On the spheroidal graphite growth and the austenite solidification in ductile irons

Evolutions of austenite and nodular/spheroidal graphite particles during solidifications of ductile irons were experimentally investigated. Spheroidal graphite particle and austenite dendrite were found nucleated independently in liquid. Austenite dendrite engulfed the spheroidal graphite particles after contact and an austenite shell formed around a spheroidal graphite particle. The graphite diameter at which the austenite shell closed around nodule was determined. Statistically determined graphite size distributions indicated multiple graphite nucleation events during solidification. Structures in a graphite nodule varied depending on the growth stages of the nodule in ductile iron. Curved graphene layers appearing as faceted growth ledges swept circumferentially around the surface of a graphite nodule at early growth stages. Mismatches between the growth fronts created gaps which divided a nodule into radially oriented conical substructures (3-D). Columnar substructure was observed in the periphery of a nodule (formed during the intermediate growth stages) on its 2-D cross section. A columnar substructure consisted of parallel peripheral grains, with their c-axes approximately parallel. Graphene layers continued building up in individual conical substructure, and a graphite nodule increased its size accordingly. Method for characterizing the crystal structures of graphite based on the selected area diffraction pattern was developed. Both hexagonal structure and rhombohedral structure were found in the spheroidal graphite particles. Possible crystallographic defects associated with hexagonal-rhombohedral structure transition were discussed. Schematic models for introducing tilt angles to the graphite lattice with basal plane tilt boundaries were constructed --Abstract, page iv

Puerarin mitigates acute liver injury in septic rats by regulating proinflammatory factors and oxidative stress levels

Purpose: To determine the protective effect of puerarin against acute liver injury in septic rats, and the mechanism involved.Methods: Eighty-seven Sprague-Dawley (SD) rats were assigned to control, sepsis and puerarin groups (each having 29 rats). Serum levels of NF-kB, TNF-α, IL-1 β, IL-6, ALT and AST were assayed. Liver lesions and levels of NO, SOD, iNOS and malondialdehyde (MDA) were measured using standard procedures.Results: Compared with the control group, the levels of NF-kB, TNF-α, IL-1β, IL-6, AST, ALT, NO, MDA and iNOS significantly increased in the sepsis group, while SOD level decreased significantly. In contrast, there were marked decreases in NF-kB, TNF-α, IL-1β, AST, ALT, NO, MDA and iNOS in puerarin group, relative to the sepsis group, while SOD expression level was significantly increased (p <0.05). The level of p-p38 in liver of septic rats was up-regulated, relative to control rats, while Nrf2 significantly decreased (p < 0.05). The expression level of p-p38 in the puerarin group was significantly decreased, relative to the sepsis group, while the expression level of Nrf2 significantly increased (p < 0.05).Conclusion: Puerarin mitigates acute liver injury in septic rats by inhibiting NF-kB and p38 signaling pathway, down-regulating proinflammatory factors, and suppressing oxidative stress. Thus, puerarin may be developed for use in the treatment liver injury

Engineering Heterogeneous Nucleation During Solidification Of Multiphase Cast Alloys: An Overview

The theory of heterogeneous nucleation was initially developed as a part of condensed matter physics, and later it was used as an important engineering tool to design metallurgical processes. This success has led to wide applications of the theory in metallurgical practice. For example, engineering heterogeneous nucleation in ductile iron has been used to reduce shrinkage defects, suppress cementite formation, and modify the size and shape of microstructural constituencies. This demonstrates how theoretical knowledge could benefit industry practice. This overview aims to summarize the authors\u27 published studies in co-authorship with colleagues and students, which covers different aspects of engineering heterogeneous nucleation in multiphase cast alloys. Several approaches for engineering heterogeneous nucleation using thermodynamic simulation as well as practical methods for improving efficiency of nucleation using the co-precipitation technique and a local transient melt supersaturation are suggested. Automated scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis and high-resolution transmission electron microscopy (TEM) were used to verify the simulation predictions. Practical examples of controlling microporosity shrinkage in cast irons with spheroidal graphite are presented to illustrate the power of engineering heterogenous nucleation

Synthesis, characterization, and antifungal evaluation of novel 1,2,3-triazolium-functionalized starch derivative

1,2,3-Triazolium-functionalized starch derivative was obtained by straightforward quaternization of the synthesized starch derivative bearing 1,2,3-triazole with benzyl bromide by combining the robust attributes of cuprous-catalyzed azide-alkyne cycloaddition. These novel starch derivatives were characterized by FTIR, UV-vis, H-1 NMR, C-13 NMR, and elemental analysis. Their antifungal activities against Colletotrichum lagenarium, Watermelon fusarium, and Phomopsis asparagi were investigated by hypha measurement in vitro. The fungicidal assessment revealed that compared with starch and starch derivative bearing 1,2,3-triazole with inhibitory indices of below 15% at 1.0 mg/mL, 1,2,3-triazolium-functionalized starch derivative had superior antifungal activity with inhibitory rates of over 60%. Especially, the best inhibitory index of 1,2,3-triazolium-functionalized starch derivative against Colletotrichum lagenarium attained 90% above at 1.0mg/mL. The results obviously showed that quaternization of 1,2,3-triazole with benzyl bromide could effectively enhance antifungal activity of the synthesized starch derivatives. The synthetic strategy described here could be utilized for the development of starch as novel antifungal biomaterial. (C) 2017 Elsevier B.V. All rights reserved

Synthesis and Antioxidant Activity of Cationic 1,2,3-Triazole Functionalized Starch Derivatives

In this study, starch was chemically modified to improve its antioxidant activity. Five novel cationic 1,2,3-triazole functionalized starch derivatives were synthesized by using "click" reaction and N-alkylation. A convenient method for pre-azidation of starch was developed. The structures of the derivatives were analyzed using FTIR and H-1 NMR. The radicals scavenging abilities of the derivatives against hydroxyl radicals, DPPH radicals, and superoxide radicals were tested in vitro in order to evaluate their antioxidant activity. Results revealed that all the cationic starch derivatives (2a-2e), as well as the precursor starch derivatives (1a-1e), had significantly improved antioxidant activity compared to native starch. In particular, the scavenging ability of the derivatives against superoxide radicals was extremely strong. The improved antioxidant activity benefited from the enhanced solubility and the added positive charges. The biocompatibility of the cationic derivatives was confirmed by the low hemolytic rate (<2%). The obtained derivatives in this study have great potential as antioxidant materials that can be applied in the fields of food and biomedicine

PP-MeT: a Real-world Personalized Prompt based Meeting Transcription System

Speaker-attributed automatic speech recognition (SA-ASR) improves the accuracy and applicability of multi-speaker ASR systems in real-world scenarios by assigning speaker labels to transcribed texts. However, SA-ASR poses unique challenges due to factors such as speaker overlap, speaker variability, background noise, and reverberation. In this study, we propose PP-MeT system, a real-world personalized prompt based meeting transcription system, which consists of a clustering system, target-speaker voice activity detection (TS-VAD), and TS-ASR. Specifically, we utilize target-speaker embedding as a prompt in TS-VAD and TS-ASR modules in our proposed system. In constrast with previous system, we fully leverage pre-trained models for system initialization, thereby bestowing our approach with heightened generalizability and precision. Experiments on M2MeT2.0 Challenge dataset show that our system achieves a cp-CER of 11.27% on the test set, ranking first in both fixed and open training conditions