Optimization of the wetting-drying characteristics of hydrophobic metal organic frameworks via crystallite size: The role of hydrogen bonding between intruded and bulk liquid

Hypothesis: The behavior of Heterogeneous Lyophobic Systems (HLSs) comprised of a lyophobic porous material and a corresponding non-wetting liquid is affected by a variety of different structural parameters of the porous material. Dependence on exogenic properties such as crystallite size is desirable for system tuning as they are much more facilely modified. We explore the dependence of intrusion pressure and intruded volume on crystallite size, testing the hypothesis that the connection between internal cavities and bulk water facilitates intrusion via hydrogen bonding, a phenomenon that is magnified in smaller crystallites with a larger surface/volume ratio. Experiments: Water intrusion/extrusion pressures and intrusion volume were experimentally measured for ZIF-8 samples of various crystallite sizes and compared to previously reported values. Alongside the practical research, molecular dynamics simulations and stochastic modeling were performed to illustrate the effect of crystallite size on the properties of the HLSs and uncover the important role of hydrogen bonding within this phenomenon. Findings: A reduction in crystallite size led to a significant decrease of intrusion and extrusion pressures below 100 nm. Simulations indicate that this behavior is due to a greater number of cages being in proximity to bulk water for smaller crystallites, allowing cross-cage hydrogen bonds to stabilize the intruded state and lower the threshold pressure of intrusion and extrusion. This is accompanied by a reduction in the overall intruded volume. Simulations demonstrate that this phenomenon is linked to ZIF-8 surface half-cages exposed to water being occupied by water due to non-trivial termination of the crystallites, even at atmospheric pressure

Bladder and bowel dysfunction, adaptive behaviour and psychiatric profiles in adults affected by autism spectrum disorders

Aims Bladder and bowel dysfunction (BBD) have been recognized in children affected by autism spectrum disorder (ASD), but no consistent information exist in adults with the condition. We evaluated the prevalence of BBD and the impact of psychiatric and behavioural profiles in adults affected by ASD. Methods Twenty-two adults and 13 children/teens with ASD and a matched group of typically developing subjects (TD) were prospectively studied. Patients and TD subjects underwent the evaluation of urinary incontinence (UI: diurnal, continuous or intermittent), nocturnal enuresis (NE), and bowel disturbances with the 3-day voiding and bowel diary. In addition, assessment of intellectual disability (ID) and psychiatric and adaptive behaviours with the Neuropsychiatric Inventory Scale (NPI) and the Vineland Adaptive Behaviour Scale 2nd Edition (Vineland-II), was performed. Results In adults, any type of incontinence was observed in 81.8% of cases, and NE and intermittent UI in 59.0% and 36.3% of patients, respectively. Faecal incontinence and constipation were detected 36.3% and in 68.1% of cases, respectively. ID was severe in 2 cases and profound in 18; NPI and Vineland-II items most affected were "Irritability/Lability," "Motor Activity," and "Agitation," and IQ-Socialization and IQ-Communication. Significant relationships were identified between intermittent UI and greater ID (P < .02) and high "anxiety" (P < .05), and between NE and high "euphoria/elevated mood" (P < .05). These results were similar to those observed in children/teens. Conclusions Adults with ASD, and greater ID and mood disorders, present with a high prevalence of BBD. A shared pathogenetic mechanism could underlie the co-occurrence of ASD, mood disorders, and BBD. © 2019 Wiley Periodicals, Inc