Fibrous Dysplasia Mimicking Bone Metastasis on Both Bone Scintigraphy and $^{18}F$-FDG PET-CT: Diagnostic Dilemma in a Patient with Breast Cancer

Suman K.C., Sudhir,Sharma, Punit,Singh, Harmandeep,Bal, Chandrasekhar,Kumar, Rakesh The Korea Society of Nuclear Medicine 2012 핵의학 분자영상 Vol.46 No.4

AC impedance spectroscopic studies of transport properties in metal oxide doped α-NPD

C.K. Suman,Jinyoung Yun,Seohee Kim,Sin-Doo Lee,이창희 한국물리학회 2009 Current Applied Physics Vol.9 No.5

The potential application of molecular organic semiconductor needs the control adjustment of conductivity. The hole transport materials (HTL)α-NPD(N,N'-di(1-naphthyl)-N,N'-diphenylbenzidin) has been doped with metal oxide (molybdenum oxide) for the study of transport phenomena. Impedance spectroscopic measurements were performed with the applied external electric filed. The activation energy calculated (0.55, 0.48 and 0.50 eV) decreases with doping of metal oxide. There is a clear indication of space charge limited (SCL) conduction in the doped and undoped thin films. The cole–cole plot indicates the device can be represented by a parallel resistance and capacitance network in series with a series resistance (of 70 Ω). At high frequency; the conduction follows the universal power law for both doped–undoped α-NPD with MoO3 and the onset frequency increases with increasing bias voltages. The conduction mechanism can be explained by classical hopping barriers (CHB) mechanism for the system.

Temperature dependent transport properties in molybdenum oxide doped α-NPD

Suman, C.K.,Yang, Jungjin,Lee, Changhee Elsevier 2010 Materials science and engineering B. Advanced Func Vol.166 No.2

<P><B>Abstract</B></P><P>The temperature dependent transport properties of molybdenum oxide (MoO<SUB>3</SUB>) doped <I>N</I>,<I>N</I>′-di(1-naphthyl)-<I>N</I>,<I>N</I>′-diphenylbenzidin (α-NPD) were studied over a frequency range of 100Hz to 1MHz. The value of trap density and mobility calculated by detailed analysis of <I>current–voltage</I> (<I>I</I>–<I>V</I>) characteristics are 9.43×10<SUP>26</SUP>m<SUP>−3</SUP> and 1.23×10<SUP>−6</SUP>cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>, respectively. The relaxation time for the carriers in the bulk and in the interface region decreases with temperature. The Cole–Cole plot indicates the device can be modeled as the combination of two parallel resistor–capacitor (<I>R</I>–<I>C</I>) circuits with a series resistance of around 70Ω. The dc conductivity shows two different regions in the studied temperature range with activation energy of <I>E</I><SUB><I>a</I></SUB>∼0.107eV (region I) and <I>E</I><SUB><I>a</I></SUB>∼52meV (region II), respectively. The ac conductivity follows the universal power law and the onset frequency increases with increase of temperature. The temperature dependent conduction mechanism can be explained by correlated hopping barrier (CBH) model.</P>

AC impedance spectroscopic studies of transport properties in metal oxide doped α-NPD

Suman, C.K.,Yun, Jinyoung,Kim, Seohee,Lee, Sin-Doo,Lee, Changhee Elsevier 2009 Current Applied Physics Vol.9 No.5

<P><B>Abstract</B></P><P>The potential application of molecular organic semiconductor needs the control adjustment of conductivity. The hole transport materials (HTL) α<B>-</B>NPD (<I>N</I>,<I>N′</I>-di(1-naphthyl)-<I>N</I>,<I>N</I>′-diphenylbenzidin) has been doped with metal oxide (molybdenum oxide) for the study of transport phenomena. Impedance spectroscopic measurements were performed with the applied external electric filed. The activation energy calculated (0.55, 0.48 and 0.50eV) decreases with doping of metal oxide. There is a clear indication of space charge limited (SCL) conduction in the doped and undoped thin films. The cole–cole plot indicates the device can be represented by a parallel resistance and capacitance network in series with a series resistance (of 70Ω). At high frequency; the conduction follows the universal power law for both doped–undoped α-NPD with MoO<SUB>3</SUB> and the onset frequency increases with increasing bias voltages. The conduction mechanism can be explained by classical hopping barriers (CHB) mechanism for the system.</P>

Electrical Impedance Studies of the Effect of a Buer Layer on Organic Bulk Hetrojunction Solar Cells

이창희,C. K. Suman,노승욱,김서희,이신두,이동구,박정호 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

The eect of a buffer layer on organic bulk hetrojunction solar cells of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester fullerene derivative (PCBM) has been studied using impedance spectroscopy in the frequency range between 100 Hz and 1 MHz. The buffer layer interfaces with a metallic contact and with the organic bulk materials in uence the efficiency and the stability of devices. Thermal annealing of the devices improves the interface with the buffer layer, thereby lowering the majority and the minority carrier injection voltage. The photocurrent density-voltage (J-V) characteristics show that the fill factor of the device with a molybdenum-oxide (MoO3) buffer layer is higher than that of the device with a poly (3, 4- ethylenedioxy-thiophene):polystyrenesulfonate (PEDOT:PSS) buffer layer. The equivalent circuit analysis for the PEDOT:PSS and the MoO3 buffer-layer devices shows that the device's capacitance and resistance for MoO3 is lower than that for PEDOT:PSS under illumination. The efficiency of the thermally-annealed PEDOT:PSS and MoO3 buffer-layer devices are 2.95 and 3.44 %, respectively. The lower efficiency of the PEDOT:PSS buer-layer devices can be attributed to the formation of a thin insulator layer at the PEDOT:PSS/P3HT:PCBM interface under illumination. The eect of a buffer layer on organic bulk hetrojunction solar cells of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester fullerene derivative (PCBM) has been studied using impedance spectroscopy in the frequency range between 100 Hz and 1 MHz. The buffer layer interfaces with a metallic contact and with the organic bulk materials in uence the efficiency and the stability of devices. Thermal annealing of the devices improves the interface with the buffer layer, thereby lowering the majority and the minority carrier injection voltage. The photocurrent density-voltage (J-V) characteristics show that the fill factor of the device with a molybdenum-oxide (MoO3) buffer layer is higher than that of the device with a poly (3, 4- ethylenedioxy-thiophene):polystyrenesulfonate (PEDOT:PSS) buffer layer. The equivalent circuit analysis for the PEDOT:PSS and the MoO3 buffer-layer devices shows that the device's capacitance and resistance for MoO3 is lower than that for PEDOT:PSS under illumination. The efficiency of the thermally-annealed PEDOT:PSS and MoO3 buffer-layer devices are 2.95 and 3.44 %, respectively. The lower efficiency of the PEDOT:PSS buer-layer devices can be attributed to the formation of a thin insulator layer at the PEDOT:PSS/P3HT:PCBM interface under illumination.

Effect of type-II quantum well of m-MTDATA/α-NPD on the performance of green organic light-emitting diodes

Yang, J.,Suman, C.K.,Lee, C. Elsevier 2009 Microelectronics Journal Vol.40 No.1

The type-II multiple quantum well (MQW) structure is prepared and introduced into green organic green light-emitting diodes consisting of 4,4'-bis-[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD) and tris-(8-hydroxyquinolinato)-aluminum (Alq<SUB>3</SUB>). The quantum well (QW) and wall are fabricated by 4,4',4''-tris-(3-methylphenylphenylamino)triphenylamine (m-MTDATA) and α-NPD, respectively. The device performance of MQW organic light-emitting diodes (OLEDs) has been improved; the luminous efficiency by 25% and power efficiency by 17% compared with the reference device. The performance improvement can be explained by the increased electron-hole balance in the device due to the hole confinement in the QW structure.

Carrier conduction mechanism for phosphorescent material doped organic semiconductor

Noh, Seunguk,Suman, C. K.,Hong, Yongtaek,Lee, Changhee American Institute of Physics 2009 JOURNAL OF APPLIED PHYSICS - Vol.105 No.3

Fabrication of transparent Al:LiF composite/MoO3 interconnecting layers for tandem white organic light emitting devices.

Yang, Jungjin,Suman, C K,Kim, Joonyoup,Song, Won-Jun,Wooh, Sanghyuk,Char, Kookheon,Lee, Changhee American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.8

<P>We report transparent Al:LiF composite/molybdenum oxides (MoO3) as interconnecting layers for tandem white organic light emitting diodes (WOLEDs) consisting of blue and red phosphorescent unit devices. The Al:LiF (3 nm)/MoO3 (10 nm) interconnecting layers show a high transmittance, good carrier generation and injection capability for tandem WOLEDs. The performance of tandem WOLEDs is sensitive to the LiF doping concentration, which is mainly attributed to the difference in efficiency of carrier injection into the adjoining electroluminescent units. For 10~20% LiF concentration, the external quantum efficiency of tandem device is almost equal to the sum of the efficiencies of blue and red OLEDs at high current density; furthermore, a small variation of Commission Internationale de l'Eclairage (CIE) coordinates with the current density is obtained.</P>

Isozymes of α-amylases from Newly Isolated Bacillus thuringiensis CKB19: Production from Immobilized cells

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.

Metabolic Profiling and Biological Activities of Bioactive Compounds Produced by Pseudomonas sp. Strain ICTB-745 Isolated from Ladakh, India

( Kamal ),( Ahmed ),( Anver Basha Shaik ),( C. Ganesh Kumar ),( Poornima Mongolla ),( P. Usha Rani ),( K. V. S ),( Rama Krishna ),( Suman Kumar Mamidyala ),( Joveeta Joseph ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.1

In an ongoing survey of the bioactive potential of microorganisms from Ladakh, India, the culture medium of a bacterial strain of a new Pseudomonas sp., strain ICTB-745, isolated from an alkaline soil sample collected from Leh, Ladakh, India, was found to contain metabolites that exhibited broad-spectrum antimicrobial and biosurfactant activities. Bioactivity-guided purification resulted in the isolation of four bioactive compounds. Their chemical structures were elucidated by 1H and 13C NMR, 2D-NMR (HMBC, HSQC, 1H,1H-COSY, and DEPT- 135), FT-IR, and mass spectroscopic methods, and were identified as 1-hydroxyphenazine, phenazine-1-carboxylic acid (PCA), rhamnolipid-1 (RL-1), and rhamnolipid-2 (RL-2). These metabolites exhibited various biological activities like antimicrobial and efficient cytotoxic potencies against different human tumor cell lines such as HeLa, HepG2, A549, and MDA MB 231. RL-1 and RL-2 exhibited a dose-dependent antifeedant activity against Spodoptera litura, producing about 82.06% and 73.66% antifeedant activity, whereas PCA showed a moderate antifeedant activity (63.67%) at 60 μg/cm2 area of castor leaf. Furthermore, PCA, RL-1, and RL-2 exhibited about 65%, 52%, and 47% mortality, respectively, against Rhyzopertha dominica at 20 μg/ml. This is the first report of rhamnolipids as antifeedant metabolites against Spodoptera litura and as insecticidal metabolites against Rhyzopertha dominica. The metabolites from Pseudomonas sp. strain ICTB-745 have interesting potential for use as a biopesticide in pest control programs.