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In this research work, aluminum substituted Ni-Co ferrite nanoparticles have been produced by a simple and cost-effective method, i.e., sol–gel auto-combustion. Synthesized nanoparticles were annealed in a muffle furnace at 600°C for 3 h before characterization. The x-ray diffraction patterns revealed that the ferrite nanoparticles grew preferentially along the (311) plane and exhibit face centered cubic structure. The crystallite size of nanoparticles (14 to 17 nm) was estimated by Scherrer’s relation. The effect of aluminum substitution on structural parameters of ferrite nanoparticles, such as lattice constant and stacking faults, have been studied. Structural analysis revealed that the lattice constant of the nanoparticles decreases as a function of aluminum content. The Fourier transform infrared spectroscopy confirmed the spinal ferrite crystal structure of synthesized aluminum substituted Ni-Co ferrite nanoparticles. The surface morphology observed through scanning electron microscopy depicts the growth and distribution of nanograins with uniform size with in the samples. Dielectric properties investigated through impedance analyzer spectroscopy revealed that aluminum substituted Ni-Co ferrite nanoparticles demonstrated the high conductivity along with potential dielectric properties. These aluminum substituted Ni-Co ferrite nanoparticles would have possible applications in high storage memory and microwave devices.

In this study, the sol-gel auto-combustion (SGAC) approach was used to synthesis praseodymium (Pr 3+ ) substituted Zinc-Cobalt (ZC) ferrites, having general formula Co 0.7 Zn 0.3 Pr x Fe 2−x O 4 (x = 0.0, 0.05, 0.10, 0.15, and 0.20). X-ray Diffraction (XRD) analysis revealed a secondary phase ( PrFeO 3 ) with a composition of x ≥ 0.10 and the presence of FCC structure. The crystallite size (D) of Pr 3+ doped ZC SFs decreased from 17.36 nm to 12.44 nm as the amount of Pr 3+ doping increased. Additionally, the lattice constant saw an enhancement from 8.34 a (Å) to 8.96 a (Å) with the incorporation of Pr 3+ into the ZC SFs. XRD and FTIR analysis verified the replacement of Pr 3+ into ZC SFs. Inhomogeneous grain size distribution was seen in samples by applying the Scanning Electron Microscopic (SEM) technique. It was discovered that the dielectric loss decreased with the applied frequency, which is helpful for high frequency device applications. The substitutions of Pr 3+ ions resulted in remanence (Mr (emu/g)), saturation magnetization (Ms (emu/g)) and coercivity (Hc (Oe)) maximum at x = 0.00 and minimum for x = 0.20 in ZC SFs, respectively. The maximum microwave frequency in GHz maximum for x = 0.00 (18.8 (GHz)) and minimum at sample x = 0.20 (7.86 (GHz)). According to the findings of our research, Pr 3+ substituted spinel ferrites appear to be very useful in radar, satellite communication, space communication, and microwave frequency applications.

A series of lanthanum (La)-doped nickel (Ni) ferrites NiLa x Fe 2- x O 4 with doping concentrations ( x  = 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05) is synthesized via a sol–gel auto-combustion method. Structural properties are determined with the help of X-ray diffraction (XRD). The effect of La doping on dielectric properties of Ni ferrites is discussed. XRD analysis confirms the existence of pure FCC spinel phase, and no impurity phase was detected. The lattice constant decreases initially due to strain produced by La 3+ ions replacement. At higher doping concentrations, the lattice constant increases due to the large ionic radius of La 3+ as compared to Fe 3+ . Tangent loss (tan δ ), dielectric constant, and dielectric loss values are determined in the 1 MHz to 3 GHz frequency range, and explained by the Maxwell–Wagner model. A persistent behavior of dielectric loss and dielectric constant was found in the mid microwave frequency region. The most stable behavior of the dielectric constant ( ε ′) and dielectric loss ( ε″ ) in the high-frequency region is found with ( x  = 0.04). Ac conductivity is also discussed in the 1 MHz to 3 GHz region, and is found to be impacted by grain and grain boundary resistive behavior at low and high frequencies. Cole–Cole plots of different samples, corresponding to different doping concentrations, are used to describe the conduction phenomena. The stable response of dielectric constant ( ε ′) and dielectric loss ( ε″ ) in the mid microwave frequency region makes NiLa x Fe 2- x O 4 nanoparticles a potential candidate for microwave devices. Highlights Lanthanum-doped nickel ferrites nanoparticles were successfully synthesized by sol–gel auto-combustion method. The effect of lanthanum doping in nickel ferrites on structural and electrical properties was investigated. The structural parameters such as lattice constant, crystallite size, lattice strain, microstrain were determined. Frequency-dependent dielectric, impedance, and electric modulus properties were investigated in microwave region. Ac conductivity in microwave region was also investigated.

PurposeThis article illustrates how, during the COVID-19 pandemic, emerging market exporting firms can adopt differentiation strategies using composition-based capabilities, which, in turn, will enable them to strengthen their images and market shares, i.e. their strategic marketing performance in advanced markets.Design/methodology/approachThis study is based on survey data obtained from 86 Pakistani firms exporting to advanced economies.FindingsThe study found that compositional collaboration capabilities positively influence the differentiation strategies and strategic marketing performance of emerging market exporting firms conducting business in advanced host markets. Furthermore, the findings indicate that differentiation strategies mediate the influence of compositional collaboration capabilities on the strategic marketing performance of these firms.Originality/valueBy taking a new compositional based theoretical perspective, this study examined the underexplored phenomenon of how emerging market firms can differentiate their offerings in advanced export markets in order to achieve a better strategic performance during external shocks such as the COVID-19 pandemic. Given that export growth is a strategic priority for many emerging markets, including Pakistan, due to their substantial trade deficits, this study provides important contributions from both the theoretical and practical perspectives.

Dysprosium (Dy 3+ ) substituted cobalt-zinc spinel ferrites were synthesized having composition (Co 0.7 Zn 0.3 Dy 3+ xFe 2−x O 4 ) with the concentration ranges from (0.00, 0.5, 0.10, 0.15, and 0.20) by using the Sol–Gel synthesis. XRD analysis confirmed the FCC spinel structure of the prepared samples. Lattice constant and X-ray density were calculated in variance ranging from 8.40–8.46 Å and 5.28–5.77 g/cm 3 , respectively. Fourier Transformation Infrared Spectroscopy (FTIR) were used to measure the frequency band in between 411–562 cm −1 for the tetra and octahedral positions. Scanning electron microscopy was used to study the surface morphology of the prepared samples. The field emission transmission electron microscopy (FE-TEM) was used for the confirmation of particle size. The calculated value of crystalline size was 13 nm, while particle size was the best on 23 nm. It was observed that, on applied field frequency the dielectric parameters exhibits decreasing trend. Magnetic properties were examined by Vibrating Sample Magnetometer (VSM) method and found out saturation magnetization (63.99 emu/g), anisotropy (K) (5366.82 J/m 3 ) and magnetic moment (2.77) were in decreasing while retentivity (2.38 emu/g), squareness ratio (0.07) and coercivity H c (133.71Oe) were in increasing trend respectively. These features of Dy 3+ substituted Co–Zn spinel ferrites recommend their better use in sensors and high frequency devices.

Praseodymium (III)-doped M-type SrPr x Fe 12-x O 19 (x = 0.00, 0.25, 0.50, 0.75, 1.00) hexa-ferrites were synthesized via micro-emulsion process followed by annealing of samples at 800 °C for 4 h. The effects of praseodymium particles on properties such as electrical, magnetic, and dielectric were studied. Via TGA the phase formation was observed to be started at 900 °C, and weight reduced to 5.27% at 1010 °C. Through X-ray diffraction (XRD), hexagonal structure was confirmed and structural properties were studied: the crystalline size, lattice constant, bulk and X-rays densities, i.e., 4.446 nm, 5.90 Å , 4.167 g·cm −3 and 6.46 g·cm −3 , respectively. The cation dispersion and shifting of frequencies were observed by FTIR at frequencies 430–590 cm −1 because of dopant of higher radii. Surface morphology, grain structure, and porosity were studied by scanning electron microscopy (SEM). Electrical properties were determined by impedance spectroscopy. The impact of Pr 3+ doping on distinct metrics, i.e. dielectric constants, dielectric loss, tan loss, A.C conductivity, was studied: 1.890, 0.023, 0.012, 0.001, respectively. The effects of Pr 3+ doping on retentivity, coercivity, saturation magnetization, and anisotropy were investigated by the vibrating sample magnetometer (VSM). The increase in saturation and remanence is due to the increase of Pr 3+ that retuned extra Fe 3+ ions from the lattice plot. The prepared materials offer valuable potential for applications of high-density recording medium applications and high-frequency devices.

Teacher behaviour and student motivation are well-known antecedents of student learning performance. However, their interaction effects remain under-explored, especially given the different types of teacher behaviour and motivation. This study2 involving students in a private Pakistani secondary school (n=367) examined these interaction effects on students’ perceived learning performance. Our findings show that when students viewed their teachers as providing better teaching and classroom structure (termed structure), their extrinsic motivation influenced perceived learning performance more than intrinsic motivation did. Conversely, how students perceived that their teachers related individually and personally to them (termed relatedness) were more pertinent in enhancing intrinsic, than extrinsic, motivation. We also demonstrated that extrinsic motivation mediated the effects of structure on only perceived grade performance, whereas intrinsic motivation mediated the effects of relatedness on grade performance as well as confidence in ability and staying motivated. Further, perceived teacher behaviour was reciprocally influenced by intrinsic motivation, but not by extrinsic motivation. The study extends academic research into the nexus of teacher behaviour and motivation, especially the differential importance of intrinsic over extrinsic motivation. It also provides practical guidance to educationists on improving student performance through appropriate teacher training.

Spinel ferrites have caught the attraction of researchers in the modern world. In this work, the spinel ferrites having formula Co 0.3 Cd 0.7 Zn 1.5 x Fe 2− x O 4 ( x  = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by Microemulsion method. Through XRD analysis, it was confirmed that all the samples were spinel ferrites. Crystallite size was found in the range of 9–17 nm, which was later on confirmed by SEM and EDX. Lattice parameter showed increasing trend which was due to larger ionic radii of Zn 2+ as compared to Fe 3+ . Impedance analyzer disclosed the electrical properties of prepared samples. Real and imaginary part of dielectric constant, impedance and modulus was determined with applied frequency range from 1 MHz to 3 GHz. The detailed electrical investigations were investigated in the frequency range of 100–3 GHz. Real and imaginary parts of impedance Z ′ and Z″ in the above frequency and substitution case suggested the existence of one relaxation regime which corresponds to grains which was totally different from its counterpart of bulks and has strong correlation with other ferrites. Real and imaginary part electrical modulus M ′ and M″ further showed the grains effect with increasing zinc substitution under the suppression of electrode polarization. A non-Debye relaxation behavior and the frequency-dependent conductivity were observed in dielectric spectra, which was also consistent with the results of AC conductivity spectra. Dielectric constant and dielectric loss showed a decreasing trend with increasing frequency and same was that with tangent loss. AC conductivity increased with increasing the frequency. Cole–Cole graph was plotted between M ′ and M ″ which confirmed the effect of only grains. Excellent dielectric properties suggest that these prepared nanoparticles are good for high-frequency device applications.

Spinel ferrites are materials that have technological and industrial applications. In this study Neodymium (Nd 3+ ) substituted Co–Zn spinel ferrites (CZNF) with chemical formula Co 0.7 Zn 0.3 Nd x Fe 2−x O 4 with the contents of (x = 0.00–0.20 with a 0.05 difference) was synthesized through sol–gel auto combustion method. The structure of the single-phase formations was verified by using X-ray diffraction (XRD). Moreover, in CZNF samples the crystallite size decreased as the Nd 3+ concentrations increased, except for the x = 0.15 sample. Moreover, by using XRD and Fourier transform infrared spectroscopy, the Nd 3+ substitution into CZNF spinel ferrite was confirmed. Using image-J software for microstructural analysis, it was discovered that adding Nd 3+ ions to CZNF caused an increase in particle size from 7 to 35 nm. It was noted that using UV–visible (UV–Vis) spectroscopy the optical energy band gap (Eg) was maximum at x = 0.00 and minimum for x = 0.20 by additions of Nd 3+ to the CZNF samples. The AC conductivity and dielectric constant of CZNF improved with the increase of Nd 3+ . The addition of Neodymium (Nd 3+ ) ion also decreased the dielectric tangent losses in CZNF spinel ferrites. The saturation magnetization and microwave frequency for x = 0.00 were a maximum of 82.22 (emu/g) and 18.14 GHz, and for x = 0.20, they were a minimum of 25.01 emu/g and 5.48 GHz, respectively. They are prospective materials for a variety of applications because of their dielectric and magnetic qualities, including bolometric devices, microwave absorption materials, and microwave frequency operating devices. Graphical abstract The graphical abstract presents the synthesis process of pure and modified Co–Zn spinel ferrites by sol–gel auto-combustion technique. The prospective materials for a variety of applications because of their dielectric and magnetic qualities, including bolometric devices, microwave absorption materials, and microwave frequency operating devices.

Gastrointestinal stromal tumors (GISTs) are neoplasms arising from the bowel wall, most often in the jejunoileum of the small intestine, but rarely from extragastrointestinal locations. GISTs most often occur in patients older than 40 years of age and can present with a multitude of gastrointestinal symptoms. We present a rare case of an extragastrointestinal stromal tumor (EGIST) causing abdominal pain and melena in a 34-year-old Hispanic male. The patient presented with diffuse abdominal pain, melena, and severe anemia. Computed tomography of the abdomen revealed a large mass abutting the small bowel. The patient was taken to surgery where the mass, which appeared to be deriving from the omentum and invading the adjacent small bowel, was completely excised and found to be a spindle cell GIST. Excision margins were determined to be negative, and the patient was started on a tyrosine kinase inhibitor for maintenance therapy. The patient continues to follow up on an outpatient basis for surveillance. This case represents the rare disease entity EGIST presenting outside the typical demographics of the disease in a young patient with no identified previous genetic syndromes. Gross examination of the mass in this case was also atypical given the appearance that the mass was rooted in the omentum and invading the small bowel which would suggest the primary tumor site was extragastrointestinal. This case demonstrates the need to build a differential diagnosis that includes GIST and the ability to successfully treat this disease if it is identified early in the clinical course.