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Strength of a 3D Printed Al 7068 Alloy Under Micro-Pillar Compression
Thamer Tabbakh,Saeed Alshihri,A. K. Basak,Abdulaziz Kurd 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
The present work investigates the mechanical properties of as-built laser powder bed fusion (L-PBF) Aluminium 7068 alloys,together with microstructural characterization. To achieve this, micro-pillar compression (in-situ) was conducted and thestate of the materials under compression were correlated with respective stress–strain curves. A cast alloy of similar bulkcomposition was also investigated, under identical conditions, as a benchmark material. As opposed to the larger sphericalgrains (about 4 μm) of the cast alloy, the L-PBF alloy exhibited typical ‘melt pool’ meso-structure, combined with refinedmicrostructure induced by rapid cooling and gave rise to sub-micron range grain sizes. The mechanical properties of theL-PBF alloy are anisotropic in nature, due to its bi-modal type meso- and micro-structure. Cross-sectional SEM investigationwas carried out on deformed micro-pillars and revealed that there exist numerous slip and shear plane networks that servedas load accommodation mechanism during compression.
Ordu, Cetin,Selcuk, Nalan A.,Akosman, Cengiz,Eren, Orhan Onder,Altunok, Elif C.,Toklu, Turkay,Oyan, Basak Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.1
Background: The aim of this study was to explore the prognostic role of metabolic response to chemotherapy, determined by FDG-PET, in patients with metastatic non-small-cell lung cancer (NSCLC). Materials and Methods: Thirty patients with metastatic NSCLC were analyzed for prognostic factors related to overall survival (OS) and progression free survival (PFS). Disease evaluation was conducted with FDG-PET/CT and contrast-enhanced CT prior to and at the end of first-line chemotherapy. Response evaluation of 19 of 30 patients was also performed after 2-3 cycles of chemotherapy. Morphological and metabolic responses were assessed according to RECIST and PERCIST, respectively. Results: The median OS and PFS were 11 months and 6.2 months, respectively. At the end of first-line chemotherapy, 10 patients achieved metabolic and anatomic responses. Of the 19 patients who had an interim response analysis after 2-3 cycles of chemotherapy, 3 achieved an anatomic response, while 9 achieved a metabolic response. In univariate analyses, favorable prognostic factors for OS were number of cycles of first-line chemotherapy, and achieving a response to chemotherapy at completion of therapy according to the PERCIST and RECIST. The OS of patients with a metabolic response after 2-3 cycles of chemotherapy was also significantly extended. Anatomic response at interim analysis did not predict OS, probably due to few patients with anatomic response. In multivariate analyses, metabolic response after completion of therapy was an independent prognostic factor for OS. Conclusions: Metabolic response is at least as effective as anatomic response in predicting survival. Metabolic response may be an earlier predictive factor for treatment response and OS in NSCLC patients.
Aberration in the structural paradigm of lens protein α crystallin by UV-C irradiation
R. K. Ghosh,T. Kar,B. Dutta,A. Pathak,R. Rakshit,R. Basak,A. Das,K. Waheeda,P. Basak,M. Bhattacharyya 한국응용생명화학회 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.3
The conformation of lens protein α crystallin was investigated using different spectroscopic techniques under normal and UV-C-irradiated condition. The structural elucidation of commercially available lens protein α crystallin under the effects of UV-C irradiation has never been reported earlier. To study the effects of irradiation on the lens protein, we used UV–visible spectroscopy, CD spectroscopy, and steady-state and time-resolved fluorescence measurements along with FTIR study, under increasing doses of UV-C irradiation. Using the secondary and tertiary structural changes as parameters for detecting conformational perturbation, we investigated the structural paradigm shift in the lens protein α crystallin. Increasing doses of UV-C radiation resulted in decreasing β sheet content of α crystallin from 30 to 10%. The fluorescence profile confirmed the formation of ROS species in the protein upon extensive exposure to UV-C irradiation. These results inferred UV-C irradiation may induce alteration of secondary structure of the lens protein leading to impaired biological functioning.
Aberration in the structural paradigm of lens protein α crystallin by UV-C irradiation
Ghosh, R.K.,Kar, T.,Dutta, B.,Pathak, A.,Rakshit, R.,Basak, R.,Das, A.,Waheeda, K.,Basak, P.,Bhattacharyya, M. The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.3
The conformation of lens protein ${\alpha}$ crystallin was investigated using different spectroscopic techniques under normal and UV-C-irradiated condition. The structural elucidation of commercially available lens protein ${\alpha}$ crystallin under the effects of UV-C irradiation has never been reported earlier. To study the effects of irradiation on the lens protein, we used UV-visible spectroscopy, CD spectroscopy, and steady-state and time-resolved fluorescence measurements along with FTIR study, under increasing doses of UV-C irradiation. Using the secondary and tertiary structural changes as parameters for detecting conformational perturbation, we investigated the structural paradigm shift in the lens protein ${\alpha}$ crystallin. Increasing doses of UV-C radiation resulted in decreasing ${\beta}$ sheet content of ${\alpha}$ crystallin from 30 to 10%. The fluorescence profile confirmed the formation of ROS species in the protein upon extensive exposure to UV-C irradiation. These results inferred UV-C irradiation may induce alteration of secondary structure of the lens protein leading to impaired biological functioning.
Stange, Daniel E.,Koo, B.K.,Huch, M.,Sibbel, G.,Basak, O.,Lyubimova, A.,Kujala, P.,Bartfeld, S.,Koster, J.,Geahlen, Jessica H.,Peters, Peter J.,van Es, Johan H.,van de Wetering, M.,Mills, Jason C.,Cle Cell Press ; MIT Press 2013 Cell Vol.155 No.2
Proliferation of the self-renewing epithelium of the gastric corpus occurs almost exclusively in the isthmus of the glands, from where cells migrate bidirectionally toward pit and base. The isthmus is therefore generally viewed as the stem cell zone. We find that the stem cell marker Troy is expressed at the gland base by a small subpopulation of fully differentiated chief cells. By lineage tracing with a Troy-eGFP-ires-CreERT2 allele, single marked chief cells are shown to generate entirely labeled gastric units over periods of months. This phenomenon accelerates upon tissue damage. Troy<SUP>+</SUP> chief cells can be cultured to generate long-lived gastric organoids. Troy marks a specific subset of chief cells that display plasticity in that they are capable of replenishing entire gastric units, essentially serving as quiescent ''reserve'' stem cells. These observations challenge the notion that stem cell hierarchies represent a ''one-way street.''
M. Imani,E. Dastanpoor,M. H. Enayati,A. K. Basak 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
Mechanical alloying (MA) of Ni and P powders containing 20 and 12 wt% P was investigated. The structural changes ofalloys during mechanical alloying were studied by X-ray diffractometry and transmission electron microscopy. The resultsshowed that the interdiffusion of Ni and P elements during MA of Ni80P20alloy leads to the development of Ni12P5and Ni2Pintermetallic compounds. However MA of the Ni88P12alloy leads to the formation of an intermetallic compound (Ni3P)and a solid solution (α-Ni) as well as partially amorphous structure. Intermediate annealing of MAed Ni88P12alloy doesnot promote the formation of fully amorphous structure. Furthermore, thermodynamic analysis using the Miedema’s semiempiricalmodel showed that the intermetallic phases are the most stable phases in Ni88P12and Ni80P20alloys during MA.