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  • 1
    Electronic Resource
    Electronic Resource
    Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with Ru3(CO)12: Evidence for facile ligand fragmentation in Ru3(CO)10(dmpdmh) to give Ru4(CO)12[μ-N(Me)N(Me)], Ru3(CO)11[P(OMe)3], and Ru3(CO)9[μ-P(OMe)3] (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 587-595 
    Details
    ISSN: 1572-8854
    Keywords: thermolysis ; P—N bond cleavage ; ruthenium clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Thermolysis of the cluster Ru3(CO)12 with the bis(phosphanyl)hydrazine ligand (MeO)2PN (Me)N(Me)P(OMe)2 (dmpdmh) in toluene at 75°C furnishes the known clusters Ru4(CO)12 [μ-N(Me)N(Me)] (2) and Ru3(CO)11[P(OMe)3] (3), in addition to the new cluster Ru3 (CO)10(dmpdmh) (1) and the phosphite-tethered cluster Ru3(CO)9[μ-P(OMe)3] (4). The simple substitution product Ru3(CO)10(dmpdmh), a logical intermediate to clusters 2–4, was synthesized by treating Ru3(CO)12 with Me3NO in CH2Cl2 at room temperature, and independent thermolysis reactions using cluster 1 was shown to yield clusters 2–4. The solid-state structure of clusters 2 and 4 were unequivocally established by X-ray diffraction analysis. Ru4(CO)12[μ-N(Me)N(Me)] crystallizes in the orthorhombic space group Pnna (#52), a = 12.913(1), b = 13.3238(6), c = 12.5690(8) Å, V = 2162.5(2) Å3, Z = 4, and d calc = 2.452 g/cm3. Ru3(CO)9[μ-P(OMe)3] crystallizes in the triclinic space group P $$\bar 1$$ a = 9.586(1), b = 14.354(1), c = 14.997(2) Å, α = 89.82(1)°, β = 98.36(1)°, γ = 92.010(8)°, V = 2040.4(4) Å3, Z = 4, and d calc = 2.212 g/cm3. The coordination of the dimethylazo linkage to the four ruthenium atoms in 2 and the phosphorus atom and one of the oxygen atoms of the methoxy groups to the three ruthenium centers in 4 are confirmed by X-ray analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009505020850
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  • 2
    Electronic Resource
    Electronic Resource
    Room temperature ligand fragmentation in the reaction between PhCCo3(CO)9 and Ph2PN(Me)N(Me)PPh2. X-ray diffraction structure of PhCCo3(CO)8[Ph2PP(O)Ph2] (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 603-608 
    Details
    ISSN: 1572-8854
    Keywords: ligand fragmentation ; hydrazine ligand ; P-C bond cleavage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cobalt cluster PhCCo3(CO)9 reacts with the bis(phosphanyl)hydrazine ligand bis(diphenylphosphino)dimethylhydrazine (dppdmh) in CH2Cl2 with added Me3NO to give the monosubstituted cluster PhCCo3(CO)8[Ph2PP(O)PPh2] as the major isolable product. The solid-state structure of this new cluster was unequivocally established by X-ray diffraction analysis, which has confirmed the presence of a noncoordinated (O)PPh2 moiety. PhCCo3(CO)8[Ph2PP(O)Ph2] crystallizes in the triclinic space group P $$\bar 1$$ , a = 12.036(2), b = 12.037(2), c = 15.124(3) Å, α = 84.82(1)°, β = 89.44(2)°, γ = 60.09(1)°, V = 1890.0(6) Å3, Z = 2, and dcalc = 1.540 g/cm3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009509221759
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  • 3
    Electronic Resource
    Electronic Resource
    Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with PhCCo3(CO)9: synthesis and X-ray characterization of the dmpdmh-bridged polymorphs of PhCCo3(CO)7[(MeO)2PN(Me)N(Me)P(OMe)2] (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 401-407 
    Details
    ISSN: 1572-8854
    Keywords: dmpdmh-Bridged polymorphs ; IR and NMR spectroscopies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The tricobalt cluster PhCCo3(CO)9 reacts with the bis(phosphanyl)hydrazine ligand bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) to give the monosubstituted cluster [PhCCo3(CO)8]2(dmpdmh) and the disubstituted cluster PhCCo3(CO)7(dmpdmh) as the major products. This latter cluster contains a bridging dmpdmh ligand. Both IR and NMR spectroscopies (31P and 1H) have been employed in the solution characterization of these two clusters. The solid-state structure of PhCCo3(CO)7(dmpdmh) was unequivocally established by X-ray diffraction analysis, which has revealed the presence of two different polymorphs for this particular cluster. The first polymorph crystallizes in the monoclinic space group P21/n, a = 9.7127(7) Å, b = 17.025(2) Å,c = 16.894(1) Å, β = 96.245(5)°, V = 2777.0(4) Å3, Z = 4, and d calc = 1.689 g/cm3; while the second polymorph crystallizes in the orthorhombic space group Pbca, a = 16.925(2) Å, b = 16.208(2) Å, c = 20.541(3) Å, V = 5635(1) Å3, Z = 8, and d calc = 1.665 g/cm3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022420410672
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  • 4
    Electronic Resource
    Electronic Resource
    Chelation of a diphosphine ligand at FeCo2(CO)9(μ3-S): Spectroscopic and X-ray diffraction data for FeCo2(CO)7(bpcd)(μ3-S) (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 391-397 
    Details
    ISSN: 1572-8854
    Keywords: diphosphine ligand ; mixed-metal cluster ; electrochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The tetrahedrane cluster, FeCo2(CO)9(μ3-S), reacts with the redox-active ligand, 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd), to give the disubstituted cluster, FeCo2(CO)7(bpcd)(μ3-S), as the sole product. This diphosphine-substituted cluster contains a cobalt-bound, chelating bpcd ligand. Both IR and 31P NMR spectroscopies have been employed in the solution characterization of FeCo2(CO)7(bpcd)(μ3-S), and the solid-state structure has been unequivocally established by X-ray diffraction analysis. FeCo2(CO)7(bpcd)(μ3-S) crystallizes in the monoclinic space group C2/c, a = 34.494(3) Å, b = 11.4194(9) Å, c = 18.634(2) Å, β = 98.103(7)°, V = 7266.7(9) Å3, Z = 8, and dcalc = 1.584 g/cm3. Cyclic voltammetric studies on FeCo2(CO)7(bpcd)(μ3-S) reveal the presence of two quasireversible redox responses assigned to the 0/1− and 1−/2− redox couples. The orbital composition of these redox couples has been examined by carrying out extended Hückel MO calculations on the model complex FeCo2(CO)7(H4-bpcd)(μ3-S), with the results being compared to related cluster compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009502708303
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  • 5
    Electronic Resource
    Electronic Resource
    Environmental changes documented by sedimentation of Lake Yiema in arid China since the late Glaciation (1999)
    Springer
    Journal of paleolimnology 22 (1999), S. 159-169 
    Details
    ISSN: 1573-0417
    Keywords: lake record ; Holocene environmental changes ; arid northwestern China
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract In this study, a 6 m long core (16,000 BP) at the center of the dry Lake Yiema, a closed lake of Shiyang River drainage in Minqin Basin of the arid northwestern China, was retrieved to recover the history of climate changes and lake evolution in the area. Five radiocarbon dates on organic matter were obtained. A chronological sequence is established based on these five dates and other dates from nearby sites. Magnetic susceptibility, particle size and chemical composition were analysized for climate proxies. The proxies indicate that a drier climate prevailed in the Shiyang River drainage during the last glacial. Lake Yiema was dry and eolian sand covered most part of the lake basin. During the early and middle Holocene, a moister climate prevailed in the drainage. Climate became dry stepwise with an abrupt transition from one stage to another during the entire Holocene and became driest since about 4,200 BP. Maximum dry climate spells occurred at about 12,000-10,000 BP and after about 4,200 BP. A dry climate event also existed at about 7,600 BP. Periodical sand storms with about 400-yr cycle happened during the middle Holocene. Desiccation processes of the lake started at 4,200 BP, and were accelerated since the last 2,500 yrs by the inflow water diversion for agriculture irrigation. During the past 2,500 yrs, the lake size has been closed associated with the human population, implying that the human impact has been accelerating the lake desiccation superimposed on the natural climate deterioration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008093300257
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  • 6
    Electronic Resource
    Electronic Resource
    DNA binding activity of the mammalian translation elongation complex: recognition of chromium- and transplatin-damaged DNA (1997)
    Springer
    Archives of toxicology 71 (1997), S. 450-454 
    Details
    ISSN: 1432-0738
    Keywords: Key words DNA damage  ;  Elongation complex  ;  Chromium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The elongation factor complex, EF-1H, serves an essential function in protein biosynthesis in eukaryotic cells, although the role of EF-1H in other physiological processes is unknown. In this report, we demonstrate that three components of EF-1H (EF-1β, EF-1δ, and EF-1γ) bind to DNA modified with chromium (Cr), a potent DNA-damaging agent and an established human carcinogen. The EF-1H complex also binds to transplatin modified DNA but not to cisplatin-modified DNA. These results demonstrate that the EF-1H complex has functional DNA binding activity and is capable of recognizing the distortions in DNA structure resulting from the covalent binding of Cr and transplatin to DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050410
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  • 7
    Electronic Resource
    Electronic Resource
    On the limit of brightness temperature in nonstationary radio sources (1995)
    Springer
    Astrophysics and space science 229 (1995), S. 79-88 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations imply that extragalactic radio sources must be in nonstationary states. One possible way to interpret a observed high brightness temperature which exceeds the inverse Compton limit is by means of a nonstationary condition (Kellerman and Pauliny-Toth 1969, Slysh 1992). This paper investigates the maximum brightness temperature of nonstationary radio sources by incorporating the continuity equation for the electron number density and the radiative transfer equation. In radio sources with a high enough magnetic field, synchrotron losses should be considered and the maximum brightness temperature will not achieve the maximum value suggested by Slysh (1992). Strong acceleration canonly shorten the time to achieve the brightness temperature limit and doesnot violate the KPT limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658567
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  • 8
    Electronic Resource
    Electronic Resource
    Dynamics of Preference by Sheep Offered Foods Varying in Flavors, Nutrients, and A Toxin (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 275-288 
    Details
    ISSN: 1573-1561
    Keywords: Food preference ; flavor ; nutrients ; toxins ; learning ; sheep ; Ovis aries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We conducted two experiments to determine how toxicosis affected preference of sheep for foods varying in flavors, nutrients, and a toxin. The first experiment determined how toxicosis affected the preference of lambs (fed a basal ration of alfalfa pellets) for foods that varied in energy and a toxin. Thirty lambs (10/treatment) were given LiCl by gavage (0, 50, or 100 mg/kg body wt/day), and 1 hr later were offered for 15 min/day foods containing different amounts (low, medium, high) of energy (barley) and a toxin (LiCl) added to alfalfa. The proportions of barley and LiCl changed every three to six days during the 30-day study. The results showed: (1) lambs' food preferences were high 〉 medium 〉 low for barley in the absence of LiCl; (2) lambs quickly regulated intake of foods in response to changes in barley and LiCl concentrations, even with short exposures (15 min/day); (3) lambs maintained intake of LiCl at about 57 mg/kg body wt by adjusting intake of food containing LiCl in accord with the amount of LiCl they received by gavage; and (4) as barley levels increased, intake of foods containing LiCl increased. The second experiment determined the relative influence of flavors, nutrients, and toxins on food preferences of lambs. We did this by treatments in which different flavors (onion and oregano at 1%) were paired with different levels of energy (depending on the addition of wheat to rabbit pellets) or a toxin (LiCl). At six-day intervals, we varied the types of food offered, either changing the nutrient or toxin content and the flavors. The resulting analyses of preference showed lambs markedly preferred foods high in nutrients and low in toxins, regardless of flavor, when changes in food flavor were not correlated with changes in nutrient and toxin concentrations. Thus, in both experiments lambs quickly regulated intake of foods varying in nutrients and a toxin according to the lambs' toxicological and nutritional state. Even with brief eating bouts lambs discriminated accurately and exhibited little permanent preference or aversion in postconditioning preference tests. The lambs remained in an unbiased testing mode, sampling anew the food. This is adaptive because the toxin and nutrient contents of plants vary with season and location. Most taste aversion studies emphasize the permanence of aversions and miss the dynamic sampling power of animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:JOEC.0000006359.62931.f9
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  • 9
    Electronic Resource
    Electronic Resource
    Multicentre trial on the efficacy and toxicity of single-dose samarium-153-ethylene diamine tetramethylene phosphonate as a palliative treatment for painful skeletal metastases in China (1999)
    Springer
    European journal of nuclear medicine 26 (1999), S. 2-7 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Samarium-153 ethylene diamine tetramethylene phosphonate ; Skeletal metastases ; Radiopharmaceutical therapy ; Palliative treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. A multicentre trial was organized in China as part of an international coordinated research project to study the efficacy and toxicity of single-dose samarium-153 ethylene diamine tetramethylene phosphonate (EDTMP) as a palliative treatment for painful skeletal metastases. One hundred and five patients with painful bone metastases from various primaries were treated with 153Sm-EDTMP at a dose of 37 MBq/kg(group I) or 18.5 MBq/kg (group II). The effects were evaluated according to change in daily analgesic consumption, pain score, sum of effect product (SEP), Physician’s Global Assessment (PGA), blood counts, and organ function tests conducted regularly for 16 weeks. Fifty-eight of 70 patients in group I and 30 of 35 in group II had a positive response, with SEPs of 22.29±14.47 and 20.13±13.90 respectively. Of 72 patients who had been receiving analgesics, 63 reduced their consumption. PGA showed that the Karnofsky score (KS) increased from 58.54±25.90 to 71.67±26.53, indicating improved general condition, but the difference was not significant. Among subgroups of patients, only those with breast cancer showed a significant change in the Karnofsky score after treatment. Inter-group differences were found for net change in KS between patients with lung and patients with breast cancer, and between patients with lung and patients with oesophageal cancer. Seventeen patients showed no response. No serious side-effects were noted, except for falls in the white blood cell (nadir 1.5×109/l) and platelet (nadir 6.0×1010/l) counts in 44/105 and 34/105 cases, respectively. Ten patients had an abnormal liver function test. Response and side-effects were both independent of dose. In conclusion, 153Sm-EDTMP provided effective palliation in 83.8% of patients with painful bone metastases; the major toxicity was temporary myelosuppression. Further studies are needed to identify better ways of determining the appropriate dose in the individual case and the efficacy of treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050351
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  • 10
    Electronic Resource
    Electronic Resource
    Morphological and Biochemical Changes During Programmed Cell Death of Rat Cerebellar Granule Cells (1997)
    Springer
    Neurochemical research 22 (1997), S. 43-48 
    Details
    ISSN: 1573-6903
    Keywords: Apoptosis ; programmed cell death ; cerebellar granule cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cultured cerebellar granule cells deprived of depolarizing concentrations of KCl and serum die by programmed cell death. Recently, it was shown that serum removal by itself can lead to oxidative stress and DNA fragmentation in these cells. We have modified the protocol which initiates cell death in such a way that only the effect of KCl withdrawal-induced cell death was observed. We have performed a series of experiments to correlate the structural and biochemical changes in this process of cell death. Significant morphological alterations occur in cell bodies and neurites during a 48-hour period of KCl removal. Cell viability dropped to 53%, 34% or 10% of control levels, respectively, as a result of 1-, 2-, or 3-day KCl removal. A series of experiments was conducted to determine the change of total protein level, protein synthesis rate, RNA synthesis rate, and mitochondrial activity during the first 48 hours of KCl removal. These studies not only provide a picture correlating the morphological and biochemical changes in the process of programmed cell death, but also serve as a reference for future studies of this complex phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027373220133
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