742875 research outputs found
Sort by
Asymmetric Conjugate Hydrocyanation of α,β-Unsaturated Aldehydes Catalyzed by Engineered 2-Deoxy-D-ribose-5-phosphate Aldolase
No full textThe enantioselective conjugate hydrocyanation of α,β-unsaturated aldehydes remains a long-standing challenge in synthetic chemistry. Here, we report the redesign of 2-deoxy-D-ribose-5-phosphate aldolase (DERA) into an efficient biocatalyst capable of promoting the asymmetric conjugate addition of hydrogen cyanide (generated in situ from trimethylsilyl cyanide) to aromatic enals via an iminium activation pathway. The evolved variant DERA-CN enables the efficient formation of various C4-nitriles with high conversions (up to 99%) and good enantioselectivity (up to 98% e.e.). Control experiments revealed a stepwise process involving enzyme-catalyzed conjugate hydrocyanation followed by spontaneous 1,2-addition of cyanide. Substrates with various electron-donating and electron-withdrawing groups are tolerated, providing access to various enantioenriched nitriles. This work expands the scope of DERA-promoted iminium catalysis and provides a rare enzymatic platform for asymmetric conjugate hydrocyanation under mild aqueous conditions.</p
COVEE:A dataset for cognitive modeling with video, electroencephalography, and eye tracker
No full textWe present COVEE, a dataset for Cognitive mOdeling with Video, Electroencephalography, and Eye tracker. COVEE aims to be a valuable resource for advancing research on human cognition and the real-time estimation of cognitive load (CL) and situation awareness (SA) in complex operational environments. COVEE subsumes approximately 26 hours of multimodal data collected in carefully designed human subject experiments in realistic task settings, along with self-reported measures for CL and SA. In total, 23 human subjects performed multiple tasks with varying complexity in their roles as remote operators of unmanned aerial vehicles. To establish baselines, extensive experiments are conducted using various modern deep learning architectures and pre-trained large vision models. Insights gained from the experiments demonstrate the potential of COVEE for future research and real-world applications related to brain–computer interfaces, assistive technologies, or other forms of real-time behavioral intervention. Both raw and processed experimental data, along with all codes, are published for the highest reproducibility (https://github.com/Purdue-AIDA3/CM-COVEE).</p
Prevalence, correlates and mental health outcomes of Internet addiction among Chinese adolescents across early, middle and late adolescence
No full textAlthough there is a growing awareness of the age differences in adolescent Internet addiction (IA), comparative research exploring the prevalence and correlates of IA across distinct developmental stages remains limited among Chinese adolescents. This study aimed to investigate the IA prevalence and its associations with demographics, lifestyles, psychosocial factors and mental health outcomes among Chinese adolescents from early to late adolescence. A total of 67,182 adolescents from Shenzhen, China participated in this cross-sectional online survey, completing self-reported questionnaires that assessed demographics, lifestyles, psychosocial factors, IA and mental health problems. The prevalence of IA was 2.7 %, 3.4 % and 6.0 % in early, middle and late adolescence, showing a progressive increase with advancing developmental stages. Grade, single child status, parental marital status and family history of mental disorders showed age-specific association patterns with adolescent IA, while gender, exercise frequency, habits of smoking or drinking, stressful life events and resilience demonstrated consistently significant associations with IA across all developmental stages. After adjusting for all covariates, IA exhibited significant associations with increased risks of depression, anxiety and suicidal ideation, except for anxiety in late adolescence. Notably, different association patterns emerged between IA and sleep disturbance across different developmental stages. These findings underscore a progressive age-related increase in IA prevalence and reveal distinct correlates of IA across different stages of adolescence, providing nuanced insights into developing targeted prevention and intervention strategies for adolescent IA.</p
