D-501036 [2,5-bis(5-hydroxymethyl-2-selenienyl)-3-hydroxymethyl-N-methylpyrrole] is herein identified as a novel antineoplastic agent with a broad spectrum of antitumoral activity against several human cancer cells and an IC 50 value in the nanomolar range. The IC 50 values for D-501036 in the renal proximal tubule, normal bronchial epithelial, and fibroblast cells were >10 Mmol/L. D-501036 exhibited no cross-resistance with vincristine-and paclitaxel-resistant cell lines, whereas a low level of resistance toward the etoposide-resistant KB variant was observed. Cell cycle analysis established that D-501036 treatment resulted in a dose-dependent accumulation in S phase with concomitant loss of both the G 0 -G 1 and G 2 -M phase in both Hep 3B and A-498 cells. Pulsed-field gel electrophoresis showed D-501036 -induced, concentration-dependent DNA breaks in both Hep 3B and A-498 cells. These breaks did not involve interference with either topoisomerase-I and topoisomerase-II function or DNA binding. Rapid reactive oxygen species production and formation of Se-DNA adducts were evident following exposure of cells to D-501036, indicating that D-501036 -mediated DNA breaks were attributable to the induction of reactive oxygen species and DNA adduct formation. Moreover, D-501036 -induced DNA damage activated ataxia telangiectasia -mutated nuclear protein kinase, leading to hyperphosphorylation of Chk1, Chk2, and p53, decreased expression of CDC25A, and up-regulation of p21 WAF1 in both p53-proficient and p53-deficient cells. Collectively, the results indicate that D-501036 -induced cell death was associated with DNA damage -mediated induction of ataxia telangiectasia -mutated activation, and p53-dependent and -independent apoptosis pathways. Notably, D-501036 shows potent activity against the growth of xenograft tumors of human renal carcinoma A-498 cells. Thus, D-501036 is a promising anticancer compound that has strong potential for the management of human cancers.
In this study, a novel procedure has been developed for predicting the notched strengths of composite plates each with a center hole. In this approach, the stress distribution of a composite plate with a center hole is first obtained by a finite element analysis, in which the experimental notched strength is applied at the boundary of the finite element model. Secondly, the point stress criterion (PSC) is used to find the characteristic length for each plate with different size of hole by an interpolation of the finite element analysis results. The characteristic length is then expressed as an empirical function of the hole size as well as the width of the plate. Finally, the notched strengths of composite plates are predicted based on the empirical function and the finite element analysis results incorporated with the principle of superposition in elasticity. For validation, three different cases from the literatures are adopted for comparison. It is shown that the predicted notched strengths by this new methodology agree well with both the experimental results and the results from analytical solutions based PSC.
There are two kinds of microsprings often used: box microsprings and zig-zag (serpentine) microsprings. Box microsprings are considered with larger spring constant k and more symmetric structure keeping balance than zig-zag microspring. Density of spring number, N, is defined as the numbers of turns within a constant total spring length to investigate performance of box microspring. With applying the same force, the relation between spring constants and microspring sizes are discussed. Under different size parameters of box microsprings: B, W, T, and L, the spring constants decrease like exponential decay and approach a limit value as density of spring number increasing. The results show density of spring number has significant effect on spring constant. Rate of change on spring constant, Kt, is defined as the ratio of spring constant between N=1 and N=10. It means normalization of spring constant that increase density of spring number from minimum to maximum. The results show Kt decreases when B and W increase and increase as T and L increasing. Therefore, the spring constant is coupled affected by different size parameters due to different tendency as results shown. Such that the results can apply in microspring design by adjusting these size parameters to obtain the spring constant.
As depositing layers with different thermal expansion coefficients, the residual gradient stress will cause the structure deformed. The deformation of structure in the free ending, middle section, and clamped end are detail investigated. It is found the clamped end often has complex deformation shape. The warpage due to buckling is found. The results show if the thickness of structure is much larger than above deposing layer, warpage will hardly happen and the free ending will have more flat region. As the thickness of structure layer being not much larger than above deposing layer, the warpage happens and the free ending is parabolic shape. In the clamped end, the complex deformation even is concave shape in the center part but protruding shape in the side region. The larger temperature difference will be more easily warpage and be no more flat. The results also show that as the ratio of length to width decreasing, seriously warpage and complex deformation happens. The free ending may be a little protruding shape. However, if the ratio of length to width is larger, the free ending will have concave shape.
Pulse heated reflow soldering is widely used as junction methods of electronic devices such as ACF, HSC, FPC, PCB, TCP, and FFC. Hot bars are the devices used in pulsed heated reflow method to heat and melt the solder materials between devices and wire becoming a junction. Therefore the performance is determined by the welding properties. The welding time, temperature and induced pressure are important factors affecting welding property. And the temperature has the significant effect due to electricity and mechanical property of solder being determined by welding temperature. However, the consistency of temperature is hard to achieve due to complex coupling of driving current, materials property, heat generation, heat conduction and hot bar shape. In this work, different shapes of hot bat are designed to obtain the temperature consistency. Due to the welding requirement, the heating process is a two steps process. And the hot bar is heated by electric current from power supply with feedback control. For assembly purpose, the hot bar is designed as a rectangular plate with circular holes near the other side respect to the heating edge to fasten the hot bar on the welding machine. And the hot bar with polygon hole in the center part would induce the uniform temperature distribution. Four dimensions of the hot bar determine the shape and investigate the temperature consistency: polygon’s sizes and its positions. Some experiments are made to measure the temperature distribution. The results show the shape has significant effect on temperature consistency. Changing the polygon hole positions will alter the temperature distribution. The central part of heating edge will hotter than both ending part initially. And in some cases, during the heating process, the both ending part will have cooler, hotter, and cooler temperature that central part with respect to heating time. The polygon hole sizes have also significant effect on the temperature distribution. They have the similar temperature distribution phenomena as positions effect. Therefore, from the experiments and analysis, the hot bar could have more uniform temperature distribution by shape design. And it is also found the temperature distribution would induce thermal residual stress and deform the hot bar.
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