scholarly journals Effect of water-to-cement ratio and curing method on the strength, shrinkage and slump of the biosand filter concrete body

2018 ◽  
Vol 77 (6) ◽  
pp. 1744-1750 ◽  
Author(s):  
Nicole Chan ◽  
Candice Young-Rojanschi ◽  
Simon Li
Keyword(s):  
Quality Control ◽  
Control Measures ◽  
Treatment Technology ◽  
Household Level ◽  
Biosand Filter ◽  
Water To Cement Ratio ◽  
Concrete Body ◽  
Concrete Mix ◽  
Biosand Filters ◽  
Curing Method

Abstract The biosand filter is a household-level water treatment technology used globally in low-resource settings. As of December 2016, over 900,000 biosand filters had been implemented in 60 countries around the world. Local, decentralized production is one of the main advantages of this technology, but it also creates challenges, especially in regards to quality control. Using the current recommended proportions for the biosand filter concrete mix, slump was measured at water-to-cement ratios of 0.51, 0.64 and 0.76, with two replicates for each level. Twenty-eight-day strength was tested on four replicate cylinders, each at water-to-cement ratios of 0.51, 0.59, 0.67 and 0.76. Wet curing and dry curing were compared for 28-day strength and for their effect on shrinkage. Maximum strength occurred at water-to-cement ratios of 0.51–0.59, equivalent to 8–9.3 L water for a full-scale filter assuming saturated media, corresponding to a slump class of S1 (10–40 mm). Wet curing significantly improved strength of the concrete mix and reduced shrinkage. Quality control measures such as the slump test can significantly improve the quality within decentralized production of biosand filters, despite localized differences in production conditions.

The Construction of the Later Poured Band and Quality Control

2014 ◽  
Vol 926-930 ◽  
pp. 661-664
Author(s):  
Min Chen
Keyword(s):  
Quality Control ◽  
Reinforced Concrete ◽  
Body Temperature ◽  
Construction Technique ◽  
High Rise ◽  
Concrete Body ◽  
Contraction Stress

Setting the late poured band is to solve different settlement between high-rise buildings and to settle the reinforced concrete body temperature--contraction stress. In addition, it effectively avoids the harmful cracks caused by the reinforced concrete body. So it is vital to set the late poured band and organize the correct construction. This paper aims at elaborating types of post pouring belt, construction preparation, construction technique, quality and so on.

scholarly journals SELF-REPORTED MALARIA AND MOSQUITO AVOIDANCE IN RELATION TO HOUSEHOLD RISK FACTORS IN A KENYAN COASTAL CITY

2005 ◽  
Vol 37 (6) ◽  
pp. 761-771 ◽  
Author(s):  
JOSEPH KEATING ◽  
KATE MACINTYRE ◽  
CHARLES M. MBOGO ◽  
JOHN I. GITHURE ◽  
JOHN C. BEIER
Keyword(s):  
Rural Areas ◽  
Mosquito Control ◽  
Control Measure ◽  
Control Measures ◽  
Level Control ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Household Level ◽  
Household Factors ◽  
History Of

A geographically stratified cross-sectional survey was conducted in 2002 to investigate household-level factors associated with use of mosquito control measures and self-reported malaria in Malindi, Kenya. A total of 629 households were surveyed. Logistic regressions were used to analyse the data. Half of all households (51%) reported all occupants using an insecticide-treated bed net and at least one additional mosquito control measure such as insecticides or removal of standing water. Forty-nine per cent reported a history of malaria in the household. Of the thirteen household factors analysed, low (OR=0·23, CI 0·11, 0·48) and medium (OR=0·50, CI 0·29, 0·86) education, mud–wood–coral (OR=0·0·39, CI 0·24, 0·66) and mud block–plaster (OR=0·47, CI 0·25, 0·87) wall types, farming (OR=1·38, CI 1·01, 1·90) and travel to rural areas (OR=0·48, CI 0·26, 0·91) were significantly associated with the use of mosquito control, while controlling for other covariates in the model. History of reported malaria was not associated with the use of mosquito control (OR=1·22, CI 0·79, 1·88). Of the thirteen covariates analysed in the second model, only two household factors were associated with history of malaria: being located in the well-drained stratum (OR=0·49, CI 0·26, 0·96) and being bitten while in the house (OR=1·22, CI 0·19, 0·49). These results suggest that high socioeconomic status is associated with increased household-level mosquito control use, although household-level control may not be enough, as many people are exposed to biting mosquitoes while away from the house and in areas that are more likely to harbour mosquitoes.

Microbiological Water Methods: Quality Control Measures for Federal Clean Water Act and Safe Drinking Water Act Regulatory Compliance

2014 ◽  
Vol 97 (2) ◽  
pp. 567-572 ◽  
Author(s):  
Patsy Root ◽  
Margo Hunt ◽  
Karla Fjeld ◽  
Laurie Kundrat
Keyword(s):  
Quality Control ◽  
Drinking Water ◽  
Clean Water Act ◽  
Regulatory Compliance ◽  
Control Measures ◽  
Clean Water ◽  
Safe Drinking Water ◽  
Safe Drinking Water Act ◽  
Specificity And Sensitivity ◽  
Microbiological Methods

Abstract Quality assurance (QA) and quality control (QC) data are required in order to have confidence in the results from analytical tests and the equipment used to produce those results. Some AOAC water methods include specific QA/QC procedures, frequencies, and acceptance criteria, but these are considered to be the minimum controls needed to perform a microbiological method successfully. Some regulatory programs, such as those at Code of Federal Regulations (CFR), Title 40, Part 136.7 for chemistry methods, require additional QA/QC measures beyond those listed in the method, which can also apply to microbiological methods. Essential QA/QC measures include sterility checks, reagent specificity and sensitivity checks, assessment of each analyst's capabilities, analysis of blind check samples, and evaluation of the presence of laboratory contamination and instrument calibration and checks. The details of these procedures, their performance frequency, and expected results are set out in this report as they apply to microbiological methods. The specific regulatory requirements of CFR Title 40 Part 136.7 for the Clean Water Act, the laboratory certification requirements of CFR Title 40 Part 141 for the Safe Drinking Water Act, and the International Organization for Standardization 17025 accreditation requirements under The NELAC Institute are also discussed.

scholarly journals Standardized quality control workflow to evaluate the reproducibility and differentiation potential of human iPSCs into neurons

2021 ◽  
Author(s):  
Carol X.-Q. Chen ◽  
Narges Abdian ◽  
Gilles Maussion ◽  
Rhalena A. Thomas ◽  
Iveta Demirova ◽  
...  
Keyword(s):  
Stem Cells ◽  
Quality Control ◽  
Cortical Neurons ◽  
Genomic Stability ◽  
Control Measures ◽  
List Type ◽  
Ipsc Line ◽  
Differentiation Potential ◽  
Germ Layers ◽  
Human Ipscs

AbstractInduced pluripotent stem cells (iPSCs) derived from human somatic cells have created new opportunities to generate disease-relevant cells. Thus, as the use of patient-derived stem cells has become more widespread, having a workflow to monitor each line is critical. This ensures iPSCs pass a suite of quality control measures, promoting reproducibility across experiments and between labs. With this in mind, we established a four-step workflow to assess our newly generated iPSCs for variations and reproducibility relative to each other and iPSCs obtained from external sources. Our benchmarks for evaluating iPSCs include examining iPSC morphology and proliferation in two different media conditions (mTeSR1 and Essential 8) and evaluating their ability to differentiate into each of the three germ layers, with a particular focus on neurons. Genomic stability in the human iPSCs was analyzed by G-band karyotyping and a qPCR-based stability test, and cell-line identity authenticated by Short Tandem Repeat (STR) analysis. Using standardized dual SMAD inhibition methods, all iPSC lines gave rise to neural progenitors that could subsequently be differentiated into cortical neurons. Neural differentiation was analyzed qualitatively by immunocytochemistry and quantitatively by q-PCR for progenitor, neuronal, cortical and glial markers. Taken together, we present a standardized quality control workflow to evaluate variability and reproducibility across and between iPSCs.HighlightsValidation of culture conditions is critical in the expansion and maintenance of an iPSC line.Characterization of pluripotency and genomic stability ensures each line is free of defects at the DNA level, while maintaining its ability to be directed into any of the three germ layers.Forebrain cortical neurons can be generated from all iPSC line tested; however, the morphology and expression pattern of these neurons can vary from line to line.

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