353 research outputs found
Looking Thru the Nano Lens: Art, Science and Nature
In 2018, an interdisciplinary team of researchers from the School of Chemistry, Sydney Nano and the Department of Art History at the University of Sydney set up a pilot project called the Nano Lens. Our project set out to examine and experiment with what it means to look closely at the natural world and inviting us, as colleagues, into a discussion and collaboration, drawing on our different perspectives. The Nano Lens also gave agency to a group of scientists in training (undergraduate and postgraduate students), and a sense of ownership of the science, which was then transmitted to the public. Taking inspiration from the artwork of the prominent Australian painter Margaret Preston (1875-1963) and the flora she depicted, the Nano Lens has opened up new research that intersects science and the arts; celebrating the value of collaboration and offering opportunities for staff and students to engage in and lead interdisciplinary discussions with the public. This paper will discuss our pilot project and the initial findings of our research together and discuss the benefits that our alliance has had in fostering collaboration and outreach activities where academics and students work together to share their research with the public. We seek to reflect on what we have learnt from the project and from opportunities to share our work and approaches. What does it mean to look like a scientist or to look like an artist and how has this enriched student learning? What value is there in opening up opportunities for informal learning about science and collaboration outside your disciplines
Effect of Pore Size, Lubricant Viscosity, and Distribution on the Slippery Properties of Infused Cement Surfaces
The fabrication of slippery liquid-infused
porous surfaces (SLIPS)
usually requires the use of structured substrates, with specifically
designed micro- and nanoroughness and complementary surface chemistry,
ideally suited to trap lubricants. It is not yet established whether
a random roughness, with a range of pores with a variable size reaching
deep into the bulk of the material, is suitable for successful infusion.
In this study, a highly porous material with random and complex roughness,
obtained by using portland cement (the most common type of cementitious
material), was tested for its potential to act as a SLIP surface.
Atomic force microscopy meniscus measurements were used to investigate
the distribution of lubricants on the surface upon subsequent stages
of depletion because of the capillary absorption of the lubricant
within the porous structure. Factors such as curing time of the cement
paste, time since infusion, and lubricant viscosity were varied to
identify the conditions under which infusion could be considered successful.
A sensitive method to evaluate the penetration of liquid (low-temperature
differential scanning calorimetry) was used, which could be applicable
to many porous materials. The optimized infusion of cement surfaces
ultimately resulted in the desired hallmarks of SLIPS, that is, high
water repellence and slipperiness, effective for several weeks, reduced
water permeability, and icephobicity
Functional Selectivity Does Not Predict Antinociceptive/Locomotor Impairing Potencies of NOP Receptor Agonists
Nociceptin/orphanin FQ controls several functions, including pain transmission, via stimulation of the N/OFQ peptide (NOP) receptor. Here we tested the hypothesis that NOP biased agonism may be instrumental for identifying innovative analgesics. In vitro experiments were performed with the dynamic mass redistribution label free assay and the NOP non-peptide agonists Ro 65-6570, AT-403 and MCOPPB. In vivo studies were performed in wild type and β-arrestin 2 knockout mice using the formalin, rotarod and locomotor activity tests. In vitro all compounds mimicked the effects of N/OFQ behaving as potent NOP full agonists. In vivo Ro 65-6570 demonstrated a slightly higher therapeutic index (antinociceptive vs. motor impairment effects) in knockout mice. However, all NOP agonists displayed very similar therapeutic index in normal mice despite significant differences in G protein biased agonism. In conclusion the different ability of inducing G protein vs. β-arrestin 2 recruitment of a NOP agonist cannot be applied to predict its antinociceptive vs. motor impairment properties
Slightly Depleted Lubricant-Infused Surfaces Are No Longer Slippery
Textured surfaces infused with a lubricating fluid
effectively reduce fouling and drag. These functions critically depend
on the presence and distribution of the lubricant, which can be
depleted by many mechanisms, including shear flow. We present a
two-phase Couette flow computational dynamic simulation over
lubricant-infused surfaces containing grooves oriented perpendicular
to the flow direction, with the aim of revealing how interfacial slip, and
therefore drag reduction, is impacted by lubricant depletion. We show
that even a slight (20%) lubricant loss decreases slip to the point of
making the lubricant superfluous, even for lubricants with lower
viscosity than the flowing liquid and regardless of how well the
lubricant wets the grooves. We explain that the drastic slip reduction is linked to a significant increase in the total viscous dissipation
and to zero dissipation in the lubricant (similar to the one given by a no-slip boundary)
Pressure drop measurements in microfluidic devices: a review on the accurate quantification of interfacial slip
The correct theoretical definition of boundary conditions of flow underpins
all fluid dynamics studies, and is particularly important in situations in which
the flow is confined on the nano- and micro-scale. Microfluidic devices are
an excellent platform to measure boundary flow conditions, and the pressure
drop versus flow rate method is particularly useful in detecting evidence
of microscale interfacial slip and drag reduction. This review focuses on
the pressure drop method, identifying the main experimental parameters
affecting the accuracy and reproducibility of microfluidic experiments of slip,
quantifying the magnitude and source of common errors, and providing
practical solutions and guidelines. A summary of literature results of interfacial
slip obtained with pressure drop measurements in microfluidic devices
is also provided, and the slip results are directly compared to expected slip
models. This review serves as an introduction for new researchers moving
into the field of interfacial slip, and as reminder for established researchers
of the need to create highly controlled experimental procedures in order
to obtain reproducible and reliable measurements of boundary flow conditions.
A direct comparison of accurate experiments with theoretical models
is bound to bring about clarity about the mechanisms of slip on smooth and
structured surfaces
Mechanical properties of Ropaque hollow nanoparticles
The elastic properties and strength upon compression of commercial Ropaque polystyrene hollow particles were investigated by atomic force microscopy (AFM). These particles are commonly used in paints as opacifying agents, as their internal air void effectively scatters light. A sharp AFM tip was used to apply a point load to the particle surface, and increased to probe both the elastic and plastic deformation of the shell, and then further until the shell broke. For small deformations, the deformation increased linearly with applied force. The Youngâs modulus was calculated by accounting for the effect of the rigid substrate, and compare the modulus obtained from the Reissner and Hertz models. The minimum stress needed to destroy the integrity of the shell was extracted and found to be smaller than or close to that of silica hollow particles with different shell thickness tested in the literature.Australian Research Council and DuluxGroup Australia through Linkage gran
Micropatterned Substrates Made by Polymer Bilayer Dewetting and Collagen Nanoscale Assembly Support Endothelial Cell Adhesion
The ability to control protein and cell positioning on a microscopic scale is crucial in many biomedical applications, such as tissue engineering and the development of biosensors. We demonstrate here that the assembly of collagen on patterned surfaces produced by the dewetting of metastable poly(N-vinylpyrrolidone) (PNVP) films on top of polystyrene films supports the adhesion and survival of a biologically relevant cell type, human endothelial cells. Micropatterning of Type 1 collagen was achieved on such substrates by exploiting the different protein affinity of the two polymers, the effect of treatment with an air plasma, and the control over the nanoscale assembly of collagen using different adsorption conditions. The simplicity of the dewetting approach, coupled with the ability to coat and pattern non-planar substrates, gives rise to possible applications in the coating of biological implants such as arterial stents
Synthesis and applications of polymeric Janus nanoparticles
Research into Janus particles has received great attention over the past decade. In his
Nobel lecture in 1991, Pierre-Gilles de Gennes suggested that asymmetric colloidal
particles with different chemical compositions on the two lobes could have a special
behaviour at interfaces, and named them âJanus grains.1 Due to their asymmetry, Janus
particles have the ability to offer more advanced chemical and physical properties
compared to that of their symmetric homogeneous counterparts and in particular may
behave as amphiphilic surfactants. However, for years after de Gennesâ Nobel lecture,
research into Janus particles was still slow, as evidenced by the limited number of
publications in the field. The main limitations to the advancement of the field were the
difficulty in synthesising well-defined Janus particles and also in characterising them,
especially in the case of nanometer-sized Janus particles. From around 2005, the
significance of Janus particles in a wide range of applications has become clear, including
in surfactants, electrochemistry, catalysis, electronics, sensors, optics, superhydrophobic
textiles and nanomedicine, and this has driven research to pursue different methods for
the fabrication of Janus particles. In the past ten years, Janus particles have become a hot
topic of research, as evidenced by the exponential growth in the number of publications in
this area. Our latest search using the keyword âJanus particlesâ on Web of Science shows
1,608 published research papers on this topic which is more than 16 times higher than in
2010
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