Improvement of deltaic lateritic soil using river sand and cement for use as pavement construction material

This study examined the effect of mechanical and chemical improvement on deltaic lateritic soils in Warri East in Delta State, Nigeria. Mechanical stabilization was carried out by adding river sand to the natural soil in various proportions, while chemical stabilization was carried out using cement and a mixture of cement and sand. Compaction and CBR tests were conducted on the natural soil before and after stabilization. From the results obtained, it was seen that the mechanical stabilization method improved the strength properties of the soil making it suitable for use as subbase materials, though not as much as the chemical stabilization method or the mixed method of stabilization. It was concluded that using a combination of cement and sand as a stabilizing agent for deltaic lateritic soils can lead to significant reduction in the amount of cement required for soil stabilization thus saving costs.

Plectin-Mediated Intermediate Filament Functions: Why Isoforms Matter

This essay focuses on the role of plectin and its various isoforms in mediating intermediate filament (IF) network functions. It is based on previous studies that provided comprehensive evidence for a concept where plectin acts as an IF recruiter, and plectin-mediated IF networking and anchoring are key elements in IF function execution. Here, plectin’s global role as modulator of IF functionality is viewed from different perspectives, including the mechanical stabilization of IF networks and their docking platforms, contribution to cellular viscoelasticity and mechanotransduction, compartmentalization and control of the actomyosin machinery, connections to the microtubule system, and mechanisms and specificity of isoform targeting. Arguments for IF networks and plectin acting as mutually dependent partners are also given. Lastly, a working model is presented that describes a unifying mechanism underlying how plectin–IF networks mechanically control and propagate actomyosin-generated forces, affect microtubule dynamics, and contribute to mechanotransduction.

Non-aqueous cross hydrolysis: an epoxide-free sol-gel route toward highly porous alumina monoliths

Highly porous alumina monoliths can be fabricated by simultaneous hydrolysis of aluminum alkoxides and salts as homonuclear precursors. The use of carcinogenic epoxides can thus be avoided. In this novel approach, no water is added to the system but hydrolysis is induced by the crystal water of the aluminum salt. Mechanical stabilization and significantly increased porosity values can be achieved when the sol-gel synthesis is performed in an autoclave.

Analysis of microvascular thrombus mechanobiology with a novel particle-based model

Platelet accumulation at the site of vascular injury is regulated by soluble platelet agonists, which induce various types of platelet responses, including integrin activation and granule secretion. The interplay between local biochemical cues, mechanical interactions between platelets and macroscopic thrombus dynamics is poorly understood. Here we describe a novel computational model of microvascular thrombus formation for detailed analysis of thrombus mechanics. Adopting a previously developed two-dimensional particle-based model focused on the thrombus shell formation, we revise it to introduce platelet agonists. Blood flow is simulated via computational fluid dynamics approach. In order to model soluble platelet activators, we apply Langevin dynamics to a large number of non-dimensional virtual particles. Taking advantage of the available data on platelet dense granule secretion kinetics, we model platelet degranulation as a stochastic agonist-dependent process. The new model qualitatively reproduces enhanced thrombus formation due to granule secretion in line with in vivo findings and provides a mechanism for thrombin confinement at the early stages of aggregate formation. Our calculations also predict that release of dense granules results in additional mechanical stabilization of the inner layers of the thrombus. Distribution of the inter-platelet forces throughout the aggregate reveals multiple weak spots in the outer regions of thrombus, which are expected to result in mechanical disruptions at the later stages of thrombus formation.

MAIN ENGINEERINGSPROPRETIES OF STABILISED EARTH BLOCK BRICKS FORMULATED WITH SOILS FROM NDJAMENA-CHAD

The most used bricks in house building in NDjamena, city of Chad which is situated in semi dry arid area with 600 millimeters of pluviometry per year and 50 °C as highest temperature, are raw clay bricks, terracotta bricks or bricks in ciment block. The raw clay bricks have strong sensibility in water and weak resistance to compression. The terracotta and cement block bricks have high thermal conductivity contrary to the adobe and their manufacturingcontribute to destroy the environment. The aim of this paper is to search Stabilised Earth Block (SEB) bricks whichare made with clay, sand and few percent of cement and respond to climatic, environmental and economic constraints. Therefore, some bricks are built in mixing differentspercents of sand and clay (M1 : 40% sand and 60% clay, M2 : 50% sand and 50% clay, M3 : 60% sand and 40% clay, M4 : 70% sand and 30% clay, M5 : 30% sand, 30% slime and 40% clay, and M6 : 40 % sand, 20% slime and 40% clay) for obtaining physical stabilizationand adding 8%, 10% or 15% of cementin each type of brick for the chemical stabilization. Theuse of moulding press machine grants already the mechanical stabilization to these bricks. Proctor test has allowedto retain M1, M3 and M4 for searching the best values of the rate absorption of water by capillarity , the resistance in compression and the thermal conductivity of these bricks. The results of tests show bricks M3 with 10% of cement have the good values 21,23 g.cm-².min-1/2 of rate absorption, 3,82 MPa of resistance in compression and 0,5W.m-1.°K-1 as thermal conductivity.

PERUBAHAN POTENSI MENGEMBANG TANAH EKSPANSIF YANG DISTABILISASI SECARA FISIS DAN MEKANIS

Expansive soil has a high swelling and shrinkage ability which can damage the buildings above it. Glagahagung Village, Purwoharjo District, Banyuwangi Regency is one of the areas suspected of having this type of soil. Residents often experience problems in their residential buildings every year, such as cracks in floors, walls, columns, and beams. Several methods can be used to improve expansive soil, including physical and mechanical stabilization. In this study, lime and cement were used as physical stabilizers. On the other hand, sand is used as a mechanical stabilizer. Physical and mechanical parameters will be observed in the stabilization process. Based on the three stabilizers, a 5% cement mixture can be the best alternative. Cement stabilizers can increase the maximum dry volume weight, reduce the rate of soil swelling, and change natural soils' classification from high plasticity clay to silty sand.