2,508 research outputs found
3D surface topography and reflectivity of anisotropic etched silicon micromirrors for BioMEMS
Fabrication and mechanical properties of chitosan composite membrane containing hydroxyapatite particles
Fabrication and Mechanical Properties of Chitosan-Montmorillonite Nano-composite
Chitosan has found various applications in gastrointestinal stent, biomedical implants as well as an effective absorbent in waste water treatment. However, the material suffers from low strength and large shrinkage upon dehydration. The current project is aimed to develop a process to fabricate chitosan composites with the addition of functionalised montmorillonite nanoparticles and to examine the effect of ceramic content on the mechanical behavior of the composites. This paper describes the fabrication of chitosan with montmorrillonite composites and the mechanical testing of the samples and the mechanical behaviour of the composites, as well as the observations of the microstructure. The effects of composition and microstructure on the mechanical properties of the composite are investigated. The results indicate that the nanoparticles are dispersed uniformly in the matrix up to 40wt% using high speed homogeniser. The elastic modulus increases monotonically with the addition of nanoparticles, but the fracture strength drops due to the defects introduced by the nanoparticles.</jats:p
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Fibroblastic tissue growth on polymeric electrospun membranes: a feasibility study
Data availability: Data sets generated during the current study are available from the corresponding author on reasonable request.In recent years the interest in synthetic scaffolds has increased significantly as an alternative to animal-derived materials, as well as the advancement of material and manufacturing engineering, has resulted in improved standardisation and reproducibility within the field. Despite these advancements, a significant amount of research on animal-derived scaffolds, whilst research on synthetic materials is lacking for the growth of non-tumourgenic breast cell lines. The main objective of this work is to manufacture biodegradable scaffolds using biocompatible materials such as PVA (Polyvinyl Alcohol), PU (Polyurethane), Ge (Gelatin) and PCL (Poly-(-caprolactone) to test human cell adhesion and investigate the optimal system that supports representative tissue organisation and that could be used as an alternative to Matrigelâą. Here, human mammary fibroblasts (HMF) were used as proof of concept. The membranes were manufactured using the process of electrospinning and characterised by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (ATR-FTIR), contact angle, tensile strength, and degradation studies. The assessment of the membranes as a viable biomaterial for the growth and development of cells was studied by MTT proliferation assay, fluorescence microscopy and SEM imaging. Results demonstrate that all materials are suitable for HMF proliferation. However, from microscopy analysis, only PU and PVA membranes induced morphological organisation of HMF similar to those results obtained in the Matrigelâą control conditions. This feasibility study reveals that HMF organisation, and proliferation are affected by the properties of the scaffold. Consequently, scaffolds parameters should be adjusted and manipulated to impact cell behaviour and emulate in vivo conditions.Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Programme Studentship and a research grant from Breast Cancer UK (BCUK)
A Descriptive Morphology of the Ant Genus Procryptocerus (Hymenoptera: Formicidae)
Morphology is the most direct approach biologists have to recognize uniqueness of insect species as compared to close relatives. Ants of the genus Procryptocerus possess important morphologic characters yet have not been explored for use in a taxonomic revision. The genus is characterized by the protrusion of the clypeus forming a broad nasus and antennal scrobes over the eyes. The toruli are located right posterior to the flanks of the nasus opposite to each other. The vertex is deflexed posteriorly in most species. An in-group comparison of the external morphology is presented focusing on the workers. A general morphology for gynes and males is also presented. Previously mentioned characters as well as new ones are presented, and their character states in different species are clarified. For the metasoma a new system of ant metasomal somite nomenclature is presented that is applicable to Aculeata in general. Finally, a Glossary of morphological terms is offered for the genus (available online). Most of the terminology can be used in other members of the Formicidae and Aculeata
Restorative Justice Cases in Scotland:Factors Related to Participation, the Restorative Process, Agreement Rates and Forms of Reparation
RPA using a multiplexed cartridge for low cost point of care diagnostics in the field
A point of care device utilising Lab-on-a-Chip technologies that is applicable for biological pathogens was designed, fabricated and tested showing sample in to answer out capabilities. The purpose of the design was to develop a cartridge with the capability to perform nucleic acid extraction and purification from a sample using a chitosan membrane at an acidic pH. Waste was stored within the cartridge with the use of sodium polyacrylate to solidify or gelate the sample in a single chamber. Nucleic acid elution was conducted using the RPA amplification reagents (alkaline pH). Passive valves were used to regulate the fluid flow and a multiplexer was designed to distribute the fluid into six microchambers for amplification reactions. Cartridges were produced using soft lithography of silicone from 3D printed moulds, bonded to glass substrates. The isothermal technique, RPA is employed for amplification. This paper shows the results from two separate experiments: the first using the RPA control nucleic acid, the second showing successful amplification from Chlamydia Trachomatis.
Endpoint analysis conducted for the RPA analysis was gel electrophoresis that showed 143 base pair DNA was amplified successfully for positive samples whilst negative samples did not show amplification. End point analysis for Chlamydia Trachomatis samples was fluorescence detection that showed successful detection of 1 copy/ÎŒL and 10 copies/ÎŒL spiked in a MES buffer.Medical Research Counci
New Symmetries in Crystals and Handed Structures
For over a century, the structure of materials has been described by a
combination of rotations, rotation-inversions and translational symmetries. By
recognizing the reversal of static structural rotations between clockwise and
counterclockwise directions as a distinct symmetry operation, here we show that
there are many more structural symmetries than are currently recognized in
right- or left-handed handed helices, spirals, and in antidistorted structures
composed equally of rotations of both handedness. For example, though a helix
or spiral cannot possess conventional mirror or inversion symmetries, they can
possess them in combination with the rotation reversal symmetry. Similarly, we
show that many antidistorted perovskites possess twice the number of symmetry
elements as conventionally identified. These new symmetries predict new forms
for "roto" properties that relate to static rotations, such as rotoelectricity,
piezorotation, and rotomagnetism. They also enable symmetry-based search for
new phenomena, such as multiferroicity involving a coupling of spins, electric
polarization and static rotations. This work is relevant to structure-property
relationships in all material structures with static rotations such as
minerals, polymers, proteins, and engineered structures.Comment: 15 Pages, 4 figures, 3 Tables; Fig. 2b has error
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