A Ternary Map of Ni–Mn–Ga Heusler Alloys from Ab Initio Calculations

In the search for new magnetic functional materials, non-stoichiometric compounds remain a relatively unexplored territory. While experimentalists create new compositions looking for improved functional properties, their work is not guided by systematic theoretical predictions. Being designed for perfect periodic crystals, the majority of first-principles approaches struggle with the concept of a non-stoichiometric system. In this work, we attempt a systematic computational study of magnetic and structural properties of Ni–Mn–Ga, mapped onto ternary composition diagrams. Compositional stability was examined using the convex hull analysis. We show that the cubic austenite has its stability region close to the stoichiometric Ni2MnGa, in agreement with experimental data, while the tetragonal martensite spreads its stability over a wider range of Mn and Ni contents. The unstable compositions in both austenite and martensite states are located in the Ga-rich corner of the ternary diagram. We note that simultaneous stability of the austenite and martensite should be considered for potentially stable compounds suitable for synthesis. The majority of compounds are predicted to be ferrimagnetically ordered in both austenitic and martensitic states. The methodology used in this work is computationally tractable, yet it delivers some predictive power. For experimentalists who plan to synthesize stable Ni–Mn–Ga compounds with ferromagnetic order, we narrow the target compositional range substantially.

Development and Validation of Q-Absorbance Ratio by UV-Spectrophotometric Method for Simultaneous Estimation of Metformin and Empagliflozin in Bulk and Combined Dosage Form

Advantages of simultaneous stability studies are the identification of new degradation products, to understand mutual induction and/or inhibition of rates of degradation and to analyze the degradation products of both drugs. Various ultraviolet spectroscopic and high performance liquid chromatographic assay methods were reported for the estimation of metformin, sitagliptin, pioglitazone, glimepiride and simvastatin individually and in combination with other drugs. All the above reported methods were based on the estimation of metformin, sitagliptin, pioglitazone, glimepiride and simvastatin alone or in combination with other drugs. The degradation products were generated and successfully separated by the developed and validated high performance liquid chromatographic methods for the estimation of the selected anti-diabetic drug combinations. The aim of the study was to develop and validate of Q-Absorbance Ratio UV-Spectrophotometric Method for Simultaneous Estimation of Metformin and Empagliflozin in Bulk and Combined Dosage Form. Keywords: Metformin, Method Development, Validation, Empagliflozin, UV-Spectrophotometer.

Partial qualitative analysis of planar 𝓐Q-Riccati equations

If we view the field of complex numbers as a 2-dimensional commutative real algebra, we can consider the differential equation z'=az2+bz+c as a particular case of 𝓐- Riccati equations z'=a · (z · z)+b · z+c where 𝓐=( ℝn,·) is a commutative, possibly nonassociative algebra, a,b,c∈𝓐 and z:I → 𝓐 is defined on some nontrivial real interval. In the case 𝓐=ℂ, the nature of (at most two) critical points can be described using purely algebraic conditions involving involution * of ℂ. In the present paper we study the critical points of 𝓛(π)- Riccati equations, where 𝓛(π) is the limit case of the so-called family of planar Lyapunov algebras, which characterize 2-dimensional homogeneous systems of quadratic ODEs with stable origin. The number of possible critical points is 1, 3 or ∞, depending on coefficients. The nature of critical points is also completely described. Finally, simultaneous stability of the origin is considered for homogeneous quadratic part corresponding to algebras 𝓛(θ).

Finite-Time Simultaneous Stabilization for Stochastic Port-Controlled Hamiltonian Systems over Delayed and Fading Channels

In this paper, a finite-time simultaneous stabilization problem is investigated for a set of stochastic port-controlled Hamiltonian (PCH) systems over delayed and fading noisy channels. The feedback control signals transmitted via a communication network suffer from both constant transmission delay and fading channels which are modeled as a time-varying stochastic model. First, on the basis of dissipative Hamiltonian structural properties, two stochastic PCH systems are combined to form an augmented system by a single output feedback controller and then sufficient conditions are developed for the semiglobally finite-time simultaneous stability in probability (SGFSSP) of the resulting closed-loop systems. The case of multiple stochastic PCH systems is also considered and a new control scheme is proposed for the systems to save costs and achieve computational simplification. Finally, an example is provided to verify the feasibility of the proposed simultaneous stabilization method.

Variable within variable - Simultaneous stability and change. The case of syllable-final s in Ciudad Real

Spanish syllable-final s has been found to be completely stable in the great majority of the varieties in which it has been studied as a sociolinguistic variable. The same is true for the variety of Ciudad Real, Spain, where our data have shown not only lack of indication of any type of change at the present moment through inferences made from apparent time, but also evidence of its stability in the last hundred years by looking at the data from the available linguistic atlases. However, in our investigation, we performed a study of all the separate contexts in which the syllable-final s occurs, and it was discovered that in one of them, the sequence /s/+/t/, a different kind of behavior was registered. Namely, in this specific context, apparent-time inferences additionally supported by the older linguistic atlas data show a clear pattern of a change from above towards a normative realization of the sibilant. In this paper, we will try to explain how it is possible for a stable variable to contain within itself a subvariable which in turn shows signs of a change in progress.

Sparseness, Antisparseness and Anything in Between: The Operating Point of a Neuron Determines Its Computational Repertoire

A recent model of intrinsic plasticity coupled to Hebbian synaptic plasticity proposes that adaptation of a neuron's threshold and gain in a sigmoidal response function to achieve a sparse, exponential output firing rate distribution facilitates the discovery of heavy-tailed or super- gaussian sources in the neuron's inputs. We show that the exponential output distribution is irrelevant to these dynamics and that, furthermore, while sparseness is sufficient, it is not necessary. The intrinsic plasticity mechanism drives the neuron's threshold large and positive, and we prove that in such a regime, the neuron will find supergaussian sources; equally, however, if the threshold is large and negative (an antisparse regime), it will also find supergaussian sources. Away from such extremes, the neuron can also discover subgaussian sources. By examining a neuron with a fixed sigmoidal nonlinearity and considering the synaptic strength fixed-point structure in the two-dimensional parameter space defined by the neuron's threshold and gain, we show that this space is carved up into sub- and supergaussian-input-finding regimes, possibly with regimes of simultaneous stability of sub- and supergaussian sources or regimes of instability of all sources; a single gaussian source may also be stabilized by the presence of a nongaussian source. A neuron's operating point (essentially its threshold and gain coupled with its input statistics) therefore critically determines its computational repertoire. Intrinsic plasticity mechanisms induce trajectories in this parameter space but do not fundamentally modify it. Unless the trajectories cross critical boundaries in this space, intrinsic plasticity is irrelevant and the neuron's nonlinearity may be frozen with identical receptive field refinement dynamics.