Strain Ratio Research Articles

Responses of osteoblasts under varied tensile stress types induced by stretching basement materials

ABSTRACT Osteoblasts are mechanosensitive cells. Tensile stress with different conditions, including loading time, frequency, magnitude, etc. would cause varied responses in osteoblasts. However, it was not clarified that the effect of the loading types on the osteoblasts. In this study, we focused on the effect of varied tensile stress types on osteoblasts, including isotropic stretch, biaxial stretch, and uniaxial stretch with the negative ratio of transverse strain to axial strain (NR) −1, 0, and 0.2 respectively. Cell proliferation was determined to be most efficient when stimulated by 6% strain at a frequency of 1 Hz and a negative value of 0 for 1 h/day. The varied strain resulted in a thickening of the F-actin cytoskeleton and a thinning of the nucleus. Nuclear flattening caused Yes-associated protein (YAP) to be transported to the nucleus. It was suggested that the influence of loading types on the mechanobiology responses must be noticed. The mechanism of cell mechanical sensitivity under varied loading types was explored, which would provide good suggestions for designing microstructures to control deformation patterns in bone tissue engineering.

Minimally invasive correction of stress urinary incontinence in women with pelvic floor dysfunction

BACKGROUND: Pelvic floor dysfunction is widespread among young women. Stress urinary incontinence is a common manifestation of the dysfunction and, even in mild forms, affects the quality of life of patients. Much attention is focused on finding and improving minimally invasive methods for treating stress urinary incontinence in women of reproductive and perimenopausal age to prevent disease progression and improve quality of life.
 AIM: The aim of this study was to evaluate the immediate and long-term results of paraurethral injections of a high-density hyaluronic biopolymer for the correction of stress urinary incontinence in women of reproductive and perimenopausal age.
 MATERIALS AND METHODS: We examined 37 patients aged 44.6 ± 4.7 years with mild to moderate stress urinary incontinence combined with grade I to II genital prolapse. After general clinical and special studies (urination diaries, King’s and Pelvic Organ Prolapse / Urinary Incontinence Sexual Questionnaire, cough test, complex urodynamic study, ultrasound examination of the urethrovesical junction and pelvic floor ultrasound with compression elastography), paraurethral injection of 4.0 ml of the high-density hyaluronic biopolymer crosslinked with 1,4-butanediol diglycidyl ether was performed. The effectiveness of therapy was evaluated 1, 6 and 12 months after the procedure.
 RESULTS: A negative cough test was detected after one, six and 12 months of follow-up in 96.9, 73.1 and 43.8 % of women, respectively; the absence of stress urinary incontinence episodes according to urination diaries was in 85.7, 61.3 and 35.0 % of patients, respectively. Gradual resorption of the drug was monitored over 12 months of observation. An ultrasound examination showed a decrease in urethral mobility one month after the procedure. According to the results of elastography before treatment, the average value of the strain ratio of paraurethral tissues was 0.50 (0.30–0.69) (p 0.001), after one and six months — 0.88 (0.76–1.03) and 0.79 (0.66–1.07) (p 0.001 and p = 0.005 respectively). Thus, the stiffness of the paraurethral tissues of the proximal posterior wall of the urethra increased within six months after the procedure. When observing women after 12 months, the stiffness values of the studied tissues decreased and approached the values before treatment. During the entire observation period, the patients noted a decrease in the degree of discomfort due to problems with urination according to the questionnaires.
 CONCLUSIONS: The introduction of the high-density hyaluronic biopolymer helps to increase the stiffness of paraurethral tissues and improve the structural support of the urethra in patients with stress urinary incontinence. After the procedure, a 12-month follow-up revealed a decrease or absence of stress urinary incontinence episodes according to urination diaries and the preservation of the positive effect of treatment according to the results of the cough test. A gradual decrease in the effect of therapy is associated with biodegradation of the drug. This method of treating mild forms of stress urinary incontinence is effective for women of reproductive and perimenopausal age who do not plan surgical treatment, are interested in achieving a quick result of therapy and are informed that the effect decreases over time after the procedure.

Diagnostic efficacy of high-frequency Grey-scale ultrasonography and Sono-elastography in grading the severity of carpal tunnel syndrome in comparison to nerve conduction studies.

To correlate the cross-sectional area (CSA) and elasticity of the median nerve (MN) measured at carpal tunnel inlet between healthy controls and various degrees of carpal tunnel syndrome (CTS) graded as per nerve conduction studies (NCS). A total of 53 patients (with 81 wrists) presenting with clinical symptoms characteristic of CTS, having their diagnosis confirmed and severity graded by NCS, and 48 healthy controls (with 96 wrists) were included in the study. All the study participants underwent wrist ultrasound which included initial Grey-scale USG followed by strain and shear wave elastography. The CSA and elasticity (in terms of strain ratio and shear modulus) of MN were measured at the carpal tunnel inlet. Statistical analysis was performed using the Mann-Whitney U test to compare between the two groups and for subgroup analysis of cases. The diagnostic performance of each variable was evaluated using the receiver operating characteristic curves. The mean CSA was 9.20 ± 1.64, 11.48 ± 1.05, 14.83 ± 1.19 and 19.87 ± 2.68 mm2, the mean shear modulus was 17.93 ± 2.81, 23.59 ± 2.63, 32.99 ± 4.14 and 54.26 ± 9.24kPa and the mean strain ratio was 5.26 ± 0.68, 5.56 ± 0.70, 7.03 ± 0.47 and 8.81 ± 0.94 in control, mild, moderate and severe grades of CTS, respectively (p < 0.001). The combined utility of Grey-scale USG and Elastography may serve as a painless and cost-effective alternative to NCS in grading the severity of CTS.

The strain ratio-dependent multiaxial low cycle fatigue behaviour and life prediction of 316L stainless steel based on critical plane at elevated temperature

The study mainly investigates the effect of strain ratio on the multiaxial low cycle fatigue behaviour of 316L at 550 °C. The evolution of both axial and torsional stress amplitude is observed to go through three stages: cyclic hardening, softening and fracture. What's different is that the torsional loading experiences fewer cyclic hardening cycles compared to the axial loading. Regarding the interaction between axial and torsional stresses, it is observed that as the torsional strain increases, the axial deformation response presents a lower peak stress and a higher softening rate, while the torsional peak stress and softening rate hardly changes with the increase of axial strain amplitude. The fracture pattern is obtained through three-dimensional (3D) depth-of-field observation. It is discovered that as the strain ratio increases, the fracture pattern transits from tensile failure mode to shear failure mode. Furthermore, the orientation angle of the fracture surface increases and lies between the critical plane angle of maximum shear strain and maximum normal strain, indicating a mixed failure mode. Additionally, a comparison of nine representative critical plane models reveals that the energy-based models can better predict the multiaxial fatigue life influenced by the strain ratio. Finally, based on the analysis of deformation and failure mechanisms, a normal damage parameter weakening factor (NDWF) is introduced into the KBM-R model, and an improved normal stress component (INSC) is introduced into the Wu-R model. The two modified models well capture the impact of strain ratio and accurately predict the multiaxial fatigue life of both 316L and P92 steel.

Experimental Research on Anisotropy Characteristics of Shale under Triaxial Incremental Cyclic Loading and Unloading

Shale is a common rock type that is associated with underground engineering projects, and several important factors, such as bedding structure, confining pressure, and the loading and unloading path, significantly influence the anisotropy of shale. Triaxial monotonic loading tests and triaxial incremental cyclic loading and unloading tests of shale under three kinds of confining pressures and five types of bedding inclination angles (θ) were thus performed to investigate the anisotropy of shale in terms of mechanical behavior, acoustic emission (AE), and energy evolution, and reveal the mechanism by which shale anisotropy is weakened. The results show that (1) the compressive strength and elastic modulus of shale decrease and then increase as the θ increases, and that both σ3 and incremental cyclic loading and unloading reduce the anisotropy in terms of the compressive strength and elastic modulus of shale, with the ratio of plastic strain to total strain reaching its maximum at a θ of 60° during each loading and unloading cycle. (2) The failure modes of shale with θ of 0°, 30°, and 90° under triaxial monotonic loading are similar to the counterparts under triaxial incremental cyclic loading and unloading, while the failure modes of shale with θ of 45° and 60° differ significantly under the two loading conditions, and interestingly, the degree to which the bedding plane participates in shale crack evolution under incremental cyclic loading and unloading is considerably lower than that under triaxial monotonic loading. (3) The cumulative AE count and AE b-value of shale first decrease and then increase as the θ increases, while the Felicity ratio decreases as the number of cycles increases. (4) As the θ increases, the total energy density U0 and the parameter m, which reflects the accumulation rate of elastic energy, first decrease and then increase, with both reaching a minimum at a θ of 60°. (5) The mode by which cyclic loading and unloading leads to failure in shale with a θ of 60° is similar to that at a θ of 0° and is the main mechanism by which shale anisotropy weakening occurs as a result of cyclic loading and unloading. The results provide experimental support and a theoretical basis for safer and more efficient underground engineering projects that involve shale.

Does Postlong Coronavirus 2019 Disease Affect Renal Stiffness without any Chronic Systemic Disorders?

In the last few years, coronavirus disease 2019 (COVID-19) has changed human lifestyle, behavior, and perception of life. This disease is caused by severe acute respiratory syndrome coronavirus 2 (SARS-COV-2). In the literature, there are limited studies about the late renal effects of COVID-19 that reflect the systemic involvement of this disease. In the present study, we aimed to compare sonoelastographic changes in both kidneys between patients who had totally recovered from COVID-19 and healthy individuals using strain wave elastography (SWE). This study was conducted between June 2021 and May 2022 in Kahramanmaraş City Hospital Department of Radiology. File and archive records were retrospectively evaluated. Basic demographic, laboratory, and renal ultrasonography (USG) and sonoelastographic findings were screened and noted. Two groups were defined to compare sonoelastographic findings. Post-long COVID-19 group had 92 post-long COVID-19 patients, and the comparator group had 9 healthy individuals". Both groups' demographic, laboratory, and ultrasound-elastographic findings were assessed. The post-long COVID-19 group had a higher renal elastographic value than the comparator group (1.52 [0.77-2.3] vs. 0.96 [0.54-1.54], p<0.001). There were no statistically significant differences between the two groups in terms of age (p=0.063), gender (p=0.654), or body mass index (BMI) (p=0.725), however, there was a significant difference observed between the two groups in the renal strain ratio (RSR). According to an ROC analysis, an RSR cutoff of >1.66 predicted post-long COVID-19 with 44.9% sensitivity and 81.9% specificity. (AUC=0.655, p<0.001). A separate ROC analysis was performed to predict post-long COVID-19 with a BMI cutoff of <33.52, kg/m2 sensitivity of 92.4% and specificity of 17% (AUC=0.655, p<0.001). We demonstrated that renal parenchymal stiffness increases with SWE in post-long COVID-19 patients.

Threshold and structure of HCP/FCC nucleation in BCC iron under arbitrary triaxial compression: Atomistic simulations

Shear deformation is one of the primary factors determining the threshold of structural transition (ST). It is important to quantitatively express the relationship between shear deformation and the ST threshold for the in-depth development of ST dynamics models. This work used classical molecular dynamics methods to study the effect of shear deformation on the ST in iron by controlling the triaxial ratio of compression. Based on the simulation results, there are significant differences in the microstructure for different loading paths. HCP lamellar twins, HCP-FCC thin twins, and crossed HCP twins embedded with parallel hexahedral FCC grains were all observed, as uniaxial loading transitions to equiaxial loading. The changes in pressure and the softening range of shear stress under different triaxial compressions were revealed. By introducing the strain triaxiality (i.e., the ratio of shear strain to volumetric strain), a general expression of the pressure threshold of ST under high strain rate compression-shear was proposed. In addition, whether the close-packed plane is easily activated under different strain environments was explained based on the results of stacking fault energy.

Estimating accurate and precise strain in low-magnitude penetratively deformed rocks: Integrating forward strain modeling and natural data

Estimating grain-scale strain using commonly used strain methods from a low-magnitude penetratively deformed rock is typically fraught with uncertainties as the measured strain is influenced by the pre-deformed grain shapes and grain-scale strain partitioning. Therefore, developing kinematic and mechanical models of orogenic wedge evolution based on such strain data can be misleading without knowing how accurate and precise those data are. To determine accuracy we created five 2-D synthetic rock images and deformed them with known strain under pure shear, simple shear, and general shear. We generated 4160 strain ratio (Rs) and long-axis orientation (φ) data. To determine precision we calculated 2σ (95%) uncertainties in Rs and φ from 102 quartz-rich rocks in Sikkim and generated 977 uncertainty data. Results show that the shape matrix eigenvector and stereographic projection methods record the lowest root mean square error, mean absolute error, and 2σ uncertainty values suggesting they are the most accurate and precise, regardless of strain ratio and deformation types. However, the accuracy and precision of φ deteriorate at Rs < 1.5. For most accurate and precise results, using the above mentioned methods, we recommend a minimum of 100 and 75 markers for Rs < 1.5 and Rs > 1.5, respectively.

Suppressed Plastic Anisotropy via Sigma-Phase Precipitation in CoCrFeMnNi High-Entropy Alloys.

The effect of sigma-phase precipitation on plastic anisotropy of the equiatomic CoCrFeMnNi high-entropy alloy was investigated. Annealing at 700 °C after cold-rolling leads to the formation of the Cr-rich σ phase with a fraction of 2.7%. It is experimentally found that the planar anisotropy (∆r = -0.16) of the CoCrFeMnNi alloy annealed at 700 °C is two times lower than that of the alloy annealed at 800 °C (∆r = -0.35). This observation was further supported by measuring the earing profile of cup specimens after the deep drawing process. The plastic strain ratio, normal anisotropy, and planar anisotropy were also predicted using the visco-plastic self-consistent model. The results indirectly indicated that the reduction of plastic anisotropy in alloy annealed at 700 °C can be attributed to the formation of the σ phase.

Evaluation of Usability and Efficacy of Strain Elastography Method Concurrently with Preoperative Ultrasonography in Cases of Hydatid Cyst

Abstract Background: Hydatid cysts (HCs), which are among the cystic lesions of the liver, are frequently encountered in endemic areas. Routine imaging modalities are sometimes insufficient to differentiate HC types, and ultrasound (US) elastography has just begun to be used for this purpose. In this study, the effectiveness of the strain elastography (SE) method in preoperative HC cases was investigated, and the relationship between HC types and elastography values was evaluated. Methods: HC cases that underwent SE simultaneously with preoperative US between January 2019 and February 2021 were evaluated retrospectively, and 75 cases were included in the study. In addition to elastography data, cyst typing according to the World Health Organization (WHO) classification was also available. Results: Thirty cases were male and 45 cases were female, the median age was 48 years, and the interquartile range was 41 years. According to the WHO classification, 15 cases were Type I, 27 cases were Type II, and 33 cases were Type III HC. Median strain ratio (SR) values were 5.69 (4.07–14.47) for Type I, median 1.49 (1.26–1.74) for Type II, and median 0.21 (0.13–0.30) for Type III, and there was a highly significant relationship between HC types and SR values (P &lt; 0.001). There was also a very strong (-) directional correlation between HC type and strain rate (P &lt; 0.001, Spemann rho (ρ): −0.928). Conclusion: US elastography is a new modality in the diagnosis of HC types, and there are few studies available. In this study, unlike the literature, it is the first time that HC typing and discrimination have been used using the SE technique, which is remarkable.

Role of microfibril angle in molecular deformation of cellulose fibrils in Pinus massoniana compression wood and opposite wood studied by in-situ WAXS

Upon tensile stress, the spiral cellulose fibrils in wood cell walls rotate like springs with decreasing microfibril angle (MFA), and the cellulose molecules elongate in the chain direction. Compression wood with high MFA and opposite wood with low MFA were comparatively studied by in-situ tensile tests combined with synchrotron radiation WAXS in the present study. FTIR spectroscopy revealed that compression wood had a higher lignin content and fewer acetyl groups. For both types of wood, the lattice spacing d004 increased and the MFA decreased gradually with the increase of tensile stress. At stresses beyond the yield point, cellulose lattice strain depended linearly on macroscopic stress, while the MFA depended linearly on macroscopic strain. The deformation mechanisms of compression wood and opposite wood are not essentially different but differ in their deformation behavior. Specifically, the contribution ratio of lattice strain and cellulose fibril reorientation to macroscopic strain was 0.25 and 0.53 for compression wood, and 0.40 and 0.33 for opposite wood, respectively. Due to the geometric effects of MFA, a greater contribution of cellulose fibril reorientation to the macroscopic deformation was detected in compression wood than in opposite wood.

Mechanics-perspective evaluation of self-sensing geopolymer coatings in structural health monitoring

Self-sensing cementitious coatings are a promising alternative in structural health monitoring due to their high sensing performance and simple production and deployment. The sensing behavior of coatings though differs compared to conventional self-sensing materials due to the interface between the coating and substrate. In this study, the bonding and sensing performance of geopolymer coatings under cyclic compression was investigated by employing four surface treatments – untreated, chipping, brooming, and chemical treatment. The coatings' splitting tensile bond strength ranged between 3.52 MPa and 6.54 MPa. The strain ratio between the coatings and substrates was between 0.62 and 0.67 and the gauge factor was found between 29 and 34. A numerical analysis involving finite element models on the strain behavior of coatings and parametric studies on the coatings' elastic modulus and thickness was carried out. A bonding coefficient, that accounts for the coatings’ mechanical and geometric properties, was proposed to accurately determine the gauge factor.

Diagnostic performance of EUS-guided elastography for differential diagnosis of gallbladder polyp

It is difficult to differentiate between neoplastic and non-neoplastic gallbladder (GB) polyps before surgery. EUS-guided elastography (EUS-EG) is a noninvasive complementary diagnostic method. The utility of EUS-EG in the differential diagnosis of GB polyps has not been investigated. We investigated the diagnostic performance of EUS-EG for the differential diagnosis of GB polyps. Patients with GB polyps were prospectively enrolled from June 2020 until November 2022. EUS-EG and semiquantitative evaluation of the strain ratio (SR) were performed for differential diagnosis of GB polyps. Fifty-three eligible patients were divided into 2 groups based on the final diagnosis after surgery. Patient demographics, EUS characteristics, and SR values were compared. A receiver-operating characteristic curve analysis was performed to determine the optimal cutoff SR value that discriminates between neoplastic and non-neoplastic GB polyps. The median SR value for neoplastic polyps (32.93 [interquartile range {IQR}, 22.37-69.02]) was significantly higher than for non-neoplastic polyps (5.40 [IQR, 2.36-14.44], P< .001). Significant differences were found in SR values between non-neoplastic, benign neoplastic (23.38 [IQR, 13.62-39.04]), and malignant polyps (49.25 [IQR, 27.90-82.00]). The optimal cutoff SR value to differentiate between neoplastic and non-neoplastic polyps was 18.4. In multivariable logistic regression, SR value >18.4 (odds ratio, 33.604; 95% confidence interval, 2.588-436.292) was an independent predictor of neoplastic polyps. EUS-EG and SR values can be used as a supplementary method for evaluating GB polyps. (Clinical trial registration number: NCT04416763.).

Applicability of Kroon network theory for biaxial mechanics in rubber through multiscale approach

In this paper, we address the problem of the multiscale prediction of the multiaxial hyperelastic behavior of rubber. Our goal is to test the predictive capabilities of a hyperelastic model grounded in the principles of continuum mechanics, bridging the gap between continuum-level mechanics and molecular-level descriptions. This constitutive model posits that macroscopic behavior results from the non-affine deformation of the molecular network, influenced by topological constraints. We employ molecular dynamics methods to measure the mechanical behavior of a rubber network structure under various deformation modes. The study includes an analysis of the molecular network deformation during the straining process, shedding light on the deformation mechanisms at the molecular level. By examining how the total network stress in our specifically designed molecular structure responds to biaxial strain ratios, we are able to assess the effectiveness of the hyperelastic constitutive model.

Preliminary Study on the Evaluation of Liver Fibrosis Using Endoscopic Ultrasound Elastography and Transabdominal Ultrasound Transient Elastography Combined with Strain Ratio

Background: This study aimed to explore the effectiveness of endoscopic ultrasound elastography (EUS-EG) in evaluating liver fibrosis. Methods: The present study involved 11 patients with chronic liver disease who met study criteria and underwent EUS-EG, transabdominal ultrasound transient elastography (TUS-TE), and liver biopsy (LB) examinations at the same time. The Batts-Ludwig scoring system for liver fibrosis was used as the gold standard to analyze the correlation between the EUS-EG strain ratio (SR) and TUS-TE liver stiffness measurement with the pathological stage of liver fibrosis. The optimal cut-off value and area under the receiver operating characteristic curve (AUROC) of EUS-EG and TUS-TE for diagnosing liver fibrosis were calculated by drawing an ROC curve, and the corresponding sensitivity, specificity, and accuracy were also calculated. Results: Endoscopic ultrasound elastography was highly positively correlated with the pathological stage of liver fibrosis (S ≥ 2, r = 0.759, P = 0.01), and TUS-TE was positively correlated with the pathological stage of liver fibrosis (S ≥ 2, r = 0.857, P = 0.003). The optimal diagnostic cut-off value of cirrhosis undergoing EUS-EG and TUS-TE was 0.84 and 14.2 Kpa, respectively. When the pathological stage was S0 - S1, the sensitivity, specificity, accuracy, and AUROC value of TUS-TE in the diagnosis of liver fibrosis were higher than those of EUS-EG (96.2%, 83.3%, 81.8%, and 0.96 vs. 94.6%, 75%, 72.7%, and 0.8958). When the pathological stage was ≥ S2, the sensitivity, specificity, accuracy, and AUROC values of EUS-EG were higher than those of TUS-TE (100%, 87.5%, 88.9%, and 0.97 vs. 100%, 83.3%, 88.9%, and 0.94). Conclusions: There is a superior correlation between EUS-EG combined with SR and the pathological stage of liver fibrosis, compared to TUS-TE, and it has the same or even higher diagnostic efficacy as TUS-TE. Larger prospective studies are needed to evaluate the clinical utility of this approach in the assessment of liver fibrosis.

Molecular dynamics simulation of effects of loading parameters on fatigue crack growth behavior in titanium single crystal

AbstractThe fatigue crack growth behavior in single‐crystal titanium with a prismatic crack was simulated using molecular dynamics (MD) considering the effects of applied temperature, strain ratio, and strain rate. The results indicate that the material exhibits transient cyclic hardening behavior and dominant cyclic softening behavior. The peak tensile stress decreases with increasing temperature or decreasing strain rate. The deformation mechanism for crack growth involves prismatic dislocation emission and the formation of vacancy defects at different loading conditions. Deformation twinning occurs at the highest temperature, and a secondary crack emerges at the highest strain rate. The Mises stress concentration at the twin boundary and the coalescence between the initial and secondary cracks may accelerate crack propagation. The ΔJ shows good linear relationships with fatigue crack growth rate (FCGR), indicating that ΔJ possesses the potential to assess fatigue crack growth behavior at the atomic scale for ductile metallic materials.

Combining Potential Strain Elastography and Radiomics for Diagnosing Breast Lesions in BI-RADS 4: Construction and Validation a Predictive Nomogram

To develop a nomogram by integrating B-mode ultrasound (US), strain ratio (SR), and radiomics signature (RS) effectively differentiating between benign and malignant lesions in the Breast Imaging Reporting and Data System (BI-RADS) 4. We retrospectively recruited 709 consecutive patients who were assigned a BI-RADS 4 and underwent curative resection or biopsy between 2017 and 2022. US images were collected before surgery. A RS was developed through a multistep feature selection and construction process. Histology findings served as the gold standard. Univariate and multivariate regression analysis were employed to analyze the clinical and US characteristics and identify variables for developing a nomogram. The calibration and discrimination of the nomogram were conducted to evaluate its performance. The study included a total of 709 patients, with 497 in the training set and 212 in the validation set. In the training set, the B-mode US had an AUC of 0.84 (95% confidence interval [CI], 0.80, 0.87). The SR demonstrated an AUC of 0.78 (95% CI, 0.74, 0.82), while the RS showed an AUC of 0.85 (95% CI, 0.81, 0.88). Notably, the nomogram exhibited superior performance compared to the conventional US, SR, and RS (AUC=0.93, both p<0.05, as per the Delong test). The clinical usefulness of the nomogram was favorable. The calibrated nomogram can be specifically designed to predict the malignancy of breast lesions in the BI-RADS 4 category.

A study on the fracture pattern change of high-burnup fuel cladding failed by pellet-cladding mechanical interaction failure under reactivity-initiated accident conditions

ABSTRACT In a part of the historical reactivity-initiated accident (RIA) simulated tests on high-burnup fuels performed at the Nuclear Safety Research Reactor, the fuel failure caused by pellet-cladding mechanical interaction (PCMI) led to splitting into upper- and lower-part pieces or even fragmentation of the cladding tube. A massive release of fuel fragments accompanied this fracture pattern change from previously known axial cracks and thus identified as a potential concern in safety evaluation regarding core coolability. Dedicated out-of-pile mechanical tests were performed with unirradiated Zircaloy-4 cladding specimens to clarify the condition of such fracture pattern change. The specimens were pre-hydrided and subjected to loading with axial-to-hoop strain ratios of ℇz/ℇθ = 0.5–1.25, simulating the effects of hydrogen embrittlement and pellet-cladding mechanical bonding of high-burnup fuels, respectively. The results indicate that higher biaxiality of the loading and lower ductility (failure strain level) assist the fracture pattern change. This study proposes a conservative criterion that a PCMI failure splits the cladding tube into more than two pieces when strain ratio ℇz/ℇθ >0.75 and a concurrent hoop strain < 1.7% at the failure instant.

Effect of swap and antisite disorder on electronic, mechanical and thermodynamic properties of equiatomic all-d-metal Heusler alloy NiVTiZn

The influence of atomic disorder on electronic, mechanical and thermodynamic properties of equiatomic quaternary all-d metal Heusler alloy NiVTiZn is studied by employing the first-principles calculations. The ground state of NiVTiZn is confirmed to be α-type structure with ferromagnetic nature, the calculated spin down energy gap and equilibrium lattice constant is ∼0.7 eV and 6.048 Å, respectively. The half metallicity could be maintained when uniaxial strain ratio increases from −7.28 % to 9.59 % and when c/a ratio ranges from 0.92 to 1.06, showing a robust half metallicity against the strain effect and tetragonal distortion. Six types of atomic swap disorder and twelve types of atomic antisite disorder are proposed. The V(Ni) and V(Zn) antisite disorders as well as V-Ni and V-Zn swap disorders are the most favorable owing to their negative formation energies. The 100 % spin polarization is preserved in V(Ti), Ni-Zn and V-Ti disordered structures although the width of band gap suffers contraction. The spin polarization of Ni(V), Ni(Zn), V(Zn) and Zn(Ni) disordered structures is also larger than 80 %. In addition, the effect of various disorder on mechanical and thermodynamic properties is also studied in detail.

Using a combination of superb microvascular imaging and other auxiliary ultrasound techniques to increase the accuracy of gray-scale ultrasound for breast masses

BackgroundBreast ultrasound is highly sensitive, but its specificity is not as high for detecting malignant lesions. Auxiliary modalities like elastography, Color and Power Doppler ultrasound are used as adjuncts to yield both a high sensitivity and specificity. Superb microvascular imaging (SMI) is a newer modality with more accuracy for detecting breast lesions. In this study, our goal was to investigate the role of SMI as an adjunct to ultrasound and find a suitable combination model for the evaluation of breast masses.MethodsIn this cross-sectional study, 132 women with 172 breast masses who underwent ultrasound-guided biopsy were included.. The ultrasound features of the lesion, the strain ratio in strain elastography, the number of vessels for each lesion, their morphology and distribution in Doppler and Power Doppler ultrasound and SMI were recorded for each lesion. A vascular score and a vascular ratio were defined.ResultsIn the histologic examination, 31 lesions (18%) were malignant and 141 lesions (82%) were benign. The vascular score was more accurate than the vascular ratio in all three modalities. The predictive ability of strain ratio was higher than Doppler and Power Doppler ultrasound and SMI. Adding SMI alone to ultrasound increased the specificity from 46.10% to 61.2% and the accuracy from 55.80% to 70.11%. In the combination of ultrasound with other modalities, the best was the combination of ultrasound, strain elastography, and SMI; which yielded a specificity and sensitivity of 100% and 74.4%, respectively.ConclusionAdding SMI and STE modalities as adjuncts to ultrasound lowers the chance of missing malignant lesions and reduces unnecessary biopsies of breast lesions. A study with a larger sample size using this combination model to evaluate the accuracy with greater precision is recommended.