Aktivno lužnati kompoziti dobiveni od troske željezne i čelične industrije

Slag as a secondary raw material from metallurgy is most often heaped in slag disposal areas without any profit. This paper deals with alkali activated slag from iron and steel production which can be used in the building industry. Products of alkali slag activation fulfill the role of inorganic binders.Kao sekundarna sirovina, troska od metalurškog procesa najčešće se odlaže na deponije bez ikakve financijske dobiti. Ovaj rad se bavi lužnato aktiviranom troskom iz proizvodnje željeza i čelika, koja kao anorgansko vezivo može biti korištena u građevinskoj industriji

Reduced and Superreduced Diplatinum Complexes

A d^8–d^8 complex [Pt_2(μ-P_2O_5(BF_2)_4]^(4–) (abbreviated Pt(pop-BF_2)^(4–)) undergoes two 1e– reductions at E_(1/2) = −1.68 and E_p = −2.46 V (vs Fc+/Fc) producing reduced Pt(pop-BF_2)^(5–) and superreduced Pt(pop-BF_2)^(6–) species, respectively. The EPR spectrum of Pt(pop-BF_2)^(5–) and UV–vis spectra of both the reduced and the superreduced complexes, together with TD-DFT calculations, reveal successive filling of the 6pσ orbital accompanied by gradual strengthening of Pt–Pt bonding interactions and, because of 6pσ delocalization, of Pt–P bonds in the course of the two reductions. Mayer–Millikan Pt–Pt bond orders of 0.173, 0.268, and 0.340 were calculated for the parent, reduced, and superreduced complexes, respectively. The second (5–/6−) reduction is accompanied by a structural distortion that is experimentally manifested by electrochemical irreversibility. Both reduction steps proceed without changing either d^8 Pt electronic configuration, making the superreduced Pt(pop-BF_2)^(6–) a very rare 6p^2 σ-bonded binuclear complex. However, the Pt–Pt σ bonding interaction is limited by the relatively long bridging-ligand-imposed Pt–Pt distance accompanied by repulsive electronic congestion. Pt(pop-BF_2)^(4–) is predicted to be a very strong photooxidant (potentials of +1.57 and +0.86 V are estimated for the singlet and triplet dσ*pσ excited states, respectively)

Photophysical and Photochemical Studies of Tricarbonyl Rhenium(I) N-Heterocyclic Carbene Complexes Containing Azide and Triazolate Ligands

Rhenium(I) N-heterocyclic carbene (NHC) complexes of the type fac-[Re(CO)3(NHC)L] with either azide or triazolate ancillary ligands L and pyridyl or pyrimidyl substituted imidazolyl units have been prepared and structurally characterised, and their photophysical and photochemical properties studied. All of the complexes exhibit phosphorescent emission from triplet metal-to-ligand (3MCLT) excited states, typical of tricarbonyl Re(I) complexes, with the triazolate bound complexes having higher quantum yields and longer decay lifetimes compared to the azide bound complexes. The complexes containing pyridyl substituted imidazolyl units are photoreactive when dissolved in acetonitrile and undergo photochemical CO dissociation, the rate of which is significantly greater in the azide cf. triazolate complex. The photochemical mechanism of the azide/pyridyl complex was analysed and appears to give the same products, albeit with different ratios, to previously reported complexes where L is a halide. A reaction mechanism is proposed

Electronic Excited States of Tungsten(0) Arylisocyanides

W(CNAryl)_6 complexes containing 2,6-diisopropylphenyl isocyanide (CNdipp) are powerful photoreductants with strongly emissive long-lived excited states. These properties are enhanced upon appending another aryl ring, e.g., W(CNdippPh^(OMe)_2)_6; CNdippPh^(OMe)_2 = 4-(3,5-dimethoxyphenyl)-2,6-diisopropylphenylisocyanide (Sattler et al. J. Am. Chem. Soc. 2015, 137, 1198−1205). Electronic transitions and low-lying excited states of these complexes were investigated by time-dependent density functional theory (TDDFT); the lowest triplet state was characterized by time-resolved infrared spectroscopy (TRIR) supported by density functional theory (DFT). The intense absorption band of W(CNdipp)_6 at 460 nm and that of W(CNdippPh^(OMe)_2)_6 at 500 nm originate from transitions of mixed ππ*(C≡N–C)/MLCT(W → Aryl) character, whereby W is depopulated by ca. 0.4 e– and the electron-density changes are predominantly localized along two equatorial molecular axes. The red shift and intensity rise on going from W(CNdipp)_6 to W(CNdippPh^(OMe)_2)_6 are attributable to more extensive delocalization of the MLCT component. The complexes also exhibit absorptions in the 300–320 nm region, owing to W → C≡N MLCT transitions. Electronic absorptions in the spectrum of W(CNXy)_6 (Xy = 2,6-dimethylphenyl), a complex with orthogonal aryl orientation, have similar characteristics, although shifted to higher energies. The relaxed lowest W(CNAryl)_6 triplet state combines ππ* excitation of a trans pair of C≡N–C moieties with MLCT (0.21 e–) and ligand-to-ligand charge transfer (LLCT, 0.24–0.27 e–) from the other four CNAryl ligands to the axial aryl and, less, to C≡N groups; the spin density is localized along a single Aryl–N≡C–W–C≡N–Aryl axis. Delocalization of excited electron density on outer aryl rings in W(CNdippPh^(OMe)_2)_6 likely promotes photoinduced electron-transfer reactions to acceptor molecules. TRIR spectra show an intense broad bleach due to ν(C≡N), a prominent transient upshifted by 60–65 cm^(–1), and a weak down-shifted feature due to antisymmetric C≡N stretch along the axis of high spin density. The TRIR spectral pattern remains unchanged on the femtosecond-nanosecond time scale, indicating that intersystem crossing and electron-density localization are ultrafast (<100 fs)

DNA Damage during G2 Phase Does Not Affect Cell Cycle Progression of the Green Alga Scenedesmus quadricauda

DNA damage is a threat to genomic integrity in all living organisms. Plants and green algae are particularly susceptible to DNA damage especially that caused by UV light, due to their light dependency for photosynthesis. For survival of a plant, and other eukaryotic cells, it is essential for an organism to continuously check the integrity of its genetic material and, when damaged, to repair it immediately. Cells therefore utilize a DNA damage response pathway that is responsible for sensing, reacting to and repairing damaged DNA. We have studied the effect of 5-fluorodeoxyuridine, zeocin, caffeine and combinations of these on the cell cycle of the green alga Scenedesmus quadricauda. The cells delayed S phase and underwent a permanent G2 phase block if DNA metabolism was affected prior to S phase; the G2 phase block imposed by zeocin was partially abolished by caffeine. No cell cycle block was observed if the treatment with zeocin occurred in G2 phase and the cells divided normally. CDKA and CDKB kinases regulate mitosis in S. quadricauda; their kinase activities were inhibited by Wee1. CDKA, CDKB protein levels were stabilized in the presence of zeocin. In contrast, the protein level of Wee1 was unaffected by DNA perturbing treatments. Wee1 therefore does not appear to be involved in the DNA damage response in S. quadricauda. Our results imply a specific reaction to DNA damage in S. quadricauda, with no cell cycle arrest, after experiencing DNA damage during G2 phase

The Plastid Genome of Eutreptiella Provides a Window into the Process of Secondary Endosymbiosis of Plastid in Euglenids

Euglenids are a group of protists that comprises species with diverse feeding modes. One distinct and diversified clade of euglenids is photoautotrophic, and its members bear green secondary plastids. In this paper we present the plastid genome of the euglenid Eutreptiella, which we assembled from 454 sequencing of Eutreptiella gDNA. Comparison of this genome and the only other available plastid genomes of photosynthetic euglenid, Euglena gracilis, revealed that they contain a virtually identical set of 57 protein coding genes, 24 genes fewer than the genome of Pyramimonas parkeae, the closest extant algal relative of the euglenid plastid. Searching within the transcriptomes of Euglena and Eutreptiella showed that 6 of the missing genes were transferred to the nucleus of the euglenid host while 18 have been probably lost completely. Euglena and Eutreptiella represent the deepest bifurcation in the photosynthetic clade, and therefore all these gene transfers and losses must have happened before the last common ancestor of all known photosynthetic euglenids. After the split of Euglena and Eutreptiella only one additional gene loss took place. The conservation of gene content in the two lineages of euglenids is in contrast to the variability of gene order and intron counts, which diversified dramatically. Our results show that the early secondary plastid of euglenids was much more susceptible to gene losses and endosymbiotic gene transfers than the established plastid, which is surprisingly resistant to changes in gene content

Evolutionary genetics of immunological supertypes reveals two faces of the Red Queen

Red Queen host-parasite co-evolution can drive adaptations of immune-genes by positive selection that erodes genetic variation (Red Queen Arms Race), or result in a balanced polymorphism (Red Queen Dynamics) and the long-term preservation of genetic variation (trans-species polymorphism). These two Red Queen processes are opposite extremes of the co-evolutionary spectrum. Here we show that both Red Queen processes can operate simultaneously, analyzing the Major Histocompatibility Complex (MHC) in guppies (Poecilia reticulata and P. obscura), and swamp guppies (Micropoecilia picta). Sub-functionalization of MHC alleles into “supertypes” explains how polymorphisms persist during rapid host-parasite co-evolution. Simulations show the maintenance of supertypes as balanced polymorphisms, consistent with Red Queen Dynamics, whereas alleles within supertypes are subject to positive selection in a Red Queen Arms Race. Building on the Divergent Allele Advantage hypothesis, we show that functional aspects of allelic diversity help to elucidate the evolution of polymorphic genes involved in Red Queen co-evolution