Mechanistic insight into biopolymer induced iron oxide mineralization through quantification of molecular bonding

Microbial production of iron (oxyhydr)oxides on polysaccharide rich biopolymers occurs on such a vast scale that it impacts the global iron cycle and has been responsible for major biogeochemical events. Yet the physiochemical controls these biopolymers exert on iron (oxyhydr)oxide formation are poorly understood. Here we used dynamic force spectroscopy to directly probe binding between complex, model and natural microbial polysaccharides and common iron (oxyhydr)oxides. Applying nucleation theory to our results demonstrates that if there is a strong attractive interaction between biopolymers and iron (oxyhydr)oxides, the biopolymers decrease the nucleation barriers, thus promoting mineral nucleation. These results are also supported by nucleation studies and density functional theory. Spectroscopic and thermogravimetric data provide insight into the subsequent growth dynamics and show that the degree and strength of water association with the polymers can explain the influence on iron (oxyhydr)oxide transformation rates. Combined, our results provide a mechanistic basis for understanding how polymer-mineral-water interactions alter iron (oxyhydr)oxides nucleation and growth dynamics and pave the way for an improved understanding of the consequences of polymer induced mineralization in natural systems

Ukupna taložna tvar na području Primorsko-goranske županije u razdoblju 1975.-2008.

Dustfall measurements in Primorsko-goranska county started in 1975 in the Bakar Bay (Site 2 - Bakar and Site 3 - Kraljevica). The measurements were extended to the city of Rijeka (Site 1 - Rijeka) in 1982, to the nearby islands (Site 4 - Krk and Site 5 - Cres) in 1986, and inland to Gorski Kotar (Site 6 - Delnice and Site 7 - Lividraga) in 1995. This article brings the results of dustfall measurements from 1975 to 2008. Dustfall was low in the city, the nearby islands, and Gorski Kotar. Recommended and limit values were occasionally exceeded in the Bakar Bay due to emissions from the coke plant and harbour at Site 2 (1979-1997) and from the shipyard at Site 3. Lead content in the dustfall was below the national limits, save for two occasions at Site 2. Deposition of sulphur and nitrogen at the inland sites were below the respective critical load values.Ispitivanja ukupne taložne tvari u Primorsko-goranskoj županiji započela su 1975. godine na području Bakarskog zaljeva. Mjerenja su se 1982. god proširila na grad Rijeku, 1986. na otoke Krk i Cres, a 1995. i na područje Gorskog kotara. U radu su prikazani rezultati mjerenja ukupne taložne tvari u razdoblju 1975.-2008. na sedam odabranih postaja: u gradu Rijeci, dvije na području Bakarskog zaljeva (Bakar i Kraljevica), dvije na otocima (Krk i Cres) te dvije u Gorskom kotaru (Delnice i Lividraga). Analizirano je kretanje prosječnih godišnjih vrijednosti ukupno istaloženih tvari te u njima prisutnih količina sagorivog pepela, sulfata, nitrata, amonija i olova. Na području grada Rijeke, otoka Krka i Cresa te Gorskog kotara količina ukupne taložne tvari je niska. Količine ukupne taložne tvari povremeno su prelazile preporučenu graničnu vrijednost u Bakru (1979.-1994.), zbog emisija iz koksare i iz luke za rasuti teret te u Kraljevici, gdje se osamdesetih godina osjećao utjecaj koksare u Bakru, a od sredine devedesetih pojačani rad u brodogradilištu. Količine olova u taložnoj tvari su niske na svim postajama, osim povremenih skokova u Bakru, kada su prijeđene preporučene vrijednosti. Količine istaloženog sumpora i dušika na području Gorskog kotara ispod su odgovarajućih vrijednosti kritičnog opterećenja za ispitivana područja

Upravljanje vjetroagregatom otporno na oštećenja kaveza asinkronog generatora

Wind turbines are usually installed on remote locations and in order to increase their economic competence malfunctions should be reduced and prevented. Faults of wind turbine generator electromechanical parts are common and very expensive. This paper proposes a fault-tolerant control strategy for variable-speed variable-pitch wind turbines in case of identified and characterised squirrel-cage generator rotor bar defect. An upgrade of the torque control loop with flux-angle-based torque modulation is proposed. In order to avoid or to postpone generator cage defects, usage of pitch controller in the low wind speed region is introduced. Presented fault-tolerant control strategy is developed taking into account its modular implementation and installation in available control systems of existing wind turbines to extend their life cycle and energy production. Practical implementation aspects such as estimation of variables used in control and estimate errors are considered and respected in operation, as well as fault-induced asymmetries. Simulation results for the case of a megawatt class wind turbine and the identified rotor bar fault are presented.Vjetroagregati se obično postavljaju na udaljene, nepristupačne lokacije te je potrebno spriječiti nastanak kvarova da bi se povećala njihova ekonomska konkurentnost. Kvarovi elektromehaničkih dijelova generatora vjetroagregata česti su i vrlo skupi. U ovom radu predstavljen je koncept upravljanja vjetroagregatima s promjenjivom brzinom vrtnje i zakretom lopatica za slučaj identificiranog i okarakteriziranog oštećenja kaveza asinkronog generatora. Predložena je nadogradnja na postojeći algoritam upravljanja momentom zasnovana na njegovoj modulaciji s obzirom na položaj magnetskog toka generatora. Da bi se izbjeglo ili usporilo širenje napuknuća kaveza generatora, predložena je primjena regulacijskog kruga za zakret lopatica i u režimu rada vjetroagregata ispod nazivne brzine vrtnje. Predstavljena strategija upravljanja razvijena je uvažavajući mogućnost modularnog nadovezivanja na postojeće metode upravljanja već postavljenih vjetroagregata s ciljem produženja njihova životnog vijeka i povećanja proizvodnje energije. Razmatrani su i uvaženi aspekti vezani uz praktičnu izvedbu, kao što je estimacija varijabli korištenih u upravljačkom algoritmu i pripadajuće pogreške estimata, kao i nesimetrije uzrokovane nastankom kvara. U radu su dani simulacijski rezultati za slučaj vjetroagregata iz megavatne klase s dijagnosticiranim napuknućem kaveza rotora

Transfer Reaction Studies with Spectrometers

The revival of transfer reaction studies benefited from the construction of the new generation large solid angle spectrometers, coupled to large gamma arrays. The recent results of gamma-particle coincident measurements in Ca-40+Zr-96 and Ar-40+Pb-208 reactions demonstrate a strong interplay between single-particle and collective degrees of freedom that is pertinent to the reaction dynamics. The development of collectivity has been followed in odd Ar isotopes populated in the Ar-40+Pb-208 reaction through the excitation of the 11/2(-) states, understood as the coupling of single particle degrees of freedom to nuclear vibration quanta. Pair transfer modes is another important degree of freedom which is presently being studied with Prisma in inverse kinematics at energies far below the Coulomb barrier. First results from the Zr-96+Ca-40 reaction elucidate the role played by nucleon-nucleon correlation

Mass correlation between light and heavy reaction products in multinucleon transfer 197Au+130Te collisions

We studied multinucleon transfer reactions in the 197Au+130Te system at Elab=1.07 GeV by employing the PRISMA magnetic spectrometer coupled to a coincident detector. For each light fragment we constructed, in coincidence, the distribution in mass of the heavy partner of the reaction. With a Monte Carlo method, starting from the binary character of the reaction, we simulated the de-excitation process of the produced heavy fragments to be able to understand their final mass distribution. The total cross sections for pure neutron transfer channels have also been extracted and compared with calculations performed with the grazing code

The association between Toll-like receptor 2 single-nucleotide polymorphisms and hepatocellular carcinoma susceptibility

<p>Abstract</p> <p>Background</p> <p>Toll-like receptors (TLR) are key innate immunity receptors participating in an immune response. Growing evidence suggests that mutations of TLR2/TLR9 gene are associated with the progress of cancers. The present study aimed to investigate the temporal relationship of single nucleotide polymorphisms (SNP) of TLR2/TLR9 and the risk of hepatocellular carcinoma (HCC).</p> <p>Methods</p> <p>In this single center-based case-control study, SNaPshot method was used to genotype sequence variants of TLR2 and TLR9 in 211 patients with HCC and 232 subjects as controls.</p> <p>Results</p> <p>Two synonymous SNPs in the exon of TLR2 were closely associated with risk of HCC. Compared with those carrying wild-type homozygous genotypes (T/T), risk of HCC decreased significantly in individuals carrying the heterozygous genotypes (C/T) of the rs3804099 (adjusted odds ratio (OR), 0.493, 95% CI 0.331 - 0.736, <it>P </it>< 0.01) and rs3804100 (adjusted OR, 0.509, 95% CI 0.342 - 0.759, <it>P </it>< 0.01). There was no significant association found in two TLR9 SNPs concerning the risk of HCC. The haplotype TT for TLR2 was associated significantly with the decreased risk of HCC (OR 0.524, 95% CI 0.394 - 0.697, <it>P </it>= 0.000). Inversely, the risk of HCC increased significantly in patients with the haplotype CC (OR 2.743, 95% CI 1.915 - 3.930, <it>P </it>= 0.000).</p> <p>Conclusions</p> <p>These results suggested that TLR2 rs3804099 C/T and rs3804100 C/T polymorphisms were closely associated with HCC. In addition, the haplotypes composed of these two TLR2 synonymous SNPs have stronger effects on the susceptibility of HCC.</p

Structure of 24Mg excited states and their influence on nucleosynthesis

The main idea of the two presented experiments is to study the decay of resonances in 24Mg at excitation energies above the 12C+12C decay thresh- old, in the astrophysical energy region of interest. The measurement of the 12C(16O,α)24Mg* reaction was performed at INFN-LNS in Catania. Only the α+20Ne decay channel of 24Mg is presented here, because it was a motivation for conducting a new experiment, a study of the 4He(20Ne,4He)20Ne reaction, performed at INFN-LNL in Legnaro. Some preliminary results of this measurement are also presented

13C+4He resonant elastic scattering on a thick gas target

Resonant elastic scattering of 13C on a thick 4He target has been measured. Reaction products from 13C(4He, 4He) were detected at several beam energies and gas pressures. Raw yield was efficiency corrected using Monte Carlo simulations and an averaged yield spectrum was produced. The observed peaks correspond well to the previously measured elastic scattering data

Analysis of states in ¹³C populated in ⁹Be + ⁴He resonant scattering

Measurements of 9Be+α resonant scattering have been performed using the thick-target approach with a 4He gas volume and a large area silicon strip detector. 9Be beam energies in the range 12 to 21.4 MeV were used to measure the 13C excitation energy spectrum between 13.2 and 16.2 MeV. An R-matrix analysis has been performed to characterize the spins and widths of 13C resonances, some of which have been proposed to be associated with a 3α+n molecular band