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Somak Das,Tuhin Subhra Manadal,Suman Das,Jayanta Biswas,Arunesh Gupta,Sreecheta Mukherjee,Sukanta Ray 한국간담췌외과학회 2023 Annals of hepato-biliary-pancreatic surgery Vol.27 No.4
Backgrounds/Aims: Extra hepatic portal venous obstruction (EHPVO) is the most common cause of portal hypertension in Indian children. While endoscopy is the primary modality of management, a subset of patients require surgery. This study aims to report the short- and long-term outcomes of EHPVO patients managed surgically. Methods: All the patients with EHPVO who underwent surgery between August 2007 and December 2021 were retrospectively reviewed. Postoperative complications were classified after Clavien–Dindo. Binary logistic regression in Wald methodology was used to determine the predictive factors responsible for unfavourable outcome. Results: Total of 202 patients with EHPVO were operated. Mean age of patients was 20.30 ± 9.96 years, and duration of illness, 90.05 ± 75.13 months. Most common indication for surgery was portal biliopathy (n = 59, 29.2%), followed by bleeding (n = 50, 24.8%). Total of 166 patients (82.2%) had shunt procedure. Splenectomy with esophagogastric devascularization was the second most common surgery (n = 20, 9.9%). Nine major postoperative complications (Clavien–Dindo > 3) were observed in 8 patients (4.0%), including 1 (0.5%) operative death. After a median follow-up of 56 months (15−156 months), 166 patients (82.2%) had favourable outcome. In multivariate analysis, associated splenic artery aneurysm (p = 0.007), isolated gastric varices (p = 0.004), preoperative endoscopic retrograde cholangiography and stenting (p = 0.015), and shunt occlusion (p < 0.001) were independent predictors of unfavourable long-term outcome. Conclusions: Surgery in EHPVO is safe, affords excellent short- and long-term outcome in patients with symptomatic EHPVO, and may be considered for secondary prophylaxis.
Investigation of thermal performance of SAC variables using fuzzy logic based expert system
Suman Debnath,Jagannath Reddy,Jagadish,Biplab Das 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8
The thermal performance of a solar air collector (SAC) is investigated experimentally under the different climatic conditions of north eastern India using fuzzy logic based expert system (FLES). The FLES based on subtractive clustering (SC) with the fuzzy logic method where here, SC is used for extraction of optimal fuzzy IF-THEN rules while a fuzzy logic is used for modeling of SAC variables. This work considered four input variables [like mass flow rate (m), collector tilt angles (θ), solar radiation (Q), temperature (T)] and the four output variables [i.e. efficiency (η), exergetic efficiency (η II ), temperature rise (∆T), and pressure drop (∆P)]. First, 272 trials of experimentation on SAC are performed by varying m from 0.0078 to 0.0118 kg/s and θ from 30 to 60°, whereas the variation of metrological data is obtained in different working days. Then modeling and parametric analysis is carried out for SAC. Experimental results reveal that the value of η increases with the increase in m, Q, T and θ up to 45°. The higher value of m results in a higher value of ∆P and that reduces the value ofη II . Also, FLES model provides comparable and acceptable values for SAC. At last, validation of the FLES model is done via published data to confirm the results.
Saha Suman,Das Santanu 대한용접접합학회 2020 대한용접·접합학회지 Vol.38 No.4
In activated tungsten inert gas (A-TIG) welding, a thin layer of suitable activating flux is applied over the base metal to not only enhance penetration of the molten metal into root gap by 2 - 3 times compared to conventional TIG welding but also reduce the weld bead width considerably. This work focuses on examining the influence of TiO2, Fe2O3 and Cr2O3 activating fluxes (single component) on the weld bead geometry observed during the butt joining of 6 mm thick stainless steel (306 grade) plates by A-TIG welding under direct current straight polarity (DCSP). Three weld bead morphological parameters, namely, the depth of penetration, reinforcement and weld bead width, and their ratios are considered. The results are compared with those obtained during conventional TIG welding. The TiO2 and Fe2O3 fluxes exhibit the potential capabilities in enhancing penetration, reducing weld bead width, and re�ducing reinforcement. The Cr2O3 flux plays an insignificant role for redefining the weld bead shape, and in certain cases, this flux performs inferior compared to conventional TIG welding.
Insight into emerging applications of forward osmosis systems
Pallabi Das,Krishna Kant Kumar Singh,Suman Dutta 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-
The advent of Forward Osmosis (FO) has ushered in a new revolution in thefield of membranetechnology. Besides the oft-studied application of water purification, FO has opened up new frontiers ofresearch in diversefields. All of them are potentially sustainable technology solutions characterized by ahigh degree of process intensification. It is interesting to imagine different avenues where the potentcombination of membrane technology and osmotic gradient can be used. This brief review evaluates foursuch emerging applications of FO; viz: Membrane Crystallization, Osmotic Pumps, Energy Production,and Membrane Evaporation which will be considered as the most important in the near future. All fouraforesaid applications were critically reviewed with respect to the principle of operation, process designfundamentals, cost distribution, tangible benefits over conventional alternatives and commercialventures around the world. Comparative assessments of transportflux, yield, configuration, andmembrane module was carried out. Several issues relating to performance, hydrodynamics and scale updesigns were analyzed with special emphasis on concentration polarization,flux decline, nature of themembrane.
Shaun Eshraghi,Suman Das,Mehdi Karevan,Kyriaki Kalaitzidou 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Electrically conductive polymer nanocomposites were prepared through selective laser sintering (SLS) of polyamide-12 (PA) powder coated with graphite nanoplatelets (GNP) using sonication. The SLS process parameters were optimized in order to maximize the tensile modulus at 3 and 5 wt% GNP. The highest tensile modulus (2.1 GPa) was achieved at 3 wt%. A slight decrease in flexural modulus and strength was observed at 3 and 5 wt% GNP compared with the neat polymer. Morphological observation of the graphitecoated PA powder showed fairly homogeneous dispersion. The SLS processed parts were nearly fully dense and the highest density (99.5%) was found at 3 wt% GNP. The bulk electrical conductivity of the SLS-processed nanocomposites was found to be 3.8×10-11 and 6.4×10-8 S/cm for 3 and 5 wt% GNP respectively.
Haseung Chung,Suman Das 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
This article investigates the fabrication of functionally graded materials (FGMs) by selective laser sintering of Nylon-11 composites filled with different volume fractions of glass beads. The investigation involved a combination of experimental studies, theoretical modeling and numerical analysis. Optimal processing parameters for each composition were developed by design of experiments (DOE). The tensile and compressive specimens for each composition and a 1-D functionally graded composition were fabricated and tested. Finally, to demonstrate the FGM approach, three different components, each exhibiting a 1-D functional gradient of particulate filled polymer composites were fabricated.
Chiranjit Maity,Saptadip Samanta,Suman K. Halder,Pradeep K. Das Mohapatra,Bikas R. Pati,Malabendu Jana,Keshab C. Mondal 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.2
The aim of this study was to produce two isozymes of α-amylase by immobilization of a newly isolated soil bacterium. The bacterium was identified as Bacillus thuringiensis CKB19 on the basis of its 16S rRNA profile. Enzyme production by free cells increased linearly with cell growth up to 34 h in starch containing enriched liquid media. The active bacterial cells were immobilized in Caalginate beads, and operational stability of the entrapped cell was optimized for amylase production. Enzyme production was optimal at an alginate concentration of 2 g%(w/v), calcium chloride concentration of 1 M, and with 300beads (each bead contained 2 × 10^7 cells)/250 mL flask. Amylase production by the immobilized cells was about 3times higher than free cell fermentation after 34 h of incubation. It was observed that the immobilized bacterium secreted two different amylases (Am-I and Am-II) into the culture fluid. The molecular masses of Am-I and Am-II were 59.6 and 44.7 kd, respectively, and showed optimum activity at pH 5.0 and 9.0. Both amylases showed optimum activity at 40℃ and were stable at the same temperature,with losses of only 10 and 20% (for Am I and Am II,respectively) of their original activities after 24 h of incubation. Further, both amylases were salt tolerant (up to 4 M NaCl) and hydrolyzed raw starchy foods into glucose. All these characteristics make this enzyme mixture suitable for use as a digestive aid and for the improvement of digestibility of animal feed ingredients.
A fluorescent probe for bisulfite ions: its application to two-photon tissue imaging
Agarwalla, Hridesh,Pal, Suman,Paul, Anirban,Jun, Yong Woong,Bae, Juryang,Ahn, Kyo Han,Srivastava, Divesh N.,Das, Amitava The Royal Society of Chemistry 2016 Journal of Materials Chemistry B Vol.4 No.48
<P>A benzoxazinone based fluorescent probe for the specific and efficient detection of bisulfite ions in aqueous medium is described. The probe formed a bisulfite/sulphite adduct with an associated turn-on fluorescence response in the red wavelength region. No interference was observed in the detection process from all possible competing anions and molecules, including cyanide ion, cysteine, homocysteine and glutathione. In addition, the probe showed a fast response time, low detection limit, and cell membrane permeability. Furthermore, the probe was two-photon excitable, enabling imaging of endogenous bisulfite ions in HeLa cells as well as in deep tissues from different organs of mouse.</P>
Laser Micro-Machining Using Near-Field Optics
Haseung Chung,Katsuo Kurabayashi,Suman Das 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Solid immersion lenses (SIL) facilitate high numerical aperture (NA) and consequent sub-wavelength diffraction limited focusing in near-field optics based systems. Such systems are in commercial and research use for various applications including near-field scanning optical microscopy, ultra-high density magnetooptic data storage and near-field nanolithography. Here, we present a novel manufacturing method using SIL-based near-field optics for laser-induced patterning on silicon wafers. Results of experiments that were conducted at various processing conditions to investigate the effects of varying incident laser power, pulse repetition rate, pulse width, number of pulses and size of SIL on processed feature size and resolution are presented.