Search

Due to urban sprawl, the demand for land has increased for the purpose of construction. It is unlikely that soil available at different construction sites will be suitable for designed structures. For improving the load-bearing capacity of the soil, different soil binders are used, which are present in distinct states. In this review, the authors have collected details about various binders, which are generally used in the soil stabilization, and their effect as a binding agent on the soil. In this article, the authors tried to review different traditional binders. After studying various research articles, the authors found that lime, ground-granulated blast slag (GGBS) polypropylene, polyurethane grouting, and asphalt mix are frequently used binders. However, the authors also gathered information about the negative environmental impact of these traditional soil binders, which led to the need for alternatives to these commonly used soil binders. To diminish this issue, different alternate hydraulic and non-hydraulic binders are discussed. The authors found alternatives to cement and lime with the alkali-activated material consisting of Na2O and silica modulus and belite-calcium sulfoaluminate ferrite, which is also known as “Aether™.” According to the research, both alternatives emit 20–30% less CO2 into the environment and also improve the compressive strength of the soil. The various studies promotes bitumen modification. Incorporating 20-mesh crumb rubber and bio-oil into the bitumen reduces its viscosity and improves its fatigue value. When waste oil is mixed with asphalt, it revitalizes the bitumen, improves fatigue resistance, and increases compressive strength. The soil particles treated by Eko soil are held together by enzymes, which give them the same strength as cement. Apart from that, low-carbon binders such as basic oxygen furnace slag, bamboo fiber, enzyme-based soil treatment, zebu manure for stabilization, and lignin-contained biofuels and coproducts are discussed. Replacing these traditional binders helps with energy savings. All waste products are recycled, and energy is saved by not manufacturing traditional binders. Additionally, energy is saved, which is required to avoid the detrimental effects of these conventional binders, making them energy-efficient alternate binders. The authors also summarize the methods used, impacts, and changes that occur in soil properties after using substitutes in place of traditional binders. From the review, the authors determined that different binders have various properties in terms of chemical and physical compositions, and they show different variations in terms of strength when added to soil with low bearing capacity or poor stability.

Despite the extensive application of calcium-based materials in Solidification/Stabilization (S/S) of Heavy Metal (HM) contaminated soils, it may suffer from some technical and environmental constraints including retard the hydration reactions and CO2 footprint. Hence, in this paper, the applicability of Basic Oxygen Furnace Slag (BOFS) along with lime (L-BOFS) and cement (C-BOFS) binders in the S/S process was investigated. To this end, various contents of stabilizers up to 30% were added to a clayey soil specimen containing different concentrations of zinc, and then, a series of micro- and macro-level experiments containing Atomic Absorption (AA), Unconfined Compressive Strength (UCS), pH, and Toxicity Characteristic Leaching Procedure (TCLP) were evaluated at different curing periods. The results showed that BOFS reduces the primarily bio-availability (absorption capability) of contaminant, but the acidic attack would cause HM desorption from the soil. So that the addition of 30% BOFS can lead to stabilization of the clayey soil contaminated with high contents of Zn after a 28-day curing. However, the incorporation of cement and lime into the BOFS proposes a successful means of enhancing the UCS of the Zn-contaminated kaolin clay and offers outstanding immobilization of Zn. Furthermore, L-BOFS samples revealed lower leachability as well as better cementation structure bonding of the S/S matrix compared to the C-BOFS as confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. It is worth noting that the UCS value of the 30 cmol/kg Zn-contaminated soil with 20% BOFS after 28 days of curing at 45 °C increased by about 50% compared to that of the sample cured at 20 °C. [ABSTRACT FROM AUTHOR]

β-C 2 S is the main active mineral component in Basic Oxygen Furnace slag (BOFS), while the content of β-C 2 S in BOFS is usually limited and fluctuated, which hindered the improvement of CO 2 capture during carbonation. To enhance the carbonation reactivity of BOFS products, different ratio of γ-C 2 S was blended with BOFS powder and carbonated, followed by hydration curing. XRD and TGA analysis were used to determine the mineral composition of each blending group after carbonation. SEM analysis was applied to observe the microstructure, and the MIP method was used to analyze the pore size structure. The results show that the carbonation degree and compressive strength of BOFS cubes were increased by the addition of γ-C 2 S. With 20 wt% blending of γ-C 2 S, the carbonated BOFS obtained the optimum increasement of carbonation degree and compressive strength, reaching 39.3% and 42.4 MPa, respectively. However, the subsequent hydration reactivity of BOFS was inhibited when blended with 20 wt% of γ-C 2 S. Despite this, the increased poorly crystalline CaCO 3 filled the system and densified the matrix, contributing to a 17.9% increase in compressive strength of SH20 after 56 days of hydration curing. • For SS20 group, the optimum results of carbonation degree (39.3%) and compressive strength (42.4 MPa) can be obtained. • As excessively blending of γ-C 2 S, the increased generation of poorly crystalline CaCO 3 may reduce the compressive strength. • Later hydration of SS20 was inhibited, while the formation of the denser microstructure enhanced its compressive strength. [ABSTRACT FROM AUTHOR]

Failure of facial prominence fusion causes cleft lip and palate (CL/P), a common human birth defect. Several potential mechanisms can be envisioned that would result in CL/P, including failure of prominence growth and/or alignment as well as a failure of fusion of the juxtaposed epithelial seams. Here, using geometric morphometrics, we analyzed facial outgrowth and shape change over time in a novel mouse model exhibiting fully penetrant bilateral CL/P. This robust model is based upon mutations in Tfap2a, the gene encoding transcription factor AP-2α, which has been implicated in both syndromic and non-syndromic human CL/P. Our findings indicate that aberrant morphology and subsequent misalignment of the facial prominences underlies the inability of the mutant prominences to fuse. Exencephaly also occured in some of the Tfap2a mutants and we observed additional morphometric differences that indicate an influence of neural tube closure defects on facial shape. Molecular analysis of the CL/P model indicates that Fgf signaling is misregulated in the face, and that reducing Fgf8 gene dosage can attenuate the clefting pathology by generating compensatory changes. Furthermore, mutations in either Tfap2a or Fgf8 increase variance in facial shape, but the combination of these mutations restores variance to normal levels. The alterations in variance provide a potential mechanistic link between clefting and the evolution and diversity of facial morphology. Overall, our findings suggest that CL/P can result from small gene-expression changes that alter the shape of the facial prominences and uncouple their coordinated morphogenesis, which is necessary for normal fusion.

Cranial neural crest development is governed by positional gene regulatory networks (GRNs). Fine-tuning of the GRN components underly facial shape variation, yet how those in the midface are connected and activated remain poorly understood. Here, we show that concerted inactivation of Tfap2a and Tfap2b in the murine neural crest even during the late migratory phase results in a midfacial cleft and skeletal abnormalities. Bulk and single-cell RNA-seq profiling reveal that loss of both Tfap2 members dysregulated numerous midface GRN components involved in midface fusion, patterning, and differentiation. Notably, Alx1/3/4 ( Alx ) transcript levels are reduced, while ChIP-seq analyses suggest TFAP2 directly and positively regulates Alx gene expression. TFAP2 and ALX co-expression in midfacial neural crest cells of both mouse and zebrafish further implies conservation of this regulatory axis across vertebrates. Consistent with this notion, tfap2a mutant zebrafish present abnormal alx3 expression patterns, and the two genes display a genetic interaction in this species. Together, these data demonstrate a critical role for TFAP2 in regulating vertebrate midfacial development in part through ALX transcription factor gene expression., Competing Interests: Competing Interest Statement: The authors declare no conflict of interest.

In the present study, industrial wastes such as Granulated Blast Furnace Slag (GBFS) and Basic Oxygen Furnace Slag (BOFS) activated with calcium oxide (CaO) and medium reactive magnesia (MgO) are used for chemical stabilization of a soft clay. This environmentally friendly approach can eliminate the hazards associated with improper waste disposal and reduce greenhouse gas emissions generated by cement production. To this end, various amounts of additives (ranging from 2.5 to 20%) with the activator:slag ratio of 1:3 are added to kaolinite clay and cured at two temperatures of 20 and 45°C. A series of laboratory tests, including pH, Electrical Conductivity (EC), one-dimensional consolidation, Unconfined Compressive Strength (UCS), are conducted on the stabilized samples. The increasing temperature causes a faster formation of cementitious products and a higher UCS value, as confirmed by the SEM micrographs and XRD analysis, particularly in the case of MgO-BOFS (MB) and CaO-BOFS (CB) samples with the UCS values of 4 and 4.7 MPa after 90 days of curing, respectively. Furthermore, the MB- and CB-stabilized clay samples show a better compressibility characteristic compared to the MgO-GBFS (MG) and CaO-GBFS (CG) blends. To further enhance the activity of the additives and to prepare a slag-clay based geopolymers, two types of alkaline solutions at various Na 2 SiO 3 :NaOH ratios are added to the mixtures at the final step. In addition, the energy absorption capacity (E u) and the secant modulus (E 50) of the optimum blends are determined to assess the toughness and stiffness of the samples. The results indicate that the UCS values of the MB and CB samples increase up to 7.41 MPa and 8.44 MPa after 90 days of curing, respectively, when the Na 2 SiO 3 :NaOH ratio is 80:20. Generally, the use of slag-clay based geopolymers, particularly BOFS, is very effective to address the problems associated with the soft soil and the optimum mixtures are successful in decreasing settlements and enhancing compressive strength of the soft soil, which can be considered for use as a pavement base material. • Soft clays can be satisfactorily treated when GBFS and BOFS are activated by CaO and MgO. • Increasing temperature can give rise to the faster formation of cementitious products, particularly in MB and CB samples. • The clay-BOFS based geopolymers show the highest increase on the UCSs of the samples in the Na 2 SiO3:NaOH ratio of 80:20. • The MB- and CB-treated samples represent a better compressibility compared to the MG and CG treatment. [ABSTRACT FROM AUTHOR]

The pathological consequences of structural variants disrupting 3D genome organization can be difficult to elucidate in vivo due to differences in gene dosage sensitivity between mice and humans. This is illustrated by branchiooculofacial syndrome (BOFS), a rare congenital disorder caused by heterozygous mutations within TFAP2A, a neural crest regulator for which humans, but not mice, are haploinsufficient. Here, we present a BOFS patient carrying a heterozygous inversion with one breakpoint located within a topologically associating domain (TAD) containing enhancers essential for TFAP2A expression in human neural crest cells (hNCCs). Using patient-specific hiPSCs, we show that, although the inversion shuffles the TFAP2A hNCC enhancers with novel genes within the same TAD, this does not result in enhancer adoption. Instead, the inversion disconnects one TFAP2A allele from its cognate enhancers, leading to monoallelic and haploinsufficient TFAP2A expression in patient hNCCs. Our work illustrates the power of hiPSC differentiation to unveil long-range pathomechanisms., (Copyright © 2019 Elsevier Inc. All rights reserved.)