bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct GABAergic and Glycinergic Inhibition of the Substantia Gelatinosa from the Rostral Ventromedial Medulla Revealed byIn VivoPatch-Clamp Analysis in Rats
Authors: Kato Go , Yasaka Toshiharu , Katafuchi Toshihiko , Furue Hidemasa , Mizuno Masaharu , Iwamoto Yukihide , Yoshimura Megumu
Published: February 2006

Stimulation of the rostral ventromedial medulla (RVM) is believed to exert analgesic effects through the activation of the serotonergic system descending to the spinal dorsal horn; however, how nociceptive transmission is modulated by the descending system has not been fully clarified. To investigate the inhibitory mechanisms affected by the RVM, anin vivopatch-clamp technique was used to record IPSCs from the substantia gelatinosa (SG) of the spinal cord evoked by chemical (glutamate injection) and electrical stimulation (ES) of the RVM in adult rats. In the voltage-clamp mode, the RVM glutamate injection and RVM-ES produced an increase in both the frequency and amplitude of IPSCs in SG neurons that was not blocked by glutamate receptor antagonists. Serotonin receptor antagonists were unexpectedly without effect, but a GABAAreceptor antagonist, bicuculline, or a glycine receptor antagonist, strychnine, completely suppressed the RVM stimulation-induced increase in IPSCs. The RVM-ES-evoked IPSCs showed fixed latency and no failure at 20 Hz stimuli with a conduction velocity of >3 m/s (3.1–20.7 m/s), suggesting descending monosynaptic GABAergic and/or glycinergic inputs from the RVM to the SG through myelinated fibers. In the current-clamp mode, action potentials elicited by noxious mechanical stimuli applied to the receptive field of the ipsilateral hindlimb were suppressed by the RVM-ES in more than half of the neurons tested (63%; 10 of 16). These findings suggest that the RVM-mediated antinociceptive effects on noxious inputs to the SG may be exerted preferentially by the direct GABAergic and glycinergic pathways to the SG.
MTH1, an Oxidized Purine Nucleoside Triphosphatase, Suppresses the Accumulation of Oxidative Damage of Nucleic Acids in the Hippocampal Microglia during Kainate-Induced Excitotoxicity
Authors: Kajitani Kosuke , Yamaguchi Hiroo , Dan Yukihiko , Furuichi Masato , Kang Dongchon , Nakabeppu Yusaku
Published: February 2006

Enhanced oxidative stress has been implicated in the excitotoxicity of the CNS, and 8-oxo-7,8-dihydro-guanine (8-oxoG), a major type of oxidative damage in nucleic acids, was reported to be accumulated in the rat hippocampus after kainate administration. We herein showed that the 8-oxoG levels in mitochondrial DNA and cellular RNA increased significantly in the CA3 subregion of the mouse hippocampus 6–12 h after kainate administration but returned to basal levels within a few days. Laser-scanning confocal microscopy revealed the 8-oxoG accumulation in mitochondrial DNA to be remarkable in CA3 microglia, whereas that in nuclear DNA or cellular RNA was also detected in the CA3 pyramidal cells and astrocytes. 8-oxoG accumulation in cellular DNA or RNA should be suppressed by MutT homolog 1 (MTH1) with 8-oxo-dGTPase (8-oxo-7,8-dihydro-2′-deoxyguanosine triphosphatase) activity and 8-oxoG-DNA glycosylase 1 (OGG1) with 8-oxoG DNA glycosylase activity. We thus examined the expression level of MTH1 and OGG1 in the mouse hippocampus after kainate administration. TheMth1mRNA level decreased soon after kainate administration and then quickly recovered beyond the basal level, and a continuously increased MTH1 protein level was observed, whereas theOgg1mRNA level remained constant. MTH1-null and wild-type mice exhibited a similar degree of CA3 neuron loss after kainate administration; however, the 8-oxoG levels that accumulated in mitochondrial DNA and cellular RNA in the CA3 microglia significantly increased in the MTH1-null mice in comparison with wild-type mice, thus demonstrating that MTH1 efficiently suppresses the accumulation of 8-oxoG in both cellular DNA and RNA in the hippocampus, especially in microglia, caused by excitotoxicity.
Model Evaluation of Linear Gut Evacuation in the Larval Radiated Shanny Using a Combination of Laboratory and Field Data
Authors: Bochdansky Alexander B. , Brunemeyer Naomi D. , Leggett William C.
Published: February 2006

The combination of gut contents and evacuation rate is an important tool with which to determine the in situ feeding rates of many organisms. Traditionally used equations of gut evacuation models, however, have made comparisons among models difficult. For consistency, we changed the notation of the linear gut evacuation model to provide a rate‐constant parameter (r) similar to the one commonly used in the exponential model. In a previous analysis using examples from the literature, we demonstrated that prolonged retention of food after a true linear pattern of gut evacuation may be mistakenly identified as an exponential pattern. We explored the linear gut evacuation rate model empirically and in more detail using the radiated shanny Ulvaria subbifurcata as the model species. Rate constants based on field data were similar to those determined in the laboratory. The basic assumption of nonfeeding during darkness was met, indicating that foraging was primarily based on visual cues. As predicted by our model, both laboratory and field data confirmed that gut evacuation was linear and characterized by a rate constant (i.e., instantaneous rate of gut evacuation) that was independent of initial gut fullness. Rate constants were, however, influenced by fish size and in some cases by the size of food particles. Analysis of triplicate time courses of gut evacuation in the field showed that larger larvae evacuated food at a relatively higher rate than did smaller larvae.
Assemblage Structure of Eastern Pacific Groundfishes on the U.S. Continental Slope in Relation to Physical and Environmental Variables
Authors: Tolimieri Nick , Levin Phillip S.
Published: February 2006

We analyzed data from the National Marine Fisheries Service continental slope trawl surveys (1999–2002) to examine patterns in eastern Pacific groundfish assemblage structure in relation to longitude, latitude, depth, temperature, and interannual variation. The slope surveys spanned approximately 32–48°N and 200–1,200‐m depths. We focused on the 26 most abundant species, which made up more than 95% of the catch in terms of biomass. Assemblage structure was strongly correlated with depth and latitude. For the most part, changes in assemblage structure appeared to be fairly continuous, although there were more‐abrupt changes at approximately 500–600 m and in the vicinity of Point Conception and Cape Mendocino, California, and Cape Blanco, Oregon. There was also an interaction between depth and latitude; more northerly sites had deeper scores on the canonical axes than did more southerly sites of comparable depth. Shallower sites also showed more variation in assemblage structure with latitude than did deeper sites. We were able to identify five assemblages on the continental slope. Pacific grenadiers Coryphaenoides acrolepis, giant grenadiers Albatrossia pectoralis, deepsea soles Embassichthys bathybius, longspine thornyheads Sebastolobus altivelis, California slickheads Alepocephalus tenebrosus, and roughtail skate Bathyraja trachura formed a deepwater assemblage with a broad latitudinal range. Southern species that inhabited very shallow waters included splitnose rockfish Sebastes diploproa, spotted ratfish Hydrolagus colliei, English soles Parophrys vetulus, stripetail rockfish Sebastes saxicola, chilipeppers Sebastes goodei, and shortbelly rockfish Sebastes jordani. Shallow‐water, midlatitude species included spiny dogfish Squalus acanthias, longnose skate Raja rhina, Pacific hakes Merluccius productus, rex soles Glyptocephalus zachirus, bigfin eelpout Lycodes cortezianus, and sandpaper skate Bathyraja interrupta. Darkblotched rockfish Sebastes crameri, arrowtooth flounder Atheresthes stomias, and Pacific Ocean perch Sebastes alutus were identified as a shallow, northerly assemblage. The final group—sablefish Anoplopoma fimbria, brown cat sharks Apristurus brunneus, aurora rockfish Sebastes aurora, Dover soles Microstomus pacificus, and shortspine thornyheads Sebastolobus alascanus—occurred at different depths over a range of latitudes and might be best described as a shallow–middepth and midlatitude–southern grouping.
Regrowth Interval Influences Productivity, Botanical Composition, and Nutritive Value of Old World Bluestem and Perennial Ryegrass Swards
Authors: Belesky David P.
Published: February 2006

Botanical composition of pasture in much of the Appalachian Region varies as weather patterns interacting with abiotic and biotic factors create conditions allowing a range of plant species to occupy temporal and spatial gaps in the stand. Field‐grown old world bluestem [Bothriochloa caucasia (Trin.) C.E. Hubb.] or perennial ryegrass (Lolium perenne L.) were defoliated at fixed time intervals (1‐, 2‐, or 4‐wk for old world bluestem and 2‐, 4‐, or 6‐wk intervals for perennial ryegrass). Herbage mass, sward botanical composition, and estimates of nutritive value were determined. White clover (Trifolium repens L.), black medic (Medicago lupulina L), and various common forbs and grasses volunteered in all stands. Old world bluestem yields ranged from 3.38 Mg ha−1 (1‐wk regrowth interval in 2002) to 9.42 Mg ha−1 (4‐wk regrowth interval in 2000). Perennial ryegrass yield increased with increasing regrowth interval in 2002, ranging from 3.16 to 7.29 Mg ha−1. The longest regrowth interval did not necessarily lead to the greatest productivity. Old world bluestem swards clipped at 4‐wk intervals decreased 60% by the third growing season, whereas perennial ryegrass swards clipped at 6‐wk intervals increased by 37%. The proportion of encroaching species increased substantially in perennial ryegrass but not old world bluestem swards by 2002, suggesting that combined effects of repeated defoliation and weather influenced sward composition and productivity. Choice of plant resource, timing and intensity of defoliation, and very likely nutrient inputs coinciding with requirements of sown species could influence sward composition and help manage diversity to sustain productivity.
Soil Test Calibration for Predicting Corn Response to Phosphorus in the Northeast USA
Authors: Heckman J. R. , Jokela W. , Morris T. , Beegle D. B. , Sims J. T. , Coale F. J. , Herbert S. , Griffin T. , Hoskins B. , Jemison J. , Sullivan W. M. , Bhumbla D. , Estes G. , Reid W. S.
Published: February 2006

The consensus of soil fertility specialists working in the northeast USA was that soil testing and recommendation systems for P needed to be reexamined because of recent changes in soil testing methodology in the laboratory and corn (Zea mays L.) production technology in the field. Soil tests (M‐COL, MM‐COL, B‐ICP, M1‐ICP, and M3‐ICP) were performed by either colorimetry or inductively coupled plasma (ICP) emission spectroscopy on samples from soil test calibration studies conducted during 1998 to 1999 at 51 experimental sites chosen to represent a range of soils, including Ultisols, Spodosols, and Alfisols, in northeastern states (Connecticut, Delaware, Massachusetts, Maryland, Maine, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and West Virginia). The mean P measured by M‐COL, MM‐COL, B‐ICP, M1‐ICP, and M3‐ICP was 8.3, 6.6, 148, 66, and 121 mg P kg−1, respectively. Production practices followed local state extension recommendations at each site and included P fertilizer treatments: none, 15 kg P ha−1 banded, or 60 kg P ha−1 broadcast. Combined analysis of variance over sites showed that plant height at 35 d after planting, silk emergence, grain yield, and grain dry down were enhanced by the broadcast P treatment. There were yield increases (P < 0.10) to the band treatment at only four sites and to the broadcast treatment at nine sites. Cate‐Nelson statistical analysis of relative yield in relation to soil test P failed to identify soil test P critical levels for any of the soil test methods. The percentage of experimental sites that had soil test P levels below the currently used critical levels in the region ranged from 14 to 65% of the sites. Results showed that 17 to 47% of those sites testing below the critical level exhibited a yield increase (P < 0.10) to broadcast P. Some of the yield responsive sites had soil test P above currently used critical levels. The calibration data obtained from the present study and the relationships examined between soil test P and relative yield do not necessarily validate the currently used soil test P critical levels nor does the data enable much refinement. This study shows that the current critical levels frequently permit both types of errors in soil test prediction; indicating a need for P fertilization when it may not be needed and not indicating a need for P fertilization when it may be needed. The second type of error is usually avoided by recommendations for crop removal rates of P.
Recovery of Nitrogen‐15–Labeled Hairy Vetch and Fertilizer Applied to Corn
Authors: Seo Jong‐Ho , Meisinger J. J. , Lee Ho‐Jin
Published: February 2006

Knowledge of the plant and soil recovery of nitrogen (N) from legume cover‐crop residues and fertilizer is needed to improve corn N use efficiency. Nitrogen‐15 labeled ammonium sulfate (AS) or hairy vetch (Vicia villosaRoth.) residues were applied at planting or AS at the six‐leaf stage (sidedressing) to silage corn (Zea maysL.) grown in 38‐cm–diameter by 60‐cm–deep microplots containing a Jungdong loam (coarse loamy, mixed, mesic, Typic Udifluvents) in Suwon, Korea. The recovery of the labeled N sources was followed over 2 yr into the corn grain, stover, and the 0‐ to 15‐cm depth of soil. Recovery of labeled N in the first‐year corn was 32% of the planting‐applied AS, 15% of planting‐applied hairy vetch (HV) residues, and 46% of the sidedress AS. Conversely, the post‐harvest soil contained more labeled N from the HV residues (38%) compared with planting AS (15%) or sidedress AS (14%). Total first‐year recoveries of15N in crop plus soil after harvest were 47% for planting AS, 54% for HV residues, and 60% for sidedress AS, which are consistent for high summer rainfall (850 mm) climates. The second‐year corn showed low availability of residual15N, although HV residues supplied about twice as much N (3.5%) as AS (1.5%). These results are consistent with other studies and show that AS is about twice as effective as legume residues in supplying N to a crop, whereas legume residues contribute about twice as much N to the soil.
Wheat Effect on Frost‐Seeded Red Clover Cultivar Establishment and Yield
Authors: Singer Jeremy W. , Casler Michael D. , Kohler Keith A.
Published: February 2006

Frost‐seeding red clover (Trifolium pratense L.) into winter cereals is a cost effective establishment method. Abiotic effects on seedling establishment have been reported, but information on cultivar differences is lacking. The objectives of this study were to quantify the effect of winter wheat (Triticum aestivum L.) on the establishment, persistence, and forage dry matter (DM) production of 15 red clover cultivars of diverse origin. Cultivars were frost‐seeded near Ames, IA in March of 2003 and 2004 and Prairie du Sac, WI in 2004. Presence of the wheat crop caused 19 and 23% mortality in 2003 and 2004 compared with the no‐wheat treatment in Iowa and 51% mortality in 2004 in Wisconsin. Dry matter yield of diploid cultivars exceeded tetraploids in all environments (439 vs. 559 g m−2). Favorable conditions for germination and emergence in 2003 resulted in high plant densities and no relationship between post‐wheat red clover density and DM yield. In 2004, unfavorable environmental conditions reduced plant densities, creating a relationship between red clover density (x) and DM yield (y) (y = 305 + 8.86x, R2 = 0.65 in Iowa; y = 382 + 3.83x, R2 = 0.22 in Wisconsin). The southern cultivar Cherokee generally had greater performance than the average northern cultivar. Differences across years and locations were inconsistent for elite and land races. Within different origins and selection histories, large variability exists in cultivar performance. More data are needed to determine if the cultivar‐by‐wheat interaction is important for screening cultivars for dual grain/forage systems.
Bradyrhizobium japonicum Preincubated with Methyl Jasmonate Increases Soybean Nodulation and Nitrogen Fixation
Authors: Mabood Fazli , Zhou Xiaomin , Smith Donald
Published: February 2006

Jasmonates (jasmonic acid and methyl jasmonate) are naturally occurring plant hormones biosynthesized in response to wounding and biotic and abiotic stresses. Besides their role in planta, they can act as signaling molecules in soybean (Glycine max)–Bradyrhizobium symbioses by inducing the transcription of nodulation genes. Previous studies have shown that inoculation of soybean with Bradyrhizobium japonicum preinduced with genistein (Ge) or methyl jasmonate (MeJA) promoted soybean nodulation and N fixation under controlled environment conditions. We conducted two separate field experiments in the year 2002 to study the effect of preinducing B. japonicum strains with methyl jasmonate (MeJA), alone or in combination with Ge, on nodulation and N fixation under field conditions. Two B. japonicum strains (532C and USDA3) and four inducer treatments (control, MeJA, Ge, and MeJA plus Ge) were formulated. Genistein and MeJA increased nodule number, nodule dry weight per plant, and seasonal N fixation, as compared with the control treatment, inoculated with uninduced B. japonicum. These results demonstrate that methyl jasmonate alone or in combination with Ge can be used to promote soybean nodulation and N fixation under short‐season field conditions.
Sward Structure of Simple and Complex Mixtures of Temperate Forages
Authors: Sanderson M. A. , Soder K. J. , Brzezinski N. , Taube F. , Klement K. , Muller L. D. , Wachendorf M.
Published: February 2006

Sward composition and structure influence herbage intake of grazing animals. We conducted a grazing study to examine how forage mixture complexity affected sward structure. Replicated 1‐ha pastures (Hagerstown silt loam soil: fine, mixed, semiactive, mesic, Typic Hapludalf) were planted to either orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.) or a nine‐species mixture [orchardgrass, tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus corniculatus L.), white clover, alfalfa (Medicago sativa L.), and chicory (Cichorium intybus L.)]. Pastures were stocked rotationally with lactating dairy cows (Bos taurus). Herbage mass, sward height, vertical structure, and nutritive value were measured pre‐ and postgrazing during four periods in each of 2002 and 2003. Pregrazing sward height was similar between the mixtures. Pregrazing herbage mass and sward bulk density were 30% less in the two‐species mixture than the nine‐species mixture in 2002 but similar in 2003. The nine‐species mixture had more herbage dry matter in the upper sward layers than the two‐species mixture. Bulk density of herbage dry matter increased and nutritive value decreased from the top to the bottom of both swards. Cattle grazed deeper into the two‐species sward (18 cm) than the nine‐species mixture (11 cm) in 2003; however, individual botanical components in the upper 25 cm of the canopy were removed similarly between treatments. We conclude that sward structure did not alter the pattern of herbage removal during grazing of simple or complex swards.
Early‐Maturing Soybean in a Wheat–Soybean Double‐Crop System Yield and Net Returns
Authors: Kyei‐Boahen S. , Zhang L.
Published: February 2006

Double‐cropping soybean [Glycine max (L.) Merr.] after harvesting wheat (Triticum aestivum L.) is an important production system in the mid‐southern USA. Field studies were conducted at Stoneville, MS (33°26′ N lat) to evaluate the seed yield and net returns from early soybean maturity groups grown in a double‐crop system under limited irrigation and to compare the results with those from a full‐season system. Soybean cultivars from maturity groups (MG) III, IV, and V were used. Double‐cropped soybean yields ranged from 2055 to 3767 kg ha−1 and were 10 to 40% lower than their full‐season counterparts. For both systems, the average yield and net returns from MG IV, in particular the late IV cultivars, were among the highest, whereas those from MG III and late V were generally the lowest. The net returns from the full‐season soybean averaged $85 to 274 ha−1 higher than those from the double‐cropped soybean; however, the net returns from the double‐cropped wheat more than compensated for these differences. The 3‐yr average wheat yield was 5170 kg ha−1 and accounted for more than 60% of the combined net returns from the double‐crop system. These results indicate that yields and net returns from double‐cropped MG III or IV soybean could be equal or greater than MG V cultivars, but the late MG IV provided the highest yield and economic return. The data indicated that wheat–soybean double‐crop system using MG III or IV under limited irrigation was more profitable than the full‐season soybean system.
Synthesis, characterization and a thermal (TG-DSC) study of gadolinium and lutetium methanesulfonate coordination compounds with pyridine-N-oxide and 2-, 3- and 4-picoline-N-oxides
Authors: de Moura , de Matos , de Farias
Published: February 2006

The synthesis, characterization and a thermal (TG and DSC) study of the coordination compounds Gd(MS)3.(py-NO)2, Gd(MS)3.(2-picNO)2, Gd(MS)3 .(3-picNO)2, Gd(MS)3.(4-picNO)2, Lu(MS)3.(py-NO)2.2H2O, Lu(MS)3 (2-picNO)1.5.H2O, Lu(MS)3. (3-picNO) and Lu(MS)3.(4-picNO)2 are reported (MS = methanesulfonate, py-NO = pyridine-N-oxide, 2-picNO, 3-picNo and 4-picNO are 2-, 3- and 4-picoline-N-oxides, respectively). The observed thermal stability trend is: 2-picNO < py-NO < 4-picNO < 3-picNO for Gd and 2-picNO < 4-picNO < 3-picNO < py-NO for Lu. It was shown that the release of ligand molecules (endothermic) is followed by the thermal degradation of the ligands (exothermic).
Polynuclear coordination precursors compounds for M3Fe5O12 garnets (M=Y, Eu, Gd and Er), Part I: Synthesis of the precursors
Authors: Patron Luminita , Carp Oana , Mindru Ioana , Marinescu Gabriela , Stanica Nicolae , Balint Ioan
Published: February 2006

Anew type of complexes compounds (NH4)6[M3Fe5(C4O5H4)6(C4O5H3)6]. 16H2O (where M(III) = Y, Eu, Gd, Er), (NH4)6[M3Fe5(C4O6H4)6(C4O6H3)6]. 16H2O (where M(III) = Gd, Er) and (NH4)6[M3Fe5(C6O7H10)6(C6O7H9)6]. xH2O (where M(III) = Y; x = 8; M(III) = Eu, Er; x = 22) [C4O5H4 2? = malate anion C4O6H42? = tartarate anion, C6O7H11 ? = gluconate anion_ have been synthesized and characterised by elemental chemical analysis and physico-chemical measurements (IR, UV-Vis spectroscopy and magnetic determinations). The synthetic possibilities offered by the use of these new compounds as potential precursors for garnets have been suggested.
Bimetallic Cd(II) and Hg(II) complexes of 1, 4-bis-(5-H/methyl/chloro-1H-benzimidazol- 2-yl)-1, 2, 3, 4-butanetetraols
Authors: Tavman Aydin
Published: February 2006

The bimetallic complexes of 1,4-bis-(5-H/methyl/chloro-1H-benzimidazol 2-yl)-1,2,3,4-butanetetraols (L1?L3) with CdCl2 and HgCl2 were synthesized and characterized by elemental analysis, molar conductivity, as well as IR and 1H-NMR spectroscopy. The ligands coordinate to the metal ion through all of the hydroxyl oxygen atoms as tetradentate in the Hg(II) complexes of L1?L3 and in the Cd(II) complexes of L2 and L3. In theCd2(L1)Cl4 complex, the ligand acts as tetradentate through the benzimidazole nitrogen atoms and the two oxygen atoms of the hydroxyl groups near the imidazole ring.
Physicochemical properties of 3, 4, 5–trimethoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)
Authors: Ferenc Wieslawa , Walków-Dziewulska Agnieszka , Sarzynski Jan
Published: February 2006

The complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3,4,5-trimethoxybenzoic acid anion of the formula: M(C10H11O5)2.nH2O, where n = 6 for Ni(II), n = 1 for Mn(II), Co(II), Cu(II), and n = 0 for Zn, have been synthesized and characterized by elemental analysis, IR spectroscopy X?ray diffraction measurements, thermogravimetry and magnetic studies. They are crystalline compounds characterized by various symmetry. They decompose in various ways when heated in air to 1273 K. At first, they dehydrate in one step and form anhydrous salts. The final products of decomposition are oxides of the respective metals (Mn2O3, Co3O4, NiO, CuO, ZnO). The solubilities of the analysed complexes in water at 293 K are in the orders of 10-2 ? 10-4 mol dm-3. The magnetic susceptibilities of the Mn(II), Co(II), Ni(II) and Cu(II) complexes were measured over the range of 76?303 K and the magnetic moments were calculated. The results show that the 3,4,5-trimethoxybenzoates of Mn(II), Co(II) and Ni(II) are high-spin complexes but that of Cu(II) forms a dimer [Cu2(C10H11O5)4(H2O)2]. The carboxylate groups bind as monodentate or bidentate chelating or bridging ligands.
Magnetic, thermal and spectroscopic features of 2, 3- and 3, 5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II)
Authors: Ferenc Wieslawa , Walków-Dziewulska Agnieszka , Sarzynski Jan
Published: February 2006

The 2,3- and 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) were synthesized as solids and their magnetic, spectral and thermal properties studied. The complexes are hydrated or anhydrous compounds which possess colors typical of the M(II) ions. Their thermal stabilities were examined in air and nitrogen and the gaseous and solid state decomposition products were also identified. The magnetic susceptibilities of the complexes were measured over the temperature range 4.4?300 K and the magnetic moments were calculated. The results show that the 2,3- and 3,5-dimethoxybenzoates of Co(II) and Ni(II) are high-spin complexes with weak ligand fields, and that the complexes of Cu(II) form dimers.
Reaction of a satirically hindered iron(III) porphyrin with peroxyacetic acid: Degradation kinetics
Authors: Prakash P. , Francisca Mary
Published: February 2006

A kinetic analysis of the reaction between peracetic acid (AcOOH), and tetrakis (pentafluorophenyl) - 21H, 23H-porphine iron(III) chloride Fe(F20TPP)Cl, in acetonitrile showed that the peracetic acid oxidatively destroys Fe(F20TPP)Cl. This is in contrast to an assumption that the oxidative degradation of metalloporphyrins can be prevented by the introduction of electron-withdrawing substituents into the phenyl groups of the porphyrin ligand. A UV-visible spectroscopic study showed a degree of macro cycle destruction of the tetrapyrrole conjucation of the metalloporphyrin. The degradation takes place via oxoperferryl species. The first step of the reaction mechanism is the reversible formation of an adduct ?X? (k1/k-1) between Fe(F20TPP)Cl and peracetic acid, followed by an irreversible step (k2) for the formation of oxoperferryl species.
Thiocyanatochrome complexes in analytical chemistry: Determination of osmium(III)
Authors: Bratulescu George , Ganescu Ion , Ganescu Anca
Published: February 2006

New complex combinations of Os(III) complexed with thiourea and ethyl thiourea, as well as of complex anions of Cr(III) analogues of Reineke?s salt, [Cr(CNS)4(amine)2]-, where the amine is aniline, benzylamine morpholine etc., were synthesized. New gravimetric, oxidimetric and spectrophotometric analytical methods are proposed for the determination of Os(III). The experimental data were statistically processed and are not affected by systematic errors.
Cobalt(II) complexes with aromatic carboxylates and N-functionalized cyclam bearing 2-pyridylmethyl pendant arms
Authors: Vuckovic Gordana , Stanic V. , Sovilj Sofija , Antonijevic-Nikolic M. , Mrozynski J.
Published: February 2006

Novel binuclear Co(II) complexeswithN-functionalized cyclam N,N?,N",N???-tetrakis( 2-pyridylmethyl)tetraazacyclotetradecane (tpmc) and one of the aromatic monoor dicarboxylato ligands (benzoate, phthalate or isophthalate ions) were prepared. They were analyzed and studied by elemental analyses (C, H, N), electrical conductivities, VIS and IR spectroscopy andmagnetic as well as cyclic voltammetric measurements. In [Co2(C6H5COO)2tpmc]ClO4)2.3H2O, the benzoate ligands are most probably coordinated as chelates in the trans-position to each Co(II) and the macrocycle adopts a chair conformation. In the complexes [Co2(Y)tpmc]ClO4)2.zH2O, (Y = phthalate or i-phthalate dianizon, z = 2; 4) it is proposed that the isomeric dicarboxylates are bonded combined as bridges and chelates. The composition and the assumed geometries of the complexes are compared with the, earlier reported, corresponding Cu(II) complexes. Cyclic voltammetry measurements showed that the compounds are electrochemically stable.
NMR analysis of (1S, 1aR, 6aR)-2’, 3’, 6, 6a-tetrahydrospiro cycloprop a indene-1(1aH), 1’- 1H indene
Authors: Spiteller Peter , Jovanovic Jovan , Spiteller Michael
Published: February 2006

The aldol condensation product of 1H-indan-1-one, (2E)-2-(2,3-dihydro-1H-in den-1-ylidene)-2,3-dihydro-1H-inden-1-one, subjected to Huang?Minlon reduction conditions was shown, via 1D and 2D NMR analysis, to be a mixture of (1S,1aR,6aR)-2?,3?,6,6a-tetrahydro-spiro cycloprop a indene-1(1aH),1? 1H indene and its 1R,1aS,6aS enantiomer and not 2,3,1?,3?-tetrahydro- 1,2? -biindenylidene as originally expected. The full NMR assignment, the coupling constants in the proton NMR, and the couplings in the HMBC and NOESY of the title compound are summarized in the Table.
A regioselective alkylation at the C-6 hydroxyl group of erythromycin A-oxime derivatives
Authors: Master Hosang , Dharmendra Singh
Published: February 2006

Erythromycin A contains five hydroxyl groups. The regioselective alkylation at the C-6 hydroxyl group was achieved to an extent of more than 97 % when a 9-O-substituted erythromycin A-9-oxime was employed as the substrate.
Synthesis and antibacterial activity of some Schiff bases derived from 4-aminobenzoic acid
Authors: Parekh Jigna , Inamdhar Pranav , Nair Rathish , Baluja Shipra , Chanda Sumitra
Published: February 2006

The following Schiff bases have been synthesized: (1) 4-(2-chlorobenzylidene)amino benzoic acid JP1, (2) 4 (furan-2-ylmethylene)amino benzoic acid JP2, (3) 4-[(3-phenylallylidene)amino]benzoic acid JP3, (4) 4 (2-hydroxybenzylidene)amino benzoic acid JP4, (5) 4 (4-hydroxy-3-methoxybenzylidene)amino benzoic acid JP5 and (6) 4 (3-nitrobenzylidene)amino benzoic acid JP6. They were screened as potential antibacterial agents against a number of medically important bacterial strains. The antibacterial activity was studied against A. faecalis ATCC 8750, E. aerogenes ATCC 13048, E. coli ATCC 25922, K. pneumoniae NCIM 2719 S. aureus ATCC 25923, P. vulgaris NCIM 8313, P. aeruginosa ATCC 27853 and S. typhimurium ATCC 23564. The antibacterial activity was evaluated using the Agar Ditch method. The solvents used were 1,4-dioxane and dimethyl sulfoxide. Different effects of the compounds were found in the bacterial strains in vestigated and the solvents used, suggesting, once again, that the antibacterial activity is dependent on the molecular structure of the compound, the solvent used and the bacterial strain under consideration. In the present work, 1,4-dioxane proved to be a good solvent in inhibiting the above stated bacterial strains.
Green chemistry approach to the synthesis of potentially bioactive aminobenzylated Mannich bases through active hydrogen compounds
Authors: Vasoya S.L. , Chovatia P.T. , Purohit D.H. , Joshi H.S.
Published: February 2006

An efficient and high yield method for the synthesis of aminobenzylated Mannich bases is described. The synthesis occurs in aqueous medium at 0 ?C. The compounds show moderate antitubercular and antimicrobial activities.
Acidity of HOCN, HSCN, HNCO, HNCS: A treatment from the viewpoint of ab initio approach
Authors: Pankratov Alexei , Khmelev Sergei
Published: February 2006

The electronic structures of the molecules HOCN, HSCN, HNCO, HNCS and the anions OCN -, SCN - have been investigated ab initio at the RHF/6-31G(d) RHF/6-31G(d,p), MP2/6-31G(d)//RHF/6-31G(d) and MP2/6-31G(d,p)//RHF/6-31G(d,p) theory levels. The thermodynamic stability of the HNCO and HNCS molecules was shown to be higher than that of the HOCH and HSCN molecules, respectively. The following series of the alteration of the protolytes strength HSCN > HOCH HNCS > HNCO, HOCN > HNCO, HSCN > HNCS was substantiated. The computations taking into account the electronic correlation (MP2/6-31G(d)//RHF/6-31G(d) and MP2/6-31G(d,p)//RHF/6-31G(d,p)) reflect the general sequence of change in the pro- ton-donor properties: HSCN > HOCN > HNCS > HNCO, coinciding with the order of descending hydrophobicity of the compounds. The comparative proton-donor ability of the above acids in aqueous solutions is determined basically from the electronic structure and size of their molecules and anions OCN -, SCN -, but not on medium effects.
Electron content of rings of fully benzenoid hydrocarbons
Authors: Gutman Ivan , Furtula Boris , Jeremic Svetlana , Turkovic Nedzad
Published: February 2006

The distribution of -electrons in rings of fully benzenoid hydrocarbons was investigated. It was found that the electron content EC of "full" rings varies significantly (between 5.5 and 2.5 electrons), and depends on the annelation mode, mainly on the number of adjacent rings. "Full" rings belonging to the same annelation class have nearly equal EC-values. The EC-values of all "empty" rings are also nearly equal (around 2 electrons).
A sorption study of Pd(II) on aminomethylphosphonic Purolite resin S-940
Authors: Paduraru Carmen , Bilba Doina , Sarghie Ioan , Tofan Lavinia
Published: February 2006

Many methods for the preconcentration-recovery of platinic metals are based on complexing sorbents. As platinic metals have a high tendency to form com plexes, the complex-forming sorbents are particularly useful. This study concerns the sorption of Pd(II) on aminomethylphosphonic Purolite S-940 resin. In order to establish the optimum conditions of Pd(II) sorption on S-940 resin, the influence of the following experimental conditions: solution pH, Pd(II) initial concentration and temperature were studied. The yield of Pd(II) recovery was maximum in buffer solutions of pH 3?5 and decreases with increasing initial concentration of the solution. The equilibrium distribution of Pd(II) between the two phases (sorbent and solution) is described by the Langmuir model of monomolecular layer adsorption. The thermodynamic quantities characteristic for the Pd(II) sorption process suggest an affinity of the Purolite resin S-940 for Pd(II).
Determination of boron in the waters of Troia by inductively coupled plasma-atomic emission spectrometry (ICP-AES)
Authors: Ozcan Hasan , Yilmaz Selahattin
Published: February 2006

The inductively coupled plasma-atomic emission spectrometry method (ICP-EAS) is proposed for the determination of boron in Troia water sources. In this study, boron samples were taken from 25 different locations during November 2002 and May 2003. The 249.773 nm boron emmision line was not affected by the sample matrix. The boron content was determined without further pretreatment of samples proposed ICP-AES method. An analysis of a given sample was completed in about 15 min. The determined boron concentrations in surface and ground water sources were between 0.00444?1.11200 mg l-1. In order to compare the results obtained by the proposed method, selected water samples were also analysed titrimetically. Pearson correlation coefficient analysis showed that there is a close relationship between the ICP-AES and the titrimetric method and the determination coefficient (R2) was calculated to be 91.34 %.
Tetrabutylammonium fluorochromate(VI)(TBFAC): A mild and efficient reagent for oxidation of organic substrates
Authors: Ghammami Shahriare , Sajadi Seyed
Published: February 2006

Orange solid tetrabutylammonium fluorochromate, (C4H9)4NCrO3F, TBAFC, is easily synthesized by the reaction of tetrabutylammonium fluoride with CrO3 in a 1:1 mole ratio. Tetrabutylammonium fluorochromate(VI) is a versatile reagent for the effective and selective oxidation of organic substrates, in particular of alcohols, under mild conditions. The facile oxidation of triphenylphosphine to triphenylphosphine oxide by TBAFC in CH3CN provides clear evidence for an oxygen-transfer reaction. .
The influence of some factors on the electrical conductivity and particle size of core/shell polystyrene/polyaniline composites
Authors: Nestorovic Gordana , Jovanovic Slobodan , Jeremic Katarina
Published: February 2006

The electrically conductive, micron-sized, core/shell polystyrene (PS)/polyaniline (PANI) composite particles were synthesized by chemical oxidative polymerization of aniline in the presence of micron-sized PS particles in 1 M HCl. The conditions of the dispersion polymerization of styrene were optimized. The influence of the initiator type employed for the chemical oxidative polymerization of aniline and the aniline (ANI) concentration on the PS/PANI particle size and size distribution and their conductivity was investigated. The obtained results show that the conductivity of the samples increased with increasing ANI concentration. The conductivity of the PS/PANI composite particles obtained with the highest ANI concentration was of the same order of magnitude as that for PANI powder. The particle size did not depend on the concentration of ANI, while the particle size distribution was narrower at higher concentrations of ANI. .
Metal ion promoted synthesis of pentaazamacrocyclic complexes of a few first row transition metal series derived from 2,6-diaminopyridine
Authors: Khan Ali , Tabassum Shabana , Begum Nishat , Chingsubam Poonam
Published: February 2006

Anew series of dichloro/dinitrato (2,6,9,13,18-pentaazacbicyclo [12.3.1]octadeca -1(18),14,16-triene) metal(II) [MLX2](M = Mn(II), Co(II), Ni(II) and Zn(II); X = Cl or NO3) and (2,6,9,13,18-pentaazacyclo[12.3.1]octadeca-1(18),14,16-triene) copper(II) dichloride/dinitrate [CuL]X2 (X = Cl or NO3) have been synthesized by the template condensation reaction of 2,6-diaminopyridine with 1,2-diaminoethane and 1,3-dibromopropane. The complexes were studied by elemental analysis, magnetic susceptibility and conductivity measurements. Various spectroscopic techniques, viz. IR, 1H-NMR, EPR, UV/Vis, were used to establish their structures. Except for the complexes of copper(II), which are square planar, all other complexes have octahedral structures.
Some insights into the reactivity of oxovanadium phosphate: Synthesis and characterization of an VOPO4-H2N(CH2)3NH2 coordination compound
Authors: de Farias , Airoldi Claudio
Published: February 2006

The lamellar matrix of VOPO4?2H2O was used as the host species to prepare a VOPO4-1,3-diaminopropane coordination compound. The oxovanadium matrix and the synthesized hybrid were characterized by elemental analysis, infared spectroscopy, thermogravimetry, X-ray diffractometry and SEM microscopy. The elemental analysis results, as well as the X-ray diffraction patterns and quantum chemical calculations, strongly suggest that the synthesized matrix is an equimolar (1:1) mixture of two compounds with the formulas VOPO4?[H 2N-(CH2)3-NH2] and VOPO4?[H2N-(CH2)3-NH2]0.5. The SEM micrographs obtained for the VOPO4- diaminopropane hybrid matrix show that the microstructure of VOPO4?2H2O is changed after reaction, with an overall exfoliation of the oxovanadium matrix.
Non-isothermal kinetic characterisation of a gas-solid reaction by TG analysis
Authors: Cupic Zeljko , Jovanovic Dusan , Krstic Jugoslav , Vukelic Nikola , Nedic Zoran
Published: February 2006

A series of silica-supported Ni-catalyst precursors was synthesized, with different SiO2/Nimole ratios between 0.2 and 1.15. The reduction of all the prepared samples was studied by thermogravimetry (TG) in a hydrogen flow. The results of the TG analysis were analyzed by the multi-thermal history model-fitting method, with non-linear regression. The activation energies for the reduction of each sample were determined. The statistical F-test was performed to discriminate between various models. It was found that increasing the SiO2/Ni mole ratio leads to a change in the reaction mechanism of the nickel reduction, resulting finally in a change from second order reaction kinetics to three halves order reaction kinetics.
Viscosities of binary mixtures of toluene with butan-1-ol and 2-methylpropan-2-ol
Authors: Dumitrescu Vasile , Pântea Octav
Published: February 2006

The viscosities of binary liquid mixtures of toluene with butan-1-ol and 2-methylpropan-2-ol have been determined at 298.15, 303.15, 308.15, 313.15 and 318.15 K over the whole concentration range. The Hind, Grunberg-Nissan, Wijk, Auslander and McAllister models were used to calculate the viscosity coefficients and these were compared with the experimental data for the mixtures. Excess viscosities were also calculated and fitted to the Redlich-Kister equation. Various thermodynamic properties of viscous flow activation were determined and their variations with composition are discussed.
Purification of natural zeolite-clinoptilolite for medical application: Extraction of lead
Authors: Tomasevic-Canovic Magdalena
Published: February 2006

A series of experiments of the leaching of lead and other cations from three samples of natural zeolite-clinoptilolite, (Sample 1-deposit Zlatokop, Vranjska Banja, Serbia and Montenegro; Sample 2-deposit Bala Mare, Romania; Sample 3-Igros near Brus, Serbia and Montenegro) using EDTA was conducted. The results of the experiments showed that the extraction efficiencies from the examined samples were different. If a sufficiently large amount of EDTA was applied, most of the lead was extracted only from Sample 1-deposit Zlatokop. Similar effects were obtained for the leaching of iron. The differences in the extraction efficiencies may be due to the difference of the of lead and iron species present in the zeolite crystals. The effects of EDTA concentration and solid/liquid ratio on the extraction of lead, iron and aluminum were studied.
Sodium dithionite as a selective demasking agent for the complexometric determination of thallium
Authors: Shetty Prakash , Shetty Nityananda
Published: February 2006

Sodium dithionite is proposed as a new demasking agent for the rapid and selective complexometric determination of thallium(III). In the presence of diverse metal ions, thallium (III) was first complexed with excess EDTA and the surplus EDTA was then titrated with a standard zinc sulphate solution at pH 5-6 (hexamine buffer) using Xylenol Orange as the indicator. The EDTA equivalent to thallium was then released selectively with sodium dithionite and back titrated with a standard zinc sulphate solution as before. Reproducible and accurate results were obtained in the range 4-100 mg of thallium with a relative error of +-27 % and a coefficient of variation (n = 6) of not more than 0.30 %. The effects of various diverse ions were studied. The method was applied to the determination of thallium in its complexes and in alloys.
Effects of localized horizontal flow patterns on eigenfrequencies of stellar global modes
Authors: Cadez V.M. , Vanlommel P.
Published: February 2006

The main goal of this paper is to estimate the significance of effects the flow profile U0(z) induces on computed global oscillation spectra. We solve numerically the eigenvalue problem for the described basic state configuration with reference to solar conditions as an example of a typical star. Obtained results show that the considered shear flows do not only affect the eigenfrequencies ? but they also have an impact on spatial profiles of eigensolutions of linearized physical quantities. Such flows may even allow for local amplification of perturbation amplitudes at positions where the resonant Doppler condition ? = kU0(z) is satisfied. For typical subsonic flow speeds this Doppler resonant wave amplification can be effective only in the case of the non acoustic gravity modes with sufficiently large horizontal wave numbers k.
Influence of solar X-ray flares on the earth-ionosphere waveguide
Authors: Grubor Davorka , Sulic D. , Zigman V.
Published: February 2006

A simultaneous analysis of solar are X-ray irradiance and VLF signal amplitude on the GQD/22.1 kHz trace was carried out. Solar are data were taken from GOES 12 satellite listings. The VLF amplitude data were recorded by means of the AbsPAL (Absolute Phase and Amplitude Logger) at the Institute of Physics, Belgrade, Serbia. It was found that solar are events from class C to class X affect the VLF signal amplitude in various ways and can be classified according to the type of effect produced in the Earth-ionosphere waveguide on the VLF propagation.
The mass of (1) Ceres obtained from four close encounters
Authors: Kovacevic Andjelka , Kuzmanoski Mike
Published: February 2006

The technique of asteroid mass determination from perturbation during close approach requires as many as possible different close approaches in order to derive reliable mass of a perturber. Here are presented some results for the mass of (1) Ceres obtained using newly found close approaches.
Some results regarding the comparison of the Earth's atmospheric models
Authors: Segan S. , Surlan B.
Published: February 2006

In this paper we examine air densities derived from our realization of aeronomic atmosphere models based on accelerometer measurements from satellites in a low Earth's orbit (LEO). Using the adapted algorithms we derive comparison parameters. The first results concerning the adjustment of the aeronomic models to the total-density model are given.
CCD measurements of double and multiple stars at NAO Rozhen
Authors: Pavlovic Rade , Cvetkovic Zorica , Olevic Dragomir , Strigachev A. , Popovic Georgije , Novakovic B.
Published: February 2006

With the 2-m telescope of the Bulgarian National Astronomical Observatory at Rozhen observations of fifteen multiple stars were carried out during one night - October 17/18, 2004. In the paper we present the results for the position angle and separation for ten multiple stars (27 pairs) which could be measured.
Scientific approaches to problems of mixtures sintering
Authors: Savitskii Arnold
Published: February 2006

Existing theories cannot convincingly explain relationships observed during sintering of mixtures and do not always help solve practical problems of sintering metal materials and ceramics. The main weakness of the known theories is insufficient attention to the phenomenon of alloy formation and its effect on volume changes of compacts, faulty ideas regarding driving forces for the sintering process, the mistaken mechanism of dissolution of solid phase in liquid, and the inaccurate mechanisms of growth and densification during the sintering of mixtures. Besides, obsolete theories are developed, as a rule, on the basis of a two-partial model that does not permit taking into account the skeleton structure of a powder body and the presence of interparticle pores in it. Essentially fresh concepts in the theory of mixture sintering are formulated and defined in this paper. The new approaches eliminate the drawbacks and discrepancies in the existing theories and provide the scientific basis for solid state and liquid phase sintering of mixtures.
A phenomenological analysis of sintering kinetics from the viewpoint of activated volume
Authors: Nikolic M.V. , Labus Nebojsa , Ristic Momcilo
Published: February 2006

The sintering kinetics of real systems has been viewed as a process of transport of activated volume. Activated volume is a parameter that can be used to describe mass transport during the sintering process. It defines the movement of point defects and dislocations during the sintering process. A phenomenological equation has been defined using this parameter, which can be applied to analyze kinetics of the sintering process. It has been applied to analyze the sintering process of several disperse systems. Values obtained for parameters of the equation have also been analyzed.