Determination of structural engineering properties of incoloy 903 and CTX-1 alloys

Tension, notched tension, compression, density, thermal conductivity, and thermal expansion tests were conducted on Incoloy 903 over the temperature range 20 K (-423 F) through 1033 K (1400 F). Fracture toughness tests were performed at room temperature (RT). Creep and rupture tests were conducted at 811 K (1000 F), 922 K (1200 F), and 1033 K (1400 F) for this alloy. Transverse unnotched and notched fatigue tests at R = 0.1 were performed at RT and 922 K (1200 F). For CTX-1 alloy, tension, Charpy V-notch impact, density, thermal conductivity, and thermal expansion tests were conducted over the temperature range 20 K (-423 F) through 1033 K (1400 F). Poisson's ratio was determined at RT, 811 K (1000 F), 922 K (1200 F), and 1033 K (1400 F). Notched tension and compression tests were performed at 20 K (-423 F), RT, and 922 K (1200 F); plane strain fracture toughness tests were conducted at RT, 77 K (-320 F), and 20 K (-423 F). Creep and rupture tests were performed at 811 K (1000 F), 922 K (1200 F), and 1033 K (1400 F); longitudinal unnotched and notched fatigue tests at R = 0.1 were conducted at RT and 922 K (1200 F). Results are presented and discussed

Polar Dynamics at the Jahn-Teller Transition in Ferroelectric GaV4S8

We present a dielectric spectroscopy study of the polar dynamics linked to the orbitally driven ferroelectric transition in the skyrmion host GaV4S8. By combining THz and MHz-GHz spectroscopy techniques, we succeed in detecting the relaxational dynamics arising from coupled orbital and polar fluctuations in this material and traced its temperature dependence in the paraelectric as well as in the ferroelectric phase. The relaxation time significantly increases when approaching the critical temperature from both sides of the transition. It is natural to assume that these polar fluctuations map the orbital dynamics at the Jahn-Teller transition. Due to the first-order character of the orbital-ordering transition, the relaxation time shows an enormous jump of about five orders of magnitude at the polar and structural phase transition.Comment: 5 pages, 4 figure

Lymphoproliferative malignancies in association with endemic African Kaposi’s Sarcoma

A CAJM study on Lymphoproliferative malignancies observed at a teaching hospital in South Africa among black Africans.The association of classical Kaposi’s sarcoma with lymphoproliferative disorders is well known. However, far less is known about lymphoproliferative malignancies in endemic African Kaposi’s sarcoma. A review of 47 patients with the endemic type of Kaposi’s sarcoma treated at the Johannesburg Teaching Hospital Complex between 1980 and 1992 revealed four patients (8,5 pc) in whom Kaposi’s sarcoma was associated with a malignant lymphoma. Possible pathogenetic mechanisms are suggested and the current literature is reviewed

IMPACT OF INFORMATION MANAGEMENT DURING DESIGN & CONSTRUCTION ON DOWNSTREAM BIM-GIS INTEROPERABILITY FOR RAIL INFRASTRUCTURE

The need for efficient and sustainable infrastructure – always critical to a city – is further gaining momentum as urbanisation creates the challenge of sustainably designing, constructing and operating the built environment. The AECOO industry, directly responsible for addressing this challenge, has adopted the use of BIM and GIS to aid in this endeavour. Both BIM and GIS overlap with respect to capturing aspects of the built environment, but are not interoperable by nature. To ensure a consistent and structured way of managing the information produced within these environments, industry standards such as IFC are implemented. Research to date focuses on addressing the integration between BIM and GIS for buildings by delving into the IFC and CityGML interoperability, which has highlighted significant geometric and semantic barriers that in the stage of integration, cannot be easily manoeuvred. The purpose of this paper is to provide an insight regarding the information lifecycle during Design & Construction in the HS2 Rail Infrastructure project and investigate the impact of current information management processes – and in particular Standards such as IFC, – on BIM-GIS interoperability and lifecycle management of an asset. Results demonstrate the levels of mis mapping during the export to IFC which varies depending on the infrastructure asset type. Discussion shows that these can be addressed by the introduction of additional semantic property sets to facilitate downstream BIM-GIS interoperability for O & M, enabling scope for future work

Definitive Evidence for Order-by-Quantum-Disorder in Er2Ti2O7

Here we establish the systematic existence of a U(1) degeneracy of all symmetry-allowed Hamiltonians quadratic in the spins on the pyrochlore lattice, at the mean-field level. By extracting the Hamiltonian of Er2Ti2O7 from inelastic neutron scattering measurements, we then show that the U(1)-degenerate states of Er2Ti2O7 are its classical ground states, and unambiguously show that quantum fluctuations break the degeneracy in a way which is confirmed by experiment. This is the first definitive observation of order-by-disorder in any material. We provide further verifiable consequences of this phenomenon, and several additional comparisons between theory and experiment.Comment: 4.5 pages, 3 figures, 7.5 pages of Supplemental Material, 8 supplemental figure

Structural, magnetic, electric, dielectric, and thermodynamic properties of multiferroic GeV4S8

The lacunar spinel GeV4S8 undergoes orbital and ferroelectric ordering at the Jahn-Teller transition around 30 K and exhibits antiferromagnetic order below about 14 K. In addition to this orbitally driven ferroelectricity, lacunar spinels are an interesting material class, as the vanadium ions form V4 clusters representing stable molecular entities with a common electron distribution and a well-defined level scheme of molecular states resulting in a unique spin state per V4 molecule. Here we report detailed x-ray, magnetic susceptibility, electrical resistivity, heat capacity, thermal expansion, and dielectric results to characterize the structural, electric, dielectric, magnetic, and thermodynamic properties of this interesting material, which also exhibits strong electronic correlations. From the magnetic susceptibility, we determine a negative Curie-Weiss temperature, indicative for antiferromagnetic exchange and a paramagnetic moment close to a spin S = 1 of the V4 molecular clusters. The low-temperature heat capacity provides experimental evidence for gapped magnon excitations. From the entropy release, we conclude about strong correlations between magnetic order and lattice distortions. In addition, the observed anomalies at the phase transitions also indicate strong coupling between structural and electronic degrees of freedom. Utilizing dielectric spectroscopy, we find the onset of significant dispersion effects at the polar Jahn-Teller transition. The dispersion becomes fully suppressed again with the onset of spin order. In addition, the temperature dependencies of dielectric constant and specific heat possibly indicate a sequential appearance of orbital and polar order.Comment: 15 pages, 9 figure

Polar and magnetic order in GaV4Se8

In the present work, we provide results from specific heat, magnetic susceptibility, dielectric constant, ac conductivity, and electrical polarization measurements performed on the lacunar spinel GaV4Se8. With decreasing temperature, we observe a transition from the paraelectric and paramagnetic cubic state into a polar, probably ferroelectric state at 42 K followed by magnetic ordering at 18 K. The polar transition is likely driven by the Jahn-Teller effect due to the degeneracy of the V4 cluster orbitals. The excess polarization arising in the magnetic phase indicates considerable magnetoelectric coupling. Overall, the behavior of GaV4Se8 in many respects is similar to that of the skyrmion host GaV4S8, exhibiting a complex interplay of orbital, spin, lattice, and polar degrees of freedom. However, its dielectric behavior at the polar transition markedly differs from that of the Jahn-Teller driven ferroelectric GeV4S8, which can be ascribed to the dissimilar electronic structure of the Ge compound.Comment: 7 pages, 6 figures. Revised version according to suggestions of referee