The Effect of Potassium Dodecyl Xanthate on the Stability of Sphalerite Suspensions

The effect of potassium dodecyl xanthate (KDX) on the coagulation, dispersion and flotation recovery of sphalerite in aqueous suspensions is investigated by means of adsorption isotherm, electrokinetic measurement and pneumatic flotation test. The degree of coagulation and the flotation recovery increase with increasing KDX concentration, approaching a maximum at the coverage corresponding approximately to a close-packed monolayer of KDX on the surface of sphalerite, and then decrease as the adsorption of KDX proceeds to the bimolecular layer. The coagulation mentioned above is interpreted not by the decrease of the electrical repulsion between particles caused by the lowering of the ζ-potential, but by the hydrophobic modification of the surface of sphalerite due to the oriented adsorption of KDX. The dispersion may be due to the hydrated surface caused by the double adsorbed layer with polar groups directed towards the solution and the increase of the ζ-potential of particles. The KDX concentration at which the dispersion occurs is correlated to the cmc of KDX. The relation between the stability of suspensions and the hydrophobic or hydrophilic nature of particles is discussed on the basis of the Hamaker-Vold theory concerning the van der Waals\u27 forces between colloid particles

The background factor of the driving compensation behavior among elderly drivers

The purpose of this study is to examine what factors lead to driving compensation behavior among elderly drivers, particularly focusing on the effect of self-reported driving performance, and to investigate the relationship between driving compensation behavior and traffic accidents or violations. After analyzing 237 elderly drivers, the results showed that whereas self-reported driving performances influenced driving compensation behaviors, the relationship between self-reported driving performances and driving compensation behaviors contradicted because of the differences in driving behaviors. Furthermore, the results indicated that the driving compensation behaviors were effective in preventing traffic accidents and violations

Freshwater mussels (Bivalvia: Unionidae) from the rising sun (Far East Asia): phylogeny, systematics, and distribution

Freshwater mussels (Bivalvia: Unionidae) is a diverse family with around 700 species being widespread in the Northern Hemisphere and Africa. These animals fulfill key ecological functions and provide important services to humans. Unfortunately, populations have declined dramatically over the last century, rendering Unionidae one of the world’s most imperiled taxonomic groups. In Far East Asia (comprising Japan, Korea, and Eastern Russia), conservation actions have been hindered by a lack of basic information on the number, identity, distribution and phylogenetic relationships of species. Available knowledge is restricted to studies on national and sub-national levels. The present study aims to resolve the diversity, biogeography and evolutionary relationships of the Far East Asian Unionidae in a globally comprehensive phylogenetic and systematic context.We reassessed the systematics of all Unionidae species in the region, including newly collected specimens from across Japan, South Korea, and Russia, based on molecular (including molecular species delineation and a COI + 28S phylogeny) and comparative morphological analyses. Biogeographical patterns were then assessed based on available species distribution data from the authors and previous reference works.We revealed that Unionidae species richness in Far East Asia is 30% higher than previously assumed, counting 43 species (41 native + 2 alien) within two Unionidae subfamilies, the Unioninae (32 + 1) and Gonideinae (9 + 1). Four of these species are new to science, i.e. Beringiana gosannensis sp. nov., Beringiana fukuharai sp. nov., Buldowskia kamiyai sp. nov., and Koreosolenaia sitgyensis gen. & sp. nov. We also propose a replacement name for Nodularia sinulata, i.e. Nodularia breviconcha nom. nov. and describe a new tribe (Middendorffinaiini tribe nov.) within the Unioninae subfamily. Biogeographical patterns indicate that this fauna is related to that from China south to Vietnam until the Mekong River basin. The Japanese islands of Honshu, Shikoku, Kyushu, Hokkaido, and the Korean Peninsula were identified as areas of particularly high conservation value, owing to high rates of endemism, diversity and habitat loss. The genetically unique species within the genera Amuranodonta, Obovalis, Koreosolenaia gen. nov., and Middendorffinaia are of high conservation concern

Prior practice in special breathing technique improves behavior in emergencies

We investigated the effects of a special breathing technique, the “Breathing Retraining technique,” on performance in emergency situations. Participants were divided into three groups: the breathing method group, the visual task group, and the control group. Participants in the breathing method group performed the Breathing Retraining technique, those in the visual task group performed a simple visual task, and those in the control group performed a random task before performing the main one. The main task was the water-pipe game, whereby participants clicked on a computer mouse in various situations and aimed to complete the game using the minimum number of clicks. Results indicated that the breathing method group accomplished the most difficult main tasks faster and more efficiently than the other groups in simulated emergency situations. These results suggest that people can work comparatively fast and efficiently even in emergency situations by practicing the Breathing Retraining technique beforehand. Additionally, there were no significant differences between the visual task group and the control group. This result indicates that it is not helpful to merely wait for an emergency; practicing the right breathing technique in advance helps individuals perform better in emergency situations

Comparing the self-assessed and examiner-assessed driving skills of Japanese driving school students

Previous research about subjective driving skills has revealed that drivers, especially younger males, tend to rate their driving skills more highly than those of the average driver. This study examines the accuracy of Japanese novice drivers' self-evaluation of their driving skills by comparing their self-assessments with assessments made by a driving examiner. We also examined the effects of gender and age on the accuracy of driver self-evaluation of their skills. A sample of Japanese driving test candidates (n=2021) completed a self-assessment using a 5-point scale applied to 19 items. The candidates completed the assessment shortly after passing their practical driving test conducted at a driving school. Their performance was also assessed by an examiner who used the same scale. The comparison between self-assessment and examiner-assessment revealed that around 40% of Japanese driving school students made a realistic assessment of their skills. With regard to the gender differences, although males displayed higher levels of overconfidence than females did, the differences were not as large as earlier studies with questionnaires had suggested. Furthermore, the effect of age on the accuracy of novice drivers' skill assessment was found to be relatively small. Our findings, which are based on a comparison of subjective assessments of driving skills between examiners and novices, instead of a questionable method which relies on a comparison with a hypothetical average driver, suggest that the majority of candidates in fact do not overrate their own skills. These results were discussed from the viewpoint of the driver education system and compared to other European research using the same framework