No harm, no foul?: Expert views on the future direction of marine antibiofouling technologies

The colonisation of submerged surfaces by marine fouling organisms is a global problem with impacts ranging from clogged pipelines and aquaculture nets through to hull fouling that increases fuel costs and green-house gas emissions and provide potential habitats for invasive species. Marine antibiofouling techniques, such as copper plates on ships and functional coatings that release toxic biocides, were historically developed in order to reduce the frequency and expense of the physical removal of fouling organisms. For a time the solution was thought to be tributyltin self-polishing coatings, but these were later proven to be detrimental to the marine environment and subsequently banned. Today, the 'state-of-the-art' general-use coatings are based on the release of biocidal copper and booster biocides, but environmental concerns exist regarding their impacts on marine life and future legislation may put restrictions on their use. While non-biocide based alternatives include non-stick or foul-release coatings, these generally work best on fast moving vessels with little stationary time, even if recent developments seem to reduce this demand on speed. We utilised a targeted questionnaire to a range of experts that work with, or are affected by, marine anti-biofouling to assess their views about potential antifouling technologies of the future. The paper provide insights into the expectations and demands that need to be addressed in development and implementation of future marine anti-biofouling technologies and indicate how those views differ between professional roles

Glutaraldehyde-crosslinking for improved copper absorption selectivity and chemical stability of polyethyleneimine coatings

Nano-thin coatings of glutaraldehyde (GA)-crosslinked polyethyleneimine (PEI) are extremely selective and effective in binding copper from seawater. Here it was demonstrated that GA-PEI performs significantly different from PEI. The copper-selectivity of self-assembled PEI coatings on silicon substrates was greatly improved by GA-crosslinking. After submersion in artificial seawater containing 200 ppb copper and equimolar amounts of 11 competing ions only copper and trace amounts of Zn were detected in the GA-crosslinked coatings, while for non-crosslinked PEI there was about 30% Zn present relative to copper. The coatings were demonstrated to be highly stable under acidic conditions and retained their copper-binding selectivity after repeated cycles of binding and acid-mediated elution. After self-assembly of the GA-crosslinked coating on mesoporous diatomaceous earth particles, significant amounts of copper could be extracted from 200 ppb in artificial seawater and eluted under acidic pH

Thermal Degradation of Adsorbed Bottle-Brush Macromolecules: Molecular Dynamics Simulation

The scission kinetics of bottle-brush molecules in solution and on an adhesive substrate is modeled by means of Molecular Dynamics simulation with Langevin thermostat. Our macromolecules comprise a long flexible polymer backbone with $L$ segments, consisting of breakable bonds, along with two side chains of length $N$, tethered to each segment of the backbone. In agreement with recent experiments and theoretical predictions, we find that bond cleavage is significantly enhanced on a strongly attractive substrate even though the chemical nature of the bonds remains thereby unchanged. We find that the mean bond life time decreases upon adsorption by more than an order of magnitude even for brush molecules with comparatively short side chains $N=1 \div 4$. The distribution of scission probability along the bonds of the backbone is found to be rather sensitive regarding the interplay between length and grafting density of side chains. The life time declines with growing contour length $L$ as $\propto L^{-0.17}$, and with side chain length as $\propto N^{-0.53}$. The probability distribution of fragment lengths at different times agrees well with experimental observations. The variation of the mean length $L(t)$ of the fragments with elapsed time confirms the notion of the thermal degradation process as a first order reaction.Comment: 15 pages, 7 figure

The genetic overlap of Attention-Deficit/Hyperactivity Disorder and Autistic-like traits: an investigation of individual symptom scales and cognitive markers

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorders (ASDs) frequently co-occur. However, due to previous exclusionary diagnostic criteria, little is known about the underlying causes of this covariation. Twin studies assessing ADHD symptoms and autistic-like traits (ALTs) suggest substantial genetic overlap, but have largely failed to take into account the genetic heterogeneity of symptom subscales. This study aimed to clarify the phenotypic and genetic relations between ADHD and ASD by distinguishing between symptom subscales that characterise the two disorders. Moreover, we aimed to investigate whether ADHD-related cognitive impairments show a relationship with ALT symptom subscales; and whether potential shared cognitive impairments underlie the genetic risk shared between the ADHD and ALT symptoms. Multivariate structural equation modelling was conducted on a population-based sample of 1312 twins aged 7–10. Social-communication ALTs correlated moderately with both ADHD symptom domains (phenotypic correlations around 0.30) and showed substantial genetic overlap with both inattention and hyperactivity-impulsivity (genetic correlation = 0.52 and 0.44, respectively). In addition to previously reported associations with ADHD traits, reaction time variability (RTV) showed significant phenotypic (0.18) and genetic (0.32) association with social-communication ALTs. RTV captured a significant proportion (24 %) of the genetic influences shared between inattention and social-communication ALTs. Our findings suggest that social-communication ALTs underlie the previously observed phenotypic and genetic covariation between ALTs and ADHD symptoms. RTV is not specific to ADHD symptoms, but is also associated with social-communication ALTs and can, in part, contribute to an explanation of the co-occurrence of ASD and ADHD

PDD symptoms in ADHD, an independent familial trait?

The aims of this study were to investigate whether subtle PDD symptoms in the context of ADHD are transmitted in families independent of ADHD, and whether PDD symptom familiality is influenced by gender and age. The sample consisted of 256 sibling pairs with at least one child with ADHD and 147 healthy controls, aged 5-19 years. Children who fulfilled criteria for autistic disorder were excluded. The Children's Social Behavior Questionnaire (CSBQ) was used to assess PDD symptoms. Probands, siblings, and controls were compared using analyses of variance. Sibling correlations were calculated for CSBQ scores after controlling for IQ, ADHD, and comorbid anxiety. In addition, we calculated cross-sibling cross-trait correlations. Both children with ADHD and their siblings had higher PDD levels than healthy controls. The sibling correlation was 0.28 for the CSBQ total scale, with the CSBQ stereotyped behavior subscale showing the strongest sibling correlation (r = 0.35). Sibling correlations remained similar in strength after controlling for IQ and ADHD, and were not confounded by comorbid anxiety. Sibling correlations were higher in female than in male probands. The social subscale showed stronger sibling correlations in elder than in younger sibling pairs. Cross-sibling cross-trait correlations for PDD and ADHD were weak and not-significant. The results confirm that children with ADHD have high levels of PDD symptoms, and further suggest that the familiality of subtle PDD symptoms in the context of ADHD is largely independent from ADHD familiality

Inhibition, flexibility, working memory and planning in autism spectrum disorders with and without comorbid ADHD-symptoms

<p>Abstract</p> <p>Background</p> <p>Recent studies have not paid a great deal of attention to comorbid attention-deficit/hyperactivity disorder (ADHD) symptoms in autistic children even though it is well known that almost half of children with autism spectrum disorder (ASD) suffer from hyperactivity, inattention and impulsivity. The goal of this study was to evaluate and compare executive functioning (EF) profiles in children with ADHD and in children with ASD with and without comorbid ADHD.</p> <p>Methods</p> <p>Children aged 6 to 18 years old with ADHD (n = 20) or ASD (High-Functioning autism or Asperger syndrome) with (n = 20) and without (n = 20) comorbid ADHD and a typically developing group (n = 20) were compared on a battery of EF tasks comprising inhibition, flexibility, working memory and planning tasks. A MANOVA, effect sizes as well as correlations between ADHD-symptomatology and EF performance were calculated. Age- and IQ-corrected z scores were used.</p> <p>Results</p> <p>There was a significant effect for the factor group (F = 1.55; dF = 42; p = .02). Post-hoc analysis revealed significant differences between the ADHD and the TD group on the inhibition task for false alarms (p = .01) and between the ADHD group, the ASD+ group (p = .03), the ASD- group (p = .02) and the TD group (p = .01) for omissions. Effect sizes showed clear deficits of ADHD children in inhibition and working memory tasks. Participants with ASD were impaired in planning and flexibility abilities. The ASD+ group showed compared to the ASD- group more problems in inhibitory performance but not in the working memory task.</p> <p>Conclusion</p> <p>Our findings replicate previous results reporting impairment of ADHD children in inhibition and working memory tasks and of ASD children in planning and flexibility abilities. The ASD + group showed similarities to the ADHD group with regard to inhibitory but not to working memory deficits. Nevertheless the heterogeneity of these and previous results shows that EF assessment is not useful for differential diagnosis between ADHD and ASD. It might be useful for evaluating strengths and weaknesses in individual children.</p

Exploratory Study of Executive Function Abilities Across the Adult Lifespan in Individuals Receiving an ASD Diagnosis in Adulthood

The few studies of autism spectrum disorder (ASD) across adulthood suggest different age-related associations in different aspects of executive function (EF). In this exploratory study we examined EF abilities and self-report autism traits in 134 adults (aged 18-75 years; mean=31 years) with abilities in the normal range, receiving a first diagnosis of ASD. Results suggest that in some EF relying on speed and sequencing (Trails A and B; Digit Symbol), late-diagnosed ASD individuals may demonstrate better performance than typical age-norms. On other EF (Digit Span, Hayling, Brixton tests) age-related correlations were similar to typical age-norms. Different domains of EF may demonstrate different trajectories for ageing with ASD, with patterns of slower, accelerated or equivalent age-related change observed across different measures

Exploratory Study of Executive Function Abilities Across the Adult Lifespan in Individuals Receiving an ASD Diagnosis in Adulthood

The few studies of autism spectrum disorder (ASD) across adulthood suggest different age-related associations in different aspects of executive function (EF). In this exploratory study we examined EF abilities and self-report autism traits in 134 adults (aged 18-75 years; mean=31 years) with abilities in the normal range, receiving a first diagnosis of ASD. Results suggest that in some EF relying on speed and sequencing (Trails A and B; Digit Symbol), late-diagnosed ASD individuals may demonstrate better performance than typical age-norms. On other EF (Digit Span, Hayling, Brixton tests) age-related correlations were similar to typical age-norms. Different domains of EF may demonstrate different trajectories for ageing with ASD, with patterns of slower, accelerated or equivalent age-related change observed across different measures