Microbiological, Environmental, and Compositional Factors in Efficacy of MICP Treatment in Clayey Soils

Expansive clayey soils can cause billions of dollars of damage to infrastructure such as roads and foundations annually. Researchers propose many techniques (e.g., pre-wetting, soil replacement, and chemical stabilization) to improve the mechanical properties of these soils; however, some of these methods are impractical in certain situations, and are unsustainable in others due to the economic and environmental impacts. One possible method for enhancing soil’s mechanical properties is Microbial Induced Calcium Carbonate Precipitation (MICP). This environmentally friendly technique is a biological process where microbes play a key role in precipitating calcium carbonate. This precipitating calcium carbonate can coat soil particles and cement the soil matrix, thereby reducing the swelling potential. MICP is a complicated process. Many environmental variables such as the soil type, composition, chemistry, and microbial communities present in the soil control the rates and amounts of carbonate precipitation. The application of MICP in clay soils is an active area of research, however due to the complex nature of MICP and the clayey soils, not all the parameters impacting MICP have been comprehensively or systematically described. Moreover, the MICP performance of the soils tested in other studies varied considerably depending on the soil types. This leads to a fundamental question: What geochemical and environmental factors influence MICP performance and how these factors can be used as predictors of the MICP effectiveness in expansive soils? Answering this question is essential in the development of optimization strategies capable of enhancing the competitive advantages of MICP over traditional soil improvement methods; Moreover, understanding these factors prior to applying MICP to the soils can be a promising key for saving time, energy, and money. To determine the factors controlling MICP effectiveness in expansive soils, we performed a series of physical, chemical, microbiological, and compositional experiments in clayey soils collected from different geographical locations. To determine how soil’s clay content and gradation impacts calcium carbonate (CaCO3) precipitation, several artificial clay/sand mixes were prepared and examined for urease activity and calcite precipitation. The test results showed that clay has more urease activity and precipitation calcite than sand despite the two having similar relative populations of indigenous ureolytic bacteria. To determine the role of microbial communities in CaCO3 precipitation, we measured CaCO3 precipitation using Rapid Carbonate Analysis (RCA) and examined its correlation with soil ureolytic bacteria determined through 16SrRNA DNA sequencing. These observations show MICP treatment can increase ureolytic strains in all soils. However, this increase is not correlated with calcium carbonate precipitation in soils. Additional testing on 6 soil samples from multiple geographical locations showed that compositional characteristics such as Cation Exchange Capacity (CAC) and Specific Surface Area (SSA) have a significant positive correlation with the efficiency of MICP. The overall results suggest that the performance of MICP treatment is better in clayey soils compared to other non-clayey soils. Moreover, the results suggest that compositional properties such as CEC and SSA of the soil could be the reasons for the observed differences in CaCO3 precipitation in soils. Therefore, it is possible that CEC and SSA can be used as indicators of the MICP effectiveness prior to any MICP treatment in soils

Studying the Relationship Between Indigenous Microbial Communities, Urease Activity, and Calcite Precipitation in Artificial Mixes of Clay and Sand

Microbial-induced calcium carbonate precipitation (MICP) is evolving as a new method of improving the mechanical properties of soil. This environmentally friendly technique is a bio-geo-chemical process where microbes play a key role in increasing soil strength through precipitating calcium carbonate. Past studies at Boise State University have indicated that MICP via bio-stimulation could be a viable alternative for expansive clayey soil treatments. However, these studies raised a new question about the relationship between soil composition, urease activity, and calcite precipitation. To answer this question, batch studies were conducted using autoclaved-sterilized sand mixed with different percentages of non-sterile natural clay and tested for urease activity. Moreover, to investigate the difference in urease activity between sand and clay bacterial communities, experiments were repeated on samples with different amounts of non-sterile sand and autoclaved-sterilized clay. MICP-treated clay/sand mixes were then evaluated for calcite precipitation. Our results showed that soil mixes with higher clay content have more urease activity and higher levels of calcite precipitation for both sand-autoclaved and clay-autoclaved soil mixes. Test results indicate that urease activity could potentially be used as an indicator of MICP performance in different soil compositions

Anti-atherogenic potential of jujube, saffron and barberry: anti-diabetic and antioxidant actions

Atherogenic dyslipidemia, characterized by an increased level of lipoprotein (a) and a decreased level of adiponectin, is a major risk factor for cardiovascular diseases in diabetic patients. To reduce cardiovascular risk in diabetic patients, use of agents with antidiabetic and anti-atherogenic potential is required. Using an animal model of diabetes, we investigated the antiatherogenic potential of extracts of three medicinal plants: jujube, barberry, and saffron. For this, serum level of fasting blood glucose, lipid profile, malondialdehyde, total antioxidant capacity, adiponectin and lipoprotein (a) in diabetic control and extract treated groups were measured. Statistical analysis of measurements showed that serum levels of fasting blood glucose, triglyceride, and VLDL decreased significantly (P < 0.05) in all treated groups. Treatment with all extracts reduced lipid peroxidation and increased antioxidant capacity of the experimental diabetic groups. Serum adiponectin levels increased in all treated groups, whereas lipoprotein (a) levels decreased, most markedly when treated with jujube extract. Jujube, saffron, and barberry extracts are beneficial in ameliorating oxidative stress and atherogenic risk of diabetic rats. This highlights the benefits of further investigating the cardio-protective potential of medicinal plant extracts and evaluating their usefulness as cardio protective agents in clinical practice

Evaluation of the effects of pulsed wave LLLT on tibial diaphysis in two rat models of experimental osteoporosis, as examined by stereological and real-time PCR gene expression analyses

Osteoporosis (OP) and osteoporotic fracture are major public health issues for society; the burden for the affected individual is also high. Previous studies have shown that pulsed wave low-level laser therapy (PW LLLT) has osteogenic effects. This study intended to evaluate the impacts of PW LLLT on the cortical bone of osteoporotic rats’ tibias in two experimental models, ovariectomized and dexamethasone-treated. We divided the rats into four ovariectomized induced OP (OVX-d) and four dexamethasone-treated (glucocorticoid-induced OP, GIOP) groups. A healthy (H) group of rats was considered for baseline evaluations. At 14 weeks following ovariectomy, we subdivided the OVX-d rats into the following groups: (i) control which had OP, (ii) OVX-d rats treated with alendronate (1 mg/kg), (iii) OVX-d rats treated with LLLT, and (iv) OVX-d rats treated with alendronate and PW LLLT. The remaining rats received dexamethasone over a 5-week period and were also subdivided into four groups: (i) control rats treated with intramuscular (i.m.) injections of distilled water (vehicle), (ii) rats treated with subcutaneous alendronate injections (1 mg/kg), (iii) laser-treated rats, and (iv) rats simultaneously treated with laser and alendronate. The rats received alendronate for 30 days and underwent PW LLLT (890 nm, 80 Hz, 0.972 J/cm2) three times per week during 8 weeks. Then, the right tibias were extracted and underwent a stereological analysis of histological parameters and real-time polymerase chain reaction (RT-PCR). A significant increase in cortical bone volume (mm3) existed in all study groups compared to the healthy rats. There were significant decreases in trabecular bone volume (mm3) in all study groups compared to the group of healthy rats. The control rats with OP and rats from the vehicle group showed significantly increased osteoclast numbers compared to most other groups. Alendronate significantly decreased osteoclast numbers in osteoporotic rats. Concurrent treatments (compounded by PW LLLT and alendronate) produce the same effect on osteoporotic bone. © 2016, Springer-Verlag London

Improved couple satisfaction and communication with marriage and relationship programs: are there gender differences?—a systematic review and meta-analysis

Abstract Background The aspects of marriage and relationship and their effect on couples’ satisfaction are essential and critical aspects to be explored in this globalized and contemporary world. Since there are no reported meta-analysis and systematic reviews conducted in the last two decades in this area, we aimed to investigate the effect of marriage and relationship programs (MRP) on couples’ relationship satisfaction (CRS) and couples’ relationship communication (CRC) and also to determine the gender differences if any. Method In this systematic review and meta-analysis, the randomized clinical trials (RCTs) published between 2000 and July 26, 2019, were retrieved from several online electronic databases such as Medline, Embase, ProQuest, and Cochrane Library. Inclusion and exclusion criteria were developed using the PICO (Population, Intervention, Comparison, Outcome) framework of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The mean differences (MDs) and 95% confidence intervals (CIs) were calculated. The reported summary statistics were calculated as random effects models based on the heterogeneity between the studies model. Funnel plots and the Egger regression test was used to confirm the presence of any publication bias. Results Of the total 12 intervention studies included, five (5) are education/communication skills programs, three (3) enrichment programs, and four (4) therapy programs. The impact of these programs was investigated on CRS and CRC. Therapy programs had a larger effect than other programs (pooled MD: 0.53 (95% CI = 0.35 to 0.71, I2 = 71.5% p = 0.0001) and had a larger effect size on wives (pooled MD: 0.53 (95% CI 0.25 to 0.80, I2 = 74.1% p = 0.0001) than husbands RS (pooled MD: 0.26 (95% CI 0.25 to 0.76, I2 = 72.4% p = 0.0001). In RC (relationship communication) area, the Enhancement programs showed the small to large effect on CRC (pooled MD: 1.31 (95% CI = 0.13 to 2.50, I2 = 94.7% p = 0.0001)) and educational programs showed small to medium effect (pooled MD: 0.32 (95% CI = 0.13 to 0.50, I2 = 74.5% p = 0.0001) on women and no effect on men. Conclusion Due to the high effect of the therapy programs on CRS and enhancement program on CRC in the current meta-analysis, the priority of their utilizations in interventions, especially by psychologists and mental health professionals, should be emphasized. Therefore, mental health planning in communities to develop MRP and care for couples’ health should be given special attention to men’s health. Due to the high heterogeneity of the results and with scanty literature in this specific domain, we are uncertain about their actual effect. However, well-designed RCTs with a larger sample size would be beneficial in closely examining the effect of MRPs on CRS and CRC