Liquid-Templating Aerogels

Modern materials science has witnessed the era of advanced fabrication methods to engineer functionality from the nano- to macroscales. Versatile fabrication and additive manufacturing methods are developed, but the ability to design a material for a given application is still limited. Here, a novel strategy that enables target-oriented manufacturing of ultra-lightweight aerogels with on-demand characteristics is introduced. The process relies on controllable liquid templating through interfacial complexation to generate tunable, stimuli-responsive 3D-structured (multiphase) filamentous liquid templates. The methodology involves nanoscale chemistry and microscale assembly of nanoparticles (NPs) at liquid-liquid interfaces to produce hierarchical macroscopic aerogels featuring multiscale porosity, ultralow density (3.05-3.41 mg cm-3 ), and high compressibility (90%) combined with elastic resilience and instant shape recovery. The challenges are overcome facing ultra-lightweight aerogels, including poor mechanical integrity and the inability to form predefined 3D constructs with on-demand functionality, for a multitude of applications. The controllable nature of the coined methodology enables tunable electromagnetic interference shielding with high specific shielding effectiveness (39 893 dB cm2 g-1 ), and one of the highest-ever reported oil-absorption capacities (487 times the initial weight of aerogel for chloroform), to be obtained. These properties originate from the engineerable nature of liquid templating, pushing the boundaries of lightweight materials to systematic function design and applications.

Development of a model to investigate the effects of prolonged ischaemia on the muscles of mastication of male Sprague Dawley rats

OBJECTIVE

The aims of this study were to develop a novel rodent model of masticatory muscle ischaemia via unilateral ligation of the external carotid artery (ECA), and to undertake a preliminary investigation to characterize its downstream effects on mechanosensitivity and cellular features of the masseter and temporalis muscles.

DESIGN

The right ECA of 18 male Sprague-Dawley rats was ligated under general anaesthesia. Mechanical detection thresholds (MDTs) at the masseter and temporalis bilaterally were measured immediately before ECA ligation and after euthanasia at 10-, 20-, and 35-days (n = 6 rats/timepoint). Tissue samples from both muscles and sides were harvested for histological analyses and for assessing changes in the expression of markers of hypoxia and muscle degeneration (Hif-1α, VegfA, and Fbxo32) via real time PCR. Data were analyzed using mixed effect models and non-parametric tests. Statistical significance was set at p < 0.05.

RESULTS

MDTs were higher in the right than left hemiface (p = 0.009) after 20 days. Histological changes indicative of muscle degeneration and fibrosis were observed in the right muscles. Hif-1α, VegfA, and Fbxo32 were more highly expressed in the masseter than temporalis muscles (all p < 0.05). Hif-1α and, VegfA did not change significantly with time in all muscles (all p > 0.05). Fbxo32 expression gradually increased in the right masseter (p = 0.024) and left temporalis (p = 0.05).

CONCLUSIONS

ECA ligation in rats induced hyposensitivity in the homolateral hemiface after 20 days accompanied by tissue degenerative changes. Our findings support the use of this model to study pathophysiologic mechanisms of masticatory muscle ischaemia in larger investigations.

Incidence and characterization of resistance to pyrethroid and organophosphorus insecticides in Thrips tabaci (Thysanoptera: Thripidae) in onion fields in Isfahan, Iran

Onion thrips, Thrips tabaci Lindeman, is the main pest of onion-growing fields in Isfahan and is mainly controlled by frequently spraying several insecticides. To investigate the resistance status and mechanisms, the susceptibility of ten field populations collected from Isfahan onion-growing regions were tested to several currently used pesticides. Resistance to the tested insecticides was observed in most populations when compared with the susceptible reference population. Enhanced detoxification, implicated by the use of inhibitors of major metabolic detoxification enzymes, was observed in the populations resistant to profenofos and chlorpyrifos. In the deltamethrin resistant populations, the amino acid substitution T929I was detected in the voltage gated sodium channel, which is known to confer pyrethroid resistance. These data are a first step towards more efficient resistance management tactics through early detection of resistant onion thrips in Iran.

Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading

Functional colloidal materials were prepared by design through the self-assembly of nanoparticles (NPs) on the surfaces of polystyrene (PS) spheres with control over NP surface coverage, NP-to-NP spacing, and NP composition. The ability to control and fine tune the coating was extended to the first demonstration of the co-assembly of NPs of dissimilar composition onto the same PS sphere, forming a multi-component coating. A broad range of NP decorated PS (PS@NPs) spheres were prepared with uniform coatings attributed to electrostatic and hydrogen bonding interactions between stabilizing groups on the NPs and the functionalized surfaces of the PS spheres. This versatile two-step method provides more fine control than methods previously demonstrated in the literature. These decorated PS spheres are of interest for a number of applications, such as catalytic reactions where the PS spheres provide a support for the dispersion, stabilization, and recovery of NP catalysts. The catalytic properties of these PS@NPs spheres were assessed by studying the catalytic degradation of azo dyes, an environmental contaminant detrimental to eye health. The PS@NPs spheres were used in multiple, sequential catalytic reactions while largely retaining the NP coating.