Strain Combinations Research Articles

K-Ion Slides in Prussian Blue Analogues.

We study the phenomenology of cooperative off-centering of K+ ions in potassiated Prussian blue analogues (PBAs). The principal distortion mechanism by which this off-centering occurs is termed a "K-ion slide", and its origin is shown to lie in the interaction between local electrostatic dipoles that couple through a combination of electrostatics and elastic strain. Using synchrotron powder X-ray diffraction measurements, we determine the crystal structures of a range of low-vacancy K2M[Fe(CN)6] PBAs (M = Ni, Co, Fe, Mn, Cd) and establish an empirical link between composition, temperature, and slide-distortion magnitude. Our results reflect the common underlying physics responsible for K-ion slides and their evolution with temperature and composition. Monte Carlo simulations driven by a simple model of dipolar interactions and strain coupling reproduce the general features of the experimental phase behavior. We discuss the implications of our study for optimizing the performance of PBA K-ion battery cathode materials and also its relevance to distortions in other, conceptually related, hybrid perovskites.

A Narrative Review of the Tale of the Dysbiotic Microbiome in the Preterm Neonate

Background: Researchers have established that the preterm neonate is born with an immature gastrointestinal tract. The preterm neonate is thus susceptible to various complications often seen in the neonatal intensive care unit, e.g., feeding intolerances, necrotizing enterocolitis, and hospital-acquired bloodstream infections. These complications can be life-threatening, and if survived, can have an unfavorable effect on the neonate’s growth and development. Aim: The aims of this narrative review article were to provide an in-depth understanding of the various factors contributing to the development of the preterm neonatal microbiome. Further, we reviewed gastrointestinal microbiome dysbiosis and its potential role in the development of feeding intolerances, necrotizing enterocolitis, and hospital-acquired bloodstream infections. Lastly, we described the potential role of probiotics in this vulnerable population. Methods: A PubMed database search was conducted identifying articles that describe the development and function of the neonatal microbiome, the role of gastrointestinal dysbiosis, and the development of neonatal complications as well as the role of probiotics in gastrointestinal dysbiosis. Results: Various maternal, neonatal, and environmental factors play a role in the development of gastrointestinal dysbiosis in the preterm neonate. This can lead to feeding intolerances, necrotizing enterocolitis, and hospital-acquired bloodstream infections. Discussion: The pathogenesis of the development of short-term complications in the preterm neonate can be linked to the immaturity of the host immune system as well as alterations seen in the intestinal microbiome. There is a growing body of evidence that probiotics can play a role in preventing dysbiosis and thus complications observed in the preterm neonate. However, the optimal combination of probiotic strains and dosage still needs to be identified.

Exploring the biochar as a suitable carrier for a bioinoculant Aspergillus niger K7 and its consequence on Eleusine coracana in field studies

Carriers are not only important in providing a protective niche for microbial inoculants but also act as delivery vehicles. In the present investigation, the aim is to study the suitability of biochar as a carrier for Aspergillus niger K7 as well as its impact on the growth and productivity of Eleusine coracana, if any. In this experiment, the spores of the K7 strain were used as bioinoculant with biochar as a carrier for growth studies of finger millet in the agriculture field. Soil and biochar were analyzed for their physiochemical properties. After that, inoculum preparation was done, and the inoculum was incubated for six months with biochar to examine the viability of K7 strain with biochar. At last, for field trials, the seeds were sown, the mixture was amended to the soil, and growth and yield parameters were measured at 60 and 130 days. The soil amended with K7 strain and biochar separately showed significant enhancement in the growth and yield of plants over control, but the combination of the fungal strain with biochar as a carrier gave the best results in our study. It can be inferred from the results that biochar can protect microbial inoculants, improve soil properties, and make nutrients available for plant growth.

Psychosocial study environment characteristics associated with exposure to sexual harassment at a large public university in southern Sweden: a cross-sectional study

ABSTRACT Background Universities can be understood as work-like environments for students, with similar risks and expectations regarding psychosocial environment. Limited research has examined this study environment from a Demand-Control-Support perspective with regard to sexual harassment. Understanding this environment is key to designing protective measures. This study aimed to examine the association between individual and psychosocial study environment characteristics and exposure to sexual harassment among students at Lund University, Sweden. Methods This cross-sectional study utilised data from an online survey conducted among students. Questions on background characteristics, exposure to sexual harassment while at university and psychosocial study environment as measured by a Demand-Control-Support-instrument were used. Bivariate, and multivariable logistic regressions were used, together with Population Attributable Fractions (PAF), and synergy indexes (SI). Results High demands and low control were independently associated with higher odds of being exposed to sexual harassment among both females and males (OR 1.41, OR 1.26 and OR 1.55, OR1.34, respectively). When adjusting for background characteristics, high study strain (combination of high demands and low control) was associated with exposure to sexual harassment among both female and male respondents (aOR 1.67 and 1.98 respectively) and could account for PAF of 14% and 15% of study environment sexual harassment for females and males, respectively. Low lecturer support was associated with higher odds for sexual harassment among females (aOR 1.19) but not males. Little evidence was found for a buffering effect of student support on high strain and sexual harassment (SI 0.7). Conclusion Working to reduce situations of high strain study environments could be an effective strategy for reducing sexual harassment in university settings. Improving support from lecturers could also modify this relationship, but more research is required to identify causal pathways underlying this result.

Efficacy of native Bacillus isolates against different larval instars of fall armyworm, Spodoptera frugiperda alone and in combination

BackgroundFall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) Lepidoptera: Noctuidae is an invasive polyphagous pest that causes severe damage to several agricultural crops. The use of pesticides is limited because of their mode of feeding and resistant development. Hence, the present work aimed to determine the pathogenicity of entomopathogenic bacteria (Bacillus spp.) against FAW in terms of mortality and growth inhibition. In this study, initially 49 native Bacillus isolates, isolated from diverse habitats in India, along with five reference strains, were screened for their efficacy against neonates of S. frugiperda under controlled laboratory conditions, followed by virulence and combinatorial bioassays.ResultsFive native Bacillus isolates (VKK1, VKK5, S16C2, S25C1, and SOIL 20) showed mortality in the range of 35.49–65.52% against neonates of S. frugiperda at single concentration (1000 μg g−1 of diet). These five isolates, along with one reference strain Btk-HD1 (Bacillus thuringiensis serovar kurstaki strain HD1), were further tested to find the median lethal concentration (LC50) for neonates of S. frugiperda. Among these, native Bt strain VKK5 showed the lowest LC50 (718.40 µg/g of diet) and HD1 showed the highest LC50 (3352 µg/g of diet). Combinatorial bioassay against neonate and third instar larvae showed that the combination of VKK5 and VKK1 had an additive effect. Moreover, growth inhibition was also recorded.ConclusionThe combination of Bt strains leads to an enhancement of pathogenicity toward FAW larvae at the initial stage of development, and in later stages, it affects their growth and development. Thus, biocontrol of FAW by entomopathogenic bacteria (Bt) can play a vital role in the effective management of FAW.

Characteristics of Iranian Probiotic UF White Cheese

Cheese is able to transport live probiotics due to its dry matter, fat, and higher pH than yogurt-like products. According to health organizations’ emphasis on promoting the consumption of healthy dairy products and consumers’ desire to eat healthier foods, in this study, the feasibility of producing probiotic UF cheese containing probiotic strains of Bifidobacterium bifidum sp. IR007-113 and Enterococcus faecium sp. IBRC-M 10836 as a single or combined study was investigated. The experimental cheeses used in this study include A: UF cheese as a control sample, B: probiotic UF cheese containing Bifidobacterium bifidum, C: probiotic UF cheese containing Enterococcus faecium, and D: probiotic UF cheese containing a combination of Bifidobacterium bifidum and Enterococcus faecium strains. Viability of probiotic organisms on the basis of log cfu/g and aroma compounds including (acetaldehyde, diacetyl, acetone, and acetic acid all in micrograms per gram) was assessed during the 60-day ripening period. The results showed that the probiotic bacterial population decreased during the 60-day storage period. However, at the end of the storage period, all experimental cheeses contained probiotic strains above 106 cfu/g. The acetaldehyde compound increased during the 60-day storage period, and diacetyl, acetoin, and acetic acid contents decreased during the 60-day storage period except for the control sample. A total of 12 free fatty acids were identified in Iranian probiotic UF white cheese, which had the highest concentration of palmitic acid among saturated fatty acids and oleic acid among unsaturated fatty acids. The sensory scores of flavor increased during the 60-day storage period. Texture sensory scores of all experimental cheeses decreased during the storage period. In terms of acceptability, all experimental cheeses showed an increasing trend. In general, the results showed that it is possible to produce UF probiotic cheese with minimal adverse effects on quality characteristics and sensory acceptability. Also, treatment D had relatively better characteristics compared to other cheese variants.

Genotype by Environment Interactions (G*E) of Chickens Tested in Ethiopia Using Body Weight as a Performance Trait.

Ethiopia is a developing nation that could highly benefit from securing food via improved smallholder poultry farming. To support farmer and breeding decisions regarding which chicken strain to use in which Ethiopian environment, G*E analyses for body weight (BW) of growing male and female chickens were conducted. Research questions were (1) if a G*E is present for BW and (2) which strain performs best in which environment in terms of predicted BW. Analyses were performed using predicted BW at four different ages (90, 120, 150, and 180 days) of five strains (Horro, Koekoek, Kuroiler, Sasso-Rhode Island Red (S-RIR), and Sasso) tested in five Ethiopian regions (Addis Ababa, Amhara, Oromia, South Region, and Tigray) that are part of three Agro-Ecological Zones (AEZ) (cool humid, cool sub-humid, and warm semi-arid). The indigenous Horro strain was used as a control group to compare four other introduced tropically adapted strains. The dataset consisted of 999 female and 989 male farm-average BW measurements. G*E was strongly present (p < 0.001) for all combinations of strain and region analyzed. In line with previous research, Sasso was shown to have the highest predicted BW, especially at an early age, followed by Kuroiler. Horro had the lowest predicted BW at most ages and in most regions, potentially due to its young breeding program. The highest predicted BW were observed in Tigray, Oromia, and Amhara regions, which are in the main part of the cool sub-humid AEZ.

Interaction between flaws and failure characteristics of red sandstone containing double flaws under compressive-shear loading

The failure characteristics of the fractured rock mass and the interaction between flaws were significantly affected by the flaw configurations. This study quantitatively investigated the effect of flaw geometries on the interaction between flaws under compressive-shear loading. The evolution of the surface strain field was recorded and analyzed using digital image correlation (DIC) technology, enabling the localization of crack paths and the determination of crack initiation mechanisms. Combined with DIC and scanning electron microscopy, both the macroscopic and microscopic failure characteristics of specimens with double flaws subjected to compressive-shear loading were comprehensively investigated. The results showed that the axial peak force of flawed specimen was sensitive to the flaw configuration, and the axial peak forces of flawed specimens with parallel flaws were greater than those with coplanar ones. The tensile strain was the primary factor dominating the initiation and propagation of cracks from flaw tips, whereas the cracking mechanism of edge cracks was a combination of tensile and shear strains. In addition, two novel parameters, namely independent parameter Ri and reinforced parameter Rr, were proposed to quantitatively characterize the independent effect discovered between coplanar flaws and the reinforced effect between parallel flaws, respectively. Besides, it was observed that the flaw configuration has a significant effect on rock failure characteristics, and three typical crack coalescent modes were found. The findings of this paper could facilitate a better understanding of the interaction between flaws and rock failure characteristics subjected to compressive-shear loading conditions.

Achieving high strength and ductility in high-entropy alloy particle reinforced Al matrix composites with proper proportion of layered structures

Particle spatial distribution has a significant influence on mechanical behavior of particulate reinforced Al matrix composites fabricated by powder metallurgy, which has been systematically investigated in our work. The results showed that, by regulating the milling time for 1 h, 10 h and ≥ 20 h, assisted by hot pressing and hot extrusion processes, three typical distributions of high-entropy alloy (HEA) particles within the Al matrix composites were constructed, i.e., particle agglomerated composite, uniformly distributed composite, and layered structure composite, respectively. After a long-time high energy milling, alloying behavior did not occur between the Al and HEA particles. Moreover, the composite with a proper proportion (19 vol%) of layered structures achieved good combination of yield strength (445.2 MPa) and fracture strain (5.4%), which was ascribed to the strengthening and toughening effect induced by bimodal gain structure. The effect of layered structure on the composite was reflected in two points: first, due to the differences in dislocation density and consumption degree of Cu atoms, the size and density of precipitates in the large particle zones differ from those in the layered structured zones. Second, according to the finite element analysis, though high content of layered structures brought high strength in the composites, it also caused stress concentration, which could reduce the ductility of composites. The dominant strengthening contribution of the layered structure in the composites was derived from the grain boundary strengthening. This research provides a new insight into Al matrix composites with different reinforcing particle distribution.

The preferred growth orientation of Ti thin film on MgO(100) substrate

Understanding the preferred growth orientation of metal films is of great significance for optimizing film properties and preparing films with special structures. However, early works mainly focused on the preferred growth orientations of FCC and BCC metal films, the preferred growth orientation of HCP metal films and its formation mechanism are unclear. In this work, Ti film was deposited on MgO(100) substrate by magnetron sputtering at 523 K. The preferred growth orientation of Ti film and its formation mechanism were studied by experiment and first-principles calculation. XRD results found the preferred growth orientations of Ti film on MgO(100) substrate were Ti(001), Ti(100), and Ti(101), with Ti(001) being the most favored. First-principles calculation results showed the preferred growth orientation of the Ti film on the MgO(100) substrate was determined by a combination of interface separation work and lattice strain.

Prevalence and influencing factors of probiotic usage among colorectal cancer patients in China: A national database study.

Probiotics have become increasingly popular among cancer patients. However, there is limited data from a real-world setting. This study aims to conduct a retrospective analysis to understand the trend of probiotic prescriptions in Chinese colorectal cancer patients. The Mann-Kendall and Cochran-Armitage trend test was applied to estimate the trend significance. Gephi software identified the combination of probiotic strains. The binary logistic regression investigated influence factors, and Spearman's rank correlation coefficient calculated correlations between probiotics and antitumor drug usage. The probiotic prescription percentage increased from 3.3% in 2015 to 4.2% in 2021 (Z = 12.77, p < 0.001). Although 48.3% of probiotic prescriptions had no indication-related diagnosis, diarrhea (OR 10.91, 95% CI 10.57-11.26) and dyspepsia (3.97, 3.82-4.12) included prescriptions most likely to contain probiotics. Prescriptions from the tertiary hospital (1.43,1.36-1.50), clinics (1.30, 1.28-1.33), and senior patients (1.018 per year, 1.017-1.019) were more likely to contain probiotics. Most probiotic prescriptions (95.0%) contained one probiotic product but multiple strains (69.3%). Enterococcus faecalis (49.7%), Lactobacillus acidophilus (39.4%), and Clostridium butyricum (27.9%) were the most prescribed strains. The probiotics co-prescribed with antitumor agents increased rapidly from 6.6% to 13.8% in seven years (Z = 15.31, p < 0.001). Oral fluorouracil agents (2.35, 2.14-2.59), regorafenib (1.70,1.27-2.26), and irinotecan (1.27,1.15-1.41) had a higher probability to co-prescribed with probiotics. There was no correlation between probiotic strain selection and specific antitumor drug use. The increasing prescription of probiotics in colorectal cancer patients in China may be related to treating the gastrointestinal toxicity of anti-cancer drugs. With unapproved indications and a lack of strain selectivity, evidence-based guidelines are urgently needed to improve probiotic use in this population.

Optimization of lactic acid bacterial starter culture to improve the quality and flavor characteristics of traditional Hurood

Hurood is a traditional fermented milk product prepared by traditional Mongolian techniques of fermenting raw milk, partial degreasing, heating, whey drainage, emulsification of curd, and molding. Currently, Hurood available in the market is generally prepared by small-scale enterprises at home or in open air. Therefore, lack of standardization of bacterial starter culture leads to variation in the flavor and sensory properties of Hurood from batch to batch. In this study, we aimed to assess the best starter culture combination obtained from 37 lactic acid bacterial strains isolated from traditional Hurood. The solidification state and sensory quality were used as indexes for determining the fermentation efficiency of the bacterial starter culture combinations. The yield and texture characteristics were used to determine the optimal ratio of bacterial strains in a combination and the processing conditions for traditional Hurood production. The most optimal bacterial culture combination was observed to be NF 9-3:NF 10-4:CH 3-1 in 5:4:1 ratio and in 3% amount. The most optimal whey temperature and heating-stirring temperature were observed to be 55°C to 60°C and 85°C to 90°C, respectively. Hurood prepared with the optimal combination of bacterial strains exhibited significantly enhanced sensory quality, flavor, and contents of AA and fatty acids. Therefore, the use of optimal starter culture of lactic acid bacteria could produce Hurood with significantly superior sensory qualities, making the product more acceptable to consumers.

Dynamic tensile deformation of Al0.1Ti0.1CoCrFeNi high entropy alloy with heterogeneous grain structure

The single-phase Al0.1Ti0.1CoCrFeNi high-entropy alloy (HEA) with heterogeneous grain structure was processed through cold rolling followed by annealing at 1073 K. The mechanical behaviors of this HEA under quasi-static (10−3 ∼ 10−1 s−1) and dynamic (1200 ∼ 3000 s−1) uniaxial tension were investigated. A combination of high tensile strength and large fracture strain was achieved. Specifically, the yield strength and ultimate tensile strength were increased from 381 MPa and 1000 MPa at 10−3 s−1 to 590 MPa and over 1200 MPa at a strain rate of 3000 s−1, respectively. Meanwhile, the engineering fracture strain of the HEA increased from 43 % to 62 % with increasing strain rate. Under dynamic tension, a high density of dislocations, together with numerous deformation twins and stacking faults, inside the fine grains contributed to the simultaneous improvement of the tensile strength and ductility.

Papaverine Enhances the Oncolytic Effects of Newcastle Disease Virus on Breast Cancer In Vitro and In Vivo.

Breast cancer is a lethal disease in females worldwide and needs effective treatment. Targeting cancer cells with selective and safe treatment seems like the best choice, as most chemotherapeutic drugs act unselectively. Papaverine showed promising antitumor activity with a high safety profile and increased blood flow through vasodilation. At the same time, it was widely noticed that virotherapy using the Newcastle disease virus proved to be safe and selective against a broad range of cancer cells. Furthermore, combination therapy is favorable, as it attacks cancer cells with multiple mechanisms and enhances virus entrance into the tumor mass, overcoming cancer cells' resistance to therapy. Therefore, we aimed at assessing the novel combination of the AMHA1 strain of Newcastle disease virus (NDV) and nonnarcotic opium alkaloid (papaverine) against breast cancer models in vitro and in vivo. Methods. In vitro experiments used two human breast cancer cell lines and one normal cell line and were treated with NDV, papaverine, and a combination. The study included a cell viability MTT assay, morphological analysis, and apoptosis detection. Animal experiments used the AN3 mouse mammary adenocarcinoma tumor model. Evaluation of the antitumor activity included growth inhibition measurement; the immunohistochemistry assay measured caspase protein expression. Finally, a semiquantitative microarray assay was used to screen changes in apoptotic proteins. In vitro, results showed that the combination therapy induces synergistic cytotoxicity and apoptosis against cancer cells with a negligible cytotoxic effect on normal cells. In vivo, combination treatment induced a significant antitumor effect with an obvious regression in tumor size and a remarkable and significant expression of caspase-3, caspase-8, and caspase-9 compared to monotherapies. Microarray analysis shows higher apoptosis protein levels in the combination therapy group. In conclusion, this study demonstrated the role of papaverine in enhancing the antitumor activity of NDV, suggesting a promising strategy for breast cancer therapy through nonchemotherapeutic drugs.

Mixed viral infection constrains the genome formula of multipartite cucumber mosaic virus

Many plant viruses have a multipartite organization, with multiple genome segments packaged into separate virus particles. The genome formula describes the relative frequencies of all viral genome segments, and previous work suggests rapid changes in these frequencies facilitate virus adaptation. Many studies have reported mixed viral infections in plants, often resulting in strong virus–virus interactions. Here, we tested whether mixed infections with tripartite alfalfa mosaic virus (AMV) and monopartite potato virus Y (PVY) affected the genome formula of the tripartite cucumber mosaic virus (CMV), our experimental model. We found that the CMV titer was reduced in mixed infections with its tripartite Bromoviridae relative AMV and in triple infections with both AMV and PVY, indicating notable virus–virus interactions. The variability of the CMV genome formula was significantly lower in mixed infections (CMV and AMV, CMV and PVY, and CMV and AMV and PVY) than in single infections (CMV only). These observations led to the surprising conclusion that mixed infections with two distinct viruses constrain the CMV genome formula. It remains unclear how common these effects are for different combinations of virus species and strains and what the underlying mechanisms are. We, therefore, extended a simulation model to consider three putative scenarios in which a second virus affected the genome formula. The simulation results also suggested that shifts in the genome formula occur, but may not be widespread due to the required conditions. One scenario modeled—co-infection exclusion through niche differentiation—was congruent with the experimental data, as this scenario led to reductions in genome formula variability and titer of the multipartite virus. Whereas previous studies highlighted host–species effects, our results indicate that the genome formula is also affected by mixed infections, suggesting that there is a broader set of environmental cues that affect the genome formula.

Introducing “Rapid phage susceptibility testing” (RPST): an accelerated lytic phage activity test for routine diagnostic laboratories within eight hours

Phage therapy, particularly for infections due to multi-drug-resistant bacteria, is increasingly gaining in importance. Consecutively, there is a rising need for phage testing in routine diagnostic laboratories. The incubation time of phage susceptibility testing for detecting lytic phage activity on phage/host strain combinations was evaluated. A standardized approach for routine diagnostic laboratories provided reliably detectable lysis zones within 8 hours.

Performance Evaluation of Bacterial Consortia from Low-Permeability Reservoir in Ordos Basin

The combination of strains of different species and genera may enhance the effects of single bacteria, surpass the tolerance upper limit, and optimize the viscosity reduction and degradation. In this study, six strains were isolated in low permeability layers of the Ordos Basin and were combined to verify the effect of the consortium strains. The selected single strains have good emulsifying and viscosity-reducing effects, but their degradation components are different. SC4561 (Bacillus cereus), SC4551 (Bacillus sp.), and H-1 (Brevibacillus sp.) form consortium A, and SC4534 (2) (Bacillus sp.), SC4542 (Bacillus licheniformis), and A-3 (Bacillus licheniformis) form consortium B. The performance of the mixed strains was evaluated by the analysis of change in emulsification rate, crude oil composition, viscosity, and the tolerance (temperature, salinity, and pH) through GC-MS, rotational rheometer, and other methods. The results showed that the temperature tolerance of the consortium strains was improved by 5-7°C. Consortium B had higher emulsibility ( E 24 was higher than 40% in average) and viscosity degradation (above 35%), and the crude oil in consortium B has almost no wall adhesion. The components of crude oil that consortia use were still diverse, including both long- and short-chain hydrocarbons. However, the proportion of long-chain n-alkanes is further reduced compared with that of single bacteria, and the highest ratio was reduced by 23.81% (B-ALL). At the same time, they also had effects on aromatic hydrocarbons with complex structures (phenanthrene and phenanthrene). This research confirms the enhanced effect of consortium bacteria on single bacteria, facilitating the implementation of microbial enhanced oil recovery technology in the future.

A sediment transport theory based on distortion-free-boundary nonhomogeneous fluid flows

Over the last 50 years several sediment transport models in coastal environments based on Shallow Water(SW) type models have been developed in the literature. The water flow over an abrupt moving topography quickly spatially variable becomes accelerated and strongly varied arising the turbulence (distortion). The acceleration and strong variation of the flow facilitate the transport of a large quantity of sediments present at the bottom while modifying it. The mathematical models based on SW type models widely used to describe the sediment transport phenomena do not account the distortion effects. Indeed, it is well-known that the SW models are derived from first order approximation of long wave theory. The acceleration and strong variation of the water flow near the bottom is due to the distortion of the horizontal velocity profile along the vertical direction. One can regard distortion as a combination of strain and rotation. The effect of the rotational component is to weaken the effect of the strain somewhat. In this work, we put in place a king theory of sediment transport derived from the second order approximation of long wave theory that can describe sediment transport processes in distortion-free-boundary nonhomogeneous fluid flows. The derived model accounts the distortion (fluctuation with great correlation lengths) that creates the turbulence. Moreover, the model differentiates the fluid velocity from sediment velocity (phase-lag) near the sediment bed. The proposed theory significantly reduces the modeling errors observed in several sediment transport models based on nonhomogeneous shallow water equations and has a great potential to increase the predictive power of sediment transport models in rivers, lakes, coastal flows, ocean basins and so on. The proposed theory improves several existing sediment transport theories recently developed in the literature and can be apply with some degree confidence.

Formability prediction of high‐strength steel sheet using experimental, analytical and theoretical analysis based on strain and stress forming limit curves and its application to automotive forming parts

AbstractIn this work, the high‐strength steel (HSS) sheet dual‐phase 440 (DP440) were conducted to establish the forming limit curve (FLC) and analytical forming limit stress curve (FLSC) obtained from experimental forming limit curve. First, the Nakajima stretch forming examination was carried out to obtain forming limit curve of investigated sheet. Afterwards, the theoretical Marciniak–Kuczinsky (M–K) model was developed and calculated to evaluate localized necking limits both in strain and stress spaces combination with anisotropic yield criteria. Then, the analytical forming limit stress curves were plastically calculated by using experimental forming limit curve data combination with Swift hardening model and anisotropic yield criteria namely, Hill’48 and Yld2000‐2d for representing anisotropic plastic deformation behavior on examined steel sheet. Finally, automotive stamping parts were performed in order to verify an applicability of all developed curves. It was observed that the analytical forming limit stress curves could more precisely predict the formability of automotive parts better than the forming limit curve based on strain. Particularly, the one based on Yld2000‐2d predict better than the one based on Hill’48. Simultaneously, the experimental forming limit curve and analytical forming limit stress curve were also evaluated comparing with the theoretical calculated forming limit curve and forming limit stress curve using the Marciniak–Kuczinsky model. It should be noted again that the experimental forming limit curve and analytical forming limit stress curve are the best one. Therefore, the Yld2000‐2d yield function better represented the anisotropic behavior of the high‐strength steel sheet dual‐phase 440 than Hill′ 48 yield function, and can suitable be used for the analysis prediction and design of bumper automotive parts under forming processes.

Virtual strain loading method for low temperature cohesive failure of asphalt binder

Cohesive failure is one of the primary reasons for low-temperature cracking in asphalt pavements. Understanding the micro-level mechanism is crucial for comprehending cohesive failure behavior. However, previous literature has not fully reported on this aspect. Moreover, there has been insufficient attention given to the correlation between macroscopic and microscopic failures. To address these issues, this study employed molecular dynamics simulation to investigate the low-temperature tensile behavior of asphalt binder. By applying virtual strain, the separation work during asphalt binder tensile failure was calculated. Additionally, a correlation between macroscopic and microscopic tensile behaviors was established. Specifically, a quadrilateral asphalt binder model was generated based on SARA fractions. By applying various combinations of virtual strain loading, the separation work at tensile failure was determined. Furthermore, the impact of strain loading combinations on separation work was analyzed. Normalization was employed to establish the correlation between macroscopic and microscopic tensile behaviors. The results indicated that thermodynamic and classical mechanical indicators validated the reliability of the tetragonal asphalt binder model. The strain loading combination consists of strain rate and loading number. All strain loading combinations exhibited the similar tensile failure characteristic. The critical separation strain was hardly influenced by strain loading combination. However, increasing strain rate significantly enhanced both the maximum traction stress and separation work of the asphalt binder. An increment in the loading number led to a decrease in separation work. The virtual strain combination of 0.5%-80 provided a more accurate representation of the actual asphalt's tensile behavior trend.