STUDIES ON GRAVITY BLIND BACKFILLING FOR GROUND STABILIZATION ABOVE ABANDONED UNDERGROUND MINES

Samir Kumar Pal,Subir Kumar Mukhopadhyay,Susmita Panda,Anup Kumar Tripathi 한국암반공학회 2010 한국암반공학회 학술대회 및 세미나 자료집 Vol.2010 No.10

Blind hydraulic backfilling is a commonly adopted technique for subsidence control of the strata over unapproachable water-logged underground excavations, particularly in coal mining. There are three variants in blind backfilling, viz., the hydro-pneumatic, the pumped-slurry, and the simple gravity backfilling. This paper mainly describes investigations carried out on gravity blind backfilling technique on the experimental model as well as in the field, since it is the simplest and the easiest among the three methods which can be used for stabilization of ground over old abandoned water-logged mines. On examination of the filling process, it was revealed that the basic process of filling occurs by sand transportation along one or more meandering channels. In the study, the relative influence of sand, water and air flow rates on the area of filling from a single inlet point and the hydraulic pressure loss per unit length were studied in detail. Inlet pressure variation with time, known as pressure signature, have been used to study the changes in the physical filling phenomena inside meandering channels and pre-jamming phase of filling. This procedure has the potential to maximize the sand throughput from a single inlet pipe at minimum possible time. Of all the above mentioned methods, simple gravity backfilling was found to be economic as well as efficient, especially when the flow rates are high. Some empirical relationships developed using multiple regression technique for use by the practicing engineers for the process control while employing this process are also discussed in the paper.

Influence of fillers on NR/SBR blends containing ENR-organoclay nanocomposites: morphology and wear.

Pal, Kaushik,Rajasekar, R,Pal, Samir Kumar,Kim, Jin Kuk,Das, Chapal Kumar American Scientific Publishers 2010 Journal of Nanoscience and Nanotechnology Vol.10 No.5

<P>In this study the Epoxidized natural rubber (ENR) and Organoclay (Cloisite 20A) were prepared by solution mixing process. The obtained nanocomposites were incorporated in Natural rubber (NR) and Styrene butadiene rubber (SBR) blends in presence of varying types of carbon black as reinforcing fillers. Morphology, curing characteristics, mechanical and thermal properties were characterized and analyzed. Also, the wear characteristics of the nanocomposites against Du-Pont abrader, DIN abrader and different mining rock surfaces were determined and discussed. The morphology of the organoclay incorporated in ENR shows a highly intercalated structure. ISAF type of carbon black shows a significant effect on curing and mechanical properties by reacting at the interface between SBR and NR matrix. All the samples show only one melting peak at same temperature on the DSC curve. Blends containing ISAF N234 type of carbon black shows high abrasion resistant properties against Du-Pont abrader, DIN abrader and different mining rock. The rubber compound containing 70 wt% of NR, 30 wt% of SBR and 10 wt% of ENR/nanoclay with ISAF N231 are found to be the toughest rubber against all types of rock under the present study.</P>

Bromelain mediates apoptosis in HeLa cells via ROS-independent pathway

Ayantika Pal,Samir Kumar Sil 경희대학교 융합한의과학연구소 2023 Oriental Pharmacy and Experimental Medicine Vol.23 No.2

Several in vitro studies along with some in vivo studies have shown the anti-cancer activity of bromelain against several types of cancer except cervical cancer. This study is focused to address the therapeutic effect of bromelain on a human cervical cancer cell line in vitro using HeLa cells. Here, the IC50 dose of bromelain enhanced Hela cell apoptosis at a concentration of 100 μg/ml after 48 h treatment, which is statistically significant compared to the dose of 50 μg/ml (p < 0.01). The percentage of live cells was reduced to about 48% and the percentage of apoptotic cells has increased to about 47% at the IC50 dose of bromelain with a 48 h exposure. Significant proportions of HeLa cells were observed to undergo apoptosis via the p53-dependent pathway in a ROS-independent manner at 100 μg/ml after 48 h treatment. In addition to that, bromelain also inhibited the formation of colonies and the migratory ability of HeLa cells. The present study reports that bromelain can act in an apoptotic pathway on human cervical cancer cell line HeLa.

Temperature-dependent femtosecond-resolved hydration dynamics of water in aqueous guanidinium hydrochloride solution

Banerjee, Debapriya,Verma, Pramod Kumar,Pal, Samir Kumar Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.10

The influence of ion dissolution in water is still controversial. The challenge posed to the existing concept of dissolved ions acting as water structure makers and structure breakers through recent studies calls for more experimental evidence. The temperature-dependent relaxation dynamics of water in bulk and in ionic salt solutions can give an idea about the hydrogen-bonded network and hence the perturbation induced in the tetrahedral structure of bulk water subsequent to ion dissolution. In our study, the temperature dependence of the observed relaxation dynamics in bulk water and guanidinium hydrochloride reveals the activation energy needed to convert water from hydrogen bonded to the free forms and hence the difference in the hydrogen-bonded network in the close vicinity of the probe molecule. The results might prove helpful to understand the interaction of hydrophobic amino acid residues with guanidinium hydrochloride during protein denaturation.

Unraveling the Role of Monoolein in Fluidity and Dynamical Response of a Mixed Cationic Lipid Bilayer

Singh, Priya,Sharma, Veerendra Kumar,Singha, Subhankar,Garcí,a Sakai, Victoria,Mukhopadhyay, Ramaprosad,Das, Ranjan,Pal, Samir Kumar American Chemical Society 2019 Langmuir Vol.35 No.13

<P>The maintenance of cell membrane fluidity is of critical importance for various cellular functions. At lower temperatures when membrane fluidity decreases, plants and cyanobacteria react by introducing unsaturation in the lipids, so that the membranes return to a more fluidic state. To probe how introduction of unsaturation leads to reduced membrane fluidity, a model cationic lipid dioctadecyldimethylammonium bromide (DODAB) has been chosen, and the effects of an unsaturated lipid monoolein (MO) on the structural dynamics and phase behavior of DODAB have been monitored by quasielastic neutron scattering and time-resolved fluorescence measurements. In the coagel phase, fluidity of the lipid bilayer increases significantly in the presence of MO relative to pure DODAB vesicles and becomes manifest in significantly enhanced dynamics of the constituent lipids along with faster hydration and orientational relaxation dynamics of a fluorophore. On the contrary, MO restricts both lateral and internal motions of the lipid molecules in the fluid phase (>330 K), which is consistent with relatively slow hydration and orientational relaxation dynamics of the fluorophore embedded in the mixed lipid bilayer. The present study illustrates how incorporation of an unsaturated lipid at lower temperatures (below the phase transition) assists the model lipid (DODAB) in regulating fluidity via enhancement of dynamics of the constituent lipids.</P> [FIG OMISSION]</BR>

Characterization of Rock Materials based on Signal Emission levels Under Uni-Axial Compression

K.U.M. Rao,Subir Kumar Ghosh,Sudipta Bhattacharjee,D. Deb,Samir K.Pal 한국암반공학회 2010 한국암반공학회 학술대회 및 세미나 자료집 Vol.2010 No.10

Characterization of engineering materials is an essential aspect of manufacturing, since the properties of both the job and the tool influence each other. Experimental work is conducted to detect acoustic, vibration and electromagnetic emissions produced during uniaxial compressive loading of rock specimens. Preliminary results of testing limestone, quartz and sandstone rock specimens are presented. Some results of testing granite and coal samples are also presented. Results indicate that different types of AE, vibration and EM signals are produced during testing of a rock type to failure. In rock drilling one of the main consumables is the cutting tool. The performance of the cutting tool and its life is also controlled by the properties of the job (rock). The present work aims at characterization of rock material based on the physical and mechanical properties, as well as the levels of acoustic emissions and electromagnetic emission under uni-axial compression with the help of appropriate sensors and instrumentation.