Effect of cement grade and fineness of slag on the early age to medium term properties of binary blends

The hydration and microstructural evolution of cementitious materials are dependent on both the mineralogical and physical attributes of the constituent materials. This paper ascertains the influence of constituent materials’ fineness on hydration and the evolution of mechanical properties of CEM I-slag composite cements. The clinker to supplementary cementitious material ratio was maintained at 50:50 and the sulphate content kept constant in all mixes. Compressive strength development was followed over time, with hydration followed by isothermal calorimetry and chemical shrinkage. Results from these techniques show that, for a given clinker, a more finely ground slag was consistently superior to a coarser slag. Furthermore, calorimetry revealed that the intensity of alite hydration and the secondary peak attributable to participation of aluminates from slag in hydration were also greater when using a finer slag. Finely ground clinker also accelerates slag hydration. The early age strengths in the binary blends were weaker than the control specimens, but this was offset beyond 7 days when using finer slag blends. Blending of higher grade CEM I (52.5R) and fine slag also yielded comparable early age strength to a CEM I- 42.5R mix

Solitons and Black Holes in a Generalized Skyrme Model with Dilaton-Quarkonium field

Skyrme theory is among the viable effective theories which emerge from low-energy limit of quantum chromodynamics. Many of its generalizations include also a dilaton. Here we find new self-gravitating solutions, both solitons and black holes, in a Generalized Skyrme Model (GSM) in which a dilaton is present. The investigation of the properties of the solutions is done numerically. We find that the introduction of the dilaton in the theory does not change the picture qualitatively, only quantitatively. The model considered here has one free parameter more than the Einstein-Skyrme model which comes from the potential of the dilaton. We have applied also the turning point method to establish that one of the black-hole branches of solutions is unstable. The turning point method here is based on the first law of black-hole thermodynamics a detailed derivation of which is given in the Appendix of the paper.Comment: 19 pages, 10 figures; v2: typos corrected, comments adde

Benchmark calculations for elastic fermion-dimer scattering

We present continuum and lattice calculations for elastic scattering between a fermion and a bound dimer in the shallow binding limit. For the continuum calculation we use the Skorniakov-Ter-Martirosian (STM) integral equation to determine the scattering length and effective range parameter to high precision. For the lattice calculation we use the finite-volume method of L\"uscher. We take into account topological finite-volume corrections to the dimer binding energy which depend on the momentum of the dimer. After subtracting these effects, we find from the lattice calculation kappa a_fd = 1.174(9) and kappa r_fd = -0.029(13). These results agree well with the continuum values kappa a_fd = 1.17907(1) and kappa r_fd = -0.0383(3) obtained from the STM equation. We discuss applications to cold atomic Fermi gases, deuteron-neutron scattering in the spin-quartet channel, and lattice calculations of scattering for nuclei and hadronic molecules at finite volume.Comment: 16 pages, 5 figure

A Coherent Spin-Photon Interface in Silicon

Electron spins in silicon quantum dots are attractive systems for quantum computing due to their long coherence times and the promise of rapid scaling using semiconductor fabrication techniques. While nearest neighbor exchange coupling of two spins has been demonstrated, the interaction of spins via microwave frequency photons could enable long distance spin-spin coupling and "all-to-all" qubit connectivity. Here we demonstrate strong-coupling between a single spin in silicon and a microwave frequency photon with spin-photon coupling rates g_s/(2\pi) > 10 MHz. The mechanism enabling coherent spin-photon interactions is based on spin-charge hybridization in the presence of a magnetic field gradient. In addition to spin-photon coupling, we demonstrate coherent control of a single spin in the device and quantum non-demolition spin state readout using cavity photons. These results open a direct path toward entangling single spins using microwave frequency photons

The effect of cutting temperature on hole quality when drilling CFRP/metal stack

The carbon fiber reinforced plastic (CFRP) are widely used in stacks with metals. That allows obtaining components with high strength and reduces weight. Holes’ drilling is a basic operation of CFRP/metal and metal/CFRP stacks machining. The most common problems of CFRP/metal stacks drilling are CFRP delamination, fiber pull – out, thermal degradation and low quality of hole surface. In this study the effect of cut ting temperature on the hole quality was provided. It was experimentally established that drilling of CFRP/metal stack was accompanied with a significant change of cutting temperature in the cutting zone during the transition of drill from CFRP to metal plate.Волокнисті полімерні композиційні матеріали (вуглепластики) широко використовуються в пакетах з металами. Це дозволяє отримати компоненти з високою міцністю, разом з тим забезпечивши зниження ваги. Свердління отворів є основною механічною операцією при обробці пакетів вуглепластик / метал і метал / вуглепластика. Найбільш поширені проблеми механічної обробки пакетів вуглепластик / метал є розшарування вуглепластика, витягування волокон, термічна деструкція і низька якість поверхні отвори. У статті представлено дослідження впливу дію температури різання на якість отворів. Експериментально було встановлено, що свердління пакета вуглепластик / сталь супроводжувався істотною зміною температури різання в зоні різання при переході свердла з вуглепластика до металевої пластини

Effect of cyclic freezing and thawing on the microstructure of composite cements

Mixed performance of composite cements exposed to freeze-thaw has been reported. A detailed understanding of the degradation mechanism is also lacking. This study investigates the microstructure of composite slag cements with and without limestone subjected to cyclic freezing and thawing. Freeze-thaw was assessed on concrete samples in accordance with CEN/TR 15177 but with a modified temperature profile. Microstructure was characterized by SEM and thermogravimetric analysis. The results indicate decalcification through carbonation and then leaching as dominant degradation mechanisms. This has implications on the pore structure and hence the water suction capacity and progression of the ice-front in concrete

Time Evolution of the Radial Perturbations and Linear Stability of Solitons and Black Holes in a Generalized Skyrme Model

We study the time evolution of the radial perturbation for self-gravitating soliton and black-hole solutions in a generalized Skyrme model in which a dilaton is present. The background solutions were obtained recently by some of the authors. For both the solitons and the black holes two branches of solutions exist which merge at some critical value of the corresponding parameter. The results show that, similar to the case without a scalar field, one of the branches is stable against radial perturbations and the other is unstable. The conclusions for the linear stability of the black holes in the generalized Skyrme model are also in agreement with the results from the thermodynamical stability analysis based on the turning point method.Comment: 18 pages, 12 figures; v2: typos corrected, comments adde

Collective Quadrupole Excitations in Transitional Nuclei

The generalized Bohr Hamiltonian was used to describe the low-lying collective excitations in even-even isotopes of Ru, Pd, Te, Ba and Nd. The Strutinsky collective potential and cranking inertial functions were obtained using the Nilsson potential. The effect of coupling with the pairing vibrations is taken into account approximately when determining the inertial functions. The calculation does not contain any free parameter

Parasite infections in a social carnivore: Evidence of their fitness consequences and factors modulating infection load

There are substantial individual differences in parasite composition and infection load in wildlife populations. Few studies have investigated the factors shaping this heterogeneity in large wild mammals or the impact of parasite infections on Darwinian fitness, particularly in juveniles. A host's parasite composition and infection load can be shaped by factors that determine contact with infective parasite stages and those that determine the host's resistance to infection, such as abiotic and social environmental factors, and age. Host–parasite interactions and synergies between coinfecting parasites may also be important. We test predictions derived from these different processes to investigate factors shaping infection loads (fecal egg/oocyte load) of two energetically costly gastrointestinal parasites: the hookworm Ancylostoma and the intracellular Cystoisospora, in juvenile spotted hyenas (Crocuta crocuta) in the Serengeti National Park, in Tanzania. We also assess whether parasite infections curtail survival to adulthood and longevity. Ancylostoma and Cystoisospora infection loads declined as the number of adult clan members increased, a result consistent with an encounter‐reduction effect whereby adults reduced encounters between juveniles and infective larvae, but were not affected by the number of juveniles in a clan. Infection loads decreased with age, possibly because active immune responses to infection improved with age. Differences in parasite load between clans possibly indicate variation in abiotic environmental factors between clan den sites. The survival of juveniles (<365 days old) to adulthood decreased with Ancylostoma load, increased with age, and was modulated by maternal social status. High‐ranking individuals with low Ancylostoma loads had a higher survivorship during the first 4 years of life than high‐ranking individuals with high Ancylostoma loads. These findings suggest that high infection loads with energetically costly parasites such as hookworms during early life can have negative fitness consequences