Wafer Bonding Fabrication of III-V/Si Based Tandem Solar Cells: A Review

Swagata Panchanan(판차난 스와가타),Subhajit Dutta(두타 수바짓),Kumar Mallem(맬른 쿠마),Simpy Sanyal(상얄 심피),Jinjoo Park(박진주),Young Hyun Cho(조영현),Eun-Chel Cho(조은철),Junsin Yi(이준신) 한국신재생에너지학회 2018 한국신재생에너지학회 학술대회논문집 Vol.2018 No.11

A Brief Study on the Fabrication of III-V/Si Based Tandem Solar Cells

Swagata Panchanan,DUTTA SUBHAJIT,Kumar Mallem,Simpy Sanyal,박진주,주민규,조영현,조은철,이준신 한국태양광발전학회 2018 Current Photovoltaic Research Vol.6 No.4

Silicon (Si) solar cells are the most successful technology which are ruling the present photovoltaic (PV) market. In that essence, multijunction (MJ) solar cells provided a new path to improve the state-of-art efficiencies. There are so many hurdles to grow the MJ III-V materials on Si substrate as Si with other materials often demands similar qualities, so it is needed to realize the prospective of Si tandem solar cells. However, Si tandem solar cells with MJ III-V materials have shown the maximum efficiency of 30 %. This work reviews the development of the III-V/Si solar cells with the synopsis of various growth mechanisms i.e hetero-epitaxy, wafer bonding and mechanical stacking of III-V materials on Si substrate. Theoretical approaches to design efficient tandem cell with an analysis of state-of-art silicon solar cells, sensitivity, difficulties and their probable solutions are discussed in this work. An analytical model which yields the practical efficiency values to design the high efficiency III-V/Si solar cells is described briefly.

Spirituality bestowing self-transcendence amid COVID-19 through slow fashion

Chakraborty Swagata,Sadachar Amrut 한국마케팅과학회 2023 Journal of Global Fashion Marketing Vol.14 No.3

We proposed and tested a conceptual model exploring how (i) COVID-stress evokes spirituality; (ii) COVID-stress and spirituality engender positive attitude toward the different dimensions of slow fashion (i.e. equity, authenticity, functionality, localism, and exclusivity) as a symbol of self-transcendence and (iii) spirituality mediates the relationships between COVID-stress and the different dimensions of slow fashion. We conducted an online survey in Amazon Mechanical Turk (n = 317) and analyzed the data through structural equation modeling. (i) COVID-stress positively influences spirituality; (ii) both COVID-stress and spirituality positively influ- ence attitude toward slow fashion in terms of equity, authenticity, localism, and exclusivity; (iii) spirituality mediates the relationships between COVID-stress and all the dimensions of slow fashion except for functionality. Due to the fast-changing situations amid the pandemic and the uneven severity of the pandemic globally, a cross-sectional study may have limited the scope for capturing nuances of retail consumer behavior. In summary, we suggest that the consumption of slow fashion apparel as a symbol of self- transcendence may help consumers cope with COVID-stress in the hope of building spiritual ties with a higher power through the process of ethical consumption amid the pandemic.

Impact spectrum of flood hazard on seismic vulnerability of bridges

Taner Yilmaz,Swagata Banerjee 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.4

Multiple hazards (multihazard) conditions may cause significant risk to structures that are originally designed for individual hazard scenarios. Such a multihazard condition arises when an earthquake strikes to a bridge pre-exposed to scour at foundations due to flood events. This study estimates the impact spectrum of flood-induced scour on seismic vulnerability of bridges. Characteristic river-crossing highway bridges are formed based on the information obtained from bridge inventories. These bridges are analyzed under earthquake-only and the abovementioned multihazard conditions, and bridge fragility curves are developed at component and system levels. Research outcome shows that bridges having pile shafts as foundation elements are protected from any additional seismic vulnerability due to the presence of scour. However, occurrence of floods can increase seismic fragility of bridges at lower damage states due to the adverse impact of scour on bridge components at superstructure level. These findings facilitate bridge design under the stated multihazard condition.

Multi-point response spectrum analysis of a historical bridge to blast ground motion

Kemal Hacıefendioğlu,Swagata Banerjee,Kurtuluş Soyluk,Olgun Köksal 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.5

In this study, the effects of ground shocks due to explosive loads on the dynamic response of historical masonry bridges are investigated by using the multi-point shock response spectrum method. With this purpose, different charge weights and distances from the charge center are considered for the analyses of a masonry bridge and depending on these parameters frequency-varying shock spectra are determined and applied to each support of the two-span masonry bridge. The net blast induced ground motion consists of air-induced and direct-induced ground motions. Acceleration time histories of blast induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectrums determined from the ground shock time histories are simulated using BlastGM software. The results obtained from uniform and multi-point response spectrum analyses cases show that significant differences take place between the uniform and multi-point blast-induced ground motions.

Evidence of an Alternative Route of Cellobiase Secretion in the Presence of Brefeldin A in the Filamentous Fungus Termitomyces clypeatus

( Banik Samudra Prosad ),( Swagata Pal ),( Sudeshna Chowdhury ),( Shakuntala Ghorai ),( Suman Khowala ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.4

Secretion of cellobiase occurred in a brefeldin A (BFA) uninhibited manner in the filamentous fungus Termitomyces clypeatus. Fluorescence confocal microscopy revealed that application of the drug at a concentration of 50 μg/ml caused arrest of Spitzenkorper assembly at the hyphal tip. This resulted in greater than 30% inhibition of total protein secretion in the culture medium. However, the cellobiase titer increased by 17%, and an additional 13% was localized in the vacuolar fraction en route secretion. The secretory vacuoles formed in the presence of the drug were also found to be bigger (68 nm) than those in the control cultures (40 nm). The enzyme secreted in the presence and absence of BFA revealed a single activity band in both cases in native PAGE and had similar molecular masses (approx. 120 kDa) in SDS-PAGE. The BFA enzyme retained 72% of native glycosylation. It also exhibited a higher stability and retained 98% activity at 50oC, 93.3% activity at pH 9, 63.64% activity in the presence of 1M guanidium hydrochloride, and 50% activity at a glucose concentration of 10 mg/ml in comparison to 68% activity, 75% activity, 36% activity, and 19% activity for the control enzyme, respectively. The observations collectively aimed at the operation of an alternative secretory pathway, distinct from the target of brefeldin A, which bypassed the Golgi apparatus, but still was able to deliver the cargo to the vacuoles for secretion. This can be utilized in selectively enhancing the yield and stability of glycosidases for a successful industrial recipe.

Multi-point response spectrum analysis of a historical bridge to blast ground motion

Haciefendioglu, Kemal,Banerjee, Swagata,Soyluk, Kurtulus,Koksal, Olgun Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.5

In this study, the effects of ground shocks due to explosive loads on the dynamic response of historical masonry bridges are investigated by using the multi-point shock response spectrum method. With this purpose, different charge weights and distances from the charge center are considered for the analyses of a masonry bridge and depending on these parameters frequency-varying shock spectra are determined and applied to each support of the two-span masonry bridge. The net blast induced ground motion consists of air-induced and direct-induced ground motions. Acceleration time histories of blast induced ground motions are obtained depending on a deterministic shape function and a stationary process. Shock response spectrums determined from the ground shock time histories are simulated using BlastGM software. The results obtained from uniform and multi-point response spectrum analyses cases show that significant differences take place between the uniform and multi-point blast-induced ground motions.

In situ Reversible Aggregation of Extracellular Cellobiase in the Filamentous Fungus Termitomyces clypeatus

Samudra Prosad Banik,Swagata Pal,Shakuntala Ghorai,Sudeshna Chowdhury,Rajib Majumder,Soumya Mukherjee,Suman Khowala 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.5

Cellobiase (E.C. 3.2.1.21), is a widely exploited industrial glycosidase with a major role in biofuel industry. Its stability and shelf life are major bottlenecks in achieving a superior formulation for industry. In the filamentous fungus Termitomyces clypeatus, the enzyme is secreted in a co-aggregated form with sucrase; the separation of this co-aggregation results in substantial loss of the enzyme’s activity. The aim of the present study was to examine the mode of aggregation of the secreted cellobiase-sucrase coaggregate and its role in the stabilization of cellobiase. Transmission electron microscopy and dynamic light scattering of purified co-aggregates revealed reversible, concentration driven self-aggregation of the extracellular enzymes to form larger entities. However, the intracellular enzyme aggregates were rigid,non-interacting, and possessed a higher percentage of disulphide bonds. Circular dichroic spectra of the two coaggregates indicated no significant difference in secondary structures. Self-association increased the stability of extracellular aggregates towards heat by 1.5 fold, SDS by 4 ~ 7 fold, and chaotropic agents, by 1.5 ~ 2 fold, than the intracellular counterpart. The Km of extracellular aggregate varied between 0.29 and 0.45 mM as a result of spontaneous aggregation and disaggregation, whereas that of intracellular aggregate was 0.22 mM irrespective of its concentration status. In situ detection of cellobiase in native PAGE revealed two activity bands of the extracellular enzyme, which indicated a minimum of two active dissociated aggregate species, as compared to a single band for the intracellular enzyme. These studies are believed to improve the understanding of aggregation of the fungal glycosidases, which remains to be a blackbox, to increase the efficacy of these enzymes. Cellobiase (E.C. 3.2.1.21), is a widely exploited industrial glycosidase with a major role in biofuel industry. Its stability and shelf life are major bottlenecks in achieving a superior formulation for industry. In the filamentous fungus Termitomyces clypeatus, the enzyme is secreted in a co-aggregated form with sucrase; the separation of this co-aggregation results in substantial loss of the enzyme’s activity. The aim of the present study was to examine the mode of aggregation of the secreted cellobiase-sucrase coaggregate and its role in the stabilization of cellobiase. Transmission electron microscopy and dynamic light scattering of purified co-aggregates revealed reversible, concentration driven self-aggregation of the extracellular enzymes to form larger entities. However, the intracellular enzyme aggregates were rigid,non-interacting, and possessed a higher percentage of disulphide bonds. Circular dichroic spectra of the two coaggregates indicated no significant difference in secondary structures. Self-association increased the stability of extracellular aggregates towards heat by 1.5 fold, SDS by 4 ~ 7 fold, and chaotropic agents, by 1.5 ~ 2 fold, than the intracellular counterpart. The Km of extracellular aggregate varied between 0.29 and 0.45 mM as a result of spontaneous aggregation and disaggregation, whereas that of intracellular aggregate was 0.22 mM irrespective of its concentration status. In situ detection of cellobiase in native PAGE revealed two activity bands of the extracellular enzyme, which indicated a minimum of two active dissociated aggregate species, as compared to a single band for the intracellular enzyme. These studies are believed to improve the understanding of aggregation of the fungal glycosidases, which remains to be a blackbox, to increase the efficacy of these enzymes.

Impact spectrum of flood hazard on seismic vulnerability of bridges

Yilmaz, Taner,Banerjee, Swagata Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.4

Multiple hazards (multihazard) conditions may cause significant risk to structures that are originally designed for individual hazard scenarios. Such a multihazard condition arises when an earthquake strikes to a bridge pre-exposed to scour at foundations due to flood events. This study estimates the impact spectrum of flood-induced scour on seismic vulnerability of bridges. Characteristic river-crossing highway bridges are formed based on the information obtained from bridge inventories. These bridges are analyzed under earthquake-only and the abovementioned multihazard conditions, and bridge fragility curves are developed at component and system levels. Research outcome shows that bridges having pile shafts as foundation elements are protected from any additional seismic vulnerability due to the presence of scour. However, occurrence of floods can increase seismic fragility of bridges at lower damage states due to the adverse impact of scour on bridge components at superstructure level. These findings facilitate bridge design under the stated multihazard condition.

Reliability-based approach for fragility assessment of bridges under floods

Raj Kamal Arora,Swagata Banerjee 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.4

Riverine flood is one of the critical natural threats to river-crossing bridges. As floods are the most-occurred natural hazard worldwide, survival probability of bridges due to floods must be assessed in a speedy but precise manner. In this regard, the paper presents a reliability-based approach for a rapid assessment of failure probability of vulnerable bridge components under floods. This robust method is generic in nature and can be applied to both concrete and steel girder bridges. The developed methodology essentially utilizes limit state performance functions, expressed in terms of capacity and flood demand, for probable failure modes of various vulnerable components of bridges. Advanced First Order Reliability Method (AFORM), Monte Carlo Simulation (MCS), and Latin Hypercube Simulation (LHS) techniques are applied for the purpose of reliability assessment and developing flood fragility curves of bridges in which flow velocity and water height are taken as flood intensity measures. Upon validating the proposed method, it is applied to a case study bridge that experiences the flood scenario of a river in Gujarat, India. Research outcome portrays how effectively and efficiently the proposed reliability-based method can be applied for a quick assessment of flood vulnerability of bridges in any flood-prone region of interest.