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Substrate effects on the microstructure of hydrogenated amorphous carbon films
I. Ahmad,S.S. Roy,Md.A. Rahman,T.I.T. Okpalugo,P.D. Maguire,J.A. McLaughlin 한국물리학회 2009 Current Applied Physics Vol.9 No.5
In this work, plasma enhanced chemical vapour deposition was used to prepare hydrogenated amorphous carbon films (a-C:H) on different substrates over a wide range of thickness. In order to observe clear substrate effect the films were produced under identical growth conditions. Raman and near edge X-ray absorption fine structure (NEXAFS) spectroscopies were employed to probe the chemical bonding of the films. For the films deposited on silicon substrates, the Raman ID/IG ratio and G-peak positions were constant for most thickness. For metallic and polymeric substrates, these parameters increased with film thickness, suggesting a change from a sp3-bonded hydrogenated structure to a more sp2 network, NEXAFS results also indicate a higher sp2 content of a-C:H films grown on metals than silicon. The metals, which are poor carbide precursors, gave carbon films with low adhesion, easily delaminated from the substrate. The delamination can be decreased/eliminated by deposition of a thin ( ~10 nm) silicon layer on stainless steel substrates prior to a-C:H coatings. Additionally we noted the electrical resistivity decreased with thickness and higher dielectric breakdown strength for a-C:H on silicon substrate.
Jehad Fataftah,Justin Z,Amarin,Haya H,Suradi,Maher T,Hadidi,Amjad T,Shatarat,Abdel Rahman A,Al Manasra,Samah Shahin,Darwish H,Badran 대한해부학회 2020 Anatomy & Cell Biology Vol.53 No.3
Our aim was to investigate the variation in the vertebral levels of the origins of the celiac artery, superior and inferior mesenteric arteries, paired renal arteries, and common iliac arteries. We conducted a retrospective imaging study in a large public secondary hospital on a nonrandom sample of 227 participants. We consecutively included adult patients who had undergone computed tomography angiography of the abdomen and excluded patients with a history of any vertebral abnormality or whose images revealed evidence of a vertebral abnormality or a congenital anomaly of any of the branches of the abdominal aorta. The primary outcome was the frequency distribution of the vertebral levels of the landmarks. The secondary outcomes were the intercorrelations of the vertebral levels of the landmarks and their relationships with age, sex, weight, height, and body mass index. The celiac artery originated at T11/T12-L1/L2, followed by the superior mesenteric artery at T12-L2, the paired renal arteries at T12/L1-L2/L3, the inferior mesenteric artery at L2-L4, and the common iliac arteries at L3-L5. The vertebral levels of the landmarks were positively intercorrelated and stronger between proximate pairs. In addition, the vertebral levels of the landmarks were related to age, but not sex, weight, height, or body mass index. The intercorrelations suggest that a considerable proportion of the variation is accounted for by ‘trickle-down’ variation; variation in the vertebral level of a proximal landmark results in variation in the vertebral level of the immediate distal landmark. The overarching parameter remains unidentified.
A.T.M. Mijanur Rahman,정승원,최동열,고상훈,이승주 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.5
In the present study, a new microbial TTI system was developed based on encapsulation techniques. TTI response (color change) was evaluated by using primarily the CIELab coordinates which were further used for the conversion into the secondary and tertiary variables and finally compared all the variables to choose the best ones for calculation of activation energy (Ea) quickly and accurately. In order to select the best variables for calculating the Ea, 95% confidence interval was also used. Primary variable a* exhibited the best linearity, narrowest 95% confidence interval and simplicity in interpretation of the color-developing reaction. Ea of the developed microbial TTIs ranged from 57.28 to 110.23 kJ/mol and maintains a consistent performance similar to that of other microbial and nonmicrobial TTIs which are commercially available. Therefore, it can be concluded that this new microbial TTI system can be used effectively in the food industry for monitoring food quality.
Rahman, T.,Rahman, K.A.,Rajia, S.,Alamgir, M.,Khan, Mahmud T.H.,Choudhuri, M. Shahabuddin K. Kyung Hee Oriental Medicine Research Center 2010 Oriental pharmacy and experimental medicine Vol.10 No.2
Two common Indian spices Carum copticum Karst (ajowan) and Cinnamomum tamala T.Nees. (bay leaves) has been investigated first time to report the activity on the central nervous system. Preliminary study of the hot water extract showed depressant activity on the hole board test as evidenced from the ambulation and head dipping scores. The extracts further quicken the onset and increased the duration of pentobarbital induced sleeping time.
Rahman, J.U.,Hussain, A.,Maqbool, A.,Ryu, G.H.,Song, T.K.,Kim, W.J.,Kim, M.H. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.593 No.-
Lead-free (0.935-x)[Bi<SUB>0.5</SUB>Na<SUB>0.5</SUB>TiO<SUB>3</SUB>-0.065BaTiO<SUB>3</SUB>]-xBaZrO<SUB>3</SUB> (BNBT-xBZ, with x=0-0.07) ceramics were prepared by a conventional solid-state reaction method. The effect of BZ addition on the crystal structure, microstructure, dielectric, ferroelectric and electric field induced strain behavior of BNBT ceramic was investigated. X-ray diffraction patterns of BNBT-xBZ ceramics revealed the formation of single phase perovskite structure in the studied composition range. Addition of BZ in BNBT transform the crystal structure from tetragonal to pseudocubic symmetry. However, with increasing BZ content, the maximum dielectric constant decreased and the dielectric maximum temperature (T<SUB>m</SUB>) shifted towards lower temperature. The field induced strain response of BNBT-xBZ increases from 0.16% for x=0 to 0.38% for x=0.03, at an applied field of 7kV/mm. The corresponding dynamic piezoelectric coefficient for these composition were (S<SUB>max</SUB>/E<SUB>max</SUB>=231pm/V) and (S<SUB>max</SUB>/E<SUB>max</SUB>=542pm/V), respectively. These results suggest that the BNBT-0.03BZ ceramic can be considered as a promising candidate material for piezoelectric application.
A. Zeeshan,H. F. Ismael,M. A. Yousif,T. Mahmood,S. U. Rahman Korean Magnetics Society 2018 Journal of Magnetics Vol.23 No.4
Effects of the uniform magnetic field on aqueous magneto-Nanofluid confined in a porous domain with wall stretching/shrinking non-linearly is analyzed via this communication. The problem is modeled using continuity, momentum and energy equation along with linear thermal radiation. The effects of physical quantities are observed for Cu, Al₂O₃, TiO₂ and Ag particles in water. The coupled boundary layer PDE’s are reduced into the system of ODEs by utilizing similarity transformation and solved using shooting and Runga-Kutta fourth order technique. Stability of the obtained results are also analyzed. The results are displayed through graphs. It is observed that the momentum boundary layer is thicker when silver particles are introduced in water. Whereas, temperature profile has the minimum value for silver nanoparticles and maximum for Titanium dioxide. Also, in case of shrinking sheet dual solutions are obtained along with smallest Eigen values.
Kang, You Jin,Kang, Jin-Won,Choi, Jung-Hwa,Park, Soo Yeon,Rahman, A.T.M. Mijanur,Jung, Seung Won,Lee, Seung Ju The Korean Society for Applied Biological Chemistr 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.6
Kimchi, in factories or during transportation, is usually stacked on shelves at different heights, which affects temperature and thus kimchi quality. In this study, a time-temperature indicator (TTI) was used to control such quality variations. A case study was conducted to evaluate the validity of using the TTI; one group of small packages of young kimchi had the TTI attached whereas the other group did not. They were stored on shelves of different heights (i.e., top, middle, and bottom) in a laboratory fermentor. The samples with TTIs were individually fermented until the color of the TTIs reached a threshold level, whereas the samples without TTIs were collectively fermented for a predetermined time at a given temperature. The qualities of fermented samples including pH, acidity, microbial counts, and reducing sugars were analyzed. The samples with TTIs had more uniform qualities that were closer to the targets than those without TTIs. These results suggest that TTIs are practical tools to control kimchi quality in terms of temperature variation.
강윤진,강진원,최정화,박수연,A.T.M. Mijanur Rahman,정성원,이성주 한국응용생명화학회 2014 Applied Biological Chemistry (Appl Biol Chem) Vol.57 No.6
Kimchi, in factories or during transportation, is usuallystacked on shelves at different heights, which affects temperatureand thus kimchi quality. In this study, a time-temperature indicator(TTI) was used to control such quality variations. A case studywas conducted to evaluate the validity of using the TTI; one groupof small packages of young kimchi had the TTI attached whereasthe other group did not. They were stored on shelves of differentheights (i.e., top, middle, and bottom) in a laboratory fermentor. The samples with TTIs were individually fermented until thecolor of the TTIs reached a threshold level, whereas the sampleswithout TTIs were collectively fermented for a predeterminedtime at a given temperature. The qualities of fermented samplesincluding pH, acidity, microbial counts, and reducing sugars wereanalyzed. The samples with TTIs had more uniform qualities thatwere closer to the targets than those without TTIs. These resultssuggest that TTIs are practical tools to control kimchi quality interms of temperature variation.
( A. T. M. Mijanur Rahman ),( Seung Ju Lee ),( Seung Won Jung ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.12
A comparative study was conducted to evaluate precision and accuracy in controlling the temperature dependence of encapsulated microbial time-temperature integrators (TTIs) developed using two different emulsification techniques. Weissela cibaria CIFP 009 cells, immobilized within 2% Na-alginate gel microbeads using homogenization (5,000, 7,000, and 10,000 rpm) and Shirasu porous glass (SPG) membrane technologies (10 μm), were applied to microbial TTIs. The prepared micobeads were characterized with respect to their size, size distribution, shape and morphology, entrapment efficiency, and bead production yield. Additionally, fermentation process parameters including growth rate were investigated. The TTI responses (changes in pH and titratable acidity (TA)) were evaluated as a function of temperature (20℃, 25℃, and 30℃). In comparison with conventional methods, SPG membrane technology was able not only to produce highly uniform, small-sized beads with the narrowest size distribution, but also the bead production yield was found to be nearly 3.0 to 4.5 times higher. However, among the TTIs produced using the homogenization technique, poor linearity (R(2)) in terms of TA was observed for the 5,000 and 7,000 rpm treatments. Consequently, microbeads produced by the SPG membrane and by homogenization at 10,000 rpm were selected for adjusting the temperature dependence. The Ea values of TTIs containing 0.5, 1.0, and 1.5 g microbeads, prepared by SPG membrane and conventional methods, were estimated to be 86.0, 83.5, and 76.6 kJ/mol, and 85.5, 73.5, and 62.2 kJ/mol, respectively. Therefore, microbial TTIs developed using SPG membrane technology are much more efficient in controlling temperature dependence.