A simple spectrofluorimetric method is described for the determination of buparvaquone (BPQ), based on its quenching effect on the fluorescence intensity of Tb3+–deferasirox (DFX) complex as a fluorescent probe. The excitation and emission wavelengths were 328 and 545 nm, respectively. The optimum conditions for determination of BPQ were investigated considering the effects of various affecting parameters. The variations in fluorescence intensity of the system showed a good linear relationship with the concentration of BPQ in the range of 10–1500 μg L−1, its correlation coefficient was 0.999 with the detection and quantification limits of 1.1 and 3.4 μg L−1, respectively. Linearity, reproducibility, recovery, limits of detection and quantification made the method suitable for BPQ assay in biological fluids, meat, dairy products and BPQ parenteral solutions (vials). The method was applied to real samples of serum and milk of three cows receiving BPQ. 相似文献
The effect of a novel heat treatment, that is, aging under superimposed external stress, on the fatigue performance and microstructural evolution of a high-strength aluminum alloy (EN AW-7075) is presented. Stress aging, a combination of heat treatment and superimposed external stress, can enhance the mechanical properties of EN AW-7075 under monotonic loading due to the acceleration of precipitation kinetics. Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) reveal that a longer aging time and the presence of superimposed stress both promote the formation and growth of precipitates, that is, the precipitation of strengthening η´ precipitates. This is confirmed by differential scanning calorimetry (DSC) heating experiments of stressless and stress-aged states. Furthermore, stress aging leads to a reduction of dimensions of precipitate-free zones near grain boundaries. Cyclic deformation responses (CDRs) and half-life hysteresis loops are evaluated focusing on the low-cycle fatigue (LCF) performance of different conditions. A noticeable cyclic hardening seen in case of the specimens aged for a short time indicates the occurrence of dynamic strain aging (DSA). Eventually, stress aging allows for an enhancement of the monotonic mechanical properties of EN AW-7075 without degrading the cyclic performance in the LCF regime. 相似文献
Polymerization processes with high reproducibility, traceability, and nontoxic compounds are required for biomedical applications. Here an automated solvent-free polymerization of hyperbranched polyglycerol has been established on a multiple-hundred gram scale. Performed is an anionic ring-opening multibranching (ROMB) polymerization with slow addition of glycidol. The solvent-free approach avoids commonly used organic solvents during the polymerization and work-up. Due to the automation of the polymerization process a high reproducibility and traceability is accomplished. The used reactor is equipped with an anchor stirrer and stirrer control, which measures the applied torque. A linear correlation of the increasing torque and the degree of polymerization is observed, which can be used to monitor the molecular weight in situ during the polymerization. 相似文献
Abstract: Different cryo-EM derived atomic models of in vivo tau filaments from patients with tauopathies consisted of R3 and R4 repeats of the microtubule-binding domain. In comparison, only the R3 repeat forms the core of the heparin-induced fibrils of the three repeat tau isoforms. For developing therapeutics, it is desirable to have an in vitro tau aggregation system producing fibrils corresponding to the disease morphology. Here we report the self-aggregation of truncated tau segment R3R4 peptide without requiring heparin for aggregation induction. We used NMR spectroscopy and other biophysical methods to monitor the self-aggregation of R3R4. We identified the hexapeptide region in R3 and β-turn region in R4 as the aggregation initiating region of the protein. The solid-state NMR of self-aggregated R3R4 fibrils demonstrated that in addition to R3 residues, residues of R4 were also part of the fibril filaments. The presence of both R3 and R4 residues in the aggregation process and the core of fibril filaments suggest that the aggregation of R3R4 might resemble the in vivo aggregation process. 相似文献
Nowadays, the internet of things (IoT) has gained significant research attention. It is becoming critically imperative to protect IoT devices against cyberattacks with the phenomenal intensification. The malicious users or attackers might take control of the devices and serious things will be at stake apart from privacy violation. Therefore, it is important to identify and prevent novel attacks in the IoT context. This paper proposes a novel attack detection system by interlinking the development and operations framework. This proposed detection model includes two stages such as proposed feature extraction and classification. The preliminary phase is feature extraction, the data from every application are processed by integrating the statistical and higher-order statistical features together with the extant features. Based on these extracted features the classification process is evolved for this, an optimized deep convolutional neural network (DCNN) model is utilized. Besides, the count of filters and filter size in the convolution layer, as well as the activation function, are optimized using a new modified algorithm of the innovative gunner (MAIG), which is the enhanced version of the AIG algorithm. Finally, the proposed work is compared and proved over other traditional works concerning positive and negative measures as well. The experimental outcomes show that the proposed MAIG algorithm for application 1 under the GAF-GYT attack achieves higher accuracy of 64.52, 2.38 and 3.76% when compared over the methods like DCNN, AIG and FAE-GWO-DBN, respectively.
In this paper, the stamping process was employed to fabricate metallic bipolar plates (MBPs). An account of low formability of the commercially pure titanium (CP–Ti), the fracture is the most common defect during its plastic deformation. Consequently, prediction of the fracture onset during the stamping was studied using three ductile fracture criteria including Rice-Tracey, Brozzo, Ayada, and a developed forming limit criteria based on consideration of the material size effect. The damage value in the lateral and central channel was evaluated to determine the critical channel and element. According to the results, the most accurate fracture prediction during stamping of titanium bipolar plates could be obtained via Brozzo ductile fracture criteria with an error rate of 3.68% compared to experiments. Moreover, the strain-based criteria represent higher fracture prediction errors compared to damage criteria. The stress state analysis showed the variation of stress triaxiality during the process leading to less accuracy of the strain-based criteria. According to the results, the damage function of the ductile damage criteria was more reliable for the semi-proportional loading path during the stamping of the titanium bipolar plates which makes them more suitable for accurate fracture prediction during the process. 相似文献
Journal of Applied Electrochemistry - In the present work, Ni@Pd core–shell nanoparticles are successfully deposited on multi-walled carbon nanotubes as support and investigated their... 相似文献