Large heat capacity anomaly near the consolute point of the binary mixture nitromethane and 3-pentanol

The large critical anomaly in the isobaric heat capacity C(p,x)(T) of the binary mixture nitromethane + 3-pentanol is measured using high-resolution adiabatic scanning calorimetry. The unique features of this technique provided an alternative approach to the study of the critical behavior of C(p,x)(T), providing further C(p,x)(T) related quantities from which valuable information could be extracted. Our data are in full agreement with the predictions of the Modern Theory of Critical Phenomena; specifically, 3D-Ising model values for the critical exponent α and the universal amplitude ratio values of the leading critical amplitudes, as well as for the first correction-to-scaling ones, provide the optimum fits to represent the experimental data. Evidence for the need of higher-order terms, i.e., first correction-to-scaling term, is given. The large value of the coefficient E for the linear temperature dependence of the background obtained is ascribed to a possible contribution of the regular linear background term, of a higher-order asymmetry term, and of the second correction-to-scaling term. Internal consistency of C(p,x)(T) and its related quantities is successfully checked.     

Testing spectral filters as Gaussian quantum optical channels

We experimentally investigate the mode characteristics of multimode radiation fields propagating through frequency-dependent Gaussian channels. After manipulating the twin beams emitted from a conventional parametric downconversion source via spectral filtering, we study the changes in their mode characteristics, utilizing the joint normalized correlation functions. While filtering reduces the number of spectral modes, it also leads to an apparent mode mismatch, which destroys the perfect photon-number correlation between the twin beams, and influences the mode properties of heralded states.     

Modeling of deformation-induced phase transformation during very high cycle fatigue (VHCF) using the boundary element method

A microstructural simulation model is proposed which accounts for damage accumulation in shear bands and deformation-induced martensite formation in a metastable austenitic stainless steel (AISI304). The model is numerically solved using the two-dimensional (2-D) boundary element method. By using this method, sliding displacements can be directly evaluated in shear bands and austenite grains as well as generated martensite domains with their individual mechanical properties and shape deformation can be considered. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fatigue of the Near-Alpha Ti-Alloy Ti6242

Ti6242 is the workhorse of high-temperature Ti-alloys in the high pressure compressor of aero engines. In this study the influence on isothermal fatigue of different load controls, i.e. stress, total strain and plastic strain control at different temperatures and environments was investigated. The alloy had a bi-modal microstructure (some 30 vol.% primary alpha), which yields a good balance between fatigue and creep properties. In addition thermomechanical fatigue (TMF) tests were also performed. Modelling lifetime on the basis of a Basquin–Coffin–Manson relationship revealed only marginal scattering in the temperature range between 350°C and 650°C. Increasing the temperature led to a decrease in lifetime. This can be attributed to increased oxidation and creep. The latter one is clearly seen in isothermal tests under stress control. Tests in vacuum resulted in longer lifetimes. In-phase TMF tests exhibited a longer lifetime than out-of-phase tests, with a factor of about 4. Lifetime and stress response of in-phase tests are similar to the corresponding lifetime of an isothermal test at the maximum temperature. This similarity can be considered as a starting point for modelling TMF behaviour on the basis of isothermal fatigue.     

Effect of nonmesogenic impurities on the order of the nematic to smectic-A phase transition in liquid crystals

By means of adiabatic scanning calorimetry, we have studied the effect of the nonmesogenic solutes cyclohexane (CH) and biphenyl (BP) on the nematic-smectic-A phase transition in the liquid crystal octylcyanobiphenyl (8CB). For all concentrations of BP studied, the transition remains second-order. For 8CB+CH, however, crossover from second-order to first-order is observed at a tricritical point of the mole fraction x of CH around 0.0460. The difference between the two systems and the crossover is explained in terms of a mean-field free energy density expression including coupling terms of x with the nematic and smectic-A order parameters.     

Femtosecond properties of photorefractive polymers

Photorefractive polymers allow to reversibly record holograms over a broad spectral range. This capability offers the possibility to store the information contained in ultrafast optical pulses (i.e., time domain) in the frequency domain. We demonstrate a storage bandwidth of >80 nm around 800 nm (i.e., >36 THz), giving a temporal resolution for Gaussian pulses of 13 fs at room temperature. Time reversal of a pulse train of 130 fs pulses confirms these capabilities.     

Neutral-kaon mixing from (2+1)-flavor domain-wall QCD

We present the first results for neutral-kaon mixing using (2+1)-flavors of domain-wall fermions. A new approach is used to extrapolate to the physical up and down quark masses from our numerical studies with pion masses in the range 240-420 MeV; only SU(2)_{L}xSU(2)_{R} chiral symmetry is assumed and the kaon is not assumed to be light. Our main result is B_{K};{MS[over ]}(2 GeV)=0.524(10)(28) where the first error is statistical and the second incorporates estimates for all systematic errors.     

Net charge fluctuations in Au + Au interactions at sqrt[s(NN)]=130 GeV

Data from Au + Au interactions at sqrt[s(NN)]=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.     

Centrality dependence of pi(+/-), K(+/-), p,and (-)p production from sqrt[s(NN)] = 130 GeV Au + Au collisions at RHIC

Identified pi(+/-), K(+/-), p, and (-)p transverse momentum spectra at midrapidity in sqrt[s(NN)] = 130 GeV Au+Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. Within errors, all midrapidity particle yields per participant are found to be increasing with the number of participating nucleons. There is an indication that K(+/-), p, and (-)p yields per participant increase faster than the pi(+/-) yields. In central collisions at high transverse momenta (p(T) > or =2 GeV/c), (-)p and p yields are comparable to the pi(+/-) yields.