Controllable corrugation of chemically converted graphene sheets in water and potential application for nanofiltration

A combination of AFM, SEM and permeation experiments suggests that the amplitude of corrugation of chemically converted graphene (CCG) sheets in water can be readily controlled by hydrothermal treatment, leading to a new class of permeation-tuneable nanofiltration membranes.

Bubble-solid interactions in water and electrolyte solutions

Surface forces between an air bubble and a flat mica surface immersed in aqueous electrolyte solutions have been investigated using a modified surface force apparatus. An analysis of the deformation of the air bubble with respect to the mutual position of the bubble and the mica surface, the capillary pressure, and the disjoining pressure allows the air-liquid surface electrical potential to be determined. The experiments show that a long-range, double-layer repulsion acts between the mica (which is negatively charged) and an air bubble in water and in various electrolyte solutions at low concentration, thereby indicating that the air bubble surface is negatively charged. However, there is clear evidence that charge regulation occurs at the air-water interface to maintain a constant surface potential, and as a result of this, the charge at this interface changes from negative to positive as the bubble approaches the mica surface. Because of the attraction that arises as a result of the charge reversal, a finite force is required to separate the bubble from the mica, though the mica remains wetted by the aqueous phase. At the low concentrations investigated, the potential on the gas-liquid interface is independent of the electrolyte type within experimental uncertainty.

Stability of aqueous films between bubbles. Part 1. The effect of speed on bubble coalescence in purified water and simple electrolyte solutions

Film thinning experiments have been conducted with aqueous films between two air phases in a thin film pressure balance. The films are free of added surfactant but simple NaCl electrolyte is added in some experiments. Initially the experiments begin with a comparatively large volume of water in a cylindrical capillary tube a few millimeters in diameter, and by withdrawing water from the center of the tube the two bounding menisci are drawn together at a prescribed rate. Thismodels two air bubbles approaching at a controlled speed. In pure water, the results show three regimes of behavior depending on the approach speed; at slow speed (<1 μm/s) it is possible to form a flat film of pure water, ∼100 nm thick, that is stabilized indefinitely by disjoining pressure due to repulsive double-layer interactions between naturally charged air/water interfaces. The data are consistent with a surface potential of -57mV on the bubble surfaces. At intermediate approach speed (∼1-150 μm/s), the films are transiently stable due to hydrodynamic drainage effects, and bubble coalescence is delayed by ∼10-100 s. At approach speeds greater than ∼150 μm/s, the hydrodynamic resistance appears to become negligible, and the bubbles coalesce without any measurable delay. Explanations for these observations are presented that take into account Derjaguin-Landau-Verwey-Overbeek and Marangoni effects entering through disjoining pressure, surface mobility, and hydrodynamic flow regimes in thin film drainage. In particular, it is argued that the dramatic reduction in hydrodynamic resistance is a transition from viscosity-controlled drainage to inertia-controlled drainage associated with a change from immobile to mobile air/water interfaces on increasing the speed of approach of two bubbles. A simple model is developed that accounts for the boundaries between different film stability or coalescence regimes. Predictions of the model are consistent with the data, and the effects of adding electrolyte can be explained. In particular, addition of electrolyte at high concentration inhibits the near-instantaneous coalescence phenomenon, thereby contributing to increased foam film stability at high approach speeds, as reported in previous literature. This work highlights the significance of bubble approach speed as well as electrolyte concentration in affecting bubble coalescence.

Diversity and architecture

Architecture can be defined as the art and tectonics of place making. The discipline of architecture involves a broad set of practices including design of the built environment, development of architectural projects either community~ based or oriented towards a (private) client, and advisory work for governments. Architecture also involves a wide spectrum of knowledge including urban design and urban planning, and a variety of architectural ideas, theories and movements. Various dominant ideologies have manifested themselves in built form, whereas other, marginal cultural parameters have emerged in the vernacular or traditional architecture. Architecture is considered the medium through which society is organised and materialised. It resonates with symbolic meaning as well as pragmatic order through built places.

The idea of Rome in Fascist art and architecture : the decorative program of the Palazzo dei Congressi in EUR, Rome

This paper engages with the notion of interspace by examining an understudied and unpublished cycle of mosaics and frescoes destined for the main hall of the Palazzo dei Congressi in Rome’s south-western suburb of EUR, a major building project by Roman architect Adalberto Libera. It first provides a socio-historical and aesthetic background to the building of EUR as Rome’s international exposition of 1942, which aimed to celebrate the achievements of Italian (and fascist) civilisation. It then focuses on the concept of Romanità (or Roman-ness) as a mythical and idealised past that was engaged on a number of levels as a teleological foundation for the advent (and eternity) of fascist rule. This past was adopted, interpreted and made manifest at the urban scale in the master plan of EUR, at the architectural scale in the buildings and at the interior scale in the decorative programs incorporated in each. It argues that the Palazzo dei Congressi allows us to gain further insight into the notion of interspace as it exemplifies this on a number of physical, symbolic and temporal levels. Physically, in the urban space, architectural form and interiors; symbolically, in the content and compositional layout of the mosaics; and temporally, in the use of historical elision and conflation between mythical pasts and idealised present.

The influence of water and metal ions on the transport properties of Trihexyl(tetradecyl)phosphonium chloride

A recent study indicated that the water-saturated ionic liquid (IL) trihexyl(tetradecyl)phosphonium chloride ([P_6,6,6,14][Cl]) provided a viable electrolyte for a Mg-air battery. However, there is limited literature on the properties of IL-water mixtures as battery electrolytes. The physical properties of [P_6,6,6,14][Cl] were studied with the addition of both water and metal salts (M_gCl₂ and LiCl) using conductivity and self-diffusion coefficient measurements. The conductivity of the samples at low water concentrations is surprisingly enhanced by the addition of the metal salt, contrary to lithium IL electrolytes. It was also found that the conductivity of the IL was increased by an order of magnitude by saturation with water. NMR diffusion measurements were used to probe the behaviour of both the cation and the water in the mixtures. It was found that the addition of metal salts to the water-saturated [P_6,6,6,14][Cl] did not affect the transport properties of the water or cation.

Occurrence of antibiotic resistance genes in reclaimed water and river water in the Werribee Basin, Australia

The purpose of this study was to investigate the occurrence of antibiotic resistance genes (ARGs) in water used for irrigation in the Werribee River Basin, Australia, including river water and reclaimed effluent water (reclaimed water). Samples of reclaimed water, collected over a one-year period, were screened for the occurrence of ARGs using PCR detection assays. The presence of ARGs in the reclaimed water samples were contrasted with that of water samples taken from the Werribee River Basin, collected over the same time period, from five points selected for varying levels of urban and agricultural impact. Of the 54 river water samples collected, 2 (4%), 2 (4%), 0 and 0 were positive for methicillin, sulfonamide, gentamicin and vancomycin-resistant genes, respectively, while 6 of 11 reclaimed water samples were positive for methicillin (9%) and sulfonamide (45%). The presence/absence of ARGs did not appear to correlate with other measured water quality parameters. The low detection of ARGs in river water indicates that, regardless of its poor quality, the river has not yet been severely contaminated with ARGs. The greater prevalence of ARGs in reclaimed water indicates that this important agricultural water source will need to be monitored into the future.

Not-I/Thou : the other subject of art and architecture

Not-I/Thou: The Other Subject of Art and Architecture is a series of essays delineating the gray areas and black zones in present-day cultural production. Part One is an implicit critique of neoliberal capitalism and its assault on the humanities through the pseudo-scientific and pseudo-empirical biases of academic and professional disciplines, while Part Two returns to apparent lost causes in the historical development of modernity and post-modernity, particularly the recourse to artistic production as both a form of mnemonics and periodic (and renascent) avant-garde agitation. In-between these twin systems of taking the measure of things, Art and Architecture, as forms of speculative intellectual capital, emerge from the shadow-lands of half-conscious and half-unconscious forces to become gestures toward a type of knowledge that has no utilitarian or generic agency. Defying the tendencies of such discourses to fall prey to instrumental orders that effectively neuter the inherent radical agenda of both, Art and Architecture are represented in this series of essays as noetic apparatuses, operating at the edge of authorized systems of knowledge, quietly and secretly validating and valorizing the shadowy and recondite, collective and personal operations of intellect in service to no particular end.