Morphology and adhesion strength in electroless Cu metallized AlNsubstrate

[[abstract]]The metallization of aluminum nitride substrates by electroless copper plating is investigated. The AlN substrate is etched by 4% NaOH to study the correlation between the adhesion strength and the surface roughness of etched AlN substrate. Both the as-received nonpolished and the polished AlN are studied. For the nonpolished substrate, the adhesion strength increases from 130 kg/cm2 for the sample with an average surface roughness of 0.2 μm to 230 kgf/cm2 for one with an average surface roughness of 0.82 μm. For the polished substrate, the adhesion strength reaches 271 kg/cm2 with a surface roughness of 0.19 μm. Mechanical interlocking is the major cause for the adhesion strength between the Cu and AlN substrates. The polished substrate that was subsequently etched could form fine cavities on the AlN surface, and the microetching effect resulted in a stronger mechanical interlocking, which increases the adhesion strength[[fileno]]2020323010153[[department]]材料科學工程學

Using M-integral for multi-cracked problems subjected to nonconservative and nonuniform crack surface tractions

AbstractIn this paper, an energy parameter based on the concept of the M-integral is proposed for describing the fracture behavior of a multi-cracked solid subjected to nonconservative and nonuniform crack surface tractions. By using the M-integral with a suitably chosen closed contour, one can evaluate the ‘surface creation energy’ (SCE) required for creation of the stressed cracks. Also, it is demonstrated that the property of path-independence holds even under the action of crack surface tractions. Therefore, the singular stress field in the near-tip areas is not directly involved in the calculation so that a complicated finite element model around the crack tips is not required in evaluation of the M-integral

Calculation of near-tip non-singular stresses for pressurized cracks

AbstractWhen the crack surfaces are traction-free, there is only one constant term T in the near-tip stress field, which contributes uniformly to the stress component acting in the direction parallel to the crack flank. As to pressurized cracks, the non-singular part of the asymptotic stresses appears to be more complicated and is no longer characterized only by the constant T. In this work, an effective numerical approach is developed for calculation of the non-singular parts of the asymptotic near-tip stresses under the action of nonuniform crack surface pressures. With this approach, the near-tip non-singular stress field can be accurately evaluated by direct use of regular numerical methods such as finite elements

An immunohistochemical study of the pancreatic endocrine cells of the Korean golden frog, Rana plancyi chosenica

The regional distribution and quantitative frequency of pancreatic endocrine cells were demonstrated in the Korean golden frog (Rana plancyi chosenica Okada), which is known as a Korean endemic species, for the first time by immunohistochemical methods using specific mammalian antisera to insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). In the pancreas of the Korean golden frog, all four endocrine cell types were demonstrated. Insulin- and glucagon-positive cells were located in the pancreas as single cells or islet-like clusters, respectively. Somatostatin-containing cells were also dispersed in the pancreas as single cells or clusters but in the case of clusters, they are exclusively situated in the marginal regions of insulin- or glucagon-positive cell clusters. PP-containing cells were also distributed as single cells or clusters. Clusters consisted of PP-positive cells are distributed as a core type and a marginally distributed type. Overall, there were 40.84±3.81% insulin-, 26.02±1.71% glucagon-, 7.63±2.09% somatostatin- and 25.51±3.26% PP-IR cells

Adhesion patterns of Neisseria lactamica and its implications.

Neisseria Meningitidis is a pathogenic bacteria responsible for a wide range of serious disease, including septsis and meningitis especially in children and infants. In contrast Neisseria lac/arnica which resides m the same ecological niche as N.meningitidis, the nasopharynx, does not cause disease and is commensal. It was found that the two species of Neisseria have converse carriage rates where N.lactamica has a protecthe role <ner N.meningitidis colonization in infants. The two species have similar structural components and genes but very different pathogenesis. It is clear that N.meningitidis adheres and invades host cells whereas N.lactamica does not invade. Adhesion of N.lactamica seems to occur mostly around the sides of the cell rather than the apex or base. Adhesion numbers of N.lactamica increase with time of infection with a greater increase from 4 to 6 hours rather than 2 to 4 hours of infection. Adhesion rates in relation to N.meningitidis adhesion numbers were less which may be dye to greater adhesive ability of As meningitidis. Inhibitor treatment of epithelial cells and thus, a decrease in cellular inflammatory response, resulted in agre-Mei J gree of adhesion and again from 4 to 6 hours, the increase in adhesion numbers mere vi eater than from. 2 to 4 hours. Supernatant quantifications showed an increase in N.Lietantiea with time,which may reflect growth of bacteria dining the course of infection. Further experimentations with advanced techniques such as con focal microscopy and more repeats of the gentamycin assay would yield more promising results. Also, the analysis of supernatant for inflammatory mediators, bactericidal compounds, and bacterial by products is necessary in order to determine the dynamics of adhesion of N.lactamica

The Effect of ePortfolio Satisfaction on Students’ Learning Motivation and Internet Self-efficacy

This study aims to investigate the effect of e-Portfolio satisfaction on students’ learn­ing motivation and Internet self-efficacy toward the use of e-Portfolio. The data collected for this study occurred over 3 months. Participants were 450 students taking the course of common at an university. The counting of 443 questionnaires was received. The findings revealed that there were positive correlations between learning motivation, Internet self-efficacy, and e-Portfolio satisfac­tion. For gender, the result showed that there were no significant Internet self-efficacy differences between gender. Besides, there were the significant differences in learning motivations and in Internet self-efficacy between the two groups. Furthermore, the multistep regression analysis in­dicated that the learning motivation was the significant predictor of Internet self-efficacy, and In­ternet self-efficacy was the significant predictor of e-Portfolio satisfaction. Based on the findings, educators and researchers needed to pay attention to these influences and take these factors into consideration in e-Portfolio. The study concludes by assessing the overall gains and shortcomings of the reform effort toward using the e-Portfolio to help student self-learning

Evolving temporal association rules with genetic algorithms

A novel framework for mining temporal association rules by discovering itemsets with a genetic algorithm is introduced. Metaheuristics have been applied to association rule mining, we show the efficacy of extending this to another variant - temporal association rule mining. Our framework is an enhancement to existing temporal association rule mining methods as it employs a genetic algorithm to simultaneously search the rule space and temporal space. A methodology for validating the ability of the proposed framework isolates target temporal itemsets in synthetic datasets. The Iterative Rule Learning method successfully discovers these targets in datasets with varying levels of difficulty

Stepwise addition of chemical reagents for enhancing electrokinetic removal of cu from real site contaminated soils

In this study, a circulation-enhanced electrokinetics (CEEK) system integrated with the stepwise addition of chemical reagents was used to remediate copper-contaminated soils collected from a real site. At first, an optimal extraction process of different chemical reagents was found to obtain the highest copper removal efficiency by conducting batch extraction experiments. The chemical reagents served as extracts including EDTA, NaOH, and sodium dithionite + sodium citrate. Then, CEEK integrated this optimal extraction, that is, the treatment of 6-day EDTA, NaOH, EDTA, sodium dithionite + sodium citrate, and EDTA in a series. According to experimental results, the NaOH and sodium dithionite + sodium citrate could effectively facilitate the copper removal during the extraction and electrokinetics (EK) processes. The optimal extraction process for this real contaminated soil (94% copper removal efficiency) was the alternative extraction of EDTA, NaOH, and sodium dithionite + sodium citrate. The copper removal efficiency of the real contaminated soil could reach around 55% after 30-day CEEK treatment. The continuous decline of soil copper concentration of this integrated EK technique could be achieved as the remediation time was extended sufficiently

Dynamics of the Compact, Ferromagnetic \nu=1 Edge

We consider the edge dynamics of a compact, fully spin polarized state at filling factor $\nu=1$. We show that there are two sets of collective excitations localized near the edge: the much studied, gapless, edge magnetoplasmon but also an additional edge spin wave that splits off below the bulk spin wave continuum. We show that both of these excitations can soften at finite wave-vectors as the potential confining the system is softened, thereby leading to edge reconstruction by spin texture or charge density wave formation. We note that a commonly employed model of the edge confining potential is non-generic in that it systematically underestimates the texturing instability.Comment: 13 pages, 7 figures, Revte

Top Quark Decays into Heavy Quark Mesons

For top quark decays into heavy quark mesons $\Upsilon$ and $\bar{B}_c^*$ , a complete calculation to the leading order both in QCD coupling constant $\alpha_s$ and in $v$, the typical velocity of the heavy quarks inside the mesons, is performed. Relatons between the top quark mass and the decay branching ratios are studied. Comparion with the results which are obtained by using the quark frangmentation functions is also discussed. The branching ratios are consistent (within a factor of $2\sim 3$) with that obtained using fragmentation functions at $m_t\sim 150$ GeV.Comment: 15 pages in LaTex form, 4 figures include