Pankaj Debnath - Academia.edu (original) (raw)

Papers by Pankaj Debnath

We study the stability of attractive atomic Bose-Einstein condensate and the macroscopic quantum ... more We study the stability of attractive atomic Bose-Einstein condensate and the macroscopic quantum many-body tunneling (MQT) in the anharmonic trap. We utilize correlated two-body basis function which keeps all possible two-body correlations. The anharmonic parameter (λ) is slowly tuned from harmonic to anharmonic. For each choice of λ the many-body equation is solved adiabatically. The use of the van der Waals interaction gives realistic picture which substantially differs from the mean-field results. For weak anharmonicity, we observe that the attractive condensate gains stability with larger number of bosons compared to that in the pure harmonic trap. The transition from resonances to bound states with weak anharmonicity also differs significantly from the earlier study of Moiseyev et.al.[J. Phys. B: At. Mol. Opt. Phys. 37, L193 (2004)]. We also study the tunneling of the metastable condensate very close to the critical number N_cr of collapse and observe that near collapse the MQT...

Indo American Journal of Pharmaceutical Research, 2013

The study was carried out to investigate the thrombolytic potential of crude ethanolic extract of... more The study was carried out to investigate the thrombolytic potential of crude ethanolic extract of fruits of Momordica charantia, an anti-diabetic medicinal plant, using an in vitro assay method. The thrombolytic investigation involved five young Bangladeshi volunteers to get different nature of blood samples. Five concentrations of the crude extract were used for the study, with a standard (Streptokinase), and negative control (sterilized distilled water) to validate the method. The thrombolytic nature of the plant was found significant (p < 0.01), except for the concentration 4 mg/ml, when compared with the negative control (water) at different doses. The plant showed mild clot lysis, i.e. 2.16Â±0.723%, 5.06Â±1.058%, 8.60Â±0.626%, 11.64Â±0.747%, and 15.18Â±1.691% at 2, 4, 6, 8, and 10 mg/ml concentrations respectively, while the standard (streptokinase) showed 47.22Â±2.738% clot lysis. Therefore, the obtained results suggest that the crude ethanolic extract of Momordica charanti...

In this paper, a three-dimensional turbine disc model is established. By using the FEM (finite el... more In this paper, a three-dimensional turbine disc model is established. By using the FEM (finite element method), the critical stress and strain concentration regions are determined according to the static structural analysis results of the turbine disc. Besides, the stress gradient distributions of the assembly holes, the gear teeth region, and the hub region are identified. Then by introducing an improved SWT (Smith-Watson-Topper) parameter model which can take the stress gradient effect into consideration, the fatigue life of the hub region, the gear teeth region, and the assembly holes is obtained. Comparing the life prediction results of the critical regions, finally we get the turbine disc’s fatigue life.

Dynamic successive cancellation flip (DSCF) decoding of polar codes is a powerful algorithm that ... more Dynamic successive cancellation flip (DSCF) decoding of polar codes is a powerful algorithm that can achieve the error correction performance of successive cancellation list (SCL) decoding, with a complexity that is close to that of successive cancellation (SC) decoding at practical signal-to-noise ratio (SNR) regimes. However, DSCF decoding requires costly transcendental computations which adversely affect its implementation complexity. In this paper, we first show that a direct application of common approximation schemes on the conventional DSCF decoding results in significant error-correction performance loss. We then introduce a training parameter and propose an approximation scheme which completely removes the need to perform transcendental computations in DSCF decoding, with almost no error-correction performance degradation.

British Journal of Pharmaceutical Research, 2014

ABSTRACT Aims: The study was conducted to compare the presence of different phytochemicals and bi... more ABSTRACT Aims: The study was conducted to compare the presence of different phytochemicals and biological activities like cytotoxicity, anthelmintic activity, antioxidant and free radical scavenging activities between aqueous and ethanolic extract of Momordica charantia L. Fruits. Methodology: The cytotoxic assay was undertaken using brine shrimp lethality test (BSLT) while the anthelmintic activity was carried out with the determination of time of paralysis and death of earthworm (Pheritima posthuma) at five different concentrations. Antioxidant and free radical scavenging activities were measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and determining the total phenolic contents. Results: Study revealed that several phytochemicals were found common for both of the extracts, though proteins and amino acids were only found in ethanolic extract. Both the extracts showed mild cytotoxic activity where the ethanolic extract showed better potency (LC50=24.245 μg/ml) than aqueous extract (LC50=24.515 μg/ml). In case of anthelmintic activity, ethanolic extract was also found significantly potent than aqueous extract at five different concentrations. IC50 values for the total antioxidant activity were 304.41±0.903 μg/ml and 479.05±1.393 μg/ml for ethanolic and aqueous extract, respectively. Ethanolic extract contained a significantly higher concentration of total phenols (71.08 ± 0.380 mg of GAE/g of extract) in comparison to aqueous extract (57.33±0.520 mg of GAE/g of extract). Conclusion: Therefore, in all aspects of the study, ethanolic extract was found more potent than aqueous extract. It can be concluded that M. charantia fruits are abundant of various phytochemicals and possess versatile biological activities.

Bangladesh Pharmaceutical Journal, 2016

This study was carried out to investigate the antioxidant activity in terms of free radical scave... more This study was carried out to investigate the antioxidant activity in terms of free radical scavenging capacity and membrane stabilizing ability of methanol extract of bark of Sonneratia apetala. The total phenol content of the extract was measured by Folin-Ciocalteu reagent. The antioxidant potential was investigated using 2,2 diphenylpicrylhydrazyl (DPPH), reducing power assay and chelating power determination. The membrane stabilizing capacity was assessed by monitoring the hypotonic solution - and heat-induced haemolysis of human erythrocytes. The total phenolic content was found 50.75 mg/gm of gallic acid equivalent. The extract exhibited significant antioxidant activity in DPPH free radical scavenging assay with IC50 value of 81.42 µg/ml as compared to the standard, BHT (IC50=42.56 µg/ml), Fe2+ ion reducing power assay and chelating power ability. In case of assay for chelating ability, EDTA represented 98.76% chelation while the plant extract showed 82.83% at concentration of...

Bangladesh Journal of Medicine, 2016

We study the stability of attractive atomic Bose-Einstein condensate in the anharmonic trap using... more We study the stability of attractive atomic Bose-Einstein condensate in the anharmonic trap using a correlated many-body method. The anharmonic parameter (λ) is slowly tuned from harmonic to weak and then to strong anharmonicity. For each choice of λ the many-body equation is solved adiabatically. The use of the van der Waals interaction gives realistic picture which substantially differs from the mean-field results. For weak anharmonicity, we observe that the attractive conden-sate gains stability with larger number of bosons compared to that in the pure harmonic trap. The transition from resonances to bound states with weak anharmonicity also differs significantly from the earlier study of Moiseyev et.al.[J. Phys. B: At. Mol. Opt. Phys. 37, L193 (2004)]. We also study the tunneling of the metastable condensate very close to the critical number Ncr of collapse. For intermediate anharmonicity, we observe dual tunneling through the two adjacent barriers. We also calculate the critica...

Bangladesh Pharmaceutical Journal, 2015

This study was conducted to evaluate the rate of vaccination and its impacts on the children in f... more This study was conducted to evaluate the rate of vaccination and its impacts on the children in four upazilas which were Noakhali sadar, Begumgonj, Companygonj and Chatkhil of Noakhali district. The study was carried out during the period of November 15, 2011 to December 15, 2011. Data were collected through questionnaire interviews, focus group discussions and cross check interviews. It was found that all interviewed parents of all ages and educational levels are aware about vaccination of their child. The study conducted on the rate of giving vaccines, (Tuberculosis, Polio, DPT, Measles and Hepatitis B) showed serious reactions in a few children after taking vaccine and occurrences of disease after taking the corresponding vaccine. The rate of vaccination in the four upazilas - Noakhali sadar, Begumgonj, Companygonj and Chatkhil were found to be 84, 86.6, 75.4 and 82%, respectively. No serious reactions were found among 120 children in four upazilas. Among thirty, two children suf...

Journal of Saudi Chemical Society, 2014

This study describes the effects of extracts and fractions of Persea willdenovii leaves against g... more This study describes the effects of extracts and fractions of Persea willdenovii leaves against goat gastrointestinal nematodes and their cytotoxicity on Vero cells. The in vitro ovicidal and larvicidal activities of the crude ethanolic, hexane, ethyl acetate (EAE), butanolic and residual hydroethanolic extracts were assessed through the inhibition of egg hatching and larval motility assays. The most active extract (EAE) was then fractionated by chromatography in an open column containing silica gel, to furnish six fractions (Fr1-Fr6), which were also tested. The cytotoxicity of active extracts and fractions was determined using the 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue exclusion assay. The EAE and two fractions (Fr1 and Fr2) showed inhibitory activity in the egg hatching of gastrointestinal nematodes of goats in a concentration-dependent manner. The effective concentrations for 50% inhibition (EC 50) of egg hatching were 2.3, 0.12 and 2.94 mg/ml for EAE, Fr1 and Fr2, respectively. All extracts and fractions were not effective in inhibiting 50% of motility of infective larvae. EAE and Fr2 had IC 50 values (50% inhibitory concentration) of 4.95 and 2.66 mg/ml, respectively. Fr1 showed a slight cytotoxic effect (cellular inviability <30%) only after 48 h of treatment (MTT test). Gas chromatography-mass spectrometry (GC-MS) analysis showed the presence of six fatty acid ethyl esters, a fatty acid methyl ester and a long-chain ketone in the most active fraction. These constituents identified in P. willdenovii can be related to the high ovicidal activity and relatively non-toxic effect of the extracts.

Physical Review A, 2010

... cr 043614-5 PK DEBNATH AND BARNALI CHAKRABARTI PHYSICAL REVIEW A 82, 043614 (2010) the calcul... more ... cr 043614-5 PK DEBNATH AND BARNALI CHAKRABARTI PHYSICAL REVIEW A 82, 043614 (2010) the calculated Ï Q by our PHEM show rapid change as k approaches kcr = â 0.451 for Î» = 0. The difference ... PKD wishes to thank Mr. Anindya Biswas for his helpful discussions. ...

Physical Review A, 2009

We study the stability of Bose-Einstein condensate (BEC) with repulsive and attractive interatomi... more We study the stability of Bose-Einstein condensate (BEC) with repulsive and attractive interatomic interactions in a harmonic plus quartic trap [V(r)=(1)/(2)momega2r2+lambdar4] . We find that BEC with repulsive interaction becomes more stable for lambda&gt;0 . For lambda&lt;0 , we observe a different metastability of the condensate even when the scattering length is positive. For BEC with attractive interaction, we observe

Pharmacognosy Journal, 2011

Pharmacognosy Journal, 2013

ABSTRACT AimsThe present study aimed at assessing the effect of methanol extract of Erioglossum r... more ABSTRACT AimsThe present study aimed at assessing the effect of methanol extract of Erioglossum rubiginosum, a widely used shrub like plant in folkloric medicine, in experimentally induced inflammation, using human red blood cell (HRBC) membrane stabilization as study method.Methods The methanol extract of leaves of E. rubiginosum and its pet-ether, carbon tetrachloride, chloroform and aqueous soluble partitionates were subjected to assays for lysis of erythrocytes and % of inhibition in hypotonic solution and heat induced lysis, using acetyl salicylic acid as standard drug, in an in vitro model.ResultsAt the concentration of 1 mg/ml, methanol extract and its pet-ether, carbon tetrachloride, chloroform and aqueous soluble partitionates significantly inhibited hypotonic solution induced lysis of the human red blood cell membrane with values of 0.428 ± 0.005, 0.204 ± 0.003, 0.233 ± 0.002, 0.411 ± 0.003, 0.439 ± 0.003% respectively; which were comparable to the standard drug acetyl salicylic acid (0.1 mg/ml), 0.166 ± 0.003. In case of heat induced HRBC heamolysis, the plant extracts also showed significant activity where the values of inhibitory actions were 14.46 ± 0.344, 28.23 ± 0.315, 25.18 ± 0.303, 17.09 ± 0.365, 13.44 ± 0.470% for methanol extract, pet-ether, carbon tetrachloride, chloroform and aqueous soluble partitionates respectively.Conclusion It can be postulated from the observed results that the membrane stabilizing action and inhibition of erythrocyte lysis property of E. rubiginosum may be the possible mechanism of action of its anti-inflammatory activity. So, further studies are suggested to evaluate the anti-inflammatory and analgesic activities of the plant.

Journal of Low Temperature Physics, 2009

We employ a correlated many-body approach to study Bose-Einstein condensation of a magnetically t... more We employ a correlated many-body approach to study Bose-Einstein condensation of a magnetically trapped gas of 7 Li atoms. The properties of a trapped gas are strongly influenced by the attractive interactions and two-body correlations. The correlations lower the interaction energy. The lowlying collective frequencies have also been calculated. In addition we explore the frequency of surface modes as a function of angular momentum.

The European Physical Journal D, 2013