bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Structures of μ3-Oxo-centered Mixed-valent Trinuclear Iron Complexes with 1-Methyl-imidazole Ligands
Authors: Dai Ji-Xiang , Wu Fang-Hui , Rothenberger Alexander , Zhang Qian-Feng
Published: February 2015

Treatment of the μ3-oxo-centered mixed-valent trinuclear iron complex [Fe3(μ3-O)(μ-OAc)6- (H2O)3] (1) in methanol solution with one, two, or three equivalents of 1-methyl-imidazole (C4H6N2) afforded the substitution products [Fe3(μ3-O)(μ-OAc)6(H2O)2(C4H6N2)] (2), [Fe3(μ3-O)(μ-OAc)6- (H2O)(C4H6N2)2] (3), and [Fe3(μ3-O)(μ-OAc)6(C4H6N2)3] (4), respectively. Complexes 2 - 4 were characterized by spectroscopic and elemental analyses, and the crystal structures of complexes 3 · 1.5MeOH· 2H2O and 4 have been determined by single-crystal X-ray diffraction. The results indicate that in 2 - 4 the trinuclear core unit [Fe3(μ3-O)(μ-OAc)6] of 1 is preserved.
Reactions of Nickel (II) Sulfate Hexahydrate with Methyl(2-pyridyl)ketone Oxime: Two Mononuclear Sulfato Complexes Containing the Neutral Ligand
Authors: Papatriantafyllopoulou Constantina , Raptopoulou Catherine P. , Terzis Aris , Janssens Jozef F. , Perlepes Spyros P. , Manessi-Zoupa Evy
Published: February 2015

The reactions of methyl(2-pyridyl)ketone oxime, (py)C(Me)NOH, with nickel(II) sulfate hexahydrate, in the absence of an external base, have been investigated. The reaction between equimolar quantities of NiSO4 ·6 H2O and (py)C(Me)NOH in H2O leads to the mononuclear complex [Ni(SO4){(py)C(Me)NOH}(H2O)3] ·H2O (1 ·H2O), while an excess of the organic ligand affords the 1 : 2 compound [Ni(SO4){(py)C(Me)NOH}2(H2O)] ·H2O (2 ·H2O). The structures of both compounds have been determined by single crystal X-ray diffraction. In both complexes the organic ligand chelates through its nitrogen atoms and the sulfate anion acts as a monodentate ligand. The thermal decomposition of complexes 1 ·H2O and 2 ·H2O has been studied. The IR data are discussed in terms of the nature of bonding and the structures of the two complexes.
Crystal Structure, Spectroscopic and Redox Properties of Copper(II) Bis{2-[(2,6-dimethylphenyl)iminomethyl-3-methoxyphenolate]}
Authors: Kasumov Veli T. , Uçar Ibrahim , Bulut Ahmet , Kösal Fevzi
Published: February 2015

The coordination chemistry of N-(2,6-di-methylphenyl)-2-hydroxy-3-methoxybenzaldimine (1) with Cu(II) has been investigated by X-ray crystallography, electronic and EPR spectroscopies, as well as by electro- and magnetochemistry. The title complex 2 crystallizes in the orthorhombic space group P212121 (a = 8.1538, b = 17.7466, c =19.8507 Å). The mononuclear square-planar molecules 2 featuring trans-N2O2 coordination are connected via weak intermolecular C-H· · ·π interactions into infinite chains parallel to the a axis. Although the intermolecular Cu· · ·Cu separations within individual chains and between chains are very long (8.154 and 9.726 Å ), the exchange interaction parameter G = 2.03 < 4, estimated from solid state EPR spectra, suggests the existence of long-distance superexchange pathways between adjacent Cu(II) centers. The electronic and electrochemical features of the compound are also discussed.
Structure and Fluorescent Properties of a Chiral Cd(II) Complex: Cd(bpy)(H2O)(PhCH=CHCO2)2
Authors: Wang Xian-Wen , Chen Jing-Zhong , Liu Jian-Hong
Published: February 2015

Reaction of Cd(CO3)2, cinnamic acid and 2,2 ' -bipyridine (bpy) in CH3OH/H2O afforded a new chiral Cd(II) complex, Cd(bpy)(H2O)(PhCH=CHCO2)2 (1). Single crystal X-ray analysis shows that complex 1 crystallizes in the monoclinic space group P21 with the cell dimensions: a = 10.081(2), b = 9.2657(19), c = 13.748(3) Å , β = 103.02(3)°, V = 1251.2(4) Å3, Z = 2. The seven-coordinated Cd atoms are in a severely distorted capped trigonal prism geometry. The complex molecules are assembled via strong O-H· · ·O hydrogen bonds into chains along the [010] direction. Complex 1 exhibits weak fluorescence in the solid state at r. t.
ScPtP und LaPtP – Zwei Phosphide mit ,,inverser“ TiNiSi-Struktur / ScPtP and LaPtP – Two Phosphides with “Inverse” TiNiSi-Type Structure
Authors: Imre Anette , Mewis Albrecht
Published: February 2015

Single crystals of ScPtP (orthorhombic, a = 6.437(1), b = 4.291(1), c = 7.550(2) Å ) were grown by reaction of the elements in molten lead (1000 °C), whereas LaPtP (orthorhombic, a = 7.268(1), b = 4.532(1), c = 7.864(2) Å ) was prepared by heating mixtures of the elements at 900 °C. Both phosphides were investigated by single crystal X-ray diffraction. Their crystal structures belong to the TiNiSi-type (Pnma; Z = 4), but the positions of the Ni and Si atoms are exchanged. Therefore the Pt atoms are located in the centers of trigonal prisms and the P atoms are coordinated by four Pt atoms in the shape of distorted tetrahedra.
Polysulfonylamine, CLXXX [1]. Bis(triphenylphosphoranyliden)ammonium-di(methansulfonyl)amid: Eine Kristallstruktur mit CH/π-Wechselwirkungen zwischen Methylund Phenylgruppen / Polysulfonylamines, CLXXX [1]. Bis(triphenylphosphoranylidene)ammonium Di(methanesulfonyl)amide:A Crystal Structure Featuring Methyl-Phenyl CH/π Interactions
Authors: Wölper Christoph , Jones Peter G. , Blaschette Armand
Published: February 2015

The structure of [Ph3PNPPh3][(MeSO2)2N] (monoclinic, P21/c, Z ' = 1; single-crystal X-ray diffraction at −140 °C) displays chains of relatively small anions, surrounded by four parallel columns of bulky cations, giving a rectangular array. In contrast to a previously reported series of onium dimesylamides with smaller cations, interanion hydrogen bonding CMe-H· · · O, originating from the inductively activated methyl groups, is not observed in the present structure. In consequence, the packing arrangement is determined by multiple phenyl embraces between cations, weak cation-anion hydrogen bonds CPh-H· · ·O/N and, most notably, by methyl-phenyl CH/π interactions between anions and cations. One methyl group forms two C-H· · ·π contacts to different phenyl rings (hydrogen-to-centroid distances: 272 and 285 pm), the other lies in a tripodal mode above an aromatic ring plane (hydrogen-to-centroid distances: ca. 330 pm).
Laportoside A and Laportomide A: A New Cerebroside and a New Ceramide from Leaves of Laportea ovalifolia
Authors: Tazoo Dagobert , Krohn Karsten , Hussain Hidayat , Kouam Simeon F. , Dongo Etienne
Published: February 2015

Laportoside A (1), a new cerebroside, and a new ceramide named laportomide A (2), have been isolated from Laportea ovalifolia. Their structures were determined by comprehensive analyses of their 1D, 2D NMR, and HREIMS spectral data. The remaining two known compounds were identified as β -sitosterol acetate, and β -sitosterol glucopyranoside.
Die Kristallstruktur der 5-Bis(thiomethyl) methylenmeldrumsäure [1] / The Crystal Structure of 5-Bis(thiomethyl)methylene Meldrum’s Acid [1]
Authors: Kuhn Norbert , Al-Sheikh Ahmad , Maichle- Mößmer Cäcilia , Steimann Manfred , Sweidan Kamal
Published: February 2015

The crystal structure of 5-bis(thiomethyl)methylene Meldrum’s Acid (2) reveals a zwitterionic nature of the compound apparently influenced by both steric and electronic factors (triclinic space group P1̄, Z = 2, a = 5.489(1), b = 7.402(2), c = 14.329(3)Å ; α = 82.25(3), β = 82.08(3), γ = 78.59(3)°; V = 561.7(2) Å3).
A Xanthene-based Ligand with Two Adjacent Malonate Binding Sites
Authors: Siewert Inke , Limberg Christian
Published: February 2015

The syntheses of two functionalized xanthenes are described which after deprotonation represent ligands for dinuclear metal complexes. For the previously prepared [RXanthdim]H2 - which after deprotonation leads to a ligand with two adjacent β -diiminato binding sites - a significantly improved synthetic procedure is described involving the Pd catalyzed coupling of two diethyl malonate moieties to the xanthene backbone. Deprotonation of the resulting compound [Xanthmal]H2 provides a ligand with two adjacent diethyl malonate functions. To demonstrate this, [Xanthmal]H2 was reacted exemplarily with two equivalents of LDA to obtain the lithium salt {Li2[Xanthmal]}2 (4) which can be treated with ZnBr2 to yield the zinc complex [Xanthmal]2Zn2 (5). Alternatively, 5 can be obtained directly from [Xanthmal]H2, when ZnEt2 is chosen as the metal precursor. The crystal structures of 4 and 5 are discussed. In summary, the results show that [Xanthmal]2− is a suitable ligand for the preparation of novel dinuclear metal complexes.
Crystal Structures and Stability of Two Bipyridyl Complexes of Metal Chloroacetates
Authors: Chen Liang , Wanga Xian-Wen , Chen Jing-Zhong , Liu Jian-Hong
Published: February 2015

The complexes Mn(Cl3CCOO)2(4,4′-bpy) (1) and [Cu2(ClCH2COO)(2,2′-bpy)2(OH)(H2O)]-(NO3)2(2) (bpy = bipyridine) were generated under mild reaction conditions and characterized by IR spectra, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and single crystal X-ray diffraction. Compound 1 exhibits a two-dimensional network with octahedrally coordinated Mn(II) atoms linked by 4,4′-bpy ligands and Cl3COO− ligands. Compound 2 features a supramolecular structure of binuclear complexes, with edge-sharing five-coordinated square-pyramidal units bridged by the ClCH2COO− ligand, an OH− group and a water molecule. Complex 1 crystallizes in the orthorhombic space group Pbcn with cell parameters: a = 16.5390(17), b = 11.6396(17), c = 9.9181(12) Å, V = 1909.3(4) Å3, Z = 4, wR2 = 0.1576. Complex 2 crystallizes in the triclinic space group P1̅ with cell parameters: a = 7.6190(15), b = 11.151(2), c = 16.640(3) Å , α = 73.13(3), β = 80.89(3), γ = 74.51(3)°, V = 1298.73(4) Å3, Z = 2, wR2 = 0.1265.
Cytotoxic Hybrids Between the Aromatic Alkaloids Bauerine C and Rutaecarpine
Authors: Huber Kilian , Bracher Franz
Published: February 2015

Two hybrids between the alkaloids bauerine C and rutaecarpine were prepared. Screening for cytotoxic activity revealed that introduction of two chlorine substituents to the quinazolinocarboline core of rutaecarpine strongly enhances cytotoxic activity, whereas methylation at the indole nitrogen is detrimental to activity.
An Improved and Green Preparation of 3-(Alkylthio)propionic Acids
Authors: Vaismaa Matti J. P. , Yliniemelä Sanna M. , Lajunen Marja K.
Published: February 2015

An efficient, facile microwave-assisted synthesis has been developed for the preparation of unsymmetrical sulfide derivatives from 3-mercaptopropionic acid and a wide variety of alkyl, allyl or aryl chlorides or bromides. The synthesis performed in ethanol at 80 or 120 °C using sodium hydroxide as a base, selectively without an offensive smell, generates 3-(alkylthio)propionic acids in good yields. Effects of reaction components, temperature, and the heating technique on the formation of the product and side-products were studied.
New Chemical Derivatives of the Natural Compound Dictyophlebine Inhibiting Acetyl- and Butyrylcholinesterase
Authors: Devkota Krishna P. , Choudhary M. Iqbal , Anjum Shazia , Nawaz Sarfaraz A. , Lenta Bruno N. , Sewald Norbert
Published: February 2015

The acetyl- and butyrylcholinesterase inhibiting natural product dictyophlebine 1 was subjected to different N-alkylation and hydrochlorination reactions by which five new and bioactive chemical derivatives (2 - 6) with pentyl, pent-4-en-1-yl, hex-5-en-1-yl, 4-chloropentyl and 5-chlorohexyl substituents at the 3-N position were obtained with high yield. The alkylated and chlorinated products 3 - 6 were found to have significantly higher inhibitory potential towards cholinesterase than the parent compound 1.
A New Germacranolide and a New Ceramide from Salvia nubicola (Lamiaceae)
Authors: Ali Muhammad S. , Ibrahima Syed A. , Ahmed Shakeel , Lobkovsky Emil
Published: February 2015

The methanol-soluble part of Salvia nubicola has yielded a new germacranolide and a new ceramide named nubtrienolide and nubenamide, respectively. Structures of both the isolated constituents were elucidated with the aid of spectroscopic techniques; the nubtrienolide structure was further confirmed via single crystal X-ray diffraction analysis. Among both the metabolites, nubtrienolide showed strong growth inhibition against Pseudomonas aeruginosa while during phytotoxicity testing, the same compound promoted the growth of Lemna minor L. instead to inhibit it.
Alkali Salts of 1-Methyl-5-nitriminotetrazole – Structures and Properties
Authors: Klapötke Thomas M. , Radies Hendrik , Stierstorfer Jörg
Published: February 2015

Alkali salts of 1-methyl-5-nitriminotetrazole (1, 1-MeAtHNO2) are common intermediates in the synthesis of alkylated nitriminotetrazoles and their derivatives and can be used as brilliant coloring agents in modern pyrotechnics, due to their cations in combination with the high nitrogen contents. The structures of the crystalline state of A+ 1-MeAtNO2
− · xH2O (A = Li+, x = 1 (2), A = Na+ (3), A = K+ (4), A = Rb+ (5) and A = Cs+ (6), all x = 0) were determined using low temperature single crystal X-ray diffraction. In addition, the compounds were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (1H, 7Li, 13C, 14N, 15N), elemental analysis and differential scanning calorimetry (DSC). Since tetrazoles are known to be promising energetic materials, the heats of formation were calculated using experimentally determined heats of combustion obtained by bomb calorimetry. The sensitivities of all compounds were tested using the BAM drophammer and friction tester showing them to have no sensitivity neither against friction (<360 N) nor impact (<50 J). Crystal data: 2: monoclinic, P21, a = 3.5152(3), b = 12.3308(9), c = 7.3381(5) Å , β = 92.068(7)°, V = 317.86(4) Å3, Z = 2, δ = 1.756 g cm−3; 3: monoclinic, P21/n, a = 3.6071(2), b = 8.3254(5), c = 18.955(1) Å, β = 91.365(6)°, V = 569.07(6) Å3, Z = 4, δ = 1.939 g cm−3; 4: monoclinic, P21/c, a = 3.6310(1), b = 8.6487(2), c = 19.8598(5) Å, β = 94.945(2)°, V = 621.34(3) Å3, Z = 4, δ = 1.948 g cm−3; 5: monoclinic, P21/n, a = 8.7948(2), b = 10.1640(2), c = 15.0571(3) Å , β = 92.470(2)°, V = 1344.71(5) Å3, Z = 8, δ = 2.258 g cm−3; 6: monoclinic, P21/n, a = 6.3539(1), b = 13.4762(3), c = 8.2876(2) Å, β = 99.245(2)°, V = 700.42(3) °Å3, Z = 4, δ = 2.618 g cm−3.
Synthesis and Structural Characterization of trans-Bis[1,3-bis(methoxyethyl)- 4,5-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichloropalladium( II)
Authors: Gökçe Aytaç Gürhan , Kılınçarslan Rafet , Aygün Muhittin , Çetinkaya Bekir , García-Granda Santiago
Published: February 2015

A Pd(II) complex of a new N-heterocyclic carbene (NHC) ligand with bulky substituents and functionalized methoxy-donor side arms has been synthesized and characterized by elemental analyses, 1H and 13C NMR, and IR spectroscopy. Molecular and crystal structures of the title complex have been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/c, with a = 15.927(2), b = 8.489(2), c = 20.309(5) Å, β = 99.213(2)°, Z = 2, Dx = 1.253 g cm−3. The palladium atom is situated on an inversion center. There are several weak intramolecular C-H ··· N/O interactions.
Bis(1-cyclohexen-3-on-1-oxy)silane, Silyl-enole von β-Ketonen/ Bis (1-cyclohexene-3-on-1-oxy)silanes, Silyl-enoles of β -Ketones
Authors: Dietz Wibke , Schwerdtfeger Yvonne , Klingebiel Uwe , Noltemeyer Mathias
Published: February 2015

5,5-Dimethylcyclohexane-1,3-dione (dimedone) and cyclohexane-1,3-dione react with Cl2Si(CMe3)2 in the presence of triethylamine to give the bis(1-cyclohexene-3-on-1-oxy)dit butylsilanes 2 and 3. Using dimedone and Cl2SiMe2, the analogous dimethylsilane 1 is obtained. A 1,4-Michael-Addition occurs using cyclohexane-1,3-dione in the reaction with Cl2SiMe2 to give a spirocyclic diketone (4). The reaction of cyclohexane-1,3-dione with lithium-diisopropylamide and F3SiCMe3 leads to the formation of a salt [iPr2NH2]2HF[C6H7O2]2, 5. The crystal structures of 2 - 5 were determined.
NOHSO4/HF – A Novel Etching System for Crystalline Silicon
Authors: Patzig Sebastian , Roewer Gerhard , Kroke Edwin , över Ingo
Published: February 2015

Solutions consisting of HF - NOHSO4 - H2SO4 exhibit a strong reactivity towards crystalline silicon which is controlled by the concentrations of the reactive species HF and NO+. Selective isotropic and anisotropic wet chemical etching with these solutions allows to generate a wide range of silicon surface morphology patterns. Traces of Ag+ ions stimulate the reactivity and lead to the formation of planarized (polished) silicon surfaces. Analyses of the silicon surface, the etching solution and the gas phase were performed with scanning electron microscopy (SEM), DR/FT-IR (diffusive reflection Fourier transform infra-red), FT-IR, Raman and NMR spectroscopy, respectively. It was found that the resulting silicon surface is hydrogen-terminated. The gas phase contains predominantly SiF4, NO and N2O. Furthermore, NH4
+ is produced in solution. The study has confirmed the crucial role of nitrosyl ions for isotropic wet chemical etching processes. The novel etching system is proposed as an effective new way for selective surface texturing of multi- and monocrystalline silicon. A high etching bath service lifetime, besides a low contamination of the etching solution with reaction products, provides ecological and economical advantages for the semiconductor and solar industry.
Solid-state 17O NMR Study of Small Biological Compounds
Authors: Yamada Kazuhiko , Shimizu Tadashi , Mitsuru Yoshida , Asanuma Miwako , Tansho Masataka , Nemoto Takahiro
Published: February 2015

We present a systematic experimental and theoretical investigation of the oxygen chemical shielding and electric-field-gradient tensors in polycrystalline amino acids and a peptide. Analysis of the 17O magic-angle-spinning (MAS), multiple-quantum MAS, and stationary nuclear magnetic resonance (NMR) spectra yield the magnitudes and the relative orientations between the two NMR tensors. The obtained 17O NMR parameters are sensitive to the hydrogen bond environments. We also demonstrate that solid-state 17O NMR is potentially useful for studying the secondary structures of peptides and proteins.
A Class of Non-Kekulé Molecules with Low Excitation Energies
Authors: Dietz Fritz , Drebov Nedko , Tyutyulkov Nikolai
Published: February 2015

A class of non-Kekulé molecular systems with a new structural principle and low excitation energies or with a triplet ground state was investigated theoretically. The systems consist of a non-Kekulé monoradical, possessing a non-bonding molecular orbital linked in a specific way to another monoradical.
Polysulfonylamine, CLXXXII. Bis(triphenylphosphoranyliden)ammonium-di(4-fluorbenzolsulfonyl)amid: Zwei Polymorphe mit unterschiedlichen Konformationen des Kations und des Anions/ Polysulfonylamines, CLXXXII. Bis(triphenylphosphoranylidene)ammoniumDi(4-fluorobenzenesulfonyl) amide: Two Polymorphs Featuring Different Conformations of the Cation and the Anion
Authors: Wölpera Christoph , Dix Ina , Freytag Matthias , Jones Peter G. , Blaschette Armand
Published: February 2015

Two polymorphs A and B of the previously unreported compound [Ph3PNPPh3]+[(4-F-C6H4 SO2)2N]− have been revealed by serendipity (form A: triclinic, space group P1̄, Z′= 1; form B: monoclinic, space group P21/n, Z′= 1). Conformational flexibility of both the cation and the anion appears to facilitate polymorph formation. The (C3P)2N moiety of the cation, as viewed down P···P′, is ecliptic in A but staggered in B, whereas the extended conformations of the anion (C-S···S′-C′ antiperiplanar) display notably different torsion angles about the S-N and the S-C bonds. Each structure is characterized by an extensive network of weak C-H···O/N/F hydrogen bonds and CH/π interactions. The packing of A consists of cation monolayers that intercalate parallel chains of anions. In contrast, polymorph B forms homoionic strands, whereby each strand comprises two ion chains and is surrounded by four parallel strands of opposite charge.
A Chain-like Polyoxotungstate Constructed from [CeW10O36]9–, [Na5(H2O)17Cl]4+, and [Na2(H2O)8]2+ Units: (NH4)3[Na5(H2O)17Cl]{[Na(H2O)4]2[CeW10O36]}· 6 H2O
Authors: Yuan Ling , Qin Chao , Wang Xinlong , Wang Enbo
Published: February 2015

An unusual cerium-containing decaoxotungstate complex, (NH4)3[Na5(H2O)17Cl]{[Na(H2O)4]2- [CeW10O36]} · 6H2O (1) has been synthesized and characterized by IR, TG, and single crystal X-ray diffraction studies (yellow crystals, orthorhombic, space group Imm2, a = 11.473(2), b = 15.225(3), c = 17.646(7) Å, V = 3082.3(15) °A3, Z = 2, R = 0.046). In this compound, sandwichtype [CeW10O36]9− clusters are linked by binuclear [Na2(H2O)8]2+ units by sharing oxygen atoms into linear chains, which are further extended into a 2D supramolecular network via pentanuclear [Na5(H2O)17Cl]4+ units by strong hydrogen bonding interactions.
Some Air-stable Unsymmetrical Nickel 1,2-Dithiolenes with Extended Tetrathiafulvalenedithiolato Ligands
Authors: Papavassiliou George C. , Anyfantis George C. , Koutselas Ioannis B.
Published: February 2015

The air-stable unsymmetrical complexes Ni(dt)(dmit), Ni(dt)(dmio), Ni(tmdt)(dmit), Ni(tmdt)(dmio), Ni(etdt)(dmit), Ni(etdt)(dmio), Ni(ptdt)(dmit), and Ni(ptdt)(dmio) (where dmit is 1,3-dithiol-2-thione-4,5-dithiolate, dmio is 1,3-dithiol-2-one-4,5-dithiolate, dt is tetrathiafulvalendithiolate, tmdt is trimethylenetetrathiafulvalenedithiolate, etdt is ethylenedithiotetrathiafulvalenedithiolate, and ptdt is propylenedithiotetrathiafulvalenedithiolate) were prepared and characterized analytically, electrochemically and spectroscopically. In the solid state, the compounds exhibit optical absorption edges between 0.70 and 0.82 eV. Their LUMO and HOMO levels occur at ca. 4.5 and 5.3 eV, respectively.
C48 Buckybowl and C60 Fullerene Precursors on the Basis of Truxenone
Authors: Amsharov Konstantin Yu. , Jansen Martin
Published: February 2015

The synthesis of bromine-substituted truxenone derivatives which constitute prospective precursors of geodesic structures is presented. The underlying mechanism of fullerene formation from truxenone-based precursors during flash pyrolysis is discussed. Isolable quantities of C60 fullerene have been achieved by intramolecular condensation of a precursor containing all 60 carbon atoms in appropriate positions, 72 out of the 90 required C-C bonds, and 3 bromine atoms.
Phenylboration of Monoalkyn-1-yltin Compounds
Authors: Wrackmeyer Bernd , Tok Oleg L. , Milius Wolfgang
Published: February 2015

The 1 : 1 reactions of triphenylborane 1 with monoalkyn-1-yltin compounds Me3Sn-C≡C-R1 2 [R1 = tBu (a), Ph (b), ferrocenyl (c), Si(H)Me2 (d), SnMe3 (e)] afford mainly (> 80 %) the corresponding alkene derivatives 3 by 1,1-phenylboration. Exchange B-Ph/Sn-C≡C-R1 takes place as a side reaction. The corresponding 1 : 2 reaction with 2b leads to the dialkenylborane 4b (R1 = Ph), of which the molecular structure could be determined by X-ray analysis. In contrast, the 1 : 2 reaction with 2e gave an allene derivative 5e. The solution-state structures of compounds 3 - 5 have been confirmed by 1H, 11B, 13C and 119Sn NMR spectroscopy.
A New Supramolecular Assembly Obtained by Reaction Between Thiosaccharin and Hexamethylenediamine
Authors: Baran Enrique J. , Piro Oscar E. , Zinczuk Juan
Published: February 2015

The crystal structure of hexamethylenediammonium bis(thiosaccharinate) dihydrate, [H3N-(CH2)6-NH3](tsac)2 · 2H2O (tsac=C7H4NO2S2, the anion of thiosaccharin), was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P21/a with Z = 4. The thiosaccharinate moiety is planar and shows small but significant modifications in the bonding of the thioamide functional group as compared with the protonated neutral molecule. The ionic crystal is further stabilized by an extensive H-bonding network, which links the anions and cations into an infinite three-dimensional supramolecular assembly. The FTIR spectrum of the compound is briefly discussed in comparison with those of the neutral constituent molecules.
Zink-reiche Erdalkalimetall-Verbindungen AZn5 und AZn11: Kristallstrukturen und chemische Bindung / Zinc-rich Alkaline Earth Compounds AZn5 and AZn11: Crystal Structures and Chemical Bonding
Authors: Wendorff Marco , Röhr Caroline
Published: February 2015

The zinc-rich compounds in the binary systems with the heavier alkaline earth elements CaZn11 and AZn5 (A = Ca, Sr, Ba) have been synthesized from melts of the elements. Their crystal structures, which were in principle known from very early powder or single crystal film experiments, have been refined on the basis of modern single crystal X-ray data. CaZn5 (hexagonal, space group P6/mmm, a = 538.99(2), c = 424.56(1) pm, Z = 1, R1 = 0.0144) crystallizes with the CaCu5 structure type and exhibits a small but distinct phase width Ca1−xZn5+2x up to a composition of Ca0.87Zn5.26 (a = 533.38(1), c = 430.04(1) pm, R1 = 0.0170) achieved through a gradual substitution of Ca by Zn2 dumbbells. The high-temperature form of SrZn5, which was prepared by quenching of melted samples, also adopts the ideal CaCu5 structure type (a = 554.1(2), c = 428.2(2) pm, R1 = 0.0314). The room temperature modification of SrZn5 (orthorhombic, space group Pnma, a = 1313.3(3), b = 529.91(10), c = 669.72(13) pm, Z = 4, R1 = 0.0349) forms a singular structure, whereas the Ba compound of corresponding composition (orthorhombic, space group Cmcm, a = 1078.3(7), b = 839.8(5), c = 532.0(3) pm, Z = 4, R1 = 0.0281) crystallizes with a third, also rather uncommon structure. For the compound CaZn11 (BaCd11 structure type; tetragonal, space group I41/amd, a = 1068.11(10), c = 682.81(7) pm, Z = 4, R1 = 0.0299) the originally proposed structure type was confirmed and also refined using single crystal data. The chemical bonding in all title compounds is analyzed using FP-LAPWband structure methods. Together with geometrical criteria and observed valence electron numbers of isotypic compounds, the results are used to compare and discuss the stability of the different structures of the intermetallic phases in the systems AZn5 and AM11 (M = Zn, Cd, Hg).
Synthesis, Crystal Structure, Spectral and Thermal Characterization, and Antimicrobial Activity of [Cu(HOr)(aepy)(H2O)] ·H2O (aepy = 2-aminoethylpyridine, HOr2– = orotate)
Authors: Yeşilel Okan Zafer , Dege Necmi , Darcan Cihan , Büyükgüngör Orhan
Published: February 2015

The copper(II) orotate complex with 2-aminoethylpyridine, [Cu(HOr)(aepy)(H2O)] ·H2O, was synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibility, IR and UV/vis spectroscopic, single crystal X-ray diffraction, and antimicrobial activity studies. The complex crystallizes in the triclinic system, space group P1̅, and the Cu(II) ion is five-coordinate with a distorted square-pyramidal coordination geometry. The aepy ligand and the orotate dianion behave as bidentate (N,N′ and N,Oacid) chelating ligands. The crystal structure is stabilized by intermolecular O-H···O and N-H···O hydrogen bonds, and the orotate ligand exhibits a double hydrogenbonding functionality. The new compound was found active against some gram (+)/(−) bacteria and yeast Candida albicans ATCC 10231, but there was no activity on Aspergillus niger.
BACTERIAL MICROFLORA OF FRESHWATER FISH ORIGINATED FROM USMAS LAKE IN LATVIA
Authors: Terentjeva Margarita , Eizenberga Inga , Novoslavskij Aleksandr , Strazdiņa Vita , Valciņa Olga , Ošmjana JevgÄnija , Bērziņš Aivars
Published: February 2015

The aim of the present study was to evaluate the bacterial contamination of gills, skin and content of gastrointestinal tract of freshwater fish. Altogether 31 fish samples, including European eel (n=11), Silver bream (n=3) and European perch (n=17) were collected between April and July in 2014 from Usmas lake located in West part of Latvia. For evaluation of bacterial load the number of TBC (total bacterial count) and Enterobacteriaceae genera in gills, skin and intestinal tract was enumerated. Presence of Salmonella spp., L. monocytogenes and Y. enterocolitica was analyzed according to the ISO methods. Among different fish species investigated TBC in gills, skin and intestinal samples ranged from 1.89 to 7.47 log CFU.g-1, from 0.66 to 8.47 log CFU.cm-2 and from 0.30 to 8.25 log CFU.g-1 accordingly. Number of Enterobacteriaceae genera in gills, skin and intestinal tract ranged from 0.7 to 5.78 log CFU.g-1, from 4.91 to 7.12 log CFU.cm-2 and from 0.70 to 7.47 log CFU.g-1, respectively. Number of TBC and Enterobacteriaceae in European eel samples of gills, skin and intestinal tract was significantly less than in Silver bream and European perch samples (P
ANTIFUNGAL ACTIVITY OF VOLATILE COMPONENTS GENERATED BY ESSENTIAL OILS AGAINST THE GENUS PENICILLIUM ISOLATED FROM BAKERY PRODUCTS
Authors: Císarová Miroslava , Tančinová Dana , Brodová Marianna
Published: February 2015

The aim of this study was evaluation of the antifungal activity of 5 essential oils (EOs). We concretely used thyme, clove, basil, jasmine and rosemary EOs by vapor contact against the fungal species, namely Penicillium citrinum, P. chrysogenum, P. hordei, P. citreonigrum, and P. viridicatum and their ability to affect production of mycotoxins. Each fungus was inoculated in the centre on Czapek Yeast Autolysate Agar (CYA) dishes. Dishes were tightly sealed with parafilm and incubated for fourteen days at 25 ± 1 °C (three replicates were used for each treatment). Volatile phase effect of 50 μl of the essential oils was found to inhibit on growth of Penicillium spp.. Complete growth inhibition of the isolates by EOs of thyme and clove was observed. The EO of basil had antifungal effect on growth of P. citreonigrum only after 3rd and 7th day of the incubation at concentration 100 % of EO, like a P. viridicatum, which was inhibited by basil EO (100 %) in comparison with control sets. Data was evaluated statistically by 95.0 % Tukey HSD test. In this study we also tested potentional effect of EOs to affect production of mycotoxins of tested Penicillium isolates which are potential toxigenic fungi. After 14 days of incubation with EOs (100 %) with control sets, they were screened for a production of mycotoxins by TLC chromatography. Results showed non affecting production of mycotoxins by tested EOs.
Conclusions indicate that volatile phase of combinations of thyme oil and clove oil showed good potential in the inhibition of growth of Penicillium spp. EOs should find a practical application in the inhibition of the fungal mycelial growth in some kind of the food.
NATURAL MICROFLORA OF WINE GRAPE BERRIES
Authors: Kántor Attila , Kačániová Miroslava , Kluz Maciej
Published: February 2015

The diversity of yeasts and bacterial species on grapes has been investigated in vineyards worldwide. For winemaking are very important three groups of microorganisms. First two includes acetic acid and lactic acid bacteria; they live and grow normally on grape surface. The third group includes more than 20 detectable genera of yeasts. There are three principal genera found on grapes Hanseniaspora uvarum (Kloeckera apiculata), Metschnikowia pulcherrima (Candida pulcherrima), and Candida stellata or new descripted Candida zemplinina. Aim of this study was investigate of number of three major groups of microorganisms which are important for grapes and winemaking. The number of bacteria on Acetobacter agar (AA) ranged from 1.76 log CFU/mL to 2.80 log CFU/mL. Lactic acid bacteria were counted on MRS agar and the number of detectable colonies ranged from 0.48 log CFU/mL to 2.06 log CFU/mL. Sabouraud dextrose agar (SDA) was used for cultivation of yeast and the number of yeasts ranged from 2.47 log CFU/mL to 2.76 log CFU/mL. For identification of yeast species were used different types of agar media with acid base indicator bromocresol green. Identified 10 yeasts species includes to genus: Candida, Metschnikowia, Pichia, Kluyveromyces, Hanseniaspora, Hansenula, Candida, Debaromyces, Rhodotorula and Saccharomyces. We identified only few bacterial species includes to genus Lactobacillus, Pediococcus, Gluconobacter and Acetobacter.
LIME PRETREATMENT OPTIMIZATION OF WHEAT STRAW TO IMPROVE ETHANOL PRODUCTION BYSACCHAROMYCES CEREVISIAE AND ITS VALIDATION
Authors: Ondrejovič Miroslav , Dudášová Veronika , Chmelová Daniela
Published: February 2015

The aim of this study was to optimize of independent variables as temperature, time and reaction ratio to output parameter of
simultaneous enzyme saccharification and fermentation by Saccharomyces cerevisiae of pretreated wheat straw as model substrate via
RSM (response surface methodology) approach. As dependent variable, it was chosen ethanol yields characterizing effectivity of
process. The optimal conditions were approximately temperature 100 °C, time 1 hour and reaction ratio 26 mL to 1 g of treated wheat
straw with ethanol yields 141.9 mg.g-1. After calculating the optimal values, the validation analyze was carried out and it was found out
that the predicted and experimentally verified dependent variable was in agreement with the optimal parameters (~ 95 %). Proposed
model was tested for three lignocellulosic materials (winter wheat straw, alfalfa hay and maize straw) as wheat straw used as model
substrate and it was confirmed the possibility of its use for other agricultural residues with similar content of lignocellulose.
MICROORGANISMS IN SELECTED CONFECTIONARY PRODUCTS DURING THE MANUFACTURING PROCESS
Authors: Petrová Jana , Juhaniaková Ä½ubomÃ­ra , Terentjeva Margarita , Kunová Simona , Blaškovičová Henrieta , Kačániová Miroslava
Published: February 2015

The aim of our study was to evaluate the microbiological quality confectionery products during production. A total of 135 samples were analyzed: 45 samples of the punch balls, 45 Venček samples and 45 samples French cubes from home, school and private production. For microorganism cultivation VRBL agar for the isolation of coliform bacteria, DRBC and DG18 for microscopic fungi and yeasts, Plate Count Agar for total viable count, Meat peptone agar for mesophilic aerobic bacteria, XLD agar for Salmonella sp. and Baird Parker agar for Staphylococcus aureus were used. Following microbiological parameters were tested: total viable count, mesophilic anaerobic microorganisms, coliform bacteria, yeast and microscopic filamentous fungi, Salmonella spp. and Staphylococcus aureus. Products are assessed according to the limit values of the number of microorganisms contained in the Codex Alimentary of the Slovak Republic. The overall assessment of the microbiological quality of the punch balls, we found that two samples from school factory and one sample from private producer did not meet CA SR for the total viable count. Comparing the microbiological quality of Venček with CA SR, we found that one sample of home production did not meet the requirements for this type of product. All the tested samples were Staphylococcus aureus and Salmonella spp. negative. Comparing the results of the samples with French cubes CA SR, we found that all the samples satisfy requirements.
CHARACTERIZATION OF ENDOPHYTIC MICROFLORA OF ROSA CANINA FRUITS
Authors: Rovná KatarÃ­na , Bakay Ladislav , Petrová Jana , Terentjeva Margarita , Černá Jana , Kačániová Miroslava
Published: February 2015

There aren’t a lot of studies about the bacterial communities associated with the Rosa canina and the aim of this study was to characterize endophytic bacteria from fruit of Rosa canina. The fruits of R. canina, which is growing wild in Slovakia, were collected in May 2013 from four locations: Nitra-Zobor, Vrbové-Baraní dvor, Rišňovce, Modra pažiť, Slovakia. Microbiological analyses were conducted by use of standard microbiological methods by spreading of fruits homogenates onto agar plate. Total viable count and mesophilic anaerobic sporulating bacteria were determined on Plate Count Agar after incubation for 2 days at 37 °C. Pseudomonas aeruginosa enumeration was carried out after incubation of Pseudomonas Isolation agar at 48 h at 35 °C. For members of the family Enterobacteriaceae (45 °C) Violet Red Bile Glucose agar were used and incubation was carried out for 24 h at 37 °C. For determinations of fungal colonies Malt agar and Czapek-Dox agar were inoculated using the spread-plate technique and incubated at 25 °C for 5 days. The yeasts were grown in Glucose Yeast Peptone agar (aerobiosis) at 25 °C during 72 hours. The total viable count of fruits ranged from 4.07 log cfu.g-1 in Rišňovce to 4.84 log cfu.g-1 in Vrbové Baraní dvor. Number of mesophilic anaerobic sporulating bacteria ranged from 4.09 in Vrbové Baraní dvor to 4.82 log cfu.g-1 in Modrá pažiť. Number of Pseudomonas aeruginosa count ranged from 2.00 in Nitra Zobor and Vrbové Baraní dvor to 3.94 log cfu.g-1 in Modrá pažiť. In our study the number of Enterobacteriaceae genera ranged from 3.38 in Nitra Zobor to 4.25 log cfu.g-1 in Vrbové Baraní dvor. Number of yeasts ranged from 3.36 in Vrbové Baraní dvor to 3.85 log cfu.g-1 in Modrá pažiť. Number of microscopic filamentous fungi ranged from 2.60 in Modrá Pažiť to 3.52 log cfu.g-1 in Nitra Zobor. Our findings indicate that Rose plant is naturally associated with a variety of endophytic microorganisms, which have different physiological and biochemical properties.
ENDOGENAL COLONIZATION OF GRAPES BERRIES
Authors: Tančinová Dana , Rybárik Ä½ubomÃ­r , Mašková Zuzana , Felšöciová SoÅa , Císarová Miroslava
Published: February 2015

The aim of study was to detect the microscopic filamentous fungi from wine surface of sterilized grapes berries of Slovak origin. We analyzed 21 samples of grapes, harvested in the year 2012 of various wine-growing regions. For the isolation of species we used the method of direct plating surface-sterilized berries (using 0.4% freshly pre-pared chlorine) on DRBC (Dichloran Rose Bengal Chloramphenicol agar). The cultivation was carried at 25±1°C, for 5 to 7 days. A total number of 2541 fungal isolates pertaining to 18 genera including Mycelia sterilia were recovered. Isolates of genus Alternaria were found in all of tested samples with the highest relative density 56.4%. The second highest isolation frequency we detected for genus Fusarium (90.48% positive samples), but with low relative density (31 isolates and 2.99% RD). Another genera with higher isolation frequency were Cladosporium (Fr 85.71%, RD 14.6%), Mycelia sterilia (Fr 85.71%, RD 4.25%), Penicillium (Fr 80.95%, RD 13.42%), Botrytis (Fr 71.43%, RD 2.95%) Rhizopus (Fr 66.66%, RD 1.34%), Aspergillus (Fr 57.14%, RD 0.87%), Epicoccum (Fr 47.62%, RD 1.22%), Trichoderma (Fr 42.86%, RD 1.26%). Isolation frequency of another eight genera (Arthrinium, Dichotomophtora, Geotrichum, Harzia, Chaetomium, Mucor, Nigrospora and Phoma) was less than 10% and relative density less than 0.5%. Chosen isolates of potential producers of mycotoxin (species of Alternaria, Aspergillus, Fusarium and Penicillium) were tested for the ability to produce relevant mycotoxins in in vitro conditions using TLC method. None isolate of Aspergillus niger aggregate (13 tested) did not produce ochratoxin A – mycotoxin monitored in wine and another products from grapes berries. Isolates of potentially toxigenic species recovered from the samples were found to produce another mycotoxins: aflatoxin B1, altenuene, alternariol, alternariol monomethylether, citrinin, diacetoxyscirpenol, deoxynivalenol, HT-2 patulin, penitrem A and T-2 toxin in in vitro conditions. In conclusion, another research should be performed to detect the occurrence of these mycotoxins in grapes, must, wine and another products from grape.
EFFECT OF PROTEINE CONTENT IN BOAR SEMINAL PLASMA ON THE SPERM MOTILITY IN DILUTED SEMEN STORED FOR 3 DAYS
Authors: Apić Jelena , Vakanjac Slobodanka , Radović Ivan , Jotanović Stoja , Živkov-Baloš Milica , Milovanović Aleksandar , Barna Tomislav , Stanković Branislav , Jajić Igor , Maletić Milan
Published: February 2015

Recently, it was frequently demonstrated that fertility of sows after artificially inseminated is lower than after mating. This is associated with a reduced fertilization capacity of overdiluted insemination doses. The aim of this study was to investigate the sperm motility in the semen samples, forming from the ejaculates with high or low protein content, stored in vitro on 17oC for 3 days. Progressive motility was significantly higher (p
WHEAT PATHOGEN RESISTANCE AND CHITINASE PROFILE
Authors: Gregorová Zuzana , Socha Peter , Maglovski MarÃ­na , Moravčíková Jana , Libantová Jana , Kuna Roman , Hauptvogel Pavol , Ildikó MatuÅ¡Ã­kovÃ¡
Published: February 2015

The powdery mildew and leaf rust caused by Blumeria graminis and Puccinia recondita (respectively) are common diseases of wheat throughout the world. These fungal diseases greatly affect crop productivity. Incorporation of effective and durable disease resistance is an important breeding objective for wheat improvement. We have evaluated resistance of four bread wheat (Triticum aestivum) and four spelt wheat (Triticum spelta) cultivars. Chitinases occurrence as well as their activity was determined in leaf tissues. There was no correlation between resistance rating and activity of chitinase. The pattern of chitinases reveals four isoforms with different size in eight wheat cultivars. A detailed understanding of the molecular events that take place during a plant–pathogen interaction is an essential goal for disease control in the future.
OVARIAN HORMONE PRODUCTION AFFECTED BY AMYGDALIN ADDITION IN VITRO
Authors: Halenár Marek , Medveďová MarÃ­na , Maruniaková Nora , Kolesárová Adriana
Published: February 2015

Amygdalin, a natural substance, is a cyanogenic glycoside occurring in the seeds of apricots and bitter almonds. It is a controversial anti-tumor compound that has been used as an alternative cancer drug for many years. Amygdalin is composed of two molecules of glucose, one of benzaldehyde, which induces an analgesic action, and one of hydrocyanic acid, which is an anti-neoplastic compound. This in vitro study was performed to evaluate the possible impact of amygdalin (1, 10, 100, 1000, 10 000 μg/mL) on the secretory activity of granulosa cells (GCs) from porcine cyclic ovaries. The release of progesterone and estradiol-17β by GCs were evaluated by ELISA. In our study, the noticeable changes in estradiol-17β release by ovarian GCs were determined after the amygdalin addition. Amygdalin, at the highest dose (10 000 μg/mL), significantly (P≤0.05) stimulated the release of estradiol-17β by GCs, in comparison to the untreated control cells. On the contrary, no significant (P≥0.05) changes in the progesterone release by GCs caused by amygdalin addition were observed. In conclusion, obtained results showed that the amygdalin application (various doses) to ovarian GCs caused a dose-dependent stimulation of the estradiol-17β release, but not progesterone, and its possible modulatory impact on the steroid production in porcine ovaries.
COMPARISON OF 2-DE PROTEOME MAPS OF WHEAT, RYE AND AMARANTH
Authors: Gálová Zdenka , Pálenčárová Eva , Chňapek Milan , Balažová Å½elmira
Published: February 2015

The protein maps of wheat (Triticum aestivum L.), cv. Brea; rye (Secale cereale L.), cv. Oklon and amaranth (Amaranthus sp.) cv. Plaisman were obtained by performing 2-DE over a broad pH range (pH 3-11NL) to obtain total protein profiles. Focussing on the gluten fraction, as it is the major trigger for Celiac disease, proteins were separated with a basic pI over a narrow pH range of pH 6-11. Putative identifications of proteins were determined using current literature. The overall spot pattern from wheat over pH 6-11was identified as gamma-gliadins (~ pI 8-10, Mrs 28 - 30, 000 Da), alpha/beta-gliadins (~pI 6.5-7.5, Mrs 25 - 35, 000 Da) and gluten proteins (pI 6-10, Mrs 35 - 60, 000 Da.). The rye had a higher number of abundant groups visible over a broad range (~ 6-200,000 Da, pI 4-9). Comparison of rye to wheat protein maps showed that each cereal had completely different spot patterns in the LMW region of the gels (
Angiosperm diversity of the Theosophical Society campus, Chennai, Tamil Nadu, India
Authors: Irwin Sheeba Jabez , Thomas Sharmila , Rathinaraj Pauline , Duvuru Narasimhan
Published: February 2015

This paper deals with the list of flowering plants from the Theosophical Society campus (TS), Chennai. The Theosophical Society campus is the second largest green patch in the city of Chennai, next to Guindy National Park. A total of 449 taxa have been recorded comprising 161 trees, 84 shrubs, 179 herbs and 25 climbers that are distributed in 353 genera, represented in 85 families, 11 super orders and 35 orders as per the APG III classification. Superorder Fabids and Lamids account for about 49% of the taxa. Paleotropical elements (66%) dominate the TS campus followed by Neotropical elements (31%). The present study reveals that TS campus has a rich and diverse exotic flora. The garden department of this protected campus takes care of conserving the floral diversity. Hence, Theosophical Society campus can be considered as a major biodiversity heritage site and an indispensible lung space for the city of Chennai.
Transparent Conductive Three-Layered Composite Films Based on Carbon Nanotubes with Improved Mechanical Stability
Authors: Schwarz Hans-Christoph , Schneider Andreas M. , Klimke Stephen , Anto Bibin T. , Eiden Stefanie , Behrens Peter
Published: February 2015

A layered composite coating material with favorable properties for application as a transparent conductor is presented. It is composed of layers of three nanoscopic materials, namely zinc oxide nanoparticles, single wall nanotubes, and graphene oxide nanosheets. The electrically conducting layer consists of single wall nanotubes (SWNTs). The layer of zinc oxide nanoparticles acts as a primer. It increases the adhesion and the stability of the films against mechanical stresses. The top layer of graphene oxide enhances the conductivity of such coatings. Such three-layer composite coatings show better conductivity (without compromising transparency) and improved mechanical stability compared to pure SWNT films. The processes used in the preparation of such coatings are easily scalable.
Copper Corrosion in Irradiated Environments. the Influence of H202 on the Electrochemistry of Copper Dissolution in Hcl Electrolyte
Authors: Smyrl W. H. , Bell R. T. , Atanasoski R. T. , Glass R. S.
Published: February 2015

The anodic dissolution of copper has been examined in deaerated, 0.1 M HCl aqueous solution in the presence of H202. Concentrations of H202 up to 0.2 M were studied at a rotating copper disk-platinum ring electrode. The open circuit potential (OCP) of copper was found to depend on both peroxide concentration and rotation rate. The OCP shifts towards more positive values with increasing H202 concentration (C) and decreasing rotation rate (ω). The dependence of OCP on (C/ω1/2) was the same s for oxygenated solutions reported earlier [1], at small values of (C/ω1/2). At higher values of (C/ω1/2), departure from the expected behavior was observed. The current- voltage curves for anodic dissolution of copper were also influenced by the presence of peroxide. The curves recorded with the potential scanned in the positive direction showed the expected 60 mV slope, but the reverse scans showed significant departures. At a given potential scan rate, hysteresis was observed which was larger for higher H202concentrations, lower rotation rates, and more positive anodic potential limits. Monitoring the cuprous ions at the outer Pt ring revealed that there was a complex set of events taking place at the copper surface, including film formation and the appear- ance of cupric ions.
Ab initioStudies of Electronic Structure of Defects in PbTe
Authors: Ahmad Salameh , Bilc Daniel , Mahanti S.D. , Kanatzidis M.G.
Published: February 2015

Ab initioelectronics structure calculations have been carried out in a series of RPb2n-1Te2n, n=16, compounds to understand the nature of “defect” states introduced by R where R = vacancy, monovalent Na, K, Rb, Cs, Ag atoms and divalent Cd atoms. We find that the density of states (DOS) near the top of the valence band and the bottom of the conduction band get significantly modified. The Na atom seems to perturb this region least (ideal acceptor in PbTe) and the other monovalent atoms enhance the DOS near the top of the valence band. Cd is an interesting case, since it introduces a strong resonance state near the bottom of the conduction band.