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The plastic strain accommodation and recrystallization behavior of the medium-entropy alloy (MEA) CoCrNiCux (x = 0, 0.66, 1 in molar ratio) were investigated. The addition of Cu induced phase separation phenomenon due to the positive mixing enthalpy of Cu with other constituent elements. This resulted in an alteration of the microstructure from a single solid-solution face-centered cubic (FCC) structure to Cu-lean FCC1 and Cu-rich FCC2 phases. Here, a higher recrystallization concentration in the Cu-rich region was observed compared to that of Cu-lean region. This occurred due to the lower hardness of Cu-rich region than Cu-lean region, which caused a greater plastic strain was accommodated in the Cu-rich region than in the Cu-lean region. Consequently, Cu-rich region tended to be more extensively recrystallized compared to that of Cu-lean region.

Facebook has the most active users as compared to any other social network. Despite its popularity, in recent years Facebook has been criticized for failing to develop user experience ("UX") continually. This failure resulted in a decrease in active users. In this study, 20 students and workers were interviewed to explore how Facebook users are currently using the app and changes that they experienced from their initial usage. The data generated by these interviews revealed not only challenges but also opportunities related to the user experience of social networks. This study would provide insights into the latest UX problems associated with the use of social networks and design guidelines for UX designers to overcome these problems as well.

Direct analysis of melamine using reverse phase chromatography is a challenge because this compound's small size and strong polar nature leads to abnormal peak symmetry as well as poor retention. Here, we introduce a simple and reliable reverse phase liquid chromatographic method using sodium hexafluorophosphate to modify an acidic aqueous eluent, resulting in improved chromatographic behaviors of melamine in complex food matrices. Variables affecting the retention mechanism, including chaotrope type, concentration and stationary phase, were investigated. Under optimum conditions, melamine retention, separation efficiency, peak shape and reproducibility were significantly improved as compared to other methods that use ionic liquids or a micellar mobile phase. No interference affected melamine detection when infant formula was applied as the food matrix. Analytical reliability was demonstrated through estimation of validation parameters such as specificity, linearity, precision, accuracy and recovery. This method is suitable for routine analysis of melamine in infant formula. More noteworthy, this is the first time that an organic solvent-free mobile phase using chaotropic salt, meeting the concept of green chemistry, has been proposed.

A novel green aqueous mobile phase modified with room temperature ionic liquids (RTILs) was employed in the absence of volatile organic solvents or ion-pairing reagents to analyze thiamine, a very polar compound, by reverse phase high performance liquid chromatography (RP-HPLC). Due to its strongly hydrophilic nature, thiamine was eluted near the column dead time (t0) using a mobile phase without adding RTILs or ion-pairing reagents, even if a 100% aqueous mobile phase, which has weak elution power under reverse phase conditions, was used. Thus, 1-ethyl-3-methyl-imidazolium hexafluorophosphate ([EMIM][PF6]), which has the strongest chaotropic effect, was selected as a mobile phase additive to improve retention and avoid baseline disturbances at t0. Various mobile phase parameters such as cation moiety, chaotropic anion moiety, pH and concentration of RTILs were optimized to determine thiamine at the proper retention time. Method validation was performed to assess linearity, intra- and inter-day accuracy and precision, recovery and repeatability; all results were found to be satisfactory. The developed method was also compared to the current official United States Pharmacopoeia (USP) and Korean Pharmacopoeia (KP) methods using an organic mobile phase containing an ionpairing reagent by means of evaluating various chromatographic parameters such as the capacity factor, theoretical plate number, peak asymmetry and tailing factor. The results indicated that the proposed method exhibited better efficiency of thiamine analysis than the official methods, and it was successfully applied to quantify thiamine in pharmaceutical preparations.