Stemming and best practice in the mining industry : a literature review

In 2015, after amendments to the explosives regulations, stemming became a mandatory activity for all South African mining operations. There are, however, circumstances in which it is thought stemming has an adverse impact on the blasting outcome. Some of these circumstances include blasting in hot holes, in reactive ground, or when blasting a pre-split. In order to determine when stemming is necessary, its role in the control of adverse blasting phenomena and impact on explosive performance were reviewed. Stemming was found to play a significant role in the fragmentation process and burden movement. Additionally, stemming significantly influences the control of flyrock, air-blast, and toxic fume generation. The review of the literature indicates some motivation for not using stemming for presplit, trim, hot hole, and reactive ground blasting, provided the benefits associated with not stemming the holes outweigh the risks of stemming them. Best practice for stemming from the literature indicates a stemming length of 0.7 × burden is best for larger hole diameters, and 20 to 30 × Ø for smaller hole diameters. Crushed aggregate appears to be the most effective stemming material. The South African explosives regulations pertaining to stemming were found to be consistent with those of Australia and the USA.http://www.saimm.co.za/journal-papersam2022Mining Engineerin

Premature atherosclerosis is associated with hypovitaminosis d and angiotensin-converting enzyme inhibitor non-use in lupus patients

The ultimate goal is to identify and target modifiable risk factors that will reduce major cardiovascular events in African American lupus patients. As a first step toward achieving this goal, this study was designed to explore risk factor models of preclinical atherosclerosis in a predominantly African American group of patients with systemic lupus erythematosus (SLE) using variables historically associated with endothelial function in nonlupus populations. Fifty-one subjects with SLE but without a history of clinical cardiovascular events were enrolled. At entry, a Framingham risk factor history and medication list were recorded. Sera and plasma samples were analyzed for lipids, lupus activity markers and total 25-hydroxyvitamin D (25 OH)D) levels. Carotid ultrasound measurements were performed to determine total plaque area (TPA) in both carotids. Cases had TPA values above age-matched controls from a vascular prevention clinic population. Logistic regression and machine learning analyses were performed to create predictive models. 25(OH)D levels were significantly lower, and SLE disease duration was significantly higher in cases. 25(OH)D levels inversely correlated with age-adjusted TPA. Angiotensin-converting enzyme (ACE) inhibitor nonuse associated with case status. Logistic regression models containing ACE inhibitor use, 25(OH)D levels and low-density lipoprotein levels had a diagnostic accuracy of 84% for predicting accelerated atherosclerosis. Similar results were obtained with machine learning models, but hydroxychlo-roquine use associated with controls in these models. This is the first study to demonstrate an association between atherosclerotic burden and 25(OH)D insufficiency or ACE inhibitor nonuse in lupus patients. These findings provide strong rationale for the study of ACE inhibitors and vitamin D replenishment as preventive therapies in this high-risk population. © Copyright 2012 Southern Society for Clinical Investigation

ARE EXPOSURE PREDICTIONS, USED FOR THE PRIORITISATION OF PHARMACEUTICALS IN THE ENVIRONMENT, FIT FOR PURPOSE?

Prioritisation methodologies are often used for identifying those pharmaceuticals that pose the greatest risk to the natural environment and to focus laboratory testing or environmental monitoring towards pharmaceuticals of greatest concern. Risk-based prioritisation approaches, employing models to derive exposure concentrations, are commonly used but the reliability of these models is unclear. The present study evaluated the accuracy of exposure models commonly used for pharmaceutical prioritisation. Targeted monitoring was conducted for 95 pharmaceuticals in the Rivers Foss and Ouse in the City of York, UK. Predicted environmental concentration (PEC) ranges were estimated based on localised prescription, hydrological data, reported metabolism and wastewater treatment plant (WwTP) removal rates, and were compared to measured environmental concentrations (MECs). For the River Foss, PECs, obtained using highest metabolism and lowest WwTP removal, were similar to MECs. In contrast, this trend was not observed for the River Ouse, possibly due to pharmaceutical inputs beyond our modelling. Pharmaceuticals were ranked by risk based on either MECs or PECs. With two exceptions (dextromethorphan and diphenhydramine), risk ranking based on both MECs and PECs produced similar results in the River Foss. Overall, these findings indicate that PECs may well be appropriate for prioritisation of pharmaceuticals in the environment when robust and local data on the system of interest are available and reflective of most source inputs to the system. This article is protected by copyright. All rights reserved

Instances and connectors : issues for a second generation process language

This work is supported by UK EPSRC grants GR/L34433 and GR/L32699Over the past decade a variety of process languages have been defined, used and evaluated. It is now possible to consider second generation languages based on this experience. Rather than develop a second generation wish list this position paper explores two issues: instances and connectors. Instances relate to the relationship between a process model as a description and the, possibly multiple, enacting instances which are created from it. Connectors refers to the issue of concurrency control and achieving a higher level of abstraction in how parts of a model interact. We believe that these issues are key to developing systems which can effectively support business processes, and that they have not received sufficient attention within the process modelling community. Through exploring these issues we also illustrate our approach to designing a second generation process language.Postprin

The Trend of Disruption in the Functional Brain Network Topology of Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive disorder associated with cognitive dysfunction that alters the brain’s functional connectivity. Assessing these alterations has become a topic of increasing interest. However, a few studies have examined different stages of AD from a complex network perspective that cover different topological scales. This study used resting state fMRI data to analyze the trend of functional connectivity alterations from a cognitively normal (CN) state through early and late mild cognitive impairment (EMCI and LMCI) and to Alzheimer’s disease. The analyses had been done at the local (hubs and activated links and areas), meso (clustering, assortativity, and rich-club), and global (small-world, small-worldness, and efficiency) topological scales. The results showed that the trends of changes in the topological architecture of the functional brain network were not entirely proportional to the AD progression. There were network characteristics that have changed non-linearly regarding the disease progression, especially at the earliest stage of the disease, i.e., EMCI. Further, it has been indicated that the diseased groups engaged somatomotor, frontoparietal, and default mode modules compared to the CN group. The diseased groups also shifted the functional network towards more random architecture. In the end, the methods introduced in this paper enable us to gain an extensive understanding of the pathological changes of the AD process

Enamel remineralization via poly(amido amine) and adhesive resin containing calcium phosphate nanoparticles

Objectives:The objective of this study was to investigate enamel remineralization using salivary statherin pro-tein-inspired poly(amidoamine) dendrimer (SN15-PAMAM) and adhesive containing nanoparticles of amor-phous calcium phosphate (NACP) in a cyclic artificial saliva/demineralizing solution for thefirst time.Methods:The enamel shear bond strengths of NACP adhesives were measured compared to commercial adhesive(Scotchbond Multi-Purpose, 3 M). Adhesive disks containing NACP were tested for calcium (Ca) and phosphorus(P) ions release. Four groups were tested: (1) enamel control, (2) enamel with NACP, (3) enamel with SN15-PAMAM, and (4) enamel with SN15-PAMAM + NACP. The specimens were treated with cyclic artificial saliva/demineralizing solution for 28 days. The remineralized enamel specimens were examined by surface and cross-sectional hardness test.Results:NACP adhesive yielded a similar shear bond strength to commercial control (Scotchbond Multi-Purpose,3 M). NACP adhesive released high levels of Ca and P ions. At 28 days, the enamel hardness of SN15-PAMAM +NACP group was 2.89 ± 0.13 GPa, significantly higher than that of control group (1.46 ± 0.10 GPa) (p< 0.05).SN15-PAMAM + NACP increased the enamel cross-sectional hardness at 28 days; at 25μm, enamel cross-sectional hardness was 90 % higher than that of control group (p< 0.05).Significance:The novel SN15-PAMAM + NACP adhesive method could achieve 90 % higher enamel reminer-alization of the artificial caries than the control under acid challenge for thefirst time. This method is promisingfor use after tooth cavity preparation, or as a coating on enamel with white spot lesions (WSLs) for prevention, toreduce secondary caries, prevent caries procession and protect tooth structures

Genome sequencing of two Neorhizobium galegae strains reveals a noeT gene responsible for the unusual acetylation of the nodulation factors

Background The species Neorhizobium galegae comprises two symbiovars that induce nodules on Galega plants. Strains of both symbiovars, orientalis and officinalis, induce nodules on the same plant species, but fix nitrogen only in their own host species. The mechanism behind this strict host specificity is not yet known. In this study, genome sequences of representatives of the two symbiovars were produced, providing new material for studying properties of N. galegae, with a special interest in genomic differences that may play a role in host specificity. Results The genome sequences confirmed that the two representative strains are much alike at a whole-genome level. Analysis of orthologous genes showed that N. galegae has a higher number of orthologs shared with Rhizobium than with Agrobacterium. The symbiosis plasmid of strain HAMBI 1141 was shown to transfer by conjugation under optimal conditions. In addition, both sequenced strains have an acetyltransferase gene which was shown to modify the Nod factor on the residue adjacent to the non-reducing-terminal residue. The working hypothesis that this gene is of major importance in directing host specificity of N. galegae could not, however, be confirmed. Conclusions Strains of N. galegae have many genes differentiating them from strains of Agrobacterium, Rhizobium and Sinorhizobium. However, the mechanism behind their ecological difference is not evident. Although the final determinant for the strict host specificity of N. galegae remains to be identified, the gene responsible for the species-specific acetylation of the Nod factors was identified in this study. We propose the name noeT for this gene to reflect its role in symbiosis.Peer reviewe

Propuesta guía para una planeación y ejecución en proyectos de vivienda unifamiliar con enfoque Lean Construction

Trabajo de investigaciónEste trabajo contempla el desarrollo de una matriz enfocada en la metodología Lean Construction para la planeación y ejecución en proyectos de vivienda unifamiliar. Así mismo se evidencia un análisis de manera cuantitativa y cualitativamente en la adopción de la filosofía Lean Construction en procesos de la gestión de la planeación y ejecución de proyectos, que permite establecer un orden de actividades y sub actividades que componen las fases de un proyecto de vivienda unifamiliar en la relación del alcance exitoso en productividad y rendimiento.INTRODUCCIÓN 1. GENERALIDADES 2. METODOLOGÍAS EN EL MARCO DE LA PLANEACIÓN Y EJECUCIÓN DE PROYECTOS 3. LEAN CONSTRUCTION EN ACTIVIDADES DE CONSTRUCCIÓN 4. IMPLEMENTACIÓN DE LA MATRIZ EN CASO DE ESTUDIO 5. CONCLUSIONES 6. RECOMENDACIONES BIBLIOGRAFÍA ANEXOSPregradoIngeniero Civi