ABSTRACT
Early-life seizures (ELS) are associated with autism spectrum disorder (ASD); however, due to a lack of effective treatments for ELS, it is not clear whether ELS plays a causal role, potentiates the ASD phenotype, or is the result of a common pathophysiology. Deficits in communications are a core feature of ASD. To isolate the impact of ELS on communication, we probed the behavioral consequences of a single episode of kainic acid-induced early-life seizures (KA-ELS) in male and female Sprague-Dawley (CD) rats. Deficits in auditory communication were observed in adult male rats as assessed by behavioral response to ultrasonic vocalization (USV) playback. Ultrasonic vocalizations are classified into two major categories - 50-kHz (positive) calls and 22-kHz (aversive) calls. Behavioral response was assessed via rat preference for different USV playback in a radial arm maze. Response to 22-kHz calls was not impacted by ELS while response to 50-kHz calls was impacted. All rats demonstrated positional preference for the arms adjacent to where 50-kHz calls were playing compared to background noise; however, male ELS rats demonstrated a greater positional preference for the arms adjacent to where 50-kHz calls were playing compared to male control rats. These studies demonstrate that responses to socially relevant auditory cues are chronically altered in adult male rats following a single episode of ELS. We speculate that these changes contribute to previously reported social deficits associated with ELS.
Subject(s)
Autism Spectrum Disorder , Ultrasonics , Animals , Female , Humans , Male , Rats , Rats, Sprague-Dawley , Seizures/chemically induced , Vocalization, Animal/physiologyABSTRACT
Cyclohexene skeletal isomerization towards methylcyclopentene is an economically favorable process due to the higher added value of the product. Traditional oxide-based catalysts face the challenge of achieving both high activity and stability. In this work, cyclohexene skeletal isomerization is achieved under mild conditions over designed zeolite-based catalysts with 96.8 wt.% liquid yield, 95.8 wt.% selectivity towards methylcyclopentene and satisfactory stability for multiple runs. The favorable performance is attributed to the unique acidic, structural and morphological features of the optimized cobalt/NaUZSM-5 catalyst. Further experimental data and DFT studies suggest that a carboncationic mechanism might be followed and that the reaction mainly occurs within the internal pores of the zeolite structures.
ABSTRACT
The effects of Zn-Pt interaction and Pt dispersion over a uniform compact cylindrical shape ZSM-5 (UZSM-5) on the catalytic octane aromatization performance are investigated. The comparison between different Pt- and Zn-modified ZSM-5 catalysts demonstrates the significance of ZSM-5 morphology and, more importantly, the metal distributions on it. For the UZSM-5 support, Pt atoms prefer to occupy the sites within its inner pores, resulting in high selectivity to xylenes during the octane aromatization. The Zn deposit in inner pores and higher dispersion of Pt lead to the spillover of Pt sites to the external surface, which is critical for the activation of octane to produce reaction intermediates that are further converted to aromatics over the inner pore catalytic sites. These effects are evidenced by a diffuse reflection infrared Fourier transform spectroscopy study of CO adsorbed on the catalyst surface. In situ X-ray absorption fine structure spectra are collected to probe the coordination number and the chemical environment of Pt and Zn atoms in the catalysts during the octane aromatization reaction. Pt and Zn are well dispersed and stable during the reaction, and a partial reduction of Pt during the reaction is observed. A theoretical study using the density functional theory method predicts that the reaction and transition-state intermediates upon octane activation are better stabilized by Pt(111) of Pt external surface sites with a smaller activation barrier, indicating their significance in C-H activation. This hypothesis is further evidenced by comparing the octane aromatization performance of various modified catalysts through varying Zn loading, blocking inner pores, and covering the external catalytic sites with SiO2.
ABSTRACT
A bimetallic-support interaction through Pt-Zn nanoparticles and uniform compact cylindrical ZSM-5 particles shows selectivity over 90% towards BTX and i-octane at controlled 60% conversion with negligible coke formation when reforming n-octane. This is a significant improvement compared to alternative Pt-Zn on conventional ZSM-5, with a selectivity of less than 40%.
ABSTRACT
Recent investigations at Camp Fauld in Buchan, Scotland have yielded two peat deposits of pre-Late Devensian age. Percentage pollen diagrams are presented. One peat is radiocarbon-dated to 34-39 ka DP, which prompts correlation with the Hengelo-Denekamp sequence of NW continental Europe, but the pollen evidence, revealing the presence of a birch-pine woodland, suggests an earlier stage. The second peat deposit records an open shrub-tundra in which Bruckenthalia spiculifolia is present. The peat yielded a radiocarbon date of 40-51 ka BP, but is suspected of having been contaminated by younger carbon. That suspicion and the presence of Bruckenthalia suggest that a correlation, based on the radiocarbon date, with the Glinde interstadial, identified in NW Germany, would be incorrect. Correlation with other Scottish pre-Late Devensian sites has proved to be difficult.
