Building a Fused Deposition Modelling (FDM) 3D Printing Visual Defect Detection System, Part 1: Creation of a Dynamic Imaging System, a Pixel-wise Segmentation Dataset with a Hybrid Synthetic Data Creation Method, and a Semantic Segmentation Algorithm with the SegFormer Deep Learning Model

Dissertation presented as the partial requirement for obtaining a Master's degree in Data Science and Advanced Analytics, specialization in Business AnalyticsAs a part of an effort to develop a surface defect detection system for FDM 3D printed objects, this work project studies the application of the SegFormer network to semantically segment 3D printed objects. The project also showcases an affordable and accessible imaging system designed for the surface defect detection system, to support the decisions made during the segmentation task and to be used to evaluate the segmentation models. To achieve this, the first-ever pixel-wise annotation dataset of 3D-printed object images was created. Model-O1, a SegFormer MiT-B0 model trained on this dataset with minimal data augmentation resulted in an Intersection-over-Union score of 87.04%. A synthetic data creation method that caters to the nature of 3D printed objects was also proposed, which expands upon existing synthetic data creation methods. The model trained on this dataset, Model-A2, achieved an IoU score of 89.31%, the best performance achieved among the models developed in this project. During the evaluation of the model based on the inference results, Model-A2 was also identified to be the most practical model for building a surface defect detection system

Fate and toxicity of spilled chemicals in groundwater and soil environment I: strong acids

We reviewed the chemical/physical properties, toxicity, environmental fate, and ecotoxicity of strong acids in soil and groundwater environments. We recommend that sulfuric acid and hydrofluoric acid be classified as chemicals of priority control based on volumes used, toxicity, carcinogenicity, and past significant spill events. Understanding the behavior and transport of spilled strong acids in soil and groundwater environments requires a multi-disciplinary approach, as they can undergo a variety of geochemical and biochemical reactions with complex geomedia. The toxicity of spilled acid is dependent on the characteristics of the geomedia exposed to the acid and the amount of residual protons following acid–substrate interaction. Soil texture, cation exchange capacity, mineral composition, bedrock type, and aluminum content may be important factors affecting the toxicity of spilled acid in soil-groundwater environments. We expect that the results of this study will contribute preliminary data for future research on chemical spills

Cyclic ADP Ribose-Dependent Ca2+ Release by Group I Metabotropic Glutamate Receptors in Acutely Dissociated Rat Hippocampal Neurons

Group I metabotropic glutamate receptors (group I mGluRs; mGluR1 and mGluR5) exert diverse effects on neuronal and synaptic functions, many of which are regulated by intracellular Ca2+. In this study, we characterized the cellular mechanisms underlying Ca2+ mobilization induced by (RS)-3,5-dihydroxyphenylglycine (DHPG; a specific group I mGluR agonist) in the somata of acutely dissociated rat hippocampal neurons using microfluorometry. We found that DHPG activates mGluR5 to mobilize intracellular Ca2+ from ryanodine-sensitive stores via cyclic adenosine diphosphate ribose (cADPR), while the PLC/IP3 signaling pathway was not involved in Ca2+ mobilization. The application of glutamate, which depolarized the membrane potential by 28.5±4.9 mV (n = 4), led to transient Ca2+ mobilization by mGluR5 and Ca2+ influx through L-type Ca2+ channels. We found no evidence that mGluR5-mediated Ca2+ release and Ca2+ influx through L-type Ca2+ channels interact to generate supralinear Ca2+ transients. Our study provides novel insights into the mechanisms of intracellular Ca2+ mobilization by mGluR5 in the somata of hippocampal neurons

A Novel Process for Extracting Precious Metals from Spent Mobile Phone PCBs and Automobile Catalysts

A novel process to simultaneously extract the precious metals such as gold, silver, platinum, palladium and rhodium from spent mobile phone printed circuit boards (PCBs) and honeycomb-type auto catalysts by smelting using waste-copper slag without adding any collector metals or by-products such as dross, matte and slime has been developed. In the process, waste-copper slag which is an industrial waste discharged from copper smelter is used not only as a flux for controlling slag composition, but also as a collector metal for capturing precious metals, and a plastic component contained in spent mobile phone PCBs is done as a reducing agent of iron oxides contained in the waste-copper slag. Using the developed process, up to 95% of gold, silver, platinum, palladium and rhodium contained in the raw materials were extracted in a CuFeSn alloy phase, respectively

Combination therapy of vitamin C and thiamine for septic shock in a multicentre, double-blind, randomized, controlled study (ATESS): study protocol for a randomized controlled trial

Background Septic shock is a life-threatening condition with underlying circulatory and cellular/metabolic abnormalities. Vitamin C and thiamine are potential candidates for adjunctive therapy; they are expected to improve outcomes based on recent experimental and clinical research. The aim of the Ascorbic Acid and Thiamine Effect in Septic Shock (ATESS) trial is to evaluate the effects of early combination therapy with intravenous vitamin C and thiamine on recovery from organ failure in patients with septic shock. Methods This study is a randomized, double-blind, placebo-controlled, multicentre trial in adult patients with septic shock recruited from six emergency departments in South Korea. Patients will be randomly allocated into the treatment or control group (1:1 ratio), and we will recruit 116 septic shock patients (58 per group). For the treatment group, vitamin C (50 mg/kg) and thiamine (200 mg) will be mixed in 50 ml of 0.9% saline and administered intravenously every 12 h for a total of 48 h. For the placebo group, an identical volume of 0.9% saline will be administered in the same manner. The primary outcome is the delta Sequential Organ Failure Assessment (SOFA) score (ΔSOFA = initial SOFA at enrolment – follow-up SOFA after 72 h). Discussion This trial will provide valuable evidence about the effectiveness of vitamin C and thiamine therapy for septic shock. If effective, this therapy might improve survival and become one of the main therapeutic adjuncts for patients with septic shock. Trial registration ClinicalTrials.gov, NCT03756220. Registered on 5 December 2018.This work was supported by a National Research Foundation of Korea grant funded by the Korean government (No. 2018R1C1B6006821). The government did not have any role in the study design; collection, management, analysis, and interpretation of data; writing of the report; and the decision to submit the report for publication

Use of Phosphate Solubilizing Bacteria to Leach Rare Earth Elements from Monazite-Bearing Ore

In the present study, the feasibility to use phosphate solubilizing bacteria (PSB) to develop a biological leaching process of rare earth elements (REE) from monazite-bearing ore was determined. To predict the REE leaching capacity of bacteria, the phosphate solubilizing abilities of 10 species of PSB were determined by halo zone formation on Reyes minimal agar media supplemented with bromo cresol green together with a phosphate solubilization test in Reyes minimal liquid media as the screening studies. Calcium phosphate was used as a model mineral phosphate. Among the test PSB strains, Pseudomonas fluorescens, P. putida, P. rhizosphaerae, Mesorhizobium ciceri, Bacillus megaterium, and Acetobacter aceti formed halo zones, with the zone of A. aceti being the widest. In the phosphate solubilization test in liquid media, Azospirillum lipoferum, P. rhizosphaerae, B. megaterium, and A. aceti caused the leaching of 6.4%, 6.9%, 7.5%, and 32.5% of calcium, respectively. When PSB were used to leach REE from monazite-bearing ore, ~5.7 mg/L of cerium (0.13% of leaching efficiency) and ~2.8 mg/L of lanthanum (0.11%) were leached by A. aceti, and Azospirillum brasilense, A. lipoferum, P. rhizosphaerae and M. ciceri leached 0.5–1 mg/L of both cerium and lanthanum (0.005%–0.01%), as measured by concentrations in the leaching liquor. These results indicate that determination of halo zone formation was found as a useful method to select high-capacity bacteria in REE leaching. However, as the leaching efficiency determined in our experiments was low, even in the presence of A. aceti, further studies are now underway to enhance leaching efficiency by selecting other microorganisms based on halo zone formation

Determination of the Habitat Preferences of Dominant Epilithic Diatoms Using Statistical Models: A Case Study in the Han River, South Korea

Diatoms have traditionally been used to assess water quality; however, current research suggests that physical factors, such as habitat and landscape, may be linked to the organization of diatom assemblages in streams. The aim of this study was to determine the environmental factors affecting the physiological and ecological changes of epilithic diatoms. To this end, the dominant diatom species were used, and a strategy based on epilithic diatom habitat characteristics was investigated for river restoration. The classification and regression tree (CART) and weighted averaging (WA) regression models were used to determine the habitat preference of epilithic diatoms and physicochemical environmental factors. The 35 environmental variables and six epilithic diatom species that were dominant at 58 sites along the Han River in South Korea were used. The species abundance and composition of adherent diatoms were affected by nutrient concentration and a variety of physicochemical environmental factors. These results suggest that when evaluating water quality, various factors that affect the abundance of epilithic diatoms should be considered. Research on the autecological characteristics and environmental preferences of indicator diatom species could help establish river restoration policies and quantitative evaluation criteria for biological assessments

Environmental Compatibility of Lightweight Aggregates from Mine Tailings and Industrial Byproducts

A lightweight aggregate was produced by sintering the mixture of gold mine tailings, red mud, and limestone at 1150 °C. The physical (i.e., skid resistance, abrasion resistance, and bond strength) and environmental (i.e., leachability) feasibility of this aggregate was assessed to consider its potential use as a construction material for bicycle lanes. The skid resistance (British pendulum number of 71) and bond strength (1.5 N·mm−2) of the aggregate were found to be appropriate for this use. However, the abrasion loss value of the aggregate was found to be 290 mg, which exceeds the limit of Korean Standard KS F 281 (200 mg). Heavy metals were found to not leach from the aggregate in various leaching tests. These include Korean (Korea Standard Method for Solid Waste), American (Toxic Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP)), and European (BS EN 12457-1) leaching tests, despite the raw materials containing significant amounts of Pb, As, and F. However, leachate extracted from the aggregate exhibited an aquatic toxicity to Daphnia magna of 13.94 TU24hr and 14.25 TU48hr, most likely due to a high pH and Ca concentration originating from the free CaO present in the aggregate. The data suggests that the physical properties of the reconstructed aggregate are appropriate for use in bicycle lane construction, however the dissolution of Ca and the pH level of the leachate need to be controlled to protect aquatic ecosystems

Evaluation of bioleaching factors on gold recovery from ore by cyanide-producing bacteria

The present study was conducted to investigate the gold bioleaching factors from ore by cyanide producing bacter- ium Chromobacterium violaceum. The optimal condition for cyanide production by C.violaceum was pH9 and 5g/L of glycine in YP medium in 2-days of incubation. In shake flask culture, gold bioleaching from the ores by C.violaceum, pH, and biooxidative treatment. The three types of low grade ores viz, R, S. and H were used. The gold bioleaching effeciencies were recorded as 0%, 50%, and 5% for ores R, S, and H, respectively, when C. violaceum culture was used without any pretreatment (protocol 1). In the experimental protocol involving grinding and pre-grown C.violaceum, leaching efficiencies increased to 60%, 100% and 40% for ore R, S, and H samples, respectively. Especially, the bioleaching effic-iency of ore S enhanced to almost 100% with pre-grown C.violaceum (protocol 3) due to their mineralogical characteristics of the ores. For refractory gold (i.e., ore R) grinding as pretreatment was needed, and for ore S (almost all of the gold was cyanidable) cyanide production was activated by using pre-grown bacteria. Biooxidation with Acidithiobacillus ferrooxidans and pH adjustment (i.e., 9-11) did not affect the bioleaching efficiencies. the mineralogical cause of gold refractoriness was anal-yzed by automated SEM that showed most of gold in the ore was entrapped in pyrite and silica. The results indicated that gold bioleaching by C.violaceum from low grade ore can be enhanced by grinding and pre-grown microbe; use of appropriate experimental condition is important according to the mineralogical characteristics