Thermoanalytical study of the complexes of 4-dimetilaminocinnamylidenepiruvate with manganese (II), cobalt (II), nickel (II), cupper (II), zinc (II) and lead (II), in the solid state

Solid state compounds M-4-DMCP, where 4-DMCP is 4-dimethylaminocinnamylidenepyruvate and M represents Mn (II), Co (II), Ni (II), Cu (II), Zn (II) and Pb (II) were prepared. These compounds were studied by thermoanalitycal techniques: thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray diffraction powder patterns and complexometric titration with EDTA. From the results obtained by the complexometric titration with EDTA, TG, DTG and DSC curves, was possible to establish the hydration degree, stoichiometry and thermal stability of the prepared compounds.

Thermal annealing effects on vanadium pentoxide xerogel films

The effect of water molecules on the conductivity and electrochemical properties of vanadium pentoxide xerogel was studied in connection with changes of morphology upon thermal annealing at different temperatures. It was demonstrated that the conductivity was increased for the samples heated at 150ºC and 270ºC compared to the vanadium pentoxide xerogel. It was also verified a stabilization of electrochemical processes of the insertion and de-insertion of lithium ions the structure of thermally annealed vanadium pentoxide.

Thermal degradation behaviour of some polydithiooxamide metal complexes

The thermal decomposition behavior of the Fe(II), Co(II), Ni(II) and Zn(II) complexes of polydithiooxamide has been investigated by thermogravimetric analysis (TGA) at a heating rate of 20°C min-1 under nitrogen. The Coats-Redfern integral method is used to evaluate the kinetic parameters for the successive steps in the decomposition sequence observed in the TGA curves. The processes of thermal decomposition taking place in the four complexes are studied comparatively as the TGA curves indicate the difference in the thermal decomposition behavior of these complexes. The thermal stabilities of these complexes are discussed in terms of repulsion among electron pairs in the valence shell of the central ion and electronegativity effects.

Thermal behaviour of TEGMMA copolymers obtained by photopolymerization using iron complexes

Copolymers of methyl methacrylate (MMA) and triethyleneglycol dimethacrylate (TEGDMA) obtained by photoinitiated polymerization using Fe(III) complexes were submitted to thermogravimetry (TGA) under dynamic air atmosphere and N2, and differential scanning calorimetric analysis (DSC). Thermal events were observed only between 90 - 110 ºC. Glass transitions were observed at ca. 100 ºC, followed by an exothermic peak at 170 ºC. The exothermic peak was assigned to a thermal curing process due to the presence of unreacted vinyl groups of the monomers. DSC revealed to be a useful tool to evaluate the curing completeness in this kind of material, using small amounts of sample in relatively short time.

Electrochemical study and dependence of 'transition state' in Co(II) and Ni(II) complexes with some antibiotics and cephalothin

Electrode kinetics and study of 'transition state' with applied potential in case of [M - antibiotics - cephalothin] system were reported at pH = 7.30 ± 0.01 at suitable supporting electrolyte at 25.0ºC. The M = Co or Ni and antibiotics were doxycycline, chlortetracycline, oxytetracycline, tetracycline, minocycline, amoxicillin and chloramphenicol used as primary ligands and cephalothin as secondary ligand. Kinetic parameters viz. transfer coefficient (a), degree of irreversibility (l), diffusion coefficient (D) and rate constant (k) were determined. The values of a and k varied from 0.41 to 0.59 and 2.60 X 10-3 cm s-1 to 9.67 X 10-3 cm s-1 in case of [Co - antibiotics - cephalothin] system. In case of [Ni - antibiotics - cephalothin], a and k varied from 0.41 to 0.58 and 2.34 X 10-3 cm s-1 to 9.19 X 10-3 cm s-1 respectively confirmed that transition state behaves between oxidant and reductant response to applied potential and it adjusts it self in such a way that the same is located midway between dropping mercury electrode and solution interface. The values of rate constant confirmed the quasireversible nature of electrode processes. The stability constants (logb) of complexes were also determined.

Complexes of 3,4-dimethoxybenzoic acid anion with Cu(II), Co(II), La(III), and Nd(III)

Physico-chemical properties of 3,4-dimethoxybenzoates of Co(II), Cu(II), La(III) and Nd(III) were studied. The complexes were obtained as hydrated or anhydrous polycrystalline solids with a metal ion-ligand mole ratio of 1 : 2 for divalent ions and of 1 : 3 in the case of trivalent cations. Their colours depend on the kind of central ion: pink for Co(II) complex, blue for Cu(II), white for La(III) and violet for Nd(III) complexes. The carboxylate groups in these compounds are monodentate, bidentate bridging or chelating and tridentate ligands. Their thermal decomposition was studied in the range of 293-1173 K. Hydrated complexes lose crystallization water molecules in one step and form anhydrous compounds, that next decompose to the oxides of respective metals. 3,4 - Dimethoxybenzoates of Co(II) is directly decomposed to the appropriate oxide and that of Nd(III) is also ultimately decomposed to its oxide but with the intemediate formation of Nd2O2CO3.. The magnetic moment values of 3,4-dimethoxybenzoates determined in the range of 76-303 K change from 4.22 µB to 4.61 µB for Co(II) complex , from 0.49 µB to 1.17 µB for Cu(II) complex , and from 2.69 µB to 3.15 µB for Nd(III) complex.

Stability constants and thermodynamic parameters of cadmium complexes with sulfonamides and cephapirin

Stability constant (log beta) and thermodynamic parameters of Cd2+ complexes with sulfonamide and cephapirin were determined by Polarographic technique at pH = 7.30 ± 0.01 and µ = 1.0 M KNO3 at 250°C. The sulfonamides were sulfadiazine, sulfisoxazole, sulfamethaxazole, sulfamethazine, sulfathiazole, sulfacetamide and sulfanilamide used as primary ligands and cephapirin as secondary ligand. Cd2+ formed 1:1:1, 1:2:1 and 1:1:2 complexes. The nature of electrode processes were reversible and diffusion controlled. The stability constants and thermodynamic parameters (deltaG, deltaH and deltaS) were determined. The formation of the metal complexes has been found to be spontaneous, exothermic in nature, and entropically unfavourable at higher temperature.

Study of complexes of cadmium with some L-amino acids and vitamin-C by voltammetric technique

Voltammetric technique was used to study the binary and ternary complexes of cadmium with L-amino acids and vitamin-C (L-ascorbic acid) at pH =7.30 ± 0.01, µ = 1.0M KNO3 at 25ºC and 35ºC. Cd (II) formed 1:1:1, 1:1:2 and 1:2:1 complexes with L-lysine, L-ornithine, L-threonine, L-serine, L-phenylglycine, L-phenylalanine, L-glutamic acid and L-aspartic acid used as primary ligands and L-ascorbic acid used as secondary ligand. The trend of stability constant of complexes was L-lysine < L-ornithine < L-threonine < L-serine < L-phenylglycine < L-phenylalanine < L-glutamic acid < L-aspartic acid which can be explained on the basis of size, basicity and steric hindrance of ligands. The values of stability constant (log β) varied from 2.23 to11.33 confirm that these drugs i.e. L-amino acids or in combination with L-ascorbic acid or their complexes could be used against Cd (II) toxicity. The study has been carried out at 35ºC also to determine the thermodynamic parameters such as enthalpy change (ΔH), Free energy change (ΔG) and entropy change (ΔS) respectively.

A novel indicator reaction for the catalytic determination of V(V) at ppb levels by the kinetic spectrophotometric method

A novel sensitive and relatively selective kinetic method is presented for the determination of V(V), based on its catalytic effect on the oxidation reaction of Ponceau Xylydine by potassium bromate in presence of 5-sulfosalicylic acid (SSA) as activator. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Ponceau Xylydine at 640 nm between 0.5 to 7 min (the fixed time method) in H3PO4 medium at 25ºC. The effect of various parameters such as concentrations of H3PO4, SSA, bromate and Ponceau Xylydine, temperature and ionic strength on the rate of net reaction were studied. The method is free from most interferences, especially from large amounts of V(IV). The decrease in absorbance is proportional to the concentration of V(V) over the entire concentration range tested (1-15 ng mL−1) with a detection limit of 0.46 ng mL-1 (according to statistical 3Sblank/k criterion) and a coefficient of variation (CV) of 1.8% (for ten replicate measurement at 95% confidence level). The proposed method suffers few interferences such as Cr(VI) and Hg(II) ions. The method was successfully applied to the determination of V(V) in tap water, drinking water, bottled mineral water samples and a certified standard reference material such as SRM-1640 with satisfactory results. The vanadium contents of water samples were also determined by FAAS for a comparison. The recovery of spiked vanadium(V) was found to be quantitative and the reproducibility was satisfactory. It was observed that the results of the SRM 1640 were in good agreement with the certified value.

Complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III)

The complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) have been synthesized as polycrystalline hydrated solids, and characterized by elemental analysis, spectroscopy, magnetic studies and also by X-ray diffraction and thermogravimetric measurements. The analysed complexes have the following colours: violet for Nd(III), white for Gd(III) and cream for Ho(III) compounds. The carboxylate groups bind as bidentate chelating (Ho) or bridging ligands (Nd, Gd). On heating to 1173K in air the complexes decompose in several steps. At first, they dehydrate in one step to form anhydrous salts, that next decompose to the oxides of respective metals. The gaseous products of their thermal decomposition in nitrogen were also determined and the magnetic susceptibilites were measured over the temperature range of 76-303K and the magnetic moments were calculated. The results show that 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) are high-spin complexes with weak ligand fields. The solubility value in water at 293K for analysed 4-chlorophenoxyacetates is in the order of 10-4mol/dm³.

Formation of polyelectrolyte multilayers and polyelectrolyte complexes in dual polymer treatment of papermaking pulp

The goal of this study was to find a new approach to modify chemically the properties of paper by improving fiber quality. This Master’s thesis includes the multiple polymer treatment in general and themeasurement methods with which the formation of multilayers and complexes can be noticed. The treatment by an oppositely charged dual polymer system is a good approach to increase paper strength. In this work, starch, a cationic polymer, and carboxymethyl cellulose (CMC), an anionic polymer, were used step-by-step to improve paper strength. The adsorption of cationic starch and CMC on cellulose fibers were analyzed via polyelectrolyte titration. The results showed that paper strength was enhanced slightly with a layer-by-layer assembly of the polymers. However, if the washing stage, which was required for layer-by-layer assembly, was eliminated, the starch/CMC complex was deposited on fibers more efficiently, and the paper strength was improved more significantly.

Sinfonia IV : 1. versio, poistettu käytöstä

Soitinnus: orkesteri.

Biologia reprodutiva de Acacia mearnsii de wild. (Fabaceae) IV: visitantes florais

Para que as estratégias de melhoramento genético em espécies arbóreas tenham sucesso, o conhecimento da biologia reprodutiva da espécie envolvida é indispensável. Um dos fatores críticos ao sucesso reprodutivo das espécies do gênero Acacia é a presença de vetores para a polinização. Os objetivos deste trabalho foram identificar os visitantes florais em um plantio comercial de Acacia mearnsii De Wild. e quantificar as políades aderidas à superfície corporal dos insetos. As observações foram realizadas em uma torre localizada no plantio comercial durante o período de floração de 2002 e 2003. Os visitantes florais foram capturados no período diurno com o auxílio de rede entomológica e de um cesto aéreo instalado em um trator. No período noturno, os insetos foram capturados com o auxílio de armadilhas luminosas instaladas entre as copas florescidas. Foram observados insetos pertencentes às ordens Coleoptera, Hymenoptera, Diptera, Hemiptera e Lepidoptera. Os besouros da espécie Macrodactylus suturalis foram considerados como dispersores do pólen de acácia-negra, pela alta frequência de indivíduos presentes no povoamento estudado e pela grande quantidade de políades aderidas no corpo dos insetos capturados (X=229,36 políades/inseto). As abelhas da espécie Apis mellifera, embora tenha sido quantificada uma grande quantidade de políades nos indivíduos capturados (X=448,50 políades/inseto), não foram observadas com frequência na área analisada. Uma das formas recomendadas para aumentar a frequência de abelhas e vespas nos plantios comerciais de acácia-negra é a manutenção de fontes de néctar e a introdução de caixas com abelhas A. mellifera.

IV Armeijakunnan ilmatorjunnan järjestelyt vetäytymisvaiheen taisteluissa 1944

Suomen kohtaloa ratkaistiin kesällä 1944 Karjalan kannaksella. Neuvostoliiton suurhyökkäyksen tavoitteena oli vähintään pakottaa Suomi irtaantumaan sodasta, jotta neuvostojoukkoja voitaisiin käyttää saksalaisia vastaan Suomen muodostamasta sivustauhasta välittämättä. Alkuun suurhyökkäys näytti onnistuvan tavoitteessaan mutta suomalaiset onnistuivat pysäyttämään Neuvostoliiton hyökkäyksen Talin – Ihantalan kaksoistaistelussa. Torjuntavoitto saavutettiin kaikkien aselajien yhteistoiminnalla. Ilmatorjuntajoukot joutuivat taistelemaan ylivoimaista ilmavihollista vastaan. Varsinkin suurhyökkäyksen alussa vihollinen pyrki toimimaan ilmatorjunnasta piittaamatta, välillä itse ilmatorjunnan kimppuun hyökätenkin. Ilmatorjuntajoukot saavuttivat kuitenkin sen verran hyviä tuloksia, että ilmavihollinen joutui muuttamaan toimintatapojaan ja jopa toimimaan ilmatorjuntaa vältellen. Näinollen ilmatorjunnan voidaan katsoa hoitaneen tehtävänsä kunnialla siellä missä toimi, ilmatorjuntaa oli vain tarpeeseen nähden aivan liian vähän. Tutkimuksen tarkoituksena on esitellä lukijalle ilmatorjunnan järjestelyitä kyseisenä ajankohtana. Järjestelyillä pyrittiin luomaan ilmatorjunnalle edellytykset menestyksekkääseen toimintaan. Järjestelyihin katsottiin tässä tutkimuksessa kuuluvan johtaminen ja viestitoiminta, tulenkäytön johtaminen, tuliasematoiminta, yhteistoiminta sekä huolto. Taktiikkaa ja muita asioita käsitellään niiltä osin kuin niillä oli vaikutusta järjestelyihin. Armeijakunnan ilmatorjuntajoukkoja johti ilmatorjuntarykmentin komentaja, IV AK:lle alistettua It.R 12:a everstiluutnantti Pietarinen. Tässä rykmentissä oli vallalla varsin komentajakeskeinen johtamiskulttuuri rykmentin komentajan antaessa tarkkoja toiminta-alueita alaisilleen patteristoille. Tämä muodostui osaltaan ongelmaksi koska patteristoilta puuttui näin ollen tietynlainen vapaus käyttää joukkojaan oma-aloitteisesti. Tulenkäytön johtamista ei jatkosodan aikana toteutettu paikallisia torjuntakeskuksia ja yötorjuntaa lukuunottamatta kenttäarmeijan joukoissa. Tähän oli syynä tarpeellisen kaluston puute, joukkojen käyttö sekä laajat vastuualueet. Ilmatorjuntaohjesäännöt määrittelivät tarkoin käytettävät tulimuodot mutta taisteluiden aikana näitä jouduttiin jatkuvasti soveltamaan. Tulikurin höltyminen vaikeutti huomattavasti pattereiden jo ennestään heikkoa ampumatarviketilannetta. 40 mm jaoksissa olisi ollut mahdollisuus tehokkaaseen jaoskohtaiseen ammuntaan mutta heikot 2T –yhteydet heikensivät tätä kykyä. Yhteistoiminta katsottiin ensiarvoisen tärkeäksi ilmatorjuntajoukoissa. Suurhyökkäyksen alussa yhteistoiminnassa maavoimien kanssa epäonnistuttiin ja tästä oli seurauksena suuret tappiot maavihollisen päästessä suoraan taisteluun ilmatorjuntajoukkojen kanssa. Yhteistoiminta ilmavoimien kanssa rajoittui lähinnä omakoneviestien ja ilmatorjunnan ryhmitystietojen välittämiseen. Yhteistoiminnan määrää voidaan pitää ihmeteltävän vähäisenä, vastasivathan molemmat osapuolet samasta tehtävästä – ilmatilan puolustamisesta. Ilmatorjuntajoukot tukeutuivat yleishuollollisesti pääsääntöisesti sen maavoimien yhtymän huoltolaitoksiin minkä alueella toimivat. Huollon toiminta onnistui hyvin, ainoana selkeänä haittatekijänä oli huoltohenkilöstön vähyys esikunnissa. Aselajin erikoishuollosta vastasi ilmatorjuntavarasto-osasto jonka kanssa toimittiin rykmentin kautta. Suurimpana huollollisena ongelmana oli amputarvikkeet, suurhyökkäyksen alussa osa joukoista ampui varastonsa lähes tyhjiksi ja jouduttiin säätelemään tulitoimintaa. Ilmatorjuntajoukkoja suunniteltiin käytettäväksi patterikokonaisuuksina mutta asemasota-vaiheessa toiminta-alueen laajuus pakotti käyttämään joukkoja jaoskohtaisesti. Näin ollen ei pystytty luomaan selkeitä painopistealueita vaan ilmatorjunta oli kaikkialla yhtä heikko. Suurhyökkäyksen edetessä joukkoja ryhdyttiin käyttämään kuitenkin enenevässä määrin patterikokonaisuuksina.