A review of the mallet impact test for small scale explosive formulations

Presented at 19th Seminar on New Trends of Energetic Materials (NTREM 2016); 20-22/04/2016, Pardubice Czech RepublicDevelopment of new explosive formulations begins with the generation of only a few milligrams of material which is investigated using a number of small scale tests such as DSC, TGA, response to flame, mallet impact (mallet friction either glancing or direct blow) to determine whether the formulation is safe to scale up to 10 g. The latter of these tests, mallet impact, can be particularly subjective as the result is directly influenced by the operator carrying out the assessment. Not only can there be a change from one operator to another but there can also be a change in the force applied during each strike potentially leading to inconsistent results. This study highlights this encountered variation and assesses the load applied by a variety of operators with varying levels of explosive experience. This paper also proposes the use of a small scale laboratory based impact test which would provide improved confidence in the assessment of impact sensitiveness of explosive formulations and assist in justifying whether a formulation can be taken to the next scale. A small scale version of the BAM impact test (EMTAP Test 43) has been devised that allows the comparison of the sensitiveness of small scale formulations relative to RDX (8.7 J, EMTAP Test 43B) whilst also ensuring a reproducible result

Solution composition and particle size effects on the dissolution and solubility of a ThO2 microstructural analogue for UO2 matrix of nuclear fuel

The objective of this study was to investigate the dissolution rate of ThO2 which was synthesised to approximate, as closely as possible, the microstructure of UO2 in a nuclear fuel matrix. The optimal sintering temperature for ThO2 pellets was found to be 1750 ℃, which produced pellets with a microstructure similar to UO2 nuclear fuel pellets, with randomly oriented grains ranging in size from 10 to 30 μm. Dissolution was conducted using ThO2 particles of different size fractions (80 to 160 μm and 2 to 4 mm) in the presence and absence of carbonate, in solutions with pH from 2 to 8 and at 80 ℃. Dissolution rates were calculated from Th released from the solid phase to solution. Particles of ThO2 were also leached with 1 M HNO3 at 80 ℃ in order to investigate the morphological changes at the particle surfaces. The concentration of Th was found to be ≥ 10–9 mol/L at pH ≤ 4, lower than the theoretical solubility of crystalline ThO2. At higher pH values, from 4 to 8, the measured concentrations (10−10 to 10–12 mol/L) were between the theoretical solubility of ThO2 and Th(OH)4. Grain boundaries were shown to exert an influence on the dissolution of ThO2 particles. Using high resolution aqueous solution analysis, these data presented here extend the current understanding of Th solubility in solutio

Evolution of phase assemblage of blended magnesium potassium phosphate cement binders at 200 degrees and 1000 degrees C

The fire performance of magnesium potassium phosphate cement (MKPC) binders blended with fly ash (FA) and ground granulated blast furnace slag (GBFS) was investigated up to 1000°C using X-ray diffraction, thermogravimetric analysis and SEM techniques. The FA/MKPC and GBFS/MKPC binders dehydrate above 200°C to form amorphous KMgPO4, concurrent with volumetric and mass changes. Above 1000°C, additional crystalline phases were formed and microstructural changes occurred, although no cracking or spalling of the samples was observed. These results indicate that FA/MKPC and GBFS/MKPC binders are expected to have satisfactory fire performance under the fire scenario conditions relevant to the operation of a UK or other geological disposal facility

Krypton irradiation damage in Nd-doped zirconolite and perovskite as potential ceramics for inert matrix fuel and plutonium disposition

ABSTRACT Understanding the effect of radiation damage and noble gas accommodation in potential ceramic hosts for plutonium disposition is necessary to evaluate the long-term behaviour during geological disposal. Polycrystalline samples of Nd-doped zirconolite and Nd-doped perovskite were irradiated ex-situ with 2 MeV Kr + at a dose of 5x10 15 ions.cm -2 to simulate plutonium nuclei recoil during alpha decay. The feasibility of thin section preparation of both pristine and irradiated samples by Focussed Ion Beam sectioning was demonstrated. After irradiation, the Nd-doped zirconolite revealed a well defined amorphous region separated from the pristine material by a thin (40-60 nm) damaged interface. The Nd-doped perovskite contained a defined irradiated region composed of an amorphous region surrounded by damaged regions. In both samples, as revealed by electron diffraction, the damaged regions and interface have a structure in which the fluorite sublattice is present while the pristine lattice is absent. In addition in Nddoped perovskite, the amorphisation dose depended on crystallographic orientation and possibly sample configuration (thin section and bulk). In Nd-doped perovskite, Electron Energy Loss Spectroscopy study revealed a change in Ti coordination associated with the crystal to amorphous transition

Use of AUDIT-C alcohol screening tool in NHS general dental practices in North London

Background: The numerous health risks of excessive alcohol consumption are well documented. Individuals at risk of harm from alcohol consumption can be identified through alcohol screening tools; however, there is limited research regarding their use in general dental practices. Methods: Data were collected as part of a feasibility trial evaluating delivery of brief alcohol advice in general dental practices in North London. Patient demographics and health-related behaviours were collected, and the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) tool was used to assess alcohol consumption patterns. Results: The analytical sample comprised 552 dental patients, of whom approximately half (46%) were drinking alcohol at hazardous levels. Males, younger adults, those who consumed red meat weekly and smokers all had significantly increased risks of excessive alcohol consumption. Smokers were more likely to consume excessive levels of alcohol irrespective of smoking frequency. Notable sex differences in alcohol consumption were identified, with males being more likely to consume alcohol frequently and in larger quantities than females. Conclusion: The AUDIT-C tool can be used in general dental practice to screen for harmful levels of alcohol consumption. Clear associations exist between patient demographics, health behaviours and excessive alcohol consumption

Patterns and Correlates of Sedentary Behaviour among people with Multiple Sclerosis: A Cross-Sectional Study

© The Author(s) 2021. Background High levels of sedentary behaviour are associated with poor health outcomes in people with multiple sclerosis (MS). Identifying modifiable correlates of sedentary behaviour for people with MS is essential to design effective intervention strategies to minimise sedentary time. Objective: To quantify patterns and identify correlates of sedentary behaviour among adults with MS. Methods: Fatigue, self-efficacy, walking capability, the physical and psychological impact of MS, health-related quality of life, and participation and autonomy were assessed by questionnaire. Participants wore an activPAL monitor. Total (min/day), prolonged bouts (≥30 minutes) and breaks in sedentary time were calculated. Associations were examined using regression analysis adjusted for demographic and clinical confounders. Results: Fifty-six adults with MS participated (mean±SD age: 57.0±9.25 years; 66% female). Self-efficacy for control over MS was associated with sedentary time (β =0.16, 95% CI 0.01, 0.30). Self-efficacy in function maintenance (β =0.02, 95% CI 0.00, 0.04), health-related quality of life (EuroQol-5D) (β =31.60, 95% CI 7.25, 55.96), and the autonomy indoors subscale of the Impact on Participation and Autonomy Questionnaire (β =-5.11, 95% CI -9.74, -0.485) were associated with breaks in sedentary time. Conclusion Future studies should consider self-efficacy, health-related quality of life and participation and autonomy as potential components of interventions to reduce sedentary behaviour.MS Society UK (grant number 53)

Changing physical activity behaviour for people with multiple sclerosis: protocol of a randomised controlled feasibility trial (iStep-MS)

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. Introduction: Although physical activity may reduce disease burden, fatigue and disability, and improve quality of life among people with multiple sclerosis (MS) many people with MS are physically inactive and spend significant time in sedentary behaviour. Behaviour-change interventions may assist people with MS to increase physical activity and reduce sedentary behaviour. However, few studies have investigated their effectiveness using objective measures of physical activity, particularly in the long-term. Further, interventions that have proven effective in the short-term may not be feasible in clinical practice because of the large amount of support provided. The iStep-MS trial aims to determine the safety, feasibility and acceptability of a behaviour-change intervention to increase physical activity and reduce sedentary behaviour among people with MS. Methods and analysis: Sixty people with MS will be randomised (1:1 ratio) to receive a 12-week intervention or usual care only. The intervention consists of four physical activity consultations with a physiotherapist supported by a handbook and pedometer. Outcomes assessed at baseline, 12 weeks and 9 months are physical activity (Actigraph GT3x-BT accelerometer), sedentary behaviour (activPAL3µ), self-reported activity and sitting time, walking capability, fatigue, self-efficacy, participation, quality of life, health service use. The safety of the intervention will be determined by assessing change in pain and fatigue and the incidence of adverse events during the follow-up period. A parallel process evaluation will assess the feasibility and acceptability of the intervention through assessment of fidelity to the programme and semi-structured interviews exploring participants’ and therapists’ experiences of the intervention. The feasibility of conducting an economic evaluation will be determined by collecting data on quality of life and resource use. Ethics and dissemination: Research Ethics Committee approval has been granted from Brunel University London. Results of the trial will be submitted for publication in journals, and distributed to people with MS and physiotherapists.This study is funded by a project grant from the MS Society, UK (award reference: 53)

Role of microstructure and surface defects on the dissolution kinetics of CeO2, a UO2 fuel analogue.

The release of radionuclides from spent fuel in a geological disposal facility is controlled by the surface mediated dissolution of UO2 in groundwater. In this study we investigate the influence of reactive surface sites on the dissolution of a synthesised CeO2 analogue for UO2 fuel. Dissolution was performed on: CeO2 annealed at high temperature, which eliminated intrinsic surface defects (point defects and dislocations); CeO2-x annealed in inert and reducing atmospheres to induce oxygen vacancy defects; and on crushed CeO2 particles of different size fractions. BET surface area measurements were used as an indicator of reactive surface site concentration. Cerium stoichiometry, determined using X-ray Photoelectron Spectroscopy (XPS) and supported by X-ray Diffraction (XRD) analysis, was used to determine oxygen vacancy concentration. Upon dissolution in nitric acid medium at 90°C, a quantifiable relationship was established between the concentration of high energy surface sites and CeO2 dissolution rate; the greater the proportion of intrinsic defects and oxygen vacancies, the higher the dissolution rate. Dissolution of oxygen vacancy-containing CeO2-x gave rise to rates that were an order of magnitude greater than for CeO2 with fewer oxygen vacancies. While enhanced solubility of Ce3+ influenced the dissolution, it was shown that replacement of vacancy sites by oxygen significantly affected the dissolution mechanism due to changes in the lattice volume and strain upon dissolution and concurrent grain boundary decohesion. These results highlight the significant influence of defect sites and grain boundaries on the dissolution kinetics of UO2 fuel analogues and reduce uncertainty in the long-term performance of spent fuel in geological disposal