Controlling morphology and porosity of porous siloxane membranes through water content of precursor microemulsion

Here we report a facile method for controlling the morphology and porosity of porous siloxane membranes through manipulation of the water content of precursor microemulsions. The polymerizable microemulsion precursors consisted of a methacrylate-terminated siloxane macromonomer (MTSM) as the oil phase, nonionic surfactant (Teric G9A8), water, and cosurfactant (isopropanol). Photo-polymerization of the oil phase in the parent microemulsion solutions resulted in polymeric solids, and subsequent removal of the extractable components yielded porous PDMS membranes. The pre-cured parent microemulsion solutions and post-cured polymers were characterized by small angle X-ray scattering (SAXS) while the nanostructures of extracted porous polymer membranes were characterized by SAXS, scanning electron microscopy (SEM) and mercury porosimetry. The results indicated that nano- and micro-structures of the membranes could be modulated by the water content of the precursor microemulsions. Further, in situ photo-rheometry was used to follow the microemulsion polymerization process. The rate of polymerization and the mechanical properties of the resulting PDMS membranes also depend on the water content of precursor microemulsions. This study demonstrates a simple approach to the fabrication of a variety of novel porous PDMS membranes with controllable morphology and porosity.

Structure retention in cross-linked poly(ethylene glycol) diacrylate hydrogel templated from a hexagonal lyotropic liquid crystal by controlling the surface tension

Retaining hexagonal lyotropic liquid crystal (LLC) structures in polymers after surfactant removal and drying is particularly challenging, as the surface tension existing during the drying processes tends to change the morphology. In this study, cross-linked poly(ethylene glycol) diacrylate (PEGDA) hydrogels were prepared in LLC hexagonal phases formed from a dodecyltrimethylammonium bromide (DTAB)/water system. The retention of the hexagonal LLC structures was examined by controlling the surface tension. Polarized light microscopy, X-ray diffraction and small angle X-ray scattering results indicate that the hexagonal LLC structure was successfully formed before polymerization and well retained after polymerization and after surfactant removal when the surface tension forces remained neutral. Controlling the surface tension during the drying process can retain the nanostructures templated from lyotropic liquid crystals which will result in the formation of materials with desired nanostructures.

Controlling the philosophical imaginary: reading Pierre Hadot with Luiz Costa Lima

This essay proffers a critical complement to Luiz Costa Lima's claims concerning the nature, history, and control of the imagination in Western culture. Accepting the wide scope of Costa Lima's critical claim about the socio-political control of imaginative literature in Western history, we claim that Pierre Hadot's work on philosophy as a bios in the ancient West cautions us lest we position philosophy in this history as always and necessarily an agency of control. At different times, philosophy has rather stood as an ally in practicing and promoting forms of criticity, and the playful, creative, and transformative envisaging of alternative ways of experiencing the world Costa Lima theoretically celebrates in literary fiction. Any critique of philosophy as always opposed to the critical imagination can only stand, we have argued, relative to philosophy as conceived on what Hadot suggests is but one, albeit the now hegemonic model: namely, as a body of systematic rational discourses, including discourses about the literary, poetics, and imaginary. What this vision of philosophy misses, Hadot shows, is how the ancient conception of philosophy (which survives in figures like Montaigne, Nietzsche, and Goethe) as a way of life promoted distinctly literary, aesthetic, and imaginative practices; first, to assist in the existential internalisation of the schools' ideas; secondly, to envisage in the sage and utopias edifying counterfactuals to help students critically reimagine accepted norms; and thirdly, in the conception of a transformed way of living and perceiving ‘according to nature’, whose parameters of autonomy and pleasurable contemplation of the singularity of the present experiences anticipate the experiences delineated in modern aesthetic theory.

Evaluation of management scenarios for controlling eutrophication in a shallow tropical urban lake

Urban lakes are typically smaller, shallower, and more exposed to human activities than natural lakes. Although the effects of harmful algal blooms (HABs) associated with eutrophication in urban lakes has become a growing concern for water resources management and environmental protection, studies focussing on this topic in relation to urban lakes are rare and knowledge of the ecological dynamics and effective management strategies for controlling eutrophication in urban lakes is lacking. This study applied an integrated three-dimensional hydrodynamics-ecological model for a small shallow tropical urban lake in Singapore and evaluated various management scenarios to control eutrophication in the lake. It is found that in-lake treatment techniques including artificial destratification, sediment manipulation and algaecide addition are either ineffective or possess environmental concerns; while watershed management strategies including hydraulic flushing and inflow nutrients reduction are more effective and have posed less environmental concerns. In this study, inflow phosphorus reduction was found to be the best strategy after evaluating the advantages and drawbacks of the management strategies studied. Runoff from the watershed exerts significant influence on urban lakes and thus an integrated water resources management at the watershed level is critical for the control of eutrophication

Do children with autism and Asperger's disorder have difficulty controlling handwriting size? A kinematic evaluation

Children with autism spectrum disorders (ASD) often show difficulties in controlling letter size and consistent letter formation during handwriting; however, there has been little research into the underlying nature of handwriting impairments in this group. The aim of this study was to assess the ability of children with ASD to regulate the size and consistency of fundamental handwriting movements when using writing guides, and determine whether the kinematic profile during writing is different to typically developing children. Twenty-six boys with ASD (16 with high-functioning autism, 10 with Asperger's disorder) aged 8-13 years (IQ > 75), and 17 typically developing children wrote a series of four cursive letter l's using 10 mm and 40 mm writing guides, using a graphics tablet and stylus. Movement size and consistency was comparable between groups when the writing guides were set at 10 mm; however, handwriting movements of children with ASD were significantly faster and more fluent than typically developing children when writing guides were set at 40 mm. Neuromotor noise was comparable to that of typically developing children across both writing sizes. Clinically, our findings indicate that children with ASD have a well-automated motor plan for simple handwriting movements when writing guides are present and that problems of handwriting legibility in ASD are likely to arise from other factors, such as complex motor chaining (i.e. writing whole words and sentences), or attentional, working memory and linguistic demands when writing.

Homogeneous isolation of nanocelluloses by controlling the shearing force and pressure in microenvironment

Nanocelluloses were prepared from sugarcane bagasse celluloses by dynamic high pressure microfluidization (DHPM), aiming at achieving a homogeneous isolation through the controlling of shearing force and pressure within a microenvironment. In the DHPM process, the homogeneous cellulose solution passed through chambers at a higher pressure in fewer cycles, compared with the high pressure homogenization (HPH) process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that entangled network structures of celluloses were well dispersed in the microenvironment, which provided proper shearing forces and pressure to fracture the hydrogen bonds. Gel permeation chromatography (GPC), CP/MAS 13C NMR and Fourier transform infrared spectroscopy (FT-IR) measurements suggested that intra-molecular hydrogen bonds were maintained. These nanocelluloses of smaller particle size, good dispersion and lower thermal stability will have great potential to be applied in electronics devices, electrochemistry, medicine, and package and printing industry. © 2014 Elsevier Ltd.

Reported and observed controlling feeding practices predict child eating behavior after 12 months

BACKGROUND: Controlling feeding practices are linked to children's self-regulatory eating practices and weight status. Maternal reports of controlling feeding practices are not always significantly related to independently rated mealtime observations. However, prior studies only assessed 1 mealtime observation, which may not be representative of typical mealtime settings or routines. OBJECTIVES: The first aim was to examine associations between reported and observed maternal pressure to eat and restriction feeding practices at baseline (T1) and after ∼12 mo (T2). The second aim was to evaluate relations between maternal and child factors [e.g., concern about child weight, child temperament, child body mass index (BMI)-for-age z scores (BMIz)] at T1 and reported and observed maternal pressure to eat and restriction feeding practices (T1 and T2). The third aim was to assess prospective associations between maternal feeding practices (T1) and child eating behaviors (T2) and child BMIz (T2). METHODS: A sample of 79 mother-child dyads in Victoria, Australia, participated in 2 lunchtime home observations (T1 and T2). BMI measures were collected during the visits. Child temperament, child eating behaviors, maternal parenting styles, and maternal feeding practices were evaluated at T1 and T2 via questionnaires. Associations were assessed with Pearson's correlation coefficients, paired t tests, and hierarchical regressions. RESULTS: Reported restriction (T1) was inversely associated with observed restriction at T1 (r = -0.24, P < 0.05). Reported pressure to eat (T2) was associated with observed pressure to eat (T2) (r = 0.48, P < 0.01) but only for mothers of girls. Maternal weight concern was associated with reported restriction at T1 (r = 0.29, P < 0.01) and T2 (r = 0.36, P < 0.01), whereas observed restriction (T1) was prospectively associated child BMI at T2 (β = -0.18, P < 0.05). CONCLUSIONS: Maternal reports may not always reflect feeding practices performed during mealtimes; it is possible some mothers may not be aware of their practices or observations may not capture covert controlling strategies.

A review on computational intelligence methods for controlling traffic signal timing

Urban traffic as one of the most important challenges in modern city life needs practically effective and efficient solutions. Artificial intelligence methods have gained popularity for optimal traffic light control. In this paper, a review of most important works in the field of controlling traffic signal timing, in particular studies focusing on Q-learning, neural network, and fuzzy logic system are presented. As per existing literature, the intelligent methods show a higher performance compared to traditional controlling methods. However, a study that compares the performance of different learning methods is not published yet. In this paper, the aforementioned computational intelligence methods and a fixed-time method are implemented to set signals times and minimize total delays for an isolated intersection. These methods are developed and compared on a same platform. The intersection is treated as an intelligent agent that learns to propose an appropriate green time for each phase. The appropriate green time for all the intelligent controllers are estimated based on the received traffic information. A comprehensive comparison is made between the performance of Q-learning, neural network, and fuzzy logic system controller for two different scenarios. The three intelligent learning controllers present close performances with multiple replication orders in two scenarios. On average Q-learning has 66%, neural network 71%, and fuzzy logic has 74% higher performance compared to the fixed-time controller.

Controlling shareholder, expropriations and firm’s leverage decision: Evidence from Chinese Non-tradable share reform

This paper examines the effect of excess control rights on the leverage decisions made by Chinese non-SOEs before and after the Non-tradable share reform (NTS reform). We find that firms with excess control rights have more excess leverage and their controlling shareholders use the resources for tunneling rather than investing in positive NPV projects. We also find that excess leverage in firms with excess control rights decreases and the market reaction to announcements of related party transactions are more positive after NTS reform. This confirms that tunneling by the controlling shareholders actually reduced. We argue that in emerging markets where legal protection for creditors and shareholders is weak, controlling shareholders borrow excess debt to tunnel through inter-corporate loans and related party transactions. Furthermore the privatization of these economies can reduce the controlling shareholders' tunneling activities and associated excess leverage which destroys firm value.

Ductile thermoset polymers via controlling network flexibility

We report the design and synthesis of a polymer structure from a cross-linkable epoxy-ionic liquid system which behaves like a hard and brittle epoxy thermoset, perfectly ductile thermoplastic and an elastomer, all depending on controllable network compositions.