scholarly journals Solidification/Stabilization of Arsenic-Containing Tailings by Steel Slag-Based Binders with High Efficiency and Low Carbon Footprint

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5864
Author(s):  
Wei Gao ◽  
Zifu Li ◽  
Siqi Zhang ◽  
Yuying Zhang ◽  
Guoxiang Teng ◽  
...  
Keyword(s):  
High Efficiency ◽  
Environmental Problem ◽  
Steel Slag ◽  
Leaching Tests ◽  
Test Results ◽  
Low Carbon ◽  
The Mean ◽  
Leaf Test ◽  
Leaching Risk ◽  
Leaching Mechanism

The disposal of nonferrous metal tailings poses a global economic and environmental problem. After employing a clinker-free steel slag-based binder (SSB) for the solidification/stabilization (S/S) of arsenic-containing tailings (AT), the effectiveness, leaching risk, and leaching mechanism of the SSB S/S treated AT (SST) were investigated via the Chinese leaching tests HJ/T299-2007 and HJ557-2010 and the leaching tests series of the multi-process Leaching Environmental Assessment Framework (LEAF). The test results were compared with those of ordinary Portland cement S/S treated AT (PST) and showed that the arsenic (As) curing rates for SST and PST samples were in the range of 96.80–98.89% and 99.52–99.2%, respectively, whereby the leached-As concentration was strongly dependent on the pH of the leachate. The LEAF test results showed that the liquid–solid partitioning limit of As leaching from AT, SST, and PST was controlled by solubility, and the highest concentrations of leached As were 7.56, 0.34, and 0.33 mg/L, respectively. The As leaching mechanism of monolithic SST was controlled by diffusion, and the mean observed diffusion coefficient of 9.35 × 10−15 cm2/s was higher than that of PST (1.55 × 10−16 cm2/s). The findings of this study could facilitate the utilization of SSB in S/S processes, replacing cement to reduce CO2 emissions.

Statistically Significant Efficiency Testing of HEPA Filters

2004 ◽  
Vol 47 (1) ◽  
pp. 101-106 ◽  
Author(s):  
Wenli Wang ◽  
Philip Winters
Keyword(s):  
High Efficiency ◽  
Test System ◽  
Test Results ◽  
Upper Limits ◽  
Efficiency Performance ◽  
Measured Efficiency ◽  
The Mean ◽  
Particle Counts ◽  
The One ◽  
Time Required

High Efficiency Particulate Air (HEPA) filter manufacturers must ensure the accuracy of efficiency testing for these filters and, at the same time, keep productivity at a reasonable level. This study describes tests conducted to determine the minimum time required to provide statistically significant efficiencies of HEPA filters using a test system currently in use of HEPA filter production. The test results of over 300 HEPA filters were analyzed in this study. The approaches in IEST RP-CC-007.1: Testing ULPA Filters for statistical analysis of particle counts were followed. A Poisson distribution was used to describe the variations and to calculate the lower and upper limits of measured counts at 95% confidence level. This study shows that 90 seconds is sufficient for this test system to determine whether a HEPA filter has an efficiency of 99.990% or higher at 95% confidence. Longer tests will cause the mean measured efficiency to approach the filter's true efficiency and also narrow the confidence interval. However, challenging HEPA filters made of glass fiber media with oil aerosols for up to one hour does not significantly change the filter's true efficiency performance. The preferred approach for a new test system is to use software that calculates the confidence limits of filter efficiency after each sampling cycle and determines whether to continue testing. For an existing system without this type of program (such as the one evaluated in this study), analysis is necessary to make sure the HEPA filters are challenged with enough aerosol particles.

scholarly journals A Review of Hydrogen Purification Technologies for Fuel Cell Vehicles

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 393
Author(s):  
Zhemin Du ◽  
Congmin Liu ◽  
Junxiang Zhai ◽  
Xiuying Guo ◽  
Yalin Xiong ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Carbon Emission ◽  
High Efficiency ◽  
Impurity Content ◽  
Fuel Cell Vehicle ◽  
Research Progress ◽  
Hydrogen Purification ◽  
Fuel Cell Vehicles ◽  
Low Carbon

Nowadays, we face a series of global challenges, including the growing depletion of fossil energy, environmental pollution, and global warming. The replacement of coal, petroleum, and natural gas by secondary energy resources is vital for sustainable development. Hydrogen (H2) energy is considered the ultimate energy in the 21st century because of its diverse sources, cleanliness, low carbon emission, flexibility, and high efficiency. H2 fuel cell vehicles are commonly the end-point application of H2 energy. Owing to their zero carbon emission, they are gradually replacing traditional vehicles powered by fossil fuel. As the H2 fuel cell vehicle industry rapidly develops, H2 fuel supply, especially H2 quality, attracts increasing attention. Compared with H2 for industrial use, the H2 purity requirements for fuel cells are not high. Still, the impurity content is strictly controlled since even a low amount of some impurities may irreversibly damage fuel cells’ performance and running life. This paper reviews different versions of current standards concerning H2 for fuel cell vehicles in China and abroad. Furthermore, we analyze the causes and developing trends for the changes in these standards in detail. On the other hand, according to characteristics of H2 for fuel cell vehicles, standard H2 purification technologies, such as pressure swing adsorption (PSA), membrane separation and metal hydride separation, were analyzed, and the latest research progress was reviewed.

scholarly journals Ex vivo evaluation of a multilayered sealant patch for watertight dural closure: cranial and spinal models

2021 ◽  
Vol 32 (8) ◽  
Author(s):  
A. Kinaci ◽  
S. van Thoor ◽  
S. Redegeld ◽  
M. Tooren ◽  
T. P. C. van Doormaal
Keyword(s):  
Ex Vivo ◽  
Resistance Test ◽  
Burst Pressure ◽  
Cerebrospinal Fluid Leakage ◽  
Computer Assisted ◽  
Dural Defect ◽  
Test Results ◽  
Physiological Conditions ◽  
Dural Attachment ◽  
The Mean

AbstractCerebrospinal fluid leakage is a frequent complication after cranial and spinal surgery. To prevent this complication and seal the dura watertight, we developed Liqoseal, a dural sealant patch comprising a watertight polyesterurethane layer and an adhesive layer consisting of poly(DL-lactide-co-ε-caprolactone) copolymer and multiarmed N-hydroxylsuccinimide functionalized polyethylene glycol. We compared acute burst pressure and resistance to physiological conditions for 72 h of Liqoseal, Adherus, Duraseal, Tachosil, and Tisseel using computer-assisted models and fresh porcine dura. The mean acute burst pressure of Liqoseal in the cranial model (145 ± 39 mmHg) was higher than that of Adherus (87 ± 47 mmHg), Duraseal (51 ± 42 mmHg) and Tachosil (71 ± 16 mmHg). Under physiological conditions, cranial model resistance test results showed that 2 of 3 Liqoseal sealants maintained dural attachment during 72 hours as opposed to 3 of 3 for Adherus and Duraseal and 0 of 3 for Tachosil. The mean burst pressure of Liqoseal in the spinal model (233 ± 81 mmHg) was higher than that of Tachosil (123 ± 63 mmHg) and Tisseel (23 ± 16 mmHg). Under physiological conditions, spinal model resistance test results showed that 2 of 3 Liqoseal sealants maintained dural attachment for 72 hours as opposed to 3 of 3 for Adherus and 0 of 3 for Duraseal and Tachosil. This novel study showed that Liqoseal is capable of achieving a strong watertight seal over a dural defect in ex vivo models.

scholarly journals New Methodology for Computing the Aircraft’s Position Based on the PPP Method in GPS and GLONASS Systems

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2525
Author(s):  
Kamil Krasuski ◽  
Damian Wierzbicki
Keyword(s):  
Linear Combination ◽  
Research Method ◽  
High Efficiency ◽  
Satellite System ◽  
Weighting Scheme ◽  
Measurement Technology ◽  
Dual Frequency ◽  
Weighted Mean ◽  
Mean Error ◽  
The Mean

In the field of air navigation, there is a constant pursuit for new navigation solutions for precise GNSS (Global Navigation Satellite System) positioning of aircraft. This study aims to present the results of research on the development of a new method for improving the performance of PPP (Precise Point Positioning) positioning in the GPS (Global Positioning System) and GLONASS (Globalnaja Nawigacionnaja Sputnikovaya Sistema) systems for air navigation. The research method is based on a linear combination of individual position solutions from the GPS and GLONASS systems. The paper shows a computational scheme based on the linear combination for geocentric XYZ coordinates of an aircraft. The algorithm of the new research method uses the weighted mean method to determine the resultant aircraft position. The research method was tested on GPS and GLONASS kinematic data from an airborne experiment carried out with a Seneca Piper PA34-200T aircraft at the Mielec airport. A dual-frequency dual-system GPS/GLONASS receiver was placed on-board the plane, which made it possible to record GNSS observations, which were then used to calculate the aircraft’s position in CSRS-PPP software. The calculated XYZ position coordinates from the CSRS-PPP software were then used in the weighted mean model’s developed optimization algorithm. The measurement weights are a function of the number of GPS and GLONASS satellites and the inverse of the mean error square. The obtained coordinates of aircraft from the research model were verified with the RTK-OTF solution. As a result of the research, the presented solution’s accuracy is better by 11–87% for the model with a weighting scheme as a function of the inverse of the mean error square. Moreover, using the XYZ position from the RTKLIB program, the research method’s accuracy increases from 45% to 82% for the model with a weighting scheme as a function of the inverse of the square of mean error. The developed method demonstrates high efficiency for improving the performance of GPS and GLONASS solutions for the PPP measurement technology in air navigation.

Genotoxicity Screening of Leachates from Solid Industrial Wastes Evaluated with the Allium Test

1997 ◽  
Vol 25 (3) ◽  
pp. 311-321 ◽  
Author(s):  
Peter G. Odeigah ◽  
Jide Ijimakinwa ◽  
Bimbo Lawal ◽  
Rebecca Oyeniyi
Keyword(s):  
Steel Slag ◽  
Settling Tank ◽  
Growth Curves ◽  
Solid Wastes ◽  
Industrial Wastes ◽  
Allium Test ◽  
Chemical Company ◽  
The Mean ◽  
Paint Sludge ◽  
Toxic Industrial Waste

Six solid wastes from the metal industry, from the chemical industry and from the production of pesticides were investigated for their toxic and genotoxic properties by using the Allium test. To simulate environmental conditions and better assess their environmental impact, the solid wastes were leached with water, and the water-extractable micropollutants were lyophilised before screening. The mean root lengths of onions exposed to different concentrations of the leachates were measured, and EC50 values were determined from the growth curves. The EC50 values of the wastes were ranked, in the order: organochlorine pesticide waste, settling tank sludge from a chemical company, paint sludge, lead slag, steel slag and aluminium slag. The leachates were also mitodepressive, and caused significant increases in the frequency of chromosome aberrations. These results demonstrate that the Allium test is a useful screening test for the evaluation and ranking of toxic industrial waste.

scholarly journals Development of UHPC Mixtures Utilizing Natural and Industrial Waste Materials as Partial Replacements of Silica Fume and Sand

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Shamsad Ahmad ◽  
Ibrahim Hakeem ◽  
Mohammed Maslehuddin
Keyword(s):  
Silica Fume ◽  
Industrial Waste ◽  
Steel Slag ◽  
Limestone Powder ◽  
Waste Materials ◽  
Cement Kiln ◽  
Test Results ◽  
Strength Criteria ◽  
Natural Pozzolana ◽  
Kiln Dust

In the exploratory study presented in this paper, an attempt was made to develop different mixtures of ultrahigh performance concrete (UHPC) using various locally available natural and industrial waste materials as partial replacements of silica fume and sand. Materials such as natural pozzolana (NP), fly ash (FA), limestone powder (LSP), cement kiln dust (CKD), and pulverized steel slag (PSS), all of which are abundantly available in Saudi Arabia at little or no cost, were employed in the development of the UHPC mixtures. A base mixture of UHPC without replacement of silica fume or sand was selected and a total of 24 trial mixtures of UHPC were prepared using different percentages of NP, FA, LSP, CKD, and PSS, partially replacing the silica fume and sand. Flow and 28-d compressive strength of each UHPC mixture were determined to finally select those mixtures, which satisfied the minimum flow and strength criteria of UHPC. The test results showed that the utilization of NP, FA, LSP, CKD, and PSS in production of UHPC is possible with acceptable flow and strength. A total of 10 UHPC mixtures were identified with flow and strength equal to or more than the minimum required.

scholarly journals Distances between mandibular posterior teeth and the WALA ridge in Peruvians with normal occlusion

2017 ◽  
Vol 22 (6) ◽  
pp. 56-60 ◽  
Author(s):  
Carla Y. Kong-Zárate ◽  
Marcos J. Carruitero ◽  
Will A. Andrews
Keyword(s):  
Age Groups ◽  
Test Results ◽  
Posterior Teeth ◽  
Normal Occlusion ◽  
Tooth Type ◽  
The Mean ◽  
Student’S T ◽  
Mandibular Posterior Teeth ◽  
Digital Caliper ◽  
Student’S T Test

ABSTRACT Objective: The purposes of this investigation were to determine the horizontal distances between the mandibular posterior teeth and the WALA ridge in a sample of Peruvians with normal occlusion and to compare them by tooth type, sex, arch side, and age groups. Methods: 65 dental casts of subjects with normal occlusion were collected. Posterior teeth, except for third molars, were evaluated. The horizontal distances between the occluso-gingival midpoints of the buccal surfaces (FA points) of each tooth and the WALA ridge were measured using a modified digital caliper. The values between each different tooth type within the sample were compared using the ANOVA and Scheffe tests, while comparisons by sex, arch side and age groups, using the Student’s t-test. Results: The mean distances in the sample was 0.96 mm for first premolars, 1.45 mm for second premolars, 2.12 mm for first molars and 2.55 mm for second molars. Statistically significant differences between each of the four tooth types were found. There were no significant differences found between sex, arch side and age groups. Conclusion: The horizontal distances between the mandibular posterior teeth and the WALA ridge increased progressively from the first premolars to the second molars in Peruvians with normal occlusion. The WALA ridge was a good landmark to evaluate the positions of posterior teeth in Peruvians with normal occlusion.

scholarly journals Handgrip strength and muscle fatigue among footwear industry workers

2016 ◽  
Vol 29 (2) ◽  
pp. 317-324 ◽  
Author(s):  
Lidiane Angélica Cotelez ◽  
Maysa Venturoso Gongora Buckeridge Serra ◽  
Eliane Ramos ◽  
José Eduardo Zaia ◽  
Flávia Oliveira Toledo ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Muscle Fatigue ◽  
Handgrip Strength ◽  
Strength Test ◽  
Strength Testing ◽  
Test Results ◽  
Irreversible Damage ◽  
Low Correlation ◽  
Footwear Industry ◽  
The Mean

Abstract Introduction: Muscle fatigue can be defined as a decrease in the performance of the neuromuscular system in generating force. This situation is considered a complex physiological process involving various body systems, in order to avoid irreversible damage or even cell death. Objective: The aim of this study was to measure muscle strength in order to assess the level of fatigue among footwear industry workers, and to determine a possible correlation between muscle strength and the perception of reported fatigue. Materials and Methods: The study included 32 male workers from the footwear industry with a mean age of 34.63 ± 11.98 years. The workers performed the handgrip strength test using a handheld dynamometer, and completed the Bipolar Fatigue Questionnaire. Results: The mean result of strength testing was 23.1 ± 8.3 kgf, and the mean score of the fatigue questionnaire was 2.28 ± 0.93 points. However, a low correlation was observed between the results of the fatigue questionnaire and the strength test results. Conclusion: The grip strength results of the footwear workers were below the values for the general Brazilian population, a fact that may indicate potential muscle fatigue. However, a low correlation with the perception of fatigue was indicated by the questionnaire.

Assessment of fundamental movement patterns and risk of injury in male soccer players

Physiotherapy ◽  
2017 ◽  
Vol 24 (2) ◽  
Author(s):  
Stanisław Gadziński ◽  
Agata Masłoń ◽  
Dorota Czechowska ◽  
Joanna Golec ◽  
Elżbieta Szczygieł ◽  
...  
Keyword(s):  
Functional Status ◽  
Age Groups ◽  
Soccer Players ◽  
Functional Movement Screen ◽  
Test Results ◽  
Motor Tasks ◽  
Functional Movement ◽  
Risk Of Injury ◽  
The Mean ◽  
Fundamental Movement Patterns

AbstractIntroduction. The aim of the study was to assess the functional status of male soccer players in different age groups who played on different surfaces. Methods. The study included 45 soccer players aged 13-35 years. Among them, 15 were junior players, 15 were players of the senior Silesia-Opole 3rd league (SL), and 15 were senior players in the futsal Extra Class league (SF). The functional status and basic motor skills were assessed according to the results obtained in seven motor tasks included in the Functional Movement Screen™ (FMS) test. Results. The mean total scores in the FMS test were statistically significantly higher among both senior futsal and senior 3

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