Study on the interface morphology in the induction welding joint of PEEK plate at low power

Induction welding is an important joining technique with potentially significant application in the connection of the Poly Ether Ether Ketone (PEEK). The present research employs the metal mesh as induction components into the induction welding of PEEK plate to PEEK plate at low power successfully. Besides, the examinations and analyses of macro/micro-structures, energy dispersive spectroscopy (EDS) and mechanical tensile properties of the joints are conducted. Meanwhile, the characteristics and formation mechanisms of the lap-welded interface structures are interpreted in detail. The results indicate that the interface morphology of the welded joint is of high quality at low power, which most of the interface area is tightly connected due to the element diffusion. Besides, the connection mechanism of the joint is bonding connection and mechanical engagement, which plays a major role in a great performance joint. Furthermore, the tensile fracture of the joint occurs in the heat-affected zone, which contributes to a high joint tensile strength.

The reduction of source effect for reliable estimation of geomagnetic transfer functions

SUMMERY We have analysed the literature suggestions regarding possible changes in vertical magnetic transfer function (VTF) over time. We have shown that for periods above 1500 s the observed changes in VTF are caused by the source effect and we proposed how to reduce this negative impact. For calculations we used 1-min recordings of geomagnetic variations registered between 2002 and 2017 in various geomagnetic observatories. In data processing we used frequency-domain Egbert's algorithm and our original algorithm based on the method of least squares in the time domain for some comparisons and tests. We have shown that for periods over 1500 s the VTFs calculated separately from summer and winter data are different. However, our analysis shows that the variability of the VTF values obtained is misleading and results from time-changing presence of magnetic field variations that do not fulfill the assumption of plane wave (there is a vertical component in the incident magnetic field). These variations are much more numerous in summer than in winter. More detailed analysis has shown also that they are usually small at night and big during the day. The vertical components of these variations constitute an error correlated with input signals (horizontal components), which alters the values of the determined VTF. Furthermore, error bars do not take this effect into account. It makes it impossible to improve the accuracy of calculations by increasing the amount of data. Analysing the estimated external parts of vertical components from the Central European observatories we noticed a great similarity of these signals even if the induction components were clearly different, which indicates that this is a regional effect. On this basis, we proposed a procedure to improve the accuracy of VTF determination by means of pre-selection of data.

Supporting Special Education Teacher Induction Through High-Leverage Practices

Induction is designed to support teachers’ effectiveness, improve their students’ learning, and foster their retention. We consider how high-leverage practices (HLPs) might provide an instructional framework for special education teacher (SET) induction. With sensemaking theory as a conceptual foundation, we posit that, by structuring induction experiences and instructional conditions around HLPs, schools and districts can send more coherent messages about effective instruction, thereby easing new SETs’ efforts to make sense of their roles. We first provide a brief review of research on new SETs’ experiences. Next, we consider how specific induction components (i.e., professional development and mentoring, teacher evaluation, and collaboration) and instructional conditions (i.e., collaboration, instructional curricula and resources, and schedules) might be structured to support SETs’ learning of and use of these HLPs. We conclude with considerations for researchers and practitioners.

Properties of Fe-based nanocrystalline magnetic powder cores (MPC) and structure of particle size distribution (PSD)

This paper discusses the influence of the Particle Size Distribution (PSD) of the nanocrystalline Fe-based granular-soft-magnetic material on the final magnetic properties of a Magnetic Powder Core (MPC). Here we show how PSD impacts the final magnetic properties. Mixing fine and coarse particles, with a dominance of coarse particles, significantly influences the magnetic permeability increase of the core. Better magnetic features are noted for MPCs constructed with certain mass ratio of fine and coarse particles due to improvement in the magnetic path in the cores. This allows to offer new induction components to industry.

Mentoring as the Core Element of New Teacher Induction in the USA: Policies and Practices

The paper focuses on mentoring as the key strategy of novice teacher induction in the USA. The study reviews current mentoring/induction policies and trends in the U.S. system of in-service teacher training and support. The findings suggest that the conceptual framework, standards and practices of new teacher mentoring in the United States conform to the dynamic trends in education and organizational management. The conceptual modification of teacher mentoring manifests itself in the development of comprehensive and sustained formal induction programs based on the theories of educational leadership, adult learning, social interaction and collaborative learning. Quality induction programs are context-based and involve multiple stakeholders (schools, school districts, local educational organizations and agencies, partner universities, state departments of education etc). Diverse forms of mentoring (one-to-one, peer, group, reciprocal, online and needs-driven mentoring, etc.) are extensively combined with other induction components offered to beginning teachers and mentors during the whole induction period. The induction components include: summer courses, orientation sessions, workshops, seminars, webinars, conferences, interviews, informal meetings and celebrations, district-based mentor training programs etc. The quantitative data obtained through the analysis of the U.S. national surveys and research reports provides ground for highlighting those mentoring and induction programs which have significantly decreased turnover rates among new teachers, contributed to their professional development and improved academic achievement in public schools by providing students with quality instruction.

Magnetodielectric and Metalomagnetic 1D Photonic Crystals Homogenization:ε-μLocal Behavior

A theory for calculating the effective optic response of photonic crystals with metallic and magnetic inclusions is reported, for the case when the wavelength of the electromagnetic fields is much larger than the lattice constant. The theory is valid for any type of Bravais lattice and arbitrary form of inclusions in the unitary cell. An equations system is obtained for macroscopic magnetic field and magnetic induction components expanding microscopic electromagnetic fields in Bloch waves. Permittivity and permeability effective tensors are obtained comparing the equations system with an anisotropic nonlocal homogenous medium. In comparison with other homogenization theories, this work uses only two tensors: nonlocal permeability and permittivity. The proposal showed here is based on the use of permeability equations, which are exact and very simple. We present the explicit form of these tensors in the case of binary 1D photonic crystals.

An Evaluation on Transfection Efficiency of pHRE-Egr1-EGFP in Hepatocellular Carcinoma Cells Bel-7402 Mediated by PEI-MZF-NPs

To improve transfection and expression efficiency of target gene, especially under cancer anoxic microenvironment, we have developed pHRE-Egr1-EGFP/PEI-MZF-NPs nanosystem, in which pHRE-Egr1-EGFP, eukaryotic gene expression plasmid, is constructed by combining radiation promoter Egr1 with anoxia induction components (HRE), forming anoxic radiation double sensitive HRE/Egr1 promoter to activate reporter gene EGFP expression. MZF-NPs (Mn0.5Zn0.5Fe2O4magnetic nanoparticles), obtained by coprecipitation method, are coated with cation poly(ethylenimine) (PEI). We transferred pHRE-Egr1-EGFP into hepatocellular carcinoma Bel-7402 cells, using PEI-MZF-NPs as the carrier and tested some relevant efficacy. The results show that PEI-MZF-NPs have good DNA-binding ability, protection ability, release ability, little toxicity, and high transfection efficiency, obviously superior to those of the liposome method and electricity perforation method. Moreover, the expression level of EGFP gene induced by anoxia and radiation was significantly higher than that of single radiation activation. It is therefore concluded that HRE/Egr1 can induce and improve target gene expression efficiency in cancer anoxic microenvironment, and that PEI-MZF-NPs can be used as a novel nonviral gene vector which offers a viable approach to the mediated radiation gene therapy of cancer.