On the directionality of membrane coupled Helmholtz resonators under open air conditions.

Controlling the absorption and diffusion of sound in the audible range constitutes an exciting field of research. Acoustic absorbers and diffusers perform extraordinarily well at high frequencies with sizes comparable to the wavelength of the working frequency. Conversely, efficient low-frequency attenuators demand large volumes leading to unpractical sizes, and there is now interest in determining whether the size of the resonator can be reduced while not compromising - or perhaps even decreasing - the working frequency.

An adjustable acoustic metamaterial cell using a magnetic membrane for tunable resonance.

Acoustic metamaterials are growing in popularity for sound applications including noise control. Despite this, there remain significant challenges associated with the fabrication of these materials for the sub-100 Hz regime, because acoustic metamaterials for such frequencies typically require sub-mm scale features to control sound waves. Advances in additive manufacturing technologies have provided practical methods for rapid fabrication of acoustic metamaterials.

Developing and Investigating a Nanovibration Intervention for the Prevention/Reversal of Bone Loss Following Spinal Cord Injury.

Osteoporosis disrupts the fine-tuned balance between bone formation and resorption, leading to reductions in bone quantity and quality and ultimately increasing fracture risk. Prevention and treatment of osteoporotic fractures is essential for reductions in mortality, morbidity, and the economic burden, particularly considering the aging global population. Extreme bone loss that mimics time-accelerated osteoporosis develops in the paralyzed limbs following complete spinal cord injury (SCI).

Impact of Beam Shape on Print Accuracy in Digital Light Processing Additive Manufacture.

Photopolymerization-based additive manufacturing requires selectively exposing a feedstock resin to ultraviolet (UV) light, which in digital light processing is achieved either using a digital micromirror device or a digital mask. The minimum tolerances and resolution for a multilayer process are separate for resolution through the Z-axis, looking through the thickness of a printed part, and resolution in the XY-axes, in the plane of the printed layer. The former depends wholly on the rate of attenuation of the incident UV light through the material relative to the mechanical motion of the build layer, while the latter is determined by a two-dimensional pattern of irradiance on the resin formed by the digital micromirror device or the digital mask.

Engineered Surfaces That Promote Capture of Latent Proteins to Facilitate Integrin-Mediated Mechanical Activation of Growth Factors.

Conventional osteogenic platforms utilize active growth factors to repair bone defects that are extensive in size, but they can adversely affect patient health. Here, an unconventional osteogenic platform is reported that functions by promoting capture of inactive osteogenic growth factor molecules to the site of cell growth for subsequent integrin-mediated activation, using a recombinant fragment of latent transforming growth factor beta-binding protein-1 (rLTBP1). It is shown that rLTBP1 binds to the growth-factor- and integrin-binding domains of fibronectin on poly(ethyl acrylate) surfaces, which immobilizes rLTBP1 and promotes the binding of latency associated peptide (LAP), within which inactive transforming growth factor beta 1 (TGF-β1) is bound.

Investigating multi-material hydrogel three-dimensional printing for representation of the neo-vasculature of solid tumours: a comprehensive mechanical analysis and assessment of nitric oxide release from human umbilical vein endothelial cells.

Many solid tumours (e.g. sarcoma, carcinoma and lymphoma) form a disorganized neo-vasculature that initiates uncontrolled vessel formation to support tumour growth.

Review of the applications of principles of insect hearing to microscale acoustic engineering challenges.

When looking for novel, simple, and energy-efficient solutions to engineering problems, nature has proved to be an incredibly valuable source of inspiration. The development of acoustic sensors has been a prolific field for bioinspired solutions. With a diverse array of evolutionary approaches to the problem of hearing at small scales (some widely different to the traditional concept of 'ear'), insects in particular have served as a starting point for several designs.

Spatiotemporal responses of trabecular and cortical bone to complete spinal cord injury in skeletally mature rats.

Objective: Characterise the spatiotemporal responses of trabecular and cortical bone to complete spinal cord injury (SCI) in the skeletally mature rat in the acute (4-week) period following injury.

Methods: The spinal cord of 5-month old male rats was transected at the T9 level. Outcome measures were assessed using micro-computed tomography, three-point bending and serum markers at 1-, 2-, and 4-weeks post-transection.

Non-destructive Analysis of the Mechanical Properties of 3D-Printed Materials.

The determination of the mechanical properties of materials is predominantly undertaken using destructive approaches. Such approaches are based on well-established mathematical formulations where a physical property of the material is measured as a function of an input under controlled conditions provided by some machine, such as load-displacement curves in indentation tests and stress-strain plots in tensile testing. The main disadvantage of these methods is that they involve destruction of samples as they are usually tested to failure to determine the properties of interest.

Additive Manufacture of Small-Scale Metamaterial Structures for Acoustic and Ultrasonic Applications.

Acoustic metamaterials are large-scale materials with small-scale structures. These structures allow for unusual interaction with propagating sound and endow the large-scale material with exceptional acoustic properties not found in normal materials. However, their multi-scale nature means that the manufacture of these materials is not trivial, often requiring micron-scale resolution over centimetre length scales.

Voxel based method for predictive modelling of solidification and stress in digital light processing based additive manufacture.

A method for predicting the solidification and stress of a digital light processing 3D print process is presented, using a voxel-based, multi-layer model to predict the degree of polymerization of the material at every stage during the print. Additive manufacturing offers extremely short development cycles, making predictive modelling of the complex chemical and mechanical interactions of photo-polymerization during part construction unappealing compared to iterative work-flows. Accurate predictions of stress, and the impact of the print parameters and post-print process upon stress, become increasingly important for 3D printing micro-scale electrical and mechanical systems as we design resonators and conductive layers.

Resilin Distribution and Sexual Dimorphism in the Midge Antenna and Their Influence on Frequency Sensitivity.

Small-scale bioacoustic sensors, such as antennae in insects, are often considered, biomechanically, to be not much more than the sum of their basic geometric features. Therefore, little is known about the fine structure and material properties of these sensors-even less so about the degree to which the well-known sexual dimorphism of the insect antenna structure affects those properties. By using confocal laser scanning microscopy (CLSM), we determined material composition patterns and estimated distribution of stiffer and softer materials in the antennae of males and females of the non-biting midge .

Engineered 3D hydrogels with full-length fibronectin that sequester and present growth factors.

Extracellular matrix (ECM)-derived matrices such as Matrigel are used to culture numerous cell types in vitro as they recapitulate ECM properties that support cell growth, organisation, migration and differentiation. These ECM-derived matrices contain various growth factors which make them highly bioactive. However, they suffer lot-to-lot variability, undefined composition and lack of controlled physical properties.

Physiological Basis of Noise-Induced Hearing Loss in a Tympanal Ear.

Acoustic overexposure, such as listening to loud music too often, results in noise-induced hearing loss. The pathologies of this prevalent sensory disorder begin within the ear at synapses of the primary auditory receptors, their postsynaptic partners and their supporting cells. The extent of noise-induced damage, however, is determined by overstimulation of primary auditory receptors, upstream of where the pathologies manifest.

Global and site-specific analysis of bone in a rat model of spinal cord injury-induced osteoporosis.

Micro-Computed Tomography bone analysis is the gold standard method for assessing trabecular and cortical bone microarchitecture in small animal bones. This technique reports morphometric parameters as averages over selected volumes of interest (VOIs). This study proposes the introduction of an additional global 2D morphometric step into the analysis process, that provides a survey of the underlying morphometric variation present throughout both trabecular and cortical bone.

Correction to: Transmission of the frequency components of the vibrational signal of the glassy-winged sharpshooter, Homalodisca vitripennis, within and between grapevines.

Unfortunately, Fig. 3 was incorrectly published in the original publication. The correct version of Fig.

Transmission of the frequency components of the vibrational signal of the glassy-winged sharpshooter, Homalodisca vitripennis, within and between grapevines.

The agricultural pest, Homalodisca vitripennis, relies on vibrational communication through plants for species identification, location, and courtship. Their vibrational signal exhibits a dominant frequency between 80 and 120 Hz, with higher frequency, lower intensity harmonics occurring approximately every 100 Hz. However, previous research revealed that not all harmonics are recorded in every signal.

Porpoise click classifier (PorCC): A high-accuracy classifier to study harbour porpoises (Phocoena phocoena) in the wild.

Harbour porpoises are well-suited for passive acoustic monitoring (PAM) as they produce highly stereotyped narrow-band high-frequency (NBHF) echolocation clicks. PAM systems must be coupled with a classification algorithm to identify the signals of interest. Here, the authors present a harbour porpoise click classifier (PorCC) developed in matlab, which uses the coefficients of two logistic regression models in a decision-making pathway to assign candidate signals to one of three categories: high-quality clicks (HQ), low-quality clicks (LQ), or high-frequency noise.

3D printed microneedle patches using stereolithography (SLA) for intradermal insulin delivery.

3D printed microneedle arrays were fabricated using a biocompatible resin through stereolithography (SLA) for transdermal insulin delivery. Microneedles were built by polymerising consecutive layers of a photopolymeric resin. Thin layers of insulin and sugar alcohol or disaccharide carriers were formed on the needle surface by inkjet printing.

Material stiffness variation in mosquito antennae.

The antennae of mosquitoes are model systems for acoustic sensation, in that they obey general principles for sound detection, using both active feedback mechanisms and passive structural adaptations. However, the biomechanical aspect of the antennal structure is much less understood than the mechano-electrical transduction. Using confocal laser scanning microscopy, we measured the fluorescent properties of the antennae of two species of mosquito- Toxorhynchites brevipalpis and Anopheles arabiensis-and, noting that fluorescence is correlated with material stiffness, we found that the structure of the antenna is not a simple beam of homogeneous material, but is in fact a rather more complex structure with spatially distributed discrete changes in material properties.

Nanoscale Coatings for Ultralow Dose BMP-2-Driven Regeneration of Critical-Sized Bone Defects.

While new biomaterials for regenerative therapies are being reported in the literature, clinical translation is slow. Some existing regenerative approaches rely on high doses of growth factors, such as bone morphogenetic protein-2 (BMP-2) in bone regeneration, which can cause serious side effects. An ultralow-dose growth factor technology is described yielding high bioactivity based on a simple polymer, poly(ethyl acrylate) (PEA), and mechanisms to drive stem cell differentiation and bone regeneration in a critical-sized murine defect model with translation to a clinical veterinary setting are reported.

Insect-inspired acoustic micro-sensors.

Micro-Electro Mechanical System (MEMS) microphones inspired by the remarkable phonotactic capability of Ormia ochracea offer the promise of microscale directional microphones with a greatly reduced need for post-processing of signals. Gravid O. ochracea females can locate their host cricket's 5 kHz mating calls to an accuracy of less than 2° despite having a distance of approximately 500 μm between the ears.

A non-destructive virtual dissection by micro-CT reveals diagnostic characters in the type specimen of Caloptilia stigmatella (Lepidoptera: Gracillariidae).

Nearly a century ago, wing venation was introduced in gracillariid taxonomy as a means to diagnose closely related genera and species groups. Recent advances in non-destructive virtual micro-dissections suggest promising approaches with which to revisit the relevance of wing venation characters on historic primary type specimens. Many unique type specimens in Gracillariidae and other microlepidoptera groups preserved in museum collections are in poor condition, and over the course of history have suffered loss or damage to their abdomens.