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Transfer Learning across Material Properties Using Center-Environment Features: From Energetics to Mechanical Properties in Multicomponent Mo Alloys.

Transfer learning (TL) provides a viable approach to mitigate data scarcity in materials informatics. While conventional TL focuses on predicting identical properties across different systems, this work demonstrates a cross-property extension of TL from energy to mechanical properties via end-to-end model weight pre-training and fine-tuning: knowledge learned from predicting substitution energies is transferred to predict distinctly different mechanical properties, substantially improving computational efficiency given the typically higher cost of acquiring target-domain data. To accelerate computational alloy design, machine learning models using center-environment (CE) features were first developed to predict substitution energies of alloying elements in molybdenum (Mo)-based alloys. The Random Forest models achieved the optimal performance and transferability-R2 = 0.97, 〈MAE〉 = 0.11 eV, and 〈RMSE〉 = 0.16 eV-against the density functional theory (DFT) benchmark. The model dependency of feature selection and importance analysis was discussed. The transferability of the energy models was validated on unknown systems with new elements. Subsequently, the energy models were fine-tuned using limited mechanical property data to construct energy-to-property (E2P) TL models capable of predicting elastic properties, including bulk modulus, Young's modulus, shear modulus, and elastic constants, achieving an improved accuracy over the non-transferred ML by ∼10-30%, with its transferability verified by additional DFT calculations. This cross-property E2P transfer learning framework opens a new avenue for accelerating computational materials discovery and may be extended to other multiproperty predictions governed by similar physical principles.

center-environment feature

The properties of the extraocular muscles of the frog. I. Mechanical properties of the isolated superior oblique and superior rectus muscles.

The mechanical properties of two extraocular muscles (superior oblique and superior rectus muscles) of the frog were studied and compared with those of a frog's skeletal muscle (iliofibularis muscle) which contains the same types of muscle fibres as the oculorotatory muscles. The extraocular muscles are very fast twitching muscles. They exhibit a smaller contraction time, a smaller half-relaxation time, a higher fusion frequency, and a lower twitch-tetanus ratio than the skeletal muscles. The maximum isometric tetanic tension produced per unit cross-sectional area is lower in the extraocular muscles than in skeletal muscles. However, the extraocular muscles show a higher fatigue resistance than the skeletal muscles. With respect to the dynamic properties there are some differences between the various oculorotatory muscles of the frog. The superior rectus muscle exhibits a faster time-course of the contraction, a higher fusion frequency, and a higher fatigability than the superior oblique muscle. An increase of the extracellular K+-concentration evokes sustained contractures not only in the extraocular muscles but also in the iliofibularis muscle; between these muscles there are no striking differences in the mechanical threshold of the whole muscle preparation. The mechanical threshold depends on the Ca++-concentration of the bathing solution and it is found in a range between 12.5 and 17.5 mM K+ in a normal Ringer solution containing 1.8 mM Ca++. The static-mechanical properties of the extraocular muscles of the frog and the dependence of the active developed tension on the muscle extension are very similar to those which are known to exist in the extraocular muscles of other vertebrates. In tetanic activated frog's oculorotatory muscles a linear relationship exists between length and tension. A variation of the stimulation frequency does not change the slope of this curve but causes parallel shifts of the curve. The peculiar properties of the extraocular muscles of the frog are discussed with respect to the muscle fibre types in these muscles and to the diameter of the muscle fibres.

Animals

Age-related changes in the mechanical properties of human skin.

The mechanical properties of skin have been studied both in vivo and in vitro by a variety of test methods. These properties are well matched to the function of the skin, and they depend on the geometry of the collagen and elastin networks of the dermis. The time dependence of these properties is thought to be related to the "ground substance" components of the dermis. Age-related changes in the mechanical properties are a function of the degradation of the elastin network and of some as yet undefined changes in the viscoelastic properties of the "ground substance."

Adult

[Effect of cross-linking agents on mechanical properties of a fluid resin (author's transl)].

Effect of several cross-linking agents added to MMA on the mechanical properties of self-cured fluid resins was studied. The cross-linking agents were 2,2-bis (4-methacryloxyethoxyphenyl) propane, trimethylolpropane trimethacrylate, neopentylglycol dimethacrylate, hexamethyleneglycol dimethacrylate and 1,2-polybutadiene. Their concentrations in MMA were 1,3,5 and 10 wt%. Measured mechanical properties were Brinell hardness, tensile strength, impact strength and transverse strength. The best composition was 5% neopentylglycol dimethacrylate in MMA among studied samples. Microscopic observation of the surface after tensile test suggested that diffusibility of cross-linking agents into PMMA powder affected the mechanical properties. Mechanical properties of both matrix and powder, and their adhesion at the interface had influence upon the mechanical properties of resins processed by powder-liquid method.

Acrylates

[Aging effect on mechanical properties in fluid resin. (Part 1). Affection of residual monomer (author's transl)].

Aging effect on the mechanical properties in fluid resins was pointed out, but little was studied on this point. Relationship between amount of residual monomer in the samples prepared by fluid resin and the mechanical properties, brinell hardness, tensile strength, were studied. Test pieces just as polymerized in the size were used. Weights of specimens kept at three different circumstances, in the air at 20 degrees C, in a water bath at 37 degrees C and in a desiccator at 11 mmHg and 40 degrees C, was checked at the prescribed time to clarify the amount of residual monomer and the mechanical properties were measured at the same time. Amount of weight loss, due to evaporation of MMA, must improve the mechanical properties. The improvement by postpolymerization could be neglected. Rate of the weight loss suggests that residual monomer must mainly be at the surface. Molecular weight of PMMA, 86.4 X 10(4) did not have any effect on the mechanical properties and on the evaporation rate of monomers from polymerized specimens. To improve the mechanical properties of fluid resin must be to decrease residual monomer as much as possible in the fluid resin especially at the surface area.

Acrylic Resins

The time-dependent mechanical properties of skin.

The mechanical properties of the skin were investigated by applying a torsional deformation to a circumscribed area. Results of the tests indicate that the skin is nonlinear and time dependent. The dynamic response shows that the phase angle is insensitive to frequency below 1 Hz; the peak torque amplitude increases slowly above 0.004 Hz. A self-consistent description is presented utilizing continuous relaxation spectra. The technique describes the stress relaxation data and predicts the form of the dynamic response.

Biomechanical Phenomena

Evaluation of alternative alloys to precious ceramic alloys. 1. Mechanical properties.

In the first part of this study, the microstructures and the mechanical properties of precious, semi-precious, and nonprecious dental casting alloys for the porcelain-baked-to-metal technique have been determined. The semi-precious alloys contained only 50% gold, and palladium, silver, and some base metals. The nonprecious alloys were of the nickel-chromium type. Discs and miniaturized tensile bars have been cast and tested either in the as cast condition, or after a simulation of the various porcelain bakes. Proof stress, ultimate tensile strength, elongation, and plastic stiffness have been measured and results compared by use of analyses of variance. The microstructure examination shows that the simulation of the porcelain bakes improves the homogeneity of the precious and semi-precious alloys. Simultaneously, the mechanical properties of the same alloys are also improved. One semi-precious alloy, still under development at the time of these tests, has its mechanical characteristics markedly downgraded by the thermal treatments. The nickel-chromium alloys exhibit the best range of mechanical properties for the porcelain-baked-to-metal technique, when considering the three most relevant properties: proof stress, plastic stiffness, and modulus of elasticity.

Chemical Phenomena

The mechanical properties of bone cements.

The mechanical properties of a number of commercially available bone cements have been investigated. Tests were carried out on specimens in compression, in bending and in tension. Using the compression test as a standard, the effects of the following variables were studied: the addition of antibiotics, strain rate, environmental temperature, and age. It was concluded that age, temperature and rate of straining have a marked effect on the strength of the cement, while the addition of small quantities of antibiotics only marginally weakens the cement.

Anti-Bacterial Agents

Thermally induced time dependence of mechanical properties in biomedical grade polyurethanes.

The time dependence of the mechanical properties of segmented urethanes as well as urethane-urea systems were monitored after the materials had been given a short thermal treatment followed by rapid cooling. Both linear and crosslinked materials were studied but the major focus was on many of the common biomedical grade urethanes. As had been noted in earlier studies on nonmedical segmented urethanes from this laboratory, many of the biomedical grade materials also showed time-dependent changes in mechanical properties that can be directly related to time-dependent changes in the degree of domain structure (microphase separation) that may occur in these segmented copolymers. Interestingly, those systems possessing significant amounts of urea linkage show little or no significant time-dependent changes in structure or properties following thermal treatment. The effect of chemical cross-linking can also influence the domain formation process and its thermal stability. The ramifications of these time dependent effects may have bearing on the biomaterial applications of segmented urethane polymers.

Adhesiveness

Membrane mechanical properties of ATP-depleted human erythrocytes.

Although the relations between the metabolic state and the mechanical properties of human red blood cells (RBC) continue to be of current interest, literature reports in this area are not in agreement. The present investigation was designed to determine several intrinsic mechanical properties of human RBC membranes before and after metabolic depletion via incubation at 37 degrees C for 24 hr. Using micropipette and flow channel techniques, three properties were measured: (1) mu, surface shear modulus of elasticity; (2) K, elastic area compressibility modulus; (3) etap, shear viscosity in the plastic domain. Our results indicate no significant differences in these parameters between fresh and ATP-depleted human RBC membranes. These present data are thus in disagreement with other literature reports indicating large changes in membrane mechanical properties consequent to metabolic depletion. A brief discussion of the possible reasons for this disagreement is presented.

Adenosine Triphosphate

Mechanical properties of smooth muscle cells in the walls of arterial resistance vessels.

1. Methods have been developed for measuring the dynamic mechanical response of arterial resistance vessels (i.d. 83--235 micrometer) with a time resolution of about 4 msec. 2. Observations of the microscope image of the smooth muscle cells in the walls of these vessels indicate that there is little intercellular compliance in this preparation, and that the mechanical properties of the activated preparation are a reflexion of the mechanical properties of the individual smooth muscle cells. 3. Under isometric conditions the force developed per unit cell area was about 350 mN/mm2. Under isotonic conditions the cells had a maximum velocity for shortening at 37 degrees C of about 0.17 lengths/sec. 4. Quick releases of activated vessels indicate that the instantaneous elastic characteristic of smooth muscle cells is approximately exponential. 5. The wall tension response to small (0.3%) square wave changes in circumference was proportional to the logarithm of the time following the start of each circumference change. 6. Active wall tension, deltaT, was varied by varying the Ca2+ concentration of the activating solution. Under these conditions the active dynamic stiffness, k, was proportional to deltaT, and was not temperature dependent. The active half response time, tau (the time, taken to recover half the tension change caused by a small change in circumference) was also proportional to deltaT, but here the constant of proportionality had a Q10 of about 1.8. 7. It is concluded that the quick release response and the square wave response are in part a function of the mechanical properties of the crossbridges between the contractile filaments. Calculations show that both these responses can be explained if it is assumed that there is a relatively compliant passive component in series with the crossbridges.

Animals

Mechanical properties of basilar membrane.

A fresh basilar membrane has different mechanical properties in the radial and in the longitudinal directions. When pressure with a needle is exerted on the basilar membrane, a narrow radially oriented strip is deflected. The form of the deflection can be deduced from the pathological consequences of the acoustic trauma as well. The observed anisotrophy is a property of the vital membrane and is disturbed by chemical and physical influences and is lost post mortem. The post-mortem changes can explain the results obtained by von Békésy which differ from ours. The physiological meaning of the mechanical properties of the basilar membrane is discussed here.

Animals

The mechanical properties of the abdominal cuticle of Rhodnius larvae.

1. The mechanical properties of loops of cuticle cut from the abdomens of 5th instar Rhodnius have been investigated. The cuticle shows pronounced viscoelastic behaviour. 2. Stress-relaxation tests show a continuously falling modulus over a wide range of times after the imposition of a strain. 3. Plasticized samples of cuticle show stress-relaxation curves which are shifted along the time axis towards earlier times by up to times 10-3. The modulus at any particular time after the imposition of strain is about 10 times lower than that of the unplasticized cuticle. 4. It is concluded that the mechanical properties of this cuticle are determined, at least for maintained stresses, largely by the matrix material. Chitin microfibrils may act as a reinforcing filler for short-term, rapid stresses. The cuticular macromolecules are probably not extensively cross-linked by primary bonds, though secondary interactions between them are probably important in the viscoelastic properties of the cuticle. 5. Plasticization probably involves a change in either the number or the strength of secondary interactions between the cuticle macromolecules, or both.

Abdominal Muscles

The effects of ultrasound on the mechanical properties of rat cardiac muscle.

The mechanical properties of cardiac muscle during ultrasonic irradiation have been studied in vitro. Left anterior papillary muscle from normal rats was suspended in buffered lactated Ringers solution equilibrated with 95% O2, and 5% CO2 and maintained at 20 degrees C. The muscles were stimulated to contract isometrically three times per minute at the length which produced maximum tension. Each muscle was irradiated with a MHz ultrasound at an average power of 2.4 Wcm-2 for a period of 10 min with a 10 min recovery period. Irradiation caused an average increase in temperature of the muscle of 1.7 +/- 0.2 degrees C (mean +/- SEM). Irradiation caused the resting tension (1.46 +/- 0.13g) to decrease by 17.8 +/- 4.7% and the developed tension (3.33 +/- 0.61g) to decrease by 4.1 +/- 0.9%. Since changes in contractile properties have been reported with temperature the bath temperature was raised and changes in contraction observed. When compensated for effects of temperature, the changes in resting tension became - 13.3 +/- 4.1% while the change in developed tension became + 1.6 +/- 2.3%. The change in resting tension is highly significant (p less than 0.05 paired t-test) while the change in developed tension is not. Thus 1 MHz ultrasound at an intensity of 2.4 Wcm-2 appears to affect resting tension of cardiac muscle without affecting the active tension. Since changes in cardiac mechanics of this type have not been described previously the effects of ultrasound appears to be unique.

Animals

Mechanical properties of the mammalian vas deferens. I. In the passive state.

Knowledge of the mechanical properties of the vas deferens is important in order to understand the mechanical interaction between an intravasal device (IVD) and the vas deferens--a necessary step for successful long-term implantation. It is equally important in order to understand the mechanism of sperm transport through the vas, with or without an IVD implant, by means of quantitative mechanical models. Experiments were performed, in vitro, on vas deferens from rat, bull, and rabbit, to determine its mechanical properties in the passive state. The data consist of (1) load response to simple extension and cyclic extension, (2) extensional response to cyclic loading, and (3) stress relaxation response at constant extensions. The load-elongation behavior is characterized by Fung's exponential model T = (T* + beta)e alpha(lambda-lambda*) - beta quantitatively, where T is the Lagrangian or engineering stress (current force in the specimen divided by the original area of cross section) (dyn/cm2), T* is a convenient stress value (dyn/cm2), alpha is a parameter characterizing material elasticity (dimensionless), beta is a second material parameter (dyn/cm2), lambda is a stretch ratio (dimensionless) equal to l/l0, where l is the instantaneous length of the specimen (cm) and l0 is its reference length measured at 2-gram-force (1 gram force = 981 dyn) applied load (cm), and lambda* is the stretch level corresponding to T* (dimensionless). The vas appears to behave as a viscoelastic material and its reduced relaxation function may be dependent on the initial level of stretch. The cyclic-loading and cyclic-extension data give evidence of internal damping mechanisms, which make the loading curves different from the unloading curves (hysteresis). Also, the mechanical behavior of the vas is found to be altered by repeated loadings in quick succession. It is likely that cyclic loadings, in vivo, occur at much lower levels of stress and thus cause negligible damage, or that there are natural mechanisms which repair the damage. The behavior of tissue from different species of animals are qualitatively similar, although the tissue from the larger-size animal is likely to be stronger and stiffer. Due to very little interweaving between the muscle fibers of the longitudinal and circumferential layers, the data reported reflect the properties of the longitudinal layers only. Because the muscular structure of the three layers is very similar, the properties of the circumferential layer may be extrapolated.

Animals

Effect of beta-aminopropionitrile on bone mechanical properties.

In vivo beta-aminopropionitrile treatment caused significant changes in the mechanical properties of rat femora. In femora treated with beta-aminopropinitrile as compared with controls, there was a 44 per cent decrease in bone stiffness and a 47 per cent increase in bone deformation to failure. Bone ash was decreased 5 per cent in the treated group. It is likely that the decrease in bone ash was secondary to impaired intermolecular bone-collagen cross-linking, which is a well established consequence of treatment with beta-aminopropionitrile. Thus, beta-aminopropionitrile influences bone mechanical properties directly by impairing collagen cross-linking and indirectly by altering bone-matrix mineralization.

Aminopropionitrile

The mechanical properties of prematurely and non--prematurely ruptured membranes. Methods and preliminary results.

The mechanical properties of the chorioamniotic membranes have been studied by several investigators over the past 100 years. No relationship between membrane strength, as measured by rupture tension, and premature or non-premature rupture of the membranes has been demonstrable. In the present study, several measures of the mechanical properties of the chorioamniotic membranes were examined. These included thickness, rupture tension, work to rupture, strain to rupture, and moduli of elasticity (Young). Prematurely and non-prematurely ruptured membranes differed with respect to thickness near the rupture site and Young's modulus near the placenta. Differences between the groups for the other parameters were not significant. This study suggests that there may be inherent differences between membranes which rupture prematurely and those which do not.

Biomechanical Phenomena