Optimizacija parametra zavarivanja čeličnih cijevi za plinovode

The aim of this paper is to define optimization of welding conditions for Submerged Arc Welding (SAW) of steel pipes for gas transportation. Fine grain steel X-52 with thickness of 8 mm were used as a base material. Welding was performed from inner and outer side. Two wires, inclined under different angles, were feed separately. Eleven samples divided in three series were experimentally welded. Performed investigations indicated that the best properties showed weldments from series III, welded with the highest heat input. On the contrary of our expectations, welds from series II, using self made equipment, showed pretty bead properties and improper geometry. So, improving of this this equipment and obtaining welds with better properties is the target in future investigations.Cilj ovog rada je definirati optimizaciju parametara zavarivanja pod praškom čeličnih cijevi za plinovode. Finozrnati čelik X-52 debljine 8 mm je korišten kao osnovni materijal. Zavarivanje je izvedeno s vanjske i unutarnje strane. Dvije žice, pod različitim kutom su dodavane odvojeno. Jedanaest uzoraka, podeljenih u tri serije ekserimentalno je zavareno. Ispitivanja su pokazala da najbolja svojstva imaju zavari iz serije III, zavareni s najvećom količinom unešene toplote. Suprotno očekivanjima, zavari iz serije II, kod kojih je korištena oprema koju su izradili autori rada, pokazali su vrlo loše karakteristike i neadekvatnu geometriju spoja. Stoga je osnovni cilj u sljedećim istrazivanjima poboljšanje ove opreme u cilju dobijanja kvalitetnijih zavara

Reduction of Chromium (VI) when Solar Selective Black Chromium is Deposited in the Presence of Organic Additive

Electrochemical dc methods were used to study the reduction of chromium (VI) in the presence of organic additives. It is shown that F–, thiourea, and citric acid are essential to enable deposition of black chrome from concentrated chromic acid solutions. A new formulation of the plating bath is defined. The optimum operating conditions under which spectrally selective surface of black chrome is deposited have been determined

Ontology of core data mining entities

In this article, we present OntoDM-core, an ontology of core data mining entities. OntoDM-core defines themost essential datamining entities in a three-layered ontological structure comprising of a specification, an implementation and an application layer. It provides a representational framework for the description of mining structured data, and in addition provides taxonomies of datasets, data mining tasks, generalizations, data mining algorithms and constraints, based on the type of data. OntoDM-core is designed to support a wide range of applications/use cases, such as semantic annotation of data mining algorithms, datasets and results; annotation of QSAR studies in the context of drug discovery investigations; and disambiguation of terms in text mining. The ontology has been thoroughly assessed following the practices in ontology engineering, is fully interoperable with many domain resources and is easy to extend

Quantum vacuum and dark matter

Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.Comment: Accepted for publication in Astrophysics and Space Scienc

The evolutionary signal in metagenome phyletic profiles predicts many gene functions

Background. The function of many genes is still not known even in model organisms. An increasing availability of microbiome DNA sequencing data provides an opportunity to infer gene function in a systematic manner. Results. We evaluated if the evolutionary signal contained in metagenome phyletic profiles (MPP) is predictive of a broad array of gene functions. The MPPs are an encoding of environmental DNA sequencing data that consists of relative abundances of gene families across metagenomes. We find that such MPPs can accurately predict 826 Gene Ontology functional categories, while drawing on human gut microbiomes, ocean metagenomes, and DNA sequences from various other engineered and natural environments. Overall, in this task, the MPPs are highly accurate, and moreover they provide coverage for a set of Gene Ontology terms largely complementary to standard phylogenetic profiles, derived from fully sequenced genomes. We also find that metagenomes approximated from taxon relative abundance obtained via 16S rRNA gene sequencing may provide surprisingly useful predictive models. Crucially, the MPPs derived from different types of environments can infer distinct, non-overlapping sets of gene functions and therefore complement each other. Consistently, simulations on > 5000 metagenomes indicate that the amount of data is not in itself critical for maximizing predictive accuracy, while the diversity of sampled environments appears to be the critical factor for obtaining robust models. Conclusions. In past work, metagenomics has provided invaluable insight into ecology of various habitats, into diversity of microbial life and also into human health and disease mechanisms. We propose that environmental DNA sequencing additionally constitutes a useful tool to predict biological roles of genes, yielding inferences out of reach for existing comparative genomics approaches

Carbon nanotubes as support for Co/TiO2 electrocatalysts for hydrogen evolution

The aim of this work was to apply multiwalled carbon nanotubes (MWCNTs) as a catalyst support in composite Co/TiO2/C electrocatalysts for hydrogen evolution. In order to elucidate the effect of MWCNTs, corresponding catalysts deposited on traditional carbon material Vulcan XC-72 were prepared as well

Reduction of Chromium (VI) when Solar Selective Black Chromium is Deposited in the Presence of Organic Additive

Venezuela: Jungle bound Orinoco RiverColorVolume 98, Page 1