Expansion Properties Research Articles

Effects of Xanthan Gum Addition and Extrusion Parameters on Properties of Starch‐Based Fried Corn Extrudates

AbstractStarch‐based corn grits are extruded and then the extrudates are fried to development for corn snacks with low oil content, improved texture, and preserved color characteristics. Effects of screw speed (100–300 rpm), feed moisture (37–47%), and xanthan gum (XG) level (0–1%) on expansion, oil absorption, hardness, color, and microstructural properties of fried extrudates are examined. Increased screw speed increases expansion index (EI) due to enhanced starch gelatinization. Elevated feed moisture content increases EI as a result of the low solubility index of starch‐based extrudates. The oil absorption of extrudates increases as screw speed and moisture content are elevated as a result of holes in the surface after frying. On the other hand, the incorporation of XG decreases oil absorption due to reduced holes on the surface. Hardness values range from 7.58 ± 0.47 to 42.26 ± 1.44 N. Increasing moisture content decreases the hardness of fried extrudates while increasing screw speed results inan increase in hardness. The incorporation of XG increases the hardness of extrudates. Increased screw speed, feed moisture, and XG ratio increase the lightness value and decrease the redness value. Browning index (BI) is decreased with an increase in feed moisture and XG level.

Polynomial stochastic dynamical indicators

This paper introduces three types of dynamical indicators that capture the effect of uncertainty on the time evolution of dynamical systems. Two indicators are derived from the definition of finite-time Lyapunov exponents, while a third indicator directly exploits the property of the polynomial expansion of the dynamics with respect to the uncertain quantities. The paper presents the derivation of the indicators and a number of numerical experiments that illustrates the use of these indicators to depict a cartography of the phase space under parametric uncertainty and to identify robust initial conditions and regions of practical stability in the restricted three-body problem.

Probing system size dependence at high baryon density by systematic comparison of Ag+Ag and Au+Au reactions at 1.23A GeV

We present UrQMD predictions for the comparison of the recently measured Ag+Ag and Au+Au runs at a beam energy of E lab = 1.23A GeV explored by the HADES experiment. To this aim, different centrality definitions are investigated: We suggest that in the case of particle production, both systems should be compared at the same number of participating nucleons, while for a comparison of the (elliptic) flow, a selection on the initial state eccentricity—as in high energy reactions—is better suited. Generally, we find good agreement between both systems, if these centrality criteria are used. Specifically, the deuteron yields per participant and the pion to proton ratios are shown to scale with A part except for very central Ag+Ag reactions due to stronger stopping in such reactions. The elliptic flow in both systems follows initial state eccentricity scaling, albeit with the opposite sign as compared to high energies, suggesting a strong relation between final flows and the initial state also at the low energies explored here. The observation of this scaling might then allow to obtain further information on the expansion properties (and the EoS) of matter at high baryon densities.

A Systematic Method to Investigate the EOR Mechanism of Nanospheres: Laboratory Experiments from Core to Micro Perspective

Nanospheres have been used as an available plugging material to solve the problem of water intrusion, which is of crucial importance to enhanced oil recovery (EOR). However, the microflow of nanospheres in a low-permeability reservoir is complex, and its plugging performance and EOR mechanism need to be further investigated by a variety of experiments. In this paper, the expansion experiments were given priority to explore the water absorption and salt tolerance of nanospheres. The displacement experiments were conducted to investigate the plugging performance of nanospheres at the core scale. The flow characteristic and EOR mechanism of nanospheres at the microscale were revealed by nuclear magnetic resonance (NMR) experiments and microfluidic experiments. Expansion and displacement experiments results demonstrate that high salinity inhibits the expansibility and agglomeration of nanospheres, and the formation damage and plugging performance of nanospheres should be comprehensively considered. The suitable particle size of nanospheres should be optimized for field application. As for the microscale, NMR experiments revealed that nanospheres would first enter the large pore and then enter the middle and small pores. In microfluidic experiments, the oil recovery increased by 23.02% original oil in place after the injection of nanospheres. The systematic and comprehensive investigations of expansion property, plugging performance, flow characteristic, and EOR mechanism of nanospheres were conducted from core to microscale, which yielded significant insights into preventing water intrusion and enhancing oil recovery.

Phase stability and tensorial thermal expansion properties of single to high‐entropy rare‐earth disilicates

AbstractTemperature limitations in nickel‐base superalloys have resulted in the emergence of SiC‐based ceramic matrix composites as a viable replacement for gas turbine components in aviation applications. Higher operating temperatures allow for reduced fuel consumption but present a materials design challenge related to environmental degradation. Rare‐earth disilicates (RE2Si2O7) have been identified as coatings that can function as environmental barriers and minimize hot component degradation. In this work, single‐ and multiple‐component rare‐earth disilicate powders were synthesized via a sol‐gel method with compositions selected to exist in the monoclinic C 2/m phase (β phase). Phase stability in multiple cation compositions was shown to follow a rule of mixtures and the C 2/m phase could be realized for compositions that contained up to 25% dysprosium, which typically only exists in a triclinic, P , phase. All compositions exhibited phase stability from room temperature to 1200°C as assessed by X‐ray diffraction. The thermal expansion tensors for each composition were determined from high‐temperature synchrotron X‐ray diffraction and accompanying Rietveld refinements. It was observed that ytterbium‐containing compositions had larger changes in the α31 shear component with increasing temperature that led to a rotation of the principal axes. Principal axes rotation of up to 47° were observed for ytterbium disilicate. The results suggest that microstructure design and crystallographic texture may be essential future avenues of investigation to ensure thermo‐mechanical robustness of rare‐earth disilicate environmental barrier coatings.

Growth Considering Lattice Mismatch and Thermal Expansion and Magneto-Optical Properties of Bismuth-Doped Rare Earth Iron Garnet Crystals

Bi3+-doped iron garnet crystals (Bi:RIG) have received extensive attention for their excellent magneto-optical properties. The quality of garnet crystals has a great relationship with mismatch in the lattice and thermal expansion between crystals and seeds. Compared with TGG seeds, Sc,Ga:YIG is more suitable as the seed for growing Bi:(HoEu)IG crystals. The crystal quality and match in the lattice and thermal expansion have been discussed. The as-grown Bi:(HoEu)IG crystal has a specific Faraday rotation angle of −467° cm–1 and shows a strong magneto-optical effect.

Behavior of bismuth ions in the two glassy systems of 50 LiF-50 P2O5 and 50 LiF-50 B2O3 (mol %) assessed by optical, FTIR and photoluminescence spectra in addition to thermal expansion properties

Glasses from two varieties of (LiF-B2O3) and (LiF-P2O5) systems with equal 50 mol % for each partner together with samples doped with 1 or 2% Bi2O3 were synthesized by melting–annealing mechanism. Multiple optical, FTIR and photoluminescence spectral measurements were carried out. Optical spectra of Bi2O3—doped glasses exhibit UV-near visible peaks owing to the specific absorption of Bi3+ ions. FTIR spectra elucidate the presence of characteristic vibrational bands from (LiF-B2O3) glass due to (BO3) and (BO3F) groups beside (LiF4) groups while the fluorophosphate glasses (LiF-P2O5) show vibrations due to PO4 and (PO3F) groups and also the possible sharing of (LiF4) groups. Photoluminescence spectral data reveal extended emission from about 375 to 700 nm and is more prominent in (LiF-B2O3) system than (LiF-P2O5) system. The thermal expansion data reveal similar behavior and the derived transition and softening temperatures are slightly lower in (LiF-P2O5) glasses than (LiF-B2O3) glasses.

Comprehensive investigation of lattice dynamics of neutron multiplier beryllides: vibrational spectra and thermal performances

In order to realize tritium self-sufficiency during the operation of fusion reactors, neutron multiplier materials are needed to multiply the number of neutrons. Beryllium (Be) and beryllides (Be12V, Be12Ti) are considered as candidates for neutron multiplier materials in the tritium breeding blanket. Thermal performances are essential data to evaluate the service performance of materials in future fusion reactors. Due to the toxicity of beryllium, the preparation and analysis of neutron multiplier materials are challenging. As a result, the performance data of neutron multiplier materials are limited. It is essential to adopt the theoretical method to get the basic parameters for the design of a tritium breeding blanket and optimization of neutron multiplier. In the present work, the electron structure, vibrational spectra, and thermal performances have been theoretically investigated to understand thermal expansion and thermal conductivity properties. Experimental data are also included to compare with the calculated results and detailed analysis is presented. Due to the reactivity with water, BeO will form on the surface of Be. Therefore, BeO was studied as well. The bulk modulus of Be is the smallest of the four materials, while BeO is the largest. Higher bulk modulus has a better ability to restrain the deformation due to pressure. The c-axis of the Be12V has the largest thermal expansion coefficient, while the c-axis of the Be12Ti is the smallest. It has been found that the larger the lattice constant of crystal axes, the smaller the linear thermal expansion coefficient in same material. Electrons play a major role in the heat transfer of Be12V and Be12Ti. At high temperatures, phonon and electron coupling must be considered. Isotopeenrichment and enlarging the grain size cannot significantly improve the phonon thermal conductivity when the temperature is higher than room temperature. The calculated values can be adopted to predict the materials’ performances and support future fusion reactors’ neutron multiplier material preparation.

Design of a transportable miniaturized optical reference cavity with flexibly tunable thermal expansion properties

A 3-cm-long optical reference cavity for transportable miniaturized ultra-stable laser is designed and analyzed using finite element analysis (FEA). Although the tiny cavity is formed in a conventional way, in which a cylinder spacer made of ultra-low expansion (ULE) glass is optically contacted with fused-silica mirror substrates and compensation rings, the compensation rings are specially designed in order to broaden the zero-thermal-expansion temperature tuning range. In addition, the cavity is capable of being rigidly fixed by clamping both end sections of the cylinder spacer along the axis. The thermodynamic analysis shows that a larger tuning span of the zero-thermal-expansion temperature varying from −10 K to + 23 K compared to all-ULE cavity is benefited, resulting in the whole optical reference cavity could work around room temperature. Meanwhile, the statics analysis indicates the design is insensitive to extrusion force and vibration so that it owns a potential of solid performance after transportation.

Featurization of Ultrafast Expansion and Geometrical Properties of Heterogeneous Colliding Plasmas

Numerous fields of research and industry have undergone revolutionary change because of the unique characteristics of ultrashort laser pulses. Moreover, the ultrafast imaging sensors, such as ICCD technique, can help to understand the ionization features and expansion properties of colliding laser-induced plasma (CLPP) and related stagnation layer (S.L.) geometry. In this work, the effort will be focused on CLPP experiments from two seeds of heterogeneous elements. The research’s goal is to analyse the geometrical development of the colliding plasma, the temporal evolution of plume composition features and its associated characteristics. The expansion velocity and forward propagation range (FPR) of the stagnation layer in a nanosecond scale—both of which have been discovered. The ultrafast imaging results give the sight and explain the possibilities of extant technologies that can help to re-engineer the plasma characteristics for the next generation of lithography applications or new selective physical concepts.

Structure, magnetism and low thermal expansion in Tb1-xErxCo2Mny intermetallic compounds

Here, we obtained a series of controllable thermal expansion alloys Tb1-xErxCo2Mny (x = 0-0.5, y = 0-0.4) by incorporating double rare earth doping and introducing non-stoichiometric Mn content. By varying the amount of Er or Mn, a low thermal expansion (LTE) is achieved in Tb0.6Er0.4Co2Mn0.1 (TECM, α1 = 1.23 × 10-6 K-1, 125~236 K). The macroscopic linear expansion and magnetic properties reveal that anomalous thermal expansion is closely related to the magnetic phase transition. Synchrotron X-ray powder diffraction results show that TECM is a cubic phase (space group: Fd-3m) at high temperatures, and a structural transition to a rhombohedral phase (space group: R-3m) occurs as temperature decreases. The negative thermal expansion c-axis compensates for the normal positive thermal expansion of the basal plane, resulting in the volumetric LTE. This study provides a new metallic and magnetic ZTE material.

Thermally Induced Microcracks in Granite and Their Effect on the Macroscale Mechanical Behavior

AbstractUnderstanding the thermal effects on rock is critical for the exploration of geothermal resources and the temperature‐driven evolution of Earth. The macroscale mechanical behavior of granite under thermal loading can be complicated due to microcracking and the heterogeneity of minerals. In this study, the thermally induced microcrack propagation of granite was first observed in real time by an ultrahigh‐temperature instrument on an optical microscope. The previous investigation believed that the α–β quartz transition at approximately 573°C leads to a sharp decrease in macroscale mechanical behavior. However, the present experimental results revealed that microcracks initiate at 300°C and coalesce between 400 and 600°C, which is the main reason for the sharp decrease in macroscale mechanical properties of granite. Additionally, an accurate grain‐based model based on the mineralogical morphology of granite samples adopted mechanical parameters of minerals obtained from microscale rock mechanical techniques. It is able to well reproduce the process of microcracking and the strength evolution of granite during heating. The numerical results show that the heterogeneity of thermal expansion and mechanical properties of minerals produce local thermal stress concentrations in granite. The uneven tensile‐compressive stress between feldspar and quartz and the shear stress around biotite result in the initiation and propagation of microcracks. The present work is potentially useful for understanding and predicting the mechanical behavior of granites under thermal loading with different mineral compositions and microstructures.

Colossal negative thermal expansion in a cucurbit[8]uril-enabled uranyl-organic polythreading framework via thermally induced relaxation.

It is an ongoing goal to achieve the effective regulation of the thermal expansion properties of materials. In this work, we propose a method for incorporating host-guest complexation into a framework structure and construct a flexible cucurbit[8]uril uranyl-organic polythreading framework, U3(bcbpy)3(CB8). U3(bcbpy)3(CB8) can undergo huge negative thermal expansion (NTE) and has a large volumetric coefficient of -962.9 × 10-6 K-1 within the temperature range of 260 K to 300 K. Crystallographic snapshots of the polythreading framework at various temperatures reveal that, different from the intrinsic transverse vibrations of the subunits of metal-organic frameworks (MOFs) that experience NTE via a well-known hinging model, the remarkable NTE effect observed here is the result of a newly-proposed thermally induced relaxation process. During this process, an extreme spring-like contraction of the flexible CB8-based pseudorotaxane units, with an onset temperature of ∼260 K, follows a period of cumulative expansion. More interestingly, compared with MOFs that commonly have relatively strong coordination bonds, due to the difference in the structural flexibility and adaptivity of the weakly bonded U3(bcbpy)3(CB8) polythreading framework, U3(bcbpy)3(CB8) shows unique time-dependent structural dynamics related to the relaxation process, the first time this has been reported in NTE materials. This work provides a feasible pathway for exploring new NTE mechanisms by using tailored supramolecular host-guest complexes with high structural flexibility and has promise for the design of new kinds of functional metal-organic materials with controllable thermal responsive behaviour.

Study on Polypropylene Composites with High Thermal Conductivity and Its Preparation

Polypropylene (PP) composite materials were prepared through two molding methods of injection and compression molding, taking PP, FG as the matrix and thermal conductive filler. The effects of molding methods and FG content on the thermal conductivity of composite materials were studied, and the SEM, XRD, and thermal expansion properties of the materials were further analyzed. Results showed that thermal conductivity of the composite material increases with increasing of the FG content. When the FG content was 75 wt%, the average thermal conductivity of the composite materials prepared by injection molding and compression molding is 9.88 W·m-1·K-1 and 6.03 W·m-1·K-1, respectively. The axial thermal conductivity is 16.6 W·m-1·K-1 and 1.35 W·m-1·K-1, and the radial thermal conductivity is 5.88 W·m-1·K-1 and 26.9 W·m-1·K-1, respectively. In composite materials formed by injection molding, the flaky FG is mainly oriented vertically, while in compression molding, the flaky FG is mainly oriented horizontally.

Anisotropic thermal expansion of silicon monolayer in biphenylene network.

Materials with a negative thermal expansion property are of great importance in the emerging family of two-dimensional materials. For example, mixing two materials with negative and positive coefficients of thermal expansion avoids volume changing with temperature. In this work, based on first-principles calculations and Grüneisen's theory, we investigated the thermal expansion properties of a silicon monolayer in biphenylene networks. Our results show that the thermal expansion is greatly negative and anisotropic, as the linear thermal expansion coefficient along the a-direction is significantly smaller than the one along the b-direction, even at high temperatures. At 300 K, the thermal expansion coefficients along the two lattice directions are -17.010 × 10-6 K-1 and -2.907 × 10-6 K-1, respectively. By analyzing the Grüneisen parameters and the elastic compliance, we obtained an understanding of the giant negative thermal expansion of the material. Rigid unit modes are also responsible for the negative thermal expansion behavior. Our work provides fundamental insights into the thermal expansion of silicon monolayer in biphenylene networks and should stimulate the further exploration of the possible thermoelectric and thermal management applications of the material.

Tuning of thermal expansion properties of a mixed-ligand MOF by ligand variation

Thermal expansion property of a mixed-ligand MOF was tuned by replacing the pyrazine (Pz) ligand with bipyridine (Bpy).

Kazhdan constants and isomorphic graph pairs

Let G be a finite group, and let Γ be a subset of G. The Kazhdan constant of the pair (G,Γ) is defined to bethe maximum distance we can guarantee that an arbitrary unitvector in an arbitrary nontrivial irreducible unitary representation space of G can be moved by some element of Γ. The Kazhdanconstant relates to the expansion properties of the Cayley graph generated by G and Γ, and has been much studied in this context. Different pairs (G1,Γ1) and (G2,Γ2) may give rise to isomorphic Cayley graphs. In this paper, we investigate the question: To whatextent is the Kazhdan constant a graph invariant? In other words, if the pairs yield isomorphic Cayley graphs, must the corresponding Kazhdan constants be equal? In our main theorem, we constructan infinite family of such pairs where the Kazhdan constants areunequal. Other relevant results are presented as well.

Crystal orientations of 1,3,5-triamino-2,4,6-trinitrobenzene-based polymer bonded explosives during the pressing process by neutron diffraction

Hot-pressed 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based polymer bonded explosives (PBX) will show significant anisotropic and irreversible expansion properties, resulting in both the deterioration of their performance and weapon reliability issues. The anisotropic mechanical and irreversible expansion characteristics of TATB-based PBX have shown to be closely related to the crystal orientation. In this work, the orientations of TATB crystals in PBX under different thermal–mechanical coupling loading conditions were studied by neutron diffraction measurement technology. The microstructures were observed by computed tomography (CT) and scanning electron microscopy (SEM), and the effects of hot pressing parameters (temperature and pressure) on the TATB crystal orientation were systematically analyzed. Combining the density and compression strength of the formed samples, the optimal hot pressing parameters were determined. The results showed that during the in-situ compression process, the TATB crystals would be reoriented. The rotation angle of the (002) plane was mainly concentrated within a 35° angle from the perpendicular pressing direction. After hot compaction, the rotation angle moved from 35° to 52°, and the orientation of the TATB crystals had obvious rebound phenomenon. The (002) plane orientation degree was related to the deformation, fragmentation, and reorientation of the TATB crystals, as well as the phase transition, thermal softening, and gap filling of the binder, and the interfacial interactions. In order to obtain higher detonation energy, better mechanical properties and better shape stability of the formed samples, (120 °C, 140 MPa) was selected as the optimal hot pressing parameters for TATB-based PBX. • Neutron diffraction was developed for the TATB crystal orientation measurement. • The TATB crystal reorientation during pressing process was obtained. • The effect of the temperature and pressure on the reorientation was quantified. • The mechanism of the crystal reorientation during pressing process was analyzed.

Mechanical Properties of Rubberized Concrete and Its Application in Green Buildings

Global warming has become an increasingly pressing issue today due to excessive carbon emissions. The application of rubberized concrete material provides a new method for the disposal of waste rubberized tires. In terms of mechanical properties, rubberized concrete has poorer compressive strength, weaker splitting and tensile strength, but higher toughness and deformation capacity than ordinary concrete. In this paper, some of the properties of rubberized concrete are verified through finite element analysis. In terms of thermal performance, by synthesizing relevant literature, it is concluded that rubberized concrete has lower thermal conductivity and less thermal expansion than the traditional one. In terms of applications in green buildings, rubberized concrete materials are superior in thermal and acoustic insulation and have vibration damping effects, yet the peak performance is low. The research on the mechanical properties, thermal conductivity, thermal expansion, and acoustic and thermal insulation properties of rubberized concrete will provide a broader vision for rubber concrete to become a new sustainable construction material.

Magneto-volume effect in Fe n Ti13–n clusters during thermal expansion

Ab initio molecular dynamics calculations have been carried out to search for the ground state structure of Fe n Ti13–n clusters and measure the thermal expansion of Fe n Ti13–n . The volume of Fe n Ti13–n clusters during thermal expansion is jointly determined by anharmonic interaction and magneto-volume effect. It has been found that Fe6Ti7, Fe9Ti4, Fe11Ti2, and Fe13 clusters can exhibit the remarkable magneto-volume effect with abnormal volume behaviors and magnetic moment behaviors during thermal expansion. A prerequisite for the magneto-volume effect of Fe n Ti13–n clusters during thermal expansion has been revealed and the magnitude of the magneto-volume is also approximately determined. Furthermore, the magneto-volume behaviors of Fe n Ti13–n clusters are qualitatively characterized by the energy contour map. Our results shed light on the mechanism of the magneto-volume effect in Fe n Ti13–n clusters during thermal expansion, which can guide the design of nanomaterials with zero expansion or even controllable expansion properties.