Proven Potential Research Articles

Comparison of one-dimensional and comprehensive two-dimensional separations by gas chromatography

Comprehensive two-dimensional gas chromatography (GC×GC) can reveal information on the composition of a sample in a way that cannot be done by one-dimensional GC (1D-GC). GC×GC also offers much greater control of chromatographic selectivity based on molecular structure. However, in spite of more than 15 years of claims of the ability of GC×GC to resolve an overwhelmingly larger number of peaks than 1D-GC, and in spite of the theoretically proven potential of GC×GC to have an order of magnitude larger peak capacity than 1D-GC, the peak capacity of currently practiced GC×GC does not generally exceed the peak capacity attainable from 1D-GC with the same analysis time and the same minimal detectable concentration (MDC). The methodology for comparing the peak capacity of GC×GC to 1D-GC is described. The comparison of the performance of GC×GC to 1D-GC shows that the modulator is the key bottleneck limiting the performance of existing GC×GC. To realize the full potential of GC×GC, duration of injection from a modulator into the second-dimension column should be reduced by an order of magnitude or more. Use of powerful data analysis techniques such as peak deconvolution in both dimensions can further increase resolving power of GC×GC.

Gamburtsev Subglacial Mountains provenance of Permian–Triassic sandstones in the Prince Charles Mountains and offshore Prydz Bay: Integrated U–Pb and T DM ages and host-rock affinity from detrital zircons

Permian–Triassic drainage radiates from the Gamburtsev Subglacial Mountains (GSM) in central Antarctica. Proximal to the GSM are Permian–Triassic fluvial sandstones in the Prince Charles Mountains (PCM), and neighbouring ?Triassic red beds in Prydz Bay (PB) ODP740A. We analysed detrital zircons for U–Pb ages, Hf-isotope compositions, and trace elements to determine the age, rock-type and source of the host magma, and “crustal” model age (T DM C). Populations of detrital zircons are (1) 700 to 500 Ma, host magmas granitoid and alkaline rock, T DM C ranges from 2.5 to 1.1 Ga, and (2) 1200–800 Ma, host magmas mafic granitoid and alkaline rock, T DM C 2.1 to 1.5 Ga. The bedrock of the PCM-PB region is a potential provenance of the detrital zircons, but the same populations in Permian siltstone south of the PCM and in sediment inclusions in ice at Lake Vostok indicate that the GSM–Vostok Subglacial Highlands (VSH) are the main provenance. Similar detrital zircons in other sandstones in Gondwanaland downslope from a wider central Antarctic reflect an upslope provenance including the GSM–VSH as a complex of 1200–800 Ma (Grenville) and older cratons with mafic granitoids embedded in 700–500 Ma fold belts with granitoids and alkaline rocks. During the past 1000 Ma, the GSM has undergone intermittent uplift on a scale resembling that of the present uplands of Central Asia.

Modelling of a novel x-ray phase contrast imaging technique based on coded apertures

X-ray phase contrast imaging is probably the most relevant among emerging x-ray imaging techniques, and it has the proven potential of revolutionizing the field of diagnostic radiology. Impressive images of a wide range of samples have been obtained, mostly at synchrotron radiation facilities. The necessity of relying on synchrotron radiation has prevented to a large extent a widespread diffusion of phase contrast imaging, thus precluding its transfer to clinical practice. A new technique, based on the use of coded apertures, was recently developed at UCL. This technique was demonstrated to provide intense phase contrast signals with conventional x-ray sources and detectors. Unlike other attempts at making phase contrast imaging feasible with conventional sources, the coded-aperture approach does not impose substantial limitations and/or filtering of the radiation beam, and it therefore allows, for the first time, exposures compatible with clinical practice. The technique has been thoroughly modelled, and this paper describes the technique in detail by going through the different steps of the modelling. All the main factors influencing image quality are discussed, alongside the viability of realizing a prototype suitable for clinical use. The model has been experimentally validated and a section of the paper shows the comparison between simulated and experimental results.For more information on this article, see medicalphysicsweb.org

FlexE ensemble docking approach to virtual screening for CDK2 inhibitors

In spite of a proven potential and effectiveness of FlexE in docking flexible ligands into an ensemble of protein structures, FlexE has rarely been successful in virtual screening situations. In this study, we constructed cyclin-dependent kinase 2 (CDK2) ensemble structures which have exactly the same backbone conformations as 1AQ1 but differ only at the side chain torsion angles of the key amino acid (Lys33, Phe80, Lys89 and Asp145) residues: the torsion angles observed in the 17 CDK2 crystal structures were adapted to represent conformational flexibility. FlexE ensemble docking protocol then completely samples the full conformational fields generated by combination of torsions of the four amino acids in the ATP binding site. Virtual screening for CDK2 inhibitors by using the FlexE ensemble docking of a database composed of 48,703 inactives and 82 actives showed significant enrichment factor (EF = 18.5), and successfully identified 71 actives among the top 132 ligands (53.8%) ranked by total energy scores. Moreover, total energy scoring followed by visual inspection filtered-off non-specific binders among the highly-ranked ligands to increase the ratio of actives-to-inactives to 71:13 at the top 5% of the virtual screening solutions.

Pan-Gondwanaland detrital zircons from Australia analysed for Hf-isotopes and trace elements reflect an ice-covered Antarctic provenance of 700–500 Ma age, TDM of 2.0–1.0 Ga, and alkaline affinity

Eastern Australian sediments of Cambrian, Ordovician, Silurian–Devonian, Triassic, and Neogene ages are known to be dominated by zircons dated 700–500 Ma (“Southwest Pacific–Gondwana igneous component”) by the U–Pb SHRIMP method, and thought to be derived from Antarctica, as suggested also by paleogeographical evidence. To extend the characteristics of the provenance we subjected SHRIMPed zircons from the Middle Triassic Hawkesbury Sandstone and four Neogene beach sands to LAM–ICPMS analysis for rock type and Hf-isotope T DM model ages. These data confirm the demonstration (from ages alone) that the beach sands were recycled from the Hawkesbury Sandstone. All five samples have a substantial fraction of 700–500 Ma zircons derived from alkaline rocks with T DM of 2.0–1.0 Ga. We analysed zircons from the nearest exposed alkaline rock of appropriate age in Antarctica: the 550–500 Ma Koettlitz Glacier Alkaline Province of the Ross orogen of the Transantarctic Mountains, emplaced during contemporary transtension. The rock types and T DM of the Koettlitz Glacier Alkaline Province zircons match those of the eastern Australian samples but only over the restricted range of 550–500 Ma. Rocks of 700–550 Ma age and alkaline type are unknown in Antarctic exposures. Rocks of this age and type, however, abound in the Pan-Gondwanaland orogens. The nearest of these is the Leeuwin Complex of the Pinjarra orogen of southwestern Australia, which connects through the Prydz–Leeuwin Belt with the Mozambique Orogenic Belt. In turn, the Leeuwin Complex is dominated by 700–500 Ma alkaline rocks generated by contemporary transtension. We find that zircons from a beach sand at Eneabba, 450 km north of the Leeuwin Complex, are dominated by alkaline types, so confirming demonstration by age alone that the sand came from the Leeuwin Complex. An important inference is that Pan-Gondwanaland terranes are potential provenances of sediment with zircons of ages 700–500 Ma, model ages 2.0–1.0 Ga, and alkaline affinity. We compiled the age spectra of our samples with others of the Southwest Pacific–Gondwana igneous component in southern Australia and reviewed their paleogeographical data. The Early Cambrian turbidites of the Kanmantoo Group were deposited from an axial northward paleocurrent that flowed across adjacent Antarctica in Wilkes Land. The Ordovician turbidite was deposited in fore-arc and abyssal fans likewise from a northward paleocurrent that flowed parallel to the uplifted Ross–Delamerian orogen. The Ordovician–Silurian–Devonian Mathinna Supergroup was deposited in a submarine fan system that prograded to the east-northeast from high ground in Antarctica. The Hawkesbury Sandstone was deposited in a braided-river system on a surface that sloped to the north-northeast from high ground in Antarctica. Together with the zircon data, the paleogeographical evidence in the Cambrian, Ordovician, Ordovician–Silurian–Devonian, and Triassic all point to a provenance in Wilkes Land, Antarctica of Pan-Gondwanaland (700–500 Ma) terranes with alkaline rocks.

Sickle Cell and Anesthesia: Do Not Abandon Well-established Practices without Evidence

Sickle Cell and Anesthesia: Do Not Abandon Well-established Practices without Evidence

Formation of Amorphous Alloys by Ion Beam Mixing and Its Multiscale Theoretical Modeling in the Equilibrium Immiscible Sc−W System

Unique amorphous alloys are synthesized at the compositions of 25 and 40 atom % of W by ion beam mixing in the equilibrium immiscible Sc-W system characterized by a positive heat of formation of +14 kJ/mol. In thermodynamic modeling, a Gibbs free energy diagram is constructed based on Miedema's theory, and the diagram predicts a glass-forming range of the Sc-W system to be within 12-58 atom % of W. To develop an atomistic model, ab initio calculations are first conducted to assist the construction of an n-body Sc-W potential under the embedded atom method. The proven realistic potential is applied in molecular dynamic simulations to study the crystal-to-amorphous transition in the Sc-W solid solutions, thus determining the glass-forming ability of the system to be within 15-50 atom % of W. Apparently, both theoretical predicted glass-forming ranges cover the experimentally measured one, showing an excellent agreement. We report, in this paper, the experimental results from ion beam mixing and the multiscale theoretical modeling concerning the amorphous alloy formation in the Sc-W system together with a brief discussion of the structural transition mechanism.

Metastable isomorphous phase diagram of the peritectic Ni-Ru system predicted byab initioand molecular dynamics calculations

With the aid of ab initio calculation, an $n$-body potential of the equilibrium peritectic Ni-Ru (fcc-hcp) system is derived under the second-moment approximation of the tight-binding formalism. The derived Ni-Ru potential is proven to be relevant not only in reproducing some static properties, such as the cohesive energies and elastic constants, etc., also in reproducing some dynamic properties, such as the melting points and thermal-expansion coefficients, etc. Applying the proven realistic Ni-Ru potential, molecular dynamics simulations show that a crystalline solid solution of either fcc or hcp structure would always win while competing with its amorphous counterpart over the entire composition range, predicting that under a nonequilibrium condition, the Ni-Ru system may feature an isomorphous phase diagram, i.e., predicting a hardly glass-forming ability of the Ni-Ru system, which, however, was previously defined as a possibly glass-forming system. Interestingly, the prediction is in good agreement with the fact that no amorphous Ni-Ru alloy has so far been obtained by any glass-producing technique as well as with that deduced from the thermodynamic calculations. Besides, the present calculations demonstrate the possibility for an equilibrium fcc-hcp system to have a metastable isomorphous phase diagram, implying that a part of the previously defined possibly glass-forming systems may convert into the hardly glass-forming ones.

Content Analysis of Prosocial and Antisocial Behavior in Japanese TV Programs

Despite the proven potential of educational robotics as a learning tool to promote disciplinary and transversal skills needed in 21st-century society, robots are still underused in schools. Teachers’ attitudes towards educational robotics play an important role in whether or not robotics is implemented in schools. This study analyses the attitudes of 174 teachers towards educational robotics, differentiating by region, gender, age, school level and disciplines taught. The results show that teachers are interested in educational robotics and that they perceive potential in the use of robots for the development of transversal skills. Some factors that limit the implementation of robotics are the costs, the time needed to prepare the activities and the fact that technologies are massively present in our everyday life and therefore some teachers do not want to bring them into school as well.

Glass-forming ability determined from inter-atomic potentials for some miscible/immiscible binary metal systems

The present study attempts to clarify one of the important issues in the field of metallic glasses (or amorphous alloys), i.e., to predict the glass-forming ability/range (GFA/GFR) of the binary metal systems. Firstly, a brief summary of the experimental observations indicates that in the miscible/immiscible systems, amorphous alloys can be formed in a broad composition range extending from central portion to nearby the edges of the two terminal solid solutions. Consequently, to predict RFA/GFR of a system becomes an issue of determining the critical solid solubility of the system, beyond which a solid solution would collapse into an energetically favored amorphous state. Secondly, the n-body potentials are derived by routine methods for the miscible Ni-Ta, Ni-Mo, and Ni-Ti systems, whereas for the immiscible Ag-Co and Cu-W systems having no any equilibrium alloy, the cross potentials are fitted to some physical properties acquired by first principles calculation for a few possible nonequilibrium alloys. Thirdly, applying the proven realistic potentials, molecular dynamics simulations with solid solution models reveal that the physical origin of crystal-to-amorphous transition is the lattice collapsing while solute atoms exceeding the critical solid solubility and that the GFRs of the systems are within the composition ranges bounded by the two determined critical solid solubilities. It turns out that the predictions are in good agreement with the experimental observations.

Atomistic Modeling of Metastable Phase Selection of a Highly Immiscible Ag–W System

Ab initio calculation is performed for predicting the cohesive energies and lattice constants of some possible metastable compounds in the Ag-W system with the largest positive formation enthalpy among the binary transition metal alloys. The calculated results together with the experimental data are then used in deriving an n-body Ag-W potential under the framework of the embedded atom method. Based on the proven realistic Ag-W potential, molecular dynamics simulations are performed to reveal the metastable phase selection over the entire composition of the system and the results predict that the metastable Ag 100-x W x alloy in an fcc structure is more stable than in the bcc structure when 0 ≤ x < 57, whereas the bcc structure becomes energetically favored when 57 < x≤100. Interestingly, the prediction is in good agreement with the experimental results.

The early cricketing tours: Imperial provenance and radical potential

The early cricketing tours: Imperial provenance and radical potential

The Early Cricketing Tours: Imperial Provenance and Radical Potential

The Early Cricketing Tours: Imperial Provenance and Radical Potential

Structural Stability of the Metastable Solid Solution in the Equilibrium Immiscible Ag–Mo System Predicted by anab InitioDerived Potential

Based on the cohesive energies and lattice constants of a few possible non-equilibrium Ag–Mo compounds obtained by ab initio calculation, a Finnis–Sinclair (FS) potential of the equilibrium immiscible Ag–Mo system is derived. Applying the proven realistic potential, molecular dynamics simulation is carried out to study, at an atomic scale, the structural stability of the Ag-based solid solutions. The simulation results predict that the fcc crystalline structure can be preserved until the Mo concentration reaches 13 at.% and the correlation of the lattice constant of the Ag-based solid solutions vs the Mo concentration is in good agreement with Vegard’s Law. In addition, the heats of formation of the fcc Ag–Mo solid solutions calculated by the derived potential are quite agreeable with that calculated by Miedema’s theory.

Decoupling Transport from Economic Growth

This paper reports on a research project that aimed to identify and assess measures which could be used to reduce travel demand while maintaining economic growth and enhancing environmental quality. The research methodology involved a detailed review of past research; contact with over 600 experts from around Europe and elsewhere for ideas on potential measures; detailed questionnaires from over 100 of these experts; and a series of three panel sessions held in different parts of Europe, each of which involved around 16 experts debating the merits of different measures and identifying case study evidence of their effectiveness. The end result was a shortlist of 13 measures, indicative of broad types, which are considered to be effective, and an indication of their effectiveness if applied across the European Union. Seven illustrative measures are discussed which stand out from the results as having proven potential (though not necessarily at a European scale) to influence transport intensity and/or unit environmental load whilst not having large detrimental effects on GDP. These are the areas where it is felt that European transport policy could most usefully be focussed in terms of decoupling of transport demand and economic growth.

Rare earth elements as provenance indicators in North Australian estuarine and coastal marine sediments

Rare earth elements (REE) in three grain size fractions of clay-dominated estuarine and coastal sediments from the North Australian coastline have been investigated for use as potential provenance indicators. Comparisons of data based on instrumental neutron activation analysis and inductively coupled plasma mass spectrometry revealed that HF digestions of zircon-bearing samples resulted in unsatisfactory recovery of REE. Instead, a relatively simple, fast and safe partial digestion using HClO 4 + HNO 3 was used to extract REE mainly from clay minerals while excluding extraction of REE from zircons. A comparison with published data for primary rock units within river catchments showed that the main REE systematics has been preserved in downstream clay-rich sediments. Analysis of variance of La/Gd (PAAS), La/Yb (PAAS) and Eu/Eu* (PAAS) ratios in five areas showed that the <63 μm fraction possessed the greatest discriminating power. All five areas could be distinguished from each other at highly significant levels based on one or more of these ratios.

Femtosecond lasers as novel tool in dental surgery

There is a proven potential of femtosecond lasers for medical applications like cornea shaping [1], ear surgery or dental surgery [2]. Minimal invasive treatment of carious tissue has become an increasingly important aspect in modern dentistry. State of the art methods like grinding using turbine-driven drills or ablation by Er:YAG lasers [3] generate mechanical and thermal stress, thus generating micro cracks of several tens of microns in the enamel [4]. These cracks are starting points for new carious attacks and have to be avoided for long term success of the dental treatment. By using femtosecond lasers (1 fs=10 −15 s) for ablating dental tissue, these drawbacks can be overcome. We have demonstrated that femtosecond laser ablation offers a tool for crack-free generation of cavities in dental tissue. Furthermore, spectral analysis of the laser induced plasma has been used to indicate carious oral tissue. Our latest results on femtosecond laser dentistry will be presented, demonstrating the great potential of this kind of laser technology in medicine.

INFOPET.GIS Project: Representation And Geosite Data For Petroleum Exploration

Abstract The Cuban Archipelago is situated in the Caribbean Sea between Yucatan (Mexico), Florida (USA), Haiti and Jamaica, with a total area of 110,860 km2 and more than 1,600 keys or small islands. The offshore shelf area of the Cuban archipelago covers an area of 67,831 km2. Cuba can be divided into two hydrocarbon provinces: the North Province (continental margin carbonates deposited up to the pre-Campanian with synorogenic sediments), which contains most of the fields and discoveries today; and the South Cuban Province (part of the Caribbean Plate volcanic-arc islands, overlain by synorogenic and postorogenic sediments). The latter has been less explored up to the present, and is partially thrusted by the Placetas, Camajuani, and Remedios Tectostratigraphic Units (TSU). Hydrocarbons are trapped most commonly in thrusted, fractured carbonates of Jurassic to Cretaceous age, and also in fractured serpentinites and volcanic rocks. The most proven rock potential is found in the Placetas and Camajuani TSUs, where organically rich, low maturity carbonates show high hydrogen indices and good source potential. At present, more than 20 oil fields have been discovered, including the small old Motembo field (1881), and the largest Varadero (1971). The last discovery, named Puerto Escondido (1997) is still being developed by horizontal drilling. The conservation of this natural and important heritage, has established different approaches, called "geotopi" in Italian, "geologic points of interest" in the Spanish language, and "geosite" in English language. These are defined as singular elements of the environment that contain an extraordinary scientific knowledge(1). In our particular case, we denominate these elements as oil-geosites. The term is designed to include all locations and objectives that include any information or scientific knowledge about petroleum exploration and production. The idea for the compilation of the oil-geosites of Cuba first began to develop in 1985, and the project Oil&amp;Geosite was started in 1998, when the concept of an oil-geosite guide or atlas was developed by leading geologists and cartographers. The Geographical Information Systems (GIS) project "SISTEMA INFORMATICO PARA PETR?LEO (INFOPET.GIS)" was designed and created to solve complex problems in oil computer science. The main purpose of the INFOPET.GIS system is the collection, storage and analysis of oil and gas objectives, and other very important geologic events. The INFOPET.GIS's application is a computer-based tool and a procedure, built around a decision support system involving the integration of spatially referenced data. Project Objectives Management of the topographical information contained in the digital cartographic base. Management of the geologic information contained in the digital cartographic base. Management of the alphanumeric information of the different oil-geosite locations. Creation of the geographical databases with a relational platform for standard desktop mapping. The project is represented by the main screen, a data show, where we explain the history of the work evolution tables, cartographic materials, and slides, pictures, and other parameters concerning both volumes, including an explanatory text about the resources potential of Cuba.

Detrital zircon geochronology: enhancing the quality of sedimentary source information through improved methodology and combined U–Pb and fission‐track techniques

ABSTRACT Zircon is the most widely used mineral in detrital dating studies because it is common to multiple rock types, is chemically and physically resistant, and can endure successive cycles of burial, metamorphism and erosion. Zircon also has the advantage that single grains may be dated by either the fission‐track (FT) or U–Pb method, which, because of their contrasting thermal sensitivities (total resetting occurs at temperatures &gt; 320 °C for FT and &gt; 700–900 °C for U–Pb), can provide unique information about both the age structure and the thermal evolution of a sediment source. However, single method‐based bias and difficulties associated with interpreting measured ages can influence both the quality and the level of useful provenance information. For example, the zircon FT system is sensitive to metamorphic overprinting and hence measured ages alone cannot be interpreted as unambiguously dating formation age of the source rock. In contrast, U–Pb zircon data have high resistance (700–900 °C) to thermal overprinting and therefore recorded formation ages may not relate to an immediate source but may instead reflect a polycyclical history. The focus of this paper is to examine, from a practical standpoint, the provenance potential of detrital zircon fission track data and to investigate the method’s complementary role as an aide to the interpretation of high‐temperature detrital U–Pb zircon data by combining U–Pb and FT methods in a single study.

GOSSYM: A COTTON CROP SIMULATION MODEL AS A TOOL FOR THE FARMER

GOSSYM, a dynamic cotton (Gossypium hirsutum L.) crop simulation model is presented as a tool to increase efficiency of cotton management. The model simulates most of the physiological and physical processes affecting cotton growth, development and yield. It is also coupled with COMAX, an artificial intelligence expert system which assists in decision making for farm management. The model is used mainly for irrigation and nitrogen fertilization management and for plant growth regulators (PGR) application, based on daily weather data, soil physical and chemical characteristics of each site and some cultural characteristics. It has a proven potential for increasing profitability and is used in USA, where it was established and validated, in commercial farm management. Its uses as a tool for the cotton farm manager will be demonstrated in this paper.