Crack mechanism and experimental verification on straightening of AZ31B magnesium alloy plate.

When plates with edge cracks in the rolling process is straightened by cyclic tensile and compressive stress, the tip of edge crack always accompanied by stress concentration, which leads to crack propagation. In this paper, damage parameters are imported into the plate straightening model based on determining the GTN damage parameters of magnesium alloy materials by inverse finite element calibration method, the influence of different straightening process schemes and prefabricated V-shaped crack geometry on crack growth is analyzed through the way of the combination of simulation and straightening experiment. The results show that the peak values of equivalent stress and equivalent strain under each straightening roll appear at the crack tip. The value of longitudinal stress and equivalent stain decrease with the distance to crack tip becomes larger. The peak value of longitudinal stress appears when the crack circumferential angle is about 100°, and the crack tip is easy to form crack propagation; when the plate passes roll 2 and roll 4, the equivalent stress and strain concentration at the crack tip are most obvious; when the reduction reaches a certain degree, the void volume fraction (VVF) reaches the VVF of the material breaking; with the increase of the entrance reduction, the number of VVF at the crack tip which reaches the material fracture increases, and the length of crack propagation increases; the stress concentration at the tip of V-shaped crack with large length-width ratio is obvious, and the VVF is more likely to reach the VVF at the time of material fracture, crack initiates and propagates easily.

Changes in and Recognition of Electrochemical Fingerprints of Acer spp. in Different Seasons.

Electroanalytical chemistry is a metrological analysis technique that provides information feedback by measuring the voltammetric signal that changes when a molecule is involved in an electrochemical reaction. There is variability in the type and content of electrochemically active substances among different plants, and the signal differences presented by such differences in electrochemical reactions can be used for plant identification and physiological monitoring. This work used electroanalytical chemistry to monitor the growth of three Acer spp. This work explores the feasibility of the electrochemical analysis technique for the physiological monitoring of highly differentiated plants within the genus and further validates the technique. Changes in the electrochemical fingerprints of A. cinnamomifolium, A. sinopurpurascens and A. palmatum 'Matsumurae' were recorded during the one-year developmental cycle. The results show that the differences in the electrochemical fingerprint profiles of Acer spp. can be used to distinguish different species and identify the growth status in each season. This work also concludes with an identification flowchart based on electrochemical fingerprinting.

Over 30 Years of Misidentification: A New Nothospecies Lycoris × jinzheniae (Amaryllidaceae) in Eastern China, Based on Molecular, Morphological, and Karyotypic Evidence.

Based on the complete chloroplast genome, morphology, and karyotype evidence, we identified a new nothospecies, Lycoris × jinzheniae S.Y. Zhang, P.C. Zhang & J.W. Shao, in eastern China. This new nothospecies has been inappropriately named Lycoris × albiflora in the previous literature for more than 30 years. However, the new nothospecies resulted from the hybridization of L. sprengeri and L. chinensis and had the following characteristics: the karyotype was 2n = 19 = 3V + 16I, the leaves emerged in the spring, the ratio of filament to corolla length was approximately 1.2, tepals were slightly undulated and curved, and it was distributed throughout eastern China. These characteristics are quite different from those of L. × albiflora; thus, in this study, we named it and provided a detailed morphological description and diagnosis.

Quantification of Silicon in Rice Based on an Electrochemical Sensor via an Amplified Electrocatalytic Strategy.

Silicon plays a very important role in the growth of rice. The study of the relationship between rice and silicon has become a hot area in the last decade. Currently, the silica-molybdenum blue spectrophotometric method is mostly used for the determination of silicon content in rice. However, the results of this method vary greatly due to the different choices of reducing agents, measurement wavelengths and color development times. In this work, we present for the first time an electrochemical sensor for the detection of silicon content in rice. This electrochemical analysis technique not only provides an alternative detection strategy, but also, due to the rapid detection by electrochemical methods and the miniaturization of the instrument, it is suitable for field testing. Methodological construction using electrochemical techniques is a key objective. The silicon in rice was extracted by HF and becomes silica after pH adjustment. The silica was then immobilized onto the glassy carbon surface. These silica nanoparticles provided additional specific surface area for adsorption of sodium borohydride and Ag ions, which in turn formed Ag nanoparticles to fabricate an electrochemical sensor. The proposed electrochemical sensor can be used for indirect measurements of 10-400 mg/L of SiO2, and thus, the method can measure 4.67-186.8 mg/g of silicon. The electrochemical sensor can be used to be comparable with the conventional silicon-molybdenum blue spectrophotometric method. The RSD of the current value was only 3.4% for five sensors. In practical use, 200 samples of glume, leaf, leaf sheath and culm were tested. The results showed that glume had the highest silicon content and culm had the lowest silicon content. The linear correlation coefficients for glume, leaf, leaf sheath and culm were 0.9841, 0.9907, 0.9894 and 0.993, respectively.

Infrageneric phylogenetics investigation of Chimonanthus based on electroactive compound profiles.

Voltammetric scan can record the profile of electrochemical active substances in plant tissues. Because the distribution of chemical components in plants is controlled by genes, these profiles can reflect differences at the genetic level in different species. In this study, the voltammetric scan was applied to the investigation of macrophanerophytes taxonomy. All species of Chimonanthus with two exotaxa were deliberately selected due to their controversial infrageneric relationship. Electrode surface modification was excluded in this work to improve the convenience and accuracy of the fingerprint recording process. The dendrogram deduced from the electrochemical fingerprint data suggests that Ch. Zhejiangensis and Ch. grammatus are two groups of Ch. nitens, which may be only the ecotype of Ch. nitens, rather than independent taxonomic species. The small variations between the three species may be due to environmental factors and cannot be used for species formation. In addition, Ch. campanulatus and Ch. Praecox were clustered together with a close relationship.

An electrochemical method for plant species determination and classification based on fingerprinting petal tissue.

The identification of plant species not only is a hobby but also has important application value in plant resources science. Traditional plant identification often relies on the experience of botanists. The infrageneric identification of plants is easily mistaken due to similarities in organ features. In this work, we propose an electrochemical method to obtain fingerprints of plant petal tissue. Fourteen species of Lycoris were used as a model for validating this methodology. Pattern and color recognition were established for visualization of electrochemical fingerprints recorded after various solvent extractions. In addition, the infrageneric relationships of these Lycoris species were deduced from the electrochemical fingerprints since the type and content of electroactive compounds in plants are controlled by genes. The results indicate that the electrochemical fingerprints of Lycoris petals are correlated with the infrageneric relationships of native Lycoris species.

Enhanced electrochemical voltammetric fingerprints for plant taxonomic sensing.

Graphene-embedded plant tissues show a high sensitivity to electrochemical signals, which enables a screen-printed electrode to be used for electrochemical fingerprint recording. The electrochemical fingerprints obtained under different conditions can be transformed into multidimensional recognition modes for plant identification. These electrochemical fingerprints reflect the types and quantities of the electrochemically active substances in plant tissues such that the fingerprints can be used for chemotaxonomic investigations. In this paper, five species of Lycoris bulbs, including L. chinensis, L. radiate, L. aurea, L. sprengeri and L. straminea, were successfully recognized by electrochemical fingerprinting. The species's interspecific relationships were also investigated. L. chinensis and L. aurea show highly similar morphology but have a relatively distant relationship. Hybridized L. radiata shows a notably close relationship with L. straminea, suggesting that one of its parents may be L. radiata. In addition, L. chinensis also shows a close relationship with L. straminea, suggesting that the L. straminea may be produced by cross-breeding L. chinensis and L. radiate. The results mentioned above indicate that the proposed electro-chemotaxonomic methodology is an inexpensive and quick taxonomic method that can provide additional evidence for the existing taxonomy system.