Indian Institute of Technology Indore

About: Indian Institute of Technology Indore is a education organization based out in Indore, Madhya Pradesh, India. It is known for research contribution in the topics: Computer science & Chemistry. The organization has 1606 authors who have published 4803 publications receiving 66500 citations.

Rock-like behavior of biocemented sand treated under non-sterile environment and various treatment conditions

Abstract: Microbially induced calcite precipitation (MICP) is a recently developed technique for microbiological ground improvement that has been applied for mitigating various geotechnical challenges. However, the major challenges, such as calcite precipitation uniformity, presence of different bacteria, cementation solution optimization for cost reduction, and implementation under non-sterile and uncontrolled field environment are still not fully explored and require detailed investigation before field application. This study aims to address these challenges of MICP to improve the geotechnical properties of sandy soils. Several series of experiments were conducted using poorly graded Narmada River (India) sand, which were subjected to various biotreatment schemes and tested for unconfined compressive strength (UCS), split tensile strength (STS), ultrasonic pulse velocity (UPV), hydraulic conductivity (after 6 d, 12 d, and 18 d of treatment), and calcite content. The microstructure of sand was examined through a scanning electron microscope (SEM). Initially, the sand was individually augmented with two non-pathogenic bacterial strains, i.e. Sporosarcina (S.) pasteurii and Bacillus (B.) sphaericus. The stopped-flow injection method was adopted to provide cementation solutions at three different durations (treatment cycle) of 12 h, 24 h, and 48 h and three different pore volumes (PVs) of 1, 0.75, and 0.5. The pore volume here refers to the porosity which is expressed as a ratio, i.e. a porosity of 50% was used as 0.5. The results showed rock-like behaviors of biocemented sand with the UCS, STS, and UPV enhancement up to 2333 kPa, 437 kPa, and 2670 m/s, respectively. The hydraulic conductivity reduction of 96.6% was achieved by 12% of calcite formation after 18 d of treatment using Sporosarcina pasteurii, 12-h treatment cycle, and one pore volume of cementation media in each cycle. Overall, a 24-h treatment cycle and 0.5-pore volume cementation solution were found to be the optimal treatment which was effective and economical to achieve heavily cemented, rock-type biocemented sand using both bacteria.

Prediction of soil organic carbon stock using digital mapping approach in humid India

Abstract: There is a need of information on soil organic carbon data for global environmental management and food security. However, the difficulty lies in obtaining soil carbon data, especially in fragile mountainous regions like Northeast India which is complex in nature and difficult to access. The present study aims to model the distribution of soil carbon stock using digital mapping approach, to predict and generate continuous spatially explicit soil carbon map in Northeast India. Firstly, negative exponential depth function has been used to fit the vertical distribution of soil carbon data, and then Random Forest model has been trained and tuned to predict the parameters of the exponential function using climate data and satellite images. The obtained parameters were finally interpolated using ordinary Kriging method and spatial distribution map across the study area has been generated. Results indicate that the negative exponential function fits the data accurately with 94% of data having R2 > 0.7. Land use and topographic factors particularly elevation was found to have the most influence on SOC distribution in Northeast India. The findings from this study indicate good results for the application of this technique to predict and monitor soil carbon of the study area as a function of topographic factors and changes in land use and climate variables. The obtained results can also be connected to global carbon models to improve the understanding of carbon dynamics.

Astrocyte-induced positive integrated information in neuron-astrocyte ensembles.

Abstract: Integrated information is a quantitative measure from information theory of how tightly all parts of a system are interconnected in terms of information exchange. In this study we show that astrocytes, playing an important role in regulation of information transmission between neurons, may contribute to a generation of positive integrated information in neuronal ensembles. Analytically and numerically we show that the presence of astrocytic regulation of neurotransmission may be essential for this information attribute in neuroastrocytic ensembles. Moreover, the proposed ``spiking-bursting'' mechanism of generating positive integrated information is shown to be generic and not limited to neuron-astrocyte networks and is given a complete analytic description.