for the first time. PVA removal via MB/O3 and MB/O2 followed a first-order kinetic model, exhibiting removal rates of 98.58 % and 48.68 %, respectively, within the initial 20 min. The physicochemical reaction of PVA degradation by MB/O3 and the physical removal reaction by MB/O2 were demonstrated. The microscale changes of bubbles and foam were captured, uncovering the phenomenon of self-pressurized dissolution of MB/O3 and the creation of larger foam structures through intact microbubbles, ultimately leading to their rupture. A comprehensive four-stage theory was proposed to explain PVA degradation by MB/O3, where physical separation, foam film degradation, and bubble coalescence within the foam play crucial roles. This theory was validated under varying pH and salt concentration conditions. Moreover, when the pH was decreased from 8.69 to 3.3, there was a 33.2 % increase in the COD removal rate. Mechanism analysis further confirmed the theory and revealed that, during PVA degradation, MB/O3 underwent stochastic cleavage, yielding small molecule remnants comprising aldehyde, carboxyl, and ester moieties. Finally, by comparison with other PVA degradation processes, the trial of MB/O3 was proven to be a straightforward and effective treatment approach for PVA degradation.

Nanoscale evolution of rubber-oil modified asphalt binder after thermal and UV aging

Thermal oxidation and ultraviolet exposure cause complex micro-scale chemical changes in asphalt binders, leading to severe deterioration of pavements. The aging-induced evolution of nanoscale domains in asphalt binders was investigated using multiple nanoscale characterizations. This in turn provides insights to develop means of alleviating the aging of asphalt binders to extend pavement service life. The chemical composition, surface topography, and mechanical properties of four asphalt binders (base asphalt and modified asphalt with bio-oils and crumb rubber) are investigated by atomic force microscopy during thermal aging and UV aging and a combination thereof. It was shown that the three domains in the asphalt binder react differently to aging. Abundant carbonyl and sulfoxide compositions are observed in the aged base asphalt binder, which is mainly generated and concentrated in the para domains. The addition of rubber and bio-modified rubber reduces the formation of aging-related compositions in para domains, thereby enhancing the aging resistance of asphalt binder. Aging also significantly changes the surface roughness and domain structures of asphalt binders. Furthermore, it was shown that the domain stability during thermal aging and UV aging can be enhanced by crumb rubber and bio-oils, respectively. Nano-mechanical characterization shows the surface of asphalt binders becomes stiffer, and its adhesion is reduced after aging. Significant reduction (up to 26%) in latter aging indicators was observed with the bio-modifier used in rubberized asphalt. This paper provides insights pertaining to the aging-induced evolution of asphalt binders while examining the efficacy of bio-modification of rubberized asphalt to delay aging. It is recommended to include hybrid aging in future studies and to test bio-modified rubberized asphalt at a larger scale.

Quantitative Optical Coherence Elastography: A Novel Intensity-Based Inversion Method Versus Strain-Based Reconstructions

Many diseases like cancer or atherosclerosis bear micro-scale tissue stiffness changes, which can be visualised by optical coherence elastography (OCE). OCE is a promising research field, where a growing number of publications present qualitative displacement maps. Quantitative OCE results have also been presented, but still lack high precision and good reproducibility, which are important for clinical applications. In this work, we compare three reconstruction methods for the Young's modulus in intensity-based quasi-static compressional OCE: uniaxial analysis, strain map based reconstruction facilitating a particle tracking improved optical flow (EOFM), and a novel image-based inverse reconstruction method (IIM). The quality of the proposed reconstruction methods is investigated by comparing their performance on twelve silicone elastomer phantoms with inclusions of varying size and stiffness. While the uniaxial reconstruction is strongly affected by lateral motion, EOFM is capable of deriving precise strain maps from consecutive OCT images during compression. However, for a valid Young's modulus reconstruction additional stress map information is required. IIM performs best, precisely reconstructing Young's modulus of inclusion and background, closely corresponding to separately determined ground truth values. The method offers a significant improvement of the relative error by a factor of 3.5 compared to uniaxial and strain-based analysis.

Micro-meso-macroscale correlation mechanism of red-bed soft rocks failure within static water based on energy analysis

The purpose of the present study is to fundamentally investigate the micro-meso-macroscale correlation mechanism of red-bed soft rocks failure within static water, based on energy analysis. Through a series of experimental studies, changes in the micro-meso-macroscale characteristics of the rocks were characterised by measuring ion concentrations in and pH of water, the pore structure and crack propagation. Based on the experimental measurements, theoretical modelling of micro-meso-macroscale energy conservation was carried out to determine the micro-meso-macroscale correlation mechanism of red-bed soft rocks failure. The results show that the microscale dominant effect of red-bed soft rocks is determined as chemical effects. The failure mechanism of red-bed soft rocks under static water saturation involves chemical, physical and mechanical dominant effects at the micro-meso-macroscale. It was demonstrated that the dominant chemical effect of clay minerals and water comprises a series of chemical energy changes in the microscale water–rock interface. This can induce the energy changes in both mesophysical and macromechanical levels. During the first month after the water saturation, there was a significant decrease in Na+ and K+ concentrations in aqueous solution, whereas there was little change in Ca+ and Mg2+ concentrations. The scanning electron microscope (SEM) images indicated an obvious change in microstructure of the red-bed soft rocks after 3 months of water saturation. A decrease in pore number and increase in total pore surface area could be seen after 6 months of water saturation. Furthermore, the theoretical results suggest that chemical effects at the microscale dominate the softening process of the rocks. During the water–rock interaction, nearly 80% of the energy dissipation results from the microscale change, and the meso-macroscale change accounts for the remaining 20%. As a uniform measure of material evolution, energy can correlate the micro-meso-macro dominant effect of red-bed soft rocks softening appropriately.

Life cycle assessment of food waste management options: a case study at campus level to foster sustainable campus

ABSTRACT This study aims to evaluate the environmental impact savings by different food waste management options of a university campus to support decision-making in the scope of sustainable campus. For this purpose, food waste generated inside the campus was characterized, and a hypothetical anaerobic digestion plant with a biogas recovery system was modeled. Two scenarios, representing the modeled plant, and current practices (landfilling and energy production methods) were formed, and life cycle assessment was conducted. For the modeled plant, the biogas and methane yields were calculated as 0.66 and 0.36 l/g VS, respectively, and generated electricity and heat were found as 92.6 and 188.9 kWh/day, respectively. Impact assessment results showed that global warming and acidification potential are the main impacts resulting from the current practices. More than 88% of impact savings can be achieved in all assessed impact categories by shifting to anaerobic digestion. In the scope of campus sustainability, 23% and 16% of the electricity and heat demand of the selected building on the campus can be supplied which results in 7%, 5%, 5%, and 4% impact reduction on campus level for global warming, photochemical ozone formation – impact on vegetation, terrestrial eutrophication, and acidification, respectively. Our results suggest that micro-scale changes may also provide a considerable amount of environmental impact savings.

An adaptive method of measuring the rake face wear of end mills based on image feature point set registration

An acceptable tool wear evaluation and acquisition approach is critical for developing an accurate, rapid, and practical online tool wear prediction system. The one-dimensional crater wear depth is difficult to quantify, and relying solely on flank wear width is very simplistic. External conditions such as vibration and illumination have a large impact on two-dimensional wear area and three-dimensional volume. In practice, these are difficult to successfully characterize tool wear. This work proposes a two-dimensional rake face edge loss area as an additional indicator to assess milling cutter wear. An adaptive measurement approach based on 2D image feature point set matching is presented to suppress the area calculation error caused by image position offset and chips or built-up edges. 201 images were collected in two groups of cutting experiments for comparison with the proposed method and the other two methods, manual registration and non-registration. The results show that the proposed method's measurement values are closer to the actual values and have a higher measurement efficiency. Furthermore, the proposed indicator is sensitive to micro-scale changes to the blade edge, especially at the tip, and can be used as a supplement one to monitor tool wear more comprehensively.

Dynamic Structural Transformations in a Series of Zero-Strain Lithium-Ion Battery Materials: Almost Simultaneous Operando X-ray Diffraction and X-ray Absorption Spectroscopy on Li2ZnTi3O8 and Related Compounds

A series of Li4/3-2x/3ZnxTi5/3-x/3O4 (LZTO) with 0 ≤ x ≤ 0.5 have received considerable interest as a negative electrode material for long-cycle-life lithium-ion batteries. However, their dynamic structural transformations under operating conditions have remained unknown, making an in-depth understanding essential for further improving the electrochemical performance. We, thus, performed almost simultaneous operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) studies on x = 0.125, 0.375, and 0.5. The x = 0.5 sample, Li2ZnTi3O8, indicated differences in the cubic lattice parameter between the discharge and charge reactions (δacs), corresponding to the reversible movement of Zn2+ ions between the tetrahedral and octahedral sites. δac was also observed for x = 0.125 and 0.375, although the capacity region exhibiting δac decreased with a decrease in x. For all of the samples, there is no significant difference in the nearest-neighbor distance of the Ti-O bond (dTi-O) between the discharge and charge reactions. We also demonstrated different structural transformations between the micro- (XRD) and atomic (XAS) scales. In the case for x = 0.5, for instance, the maximum microscale change in ac was within +0.29(3)%, whereas at the atomic scale, dTi-O changed by up to +4.8(3)%. Combined with our previous results for ex situ XRD and operando XRD/XAS measurements on other x compositions, the whole structural nature of LZTO, such as correspondence between ac and dTi-O, origins for voltage hysteresis, and zero-strain reaction mechanisms, has been unveiled.

Mathematical modeling of morphological changes in photochromic crystals by catastrophe theory

Photochromic diarylethene is known to exhibit reversible photoisomerization under irradiation with ultraviolet (UV) and visible light. Besides reversible optical properties upon light irradiation, a variety of discontinuous morphological changes of the crystals are reported in the literature, such as sudden crystal bending, cracking, and photosalient effects, which are caused simply by UV and visible light irradiation. These morphological phenomena with discontinuities are micro-scale changes caused by photoisomerization of molecules at the nanoscale and lead to the realization of important functions for optical devices. However, the theoretical models behind these phenomena are not well understood. In this paper, we construct a mathematical model that can treat diverse phenomena in a unified model by using swallow-tail catastrophe, a higher-order catastrophe than cusp catastrophe, from the seven elementary catastrophes that can describe discontinuities in the phenomena. By introducing hyperbolic operating curves in the model, the intrinsic properties of the photochromic crystals are represented. The induced morphogenesis, such as bending, cracking, and photosalient effects, are systematically classified by the proposed catastrophe model, which even implies the possibility of unexplored operating conditions of the crystals and explains known phenomena. The proposed catastrophe-theory-based modeling provides a foundation for understanding and discovering the versatile morphogenesis in photochromic crystals. Furthermore, the proposed approach provides a basis for understanding and discovering various morphological changes in photochromic crystals and similar systems.

Using acoustic velocities and microimaging to probe microstructural changes caused by thermal shocking of tight rocks

Introduction: Large scale, Earth processes and bulk rock properties are influenced by underpinning, dynamic, microstructures within rocks and geomaterials. Traditionally, the amount of porosity has been considered the primary control on important bulk rock properties like seismic wave velocities (Vp and Vs) and permeability. However, in tight rocks, velocity and permeability (k) can change substantially despite small changes in the amount of porosity during cracking. Therefore, other microstructural features inherent to given lithologies, such as heterogeneity and anisotropy in mineral properties are considered as factors controlling these bulk rock properties. Understanding which microstructural features control Vp, Vs, and permeability in tight rocks is useful in applications like enhanced geothermal systems (EGS), where thermal shocking is used to increase permeability. Thermal shocking involves injecting surface water into the subsurface to cool mineral crystals, induce contraction of crystals, and cause thermal cracking.Methods: We tested three tight lithologies with unique microstructures; granodiorite (SWG), basalt (PTB), and carbonate (MSA). We simulated thermal shocking by slowly heating samples to 350°C and then quenching them. We chose a temperature of 350°C because thermal shocking at this temperature is not well documented in literature, and this temperature is relevant to EGS. Using time-lapse microimaging, we assessed how thermal cracking occurs in each lithology and explored how thermal cracks influence connected porosity, Vp, Vs, and k.Results: Microimaging shows extensive cracking in the SWG and MSA lithologies, and little to no cracking in PTB with thermal shocking treatment. Vp and Vs became more pressure sensitive, and elastic moduli decreased with treatment for all lithologies. This may be caused by reduced stiffness between mineral crystal boundaries with treatment.Discussion: Lithologies with minerals that have anisotropy of or a wide range in thermal conductivity and/or thermal expansion coefficients can have increased thermal cracking. In thermally shocked SWG and MSA, Vp and Vs are good indicators of thermal cracking and k increases, but less so in PTB. Lithologies like PTB may require multiple thermal shock stimulations to increase permeability. Our results highlight how micro-scale changes influence bulk rock properties and when we can monitor permeability increases and microscale thermal cracking with Vp and Vs.

Applications and Implications of Service Robots in Hospitality Sector: A Case Study

Purpose–Previous research has emphasized that service robots cause radically change current service production and delivery practices and, consequently, service management and marketing strategies. This research explores the use of current state-of-the-art service robotics in the hospitality industry and aims to better understand how this technology can transform service operations. Design/Methodology/Approach–An exploratory qualitative approach was adopted for this study. Case study pattern and holistic single case pattern were preferred from qualitative research patterns as the method of inquiry. This qualitative study was conducted using a thematic analysis approach.The criterion sampling method was performed to collect data with one participant through in-depth, semi-structured individual interview. Data were analyzed using a thematic approach that built on a priori themes or categories were adopted for data analysis. Findings –Analysis of participant’s perspectives and experiences showed the 8 themes of the roles of service robotics in service encounters including substitute, support, supporting new business models, improve, differentiate, creative experiences & competition, upskill, and data collection. Unlike the previous research, supporting new business models, creative experiences & competition, and data collection were also found as new technology roles specific to service robots. By developing a new conceptual DRiTE Model (Development of Robotics in Tourism Ecosystem), the research not only contributes theoretical implications to the literature but also offers business strategies (management, marketing, etc.) for hospitality firms to manage innovative, automated service offerings. Discussion –Despite previous research having extensively discussed the use of technology in services, it can be interpreted that the current global tourism industry on the use of robotics in service encounters is still in its infancy. Over time, these micro-scale changes will evolve to form a global ecosystem. This means that the way they do business will change on a global scale through various diffusion areas such as brand, service type or stakeholder network. The paper’s novelty and uniqueness lie in suggesting a new conceptual DRiTE of addressing the implications ofthis research and offering insight for hospitality services-related managers into how to effectively research implications can be implemented.

Dynamicity of language teacher motivation in online EFL classes

Despite the growing focus on the dynamic nature of second/foreign language (L2) teacher motivation in recent years, the existing work has primarily explored fluctuations in motivational trajectories over macro timescales covering months and years. Micro-scale changes of motivation at the lesson level and the factors underlying such changes have received little attention, particularly in the context of online instruction. The present study aims to close this gap by investigating dynamic changes in teacher motivation in the course of regularly-scheduled online English-as-a-foreign-language (EFL) classes in Turkey, as experienced by two EFL teachers at the tertiary level. Changes in motivation levels and the reasons for these changes were tracked in eight 45-min. classes over two weeks. Data were collected via self-ratings of motivational intensity at 5-min. intervals, journal entries, interviews, and lesson plans. The analysis showed considerable variation in the motivation levels within the participating teachers, with the fluctuations resulting from a complex array of learner-related, course-related, and individual factors. Overall, the findings provide further insights into the situated complexity of L2 teacher motivation and suggest that L2 teacher motivation to teach online is characterized by temporal, individual, and contextual variation, being open to influences and displaying nonlinear development over timescales.