Portable X-ray fluorescence (pXRF) calibration for analysis of nutrient concentrations and trace element contaminants in fertilisers

With the increasing popularity of local blending of fertilisers, the fertiliser industry faces issues regarding quality control and fertiliser adulteration. Another problem is the contamination of fertilisers with trace elements that have been shown to subsequently accumulate in the soil and be taken up by plants, posing a danger to the environment and human health. Conventional characterisation methods necessary to ensure the quality of fertilisers and to comply with local regulations are costly, time consuming and sometimes not even accessible. Alternatively, using a wide range of unamended and intentionally amended fertilisers this study developed empirical calibrations for a portable handheld X-ray fluorescence (pXRF) spectrometer, determined the reliability for estimating the macro and micro nutrients and evaluated the use of the pXRF for the high-throughput detection of trace element contaminants in fertilisers. The models developed using pXRF for Mg, P, S, K, Ca, Mn, Fe, Zn and Mo had R2 values greater or equal to 0.97. These models also performed well on validation, with R2 values greater or equal to 0.97 (except for Fe, R2val = 0.55) and slope values ranging from 0.81 to 1.44. A second set of models were developed with a focus on trace elements in amended fertilisers. The R2 values of calibration for Co, Ni, As, Se, Cd and Pb were greater than or equal to 0.80. At concentrations up to 1000 mg kg-1, good validation statistics were also obtained; R2 values ranged from 0.97–0.99, except in one instance. The regression coefficients of the validation also had good prediction in the range of 0–100 mg kg-1 (R2 values were from 0.78–0.99), but not as well at lower concentrations up to 20 mg kg-1 (R2 values ranged from 0.10–0.99), especially for Cd. This study has demonstrated that pXRF can measure several major (P, Ca) and micro (Mn, Fe, Cu) nutrients, as well as trace elements and potential contaminants (Cr, Ni, As) in fertilisers with high accuracy and precision. The results obtained in this study is good, especially considering that loose powders were scanned for a maximum of 90 seconds without the use of a vacuum pump.

Considerations of the limitations of commonly applied characterisation methods in understanding protein-driven irreversible fouling

FEEM and LC-OCD characterisation supplemented with an understanding of protein morphology, hydrophobicity and charge lends insights into protein fouling behaviour.

Metallurgical Modelling of Ti-6Al-4V for Welding Applications

Manufacturing processes such as welding subject the α/β titanium alloy Ti-6Al-4V to a wide range of temperatures and temperature rates, generating microstructure variations in the phases and in the precipitate dimensions. In this study, the metallurgical and numerical modelling of Ti-6Al-4V when subjected to a high energy density welding process was affected by a series of analytical equations coded in Sysweld commercial specialist FE welding software. Numerical predictions were compared with experimental results from laser welding tests on plates with different thicknesses, initial microstructural morphologies, and operating conditions. The evolution of the microstructure was described by using a diffusion-based approach when the material was operating in the α + β field, whilst empirical equations were used for temperatures above the β-transus temperature. Predictions made by the subroutines within the FE model were shown to match with reasonable trends when validated using experimental characterisation methods for various metallurgical features, including the α particle size, β grain size, martensitic needle thickness, and relative phase volume fractions.

Dynamic High-density Functional Substrate Mapping Improves Outcomes in Ischaemic Ventricular Tachycardia Ablation: Sense Protocol Functional Substrate Mapping and Other Functional Mapping Techniques

Post-infarct-related ventricular tachycardia (VT) occurs due to reentry over surviving fibres within ventricular scar tissue. The mapping and ablation of patients in VT remains a challenge when VT is poorly tolerated and in cases in which VT is non-sustained or not inducible. Conventional substrate mapping techniques are limited by the ambiguity of substrate characterisation methods and the variety of mapping tools, which may record signals differently based on their bipolar spacing and electrode size. Real world data suggest that outcomes from VT ablation remain poor in terms of freedom from recurrent therapy using conventional techniques. Functional substrate mapping techniques, such as single extrastimulus protocol mapping, identify regions of unmasked delayed potentials, which, by nature of their dynamic and functional components, may play a critical role in sustaining VT. These methods may improve substrate mapping of VT, potentially making ablation safer and more reproducible, and thereby improving the outcomes. Further large-scale studies are needed.

Material characterisation methods for a tumbling self-piercing riveting process

The growing demands of resource-saving processes and products are leading to increasing importance of lightweight construction for the automotive industry. One approach is multi-material design, which uses high-strength steels and aluminium alloys in the production of vehicle bodies. Therefore, reliable processes for joining components with different mechanical properties and geometries are necessary. As conventional joining processes reach their limits, new versatile processes and methods are required which can adapt to different process conditions and disturbance variables. A widely used joining process to join different materials is self-piercing riveting as a joining by forming method, however it is characterised as inflexible to changing process conditions due to a linear process kinematic and rigid dies. An approach to extend the process limits is the application of a tumbling kinematic for the punch. Thus, an adapted tumbling strategy can be used to influence the joining process and to achieve a controlled material flow in order to manufacture tailored joints. For the fundamental investigation of the process, numerical investigations are necessary. In order to achieve high model quality a precise material modelling is crucial. Therefore, a characterisation of the materials HCT590X+Z and EN AW-6014 as typical materials of multi-material mixes and the rivet material 38B2 is performed. Due to the different stress conditions during tumbling self-piercing riveting suitable characterisation methods are selected and carried out.

GAKTpore: Stereological Characterisation Methods for Porous Foams in Biomedical Applications

In tissue engineering, scaffolds are a key component that possess a highly elaborate pore structure. Careful characterisation of such porous structures enables the prediction of a variety of large-scale biological responses. In this work, a rapid, efficient, and accurate methodology for 2D bulk porous structure analysis is proposed. The algorithm, “GAKTpore”, creates a morphology map allowing quantification and visualisation of spatial feature variation. The software achieves 99.6% and 99.1% mean accuracy for pore diameter and shape factor identification, respectively. There are two main algorithm novelties within this work: (1) feature-dependant homogeneity map; (2) a new waviness function providing insights into the convexity/concavity of pores, important for understanding the influence on cell adhesion and proliferation. The algorithm is applied to foam structures, providing a full characterisation of a 10 mm diameter SEM micrograph (14,784 × 14,915 px) with 190,249 pores in ~9 min and has elucidated new insights into collagen scaffold formation by relating microstructural formation to the bulk formation environment. This novel porosity characterisation algorithm demonstrates its versatility, where accuracy, repeatability, and time are paramount. Thus, GAKTpore offers enormous potential to optimise and enhance scaffolds within tissue engineering.

Production and characterisation of adsorbents synthesised by hydrothermal carbonisation of biomass wastes

Surface structure and chemical properties of adsorbents are important factors required to understand the mechanism of adsorption. The purpose of this study was to produce hydrochars from biomass using hydrothermal carbonisation (HTC) and to analyse their sorption capacities. The biomass used in this study were coco-peat (CP), coconut shell (CS), eggshell (ES), rice husk (RH) and lemon peel (LP). The operating conditions for HTC were 200 °C and 20 h residence time. The characterisation methods consisted of Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Fourier Transform Infrared Ray (FTIR) Spectroscopy, and Brunauer, Emmett and Teller (BET). The results showed that HTC improved the sorption capacities of the biomass wastes. It was found that hydrochars were crispy and flaky with more micro- and meso-porous structures, indicating that lignin and other components were denatured due to carbonisation. This led to the creation of more active sites for sorption and pollutant binding. The hydrochars showed a percentage increase in carbon content and a decrease in oxygen content with traces of other elements, compared to their corresponding raw biomass. The major functional groups identified were –OH and –COOH. The surface area of the hydrochars which include CP (2.14 m2/g), CS (14.04 m2/g), ES (0.50 m2/g), RH (15.74 m2/g), and LP (6.89 m2/g) were significantly improved compared with those of the raw biomass. The study showed that the hydrochars produced from the biomass wastes have the potential to be used as adsorbents.

Novel hybrid method to additively manufacture denser graphite structures using Binder Jetting

This study introduces two hybrid processes integrating an additive manufacturing technique with post-processing treatments namely (i) Binder Jetting Printing (BJP) + Cold Isostatic Pressing (CIP) + cycle and (ii) BJP + cycle where cycle refers to a sequence of Impregnation—Drying—Pyrolysis. These two new processes yielded additively manufactured parts with higher density and reduced defects/porosities. As a testbed, we used these new processes to fabricate graphite structures. The samples produced by both methods were compared with each other and benchmarked to the samples produced by (a) BJP alone and (b) Traditional uniaxial pressing like compaction moulding. Various characterisation methods were used to investigate the microstructure and mechanical properties which showed that the porosity of hybrid manufactured samples reduces from 55% to a record 7%. This technological pathway is expected to create a new avalanche of industrial applications that are hitherto unexplored in the arena of hybrid additive manufacturing with BJP method.

Molecular basis for protein–protein interactions

This minireview provides an overview on the current knowledge of protein–protein interactions, common characterisation methods to characterise them, and their role in protein complex formation with some examples. A deep understanding of protein–protein interactions and their molecular interactions is important for a number of applications, including drug design. Protein–protein interactions and their discovery are thus an interesting avenue for understanding how protein complexes, which make up the majority of proteins, work.