94 research outputs found
Effect and Process Conditions of Cold Plasma Combined withL-Glutamic Acid and Salt Stress on Germination and Enrichment ofγ-Aminobutyric Acid in Adzuki Bean
This study aimed to investigate the effect of cold atmospheric pressure plasma (CAPP) treatment combined with salt stress on the enrichment of gamma-aminobutyric acid (GABA) in adzuki beans after germination. The effect of CAPP voltage, frequency, and duration of treatment of seeds, on their GABA content during germination was investigated using adzuki beans as raw material. In addition, the method of germination using L-glutamic acid (L-Glu) combined with salt stress was used to investigate the effect of single factors (germination time and concentrations of CaCl2, L-Glu, and NaCl) on enrichment of GABA. The optimal process conditions for enrichment of GABA using response surface optimization experiments were also determined. The results showed that the treatment of seeds with CAPP technology had a beneficial effect on their germination and enrichment of GABA. The CAPP treatment was more effective under the following conditions: voltage of 90 kV, frequency of 120 Hz, and duration of 20 min. When the germination time was 58 h and the CaCl2, L-Glu, and NaCl concentrations were 4.4 mmol/L, 3.2 mg/mL, and 66 mmol/L, respectively, the GABA content of germinated adzuki beans was 160.23±2.91 mg/100 g, which was 7.12 times higher than that of ungerminated adzuki beans. This method is efficient, reliable, cost-effective, and provides a technical reference for the industrial production of GABA-rich foods
Use of Hypoxia Combined with Acid Stress to Enrich GABA in Adzuki /Mung Beans, and Optimization of GABA-rich Sprouted Bean/Rice Mixture Processing Conditions
In order to study the effect of hypoxia combined with acid stress on GABA enrichment in adzuki bean and mung bean, germination time, germination temperature, hypoxia time and L-glutamic acid concentration were investigated by single factor. Based on the stress conditions identified for high GABA sprouted beans, GABA-enriched adzuki and mung beans were mixed with rice, and D-mixture design was used to optimize processing conditions for these sprouted bean/rice mixtures. Results showed that hypoxia combined with acid stress promoted GABA enrichment in adzuki and mung beans. In sprouted adzuki beans, GABA reached levels as high as 158.32±3.24 mg/100 g under the germination time of 48 h, germination temperature of 40 ℃, 15 h exposure to hypoxia, and L-glutamic acid concentration of 2.5 mg/mL. Mung bean stress conditions were: Germination time of 24 h, germination temperature of 35 ℃, 15 h exposure to hypoxia, and L-glutamic acid concentration of 2.5 mg/mL, the content of GABA was 141.57±4.35 mg/100 g. On this basis, the sprouted beans and rice formulation was optimized by D-mixture design as follows: Rice 76%, sprouted mung beans 11%, and sprouted adzuki beans 13%. Under this composition, the GABA content of sprouted bean/rice mixture was 23.73±1.03 mg/100 g, and the average sensory score was 88.76±2.47. The taste, color, and aroma of the sprouted bean/rice mixture fell within acceptable ranges, and the active ingredient GABA was enriched, enhancing the nutritional and functional properties of sprouted beans/rice. This study provided a theoretical reference for the further development of rice/grain mixtures
Knock-down of YME1L1 induces mitochondrial dysfunction during early porcine embryonic development
YME1L1, a mitochondrial metalloproteinase, is an Adenosine triphosphate (ATP)-dependent metalloproteinase and locates in the mitochondrial inner membrane. The protease domain of YME1L1 is oriented towards the mitochondrial intermembrane space, which modulates the mitochondrial GTPase optic atrophy type 1 (OPA1) processing. However, during embryonic development, there is no report yet about the role of YME1L1 on mitochondrial biogenesis and function in pigs. In the current study, the mRNA level of YME1L1 was knocked down by double strand RNA microinjection to the 1-cell stage embryos. The expression patterns of YME1L1 and its related proteins were performed by immunofluorescence and western blotting. To access the biological function of YME1L1, we first counted the preimplantation development rate, diameter, and total cell number of blastocyst on day-7. First, the localization of endogenous YME1L1 was found in the punctate structures of the mitochondria, and the expression level of YME1L1 is highly expressed from the 4-cell stage. Following significant knock-down of YME1L1, blastocyst rate and quality were decreased, and mitochondrial fragmentation was induced. YME1L1 knockdown induced excessive ROS production, lower mitochondrial membrane potential, and lower ATP levels. The OPA1 cleavage induced by YME1L1 knockdown was prevented by double knock-down of YME1L1 and OMA1. Moreover, cytochrome c, a pro-apoptotic signal, was released from the mitochondria after the knock-down of YME1L1. Taken together, these results indicate that YME1L1 is essential for regulating mitochondrial fission, function, and apoptosis during porcine embryo preimplantation development
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
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Constitutive modeling of pseudoelastic NiTi and its application to structural problems
Nearly equiatomic NiTi exhibits the unique characteristic of pseudoelasticity, i.e. it can be deformed to strain levels of several percent that is fully recoverable on unloading. Under tension, the phase transformation results in strain of nearly 7% and inhomogeneous deformation while the stress remains essentially constant. By contrast, under compression, transformation occurs at a much higher stress, the induced strain is nearly one-half and deformation is essentially homogeneous. These material nonlinearities interact with structural instabilities to produce hitherto unknown intriguing structural responses.
A constitutive modeling framework based on J₂-type kinematic hardening is developed to address the tension/compression asymmetry of pseudoelastic NiTi, including inhomogeneous versus homogeneous deformations. Its performance is then evaluated in the numerical studies of four nonlinear NiTi structures that were previously investigated experimentally.
The first problem considered is the buckling and recovery of an axially compressed NiTi tube. The modeling efforts reproduce the major events observed, including onset of axisymmetric wrinkling, collapse by progressive development of buckling lobes with three circumferential waves, erasure of the lobes and recovery of deformation upon unloading. The study shows that the tension/compression asymmetry plays the key role in bringing the calculated response close to the experimental one and addition of plastic deformation further improves the results. The second problem involves a NiTi strip under tension. The constitutive model properly accounting for softening in the tensile response reproduces the closed hysteresis with two stress plateaus with correct levels and extents, as well as localization of deformation into inclined bands that propagate in the specimen. In the third problem, the constitutive model is used to analyze the tension test of a NiTi tube. The simulation reproduces a closed hysteretic response with two stress plateaus close to the measured one. The tubular geometry of the specimen imposes helical and multi-pronged localization patterns. The last problem studied is the bending of a NiTi tube. The simulation reproduces the major features of the experimental results: the hysteretic moment-end rotation response with two plateaus; localization of curvatures; progressive development of diamond patterns of higher strain on the tensioned side and the nearly homogeneous deformation on the compressed side.Engineering Mechanic
A finite-strain model for a superelastic NiTi shape memory alloy
A finite-strain constitutive model of a superelastic NiTi shape memory alloy is proposed in this paper. Via backward Euler implicit integration scheme and the incorporation of material softening, the model is implemented into finite element code to reproduce a Lüders like deformation of a superelastic NiTi. The simulation results are in agreement with the experimental results, indicating that the constitutive model can reasonably predict the mechanical behavior of a superelastic NiTi. A parametric study further verifies that the magnitude of softening modulus has a significant effect on the stress-strain response and Lüders-like deformation of a superelastic NiTi
Thermomechanical modeling on the crack initiation of NiTi shape memory alloy
The fracture of shape memory alloys is distinct from that of conventional metals, owing to the coexistence and interaction of multiple special features such as martensitic transformation, dislocation-induced plasticity, thermomechanical coupling and others. In this paper, the impact of thermomechanical behavior upon the crack initiation of a NiTi shape memory alloy under Mode I loading is investigated numerically and verified experimentally. A constitutive model incorporating phase transformation, plasticity and thermomechanical coupling is established. Via backward Euler integration and finite-element implementation, the longitudinal strain, martensite volume fraction and temperature field in the vicinity of the crack tip are furnished. The effects of grain size and loading rate on J-integral are revealed. The grain size dependence of crack initiation is non-monotonic. For the samples with grain sizes of 1500 nm, 18 nm and 10 nm, the shielding effect takes place in front of the crack. Additionally, the anti-shielding effect is detected for samples with grain sizes of 80 nm and 42 nm. The parametric study shows that loading rate imposes limited influence on J-integral, which is attributed to a small scale transformation. The decrement of yield stress and the increment of transformation hardening modulus can alleviate the anti-shielding effect and arouse the shielding effect upon crack initiation. The presented results shed light on the design and fabrication of high toughness phase transformable materials
Numerical simulation study on the relationship between mining heights and shield resistance in longwall panel
A numerical model based on a Continuum-based Distinct Element Method (CDEM) was used to carry out a dynamic simulation of the interaction between shield and rock strata movement in longwall mining. In Northern China, the Ordos coal field geological conditions and operational characteristics were used as a case example. The CDEM was constructed on Ordos coal field shield’s operation characteristics and geological conditions. Numerical modelling was carried out to investigate the effects of different mining heights on the caving process, movement characteristics, equilibrium and stability conditions of overburden as the interaction between shield and surrounding rocks. With the numerical model, the internal factors for changes in shield resistance under different mining heights was found. The quantitative relationship between mining heights and shield resistance was also obtained by the numerical simulation. Keywords: Numerical simulation, Shield resistance, Interaction between shield and surrounding rock, Mining height
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