Effect of fibre treatments on interfacial shear strength of hemp fibre reinforced polylactide and unsaturated polyester composites

Surface treatment of hemp fibres was investigated as a means of improving interfacial shear strength (IFSS) of hemp fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/hemp fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated fibre samples. IFSS of UPE/hemp fibre samples increased for all treated fibres. This is believed to be due to the improvement of chemical bonding between the treated fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment fibre/UPE samples

CHEMICAL AND PHYSICAL ANALYSIS OF LAMINATED SEDIMENT FORMED IN LOE POOL, CORNWALL

Institute for Marine Environmental Research, Prospect Place, The Hoe, Plymout

Influence of loading rate, alkali fibre treatment and crystallinity on fracture toughness of random short hemp fibre reinforced polylactide bio-composites

Plane-strain fracture toughness (KIc) of random short hemp fibre reinforced polylactide (PLA) bio-composites was investigated along with the effect of loading rate, fibre treatment and PLA crystallinity. Fracture toughness testing was carried out at loading rates varying from 0.5 to 20 mm/min using single-edge-notched bending specimens with 0 to 30 wt% fibre. KQ (trial KIc) of composites decreased as loading rate increased, until stabilising to give KIc values at a loading rate of 10 mm/min and higher. The reduction of crazing and stress whitening, as well as a more direct crack path observed in PLA samples combined with reduced plastic deformation observed in composites provided explanation for this reduction. KIc of composites was found to decrease with increased fibre content and fibre treatment with sodium hydroxide. Studies controlling the degree of PLA crystallinity by heat treatment or “annealing” showed that reduction of KIc can be attributed to increased crystallinity

Late Pliocene lakes and soils: a global data set for the analysis of climate feedbacks in a warmer world

The global distribution of late Pliocene soils and lakes has been reconstructed using a synthesis of geological data. These reconstructions are then used as boundary conditions for the Hadley Centre General Circulation Model (HadCM3) and the BIOME4 mechanistic vegetation model. By combining our novel soil and lake reconstructions with a fully coupled climate model we are able to explore the feedbacks of soils and lakes on the climate of the late Pliocene. Our experiments reveal regionally confined changes of local climate and vegetation in response to the new boundary conditions. The addition of late Pliocene soils has the largest influence on surface air temperatures, with notable increases in Australia, the southern part of northern Africa and in Asia. The inclusion of late Pliocene lakes increases precipitation in central Africa and at the locations of lakes in the Northern Hemisphere. When combined, the feedbacks on climate from late Pliocene lakes and soils improve the data to model fit in western North America and the southern part of northern Africa

Late Pliocene lakes and soils: a data-model comparison for the analysis of climate feedbacks in a warmer world

Based on a synthesis of geological data we have reconstructed the global distribution of Late Pliocene soils and lakes which are then used as boundary conditions in a series of model experiments using the Hadley Centre General Circulation Model (HadCM3) and the BIOME4 mechanistic vegetation model. By combining our novel soil and lake reconstructions with a fully coupled climate model we are able to explore the feedbacks of soils and lakes on the climate of the Late Pliocene. Our experiments reveal regionally confined changes of local climate and vegetation in response to the new boundary conditions. The addition of Late Pliocene soils has the largest influence on surface air temperatures, with notable increases in Australia, southern North Africa and Asia. The inclusion of Late Pliocene lakes generates a significant increase in precipitation in central Africa, as well as seasonal increases in the Northern Hemisphere. When combined, the feedbacks on climate from Late Pliocene lakes and soils improve the data to model fit in western North America and southern North Africa

Electronic cigarette use among adult smokers: longitudinal associations with smoking and trait impulsivity

Objective: The present exploratory study uses a longitudinal design to assess the associations between electronic cigarette (e-cigarette) use and cigarette smoking, motivation to quit and trait impulsivity among adult smokers. // Methods: One hundred and sixteen cigarette smokers only and ninety-one dual users (smoke cigarettes and use e-cigarettes) were recruited (mean age [standard deviation] = 25.11[6.94], male = 48.3%). Participants were recruited online and 121 were followed-up at 3 months. Participants completed online questionnaires regarding socio-demographics, smoking/e-cigarette use characteristics and trait impulsivity at baseline, and they self-reported their smoking status at 3-month follow-up. // Results: The use of e-cigarettes in cigarette smokers was associated with a higher rate of stopping cigarette smoking at follow-up, relative to smokers who did not use e-cigarettes (χ2[1] = 11.03, p < 0.01). Multivariate logistic regressions controlling for age and gender showed a significant association between motivation to quit and stopping cigarette smoking at follow-up (odds ratio = 2.11, 99% Confidence Interval = 1.12–3.97, p < 0.01). There was no link between trait impulsivity and stopping cigarette smoking. // Conclusions: The data suggest that e-cigarettes may increase rates of quitting cigarette smoking

Examining the relationship between impulsivity-related personality traits and e-cigarette use in adults

Aims The present study aimed to investigate the relationship between impulsivity-related personality traits based on the UPPS-P model and e-cigarette use. The study used a sample of mainly European adults and compared e-cigarette users with non-smokers, cigarette smokers and dual users (those who currently smoke cigarettes and use e-cigarettes). Additionally, the relationship between impulsivity-related traits and frequency and intensity of e-cigarette use was examined, while the main reasons for e-cigarette use were also assessed. Methods Participants were 720 adults (234 non-smokers, 164 smokers, 150 e-cigarette users, 172 dual users), who completed online questionnaires regarding sociodemographics, smoking/e-cigarette use behaviour, and impulsivity (UPPS-P scale). Results Impulsivity-related traits did not significantly differentiate e-cigarette users from non-smokers. E-cigarette users showed lower levels of lack of perseverance than cigarette smokers, and they exhibited lower levels of negative and positive urgency than dual users. Negative urgency also significantly differentiated smokers and non-smokers, with smokers having higher levels of the trait. No significant results were found examining the relationship between the impulsivity-related traits and e-cigarette behaviour (number of days vaping per month, number of times vaping per day, and millilitres of e-liquid used per day). The main reason given for e-cigarette use was the perception that it is less harmful than cigarettes. Conclusion The present study found that trait impulsivity differentiated e-cigarette users from cigarette smokers and dual users, but did not differentiate e-cigarette users from non-smokers. Such findings are important to not only help us identify factors associated with e-cigarette use, but also to potentially inform treatment plans and decisions

Social interaction anxiety, social phobia, and cognitive control: controlled reactions to facial affect during an emotional face flanker task

Trait social anxiety may predict differences in the cognitive control of emotional distraction when emotional face discrimination is required. This effect can be investigated using an emotional face flanker task. This study addresses an important research gap, as previous studies did not separate the effects of trait social interaction anxiety from the effects of trait social phobia upon emotional face flanker task performance. In this laboratory based behavioural experiment, the 87 participants (mean age 24.3) were university students or staff recruited via departmental adverts. We used an emotional (happy versus fearful) face flanker task, and assessed sub-clinical social anxiety with the SIAS/SPS. Elevated trait social phobia was related to an increased reaction time (RT) congruency effect, whereas trait social interaction anxiety was not. Elevated trait social interaction anxiety was related to a decreased happy face RT advantage for central target faces, but the effect of trait social phobia was very weak. Trait social interaction anxiety and trait social phobia may predict subtle differences when the cognitive control of reactions to emotional facial expressions is required

A facial expression for anxiety.

Anxiety and fear are often confounded in discussions of human emotions. However, studies of rodent defensive reactions under naturalistic conditions suggest anxiety is functionally distinct from fear. Unambiguous threats, such as predators, elicit flight from rodents (if an escape-route is available), whereas ambiguous threats (e.g., the odor of a predator) elicit risk assessment behavior, which is associated with anxiety as it is preferentially modulated by anti-anxiety drugs. However, without human evidence, it would be premature to assume that rodent-based psychological models are valid for humans. We tested the human validity of the risk assessment explanation for anxiety by presenting 8 volunteers with emotive scenarios and asking them to pose facial expressions. Photographs and videos of these expressions were shown to 40 participants who matched them to the scenarios and labeled each expression. Scenarios describing ambiguous threats were preferentially matched to the facial expression posed in response to the same scenario type. This expression consisted of two plausible environmental-scanning behaviors (eye darts and head swivels) and was labeled as anxiety, not fear. The facial expression elicited by unambiguous threat scenarios was labeled as fear. The emotion labels generated were then presented to another 18 participants who matched them back to photographs of the facial expressions. This back-matching of labels to faces also linked anxiety to the environmental-scanning face rather than fear face. Results therefore suggest that anxiety produces a distinct facial expression and that it has adaptive value in situations that are ambiguously threatening, supporting a functional, risk-assessing explanation for human anxiet