An experimental and analytical investigation of reinforced concrete beam-column joints strengthened with a range of CFRP schemes applied only to the beam

This paper investigates the experimental and analytical behaviour of beam-column joints that are subjected to a combination of torque, flexural and direct shear forces, where different Carbon Fibre Polymer (CFRP) strengthening wraps have been applied only to the beam. These wrapping schemes have previously been determined by the research community as an effective method of enhancing the torsional capacities of simply supported reinforced concrete beams. In this investigation, four 3/4-scale exterior beam-column joints were subjected to combined monotonic loading; three different beam wrapping schemes were employed to strengthen the beam region of the joint. The paper suggests a series of rational formulae, based on the space truss mechanism, which can be used to evaluate the joint shear demand of the beams wrapped in these various ways. Further, an iterative model, based on the average stress-strain method, has been introduced to predict joint strength. The proposed analytical approaches show good agreement with the experimental results. The experimental outcomes along with the adopted analytical methods reflect the consistent influence of the wrapping ratio, the interaction between the combined forces, the concrete strut capacity and the fibre orientation on the joint forces, the failure mode and the distortion levels. A large rise in the strut force resulting from shear stresses generated from this combination of forces is demonstrated and leads to a sudden-brittle failure. Likewise, increases in the beams’ main steel rebar strains are identified at the column face, again influenced by the load interactions and the wrapping systems used

Formulation, stabilisation and encapsulation of bacteriophage for phage therapy

Against a backdrop of global antibiotic resistance and increasing awareness of the importance of the human microbiota, there has been resurgent interest in the potential use of bacteriophages for therapeutic purposes, known as phage therapy. A number of phage therapy phase I and II clinical trials have concluded, and shown phages don’t present significant adverse safety concerns. These clinical trials used simple phage suspensions without any formulation and phage stability was of secondary concern. Phages have a limited stability in solution, and undergo a significant drop in phage titre during processing and storage which is unacceptable if phages are to become regulated pharmaceuticals, where stable dosage and well defined pharmacokinetics and pharmacodynamics are de rigueur. Animal studies have shown that the efficacy of phage therapy outcomes depend on the phage concentration (i.e. the dose) delivered at the site of infection, and their ability to target and kill bacteria, arresting bacterial growth and clearing the infection. In addition, in vitro and animal studies have shown the importance of using phage cocktails rather than single phage preparations to achieve better therapy outcomes. The in vivo reduction of phage concentration due to interactions with host antibodies or other clearance mechanisms may necessitate repeated dosing of phages, or sustained release approaches. Modelling of phage-bacterium population dynamics reinforces these points. Surprisingly little attention has been devoted to the effect of formulation on phage therapy outcomes, given the need for phage cocktails, where each phage within a cocktail may require significantly different formulation to retain a high enough infective dose. This review firstly looks at the clinical needs and challenges (informed through a review of key animal studies evaluating phage therapy) associated with treatment of acute and chronic infections and the drivers for phage encapsulation. An important driver for formulation and encapsulation is shelf life and storage of phage to ensure reproducible dosages. Other drivers include formulation of phage for encapsulation in micro- and nanoparticles for effective delivery, encapsulation in stimuli responsive systems for triggered controlled or sustained release at the targeted site of infection. Encapsulation of phage (e.g. in liposomes) may also be used to increase the circulation time of phage for treating systemic infections, for prophylactic treatment or to treat intracellular infections. We then proceed to document approaches used in the published literature on the formulation and stabilisation of phage for storage and encapsulation of bacteriophage in micro- and nanostructured materials using freeze drying (lyophilization), spray drying, in emulsions e.g. ointments, polymeric microparticles, nanoparticles and liposomes. As phage therapy moves forward towards Phase III clinical trials, the review concludes by looking at promising new approaches for micro- and nanoencapsulation of phages and how these may address gaps in the field

Dielectric and conductivity relaxation in dry and humid solid PEO electrolytes

The interaction of water with uncomplexed poly(ethylene oxide) (PEO) is studied by dielectric relaxation spectroscopy techniques for water contents up to about 0.60(w/w). The techniques used include thermally stimulated depolarization currents, thermally stimulated polarization currents and dc conductivity measurements in the temperature range 77-300 K, as well as broadband ac techniques in the frequency range 10-1010 Hz. The results are discussed in terms of molecular distribution and organization of water in a separate phase, restriction of the molecular mobility of water molecules, dipolar and space charge contributions to the main (α) relaxation and plasticizing action of water. © 1994

Complete Genome Sequence of the Novel Escherichia coli Phage phAPEC8

Bacteriophage phAPEC8 is an Escherichia coli-infecting myovirus, isolated on an avian pathogenic Escherichia coli (APEC) strain. APEC strains cause colibacillosis in poultry, resulting in high mortality levels and important economic losses. Genomic analysis of the 147,737-bp double-stranded DNA phAPEC8 genome revealed that 53% of the 269 encoded proteins are unique to this phage. Its closest relatives include the Salmonella phage PVP-SE1 and the coliphage rv5, with 19% and 18% similar proteins, respectively. As such, phAPEC8 represents a novel, phylogenetically distinct clade within the Myoviridae, with molecular properties suitable for phage therapy applications.status: publishe

A simplified shear model for reinforced concrete elements subjected to reverse lateral loadings

The response of reinforced concrete elements to earthquake loads can be controlled by bending or shear behaviour, depending on the geometrical characteristics of the elements and on the reinforcement detailing. To represent the shear behaviour, in elements where shear is not negligible, it was developed and implemented in the VisualANL a non-linear shear model. Finally, in this paper are presented and discussed the results of a set of numerical calibration analyses based on tests on full-scale frames

Bismuth oxyhalide based photo-enhanced triboelectric nanogenerators

Utilizing wide absorption characteristics of a narrow bandgap (~1.8 eV) semiconductor, we report on Bismuth Oxyiodide (BiOI) based photo-enhanced triboelectric nanogenerator (TENG). The potentiostatic deposition of tribo-positive BiOI on transparent, electrically conducting Fluorine doped Indium Tin Oxide (FTO) substrates provides a pathway to exploit concurrently the photo-enhanced charge generation and triboelectric effects. When utilized against tribo-negative polydimethylsiloxane (PDMS) films, under illumination, the BiOI/PDMS TENGs’ output was significantly enhanced, wherein an increase of 21% in output voltage, 38% in charge density (26% in short-circuit current density), and 74% in overall power density (from 0.25 Wm−2 (in dark) and 0.44 Wm−2 (under illumination)), respectively, was observed. Correspondingly, a dramatic enhancement (from ~25 mV to ~300 mV) in the average surface potential, termed as surface photovoltage (SPV), for the illuminated BiOI was observed by Kelvin Probe Force Microscopy (KPFM). For an isolated, grounded BiOI/FTO electrode, this enhanced SPV was slow-decaying (~3.5 h) and is attributed to the high dielectric constant, presence of deep surface states and traps within BiOI, and slow charge-exchange with the ambient environment. The work thus not only provides an approach for the enhancement of mechanical-to-electrical efficiency of TENGs by light absorption but can also be utilized for self-powered detection of electromagnetic radiation and photodetectors. © 2021 Elsevier Lt

Replacing the metal electrodes in triboelectric nanogenerators: High-performance laser-induced graphene electrodes

While significant work is being carried out to develop materials for enabling high surface charge density triboelectric nanogenerators (TENG), little attention has been paid to the role of electrodes responsible for charge collection. This work reports on the facile synthesis and use of high crystallinity, sp2-hybridised laser-induced graphene (LIG) as a high-efficiency electrode for triboelectric nanogenerators (TENGs). Using a conventional 10.6 μm CO2 laser, the controlled, direct photothermal conversion of dielectric, tribo-negative polyimide (PI) and tribo-positive cellulosic paper into corresponding PI-LIG and paper-LIG, respectively, facilitates a significantly higher electrical output as compared to the commonly utilised adhesive aluminium electrodes. The LIG based paper-PI TENGs showed significantly higher electrical output characteristics with a peak-to-peak voltage of up to ~625 V, a current density of ~20 mA m−2 and a transferred charge density of ~138 μC m−2 with a maximum power output of ~2.25 W m−2, respectively, while the corresponding values for the conventional Al-tape electrode-based paper-PI TENGs were 400 Vp-p, ~10 mA m−2, ~85 μC m−2 and 0.9 W m−2, respectively. The mechanically robust LIG electrodes show excellent stability with less than 5.0% variation in output over 12,000 contact cycles. Using Kelvin probe force microscopy (KPFM) measurements, we have measured differences in not only the average surface potentials of the triboelectric surfaces (−0.26 V for pristine PI vs. +0.34 V for paper, which drive the TENG electrical output) but also for the LIG's synthesised from them (−0.08 V for PI-LIG vs. +0.26 V for paper-LIG), suggestive of the role of initial surface chemistry in the formation of LIGs. The enhanced (~150%) power density for LIG based TENGs is ascribed to the lowering of the charge transfer barrier height via the alignment of Fermi levels resulting in higher surface charge on the dielectric surface and the significantly (~6 orders) lower interfacial contact impedance of LIG as compared to adhesive aluminium electrodes. Thus, via the removal of the additional interface between the triboelectric surface and electrode, high-performance metal-free TENGs with excellent prospects for enabling energy harvesting applications can be realised. © 2020 Elsevier Lt

Expanding the portfolio of tribo-positive materials: Aniline formaldehyde condensates for high charge density triboelectric nanogenerators

The rapid uptake of energy harvesting triboelectric nanogenerators (TENGs) for self-powered electronics requires the development of high-performance tribo-materials capable of providing large power outputs. This work reports on the synthesis and use of aniline formaldehyde resin (AFR) for energy-harvesting applications. The facile, acidic-medium reaction between aniline and formaldehyde produces the aniline-formaldehyde condensate, which upon an in-vacuo high temperature curing step provides smooth AFR films with abundant nitrogen and oxygen surface functional groups which can acquire a tribo-positive charge and thus endow AFR with a significantly higher positive tribo-polarity than the existing state-of-art polyamide-6 (PA6). A TENG comprising of optimized thin-layered AFR against a polytetrafluoroethylene (PTFE) film produced a peak-to-peak voltage of up to ~1000 V, a current density of ~65 mA m−2, a transferred charge density of ~200 μC m−2 and an instantaneous power output (energy pulse) of ~11 W m−2 (28.1 μJ cycle−1), respectively. The suitability of AFR was further supported through the Kelvin probe force microscopy (KPFM) measurements, which reveal a significantly higher average surface potential value of 1.147 V for AFR as compared to 0.87 V for PA6 and a step-by-step increase of the surface potential with the increase of energy generation cycles. The work not only proposes a novel and scalable mouldable AFR synthesis process but also expands with excellent prospects, the current portfolio of tribo-positive materials for triboelectric energy harvesting applications. © 2019 Elsevier Lt