Solid Inclusions Research Articles

Omphacite Melting and the Destruction of Early High‐Pressure Rock Records

AbstractThe presence of eclogite marks high‐pressure metamorphism and deep, cold burial of crust, and is therefore a widely accepted indicator for the onset of modern‐style plate tectonics. However, eclogite is rarely preserved in many heavily granulite‐overprinted orogens, which are particularly common across ancient metamorphic terranes (i.e., Archean and Paleoproterozoic terranes). Here, we show that eclogite melting processes may be principally responsible for the poor preservation of high‐pressure records. We demonstrate eclogite melting via detailed petrological, geochronological, and geochemical analyses on eclogites and separated centimetric leucosomes from the central Himalaya. The central Himalayan eclogites were overprinted by strong granulite‐facies metamorphism, such that omphacite is only sparsely preserved. Thermodynamic modeling results indicate the eclogite experienced two types of anatectic reactions: phengite dehydration melting at high‐pressure in the presence of omphacite, and subsequent omphacite dominated melting during exhumation. Diagnostic features for these melting reactions include (a) the occurrence of Kfs‐Pl‐Qz multiphase solid inclusions and Cpx‐Pl‐Qz polymineralic inclusions; (b) the high Na2O/K2O melts and Na‐rich plagioclase in leucosomes; (c) the consistent trace elements patterns between omphacite and leucosomes; and (d) obvious Na2O zonation in clinopyroxene. Omphacite dominated melting is characterized by the jadeite breakdown, releasing Na and Al into the melts. This melting mechanism subsequently forms a less sodic clinopyroxene and high Na2O/K2O melts. These Himalayan findings appear relevant to early Earth explorations because of the high thermal gradients and intense granulite‐facies overprints, implying that partial melting of eclogite dominated by omphacite breakdown could have erased early high‐pressure records of modern‐style plate tectonics.

Constraints on Crystallinity of Graphite Inclusions in Nephrite Jade from Xinjiang, Northwest China: Implications for Nephrite Jade Formation Temperatures

Graphite usually occurs in mineral/rock associations in the form of solid inclusions and plays an important role in tracing regional metamorphic degree, ore-forming temperature, fluid evolution, as well as the deep carbon cycle of the Earth. In this study, we investigate the placer black nephrite jade where the co-occurrence of abundant graphite inclusions and jade remains extraordinary. By employing petrographic, mineral-chemical, and Raman spectroscopic methods, we characterize the textures and crystallinity of graphite inclusions that exist in nephrite jade. EPMA and petrological data indicate that the main constituents of black jade are tremolite and graphite, with minor phases of diopside, calcite, dolomite, epidote, and apatite. Micro-Raman spectroscopic thermometry of carbonaceous material shows that most of the formation temperatures of graphite inclusions are between 378 and 556 °C, and only a few temperatures may be above 650 °C, indicating that graphite inclusions were formed at medium- to high-temperature metamorphic facies. The petrologic and spectral investigations of graphite inclusions in these nephrite jade samples show major metamorphic signatures with mixed features associated with fluid precipitation. Our results allow us to propose that primary nephrite jade was formed under multi-stage tectonic evolution conditions, and regional temperatures were predominately driven by the late continent–continent collision, while the ore-controlling temperatures of nephrite jade formation were found in a medium- to high-temperature environment.

Motion behaviour of solid inclusions at the steel–slag interface in high-Al steel

ABSTRACT In the steelmaking process of high-Al steel, solid inclusions will accumulate in the slag phase near the steel–slag interface, and it is crucial to eliminate the residual Al-containing inclusions in molten steel. In the present study, the film-rupture and drainage models were applied to clarify the characteristics of the inclusion detachment motion. The analysis of parameters was carried out and their impact on the inclusion motion was further discussed. It was found that the micro-size inclusions are prone to remain at the interface or rebound back into the steel. According to the models, the motion of the solid inclusion in the drainage stage is solely influenced by the steel density and the interfacial tension between steel and slag. The decrease of the steel–slag interfacial tension is beneficial to the transfer of the inclusions, while the low-density of the high-Al steel will promote the rebound of the inclusions.

Widespread development of bedding-parallel calcite veins in medium–high maturity organic-rich lacustrine shales (Upper Cretaceous Qingshankou Formation, Northern Songliao Basin, NE China): Implications for hydrocarbon generation and horizontal compression

Bedding-parallel calcite veins (BPCVs) occur widely in Upper Cretaceous lacustrine shales of the Qingshankou Formation in the Northern Songliao Basin, China. Research on the formation processes and geological significance of BPCVs has focused on the sources of fluid, timing of formation, initiation, dilation and growth mechanisms, and on relationships with hydrocarbon generation. In this study, we addressed these issues through a comprehensive study of drill cores containing BPCVs using petrographic observations, isotope geochemistry, rare earth element (REE) analysis, fluid inclusion analysis, in situ U–Pb dating, and basin modeling. BPCVs were observed in medium–high maturity shales with high organic matter contents with heterogeneous compositions. Similarities in δ13C, δ18O, 87Sr/86Sr, and REEs contents between BPCVs and the host shale indicate that locally derived formation fluids driven by chemical gradients were involved in BPCV formation. The in situ U–Pb age dating (70 ± 8.9 Ma and 70.6 ± 9.7 Ma) constrained BPCVs formation to the late Cretaceous, corresponding to a burial depth of ∼1600 m, indicating that the BPCVs formed in the oil window. The latter is also supported by fluid inclusions-derived temperatures (∼76–109 °C). BPCV formation included vein initiation and dilation, and the microstructures, e.g., domal and pincer structures, sigmoidal calcite veins, conjugate en-échelon calcite vein arrays, as well as mechanical crystal twins of the BPCVs, all indicate that tectonic compression influenced fracture development as also indicated in other basins where beef occur. Fluid overpressure caused by hydrocarbon generation, tectonic compression, and clay mineral transformation (mainly smectite to illite conversion) was responsible for vein dilatation. Antitaxial fibrous crystals with smooth crystal boundaries and high aspect ratios, containing sinusoidal solid inclusions as well as median planes, indicate that crystallization force promoted vein growth. Thus, BPCVs can be used as a good indicator of hydrocarbon generation, and horizontal tectonic compression.

Phase analysis of complex non-metallic inclusions in Al-deoxidized 42CrMo4 steel after contact with MgO–C refractories

This study extensively investigated characteristic non-metallic inclusions in oxidized and deoxidized 42CrMo4 steel after contact to MgO–C refractories, proposing possible formation and modification mechanisms of non-metallic inclusions. The structures and compositions of different inclusion species were analyzed, revealing various types: crystalline, amorphous, and complex inclusions containing both crystalline and amorphous phases. The latter always consisted of an amorphous Mn–Si–Al–O matrix containing various crystalline phases such as Al2O3, MnAl2O4 and/or MnTiO3. The formation of amorphous Mn–Si–Al–O inclusions was attributed to steel melt oxidation, while pure crystalline corundum inclusions resulted from both the steel melt oxidation and deoxidation. Alumina inclusions exhibited different shapes, likely because of variations in aluminum and oxygen supersaturation in the steel melt during their formation. Complex inclusions were suggested to form through precipitation on existing inclusions and mutual collision of pre-existing inclusions, facilitated by the non-wetting behavior of solid alumina inclusions in the steel melt.

Pressure–temperature–time path of ultrahigh-pressure metamorphic terranes constrained by zircon petrochronology: A case study of orthogneisses from the northern Sulu belt, China

Reconstruction of pressure–temperature–time (P–T–t) path of volumetrically-dominant orthogneisses in deeply subducted continental crusts is challenging due to their simple amphibolite-facies mineral assemblages. To provide new insights into this issue, a detailed study of mineral inclusions, trace elements and U-Pb ages within robust zircon containers, together with titanite U-Pb dating and petrology were conducted on ultrahigh-pressure (UHP) orthogneisses from the northern Sulu belt. The following P–T–t conditions of three metamorphic stages were constrained: (i) cathodoluminescence (CL)-grey zircon cores (ca. 238–237 Ma) with flat heavy rare earth element (HREE) patterns include garnet, phengite and omphacite that yield estimated P–T conditions of 2.3–2.8 GPa/730–800 °C, corresponding to prograde high-pressure (HP) metamorphism before the UHP peak. (ii) CL-dark zircon mantles (ca. 224 Ma) contain multiphase solid inclusions of plagioclase + K-feldspar + quartz and show extremely low Th/U ratios (≤0.08) and negative Eu anomalies, demonstrating their crystallization from hydrous melt at 2.0–1.8 GPa/890–820 °C during HP eclogite-facies exhumation. In addition, titanite grains are characterized by high LREE contents (1939–5239 ppm), Th/U ratios (0.37–0.81) and crystallization temperatures (830–801 °C), suggesting their peritectic origin. The lower intercept age (220 ± 4 Ma) of titanite is broadly consistent with the ages of the zircon mantles, indicating that they both crystallized from the melt at the same stage. (iii) CL-bright zircon rims (ca. 212–211 Ma) preserve low-pressure mineral inclusions of plagioclase, K-feldspar and quartz, and they show low Th/U ratios (0.03–0.12) and steep HREE patterns with negative Eu anomalies, witnessing amphibolite-facies overprinting at 1.0–0.8 GPa/610–550 °C. Combined with the metamorphic peak conditions of 3.2 GPa/840 °C at ca. 232 Ma constrained by previous studies from the same area, the P–T–t path of the northern Sulu UHP belt is reconstructed. The data reflects two-stage exhumation of this terrane, including an early-stage (5.8 km/m.y.) and a later-stage slower (3.1 km/m.y.) exhumation processes. The faster exhumation during early decompression was probably enhanced by extensive melting activity recorded by the CL-dark zircon mantles from the orthogneisses.

It’s a trap!: Modern and ancient halite as Lagerstätten

ABSTRACT Chemical sediments, such as bedded halite (NaCl), are strongly influenced by environmental conditions during deposition and, if unaltered, may preserve microorganisms, microfossils, and organic compounds for hundreds of millions of years. Recent studies show that halite is an excellent repository for organic materials, as well as a variety of environmental data. Halite is a perfect trap. Due to its rapid growth, parent brine, gas, crystals of other minerals, and any organic material are encased within primary fluid inclusions or as solid inclusions along growth bands. These inclusions function as “snapshot” repositories of the hydrosphere, atmosphere, lithosphere, and biosphere. However, organic material in halite is still relatively unknown in the sedimentological and paleontological communities. Here, we present highlights of preservation in halite to showcase the diversity of life that has been documented within it. We also discuss: 1) the properties of halite that give it such excellent preservation potential, 2) the challenges to and strategies for studying organic material in halite, 3) preservation in other salt minerals such as gypsum, and 4) implications for astrobiological research. Recommendations for the future study of organic material in halite include collaboration amongst chemical sedimentologists, paleontologists, and microbiologists.

Acoustic wave propagation in a porous medium saturated with a Kelvin–Voigt non-Newtonian fluid

SUMMARYWave propagation in anelastic rocks is a relevant scientific topic in basic research with applications in exploration geophysics. The classical Biot theory laid the foundation for wave propagation in porous media composed of a solid frame and a saturating fluid, whose constitutive relations are linear. However, reservoir rocks may have a high-viscosity fluid, which exhibits a non-Newtonian (nN) behaviour. We develop a poroelasticity theory, where the fluid stress-strain relation is described with a Kelvin–Voigt mechanical model, thus incorporating viscoelasticity. First, we obtain the differential equations from first principles by defining the strain and kinetic energies and the dissipation function. We perform a plane-wave analysis to obtain the wave velocity and attenuation. The validity of the theory is demonstrated with three examples, namely, considering a porous solid saturated with a nN pore fluid, a nN fluid containing solid inclusions and a pure nN fluid. The analysis shows that the fluid may cause a negative velocity dispersion of the fast P(S)-wave velocities, that is velocity decreases with frequency. In acoustics, velocity increases with frequency (anomalous dispersion in optics). Furthermore, the fluid viscoelasticity has not a relevant effect on the wave responses observed in conventional field and laboratory tests. A comparison with previous theories supports the validity of the theory, which is useful to analyse wave propagation in a porous medium saturated with a fluid of high viscosity.

Soft solid subwavelength plates with periodic inclusions: Effects on acoustic Transmission Loss

Dispersion and scattering properties of a soft solid plate with solid cylindrical inclusions embedded in are theoretically and numerically reported in this work. The system is numerically analyzed considering both the vibroacoustic coupling and the presence of viscoelastic losses. In addition to the mechanical properties of the soft solid plate that allows the shift of the higher order Lamb modes to the low audible frequency domain, the presence of the inclusions introduces resonant and antiresonant phenomena in the subwavelength regime, leading to an elastic band-gap and a destructive modal interference in the soft solid plate able to interact with each other. These phenomena are used to design a system with strong transmission loss, breaking the mass law by 15 dB, and with subwavelength dimensions as the thickness is 32 times smaller than the equivalent wavelength in air. These performances are both computed and tested experimentally using a standard measuring process.

Start of the work-based learning revolution? The impact on academic quality of Dutch science masters, perceived by university professors

PurposeWork-Based Learning (WBL) is a form of practical learning that is still rare, yet upcoming in academic education. It differs mainly from classical approaches because work experience forms a key curriculum element. To enable WBL, a cultural change in academic landscape seems required, which depends on views and support of academic staff.Design/methodology/approachThe authors carried out a case study, in which the authors interviewed 20 Dutch science professors to examine their vision on the master track Science, Business and Policy (SBP), a WBL program offered for over 15 years.FindingsGenerally professors are positive about its added value and recommend the track, especially for students with career ambitions outside academia. WBL is perceived to have a positive contribution to academic level. Professors indicated that for academic skills development, compared with a traditional master's program, SBP is evaluated neutral to positive.Originality/valueAltogether the current climate at the university of Groningen towards WBL seems predominantly positive. The educational change towards a solid inclusion of WBL in the regular curriculum seems supported by one of the key players, the professors. This track could thereby be an example for other WBL programs worldwide.

Encapsulation of hyperoside with acyclic cucurbiturils: Supramolecular binding behavior, water solubility and in vitro antioxidant activity

Hyperoside (Hyp) is a natural flavonol glycoside widely present in plants, which possesses important pharmacological activities including anti-inflammatory, anti-viral, organ-protection, antioxidant, and anti-tumor, etc. However, its poor water solubility and low oral bioavailability severely limit its further development for pharmaceutical uses. In this work, solid inclusion complexes of Hyp with two acyclic cucurbiturils (ACBs, M1 and M2) were prepared by the method of suspension. The formation of inclusion complexes was confirmed by Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD) and nuclear magnetic resonance (NMR) analyses. Based on Job's plot, proton nuclear magnetic resonance (1H NMR) spectroscopy, two-dimensional diffusion ordered spectroscopy (2D-DOSY), two-dimensional rotating-frame Overhauser enhancement spectroscopy (2D-ROESY) and molecular docking experiments, a 1:1 inclusion mode was rationally proposed. The binding stability constants (Ks) were determined by fluorescence titration, up to 4.22 × 104 and 6.97 × 104 L·mol-1 for Hyp/M1 and Hyp/M2, respectively. After inclusion complexation with ACDs, the water solubility of Hyp was elevated by more than 300-fold, which was much superior to that with cyclodextrins. Furthermore, in vitro antioxidant activity of Hyp was significantly promoted by formation of inclusion complexes. These results would inspire new strategies for further developments of Hyp for pharmaceutical uses.

Progressive algorithm for the scattering of electromagnetic waves by a multilayered eccentric sphere.

This paper presents a general progressive algorithm for the computational study of electromagnetic wave scattering by a multilayered eccentric nanoparticle. The presented methodology is based on a combination of the vector addition theorem for spherical wave functions and an efficient progressive algorithm that matches the boundary conditions of every two adjacent shell layers from the outmost to the innermost layer. As a result, only a solution of small-sized matrices is required rather than solving a large set of system equations as reported in other works. With the developed approach, explicit expressions of the Mie scattering coefficients of the eccentric particle can be obtained. Moreover, the Mie coefficients of a specific inner layer could be calculated selectively, instead of having to compute those of all layers of the entire particle as required by other algorithms. The presented methodology can be used to study practically any type of spherical particle inclusions and the most widely studied cases such as scattering by solid particles, concentric particles, and inclusions with centers displaced along a straight line are just special cases of the algorithm presented. Computed results are also presented, illustrating that the eccentric structure allows extra freedom in the design of multilayered nanoparticles for optical applications.

Encapsulation through concern of inter and intramolecular hydrogen bonding of 2-hydroxybenzoic acid with C-alkyl calix[4]resorcinarenes

The host-guest complexation of 2-hydroxybenzoic acid (compound 4) with four C-alkyl calix[4]resorcinarenes (compounds 3a-3d) were investigated in aqueous, solid state and gas phase. The solid inclusion complexes were prepared by solvent evaporation method. The solubility of compound 4, compounds 3a-3d and inclusion complexes were analyzed in different polar, non-polar and dipolar solvents. The binding stoichiometric ratio of inclusion complexes was analyzed by phase solubility and jobs plot method. UV–Visible and fluorescence spectral studies were provided the information about binding constant, stoichiometric ratio and Gibb's free energy values. The solid inclusion complexes were characterized by FTIR, 1HNMR , 13CNMR and powder X-ray diffraction studies to determine the interactions between the compound 4 and compounds 3a-3d. The surface morphology of all were characterized by scanning electron microscopic imagining analysis. The biological activity of all were done by phosphomolybdate antioxidant assay and kirby-bauer antibacterial studies. The proposed structure of inclusion complexes were optimized for the two orientations using DFT B3LYP 3–21 G method in the gas phase. The more stable orientations of inclusion complexes were predicted from energy and band gap energy values

Genesis of Fibrous Calcite in the Chang 7 Member of the Yanchang Formation, Ordos Basin

AbstractTo explore the genesis of the laminated calcite veins developed in the black shale of Chang 73 submember of the Ordos Basin, the petrology, microstructure and geochemistry of calcite veins are studied using thin sections, fluid inclusions, trace elements and isotopic geochemistry. The source, the time of formation, the mechanism of formation, and the dynamic background of the veins are discussed. The veins are mostly made up of calcite, mixed with lenticular or spindle‐shape solid wall rock inclusions. Three structures are identified in the calcite minerals: fibrous, rhombic cleavage, and wedge‐like structure. Trace elements and isotopes of carbon and oxygen confirm that the calcite veins were formed from a high density hydrothermal fluid. It is assumed that calcite veins formed prior to wall rock consolidation during the formation of the Qinling Orogenic Belt in the Middle and Late Triassic. The results show that the sedimentary sources of Chang 73 submember were influenced by hydrothermal materials besides terrigenous detritus. The fibrous calcite is different from the fibrous calcite reported in the morphology and mechanism of formation. In this way, the research complements and improves the morphology and the mechanism of formation of fibrous calcite.

Pressure-induced Fermi resonance between fundamental modes in α-Hydroquinone

Fermi resonance (FR), a prevalent phenomenon in molecules, has an important effect in spectrum analysis. As an effective way to change the molecular structure and tune symmetry, high-pressure techniques can often induce FR. Hydroquinone (HQ) is a hydrogen-bonded crystal that tends to form a solid inclusion compound with a suitable guest and has wide applications. Inthiswork, a high-pressure technique was used to investigate α-HQ using high pressure to tune the symmetry to produce FR. Raman and infrared spectra of α-HQ were investigated at ambient pressure, and then Raman spectra under high pressure of α-HQ were investigated up to 19.64 GPa. Results indicated that there were two phase transitions found at about 3.61 and 12.46 GPa. Fundamental FR was not present in α-HQ molecules at ambient pressure. At 3.61 GPa, the first-order phase transition occurred due to the pressure-induced symmetry change, resulting in two Raman modes at 831 cm−1 and 854 cm−1 with the same symmetry, thereby providing evidence that the fundamental FR phenomenon occurred. Furthermore, the pressure-induced changes of the FR parameters were elucidated. Thus pressure provided an effective way to study FR between two asymmetric species.

Fingerprinting crustal anatexis with apatite trace element, halogen, and Sr isotope data

The geochemistry of apatite is a valuable tool for granite petrogenetic study. Here we explore the capability of apatite for fingerprinting anatectic reactions during crustal melting. We conducted a detailed petrographic, trace element, volatile, and Sr isotopic study of the apatites from four groups of leucosomes and leucogranites that formed by amphibole dehydration melting (group I), hydration melting (group II), muscovite dehydration melting (group III), and feldspar accumulation (Group IV) from the central Himalayan orogen. The coexistence of primary CO2-rich fluid and multiphase solid inclusions in apatite indicates fluid–melt immiscibility and suggests that C–O–H fluids were present during hydration melting. We observe marked differences in major and trace element, as well as halogen (F and Cl) contents in apatite from different groups, corresponding to different melting reactions. Apatite REE, Y, Mn, F, and F/Cl exhibit a decrease, whereas Sr/Y and Cl increase, from muscovite dehydration melting to hydration melting, and to amphibole dehydration melting. Amphibole dehydration melting results in similar CaO, Sr, and Eu/Eu* in apatite to hydration melting, but the latter leads to lower (La/Yb)N in apatite. These geochemical differences in apatite can be explained by different minerals participating in the melting reactions and varying melt polymerization resulting from the different melting reactions. The degree of melt polymerization decreases in the sequence from muscovite dehydration melting to hydration melting, and to amphibole dehydration melting. A higher degree of melt polymerization results in higher values for trace element partition coefficients between apatite and melt, and therefore the enhanced incorporation of REE, Y and Mn in apatite. Higher Sr and Eu/Eu* in apatite reflect the consumption of a larger amount of plagioclase in the melting reaction. The F and Cl contents in partial melts were calculated based on apatite composition, which exhibit an increasing trend from hydration melting to muscovite hydration melting, and to amphibole hydration melting. Such a trend can be explained by different proportions of hydrous minerals (muscovite and amphibole) participating in the melting reactions, with amphibole responsible for the high Cl content in melt and apatite. In addition, the apatite Sr isotopic compositions record the Sr isotopic disequilibrium during partial melting and exhibit distinct evolutional trends resulting from different anatectic reactions. Muscovite dehydration melting forms melt with higher 87Sr/86Sr than the restite due to radiogenic Sr released by muscovite. Apatite therefore records progressively decreasing 87Sr/86Sr during melt evolution before the isotopic homogenization between the partial melt and the restite. In contrast, apatites crystallized from the melt of hydration melting show an evolutional trend of increasing 87Sr/86Sr. In summary, the elemental and isotopic compositions of apatite can be related to different types of melting reactions, and can therefore be used as an indicator of the mechanisms of melt formation during crustal anatexis. We demonstrate such an application through the case study of group IV apatite from feldspar accumulation, and also explore its utility in granite petrogenetic studies.

Applying Numerical Optimization Technique in the Development of Valueadded Powdered Custard

Custard powder is a relatively shelf-stable, fine textured, dry-formulated, carbohydrate-rich breakfast food product primarily made from corn starch with the addition of salt, flavoring, and coloring agents and with or without the inclusion of egg yolk solids, vitamins, and minerals. The aim of this study was to formulate, characterize, and optimize value-added custard from millet, soybean, and tigernut. A three-component constrained optimal (custom) mixture experimental design, with 69 randomized experimental runs, was employed. The formulation design constraints were: millet (10% - 70%), soybean (10% - 70%), and tigernut (10% - 70%). Other constant components of the formulation were sweet potato extract (3%), date (2 %), clove (1%), cinnamon (1%), turmeric (1%), and ginger (2%). The formulated samples were analyzed and evaluated for quality and sensory characteristics using standard procedures. The result of the optimization gave optimized custard with an overall desirability index of 0.535, based on the set optimization goals and individual quality desirability indices. The optimal formulated value-added custard was obtained from 10.0 % millet flour, 49.3 % soybean meal, and 30.7 % tigernut. The quality properties of this optimal custard are 3.78 % ash content, 28.5 % crude protein, 10.1 % moisture content, 20.1 % fat content, 4.43 % crude fibre, 33.9 % carbohydrate, and 5.79 overall acceptability. The result of the study showed that the formulated value-added custard was found to be of higher quality than the traditional custard which is produced from monocereals. Improving the nutritional quality of food and tackling nutrient deficiencies, particularly protein energy malnutrition in populations, is possible through the application of numerical optimization technique in development new, dietary-based food products.

The extreme bulk-modulus contrast of bubbly soft matter for underwater acoustic modulation

Bubbles in liquid and soft matter are excellent acoustic resonators with extremely low resonant frequencies. We find that bubbly soft matter (BSM) can enable full-phase (2π) modulation of incident acoustic waves just through changing the bubble size. Compared with the conventional solid–solid binary locally resonant metamaterial (SSM), due to the extreme bulk-modulus ratio of the bubbles and the soft matrix, the BSM has two distinguished merits. First, the size of the bubbly inclusions for the full-phase modulation is only about a third of the solid inclusions in the SSM; second, the range of variation of the bubbly inclusions to cover the full-phase modulation is two orders of magnitude wider than that of the solid inclusions. These features, combined with the salient advantage of wave-impedance match between soft matter and water, can realize compact and light-weight reflective and transmissive underwater bubble metasurfaces. At the lower limit 3 kHz of the active sonar operating frequency, an ultrathin reflective metasurface with a thickness of 1/50 the wavelength can redirect the incident waves at a given angle. Bubble resonance in soft matter opens a new avenue for underwater acoustic modulation at the deepest subwavelength.

Anelastic dispersion and attenuation of P- and SV-wave scattering by aligned nonisothermal inclusions of finite thickness

We have investigated the anelastic dispersion and attenuation of P- and SV-wave scattering by nonisothermal inclusions of finite thickness. The inclusions, which are aligned and sparsely embedded in an isotropic medium, induce an initial static stress field (acoustoelasticity) and a nonlinear dependence of the velocities on this stress. Moreover, we describe the anelastic properties as a function of frequency by incorporating the displacement discontinuities across the inclusion into the representation theorem by using the Foldy approximation. The response as a function of temperature is calculated for different incidence angles (anisotropy), and the results find that anelasticity increases with an increasing temperature difference between the inclusions and the background medium. The SV wave in the solid inclusions indicates a stronger sensitivity along the inclusion normal, and it is more affected than the P wave. The P- and SV-wave scattering by fluid-saturated inclusions behave in an opposite manner. This theory can be useful to evaluate the distribution of temperature from seismic attributes.

Evaluating the effect of solid lubricant inclusion on the friction and wear properties of Laser Sintered Polyamide-12 components

The processing of Polyamide-12 (PA12) by Laser Sintering is one of the most well-established Additive Manufacturing (AM) processes for producing functional components for end-use applications. However, its further adoption within industry remains hindered by an incomplete understanding of resultant part quality and the impact this has on component wear. The scope of this research was to investigate the dry sliding behaviour of Laser Sintered Polyamide-12, as well as evaluate whether the inclusion of solid lubricant fillers effect the friction and wear properties of parts produced. Polytetrafluoroethylene (PTFE), Graphite and Molybdenum disulphide (MoS2) were added to Polyamide-12 powder in 1 : 100 mass ratios, respectively, to create three different polymeric composites. Mechanical blending and Laser Sintering then ensued; the latter was performed using identical processing parameters throughout. Tribological performance was evaluated by ball-on-flat uni-directional wear testing. Tensile testing was also carried out to help elucidate what wear mechanisms were active during sliding, as well as identify whether solid lubricant inclusion impacted mechanical performance. Results showed that in all instances solid lubricant inclusion significantly influenced the friction and wear properties of resultant composites, without compromising their mechanical performance when compared with neat-PA12. More specifically, it was demonstrated that the individual additions of PTFE and MoS2 could reduce the coefficient of friction and specific wear rate of Laser Sintered PA12 components by as much as 50% and 78%, respectively.