Background The olfactory organ of turtles consists of an upper chamber epithelium (UCE) associated with glands and a lower chamber epithelium (LCE) lacking glands. The odorant receptors (ORs) are a family of olfactory receptors generally categorized into classes I and II based on sequence similarity. In amniotes, class I and II ORs are thought to preferentially detect hydrophilic and hydrophobic molecules, respectively. The relative abundance of OR classes vary among turtles: while class I ORs predominate in aquatic turtles, class II ORs are more abundant in terrestrial turtles. However, it remains unclear where these receptors are expressed in the olfactory organ of turtles. Results In this study, we identified eight class I ORs and 61 class II ORs and examined the distribution of OR-expressing cells in the olfactory organ of the African spurred tortoise (Centrochelys sulcata). In situ hybridization analysis revealed that all representative class I ORs examined in C. sulcata are expressed in both the UCE and the LCE, whereas all representative class II ORs examined are restricted to the UCE. These findings are in marked contrast to our previous observations in the olfactory organ of the sea turtle Chelonia mydas. Also, double-labeling experiments revealed that class I ORs are not co-expressed with the transcription factor B-cell lymphoma/leukemia 11b (Bcl11b), suggesting that Bcl11b-mediated repression of class I OR expression is conserved in C. sulcata. Conclusion Present findings suggest that ecological adaptation of turtles may be correlated with variation in the expression site of ORs within the olfactory organ.
This study investigates the ductile fracture mechanisms in as-quenched (As-Q) and quenched-and-tempered (Q-T) dual-phase steels. Using in-situ tensile testing combined with synchrotron X-ray tomography, we performed four-dimensional quantitative analysis of void evolution to reveal how heat treatment fundamentally alters damage behavior. The high-strength, low-ductility As-Q steel exhibited premature failure. Its significant phase-hardness mismatch between ferrite and martensite phases induced continuous and widespread void nucleation via martensite cracking after reaching the ultimate tensile strength. The subsequent rapid, isotropic growth and coalescence of these numerous voids led to early fracture. In contrast, tempering the Q-T steel reduced the hardness mismatch among phases, yielding superior ductility with lower strength. The Q-T steel, in particular, exhibited a two-stage damage process. Throughout most of the deformation, voids grew anisotropically by elongating along the tensile axis. This stable growth, however, gave way to a drastic change just before fracture, characterized by a rapid proliferation of voids oriented perpendicular to the loading direction. This final phase is attributed to damage in the martensite, suggesting the quantitative and qualitative differences in void evolution between the As-Q and Q-T steels.
Chemical cues that appear potent in controlled laboratory bioassays do not necessarily function as effective behavioural cues under natural conditions, where animals can freely approach or ignore stimuli. How chemical detectability translates into voluntary behavioural engagement, therefore, remains an important unresolved question. Plant-derived semiochemicals provide a tractable system for examining this issue because the same compounds can be presented either as intact natural sources or as purified chemicals. Domestic cats (Felis silvestris catus) show a characteristic self-anointing response to iridoid-producing plants, including catnip (Nepeta cataria) and silver vine (Actinidia polygama), both widely regarded as cat-attractants. Here, we tested whether these plants differ in their ability to induce voluntary engagement under free-choice conditions. Free-roaming cats rarely showed self-anointing behaviour (face-rubbing and rolling) toward intact catnip plants, but consistently engaged with silver vine. The same bias toward silver vine was observed in captive cats presented simultaneously with plant extracts. Chemical analyses confirmed that catnip contained abundant bioactive nepetalactone, indicating that weak responsiveness was not explained by a lack of bioactive compounds. These findings demonstrate that chemical abundance and laboratory bioactivity do not necessarily predict behavioural reliability under natural encounter conditions. Instead, whether a cue consistently elicits voluntary engagement may determine its ecological effectiveness as a behavioural cue.
The damage initiation and evolution behaviors of ferrite-martensite dual phase (DP), transformation-induced plasticity (TRIP)-aided dual-phase (TDP), quenched and tempered (QT), and TRIP-aided martensitic (TM) steels during tensile deformation were investigated. Voids were initiated at the phase boundaries and inside the martensite in the DP and TDP steels, whereas fine voids were observed at the prior austenite, packet, and block boundaries in the QT and TM steels. In the DP and TDP steels, the size of the voids remarkably increased with the plastic strain, even though the number of voids increased slightly. By contrast, the QT and TM steels exhibited a drastic increase in the number of voids, whereas a slight increase in the size of the voids was observed. The voids in the TM steel hardly extended as the plastic strain increased unlike those in the QT steel. The extent of voids in the DP and TDP steels might be attributed to stress and plastic strain partitioning between the different phases during tensile deformation. In addition, the promotion of void initiation and suppression of void growth might be attributed to the fine and uniform martensite matrix in the QT and TM steels. The suppression of void initiation in the TDP steel and void growth in the TM steel might be attributed to the stress and plastic strain relaxations at the void initiation site and the vicinity of voids owing to the effective martensitic transformation of retained austenite.
This study investigates the wear behavior of a new nozzle made of Stainless Steel (SS) 316L using an accelerated wear test under machining condition employing different abrasives namely Garnet and Silicon Carbide (SiC). The research focuses on the newly designed nozzle consisting of two detachable parts; an inlet and an outlet with a special feature for easy replacement. Preliminary experiments were carried out to evaluate the wear rate, wear patterns, and surface degradation using SEM analysis. Results showed that the nozzle tested with SiC experienced more severe erosion, indicated by a greater expansion in bore size, compared to the one tested with Garnet. SEM, mass loss, elemental analysis, and surface roughness results reveal that SiC abrasives cause significant nozzle wear through combined material removal and particle embedding. The surface roughness varies along the nozzle, with the inlet showing the highest erosion. These findings highlight the need for appropriate abrasive selection and nozzle design to reduce wear and extend service life.
