Monte Carlo study on the self-assembly of nanoparticles into a nanorod structure.

Matin, Mohammad A,Kim, Hyojeong,Saha, Joyanta K,Zhang, Zhengqing,Kim, Jinkwon,Jang, Joonkyung American Scientific Publishers 2013 Journal of nanoscience and nanotechnology Vol.13 No.9

<P>It is well known that semiconductor nanoparticles (NPs) can assemble into a range of low dimensional structures, such as nanowires, nanorods and nanosheets. In this study, we investigate the self-assembly of CdTe NPs by using Monte Carlo simulation. Using a simple model for the anisotropic interaction of NPs, the present Monte Carlo simulation demonstrated that NPs with large dipole moments assemble spontaneously into a nanorod even if the short range interactions among NPs is isotropic. Interestingly, we found that the present nanorod grew by forming a transient structure which looks similar to a double ring. For NPs similar to CdTe, the dipole-dipole interaction had a dominant effect over van der Waals attractions and steric repulsion on the final structure of the NP aggregates. The simulated rods are similar to those observed in the experimental self-assembly of CdTe NPs. The NPs with relatively small electric dipole moments aggregated into more or less isotropic structures.</P>

Origin of Poor Thermal Stability of HDDR-Treated Nd-Fe-B-Type Material

Matin, Md Abdul,Hae-Woong Kwon,Jung-Goo Lee,Ji-Hun Yu IEEE 2014 IEEE transactions on magnetics Vol.50 No.1

<P>Thermal stability of the Nd<SUB>12.5</SUB>Fe<SUB>80.6</SUB>B<SUB>6.4</SUB>Ga<SUB>0.3</SUB>Nb<SUB>0.2</SUB> hydrogenation, disproportionation, desorption and recombination (HDDR)-treated powder was studied, and it was correlated to the residual hydrogen in the powder. Presence of the residual hydrogen in the HDDR-treated powder was investigated by X-ray diffraction (XRD), thermopiezic analyser (TPA) and hydrogen analysis. The HDDR-treated material contained a significant amount of hydrogen, and it influenced the thermal stability of the material. Coercivity of the HDDR-treated powder was markedly reduced by heating above 600 <SUP>°</SUP>C, and it was related to the residual hydrogen. The residual hydrogen existed in the form of Nd<SUB>2</SUB>Fe<SUB>14</SUB>BHx hydride, and it was disproportionated into α-Fe, Fe<SUB>2</SUB>B and NdH<SUB>2</SUB> phases at an elevated temperature. The coercivity reduction was attributed to the magnetically soft α-Fe and Fe<SUB>2</SUB>B phases formed by the disproportionation.</P>

Sonochemical synthesis of Pt-doped Pd nanoparticles with enhanced electrocatalytic activity for formic acid oxidation reaction

Matin, Md. Abdul,Jang, Ji-Hoon,Lee, Eunjik,Kwon, Young-Uk Springer-Verlag 2012 Journal of applied electrochemistry Vol.42 No.10

Rational syntheses of core-shell Fe@(PtRu) nanoparticle electrocatalysts for the methanol oxidation reaction with complete suppression of CO-poisoning and highly enhanced activity

Matin, Md. Abdul,Lee, Eunjik,Kim, Hyunchul,Yoon, Won-Sub,Kwon, Young-Uk The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.33

<P>We report the syntheses of ternary nanoparticles (NPs) of Fex@(PtRu)(1−x)/2(<I>x</I>= 0.0, 0.30, 0.34, 0.38, and 0.44) with Fe cores and PtRu alloy shells, which exhibit greatly improved electrocatalytic properties for the methanol oxidation reaction (MOR). The syntheses were achieved by one-step sonochemical treatments of Pt(acac)2, Ru(acac)3, and Fe(acac)3in ethylene glycol. The NPs are characterized by X-ray diffractometry, transmission electron microscopy (TEM), and inductively coupled plasma-adsorption emission spectroscopy for the particle size, morphology, and composition, respectively. The formation of core-shell NPs has been proven by scanning TEM-energy dispersive X-ray spectroscopy, and the electronic structures of the elements have been investigated by X-ray photoelectron spectroscopy and X-ray adsorption near edge spectroscopy. The ternary NPs show enhanced MOR electrocatalytic activity compared to a commercial PtRu-alloy (PtRu) by a factor of up to 2.5 based on the forward current density data. More importantly, the ternary NPs show complete suppression of CO-poisoning. Chronoamperometry data for MOR on the ternary NPs show improved stability over Pt/C and PtRu references.</P>

Phenotypic and Genotypic Analysis of Rice Lesion Mimic Mutants

Matin, Mohammad Nurul,Pandeya, Devendra,Baek, Kwnag-Hyun,Lee, Dong-Sun,Lee, Jai-Heon,Kang, Ho-Duck,Kang, Sang-Gu The Korean Society of Plant Pathology 2010 Plant Pathology Journal Vol.26 No.2

Lesion mimic mutant (LMM) plants display spontaneous necrotic lesions on their leaves without any pathogenic infection. Specific rice LMMs designated as spotted leaf (spl) including spl1, spl3, spl4, spl5 and spl6 are genetically known as lesion resembling disease (lrd) mutant. The inheritance patterns in the $F_1$ and $F_2$ progenies of these mutants are controlled by recessive genetic factors. Lesion development in the rice LMMs were controlled by both development stages and environmental factors. The rice LMMs exhibited higher numbers of spots under $45^{\circ}C$ temperature than those under $30^{\circ}C$. Contents of chlorophyll were drastically reduced at 60 days old LMM leaves when the spot formation was severe. The levels of endogenous hydrogen peroxide were highest at 45 days old mutants but reduced at 60 days old. Transcription levels of stress related genes including thioredoxin peroxidase and protein disulfide isomerase were reduced in spotted leaves than those of non spotted leaves. It could be suggested that scavenging system against reactive oxygen species induced by either stresses or innate metabolisms may not work properly in the rice LMMs. As these rice LMMs autonomously expressed clear lesions of lrd phenotype without pathogen infection, it could be useful to understand stresses responses in plants.

Theoretical Calculations of Infrared Bands of CH₃⁺ and CH₅⁺

Matin, Mohammad A.,Jang, Joonkyung,Park, Seung Min Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.7

Existing theoretical calculations predict that infrared spectra of the two most fundamental reactive carbo-ions, methyl cation $CH{_3}^+$ with $D_{3h}$ symmetry and protonated methyl cation $CH{_5}^+$ with $C_s(I)$, $C_s(II)$, and $C_{2v}$ symmetries, appear together in the 7-${\mu}m$ region corresponding to the C-H bending modes. Vibrational band profiles of $CH{_3}^+$ and $CH{_5}^+$ have been compared by ab initio calculation methods that use the basis sets of MP2/aug-cc-pVTZ and CCSD(T)/cc-pVTZ. Our results indicate that the bands of rotation-vibration transitions of $CH{_3}^+$ and $CH{_5}^+$ should overlap not only in the 3-${\mu}m$ region corresponding to the C-H stretching modes but also in the 7-${\mu}m$ region corresponding to the C-H bending modes. Five band intensities of $CH{_5}^+$ among fifteen vibrational transitions between 6 and 8 ${\mu}m$ region are stronger than those of the ${\nu}_2$ and ${\nu}_4$ bands in $CH{_3}^+$. Ultimate near degeneracy of the two bending vibrations ${\nu}_2$ and ${\nu}_4$ of $CH{_3}^+$along with the stronger intensities of $CH{_5}^+$ in the three hydrogen scrambling structures may cause extreme complications in the analysis of the high-resolution carbo-ion spectra in the 7-${\mu}m$ region.

Ferutinin, an Apoptosis Inducing Terpenoid from Ferula ovina

Matin, Maryam Moghaddam,Nakhaeizadeh, Hossein,Bahrami, Ahamd Reza,Iranshahi, Mehrdad,Arghiani, Nahid,Rassouli, Fatemeh Behnam Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.5

A current hurdle in cancer management is the intrinsic or acquired resistance of cancer cells to chemical agents that restricts the efficacy of therapeutic strategies. Accordingly, there is an increasing desire to discover new natural compounds with selective toxicity to combat malignancies. In present study, the cytotoxic and apoptosis-inducing activities of ferutinin, a terpenoid derivative from Ferula ovina, were investigated on human breast (MCF7) and bladder (TCC) cancer cells as well as normal fibroblasts (HFF3).The toxicity and DNA damage inducing effects of ferutinin were studied by MTT and comet assays, DAPI and PI staining and DNA laddering. The $IC_{50}$ values of ferutinin were identified and compared with routine prescribed drugs, doxorubicin and vincristine, by MTT test. Alkaline comet assay and DAPI staining revealed DNA damage due to ferutinin, which was significantly (p<0.001) higher in MCF7 and TCC than HFF3 cells. Apoptosis induction was evidenced by PI staining and DNA laddering. Our results suggest that ferutinin could be considered as an effective anticancer agent for future in vivo and clinical experiments.

Density Functional Theory Study on the Cross-Linking of Mussel Adhesive Proteins

Matin, Mohammad A.,Chitumalla, Ramesh Kumar,Lim, Manho,Gao, Xingfa,Jang, Joonkyung American Chemical Society 2015 The Journal of physical chemistry B Vol.119 No.17

<P>The water-resistant adhesion of mussel adhesive proteins (MAPs) to a wet surface requires a cross-linking step, where the catecholic ligands of MAPs coordinate to various transition-metal ions. Fe(III), among the range of metal ions, induces particularly strong cross-linking. The molecular details underlying this cross-linking mediated by transition-metal ions are largely unknown. Of particular interest is the metal–ligand binding energy, which is the molecular origin of the mechanical properties of cross-linked MAPs. Using density functional theory, this study examined the structures and binding energies of various trivalent metal ions (Ti–Ga) forming coordination complexes with a polymeric ligand similar to a MAP. These binding energies were 1 order of magnitude larger than the physisorption energy of a catechol molecule on a metallic surface. On the other hand, the coordination strength of Fe(III) with the ligand was not particularly strong compared to the other metal ions studied. Therefore, the strong cross-linking in the presence of Fe(III) is ascribed to its additional ability as an oxidant to induce covalent cross-linking of the catecholic groups of MAPs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2015/jpcbfk.2015.119.issue-17/acs.jpcb.5b01152/production/images/medium/jp-2015-011524_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b01152'>ACS Electronic Supporting Info</A></P>

Developing Operating Rules for Conjunctive Use of Surface and Groundwater Considering the Water Quality Issues

Matin Rafipour-Langeroudi,Reza Kerachian,Mohammad Reza Bazargan-Lari 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.2

This paper presents a new methodology for developing operating rules for conjunctive use of surface and groundwater. BayesianNetworks-based operating rules are trained and verified using the results of a multi-objective optimization model. Reduction ofpumping costs, improving the groundwater quality, water supply with acceptable quality and controlling the groundwater tablefluctuations are considered as objective functions of the optimization model. In order to provide Pareto fonts among these conflictingobjectives, the combination of MODFLOW and MT3D groundwater quantity and quality simulation models and Non-dominatedSorting Genetic Algorithm II (NSGA-II) are used. The best solutions on the Pareto fronts, which are selected using the Young andNash bargaining theories, are used to train and verify Bayesian Networks (BNs). In real-time water allocation from surface andgroundwater resources, the BNs-based rules can be used without any need to run the time consuming optimization and conflictresolution models. The proposed methodology is applied to the conjunctive use of water resources in the Tehran region, Iran. Theresults show that using the operating rules can improve the groundwater quality and control the groundwater table fluctuations in thestudy area.

Comparative Phenotypic and Physiological Characteristics of Spotted Leaf 6 (spl6) and Brown Leaf Spot2 (bl2) Lesion Mimic Mutants (LMM) in Rice

Matin, Mohammad Nurul,Saief, Saifullah Ahmed,Rahman, Mohammad Mominur,Lee, Dong-Hoon,Kang, Ho-Duck,Lee, Dong-Sun,Kang, Sang-Gu Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.30 No.6

Spontaneous necrotic lesions were found in a lesion mimic mutant brown leaf spot 2 (bl2) without pathogenic infection. Small spots in the seedlings appeared at the four leaves stage and gradually grew into a large round and black area with a gray center on the leaf surfaces. Lower growth habit and lower agronomic trait values with reduced stature, tiller, and panicle number, as well as lower yield potential were noted in the mutants relative to the trait values of the wild-type plants. Microscopic analysis revealed that mesophyll chloroplast was severely damaged or absent in the spotted area of the mutant leaves. Total chlorophyll content, hydrogen peroxide level, and catalase activity were increased at up to 45 days after germination and were dropped at 60 d in the mutant leaves. However, the total protein contents were reduced slightly with a growth period of up to 45 days and were increased at 60 days after germination. A gradual increment of the total ascorbic acid contents in the mutants were observed with advanced plant age, but increased until 45 days and dropped comparatively at 60 days in the wild-type leaves. Increased gene transcriptions of OsPDI and OsGPX1 were noted in the spotted leaves as compared to the nons-potted leaves of the mutant and wild-type leaves, whereas transcripts of OsTPX were transcribed at lower levels in the spotted leaves as compared to the non-spotted leaves. The genetic nature of the bl2 mutant indicated that the $F_1$ plants evidenced the wild-type phenotype and that bl2 was governed by a single recessive gene.