A New Type of Cemented Sand-Gravel (CSG) Mixtures for Water-Tightening of Hardfill Dams

This paper aims to achieve a specific type of cemented sand-gravel mixtures with low permeability to implement in the impervious zone of hardfill dams. To this end, various mixtures are prepared by blending two native soils of sand and gravel with different amounts of kaolinite or bentonite additives in presence of various cement content. The compaction properties, uniaxial compressive strength, permeability and scanning electron microscope (SEM) images of mixtures are measured. According to the results, the cemented mixture containing 10% of kaolinite additive regardless of native soil type exhibits the maximum strength. However, the bentonite disturbs the cement hydration in the mixture, and the strength of mixtures especially with high cement content decreases with increasing the bentonite content. The permeability of mixtures is related to the amount of cement and fine additive in the mixture. The permeability of both cemented sand and gravel mixtures decreases with increasing the bentonite additive. However, the kaolinite additive has a limited influence on the permeability of cemented gravel mixtures. The lowest permeability is achieved in the mixture involving the higher amount of bentonite (with a weight ratio of 30%) in presence of adequate cement.

Compressional Physics of Binary Mixture of Dried Andrographis paniculata and Moringa oleifera Leaves

Traditionally, the leafy part of Andrographis paniculata and Moringa oleifera have been widely reported to manage hypertension. Investigation of its pharmacological actions justifies its use. As part of formulation studies to standardize them, this study focused on their compaction and compression properties. Compacts equivalent to 250 mg of A. paniculata and M. oleifera were produced by compressing powders and granules at various compression pressure. Results show that M. oleifera met the WHO limit for ash values. Relative density values for granulated batches were higher, while their moisture content values were lower when compared to those of direct compression. The result from Heckel plots shows that batches deform mainly by plastic flow. For Kawakita plots, values of 1/b show that batches containing microcrystalline cellulose were less cohesive. The plot of tensile strength signifies that granulated batches achieved maximum crushing strength faster at low pressure. Formulations containing maize starch were shown to have higher percent porosity, and granulated batches gave higher values for apparent density-pressure relationship and lower friability values. Tablets produced by the wet granulation method showed better compression and compaction properties than those formulated by direct compression.

Experimental Study on Stabilisation of Clayey Soil Using Cement and Bagasse Ash

In order for the foundation of building to be strong, the soil around it plays a critical role. So, researcher or engineer should have thorough knowledge about the factors affecting behaviour of soil which can be altered by the process of soil stabilisation. This study aims to investigate the applicability of SCBA (Sugarcane Bagasse Ash) to stabilize the clayey soil. Sugar factories produce waste after extraction of sugarcane gets brunt and the ash, hence produced is known as bagasse ash. Soil is treated with partial replacement of cement (3%, 6%, 9% and 12%) and with bagasse ash (2%, 4%, 6%and 8%). A total of 45 specimens were prepared in this study. Later those test specimens were evaluated for compaction properties. The results found after thorough study was that there was increase in the compaction properties with percentage increase in Sugarcane Bagasse Ash up to certain limit.

Characteristics of unfired soil blocks stabilized with industrial waste and agricultural waste

The problem of pollution is on daily rise and environment protection is becoming challengeable task due to production of fired bricks and improper disposal of waste materials. This experimental investigation is conducted on unfired compacted soil block stabilized with waste materials. The waste materials utilized in this investigation were paddy straw fiber, sugarcane bagasse ash and marble dust because of their improper disposal and burning of paddy straw is one of them. Marble dust was put on at distinct percentages in the span of 25% to 35%, bagasse ash and paddy straw fibers (75mm length) were also added in varied %age. Experiments were conducted on the blocks to determine the compaction properties and compressive strength of the blocks. The outcome of this experimentation determined that the light weight unfired admixed soil block is achievable with optimum amount of waste materials. Also, inclusion of marble dust in soil block admixed with bagasse ash and paddy straw fiber increases the compressive strength.

Structural and functional characterization of DdrC, a novel DNA damage-induced nucleoid associated protein involved in DNA compaction

Deinococcus radiodurans is a spherical bacterium well-known for its outstanding resistance to DNA-damaging agents. Exposure to such agents leads to drastic changes in the transcriptome of D. radiodurans. In particular, four Deinococcus-specific genes, known as DNA Damage Response genes, are strongly up-regulated and have been shown to contribute to the resistance phenotype of D. radiodurans. One of these, DdrC, is expressed shortly after exposure to γ-radiation and is rapidly recruited to the nucleoid. In vitro, DdrC has been shown to compact circular DNA, circularize linear DNA, anneal complementary DNA strands and protect DNA from nucleases. To shed light on the possible functions of DdrC in D. radiodurans, we determined the crystal structure of the domain-swapped DdrC dimer at a resolution of 2.2 Å and further characterized its DNA binding and compaction properties. Notably, we show that DdrC bears two asymmetric DNA binding sites located on either side of the dimer and can modulate the topology and level of compaction of circular DNA. These findings suggest that DdrC may be a DNA damage-induced nucleoid-associated protein that enhances nucleoid compaction to limit the dispersion of the fragmented genome and facilitate DNA repair after exposure to severe DNA damaging conditions.

Preliminary Characterization of Co-processed Excipients of Okra (Abelmoschus esculentus) Mucilage and Pregelatinized Potato Starch

Background: Okra mucilage is highly viscous with good binding properties in tablets. Pregelatinized starches have significantly improved flow properties but produce tablets of poor mechanical strength.Objective: Preliminary evaluation of co-processed excipients of Okra mucilage and pregelatinized potato starch as directly-compressible excipients.Methods: Polymers were characterized for morphology (SEM), crystallinity (FT-IR) and flow properties. Coprocessed excipients were developed with Okra mucilage and pregelatinized potato starch at different ratios of starch: mucilage (95:5, 90:10, 85:15, 80:20, 70:30), using the co-fusion method. The flow, packing and compaction properties of the co-processed excipients were evaluated using density measurements, angle of repose, angle of internal friction, Kawakita model, consolidation index (C) and consolidation rate (K).Results: Larger agglomerates of the co-processed excipients indicated formation of a new polymer. FT-IR spectra showed retention of all the major peaks of individual polymers. Okra mucilage imparted swelling while starch improved flow in the co-processed excipients (Hausner’s ratio 1.12-1.20). Values from Kawakita plots revealedcohesiveness and compressibility were imparted to the co-processed excipients (a = 0.300–0.329; b = 0.078–0.361) suggesting good compactibility. Consolidation index and rate were observed to increase with Okra mucilage content, implying improved rate of packing as well as enhanced flow (C = 0.566-1.389; K = 0.123-0.424). The batch containing starch: mucilage 70:30 gave the best properties of good flow, cohesiveness and compactibility, essential parameters required in directly-compressible excipients.Conclusion: The co-processed excipients of Okra mucilage and pregelatinized potato starch could therefore be used as excipients for direct compression in tablet formulations.