Surface roughness is a critical factor affecting the performance of dental implants. One approach to influence this is through sandblasted, large grit, acid-etched (SLA) modification on pure titanium implant surfaces. In this study, SLA was performed on grade IV pure titanium. Sandblasting was conducted at distances of 2, 4, and 6 cm. Subsequently, the samples were etched with a mixed acid solution of HCl, H2SO4, and H2O for 0, 30, and 60 min. Surface roughness and X-ray diffraction (XRD) characterizations were conducted on the samples. The results revealed that surface roughness increased but was not too significant as the sandblasting distance decreased. Longer etching durations for sandblasted with acid-etched samples led to reduced surface roughness (Sa and Sz). It was found that a 60 min-etched sample resulted in optimal Sa, Sz, and Ssk values, i.e., 1.19 μm, 13.76 μm, and −0.60, respectively. The XRD texture was significantly influenced by sandblasting, with compressive residual stress increasing as the sandblasting distance decreased. Normal stress causes hill formations at shorter sandblasting distances. For etched samples, the residual stress decreased with longer etching durations. Normal stress-decreasing trend aligns with the initial reduction in hill and valley within the samples and subsequent hill enhancement at extended etching duration.

Les inputs audiovisuels tels que les films et les séries sont de plus en plus souvent utilisés dans les cours de langue étrangère (LE) car ils permettent une exposition authentique à la langue. Plusieurs études suggèrent qu’ils soutiennent l’apprentissage de nouveaux mots, mais que l’inclusion d’activités de pré-/post-visionnage pourrait renforcer cet apprentissage. La présente étude a été menée en Suisse alémanique et s’intéresse à l’effet de la présence et du placement d’une telle activité sur l’apprentissage de 51 mots cibles. Dans une étude within-design, 97 apprenants de français langue étrangère de 13–14 ans ont regardé trois extraits de la série télévisée « Plan Cœur » (Netflix, 2018). Les trois conditions étaient : épisode seul, épisode et activité avant, épisode et activité après. Les activités portaient sur la reconnaissance du sens des mots cibles. Trois post-tests immédiats et un post-test différé du même type (reconnaissance de sens) ont été effectués auprès des quatre classes de niveau scolaire supérieur (classes générales et prégymnasiales/GPG) et des deux classes de niveau scolaire inférieur (classes à exigences de base/EBA). Nos résultats confirment la supériorité des conditions avec activité ainsi qu’une différence (peu surprenante) selon le niveau scolaire. On trouve aussi une interaction entre le moment de test et condition avec plus de réponses correctes aux post-tests immédiats. La différence entre activité pré et post est cependant négligeable. Ces résultats soulignent l’importance des activités pré-/post-visionnage pour l’apprentissage de nouveaux mots en LE.

This study originates from my curiosity to explore a different Latin teaching approach to address some students’ misconception that Latin is an unnecessarily complicated language that no one speaks anymore.

In the present study we challenge the generally accepted view based primarily on L1 data that surface linguistic information decays rapidly during reading and that only propositional information is retained in memory. In two eye-tracking experiments, we show that both L1 and L2 adult readers retain verbatim information of a text. In particular, the reading behaviour of L2 German learners revealed that they were sensitive to both lexical (synonyms) and syntactic (active/passive alternation) substitutions during a second reading of the texts, while L1 exhibited only reduced sensitivity to the lexical substitutions. The results deliver an important piece of evidence that complies with several current processing (e.g., Shallow Structure Hypothesis), acquisition (Declarative/Procedural Model) and cognitive (e.g., Fuzzy Trace Theory) approaches and adds a new dimension to their empirical and theoretical basis.

The functional composition of plant communities in montane regions has been studied for decades, and most recent analyses find that environmentally favourable landscapes at lower altitudes tend to be dominated by species with resource-acquisitive traits, while more resource-conservative taxa dominate higher-altitude communities. However, it is unclear the extent to which this pattern is driven by co-gradient variation within clades or changes in clade representation across the gradient. To test for co-gradient variation, species composition, phylogenetic structure and functional traits were quantified for 97 species within the plant family Melastomataceae at five locations across a 2500-m altitudinal gradient along Volcán Barva in Costa Rica. Average melastome leaf force to punch, specific leaf area and leaf size vary with altitude, while four other functional traits do not. Taxonomic dissimilarity between communities was correlated with altitudinal difference, while phylogenetic dissimilarity was correlated with altitudinal dissimilarity only when measured with a metric that emphasizes shallow turnover of the tips of the phylogeny. These results highlight how species turnover may be more pronounced than functional or phylogenetic variation along altitudinal gradients. In addition, these results highlight the conservation value of lowland tropical forests, which here harbour a disproportionate amount of phylogenetic and functional diversity.

This paper discusses the role of authenticity and authenticity claims in computer assisted language learning (CALL). It considers authenticity as the result of a social negotiation process rather than an innate feature of a text, object, person, or activity. From this basis, it argues that authenticity claims play an important role in both second language acquisition (SLA) and CALL, being utilized to support the legitimacy of an approach or discipline more generally, as well as in defending a specific didactic design, especially with regard to transfer and motivation. The paper distinguishes between three domains of authenticity claims essential to CALL contexts: authenticity through language (linguistic authenticity), authenticity through origin (cultural authenticity), and authenticity through daily life experiences (functional authenticity). It points out problematic aspects of engaging in authenticity claims and argues that a reflexive stance might be useful in questioning the role of authenticity claims in CALL theory and practice.

This exploratory study investigates the linguistic and social interaction of four intermediate EFL learners during game play in a massively multiplayer online role playing game (MMORPG). Twelve illustrative episodes drawn from the participants’ text chat, collected in four 70-minute sessions held over a one-month period, are analyzed from a sociocultural perspective. Qualitative analysis reveals the presence of interactional features associated with the development of sociocultural competence. Throughout this study the learners successfully engaged in collaborative social interaction involving dialogue, conducted exclusively in the target language. Participants made appropriate use of politeness involving greetings, informal language, small talk, humor, and leave-takings, as a means to support the operation of collaborative interpersonal relationships. These relationships appeared based on reciprocity, friendship, and teamwork. They were effective in facilitating the creation of a low stress atmosphere characterized by social cohesion that was conducive to co-construction, and the consistent production of coherent target language output. The data indicates that the learners were able to jointly establish, and maintain, states of intersubjectivity through the use of continuers, and requests for assistance relevant to in-game tasks. Learner feedback was positive, and suggests that although the participants found the game play challenging, as this research progressed they became increasingly comfortable as their familiarity with the game increased. Aspects of participation identified by the learners as beneficial included opportunities for risk-taking, enhanced fluency practice, and exposure to vocabulary not normally encountered in regular language classes. The analysis suggests that the game provided access to an environment conducive to forms of collaborative target language use and social interaction identified as beneficial in the sociocultural account of language development.

This qualitative study investigates the relationship between learning opportunities and teacher cognition in the context of a videoconferencing (VC) project for foreign languages (FL) in French primary schools. Six generalist primary teachers were followed throughout the initial six-month stage of the initiative, and data were collected from learners, teachers, and trainers via questionnaire, video and audio recordings of class and feedback sessions, online teacher and trainer discussion, and video-stimulated recall interviews. Interview data revealed distinct teacher profiles involving differences in orientation to teaching and the teacher, learning and learners, and technology. These profiles corresponded to different teaching strategies and resulted in varying patterns of learner interaction in VC sessions. Teachers’ comments showed them to be guided by general rather than FL-specific pedagogical principles, and pedagogical concerns frequently intersected with technical issues as teachers learned to exploit the new VC technology. While most teachers valued spontaneous FL interaction as a key VC affordance, the filmed sessions revealed little unplanned learner-learner communication. This finding is related to teachers’ views of second language acquisition as product rather than a process; for more learner-centred teachers, spontaneity was affected by rehearsal, and for more teacher-oriented practitioners, sustained teacher intervention influenced patterns of learner participation. In addition to these classroom findings, the study highlights the value of this type of participant research in facilitating the exchange of resources and expertise, classroom video footage, and participants’ comments and queries, and thus contributing to professional development in CALL and CMC-based teacher education.

A prediction of the hypothesis that niche processes control plant species distributions across edaphic gradients is that pairwise comparisons of related species on contrasting soils should show consistent patterns of trait divergence. This hypothesis was tested in lowland Bornean rain forest by combining measurements of leaf traits, soil nutrients and the distribution of tree species in the Dipterocarpaceae across a nutrient gradient. Nine species were studied, comprising four related pairs in Shorea (phylogenetic independent contrasts; PICs) and one habitat generalist (Dipterocarpus sublamellatus). Lamina area, specific leaf area (SLA), leaf nitrogen (N) and phosphorus (P) were measured for ∼10 saplings of each species; habitat associations were defined as a continuous function of soil nutrients and categorically in relation to substrate. Species distributions and traits varied significantly with soil nutrients. When all species were pooled, SLA and leaf P increased significantly with species' distribution across the nutrient gradient; leaf N showed the same trend. Trait shifts with habitat were stronger and more pervasive when habitat was defined categorically – in all four PICs, rich-soil specialists had larger leaves, higher SLA, leaf N and P, and lower N:P ratios. Trait shifts with habitat at least partly reflect intrinsic differences between species. Within Shorea, variation in lamina area and N:P ratio were more strongly related to phylogeny than habitat, whereas the reverse held for SLA and leaf P. Phylogeny also influenced the extent of trait divergence between related species on different soils, and patterns of trait correlation within lineages. Results support the hypothesis that niche processes influence the distribution of species and traits in lowland tropical tree communities, and highlight the value of phylogenetic information for increasing the power of comparative studies.

This study examines interrelationships between eight leaf attributes (specific leaf mass, area, dry mass, lamina thickness, mesophyll cell number per cm2, mesophyll cell volume, chloroplast volume, and number of chloroplasts per mesophyll cell) in field-grown plants of 94 species from the Eastern Pamir Mountains, at elevations between 3800 and 4750 m. Unlike most other mountain areas, the Eastern Pamirs, Karakorum system, Tadjikistan provide localities where low temperatures and radiation combine with moisture stress at high altitudes. For all the attributes measured, significant differences were found between plants with different mesophyll types. Leaves with dorsiventral palisade structure (dorsal palisade, ventral spongy mesophyll cells) had thicker leaves with larger but fewer mesophyll cells, containing more and larger chloroplasts. These differences in mesophyll type are reflected in differences in the total surface of mesophyll cells per unit leaf area (Ames/A) or volume (Ames/V). Plants with isopalisade leaf structure (palisade cells under both dorsal and ventral surfaces) are more commonly xerophytes and their increased values of Ames/A and Ames/V decrease CO2 mesophyll resistance, which is an important adaptation to drought. Path analysis shows the critical importance of mesophyll cell volume in leading to the covariance between the different leaf attributes and hence to specific leaf mass (SLM), even though mesophyll cell volume is not itself strongly correlated with SLM. This is because mesophyll cell volume increases SLM through its effects on leaf thickness and chloroplast number per cell, but decreases SLM through its negative effect on mesophyll cell density.

The contribution of the starch and soluble carbohydrate pools to the diurnal variations of leaf mass per unit area (LMA) has been investigated in tomato leaves. A glasshouse experiment was carried out with plants pruned to two or five fruits per truss. Leaflets were sampled at sunrise, noon and sunset at different positions within the leaf (basal or terminal), and on different sympods along the stem. Carbohydrate contents and LMA were significantly higher in the terminal than in the basal leaflets, except at sunrise. During the day, differences in starch accumulation between terminal and basal leaflets increased with leaf height on the plant. Among sympods, the soluble carbohydrate content of the terminal leaflets did not vary significantly, whereas at 13.00 h the LMA was minimum in the middle of the plant and maximum at the top, and the leaf starch content significantly increased half-way up the plant. The plant fruit load had only small and non-significant effects on the LMA and carbohydrate contents. The response of LMA and carbohydrate contents to changing source activity was observed under controlled climatic conditions. The starch pool of fully expanded leaves was rapidly filled and emptied under increasing and decreasing source activity. In young expanding leaves, this pool was hardly filled during daylight. On average the soluble carbohydrates did not contribute significantly to the diurnal variations in LMA, whereas fluctuations in starch explained c. 70% and 44% of these variations in the upper and lower leaves, respectively. The results are discussed with respect to the modelling of LMA at the level of individual tomato leaves or sympods.

There is some evidence that traits of fresh leaves that provide structural or chemical protection (‘defence’) remain operational in the leaf litter and control interspecific variation in decomposition rate in or on the soil. We tested experimentally whether the negative relationship between foliar defence and litter decomposition rate is fundamental, i.e. whether it is seen consistently across higher plant species and life forms, and whether it is repeated in the floras of geographically and climatically distinct areas separated by an ocean. We employed the published results of two outdoor litter bag experiments, in which we simultaneously compared the relative mass losses (‘decomposibility’) of leaf litters of a wide range of plant species. One experiment was in Córdoba, Argentina, and included 48 Argentine species typical of the dry, subtropical landscapes along a steep altitudinal gradient. The other was in Sheffield, UK, and hosted 72 British species typical of the temperate–Atlantic landscape there. We linked the two experiments through a similar experiment in Sheffield that hosted litters of subsets of both the Argentine and British species. We also tested fresh leaves of all species from the same areas for tensile strength (‘toughness’) and relative palatability to generalist herbivorous snails in multi-species ‘cafeteria’ experiments. Both in Argentina and in Great Britain there were highly significant correlations between leaf palatability (r=0.61; 0.73) or leaf tensile strength (r=−0.60; −0.60) and litter mass loss across all species. These relationships could be explained by variation both between and within broad life-form groups. Specific leaf area (area[ratio ]dry mass) of fresh leaves was consistently correlated only with litter mass loss within British life form groups. We illustrated the possible ecosystem consequences of these relationships by comparing functional traits of British species differing in leaf habit. In comparison with deciduous species, evergreens generally had innately slow growth, which corresponded to their longer-lived leaves of lower specific leaf area, higher tensile strength and lower palatability to generalist invertebrate herbivores. Correspondingly, evergreens produced more resistant leaf litter. Thus, slow-growing evergreens might maintain their position in infertile ecosystems through leaf traits that help them to conserve their nutrients efficiently and to keep nutrient mineralization low, thereby not allowing potentially fast-growing deciduous species to outcompete them.