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OBJECTIVE: We have shown that the acoustic change complex (ACC) can be elicited by changing the horizontal sound location in young individuals. In this study, we aimed to evaluate the application of ACC within the elderly and its relationship with behavioural results. DESIGN: The minimum audible angle (MAA), as well as onset cortical auditory evoked potentials (onset-CAEPs) and ACC elicited by the stimuli of location-change white noise (±45 to ±2 degrees) were recorded. Latencies and amplitudes were analysed using repeated-measures ANOVA. Pearson correlation analysis was conducted to examine the relationship between ACC and MAA. STUDY SAMPLE: Ten older adults with normal hearing (NH) and twenty with presbycusis. RESULTS: The ACC was effectively elicited with angular variations in elderly participants. The onset-CAEP N1 latency, ACC N1'-P2' amplitude, and N1' latency were all associated with the angle shifts, with the N1' latency being the most predictive factor for angle discrimination. The consistency between MAA and ACC made them complementary for the clinical evaluation of sound localisation. CONCLUSIONS: The utilisation of ACC, evoked by location-change sounds, presented a promising clinical objective measure for evaluating sound localisation abilities in the elderly.
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Background: Patients with age-related hearing loss (ARHL) often struggle with tracking and locating sound sources, but the neural signature associated with these impairments remains unclear. Materials and methods: Using a passive listening task with stimuli from five different horizontal directions in functional magnetic resonance imaging, we defined functional regions of interest (ROIs) of the auditory "where" pathway based on the data of previous literatures and young normal hearing listeners (n = 20). Then, we investigated associations of the demographic, cognitive, and behavioral features of sound localization with task-based activation and connectivity of the ROIs in ARHL patients (n = 22). Results: We found that the increased high-level region activation, such as the premotor cortex and inferior parietal lobule, was associated with increased localization accuracy and cognitive function. Moreover, increased connectivity between the left planum temporale and left superior frontal gyrus was associated with increased localization accuracy in ARHL. Increased connectivity between right primary auditory cortex and right middle temporal gyrus, right premotor cortex and left anterior cingulate cortex, and right planum temporale and left lingual gyrus in ARHL was associated with decreased localization accuracy. Among the ARHL patients, the task-dependent brain activation and connectivity of certain ROIs were associated with education, hearing loss duration, and cognitive function. Conclusion: Consistent with the sensory deprivation hypothesis, in ARHL, sound source identification, which requires advanced processing in the high-level cortex, is impaired, whereas the right-left discrimination, which relies on the primary sensory cortex, is compensated with a tendency to recruit more resources concerning cognition and attention to the auditory sensory cortex. Overall, this study expanded our understanding of the neural mechanisms contributing to sound localization deficits associated with ARHL and may serve as a potential imaging biomarker for investigating and predicting anomalous sound localization.
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Flavonoids are ubiquitous polyphenolic compounds that play a vital role in plants' defense response and medicinal efficacy. UV-B radiation is a vital environmental regulator governing flavonoid biosynthesis in plants. Many plants rapidly biosynthesize flavonoids as a response to UV-B stress conditions. Here, we investigated the effects of flavonoid biosynthesis via UV-B irradiation in Euphorbia lathyris. We found that exposure of the E. lathyris callus to UV-B radiation sharply increased the level of one O-methyltransferase (ElOMT1) transcript and led to the biosynthesis of several methylated flavonoids. The methyltransferase ElOMT1 was expressed heterologously in E. coli, and we tested the catalytic activity of recombinant ElOMT1 with possible substrates, including caffeic acid, baicalin, and luteolin, in vitro. ElOMT1 could efficiently methylate when the hydroxyl groups were contained in the core nucleus of the flavonoid. This molecular characterization identifies a methyltransferase responsible for the chemical modification of the core flavonoid structure through methylation and helps reveal the mechanism of methylated flavonoid biosynthesis in Euphorbiaceae. This study identifies the O-methyltransferase that responds to UV-B irradiation and helps shed light on the mechanism of flavonoid biosynthesis in Euphorbia lathyris.
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Euphorbia , Euphorbia/génétique , Escherichia coli/génétique , Flavonoïdes/génétique , Lutéoline , Methyltransferases/génétiqueRÉSUMÉ
NO reduction over highly dispersed zerovalent iron (Fe0) supported on graphene (G), with and without the presence of CO in the reacting stream, was systematically studied using a fixed-bed reactor, and the reaction mechanism was examined with the aid of in situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations. The in situ FTIR results showed that NO adsorbed on the Fe0 site is reduced to form active surface oxygen species (O*), which is then reduced by carbon in graphene to form CO2. The presence of CO in the reacting stream helps to reduce the oxidized Fe(O) sites to regenerate Fe0 sites, making NO reduction easier. It was revealed that NO and CO2 are easily adsorbed on the active surface oxygen species (O*) to form nitrate and carbonate, inhibiting their reduction by CO and deactivating the catalyst. The DFT calculations results suggest that the role of Fe is to reduce the energy barrier of the NO adsorption and decomposition, which controls the formation of active surface oxygen species and N2. The combined FTIR and DFT results offer new insights into the possible mechanism of catalytic NO reduction over graphene loaded with Fe, with and without CO.
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INTRODUCTION: Cycling is a popular choice for urban transportation. Helmets are important and the most popular means of head protection for cyclists. However, a debate about the effectiveness of helmets in protecting a cyclist's head from injury continues. METHOD: We employed computational biomechanics methods to analyze the head protection effectiveness of nine off-the-shelf-helmets for two typical impact scenarios that occur in cycling accidents: cyclist's head impacting a kerb (kerb-impact) and cyclist skidding (skidding impact) on the road surface. We conducted drop tests for all nine analyzed helmets, and used the test data for validation of the corresponding helmet finite element (FE) models created in this study. The validated helmet models were then used in the full-scale computer simulations (FE analysis for the skull, brain and helmet, and multibody dynamics for the remaining segments of the cyclist's body) of the cycling accidents for cyclists wearing a helmet and without a helmet. RESULTS: The results indicate that helmets can reduce both the peak linear acceleration of the cyclist head center of gravity (COG) and the risk of cyclist skull fracture. However, higher rotational acceleration of the head COG was predicted for cyclists wearing helmets. The results obtained using the injury criteria that rely on the brain deformations (maximum shear strain MPS and cumulative strain damage measure CSDM) suggest that helmets may offer protection in all the analyzed cyclist impact scenarios. However, the predicted level of protection varies for different helmets and impact scenarios with appreciable variations in the predictions obtained using different injury criteria. Reduction in the maximum principal strain (MPS0.98) for helmeted cyclists was predicted for both impact scenarios. In contrast, wearing the helmet reduced the CSDM only for the skidding impact scenario. For the kerb-impact scenario, no clear influence of the helmet on the predicted CSDM was observed.
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Traumatismes cranioencéphaliques , Dispositifs de protection de la tête , Accélération , Accidents de la route/prévention et contrôle , Cyclisme/traumatismes , Phénomènes biomécaniques , Traumatismes cranioencéphaliques/prévention et contrôle , HumainsRÉSUMÉ
The charge transport of Ru(II) complex molecular junctions, fabricated using a soft stamp-printing method, was investigated from 95 to 299 K under both dark and light conditions in order to explore the roles of the electrode/molecule interface and complex properties in the device performance. The junctions show asymmetric current-voltage characteristics with conductance switching and a photovoltaic effect at low temperature. The device performance depends greatly on the redox characteristics and built-in potential induced by electrode/molecule interface(s) and the molecular dipole. Our work may provide valuable information for the design of novel molecular electronics.