Improving the strength of sandy soils via ureolytic CaCO&lt;sub&gt;3&lt;/sub&gt; solidification by &lt;i&gt;Sporosarcina ureae&lt;/i&gt;

Abstract. “Microbially induced carbonate precipitation” (MICP) is a biogeochemical process that can be applied to strengthen materials. The hydrolysis of urea by microbial catalysis to form carbonate is a commonly studied example of MICP. In this study, Sporosarcina ureae, a ureolytic organism, was compared to other ureolytic and non-ureolytic organisms of Bacillus and Sporosarcina genera in the assessment of its ability to produce carbonates by ureolytic MICP for ground reinforcement. It was found that S. ureae grew optimally in alkaline (pH ∼ 9.0) conditions which favoured MICP and could degrade urea (units U mL−1 represent µmol min−1 mL OD600) at levels (30.28 U mL−1) similar to S. pasteurii (32.76 U mL−1), the model ureolytic MICP organism. When cells of S. ureae were concentrated (OD600 ∼ 15–20) and mixed with cementation medium containing 0.5 M calcium chloride (CaCl2) and urea into a model sand, repeated treatments (3 × 24 h) were able to improve the confined direct shear strength of samples from 15.77 kPa to as much as 135.80 kPa. This was more than any other organism observed in the study. Imaging of the reinforced samples with scanning electron microscopy and energy-dispersive spectroscopy confirmed the successful precipitation of calcium carbonate (CaCO3) across sand particles by S. ureae. Treated samples were also tested experimentally according to model North American climatic conditions to understand the environmental durability of MICP. No statistically significant (p < 0.05, n= 3) difference in strength was observed for samples that underwent freeze–thaw cycling or flood-like simulations. However, shear strength of samples following acid rain simulations fell to 29.2 % of control MICP samples. Overall, the species S. ureae was found to be an excellent organism for MICP by ureolysis to achieve ground strengthening. However, the feasibility of MICP as a durable reinforcement technique is limited by specific climate conditions (i.e. acid rain).

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Improving the Strength of Sandy Soils via Ureolytic CaCO3 Solidification by Sporosarcina ureae

10.5194/bg-2017-517 ◽

2018 ◽

Author(s):

Justin Michael Whitaker ◽

Sai Vanapalli ◽

Danielle Fortin

Keyword(s):

Sandy Soils ◽

Climatic Conditions ◽

Carbonate Precipitation ◽

Alkaline Ph ◽

Biogeochemical Process ◽

Sporosarcina Ureae ◽

Environmental Durability ◽

Sand Particles ◽

Hydrolysis Of ◽

Scanning Electron

Abstract. Microbial induced carbonate precipitation (MICP) is a biogeochemical process that can be applied to strengthen materials. The hydrolysis of urea by microbial catalysis to form carbonate is a commonly studied example of MICP. In this study, Sporosarcina ureae, a ureolytic organism, was compared to other ureolytic and non-ureolytic organisms of Bacillus and Sporosarcina in the assessment of its ability to produce carbonates by ureolytic MICP for ground reinforcement. It was found that S. ureae grew optimally in alkaline (pH ~ 9.0) conditions which favoured MICP and could degrade urea (30.28 U/mL) at levels similar to S. pasteurii (32.76 U/mL), the model ureolytic MICP organism. When cells of S. ureae were concentrated (OD600 ~ 15–20) and mixed with cementation medium containing 0.5 M calcium chloride (CaCl2) and urea into a model sand, repeated treatments (3 × 24 h) were able to improve the confined direct shear strength of samples from 15.77 kPa to as much as 135.8 kPa. This was more than any other organism observed in the study. Imaging of the reinforced samples with scanning electron microscopy and energy dispersive spectroscopy confirmed the successful precipitation of calcium carbonate (CaCO3), organized as calcite, across sand particles by S. ureae. Treated samples were also tested experimentally according to model North American climatic conditions to understand the environmental durability of MICP. No significant (p

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Determining the effect of synthetic-based varnish and impregnation on wood’s shear strength under cold climate conditions

BioResources ◽

10.15376/biores.16.2.3377-3390 ◽

2021 ◽

Vol 16 (2) ◽

pp. 3377-3390

Author(s):

Şemsettin Doruk

Keyword(s):

Shear Strength ◽

Ambient Temperature ◽

Climatic Conditions ◽

Wood Products ◽

Cold Climate ◽

Wood Preservation ◽

Water Repellent ◽

Wood Preservatives ◽

Climate Conditions ◽

Parallel Direction

Glue shear strength and wood preservatives play an important role in the longevity of engineered wood products. The effects of factors such as UV rays, humidity, and temperature on wooden materials are known. However, it is not known what effects sub-zero temperatures have on wood material and how wood preservatives play a role. This study determined the effects of synthetic-based varnish and impregnation on shear strength in cold climatic conditions. Variables including glue type, ambient temperature, tree type, and process type were investigated. Wood laminate test samples were produced for this purpose, and water repellent impregnation material and synthetic-based varnish were used as wood preservatives. Experimental samples were kept in a cold air cabinet at (-15 °C) and (-30 °C) temperature for 90 days. Samples kept in different temperature conditions were subjected to a pull experiment in a parallel (//) direction to the fibers under static load. As the ambient temperature decreased, the shear strength decreased (-15 °C: 8,960 N/mm2 ,-30 °C: 8,025 N/mm2 ) . When the performance of wood preservation elements were examined, it was determined that the varnish process (8,875 N/mm2) and the impregnation process (8,691 N/mm2) were not statistically significant, at 12% and 10%, respectively.

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Ecological specificities of the interaction between animal breeding and climate changes, caused by greenhouse gas emissions

Agricultural science and practice ◽

10.15407/agrisp4.03.062 ◽

2017 ◽

Vol 4 (3) ◽

pp. 62-72

Author(s):

O. Zhukorsky ◽

O. Nykyforuk ◽

N. Boltyk

Keyword(s):

Greenhouse Gases ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Climatic Conditions ◽

Animal Breeding ◽

Gas Emissions ◽

Climate Conditions ◽

Emissions Inventory ◽

Theoretical Substantiation ◽

Global Problems

Aim. Proper development of animal breeding in the conditions of current global problems and the decrease of anthropogenic burden on environment due to greenhouse gas emissions, caused by animal breeding activity, require the study of interaction processes between animal breeding and external climatic conditions. Methods. The theoretical substantiation of the problem was performed based on scientifi c literature, statistical informa- tion of the UN Food and Agriculture Organization and the data of the National greenhouse gas emissions inventory in Ukraine. Theoretically possible emissions of greenhouse gases into atmosphere due to animal breeding in Ukraine and specifi c farms are calculated by the international methods using the statistical infor- mation about animal breeding in Ukraine and the economic-technological information of the activity of the investigated farms. Results. The interaction between the animal breeding production and weather-and-climate conditions of environment was analyzed. Possible vectors of activity for the industry, which promote global warming and negative processes, related to it, were determined. The main factors, affecting the formation of greenhouse gases from the activity of enterprises, aimed at animal breeding production, were characterized. Literature data, statistical data and calculations were used to analyze the role of animal breeding in the green- house gas emissions in global and national framework as well as at the level of specifi c farms with the consid- eration of individual specifi cities of these farms. Conclusions. Current global problems require clear balance between constant development of sustainable animal breeding and the decrease of the carbon footprint due to the activity of animal breeding.

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Relationship between Relative Maturity and Grain Yield of Maize (Zea mays L.) Hybrids in Northwest New Mexico for the 2003–2019 Period

Agriculture ◽

10.3390/agriculture10070290 ◽

2020 ◽

Vol 10 (7) ◽

pp. 290

Author(s):

Koffi Djaman ◽

Curtis Owen ◽

Margaret M. West ◽

Samuel Allen ◽

Komlan Koudahe ◽

...

Keyword(s):

New Mexico ◽

Grain Yield ◽

Sprinkler Irrigation ◽

Growing Season ◽

Climatic Conditions ◽

Agricultural Science ◽

Production Optimization ◽

Science Center ◽

Early Season ◽

Climate Conditions

The highly variable weather under changing climate conditions affects the establishment and the cutoff of crop growing season and exposes crops to failure if producers choose non-adapted relative maturity that matches the characteristics of the crop growing season. This study aimed to determine the relationship between maize hybrid relative maturity and the grain yield and determine the relative maturity range that will sustain maize production in northwest New Mexico (NM). Different relative maturity maize hybrids were grown at the Agricultural Science Center at Farmington ((Latitude 36.69° North, Longitude 108.31° West, elevation 1720 m) from 2003 to 2019 under sprinkler irrigation. A total of 343 hybrids were grouped as early and full season hybrids according to their relative maturity that ranged from 93 to 119 and 64 hybrids with unknown relative maturity. The crops were grown under optimal management condition with no stress of any kind. The results showed non-significant increase in grain yield in early season hybrids and non-significant decrease in grain yield with relative maturity in full season hybrids. The relative maturity range of 100–110 obtained reasonable high grain yields and could be considered under the northwestern New Mexico climatic conditions. However, more research should target the evaluation of different planting date coupled with plant population density to determine the planting window for the early season and full season hybrids for the production optimization and sustainability.

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The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

Scientific Reports ◽

10.1038/s41598-021-85712-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Charalampos Konstantinou ◽

Yuze Wang ◽

Giovanna Biscontin ◽

Kenichi Soga

Keyword(s):

Calcium Carbonate ◽

Calcium Chloride ◽

Urease Activity ◽

Coarse Sand ◽

Carbonate Precipitation ◽

Population Densities ◽

Carbonate Cements ◽

Microbially Induced Carbonate Precipitation

AbstractProtocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

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