Additive manufacture of three dimensional nanocomposite based objects through multiphoton fabrication

Three dimensional structures prepared from a gold-polymer composite formulation have been fabricated using multiphoton lithography. In this process, gold nanoparticles were simultaneously formed through photoreduction whilst polymerisation of two possible monomers was promoted. The monomers, trimethylopropane triacrylate (TMPTA) and pentaerythritol triacrylate (PETA) were mixed with a gold salt, but it was found that the addition of a Ruthenium (II) complex enhanced both the geometrical uniformity and integrity of the polymerized / reduced material, enabling the first production of 3D gold-polymer structures by single step multiphoton lithography

Diarrhea in young children from low-income countries leads to large-scale alterations in intestinal microbiota composition

Acknowledgments This work was funded in part by the William and Melinda Gates Foundation, award 42917 to JPN and OCS; US National Institutes of Health grants 5R01HG005220 to HCB, 5R01HG004885 to MP; US National Science Foundation Graduate Research Fellowship award DGE0750616 to JNP; AWW and JP are funded by The Wellcome Trust (Grant No. WT098051).Peer reviewedPublisher PD

Direct synthesis of multiplexed metal nanowire based devices using carbon nanotubes as vector templates

We present the synthesis of metal nanowires in a multiplexed device configuration using single‐walled carbon nanotubes (SWNTs) as nanoscale vector templates. The SWNT templates control the dimensionality of the wires, allowing precise control of their size, shape and orientation; moreover a solution processable approach enables their linear deposition between specific electrode pairs in electronic devices. Electrical characterizations demonstrate the successful fabrication of metal nanowire electronic devices, while multiscale characterization of the different fabrication steps reveals details of the structure and charge transfer between the material encapsulated and the carbon nanotube. Overall the strategy presented allows facile, low‐cost and direct synthesis of multiplexed metal nanowire devices for nanoelectronic applications

Author Correction: Additive manufacture of complex 3D Au-containing nanocomposites by simultaneous two-photon polymerisation and photoreduction

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper

multifunctional bioinstructive 3d architectures to modulate cellular behavior

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How can frontline expertise and new models of care best contribute to safely reducing avoidable acute admissions? A mixed-methods study of four acute hospitals

BackgroundHospital emergency admissions have risen annually, exacerbating pressures on emergency departments (EDs) and acute medical units. These pressures have an adverse impact on patient experience and potentially lead to suboptimal clinical decision-making. In response, a variety of innovations have been developed, but whether or not these reduce inappropriate admissions or improve patient and clinician experience is largely unknown.AimsTo investigate the interplay of service factors influencing decision-making about emergency admissions, and to understand how the medical assessment process is experienced by patients, carers and practitioners.MethodsThe project used a multiple case study design for a mixed-methods analysis of decision-making about admissions in four acute hospitals. The primary research comprised two parts: value stream mapping to measure time spent by practitioners on key activities in 108 patient pathways, including an embedded study of cost; and an ethnographic study incorporating data from 65 patients, 30 carers and 282 practitioners of different specialties and levels. Additional data were collected through a clinical panel, learning sets, stakeholder workshops, reading groups and review of site data and documentation. We used a realist synthesis approach to integrate findings from all sources.FindingsPatients’ experiences of emergency care were positive and they often did not raise concerns, whereas carers were more vocal. Staff’s focus on patient flow sometimes limited time for basic care, optimal communication and shared decision-making. Practitioners admitted or discharged few patients during the first hour, but decision-making increased rapidly towards the 4-hour target. Overall, patients’ journey times were similar, although waiting before being seen, for tests or after admission decisions, varied considerably. The meaning of what constituted an ‘admission’ varied across sites and sometimes within a site. Medical and social complexity, targets and ‘bed pressure’, patient safety and risk, each influenced admission/discharge decision-making. Each site responded to these pressures with different initiatives designed to expedite appropriate decision-making. New ways of using hospital ‘space’ were identified. Clinical decision units and observation wards allow potentially dischargeable patients with medical and/or social complexity to be ‘off the clock’, allowing time for tests, observation or safe discharge. New teams supported admission avoidance: an acute general practitioner service filtered patients prior to arrival; discharge teams linked with community services; specialist teams for the elderly facilitated outpatient treatment. Senior doctors had a range of roles: evaluating complex patients, advising and training juniors, and overseeing ED activity.ConclusionsThis research shows how hospitals under pressure manage complexity, safety and risk in emergency care by developing ‘ground-up’ initiatives that facilitate timely, appropriate and safe decision-making, and alternative care pathways for lower-risk, ambulatory patients. New teams and ‘off the clock’ spaces contribute to safely reducing avoidable admissions; frontline expertise brings value not only by placing senior experienced practitioners at the front door of EDs, but also by using seniors in advisory roles. Although the principal limitation of this research is its observational design, so that causation cannot be inferred, its strength is hypothesis generation. Further research should test whether or not the service and care innovations identified here can improve patient experience of acute care and safely reduce avoidable admissions.FundingThe National Institute for Health Research (NIHR) Health Services and Delivery Research programme (project number 10/1010/06). This research was supported by the NIHR Collaboration for Leadership in Applied Health Research and Care South West Peninsula

Evolution of carbon nanotubes and their metallurgical reactions in Al-based composites in response to laser irradiation during selective laser melting

Aluminium-based composites reinforced with carbon nanotubes are widely sought for their outstanding metallurgical and structural properties that largely depend on the manufacturing route. In this work, the process-structure-property relationship for a composite made from high-energy-ball-milled pure Al and multi-walled carbon nanotubes (MWCNT) processed by laser powder-bed-fusion additive manufacturing was investigated. The response of MWCNT to laser irradiation and their interfacial reactions with Al were probed in a holistic investigation. X-ray diffraction confirmed the partial transformation of C into Al-carbides in addition to the presence of some nano-crystalline graphitic materials. Microscopy revealed evidence of carbides segregation at the melt pool boundaries as well as migration along the build direction. Raman spectroscopy showed that laser irradiation promoted re-graphitisation in MWCNT, reducing the amount of defects introduced by milling. Two types of Al4C3 formed as a result of the metallurgical reaction between Al and MWCNT. These were needle-like and hexagonal Al4C3 and their mechanisms of formation, direct precipitation and dissolution-precipitation, respectively, were explained in light of the thermal profile experienced by the material during melting and solidification. Large scale electron backscatter diffraction showed that there is no distinctive texture developing during melting and solidification. Micro- and nano-indentation testing showed uniform mechanical properties

Citrobacter rodentium is an unstable pathogen showing evidence of significant genomic flux.

Citrobacter rodentium is a natural mouse pathogen that causes attaching and effacing (A/E) lesions. It shares a common virulence strategy with the clinically significant human A/E pathogens enteropathogenic E. coli (EPEC) and enterohaemorrhagic E. coli (EHEC) and is widely used to model this route of pathogenesis. We previously reported the complete genome sequence of C. rodentium ICC168, where we found that the genome displayed many characteristics of a newly evolved pathogen. In this study, through PFGE, sequencing of isolates showing variation, whole genome transcriptome analysis and examination of the mobile genetic elements, we found that, consistent with our previous hypothesis, the genome of C. rodentium is unstable as a result of repeat-mediated, large-scale genome recombination and because of active transposition of mobile genetic elements such as the prophages. We sequenced an additional C. rodentium strain, EX-33, to reveal that the reference strain ICC168 is representative of the species and that most of the inactivating mutations were common to both isolates and likely to have occurred early on in the evolution of this pathogen. We draw parallels with the evolution of other bacterial pathogens and conclude that C. rodentium is a recently evolved pathogen that may have emerged alongside the development of inbred mice as a model for human disease

The influence of printing parameters on multi-material two-photon polymerisation based micro additive manufacturing

Two-photon polymerisation (2PP) based additive manufacturing has emerged as a powerful technology to fabricate complex three-dimensional micro- and nanoscale architectures. However, a comprehensive understanding of the effect of printing parameters on the functional properties of these structures is needed to unleash the potential of 2PP and enable controlled deposition / integration of various materials into multi-material structures. In this study we investigate the correlation between printing parameters, resin composition and the final properties of 2PP structures fabricated with different monomers and initiators. The link between 2PP process and final material properties is validated by morphological studies, vibrational spectroscopy and advanced mass spectrometry, ToF-SIMS, imaging. We establish empirical relationships between printing parameters and mechanical properties, and achieve controlled deposition of different monomers with high precision and uniform composition. The approaches developed here are successfully used to demonstrate multi-material 2PP and produce complex 3D architectures incorporating three polymers. The 2PP structures produced can be transferred into solution or onto different substrates, in addition to direct fabrication on flexible substrates. This work advances the understanding of the 2PP process, which enable rational design and manufacture of complex geometries and additive manufacturing of nanoscale multi-material structures