High-temperature superelasticity in CoNiGa,CoNiAl, NiFeGa,and TiNi monocrystals

The influence of the crystal orientation on the thermoelastic martensitic transformations developing under load was investigated for Co₄₉Ni₂₁Ga₃₀, Co₄₀Ni₃₃Al₂₇, Co₃₅Ni₃₅Al₃₀, Ni₅₄Fe₁₉Ga₂₇, and Ti_49.4Ni_50.6 (аt. %) monocrystals. It has been shown that the superelastic temperature range depends on the crystal orientation and reaches a maximum for [001]-oriented crystals. In monophase crystals of Co₄₉Ni₂₁Ga₃₀, Co₄₀Ni₃₃Al₂₇, Co₃₅Ni₃₅Al₃₀, and Ni₅₄Fe₁₉Ga₂₇ (at. %), segregation of dispersion particles takes place at test temperatures T > 623 K. A criterion for high-temperature superelasticity has been proposed which implies the attainment of high strength of the high-temperature phase due to a proper choice of the crystal orientation, deviation from stoichiometry, and segregation of dispersion particles. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10. pp. 19–37. October, 2008.     

A statistical fMRI model for differential T2* contrast incorporating T1 and T2* of gray matter

Relaxation parameter estimation and brain activation detection are two main areas of study in magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI). Relaxation parameters can be used to distinguish voxels containing different types of tissue whereas activation determines voxels that are associated with neuronal activity. In fMRI, the standard practice has been to discard the first scans to avoid magnetic saturation effects. However, these first images have important information on the MR relaxivities for the type of tissue contained in voxels, which could provide pathological tissue discrimination. It is also well-known that the voxels located in gray matter (GM) contain neurons that are to be active while the subject is performing a task. As such, GM MR relaxivities can be incorporated into a statistical model in order to better detect brain activation. Moreover, although the MR magnetization physically depends on tissue and imaging parameters in a nonlinear fashion, a linear model is what is conventionally used in fMRI activation studies. In this study, we develop a statistical fMRI model for Differential T₂^? ConTrast Incorporating T₁ and T₂^? of GM, so-called DeTeCT-ING Model, that considers the physical magnetization equation to model MR magnetization; uses complex-valued time courses to estimate T₁ and T₂^? for each voxel; then incorporates gray matter MR relaxivities into the statistical model in order to better detect brain activation, all from a single pulse sequence by utilizing the first scans.     

Assessment of strength properties of cemented paste backfill by ultrasonic pulse velocity test

Ultrasonic pulse velocity (UPV) test is one of the most popular non-destructive techniques used in the assessment of the mechanical properties of concrete or rock materials. In this study, the effects of binder type/dosage, water to cement ratio (w/c) and fines content (<20 μm) of the tailings on ultrasonic pulse velocity (UPV) of cemented paste backfill (CPB) samples were investigated and correlated with the corresponding unconfined compressive strength (UCS) data. A total of 96 CPB samples prepared at different mixture properties were subjected to the UPV and UCS tests at 7, 14, 28 and 56-days of curing periods. UPV and UCS of CPB samples of ordinary Portland cement (CEM I 42.5 R) and sulphate resistant cement (SRC 32.5) initially increased rapidly, but, slowed down after 14 days. However, UPV and UCS of CPB samples of the blast furnace slag cement (CEM III/A 42.5 N) steadily increased between 7 and 56 days. Increasing binder dosage or reducing w/c ratio and fines content (<20 μm) increased the UCS and UPV of CPB samples. UPV was found to be particularly sensitive to fines content. UCS data were correlated with the corresponding UPV data. A linear relation appeared to exist between the UCS and UPV of CPB samples. These findings have demonstrated that the UPV test can be reliably used for the estimation of the strength of CPB samples.     

Structure and Reactivity of 2-Hydroxyiminobenzyl-2-oxo-4,4,5,5-tetramethyl[1,3,2]dioxaphospholanes

Abstract

The reaction of 2-benzoyl-2-oxo-4,4,5,5–tetramethyl [1,3,2] dioxaphospholane (3) with hydroxylamine yields the corresponding E oxime (E-4) and benzonitrile (5), which arises from fragmentation of the Z oxime via an intramolecular attack of the N-OH on the phosphorus.     

Recovering orthogonal tensors under arbitrarily strong,but locally correlated,noise

We consider the problem of recovering an orthogonally decomposable tensor with a subset of elements distorted by noise with arbitrarily large magnitude. We focus on the particular case where each mode in the decomposition is corrupted by noise vectors with components that are correlated locally, that is, with nearby components. We show that this deterministic tensor completion problem has the unusual property that it can be solved in polynomial time if the rank of the tensor is sufficiently large. This is the polar opposite of the low-rank assumptions of typical low-rank tensor and matrix completion settings. We show that our problem can be solved through a system of coupled Sylvester-like equations and show how to accelerate their solution by an alternating solver. This enables recovery even with a substantial number of missing entries, for instance for $n$-dimensional tensors of rank $n$ with up to $40\%$ missing entries.