1,721,040 research outputs found
THE TRACES OF THE PAST: INFORMATIVE TOOLS FOR THE RECONSTRUCTION OF AURELIAN WALLS IN RIONE TESTACCIO
No full textRome has a great cultural heritage, formed by the stratification of styles and political influences from different eras. The different eras and architectural styles that have defined the city in the two millennia of history, make each part unique in its kind. This succession of changes has by necessity led to the denial of some archaeologies that in past ages were pivotal points in the development of the ancient city. The research presented here is intended to analyze and reconstruct the archeology of the river stretch of the Aurelian Walls on the Lungotevere Testaccio partly disappeared from the architectural landscape of the city. The research was set in two main phases, the first based on the two-dimensional study of the lost fabric, focusing on the cartographic study and the digitization of them in the GIS environment. The second one still under development foresees the digitalization of the threedimensional elements detected and the insertion of these within the dedicated platforms
Survey Experiences: The sistem of mills of Bagno Vignoni;The Etruscan urn of the Cacni Family; Rione Monti; The Loggia of the Rector Bulding.
No full textRilievo geometrico del sistema dei mulini ad acqua di Bagno Vignoni.
Geometric survey of the medieval water mills system of Bagno Vignoni, project integrated to the Detail ed Plan commissioned by the City of San Quirico d'Orcia. The survay and restoration were made with a loan granted by the European Commission under the "Raphael" Program, banned by the European Union and dedicated to the restoration and enhancement of European cultural heritage in the field of industrial archeology. General Manager: Francesco Riccardo Ghio. 2005.
Survay of the Loggia of the Rector Building, photogrammetric Survey and 3D modeling of one of the chiseled capitals of the portico that has a particular artistic merit.
Survey and photogrammetric survey of the Lodge of the Rector's Palace in Dubrovnik designed by Onofrio della Cava and photografic campaign aimed at creating a 3d mesh model through the use of software structure for motion of the engraved capitals by Pietro di Martino da Milano. Modeling, high resolution texturing and profiling of the capitals of the porch. Consultancy related to the Recovery Plan of the urban space promoted by the Municipality of Ragusa.
Topographic, architectural and urban survey of Rione Monti.
Topographic, architectural and urban survey of Rione Monti and 3D model for the reconstruction of the historical transformations of the district included between Via Panisperna, Via Cavour and Via dei Fori Imperiali. Cataloging and indexing of historical and iconographic data taken from the Gregorian Cadastre and related brogliardi (1818-24), and from the Geographic Web-GIS Information System of the Urbanism Laboratory of the Department of Architecture coordinated by Prof. Paolo Micalizzi. Since 2014, the research was focused on the virtual reconstruction of the Alessandrino District.
Photogrammetric survey and 3D modeling of the funerary urn depicting the myth of Oenomaus, found inside the tomb of the Etruscan family of Cacni in Perugia (III-I century BC).
The survey, aimed at the graphic documentation and implementation of a virtual model for the study and dissemination, has been performed with photographic processed with software modeling structure from motion. The urn, recovered in 2013 by the Cultural Heritage's Police Command along with other 21 and with the funeral set of the tomb of the Cacni family at Perugia, was exhibited at the Quirinale and then moved to Perugia, at the National Archaeological Museum of Umbria
Archeologia, storia e natura: il Borghetto Flaminio. Archeology,history and nature: Borghetto Flaminio
No full textArcheology,history and nature: Borghetto Flaminio
There are many places that offer beautiful and unique landscapes, of unequivocal historical importance and with a one of a kind artistic interest. All possess special characteristics that must be maintained for all future generations. However, these three components rarely coexist in one single place or they would consequently assume a unique value and would become very difficult to understand in view of the overlapping of the multiple systems involved. One of the sites with such characteristics is the subject of an articulated research and of this article: the Flaminio Village.
Introduction
Archeology of knowledge is made up of small inconspicuous truths that are detected with a strict method. Nietzche wrote that "we transformed knowledge into a passion that does not fear sacrifice and, in a final analysis, this knowledge is only afraid of extinguishing itself. The only real fear of those who acquire perfect knowledge is to see it all disappear."
The strategy chosen to document the transformations and permanence of the signs that characterize the area under study was long and complex.
A series of questions were raised several times during the research.
These questions vanished as soon as we assumed that the "history" had to be understood as a production of meanings based on the traces of events, such as the analytical and indefinite construction of history. This would become a tool used to break down well-established certainties and an "element" that must be preserved in its entirety and overcome at the same time.
Overcoming, the liberation of the tentacles of history, is the only way out of the "maze" where we can get lost at the end of a proper search, as stated by Tafuri.
That's the risk we face every time we are involved in a methodological research of the nature and history of a place
Inhibition of Urease by Hydroquinones: A Structural and Kinetic Study
Full text linkHydroquinones are a class of organic compounds abundant in nature that result from the full reduction of the corresponding quinones. Quinones are known to efficiently inhibit urease, a NiII-containing enzyme that catalyzes the hydrolysis of urea to yield ammonia and carbonate and acts as a virulence factor of several human pathogens, in addition to decreasing the efficiency of soil organic nitrogen fertilization. Here, we report the molecular characterization of the inhibition of urease from Sporosarcina pasteurii (SPU) and Canavalia ensiformis (jack bean, JBU) by 1,4-hydroquinone (HQ) and its methyl and tert-butyl derivatives. The 1.63-Å resolution X-ray crystal structure of the SPU-HQ complex discloses that HQ covalently binds to the thiol group of αCys322, a key residue located on a mobile protein flap directly involved in the catalytic mechanism. Inhibition kinetic data obtained for the three compounds on JBU reveals the occurrence of an irreversible inactivation process that involves a radical-based autocatalytic mechanism
Long-wavelength mesh & collect native SAD phasing from microcrystals
No full textHarnessing the anomalous signal from macromolecular crystals with volumes of less than 10 000 mm3 for native phasing requires careful experimental planning. The type of anomalous scatterers that are naturally present in the sample, such as sulfur, phosphorus and calcium, will dictate the beam energy required and determine the level of radiation sensitivity, while the crystal size will dictate the beam size and the sample-mounting technique, in turn indicating the specifications of a suitable beamline. On the EMBL beamline P13 at PETRA III, Mesh&Collect data collection from concanavalin A microcrystals with linear dimensions of 20 mm or less using an accordingly sized microbeam at a wavelength of 1.892 A ̊ (6.551 keV, close to the Mn edge at 6.549 keV) increases the expected Bijvoet ratio to 2.1% from an expected 0.7% at 12.6 keV (Se K edge), thus allowing experimental phase determination using the anomalous signal from naturally present Mn2+ and Ca2+ ions. Dozens of crystals were harvested and flash-cryocooled in micro-meshes, rapidly screened for diffraction (less than a minute per loop) and then used for serial Mesh&Collect collection of about 298 partial data sets (10 of crystal rotation per sample). The partial data sets were integrated and scaled. A genetic algorithm for combining partial data sets was used to select those to be merged into a single data set. This final data set showed high completeness, high multiplicity and sufficient anomalous signal to locate the anomalous scatterers, and provided phasing information which allowed complete auto-tracing of the polypeptide chain. To allow the complete experiment to run in less than 2 h, a practically acceptable time frame, the diffractometer and detector had to run together with limited manual intervention. The combination of several cutting-edge components allowed accurate anomalous signal to be measured from small crystals
Choosing your (Friedel) mates wisely: Grouping data sets to improve anomalous signal
No full textSingle-wavelength anomalous diffraction (SAD) phasing from multiple crystals can be especially challenging in samples with weak anomalous signals and/or strong non-isomorphism. Here, advantage is taken of the combinatorial diversity possible in such experiments to study the relationship between merging statistics and downstream metrics of phasing signals. It is furthermore shown that a genetic algorithm (GA) can be used to optimize the grouping of data sets to enhance weak anomalous signals based on these merging statistics
Insights into Urease Inhibition by N-(n-Butyl) Phosphoric Triamide through an Integrated Structural and Kinetic Approach
No full textThe nickel-dependent enzyme urease represents a negative element for the efficiency of soil nitrogen fertilization as well as a virulence factor for a large number of pathogenic and antibiotic-resistant bacteria. The development of ever more efficient urease inhibitors demands knowledge of their modes of action at the molecular level. N-(n-Butyl)-phosphoric triamide (NBPTO) is the oxo-derivative of N-(n-butyl)-thiophosphoric triamide (NBPT), which is extensively employed in agriculture to increase the efficiency of urea-based fertilizers. The 1.45 Å resolution structure of the enzyme-inhibitor complex obtained upon incubation of Sporosarcina pasteurii urease (SPU) with NBPTO shows the presence of diamido phosphoric acid (DAP), generated upon enzymatic hydrolysis of NBPTO with the release of n-butyl amine. DAP is bound in a tridentate binding mode to the two Ni(II) ions in the active site of urease via two O atoms and an amide NH 2 group, whereas the second amide group of DAP points away from the metal center into the active-site channel. The mobile flap modulating the size of the active-site cavity is found in a disordered closed-open conformation. A kinetic characterization of the NBPTO-based inhibition of both bacterial (SPU) and plant (Canavalia ensiformis or jack bean, JBU) ureases, carried out by calorimetric measurements, indicates the occurrence of a reversible slow-inhibition mode of action. The latter is characterized by a very small value of the equilibrium dissociation constant of the urease-DAP complex caused, in turn, by the large rate constant for the formation of the enzyme-inhibitor complex. The much greater capability of NBPTO to inhibit urease, as compared with that of NBPT, is thus not caused by the presence of a P?O moiety versus a P?S moiety, as previously suggested, but rather by the readiness of NBPTO to react with urease without the need to convert one of the P-NH 2 amide moieties to its P-OH acid derivative, as in the case of NBPT. The latter process is indeed characterized by a very small equilibrium constant that reduces drastically the concentration of the active form of the inhibitor in the case of NBPT. This indicates that high-efficiency phosphoramide-based urease inhibitors must have at least one O atom bound to the central P atom in order for the molecule to efficiently and rapidly bind to the dinickel center of the enzyme
The Impact of pH on Catalytically Critical Protein Conformational Changes: The Case of the Urease, a Nickel Enzyme
No full textUrease uses a cluster of two NiII ions to activate a water molecule for urea hydrolysis. The key to this unsurpassed enzyme is a change in the conformation of a flexible structural motif, the mobile flap, which must be able to move from an open to a closed conformation to stabilize the chelating interaction of urea with the NiII cluster. This conformational change brings the imidazole side chain functionality of a critical histidine residue, αHis323, in close proximity to the site that holds the transition state structure of the reaction, facilitating its evolution to the products. Herein, we describe the influence of the solution pH in modulating the conformation of the mobile flap. High-resolution crystal structures of urease inhibited in the presence of N-(n-butyl)phosphoric triamide (NBPTO) at pH 6.5 and pH 7.5 are described and compared to the analogous structure obtained at pH 7.0. The kinetics of urease in the absence and presence of NBPTO are investigated by a calorimetric assay in the pH 6.0–8.0 range. The results indicate that pH modulates the protonation state of αHis323, which was revealed to have pKa=6.6, and consequently the conformation of the mobile flap. Two additional residues (αAsp224 and αArg339) are shown to be key factors for the conformational change. The role of pH in modulating the catalysis of urea hydrolysis is clarified through the molecular and structural details of the interplay between protein conformation and solution acidity in the paradigmatic case of a metalloenzyme
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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