Magnetism and half-metallicity at the O surfaces of ceramic oxides

The occurence of spin-polarization at ZrO$_{2}$, Al$_{2}$O$_{3}$ and MgO surfaces is proved by means of \textit{ab-initio} calculations within the density functional theory. Large spin moments, as high as 1.56 $\mu_B$, develop at O-ended polar terminations, transforming the non-magnetic insulator into a half-metal. The magnetic moments mainly reside in the surface oxygen atoms and their origin is related to the existence of $2p$ holes of well-defined spin polarization at the valence band of the ionic oxide. The direct relation between magnetization and local loss of donor charge makes possible to extend the magnetization mechanism beyond surface properties

Salicylaldehyde hydrazones: buttressing of outer sphere hydrogen-bonding and copper-extraction properties

Salicylaldehyde hydrazones are weaker copper extractants than their oxime derivatives, which are used in hydrometallurgical processes to recover ~20 % of the world’s copper. Their strength, based on the extraction equilibrium constant Ke, can be increased by nearly three orders of magnitude by incorporating electron-withdrawing or hydrogen-bond acceptor groups (X) ortho to the phenolic OH group of the salicylaldehyde unit. Density functional theory calculations suggest that the effects of the 3-X substituents arise from a combination of their influence on the acidity of the phenol in the pH-dependent equilibrium, Cu2+ + 2Lorg ⇌ [Cu(L–H)2]org + 2H+, and on their ability to ‘buttress’ interligand hydrogen bonding by interacting with the hydrazone N–H donor group. X-ray crystal structure determination and computed structures indicate that in both the solid state and the gas phase, coordinated hydrazone groups are less planar than coordinated oximes and this has an adverse effect on intramolecular hydrogen-bond formation to the neighbouring phenolate oxygen atoms

Effect of impedance variation around the fundamentals on PA distortions characteristics under wideband multi-tone stimulus

Characterisation of modern wireless power transistors and amplifies requires wideband-modulated stimuli for realistic performance evaluation. Normally power transistor performance is evaluated using passive load-pull techniques. However, these have some physical realization constraints that influence the amplitude and the phase of the presented impedance at the DUT plane as across the modulated bandwidth. The problem becomes more apparent as modulation bandwidth is increased beyond few MHz. It has been shown recently that a digitally controlled active envelop load-pull (ELP) system can completely address this problem [1], thus allowing for a more systematic investigation of the parameters that may affect the performance of power transistors under wideband-modulated stimuli. In this paper, non ideal multi-tone impedance conditions are purposely introduced for demonstrating their effects on power amplifier performance in order to illustrate the DUT sensitivity to measurement system imperfections at higher modulation bandwidths in excess of few MHz

3–20 GHz GaN MMIC Power Amplifier Design Through a COUT Compensation Strategy

This paper presents the design approach for a compact, single-stage, wideband MMIC power amplifier. A method is proposed to compensate the output capacitance of the active device over a frequency range as wide as possible, with minimum impact on the achievable output power, that leads to a 2- element compensating network. A 3- section transformer is then adopted for a real-to-real transformation. The CW characterization shows output power higher than 32dBm and drain efficiency between 35% and 45%, over a fractional bandwidth of 148%, from 3 GHz to 20 GHz

Contrast Mechanisms for the Detection of Ferroelectric Domains with Scanning Force Microscopy

We present a full analysis of the contrast mechanisms for the detection of ferroelectric domains on all faces of bulk single crystals using scanning force microscopy exemplified on hexagonally poled lithium niobate. The domain contrast can be attributed to three different mechanisms: i) the thickness change of the sample due to an out-of-plane piezoelectric response (standard piezoresponse force microscopy), ii) the lateral displacement of the sample surface due to an in-plane piezoresponse, and iii) the electrostatic tip-sample interaction at the domain boundaries caused by surface charges on the crystallographic y- and z-faces. A careful analysis of the movement of the cantilever with respect to its orientation relative to the crystallographic axes of the sample allows a clear attribution of the observed domain contrast to the driving forces respectively.Comment: 8 pages, 8 figure

The Prospective Co-Parenting Relationship Scale (PCRS) for sexual minority and heterosexual people: preliminary validation

The coparenting relationship begins with a process of planning and negotiation about having children. Available psychological instruments have not been adapted to sexual minority people, which compromises their ecological validity. This mixed method study aimed to adapt and validate a prospective version of the Co-Parenting Relationship Scale in a Portuguese sample of sexual minority and heterosexual adults who did not have children and who were in a dyadic relationship. In study 1, cognitive interviews were used to gather participants’ reflections about the original items and the role played by the family of origin and anticipated stigma in coparenting (n = 6). In study 2, using a sample of individuals from 18 to 45 years old, two Exploratory Factor Analyses (EFA) were conducted separately for sexual minority (n = 167) and heterosexual persons (n = 198), and a Confirmatory Factor Analysis (CFA) was conducted for heterosexual persons (n = 176). Results showed underscored the importance of families of origin independent of sexual orientation. Different factorial structures for sexual minority and heterosexual persons were observed. Among sexual minority persons, the role of stigma was also highlighted. Implications for practice and research are discussed