Carbon Dioxide-Mediated C(sp3)-H Arylation of Amine Substrates.

Science.gov (United States)

Kapoor, Mohit; Liu, Daniel; Young, Michael C

2018-05-25

Elaborating amines via C-H functionalization has been an important area of research over the past decade but has generally relied on an added directing group or sterically hindered amine approach. Since free-amine-directed C(sp 3 )-H activation is still primarily limited to cyclization reactions and to improve the sustainability and reaction scope of amine-based C-H activation, we present a strategy using CO 2 in the form of dry ice that facilitates intermolecular C-H arylation. This methodology has been used to enable an operationally simple procedure whereby 1° and 2° aliphatic amines can be arylated selectively at their γ-C-H positions. In addition to potentially serving as a directing group, CO 2 has also been demonstrated to curtail the oxidation of sensitive amine substrates.

Observation/confirmation of hindered E2 strength in {sup 18}C/{sup 16}C

Energy Technology Data Exchange (ETDEWEB)

Ong, H.J. [Osaka University, RCNP, Ibaraki, Osaka (Japan); Imai, N. [KEK, Tsukuba, Ibaraki (Japan); Suzuki, D.; Iwasaki, H.; Onishi, T.K.; Suzuki, M.K.; Nakao, T.; Ichikawa, Y. [University of Tokyo, Department of Physics, Bunkyo,Tokyo (Japan); Sakurai, H.; Takeuchi, S.; Kondo, Y.; Aoi, N.; Baba, H.; Bishop, S.; Ishihara, M.; Kubo, T.; Motobayashi, T.; Yanagisawa, Y. [RIKEN, RIKEN Nishina Center, Wako, Saitama (Japan); Ota, S. [University of Tokyo, RIKEN Campus, CNS, Wako, Saitama (Japan); Togano, Y.; Kurita, K. [Rikkyo University, Department of Physics, Toshima, Tokyo (Japan); Nakamura, T.; Okumura, T. [Tokyo Institute of Technology, Department of Physics, Meguro, Tokyo (Japan)

2009-12-15

We have measured the lifetime of the first excited 2{sup +} state in {sup 18}C using an upgraded recoil shadow method to determine the electric quadrupole transition. The measured mean lifetime is 18.9{+-}0.9 (stat){+-}4.4 (syst) ps, corresponding to B(E2;2{sub 1} {sup +}{yields} 0{sup +} {sub gs}) = 4.3{+-}0.2{+-}1.0 e{sup 2}fm{sup 4}, or about 1.5 Weisskopf units. The mean lifetime of the first 2{sup +} state in {sup 16}C was remeasured to be 18.3{+-}1.4{+-}4.8 ps, about four times shorter than the value reported previously. The discrepancy is explained by incorporating the {gamma} -ray angular distribution obtained in this work into the previous measurement. The observed transition strengths in {sup 16,18}C are hindered compared to the empirical values, indicating that the anomalous E2 strength observed in {sup 16}C persists in {sup 18}C. (orig.)

Geometry and bonding in the ground and lowest triplet state of D{sub 6h} symmetric crenellated edged C{sub 6[3m(m-1)+1]}H{sub 6(2m-1)} (m = 2,..., 6) graphene hydrocarbon molecules

Energy Technology Data Exchange (ETDEWEB)

Philpott, Michael R., E-mail: philpott@imr.edu [Center for Computational Materials Science, Institute of Materials Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, 980-8577 Sendai (Japan); Kawazoe, Yoshiyuki [Center for Computational Materials Science, Institute of Materials Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, 980-8577 Sendai (Japan)

2009-03-30

Ab initio plane wave all valence electron based DFT calculations were used to explore the dichotomy of perimeter vs. interior in the electronic and geometric structure of the D{sub 6h} singlet ground state and D{sub 2h} lowest triplet state of planar graphene hydrocarbon molecules with crenellated (arm chair) edges and the general formula C{sub 6[3m(m-1)+1]} H{sub 6(2m-1)} where m = 2,...,6. The largest molecule C{sub 546}H{sub 66} was 4.78 nm across and contained 2250 valence electrons. These molecules are nominally 'fully benzenoid hydrocarbons'. However with increasing size, the core of central atoms abandoned any fully benzenoid geometry they had in small systems and organized into single layer graphite (graphene) structure. The perimeter atoms of the crenellation adopted a conjugated geometry with unequal bonds and between core and perimeter there were some C{sub 6} rings retaining remnants of aromatic sextet-type properties. Compared to a zigzag edge the crenellated edge conferred stability in all the systems studied as measured by the singlet homo-lumo level gap BG{sub 0} and the singlet-lowest triplet energy gap {Delta}E{sub ST}. For the largest crenellated system (m = 6) BG{sub 0} and {Delta}E{sub ST} were approximately 0.7 eV, larger in value than for similarly sized hexagonal graphenes with zigzag edges. Triplet states were identified for all the molecules in the series and in the case of the m = 2 molecule hexabenzocoronene C{sub 42}H{sub 18}, two conformations with D{sub 2h} symmetry were identified and compared to features on the triplet state potential energy surface of benzene.

Mechanistic Insight into Ketone α-Alkylation with Unactivated Olefins via C-H Activation Promoted by Metal-Organic Cooperative Catalysis (MOCC): Enriching the MOCC Chemistry.

Science.gov (United States)

Dang, Yanfeng; Qu, Shuanglin; Tao, Yuan; Deng, Xi; Wang, Zhi-Xiang

2015-05-20

Metal-organic cooperative catalysis (MOCC) has been successfully applied for hydroacylation of olefins with aldehydes via directed C(sp(2))-H functionalization. Most recently, it was reported that an elaborated MOCC system, containing Rh(I) catalyst and 7-azaindoline (L1) cocatalyst, could even catalyze ketone α-alkylation with unactivated olefins via C(sp(3))-H activation. Herein we present a density functional theory study to understand the mechanism of the challenging ketone α-alkylation. The transformation uses IMesRh(I)Cl(L1)(CH2═CH2) as an active catalyst and proceeds via sequential seven steps, including ketone condensation with L1, giving enamine 1b; 1b coordination to Rh(I) active catalyst, generating Rh(I)-1b intermediate; C(sp(2))-H oxidative addition, leading to a Rh(III)-H hydride; olefin migratory insertion into Rh(III)-H bond; reductive elimination, generating Rh(I)-1c(alkylated 1b) intermediate; decoordination of 1c, liberating 1c and regenerating Rh(I) active catalyst; and hydrolysis of 1c, furnishing the final α-alkylation product 1d and regenerating L1. Among the seven steps, reductive elimination is the rate-determining step. The C-H bond preactivation via agostic interaction is crucial for the bond activation. The mechanism rationalizes the experimental puzzles: why only L1 among several candidates performed perfectly, whereas others failed, and why Wilkinson's catalyst commonly used in MOCC systems performed poorly. Based on the established mechanism and stimulated by other relevant experimental reactions, we attempted to enrich MOCC chemistry computationally, exemplifying how to develop new organic catalysts and proposing L7 to be an alternative for L1 and demonstrating the great potential of expanding the hitherto exclusive use of Rh(I)/Rh(III) manifold to Co(0)/Co(II) redox cycling in developing MOCC systems.

C M K Nair

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science. C M K Nair. Articles written in Bulletin of Materials Science. Volume 24 Issue 2 April 2001 pp 249-252 Crystal Growth. Thermal behaviour of strontium tartrate single crystals grown in gel · M H Rahimkutty K Rajendra Babu K Sreedharan Pillai M R Sudarsana Kumar C M K Nair.

Hinder för utomhusundervisning med fokus på årskurs 4-6

OpenAIRE

Petersson, Essi; Carstensen, Linnea

2018-01-01

I den här studien har vi tagit fram de hinder som begränsar möjligheterna för utomhusundervisning för elever i grundskolan, med fokus på årskurs 4-6 och middle school. Syftet med studien var att synliggöra vilka hinder som kan stå i vägen för utomhusundervisning samt visa på behov av vidare forskning i området. Forskningsfrågan som vi har försökt svara på är: Vad utgör hinder för utomhusundervisning med elever i grundskolan, med fokus på årskurs 4-6 och middle school? Studien bygger på den pr...

The Agost Basin (Betic Cordillera, Alicante province, Spain): a pull-apart basin involving salt tectonics

Science.gov (United States)

Martín-Martín, Manuel; Estévez, Antonio; Martín-Rojas, Ivan; Guerrera, Francesco; Alcalá, Francisco J.; Serrano, Francisco; Tramontana, Mario

2018-03-01

The Agost Basin is characterized by a Miocene-Quaternary shallow marine and continental infilling controlled by the evolution of several curvilinear faults involving salt tectonics derived from Triassic rocks. From the Serravallian on, the area experienced a horizontal maximum compression with a rotation of the maximum stress axis from E-W to N-S. The resulting deformation gave rise to a strike-slip fault whose evolution is characterized progressively by three stages: (1) stepover/releasing bend with a dextral motion of blocks; (2) very close to pure horizontal compression; and (3) restraining bend with a sinistral movement of blocks. In particular, after an incipient fracturing stage, faults generated a pull-apart basin with terraced sidewall fault and graben subzones developed in the context of a dextral stepover during the lower part of late Miocene p.p. The occurrence of Triassic shales and evaporites played a fundamental role in the tectonic evolution of the study area. The salty material flowed along faults during this stage generating salt walls in root zones and salt push-up structures at the surface. During the purely compressive stage (middle part of late Miocene p.p.) the salt walls were squeezed to form extrusive mushroom-like structures. The large amount of clayish and salty material that surfaced was rapidly eroded and deposited into the basin, generating prograding fan clinoforms. The occurrence of shales and evaporites (both in the margins of the basin and in the proper infilling) favored folding of basin deposits, faulting, and the formation of rising blocks. Later, in the last stage (upper part of late Miocene p.p.), the area was affected by sinistral restraining conditions and faults must have bent to their current shape. The progressive folding of the basin and deformation of margins changed the supply points and finally caused the end of deposition and the beginning of the current erosive systems. On the basis of the interdisciplinary results

Fast Homoepitaxial Growth of 4H-SiC Films on 4° off-Axis Substrates in a SiH4-C2H4-H2 System

International Nuclear Information System (INIS)

Liu Bin; Sun Guo-Sheng; Liu Xing-Fang; Zhang Feng; Dong Lin; Zheng Liu; Yan Guo-Guo; Liu Sheng-Bei; Zhao Wan-Shun; Wang Lei; Zeng Yi-Ping; Wang Zhan-Guo; Li Xi-Guang; Yang Fei

2013-01-01

Homoepitaxial growth of 4H-SiC epilayers is conducted in a SiH 4 -C 2 H 4 -H 2 system by low pressure hot-wall vertical chemical vapor deposition (CVD). Thick epilayers of 45 μm are achieved at a high growth rate up to 26 μm/h under an optimized growth condition, and are characterized by using a Normaski optical microscope, a scanning electronic microscope (SEM), an atomic force microscope (AFM) and an x-ray diffractometer (XRD), indicating good crystalline quality with mirror-like smooth surfaces and an rms roughness of 0.9 nm in a 5 μm × 5μm area. The dependence of the 4H-SiC growth rate on growth conditions on 4° off-axis 4H-SiC substrates and its mechanism are investigated. It is found that the H 2 flow rate could influence the surface roughness, while good surface morphologies without Si droplets and epitaxial defects such as triangular defects could be obtained by increasing temperature

Dye stability and performances of dye-sensitized solar cells with different nitrogen additives at elevated temperatures - Can sterically hindered pyridines prevent dye degradation?

Energy Technology Data Exchange (ETDEWEB)

Tuyet Nguyen, Phuong; Lund, Torben [Department of Science, Systems and Models, Roskilde University, 4000 Roskilde (Denmark); Rand Andersen, Anders [University of Southern Denmark, Institute of Sensors, Signals and Electrotechnics (SENSE), Niels Bohrs Alle 1, 5230 Odense M (Denmark); Danish Technological Institute, Plastics Technology, Gregersensvej 2630 Taastrup (Denmark); Morten Skou, Eivind [University of Southern Denmark, Department of Chemical Engineering, Biotechnology and Enviromental Technology, Niels Bohrs Alle 1, 5230 Odense M (Denmark)

2010-10-15

The homogeneous kinetics of the nucleophilic substitution reactions between the ruthenium dye N719 and eight pyridines and 1-methylbenzimidazole have been investigated in 3-methoxypropionitrile at 100 C. The half lives of N719 with the additives 4-tert-butylpyridine (0.5 M) and 1-methylbenzimidazole (0.5 M) were 57 and 160 h, respectively. Sterically hindered pyridines like 2,6-lutidine did not react with N719. The efficiencies of dye-sensitized solar cells (DSC, area=8.0 cm{sup 2}) prepared with 1-methylbenzimidazole (MBI), 4-tert-butylpyridine (4-TBP), 2,6-lutidine and without any additive were 7.1%, 6.2%, 6.0% and 4.8%, respectively. The cells were stored in dark at 85 C and their I-V curves and impedance spectra were measured at regular time intervals. The N719 dye degradation in the cells were monitored by a new dye extraction protocol combined with analysis of the dye extract by HPLC coupled to mass spectrometry. After 300 h storage in dark at 85 C 40% of the initial amount of N719 dye was degraded in DSC cells prepared with MBI and the efficiency was decreased to 40% of its initial value. DSC cells prepared with 2,6-lutidine or no additives showed smaller thermal dye and efficiency stability at elevated temperatures than DSC cells prepared with the none sterically hindered additives MBI and 4-TBP. In the cells prepared with 2,6-lutidine or no additive higher contents of the iodo products [RuL{sub 2}(NCS)(iodide)]{sup +} and [RuL{sub 2}(3-MPN)(iodide)]{sup +} were found than in cells prepared with 4-TBP and MBI. It is suggested that sterically hindered pyridines have smaller complexation constants with I{sub 3}{sup -} than unsterically hindered additives. This may explain the observed faster nucleophilic substitution rates of uncomplexed I{sub 3}{sup -} with N719 in DSC cells prepared with sterically hindered pyridines. The EIS analysis showed that the lifetime of the injected electrons in the TiO{sub 2}{tau}{sub eff} is reduced by a thermally induced change

Stacking reactions of the borole complex Cp*Rh(η5-C4H4BPh) with the dicationic fragments [Cp*M]2+ (M = Rh or Ir)

International Nuclear Information System (INIS)

Loginov, D.A.; Muratov, D.V.; Starikova, Z.A.; Petrovskij, P.V.; Kudinov, A.R.

2006-01-01

The reaction of the (borole)rhodium iodide complex [(η-C 4 H 4 BPh)RhI] 4 with Cp*Li afforded the sandwich compound Cp*Rh(η-C 4 H 4 BPh) (1). The reactions of compound 1 with the solvated complexes [Cp*M(MeNO 2 ) 3 ] 2+ (BF 4 - ) 2 gave triple-decker cationic complexes with the central borole ligand [Cp*Rh(μ-η 5 :η 5 -C 4 H 4 BPh)MCp*] 2+ (BF 4 - ) 2 (M = Rh or Ir). The structure of complex 1 was established by X-ray diffraction [ru

Assembly of [Cu2(COO)4] and [M3(μ3-O)(COO)6] (M = Sc, Fe, Ga, and In) building blocks into porous frameworks towards ultra-high C2H2/CO2 and C2H2/CH4 separation performance.

Science.gov (United States)

Zhang, Jian-Wei; Hu, Man-Cheng; Li, Shu-Ni; Jiang, Yu-Cheng; Qu, Peng; Zhai, Quan-Guo

2018-02-20

A porous MOF platform (SNNU-65s) formed by creatively combining paddle-wheel-like [Cu 2 (COO) 4 ] and trigonal prismatic [M 3 (μ 3 -O)(COO) 6 ] building blocks was designed herein. The mixed and high-density open metal sites and the OH-functionalized pore surface promote SNNU-65s to exhibit ultra-high C 2 H 2 uptake and separation performance. Impressively, SNNU-65-Cu-Ga stands out for the highest C 2 H 2 /CO 2 (18.7) and C 2 H 2 /CH 4 (120.6) selectivity among all the reported MOFs at room temperature.

Deposition and characterisation of multilayer hard coatings. Ti/TiNδ/TiCxNy/(TiC) a-C:H/(Ti) a-C:H

International Nuclear Information System (INIS)

Burinprakhon, T.

2001-02-01

Multilayer hard coatings containing Ti, TiNδ, TiC x N y , (TiC m ) a-C:H, (TiC n ) a-C:H, and (Ti) a-C:H were deposited on commercially pure titanium substrates by using an asymmetric bipolar pulsed-dc reactive magnetron sputtering of a titanium target, with Ar, Ar+N 2 , Ar+N 2 +CH 4 , and Ar+CH 4 gas mixtures. The microstructures, elemental compositions and bonding states of the interlayers and the coating surfaces were studied by using cross-sectional transmission electron microscopy (XTEM), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The microstructure development of the multilayer coating was strongly influenced by target poisoning. As a result of the complete poisoning of the titanium target during the deposition of TiNδ and TiC x N y interlayers, the a-C:H interlayers containing graded titanium and nitrogen contents were found to develop successively to the TiC x N y interlayer without the formation of near-stoichiometric TiC. The (TiC m ) a-C:H interlayer consisted of nano-particles of distorted fcc crystal structure embedded in the a-C:H matrix. The (TiC n ) a-C:H and (Ti) a-C:H top layers were found to be a-C:H matrix without nano-particles. In the (Ti) a-C:H top layer there was no measurable amount of Ti observed, regardless of the variation of CH 4 concentration between 37.5 and 60 % flow rate in Ar+-CH4 gas mixture. The top layer (Ti) a-C:H was found to contain approximately 10 atomic % nitrogen, due to N 2 contamination during deposition caused by low conductance of N 2 through the nominally closed valve of the mass flow controller. The change of the CH 4 concentration during deposition of the top layer (Ti) a-C:H, however, showed a strong influence on the hydrogen content. The comparison of the fluorescence background of the Raman spectra revealed that hydrogen-less (Ti) a-C:H was deposited at a CH 4 concentration of less than 50 % flow rate in Ar. The hardness

(VI) ML6 Complexes

African Journals Online (AJOL)

A geometric analysis revealed that beta-(C-H) and alpha-(C-C) can occupy the seventh and eighth coordination sites in the title Fischer carbene complexes as agostic interactions, which allows classifying the carbene as a η3 ligand in these cases. This theory was supported by the relative energies of the conformers and an ...

Ab initio CASSCF study of the electronic structure of the transition-metal alkylidene-like complexes Mo-M[prime]H[sub 2] (M[prime] = C, Si, Ge, and Sn)

Energy Technology Data Exchange (ETDEWEB)

Marquez, A.; Sanz, J.F. (Universidad de Sevilla (Spain))

1992-12-02

Experimental and theoretical research on the electronic and geometric structure of transition-metal-carbenes and -alkylidenes is an active area in chemistry nowadays due to their potential activity in catalysis and in organic and organometallic synthesis. A theoretical investigation of the electronic structure of the high-valent, transition-metal, alkylidene-like complexes MoM[prime]H[sub 2] (M[prime] = C, Si, Ge, and Sn) is reported. Based on ab initio calculations carried out at the complete active space multiconfiguration self-consistent field (CASSCF) level, the molecular structure of the ground state and some low-lying excited states have been determined. For M[prime] = C, Si, and Ge, the ground state has C[sub 2v] symmetry (state [sup 5]B[sub 1]) and corresponds to pairing each electron of the M[prime]H[sub 2] triplet [sup 3]B[sub 1] with an electron of Mo ([sup 7]S). In the case of MoSnH[sub 2], the lowest state is bent (C[sub s] symmetry, state [sup 7]A[prime]), the out-of-plane angle being 68[degrees], and dissociates into SnH[sub 2] ([sup 1]A[sub 1]) + Mo ([sup 7]S). Dissociation energies, potential energy profiles for the dissociation, harmonic force constants in terms of internal symmetry coordinates, and vibrational frequencies are reported. The comparison of these properties with those of their pentacarbonylated homologous (CO)[sub 5]M[double bond]M[prime]H[sub 2] shows that the carbene-like (Fischer) type of complexation is stronger than the alkylidene-like one (Schrock). 28 refs., 4 figs., 6 tabs.

Design and syntheses of hybrid metal-organic materials based on K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] metallotectons

Science.gov (United States)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao; Wang, Wenqiang; Wang, Lei

2016-05-01

By using K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] (C2O42-=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C2O4)2(H2O)2}2]·(H-L1)2·H2O 1, [Fe(C2O4)Cl2]·(H2-L2)0.5·(L2)0.5·H2O 2, [{Fe(C2O4)1.5Cl2}2]·(H-L3)43, [Fe2(C2O4)Cl8]·(H2-L4)2·2H2O 4, K[Al(C2O4)3]·(H2-L5)·2H2O 5, K[Al(C2O4)3]·(H-L6)2·2H2O 6, K[Cr(C2O4)3]·2H2O 7, Na[Fe(C2O4)3]·(H-L6)2·2H2O 8 (with L1=4-dimethylaminopyridine, L2=2,3,5,6-tetramethylpyrazine, L3=2-aminobenzimidazole, L4=1,4-bis-(1H-imidazol-1-yl)benzene, L5=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L6=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C2O4)2(H2O)2]- unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C2O4)Cl2]- anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe2(C2O4)3Cl4]4- unit. Compound 4 features distinct [Fe2(C2O4)Cl8]4- units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C2O4)3]3- units and K+ cations. The 1D chains are further extended into 3D antionic H-bonded framework through O-H···O H-bonds. Compounds 6-8 show 2D [KAl(C2O4)3]2- layer, [KCr(C2O4)3]2- layer and [NaFe(C2O4)3]2- layer, respectively.

Acetylcholine Attenuates Hypoxia/ Reoxygenation-Induced Mitochondrial and Cytosolic ROS Formation in H9c2 Cells via M2 Acetylcholine Receptor

Directory of Open Access Journals (Sweden)

Yi Miao

2013-02-01

Full Text Available Background: The anti-infammatory and cardioprotective effect of acetylcholine (ACh has been reported; nevertheless, whether and how ACh exhibits an antioxidant property against ischemia/reperfusion (I/R-induced oxidative stress remains obscure. Methods: In the present study, H9c2 rat cardiomyocytes were exposed to hypoxia/reoxygenation (H/R to mimic I/R injury. We estimated intracellular different sources of reactive oxygen species (ROS by measuring mitochondrial ROS (mtROS, mitochondrial DNA (mtDNA copy number, xanthine oxidase (XO and NADPH oxidase (NOX activity and expression of rac 1. Cell injury was determined by lactate dehydrogenase (LDH release and cleaved caspase-3 expression. The siRNA transfection was performed to knockdown of M2 acetylcholine receptor (M2 AChR expression. Results: 12-h hypoxia followed by 2-h reoxygenation resulted in an abrupt burst of ROS in H9c2 cells. Administration of ACh reduced the levels of ROS in a concentration-dependent manner. Compared to the H/R group, ACh decreased mtROS, recovered mtDNA copy number, diminished XO and NOX activity, rac 1 expression as well as cell injury. Co- treatment with atropine rather than hexamethonium abolished the antioxidant and cardioprotective effect of ACh. Moreover, knockdown of M2 AChR by siRNA showed the similar trends as atropine co-treatment group. Conclusions: ACh inhibits mitochondria-, XO- and NOX-derived ROS production thus protecting H9c2 cells against H/R-induced oxidative stress, and these benefcial effects are mainly mediated by M2 AChR. Our findings suggested that increasing ACh release could be a potential therapeutic strategy for treatment and prevention of I/R injury.

Design and synthesis of a redox-active tc-99m radiopharmaceutical with ferrocenedithiocarboxylate [FcCS=Fe(C{sub 5}H{sub 4}CS{sub 2})(C{sub 5}H{sub 5}){sup -}

Energy Technology Data Exchange (ETDEWEB)

Uccelli, Licia; Bolzati, Cristina; Boschi, Alessandra; Duatti, Adriano E-mail: dta@ifeuniv.unife.it; Morin, Christophe; Pasqualini, Roberto; Giganti, Melchiore; Piffanelli, Adriano

1999-01-01

The synthesis, at tracer level, of two Tc-99m complexes having the same chemical composition and structure, but differing by one electron in the total electron counting, is reported. These compounds have been prepared by reacting [{sup 99m}TcO{sub 4}]{sup -} with the piperidinium salt of the ligand ferrocenedithiocarboxylate {l_brace}[Fe(II)(C{sub 5}H{sub 4}CS{sub 2})(C{sub 5}H{sub 5})]{sup -}=FcCS{r_brace}, in the presence of N-methyl S-methyldithiocarbazate as donor of N{sup 3-} groups, and triphenylphosphine or SnCl{sub 2} as reducing agents. The formation of the neutral complex [{sup 99m}Tc(N)(FcCS){sub 2}] (compound A) and of the monocationic, mixed-valence complex [{sup 99m}Tc(N)(FcCS) (FcCS*)]{sup +} (compound B) {l_brace}FcCS* [Fe(III)(C{sub 5}H{sub 4}CS{sub 2})(C{sub 5}H{sub 5})]{r_brace} was obtained in high yield. Both complexes comprise a terminal Tc{identical_to}N multiple bond and two FcCS ligands coordinated to the metal center through the two sulfur atoms of the -CS{sub 2} group, but they differ in the oxidation state of one of the two iron atoms of the coordinated FcCS ligands. In complex A, the two Fe atoms are both in the +2 oxidation state, while in B, one Fe atom is in the +2 and the other is in the +3 oxidation state. Thus, B is a mixed-valence Fe(II)-Fe(III) complex. B is easily converted into A by one-electron exchange with various reductants such as triphenylphosphine and excess SnCl{sub 2}. Biodistribution studies in rats showed that complexes A and B are mostly retained in lungs and liver without any significant uptake in organs such as heart and brain.

Mercury(II) and methylmercury(II) complexes of novel sterically hindered thiolates: 13C and 199Hg NMR studies and the crystal and molecular structures of [MeHg(SC6H2-2,4,6-Pri3)], [Hg(SC6H4-2-SiMe3)2], [Hg(2-SC5H3N-3-SiMe3)2], and [Hg{(2-SC6H4)2SiMe2}]2

International Nuclear Information System (INIS)

Block, E.; Brito, M.; Gernon, M.; McGowty, D.; Kang, Hyunkyu; Zubieta, J.

1990-01-01

Several series of complexes of the types [MeHg(SR)] and [Hg(SR) 2 ] have been synthesized, where the ligands are members of new classes of sterically hindered thiolates, including (triorganosilyl)methanethiols, 2-(triorganosilyl)benzenethiols, 3-(triorganosilyl)pyridine-2-thiols, and bis(2-mercaptophenyl) derivatives. Detailed 1 H, 13 C, and 199 Hg NMR studies revealed several general trends. The 199 Hg chemical shifts moved upfield in the order [MeHg(SR)] 2 ] 2 ] 2 ]. For the [MeHg(SR)] series of complexes, 1 J(Hg-C) correlates with δ( 13 C(methyl)) and with the type of thiolate ligand. Anomalous behavior is observed for oligomeric species. There is only a limited correlation of δ( 199 Hg) with steric cone angles for a subset of the complexes. Crystal data for the complexes are reported. 86 refs., 7 figs., 11 tabs

In vitro circumvention of cisplatin resistance by the novel sterically hindered platinum complex AMD473.

Science.gov (United States)

Holford, J.; Sharp, S. Y.; Murrer, B. A.; Abrams, M.; Kelland, L. R.

1998-01-01

A novel sterically hindered platinum complex, AMD473 [cis-aminedichloro(2-methylpyridine) platinum (II)], has been selected for phase I clinical trials due to commence in 1997. AMD473 was rationally designed to react preferentially with nucleic acids over sulphur ligands such as glutathione. This report documents the in vitro circumvention of acquired cisplatin resistance mechanisms in human ovarian carcinoma (HOC) cell lines by AMD473. In a panel of 11 HOC cell lines, AMD473 showed intermediate growth inhibition potency (mean IC50 of 8.1 microM) in comparison to cisplatin (mean IC50 of 2.6 microM) and carboplatin (mean IC50 of 20.3 microM). AMD473 showed only a 30.7-fold increase in IC50 value from the most sensitive to the most resistant HOC cell line, whereas for cisplatin it was 117.9-fold and for carboplatin 119.7-fold. AMD473 also showed significantly (P or = 14 h for AMD473) after equitoxic doses were exposed to HOC cells for 2 h. AMD473 ICLs in the CH1 HOC cell line were slowly formed and showed no visible signs of being repaired 24 h after removal of drug. This was paralleled by a slower, longer lasting induction of p53 protein by equitoxic doses of AMD473 in HOC cell lines with wild-type p53. This new class of sterically hindered platinum compound, selected for clinical trial in 1997, may therefore elicit improved clinical response in intrinsically and acquired cisplatin-resistant tumours in the clinic. Images Figure 9 PMID:9472630

In contrast to conventional inactivated influenza vaccines, 4xM2e.HSP70c fusion protein fully protected mice against lethal dose of H1, H3 and H9 influenza A isolates circulating in Iran

Energy Technology Data Exchange (ETDEWEB)

Ebrahimi, Seyyed Mahmoud, E-mail: smebrahimi@shirazu.ac.ir [Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, P.O. Box 14155-3651,Tehran (Iran, Islamic Republic of); Research Center of Virus and Vaccine, Baqiyatallah University of Medical Science, P.O.Box 14155-3651, Tehran (Iran, Islamic Republic of); Dabaghian, Mehran [Department of Pathobiology, University of Tehran, Faculty of Veterinary Medicine, P.O. Box 14155-6453, Tehran (Iran, Islamic Republic of); Tebianian, Majid [Department of Biotechnology, Razi Vaccine and Serum Research Institute (RVSRI), P.O. Box 31975/148, Karaj, Tehran (Iran, Islamic Republic of); Zabeh Jazi, Mohammad Hossein [Department of Pathobiology, University of Tehran, Faculty of Veterinary Medicine, P.O. Box 14155-6453, Tehran (Iran, Islamic Republic of)

2012-08-15

Ideal vaccines against influenza viruses should elicit not only a humoral response, but also a cellular response. Mycobacterium tuberculosis HSP70 (mHSP70) have been found to promote immunogenic APCs function, elicit a strong cytotoxic T lymphocyte (CTL) response, and prevent the induction of tolerance. Moreover, it showed linkage of antigens to the C-terminus of mHSP70 (mHSP70c) can represent them as vaccines resulted in more potent, protective antigen specific responses in the absence of adjuvants or complex formulations. Hence, recombinant fusion protein comprising C-terminus of mHSP70 genetically fused to four tandem repeats of the ectodomain of the conserved influenza matrix protein M2 (M2e) was expressed in Escherichia coli, purified under denaturing condition, refolding, and then confirmed by SDS-PAGE, respectively. The recombinant fusion protein, 4xM2e.HSP70c, retained its immunogenicity and displayed the protective epitope of M2e by ELISA and FITC assays. A prime-boost administration of 4xM2e.HSP70c formulated in F105 buffer by intramuscular route in mice (Balb/C) provided full protection against lethal dose of mouse-adapted H1N1, H3N2, or H9N2 influenza A isolates from Iran compared to 0-33.34% survival rate of challenged unimmunized and immunized mice with the currently in use conventional vaccines designated as control groups. However, protection induced by immunization with 4xM2e.HSP70c failed to prevent weight loss in challenged mice; they experienced significantly lower weight loss, clinical symptoms and higher lung viral clearance in comparison with protective effects of conventional influenza vaccines in challenged mice. These data demonstrate that C-terminal domain of mHSP70 can be a superior candidate to deliver the adjuvant function in M2e-based influenza A vaccine in order to provide significant protection against multiple influenza A virus strains.

In contrast to conventional inactivated influenza vaccines, 4xM2e.HSP70c fusion protein fully protected mice against lethal dose of H1, H3 and H9 influenza A isolates circulating in Iran

International Nuclear Information System (INIS)

Ebrahimi, Seyyed Mahmoud; Dabaghian, Mehran; Tebianian, Majid; Zabeh Jazi, Mohammad Hossein

2012-01-01

Ideal vaccines against influenza viruses should elicit not only a humoral response, but also a cellular response. Mycobacterium tuberculosis HSP70 (mHSP70) have been found to promote immunogenic APCs function, elicit a strong cytotoxic T lymphocyte (CTL) response, and prevent the induction of tolerance. Moreover, it showed linkage of antigens to the C-terminus of mHSP70 (mHSP70c) can represent them as vaccines resulted in more potent, protective antigen specific responses in the absence of adjuvants or complex formulations. Hence, recombinant fusion protein comprising C-terminus of mHSP70 genetically fused to four tandem repeats of the ectodomain of the conserved influenza matrix protein M2 (M2e) was expressed in Escherichia coli, purified under denaturing condition, refolding, and then confirmed by SDS–PAGE, respectively. The recombinant fusion protein, 4xM2e.HSP70c, retained its immunogenicity and displayed the protective epitope of M2e by ELISA and FITC assays. A prime-boost administration of 4xM2e.HSP70c formulated in F105 buffer by intramuscular route in mice (Balb/C) provided full protection against lethal dose of mouse-adapted H1N1, H3N2, or H9N2 influenza A isolates from Iran compared to 0–33.34% survival rate of challenged unimmunized and immunized mice with the currently in use conventional vaccines designated as control groups. However, protection induced by immunization with 4xM2e.HSP70c failed to prevent weight loss in challenged mice; they experienced significantly lower weight loss, clinical symptoms and higher lung viral clearance in comparison with protective effects of conventional influenza vaccines in challenged mice. These data demonstrate that C-terminal domain of mHSP70 can be a superior candidate to deliver the adjuvant function in M2e-based influenza A vaccine in order to provide significant protection against multiple influenza A virus strains.

Axial zero-field splitting in mononuclear Co(ii) 2-N substituted N-confused porphyrin: Co(2-NC3H5-21-Y-CH2C6H4CH3-NCTPP)Cl (Y = o, m, p) and Co(2-NC3H5-21-CH2C6H5-NCTPP)Cl.

Science.gov (United States)

Lai, Ya-Yuan; Chang, Yu-Chang; Chen, Jyh-Horung; Wang, Shin-Shin; Tung, Jo-Yu

2016-03-21

The inner C-benzyl- and C-o-xylyl (or m-xylyl, p-xylyl)-substituted cobalt(ii) complexes of a 2-N-substituted N-confused porphyrin were synthesized from the reaction of 2-NC3H5NCTPPH (1) and CoCl2·6H2O in toluene (or o-xylene, m-xylene, p-xylene). The crystal structures of diamagnetic chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-hydrogen-21-carbaporphyrinato-N,N',N'')zinc(ii) [Zn(2-NC3H5-21-H-NCTPP)Cl; 3 ] and paramagnetic chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-benzyl-21-carbaporphyrinato-N,N',N'')cobalt(ii) [Co(2-NC3H5-21-CH2C6H5NCTPP)Cl; 7], and chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-Y-xylyl-21-carbaporphyrinato-N,N',N'')cobalt(ii) [Co(2-NC3H5-21-Y-CH2C6H4CH3NCTPP)Cl] [Y = o (8), m (9), p (10)] were determined. The coordination sphere around the Zn(2+) (or Co(2+)) ion in 3 (or 7-10) is a distorted tetrahedron (DT). The free energy of activation at the coalescence temperature Tc for the exchange of phenyl ortho protons o-H (26) with o-H (22) in 3 in a CDCl3 solvent is found to be ΔG = 61.4 kJ mol(-1) through (1)H NMR temperature-dependent measurements. The axial zero-field splitting parameter |D| was found to vary from 35.6 cm(-1) in 7 (or 30.7 cm(-1) in 8) to 42.0 cm(-1) in 9 and 46.9 cm(-1) in 10 through paramagnetic susceptibility measurements. The magnitude of |D| can be related to the coordination sphere at the cobalt sites.

Sugar supported H/sub 2/ production and C/sub 2/H/sub 2/ reduction by the cyanobiont Anabaena azollae

Energy Technology Data Exchange (ETDEWEB)

Rozen, A.; Tel-Or, E.

1986-01-01

Sugar supported activities of H/sub 2/ production and C/sub 2/H/sub 2/ reduction were characterized in axenic cell cultures of the cyanobiont Anabaena azollae isolated from the water fern Azolla filiculoides. Fructose was found to be the favoured substrate, enhancing activities in both the light and the dark even at relatively low concentrations of 0.5-1.0 mM. Higher concentrations of sucrose, (10-20mM) also supported H/sub 2/ production and C/sub 2/H/sub 2/ reduction, while glucose was less effective. Levels of H/sub 2/ production were always lower than those of C/sub 2/H/sub 2/ reduction. 13 references.

Synthesis, autoxidation and photooxidation of hindered pyrrole derivatives. Hindered pyrrolic nitroxide radicals; Synthese, autoxydation et photoxidation de pyrroles encombres radicaux nitroxydes pyrroliques encombres

Energy Technology Data Exchange (ETDEWEB)

Ramasseul, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1969-07-01

2,5-di-t-butyl and 2,3,5-tri-t-butyl pyrrole are prepared from pinacoline and their structure is confirmed by comparison with 2,5-di-t-butyl furan and thiophene (I.R., U.V. and N.M.R. {sup 13}C satellites observation giving J{sub 13{sub C-H}} and J{sub H{sub 3}-H{sub 4}}). The sensitized photooxidation of these hindered pyrroles gives corresponding hydroperoxides which most likely structure is determined using physical and chemical methods. Oxidation of 2,5-di-t-butyl and 2,3,5-tri-t-butyl pyrrole by hydrogen peroxide in presence of inorganic per-acid of by p-nitro-perbenzoic acid does not give the pyrrolic nitroxides in contrast with secondary amines. Some N-hydroxypyrroles are then prepared from pinacoline and ethyl pivaloyl-acetate. Their oxidation by lead dioxide gives the corresponding pyrrolic nitroxides. 2,5-di-t-butyl 3,4-di-ethoxycarbonyl pyrryl 1-oxy is isolated and studied spectroscopically (visible and U.V., E.P.R.). In marked contrast with ordinary nitroxides it does not show solvent effect. It can be compared with 2,4-di-t-butyl cyclopentadienone, a carbon analog. For both, the long wave length transition does not show the usual n - {pi}* behaviour; that is confirmed by E.P.R. Using Huckel method for pyrrolic nitroxide skeleton, it is possible to have a good interpretation of experimental data. (author) [French] Les di-t-butyl 2,5 et tri-t-butyl-2,3,5 pyrrole sont synthetises a partir de la pinacoline et leur structure confirmee par comparaison avec les di-t-butyl-2,5 furanne et thiophene (I.R., U.V. et R.M.N.: observation des satellites {sup 13}C conduisant a la mesure des J{sub 13{sub C-H}} et J{sub H{sub 3}{sub -H{sub 4}}). La photoxydation sensibilisee de ces pyrroles encombres conduit aux hydroperoxydes correspondants dont la structure la plus probable est determinee par les methodes physicochimiques. L'oxydation des di-t-butyl-2,5 et tri-t-butyl-2,3,5 pyrrole par l'eau oxygenee en presence de peracide mineral ou par l'acide p

13C and 1H nuclear magnetic resonance of methyl-substituted acetophenones and methyl benzoates: steric hindrance and inhibited conjugation.

Science.gov (United States)

Budesínský, Milos; Kulhánek, Jirí; Böhm, Stanislav; Cigler, Petr; Exner, Otto

2004-10-01

The 1H and 13C NMR spectra of 14 methyl-substituted acetophenones and 14 methyl-substituted methyl benzoates were assigned and interpreted with respect to the conformation of the C(ar)-C(O) bond. The substituent effects are proportional in the two series and can be divided into polar and steric: each has different effects on the 13C SCS of the individual atoms. In the case of C atoms C(O), C(1) and CH3(CO), the steric effects were quantitatively separated by comparing SCS in the ortho and para positions. The steric effects are proportional for the individual C atoms and also to steric effects estimated from other physical quantities. However, they do not depend simply on the angle of torsion phi of the functional group as anticipated hitherto. A better description distinguishes two classes of compounds: sterically not hindered or slightly hindered planar molecules and strongly sterically hindered, markedly non-planar. In order to confirm this reasoning without empirical correlations, the J(C,C) coupling constants were measured for three acetophenone derivatives labeled with 13C in the acetyl methyl group. The constants confirm unambiguously the conformation of 2-methylacetophenone; their zero values are in accord with the conformation of 2,6-dimethylacetophenone. The zero values in the unsubstituted acetophenone are at variance with previous erroneous report but all J(C,C) values are in accord with calculations at the B3LYP/6-311++G(2d,2p)//B3LYP/6-311+G(d,p) level. Copyright 2004 John Wiley & Sons, Ltd.

Design and syntheses of hybrid metal–organic materials based on K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] metallotectons

Energy Technology Data Exchange (ETDEWEB)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao, E-mail: dbwang@qust.edu.cn; Wang, Wenqiang; Wang, Lei, E-mail: inorchemwl@126.com

2016-05-15

By using K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] (C{sub 2}O{sub 4}{sup 2−}=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C_2O_4)_2(H_2O)_2}{sub 2}]·(H–L{sub 1}){sub 2}·H{sub 2}O 1, [Fe(C{sub 2}O{sub 4})Cl{sub 2}]·(H{sub 2}–L{sub 2}){sub 0.5}·(L{sub 2}){sub 0.5}·H{sub 2}O 2, [{Fe(C_2O_4)_1_._5Cl_2}{sub 2}]·(H–L{sub 3}){sub 4}3, [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]·(H{sub 2}–L{sub 4}){sub 2}·2H{sub 2}O 4, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H{sub 2}–L{sub 5})·2H{sub 2}O 5, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 6, K[Cr(C{sub 2}O{sub 4}){sub 3}]·2H{sub 2}O 7, Na[Fe(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 8 (with L{sub 1}=4-dimethylaminopyridine, L{sub 2}=2,3,5,6-tetramethylpyrazine, L{sub 3}=2-aminobenzimidazole, L{sub 4}=1,4-bis-(1H-imidazol-1-yl)benzene, L{sub 5}=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L{sub 6}=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O){sub 2}]{sup −} unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C{sub 2}O{sub 4})Cl{sub 2}]{sup -} anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe{sub 2}(C{sub 2}O{sub 4}){sub 3}Cl{sub 4}]{sup 4−} unit. Compound 4 features distinct [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]{sup 4−} units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C{sub 2}O{sub 4}){sub 3}]{sup 3−} units and K{sup +} cations. The 1D chains are further extended into 3D antionic H-bonded framework through O–H···O H-bonds. Compounds 6–8 show 2D [KAl(C{sub 2}O

Study on the equilibrium in the MBr2-CH3OH-H2O system (M = Sr2+, Ba2+) at 25 0C

International Nuclear Information System (INIS)

Zlateva, I.; Stoev, M.

1985-01-01

The dehydration processes in the three-component system MBr 2 -CH 3 OH-H 2 O (M = Sr 2+ , Ba 2+ ) have been studied at 25 0 C by physio-chemical analyses. Crystallization fields for the lower crystal hydrates SrBr 2 x H 2 O and BaBr 2 x H 2 O have been found. The solubility curves exhibit complex-formation processes. The dehydration and solvation processes in three-component system such as MBr 2 -CH 3 OH-H 2 O at 25 0 C with M = Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ have been discussed in general terms. (author)

Two competing ionization processes in ESI-MS analysis of N-(1,3-diphenylallyl)benzenamines: formation of the unusual [M-H]+ ion versus the regular [M+H]+ ion.

Science.gov (United States)

Fang, Liwen; Dong, Cheng; Guo, Cheng; Xu, Jianxing; Liu, Qiaoling; Qu, Zhirong; Jiang, Kezhi

2018-06-01

A series of N-(1,3-diphenylallyl)benzenamine derivatives (M) were investigated by electrospray ionization mass spectrometry in the positive-ion mode. Both the anomalous [M-H] + and the regular [M+H] + were observed in the ESI mass spectra. The occurrence of [M-H] + has been supported by accurate mass spectrometry, liquid chromatography mass spectrometry, and tandem mass spectrometry analysis. Calculation results indicated that formation of [M-H] + is attributed to the ion-molecule reaction of M with the protonated ESI solvent molecule (e.g. CH 3 OH 2 + ) via hydride abstraction from a tertiary C sp3 -H. The competing ionization processes leading to [M-H] + or [M+H] + were significantly affected by the concentration of formic acid in the electrospray ionization solvent and the proton affinity of the N atom.

Investigation of instability of M23C6 particles in F82H steel under electron and ion irradiation conditions

Science.gov (United States)

Kano, Sho; Yang, Huilong; Shen, Jingjie; Zhao, Zishou; McGrady, John; Hamaguchi, Dai; Ando, Mamami; Tanigawa, Hiroyasu; Abe, Hiroaki

2018-04-01

In order to clarify the instability of M23C6 in F82H steel under irradiation, both electron irradiation using a high voltage electron microscope (HVEM) and ion irradiation using an ion accelerator were performed. For the electron irradiation, in-situ observation under 2 MV electron irradiation and ex-situ high resolution electron microscopic (HREM) analysis were utilized to evaluate the response of M23C6 against irradiation. The temperature dependence of the irradiation induced instability of the carbide was first confirmed: 293 K indicating severe loss of crystallinity due to dissolution of the constituent atoms though irradiation-enhanced diffusion under the vacancy diffusion by the focused electron beam irradiation. For the ion irradiation, 10.5 MeV-Fe3+ ion was applied to bombard the F82H steel at 673 K to achieve the displacement damage of ≈20 dpa at the depth of 1.0 μm from surface. Cross-section TEM specimens were prepared by a focused ion beam technique. The shrinkage of carbide particles was observed especially near the irradiation surface. Besides, the lattice fringes at the periphery of carbide were observed in the irradiated M23C6 by the HREM analysis, which is different from that observed in the electron irradiation. It was clarified that the instability of M23C6 is dependent on the irradiation conditions, indicating that the flow rate of vacancy type defects might be the key factor to cause the dissolution of constituent atoms of carbide particles into matrix under irradiation.

1,4-Iron Migration for Expedient Allene Annulations through Iron-Catalyzed C-H/N-H/C-O/C-H Functionalizations.

Science.gov (United States)

Mo, Jiayu; Müller, Thomas; Oliveira, João C A; Ackermann, Lutz

2018-06-25

C-H activation bears great potential for enabling sustainable molecular syntheses in a step- and atom-economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C-H/N-H/C-O/C-H functionalization sequence. The powerful iron catalysis occurred under external-oxidant-free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4-iron migration regime for facile C-H activations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phyllanthus muellerianus and C6H15NO3 synergistic effects on 0.5 M H2SO4-immersed steel-reinforced concrete: Implication for clean corrosion-protection of wind energy structures in industrial environment

Science.gov (United States)

Okeniyi, Joshua Olusegun; Omotosho, Olugbenga Adeshola; Popoola, Abimbola Patricia Idowu; Loto, Cleophas Akintoye

2016-07-01

This paper investigates Phyllanthus muellerianus leaf-extract and C6H15NO3 (triethanolamine: TEA) synergistic effects on reinforcing-steel corrosion-inhibition and the compressive-strength of steel-reinforced concrete immersed in 0.5 M H2SO4. This is to assess suitability of the synergistic admixture usage for wind-energy steel-reinforced concrete structures designed for industrial environments. Steel-reinforced concrete specimens were admixed with individual and synergistic designs of Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures and immersed in the 0.5 M H2SO4. Electrochemical monitoring of corrosion potential, as per ASTM C876-91 R99, and corrosion current were obtained and statistically analysed, as per ASTM G16-95 R04, for modelling noise resistance. Post-immersion compressive-strength testing then followed, as per ASTM C39/C39M-03, for detailing the admixture effect on load-bearing strength of the steel-reinforced concrete specimens. Results showed that while individual Phyllanthus muellerianus leaf-extract concentrations exhibited better inhibition-efficiency performance than C6H15NO3, synergistic additions of C6H15NO3 to Phyllanthus muellerianus leaf-extract improved steel-rebar corrosion-inhibition. Thus, 6 g Phyllanthus muellerianus + 2 g C6H15NO3 synergistically improved inhibition-efficiency to η = 84.17%, from η = 55.28% by the optimal chemical or from η = 74.72% by the optimal plant-extract admixtures. The study also established that improved compressive strength of steel-reinforced concrete with acceptable inhibition of the steel-rebar corrosion could be attained through optimal combination of the Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures.

Study of the unimolecular decompositions of the (C3H6)+2 and (c-C3H6)+2 complexes

International Nuclear Information System (INIS)

Tzeng, W.; Ono, Y.; Linn, S.H.; Ng, C.Y.

1985-01-01

The major product channels identified in the unimolecular decompositions ofC 3 H + 6 xC 3 H 6 and c-C 3 H + 6 xc-C 3 H 6 in the total energy [neutral (C 3 H 6 ) 2 or (c-C 3 H 6 ) 2 heat of formation plus excitation energy] range of approx.230--450 kcal/mol are C 3 H + 7 +C 3 H 5 , C 4 H + 7 +C 2 H 5 , C 4 H + 8 +C 2 H 4 , and C 5 H + 9 +CH 3 . The measured appearance energy for C 4 H + 7 (9.54 +- 0.04 eV) from (C 3 H 6 ) 2 is equal to the thermochemical threshold for the formation of C 4 H + 7 +C 2 H 5 from (C 3 H 6 ) 2 , indicating that the exit potential energy barrier for the ion--molecule reaction C 3 H + 6 +C 3 H 6 →C 4 H + 7 +C 2 H 5 is negligible. There is evidence that the formations of C 4 H + 7 +C 2 H 4 +H from (C 3 H 6 ) + 2 and (c-C 3 H 6 ) + 2 also proceed with high probabilities when they are energetically allowed. The variations of the relative abundances for C 4 H + 7 ,C 4 H + 8 , and C 5 H + 9 from (C 3 H 6 ) + 2 and (c-C 3 H 6 ) + 2 as a function of ionizing photon energy are in qualitative agreement, suggesting that (C 3 H 6 ) + 2 and (c-C 3 H 6 ) + 2 rearrange to similar C 6 H + 12 isomers prior to fragmentation. The fact that C 6 H + 11 is found to be a primary ion from the unimolecular decomposition of (c-C 3 H 6 ) + 2 but not (C 3 H 6 ) + 2 supports the conclusion that the distribution of C 6 H + 12 collision complexes involved in the C 3 H + 6 +C 3 H 6 reactions is different from that in the cyclopropane ion--molecule reactions

The I{sub c}(H)-T{sub c}(H) phase boundary of superconducting Nb thin films with periodic and quasiperiodic antidot arrays

Energy Technology Data Exchange (ETDEWEB)

Bothner, D.; Kemmler, M.; Cozma, R.; Kleiner, R.; Koelle, D. [Physikalisches Institut and Center for Collective Quantum Phenomena, Universitaet Tuebingen (Germany); Misko, V.; Peeters, F. [Departement Fysica, Universiteit Antwerpen (Belgium); Nori, F. [Advanced Science Institute, RIKEN (Japan)

2011-07-01

The magnetic field dependent critical current I{sub c}(H) of superconducting thin films with artificial defects strongly depends on the symmetry of the defect arrangement. Likewise the critical temperature T{sub c}(H) of superconducting wire networks is heavily influenced by the symmetry of the system. Here we present experimental data on the I{sub c}(H)-T{sub c}(H) phase boundary of Nb thin films with artificial defect lattices of different symmetries. For this purpose we fabricated 60 nm thick Nb films with antidots in periodic (triangular) and five different quasiperiodic arrangements. The parameters of the antidot arrays were varied to investigate the influence of antidot diameter and array density. Experiments were performed with high temperature stability ({delta}T<1 mK) at 0.5{<=}T/T{sub c}{<=}1. From the I-V-characteristics at variable H and T we extract I{sub c}(H) and T{sub c}(H) for different voltage and resistance criteria. The experimental data for the critical current density are compared with results from numerical molecular dynamics simulations.

Standard Molar Enthalpy of Formation of RE(C5H8NS2)3(C12H8N2)

Institute of Scientific and Technical Information of China (English)

Meng Xiangxin; Shuai Qi; Chen Sanping; Xie Gang; Gao Shengli; Shi Qizhen

2005-01-01

Four solid ternary complexes of RE (C5H8NS2)3(C12H8N2) (RE=Eu, Gd, Tb, Dy) were synthesized in absolute ethanol by rare earth chloride low hydrate with the mixed ligands of ammonium pyrrolidinedi-thiocarbamate (APDC) and 1, 10-phenanthroline*H2O (o-phen*H2O) in the ordinary laboratory atmosphere without any cautions against moisture or air sensitivity. IR spectra of the complexes show that the RE3+ coordinated with six sulfur atoms of three PDC- and two nitrogen atoms of o-phen*H2O. It was assumed that the coordination number of RE3+ is eight. The constant-volume combustion energies of the complexes, ΔcU, were determined as (-16937.88±9.79 ), (-17588.79±8.62 ), (-17747.14±8.25 ) and (-17840.37±8.87 ) kJ*mol-1, by a precise rotating-bomb calorimeter at 298.15 K. Its standard molar enthalpies of combustion, ΔcHθm, and standard molar enthalpies of formation, ΔfHθm, were calculated as (-16953.37±9.79), (-17604.28±8.62), (-17762.63±8.25), (-17855.86±8.87) kJ*mol-1 and (-857.04±10.52), (-282.43±9.58), (-130.08±9.13), (-55.75±9.83) kJ*mol-1.

A point mutation in the [2Fe–2S] cluster binding region of the NAF-1 protein (H114C) dramatically hinders the cluster donor properties

Energy Technology Data Exchange (ETDEWEB)

Tamir, Sagi; Eisenberg-Domovich, Yael [The Hebrew University of Jerusalem, Edmond J. Safra Campus at Givat Ram, Jerusalem 91904 (Israel); Conlan, Andrea R.; Stofleth, Jason T.; Lipper, Colin H.; Paddock, Mark L. [University of California at San Diego, La Jolla, CA 92093 (United States); Mittler, Ron [University of North Texas, Denton, TX 76203 (United States); Jennings, Patricia A. [University of California at San Diego, La Jolla, CA 92093 (United States); Livnah, Oded, E-mail: oded.livnah@huji.ac.il; Nechushtai, Rachel, E-mail: oded.livnah@huji.ac.il [The Hebrew University of Jerusalem, Edmond J. Safra Campus at Givat Ram, Jerusalem 91904 (Israel)

2014-06-01

NAF-1 has been shown to be related with human health and disease, is upregulated in epithelial breast cancer and suppression of its expression significantly suppresses tumor growth. It is shown that replacement of the single His ligand with Cys resulted in dramatic changes to the properties of its 2Fe-2S clusters without any global crystal structural changes. NAF-1 is an important [2Fe–2S] NEET protein associated with human health and disease. A mis-splicing mutation in NAF-1 results in Wolfram Syndrome type 2, a lethal childhood disease. Upregulation of NAF-1 is found in epithelial breast cancer cells, and suppression of NAF-1 expression by knockdown significantly suppresses tumor growth. Key to NAF-1 function is the NEET fold with its [2Fe–2S] cluster. In this work, the high-resolution structure of native NAF-1 was determined to 1.65 Å resolution (R factor = 13.5%) together with that of a mutant in which the single His ligand of its [2Fe–2S] cluster, His114, was replaced by Cys. The NAF-1 H114C mutant structure was determined to 1.58 Å resolution (R factor = 16.0%). All structural differences were localized to the cluster binding site. Compared with native NAF-1, the [2Fe–2S] clusters of the H114C mutant were found to (i) be 25-fold more stable, (ii) have a redox potential that is 300 mV more negative and (iii) have their cluster donation/transfer function abolished. Because no global structural differences were found between the mutant and the native (wild-type) NAF-1 proteins, yet significant functional differences exist between them, the NAF-1 H114C mutant is an excellent tool to decipher the underlying biological importance of the [2Fe–2S] cluster of NAF-1 in vivo.

A point mutation in the [2Fe–2S] cluster binding region of the NAF-1 protein (H114C) dramatically hinders the cluster donor properties

International Nuclear Information System (INIS)

Tamir, Sagi; Eisenberg-Domovich, Yael; Conlan, Andrea R.; Stofleth, Jason T.; Lipper, Colin H.; Paddock, Mark L.; Mittler, Ron; Jennings, Patricia A.; Livnah, Oded; Nechushtai, Rachel

2014-01-01

NAF-1 has been shown to be related with human health and disease, is upregulated in epithelial breast cancer and suppression of its expression significantly suppresses tumor growth. It is shown that replacement of the single His ligand with Cys resulted in dramatic changes to the properties of its 2Fe-2S clusters without any global crystal structural changes. NAF-1 is an important [2Fe–2S] NEET protein associated with human health and disease. A mis-splicing mutation in NAF-1 results in Wolfram Syndrome type 2, a lethal childhood disease. Upregulation of NAF-1 is found in epithelial breast cancer cells, and suppression of NAF-1 expression by knockdown significantly suppresses tumor growth. Key to NAF-1 function is the NEET fold with its [2Fe–2S] cluster. In this work, the high-resolution structure of native NAF-1 was determined to 1.65 Å resolution (R factor = 13.5%) together with that of a mutant in which the single His ligand of its [2Fe–2S] cluster, His114, was replaced by Cys. The NAF-1 H114C mutant structure was determined to 1.58 Å resolution (R factor = 16.0%). All structural differences were localized to the cluster binding site. Compared with native NAF-1, the [2Fe–2S] clusters of the H114C mutant were found to (i) be 25-fold more stable, (ii) have a redox potential that is 300 mV more negative and (iii) have their cluster donation/transfer function abolished. Because no global structural differences were found between the mutant and the native (wild-type) NAF-1 proteins, yet significant functional differences exist between them, the NAF-1 H114C mutant is an excellent tool to decipher the underlying biological importance of the [2Fe–2S] cluster of NAF-1 in vivo

Breakdown of the Coulomb friction law in TiC/a-C:H nanocomposite coatings

International Nuclear Information System (INIS)

Pei, Y. T.; Huizenga, P.; Galvan, D.; Hosson, J. Th. M. de

2006-01-01

Advanced TiC/a-C:H nanocomposite coatings have been produced via reactive deposition in a closed-field unbalanced magnetron sputtering system (Hauzer HTC-1000 or HTC 1200). In this paper, we report on the tribological behavior of TiC/a-C:H nanocomposite coatings in which ultralow friction is tailored with superior wear resistance, two properties often difficult to achieve simultaneously. Tribotests have been performed at room temperature with a ball-on-disk configuration. In situ monitoring of the wear depth of the coated disk together with the wear height of the ball counterpart at nanometer scale reveals that the self-lubricating effects are induced by the formation of transfer films on the surface of the ball counterpart. A remarkable finding is a breakdown of the Coulomb friction law in the TiC/a-C:H nanocomposite coatings. In addition, the coefficient of friction of TiC/a-C:H nanocomposite coatings decreases with decreasing relative humidity. A superior wear resistance of the coated disk at a level of 10 -17 m 3 /N m (per lap) has been achieved under the condition of superlow friction and high toughness, both of which require fine TiC nanoparticles (e.g., 2 nm) and a wide matrix separation that must be comparable to the dimensions of the nanoparticles

Reaction of the C2H radical with 1-butyne (C4H6): Low Temperature Kinetics and Isomer-Specific Product Detection

Energy Technology Data Exchange (ETDEWEB)

Soorkia, Satchin; Trevitt, Adam J.; Selby, Talitha M.; Osborn, David L.; Taatjes, Craig A.; Wilson, Kevin R.; Leone, Stephen R.

2009-12-22

The rate coefficient for the reaction of the ethynyl radical (C{sub 2}H) with 1-butyne (H-C{triple_bond}C-CH{sub 2}-CH{sub 3}) is measured in a pulsed Laval nozzle apparatus. Ethynyl radicals are formed by laser photolysis of acetylene (C{sub 2}H{sub 2}) at 193 nm and detected via chemiluminescence (C{sub 2}H + O{sub 2} {yields} CH (A{sup 2}{Delta}) + CO{sub 2}). The rate coefficients are measured over the temperature range of 74-295 K. The C{sub 2}H + 1-butyne reaction exhibits no barrier and occurs with rate constants close to the collision limit. The temperature dependent rate coefficients can be fit within experimental uncertainties by the expression k = (2.4 {+-} 0.5) x 10{sup -10} (T/295 K)-(0.04 {+-} 0.03) cm{sup 3} molecule{sup -1}s{sup -1}. Reaction products are detected at room temperature (295 K) and 533 Pa using a Multiplexed Photoionization Mass Spectrometer (MPIMS) coupled to the tunable VUV synchrotron radiation from the Advanced Light Source at the Lawrence Berkeley National Laboratory. Two product channels are identified for this reaction: m/z = 64 (C{sub 5}H{sub 4}) and m/z = 78 (C{sub 6}H{sub 6}) corresponding to the CH{sub 3}- and H-loss channels, respectively. Photoionization efficiency (PIE) curves are used to analyze the isomeric composition of both product channels. The C{sub 5}H{sub 4} products are found to be exclusively linear isomers composed of ethynylallene and methyldiacetylene in a 4:1 ratio. In contrast, the C{sub 6}H{sub 6} product channel includes two cyclic isomers, fulvene 18({+-}5)% and 3,4-dimethylenecyclobut-1-ene 32({+-}8)%, as well as three linear isomers, 2-ethynyl-1,3-butadiene 8({+-}5)%, 3,4-hexadiene-1-yne 28({+-}8)% and 1,3-hexadiyne 14({+-}5)%. Within experimental uncertainties, we do not see appreciable amounts of benzene and an upper limit of 10% is estimated. Diacetylene (C{sub 4}H{sub 2}) formation via the C{sub 2}H{sub 5}-loss channel is also thermodynamically possible but cannot be observed due to experimental

Zinc-induced Self-association of Complement C3b and Factor H

Science.gov (United States)

Nan, Ruodan; Tetchner, Stuart; Rodriguez, Elizabeth; Pao, Po-Jung; Gor, Jayesh; Lengyel, Imre; Perkins, Stephen J.

2013-01-01

The sub-retinal pigment epithelial deposits that are a hallmark of age-related macular degeneration contain both C3b and millimolar levels of zinc. C3 is the central protein of complement, whereas C3u is formed by the spontaneous hydrolysis of the thioester bridge in C3. During activation, C3 is cleaved to form active C3b, then C3b is inactivated by Factor I and Factor H to form the C3c and C3d fragments. The interaction of zinc with C3 was quantified using analytical ultracentrifugation and x-ray scattering. C3, C3u, and C3b associated strongly in >100 μm zinc, whereas C3c and C3d showed weak association. With zinc, C3 forms soluble oligomers, whereas C3u and C3b precipitate. We conclude that the C3, C3u, and C3b association with zinc depended on the relative positions of C3d and C3c in each protein. Computational predictions showed that putative weak zinc binding sites with different capacities exist in all five proteins, in agreement with experiments. Factor H forms large oligomers in >10 μm zinc. In contrast to C3b or Factor H alone, the solubility of the central C3b-Factor H complex was much reduced at 60 μm zinc and even more so at >100 μm zinc. The removal of the C3b-Factor H complex by zinc explains the reduced C3u/C3b inactivation rates by zinc. Zinc-induced precipitation may contribute to the initial development of sub-retinal pigment epithelial deposits in the retina as well as reducing the progression to advanced age-related macular degeneration in higher risk patients. PMID:23661701

Direct measurements of rate constants for the reactions of CH3 radicals with C2H6, C2H4, and C2H2 at high temperatures.

Science.gov (United States)

Peukert, S L; Labbe, N J; Sivaramakrishnan, R; Michael, J V

2013-10-10

The shock tube technique has been used to study the reactions CH3 + C2H6 → C2H4 + CH4 + H (1), CH3 + C2H4 → Products + H (2), and CH3 + C2H2 → Products + H (3). Biacetyl, (CH3CO)2, was used as a clean high temperature thermal source for CH3-radicals for all the three reactions studied in this work. For reaction 1, the experiments span a T-range of 1153 K ≤ T ≤ 1297 K, at P ~ 0.4 bar. The experiments on reaction 2 cover a T-range of 1176 K ≤ T ≤ 1366 K, at P ~ 1.0 bar, and those on reaction 3 a T-range of 1127 K ≤ T ≤ 1346 K, at P ~ 1.0 bar. Reflected shock tube experiments performed on reactions 1-3, monitored the formation of H-atoms with H-atom Atomic Resonance Absorption Spectrometric (ARAS). Fits to the H-atom temporal profiles using an assembled kinetics model were used to make determinations for k1, k2, and k3. In the case of C2H6, the measurements of [H]-atoms were used to derive direct high-temperature rate constants, k1, that can be represented by the Arrhenius equation k1(T) = 5.41 × 10(-12) exp(-6043 K/T) cm(3) molecules(-1) s(-1) (1153 K ≤ T ≤ 1297 K) for the only bimolecular process that occurs, H-atom abstraction. TST calculations based on ab initio properties calculated at the CCSD(T)/CBS//M06-2X/cc-pVTZ level of theory show excellent agreement, within ±20%, of the measured rate constants. For the reaction of CH3 with C2H4, the present rate constant results, k2', refer to the sum of rate constants, k(2b) + k(2c), from two competing processes, addition-elimination, and the direct abstraction CH3 + C2H4 → C3H6 + H (2b) and CH3 + C2H4 → C2H2 + H + CH4 (2c). Experimental rate constants for k2' can be represented by the Arrhenius equation k2'(T) = 2.18 × 10(-10) exp(-11830 K/T) cm(3) molecules(-1) s(-1) (1176 K ≤ T ≤ 1366 K). The present results are in excellent agreement with recent theoretical predictions. The present study provides the only direct measurement for the high-temperature rate constants for these channels

The formation of [M-H]+ ions in N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione derivatives during atmospheric pressure photoionization mass spectrometry

KAUST Repository

Sioud, Salim

2014-10-09

RESULTS [M-H]+ ions were observed under APPI conditions. The type of dopant and the length of the alkyl chain affected the formation of these ions. MS/MS fragmentation of [M-H]+ and [M + H]+ ions exhibited completely different patterns. Theoretical calculations revealed that the loss of hydrogen molecules from the [M + H]+ ions is the most favourable condition under which to form [M-H]+ ions.CONCLUSIONS [M-H]+ ions were detected in all the TPD derivatives studied here under the special experimental conditions during APPI, using a halogenated benzene dopant, and TPD containing substituted N-alkyl side chains with a minimum of four carbon atoms. Density functional theory calculations showed that for [M-H]+ ions to be formed under these conditions, the loss of hydrogen molecules from the [M + H]+ ions is proposed to be necessary.RATIONALE The formation of ions during atmospheric pressure photoionization (APPI) mass spectrometry in the positive mode usually provides radical cations and/or protonated species. Intriguingly, during the analysis of some N-alkyl-substituted thieno[3,4-c]pyrrole-4,6-dione (TPD) derivatives synthesized in our laboratory, unusual [M-H]+ ion peaks were observed. In this work we investigate the formation of [M-H]+ ions observed under APPI conditions.METHODS Multiple experimental parameters, including the type of ionization source, the composition of the solvent, the type of dopant, the infusion flow rate, and the length of the alkyl side chain were investigated to determine their effects on the formation of [M-H]+ ions. In addition, a comparison study of the gas-phase tandem mass spectrometric (MS/MS) fragmentation of [M + H]+ vs [M-H]+ ions and computational approaches were used.

Tribological properties of TiC/a-C:H nanocomposite coatings prepared via HiPIMS

Science.gov (United States)

Sánchez-López, J. C.; Dominguez-Meister, S.; Rojas, T. C.; Colasuonno, M.; Bazzan, M.; Patelli, A.

2018-05-01

High power impulse magnetron sputtering (HiPIMS) technology has been employed to prepare TiC/a-C:H nanocomposite coatings from a titanium target in acetylene (C2H2) reactive atmospheres. Gas fluxes were varied from 1.3 to 4.4 sccm to obtain C/Ti ratios from 2 to 15 as measured by electron probe microanalysis (EPMA). X-ray diffraction and transmission electron microscopy demonstrate the presence of TiC nanocrystals embedded in an amorphous carbon-based matrix. The hardness properties decrease from 17 to 10 GPa as the carbon content increases. The tribological properties were measured using a pin-on-disk tribometer in ambient air (RH = 30-40%) at 10 cm/s with 5 N of applied load against 6-mm 100Cr6 balls. The friction coefficient and the film wear rates are gradually improved from 0.3 and 7 × 10-6 mm3/N m to 0.15 and 2 × 10-7 mm3/N m, respectively, by increasing the C2H2 flux. To understand the tribological processes appearing at the interface and to elucidate the wear mechanism, microstructural and chemical investigations of the coatings were performed before and after the friction test. EPMA, X-ray photoelectron and electron energy-loss spectroscopies were employed to obtain an estimation of the fraction of the a-C:H phase, which can be correlated with the tribological behavior. Examination of the friction counterfaces (ball and track) by Raman microanalysis reveals an increased ordering of the amorphous carbon phase concomitant with friction reduction. The tribological results were compared with similar TiC/a-C(:H) composites prepared by the conventional direct current process.

Photodissociation of pyrene cations: structure and energetics from C16H10(+) to C14(+) and almost everything in between.

Science.gov (United States)

West, Brandi; Useli-Bacchitta, Francesca; Sabbah, Hassan; Blanchet, Valérie; Bodi, Andras; Mayer, Paul M; Joblin, Christine

2014-09-11

The unimolecular dissociation of the pyrene radical cation, C16H10(+•), has been explored using a combination of computational techniques and experimental approaches, such as multiple photon absorption in the cold ion trap Piège à Ions pour la Recherche et l'Etude de Nouvelles Espèces Astrochimiques (PIRENEA) and imaging photoelectron photoion coincidence spectrometry (iPEPICO). In total, 22 reactions, involving the fragmentation cascade (H, C2H2, and C4H2 loss) from the pyrene radical cation down to the C14(+•) fragment ion, have been studied using PIRENEA. Branching ratios have been measured for reactions from C16H10(+•), C16H8(+•), and C16H5(+). Density functional theory calculations of the fragmentation pathways observed experimentally and postulated theoretically lead to 17 unique structures. One important prediction is the opening of the pyrene ring system starting from the C16H4(+•) radical. In the iPEPICO experiments, only two reactions could be studied, namely, R1 C16H10(+•) → C16H9(+) + H (m/z = 201) and R2 C16H9(+) → C16H8(+•) + H (m/z = 200). The activation energies for these reactions were determined to be 5.4 ± 1.2 and 3.3 ± 1.1 eV, respectively.

Measurement of 2J(H,C)- and 3J(H,C)-coupling constants by α/β selective HC(C)H-TOCSY

International Nuclear Information System (INIS)

Duchardt, Elke; Richter, Christian; Reif, Bernd; Glaser, Steffen J.; Engels, Joachim W.; Griesinger, Christian; Schwalbe, Harald

2001-01-01

A new heteronuclear NMR pulse sequence for the measurement of n J(C,H) coupling constants, the α/βselective HC(C)H-TOCSY, is described. It is shown that the S 3 E element (Meissner et al., 1997a,b) can be used to obtain spin state selective coherence transfer in molecules, in which adjacent CH moieties are labeled with 13 C. Application of the α/β selective HC(C)H-TOCSY to a 10nt RNA tetraloop 5'-CGCUUUUGCG-3', in which the four uridine residues are 13 C labeled in the sugar moiety, allowed measurement of two bond and three bond J(C,H) coupling constants, which provide additional restraints to characterize the sugar ring conformation of RNA in cases of conformational averaging

What is the best bonding model of the (σ-H-BR) species bound to a transition metal? Bonding analysis in complexes [(H)2Cl(PMe3)2M(σ-H-BR)] (M = Fe, Ru, Os).

Science.gov (United States)

Pandey, Krishna K

2012-03-21

Density Functional Theory calculations have been performed for the σ-hydroboryl complexes of iron, ruthenium and osmium [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] (M = Fe, Ru, Os; R = OMe, NMe(2), Ph) at the BP86/TZ2P/ZORA level of theory in order to understand the interactions between metal and HBR ligands. The calculated geometries of the complexes [(H)(2)Cl(PMe(3))(2)Ru(HBNMe(2))], [(H)(2)Cl(PMe(3))(2)Os(HBR)] (R = OMe, NMe(2)) are in excellent agreement with structurally characterized complexes [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))], [(H)(2)Cl(P(i)Pr(3))(2)Os{σ-H-BOCH(2)CH(2)OB(O(2)CH(2)CH(2))}] and [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))]. The longer calculated M-B bond distance in complex [(H)(2)Cl(PMe(3))(2)M(σ-H-BNMe(2))] are due to greater B-N π bonding and as a result, a weaker M-B π-back-bonding. The B-H2 bond distances reveal that (i) iron complexes contain bis(σ-borane) ligand, (ii) ruthenium complexes contain (σ-H-BR) ligands with a stretched B-H2 bond, and (iii) osmium complexes contain hydride (H2) and (σ-H-BR) ligands. The H-BR ligands in osmium complexes are a better trans-directing ligand than the Cl ligand. Values of interaction energy, electrostatic interaction, orbital interaction, and bond dissociation energy for interactions between ionic fragments are very large and may not be consistent with M-(σ-H-BR) bonding. The EDA as well as NBO and AIM analysis suggest that the best bonding model for the M-σ-H-BR interactions in the complexes [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] is the interaction between neutral fragments [(H)(2)Cl(PMe(3))(2)M] and [σ-H-BR]. This becomes evident from the calculated values for the orbital interactions. The electron configuration of the fragments which is shown for C in Fig. 1 experiences the smallest change upon the M-σ-H-BR bond formation. Since model C also requires the least amount of electronic excitation and geometry changes of all models given by the ΔE(prep) values, it is clearly the most appropriate choice of

The C-terminal domains of NF-H and NF-M subunits maintain axonal neurofilament content by blocking turnover of the stationary neurofilament network.

Directory of Open Access Journals (Sweden)

Mala V Rao

Full Text Available Newly synthesized neurofilaments or protofilaments are incorporated into a highly stable stationary cytoskeleton network as they are transported along axons. Although the heavily phosphorylated carboxyl-terminal tail domains of the heavy and medium neurofilament (NF subunits have been proposed to contribute to this process and particularly to stability of this structure, their function is still obscure. Here we show in NF-H/M tail deletion [NF-(H/M(tailΔ] mice that the deletion of both of these domains selectively lowers NF levels 3-6 fold along optic axons without altering either rates of subunit synthesis or the rate of slow axonal transport of NF. Pulse labeling studies carried out over 90 days revealed a significantly faster rate of disappearance of NF from the stationary NF network of optic axons in NF-(H/M(tailΔ mice. Faster NF disappearance was accompanied by elevated levels of NF-L proteolytic fragments in NF-(H/M(tailΔ axons. We conclude that NF-H and NF-M C-terminal domains do not normally regulate NF transport rates as previously proposed, but instead increase the proteolytic resistance of NF, thereby stabilizing the stationary neurofilament cytoskeleton along axons.

m-plane GaN layers grown by rf-plasma assisted molecular beam epitaxy with varying Ga/N flux ratios on m-plane 4H-SiC substrates

International Nuclear Information System (INIS)

Armitage, R.; Horita, M.; Suda, J.; Kimoto, T.

2007-01-01

A series of m-plane GaN layers with the Ga beam-equivalent pressure (BEP) as the only varied parameter was grown by rf-plasma assisted molecular beam epitaxy on m-plane 4H-SiC substrates using AlN buffer layers. The smoothest growth surfaces and most complete film coalescence were found for the highest Ga BEP corresponding to the Ga droplet accumulation regime. However, better structural quality as assessed by x-ray rocking curves was observed for growth at a lower Ga BEP value below the droplet limit. The variation of rocking curve widths for planes inclined with respect to the epilayer c axis followed a different trend with Ga BEP than those of reflections parallel to the c axis. The GaN layers were found to exhibit a large residual compressive strain along the a axis

C60H- an intermediate in the photochemical reduction of C60 fullerene with triethylamine

International Nuclear Information System (INIS)

Stasko, A.; Brezova, V.; Neudeck, A.; Bartl, A.; Dunsch, L.

1999-01-01

The systematic investigations on the photo reduction of C 60 fullerene and its derivatives using triethylamine and TiO 2 donors, and also other techniques, verified the formation of C 60 .- . Formation of the mono-anion a narrow EPR line (pp A = 0.1 mT) was observed. During a continuous irradiation line A is replaced with line B having g B - 2.0006 and pp B = 0.04 mT which also vanished under prolonged irradiation. But lines A and B repeated after stopping irradiation. This unusual behaviour was re-investigated in analogous EPR-NIR experiments using now a rapid NIR spectrometer. The band at 996 nm was assigned to C 60 H - . The mechanism of C 60 H - formation is discussed

Ceramics and M.H.D

International Nuclear Information System (INIS)

Yvars, M.

1979-10-01

The materials considered for the insulating walls of a M.H.D. converter are Al 2 O 3 , and the calcium or strontium zirconates. For the conducting walls electricity conducting oxides are being considered such as ZrO 2 or CrO 3 La essentially. The principle of M.H.D. systems is recalled, the materials considered are described as is their behaviour in the corrosive atmospheres of M.H.D. streams [fr

Si/C and H coadsorption at 4H-SiC{0001} surfaces

Energy Technology Data Exchange (ETDEWEB)

Wachowicz, E., E-mail: elwira@ifd.uni.wroc.pl [Institute of Experimental Physics, University of Wrocław, Plac M. Borna 9, PL-50-204 Wrocław (Poland); Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, Pawińskiego 5a, PL-02-106 Warsaw (Poland)

2016-06-15

Highlights: • Si on C-terminated and C on Si-terminated surface adsorb in the H{sub 3} hollow site. • The preferred adsorption site is in contrary to the stacking order of bulk crystal. • The presence of hydrogen increases the adsorption energy of Si/C. • Hydrogen weakens the bonds between the adsorbed Si or C and the surface. • Carbon adsorbs on top of the surface carbon on the C-terminated surface. • With both C and H on Si-terminated surface the surface state vanishes. - Abstract: Density functional theory (DFT) study of adsorption of 0.25 monolayer of either Si or C on 4H-SiC{0001} surfaces is presented. The adsorption in high-symmetry sites on both Si- and C-terminated surfaces was examined and the influence of the preadsorbed 0.25 ML of hydrogen on the Si/C adsorption was considered. It was found out that for Si on C-terminated surface and C on Si-terminated the most favourable is threefolded adsorption site on both clean and H-precovered surface. This is contrary to the bulk crystal stacking order which would require adsorption on top of the topmost surface atom. In those cases, the presence of hydrogen weakens the bonding of the adsorbate. Carbon on the C-terminated surface, only binds on-top of the surface atom. The C−C bond-length is almost the same for the clean surface and for one with H and equals to ∼1.33 Å which is shorter by ∼0.2 than in diamond. The analysis of the electronic structure changes under adsorption is also presented.

Molecular and crystal structure of nido-9-C5H5N-11-I-7,8-C2B9H10: supramolecular architecture via hydrogen bonding X-H...I (X = B, C)

International Nuclear Information System (INIS)

Polyanskaya, T.M.

2006-01-01

A monocrystal X-ray diffraction study of a new iodine-containing cluster compound 9-(pyridine)-11-iodo-decahydro-7,8-dicarba-nido-undecaborane [9-C 5 H 5 N-11-I-7,8-C 2 B 9 H 10 ] has been performed. Crystal data: C 7 H 15 B 9 NI, M = 337.39, monoclinic, space group P2 1 /c, unit cell parameters: a=9.348(1) A, b=11.159(1) A, c=13.442(2) A, β=98.13(1) deg, V=1388.1(5) A 3 , Z=4, d calc = 1.614 g/cm 3 , T = 295 K, F(000)=648, μ=2.276 mm -1 . The structure was solved by a direct method and refined in the full-matrix anisotropic approximation (isotropic for hydrogen atoms) to final agreement factors R 1 = 0.0254, wR 2 = 0.0454 for 2437 I hkl >2σ I from 3590 measured I hkl (an Enraf-Nonius CAD-4 diffractometer, λMoK α , graphite monochromator, θ/2θ-scanning). The molecules are joined into a supramolecular assembly by hydrogen bonds X-H...I (X = B, C) [ru

Design and Investigation of SST/nc-Si:H/M (M = Ag, Au, Ni and M/nc-Si:H/M Multifunctional Devices

Directory of Open Access Journals (Sweden)

A. F. Qasrawi

2013-01-01

Full Text Available Hydrogenated nanocrystalline Silicon thin films prepared by the very high frequency chemical vapor deposition technique (VHF-CVD on stainless steel (SST substrates are used to design Schottky point contact barriers for the purpose of solar energy conversion and passive electronic component applications. In this process, the contact performance between SST and M (M = Ag, Au, and Ni and between Ag, Au, and Ni electrodes was characterized by means of current-voltage, capacitance-voltage, and light intensity dependence of short circuit ( current and open circuit voltage ( of the contacts. Particularly, the devices ideality factors, barrier heights were evaluated by the Schottky method and compared to the Cheung's. Best Schottky device performance with lowest ideality factor suitable for electronic applications was observed in the SST/nc-Si:H/Ag structure. This device reflects a of 229 mV with an of 1.6 mA/cm2 under an illumination intensity of ~40 klux. On the other hand, the highest being 9.0 mA/cm2 and the of 53.1 mV were observed for Ni/nc-Si:H/Au structure. As these voltages represent the maximum biasing voltage for some of the designed devices, the SST/nc-Si:H/M and M/nc-Si:H/M can be regarded as multifunctional self-energy that provided electronic devices suitable for active or passive applications.

Modelling of phase equilibria in CH4–C2H6–C3H8–nC4H10–NaCl–H2O systems

International Nuclear Information System (INIS)

Li, Jun; Zhang, Zhigang; Luo, Xiaorong; Li, Xiaochun

2015-01-01

Highlights: • A new model was established for the phase equilibria of C1–C2–C3–nC4–brine systems. • The model can reproduce of hydrocarbon–brine equilibria to high T&P and salinity. • The model can well predict H 2 O solubility in light hydrocarbon rich phases. - Abstract: A thermodynamic model is presented for the mutual solubility of CH 4 –C 2 H 6 –C 3 H 8 –nC 4 H 10 –brine systems up to high temperature, pressure and salinity. The Peng–Robinson model is used for non-aqueous phase fugacity calculations, and the Pitzer model is used for aqueous phase activity calculations. The model can accurately reproduce the experimental solubilities of CH 4 , C 2 H 6 , C 3 H 8 and nC 4 H 10 in water or NaCl solutions and H 2 O solubility in the non-aqueous phase. The experimental data of mutual solubility for the CH 4 –brine subsystem are sufficient for temperatures exceeding 250 °C, pressures exceeding 1000 bar and NaCl molalities greater than 6 molal. Compared to the CH 4 –brine system, the mutual solubility data of C 2 H 6 –brine, C 3 H 8 –brine and nC 4 H 10 –brine are not sufficient. Based on the comparison with the experimental data of H 2 O solubility in C 2 H 6 -, C 3 H 8 - or nC 4 H 10 -rich phases, the model has an excellent capability for the prediction of H 2 O solubility in hydrocarbon-rich phases, as these experimental data were not used in the modelling. Predictions of hydrocarbon solubility (at temperatures up to 200 °C, pressures up to 1000 bar and NaCl molalities greater than 6 molal) were made for the C 2 H 6 –brine, C 3 H 8 –brine and nC 4 H 10 –brine systems. The predictions suggest that increasing pressure generally increases the hydrocarbon solubility in water or brine, especially in the lower-pressure region. Increasing temperature usually decreases the hydrocarbon solubility at lower temperatures but increases the hydrocarbon solubility at higher temperatures. Increasing water salinity dramatically decreases

Understanding trends in C-H bond activation in heterogeneous catalysis.

Science.gov (United States)

Latimer, Allegra A; Kulkarni, Ambarish R; Aljama, Hassan; Montoya, Joseph H; Yoo, Jong Suk; Tsai, Charlie; Abild-Pedersen, Frank; Studt, Felix; Nørskov, Jens K

2017-02-01

While the search for catalysts capable of directly converting methane to higher value commodity chemicals and liquid fuels has been active for over a century, a viable industrial process for selective methane activation has yet to be developed. Electronic structure calculations are playing an increasingly relevant role in this search, but large-scale materials screening efforts are hindered by computationally expensive transition state barrier calculations. The purpose of the present letter is twofold. First, we show that, for the wide range of catalysts that proceed via a radical intermediate, a unifying framework for predicting C-H activation barriers using a single universal descriptor can be established. Second, we combine this scaling approach with a thermodynamic analysis of active site formation to provide a map of methane activation rates. Our model successfully rationalizes the available empirical data and lays the foundation for future catalyst design strategies that transcend different catalyst classes.

A two-state computational investigation of methane C--H and ethane C--C oxidative addition to [CpM(PH3)]n+ (M = Co, Rh, Ir; n = 0, 1).

Science.gov (United States)

Petit, Alban; Richard, Philippe; Cacelli, Ivo; Poli, Rinaldo

2006-01-11

Reductive elimination of methane from methyl hydride half-sandwich phosphane complexes of the Group 9 metals has been investigated by DFT calculations on the model system [CpM(PH(3))(CH(3))(H)] (M = Co, Rh, Ir). For each metal, the unsaturated product has a triplet ground state; thus, spin crossover occurs during the reaction. All relevant stationary points on the two potential energy surfaces (PES) and the minimum energy crossing point (MECP) were optimized. Spin crossover occurs very near the sigma-CH(4) complex local minimum for the Co system, whereas the heavier Rh and Ir systems remain in the singlet state until the CH(4) molecule is almost completely expelled from the metal coordination sphere. No local sigma-CH(4) minimum was found for the Ir system. The energetic profiles agree with the nonexistence of the Co(III) methyl hydride complex and with the greater thermal stability of the Ir complex relative to the Rh complex. Reductive elimination of methane from the related oxidized complexes [CpM(PH(3))(CH(3))(H)](+) (M = Rh, Ir) proceeds entirely on the spin doublet PES, because the 15-electron [CpM(PH(3))](+) products have a doublet ground state. This process is thermodynamically favored by about 25 kcal mol(-1) relative to the corresponding neutral system. It is essentially barrierless for the Rh system and has a relatively small barrier (ca. 7.5 kcal mol(-1)) for the Ir system. In both cases, the reaction involves a sigma-CH(4) intermediate. Reductive elimination of ethane from [CpM(PH(3))(CH(3))(2)](+) (M = Rh, Ir) shows a similar thermodynamic profile, but is kinetically quite different from methane elimination from [CpM(PH(3))(CH(3))(H)](+): the reductive elimination barrier is much greater and does not involve a sigma-complex intermediate. The large difference in the calculated activation barriers (ca. 12.0 and ca. 30.5 kcal mol(-1) for the Rh and Ir systems, respectively) agrees with the experimental observation, for related systems, of oxidatively

Routine production of H11CN and :11C:-1-aminocyclopentanecarboxylic acid

International Nuclear Information System (INIS)

Sambre, J.; Vandecasteele, C.; Geothals, P.; Rabi, N.A.; Haver, D. van; Slegers, G.

1985-01-01

The production of H 11 CN using the 14 N(p,α) 11 C reaction, was studied. The yield is 140 mCi/μA at saturation (EOB). From 1.8 Ci of H 11 CN 140 mCi of [ 11 C]ACPC are produced routinely and under remote-control. Chemical and pharmaceutical controls showed that the product is suitable for injection. (author)

Structural insights into drug development strategy targeting EGFR T790M/C797S.

Science.gov (United States)

Zhu, Su-Jie; Zhao, Peng; Yang, Jiao; Ma, Rui; Yan, Xiao-E; Yang, Sheng-Yong; Yang, Jing-Wen; Yun, Cai-Hong

2018-03-02

Treatment of non-small-cell lung cancers (NSCLCs) harboring primary EGFR oncogenic mutations such as L858R and exon 19 deletion delE746_A750 (Del-19) using gefitinib/erlotinib ultimately fails due to the emergence of T790M mutation. Though WZ4002/CO-1686/AZD9291 are effective in overcoming EGFR T790M by targeting Cys797 via covalent bonding, their efficacy is again limited due to the emergence of C797S mutation. New agents effectively inhibiting EGFR T790M without covalent linkage through Cys 797 may solve this problem. We presented here crystal structures of EGFR activating/drug-resistant mutants in complex with a panel of reversible inhibitors along with mutagenesis and enzyme kinetic data. These data revealed a previously un-described hydrophobic clamp structure in the EGFR kinase which may be exploited to facilitate development of next generation drugs targeting EGFR T790M with or without concomitant C797S. Interestingly, mutations in the hydrophobic clamp that hinder drug binding often also weaken ATP binding and/or abolish kinase activity, thus do not readily result in resistance to the drugs.

Cp*Co(III) Catalyzed Site-Selective C-H Activation of Unsymmetrical O-Acyl Oximes: Synthesis of Multisubstituted Isoquinolines from Terminal and Internal Alkynes.

Science.gov (United States)

Sun, Bo; Yoshino, Tatsuhiko; Kanai, Motomu; Matsunaga, Shigeki

2015-10-26

The synthesis of isoquinolines by site-selective C-H activation of O-acyl oximes with a Cp*Co(III) catalyst is described. In the presence of this catalyst, the C-H activation of various unsymmetrically substituted O-acyl oximes selectively occurred at the sterically less hindered site, and reactions with terminal as well as internal alkynes afforded the corresponding products in up to 98 % yield. Whereas the reactions catalyzed by the Cp*Co(III) system proceeded with high site selectivity (15:1 to 20:1), use of the corresponding Cp*Rh(III) catalysts led to low selectivities and/or yields when unsymmetrical O-acyl oximes and terminal alkynes were used. Deuterium labeling studies indicate a clear difference in the site selectivity of the C-H activation step under Cp*Co(III) and Cp*Rh(III) catalysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development and Validation of a Liquid Medium (M7H9C) for Routine Culture of Mycobacterium avium subsp. paratuberculosis To Replace Modified Bactec 12B Medium

Science.gov (United States)

Whittington, Ann-Michele; Waldron, Anna; Begg, Douglas J.; de Silva, Kumi; Purdie, Auriol C.; Plain, Karren M.

2013-01-01

Liquid culture of Mycobacterium avium subsp. paratuberculosis from clinical samples, such as feces, is the most sensitive antemortem test for the diagnosis of Johne's disease in ruminants. In Australia, New Zealand, the United States, and some other countries, the Bactec 460 system with modified Bactec 12B medium (Becton, Dickinson) has been the most commonly used liquid culture system, but it was discontinued in 2012. In this study, a new liquid culture medium, M7H9C, was developed. It consists of a Middlebrook 7H9 medium base with added Casitone, albumin, dextrose, catalase, egg yolk, mycobactin J, and a cocktail of antibiotics. We found that polyoxyethylene stearate (POES) was not essential for the cultivation of M. avium subsp. paratuberculosis in either the Bactec 12B or the M7H9C medium. The limit of detection determined using pure cultures of the C and S strains of M. avium subsp. paratuberculosis was 7 bacilli per 50 μl inoculum in the two media. The new medium was validated using 784 fecal and tissue samples from sheep and cattle, >25% of which contained viable M. avium subsp. paratuberculosis. Discrepant results for the clinical samples between the two media were mostly associated with samples that contained <10 viable bacilli per gram, but these results were relatively uncommon, and the performances of the two media were not significantly different. M7H9C medium was less than half the cost of the Bactec 12B medium and did not require regular examination during incubation, but a confirmatory IS900 PCR test had to be performed on every culture after the predetermined incubation period. PMID:24048541

Electrooxidative Rhodium-Catalyzed C-H/C-H Activation: Electricity as Oxidant for Cross-Dehydrogenative Alkenylation.

Science.gov (United States)

Qiu, Youai; Kong, Wei-Jun; Struwe, Julia; Sauermann, Nicolas; Rogge, Torben; Scheremetjew, Alexej; Ackermann, Lutz

2018-04-06

Rhodium(III) catalysis has enabled a plethora of oxidative C-H functionalizations, which predominantly employ stoichiometric amounts of toxic and/or expensive metal oxidants. In contrast, we describe the first electrochemical C-H activation by rhodium catalysis that avoids hazardous chemical oxidants. Thus, environmentally-benign twofold C-H/C-H functionalizations were accomplished with weakly-coordinating benzoic acids and benzamides, employing electricity as the terminal oxidant with H2 as the sole byproduct. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theoretical survey on M@C_8_0 (M = Ca, Sr, and Ba): Behavior of different alkaline earth metal impacting the chemical stability and electronic properties

International Nuclear Information System (INIS)

Cui, Jin-Bo; Guo, Yi-Jun; Li, Qiao-Zhi; Zhao, Pei; Zhao, Xiang

2016-01-01

Structures of mono-metallofullerenes M@C_8_0 (M = Ca, Sr, and Ba) that separated in early experiment are determined owning the C_2_v(31920)-C_8_0 cage. The change rule of properties for M@C_8_0 (M = Ca, Sr, and Ba) influenced by different inner metal are discussed. As the trapped metal changes from calcium to barium, performance of thermodynamic stabilities for M@C_2_v(31920)-C_8_0, M@C_2_v(31922)-C_8_0, and M@D_5_h(31923)-C_8_0 are significantly different. Orbital analysis suggests that the lowest unoccupied molecular orbitals (LUMOs) of Ca@C_2_v(31920)-C_8_0 and Ca@D_5_h(31923)-C_8_0 are mostly located on the trapped metal, whereas reduction reactions of Ca@C_2_v(31920)-C_8_0 and Ca@D_5_h(31923)-C_8_0 occur on the fullerene cage. Natural electron configuration analyses demonstrates that the decentralized electron back-donation of Ba@C_2_v(31920)-C_8_0 would take responsible for the instability of itself. Electronic properties such as electron affinities and ionization potentials are significantly affected by encapsulated metal are also found. Computational UV–visible–NIR spectra for M@C_2_v(31920)-C_8_0 (M = Ca, Sr, Ba) are in perfect accord with the spectra obtained experimentally.

Intrinsic magnetic properties of Sm{sub 2}Fe{sub 17-x}M{sub x}N{sub y}/C{sub y} (M=Al, Ga or Si)

Energy Technology Data Exchange (ETDEWEB)

Kubis, M.; Eckert, D.; Gebel, B.; Mueller, K.-H. E-mail: khm@ifw-dresden.de; Schultz, L

2000-07-01

Curie temperature T{sub c}, saturation polarization J{sub s} and anisotropy field H{sub a} of Sm{sub 2}Fe{sub 17-x}M{sub x}N{sub y}/C{sub y} with M=Al, Ga or Si (x{<=}3, y{approx}3) were determined by thermomagnetic measurements and a numerical fitting procedure of demagnetization curves. An increasing amount of the substitutional element M leads to an increase of T{sub c} of the Sm{sub 2}Fe{sub 17-x}M{sub x} parent compounds and generally to a decrease of T{sub c}, J{sub s} and H{sub a} for the interstitial nitrides and carbides. However, for small M contents, x{<=}1, an increased H{sub a} was observed compared to the substitution-free interstitial compounds. Gas-carburized and melt-carburized Sm{sub 2}Fe{sub 15}Ga{sub 2}C{sub y} samples showed large differences in J{sub s} and H{sub a} but identical T{sub c} values.

Charge transfer processes in collisions of H+ ions with H2, D2, CO, CO2 CH4, C2H2, C2H6 and C3H8 molecules below 10 keV

International Nuclear Information System (INIS)

Kusakabe, T.; Buenker, R.J.; Kimura, M.

2002-01-01

Charge transfer processes resulting from collisions of H + ions with H 2 , D 2 , CO, CO 2 CH 4 , C 2 H 2 , C 2 H 6 and C 3 H 8 molecules have been investigated in the energy range of 0.2 to 4.0 keV experimentally and theoretically. The initial growth rate method was employed in the experiment for studying the dynamics and cross sections. Theoretical analysis based on a molecular-orbital expansion method for H 2 , D 2 , CO, CH 4 and C 2 H 2 targets was also carried out. The present results for the H 2 , CO and CO 2 molecules by H + impact are found to be in excellent accord with most of previous measurements above 1 keV, but they show some differences below this energy where our result displays a stronger energy-dependence. For CH 4 , C 2 H 2 , C 2 H 6 and C 3 H 8 targets, both experimental and theoretical results indicate that if one assumes vibrationally excited molecular ions (CH 4 + , C 2 H 2 + , C 2 H 6 + and C 3 H 8 + ) formed in the exit channel, then charge transfer processes sometimes become more favorable since these vibrationally excited fragments meet an accidental resonant condition. This is a clear indication of the role of vibrational excited states for charge transfer, and is an important realization for general understanding. (author)

The CENP-T C-Terminus Is Exclusively Proximal to H3.1 and not to H3.2 or H3.3

Science.gov (United States)

Abendroth, Christian; Hofmeister, Antje; Hake, Sandra B.; Kamweru, Paul K.; Miess, Elke; Dornblut, Carsten; Küffner, Isabell; Deng, Wen; Leonhardt, Heinrich; Orthaus, Sandra; Hoischen, Christian; Diekmann, Stephan

2015-01-01

The kinetochore proteins assemble onto centromeric chromatin and regulate DNA segregation during cell division. The inner kinetochore proteins bind centromeres while most outer kinetochore proteins assemble at centromeres during mitosis, connecting the complex to microtubules. The centromere–kinetochore complex contains specific nucleosomes and nucleosomal particles. CENP-A replaces canonical H3 in centromeric nucleosomes, defining centromeric chromatin. Next to CENP-A, the CCAN multi-protein complex settles which contains CENP-T/W/S/X. These four proteins are described to form a nucleosomal particle at centromeres. We had found the CENP-T C-terminus and the CENP-S termini next to histone H3.1 but not to CENP-A, suggesting that the Constitutive Centromere-Associated Network (CCAN) bridges a CENP-A- and a H3-containing nucleosome. Here, we show by in vivo FRET that this proximity between CENP-T and H3 is specific for H3.1 but neither for the H3.1 mutants H3.1C96A and H3.1C110A nor for H3.2 or H3.3. We also found CENP-M next to H3.1 but not to these H3.1 mutants. Consistently, we detected CENP-M next to CENP-S. These data elucidate the local molecular neighborhood of CCAN proteins next to a H3.1-containing centromeric nucleosome. They also indicate an exclusive position of H3.1 clearly distinct from H3.2, thus documenting a local, and potentially also functional, difference between H3.1 and H3.2. PMID:25775162

The CENP-T C-Terminus Is Exclusively Proximal to H3.1 and not to H3.2 or H3.3

Directory of Open Access Journals (Sweden)

Christian Abendroth

2015-03-01

Full Text Available The kinetochore proteins assemble onto centromeric chromatin and regulate DNA segregation during cell division. The inner kinetochore proteins bind centromeres while most outer kinetochore proteins assemble at centromeres during mitosis, connecting the complex to microtubules. The centromere–kinetochore complex contains specific nucleosomes and nucleosomal particles. CENP-A replaces canonical H3 in centromeric nucleosomes, defining centromeric chromatin. Next to CENP-A, the CCAN multi-protein complex settles which contains CENP-T/W/S/X. These four proteins are described to form a nucleosomal particle at centromeres. We had found the CENP-T C-terminus and the CENP-S termini next to histone H3.1 but not to CENP-A, suggesting that the Constitutive Centromere-Associated Network (CCAN bridges a CENP-A- and a H3-containing nucleosome. Here, we show by in vivo FRET that this proximity between CENP-T and H3 is specific for H3.1 but neither for the H3.1 mutants H3.1C96A and H3.1C110A nor for H3.2 or H3.3. We also found CENP-M next to H3.1 but not to these H3.1 mutants. Consistently, we detected CENP-M next to CENP-S. These data elucidate the local molecular neighborhood of CCAN proteins next to a H3.1-containing centromeric nucleosome. They also indicate an exclusive position of H3.1 clearly distinct from H3.2, thus documenting a local, and potentially also functional, difference between H3.1 and H3.2.

Solid-state microwave annealing of ion-implanted 4H-SiC

International Nuclear Information System (INIS)

Sundaresan, Siddarth G.; Tian, Yong-lai; Ridgway, Mark C.; Mahadik, Nadeemullah A.; Qadri, Syed B.; Rao, Mulpuri V.

2007-01-01

Solid-state microwave annealing was performed at temperatures up to 2120 deg, C for 30 s on ion-implanted 4H-SiC in N 2 ambient. The surface roughness in the samples annealed without a surface cap at 1950 deg, C is 2.65 nm for 10 μm x 10 μm atomic force microscopy scans. The sheet resistances measured on Al + - and P + -implanted 4H-SiC, annealed by microwaves, are lower than the best conventional furnace annealing results reported in literature. X-ray diffraction spectra indicate alleviation of the lattice damage induced by the ion-implantation and also incorporation of most of the implanted species into substitutional lattice sites

Impact of Weak Agostic Interactions in Nickel Electrocatalysts for Hydrogen Oxidation

Energy Technology Data Exchange (ETDEWEB)

Klug, Christina M. [Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States; O’Hagan, Molly [Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States; Bullock, R. Morris [Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States; Appel, Aaron M. [Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States; Wiedner, Eric S. [Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States

2017-06-08

To understand how H2 binding and oxidation is influenced by [Ni(PR2NR'2)2]2+ PR2NR'2 catalysts with H2 binding energies close to thermoneutral, two [Ni(PPh2NR'2)2]2+ (R = Me or C14H29) complexes with phenyl substituents on phosphorous and varying alkyl chain lengths on the pendant amine were studied. In the solid state, [Ni(PPh2NMe2)2]2+ exhibits an anagostic interaction between the Ni(II) center and the α-CH3 of the pendant amine, and DFT and variable-temperature 31P NMR experiments suggest than the anagostic interaction persists in solution. The equilibrium constants for H2 addition to these complexes was measured by 31P NMR spectroscopy, affording free energies of H2 addition (ΔG°H2) of –0.8 kcal mol–1 in benzonitrile and –1.6 to –2.3 kcal mol–1 in THF. The anagostic interaction contributes to the low driving force for H2 binding by stabilizing the four-coordinate Ni(II) species prior to binding of H2. The pseudo-first order rate constants for H2 addition at 1 atm were measured by variable scan rate cyclic voltammetry, and were found to be similar for both complexes, less than 0.2 s–1 in benzonitrile and 3 –6 s–1 in THF. In the presence of exogenous base and H2 , turnover frequencies of electrocatalytic H2 oxidation were measured to be less than 0.2 s–1 in benzonitrile and 4 –9 s–1 in THF. These complexes are slower electrocatalysts for H2 oxidation than previously studied [Ni(PR2NR'2)2]2+ complexes due to a competition between H2 binding and formation of the anagostic interaction. However, the decrease in catalytic rate is accompanied by a beneficial 130 mV decrease in overpotential. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences. Computational resources were provided at the National Energy Research Scientific Computing Center (NERSC) at Lawrence

Theoretical survey on M@C{sub 80} (M = Ca, Sr, and Ba): Behavior of different alkaline earth metal impacting the chemical stability and electronic properties

Energy Technology Data Exchange (ETDEWEB)

Cui, Jin-Bo; Guo, Yi-Jun; Li, Qiao-Zhi; Zhao, Pei; Zhao, Xiang, E-mail: xzhao@mail.xjtu.edu.cn

2016-08-02

Structures of mono-metallofullerenes M@C{sub 80} (M = Ca, Sr, and Ba) that separated in early experiment are determined owning the C{sub 2v}(31920)-C{sub 80} cage. The change rule of properties for M@C{sub 80} (M = Ca, Sr, and Ba) influenced by different inner metal are discussed. As the trapped metal changes from calcium to barium, performance of thermodynamic stabilities for M@C{sub 2v}(31920)-C{sub 80}, M@C{sub 2v}(31922)-C{sub 80}, and M@D{sub 5h}(31923)-C{sub 80} are significantly different. Orbital analysis suggests that the lowest unoccupied molecular orbitals (LUMOs) of Ca@C{sub 2v}(31920)-C{sub 80} and Ca@D{sub 5h}(31923)-C{sub 80} are mostly located on the trapped metal, whereas reduction reactions of Ca@C{sub 2v}(31920)-C{sub 80} and Ca@D{sub 5h}(31923)-C{sub 80} occur on the fullerene cage. Natural electron configuration analyses demonstrates that the decentralized electron back-donation of Ba@C{sub 2v}(31920)-C{sub 80} would take responsible for the instability of itself. Electronic properties such as electron affinities and ionization potentials are significantly affected by encapsulated metal are also found. Computational UV–visible–NIR spectra for M@C{sub 2v}(31920)-C{sub 80} (M = Ca, Sr, Ba) are in perfect accord with the spectra obtained experimentally.

Substrate-Mediated C-C and C-H Coupling after Dehalogenation.

Science.gov (United States)

Kong, Huihui; Yang, Sha; Gao, Hongying; Timmer, Alexander; Hill, Jonathan P; Díaz Arado, Oscar; Mönig, Harry; Huang, Xinyan; Tang, Qin; Ji, Qingmin; Liu, Wei; Fuchs, Harald

2017-03-15

Intermolecular C-C coupling after cleavage of C-X (mostly, X = Br or I) bonds has been extensively studied for facilitating the synthesis of polymeric nanostructures. However, the accidental appearance of C-H coupling at the terminal carbon atoms would limit the successive extension of covalent polymers. To our knowledge, the selective C-H coupling after dehalogenation has not so far been reported, which may illuminate another interesting field of chemical synthesis on surfaces besides in situ fabrication of polymers, i.e., synthesis of novel organic molecules. By combining STM imaging, XPS analysis, and DFT calculations, we have achieved predominant C-C coupling on Au(111) and more interestingly selective C-H coupling on Ag(111), which in turn leads to selective synthesis of polymeric chains or new organic molecules.

Experimental studies of collisions of excited Li(4p) atoms with C2H4, C2H6, C3H8 and theoretical interpretation of the Li-C2H4 system

International Nuclear Information System (INIS)

Semmineh, Natenael; Bililign, Solomon; Hagebaum-Reignier, Denis; Jeung, Gwang-Hi

2009-01-01

Collisions of excited Li(4p) states with C 2 H 4 , C 2 H 6 and C 3 H 8 are studied experimentally using far-wing scattering state spectroscopy techniques. High-level ab initio quantum mechanical studies of the Li-C 2 H 4 system are conducted to explain the results of the experiment for this system. The recent and present works indicate that knowledge of the internal structure of the perturber (C 2 H 4 , C 2 H 6 and C 3 H 8 ) is essential to fully understand the interaction between the metal and the hydrocarbon molecules. The ab initio calculation shows that the Li(4d) (with little probability under the experimental conditions) and the Li(4p) can be formed directly through the laser pumping. It also shows that the Li(4s) and Li(3d) states can be formed through an electronic diabatic coupling involving a radiationless process. However, the Li(3p), Li(3s) and Li(2p) states can only be formed through a secondary diabatic coupling which is a much less probable process than the primary one. The calculation limited to two C 2v sections of the potential energy surfaces (PESs) shows peculiar multi-state crossings that we have never seen in other lithium complexes we studied

Synthesis and in vivo evaluation of [{sup 11}C]p-P.V.P.-M.E.M.A. as a PET radioligand for imaging nicotinic receptors

Energy Technology Data Exchange (ETDEWEB)

Langle, S.; Roger, G.; Lagnel-de Bruin, B.; Hinnen, F.; Bottlaender, M.; Dolle, F. [Service Hospitalier Frederic Joliot 91 - Orsay (France); Fulton, R.; Henderson, D. [RPAH, NSW (Australia); Kassiou, M. [Sydney Univ., NSW (Australia)

2008-02-15

Nicotinic acetylcholine receptors (n.A.Ch.R.) are crucial to many brain physiological functions and they are involved in a wide range of diseases of the brain making them attractive targets for tomographic imaging. Of particular interest, (((R)-2- [6-chloro-5-((E)-2-pyridin-4-yl-vinyl)-pyridin-3-yloxy]-1- methyl-ethyl)-methyl-amine) (p-P.V.P.-M.E.M.A.) displayed an affinity of Ki 0.077 nM for n.A.Ch.R. when using [{sup 3}H]cytisine and whole rat brain membrane [1]. p-P.V.P.-M.E.M.A. and its corresponding nor-methyl derivative where obtained using a multistep synthesis. [{sup 11}C]p-P.V.P.-M.E.M.A. prepared from the nor-methyl derivative as precursor and labeled with carbon-(T1/2 = 20.4 min) using [{sup 11}C]CH{sub 3}I. The reaction was conducted in D.M.F. using tetra-butyl ammonium hydroxide (T.B.A.H.) as base and allowed to react at room temperature for 2 min, followed by heating at 80 degrees C for 5 min. The reaction mixture was diluted with 0.5 m L of a solution of 0.1 M NH{sub 4}Ac (pH 10):A.C.N. (70:30; v:v) and injected onto a HPLC X Terra R.P. C-18 (7.8 x 300 mm, 10 mm) semi preparative reversed-phase column. Using a mobile phase of 0.1 M NH{sub 4}Ac (pH 10):A.C.N. (70:30; v:v) and a flow rate of 6.0 m L/min, the retention time (t.R.) of [{sup 11}C]p-P.V.P.-M.E.M.A. was 8.6 min. [{sup 11}C]p-P.V.P.-M.E.M.A. was isolated in a 1.5% (n = 4) non decay corrected radiochemical yield based on starting [{sup 11}C]CH{sub 3}I in an average synthesis time of 33.6 min (including H.P.L.C. purification and formulation). In the final product solution, radiochemical and chemical purity was greater than 99% with a specific activity of 86.4 GBq/mmol (2334 mCi/mmol). (authors)

Temperature-dependent infrared optical properties of 3C-, 4H- and 6H-SiC

Science.gov (United States)

Tong, Zhen; Liu, Linhua; Li, Liangsheng; Bao, Hua

2018-05-01

The temperature-dependent optical properties of cubic (3C) and hexagonal (4H and 6H) silicon carbide are investigated in the infrared range of 2-16 μm both by experimental measurements and numerical simulations. The temperature in experimental measurement is up to 593 K, while the numerical method can predict the optical properties at elevated temperatures. To investigate the temperature effect, the temperature-dependent damping parameter in the Lorentz model is calculated based on anharmonic lattice dynamics method, in which the harmonic and anharmonic interatomic force constants are determined from first-principles calculations. The infrared phonon modes of silicon carbide are determined from first-principles calculations. Based on first-principles calculations, the Lorentz model is parameterized without any experimental fitting data and the temperature effect is considered. In our investigations, we find that the increasing temperature induces a small reduction of the reflectivity in the range of 10-13 μm. More importantly, it also shows that our first-principles calculations can predict the infrared optical properties at high-temperature effectively which is not easy to be obtained through experimental measurements.

Olbaltumvielu un peptīdu sorbcijas īpašību izpēte AEŠH apstākļos uz dažādām C18 kolonnām

OpenAIRE

Marduseviča, Aļona

2014-01-01

Olbaltumvielu un peptīdu sorbcijas īpašību izpēte AEŠH apstākļos uz dažādām C18 kolonnām. A. Marduseviča, darba vadītāji Dr. Chem. Asoc. Prof. P. Mekšs, O. Rotkāja. Maģistra darbs, 51 lappuses, 3 tabulas, 37 attēli, 42 literatūras avoti. Latviešu valodā. Atslēgas vārdi: OLBALUMVIELAS, PEPTĪDI, AEŠH, C18 KOLONNAS, IZDALĪŠANAS FAKTORS, GRADIENTA SLĪPUMS. Darbā apskatīti olbaltumvielu un peptīdu atdalīšanas mehānismi, gradients, organisko šķīdinātāju, kolonnas un temperatūras ietekme uz ol...

Monte-Carlo Simulation of γ-ray and Fast Neutron Radiolysis of Liquid Water and 0.4 M H2SO4 Solutions at Temperatures up to 325 oC

International Nuclear Information System (INIS)

Sunaryo, G.R.; Jintana, M.; Gerin, J.P.J.

2011-01-01

Monte-Carlo simulations were used to study the radiolysis of liquid water at 25-325 o C when subjected to low linear energy transfer (LET) of 60 Co γ-ray radiation and fast neutrons of 2 and 0.8 MeV. The energy deposited in the early stage of 60 Co γ--ray irradiation was approximated by considering short segments (∼150 μm) of 300 MeV proton tracks, corresponding to an average LET of ∼0.3 keV/μm. In case of 2 MeV fast neutrons, the energy deposited was considered by using short segments (∼5 μm) of energy at 1.264, 0.465, 0.171, 0.063 and 0.24 MeV. 0.8 MeV fast neutrons were approximated by 0.505, 0.186, 0.069 and 0.025 MeV protons. The effect of 0.4 M H 2 SO 4 solution on radiolysis was also studied by this method for both 60 Co γ-rays and 0.8 MeV fast neutrons. The simulated results at the time of 10 -7 s after irradiation were obtained and compared with the available experimental results published by other researchers to be in excellent agreement with them over the entire temperature ranges and radiation sources studied. Except for g(H 2 ) that increase with temperature rises, the general behaviors of higher radical products and lower molecular products at higher temperatures were obtained. The LET effect is also validated by this study, showing that the increase in LET would yield higher molecular and lower radical products. Studies on 0.4 M H 2 SO 4 solutions also show good agreement between the computed and experimental data for γ-ray irradiation: the presence of 0.4 M H + , except for g(H 2 ) that gives lower value at 25 o C and higher value at 325 o C, gives the higher values for radicals and g(H 2 O 2 ) at 25 o C and lower values at 325 o C, compared with that for neutral water. The computed data show good agreement with the experimental data for 0.4 M H 2 SO 4 solutions induced by 0.8 MeV fast neutrons, except for g(H 2 ) and g(H · ) that gives good agreement up to 50 o C, then the opposite tendencies with the further temperature rises

Parylene C-Based Flexible Electronics for pH Monitoring Applications

Directory of Open Access Journals (Sweden)

Tatiana Trantidou

2014-07-01

Full Text Available Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H+ sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26–0.38 mV/min. The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues.

Parylene C-based flexible electronics for pH monitoring applications.

Science.gov (United States)

Trantidou, Tatiana; Tariq, Mehvesh; Terracciano, Cesare M; Toumazou, Christofer; Prodromakis, Themistoklis

2014-07-01

Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H(+) sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm) of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s) system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26-0.38 mV/min). The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues.

Electrically modulated lateral photovoltage in μc-SiOx:H/a-Si:H/c-Si p-i-n structure at low temperatures

Energy Technology Data Exchange (ETDEWEB)

Liu, Jihong; Qiao, Shuang, E-mail: sqiao@hbu.edu.cn; Wang, Jianglong; Wang, Shufang, E-mail: sfwang@hbu.edu.cn; Fu, Guangsheng

2017-04-15

Graphical abstract: In this paper, the temperature dependence of the LPE has been experimentally studied under illumination of different lasers ranging from visible to infrared for the μc-SiOx:H/a-Si:H/c-Si p-i-n structure. It was found that the position sensitivity increases nearly linearly with wavelength from 405 nm to 980 nm in the whole temperature range, and the saturated position sensitivity decreased quickly from 32.4 mV/mm to a very low value of 1.26 mV/mm and the nonlinearity improved from 7.01% to 3.54% with temperature decreasing from 296 K to 80 K for 532 nm laser illumination. By comparing the experiment results of μc-SiOx:H/a-Si:H/c-Si and ITO/c-Si, it is suggest that the position sensitivity was mainly determined by the temperature-dependent SB and the nonlinearity was directly related to the decreased resistivity of conductive layer. When an external bias voltage was applied, the LPE improved greatly and the position sensitivity of 361.35 mV/mm under illumination of 80 mW at 80 K is 286.7 times as large as that without biased voltage. More importantly, both the position sensitivity and the nonlinearity were independent of temperature again, which can be ascribed to the large constant transmission probability and diffusion length induced by the greatly increased SB. Our research provides an essential insight on the bias voltage-modulated LPE at different temperatures, and this temperature-independent greatly improved LPE is thought to be very useful for developing novel photoelectric devices. - Highlights: • The LPE is proportional to the laser wavelength in the whole temperature range. • The LPE decreases gradually with decreasing temperature from 296 K to 80 K. • Nonlinearity of the LPV curve improves a little with decreasing temperature. • The LPE improves dramatically and is independent of temperature with the aid of a bias voltage. - Abstract: The lateral photovoltaic effect (LPE) in μc-SiOx:H/a-Si:H/c-Si p-i-n structure is studied

Trivalent metallocene chemistry of some uranium, titanium, and zirconium complexes

International Nuclear Information System (INIS)

Lukens, W.W. Jr.

1995-05-01

Dicyclopentadienyluranium halide dimers have been prepared and their solution behavior examined. These molecules exist as dimers in solution, and the halide ligands undergo rapid site exchange on the NMR timescale above 50 C. Analogous dicyclopentadienyluranium hydroxide dimers have also been prepared; they oxidatively eliminate hydrogen to give the corresponding oxide dimers. Mechanism of this reaction is consistent with αmigration of one of the hydroxide hydrogen atoms to a uranium center followed by elimination of hydrogen. Ground state of [(Me 3 Si) 2 C 5 H 3 ] 3 M M = Nd, U and their base adducts has been examined by variable temperature magnetic susceptibility and EPR spectroscopy. The ground state is found to be 4 I 9/2 with a crystal field state consisting largely of J z = 1/2 lowest, in agreement with previous studies on tris-cyclopentadienylneodymium complexes. The zirconium metallocene Cp 3 Zr has been prepared, characterized crystallographically, and its reactivity studied. Its chemical behavior is controlled by presence of an electron in the non-bonding, d z 2 orbital which prevents formation of base adducts Of Cp 3 Zr, but allows Cp 3 Zr to abstract atoms from other molecules. Electonic and EPR spectra of Cp* 2 TiX complexes, where Cp* is Me 5 C 5 and X is a monodentate, anionic ligand such as halide, have been studied. A π-bonding spectrochemical series is developed, and trends in π-bonding ability are found similar to those in other inorganic complexes. The β-agostic interactions in Cp* 2 TiN(Me)Ph have been examined using variable temperature EPR spectroscopy, and the enthalpy/entropy of the interaction determined. In Cp* 2 TiEt, enthalpy of the β-agostic interaction is -1.9 kcal/mol. The titanocene anion, Cp* 2 TiLi(TMEDA) (TMEDA is N,N,N',N'-tetramethylethylenediamine), has been prepared and its structure determined

LABORATORY GAS-PHASE DETECTION OF THE CYCLOPROPENYL CATION (c-C{sub 3}H{sub 3} {sup +})

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dongfeng; Doney, Kirstin D.; Linnartz, Harold, E-mail: zhao@strw.leidenuniv.nl [Sackler Laboratory for Astrophysics, Leiden Observatory, University of Leiden, PO Box 9513, NL 2300 RA Leiden (Netherlands)

2014-08-20

The cyclopropenyl cation (c-C{sub 3}H{sub 3} {sup +}) is the smallest aromatic hydrocarbon molecule and considered to be a pivotal intermediate in ion-molecule reactions in space. An astronomical identification has been prohibited so far, because of a lack of gas-phase data. Here we report the first high resolution infrared laboratory gas-phase spectrum of the ν {sub 4} (C-H asymmetric stretching) fundamental band of c-C{sub 3}H{sub 3} {sup +}. The c-C{sub 3}H{sub 3} {sup +} cations are generated in supersonically expanding planar plasma by discharging a propyne/helium gas pulse, yielding a rotational temperature of ∼35 K. The absorption spectrum is recorded in the 3.19 μm region using sensitive continuous-wave cavity ring-down spectroscopy. The analysis of about 130 ro-vibrational transitions results in precise spectroscopic parameters. These constants allow for an accurate comparison with high-level theoretical predictions, and provide the relevant information needed to search for this astrochemically relevant carbo-cation in space.

A Multi-Wavelength Study of Parent Volatile Abundances in Comet C/2006 M4 (SWAN)

Science.gov (United States)

DiSanti, Michael A.; Villanueva, Geronimo L.; Milam, Stefanie N.; Zack, Lindsay N.; Bonev, Boncho P.; Mumma, Michael; Ziurys, Lucy M.; Anderson, William M.

2009-01-01

Volatile organic emissions were detected post-perihelion in the long period comet C/2006 M4 (SWAN) in October and November 2006. Our study combines target-of-opportunity, observations using the infrared Cryogenic Echelle Spectrometer (CSHELL) at the NASA-IRTF 3-m telescope, and millimeter wavelength observations using the Arizona Radio Observatory (ARO) 12-m telescope. Five parent volatiles were measured with CSHELL (H2O, CO, CH3OH, CH4, and C2H6), and two additional species (HCN and CS) were measured with the ARID 12-m. These revealed highly depleted CO and somewhat enriched CH3OH compared with abundances observed in the dominant group of long-period (Oort cloud) comets in our sample and similar to those observed recently in Comet 8P/Tuttle. This may indicate highly efficient H-atom addition to CO at very low temperature (approx.10-20 K) on the surfaces of interstellar (pre-cometary) grains. Comet C12006 M4 had nearly "normal" C2H6, and CH4, suggesting a processing history similar to that experienced by the dominant group. When compared with estimated water production at the time of the millimeter observations, HCN was slightly depleted compared with the normal abundance in comets based on 1R observations but was consistent with the majority of values from the millimeter. The ratio CS/HCN in C/2006 M4 was within the range measured in ten comets at millimeter wavelengths. The higher apparent H-atom conversion efficiency compared with most comets may indicate that the icy grains incorporated into C/2006 M4 were exposed to higher H-atom densities, or alternatively to similar densities but for a longer period of time.

Computational Study of Pincer Iridium Catalytic Systems: C-H, N-H, and C-C Bond Activation and C-C Coupling Reactions

Science.gov (United States)

Zhou, Tian

Computational chemistry has achieved vast progress in the last decades in the field, which was considered to be only experimental before. DFT (density functional theory) calculations have been proven to be able to be applied to large systems, while maintaining high accuracy. One of the most important achievements of DFT calculations is in exploring the mechanism of bond activation reactions catalyzed by organometallic complexes. In this dissertation, we discuss DFT studies of several catalytic systems explored in the lab of Professor Alan S. Goldman. Headlines in the work are: (1) (R4PCP)Ir alkane dehydrogenation catalysts are highly selective and different from ( R4POCOP)Ir catalysts, predicting different rate-/selectivity-determining steps; (2) The study of the mechanism for double C-H addition/cyclometalation of phenanthrene or biphenyl by (tBu4PCP)Ir(I) and ( iPr4PCP)Ir illustrates that neutral Ir(III) C-H addition products can undergo a very facile second C-H addition, particularly in the case of sterically less-crowded Ir(I) complexes; (3) (iPr4PCP)Ir pure solid phase catalyst is highly effective in producing high yields of alpha-olefin products, since the activation enthalpy for dehydrogenation is higher than that for isomerization via an allyl pathway; higher temperatures favor the dehydrogenation/isomerization ratio; (4) (PCP)Ir(H)2(N2H4) complex follows a hydrogen transfer mechanism to undergo both dehydrogenation to form N 2 and H2, as well as hydrogen transfer followed by N-N bond cleavage to form NH3, N2, and H2; (5) The key for the catalytic effect of solvent molecule in CO insertion reaction for RMn(CO)5 is hydrogen bond assisted interaction. The basicity of the solvent determines the strength of the hydrogen bond interaction during the catalytic path and determines the catalytic power of the solvent; and (6) Dehydrogenative coupling of unactivated C-H bonds (intermolecular vinyl-vinyl, intramolecular vinyl-benzyl) is catalyzed by precursors of the

Experimental and Theoretical Studies of the Factors Affecting the Cycloplatination of the Chiral Ferrocenylaldimine (SC-[(η5-C5H5Fe{(η5-C5H4–C(H=N–CH(Me(C6H5}

Directory of Open Access Journals (Sweden)

Concepción López

2014-11-01

Full Text Available The study of the reactivity of the enantiopure ferrocenyl Schiff base (SC-[FcCH=N–CH(Me(C6H5] (1 (Fc = (η5-C5H5Fe(η5-C5H4 with cis-[PtCl2(dmso2] under different experimental conditions is reported. Four different types of chiral Pt(II have been isolated and characterized. One of them is the enantiomerically pure trans-(SC-[Pt{κ1-N[FcCH=N–CH(Me(C6H5]}Cl2(dmso] (2a in which the imine acts as a neutral N-donor ligand; while the other three are the cycloplatinated complexes: [Pt{κ2-C,N [(C6H4–N=CHFc]}Cl(dmso] (7a and the two diastereomers {(Sp,SC and (Rp,SC} of [Pt{κ2-C,N[(η5-C5H3–CH=N–{CH(Me(C6H5}]Fe(η5-C5H5}Cl(dmso] (8a and 9a, respectively. Isomers 7a-9a, differ in the nature of the metallated carbon atom [CPh (in 7a or CFc (in 8a and 9a] or the planar chirality of the 1,2-disubstituted ferrocenyl unit (8a and 9a. Reactions of 7a–9a with PPh3 gave [Pt{κ2-C,N[(C6H4–N=CHFc]}Cl(PPh3] (in 7b and the diastereomers (Sp,SC and (Rp,SC of [Pt{κ2-C,N[(η5-C5H3–CH=N–{CH(Me(C6H5}] Fe(η5-C5H5}Cl(PPh3] (8b and 9b, respectively. Comparative studies of the electrochemical properties and cytotoxic activities on MCF7 and MDA-MB231 breast cancer cell lines of 2a and cycloplatinated complexes 7b-9b are also reported. Theoretical studies based on DFT calculations have also been carried out in order to rationalize the results obtained from the cycloplatination of 1, the stability of the Pt(II complexes and their electrochemical properties.

C M Dudhe

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science. C M Dudhe. Articles written in Bulletin of Materials Science. Volume 38 Issue 5 September 2015 pp 1423-1427. Nucleation and evaporation of domains due to electric field at room temperature in BaTiO3 single crystals · C M Dudhe P R Arjunwadkar · More Details Abstract ...

The influence of polytypic structures on the M011-->M101 solid-solid phase transition of n-C36H74: An application of the oblique infrared transmission method

Science.gov (United States)

Kubota, Hideki; Kaneko, Fumitoshi; Kawaguchi, Tatsuya; Kawasaki, Masatsugu

2004-07-01

The molecular displacements on the M011→M101 phase transition of n-hexatriacontane (n-C36H74) have been investigated with an IR microscope designed for the oblique infrared transmission method. It has been clarified that two polytypic structures of the M011 modification, single-layered structure (Mon) and double-layered one (Orth II), both transform to the M101 modification of single-layered structure with their respective mechanisms. On the M011(Mon)→M101 transition, the inclination direction of molecular axis is changed by 90° through an intermediate state in which the molecular chain is set perpendicular to the basal plane of the single crystal. On the other hand, a polymorphic-polytypic composite structural change on the M011(Orth II)→M101 transition is accomplished through two kinds of molecular displacements occurring alternately along the stacking direction of molecular layers.

Theoretical descriptions of novel triplet germylenes M1-Ge-M2-M3 (M1 = H, Li, Na, K; M2 = Be, Mg, Ca; M3 = H, F, Cl, Br).

Science.gov (United States)

Kassaee, Mohamad Zaman; Ashenagar, Samaneh

2018-02-06

In a quest to identify new ground-state triplet germylenes, the stabilities (singlet-triplet energy differences, ΔE S-T ) of 96 singlet (s) and triplet (t) M 1 -Ge-M 2 -M 3 species were compared and contrasted at the B3LYP/6-311++G**, QCISD(T)/6-311++G**, and CCSD(T)/6-311++G** levels of theory (M 1  = H, Li, Na, K; M 2  = Be, Mg, Ca; M 3  = H, F, Cl, Br). Interestingly, F-substituent triplet germylenes (M 3  = F) appear to be more stable and linear than the corresponding Cl- or Br-substituent triplet germylenes (M 3  = Cl or Br). Triplets with M 1  = K (i.e., the K-Ge-M 2 -M 3 series) seem to be more stable than the corresponding triplets with M 1  = H, Li, or Na. This can be attributed to the higher electropositivity of potassium. Triplet species with M 3  = Cl behave similarly to those with M 3  = Br. Conversely, triplets with M 3  = H show similar stabilities and linearities to those with M 3  = F. Singlet species of formulae K-Ge-Ca-Cl and K-Ge-Ca-Br form unexpected cyclic structures. Finally, the triplet germylenes M 1 -Ge-M 2 -M 3 become more stable as the electropositivities of the α-substituents (M 1 and M 2 ) and the electronegativity of the β-substituent (M 3 ) increase.

Palladium Catalyzed Allylic C-H Alkylation

DEFF Research Database (Denmark)

Engelin, Casper Junker; Fristrup, Peter

2011-01-01

are highlighted with emphasis on those leading to C-C bond formation, but where it was deemed necessary for the general understanding of the process closely related C-H oxidations and aminations are also included. It is found that C-H cleavage is most likely achieved by ligand participation which could involve......-H alkylation reaction which is the topic of the current review. Particular emphasis is put on current mechanistic proposals for the three reaction types comprising the overall transformation: C-H activation, nucleophillic addition, and re-oxidation of the active catalyst. Recent advances in C-H bond activation...... an acetate ion coordinated to Pd. Several of the reported systems rely on benzoquinone for re-oxidation of the active catalyst. The scope for nucleophilic addition in allylic C-H alkylation is currently limited, due to demands on pKa of the nucleophile. This limitation could be due to the pH dependence...

1400 V 4H-SiC power MOSFETs

Energy Technology Data Exchange (ETDEWEB)

Agarwal, A.K.; Casady, J.B.; Rowland, L.B.; Valek, W.F.; Brandt, C.D. [Northrop Grumman Sci. and Technol. Center, Pittsburgh, PA (United States)

1998-08-01

Silicon carbide (4H-SiC), power U-metal-oxide-semiconductor field-effect transistors (UMOSFETs) were fabricated and characterized from room temperature to 200 C. The devices had a 12 {mu}m thick lightly doped n-type drift layer, and a nominal channel length of 4 {mu}m. When tested under Fluorinert{sup TM} at room temperature, blocking voltages ranged from 1.3 kV to 1.4 kV. Effective channel mobility ranged from 1.5 cm{sup 2}/V.s at room temperature with a gate bias of 32 V (oxide field {proportional_to} 3.5 MV/cm) up to 7 cm{sup 2}/V.s at 100 C with an applied gate bias of 26 V (oxide field {proportional_to} 2.9 MV/cm). Specific on-resistance (R{sub on,sp}) was calculated to be as low as 74 m{Omega}.cm{sup 2} at 100 C under the same gate bias. Fowler-Nordheim measurements with positive gate bias on actual UMOS devices indicated thermionic field injection at elevated temperatures. (orig.) 8 refs.

Synthesis and Properties of New Polymer Having Hindered Phenol Antioxidants

International Nuclear Information System (INIS)

Kim, Taek Hyeon; Song, Yi Rang; Kim, Jae Nyoung

2003-01-01

Polymeric antioxidants was successfully prepared by the copolymerization of monomeric maleimide with MMA. The copolymers possess some stabilizing effect against thermal oxidation with oven aging in air at 120 .deg. C for 5 days and also have the some resistance to water extraction. It is well known that the addition of antioxidants is the most convenient and effective way to block the thermal oxidation of polyolefins. Hindered phenol antioxidants, which contain the 2,6-di-tert-butylphenol functional group, are very effective primary antioxidants. However, low molecular weight (MW) antioxidants are easily lost from the polymers by the physical loss such as migration, evaporation, and extraction by liquid. The effectiveness of low MW antioxidants is limited. Therefore a new trend for antioxidant development is to prepare antioxidant with higher MW. The copolymerization or homopolymerization of the functional monomer bearing hindered phenol antioxidants is a conventional method for preparing polymeric antioxidants

Tetrahedral silsesquioxane-C2H2Ti complex for hydrogen storage

Science.gov (United States)

Konda, Ravinder; Tavhare, Priyanka; Ingale, Nilesh; Chaudhari, Ajay

2018-04-01

The interaction of molecular hydrogen with tetrahedral silsesquioxane (T4)-C2H2Ti complex has been studied using Density Functional Theory with M06-2X functional and MP2 method with 6-311++G** basis set. T4-C2H2Ti complex can absorb maximum five hydrogen molecules with the gravimetric hydrogen storage capacity of 3.4 wt %. Adsorption energy calculations show that H2 adsorption on T4-C2H2Ti complex is favorable at room temperature by both the methods. We have studied the effect of temperature and pressure on Gibbs free energy corrected adsorption energies. Molecular dynamics simulations for H2 adsorbed T4-C2H2Ti complex have also been performed at 300K and show that loosely bonded H2 molecule flies away within 1fs. Various interaction energies within the complex are studied. Stability of a complex is predicted by means of a gap between Highest Occupied Molecular Orbital (HUMO) and Lowest Unoccupied Molecular Orbital (LUMO). The H2 desorption temperature for T4-C2H2Ti complex is calculated with Van't Hoff equation and it is found to be 229K.

Experimental investigation of slow-positron emission from 4H-SiC and 6H-SiC surfaces

International Nuclear Information System (INIS)

Ling, C.C.; Beling, C.D.; Fung, S.; Weng, H.M.

2002-01-01

Slow-positron emission from the surfaces of as-grown n-type 4H-SiC and 6H-SiC (silicon carbide) with a conversion efficiency of ∼10 -4 has been observed. After 30 min of 1000 deg. C annealing in forming gas, the conversion efficiency of the n-type 6H-SiC sample was observed to be enhanced by 75% to 1.9x10 -4 , but it then dropped to ∼10 -5 upon a further 30 min annealing at 1400 deg. C. The positron work function of the n-type 6H-SiC was found to increase by 29% upon 1000 deg. C annealing. For both p-type 4H-SiC and p-type 6H-SiC materials, the conversion efficiency was of the order of ∼10 -5 , some ten times lower than that for the n-type materials. This was attributed to the band bending at the p-type material surface which caused positrons to drift away from the positron emitting surface. (author)

Electrochemical Cobalt-Catalyzed C-H Activation.

Science.gov (United States)

Sauermann, Nicolas; Meyer, Tjark H; Ackermann, Lutz

2018-06-19

Carbon-heteroatom bonds represent omnipresent structural motifs of the vast majority of functionalized materials and bioactive compounds. C-H activation has emerged as arguably the most efficient strategy to construct C-Het bonds. Despite of major advances, these C-H transformations were largely dominated by precious transition metal catalysts, in combination with stoichiometric, toxic metal oxidants. Herein, we discuss the recent evolution of cobalt-catalyzed C-H activations that enable C-Het formations with electricity as the sole sustainable oxidant until May 2018. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photodissociation of C3H5Br and C4H7Br at 234 nm

International Nuclear Information System (INIS)

Kim, Hyun Kook; Paul, Dababrata; Hong, Ki Ryong; Cho, Ha Na; Kim, Tae Kyu; Lee, Kyoung Seok

2012-01-01

The photodissociation dynamics of cyclopropyl bromide (C-3H 5 Br) and cyclobutyl bromide (C 4 H 7 Br) at 234 nm was investigated. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br( 2 P 3/2 ) and Br*( 2 P 1/2 ) atoms. The recoil anisotropies for the Br and Br* channels were measured to be βBr = 0.92 ± 0.03 and βBr* = 1.52 ± 0.04 for C 3 H 5 Br and βBr = 1.10 ± 0.03 and βBr* = 1.49 ± 0.05 for C 4 H 7 Br. The relative quantum yield for Br was found to be ΦBr = 0.13 ± 0.03 and for C 3 H 5 Br and C 4 H 7 Br, respectively. The soft radical limit of the impulsive model adequately modeled the related energy partitioning. The nonadiabatic transition probability from the 3A' and 4A' potential energy surfaces was estimated and discussed

Comparison of the reactivity of 2-Li-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2} with MCl{sub 4} (M=Th, U). Isolation of a thorium aryl complex or a uranium benzyne complex

Energy Technology Data Exchange (ETDEWEB)

Seaman, Lani A.; Pedrick, Elizabeth A.; Wu, Guang; Hayton, Trevor W. [California Univ., Santa Barbara, CA (United States). Dept. of Chemistry and Biochemistry; Tsuchiya, Takashi; Jakubikova, Elena [North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemistry

2013-09-27

Individualism under actinoids: The reaction of 2-Li-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2} with [MCl{sub 4} (dme) {sub n}] (M=Th, n=2; M=U, n=0) gives the thorium aryl complex [Th(2-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2}){sub 4}] or the uranium benzene complex Li[U(2,3-C{sub 6}H{sub 3}CH{sub 2}NMe{sub 2})(2-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2}){sub 3}]. A DFT analysis suggests that the formation of a benzyne complex with uranium but not with thorium is a kinetic and not thermodynamic effect. [German] Individualismus unter Actinoiden: Die Reaktion von 2-Li-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2} mit [MCl{sub 4} (dme) {sub n}] (M=Th, n=2; M=U, n=0) ergibt den Thoriumarylkomplex [Th(2-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2}){sub 4}] bzw. den Uranbenz-inkomplex Li[U(2,3-C{sub 6}H{sub 3}CH{sub 2}NMe{sub 2})(2-C{sub 6}H{sub 4}CH{sub 2}NMe{sub 2}){sub 3}]. Einer dichtefunktionaltheoretischen Analyse zufolge ist es kinetisch und nicht thermodynamisch bedingt, dass der Benz-inkomplex im Fall von Uran entsteht, nicht aber im Fall von Thorium.

Effect of M{sub 3}C on the precipitation behavior of M{sub 23}C{sub 6} phase during early stage of tempering in T91 ferritic steel

Energy Technology Data Exchange (ETDEWEB)

Liu, Chenxi; Liu, Yongchang; Zhang, Dantian; Ning, Baoqun; Yan, Zesheng [School of Material Science and Engineering, Tianjin Key Laboratory of Advanced Jointing Technology, Tianjin University, Tianjin (China)

2011-12-15

Tempered martensitic structure is the service condition of T91 ferritic steel after adopting the austenitizing followed by tempering. Needle-like M{sub 3}C particles are precipitated during air cooling after austenization, while the precipitation of M{sub 3}C is suppressed during the water cooling. The effect of existence of M{sub 3}C on the precipitation behaviors of M{sub 23}C{sub 6} during the early stage of tempering, as nucleation site, number density and size distribution, was investigated by means of TEM observation. The TEM results indicate that, upon the same tempering time, the size of M{sub 23}C{sub 6} is smaller and its number density is higher in the sample pre-existing M{sub 3}C than in the sample without M{sub 3}C. This can be explained that existence of M{sub 3}C results in more M{sub 23}C{sub 6} precipitates forming inside of grain, where a relatively low self-diffusion coefficient of alloy element leads to M{sub 23}C{sub 6} hardly coarsening. However, with the prolongation of tempering time, this effect becomes weaken. Microhardness results indicate that the existence of M{sub 3}C phase results in the increase of hardness after tempering due to the precipitation of finer and denser M{sub 23}C{sub 6} particles. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Molecular structures and excited states of CpM(CO)(2) (Cp = eta(5)-C(5)H(5); M = Rh, Ir) and [Cl(2)Rh(CO)(2)](-). Theoretical evidence for a competitive charge transfer mechanism.

Science.gov (United States)

Hu, Zhenming; Boyd, Russell J; Nakatsuji, Hiroshi

2002-03-20

Molecular structures and excited states of CpM(CO)(2) (Cp = eta(5)-C(5)H(5); M = Rh, Ir) and [Cl(2)Rh(CO)(2)](-) complexes have been investigated using the B3LYP and the symmetry-adapted cluster (SAC)/SAC-configuration interaction (SAC-CI) theoretical methods. All the dicarbonyl complexes have singlet ground electronic states with large singlet-triplet separations. Thermal dissociations of CO from the parent dicarbonyls are energetically unfavorable. CO thermal dissociation is an activation process for [Cl(2)Rh(CO)(2)](-) while it is a repulsive potential for CpM(CO)(2). The natures of the main excited states of CpM(CO)(2) and [Cl(2)Rh(CO)(2)](-) are found to be quite different. For [Cl(2)Rh(CO)(2)](-), all the strong transitions are identified to be metal to ligand CO charge transfer (MLCT) excitations. A significant feature of the excited states of CpM(CO)(2) is that both MLCT excitation and a ligand Cp to metal and CO charge transfer excitation are strongly mixed in the higher energy states with the latter having the largest oscillator strength. A competitive charge transfer excited state has therefore been identified theoretically for CpRh(CO)(2) and CpIr(CO)(2). The wavelength dependence of the quantum efficiencies for the photoreactions of CpM(CO)(2) reported by Lees et al. can be explained by the existence of two different types of excited states. The origin of the low quantum efficiencies for the C-H/S-H bond activations of CpM(CO)(2) can be attributed to the smaller proportion of the MLCT excitation in the higher energy states.

~ i t i d e r m a t o ~ h ~ t i c Activities of Nine (9) Essential Oils J.R. ...

African Journals Online (AJOL)

i t i d e r m a t o ~ h ~ t i c Activities of Nine (9) Essential Oils. J.R. KUIATE", S.P. KUATE'.~, N.E. KEMADJOU~, S. DJOKOUA~, F. ZIFACK~ AND J. ~. 0. ~. 0. ~. I Department of Biochemistry, FS, University of Dschang, P.O. Box 67 Dschang, Cameroon. 2~epartment of Biochemistry, FS, University of Yaoundt!, P.O. Box 812 ...

Experimental and theoretical studies of the C{sub 6}H{sub 5} + C{sub 6}H{sub 6} reaction

Energy Technology Data Exchange (ETDEWEB)

Park, J.; Burova, S.; Rodgers, A.S.; Lin, M.C.

1999-11-11

The absolute rate constants for the C{sub 6}H{sub 5} + C{sub 6}H{sub 6} and C{sub 6}D{sub 6} reactions have been measured by cavity ringdown spectrometry at temperatures between 298 and 495 K at a constant 40 Torr Ar pressure. The new results, which reveal no detectable kinetic isotopic effect, can be represented by the Arrhenius equation, {kappa}{sub 1} = 10{sup (11.91{+-}0.13)} exp[{minus}(2,102 {+-} 106)/T] cm{sup 3}/(mol s). Low-temperature data for the addition/stabilization process, C{sub 6}H{sub 5} + C{sub 6}H{sub 6} {r{underscore}arrow} C{sub 12}H{sub 11}, can be correlated with those obtained in a low-pressure, high-temperature Knudsen cell study for the addition/displacement reaction, C{sub 6}H{sub 5} + C{sub 6}H{sub 6} {r{underscore}arrow} C{sub 12}H{sub 10} + H, by the RRKM theory using the molecular and transition-state parameters computed at the B3LYP/6-311G(d,p) level of theory. Combination of these two sets of data gives {kappa}{sub 1} = 10{sup (11.98{+-}0.03)} exp[{minus}(2168 {+-} 34)/T] cm{sup 3}/(mol s) covering the temperature range 298--1,330 K. The RRKM theory also correlates satisfactorily the forward reaction data with the high-temperature shock-tube result for the reverse H-for-C{sub 6}H{sub 5} substitution process with 2.7 and 4.7 kcal/mol barriers for the entrance (C{sub 6}H{sub 5} + C{sub 6}H{sub 6}) and reverse (H + C{sub 12}H{sub 10}) reactions, respectively. For modeling applications, the authors have calculated the forward reaction rate constants for the formation of the two competing products, H + C{sub 12}H{sub 10} and C{sub 12}H{sub 11}, at several pressures covering 300 K {lt} T {lt} 2,500 K.

THE PHYSICAL MECHANISM BEHIND M DWARF METALLICITY INDICATORS AND THE ROLE OF C AND O ABUNDANCES

Energy Technology Data Exchange (ETDEWEB)

Veyette, Mark J.; Muirhead, Philip S. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Mann, Andrew W. [Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States); Allard, France [Centre de Recherche Astrophysique de Lyon, UMR 5574, Université de Lyon, ENS de Lyon, Université Lyon 1, CNRS, F-69007, Lyon (France)

2016-09-10

We present near-infrared (NIR) synthetic spectra based on PHOENIX stellar atmosphere models of typical early and mid-M dwarfs with varied C and O abundances. We apply multiple recently published methods for determining M dwarf metallicity to our models to determine the effects of C and O abundances on metallicity indicators. We find that the pseudo-continuum level is very sensitive to C/O and that all metallicity indicators show a dependence on C and O abundances, especially in lower T {sub eff} models. In some cases, the inferred metallicity ranges over a full order of magnitude (>1 dex) when [C/Fe] and [O/Fe] are varied independently by ±0.2. We also find that [(O−C)/Fe], the difference in O and C abundances, is a better tracer of the pseudo-continuum level than C/O. Models of mid-M dwarfs with [C/Fe], [O/Fe], and [M/H] that are realistic in the context of galactic chemical evolution suggest that variation in [(O−C)/Fe] is the primary physical mechanism behind the M dwarf metallicity tracers investigated here. Empirically calibrated metallicity indicators are still valid for most nearby M dwarfs due to the tight correlation between [(O−C)/Fe] and [Fe/H] evident in spectroscopic surveys of solar neighborhood FGK stars. Variations in C and O abundances also affect the spectral energy distribution of M dwarfs. Allowing [O/Fe] to be a free parameter provides better agreement between the synthetic spectra and observed spectra of metal-rich M dwarfs. We suggest that flux-calibrated, low-resolution, NIR spectra can provide a path toward measuring C and O abundances in M dwarfs and breaking the degeneracy between C/O and [Fe/H] present in M dwarf metallicity indicators.

Volume properties and refraction of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids lysine, threonine, and oxyproline (C60(C6H13N2O2)2, C60(C4H8NO3)2, and C60(C5H9NO2)2) at 25°C

Science.gov (United States)

Semenov, K. N.; Ivanova, N. M.; Charykov, N. A.; Keskinov, V. A.; Kalacheva, S. S.; Duryagina, N. N.; Garamova, P. V.; Kulenova, N. A.; Nabieva, A.

2017-02-01

Concentration dependences of the density of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids are studied by pycnometry. Concentration dependences of the average molar volumes and partial volumes of components (H2O and corresponding bisadducts) are calculated for C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems at 25°C. Concentration dependences of the indices of refraction of C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems are determined at 25°C. The concentration dependences of specific refraction and molar refraction of bisadducts and aqueous solutions of them are calculated.

The radiosensitivity of human keratinocytes: influence of activated c-H-ras oncogene expression and tumorigenicity

International Nuclear Information System (INIS)

Mendonca, M.S.; Redpath, J.L.; Stanbridge, E.J.

1991-01-01

The authors investigated γ-ray sensitivity of several activated c-H-ras (EJ) containing clones established after transfection of the spontaneously immortalized non-tumorigenic human keratinocyte cell line HaCaT. The clones were grouped according to tumorigenic potential after subcutaneous injection into nude mice, and fell into three classes: Class I clones A-4 and I-6 are non-tumorigenic and express very low levels of c-H-ras mRNA and no mutated ras protein (p 21 ); Class II clones I-5 and I-7 grow to large (benign) epidermal cysts, express intermediate to high c-H-ras mRNA and variable levels of mutated ras p 21 protein with clone I-5 expressing little and clone I-7 expressing high levels of p 21 ; Class III clones II-3 and II-4 grow to solid squamous cell carcinomas, express high c-H-ras mRNA and high level of mutated p 21 ras protein similar to clone I-7. Comparison of single-hit multitarget or linear-quadratic survival curve parameters, and survival at 2Gy (S 2 ) indicate no general correlation with either activated c-H-ras expression level or tumorigenic potential, and increased radioresistance. (author)

Araloside C Prevents Hypoxia/Reoxygenation-Induced Endoplasmic Reticulum Stress via Increasing Heat Shock Protein 90 in H9c2 Cardiomyocytes

Directory of Open Access Journals (Sweden)

Yuyang Du

2018-04-01

Full Text Available Araloside C (AsC is a cardioprotective triterpenoid compound that is mainly isolated from Aralia elata. This study aims to determine the effects of AsC on hypoxia-reoxygenation (H/R-induced apoptosis in H9c2 cardiomyocytes and its underlying mechanisms. Results demonstrated that pretreatment with AsC (12.5 μM for 12 h significantly suppressed the H/R injury in H9c2 cardiomyocytes, including improving cell viability, attenuating the LDH leakage and preventing cardiomyocyte apoptosis. AsC also inhibited H/R-induced ER stress by reducing the activation of ER stress pathways (PERK/eIF2α and ATF6, and decreasing the expression of ER stress-related apoptotic proteins (CHOP and caspase-12. Moreover, AsC greatly improved the expression level of HSP90 compared with that in the H/R group. The use of HSP90 inhibitor 17-AAG and HSP90 siRNA blocked the above suppression effect of AsC on ER stress-related apoptosis caused by H/R. Taken together, AsC could reduce H/R-induced apoptosis possibly because it attenuates ER stress-dependent apoptotic pathways by increasing HSP90 expression.

Chloride-based fast homoepitaxial growth of 4H-SiC films in a vertical hot-wall CVD

Science.gov (United States)

Guoguo, Yan; Feng, Zhang; Yingxi, Niu; Fei, Yang; Xingfang, Liu; Lei, Wang; Wanshun, Zhao; Guosheng, Sun; Yiping, Zeng

2016-06-01

Chloride-based fast homoepitaxial growth of 4H-SiC epilayers was performed on 4° off-axis 4H-SiC substrates in a home-made vertical hot-wall chemical vapor deposition (CVD) system using H2-SiH4-C2H4-HCl. The effect of the SiH4/H2 ratio and reactor pressure on the growth rate of 4H-SiC epilayers has been studied successively. The growth rate increase in proportion to the SiH4/H2 ratio and the influence mechanism of chlorine has been investigated. With the reactor pressure increasing from 40 to 100 Torr, the growth rate increased to 52 μm/hand then decreased to 47 μm/h, which is due to the joint effect of H2 and HCl etching as well as the formation of Si clusters at higher reactor pressure. The surface root mean square (RMS) roughness keeps around 1 nm with the growth rate increasing to 49 μm/h. The scanning electron microscope (SEM), Raman spectroscopy and X-ray diffraction (XRD) demonstrate that 96.7 μm thick 4H-SiC layers of good uniformity in thickness and doping with high crystal quality can be achieved. These results prove that chloride-based fast epitaxy is an advanced growth technique for 4H-SiC homoepitaxy. Project supported by the National High Technology R&D Program of China (No. 2014AA041402), the National Natural Science Foundation of China (Nos. 61474113, 61274007, 61574140), the Beijing Natural Science Foundation of China (Nos. 4132076, 4132074), the Program of State Grid Smart Grid Research Institute (No. SGRI-WD-71-14-004), and the Youth Innovation Promotion Association of CAS.

Ionic fragmentation of a natural product, limonene (C10H16), following core [C 1s] photoionization

International Nuclear Information System (INIS)

Castilho, R.B. de; Nunez, C.V.; Coutinho, L.H.; Lago, A.F.; Bernini, R.B.; Souza, G.G.B. de

2007-01-01

Photoionization of the limonene [C 10 H 16 ] molecule was studied for the first time following C 1s ionization, using synchrotron radiation and time-of-fight mass spectrometry. As a reference for further analysis of the photon induced fragmentation of the limonene molecule, the He(I) mass spectrum was also obtained. Previously unreported singly charged species have been observed at 310 eV: H + , C + , CH + , CH 2 + , CH 3 + . A close similarity has been observed between the high photon energy mass spectrum and the standard electron impact mass spectrum of limonene, obtained at 70 eV. In particular, the base peak [C 5 H 8 + , m/q = 68], known to result from a Retro Diels-Alder reaction, remains the same in both cases. Approximate values for the mean kinetic energy were determined for all ionic species

Systems Li2B4O7 (Na2B4O7, K2B4O7)-N2H3H4OH-H2O at 25 deg C

International Nuclear Information System (INIS)

Skvortsov, V.G.; Sadetdinov, Sh.V.; Akimov, V.M.; Mitrasov, Yu.N.; Petrova, O.V.; Klopov, Yu.N.

1994-01-01

Phase equilibriums in the Li 2 B 4 O 7 (Na 2 B 4 O 7 , K 2 B 4 O 7 )-N 2 H 3 H 4 OH-H 2 O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM 2 B 4 O 7 ·nN 2 H 3 C 2 H 4 OH·XH 2 O, where M=Li, Na with hydrazine ethanol. K 2 B 4 O 7 ·4H 2 O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods

Growth and optical, magnetic and transport properties of (C4H9NH3)2MCl4 organic-inorganic hybrid films (M = Cu, Sn)

Science.gov (United States)

Aruta, C.; Licci, F.; Zappettini, A.; Bolzoni, F.; Rastelli, F.; Ferro, P.; Besagni, T.

2005-10-01

Films of (C4H9NH3)2MCl4 (M=Cu and Sn) organic-inorganic hybrid perovskites have been deposited in-situ by a single-source thermal ablation technique on glassy, crystalline and polymeric substrates. Independently of the substrate, the films were well crystallized, c-axis oriented and with a narrow rocking curve of the (0010) reflection (full width at half maximum photoluminescence spectra of typical (C4H9NH3)2SnCl4 films at 12 K had a broad yellow band, which did not correspond to any significant peak in the absorption spectrum. The films were semiconducting down to 250 K or, in the case of the best samples, down to 200 K and became insulating at lower temperature. The resistivity of the best films was (5±1) 104 Ω cm at 300 K, and the energy gap was 1.11 eV.

Triple resonance experiments for the simultaneous correlation of H6/H5 and exchangeable protons of pyrimidine nucleotides in 13C,15N-labeled RNA applicable to larger RNA molecules

International Nuclear Information System (INIS)

Woehnert, Jens; Goerlach, Matthias; Schwalbe, Harald

2003-01-01

Triple-resonance two-dimensional H6/H5(C4N)H and C6/C5(C4N)H experiments are described that provide through-bond H6/H5 or C6/C5 to imino/amino correlations in pyrimidine bases in 13 C, 15 N-labeled RNA. The experiments simultaneously transfer H6/H5 magnetization by an INEPT step to the C6/C5 nuclei and by homonuclear CC- and heteronuclear CN-TOCSY steps via the intervening C4 nucleus to the N3/N4 nuclei and then by a reverse INEPT step to the imino/amino hydrogens. The sensitivity of these experiments is high as demonstrated using a 30-nucleotide pyrimidine rich RNA at a concentration of 0.9 mM at temperatures of 10 deg. C and 25 deg. C. This indicates the general applicability of the experiments and the possibility to obtain correlations for imino resonances in non-canonical regions of the target RNA

Electronic transitions of C{sub 5}H{sup +} and C{sub 5}H: neon matrix and CASPT2 studies

Energy Technology Data Exchange (ETDEWEB)

Fulara, Jan, E-mail: fulara@ifpan.edu.pl [Department of Chemistry, University of Basel, Klingelbergstarasse 80, CH-4056 Basel (Switzerland); Institute of Physics, Polish Academy of Sciences, Al. Lotników, 32/46, PL-02-668 Warsaw (Poland); Nagy, Adam; Chakraborty, Arghya; Maier, John P., E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstarasse 80, CH-4056 Basel (Switzerland)

2016-06-28

Two electronic transitions at 512.3 and 250 nm of linear-C{sub 5}H{sup +} are detected following mass-selective deposition of m/z = 61 cations into a 6 K neon matrix and assigned to the 1 {sup 1}Π←X {sup 1}Σ{sup +} and 1 {sup 1}Σ{sup +}←X {sup 1}Σ{sup +} systems. Five absorption systems of l-C{sub 5}H with origin bands at 528,7, 482.6, 429.0, 368.5, and 326.8 nm are observed after neutralization of the cations in the matrix and identified as transitions from the X {sup 2}Π to 1 {sup 2}Δ, 1 {sup 2}Σ {sup −}, 1 {sup 2}Σ{sup +}, 2 {sup 2}Π, and 3 {sup 2}Π electronic states. The assignment to specific structures is based on calculated excitation energies, vibrational frequencies in the electronic states, along with simulated Franck–Condon profiles.

Melting Can Hinder Impact-Induced Adhesion

Science.gov (United States)

Hassani-Gangaraj, Mostafa; Veysset, David; Nelson, Keith A.; Schuh, Christopher A.

2017-10-01

Melting has long been used to join metallic materials, from welding to selective laser melting in additive manufacturing. In the same school of thought, localized melting has been generally perceived as an advantage, if not the main mechanism, for the adhesion of metallic microparticles to substrates during a supersonic impact. Here, we conduct the first in situ supersonic impact observations of individual metallic microparticles aimed at the explicit study of melting effects. Counterintuitively, we find that under at least some conditions melting is disadvantageous and hinders impact-induced adhesion. In the parameter space explored, i.e., ˜10 μ m particle size and ˜1 km /s particle velocity, we argue that the solidification time is much longer than the residence time of the particle on the substrate, so that resolidification cannot be a significant factor in adhesion.

Fusion hindrance in reactions with very heavy ions: Border between normal and hindered fusion

International Nuclear Information System (INIS)

Shen Caiwan; Li Qingfeng; Boilley, David; Shen Junjie; Abe, Yasuhisa

2011-01-01

The fusion hindrance in heavy-ion collisions is studied in the framework of the two-center liquid drop model. It appears that the neck and the radial degrees of freedom might both be hampered by an inner potential barrier on their path between the contact configuration to the compound nucleus. Heavy-ion reactions with and without the two kinds of fusion hindrance are classified through systematic calculations. It is found that the number of reactions without radial fusion hindrance is much smaller than that without neck fusion hindrance, and for both kinds of fusion hindrance the number of reactions without fusion hindrance at small mass-asymmetry parameter α is smaller than that at large α. In the formation of a given compound nucleus, if a reaction with α c is not hindered, then other reactions with α>α c are also not hindered, as is well known experimentally.

Directing-Group-mediated C-H-Alkynylations.

Science.gov (United States)

Caspers, Lucien D; Nachtsheim, Boris J

2018-05-18

C-C triple bonds are amongst the most versatile functional groups in synthetic chemistry. Complementary to the Sonogashira coupling the direct metal-catalyzed alkynylation of C-H bonds has emerged as a highly promising approach in recent years. To guarantee a high regioselectivity suitable directing groups (DGs) are necessary to guide the transition metal (TM) into the right place. In this Focus Review we present the current developments in DG-mediated C(sp 2 )-H and C(sp 3 )-H modifications with terminal alkynes under oxidative conditions and with electrophilic alkynylation reagents. We will discuss further modifications of the alkyne, in particular subsequent cyclizations to carbo- and heterocycles and modifications of the DG in the presence of the alkyne. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uptake of [3H]PAH and [14C]urate into isolated proximal tubular segments of the pig kidney

International Nuclear Information System (INIS)

Schali, C.; Roch-Ramel, F.

1981-01-01

Segments of proximal convoluted (PCT) and proximal straight (PST) tubules of minipigs and normal-sized pigs were microdissected (without collagenase treatment) and incubated (30 min, 37 0 C, pH 7.4) in Ringer solution (under O 2 ) containing [ 3 H]PAH (3.10 -5 M) or [ 14 C]urate (9.10 -5 M) and, in inhibitor studies, probenecid, pyrazinoic acid (PZA), urate, or PAH, all at 1 mM. In both strains the uptake of [ 3 H]PAH expressed as mean T/M ratio (cpm per ml tissue water/cpm per ml incubation medium) was significantly higher (P 14 C]urate. In eight minipigs the T/M was 4.9 +/- 0.5 in 24 PCT and 2 +/- 0.2 in 25 PST. In normal-sized pigs the T/M was 3.8 +/- 0.3 in 35 PCT (five pigs) and 1.9 +/- 0.4 in eight PST (two pigs). In inhibitor studies urate significantly depressed the uptake of [ 3 H]PAH, and unlabeled PAH depressed the uptake of [ 14 C]urate. PZA significantly inhibited the uptake of [ 14 C]urate but not that of [ 3 H]PAH, whereas probenecid had a strong inhibitory efect on the uptake of both compounds. These results suggest that [ 14 C]urate and [ 3 H]PAH are transported by a transport system located mainly in the proximal convoluted tubule. These findings are in contrast in the findings are in contrast to the findings obtained in rabbits in which the transport system of PAH and urate is mainly located in the proximal part of the pars recta

Thermal stability of nanocomposite CrC/a-C:H thin films

International Nuclear Information System (INIS)

Gassner, G.; Mayrhofer, P.H.; Patscheider, J.; Mitterer, C.

2007-01-01

The thermal stability of low-friction Me-C/a-C:H coatings is important for their potential applications in the tool and automotive industry. Recently we showed that CrC x /a-C:H coatings prepared by unbalanced magnetron sputtering of a Cr target in Ar + CH 4 glow discharges exhibit a nanocomposite structure where metastable fcc CrC nanocrystals are encapsulated by an a-C:H phase. Here, we present the structural evolution of these nanocomposite CrC/a-C:H coatings during annealing. High-temperature X-ray diffraction in vacuum and differential scanning calorimetry (DSC) combined with thermo-gravimetric analysis in Ar atmosphere indicate decomposition of the formed metastable fcc CrC phase and subsequent formation of Cr 3 C 2 and Cr 7 C 3 and structural transformation of the a-C:H matrix phase towards higher sp 2 bonding contents at temperatures above 450 deg. C. Combined DSC and mass spectrometer analysis as well as elemental profiling after annealing in vacuum by elastic recoil detection analysis relate this transformation to the loss of bonded hydrogen at temperatures above 200 deg. C. Due to these structural changes the coefficient of friction depends on the annealing temperature of the nanocomposite a-C:H coatings and shows a minimum of ∼ 0.13 for T = 200 deg. C. The more complex tribochemical reactions, influenced by the hydrogen loss from the coating during in-situ high temperatures ball-on disc tests, result in coefficient of friction values below 0.05 for T < 120 deg. C

Nido-Carborane building-block reagents. 2. Bulky-substituent (alkyl)2C2B4H6 derivatives and (C6H5)2C2B4H6: synthesis and properties

International Nuclear Information System (INIS)

Boyter, H.A. Jr.; Grimes, R.N.

1988-01-01

The preparation and chemistry of nido-2,3-R 2 C 2 C 2 B 4 H 6 carboranes in which R is n-butyl, isopentyl, n-hexyl, and phenyl was investigated in order to further assess the steric and electronic influence of the R groups on the properties of the nido-C 2 B 4 cage, especially with respect to metal complexation at the C 2 B 3 face and metal-promoted oxidative fusion. The three dialkyl derivatives were prepared from the corresponding dialkylacetylenes via reaction with B 5 H 9 and triethylamine, but the diphenyl compound could not be prepared in this manner and was obtained instead in a thermal reaction of B 5 H 9 with diphenylacetylene in the absence of amine. All four carboranes are readily bridge-deprotonated by NaH in THF, and the anions of the dialkyl species, on treatment with FeCl 2 and air oxidation, generate the respective R 4 C 4 B 8 H 8 carborane fusion products were R = n-C 4 H 9 , i-C 5 H 11 or n-C 6 H 13 . The diphenylcarborane anion Ph 2 C 2 B 4 H 5 - did not form detectable metal complexes with Fe 2+ , Co 2+ , or Ni 2+ , and no evidence of a Ph 4 C 4 B 8 H 8 fusion product has been found. Treatment of Ph 2 C 2 B 4 H 6 with Cr(CO) 6 did not lead to metal coordination of the phenyl rings, unlike (PhCH 2 ) 2 C 2 B 4 H 6 , which had previously been shown to form mono- and bis(tricarbonylchromium) complexes. However, the reaction of Ph 2 C 2 B 4 H 5 - , CoCl 2 , and (PhPCH 2 ) 2 did give 1,1-(Ph 2 PCH 2 ) 2 -1-Cl-1,2,3-Co(Ph 2 C 2 B 4 H 4 ), the only case in which metal complexation of the diphenylcarborane was observed. 14 references, 3 figures, 3 tables

Measurements of H[sub c2](T) in Bi-Sr-Cu-O

Energy Technology Data Exchange (ETDEWEB)

Osofsky, M.S.; Soulen, R.J. Jr.; Wolf, S.A. (Naval Research Lab., Washington, DC (United States)); Broto, J.M.; Rakoto, H.; Ousset, J.C.; Coffe, G.; Askenazy, S. (Service National des Champs Magnetique Pulses, Toulouse (France)); Pari, P. (Laboratoire des Basses Temperatures, Gif-sur-Yvette (France)); Bozovic, I.; Eckstein, J.N.; Virshup, G.F. (Varian Associates, Palo Alto, CA (United States))

1994-04-01

H[sub c2](T) has been measured for thin BSCO films at temperatures down to 65 mK and pulsed fields up to 35 T. H[sub c2](T) diverged anomalously as the temperature decreased. At the lowest temperature, it was five times that expected for a conventional superconductor. This result cannot be explained by any conventional model which relies on magnetic ordering, local pairing mechanisms, or superlattice superconductivity. 51 refs., 3 figs.

Study of the fragmentation of astrophysical interest molecules (C{sub n}H{sub m}) induced by high velocity collision; Etude de la fragmentation de molecules d'interet astrophysique de type C{sub n}H{sub m} par collision atomique de haute vitesse

Energy Technology Data Exchange (ETDEWEB)

Tuna, Th

2008-07-15

This work shows the study of atom-molecule collision processes in the high velocity domain (v=4,5 a.u). The molecules concerned by this work are small unsaturated hydrocarbons C{sub 1-4}H and C{sub 3}H{sub 2}. Molecules are accelerated with the Tandem accelerator in Orsay and their fragmentation is analyzed by the 4{pi}, 100% efficient detector, AGAT. Thanks to a shape analysis of the current signal from the silicon detectors in association with the well known grid method, we are able to measure all the fragmentation channels of the incident molecule. These dissociation measurements have been introduced in the modelization of two objects of the interstellar medium in which a lot of hydrocarbon molecules have been observed (TMC1, horse-head nebula). We have extended our branching ratios obtained by high velocity collision to other electronic processes included in the chemical database like photodissociation and dissociative recombination. This procedure is feasible under an assumption of the statistical point of view of the molecular fragmentation. The deviations following our modification are very small in the modelization of TMC1 but significant in the photodissociation region. The first part is dedicated to the description of the experimental setting that has enabled us to study the fragmentation of C{sub n}H{sub m} molecules: the Orsay's Tandem accelerator and the Agat detector. The second part deals with negative ion sources and particularly with the Sahat source that is based on electronic impact and has shown good features for the production of anions and correct stability for its use with accelerators. The third part is dedicated to the experimental results in terms of cross-sections, number of fragments and branching ratios, associated to the various collisional processes. The last part presents an application of our measurement of fragmentation data to astro-chemistry. In this field, the simulation codes of the inter-stellar medium require databases

Examination of near-wall hindered Brownian diffusion of nanoparticles: Experimental comparison to theories by Brenner (1961) and Goldman et al. (1967)

International Nuclear Information System (INIS)

Choi, C. K.; Margraves, C. H.; Kihm, K. D.

2007-01-01

Multilayered distributions of hindered mean square displacement (MSD) for nanoparticles are measured in the near-wall region within 500 nm from the solid surface using total internal reflection fluorescence microscopy, an evanescent wave microscopic imaging technique. Examined particles are yellow-green (505/515) polystyrene fluorescent nanospheres of 100, 250, and 500 nm radii with a specific gravity of 1.055. To ensure the measurement accuracy, special care is taken to minimize photobleaching of fluorescent particles by adding neutral density filters to optimally reduce the excitation power. The experimental results for parallel MSDs to the solid surface validate the theory of hindered diffusion [A. J. Goldman, R. G. Cox, and H. Brenner, 'Slow viscous motion of a sphere parallel to a plane - I: Motion through a quiescent fluid', Chem. Eng. Sci. 22, 637 (1967)] of spheres based on viscous slow-down in the near-wall region. It is also reported that the effect of adding sodium chloride up to 10 mM to the solution has little effect on the parallel diffusive motion of the tested nanoparticles. Experimental evidence shows that normal MSDs, for submicroscopic charged nanoparticles, are substantially different from Einstein's 2DΔt due to the deterministic motion arising from electrostatic forces

Measurement of the C / H ratio using neutrons; Mesure du rapport C / H au moyen des neutrons

Energy Technology Data Exchange (ETDEWEB)

Martinelli, P [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Ricci, H [Universite de Lima (Peru)

1960-07-01

A probe made up of a Ra ({alpha}, n) Be neutron source and a proportional counter filled with boron trifluoride has been used to measure the C/H ratio in hydrocarbons. The intensity of the thermal neutron flux in the neighbourhood of the detector increases with the concentration of the hydrocarbon hydrogen surrounding it. By measuring the density it is possible to deduce the C/H ratio. It is thus possible to evaluate the C/H ratio with a precision equal to that given by the {beta}-ray transmission method. The errors arising from the chemical nature of the hydrocarbon can be reduced to a minimum. This method has the advantage of allowing the measurement of the C/H ratio of hydrocarbons contained in recipients or thick steel tubing by means an independent portable apparatus. (author) [French] Une sonde constituee d'une source de neutrons Ra ({alpha}, n) Be et d'un compteur proportionnel a remplissage de trifluorure de bore a ete utilisee pour mesurer le rapport C/H dans les hydrocarbures. Le flux des neutrons thermiques au voisinage du detecteur est d'autant plus intense que la concentration en hydrogene de l'hydrocarbure qui entoure la sonde est plus elevee. Une mesure de densite permet d'en deduire le rapport C/H. On peut ainsi evaluer le rapport C/H avec une precision aussi bonne que celle que l'on obtient par transmission de rayons {beta}. Les erreurs provenant de la nature chimique de l'hydrocarbure peuvent etre minimisees. Cette methode presente l'avantage de permettre la mesure du rapport C/H d'hydrocarbures contenus dans des recipients ou des canalisations epaisses en acier a l'aide d'un appareil exterieur transportable. (auteur)

Electrooxidative Ruthenium-Catalyzed C-H/O-H Annulation by Weak O-Coordination.

Science.gov (United States)

Qiu, Youai; Tian, Cong; Massignan, Leonardo; Rogge, Torben; Ackermann, Lutz

2018-05-14

Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C-H activation is restricted to strongly N-coordinating directing groups. The first example of electrocatalytic C-H activation by weak O-coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C-H/O-H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C-H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Electronic Structure of Dissymmetrical, Naphthalene-Bridged Sandwich Complexes [Cp ' Fe(mu-C10H8)MCp*](x) (x=0,+1; M = Fe, Ru; Cp ' = eta(5)-C5H2-1,2,4-tBu(3); Cp* = eta(5)-C5Me5)

NARCIS (Netherlands)

Malberg, J.; Lupton, E.; Schnöckelborg, E.M.; de Bruin, B.; de Sutter, J.; Meyer, K.; Hartl, F.; Wolf, R.

2013-01-01

The dissymmetrical naphthalene-bridged complexes [Cp'Fe(mu-C10H8)FeCp*] (3; Cp* = eta(5)-C5Me5, Cp' = eta(5)-C5H2-1,2,4-tBu(3)) and [Cp'Fe(mu-C10H8)RuCp*] (4) were synthesized via a one-pot procedure from FeCl2(thf)(1.5), Cp'K, KC10H8, and [Cp*FeCl(tmeda)] (tmeda =

Autoradiography of H-3-pirenzepine and H-3-AFDX-384 in Mouse Brain Regions: Possible Insights into M-1, M-2, and M-4 Muscarinic Receptors Distribution

Czech Academy of Sciences Publication Activity Database

Valuskova, P.; Farar, V.; Forczek, Sándor; Křížová, I.; Mysliveček, J.

2018-01-01

Roč. 9, FEB 20 (2018), č. článku 124. ISSN 1663-9812 Institutional support: RVO:61389030 Keywords : 3 h-afdx-384 * 3 H-pirenzepine * 3 h-qnb * Autoradiography * M muscarinic receptor 1 * M muscarinic receptor 2 * M muscarinic receptor 4 Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology Impact factor: 4.400, year: 2016

Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

Energy Technology Data Exchange (ETDEWEB)

Colby, Denise; Bergman, Robert; Ellman, Jonathan

2010-05-13

Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach

Identification and H(D)-bond energies of C-H(D)Cl interactions in chloride-haloalkane clusters: a combined X-ray crystallographic, spectroscopic, and theoretical study.

Science.gov (United States)

Serebryanskaya, Tatiyana V; Novikov, Alexander S; Gushchin, Pavel V; Haukka, Matti; Asfin, Ruslan E; Tolstoy, Peter M; Kukushkin, Vadim Yu

2016-05-18

The cationic (1,3,5-triazapentadiene)Pt(II) complex [Pt{NH[double bond, length as m-dash]C(N(CH2)5)N(Ph)C(NH2)[double bond, length as m-dash]NPh}2]Cl2 ([]Cl2) was crystallized from four haloalkane solvents giving [][Cl2(CDCl3)4], [][Cl2(CHBr3)4], [][Cl2(CH2Cl2)2], and [][Cl2(C2H4Cl2)2] solvates that were studied by X-ray diffraction. In the crystal structures of [][Cl2(CDCl3)4] and [][Cl2(CHBr3)4], the Cl(-) ion interacts with two haloform molecules via C-DCl(-) and C-HCl(-) contacts, thus forming the negatively charged isostructural clusters [Cl(CDCl3)2](-) and [Cl(CHBr3)2](-). In the structures of [][Cl2(CH2Cl2)2] and [][Cl2(C2H4Cl2)2], cations [](2+) are linked to a 3D-network by a system of H-bondings including one formed by each Cl(-) ion with CH2Cl2 or C2H4Cl2 molecules. The lengths and energies of these H-bonds in the chloride-haloalkane clusters were analyzed by DFT calculations (M06 functional) including AIM analysis. The crystal packing noticeably affected the geometry of the clusters, and energy of C-HCl(-) hydrogen bonds ranged from 1 to 6 kcal mol(-1). An exponential correlation (R(2) > 0.98) between the calculated Cl(-)H distances and the energies of the corresponding contacts was found and used to calculate hydrogen bond energies from the experimental Cl(-)H distances. Predicted energy values (3.3-3.9 kcal mol(-1) for the [Cl(CHCl3)2](-) cluster) are in a reasonable agreement with the energy of the Cl3C-HCl(-) bond estimated using ATRFTIR spectroscopy (2.7 kcal mol(-1)).

Sujecion de piezas durante las mediciones con M.M.C

Directory of Open Access Journals (Sweden)

Miguel Ángel Sellés Cantó

2012-08-01

Full Text Available This Coordinate Measuring Machines (C.M.M. has had an increasingly important role throughout history. We are talking to an enterprise-level quality control. A system that is being implemented in all companies, and has developed some tools to control a variety of parameters such as production stabilization.In this paper, we first set out an introduction to the use of C.M.M. as tools for quality control in SME's. Then we explore the importance of piece positioning and clamping before being measured in a C.M.M. We finally analyze four possible moorings, and deviations are obtained. These moorings are designed in order to place the same work piece in the four cases.Finally, the results obtained are compared and show which is the best way to put the part on the C.M.M.

Photocatalytic degradation of hexadecyl trimethyl ammonium chloride C/sub 19/H/sub 42/NCl

International Nuclear Information System (INIS)

Hassan, M.U.; Anwar, J.; Saif, M.J.

2008-01-01

Surfactants in the environment are a prerequisite for the sustainable development of human health and ecosystems. Surfactants are important in daily life in households as well as in industrial cleansing processes. It is important to have a detailed knowledge about their lifetime in the environment, their biodegradability in wastewater treatment plants and in natural waters, and their ecotoxicity. Most of the issues on environmental acceptability focus on the effects on the environment associated with the use and disposal of these surfactants. These effects are taken into account by a risk assessment. The first step in a risk assessment is an estimate of the concentrations of surf act ants in the environmental compartment of interest, such as wastewater treatment plant effluents, surface waters, sediments, and soils. This estimate is generated either by actual measurement or by prediction via modelling. The measured or predicted concentrations are then compared to the concentrations of surfactant known to be toxic to organisms living in these environmental compartments. There are many situations where industry is producing both heavy metals ions and organic pollutants, Successful treatment of effluents of this type to achieve legislative compliance will depend on whether the heavy metals effect the process of degradation of the organic species and whether the presence of organic molecules hinder the process of removal of heavy metals. Degradation of cationic surfactant was studied with a photolytic cell system. Compressed air was used as oxidant and the temperature was maintained at 25-30 degree C. Effect of UV source, hydrogen peroxide (H/sub 2/O/sub 2/) and titanium (TiO/sub 2/) on Hexadecyl trimethyl ammonium Chloride C/sub 19/H/sub 42/NCl were recorded. HPLC and IR were used to analyse to study the rate of degradation of C/sub 19/H/sub 42/NCl. (author)

Investigation on pseudosymmetry, twinning and disorder in crystal structure determinations: Ba(H2O)M2III[PO3(OH)]4 (M=Fe, V) as examples

International Nuclear Information System (INIS)

Sun Wei; Huang Yaxi; Pan Yuanming; Mi Jinxiao

2012-01-01

Twinning commonly occurs in monoclinic crystals with dimensionally similar a and c axes and results in pseudo-orthorhombic symmetries with overlapping diffractions. For example, twinning in the new synthetic compound Ba(H 2 O)Fe 2 [PO 3 (OH)] 4 , which varies in space group from P2 1 to P2 1 /c with approximately equal a and c axial lengths, gives rise to a pseudosymmetry of C222 1 . Similarly, the related compound Ba(H 2 O)V 2 [PO 3 (OH)] 4 is commonly twinned and varies in space groups as well, arising from ordered to disordered distributions of the barium cations and water molecules in the cavities. Moreover, analyses of these and other twinned structures show that the small average standard uncertainty of bond distances is a sensitive criterion for structure determinations, especially for those involving crystal twinning as well as order–disorder. A proper structure determination leads to small standard uncertainties of the atomic displacement parameters, which further result in the small standard uncertainties of bond distances. - Graphical abstract: Ba(H 2 O)M 2 III [PO 3 (OH)] 4 (M=Fe, V) varies in space group from P2 1 to P2 1 /c, arising from ordered to disordered distributions of Ba 2+ and H 2 O in the cavities. Highlights: ► Twinning commonly occurs in monoclinic crystals with a≈c. ► Overlapping diffractions from twin domains hamper with the determination of real space groups. ► Conventional criteria for evaluating the real space groups are not effective in this case. ► Small standard uncertainty of bond distances is proposed as a sensitive criterion. ► Using this criterion we determined the order–disorder structures of Ba(H 2 O)M 2 III [PO 3 (OH)] 4 (M=Fe, V) from twinned crystals.

A bonding study of c-C5H8 adsorption on Pt(111)

International Nuclear Information System (INIS)

Simonetti, S.; Jasen, P.; Gonzalez, E.; Juan, A.; Brizuela, G.

2006-01-01

The chemisorption of cyclopentane (c-C 5 H 8 ) on Pt(111) has been studied using a qualitative band-structure calculations in the framework of tight-binding implementation with the YAeHMOP package. We modeled the metal surface by a two-dimensional slab of finite thickness with an overlayer of c-C 5 H 8 , in a (3x3) di-σ geometry. The c-C 5 H 8 molecule is attached to the surface with its C?C atoms bonded mainly with two Pt atoms while the opposite CH 2 bends towards the surface. The Pt?Pt bonds in the underlying surface and the C?C bonds of c-C 5 H 8 are weakened upon the chemisorption. A noticeable Pt-H and Pt-C interactions has been observed. We found that of Pt 5d z 2 band plays an important role in the bonding between c-C 5 H 8 and the surface, as do the Pt 6s and 6p z bands. The HOMO-LUMO bands of c-C 5 H 8 are very dispersed, indicative of a strong interaction with the metal surface

[Protective effect of taxifolin on H2O2-induced 
H9C2 cell pyroptosis].

Science.gov (United States)

Ye, Yanqiong; Wang, Xiaoli; Cai, Qian; Zhuang, Jian; Tan, Xiaohua; He, Wei; Zhao, Mingyi

2017-12-28

To explore the effect of taxifolin on H2O2-induced pyroptosis in H9C2 cells and the possible mechanisms.
 Methods: The H9C2 cells was divided into 3 groups: a control group, a hydrogen peroxide (H2O2)group and a taxifolin group. The morphology of H9C2 cells was observed by inverted phase contrast microscope. The mitochondrial membrane potential was measured by JC-1 staining and flow cytometry. The alteration of the level of reactive oxygen species (ROS) was detected by specific mitochondrial probe. The protein levels of cysteinyl aspartate specific proteinase-1 (caspase-1)was determined by Western blot. The mRNA levels of interleukin-18 (IL-18), interleukin-1a (IL-1a), interleukin-1b (IL-1b), absent in melanoma 2 (AIM2), apoptosis-associated apeck-like protein (ASC), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)and nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain-containing protein 4 (NLRC4) were determined by reverse transcription-polymerase chain reaction (RT-PCR).
 Results: Compared with the control group, the morphology of H9C2 cells obviously changed in the H2O2-treated group, which was guadually improved in the presence of taxifolin. Compared with the control group, the mitochondrial membrane potential was markedly decreased in the H2O2-treated cells, accompanied by the increase ofROS (both PH2O2 group, the mitochondrial membrane potential changes in the taxifolin group was increased while the ROS was decreased, with significant difference (both PH2O2-treated group were significantly increased (all PH2O2-induced H9C2 cell pyroptosis through inhibition of AIM2, NLRP3 and NLRC4 in flammasome.

Recent Developments in C-H Activation for Materials Science in the Center for Selective C-H Activation.

Science.gov (United States)

Zhang, Junxiang; Kang, Lauren J; Parker, Timothy C; Blakey, Simon B; Luscombe, Christine K; Marder, Seth R

2018-04-16

Abstract : Organic electronics is a rapidly growing field driven in large part by the synthesis of ∏-conjugated molecules and polymers. Traditional aryl cross-coupling reactions such as the Stille and Suzuki have been used extensively in the synthesis of ∏-conjugated molecules and polymers, but the synthesis of intermediates necessary for traditional cross-couplings can include multiple steps with toxic and hazardous reagents. Direct arylation through C-H bond activation has the potential to reduce the number of steps and hazards while being more atom-economical. Within the Center for Selective C-H Functionalization (CCHF), we have been developing C-H activation methodology for the synthesis of ∏-conjugated materials of interest, including direct arylation of difficult-to-functionalize electron acceptor intermediates and living polymerization of ∏-conjugated polymers through C-H activation.

Hydrogenation and Deuteration of C{sub 2}H{sub 2} and C{sub 2}H{sub 4} on Cold Grains: A Clue to the Formation Mechanism of C{sub 2}H{sub 6} with Astronomical Interest

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Hitomi; Kawakita, Hideyo [Koyama Astronomical Observatory, Kyoto Sangyo University Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan); Hidaka, Hiroshi; Hama, Tetsuya; Watanabe, Naoki [Institute of Low Temperature Science, Hokkaido University N19-W8, Kita-ku, Sapporo, Hokkaido 060-0819 (Japan); Lamberts, Thanja; Kästner, Johannes, E-mail: h_kobayashi@kyoto-nijikoubou.com [Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

2017-03-10

We quantitatively investigated the hydrogen addition reactions of acetylene (C{sub 2}H{sub 2}) and ethylene (C{sub 2}H{sub 4}) on amorphous solid water (ASW) at 10 and 20 K relevant to the formation of ethane (C{sub 2}H{sub 6}) on interstellar icy grains. We found that the ASW surface enhances the reaction rates for C{sub 2}H{sub 2} and C{sub 2}H{sub 4} by approximately a factor of 2 compared to those on the pure-solid C{sub 2}H{sub 2} and C{sub 2}H{sub 4} at 10 K, probably due to an increase in the sticking coefficient and adsorption energy of the H atoms on ASW. In contrast to the previous proposal that the hydrogenation rate of C{sub 2}H{sub 4} is orders of magnitude larger than that of C{sub 2}H{sub 2}, the present results show that the difference in hydrogenation rates of C{sub 2}H{sub 2} and C{sub 2}H{sub 4} is only within a factor of 3 on both the surfaces of pure solids and ASW. In addition, we found the small kinetic isotope effect for hydrogenation/deuteration of C{sub 2}H{sub 2} and C{sub 2}H{sub 4} at 10 K, despite the requirement of quantum tunneling. At 20 K, the reaction rate of deuteration becomes even larger than that of hydrogenation. These unusual isotope effects might originate from a slightly larger number density of D atoms than H atoms on ASW at 20 K. The hydrogenation of C{sub 2}H{sub 2} is four times faster than CO hydrogenation and can produce C{sub 2}H{sub 6} efficiently through C{sub 2}H{sub 4} even in the environment of a dark molecular cloud.

Approximations for the waiting-time distribution in an M/P H/c priority queue

NARCIS (Netherlands)

Al Hanbali, Ahmad; Alvarez, Elisa; van der Heijden, Matthijs C.

2015-01-01

We investigate the use of priority mechanisms when assigning service engineers to customers as a tool for service differentiation. To this end, we analyze a non-preemptive M/PH/c priority queue with various customer classes. For this queue, we present various accurate and fast methods to estimate

Densities, viscosities, and refractive indexes for {C2H5CO2(CH2)2CH3+C6H13OH+C6H6} at T=308.15 K

International Nuclear Information System (INIS)

Casas, Herminio; Garcia-Garabal, Sandra; Segade, Luisa; Cabeza, Oscar.; Franjo, Carlos; Jimenez, Eulogio

2003-01-01

In this work we present densities, kinematic viscosities, and refractive indexes of the ternary system {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 13 OH+C 6 H 6 } and the corresponding binary mixtures {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 6 }, {C 2 H 5 CO 2 (CH 2 ) 2 CH 3 +C 6 H 13 OH}, and {C 6 H 13 OH+C 6 H 6 }. All data have been measured at T=308.15 K and atmospheric pressure over the whole composition range. The excess molar volumes, dynamic viscosity deviations, and changes of the refractive index on mixing were calculated from experimental measurements. The results for binary mixtures were fitted to a polynomial relationship to estimate the coefficients and standard deviations. The Cibulka equation has been used to correlate the experimental values of ternary mixtures. Also, the experimental values obtained for the ternary mixture were used to test the empirical methods of Kohler, Jacob and Fitzner, Colinet, Tsao and Smith, Toop, Scatchard et al., and Hillert. These methods predict excess properties of the ternary mixtures from those of the involved binary mixtures. The results obtained for dynamic viscosities of the binary mixtures were used to test the semi-empirical relations of Grunberg-Nissan, McAllister, Auslaender, and Teja-Rice. Finally, the experimental refractive indexes were compared with the predicted results for the Lorentz-Lorenz, Gladstone-Dale, Wiener, Heller, and Arago-Biot equations. In all cases, we give the standard deviation between the experimental data and that calculated with the above named relations

N.M.R. study of organo-phosphorus compounds: non equivalence of methylenic protons in the {alpha} position of an asymmetric phosphorus atom. Application to study of coupling constants J{sub P,H} and J{sub H,H}; R.M.N. de composes organo-phosphores: non equivalence de protons methyleniques en {alpha} d'un phosphore asymetrique. Application a l'etude des constantes de couplage J{sub P,H} et J{sub H,H}

Energy Technology Data Exchange (ETDEWEB)

Albrand, J P [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1969-07-01

Non-equivalent methylenic protons, with respect to an asymmetric center, have been observed in the n.m.r. spectra of some three- and tetra-coordinated phosphorus compounds. The analysis of these spectra yield the following results: in the studied secondary phosphines, the inversion rate at the phosphorus atom is slow on the n.m.r. time scale; the geminal coupling constant, for a free-rotating methylene group attached to a phosphorus atom, is negative; in phosphines the non equivalence of methylenic protons reveals two {sup 2}J{sub P-C-H} coupling constants which differ by about 5 Hz. This result is in agreement with previous studies on cyclic phosphines. In phosphine oxides, the {sup 2}J{sub P-C-H} values are negative. The {sup 3}J{sub H-P-C-H} coupling constant is positive in both phosphines and phosphine oxides. In phosphines, the non-equivalent methylenic protons exhibit two nearly equal values for this coupling constant. (author) [French] La non-equivalence de protons methyleniques observee dans quelques composes phosphores tricoordines et tetracoordines a apporte les resultats suivants, concernant la stereochimie et les constantes de couplage dans ces composes: dans les phosphines secondaires, la structure pyramidale des liaisons issues du phosphore est fixe a l'echelle de temps de mesure de la R.M.N.; la constante de couplage {sup 2}J{sub H-C-H}, pour un methylene en libre rotation en {alpha} d'un atome de phosphore, est negative; dans les phosphines etudiees, la non-equivalence. observee pour les protons methyleniques s'accompagne d'une difference importante (5 Hz) entre les deux constantes de couplage {sup 2}J{sub P-C-H} determinees par l'analyse; ce resultat est en accord avec la stereospecificite deja observee pour ce couplage dans les phosphines cycliques. Les valeurs observees pour {sup 2}J{sub P-C-H} dans les oxydes de phosphines sont negatives. Les valeurs de la constante de couplage {sup 3}J{sub H-P-C-H}, dans les phosphines et oxydes de phosphine

Overlearned responses hinder S-R binding.

Science.gov (United States)

Moeller, Birte; Frings, Christian

2017-01-01

Two mechanisms that are important for human action control are the integration of individual action plans (see Hommel, Müsseler, Aschersleben, & Prinz, 2001) and the automatization of overlearned actions to familiar stimuli (see Logan, 1988). In the present study, we analyzed the influence of automatization on action plan integration. Integration with pronunciation responses were compared for response incompatible word and nonword stimuli. Stimulus-response binding effects were observed for nonwords. In contrast, words that automatically triggered an overlearned pronunciation response were not integrated with pronunciation of a different word. That is, automatized response retrieval hindered binding effects regarding the retrieving stimulus and a new response. The results are a first indication of the way that binding and learning processes interact, and might also be a first step to understanding the more complex interdependency of the processes responsible for stimulus-response binding in action control and stimulus-response associations in learning research. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Reactive carbon-chain molecules: synthesis of 1-diazo-2,4-pentadiyne and spectroscopic characterization of triplet pentadiynylidene (H-C[triple bond]C-:C-C[triple bond]C-H).

Science.gov (United States)

Bowling, Nathan P; Halter, Robert J; Hodges, Jonathan A; Seburg, Randal A; Thomas, Phillip S; Simmons, Christopher S; Stanton, John F; McMahon, Robert J

2006-03-15

1-Diazo-2,4-pentadiyne (6a), along with both monodeuterio isotopomers 6b and 6c, has been synthesized via a route that proceeds through diacetylene, 2,4-pentadiynal, and 2,4-pentadiynal tosylhydrazone. Photolysis of diazo compounds 6a-c (lambda > 444 nm; Ar or N2, 10 K) generates triplet carbenes HC5H (1) and HC5D (1-d), which have been characterized by IR, EPR, and UV/vis spectroscopy. Although many resonance structures contribute to the resonance hybrid for this highly unsaturated carbon-chain molecule, experiment and theory reveal that the structure is best depicted in terms of the dominant resonance contributor of penta-1,4-diyn-3-ylidene (diethynylcarbene, H-C[triple bond]C-:C-C[triple bond]C-H). Theory predicts an axially symmetric (D(infinity h)) structure and a triplet electronic ground state for 1 (CCSD(T)/ANO). Experimental IR frequencies and isotope shifts are in good agreement with computed values. The triplet EPR spectrum of 1 (absolute value(D/hc) = 0.6157 cm(-1), absolute value(E/hc) = 0.0006 cm(-1)) is consistent with an axially symmetric structure, and the Curie law behavior confirms that the triplet state is the ground state. The electronic absorption spectrum of 1 exhibits a weak transition near 400 nm with extensive vibronic coupling. Chemical trapping of triplet HC5H (1) in an O2-doped matrix affords the carbonyl oxide 16 derived exclusively from attack at the central carbon.

Fluoride induces apoptosis in H9c2 cardiomyocytes via the mitochondrial pathway.

Science.gov (United States)

Yan, Xiaoyan; Wang, Lu; Yang, Xia; Qiu, Yulan; Tian, Xiaolin; Lv, Yi; Tian, Fengjie; Song, Guohua; Wang, Tong

2017-09-01

Numerous studies have shown that chronic excessive fluoride intake can adversely affect different organ systems. In particular, the cardiovascular system is susceptible to disruption by a high concentration of fluoride. The objectives of this study were to explore the mechanism of apoptosis by detecting the toxic effects of different concentrations of sodium fluoride (NaF) in H9c2 cells exposed for up to 96 h. NaF not only inhibited H9c2 cell proliferation but also induced apoptosis and morphological damage. With increasing NaF concentrations, early apoptosis of H9c2 cells was increased while the mitochondrial membrane potential was decreased. Compared with the control group, the mRNA levels of caspase-3, caspase-9, and cytochrome c all increased with increasing concentrations of NaF. In summary, these data suggest that apoptosis is involved in NaF-induced H9c2 cell toxicity and that activation of the mitochondrial pathway may occur. Copyright © 2017 Elsevier Ltd. All rights reserved.

p38 mitogen-activated protein kinase (p38MAPK) upregulates catalase levels in response to low dose H2O2 treatment through enhancement of mRNA stability.

Science.gov (United States)

Sen, Prosenjit; Chakraborty, Prabir Kumar; Raha, Sanghamitra

2005-08-15

V79 fibroblasts were repetitively stressed through multiple exposures to a low dose (30 microM) H2O2 in culture for 4 weeks. Catalase activity, protein levels and mRNA levels increased markedly (5-6-fold) during this time and these augmentations were inhibited by the simultaneous presence of SB203580, an inhibitor of p38 mitogen-activated protein kinase (p38MAPK). p38MAPK became dually phosphorylated and ATF-2, a p38MAPK substrate also became increasingly phosphorylated over the repetitive stress period. Short interfering RNA that induced effective silencing of p38MAPK, was used to silence p38MAPK in V79 fibroblasts. Silencing of p38MAPK drastically hindered the elevation in catalase (protein and mRNA) levels observed after a single low dose (50 microM) of H2O. The rise in catalase mRNA levels induced by low concentration (single and multiple dose) H2O2 treatment was established to be unconnected with transcriptional upregulation but was brought forth primarily by an enhancement in catalase mRNA stability through the action of p38MAPK. Therefore, our data strongly indicate that activation of p38MAPK is a key controlling step in the upregulation of catalase levels by low dose H2O2 treatment.

The effects of gamma irradiation on the fate of hindered phenol antioxidants in food contact polymers. Analytical and 14C-labelling studies

International Nuclear Information System (INIS)

Allen, D.W.; Leathard, D.A.; Smith, C.

1991-01-01

The extractable levels of two hindered phenol antioxidants (Irganox 1076 and Irganox 1010) present in PVC, polyethylene and polypropylene have been monitored by HPLC techniques following progressive exposure of the polymers to 60 Co(gamma) radiation. There is a gradual diminution in the extractable levels of each antioxidant as irradiation progresses as a result of transformation of the antioxidants in the oxidation reactions ensuing during irradiation. Experiments involving the use of a 14 C-labelled sample of Irganox 1076 in polyolefins have provided evidence of covalent binding of antioxidant degradation products to the polymer following gamma irradiation. However, there is also evidence of the formation of extractable degradation products, the identity of which is as yet unknown. (author)

The effects of gamma irradiation on the fate of hindered phenol antioxidants in food contact polymers. Analytical and 14C-labelling studies

Science.gov (United States)

Allen, David W.; Leathard, David A.; Smith, Christine

The extractable levels of two hindered phenol antioxidants (Irganox 1076 and Irganox 1010) present in PVC, polyethylene and polypropylene, have been monitored by HPLC techniques following progressive exposure of the polymers to 60Co γ radiation. There is a gradual diminution in the extractable levels of each antioxidant as irradiation progresses as a result of transformation of the antioxidants in the oxidation reactions ensuing during irradiation. Experiments involving the use of a 14C-labelled sample of Irganox 1076 in polyolefins have provided evidence of covalent binding of antioxidant degradation products to the polymer following gamma irradiation. However, there is also evidence of the formation of extractable degradation products, the identity of which is as yet unknown.

Low-temperature heat capacity and standard molar enthalpy of formation of 9-fluorenemethanol (C14H12O)

International Nuclear Information System (INIS)

Di, You-Ying; Tan, Zhi-Cheng.; Sun, Xiao-Hong; Wang, Mei-Han; Xu, Fen; Liu, Yuan-Fa; Sun, Li-Xian; Zhang, Hong-Tao

2004-01-01

Low-temperature heat capacities of the 9-fluorenemethanol (C 14 H 12 O) have been precisely measured with a small sample automatic adiabatic calorimeter over the temperature range between T=78 K and T=390 K. The solid-liquid phase transition of the compound has been observed to be T fus =(376.567±0.012) K from the heat-capacity measurements. The molar enthalpy and entropy of the melting of the substance were determined to be Δ fus H m =(26.273±0.013) kJ · mol -1 and Δ fus S m =(69.770±0.035) J · K -1 · mol -1 . The experimental values of molar heat capacities in solid and liquid regions have been fitted to two polynomial equations by the least squares method. The constant-volume energy and standard molar enthalpy of combustion of the compound have been determined, Δ c U(C 14 H 12 O, s)=-(7125.56 ± 4.62) kJ · mol -1 and Δ c H m compfn (C 14 H 12 O, s)=-(7131.76 ± 4.62) kJ · mol -1 , by means of a homemade precision oxygen-bomb combustion calorimeter at T=(298.15±0.001) K. The standard molar enthalpy of formation of the compound has been derived, Δ f H m compfn (C 14 H 12 O,s)=-(92.36 ± 0.97) kJ · mol -1 , from the standard molar enthalpy of combustion of the compound in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle

Sensitive method for continuous air monitoring for /sup 14/C and /sup 3/H. Empfindliches verfahren zur koninuierlichen C-14 und H-3 luftueberwachung

Energy Technology Data Exchange (ETDEWEB)

Rudolph, J.; Weiss, W.

1976-07-01

In the monitoring of air for /sup 14/C and /sup 3/H the necessary sensitivity cannot be achieved by direct measurement, but only through continuous sampling and scintillation spectroscopy. The two radionuclides are separated from each other at the time of sampling. In addition, by a catalytic reaction over CuO at 600/sup 0/C, a differentiation is achieved between tritiated atmospheric water vapor (HTO), /sup 14/CO/sub 2/ and other isotopically labeled substances contained in the air. Tritium is obtained in the form of water and /sup 14/C as Na/sub 2//sup 14/CO/sub 3/. Radioactivity is measured in a scintillation spectrometer. For tritium this method has a detection limit of 0.8 pCi/m/sup 3/ or air, and for C/sup 14/ 0.6 pCi/m/sup 3/ of air. These values correspond to 15 to 30% of the mean background concentration for HTO and /sup 14/CO/sub 2/ observed up to the present.

Fabrication of 4H-SiC Schottky barrier diodes with high breakdown voltages

CERN Document Server

Kum, B H; Shin, M W; Park, J D

1999-01-01

This paper discusses the fabrication and the breakdown characteristics of 4H-SiC Schottky barrier diodes (SBDs). Optimal processing conditions for the ohmic contacts were extracted using the transmission-line method (TLM) and were applied to the device fabrication. The Ti/4H-SiC SBDs with Si sub x B sub y passivation showed a maximum reverse breakdown voltage of 268 V with a forward current density as high as 70 mA/cm sup 2 at a forward voltage of 2 V. The breakdown of the Pt. 4H-SiC SBDs without any passivation occurred at near 110 V. It is concluded that the breakdown enhancement in the Ti/4H-SiC SBDs can be attributed to the passivation; otherwise, excess surface charge near the edge of the Schottky contact would lead to electric fields of sufficient magnitude to cause field emission.

Rietveld refinement of the structures of 1.0 C-S-H and 1.5 C-S-H

KAUST Repository

Battocchio, Francesco

2012-11-01

Low-Q region Rietveld analyses were performed on C-S-H synchrotron XRD patterns, using the software MAUD. Two different crystal structures of tobermorite 11 Å were used as a starting model: monoclinic ordered Merlino tobermorite, and orthorhombic disordered Hamid tobermorite. Structural modifications were required to adapt the structures to the chemical composition and the different interlayer spacing of the C-S-H samples. Refinement of atomic positions was done by using special constraints called fragments that maintain interatomic distances and orientations within atomic polyhedra. Anisotropic crystallite size refinement showed that C-S-H has a nanocrystalline disordered structure with a preferred direction of elongation of the nanocrystallites in the plane of the Ca interlayer. The quality of the fit showed that the monoclinic structure gives a more adequate representation of C-S-H, whereas the disordered orthorhombic structure can be considered a more realistic model if the lack of long-range order of the silica chain along the c-direction is assumed. © 2012 Elsevier Ltd. All rights reserved.

The bovine papillomavirus E5 oncogene can cooperate with ras: identification of p21 amino acids critical for transformation by c-rasH but not v-rasH

DEFF Research Database (Denmark)

Willumsen, B M; Vass, W C; Velu, T J

1991-01-01

We have previously used a series of insertion-deletion mutants of the mutationally activated v-rasH gene to identify several regions of the encoded protein that are dispensable for cellular transformation (B. M. Willumsen, A. G. Papageorge, H.-F. Kung, E. Bekesi, T. Robins, M. Johnsen, W. C. Vass...... in their v-rasH forms. We conclude that a region including amino acids 102 and 103 encodes a function that is more critical to c-rasH than to v-rasH. Guanine nucleotide exchange is one function that is compatible with such a phenotype......., and D. R. Lowy, Mol. Cell. Biol. 6:2646-2654, 1986). To determine if some of these amino acids are more important for the biological activity of c-rasH, we have now tested many of the same insertion-deletion mutants in the c-rasH form for their ability to transform NIH 3T3 cells. Since the transforming...

Neutron diffraction study of phase relationship of Ti-C-H system

International Nuclear Information System (INIS)

Khidirov, I.; Mukhtarova, N.N.; Mirzaev, B.B.; Serikbaev, B.T.; Zaginaichenko, S.Yu.; Schur, D.V.; Pishuk, V.K.; Kuzmenko, L.V.; Garbuz, V.V.; Nuzhda, S.V.; Pishuk, O.V.

2006-01-01

temperature the sintering process is very active. Later on, the step increasing of temperature was carried out till 1000 deg. C with a step of 100 deg. C. The briquettes were exposed during 24 h at each temperature. With increasing temperature up to 800-1000 deg. C the pressured powder became well sintered and hydrogen emission from the sample was prevented. The final product was prepared after the annealing at 1000 deg. C followed by quenching in water. Compound of the samples was controlled by chemical analysis and compound of the single-phase samples also was controlled by minimizing the divergence factors of structure determination using neutron diffraction patterns. It is established that at hardening from 1000 deg. C in the samples with low concentration of C and H the solid solution of C and H in BCC β-Ti (with impurity of FCC- TiC x H y -phase) is formed. This metastable phase is stable enough at the room temperature. It is shown that at carbon concentration of 0.30 ≤ x ≤ 0.50 and y ≥ x in Ti-C-H system the ordered hexagonal close-packed (HCP) structure is stabilized, and at y x H y compounds have the ordered HCP structure corresponding to formula Ti 2 C 1-z H 2-z . The crystal structure of the phase is described within the framework of space group, where metal atoms are strongly displaced along c axis (Z Me =0.234±0.001) with respect to their ideal positions (z id =1/4). Step annealing of the single-phase solid solutions at temperatures of 700-600-500 deg. C during 24 h leads to decay of the samples, having concentration C/Ti≤0.43, the hydride phases being separated. Hence, the ordered solid solution Ti 2 C 1-x H 2-y is stable at concentrations 1.00≥C/Ti>0.43 (near carbon stoichiometry Ti 2 C), but it is metastable at concentrations 0.30≤C/T≤0.43. Compound TiC x H y at concentrations 0.45≤x≤0.55 and y< x can have both disordered (sp. gr. Fm3m) and ordered FCC-structure (sp. gr. Fd3m) depending on temperature. At temperatures lower than 600 deg. C

M-S-H precipitation in low-pH concretes in clayey environment

International Nuclear Information System (INIS)

Dauzeres, A.; Achiedo, G.; Nied, D.; L'Hopital, E.; Alahrache, S.; Lothenbach, B.

2015-01-01

In the framework of the CI-project (Cement Clay Interaction Experiment), two different low-pH cements were emplaced at Mont Terri rock laboratory to study their interactions with the surrounding Opalinus Clay (OPA): ESDRED (shotcrete mixture: 60% of CEM-I 42.5 N + 40% of silica fume + aluminium sulphate salt as accelerator) and LAC composed of CEM-III/B 42.5 L (60% of blast furnace slag + 10% nano silica). After 5 years of interactions in the Mont Terri rock laboratory, SEM-EDS analyses show a systematic Mg-perturbation associated with a high decalcification near the surface of both cementitious materials. TGA (Thermogravimetric Analysis) and XRD (X-ray diffraction) investigations associate this Mg-enrichment to the possible formation of M-S-H. This result is confirmed by 29 Si NMR analyses, showing a high polymerisation degree of the Si-network in the Mg-enriched zone typical of a sheet-like structure. Tem/EDS investigations of a FIB section carried out in the Mg zone of both LAC and ESDRED concretes indicate that the Mg phase exhibits a gel-like structure similar to C-S-H gel. This experimentally observed Mg-enrichment in the interaction zone is well reproduced by reactive transport modelling of the LAC/Opalinus clay with the HYTEC code. (authors)

Theoretical characterizations of novel C2H5O+ reactions

Science.gov (United States)

Hudson, Charles E.; McAdoo, David J.

2004-03-01

Assorted reactions of C2H5O+ isomers are characterized by theory, including tracing their courses by means of intrinsic reaction coordinate computations. We establish that CH3CH=OH+ eliminates methane by transferring H from oxygen to a methyl hydrogen and then to the CC bond to produce CHO++CH4. This adds to the limited knowledge of the involvement of hypervalent structures in the reactions of cations in the gas phase. Second, we characterized the course of CH3CH=OH+-->H3O++HC[triple bond; length as m-dash]CH. In this dissociation, H first migrates from the methyl to the oxygen to give O-protonated vinyl alcohol, a stable intermediate. Then the H2O swings outward to over the middle of the CC bond while one of the two hydrogens on the non-O-bearing carbon revolves to between the oxygen and the two carbons, leading to formation of a [H3O+ HC[triple bond; length as m-dash]CH] complex. This complex contains sufficient energy to dissociate its partners because a high barrier is crossed in its formation. Third, we found that methane elimination from CH3O+=CH2 involves stretching of the CH3---O bond and then rotation of the methyl so that a methyl hydrogen is pointed directly toward the oxygen. This reaction is completed by further rotation of the methyl to abstract a methylene hydrogen to the opposite side of the methyl from that initially bonded to oxygen. This clearly establishes that this dissociation takes place through an ion-neutral complex. Each of the reaction coordinates for the three preceding reactions traverses a novel bonding stage involving H, evidence that such are not unusual in gas phase ion chemistry. Finally, we showed that in the rearrangement CH3O+=CH2-->CH2=O+CH3, before Ht is transferred CH2 rotates around the C=C bond from being in the skeletal plane to being perpendicular to it, and Ht remains in the skeletal plane throughout its transfer. This pathway appears to balance avoiding an orbital symmetry-forbidden suprafacial transition state with

In-situ pH measurements and sample analyses in glass-iron-clay systems at 90 deg. C and 150 deg. C

International Nuclear Information System (INIS)

Rozsypal, Christophe; Mosser-Ruck, Regine; Truche, Laurent; Pignatelli, Isabella; Randi, Aurelien; Bartier, Daniele; Cathelineau, Michel; Michau, Nicolas

2012-01-01

Document available in extended abstract form only. The long term repository of long life and high activity radioactive waste consists in the burial of steel overpacks of vitrified waste in a clay-stone. As the natural interstitial fluid of the clay-stone is a potential corrosion enhancer for the containers, the viability of the repository requires previous data acquisition on the interactions between clays, water, metallic iron, and glass. A set of experiments have been performed in autoclaves at 90 deg. C (thermal peak of the site) in order to follow the pH evolution and to characterize fluids with time and solids at the end of the experiments. Another set of experiments at 150 deg. C have also been carried out in order to increase the rates of the involved chemical reactions and mineralogical transformations. The objectives of those two sets of experiments were to measure the in-situ pH, to study how it was influenced by various parameters, such as the presence of glass and/or iron, to estimate the increase of the CO 2 and H 2 pressures, and to analyze gas and liquids taken in the course or at the end of experiments and solids recovered at the end of the experiments. The initial aqueous solution simulating the natural interstitial fluid was made of 22 mM of sodium, 4 mM of calcium, 29.75 mM of chloride, and 0.25 mM of bromide as a tracer. The initial solution/clay mass ratio was 10 for all the experiments, the metallic iron/clay or glass/clay mass ratios were 0.1 or 0. The list of the experiments and their characteristics is given in Table (1). The first results concern the evolution of the in-situ pH during the A90pH experiment and are reported on Figure (1). The measurements started after a 48 hours stabilization time of the pH probe. The pH seemed to tend reaching a plateau after several weeks. (authors)

Tunable Robust pacs-MOFs: a Platform for Systematic Enhancement of the C2H2 Uptake and C2H2/C2H4 Separation Performance.

Science.gov (United States)

Chen, Di-Ming; Sun, Chun-Xiao; Zhang, Nan-Nan; Si, Huan-Huan; Liu, Chun-Sen; Du, Miao

2018-03-05

As a modulatable class of porous crystalline materials, metal-organic frameworks (MOFs) have gained intensive research attention in the domain of gas storage and separation. In this study, we report on the synthesis and gas adsorption properties of two robust MOFs with the general formula [Co 3 (μ 3 -OH)(cpt) 3 Co 3 (μ 3 -OH)(L) 3 (H 2 O) 9 ](NO 3 ) 4 (guests) n [L = 3-amino-1,2,4-triazole (1) and 3,5-diamino-1,2,4-triazole (2); Hcpt = 4-(4-carboxyphenyl)-1,2,4-triazole], which show the same pacs topology. Both MOFs are isostructural to each other and show MIL-88-type frameworks whose pore spaces are partitioned by different functionlized trinuclear 1,2,4-triazolate-based clusters. The similar framework components with different amounts of functional groups make them an ideal platform to permit a systematic gas sorption/separation study to evaluate the effects of distinctive parameters on the C 2 H 2 uptake and separation performance. Because of the presence of additional amido groups, the MOF 2 equipped with a datz-based cluster (Hdatz = 3,5-diamino-1,2,4-triazole) shows a much improved C 2 H 2 uptake capacity and separation performance over that of the MOF 1 equipped with atz-based clusters (Hatz = 3-amino-1,2,4-triazole), although the surface area of the MOF 1 is almost twice than that of the MOF 2. Moreover, the high density of open metal sites, abundant free amido groups, and charged framework give the MOF 2 an excellent C 2 H 2 separation performance, with ideal adsorbed solution theory selectivity values reaching up to 11.5 and 13 for C 2 H 2 /C 2 H 4 (1:99) and C 2 H 2 /CO 2 (50:50) at 298 K and 1 bar, showing potential for use in natural gas purification.

Absence of PDGF-induced, PKC-independent c-fos expression in a chemically transformed C3H/10T1/2 cell clone.

Science.gov (United States)

Vassbotn, F S; Skar, R; Holmsen, H; Lillehaug, J R

1992-09-01

The effect of platelet-derived growth factor (PDGF) on c-fos mRNA transcription was studied in the immortalized mouse embryo fibroblast C3H/10T1/2 Cl 8 (10T1/2) cells and the chemically transformed, tumorigenic subclone C3H/10T1/2 Cl 16 (Cl 16). In the 10T1/2 cells as well as the Cl 16 subclone, the dose-dependent PDGF stimulation of c-fos mRNA synthesis was similar in both logarithmically growing and confluent cultures. c-fos mRNA was induced severalfold by 12-O-tetradecanoylphorbol-13-acetate (TPA) in both 10T1/2 and Cl 16. Down-regulation of protein kinase C (PKC) activity by TPA pretreatment inhibited PDGF-stimulated c-fos mRNA expression in Cl 16 cells but did not affect this induction in the 10T1/2 cells. This inhibition was not a general phenomenon of 3-methylcholanthrene-mediated transformation of 10T1/2 cells since experiments with another transformed 10T1/2 cell clone, C3H/10T1/2 TPA 482, gave qualitatively the same results as the 10T1/2 cells. Receptor binding experiments showed that the nontransformed and transformed cells had a comparable number of PDGF receptors, 1.3 x 10(5) and 0.7 x 10(5) receptors per cell, respectively. Furthermore, cAMP-induced c-fos expression induced by forskolin is formerly shown to be independent of PKC down-regulation. In our experiments, forskolin induced c-fos expression in both clones. However, PKC down-regulation inhibited the forskolin-induced c-fos expression in Cl 16 cells. This apparently demonstrates cross talk between PKC and PKA in the c-fos induction pathway. The present results provide evidence for an impaired mechanism for activating c-fos expression through PKC-independent, PDGF-induced signal transduction in the chemically transformed Cl 16 fibroblasts compared to that in nontransformed 10T1/2 cells.

Protective Effect of Hibiscus Sabdariffa on Doxorubicin-induced Cytotoxicity in H9c2 Cardiomyoblast Cells.

Science.gov (United States)

Hosseini, Azar; Bakhtiari, Elham; Mousavi, Seyed Hadi

2017-01-01

Doxorubicin (DOX) is an effective anticancer drug. But its clinical application is limited, because DOX induces apoptosis in cardiomyocytes and it leads to permanent degenerative cardiomyopathy and heart failure. Recent trainings showed that Hibiscus sabdariffa exhibit pharmacological actions such as potent antioxidant. So, in this study we explored the protective effect of H. sabdariffa extract on doxorubicin-induced cytotoxicity in H9c2 cells. Cell viability was quantified by MTT assay. Apoptotic cells were determined using PI staining of DNA fragmentation by flowcytometry (sub-G1 peak). Cells were cultured with 5 μM DOX for 24 h to create the cell damage. H9c2 cells were pretreated with different concentrations (7.81-500 μg/mL) of H. sabdariffa extract (HSE) for 2 h before DOX treatment in all trials. Pretreatment with HSE increased cell viability at concentration of 31.25-500 μg/mL. Compared to control cells, apoptosis was induced in DOX treated cells after 24 h, (sabdariffa could exert the cardioprotective effects on DOX-induced toxicity partly by antiapoptotic activity.

Scintigraphic imaging with 99mTc- exorphin C in rabbits

International Nuclear Information System (INIS)

Ertay, T.; Uenak, P.; Tasci, C.; Zihnioglu, F.; Durak, H.

2005-01-01

Exorphin C is a peptide with five amino acids [(Tyr-Pro-Ile-Ser-Leu) Trifluoroacetate salt] (Sigma) that has an affinity to opioid receptor-expressing tissues and tumors. Exorphin-C was labeled with 99m Tc using glucoheptonate (GH) as bifunctional chelating agent. Then, we investigated its radiopharmaceutical potential as opioid receptor-expressing tissue on rabbits. Quality controls were performed by ITLC, paper electrophoresis and HPLC. Labeling efficiency was higher than 98%. The compound was stable for at least 5 h at room temperature. Scintigraphic imaging with 99m Tc-GH-exorphin C ( 99m Tc-GE) was performed on male Albino rabbits. Static images were obtained from anterior projection using a Camstar XR/T gamma camera at several time intervals. Although a significant amount of activity was seen in the brain, less activity was seen on receptor saturation studies at 30 min. Slight hepatobiliary excretion was seen, though the main excretion route was renal. After saturating, the receptor hepatobiliary excretion was not seen; the only excretion route was renal

Preparation and comparison of a-C:H coatings using reactive sputter techniques

Energy Technology Data Exchange (ETDEWEB)

Keunecke, M., E-mail: martin.keunecke@ist.fraunhofer.d [Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig (Germany); Weigel, K.; Bewilogua, K. [Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig (Germany); Cremer, R.; Fuss, H.-G. [CemeCon AG, Wuerselen (Germany)

2009-12-31

Amorphous hydrogenated carbon (a-C:H) coatings are widely used in several industrial applications. These coatings commonly will be prepared by plasma activated chemical vapor deposition (PACVD). The main method used to prepare a-C:H coating in industrial scale is based on a glow discharge in a hydrocarbon gas like acetylene or methane using a substrate electrode powered with medium frequency (m.f. - some 10 to 300 kHz). Some aims of further development are adhesion improvement, increase of hardness and high coating quality on complex geometries. A relatively new and promising technique to fulfil these requirements is the deposition of a-C:H coatings by a reactive d.c. magnetron sputter deposition from a graphite target with acetylene as reactive gas. An advancement of this technique is the deposition in a pulsed magnetron sputter process. Using these three mentioned techniques a-C:H coatings were prepared in the same deposition machine. For adhesion improvement different interlayer systems were applied. The effect of different substrate bias voltages (d.c. and d.c. pulse) was investigated. By applying the magnetron sputter technique in the d.c. pulse mode, plastic hardness values up to 40 GPa could be reached. Besides hardness other mechanical properties like resistance against abrasive wear were measured and compared. Cross sectional SEM images showed the growth structure of the coatings.

Thermoelectric properties of the 3C, 2H, 4H, and 6H polytypes of the wide-band-gap semiconductors SiC, GaN, and ZnO

Directory of Open Access Journals (Sweden)

Zheng Huang

2015-09-01

Full Text Available We have investigated the thermoelectric properties of the 3C, 2H, 4H, and 6H polytypes of the wide-band-gap(n-type semiconductors SiC, GaN, and ZnO based on first-principles calculations and Boltzmann transport theory. Our results show that the thermoelectric performance increases from 3C to 6H, 4H, and 2H structures with an increase of hexagonality for SiC. However, for GaN and ZnO, their power factors show a very weak dependence on the polytype. Detailed analysis of the thermoelectric properties with respect to temperature and carrier concentration of 4H-SiC, 2H-GaN, and 2H-ZnO shows that the figure of merit of these three compounds increases with temperature, indicating the promising potential applications of these thermoelectric materials at high temperature. The significant difference of the polytype-dependent thermoelectric properties among SiC, GaN, and ZnO might be related to the competition between covalency and ionicity in these semiconductors. Our calculations may provide a new way to enhance the thermoelectric properties of wide-band-gap semiconductors through atomic structure design, especially hexagonality design for SiC.

Anomalous temperature dependence of H{sub c2} in BiSrCuO

Energy Technology Data Exchange (ETDEWEB)

Broto, J.M. [Service National Des Champs Magnetiques Pulses, 31077 Toulouse Cedex (France); Rakoto, H. [Service National Des Champs Magnetiques Pulses, 31077 Toulouse Cedex (France); Ousset, J.C. [Service National Des Champs Magnetiques Pulses, 31077 Toulouse Cedex (France); Coffe, G. [Service National Des Champs Magnetiques Pulses, 31077 Toulouse Cedex (France); Askenazy, S. [Service National Des Champs Magnetiques Pulses, 31077 Toulouse Cedex (France); Osofsky, M.S. [Naval Research Laboratory, Washington, DC 20375-5000 (United States); Soulen, R.J. Jr. [Naval Research Laboratory, Washington, DC 20375-5000 (United States); Wolf, S.A. [Naval Research Laboratory, Washington, DC 20375-5000 (United States); Pari, P. [Centre d`Etudes de Saclay, Service de Physique de l`Etat Condense, Laboratoire des Basses Temperatures, 91191 Gif-sur-Yvette (France); Bozovic, I. [Edward L. Ginzton Research Center, Varian Associates, Palo Alto, CA 94304-1025 (United States); Eckstein, J.N. [Edward L. Ginzton Research Center, Varian Associates, Palo Alto, CA 94304-1025 (United States); Virshup, G.F. [Edward L. Ginzton Research Center, Varian Associates, Palo Alto, CA 94304-1025 (United States)

1995-05-01

H{sub c2}(T) has been measured for thin BSCO films at temperatures down to 65 mK and pulsed fields up to 35 T. H{sub c2}(T) diverged anomalously as the temperature decreased: at the lowest temperature, it was five times that expected for a conventional superconductor. Although deviations from the conventional behavior have been observed in other superconductors, such strong divergence over such a large range of reduced temperature has not been seen before. (orig.).

Vitamin C and sodium bicarbonate enhance the antioxidant ability of H9C2 cells and induce HSPs to relieve heat stress.

Science.gov (United States)

Yin, Bin; Tang, Shu; Sun, Jiarui; Zhang, Xiaohui; Xu, Jiao; Di, Liangjiao; Li, Zhihong; Hu, Yurong; Bao, Endong

2018-02-13

Heat stress is exacerbated by global warming and affects human and animal health, leading to heart damage caused by imbalances in reactive oxygen species (ROS) and the antioxidant system, acid-base chemistry, electrolytes and respiratory alkalosis. Vitamin C scavenges excess ROS, and sodium bicarbonate maintains acid-base and electrolyte balance, and alleviates respiratory alkalosis. Herein, we explored the ability of vitamin C alone and in combination with equimolar sodium bicarbonate (Vitamin C-Na) to stimulate endogenous antioxidants and heat shock proteins (HSPs) to relieve heat stress in H9C2 cells. Control, vitamin C (20 μg/ml vitamin C for 16 h) and vitamin C-Na (20 μg/ml vitamin C-Na for 16 h) groups were heat-stressed for 1, 3 or 5 h. Granular and vacuolar degeneration, karyopyknosis and damage to nuclei and mitochondria were clearly reduced in treatment groups, as were apoptosis, lactate dehydrogenase activity and ROS and malondialdehyde levels, while superoxide dismutase activity was increased. Additionally, CRYAB, Hsp27, Hsp60 and Hsp70 mRNA levels were upregulated at 3 h (p < 0.01), and protein levels were increased for CRYAB at 0 h (p < 0.05) and 1 h (p < 0.01), and for Hsp70 at 3 and 5 h (p < 0.01). Thus, pre-treatment with vitamin C or vitamin C-Na might protect H9C2 cells against heat damage by enhancing the antioxidant ability and upregulating CRYAB and Hsp70.

Um estudo teórico de propriedades moleculares em complexos de hidrogênio trimoleculares C2H4···2HF, C2H2···2HF e C3h6···2HF A theoretical study of molecular properties of C2H4···2HF, C2H2···2HF AND C3H6···2HF trimolecular hydrogen-bonded complexes

Directory of Open Access Journals (Sweden)

Boaz G. Oliveira

2008-01-01

Full Text Available We present a theoretical study of molecular properties in C2H4···2HF, C2H2···2HF and C3H6···2HF trimolecular hydrogen-bonded complexes. From B3LYP/6-311++G(d,p calculations, the most important structural deformations are related to the C=C (C2H4, C≡C (C2H2, C-C (C3H6 and HF bond lengths. According to the Bader's atoms in molecules and CHELPG calculations, it was identified a tertiary interaction between the fluorine atom of the second hydrofluoric acid molecule and hydrogen atoms of the ethylene and acetylene within the C2H4···2HF and C2H2···2HF complexes, respectively. Additionally, the evaluation of the infrared spectrum characterized the new vibrational modes and bathochromic effect of the HF molecules.

Isotope effects and their implications for the covalent binding of inhaled [3H]- and [14C]formaldehyde in the rat nasal mucosa

International Nuclear Information System (INIS)

Heck Hd'; Casanova, M.

1987-01-01

DNA-protein crosslinks were formed in the nasal respiratory mucosa of Fischer-344 rats exposed for 3 hr to selected concentrations of [ 3 H]- and [ 14 C]formaldehyde ( 3 HCHO and H 14 CHO). In rats depleted of glutathione (GSH) and exposed to 10 ppm of 3 HCHO and H 14 CHO, the 3 H/ 14 C ratio of the fraction of the DNA that was crosslinked to proteins was significantly (39 +/- 6%) higher than that of the inhaled gas. This suggests an isotope effect, either on the formation of DNA-protein crosslinks by labeled HCHO or on the oxidation of labeled HCHO catalyzed by formaldehyde (FDH) or aldehyde dehydrogenase (AldDH). The possibility of an isotope effect on the formation of crosslinks was investigated using rat hepatic nuclei incubated with [ 3 H]- and [ 14 C]formaldehyde (0.1 mM, 37 degrees C). A small (3.4 +/- 0.9%) isotope effect was detected on this reaction, which slightly favored 3 HCHO over H 14 CHO in binding to DNA. The magnitude of this isotope effect cannot account for the high isotope ratio observed in the crosslinked DNA in vivo. The possibility of an isotope effect on the oxidation of 3 HCHO and H 14 CHO catalyzed by FDH was investigated using homogenates of the rat nasal mucosa incubated with [ 3 H]- and [ 14 C]formaldehyde at total formaldehyde concentrations ranging from 0.1 to 11 microM, NAD+ (1 mM), GSH (15 mM), and pyrazole (1 mM). The experiments showed that 3 HCHO is oxidized significantly more slowly than H 14 CHO under these conditions (Vmax/Km (H 14 CHO) divided by Vmax/Km ( 3 HCHO) = 1.82 +/- 0.11). A similar isotope effect was observed in the absence of GSH, presumably due to the oxidation of 3 HCHO and H 14 CHO catalyzed by AldDH

The protective effect of lycopene on hypoxia/reoxygenation-induced endoplasmic reticulum stress in H9C2 cardiomyocytes.

Science.gov (United States)

Gao, Yang; Jia, Pengyu; Shu, WenQi; Jia, Dalin

2016-03-05

Nowadays, drugs protecting ischemia/reperfusion (I/R) myocardium become more suitable for clinic. It has been confirmed lycopene has various protections, but lacking the observation of its effect on endoplasmic reticulum stress (ERS)-mediated apoptosis caused by hypoxia/reoxygenation (H/R). This study aims to clarify the protective effect of lycopene on ERS induced by H/R in H9C2 cardiomyocytes. Detect the survival rate, lactic dehydrogenase (LDH) activity, apoptosis ratio, glucose-regulated proteins 78 (GRP78), C/EBP homologous protein (CHOP), c-Jun-N-terminal protein Kinase (JNK) and Caspase-12 mRNA and protein expression and phosphorylation of JNK (p-JNK) protein expression. LDH activity, apoptosis ratio and GRP78 protein expression increase in the H/R group, reduced by lycopene. The survival rate reduces in the H/R and thapsigargin (TG) groups; lycopene and 4-phenyl butyric acid (4-PBA) can improve it caused by H/R, lycopene also can improve it caused by TG. The apoptosis ratio, the expression of GRP78, CHOP and Caspase-12 mRNA and protein and p-JNK protein increase in the H/R and TG groups, weaken in the lycopene+H/R, 4-PBA+H/R and lycopene+TG groups. There is no obvious change in the expression of JNK mRNA or protein. Hence, our results provide the evidence that 10 μM lycopene plays an obviously protective effect on H/R H9C2 cardiomyocytes, realized through reducing ERS and apoptosis. The possible mechanism may be related to CHOP, p-JNK and Caspase-12 pathways. Copyright © 2016. Published by Elsevier B.V.

Advanced TiC/a-C : H nanocomposite coatings deposited by magnetron sputtering

NARCIS (Netherlands)

Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De; Strondl, C.

2006-01-01

TiC/a-C:H nanocomposite coatings have been deposited by magnetron Sputtering. They consist of 2-5 nm TiC nanocrystallites embedded in the amorphous hydrocarbon (a-C:H) matrix. A transition from a Columnar to a glassy microstructure has been observed in the nanocomposite coatings with increasing

Lectures given at the C.I.M.E. Summer School

CERN Document Server

Zannier, Umberto

2003-01-01

The C.I.M.E. session in Diophantine Approximation, held in Cetraro (Italy) June 28 - July 6, 2000 focused on height theory, linear independence and transcendence in group varieties, Baker's method, approximations to algebraic numbers and applications to polynomial-exponential diophantine equations and to diophantine theory of linear recurrences. Very fine lectures by D. Masser, Y. Nesterenko, H.-P. Schlickewei, W.M. Schmidt and M. Waldschmidt have resulted giving a good overview of these topics, and describing central results, both classical and recent, emphasizing the new methods and ideas of the proofs rather than the details. They are addressed to a wide audience and do not require any prior specific knowledge.

Characterization of the human pH- and PKA-activated ClC-2G(2 alpha) Cl- channel.

Science.gov (United States)

Sherry, A M; Stroffekova, K; Knapp, L M; Kupert, E Y; Cuppoletti, J; Malinowska, D H

1997-08-01

A ClC-2G(2 alpha) Cl- channel was identified to be present in human lung and stomach, and a partial cDNA for this Cl- channel was cloned from a human fetal lung library. A full-length expressible human ClC-2G(2 alpha) cDNA was constructed by ligation of mutagenized expressible rabbit ClC-2G(2 alpha) cDNA with the human lung ClC-2G(2 alpha) cDNA, expressed in oocytes, and characterized at the single-channel level. Adenosine 3',5'-cyclic monophosphate-dependent protein kinase (PKA) treatment increased the probability of opening of the channel (Po). After PKA activation, the channel exhibited a linear (r = 0.99) current-voltage curve with a slope conductance of 22.1 +/- 0.8 pS in symmetric 800 mM tetraethylammonium chloride (TEACl; pH 7.4). Under fivefold gradient conditions of TEACl, a reversal potential of +21.5 +/- 2.8 mV was measured demonstrating anion-to-cation discrimination. As previously demonstrated for the rabbit ClC-2G(2 alpha) Cl- channel, the human analog, hClC-2G(2 alpha), was active at pH 7.4 as well as when the pH of the extracellular face of the channel (trans side of the bilayer; pHtrans) was asymmetrically reduced to pH 3.0. The extent of PKA activation was dependent on pHtrans. With PKA treatment, Po increased fourfold with a pHtrans of 7.4 and eightfold with a pHtrans of 3.0. Effects of sequential PKA addition followed by pHtrans reduction on the same channel suggested that the PKA- and pH-dependent increases in channel Po were separable and cumulative. Northern analysis showed ClC-2G(2 alpha) mRNA to be present in human adult and fetal lung and adult stomach, and quantitative reverse transcriptase-polymerase chain reaction showed this channel to be present in the adult human lung and stomach at about one-half the level found in fetal lung. The findings of the present study suggest that the ClC-2G(2 alpha) Cl- channel may play an important role in Cl- transport in the fetal and adult human lung.

Growth of Ba-hexaferrite films on single crystal 6-H SiC

International Nuclear Information System (INIS)

Chen Zhoahui; Yang, Aria; Yoon, S.D.; Ziemer, Katherine; Vittoria, Carmine; Harris, V.G.

2006-01-01

Barium hexaferrite films have been processed by pulsed laser deposition on single crystal 6-H silicon carbide substrates. Atomic force microscopy images show hexagonal crystals (∼0.5μm in diameter) oriented with the c-axis perpendicular to the film plane. X-ray θ-2θ diffraction measurements indicate a strong (0,0,2n) alignment of crystallites. The magnetization for low-pressure deposition (20mTorr) is comparable to bulk values (4πM s ∼4320G). The loop squareness, important for self-bias microwave device applications, increases with oxygen pressure reaching a maximum value of 70%. This marks the first growth of a microwave ferrite on SiC substrates and offers a new approach in the design and development of μ-wave and mm-wave monolithic integrated circuits. c integrated circuits

Catalyst- and Reagent-free Electrochemical Azole C-H Amination.

Science.gov (United States)

Qiu, Youai; Struwe, Julia; Meyer, Tjark H; Oliveira, Joao Carlos Agostinho Carlos Agostinho; Ackermann, Lutz

2018-06-14

Catalyst-, and chemical oxidant-free electrochemical azole C-H aminations were accomplished via cross-dehydrogenative C-H/N-H functionalization. The catalyst-free electrochemical C-H amination proved feasible on azoles with high levels of efficacy and selectivity, avoiding the use of stoichiometric oxidants under ambient conditions. Likewise, the C(sp3)-H nitrogenation proved viable under otherwise identical conditions. The dehydrogenative C-H amination featured ample scope, including cyclic and acyclic aliphatic amines as well as anilines, and employed sustainable electricity as the sole oxidant. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

H2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodes

KAUST Repository

Ahmed, Bilal

2016-03-08

Herein we demonstrate that a prominent member of the MXene family, Ti2C, undergoes surface oxidation at room temperature when treated with hydrogen peroxide (H2O2). The H2O2 treatment results in opening up of MXene sheets and formation of TiO2 nanocrystals on their surface, which is evidenced by the high surface area of H2O2 treated MXene and X-ray diffraction (XRD) analysis. We show that the reaction time and the amount of hydrogen peroxide used are the limiting factors, which determine the morphology and composition of the final product. Furthermore, it is shown that the performance of H2O2 treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepared MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g−1, 337 mA h g−1 and 297 mA h g−1 were obtained for H2O2 treated MXene at current densities of 100 mA g−1, 500 mA g−1 and 1000 mA g−1, respectively. In addition, when tested at a very high current density, such as 5000 mA g−1, the H2O2 treated MXene showed a specific capacity of 150 mA h g−1 and excellent rate capability. These results clearly demonstrate that H2O2 treatment of Ti2C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.

H2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodes

KAUST Repository

Ahmed, Bilal; Anjum, Dalaver H.; Hedhili, Mohamed N.; Gogotsi, Yury; Alshareef, Husam N.

2016-01-01

Herein we demonstrate that a prominent member of the MXene family, Ti2C, undergoes surface oxidation at room temperature when treated with hydrogen peroxide (H2O2). The H2O2 treatment results in opening up of MXene sheets and formation of TiO2 nanocrystals on their surface, which is evidenced by the high surface area of H2O2 treated MXene and X-ray diffraction (XRD) analysis. We show that the reaction time and the amount of hydrogen peroxide used are the limiting factors, which determine the morphology and composition of the final product. Furthermore, it is shown that the performance of H2O2 treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepared MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g−1, 337 mA h g−1 and 297 mA h g−1 were obtained for H2O2 treated MXene at current densities of 100 mA g−1, 500 mA g−1 and 1000 mA g−1, respectively. In addition, when tested at a very high current density, such as 5000 mA g−1, the H2O2 treated MXene showed a specific capacity of 150 mA h g−1 and excellent rate capability. These results clearly demonstrate that H2O2 treatment of Ti2C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.

Pharmacokinetics of enrofloxacin HCl-2H2O (ENRO-C) in dogs and PK/PD Monte Carlo simulations against Leptospira sp.

Science.gov (United States)

Sumano, Hector; Ocampo, Luis; Tapia, Graciela; Mendoza, C de Jesus; Gutierrez, Lilia

2018-04-12

Pharmacokinetics/pharmacodynamics (PK/PD) ratios of reference enrofloxacin (Enro-R) and enrofloxacin as HCl-2H 2 O (Enro-C), as well as Monte Carlo simulations based on composite MIC 50 and MIC 90 vs. Leptospira sp., were carried out in dogs after their IM and oral administration (10 mg/kg). Plasma determination of enrofloxacin was achieved by means of high performance liquid chromatography (HPLC). Maximum plasma concentration values after oral administration were 1.47 ± 0.19 µg/mL and 5.3 ± 0.84 µg/mL for Enro-R and Enro-C, respectively, and 1.6 ± 0.12 µg/mL and 7.6 ± 0.93 µg/mL after IM administration. Area under the plasma vs. time concentrations in 24 h (AUC 0-24 ) were 8.02 µg/mL/h and 36.2 µg/mL/h for Enro-R oral and Enro-C oral , respectively, and 8.55 ± 0.85 µg/mL/h and 56.4 ± 6.21 µg/mL/h after IM administration of these drugs. Only PK/PD ratios and Monte Carlo simulations obtained with Enro-C, anticipate that its IM administration to dogs will result in therapeutic concentrations to treat leptospirosis. This is the first time enrofloxacin has been recommended to treat this disease in dogs.

Two new two-dimensional organically templated phosphite compounds: (C6H16N2)0.5[M(HPO3)F], M=Fe(II) and Co(II): Solvothermal synthesis, crystal structures, thermal, spectroscopic, and magnetic properties

International Nuclear Information System (INIS)

Fernandez-Armas, Sergio; Mesa, Jose L.; Pizarro, Jose L.; Chung, U-Chan; Arriortua, Maria I.; Rojo, Teofilo

2005-01-01

The organically templated (C 6 H 16 N 2 ) 0.5 [M(HPO 3 )F] [M(II)=Fe (1) and Co (2)] compounds have been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds are isostructural and crystallize in the C2/c monoclinic space group. The unit-cell parameters are a=5.607(1), b=21.276(4), c=11.652(1)A, β=93.74(1) deg. for the iron phase and a=5.5822(7), b=21.325(3), c=11.4910(1)A, β=93.464(9) o for the cobalt compound with Z=4. The crystal structure of these compounds consists of [M(HPO 3 )F] - anionic sheets. The layers are constructed from chains which contain [M 2 O 6 F 3 ] dimeric units linked by fluoride ions. The trans-1,4-diaminocyclohexane cations are placed in the interlayer space. The IR and Raman spectra show the bands corresponding to the phosphite oxoanion and organic dication. The Dq and Racah (B and C) parameters have been calculated from the diffuse reflectance spectra in the visible region. Dq parameter is 790cm -1 for compound (1). For phase (2) the Dq value is 725cm -1 and B and C are 930 and 4100cm -1 , respectively. The thermal evolution of the molar magnetic susceptibilities of these compounds show maxima at 20.0 and 6.0K for the iron(II) and cobalt(II) phases, respectively. These results indicate the existence of antiferromagnetic interactions in both compounds

Genome-Wide Mapping of 5mC and 5hmC Identified Differentially Modified Genomic Regions in Late-Onset Severe Preeclampsia: A Pilot Study.

Directory of Open Access Journals (Sweden)

Lisha Zhu

Full Text Available Preeclampsia (PE is a leading cause of perinatal morbidity and mortality. However, as a common form of PE, the etiology of late-onset PE is elusive. We analyzed 5-methylcytosine (5mC and 5-hydroxymethylcytosine (5hmC levels in the placentas of late-onset severe PE patients (n = 4 and normal controls (n = 4 using a (hydroxymethylated DNA immunoprecipitation approach combined with deep sequencing ([h]MeDIP-seq, and the results were verified by (hMeDIP-qPCR. The most significant differentially methylated regions (DMRs were verified by MassARRAY EppiTYPER in an enlarged sample size (n = 20. Bioinformatics analysis identified 714 peaks of 5mC that were associated with 403 genes and 119 peaks of 5hmC that were associated with 61 genes, thus showing significant differences between the PE patients and the controls (>2-fold, p<0.05. Further, only one gene, PTPRN2, had both 5mC and 5hmC changes in patients. The ErbB signaling pathway was enriched in those 403 genes that had significantly different 5mC level between the groups. This genome-wide mapping of 5mC and 5hmC in late-onset severe PE and normal controls demonstrates that both 5mC and 5hmC play epigenetic roles in the regulation of the disease, but work independently. We reveal the genome-wide mapping of DNA methylation and DNA hydroxymethylation in late-onset PE placentas for the first time, and the identified ErbB signaling pathway and the gene PTPRN2 may be relevant to the epigenetic pathogenesis of late-onset PE.

Circadian and longitudinal variation of serum C-telopeptide, osteocalcin, and skeletal alkaline phosphatase in C3H/HeJ mice.

Science.gov (United States)

Srivastava, A K; Bhattacharyya, S; Li, X; Mohan, S; Baylink, D J

2001-10-01

Inbred strains of mice are increasingly being used as an animal model to investigate skeletal disorders relevant to humans. In the bone field, one of the most convenient endpoints for evaluating genetic, physiological, or pharmaceutical perturbations is the use of biochemical markers. To apply biochemical markers in an effective manner, it is of key importance to establish the biological variation and appropriate sampling time. In this study, we evaluate two components: (i) circadian changes, and (ii) longitudinal variation for three serum markers, osteocalcin, C-telopeptide, and skeletal alkaline phosphatase (sALP), using 6-week-old C3H/HeJ (C3H) mice. To study circadian rhythms, the mice were randomly divided into eight groups of 15 mice each. Blood was collected at 3 h intervals, starting at 9:00 A.M. and continuing until 6:00 A.M. the next day. To determine whether circadian rhythm is intrinsically regulated or influenced by restricted food intake, it was also studied after a 12 h fasting period. Serum osteocalcin and C-telopeptide levels were measured by enzyme-linked immunoassay (ELISA) and skeletal alkaline phosphatase by a kinetic assay. The results demonstrated significant circadian variations in osteocalcin and C-telopeptide levels with a peak value between 0900 and 1200 h during daytime and a nadir between 15:00 and 18:00 h. The peak levels of C-telopeptide and osteocalcin were 26%-66% higher as compared with 24 h mean values. The pattern of the circadian variation of C-telopeptide and osteocalcin was similar in female and male animals and was not significantly affected by restricted food intake. The sALP levels were only marginally affected by the circadian rhythm. Longitudinal variations, expressed as coefficient of variation (CV), for osteocalcin, C-telopeptide, and sALP concentrations were 17%, 14%, and 16%, respectively. In addition, the longitudinal variations were not significantly influenced by the time of blood collection in sALP and osteocalcin

A determination of m_c(m_c) from HERA data using a matched heavy-flavor scheme

International Nuclear Information System (INIS)

Bertone, Valerio; Cooper-Sarkar, Amanda

2016-05-01

The charm quark mass is one of the fundamental parameters of the Standard Model Lagrangian. In this work we present a determination of the MS charm mass from a fit to the inclusive and charm HERA deep-inelastic structure function data. The analysis is performed within the xFitter framework, with structure functions computed in the FONLL general-mass scheme as implemented in APFEL. In the case of the FONLL-C scheme, we obtain m_c(m_c)=1.335±0.043(exp)"+"0"."0"1"9_-_0_._0_0_0(param)"+"0"."0"1"1_-_0_._0_0_8(mod)"+"0"."0"3"3_-_0_._0_0_8(th) GeV. We also perform an analogous determination in the fixed-flavor-number scheme at next-to-leading order, finding m_c(m_c)=1.318 ± 0.054(exp)"+"0"."0"1"1_-_0_._0_1_0(param)"+"0"."0"1"5_-_0_._0_1_9(mod)"+"0"."0"4 "5_-_0_._0_0_4(th) GeV, compatible with the FONLL-C value. Our results are consistent with previous determinations from DIS data as well as with the PDG world average.

Ir-catalyzed C-H silylations of phenyldeazapurines

Czech Academy of Sciences Publication Activity Database

Sabat, Nazarii; Poštová Slavětínská, Lenka; Hocek, Michal

2015-01-01

Roč. 56, č. 49 (2015), s. 6860-6862 ISSN 0040-4039 Institutional support: RVO:61388963 Keywords : C-H silylation * deazapurines * iridium catalysis * C-H activations Subject RIV: CC - Organic Chemistry Impact factor: 2.347, year: 2015

Hydrogen behaviour study in plasma facing a-C:H and a-SiC:H hydrogenated amorphous materials for fusion reactors

International Nuclear Information System (INIS)

Barbier, Gauzelin

1997-01-01

Plasma facing components of controlled fusion test devices (tokamaks) are submitted to several constraints (irradiation, high temperatures). The erosion (physical sputtering and chemical erosion) and the hydrogen recycling (retention and desorption) of these materials influence many plasma parameters and thus affect drastically the tokamak running. Firstly, we will describe the different plasma-material interactions. It will be pointed out, how erosion and hydrogen recycling are strongly related to both chemical and physical properties of the material. In order to reduce this interactions, we have selected two amorphous hydrogenated materials (a-C:H and a-SiC:H), which are known for their good thermal and chemical qualities. Some samples have been then implanted with lithium ions at different fluences. Our materials have been then irradiated with deuterium ions at low energy. From our results, it is shown that both the lithium implantation and the use of an a-SiC:H substrate can be benefit in enhancing the hydrogen retention. These results were completed with thermal desorption studies of these materials. It was evidenced that the hydrogen fixation was more efficient in a -SiC:H than in a-C:H substrate. Results in good agreement with those described above have been obtained by exposing a-C:H and a-SiC:H samples to the scrape off layer of the tokamak of Varennes (TdeV, Canada). A modeling of hydrogen diffusion under irradiation has been also proposed. (author)

General allylic C-H alkylation with tertiary nucleophiles.

Science.gov (United States)

Howell, Jennifer M; Liu, Wei; Young, Andrew J; White, M Christina

2014-04-16

A general method for intermolecular allylic C-H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C-H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C-H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C-H reactivity are illustrated in an allylic C-H alkylation/Diels-Alder reaction cascade: a reactive diene is generated via intermolecular allylic C-H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids.

Computational Material Modeling of Hydrated Cement Paste Calcium Silicate Hydrate (C-S-H) Chemistry Structure - Influence of Magnesium Exchange on Mechanical Stiffness: C-S-H Jennite

Science.gov (United States)

2015-04-27

MODELING OF C-S-H Material chemistry level modeling following the principles and techniques commonly grouped under Computational Material Science is...Henmi, C. and Kusachi, I. Monoclinic tobermorite from fuka, bitchu-cho, Okoyama Perfecture. Japan J. Min. Petr. Econ . Geol. (1989)84:374-379. [22...31] Liu, Y. et al. First principles study of the stability and mechanical properties of MC (M=Ti, V, Zr, Nb, Hf and Ta) compounds. Journal of Alloys and Compounds. (2014) 582:500-504. 10

A FORMAÇÃO DE LIGAÇÕES DE HIDROGÊNIO π‧‧‧H, F‧‧‧H E C‧‧‧H NOS COMPLEXOS C2H2‧‧‧(HF, C2H2‧‧‧2(HF E C2H2‧‧‧3(HF

Directory of Open Access Journals (Sweden)

Boaz G. Oliveira

2016-04-01

Full Text Available In this work, a theoretical study on the basis of structural, vibrational, electronic and topological parameters of the C2H2‧‧‧(HF, C2H2‧‧‧2(HF and C2H2‧‧‧3(HF complexes concerning the formation of π‧‧‧H, F‧‧‧H and C‧‧‧H hydrogen bonds is presented. The main difference among these complexes is not properly the interaction strength, but the hydrogen bond type whose benchmark is ruled justly by the structure. Meanwhile, the occurrence of π‧‧‧H hydrogen bonds was unveiled in both C2H2‧‧‧(HF dimer and C2H2‧‧‧3(HF tetramer, although in latter, this interaction is stronger than C‧‧‧H of the C2H2‧‧‧2(HF trimer. However, the F‧‧‧H hydrogen bonds within the subunits of hydrofluoric acid are the strongest ones, reaching a partial covalent limit, and thereby contribute decisively to the stabilization of the tetramer structure. In line with this, the largest red-shifts were observed on the hydrofluoric acid trimer of the C2H2‧‧‧3(HF complex.

The Precipitation Products Generation Chain for the EUMETSAT Hydrological Satellite Application Facility at C.N.M.C.A.

Science.gov (United States)

Zauli, Francesco; Biron, Daniele; Melfi, Davide

2009-11-01

The EUMETSA T Satellite Application Facility in support to Hydrology (H-SAF) focuses on the development of new geophysical products on precipitation, soil moisture and snow parameters and the utilisation of these parameters in hydrological models, NWP models and water management. The development phase of the H-SAF started in September 2005 under the leadership of Italian Meteorological Service.The Centro Nazionale di Meteorologia e Climatologia Aeronautica (C.N.M.C.A.), the Italian National Weather Centre, that physically hosts the generation chain of precipitation products, developed activities to reach the final target: development of algorithms, validation of results, implementation of operative procedure to supply the service and to monitor the service performances.The paper shows the recent architectural review of H- SAF precipitation group, stressing components of operation for high sustainability, full redundancy, absolute continuity of service.

Stringent DDI-based prediction of H. sapiens-M. tuberculosis H37Rv protein-protein interactions.

Science.gov (United States)

Zhou, Hufeng; Rezaei, Javad; Hugo, Willy; Gao, Shangzhi; Jin, Jingjing; Fan, Mengyuan; Yong, Chern-Han; Wozniak, Michal; Wong, Limsoon

2013-01-01

H. sapiens-M. tuberculosis H37Rv protein-protein interaction (PPI) data are very important information to illuminate the infection mechanism of M. tuberculosis H37Rv. But current H. sapiens-M. tuberculosis H37Rv PPI data are very scarce. This seriously limits the study of the interaction between this important pathogen and its host H. sapiens. Computational prediction of H. sapiens-M. tuberculosis H37Rv PPIs is an important strategy to fill in the gap. Domain-domain interaction (DDI) based prediction is one of the frequently used computational approaches in predicting both intra-species and inter-species PPIs. However, the performance of DDI-based host-pathogen PPI prediction has been rather limited. We develop a stringent DDI-based prediction approach with emphasis on (i) differences between the specific domain sequences on annotated regions of proteins under the same domain ID and (ii) calculation of the interaction strength of predicted PPIs based on the interacting residues in their interaction interfaces. We compare our stringent DDI-based approach to a conventional DDI-based approach for predicting PPIs based on gold standard intra-species PPIs and coherent informative Gene Ontology terms assessment. The assessment results show that our stringent DDI-based approach achieves much better performance in predicting PPIs than the conventional approach. Using our stringent DDI-based approach, we have predicted a small set of reliable H. sapiens-M. tuberculosis H37Rv PPIs which could be very useful for a variety of related studies. We also analyze the H. sapiens-M. tuberculosis H37Rv PPIs predicted by our stringent DDI-based approach using cellular compartment distribution analysis, functional category enrichment analysis and pathway enrichment analysis. The analyses support the validity of our prediction result. Also, based on an analysis of the H. sapiens-M. tuberculosis H37Rv PPI network predicted by our stringent DDI-based approach, we have discovered some

Impaired ALDH2 activity decreases the mitochondrial respiration in H9C2 cardiomyocytes.

Science.gov (United States)

Mali, Vishal R; Deshpande, Mandar; Pan, Guodong; Thandavarayan, Rajarajan A; Palaniyandi, Suresh S

2016-02-01

Reactive oxygen species (ROS)-mediated reactive aldehydes induce cellular stress. In cardiovascular diseases such as ischemia-reperfusion injury, lipid-peroxidation derived reactive aldehydes such as 4-hydroxy-2-nonenal (4HNE) are known to contribute to the pathogenesis. 4HNE is involved in ROS formation, abnormal calcium handling and more importantly defective mitochondrial respiration. Aldehyde dehydrogenase (ALDH) superfamily contains NAD(P)(+)-dependent isozymes which can detoxify endogenous and exogenous aldehydes into non-toxic carboxylic acids. Therefore we hypothesize that 4HNE afflicts mitochondrial respiration and leads to cell death by impairing ALDH2 activity in cultured H9C2 cardiomyocyte cell lines. H9C2 cardiomyocytes were treated with 25, 50 and 75 μM 4HNE and its vehicle, ethanol as well as 25, 50 and 75 μM disulfiram (DSF), an inhibitor of ALDH2 and its vehicle (DMSO) for 4 h. 4HNE significantly decreased ALDH2 activity, ALDH2 protein levels, mitochondrial respiration and mitochondrial respiratory reserve capacity, and increased 4HNE adduct formation and cell death in cultured H9C2 cardiomyocytes. ALDH2 inhibition by DSF and ALDH2 siRNA attenuated ALDH2 activity besides reducing ALDH2 levels, mitochondrial respiration and mitochondrial respiratory reserve capacity and increased cell death. Our results indicate that ALDH2 impairment can lead to poor mitochondrial respiration and increased cell death in cultured H9C2 cardiomyocytes. Copyright © 2015 Elsevier Inc. All rights reserved.

Two Palladium-Catalyzed Domino Reactions from One Set of Substrates/Reagents: Efficient Synthesis of Substituted Indenes and cis-Stilbenoid Hydrocarbons from the Same Internal Alkynes and Hindered Grignard Reagents

Science.gov (United States)

Dong, Cheng-Guo; Yeung, Pik; Hu, Qiao-Sheng

2008-01-01

Two types of domino reactions from the same internal alkynes and hindered Grignard reagents based on carbopalladation, Pd-catalyzed cross-coupling reaction and C-H activation strategy are described. The realization of these domino reactions relied on the control of the use of the ligand and the reaction temperature. Our study provides an efficient access to useful polysubstituted indenes and cis-substituted stilbenes, and may offer new means to the development of tandem/domino reactions in a more efficient way. PMID:17217305

Low-temperature heat capacity of Al(C11H19O2)3

International Nuclear Information System (INIS)

Bespyatov, Michael A.; Chernyaikin, Ivan S.; Naumov, Viktor N.; Stabnikov, Pavel A.; Gelfond, Nikolay V.

2014-01-01

Highlights: • The temperature dependence of heat capacity of Al(C 11 H 19 O 2 ) 3 has been measured. • The experimental data were used to calculate standard thermodynamic functions. • The thermodynamic functions at 298.15 K are presented. - Abstract: The heat capacity of Al(C 11 H 19 O 2 ) 3 was measured by adiabatic-shield calorimetry in the temperature range 6–320 K; no transition or thermal anomalies were found. The thermodynamic functions (entropy, enthalpy, and reduced Gibbs free energy) at 298.15 K have been calculated using the obtained experimental heat capacity data. The obtained standard values are as follows: C° p,m = (882.3 ± 1.3) J mol −1 K −1 , Δ 0 298.15 S° m = J(980 ± 2) mol −1 K −1 , Δ 0 298.15 H° m = (145.1 ± 0.2) kJ mol −1 , Φ° m = (493.4 ± 1.7) J mol −1 K −1

PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis

Science.gov (United States)

Méndez-Lucas, Andrés; Duarte, João; Sunny, Nishanth E.; Satapati, Santhosh; He, TianTeng; Fu, Xiaorong; Bermúdez, Jordi; Burgess, Shawn C.; Perales, Jose C.

2013-01-01

Background & Aims Hepatic gluconeogenesis helps maintain systemic energy homeostasis by compensating for discontinuities in nutrient supply. Liver specific deletion of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) abolishes gluconeogenesis from mitochondrial substrates, deregulates lipid metabolism and affects TCA cycle. While, mouse liver almost exclusively expresses PEPCK-C, humans equally present a mitochondrial isozyme (PEPCK-M). Despite clear relevance to human physiology, the role of PEPCK-M and its gluconeogenic potential remain unknown. Here, we test the significance of PEPCK-M in gluconeogenesis and TCA cycle function in liver-specific PEPCK-C knockout and WT mice. Methods The effects of the overexpression of PEPCK-M were examined by a combination of tracer studies and molecular biology techniques. Partial PEPCK-C re-expression was used as a positive control. Metabolic fluxes were evaluated in isolated livers by NMR using 2H and 13C tracers. Gluconeogenic potential, together with metabolic profiling, were investigated in vivo and in primary hepatocytes. Results PEPCK-M expression partially rescued defects in lipid metabolism, gluconeogenesis and TCA cycle function impaired by PEPCK-C deletion, while ~10% re-expression of PEPCK-C normalized most parameters. When PEPCK-M was expressed in the presence of PEPCK-C, the mitochondrial isozyme amplified total gluconeogenic capacity, suggesting autonomous regulation of oxaloacetate to phosphoenolpyruvate fluxes by the individual isoforms. Conclusions We conclude that PEPCK-M has gluconeogenic potential per se, and cooperates with PEPCK-C to adjust gluconeogenic/TCA flux to changes in substrate or energy availability, hinting at a role in the regulation of glucose and lipid metabolism in human liver. PMID:23466304

The Legacy of Patient H.M. for Neuroscience

Science.gov (United States)

Squire, Larry R.

2009-01-01

H.M. is probably the best known single patient in the history of neuroscience. His severe memory impairment, which resulted from experimental neurosurgery to control seizures, was the subject of study for five decades until his death in December 2008. Work with H.M. established fundamental principles about how memory functions are organized in the brain. PMID:19146808

Polymeric anionic networks using dibromine as a crosslinker; the preparation and crystal structure of [(C4H9)4N]2[Pt2Br10].(Br2)7 and [(C4H9)4N]2[PtBr4Cl2].(Br2)6.

Science.gov (United States)

Berkei, Michael; Bickley, Jamie F; Heaton, Brian T; Steiner, Alexander

2002-09-21

The reaction of M[PtX3(CO)] (M+ = [(C4H9)4N]+, X = Br, Cl) with an excess of Br2 gives the new platinum(IV) salts, [(C4H9)4N]2[Pt2Br10].(Br2)7, 1, and [(C4H9)4N]2[PtBr4Cl2].(Br2)6, 2, which, in the solid state, contain strong Br Br interactions resulting in the formation of polymeric networks; they could provide useful solid storage reservoirs for elemental bromine.

Sodium chloride-citrate beverages attenuate hypovolemia in men resting 12 h at 2800 m altitude.

Science.gov (United States)

Greenleaf, J E; Farrell, P A; Loomis, J L; Fedele, M J; West, J; Rössler, A; Hinghofer-Szalkay, H

1998-10-01

The mechanism for reduction and restoration of total body water and plasma volume (PV) during initial exposure to acute altitude (ALT) is not clear but may involve involuntary dehydration; i.e., delayed voluntary fluid intake. Ten men (24 +/- SD 3 yr, 180.8 +/- 8.1 cm height, 78.8 +/- 12.8 kg weight, 1.99 +/- 0.19 m2 surface area, and 12.2 +/- 4.0% body fat) were in a semi-reclining position for 12 h in a chamber at 2800 m (539 mmHg) ALT or at 321 m (732 mmHg; ground). They ate a controlled breakfast (450 kcal + 3 ml x kg(-1) H2O) on the ground, and lunch and dinner at ALT (or on the ground) for a total daily intake of 2850 kcal (14% PRO, 67% CHO, 16% fat, 2.6g NaCl). At hour 10 they consumed fluid-electrolyte beverages or water (12 ml x kg(-1), 948 ml x d(-1)) in 4 sessions at weekly intervals. Beverage compositions were: a) 185 mEq x L(-1) Na+, 283 mOsm x kg(-1); b) 21.6 mEq x L(-1) Na+, 365 mOsm x kg(-1); c) water at ALT; and d) water on the ground. After 10 h at ALT % deltaPV (Hb-Hct) decreased (p < 0.05) by: a) 9.0 +/- SE 1.5%; b) 6.2 +/- 1.7%; c) 7.4 +/- 2.2%; and d) by 9.0 +/- 2.4%, respectively. After drinking from 1000-1030 h, PV at 1200 h changed by: a) +8.3 +/- SE 2.0% (p < 0.05); b) +2.8 +/- 2.7% (NS); c) -0.9 +/- 1.5% (NS); and d) by +0.8 +/- 3.5% (NS), respectively. The similar ground-induced hypovolemia suggests a response to confinement rather than an ALT effect and involuntary dehydration does not appear to be implicated. The significant increase in PV after consuming the (a) NaCl-NaCitrate beverage indicates that drink ionic composition appears to be more important than its osmolality for restoring PV in these conditions. Practical considerations: Because this hypovolemia was probably due to the confinement rather that reduced ambient pressure, appropriate countermeasures could be consumption of isotonic beverages, elastic stockings, leg exercise, and leg elevation.

Differential geometry the mathematical works of J. H. C. Whitehead

CERN Document Server

James, I M

1962-01-01

The Mathematical Works of J. H. C. Whitehead, Volume 1: Differential Geometry contains all of Whitehead's published work on differential geometry, along with some papers on algebras. Most of these were written in the period 1929-1937, but a few later articles are included. The book begins with a list of Whitehead's works, in chronological order of writing as well as a biographical note by M. H. A. Newman and Barbara Whitehead, and a mathematical appreciation by John Milnor. This is followed by separate chapters on topics such as linear connections; a method of obtaining normal representations

Photodissociation of C{sub 3}H{sub 5}Br and C{sub 4}H{sub 7}Br at 234 nm

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Kook; Paul, Dababrata; Hong, Ki Ryong; Cho, Ha Na; Kim, Tae Kyu [Pusan National University, Busan (Korea, Republic of); Lee, Kyoung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2012-01-15

The photodissociation dynamics of cyclopropyl bromide (C-3H{sub 5}Br) and cyclobutyl bromide (C{sub 4}H{sub 7}Br) at 234 nm was investigated. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br({sup 2}P{sub 3/2}) and Br*({sup 2}P{sub 1/2}) atoms. The recoil anisotropies for the Br and Br* channels were measured to be βBr = 0.92 ± 0.03 and βBr* = 1.52 ± 0.04 for C{sub 3}H{sub 5}Br and βBr = 1.10 ± 0.03 and βBr* = 1.49 ± 0.05 for C{sub 4}H{sub 7}Br. The relative quantum yield for Br was found to be ΦBr = 0.13 ± 0.03 and for C{sub 3}H{sub 5}Br and C{sub 4}H{sub 7}Br, respectively. The soft radical limit of the impulsive model adequately modeled the related energy partitioning. The nonadiabatic transition probability from the 3A' and 4A' potential energy surfaces was estimated and discussed.

Infrared spectroscopic investigation of M(H2PO4)2x2H2O (M=Mg, Mn, Cd) dehydration products

International Nuclear Information System (INIS)

Pechkovskij, V.V.; Dzyuba, E.D.; Mel'nikova, R.Ya.; Salonets, G.I.; Kovalishina, V.I.; Malashonok, I.E.

1982-01-01

Using the method of IR spectroscopy the composition of products separated at different stages of M(H 2 PO 4 ) 2 x2H 2 O dehydration, where M=Mg, Mn, Cd, has been investigated. It is shown that cation influence is expressed in strengthening of bond of proton-containing groups in the structure of initial compounds from magnesium to cadmium. A supposition is made that the difference in bond character of the groups more evidently expressed for partially dehydrated products of the composition M(H 2 PO 4 ) 2 , conditions a possibility of dehydration in two directions- with the formation of intermediate phase MH 2 P 2 O 7 or with separation of three phosphoric acid

Collective flows of protons and $\\pi^-$ mesons in $^{2}$H + C, Ta and He plus C, Ta collisions at 3.4 GeV/nucleon

CERN Document Server

Chkhaidze, L; Djobava, T; Kladnitskaya, E; Kharkhelauri, L; Uzhinsky, V

2011-01-01

Collective flows of protons and negative pions have been studied in (2)H + C, Ta and He + C, Ta collisions at an energy of 3.4 GeV/nucleon. The data have been obtained by the 2-m Propane Bubble Chamber (PBC-500) at JINR. It is found that the directed flow of protons and pi(-) mesons characterized by d /d(y) increases with increase of the mass numbers of colliding nucleus pairs; the elliptic proton flow points out of the reaction plane and also strengthens as the system mass increases; the negative pion directed flow is in the same reaction plane as the proton flow for the lighter (2H + C, He + C) systems and in the opposite direction for the heavier ((2)H + Ta, He + Ta) systems. In (2)H + C, He + C, C + C, C + Ne, (2)H + Ta, He + Ta, C + Cu, and C + Ta collisions, the linear dependence of directed and elliptic flow parameters from mass numbers of projectile and target nuclei, (A(P).A(T))(1/2), is similar for protons while for pi(-) mesons the dependence of directed flow parameters is stronger. The ultrarelati...

Conformation-induced remote meta-C-H activation of amines

Science.gov (United States)

Tang, Ri-Yuan; Li, Gang; Yu, Jin-Quan

2014-03-01

Achieving site selectivity in carbon-hydrogen (C-H) functionalization reactions is a long-standing challenge in organic chemistry. The small differences in intrinsic reactivity of C-H bonds in any given organic molecule can lead to the activation of undesired C-H bonds by a non-selective catalyst. One solution to this problem is to distinguish C-H bonds on the basis of their location in the molecule relative to a specific functional group. In this context, the activation of C-H bonds five or six bonds away from a functional group by cyclometallation has been extensively studied. However, the directed activation of C-H bonds that are distal to (more than six bonds away) functional groups has remained challenging, especially when the target C-H bond is geometrically inaccessible to directed metallation owing to the ring strain encountered in cyclometallation. Here we report a recyclable template that directs the olefination and acetoxylation of distal meta-C-H bonds--as far as 11 bonds away--of anilines and benzylic amines. This template is able to direct the meta-selective C-H functionalization of bicyclic heterocycles via a highly strained, tricyclic-cyclophane-like palladated intermediate. X-ray and nuclear magnetic resonance studies reveal that the conformational biases induced by a single fluorine substitution in the template can be enhanced by using a ligand to switch from ortho- to meta-selectivity.

A General Catalyst for Site-Selective C(sp(3))-H Bond Amination of Activated Secondary over Tertiary Alkyl C(sp(3))-H Bonds.

Science.gov (United States)

Scamp, Ryan J; Jirak, James G; Dolan, Nicholas S; Guzei, Ilia A; Schomaker, Jennifer M

2016-06-17

The discovery of transition metal complexes capable of promoting general, catalyst-controlled and selective carbon-hydrogen (C-H) bond amination of activated secondary C-H bonds over tertiary alkyl C(sp(3))-H bonds is challenging, as substrate control often dominates when reactive nitrene intermediates are involved. In this letter, we report the design of a new silver complex, [(Py5Me2)AgOTf]2, that displays general and good-to-excellent selectivity for nitrene insertion into propargylic, benzylic, and allylic C-H bonds over tertiary alkyl C(sp(3))-H bonds.

Role of Met80 and Tyr67 in the low-pH conformational equilibria of cytochrome c.

Science.gov (United States)

Battistuzzi, Gianantonio; Bortolotti, Carlo Augusto; Bellei, Marzia; Di Rocco, Giulia; Salewski, Johannes; Hildebrandt, Peter; Sola, Marco

2012-07-31

The low-pH conformational equilibria of ferric yeast iso-1 cytochrome c (ycc) and its M80A, M80A/Y67H, and M80A/Y67A variants were studied from pH 7 to 2 at low ionic strength through electronic absorption, magnetic circular dichroism, and resonance Raman spectroscopies. For wild-type ycc, the protein structure, axial heme ligands, and spin state of the iron atom convert from the native folded His/Met low-spin (LS) form to a molten globule His/H(2)O high-spin (HS) form and a totally unfolded bis-aquo HS state, in a single cooperative transition with an apparent pK(a) of ~3.0. An analogous cooperative transition occurs for the M80A and M80A/Y67H variants. This is preceded by protonation of heme propionate-7, with a pK(a) of ~4.2, and by an equilibrium between a His/OH(-)-ligated LS and a His/H(2)O-ligated HS conformer, with a pK(a) of ~5.9. In the M80A/Y67A variant, the cooperative low-pH transition is split into two distinct processes because of an increased stability of the molten globule state that is formed at higher pH values than the other species. These data show that removal of the axial methionine ligand does not significantly alter the mechanism of acidic unfolding and the ranges of stability of low-pH conformers. Instead, removal of a hydrogen bonding partner at position 67 increases the stability of the molten globule and renders cytochrome c more susceptible to acid unfolding. This underlines the key role played by Tyr67 in stabilizing the three-dimensional structure of cytochrome c by means of the hydrogen bonding network connecting the Ω loops formed by residues 71-85 and 40-57.

Homoleptic diphosphacyclobutadiene complexes [M(η(4)-P2C2R2)2]x- (M = Fe, Co; x = 0, 1).

Science.gov (United States)

Wolf, Robert; Ehlers, Andreas W; Khusniyarov, Marat M; Hartl, František; de Bruin, Bas; Long, Gary J; Grandjean, Fernande; Schappacher, Falko M; Pöttgen, Rainer; Slootweg, J Chris; Lutz, Martin; Spek, Anthony L; Lammertsma, Koop

2010-12-27

The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)(thf)(2)][Fe(η(4)-P(2)C(2)tBu(2))(2)] (K1), [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)tBu(2))(2)] (K2), and [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)Ad(2))(2)] (K3, Ad = adamantyl) were obtained from reactions of [K([18]crown-6)(thf)(2)][M(η(4)-C(14)H(10))(2)] (M = Fe, Co) with tBuC[triple bond]P (1, 2), or with AdC[triple bond]P (3). Neutral sandwiches [M(η(4)-P(2)C(2)tBu(2))(2)] (4: M = Fe 5: M = Co) were obtained by oxidizing 1 and 2 with [Cp(2)Fe]PF(6). Cyclic voltammetry and spectro-electrochemistry indicate that the two [M(η(4)-P(2)C(2)tBu(2))(2)](-)/[M(η(4)-P(2)C(2)tBu(2))(2)] moieties can be reversibly interconverted by one electron oxidation and reduction, respectively. Complexes 1-5 were characterized by multinuclear NMR, EPR (1 and 5), UV/Vis, and Mössbauer spectroscopies (1 and 4), mass spectrometry (4 and 5), and microanalysis (1-3). The molecular structures of 1-5 were determined by using X-ray crystallography. Essentially D(2d)-symmetric structures were found for all five complexes, which show the two 1,3-diphosphacyclobutadiene rings in a staggered orientation. Density functional theory calculations revealed the importance of covalent metal-ligand π bonding in 1-5. Possible oxidation state assignments for the metal ions are discussed.

Experimental ion mobility measurements in Xe-C2H6

Science.gov (United States)

Perdigoto, J. M. C.; Cortez, A. F. V.; Veenhof, R.; Neves, P. N. B.; Santos, F. P.; Borges, F. I. G. M.; Conde, C. A. N.

2017-10-01

In this paper we present the results of the ion mobility measurements made in gaseous mixtures of xenon (Xe) with ethane (C2H6) for pressures ranging from 6 to 10 Torr (8-10.6 mbar) and for low reduced electric fields in the 10 Td to 25 Td range (2.4-6.1 kVṡcm-1ṡ bar-1), at room temperature. The time of arrival spectra revealed two peaks throughout the entire range studied which were attributed to ion species with 3-carbons (C3H5+, C3H6+ C3H8+ and C3H9+) and with 4-carbons (C4H7+, C4H9+ and C4H10+). Besides these, and for Xe concentrations above 70%, a bump starts to appear at the right side of the main peak for reduced electric fields higher than 20 Td, which was attributed to the resonant charge transfer of C2H6+ to C2H6 that affects the mobility of its ion products (C3H8+ and C3H9+). The time of arrival spectra for Xe concentrations of 20%, 50%, 70% and 90% are presented, together with the reduced mobilities as a function of the Xe concentration calculated from the peaks observed for the low reduced electric fields and pressures studied.

Effect of H/C ratio on coal ignition

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

1988-09-01

The Cahn balance technique was found to be suitable for estimating ignition temperature and its dependence on the H/C ratio of the coal. This temperature decreased with increasing H/C ratio of coals. For coals a linear correlation between H/C ratio and the temperature was established. Chars derived from the coals deviated from the linear correlation established on coals. 17 refs., 4 figs.

Interconversion of η3-H2SiRR' σ-complexes and 16-electron silylene complexes via reversible H-H or C-H elimination.

Science.gov (United States)

Lipke, Mark C; Neumeyer, Felix; Tilley, T Don

2014-04-23

Solid samples of η(3)-silane complexes [PhBP(Ph)3]RuH(η(3)-H2SiRR') (R,R' = Et2, 1a; PhMe, 1b; Ph2, 1c, MeMes, 1d) decompose when exposed to dynamic vacuum. Gas-phase H2/D2 exchange between isolated, solid samples of 1c-d3 and 1c indicate that a reversible elimination of H2 is the first step in the irreversible decomposition. An efficient solution-phase trap for hydrogen, the 16-electron ruthenium benzyl complex [PhBP(Ph)3]Ru[η(3)-CH2(3,5-Me2C6H3)] (3) reacts quantitatively with H2 in benzene via elimination of mesitylene to form the η(5)-cyclohexadienyl complex [PhBP(Ph)3]Ru(η(5)-C6H7) (4). This H2 trapping reaction was utilized to drive forward and quantify the elimination of H2 from 1b,d in solution, which resulted in the decomposition of 1b,d to form 4 and several organosilicon products that could not be identified. Reaction of {[PhBP(Ph)3]Ru(μ-Cl)}2 (2) with (THF)2Li(SiHMes2) forms a new η(3)-H2Si species [PhBP(Ph)3]Ru[CH2(2-(η(3)-H2SiMes)-3,5-Me2C6H2)] (5) which reacts with H2 to form the η(3)-H2SiMes2 complex [PhBP(Ph)3]RuH(η(3)-H2SiMes2) (1e). Complex 1e was identified by NMR spectroscopy prior to its decomposition by elimination of Mes2SiH2 to form 4. DFT calculations indicate that an isomer of 5, the 16-electron silylene complex [PhBP(Ph)3]Ru(μ-H)(═SiMes2), is only 2 kcal/mol higher in energy than 5. Treatment of 5 with XylNC (Xyl = 2,6-dimethylphenyl) resulted in trapping of [PhBP(Ph)3]Ru(μ-H)(═SiMes2) to form the 18-electron silylene complex [PhBP(Ph)3]Ru(CNXyl)(μ-H)(═SiMes2) (6). A closely related germylene complex [PhBP(Ph)3]Ru[CN(2,6-diphenyl-4-MeC6H2)](H)(═GeH(t)Bu) (8) was prepared from reaction of (t)BuGeH3 with the benzyl complex [PhBP(Ph)3]Ru[CN(2,6-diphenyl-4-MeC6H2)][η(1)-CH2(3,5-Me2C6H3)] (7). Single crystal XRD analysis indicated that unlike for 6, the hydride ligand in 8 is a terminal hydride that does not engage in 3c-2e Ru-H → Ge bonding. Complex 1b is an effective precatalyst for the catalytic Ge-H dehydrocoupling

Specific primary ionization induced by minimum ionizing electrons in CH4, C2H6, C3H8, i-C4H10, Ar, DME,TEA and TMAE

International Nuclear Information System (INIS)

Melamud, G.; Breskin, A.; Chechik, R.; Pansky, A.

1992-10-01

Specific primary ionization induced by minimum ionizing electrons has been measured in several gases and vapors. Charges deposited by β-electrons in a low pressure gas, were collected, amplified by a multistep gaseous electron multiplier and counted. The high counting efficiency of the multiplier provided results of systematically higher values as compared to existing data. The respective values of the specific primary ionization in CH 4 C 2 H 6 , C 3 H 8 ,i-C 4 H 10 , Argon, Dimethylether, Triethylamine and Tetrakis(dimethylamino) ethylene are: 0.034, 0.065, 0.095, 0.12, 0.03, 0.082, 0.0195 and 0.370 clusters/cm*Torr. We present the experimental method and discuss the results and their accuracy. (authors)

Processing and Characterization of Thousand-Hour 500 C Durable 4H-SiC JFET Integrated Circuits

Science.gov (United States)

Spry, David J.; Neudeck, Philip G.; Chen, Liangyu; Lukco, Dorothy; Chang, Carl W.; Beheim, Glenn M.; Krasowski, Michael J.; Prokop, Norman F.

2016-01-01

This work reports fabrication and testing of integrated circuits (ICs) with two levels of interconnect that consistently achieve greater than 1000 hours of stable electrical operation at 500 C in air ambient. These ICs are based on 4H-SiC junction field effect transistor (JFET) technology that integrates hafnium ohmic contacts with TaSi2 interconnects and SiO2 and Si3N4 dielectric layers over 1-m scale vertical topology. Following initial burn-in, important circuit parameters remain stable for more than 1000 hours of 500 C operational testing. These results advance the technology foundation for realizing long-term durable 500 C ICs with increased functional capability for sensing and control combustion engine, planetary, deep-well drilling, and other harsh-environment applications.

Sterically hindered solvent extractants

International Nuclear Information System (INIS)

Solka, J.L.; Reis, A.H. Jr.; Mason, G.W.; Lewey, S.M.; Peppard, D.F.

1978-01-01

Di-t-pentylphosphinic acid, [C(CH 3 ) 2 (CH 2 CH 3 )] 2 PO(OH), H[Dt-PeP], has been shown by single-crystal X-ray diffraction data to be dimeric in the solid state. H[Dt-PeP] crystallizes in the centro-symmetric orthorhombic space group, Cmca, with unit cell parameters, a = 17.694(7), b = 11.021(4), and c = 13.073(5) A, and Z = 8, indicating that the molecule must conform to a crystallographic mirror plane or 2-fold axis. A measured density of 1.088 g/cm 3 is in good agreement with a calculated value of 1.074 g/cm 3 for a unit cell volume of 2549.3(A) 3 and a formula weight of 206.25 g. A total of 646 three-dimensional X-ray data were collected on an automated XRD-490 G.E. diffractometer. The structure was solved using a combination of direct methods, Patterson, Fourier, and least-squares refinement techniques. Refinement of the data indicates that H[Dt-PeP] is dimeric, and contains a mirror plane in which the hydrogen-bonded, eight-membered ring lies. A structural disorder involving principally the ethylene carbon but affecting the methyl carbons as well precluded a precise determination of the carbon positions and severely reduced the precision of the final refinement. In the liquid-liquid extraction system consisting of a solution of H[Dt-PeP] in benzene vs an acidic aqueous chloride phase, the extraction of UO 2 2+ follows the stoichiometry: UO 2 sub(A) 2+ + 2(HY) 2 subO = UO 2 (HY 2 ) 2 sub(O) + 2Hsub(A) + where (HY) 2 represents the dimer of H[Dt-PeP] and A and O represent the mutually equilibrated aqueous and organic phases. The expression for the distribution ratio, k, for UO 2 2+ is given. (author)

Superhard nanocomposite nc-TiC/a-C:H film fabricated by filtered cathodic vacuum arc technique

International Nuclear Information System (INIS)

Wang Yaohui; Zhang Xu; Wu Xianying; Zhang Huixing; Zhang Xiaoji

2008-01-01

Superhard nanocomposite nc-TiC/a-C:H films, with an excellent combination of high elastic recovery, low friction coefficient and good H/E ratio, were prepared by filtered cathodic vacuum arc technique using the C 2 H 2 gas as the precursor. The effect of C 2 H 2 flow rate on the microstructure, phase composition, mechanical and tribological properties of nanocomposite nc-TiC/a-C:H films have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy disperse spectroscopy (EDS), microindentation and tribotester measurements. It was observed that the C 2 H 2 flow rate significantly affected the Ti content and hardness of films. Furthermore, by selecting the proper value for C 2 H 2 flow rate, 20 sccm, one can deposit the nanocomposite film nc-TiC/a-C:H with excellent properties such as superhardness (66.4 GPa), high elastic recovery (83.3%) and high H/E ratio (0.13)

Stringent homology-based prediction of H. sapiens-M. tuberculosis H37Rv protein-protein interactions.

Science.gov (United States)

Zhou, Hufeng; Gao, Shangzhi; Nguyen, Nam Ninh; Fan, Mengyuan; Jin, Jingjing; Liu, Bing; Zhao, Liang; Xiong, Geng; Tan, Min; Li, Shijun; Wong, Limsoon

2014-04-08

H. sapiens-M. tuberculosis H37Rv protein-protein interaction (PPI) data are essential for understanding the infection mechanism of the formidable pathogen M. tuberculosis H37Rv. Computational prediction is an important strategy to fill the gap in experimental H. sapiens-M. tuberculosis H37Rv PPI data. Homology-based prediction is frequently used in predicting both intra-species and inter-species PPIs. However, some limitations are not properly resolved in several published works that predict eukaryote-prokaryote inter-species PPIs using intra-species template PPIs. We develop a stringent homology-based prediction approach by taking into account (i) differences between eukaryotic and prokaryotic proteins and (ii) differences between inter-species and intra-species PPI interfaces. We compare our stringent homology-based approach to a conventional homology-based approach for predicting host-pathogen PPIs, based on cellular compartment distribution analysis, disease gene list enrichment analysis, pathway enrichment analysis and functional category enrichment analysis. These analyses support the validity of our prediction result, and clearly show that our approach has better performance in predicting H. sapiens-M. tuberculosis H37Rv PPIs. Using our stringent homology-based approach, we have predicted a set of highly plausible H. sapiens-M. tuberculosis H37Rv PPIs which might be useful for many of related studies. Based on our analysis of the H. sapiens-M. tuberculosis H37Rv PPI network predicted by our stringent homology-based approach, we have discovered several interesting properties which are reported here for the first time. We find that both host proteins and pathogen proteins involved in the host-pathogen PPIs tend to be hubs in their own intra-species PPI network. Also, both host and pathogen proteins involved in host-pathogen PPIs tend to have longer primary sequence, tend to have more domains, tend to be more hydrophilic, etc. And the protein domains from both

Proton relays in anomalous carbocations dictate spectroscopy, stability, and mechanisms: case studies on C2H5+ and C3H3.

Science.gov (United States)

Sager, LeeAnn M; Iyengar, Srinivasan S

2017-10-18

We present a detailed analysis of the anomalous carbocations: C 2 H 5 + and C 3 H 3 + . This work involves (a) probing electronic structural properties, (b) ab initio dynamics simulations over a range of internal energies, (c) analysis of reduced dimensional potential surfaces directed along selected conformational transition pathways, (d) dynamically averaged vibrational spectra computed from ab initio dynamics trajectories, and (e) two-dimensional time-frequency analysis to probe conformational dynamics. Key findings are as follows: (i) as noted in our previous study on C 2 H 3 + , it appears that these non-classical carbocations are stabilized by delocalized nuclear frameworks and "proton shuttles". We analyze this nuclear delocalization and find critical parallels between conformational changes in C 2 H 3 + , C 2 H 5 + , and C 3 H 3 + . (ii) The vibrational signatures of C 2 H 5 + are dominated by the "bridge-proton" conformation, but also show critical contributions from the "classical" configuration, which is a transition state at almost all levels of theory. This result is further substantiated through two-dimensional time-frequency analysis and is at odds with earlier explanations of the experimental spectra, where frequencies close to the classical region were thought to arise from an impurity. While this is still possible, our results here indicate an additional (perhaps more likely) explanation that involves the "classical" isomer. (iii) Finally, in the case of C 3 H 3 + our explanation of the experimental result includes the presence of multiple, namely, "cyclic", "straight", and propargyl, configurations. Proton shuttles and nuclear delocalization, reminiscent of those seen in the case of C 2 H 3 + , were seen all through and have a critical role in all our observations.

Feeling hindered by health problems and functional capacity at 60 years and above.

Science.gov (United States)

Fagerström, Cecilia; Holst, Göran; Hallberg, Ingalill R

2007-01-01

It is common to use activities of daily living (ADL) rating scales to identify the impact of health problems such as diseases, impaired eyesight or hearing on daily life. However, for various reasons people with health problems might feel hindered in daily life before limitations in ability to perform ADL have occurred. In addition, there is sparse knowledge of what makes people feel hindered by health problems in relation to their ADL capacity. The aim was to investigate feeling hindered by health problems among 1297 people aged 60-89 living at home in relation to ADL capacity, health problems, life satisfaction, self-esteem, and social and financial resources, using a self-reported questionnaire, including questions from Older Americans' Resources and Services schedule (OARS), Rosenberg's self-esteem and Life Satisfaction Index Z (LSIZ). People feeling greatly hindered by health problems rarely had anyone who could help when they needed support, had lower life satisfaction and self-esteem than those not feeling hindered. Feeling hindered by health problems appeared to take on a different meaning depending on ADL capacity, knowledge that seems essential to include when accomplishing health promotion and rehabilitation interventions, especially at the early stages of reduced ADL capacity.

Luteolin Prevents H2O2-Induced Apoptosis in H9C2 Cells through Modulating Akt-P53/Mdm2 Signaling Pathway

Directory of Open Access Journals (Sweden)

Hong Chang

2016-01-01

Full Text Available Introduction. Luteolin, a falconoid compound in many Chinese herbs and formula, plays important roles in cardiovascular diseases. The underlying mechanism of luteolin remains to be further elaborated. Methods. A model of hydrogen peroxide- (H2O2- induced H9C2 cells apoptosis was established. Cell viabilities were examined with an MTT assay. 2′,7′-Dichlorofluorescin diacetate (DCFH-DA and flow cytometry were used to detect ROS level and apoptosis rate, respectively. The expressions of signaling proteins related to apoptosis were analyzed by western blot and mRNA levels were detected by real-time polymerase chain reaction (PCR. Quercetin was applied as positive drug. Results. Incubation with various concentrations of H2O2 (0, 50, 100, and 200 μM for 1 h caused dose-dependent loss of cell viability and 100 μM H2O2 reduced the cell viability to approximately 50%. Treatments with luteolin and quercetin protected cells from H2O2-induced cytotoxicity and reduced cellular ROS level and apoptosis rate. Moreover, luteolin could downregulate the expressions of Bax, caspase-8, cleaved-caspase-3, and p53 in apoptotic signaling pathway. Further study showed that the expressions of Akt, Bcl-2, and Mdm2 were upregulated by luteolin. Conclusion. Luteolin protects H9C2 cells from H2O2-induced apoptosis. The protective and antiapoptotic effects of luteolin could be mediated by regulating the Akt-P53/Mdm2 apoptotic pathway.

Triosmium cluster compounds containing isocyanide and hydride ligands. Crystal and molecular structure of (μ-H)(μ-eta1-C==N(H)(t-C4H9))Os3(CO)10

International Nuclear Information System (INIS)

Adams, R.D.; Golembeski, N.M.

1979-01-01

The crystal and molecular structure of the compound (μ-H)(μ-eta 1 -C==N(H)(t-C 4 H 9 ))Os 3 (CO) 10 has been determined by X-ray crystallographic methods. The compound crystallizes in the centrosymmetric monoclinic space group P2 1 /n[C/sub 2h/ 5 ]:a = 13.651 (4) A, b = 9.156 (4) A, c = 18.275 (5) A, β = 111.42 (2) 0 , V = 2126.3 (25) A 3 , Z = 4, rho/sub calcd/ = 2.92 g cm -3 . A uniform triangular cluster of three osmium atoms contains ten linear carbonyl groups and a μ-eta 1 -C==N(H)(t-C 4 H 9 ) iminyl ligand. The carbon atom of the iminyl ligand symmetrically bridges one osmium-osmium bond, as is shown by the internuclear separations Os(2)-C(11) = 2.066 (8) A and Os(3)-C(11) = 2.043 (8) A. The iminyl bond, C(11)-N, is double with the C-N distance being 1.298 (10) A

Ligand-controlled, tunable silver-catalyzed C-H amination.

Science.gov (United States)

Alderson, Juliet M; Phelps, Alicia M; Scamp, Ryan J; Dolan, Nicholas S; Schomaker, Jennifer M

2014-12-03

The development of readily tunable and regioselective C-H functionalization reactions that operate solely through catalyst control remains a challenge in modern organic synthesis. Herein, we report that simple silver catalysts supported by common nitrogenated ligands can be used to tune a nitrene transfer reaction between two different types of C-H bonds. The results reported herein represent the first example of ligand-controlled and site-selective silver-promoted C-H amination.

Thermochemical Properties Enthalpy, Entropy, and Heat Capacity of C1-C4 Fluorinated Hydrocarbons: Fluorocarbon Group Additivity.

Science.gov (United States)

Wang, Heng; Castillo, Álvaro; Bozzelli, Joseph W

2015-07-23

Enthalpies of formation for 14 C2–C4 fluorinated hydrocarbons were calculated with nine popular ab initio and density functional theory methods: B3LYP, CBS-QB3, CBS-APNO, M06, M06-2X, ωB97X, G4, G4(MP2)-6X, and W1U via several series of isodesmic reactions. The recommended ideal gas phase ΔHf298° (kcal mol(–1)) values calculated in this study are the following: −65.4 for CH3CH2F; −70.2 for CH3CH2CH2F; −75.3 for CH3CHFCH3; −75.2 for CH3CH2CH2CH2F; −80.3 for CH3CHFCH2CH3; −108.1 for CH2F2; −120.9 for CH3CHF2; −125.8 for CH3CH2CHF2; −133.3 for CH3CF2CH3; −166.7 for CHF3; −180.5 for CH3CF3; −185.5 for CH3CH2CF3; −223.2 for CF4; and −85.8 for (CH3)3CF. Entropies (S298° in cal mol(–1) K(–1)) were estimated using B3LYP/6-31+G(d,p) computed frequencies and geometries. Rotational barriers were determined and hindered internal rotational contributions for S298°, and Cp(T) were calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of the intramolecular rotation potential energy curve. Thermochemical properties for the fluorinated carbon groups C/C/F/H2, C/C2/F/H, C/C/F2/H, C/C2/F2, and C/C/F3 were derived from the above target fluorocarbons. Previously published enthalpies and groups for 1,2-difluoroethane, 1,1,2-trifluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,2,2-pentafluoroethane, 2-fluoro-2-methylpropane that were previously determined via work reaction schemes are revised using updated reference species values. Standard deviations are compared for the calculation methods.

Triple Layer Antireflection Design Concept for the Front Side of c-Si Heterojunction Solar Cell Based on the Antireflective Effect of nc-3C-SiC:H Emitter Layer

Directory of Open Access Journals (Sweden)

Erick Omondi Ateto

2016-01-01

Full Text Available We investigated the antireflective (AR effect of hydrogenated nanocrystalline cubic silicon carbide (nc-3C-SiC:H emitter and its application in the triple layer AR design for the front side of silicon heterojunction (SHJ solar cell. We found that the nc-3C-SiC:H emitter can serve both as an emitter and antireflective coating for SHJ solar cell, which enables us to realize the triple AR design by adding one additional dielectric layer to normally used SHJ structure with a transparent conductive oxide (TCO and an emitter layer. The optimized SHJ structure with the triple layer AR coating (LiF/ITO/nc-3C-SiC:H exhibit a short circuit current density (Jsc of 38.65 mA/cm2 and lower reflectivity of about 3.42% at wavelength range of 300 nm–1000 nm.

Advanced TiC/a-C: H nanocomposite coatings deposited by magnetron sputtering

OpenAIRE

Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De; Strondl, C.

2006-01-01

TiC/a-C:H nanocomposite coatings have been deposited by magnetron Sputtering. They consist of 2-5 nm TiC nanocrystallites embedded in the amorphous hydrocarbon (a-C:H) matrix. A transition from a Columnar to a glassy microstructure has been observed in the nanocomposite coatings with increasing substrate bias or carbon content. Micro-cracks induced by nanoindentation or wear tests readily propagate through the column boundaries whereas the coatings without a columnar inicrostructure exhibit s...

A DFT study on the effect of hydrogen in ethylene and propylene polymerization using a Ti-based heterogeneous Ziegler–Natta catalyst

KAUST Repository

Bahri-Laleh, Naeimeh

2012-11-01

Hydrogenolysis of a series of model Ziegler-Natta (Z-N) catalysts to form Ti-H bond was studied within DFT. We focused our efforts on Ti species attached to the (110) lateral cut of MgCl 2 which exist as different centres including Ti-C 2H 5, Ti-CH 2CH(CH 3) 2, and Ti-CH(CH 3)CH 2CH 3 in ethylene and propylene polymerization. In the next step, reactivity of Ti-H bond towards ethylene and propylene (1,2- and 2,1-) insertion was investigated. Results showed that insertion of ethylene and propylene into Ti-H bond has less barrier, in comparison with their insertion in Ti-C bond, however, ethylene and propylene 2,1- insertion lead to Ti-C 2H 5 and Ti-CH(CH 3) 2 centres respectively, which were stable due to strong β-agostic interactions. Finally, by considering different possible reactions of active centre, activity depression in ethylene polymerization and activity increase in propylene polymerization were explained in detail. © 2012 Elsevier B.V.

Symmetry breaking and spectral considerations of the surprisingly floppy c-C3H radical and the related dipole-bound excited state of c-C3H-

Science.gov (United States)

Bassett, Matthew K.; Fortenberry, Ryan C.

2017-06-01

The C3H radical is believed to be prevalent throughout the interstellar medium and may be involved in the formation of polycyclic aromatic hydrocarbons. C3H exists as both a linear and a cyclic isomer. The C2 v cyclopropenylidenyl radical isomer was detected in the dark molecular cloud TMC-1, and the linear propenylidenyl radical isomer has been observed in various dark molecular clouds. Even though the c-C3H radical has been classified rotationally, the vibrational frequencies of this seemingly important interstellar molecule have never been directly observed. Established, highly accurate quartic force field methodologies are employed here to compute useful geometrical data, spectroscopic constants, and vibrational frequencies. The computed rotational constants are consistent with the experimental results. Consequently, the three a1 (ν1, ν2, and ν3) and one b1 (ν6) anharmonic vibrational frequencies at 3117.7 cm-1, 1564.3 cm-1, 1198.5 cm-1, and 826.7 cm-1, respectively, are reliable predictions for these, as of yet unseen, observables. Unfortunately, the two b2 fundamentals (ν4 and ν5) cannot be treated adequately in the current approach due to a flat and possible double-well potential described in detail herein. The dipole-bound excited state of the anion suffers from the same issues and may not even be bound. However, the trusted fundamental vibrational frequencies described for the neutral radical should not be affected by this deformity and are the first robustly produced for c-C3H. The insights gained here will also be applicable to other structures containing three-membered bare and exposed carbon rings that are surprisingly floppy in nature.

Metal coordination by sterically hindered heterocyclic ligands, including 2-vinylpyridine, assessed by investigation of cobaloximes.

Science.gov (United States)

Siega, Patrizia; Randaccio, Lucio; Marzilli, Patricia A; Marzilli, Luigi G

2006-04-17

Structural and 1H NMR data have been obtained for cobaloximes with the bulkiest substituted pyridines reported so far. We have isolated in noncoordinating solvents the complexes CH3Co(DH)2L (methylcobaloxime, where DH = the monoanion of dimethylglyoxime) with L = sterically hindered N-donor ligands: quinoline, 4-CH3quinoline, 2,4-(CH3)2pyridine, and 2-R-pyridine (R = CH3, OCH3, CH2CH3, CH=CH2). We have found that the Co-N(ax) bond is very long in the structurally characterized complexes. In particular, CH3Co(DH)2(4-CH3quinoline) has a longer Co-N(ax) bond (2.193(3) A) than any reported for methylcobaloximes. The main cause of the long bonds is unambiguously identified as the steric bulk of L by the fairly linear relationship found for Co-N(ax) distance vs CCA (calculated cone angle, CCA, a computed measure of bulk) over an extensive series of methylcobaloximes. The linear relationship improves if L basicity (quantified by pKa) is taken into account. In anhydrous CDCl3 at 25 degrees C, all complexes except the 2-aminopyridine adduct exhibit 1H NMR spectra consistent with partial dissociation of L to form the methylcobaloxime dimer. 1H NMR experiments at -20 degrees C allowed us to assess qualitatively the relative binding ability of L as follows: 2,4-(CH3)2pyridine > 4-CH3quinoline approximately = quinoline approximately = 2-CH3pyridine > 2-CH3Opyridine > 2-CH3CH2pyridine > 2-CH2=CHpyridine. The broadness of the 1H NMR signals at 25 degrees C suggests a similar order for the ligand exchange rate. The lack of dissociation by 2-aminopyridine is attributed to an intramolecular hydrogen bond between the NH2 group and an oxime O atom. The weaker than expected binding of 2-vinylpyridine relative to the Co-N(ax) bond length is attributed to rotation of the 2-vinyl group required for this bulky ligand to bind to the metal center, a conclusion supported by pronounced changes in 2-vinylpyridine signals upon coordination.

Triosmium cluster compounds containing isocyanide and hydride ligands. Crystal and molecular structures of (μ-H)(H)Os3(CO)10(CN-t-C4H9) and (μ-H)2Os3(CO)9(CN-t-C4H9)

International Nuclear Information System (INIS)

Adams, R.D.; Golembski, N.M.

1979-01-01

The structures of the compounds (μ-H)(H)Os 3 (CO) 10 (CN-t-C 4 H 9 ) and (μ-H) 2 Os 3 (CO) 9 (CN-t-C 4 H 9 ) have been revealed by x-ray crystallographic techniques. For (μ-H)(H)Os 3 (CO) 10 (CN-t-C 4 H 9 ): a = 9.064 (3), b = 12.225 (3), c = 20.364 (4) A; β = 98.73 (3) 0 ; space group P2 1 /c[C/sub 2h/ 5 ], No. 14; Z = 4; d/sub calcd/ = 2.79 g cm -3 . This compound contains a triangular cluster of three osmium atoms; Os(1)--Os(2) = 2.930 (1) A, Os(1)--Os(3) = 2.876 (1) A, and Os(2)--Os(3) = 3.000 (1) A. There are ten linear terminal carbonyl groups and one linear terminal isocyanide ligand which occupies an axial coordination site. The hydrogen atoms were not observed crystallographically, but their positions are strongly inferred from considerations of molecular geometry. For (μ-H) 2 Os 3 (CO) 9 (CN-t-C 4 H 9 ): a = 15.220 (8), b = 12.093 (6), c = 23.454 (5) A; space group Pbcn [D/sub 2h/ 14 ], No. 60; Z = 8; d/sub calcd/ = 2.79 g cm -3 . The compound is analogous to the parent carbonyl (μ-H) 2 Os 3 (CO) 10 and has two normal and one short osmium--osmium bonds: Os(1)--Os(2) = 2.827 (1) A, Os(1)--Os(3) = 2.828 (1) A, Os(2)--Os(3) = 2.691 (1) A. The isocyanide ligand resides in an equatorial coordination site on osmium Os(2). The hydrogen atoms were not observed but are believed to occupy bridging positions as in the parent carbonyl complex. 2 figures, 7 tables

Compensating for Language Deficits in Amnesia II: H.M.’s Spared versus Impaired Encoding Categories

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Chris Hadley

2013-03-01

Full Text Available Although amnesic H.M. typically could not recall where or when he met someone, he could recall their topics of conversation after long interference-filled delays, suggesting impaired encoding for some categories of novel events but not others. Similarly, H.M. successfully encoded into internal representations (sentence plans some novel linguistic structures but not others in the present language production studies. For example, on the Test of Language Competence (TLC, H.M. produced uncorrected errors when encoding a wide range of novel linguistic structures, e.g., violating reliably more gender constraints than memory-normal controls when encoding referent-noun, pronoun-antecedent, and referent-pronoun anaphora, as when he erroneously and without correction used the gender-inappropriate pronoun “her” to refer to a man. In contrast, H.M. never violated corresponding referent-gender constraints for proper names, suggesting that his mechanisms for encoding proper name gender-agreement were intact. However, H.M. produced no more dysfluencies, off-topic comments, false starts, neologisms, or word and phonological sequencing errors than controls on the TLC. Present results suggest that: (a frontal mechanisms for retrieving and sequencing word, phrase, and phonological categories are intact in H.M., unlike in category-specific aphasia; (b encoding mechanisms in the hippocampal region are category-specific rather than item-specific, applying to, e.g., proper names rather than words; (c H.M.’s category-specific mechanisms for encoding referents into words, phrases, and propositions are impaired, with the exception of referent gender, person, and number for encoding proper names; and (d H.M. overuses his intact proper name encoding mechanisms to compensate for his impaired mechanisms for encoding other functionally equivalent linguistic information.

Mechanical stimulation of C2C12 cells increases m-calpain expression and activity, focal adhesion plaque degradation and cell fusion

DEFF Research Database (Denmark)

Grossi, Alberto; Karlsson, Anders Hans; Lawson, Moira A.

2005-01-01

Abstract Mechanical Stimulation of C2C12 Cells Increases m-calpain Expression and Activity, Focal Adhesion Plaque Degradation and Cell Fusion A. Grossi, A. H. Karlsson, M. A. Lawson; Department of Dairy and Food Science, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark...... Myogenesis is a complex sequence of events, including the irreversible transition from the proliferation-competent myoblast stage into fused, multinucleated myotubes. During embryonic development, myogenic differentiation is regulated by positive and negative signals from surrounding tissues. Stimulation due...... to the activity of ubiquitous proteolytic enzymes known as calpains has been reported. Whether there is a link between stretch- or load induced signaling and calpain expression and activation is not known. Using a magnetic bead stimulation assay and C2C12 mouse myoblasts cell population, we have demonstrated...

Bluish-white-light-emitting diodes based on two-dimensional lead halide perovskite (C6H5C2H4NH3)2PbCl2Br2

Science.gov (United States)

Cai, Peiqing; Wang, Xiangfu; Seo, Hyo Jin; Yan, Xiaohong

2018-04-01

Bluish-white-light-emitting diodes (BWLEDs) are designed based on the two-dimensional mixed halide perovskite (C6H5C2H4NH3)2PbCl2Br2 at room temperature. Bluish-white electroluminescence devices were fabricated by a spin-coating method. The BWLEDs can be turned on at 4.9 V and depict a maximum luminance of ˜70 cd/m2 at 7 V. Low and room temperature photoluminescence spectra show the coexistence of free exciton and self-trapped exciton luminescence in a deformable lattice. The strategy of achieving white electroluminescence (EL) from mixed halide perovskite reported here can be applied to other two-dimensional perovskites to increase the optoelectronic efficiency of the device in the future.

Enzyme-controlled nitrogen-atom transfer enables regiodivergent C-H amination.

Science.gov (United States)

Hyster, Todd K; Farwell, Christopher C; Buller, Andrew R; McIntosh, John A; Arnold, Frances H

2014-11-05

We recently demonstrated that variants of cytochrome P450BM3 (CYP102A1) catalyze the insertion of nitrogen species into benzylic C-H bonds to form new C-N bonds. An outstanding challenge in the field of C-H amination is catalyst-controlled regioselectivity. Here, we report two engineered variants of P450BM3 that provide divergent regioselectivity for C-H amination-one favoring amination of benzylic C-H bonds and the other favoring homo-benzylic C-H bonds. The two variants provide nearly identical kinetic isotope effect values (2.8-3.0), suggesting that C-H abstraction is rate-limiting. The 2.66-Å crystal structure of the most active enzyme suggests that the engineered active site can preorganize the substrate for reactivity. We hypothesize that the enzyme controls regioselectivity through localization of a single C-H bond close to the iron nitrenoid.

Direct Rehydrogenation of LiBH4 from H-Deficient Li2B12H12−x

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Yigang Yan

2018-03-01

Full Text Available Li2B12H12 is commonly considered as a boron sink hindering the reversible hydrogen sorption of LiBH4. Recently, in the dehydrogenation process of LiBH4 an amorphous H-deficient Li2B12H12−x phase was observed. In the present study, we investigate the rehydrogenation properties of Li2B12H12−x to form LiBH4. With addition of nanostructured cobalt boride in a 1:1 mass ratio, the rehydrogenation properties of Li2B12H12−x are improved, where LiBH4 forms under milder conditions (e.g., 400 °C, 100 bar H2 with a yield of 68%. The active catalytic species in the reversible sorption reaction is suggested to be nonmetallic CoxB (x = 1 based on 11B MAS NMR experiments and its role has been discussed.

Direct approaches to nitriles via highly efficient nitrogenation strategy through C-H or C-C bond cleavage.

Science.gov (United States)

Wang, Teng; Jiao, Ning

2014-04-15

Because of the importance of nitrogen-containing compounds in chemistry and biology, organic chemists have long focused on the development of novel methodologies for their synthesis. For example, nitrogen-containing compounds show up within functional materials, as top-selling drugs, and as bioactive molecules. To synthesize these compounds in a green and sustainable way, researchers have focused on the direct functionalization of hydrocarbons via C-H or C-C bond cleavage. Although researchers have made significant progress in the direct functionalization of simple hydrocarbons, direct C-N bond formation via C-H or C-C bond cleavage remains challenging, in part because of the unstable character of some N-nucleophiles under oxidative conditions. The nitriles are versatile building blocks and precursors in organic synthesis. Recently, chemists have achieved the direct C-H cyanation with toxic cyanide salts in the presence of stoichiometric metal oxidants. In this Account, we describe recent progress made by our group in nitrile synthesis. C-H or C-C bond cleavage is a key process in our strategy, and azides or DMF serve as the nitrogen source. In these reactions, we successfully realized direct nitrile synthesis using a variety of hydrocarbon groups as nitrile precursors, including methyl, alkenyl, and alkynyl groups. We could carry out C(sp(3))-H functionalization on benzylic, allylic, and propargylic C-H bonds to produce diverse valuable synthetic nitriles. Mild oxidation of C═C double-bonds and C≡C triple-bonds also produced nitriles. The incorporation of nitrogen within the carbon skeleton typically involved the participation of azide reagents. Although some mechanistic details remain unclear, studies of these nitrogenation reactions implicate the involvement of a cation or radical intermediate, and an oxidative rearrangement of azide intermediate produced the nitrile. We also explored environmentally friendly oxidants, such as molecular oxygen, to make our

Solid-state molecular organometallic chemistry. Single-crystal to single-crystal reactivity and catalysis with light hydrocarbon substrates.

Science.gov (United States)

Chadwick, F Mark; McKay, Alasdair I; Martinez-Martinez, Antonio J; Rees, Nicholas H; Krämer, Tobias; Macgregor, Stuart A; Weller, Andrew S

2017-08-01

Single-crystal to single-crystal solid/gas reactivity and catalysis starting from the precursor sigma-alkane complex [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(η 2 η 2 -NBA)][BAr F 4 ] (NBA = norbornane; Ar F = 3,5-(CF 3 ) 2 C 6 H 3 ) is reported. By adding ethene, propene and 1-butene to this precursor in solid/gas reactions the resulting alkene complexes [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(alkene) x ][BAr F 4 ] are formed. The ethene ( x = 2) complex, [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(ethene) 2 ][BAr F 4 ]-Oct , has been characterized in the solid-state (single-crystal X-ray diffraction) and by solution and solid-state NMR spectroscopy. Rapid, low temperature recrystallization using solution methods results in a different crystalline modification, [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(ethene) 2 ][BAr F 4 ]-Hex , that has a hexagonal microporous structure ( P 6 3 22). The propene complex ( x = 1) [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(propene)][BAr F 4 ] is characterized as having a π-bound alkene with a supporting γ-agostic Rh···H 3 C interaction at low temperature by single-crystal X-ray diffraction, variable temperature solution and solid-state NMR spectroscopy, as well as periodic density functional theory (DFT) calculations. A fluxional process occurs in both the solid-state and solution that is proposed to proceed via a tautomeric allyl-hydride. Gas/solid catalytic isomerization of d 3 -propene, H 2 C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111

Quantitative LC-MS Provides No Evidence for m6 dA or m4 dC in the Genome of Mouse Embryonic Stem Cells and Tissues.

Science.gov (United States)

Schiffers, Sarah; Ebert, Charlotte; Rahimoff, René; Kosmatchev, Olesea; Steinbacher, Jessica; Bohne, Alexandra-Viola; Spada, Fabio; Michalakis, Stylianos; Nickelsen, Jörg; Müller, Markus; Carell, Thomas

2017-09-04

Until recently, it was believed that the genomes of higher organisms contain, in addition to the four canonical DNA bases, only 5-methyl-dC (m 5 dC) as a modified base to control epigenetic processes. In recent years, this view has changed dramatically with the discovery of 5-hydroxymethyl-dC (hmdC), 5-formyl-dC (fdC), and 5-carboxy-dC (cadC) in DNA from stem cells and brain tissue. N 6 -methyldeoxyadenosine (m 6 dA) is the most recent base reported to be present in the genome of various eukaryotic organisms. This base, together with N 4 -methyldeoxycytidine (m 4 dC), was first reported to be a component of bacterial genomes. In this work, we investigated the levels and distribution of these potentially epigenetically relevant DNA bases by using a novel ultrasensitive UHPLC-MS method. We further report quantitative data for m 5 dC, hmdC, fdC, and cadC, but we were unable to detect either m 4 dC or m 6 dA in DNA isolated from mouse embryonic stem cells or brain and liver tissue, which calls into question their epigenetic relevance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electroremovable Traceless Hydrazides for Cobalt-Catalyzed Electro-Oxidative C-H/N-H Activation with Internal Alkynes.

Science.gov (United States)

Mei, Ruhuai; Sauermann, Nicolas; Oliveira, João C A; Ackermann, Lutz

2018-06-27

Electrochemical oxidative C-H/N-H activations have been accomplished with a versatile cobalt catalyst in terms of [4 + 2] annulations of internal alkynes. The electro-oxidative C-H activation manifold proved viable with an undivided cell setup under exceedingly mild reaction conditions at room temperature using earth-abundant cobalt catalysts. The electrochemical cobalt catalysis prevents the use of transition metal oxidants in C-H activation catalysis, generating H 2 as the sole byproduct. Detailed mechanistic studies provided strong support for a facile C-H cobaltation by an initially formed cobalt(III) catalyst. The subsequent alkyne migratory insertion was interrogated by mass spectrometry and DFT calculations, providing strong support for a facile C-H activation and the formation of a key seven-membered cobalta(III) cycle in a regioselective fashion. Key to success for the unprecedented use of internal alkynes in electrochemical C-H/N-H activations was represented by the use of N-2-pyridylhydrazides, for which we developed a traceless electrocleavage strategy by electroreductive samarium catalysis at room temperature.

13C, 1H spin-spin coupling constants. Pt. 4

International Nuclear Information System (INIS)

Aydin, R.; Guenther, H.

1979-01-01

One-bond, geminal, and vicinal 13 C, 1 H coupling constants have been determined for adamantane using α-and β-[D]adamantane and the relation sup(n)J( 13 C, 1 H)=6,5144sup(n)J( 13 C, 2 H) for the conversion of the measured sup(n)J( 13 C, 2 H) values. It is shown that the magnitude of 3 Jsub(trans) is strongly influenced by the substitution pattern. Relative H,D isotope effects for 13 C chemical shifts are given. (orig.) [de

Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001).

Science.gov (United States)

Li, Lianbi; Zang, Yuan; Hu, Jichao; Lin, Shenghuang; Chen, Zhiming

2017-05-25

The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL) on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001) Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm², the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm². Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001

Directory of Open Access Journals (Sweden)

Lianbi Li

2017-05-01

Full Text Available The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001 Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 <21-1> at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm2, the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm2. Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

Redox-neutral rhodium-catalyzed C-H functionalization of arylamine N-oxides with diazo compounds: primary C(sp(3))-H/C(sp(2))-H activation and oxygen-atom transfer.

Science.gov (United States)

Zhou, Bing; Chen, Zhaoqiang; Yang, Yaxi; Ai, Wen; Tang, Huanyu; Wu, Yunxiang; Zhu, Weiliang; Li, Yuanchao

2015-10-05

An unprecedented rhodium(III)-catalyzed regioselective redox-neutral annulation reaction of 1-naphthylamine N-oxides with diazo compounds was developed to afford various biologically important 1H-benzo[g]indolines. This coupling reaction proceeds under mild reaction conditions and does not require external oxidants. The only by-products are dinitrogen and water. More significantly, this reaction represents the first example of dual functiaonalization of unactivated a primary C(sp(3) )H bond and C(sp(2) )H bond with diazocarbonyl compounds. DFT calculations revealed that an intermediate iminium is most likely involved in the catalytic cycle. Moreover, a rhodium(III)-catalyzed coupling of readily available tertiary aniline N-oxides with α-diazomalonates was also developed under external oxidant-free conditions to access various aminomandelic acid derivatives by an O-atom-transfer reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The murine choroid plexus epithelium expresses the 2Cl-/H+-exchanger ClC-7 and Na+/H+ exchanger NHE6 in the luminal membrane domain

DEFF Research Database (Denmark)

Damkier, Helle H; Christensen, Henriette L; Christensen, Inga B

2017-01-01

, but the pH value seems nonetheless maintained within narrow limits, even when faced with acid/base challenges. The involvement of choroid plexus acid/base transporters in CSF pH regulation is highlighted by the expression of several acid/base transporters in the epithelium. The aim of the current study...... was to identify novel acid/base transporters expressed in the luminal membrane of the choroid plexus epithelium to pave the way for systematic investigations of each candidate transporter in the regulation of CSF pH. Mass spectrometry analysis of proteins from epithelial cells isolated by fluorescence activated...... cell sorting identified the Cl-/H+ exchangers ClC-3, -4, -5, and -7 in addition to known choroid plexus acid/base transporters. RT-PCR on FACS isolated epithelial cells confirmed the expression of the corresponding mRNAs, as well as NHE6 mRNA. Both NHE6 and ClC-7 were immunolocalized to the luminal...

Compositional, structural and mechanical characteristics of nc-TiC/a-C:H nanocomposite films

International Nuclear Information System (INIS)

Wang Yaohui; Zhang Xu; Wu Xianying; Zhang Huixing; Zhang Xiaoji

2008-01-01

Nanocomposite nc-TiC/a-C:H films, with an unusual combination of superhardness, high elastic modulus and high elastic recovery, are prepared by filtered cathodic vacuum arc technique using the C 2 H 2 gas as the precursor. The effects of filter coil current on compositional, structural and mechanical properties of the nc-TiC/a-C:H films have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy disperse spectroscopy (EDS), microindentation and tribotester measurements. XPS and Raman analyses show that composition and nanostructure of the nc-TiC/a-C:H films can be changed by varying the filter coil current. By selecting the proper value of filter coil current, 2.5 A, one can remarkably enhance the mechanical properties of films such as superhardness (43.6 GPa). The superhardness can be ascribed to the phase variation and the nanostructure.

The HCClF_2-HCCH Complex: Microwave Spectrum, Structure and C-H\\cdotsπ Interactions

Science.gov (United States)

Peebles, Rebecca A.; Sexton, John M.; Elliott, Ashley A.; Steber, Amanda L.; Peebles, Sean A.; Neill, Justin L.; Muckle, Matt T.; Pate, Brooks H.

2010-06-01

The HCF_3-HCCH complex was recently found to have a weak C-H\\cdotsπ interaction between the fluoroform and acetylene, as well as having a secondary interaction between the fluorine atoms and one of the acetylene hydrogen atoms; however, extensive splittings due to large amplitude motions within the complex have complicated our efforts at making a full assignment of the HCF_3-HCCH spectrum. In an attempt to remove some of the ambiguity in the HCF_3-HCCH study, we have substituted a chlorine atom for one fluorine atom and undertaken an investigation of the HCClF_2-HCCH complex. This eliminates the possibility of internal rotation of the methane subunit, while still maintaining a C-H\\cdotsπ interaction. Using the chirped-pulse Fourier-transform microwave (CP-FTMW) spectrometer at the University of Virginia and the Balle-Flygare FTMW spectrometer at Eastern Illinois University, the spectra of four isotopologues of HCClF_2-HCCH have been assigned, with no indication of internal motions within the complex. The structure has been determined from the experimental moments of inertia, confirming that this dimer has the expected weak C-H\\cdotsπ interaction. In addition, the off-diagonal χab quadrupole coupling constant has been used to determine the angle between the C-Cl bond and the a-axis of the complex. This, and Kraitchman coordinates for the chlorine atom, help confirm the structural details from the inertial fit. The structural results will be compared with other complexes showing C-H\\cdotsπ and C-H\\cdotsO interactions. S. A. Peebles, M. M. Serafin, R. A. Peebles, 61st International Symposium on Molecular Spectroscopy, Talk MH13, June 19, 2006.

H2-H2O-HI Hydrogen Separation in H2-H2O-HI Gaseous Mixture Using the Silica Membrane

International Nuclear Information System (INIS)

Pandiangan, Tumpal

2002-01-01

It was evaluated aiming at the application for hydrogen iodide decomposition in the thermochemical lS process. Porous alumina tube having pore size of 0.1 μm was modified by chemical vapor deposition using tetraethoxysilane. The permeance single gas of He, H 2 , and N 2 was measured at 300-600 o C. Hydrogen permeance of the modified membrane at a permeation temperature of 600 o C was about 5.22 x 10 -08 mol/Pa m 2 s, and 3.2 x 10 -09 of using gas mixture of H 2 -H 2 O-HI, where as HI permeances was below 1 x 10 -10 mol/Pa m 2 s. The Hydrogen permeance relative was not changed after 25 hours exposure in a mixture of H 2 -H 2 O-HI gas at the temperature of 450 o C. (author)

Evaluation of mitomycin-C effect on biodistribution of {sup 99m}Tc-dimercaptosuccinic acid in BALB/C mice; Avaliacao do efeito da mitomicina-c na biodistribuicao do radiofarmaco acido dimercaptosuccinico marcado com tecnecio-99m em camundongos BALB/C

Energy Technology Data Exchange (ETDEWEB)

Gomes, Maria Luisa; Britto, Deise Mara de M.; Freitas, Rosimeire de S.; Bernardo-Filho, Mario [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil). Centro de Pesquisa Basica; Braga, Ana Cristina de S.; Bezerra, Roberto Jose A.C. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Biologia Roberto Alcantara Gomes. Dept. de Biofisica e Biometria

1999-11-01

The many desirable characteristics of technetium-99m have stimulated the development of labeling techniques for different molecular and cellular structures. It is accepted that a variety of factors such the drug chemotherapy can alter the biodistribution of radiopharmaceuticals. The unknowledge of these factor may result in an unexpected behavior of the radiopharmaceuticals. Since patients on chemotherapeutic treatment can be submitted to a nuclear medicine procedure, we have studied in mice, the effect of mitomycin-C on the {sup 99m} Tc-DMSA used for kidney scintigraphy. Mitomycin-C is an antineoplastic agent obtained from Streptomyces caesptosus. The metabolism of this drug produces different toxic and inactive metabolites. Mitomycin-C 0.15 mg was administered in Balb/c female with an interval of 72 hours. After one hour of the last dose, 0.3 ml of 9{sup 9m}c-DMSA (7.4 MBq) were injected and after 0.5 h the animals were sacrificed. The organs were isolated and counted in a well counter. The percentage of radioactivity (%ATI) were calculated and statistical analysis were performed (Wilcoxon Test). The results have shown that the %ATI: has increased in stomach and uterus, has decreased in kidney and ovary; has not altered in pancreas, spleen, lung, heart, liver, thymus, thyroid, bone and brain. The increase of % ATI could be justified by the metabolic process or the therapeutical effect of mitomycin-C. As an effect of this drug is observed in the uptake of the {sup 99m} Tc-DMSA by the kidney, probably an alteration in the kidney scintigraphy is expected. However, the increase of %ATI of this radiopharmaceutical in other organs by the mitomycin-C could be evaluated carefully. (author) 12 ref., 2 tabs.

Strongly coupled modes of M and H for perpendicular resonance

Science.gov (United States)

Sun, Chen; Saslow, Wayne M.

2018-05-01

We apply the equations for the magnetization M ⃗ and field H ⃗ to study their coupled modes for a semi-infinite ferromagnet, conductor, or insulator with magnetization M0 and field H0 normal to the plane (perpendicular resonance) and wave vector normal to the plane, which makes the modes doubly degenerate. With dimensionless damping constant α and dimensionless transverse susceptibility χ⊥=M0/He(He≡H0-M0) , we derive an analytic expression for the wave vector squared, showing that M ⃗ and H ⃗ are nearly decoupled only if α ≫χ⊥ . This is violated in the ferromagnetic regime, although a first correction is found to give good agreement away from resonance. Emphasizing the conductor permalloy as a function of H0 we study the eigenvalues and eigenmodes and the dissipation rate due to absorption both from the total effective field and from the Joule heating. (We include the contribution of the nonuniform exchange energy term, needed for energy conservation.) Using these modes we then apply, for a semi-infinite ferromagnet, a range of boundary conditions (i.e., surface anisotropies) on M⊥ to find the reflection coefficient R and the reflectivity |R| 2. As a function of H0, absorption is dominated by the the skin depth mode (primarily H ⃗) except near the resonance and at a higher-field Hd associated with a dip in the reflectivity, whose position above the main resonance varies quadratically with the surface anisotropy Ks. The dip is driven by the boundary condition on M ⃗; the coefficient of the (primarily) M ⃗ mode becomes very small at the dip, being compensated by an increase in the amplitude of the M ⃗ mode, which has a Lorentzian line shape of height ˜α-1 and width ˜α .

RIR MAPLE procedure for deposition of carbon rich Si/C/H films

International Nuclear Information System (INIS)

Dřínek, Vladislav; Strašák, Tomáš; Novotný, Filip; Fajgar, Radek; Bastl, Zdeněk

2014-01-01

We applied the resonant infrared matrix assisted pulsed laser evaporation (RIR MAPLE) technique to demonstrate a new approach to a controlled deposition of carbon rich amorphous Si/C/H film. In absence of radicals and accelerated species commonly generated in PECVD and sputtering setups, the RIR MAPLE method does not decompose precursor molecules. Moreover, unlike the standard MAPLE procedure, in which solvent molecules absorb laser energy from excimer or near infrared lasers, we applied the pulsed TEA CO 2 laser to excite the dendrimer precursor molecules in a frozen target. In this manner we achieved just cross-linking of the starting precursor on substrates and the deposition of carbon rich Si/C/H film. The film was analyzed by Fourier Transformed Infrared (FTIR), UV/VIS, Raman and X-ray Photoelectron (XPS) spectroscopy and Atomic Force Microscopy (AFM) technique. According to analyses the film retained the precursor elemental composition free of graphitic (sp 2 ) clusters. In course of reaction only the peripheral allyl groups containing C=C bonds were opened to achieve cross-linking. Whereas annealing to 300 °C was necessary for the elimination of =C–H 1 , 2 bonds in the films prepared at 200 °C, those bonds vanished completely for the films prepared at substrate temperature 255 °C. The film posseses a smooth surface with root mean square (RMS) parameter up to 10 nm within scanned distance 2.5 μm.

RIR MAPLE procedure for deposition of carbon rich Si/C/H films

Energy Technology Data Exchange (ETDEWEB)

Dřínek, Vladislav, E-mail: drinek@icpf.cas.cz [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojova 135, 165 02 Prague 6 (Czech Republic); Strašák, Tomáš [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojova 135, 165 02 Prague 6 (Czech Republic); Novotný, Filip [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, 115 19 Prague (Czech Republic); Fajgar, Radek [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojova 135, 165 02 Prague 6 (Czech Republic); Bastl, Zdeněk [J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i., Dolejškova 2155/3, 182 23 Prague 8 (Czech Republic)

2014-02-15

We applied the resonant infrared matrix assisted pulsed laser evaporation (RIR MAPLE) technique to demonstrate a new approach to a controlled deposition of carbon rich amorphous Si/C/H film. In absence of radicals and accelerated species commonly generated in PECVD and sputtering setups, the RIR MAPLE method does not decompose precursor molecules. Moreover, unlike the standard MAPLE procedure, in which solvent molecules absorb laser energy from excimer or near infrared lasers, we applied the pulsed TEA CO{sub 2} laser to excite the dendrimer precursor molecules in a frozen target. In this manner we achieved just cross-linking of the starting precursor on substrates and the deposition of carbon rich Si/C/H film. The film was analyzed by Fourier Transformed Infrared (FTIR), UV/VIS, Raman and X-ray Photoelectron (XPS) spectroscopy and Atomic Force Microscopy (AFM) technique. According to analyses the film retained the precursor elemental composition free of graphitic (sp{sup 2}) clusters. In course of reaction only the peripheral allyl groups containing C=C bonds were opened to achieve cross-linking. Whereas annealing to 300 °C was necessary for the elimination of =C–H{sub 1}, {sub 2} bonds in the films prepared at 200 °C, those bonds vanished completely for the films prepared at substrate temperature 255 °C. The film posseses a smooth surface with root mean square (RMS) parameter up to 10 nm within scanned distance 2.5 μm.

Non-Markovianity hinders Quantum Darwinism

Science.gov (United States)

Galve, Fernando; Zambrini, Roberta; Maniscalco, Sabrina

2016-01-01

We investigate Quantum Darwinism and the emergence of a classical world from the quantum one in connection with the spectral properties of the environment. We use a microscopic model of quantum environment in which, by changing a simple system parameter, we can modify the information back flow from environment into the system, and therefore its non-Markovian character. We show that the presence of memory effects hinders the emergence of classical objective reality, linking these two apparently unrelated concepts via a unique dynamical feature related to decoherence factors.

The synthesis of Org 3770 labelled with 3H, 13C and 14C

International Nuclear Information System (INIS)

Kaspersen, F.M.; Rooij, F.A.M. van; Sperling, E.G.M.; Wieringa, J.H.

1989-01-01

The syntheses of 1,2,3,4,10,14b-hexahydro-2-methylpyrazino[2,1-a]pyrido[2,3-c][2]benazepine (Org 3770) labelled with 3 H (and 2 H), 13 C and 14 C are described. Tritiated Org 3770 was prepared either by exchange under alkaline conditions with tritiated water or catalytic reductive dehalogenation of a chloro analogue with 3 H 2 . 13 C-labelled material was obtained in a seven-step synthesis starting from 13 C-labelled benzene whereas 14 C-Org 3770 was prepared in a three-step synthesis starting with 14 CO 2 . All labelled compounds were analyzed by TLC, HPLC, MS and NMR. (author)

M6-C artificial disc placement.

Science.gov (United States)

Coric, Domagoj; Parish, John; Boltes, Margaret O

2017-01-01

There has been a steady evolution of cervical total disc replacement (TDR) devices over the last decade resulting in surgical technique that closely mimics anterior cervical discectomy and fusion as well as disc design that emphasizes quality of motion. The M6-C TDR device is a modern-generation artificial disc composed of titanium endplates with tri-keel fixation as well as a polyethylene weave with a polyurethane core. Although not yet approved by the FDA, M6-C has finished a pilot and pivotal US Investigational Device Exemption (IDE) study. The authors present the surgical technique for implantation of a 2-level M6-C cervical TDR device. The video can be found here: https://youtu.be/rFEAqINLRCo .

Biochemical Characterization of Mycobacterium smegmatis RnhC (MSMEG_4305), a Bifunctional Enzyme Composed of Autonomous N-Terminal Type I RNase H and C-Terminal Acid Phosphatase Domains.

Science.gov (United States)

Jacewicz, Agata; Shuman, Stewart

2015-08-01

Mycobacterium smegmatis encodes several DNA repair polymerases that are adept at incorporating ribonucleotides, which raises questions about how ribonucleotides in DNA are sensed and removed. RNase H enzymes, of which M. smegmatis encodes four, are strong candidates for a surveillance role. Here, we interrogate the biochemical activity and nucleic acid substrate specificity of M. smegmatis RnhC, a bifunctional RNase H and acid phosphatase. We report that (i) the RnhC nuclease is stringently specific for RNA:DNA hybrid duplexes; (ii) RnhC does not selectively recognize and cleave DNA-RNA or RNA-DNA junctions in duplex nucleic acid; (iii) RnhC cannot incise an embedded monoribonucleotide or diribonucleotide in duplex DNA; (iv) RnhC can incise tracts of 4 or more ribonucleotides embedded in duplex DNA, leaving two or more residual ribonucleotides at the cleaved 3'-OH end and at least one or two ribonucleotides on the 5'-PO4 end; (v) the RNase H activity is inherent in an autonomous 140-amino-acid (aa) N-terminal domain of RnhC; and (vi) the C-terminal 211-aa domain of RnhC is an autonomous acid phosphatase. The cleavage specificity of RnhC is clearly distinct from that of Escherichia coli RNase H2, which selectively incises at an RNA-DNA junction. Thus, we classify RnhC as a type I RNase H. The properties of RnhC are consistent with a role in Okazaki fragment RNA primer removal or in surveillance of oligoribonucleotide tracts embedded in DNA but not in excision repair of single misincorporated ribonucleotides. RNase H enzymes help cleanse the genome of ribonucleotides that are present either as ribotracts (e.g., RNA primers) or as single ribonucleotides embedded in duplex DNA. Mycobacterium smegmatis encodes four RNase H proteins, including RnhC, which is characterized in this study. The nucleic acid substrate and cleavage site specificities of RnhC are consistent with a role in initiating the removal of ribotracts but not in single-ribonucleotide surveillance. RnhC

Breakdown of the Coulomb friction law in TiC/a-C : H nanocomposite coatings

NARCIS (Netherlands)

Pei, Y.T.; Huizenga, P.; Galvan, D.; Hosson, J.Th.M. De

2006-01-01

Advanced TiC/a-C:H nanocomposite coatings have been produced via reactive deposition in a closed-field unbalanced magnetron sputtering system (Hauzer HTC-1000 or HTC 1200). In this paper, we report on the tribological behavior of TiC/a-C:H nanocomposite coatings in which ultralow friction is

Multiscale investigation of graphene layers on 6H-SiC(000-1)

OpenAIRE

Tiberj, Antoine; Huntzinger, Jean-Roch; Camassel, Jean; Hiebel, Fanny; Mahmood, Ather; Mallet, Pierre; Naud, Cecile; Veuillen, Jean-Yves

2011-01-01

Abstract In this article, a multiscale investigation of few graphene layers grown on 6H-SiC(000-1) under ultrahigh vacuum (UHV) conditions is presented. At 100-μm scale, the authors show that the UHV growth yields few layer graphene (FLG) with an average thickness given by Auger spectroscopy between 1 and 2 graphene planes. At the same scale, electron diffraction reveals a significant rotational disorder between the first graphene layer and the SiC surface, although well-defined preferre...

Bis(arene) actinide sandwich complexes, (η6-C6H3R3)2An: Linear or bent?

International Nuclear Information System (INIS)

Li, J.; Bursten, B.E.

1999-01-01

The syntheses of the sandwich complexes ferrocene, (η 5 -C 5 H 5 ) 2 -Fe, in 1951 and uranocene, (η 8 -C 8 H 8 ) 2 U, in 1968 ushered in the modern eras of organotransition metal and organoactinide chemistry, respectively. Ferrocene and uranocene are examples of linear sandwich complexes, that is, those in which the (ring centroid)-M-(ring centroid) angle (denoted θ) is 180 degree. In the case of (η 5 -C 5 H 5 ) 2 M chemistry, a number of bent (θ 2 An (An = Th-Am) and (η 6 -C 6 H 3 R 3 ) 2 An (An = Th, U, Pu; R = Me, t Bu) obtained by using local density approximation (LDA) and Perdew-Wang (PW91) gradient-corrected relativistic density functional theory (DFT) methods. These DFT methods are found to be able to reproduce the experimental geometries and vibrational frequencies of organoactinide complexes with satisfactory accuracy. The (TTB) 2 An calculations that are reported here are, to date, the largest full geometry optimizations to be carried out on an actinide system

Survivors of Downsizing: Helpful and Hindering Experiences

Science.gov (United States)

Amundson, Norman E.; Borgen, William A.; Jordan, Sharalyn; Erlebach, Anne C.

2004-01-01

Thirty-one downsizing survivors from both the private and public sector were interviewed to determine incidents that either helped or hindered their transition through 1 or more organizational downsizings. A critical incident technique was used to analyze and organize the data around themes that emerged, themes were represented by both positive…

When Higher Working Memory Capacity Hinders Insight

Science.gov (United States)

DeCaro, Marci S.; Van Stockum, Charles A., Jr.; Wieth, Mareike B.

2016-01-01

Higher working memory capacity (WMC) improves performance on a range of cognitive and academic tasks. However, a greater ability to control attention sometimes leads individuals with higher WMC to persist in using complex, attention-demanding approaches that are suboptimal for a given task. We examined whether higher WMC would hinder insight…

Aging of oxygen and hydrogen plasma discharge treated a-C:H and ta-C coatings

Energy Technology Data Exchange (ETDEWEB)

Bachmann, Svenja [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); BMW Group, Hufelandstraße 4, 80788 Munich (Germany); Schulze, Marcus [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); Morasch, Jan [Institute of Materials Science, Technische Universität Darmstadt, Surface Science Division, Jovanka-Bonschits-Straße 2, 64287 Darmstadt (Germany); Hesse, Sabine [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); Hussein, Laith [Eduard-Zintl-Institut, Department of Chemistry, Technische Universität Darmstadt, Alarich-Weiss-Str. 12, 64287, Darmstadt (Germany); Krell, Lisa; Schnagl, Johann [BMW Group, Hufelandstraße 4, 80788 Munich (Germany); Stark, Robert W. [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); and others

2016-05-15

Highlights: • The water CA of O{sub 2} and H{sub 2} plasma treated a-C:H and ta-C changes from hydrophillic to hydrophobic on aging. • XPS study indicates that the decrease in surface energy of plasma treated a-C:H and ta-C could be due to adsorption of organic component from air. • The COFLFM of O{sub 2} and H{sub 2} plasma treated a-C:H and ta-C decreased upon aging. • The COF of glycerol lubricated ta-C showed no sign of change upon aging. - Abstract: Surface modification with gas plasma is an efficient and easy way to improve the surface energy and the tribological behavior of diamond-like carbon (DLC) coatings, e.g., in biomedical implants or as protective coatings. However, the long-term performance of the plasma treated DLC coatings is not fully clear. We thus studied the long-term stability of two kinds of DLC coatings, namely (a) hydrogenated amorphous carbon (a-C:H) and (b) tetrahedral amorphous carbon (ta-C) treated at different radio frequency (RF) power and time of oxygen (O{sub 2}) and hydrogen (H{sub 2}) plasma. Their surface properties, e.g. surface wettability, structure and tribological behavior, were studied at regular intervals for a period of two months using contact angle goniometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), lateral force microscopy (LFM) and ball on disc apparatus. The surface energy of both the coatings decreased upon aging. The higher the RF power and time of treatment, the higher was the hydrophobicity upon aging. XPS analysis showed that the increase in hydrophobicity could be due to adsorption of unavoidable volatile organic components in the atmosphere. The H{sub 2} plasma treated ta-C was capable of rearranging its structural bonds upon aging. The nano-friction measurements by LFM showed that the coefficient of friction of plasma treated a-C:H and ta-C decreased upon aging. The results indicate that the surface properties of plasma treated a‐C:H and ta‐C are not stable on long-term and are

Alkane Activation at Ambient Temperatures: Unusual Selectivities, C-C, C-H Bond Scission versus C-C Bond Coupling

NARCIS (Netherlands)

Trionfetti, C.; Agiral, A.; Gardeniers, Johannes G.E.; Lefferts, Leonardus; Seshan, Kulathuiyer

2008-01-01

Activating bonds: A cold plasma generated by dielectric barrier discharge in a microreactor converts alkanes (C1–C3) at atmospheric pressure. Large amounts of products with higher molecular weight than the starting hydrocarbons are observed showing that C-H activation at lower T favourably leads to

Protective Effects of Moringa oleifera on HBV Genotypes C and H Transiently Transfected Huh7 Cells

Science.gov (United States)

Feustel, Sina; Ayón-Pérez, Fabiola; Sandoval-Rodriguez, Ana; Rodríguez-Echevarría, Roberto; Contreras-Salinas, Homero

2017-01-01

Chronic hepatitis B infection treatment implicates a long-lasting treatment. M. oleifera extracts contain compounds with antiviral, antioxidant, and antifibrotic properties. In this study, the effect of M. oleifera was evaluated in Huh7 cells expressing either HBV genotypes C or H for the antiviral, antifibrotic, anti-inflammatory, and antioxidative responses. Huh7 cells were treated with an aqueous extract of M. oleifera (leaves) at doses of 0, 30, 45, or 60 μg/mL. The replicative virus and TGF-β1, CTGF, CAT, IFN-β1, and pgRNA expressions were measured by real time. HBsAg and IL-6 titers were determined by ELISA. CTGF, TGF-β1, IFN-β1, and pgRNA expressions decreased with M. oleifera treatment irrespective of the HBV genotype. HBsAg secretion in the supernatant of transfected Huh7 cells with both HBV genotypes was decreased regardless of the dose of M. oleifera. Similar effect was observed in proinflammatory cytokine IL-6, which had a tendency to decrease at 24 hours of treatment. Transfection with both HBV genotypes strongly decreased CAT expression, which is retrieved with M. oleifera treatment. M. oleifera treatment reduced fibrosis markers, IL-6, and HBsAg secretion in HBV genotypes C and H. However, at the level of replication, only HBV-DNA genotype C was slightly reduced with this treatment. PMID:29214184

A polysaccharide of Dendrobium officinale ameliorates H2O2-induced apoptosis in H9c2 cardiomyocytes via PI3K/AKT and MAPK pathways.

Science.gov (United States)

Zhang, Jing-Yi; Guo, Ying; Si, Jin-Ping; Sun, Xiao-Bo; Sun, Gui-Bo; Liu, Jing-Jing

2017-11-01

Dendrobium officinale is one valuable traditional Chinese medicine, which has skyscraping medicinal value. Polysaccharide is the main active ingredient in D. officinale; its antioxidant activity is a hot research topic nowadays. Oxidative stress plays an important role in the pathological progress of a variety of cardiovascular disease, as one of key factors of cardiomyocyte apoptosis. This research adopts a model of H 2 O 2 induction-H9c2 cardiomyocytes apoptosis, aiming to study the effect of Dendrobium officinale Polysaccharide (DOP-GY) for cardiomyocyte apoptosis caused by oxidative stress and its possible mechanism. Our results showed that pretreatment of DOP-GY (low dose: 6.25μg/mL, medium dose: 12.5μg/mL, high dose: 25μg/mL) followed by a 2h incubation with 200μM H 2 O 2 elevated the survival rate, cutted the LDH leakage, reduced lipid peroxidation damage, improved the activity of the endogenous antioxidant enzymes. In addition, the pretreatment of DOP-GY significantly inhibited the production of ROS, declined of the mitochondrial membrane potential, down-regulated pro-apoptosis protein and up-regulated anti-apoptosis protein. The protective effect was correlated with the PI3K/Akt and MAPK signal pathway. Collectively, these observations suggest that DOY-GY has the potential to exert cardioprotective effects against H 2 O 2 -induced H9c2 cardiomyocyte apoptosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Multiscale investigation of graphene layers on 6H-SiC(000-1

Directory of Open Access Journals (Sweden)

Hiebel Fanny

2011-01-01

Full Text Available Abstract In this article, a multiscale investigation of few graphene layers grown on 6H-SiC(000-1 under ultrahigh vacuum (UHV conditions is presented. At 100-μm scale, the authors show that the UHV growth yields few layer graphene (FLG with an average thickness given by Auger spectroscopy between 1 and 2 graphene planes. At the same scale, electron diffraction reveals a significant rotational disorder between the first graphene layer and the SiC surface, although well-defined preferred orientations exist. This is confirmed at the nanometer scale by scanning tunneling microscopy (STM. Finally, STM (at the nm scale and Raman spectroscopy (at the μm scale show that the FLG stacking is turbostratic, and that the domain size of the crystallites ranges from 10 to 100 nm. The most striking result is that the FLGs experience a strong compressive stress that is seldom observed for graphene grown on the C face of SiC substrates.

Electrically active defects in n-type 4H- and 6H-SiC

Energy Technology Data Exchange (ETDEWEB)

Doyle, J.P. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics]|[IBM Research Div., T.J. Watson Research Center, Yorktown Heights, NY (United States); Aboelfotoh, M.O. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics]|[North Carolina State Univ., Dept. of Materials Science and Engineering, Raleigh, NC (United States); Svensson, B.G. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid State Electronics

1998-06-01

We have found that in 6H-SiC, irradiation induced defects can become mobile at temperatures as low as 200 C. Through isochronal and isothermal annealing a level at 0.51 eV below the conduction band (with a capture cross-section of 2 x 10{sup -14} cm{sup 2}), appears to disassociate through a first order process with an activation energy of 1.45 eV+/-0.1 eV. In 4H-SiC, we have observed two irradiation induced defects assigned the positions 0.62 eV and 0.68 eV below E{sub c} (with capture cross-sections of 4 x 10{sup -14} cm{sup 2} and 5 x 10{sup -15} cm{sup 2}, respectively) which are found to be unstable at room temperature with time. SIMS analysis indicates that in both 6H- and 4H-SiC the defect levels are not due to the incorporation of the transition metals Ti, V, or Cr. Additionally, in both polytypes of SiC that were examined, the defects are found to display acceptor-like behavior as no evidence of a Poole-Frenkel shift was observed during DLTS measurements. (orig.) 10 refs.

Radiosensitization of C225 on human non-small cell lung cancer cell line H-520

International Nuclear Information System (INIS)

Zhang Yingdong; Wang Junjie; Liu Feng; Zhao Yong

2008-01-01

Objective: To investigate the efficacy of C225 (cetuximab), a chimeric human-mouse anti-epithelial growth factor receptor monoclonal antibody, combined with 60 Co gamma irradiation against human non-small cell lung cancer cell line H-520. Methods: H-520 cells were treated either with different dose of 60 Co irradiation (1,2,4,6,8 and 10 Gy)alone or together with C225 (100 nmol/L). Colony forming capacity was determined to create the survival curve 10 days after the treatment. Cells in different groups were harvested 72 hours after irradiation for apoptosis analysis or 48 hours after irradiation for cell cycle analysis by flow cytometry assay. Results: The clone number in combinational treatment group was less than that in irradiation only group, which suggested that the cell survival rate in the combinational treatment group was significantly decreased comparing with irradiation only group (F=6.36, P O + G 1 phases for C225 treatment, in G 2 + M phases for 60 Co irradiation, and in both G 0 + G 1 and G 2 + M phases for C225 in combination with 60 Co irradiation. Conclusions: C225 has radiosensitizing effects on H-520 cells, which may through the enhancement of 60 Co irradiation-induced cell death and cell cycle arrest. This study provides a supportive evidence for clinical treatment in non-small cell lung cancer. (authors)

Trivalent metallocene chemistry of some uranium, titanium, and zirconium complexes

Energy Technology Data Exchange (ETDEWEB)

Lukens, Jr., Wayne Wendell [Univ. of California, Berkeley, CA (United States)

1995-05-01

Dicyclopentadienyluranium halide dimers have been prepared and their solution behavior examined. These molecules exist as dimers in solution, and the halide ligands undergo rapid site exchange on the NMR timescale above 50 C. Analogous dicyclopentadienyluranium hydroxide dimers have also been prepared; they oxidatively eliminate hydrogen to give the corresponding oxide dimers. Mechanism of this reaction is consistent with αmigration of one of the hydroxide hydrogen atoms to a uranium center followed by elimination of hydrogen. Ground state of [(Me₃Si)₂C₅H₃]₃M M = Nd, U and their base adducts has been examined by variable temperature magnetic susceptibility and EPR spectroscopy. The ground state is found to be ⁴I_9/2 with a crystal field state consisting largely of J_z = 1/2 lowest, in agreement with previous studies on tris-cyclopentadienylneodymium complexes. The zirconium metallocene Cp₃Zr has been prepared, characterized crystallographically, and its reactivity studied. Its chemical behavior is controlled by presence of an electron in the non-bonding, d_z2 orbital which prevents formation of base adducts Of Cp₃Zr, but allows Cp₃Zr to abstract atoms from other molecules. Electonic and EPR spectra of Cp*₂TiX complexes, where Cp* is Me₅C₅ and X is a monodentate, anionic ligand such as halide, have been studied. A π-bonding spectrochemical series is developed, and trends in π-bonding ability are found similar to those in other inorganic complexes. The β-agostic interactions in Cp*₂TiN(Me)Ph have been examined using variable temperature EPR spectroscopy, and the enthalpy/entropy of the interaction determined. In Cp*₂TiEt, enthalpy of the β-agostic interaction is -1.9 kcal/mol. The titanocene anion, Cp*₂TiLi(TMEDA) (TMEDA is N,N,N`,N`-tetramethylethylenediamine), has been

Cleavage of sp3 C-O bonds via oxidative addition of C-H bonds.

Science.gov (United States)

Choi, Jongwook; Choliy, Yuriy; Zhang, Xiawei; Emge, Thomas J; Krogh-Jespersen, Karsten; Goldman, Alan S

2009-11-04

(PCP)Ir (PCP = kappa(3)-C(6)H(3)-2,6-[CH(2)P(t-Bu)(2)](2)) is found to undergo oxidative addition of the methyl-oxygen bond of electron-poor methyl aryl ethers, including methoxy-3,5-bis(trifluoromethyl)benzene and methoxypentafluorobenzene, to give the corresponding aryloxide complexes (PCP)Ir(CH(3))(OAr). Although the net reaction is insertion of the Ir center into the C-O bond, density functional theory (DFT) calculations and a significant kinetic isotope effect [k(CH(3))(OAr)/k(CD(3))(OAr) = 4.3(3)] strongly argue against a simple insertion mechanism and in favor of a pathway involving C-H addition and alpha-migration of the OAr group to give a methylene complex followed by hydride-to-methylene migration to give the observed product. Ethoxy aryl ethers, including ethoxybenzene, also undergo C-O bond cleavage by (PCP)Ir, but the net reaction in this case is 1,2-elimination of ArO-H to give (PCP)Ir(H)(OAr) and ethylene. DFT calculations point to a low-barrier pathway for this reaction that proceeds through C-H addition of the ethoxy methyl group followed by beta-aryl oxide elimination and loss of ethylene. Thus, both of these distinct C-O cleavage reactions proceed via initial addition of a C(sp(3))-H bond, despite the fact that such bonds are typically considered inert and are much stronger than C-O bonds.

Quantified pH imaging with hyperpolarized (13) C-bicarbonate.

Science.gov (United States)

Scholz, David Johannes; Janich, Martin A; Köllisch, Ulrich; Schulte, Rolf F; Ardenkjaer-Larsen, Jan H; Frank, Annette; Haase, Axel; Schwaiger, Markus; Menzel, Marion I

2015-06-01

Because pH plays a crucial role in several diseases, it is desirable to measure pH in vivo noninvasively and in a spatially localized manner. Spatial maps of pH were quantified in vitro, with a focus on method-based errors, and applied in vivo. In vitro and in vivo (13) C mapping were performed for various flip angles for bicarbonate (BiC) and CO2 with spectral-spatial excitation and spiral readout in healthy Lewis rats in five slices. Acute subcutaneous sterile inflammation was induced with Concanavalin A in the right leg of Buffalo rats. pH and proton images were measured 2 h after induction. After optimizing the signal to noise ratio of the hyperpolarized (13) C-bicarbonate, error estimation of the spectral-spatial excited spectrum reveals that the method covers the biologically relevant pH range of 6 to 8 with low pH error (< 0.2). Quantification of pH maps shows negligible impact of the residual bicarbonate signal. pH maps reflect the induction of acute metabolic alkalosis. Inflamed, infected regions exhibit lower pH. Hyperpolarized (13) C-bicarbonate pH mapping was shown to be sensitive in the biologically relevant pH range. The mapping of pH was applied to healthy in vivo organs and interpreted within inflammation and acute metabolic alkalosis models. © 2014 Wiley Periodicals, Inc.

The 3H(α,γ)7Li reaction below Ec.m. = 1 MeV

International Nuclear Information System (INIS)

Brune, C.R.; Kavanagh, R.W.; Rolfs, C.

1993-01-01

The 3 H(α,γ) reaction, and its mirror 3 He(α,γ) are responsible for 7 Li production in the big bang. It has been demonstrated that the uncertainty in the 3 H(α,γ) reaction rate significantly affects the calculated amount of 7 Li, which is important for comparison to the observed 7 Li abundance and constraining the baryon density allowed by the standard big-bang model. Using specially prepared thin Ti- 3 H targets and an 85% high-purity germanium detector, the authors have measured the γ rays produced by the 3 H(α,γ) reaction for 50 c.m. 7 Li bound states, and angular distributions of the capture γ rays. The results are compared to previous experiments and nuclear model calculations

New type of M23C6 carbide precipitation in an austenitic stainless steel containing niobium

International Nuclear Information System (INIS)

Terao, Nobuzo; Sasmal, B.

1981-01-01

An electron microscopic study has been made of precipitation in an austenitic stainless steel, 16Cr-16Ni-0.8Nb-1.8Mo-0.06C. Attention has been focused on structural changes which take place during long ageing treatments, extended up to 14.4 Ms (4000 h). In addition to the wellknown chromium rich M 23 C 6 carbides, which appear, together with NbC, from the beginning of the precipitation treatment at 1073 K, a new plate-like morphology of M 23 C 6 carbide precipitation was observed after long ageing treatments. These M 23 C 6 carbide plates were formed on (110) planes in regions near pre-existing undissolved NbC particles and their edges were bounded by (111) planes of the fcc alloy matrix. It is suggested that this unexpected process might be favoured by the stresses produced around the undissolved NbC particles. (author)

Effect of the CO2/SiH4 Ratio in the p-μc-SiO:H Emitter Layer on the Performance of Crystalline Silicon Heterojunction Solar Cells

Directory of Open Access Journals (Sweden)

Jaran Sritharathikhun

2014-01-01

Full Text Available This paper reports the preparation of wide gap p-type hydrogenated microcrystalline silicon oxide (p-μc-SiO:H films using a 40 MHz very high frequency plasma enhanced chemical vapor deposition technique. The reported work focused on the effects of the CO2/SiH4 ratio on the properties of p-μc-SiO:H films and the effectiveness of the films as an emitter layer of crystalline silicon heterojunction (c-Si-HJ solar cells. A p-μc-SiO:H film with a wide optical band gap (E04, 2.1 eV, can be obtained by increasing the CO2/SiH4 ratio; however, the tradeoff between E04 and dark conductivity must be considered. The CO2/SiH4 ratio of the p-μc-SiO:H emitter layer also significantly affects the performance of the solar cells. Compared to the cell using p-μc-Si:H (CO2/SiH4 = 0, the cell with the p-μc-SiO:H emitter layer performs more efficiently. We have achieved the highest efficiency of 18.3% with an open-circuit voltage (Voc of 692 mV from the cell using the p-μc-SiO:H layer. The enhancement in the Voc and the efficiency of the solar cells verified the potential of the p-μc-SiO:H films for use as the emitter layer in c-Si-HJ solar cells.

Sequence Variations in the Flagellar Antigen Genes fliC H25 and fliC H28 of Escherichia coli and Their Use in Identification and Characterization of Enterohemorrhagic E. coli (EHEC) O145:H25 and O145:H28

Science.gov (United States)

Beutin, Lothar; Delannoy, Sabine; Fach, Patrick

2015-01-01

Enterohemorrhagic E. coli (EHEC) serogroup O145 is regarded as one of the major EHEC serogroups involved in severe infections in humans. EHEC O145 encompasses motile and non-motile strains of serotypes O145:H25 and O145:H28. Sequencing the fliC-genes associated with the flagellar antigens H25 and H28 revealed the genetic diversity of the fliC H25 and fliC H28 gene sequences in E. coli. Based on allele discrimination of these fliC-genes real-time PCR tests were designed for identification of EHEC O145:H25 and O145:H28. The fliC H25 genes present in O145:H25 were found to be very similar to those present in E. coli serogroups O2, O100, O165, O172 and O177 pointing to their common evolution but were different from fliC H25 genes of a multiple number of other E. coli serotypes. In a similar way, EHEC O145:H28 harbor a characteristic fliC H28 allele which, apart from EHEC O145:H28, was only found in enteropathogenic (EPEC) O28:H28 strains that shared some common traits with EHEC O145:H28. The real time PCR-assays targeting these fliC H25[O145] and fliC H28[O145] alleles allow better characterization of EHEC O145:H25 and EHEC O145:H28. Evaluation of these PCR assays in spiked ready-to eat salad samples resulted in specific detection of both types of EHEC O145 strains even when low spiking levels of 1–10 cfu/g were used. Furthermore these PCR assays allowed identification of non-motile E. coli strains which are serologically not typable for their H-antigens. The combined use of O-antigen genotyping (O145wzy) and detection of the respective fliC H25[O145] and fliC H28[O145] allele types contributes to improve identification and molecular serotyping of E. coli O145 isolates. PMID:26000885

Solvothermal synthesis and characterisation of new one-dimensional indium and gallium sulphides: [C1N4H26]0.5[InS2] and [C1N4H26]0.5[GaS2

International Nuclear Information System (INIS)

Vaqueiro, Paz

2006-01-01

Two new main group metal sulphides, [C 1 N 4 H 26 ] 0.5 [InS 2 ] (1) and [C 1 N 4 H 26 ] 0.5 [GaS 2 ] (2) have been prepared solvothermally in the presence of 1,4-bis(3-aminopropyl)piperazine and their crystal structures determined by single-crystal X-ray diffraction. Both compounds are isostructural and crystallise in the monoclinic space group P2 1 /n (Z=4), with a=6.5628(5), b=11.2008(9), c=12.6611(9) A and β=94.410(4) o (wR=0.035) for compound (1) and a=6.1094(5), b=11.2469(9), c=12.7064(10) A and β=94.313(4) o (wR=0.021) for compound (2). The structure of [C 1 N 4 H 26 ] 0.5 [MS 2 ] (M=In,Ga) consists of one-dimensional [MS 2 ] - chains which run parallel to the crystallographic a axis and are separated by diprotonated amine molecules. These materials represent the first example of solvothermally prepared one-dimensional gallium and indium sulphides. -- Graphical abstract: [C 1 N 4 H 26 ] 0.5 [InS 2 ] and [C 1 N 4 H 26 ] 0.5 [GaS 2 ], prepared under solvothermal conditions, consist of one-dimensional [MS 2 ] - chains separated by diprotonated 1,4-bis(3-aminopropyl)piperazine molecules

Characterization of a n+3C/n−4H SiC heterojunction diode

Energy Technology Data Exchange (ETDEWEB)

Minamisawa, R. A.; Mihaila, A. [Department of Power Electronics, ABB Corporate Research Center, CH-5405 Baden-Dättwil (Switzerland); Farkas, I.; Hsu, C.-W.; Janzén, E. [Semiconductor Materials, IFM, Linköping University, SE-58183 Linköping (Sweden); Teodorescu, V. S. [National Institute of Material Physics, R-077125 Bucharest-Măgurele (Romania); Afanas' ev, V. V. [Semiconductor Physics Laboratory, KU Leuven, 3001 Leuven (Belgium); Rahimo, M. [ABB Semiconductors, Fabrikstrasse 3, CH-5600 Lenzburg (Switzerland)

2016-04-04

We report on the fabrication of n + 3C/n-4H SiC heterojunction diodes (HJDs) potentially promising the ultimate thermal stability of the junction. The diodes were systematically analyzed by TEM, X-ray diffraction, AFM, and secondary ion mass spectroscopy, indicating the formation of epitaxial 3C-SiC crystal on top of 4H-SiC substrate with continuous interface, low surface roughness, and up to ∼7 × 10{sup 17 }cm{sup −3} dopant impurity concentration. The conduction band off-set is about 1 V as extracted from CV measurements, while the valence bands of both SiC polytypes are aligned. The HJDs feature opening voltage of 1.65 V, consistent with the barrier height of about 1.5 eV extracted from CV measurement. We finally compare the electrical results of the n + 3C/n-4H SiC heterojunction diodes with those featuring Si and Ge doped anodes in order to evaluate current challenges involved in the fabrication of such devices.

H I CLOUDS IN THE M81 FILAMENT AS DARK MATTER MINIHALOS-A PHASE-SPACE MISMATCH

International Nuclear Information System (INIS)

Chynoweth, Katie M.; Langston, Glen I.; Holley-Bockelmann, Kelly

2011-01-01

Cosmological galaxy formation models predict the existence of dark matter minihalos surrounding galaxies and in filaments connecting groups of galaxies. The more massive of these minihalos are predicted to host H I gas that should be detectable by current radio telescopes such as the Robert C. Byrd Green Bank Telescope (GBT). We observed the region including the M81/M82 and NGC 2403 galaxy groups, searching for observational evidence of an H I component associated with dark matter halos within the 'M81 Filament', using the GBT. The map covers an 8. 0 7 x 21. 0 3 (480 kpc x 1.2 Mpc) region centered between the M81/M82 and NGC 2403 galaxy groups. Our observations cover a wide velocity range, from -890 to 1320 km s -1 , which spans much of the range predicted by cosmological N-body simulations for dark matter minihalo velocities. Our search is not complete in the velocity range -210 to 85 km s -1 , containing Galactic emission and the HVC Complex A. For an H I cloud at the distance of M81, with a size ≤10 kpc, our average 5σ mass detection limit is 3.2 x 10 6 M sun , for a linewidth of 20 km s -1 . We compare our observations to two large cosmological N-body simulations and find that the simulation predicts a significantly greater number of detectable minihalos than are found in our observations, and that the simulated minihalos do not match the phase space of observed H I clouds. These results place strong constraints on the H I gas that can be associated with dark matter halos. Our observations indicate that the majority of extragalactic H I clouds with a mass greater than 10 6 M sun are likely to be generated through tidal stripping caused by galaxy interactions.

Cluster-enhanced X-O-2 photochemistry (X=CH3I, C3H6, C6H12, and Xe)

NARCIS (Netherlands)

Baklanov, A.V.; Bogdanchikov, G.A.; Vidma, K.V.; Chestakov, D.A.; Parker, D.H.

2007-01-01

The effect of a local environment on the photodissociation of molecular oxygen is investigated in the van der Waals complex X-O-2 (X=CH3I, C3H6, C6H12, and Xe). A single laser operating at wavelengths around 226 nm is used for both photodissociation of the van der Waals complex and simultaneous

Metal-free oxidative olefination of primary amines with benzylic C-H bonds through direct deamination and C-H bond activation.

Science.gov (United States)

Gong, Liang; Xing, Li-Juan; Xu, Tong; Zhu, Xue-Ping; Zhou, Wen; Kang, Ning; Wang, Bin

2014-09-14

An oxidative olefination reaction between aliphatic primary amines and benzylic sp(3) C-H bonds has been achieved using N-bromosuccinimide as catalyst and tert-butyl hydroperoxide as oxidant. The olefination proceeds under mild metal-free conditions through direct deamination and benzylic C-H bond activation, and provides easy access to biologically active 2-styrylquinolines with (E)-configuration.

Bauhinia championii Flavone Attenuates Hypoxia-Reoxygenation Induced Apoptosis in H9c2 Cardiomyocytes by Improving Mitochondrial Dysfunction.

Science.gov (United States)

Liao, Ping; Sun, Guibo; Zhang, Chan; Wang, Min; Sun, Yao; Zhou, Yuehan; Sun, Xiaobo; Jian, Jie

2016-11-04

This study aimed to determine the effects of Bauhinia championii flavone (BCF) on hypoxia-reoxygenation (H/R) induced apoptosis in H9c2 cardiomyocytes and to explore potential mechanisms. The H/R model in H9c2 cardiomyocytes was established by 6 h of hypoxia and 12 h of reoxygenation. Cell viability was detected by CCK-8 assay. Apoptotic rate was measured by Annexin V/PI staining. Levels of mitochondria-associated ROS, mitochondrial transmembrane potential (∆Ψm) and mitochondrial permeability transition pores (MPTP) opening were assessed by fluorescent probes. ATP production was measured by ATP assay kit. The release of cytochrome c, translocation of Bax, and related proteins were measured by western blotting. Our results showed that pretreatment with BCF significantly improved cell viability and attenuated the cardiomyocyte apoptosis caused by H/R. Furthermore, BCF increased ATP production and inhibited ROS-generating mitochondria, depolarization of ΔΨm, and MPTP opening. Moreover, BCF pretreatment decreased Bax mitochondrial translocation, cytochrome c release, and activation of caspase-3, as well as increased the expression of p-PI3K, p-Akt, and the ratio of Bcl-2 to Bax. Interestingly, a specific inhibitor of phosphatidylinositol 3-kinase, LY294002, partly reversed the anti-apoptotic effect of BCF. These observations indicated that BCF pretreatment attenuates H/R-induced myocardial apoptosis strength by improving mitochondrial dysfunction via PI3K/Akt signaling pathway.

Study of the hydrogen behavior in amorphous hydrogenated materials of type a - C:H and a - SiC:H facing fusion reactor plasma

International Nuclear Information System (INIS)

Barbier, G.

1997-01-01

Plasma facing components of controlled fusion test devices (tokamaks) are submitted to several constraints (irradiation, high temperatures). The erosion (physical sputtering and chemical erosion) and the hydrogen recycling (retention and desorption) of these materials influence many plasma parameters and thus affect drastically the tokamak running. First, we will describe the different plasma-material interactions. It will be pointed out, how erosion and hydrogen recycling are strongly related to both chemical and physical properties of the material. In order to reduce these interactions, we have selected two amorphous hydrogenated materials (a-C:H and a-SiC:H), which are known for their good thermal and chemical qualities. Some samples have been then implanted with lithium ions at different fluences. Our materials have been then irradiated with deuterium ions at low energy. From our results, it is shown that both the lithium implantation and the use of an a - SiC:H substrate can be beneficial in enhancing the hydrogen retention. These results were completed with thermal desorption studies of these materials. It was evidenced that the hydrogen fixation was more efficient in a-SiC:H than in a-C:H substrate. Results in good agreement with those described above have been obtained by exposing a - C:H and a - SiC:H samples to the scrape off layer of the tokamak of Varennes (TdeV, Canada). A modelling of hydrogen diffusion under irradiation has been also proposed. (author)

Crystallization and preliminary X-ray diffraction analysis of the C-terminal domain of the human spliceosomal DExD/H-box protein hPrp22

International Nuclear Information System (INIS)

Kudlinzki, Denis; Nagel, Christian; Ficner, Ralf

2009-01-01

The cloning, purification and crystallization of the C-terminal domain of human hPrp22 are reported. This communication also contains data for the preliminary X-ray diffraction analysis. The Homo sapiens DExD/H-box protein hPrp22 is a crucial component of the eukaryotic pre-mRNA splicing machinery. Within the splicing cycle, it is involved in the ligation of exons and generation of the lariat and it additionally catalyzes the release of mature mRNA from the spliceosomal U5 snRNP. The yeast homologue of this protein, yPrp22, shows ATP-dependent RNA-helicase activity and is capable of unwinding RNA/RNA duplex molecules. A truncated construct coding for residues 950–1183 of human Prp22, comprising the structurally and functionally uncharacterized C-terminal domain, was cloned into an Escherichia coli expression vector. The protein was subsequently overproduced, purified and crystallized. The crystals obtained diffracted to 2.1 Å resolution, belonged to the tetragonal space group P4 1 2 1 2 or P4 3 2 1 2, with unit-cell parameters a = b = 78.2, c = 88.4 Å, and contained one molecule in the asymmetric unit

Ab initio study of 3C-SiC/M (M = Ti or Al) nano-hetero interfaces

International Nuclear Information System (INIS)

Tanaka, Shingo; Kohyama, Masanori

2003-01-01

Ab initio pseudopotential calculation of 3C-SiC(1 1 1)/Al nano-hetero interfaces have been performed and interface atom species dependence (IASD) and interface orientation dependence (IOD) of nano-hetero interfaces between 3C-SiC ((1 1 1) or (0 0 1) orientation) and metal (Ti or Al) have been studied systematically. Stable atomic configurations of the 3C-SiC(1 1 1)/Al interfaces are quite different from those of the 3C-SiC(1 1 1)/Ti interfaces. Two terminated, Si-terminated (Si-TERM) and C-terminated (C-TERM), 3C-SiC(1 1 1)/Al interfaces have covalent bonding nature. In 3C-SiC/M (M = Ti or Al) nano-hetero interfaces, the C-terminated interface has relative strong, covalent and ionic C-Ti or C-Al bonds as TiC or SiC while the Si-terminated interface has various type of bonding nature, relative weak Si-Ti or Si-Al bonds from metallic character at the (0 0 1) interface to covalent character at the (1 1 1) interface. Adhesive energy (AE) shows strong IASD and IOD. The AE of the C-terminated interface is larger than that of the Si-terminated one. In the C-terminated interface, the AE of the (1 1 1) interface is smaller than that of the (0 0 1) one while in the Si-terminated interface there exists opposite interrelation. Schottky barrier height (SBH) also shows strong IASD and IOD. The SBH of the C-terminated interface is smaller than that of the Si-terminated one. The C-terminated SiC/Al interfaces have extremely small SBHs. In comparison with some experimental SBH, the present result is reliable as the difference of SBH between the two terminated interfaces and qualitative properties

Factors Motivating and Hindering Information and Communication Technologies Action Competence

Directory of Open Access Journals (Sweden)

Adile Aşkım Kurt

2013-01-01

Full Text Available Information and Communication Technologies Action Competence (ICTAC can be defined as “individuals’ motivation and capacity to voluntarily employ their ICT skills for initiating or taking part in civic actions”. Since academic staff and teachers in ICT related fields have crucial roles in training action-competent individuals, this study aimed to determine the views of preservice teachers and instructors in Computer Education and Instructional Technology (CEIT departments about the motivating and hindering factors regarding ICTAC. Researchers used purposeful sampling technique and identified seven instructors and 16 students attending outlier CEIT departments from four different Turkish state universities. Since there is no contemporary framework on factors motivating or hindering ICTAC, the study was conducted with a qualitative approach and the data were collected through semi-structured interviews. Factors motivating and hindering ICTAC were identified through a content analysis. Findings of the study are believed to guide ICT and ICT education professionals in training students with higher levels of ICTAC and guide the course developers to focus on relevant social responsibility issues

Environmental 14C and 3H activities: global trends and local contamination

International Nuclear Information System (INIS)

Krajcar Bronic, I.; Obelic, B.; Horvatincic, N.

2000-01-01

The anthropogenic disturbance of natural distributions of radiocarbon ( 14 C) and tritium ( 3 H) due to the release of bomb-produced isotopes occurred after the World War II and at the same time the monitoring of these isotopes started at several stations in the world. Radioactive isotopes 14 C and 3 H, together with the stable isotopes 2 H and 18 O, are very important tracers in environmental, climatological and hydrological studies. Monitoring of environmental levels of 14 C and 3 H in Croatia started more then 20 years ago, while that of the stable isotopes somewhat later. The monitoring was performed at the three types of stations: a) 'clean-air' sites, which are supposed to reflect only the global disturbance of the atmospheric isotope concentrations, b) in a densely populated industrial center, where the effect of intense fossil-fuel combustion is expected, and local contamination from institutions using radioactive-labeled material is also possible, and c) at locations around the Nuclear Power Plant Krsko. The mean yearly 3 H activities in precipitation continuously decrease since the beginning of monitoring approaching slowly the natural equilibrium. The monthly 3 H activities show seasonal variations, with maximum in early summer and minimum in early winter. Both seasonal variations and the decrease of the mean yearly values are typical for continental stations of the Northern Hemisphere. At the sampling site located at the Institute, several periods of higher 3 H activities were observed, due to the local contamination with the tritium-labeled material. The 14 C concentration in the atmosphere shows also the continuous decrease of the mean yearly values and superposed seasonal fluctuations, with higher activity during summer. Seasonal peak-to-peak variations are higher in the area of the city of Zagreb than at the clean-air site on the mountain (about 1000 m a.s.l.). This difference is caused by the introduction of CO 2 (containing no 14 C isotope

Gas-phase reactivity of lanthanide cations with fluorocarbons: C-F versus C-H and C-C bond activation

International Nuclear Information System (INIS)

Cornehl, H.H.; Hornung, G.; Schwarz, H.

1996-01-01

The gas-phase reactivity of the fluorinated hydrocarbons CF 4 , CHF 3 , CH 3 F, C 2 F 6 , 1,1-C 2 H 4 F 2 , and C 6 F 6 with the lanthanide cations Ce + , Pr + , Sm + , Ho + , Tm + , and Yb + and the reactivity of C 6 H 5 F with all lanthanide cations Ln + (Ln = La-Lu, with the exception of Pm + ) have been examined by Fourier-transform ion cyclotron resonance mass spectrometry. The perfluorinated compounds tetrafluoromethane and hexafluoroethane as well as trifluoromethane do not react with any lanthanide cation. Selective activation of the strong C-F bonds in fluoromethane, 1,1-difluoroethane, hexafluorobenzene, and fluorobenzene appears as a general reaction scheme along the 4f row. Experimental evidence is given for a 'harpoon'-like mechanism for the F atom abstraction process which operates via an initial electron transfer from the lanthanide cation to the fluorinated substrate in the encounter complex Ln + RF. The most reactive lanthanides La + , Ce + , Gd + , and Tb + and also the formal closed-shell species Lu + exhibit additional C-H and C-C bond activation pathways in the reaction with fluorobenzene, namely dehydrohalogenation as well as loss of a neutral acetylene molecule. In the case of Tm + and Yb + the formation of neutral LnF 3 is observed in a multistep process via C-C coupling and charge transfer. 17 refs., 2 figs., 2 tabs

Analytic Morse/long-range potential energy surfaces and "adiabatic-hindered-rotor" treatment for a symmetric top-linear molecule dimer: A case study of CH3F-H2

Science.gov (United States)

Zhang, Xiao-Long; Ma, Yong-Tao; Zhai, Yu; Li, Hui

2018-03-01

A first effective six-dimensional ab initio potential energy surface (PES) for CH3F-H2 which explicitly includes the intramolecular Q3 stretching normal mode of the CH3F monomer is presented. The electronic structure computations have been carried out at the explicitly correlated coupled cluster level of theory [CCSD(T)-F12a] with an augmented correlation-consistent triple zeta basis set. Five-dimensional analytical intermolecular PESs for ν3(CH3F) = 0 and 1 are then obtained by fitting the vibrationally averaged potentials to the Morse/Long-Range (MLR) potential function form. The MLR function form is applied to the nonlinear molecule-linear molecule case for the first time. These fits to 25 015 points have root-mean-square deviations of 0.74 cm-1 and 0.082 cm-1 for interaction energies less than 0.0 cm-1. Using the adiabatic hindered-rotor approximation, three-dimensional PESs for CH3F-paraH2 are generated from the 5D PESs over all possible orientations of the hydrogen monomer. The infrared and microwave spectra for CH3F-paraH2 dimer are predicted for the first time. These analytic PESs can be used for modeling the dynamical behavior in CH3F-(H2)N clusters, including the possible appearance of microscopic superfluidity.

Radical C-H functionalization to construct heterocyclic compounds.

Science.gov (United States)

Yu, Jin-Tao; Pan, Changduo

2016-02-07

Heterocyclic compounds are widely present in natural products, pharmaceuticals and bioactive molecules. Thus, organic and pharmaceutical chemists have been making extensive efforts to construct those heterocyclic frameworks through developing versatile and efficient synthetic strategies. The direct C-H functionalization via the radical pathway has emerged as a promising and dramatic approach towards heterocycles with high atom- and step-economy. Heterocyclic compounds such as coumarins, furans, benzofurans, xanthones, benzothiazoles, indoles, indolines, oxindoles, quinolines, isoquinolines, quinoxaline, and phenanthridines have been successfully synthesized by C-H functionalization through the radical pathway. In this review, recent advances on radical C-H functionalization to construct heterocyclic compounds are highlighted with discussions.

Zinc terephthalates ZnC_8H_4O_4 as anodes for lithium ion batteries

International Nuclear Information System (INIS)

Wang, Liping; Zou, Jian; Chen, Shulin; Yang, Jingyi; Qing, Fangzhu; Gao, Peng; Li, Jingze

2017-01-01

Graphical abstract: Both of well-crystalline and amorphous zinc terephthalates ZnC_8H_4O_4 are synthesized and amorphous structure demonstrates a higher capacity and better cycling performance. - Highlights: • Crystalline and amorphous ZnC_8H_4O_4 are obtained. • Both crystalline and amorphous ZnC_8H_4O_4 have σ_e of 10"−"7 S m"−"1. • Lithium ion diffusion is the rate-determine process. • Amorphous has a high capacity and durable performance. • Amorphous ZnC_8H_4O_4 has a high apparent lithium ion diffusion coefficient. - Abstract: Organic materials offer the advantages of cost-effective, environmental benignity, and molecular structural diversity as applications of electrode materials for lithium ion batteries. In fact, their lithium storage behaviors in terms of dynamics and kinetics intrinsically lie in ion migration in solids. Thus the solid forms including crystalline and amorphous states are crucial for the properties. In this study, a conventional carbonyl type organic material, namely zinc terephthalate (ZnC_8H_4O_4), is obtained in both well-crystalline and amorphous forms and applied as anodes for lithium ion batteries. ZnC_8H_4O_4 with amorphous structure shows higher lithium storage capacity and better capacity retention compared with that of crystalline one. It is ascribed that the amorphous phase provides a higher lithium ion diffusion coefficient than the crystalline one under the conditions of similar electronic conductivity.

Characteristics of one-port surface acoustic wave resonator fabricated on ZnO/6H-SiC layered structure

Science.gov (United States)

Li, Qi; Qian, Lirong; Fu, Sulei; Song, Cheng; Zeng, Fei; Pan, Feng

2018-04-01

Characteristics of one-port surface acoustic wave (SAW) resonators fabricated on ZnO/6H-SiC layered structure were investigated experimentally and theoretically. Phase velocities (V p), electromechanical coupling coefficients (K 2), quality factors (Q), and temperature coefficients of frequency (TCF) of Rayleigh wave (0th mode) and first- and second-order Sezawa wave (1st and 2nd modes, respectively) for different piezoelectric film thickness-to-wavelength (h ZnO /λ) ratios were systematically studied. Results demonstrated that one-port SAW resonators fabricated on the ZnO/6H-SiC layered structure were promising for high-frequency SAW applications with moderate K 2 and TCF values. A high K 2 of 2.44% associated with a V p of 5182 m s‑1 and a TCF of  ‑41.8 ppm/°C was achieved at h ZnO /λ  =  0.41 in the 1st mode, while a large V p of 7210 m s‑1 with a K 2 of 0.19% and a TCF of  ‑36.4 ppm/°C was obtained for h ZnO /λ  =  0.31 in the 2nd mode. Besides, most of the parameters were reported for the first time and will be helpful for the future design and optimization of SAW devices fabricated on ZnO/6H-SiC layered structures.

Point mutations in the post-M2 region of human alpha-ENaC regulate cation selectivity.

Science.gov (United States)

Ji, H L; Parker, S; Langloh, A L; Fuller, C M; Benos, D J

2001-07-01

We tested the hypothesis that an arginine-rich region immediately following the second transmembrane domain may constitute part of the inner mouth of the epithelial Na+ channel (ENaC) pore and, hence, influence conduction and/or selectivity properties of the channel by expressing double point mutants in Xenopus oocytes. Double point mutations of arginines in this post-M2 region of the human alpha-ENaC (alpha-hENaC) led to a decrease and increase in the macroscopic conductance of alphaR586E,R587Ebetagamma- and alphaR589E,R591Ebetagamma-hENaC, respectively, but had no effect on the single-channel conductance of either double point mutant. However, the apparent equilibrium dissociation constant for Na+ was decreased for both alphaR586E,R587Ebetagamma- and alphaR589E,R591Ebetagamma-hENaC, and the maximum amiloride-sensitive Na+ current was decreased for alphaR586E,R587Ebetagamma-hENaC and increased for alphaR589E,R591Ebetagamma-hENaC. The relative permeabilities of Li+ and K+ vs. Na+ were increased 11.25- to 27.57-fold for alphaR586E,R587Ebetagamma-hENaC compared with wild type. The relative ion permeability of these double mutants and wild-type ENaC was inversely related to the crystal diameter of the permeant ions. Thus the region of positive charge is important for the ion permeation properties of the channel and may form part of the pore itself.

C2H observations toward the Orion Bar

NARCIS (Netherlands)

Nagy, Z.; Ossenkopf, V.; Van der Tak, F. F. S.; Faure, A.; Makai, Z.; Bergin, E. A.

Context. The ethynyl radical (C2H) is one of the first radicals to be detected in the interstellar medium. Its higher rotational transitions have recently become available with the Herschel Space Observatory. Aims: We aim to constrain the physical parameters of the C2H emitting gas toward the Orion

C9H14N

Indian Academy of Sciences (India)

J. Chem. Sci. Vol. 128, No. 7, July 2016, pp. 1037–1045. c Indian Academy of ..... Teraski O, Barry J C and Thomas J M 1987 Nature ... Betteridge P W, Carruthers J R, Cooper R I, Prout K and ... Clegg W and Watson D G 2007 Acta Cryst.

Magnetocaloric effect in gadolinium-oxalate framework Gd2(C2O4)3(H2O)6⋅(0⋅6H2O)

International Nuclear Information System (INIS)

Sibille, Romain; Didelot, Emilie; Mazet, Thomas; Malaman, Bernard; François, Michel

2014-01-01

Magnetic refrigerants incorporating Gd 3+ ions and light organic ligands offer a good balance between isolation of the magnetic centers and their density. We synthesized the framework material Gd 2 (C 2 O 4 ) 3 (H 2 O) 6 ⋅0.6H 2 O by a hydrothermal route and characterized its structure. The honeycomb lattice of Gd 3+ ions interlinked by oxalate ligands in the (a,c) plane ensures their decoupling in terms of magnetic exchange interactions. This is corroborated by magnetic measurements indicating negligible interactions between the Gd 3+ ions in this material. The magnetocaloric effect was evaluated from isothermal magnetization measurements. The maximum entropy change −ΔS M max reaches 75.9 mJ cm −3 K −1 (around 2 K) for a moderate field change (2 T)

Multiple C-H Bond Activations and Ring-Opening C-S Bond Cleavage of Thiophene by Dirhenium Carbonyl Complexes.

Science.gov (United States)

Adams, Richard D; Dhull, Poonam; Tedder, Jonathan D

2018-06-14

The reaction of Re 2 (CO) 8 (μ-C 6 H 5 )(μ-H) (1) with thiophene in CH 2 Cl 2 at 40 °C yielded the new compound Re 2 (CO) 8 (μ-η 2 -SC 4 H 3 )(μ-H) (2), which contains a bridging σ-π-coordinated thienyl ligand formed by the activation of the C-H bond at the 2 position of the thiophene. Compound 2 exhibits dynamical activity on the NMR time scale involving rearrangements of the bridging thienyl ligand. The reaction of compound 2 with a second 1 equiv of 1 at 45 °C yielded the doubly metalated product [Re 2 (CO) 8 (μ-H)] 2 (μ-η 2 -2,3-μ-η 2 -4,5-C 4 H 2 S) (3), formed by the activation of the C-H bond at the 5 position of the thienyl ligand in 2. Heating 3 in a hexane solvent to reflux transformed it into the ring-opened compound Re(CO) 4 [μ-η 5 -η 2 -SCC(H)C(H)C(H)][Re(CO) 3 ][Re 2 (CO) 8 (μ-H)] (4) by the loss of one CO ligand. Compound 4 contains a doubly metalated 1-thiapentadienyl ligand formed by the cleavage of one of the C-S bonds. When heated to reflux (125 °C) in an octane solvent in the presence of H 2 O, the new compound Re(CO) 4 [η 5 -μ-η 2 -SC(H)C(H)C(H)C(H)]Re(CO) 3 (5) was obtained by cleavage of the Re 2 (CO) 8 (μ-H) group from 4 with formation of the known coproduct [Re(CO) 3 (μ 3 -OH)] 4 . All new products were characterized by single-crystal X-ray diffraction analyses.

A combined crossed molecular beams and theoretical study of the reaction CN + C2H4

International Nuclear Information System (INIS)

Balucani, Nadia; Leonori, Francesca; Petrucci, Raffaele; Wang, Xingan; Casavecchia, Piergiorgio; Skouteris, Dimitrios; Albernaz, Alessandra F.; Gargano, Ricardo

2015-01-01

Highlights: • The CN + C 2 H 4 reaction was investigated in crossed beam experiments. • Electronic structure calculations of the potential energy surface were performed. • RRKM estimates qualitatively reproduce the experimental C 2 H 3 NC yield. - Abstract: The CN + C 2 H 4 reaction has been investigated experimentally, in crossed molecular beam (CMB) experiments at the collision energy of 33.4 kJ/mol, and theoretically, by electronic structure calculations of the relevant potential energy surface and Rice–Ramsperger–Kassel–Marcus (RRKM) estimates of the product branching ratio. Differently from previous CMB experiments at lower collision energies, but similarly to a high energy study, we have some indication that a second reaction channel is open at this collision energy, the characteristics of which are consistent with the channel leading to CH 2 CHNC + H. The RRKM estimates using M06L electronic structure calculations qualitatively support the experimental observation of C 2 H 3 NC formation at this and at the higher collision energy of 42.7 kJ/mol of previous experiments

Reaction mechanisms at 4H-SiC/SiO2 interface during wet SiC oxidation

Science.gov (United States)

Akiyama, Toru; Hori, Shinsuke; Nakamura, Kohji; Ito, Tomonori; Kageshima, Hiroyuki; Uematsu, Masashi; Shiraishi, Kenji

2018-04-01

The reaction processes at the interface between SiC with 4H structure (4H-SiC) and SiO2 during wet oxidation are investigated by electronic structure calculations within the density functional theory. Our calculations for 4H-SiC/SiO2 interfaces with various orientations demonstrate characteristic features of the reaction depending on the crystal orientation of SiC: On the Si-face, the H2O molecule is stable in SiO2 and hardly reacts with the SiC substrate, while the O atom of H2O can form Si-O bonds at the C-face interface. Two OH groups are found to be at least necessary for forming new Si-O bonds at the Si-face interface, indicating that the oxidation rate on the Si-face is very low compared with that on the C-face. On the other hand, both the H2O molecule and the OH group are incorporated into the C-face interface, and the energy barrier for OH is similar to that for H2O. By comparing the calculated energy barriers for these reactants with the activation energies of oxide growth rate, we suggest the orientation-dependent rate-limiting processes during wet SiC oxidation.

Dipole model analysis of F2cc¯${m{F}}_2^{{m{car c}}} $ derived from the new D* data in DIS at HERA

Directory of Open Access Journals (Sweden)

Luszczak Agnieszka

2012-12-01

Full Text Available I analyse the new D* deep inelastic scattering data from HERA with the help of dipole models. I calculate F2cc¯${m{F}}_2^{{m{car c}}} $ from the GBW [1] and BGK [2] saturation models. I compare results with the last values determined by H1 at low Q2. I find good agreement with the data.

Synthesis of two S-(methyl-3H)-labelled enkephalins and S-(methyl-14C) substance P

International Nuclear Information System (INIS)

Naegren, K.; Laangstroem, B.; Franzen, H.M.; Ragnarsson, U.

1988-01-01

The synthesis of 3 H-labelled Met-enkephalin and Tyr-D-Ala-Gly-Phe-Met-NH 2 (DALA) and 14 C-labelled Substance P (SP) from previously described, fully protected intermediates is reported. The labelled peptides were prepared by methylation with ( 3 H)- or ( 14 C)methyl iodide of the sulphide anions formed on deprotection of the corresponding S-benzyl-homocysteine precursors with sodium in liquid ammonia. After purification by LC, the labelled peptides were obtained in radiochemical yields in the range of 9 to 24% with a radiochemical purity higher than 97%. The specific radioactivities of the 3 H- and 14 C- labelled products, corresponding to the labelled methyl iodides used, were 80 mCi/μmol and 60 μCi/μmol, respectively. (author)

Magnetic studies reveal near-perfect paramagnetism in the molecular semiconductor vanadyl phthalocyanine (C{sub 32}H{sub 16}N{sub 8}VO)

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhengjun [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506-6315 (United States); Pi, Li [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei 230031 (China); Seehra, Mohindar S., E-mail: mseehra@wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506-6315 (United States); Bindra, Jasleen; Van Tol, Hans; Dalal, Naresh S. [National High Magnetic Field Laboratory, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States)

2017-01-15

Temperature (0.5–300 K) and magnetic field (H up to 90 kOe) dependences of the magnetization (M) of a powder sample of vanadyl phthalocyanine (VOPc) having the Phase II-triclinic structure are measured and analyzed. The data of χ = M/H vs. T measured in H = 1 kOe fit the modified Curie-Weiss (CW) law, χ = χ{sub o}+C/(T−θ), with C = 6.266×10{sup −4} emuK/gOe, θ = −0.1 K and χ{sub o} = −9.3×10{sup −7} emu/gOe. The Curie constant C yields magnetic moment μ = 1.704 μ{sub B}, S = 1/2, and g = 1.967 characteristic of VO{sup 2+}. The magnitude of θ = −0.1 K signifying very weak inter-ion antiferromagnetic exchange coupling is supported by the analysis of the variable frequency (9.8–336 GHz) electron paramagnetic resonance data. The isothermal data of M vs. H at ten temperatures between 0.5 K and 300 K when plotted as M vs. H/(T+0.1) collapses on to a single curve given by M = M{sub o}tanh {gμ_BH/[2k_B(T+0.1)]} with M{sub o} = Ngμ{sub B}S = 9.48 emu/g expected for S = 1/2 system, thus signifying near perfect paramagnetism in VOPc. - Highlights: • Magnetization M vs. temperature T from 0.5 K to 300 K in H = 1 kOe is reported. • M vs. T data fit Curie-Weiss law with θ = −0.1 K, S = 1/2, &g = 1.967 for VO{sup 2+}. • Isothermal M vs. H data (H up to 90 kOe) for ten T from 0.5 K to 300 K is reported. • M vs. H/(T−θ) plot for various T fit a single Brillouin function curve for S = 1/2. • Analysis of magnetic and EPR data in VOPc shows near perfect S = 1/2 paramagnetism.

Palladium-catalysed electrophilic aromatic C-H fluorination

Science.gov (United States)

Yamamoto, Kumiko; Li, Jiakun; Garber, Jeffrey A. O.; Rolfes, Julian D.; Boursalian, Gregory B.; Borghs, Jannik C.; Genicot, Christophe; Jacq, Jérôme; van Gastel, Maurice; Neese, Frank; Ritter, Tobias

2018-02-01

Aryl fluorides are widely used in the pharmaceutical and agrochemical industries, and recent advances have enabled their synthesis through the conversion of various functional groups. However, there is a lack of general methods for direct aromatic carbon-hydrogen (C-H) fluorination. Conventional methods require the use of either strong fluorinating reagents, which are often unselective and difficult to handle, such as elemental fluorine, or less reactive reagents that attack only the most activated arenes, which reduces the substrate scope. A method for the direct fluorination of aromatic C-H bonds could facilitate access to fluorinated derivatives of functional molecules that would otherwise be difficult to produce. For example, drug candidates with improved properties, such as increased metabolic stability or better blood-brain-barrier penetration, may become available. Here we describe an approach to catalysis and the resulting development of an undirected, palladium-catalysed method for aromatic C-H fluorination using mild electrophilic fluorinating reagents. The reaction involves a mode of catalysis that is unusual in aromatic C-H functionalization because no organometallic intermediate is formed; instead, a reactive transition-metal-fluoride electrophile is generated catalytically for the fluorination of arenes that do not otherwise react with mild fluorinating reagents. The scope and functional-group tolerance of this reaction could provide access to functional fluorinated molecules in pharmaceutical and agrochemical development that would otherwise not be readily accessible.

Directed C-H Bond Oxidation of (+)-Pleuromutilin.

Science.gov (United States)

Ma, Xiaoshen; Kucera, Roman; Goethe, Olivia F; Murphy, Stephen K; Herzon, Seth B

2018-05-01

Antibiotics derived from the diterpene fungal metabolite (+)-pleuromutilin (1) are useful agents for the treatment Gram-positive infections in humans and farm animals. Pleuromutilins elicit slow rates of resistance development and minimal cross-resistance with existing antibiotics. Despite efforts aimed at producing new derivatives by semisynthesis, modification of the tricyclic core is underexplored, in part due to a limited number of functional group handles. Herein, we report methods to selectively functionalize the methyl groups of (+)-pleuromutilin (1) by hydroxyl-directed iridium-catalyzed C-H silylation, followed by Tamao-Fleming oxidation. These reactions provided access to C16, C17, and C18 monooxidized products, as well as C15/C16 and C17/C18 dioxidized products. Four new functionalized derivatives were prepared from the protected C17 oxidation product. C6 carboxylic acid, aldehyde, and normethyl derivatives were prepared from the C16 oxidation product. Many of these sequences were executed on gram scales. The efficiency and practicality of these routes provides an easy method to rapidly interrogate structure-activity relationships that were previously beyond reach. This study will inform the design of fully synthetic approaches to novel pleuromutilins and underscores the power of the hydroxyl-directed iridium-catalyzed C-H silylation reaction.

Standard Molar Enthalpy of Formation of RE(C5H8NS2)3(o-phen)

Institute of Scientific and Technical Information of China (English)

MENG Xiang-Xin; GAO Sheng-Li; CHEN San-Ping; YANG Xu-Wu; XIE Gang; SHI Qi-Zhen

2005-01-01

Five solid ternary complexes of RE(C5H8NS2)3(o-phen) (RE=Ho, Er, Tm, Yb, Lu) have been synthesized in absolute ethanol by rare earth chloride low hydrate reacting with the mixed ligands of ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline·H2O (o-phen·H2O) in the ordinary laboratory atmosphere without any cautions against moisture or air. IR spectra of the complexes showed that the RE3+ coordinated with six sulfur atoms of three PDC- and two nitrogen atoms of o-phen·H2O. It was assumed that the coordination number of RE3+was eight. The constant-volume combustion energies of the complexes, △cU, were determined as (-16788.46±7.74), (- 15434.53± 8.28), (- 15287.807.31), (- 15200.50±7.22) and (- 15254.34±6.61) kJ·mol-1, respectively, by a precise rotating-bomb calorimeter at 298.15 K. Its standard molar enthalpies of combustion, △cH m,and standard molar enthalpies of formation, △fH m, were calculated as (-16803.95 ±7.74), (-15450.02±8.28),(-15303.29±9.28), (-15215.99±7.22), (-15269.83±6.61) kJ·mol-1 and (-1115.42±8.94), (-2477.80±9.15), (-2619.95 ±10.44), (-2670.17 ± 8.22), ( -2650.06± 8.49) kJ·mol-1, respectively.

Synthesis and characterisation of pure C(-A)-S-H phases

International Nuclear Information System (INIS)

L'Hopital, E.; Lothenbach, B.; Le Saout, G.; Kulik, D.A.; Scrivener, K.

2015-01-01

The construction of nuclear power plants requires huge quantity of cement and the cement production generates about 8% of global man-made CO 2 emissions. One way of reducing the concrete's CO 2 contribution is to lower its CO 2 generation and energy consumption by a partial replacement of clinker with supplementary cementitious materials (SCMs). Common SCMs such as blast furnace slag or fly ash contain more silicon and aluminium than Portland cement, so that the hydrates formed are different than in Portland cements, which might affect the concrete mechanical properties. The most important phase formed during the reaction of Portland cement with water is calcium silicate hydrate, C-S-H. In the presence of SCMs, C-S-H can have different composition compared to C-S-H in Portland cements. The present work focuses on synthesis of pure C(-A)- S-H at a Ca/Si ratio equal to 1 in presence of different quantities of aluminium (Al/Si atomic ratio from 0 to 0.05) to determine the aluminium incorporation in C-S-H. The absence of any other solids and the low aluminium concentrations measured in the solution clearly showed an uptake of aluminium within the C-(A)-S-H phase. The presence of aluminium increased the interlayer distance, indicating an uptake of aluminium in the C-(A)-S-H structure. The uptake of aluminium was more pronounced at higher dissolved aluminium concentrations, consistent with the formation of a solid solution between C-S-H and C-A-S-H. The presence of aluminium led to a decrease of the calcium concentrations, while the silica and aluminium concentrations increased

Monte Carlo Simulation of Electron Transport in 4H- and 6H-SiC

International Nuclear Information System (INIS)

Sun, C. C.; You, A. H.; Wong, E. K.

2010-01-01

The Monte Carlo (MC) simulation of electron transport properties at high electric field region in 4H- and 6H-SiC are presented. This MC model includes two non-parabolic conduction bands. Based on the material parameters, the electron scattering rates included polar optical phonon scattering, optical phonon scattering and acoustic phonon scattering are evaluated. The electron drift velocity, energy and free flight time are simulated as a function of applied electric field at an impurity concentration of 1x10 18 cm 3 in room temperature. The simulated drift velocity with electric field dependencies is in a good agreement with experimental results found in literature. The saturation velocities for both polytypes are close, but the scattering rates are much more pronounced for 6H-SiC. Our simulation model clearly shows complete electron transport properties in 4H- and 6H-SiC.

Crossed-beam reaction of carbon atoms with hydrocarbon molecules. IV. Chemical dynamics of methylpropargyl radical formation, C4H5, from reaction of C(3Pj) with propylene, C3H6 (X1A)

International Nuclear Information System (INIS)

Kaiser, R.I.; Stranges, D.; Bevsek, H.M.; Lee, Y.T.; Suits, A.G.

1997-01-01

The reaction between ground state carbon atoms and propylene, C 3 H 6 , was studied at average collision energies of 23.3 and 45.0 kJmol -1 using the crossed molecular beam technique. Product angular distributions and time-of-flight spectra of C 4 H 5 at m/e=53 were recorded. Forward-convolution fitting of the data yields a maximum energy release as well as angular distributions consistent with the formation of methylpropargyl radicals. Reaction dynamics inferred from the experimental results suggest that the reaction proceeds on the lowest 3 A surface via an initial addition of the carbon atom to the π-orbital to form a triplet methylcyclopropylidene collision complex followed by ring opening to triplet 1,2-butadiene. Within 0.3 endash 0.6 ps, 1,2-butadiene decomposes through carbon endash hydrogen bond rupture to atomic hydrogen and methylpropargyl radicals. The explicit identification of C 4 H 5 under single collision conditions represents a further example of a carbon endash hydrogen exchange in reactions of ground state carbon with unsaturated hydrocarbons. This versatile machine represents an alternative pathway to build up unsaturated hydrocarbon chains in combustion processes, chemical vapor deposition, and in the interstellar medium. copyright 1997 American Institute of Physics

Mitochondrial dysfunction in H9c2 cells during ischemia and amelioration with Tribulus terrestris L.

Science.gov (United States)

Reshma, P L; Sainu, Neethu S; Mathew, Anil K; Raghu, K G

2016-05-01

The present study investigates the protective effect of partially characterized Tribulus terrestris L. fruit methanol extract against mitochondrial dysfunction in cell based (H9c2) myocardial ischemia model. To induce ischemia, the cells were maintained in an ischemic buffer (composition in mM -137 NaCl, 12 KCl, 0.5 MgCl2, 0.9 CaCl2, 20 HEPES, 20 2-deoxy-d-glucose, pH-6.2) at 37°C with 0.1% O2, 5% CO2, and 95% N2 in a hypoxia incubator for 1h. Cells were pretreated with various concentrations of T. terrestris L. fruit methanol extract (10 and 25μg/ml) and Cyclosporin A (1μM) for 24h prior to the induction of ischemia. Different parameters like lactate dehydrogenase release, total antioxidant capacity, glutathione content and antioxidant enzymes were investigated. Studies were conducted on mitochondria by analyzing alterations in mitochondrial membrane potential, integrity, and dynamics (fission and fusion proteins - Mfn1, Mfn2, OPA1, Drp1 and Fis1). Various biochemical processes in mitochondria like activity of electron transport chain (ETC) complexes, oxygen consumption and ATP production was measured. Ischemia for 1h caused a significant (p≤0.05) increase in LDH leakage, decrease in antioxidant activity and caused mitochondrial dysfunction. T. terrestris L. fruit methanol extract pretreatment was found effective in safeguarding mitochondria via its antioxidant potential, mediated through various bioactives. HPLC of T. terrestris L. fruit methanol extract revealed the presence of ferulic acid, phloridzin and diosgenin. T. terrestris L. fruit ameliorate ischemic insult in H9c2 cells by safeguarding mitochondrial function. This validates the use of T. terrestris L. against heart disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

Generation of the J/sub c/, H/sub c/, T/sub c/ surface for commercial superconductor using reduced-state parameters

International Nuclear Information System (INIS)

Green, M.A.

1988-04-01

This report presents a method for calculating the J/sub C/, H/sub C/, T/sub C/ surface for Type II Superconductors. The method requires that one knows T/sub C/ at zero current and field, H/sub c2/ at zero current and temperature, and J/sub c/ at at least one temperature and field. The theory presented in this report agrees with the measured data quite well over virtually the entire J/sub c/, H/sub c/, T/sub c/ surface given the value of J/sub c/ versus H at one or two temperatures. This report presents calculated and measured values of J/sub c/ versus T and B for niobium titanium, niobium zirconium, niobium tin, niobium titanium tin, niobium tantalum tin, vanadium zirconium hafnium, and vanadium gallium. Good agreement of theory with measured data was obtained for commercial niobium titanium and niobium tin. 76 refs., 26 figs., 6 tabs

pH-Triggered Molecular Alignment for Reproducible SERS Detection via an AuNP/Nanocellulose Platform

Science.gov (United States)

Wei, Haoran; Vikesland, Peter J.

2015-12-01

The low affinity of neutral and hydrophobic molecules towards noble metal surfaces hinders their detection by surface-enhanced Raman spectroscopy (SERS). Herein, we present a method to enhance gold nanoparticle (AuNP) surface affinity by lowering the suspension pH below the analyte pKa. We developed an AuNP/bacterial cellulose (BC) nanocomposite platform and applied it to two common pollutants, carbamazepine (CBZ) and atrazine (ATZ) with pKa values of 2.3 and 1.7, respectively. Simple mixing of the analytes with AuNP/BC at pH < pKa resulted in consistent electrostatic alignment of the CBZ and ATZ molecules across the nanocomposite and highly reproducible SERS spectra. Limits of detection of 3 nM and 11 nM for CBZ and ATZ, respectively, were attained. Tests with additional analytes (melamine, 2,4-dichloroaniline, 4-chloroaniline, 3-bromoaniline, and 3-nitroaniline) further illustrate that the AuNP/BC platform provides reproducible analyte detection and quantification while avoiding the uncontrolled aggregation and flocculation of AuNPs that often hinder low pH detection.

CLCNKB mutations causing mild Bartter syndrome profoundly alter the pH and Ca2+ dependence of ClC-Kb channels.

Science.gov (United States)

Andrini, Olga; Keck, Mathilde; L'Hoste, Sébastien; Briones, Rodolfo; Mansour-Hendili, Lamisse; Grand, Teddy; Sepúlveda, Francisco V; Blanchard, Anne; Lourdel, Stéphane; Vargas-Poussou, Rosa; Teulon, Jacques

2014-09-01

ClC-Kb, a member of the ClC family of Cl(-) channels/transporters, plays a major role in the absorption of NaCl in the distal nephron. CLCNKB mutations cause Bartter syndrome type 3, a hereditary renal salt-wasting tubulopathy. Here, we investigate the functional consequences of a Val to Met substitution at position 170 (V170M, α helix F), which was detected in eight patients displaying a mild phenotype. Conductance and surface expression were reduced by ~40-50 %. The regulation of channel activity by external H(+) and Ca(2+) is a characteristic property of ClC-Kb. Inhibition by external H(+) was dramatically altered, with pKH shifting from 7.6 to 6.0. Stimulation by external Ca(2+) on the other hand was no longer detectable at pH 7.4, but was still present at acidic pH values. Functionally, these regulatory modifications partly counterbalance the reduced surface expression by rendering V170M hyperactive. Pathogenic Met170 seems to interact with another methionine on α helix H (Met227) since diverse mutations at this site partly removed pH sensitivity alterations of V170M ClC-Kb. Exploring other disease-associated mutations, we found that a Pro to Leu substitution at position 124 (α helix D, Simon et al., Nat Genet 1997, 17:171-178) had functional consequences similar to those of V170M. In conclusion, we report here for the first time that ClC-Kb disease-causing mutations located around the selectivity filter can result in both reduced surface expression and hyperactivity in heterologous expression systems. This interplay must be considered when analyzing the mild phenotype of patients with type 3 Bartter syndrome.

Study of the hydrogen behavior in amorphous hydrogenated materials of type a - C:H and a - SiC:H facing fusion reactor plasma; Etude du comportament de l`hydrogene dans des materiaux amorphes hydrogenes de type a - C:H et a - SiC:H devant faire face au plasma des reacteurs a fusion

Energy Technology Data Exchange (ETDEWEB)