Extra Phase Research Articles

Frequency and temperature dependent electric polarization, relaxation, and transport properties of Mo and W doped BaTiO3

In this article, we report the structural, dielectric, electronic, and transport properties of Mo and W doped BaTiO3 ceramic. The BaTiO3 (BTO), BaTi0.85Mo0.15O3 (BTMO), and BaTi0.85W0.15O3 (BTWO) samples were prepared by double sintering ceramic technique. The X-ray diffraction patterns confirmed the tetragonal phase of the perovskite structure with the P4mm space group including some extra phases in BTMO and BTWO. A relaxation peak in the real part of electric modulus M'' is observed for BTO and BTMO at 3kHz. The dielectric constants, (εr' , εr'') and loss tangent (tanδ) for all samples were measured from 300 K to 450 K under the application of 100kHz electric field and temperature dependent dielectric anomalies ensure a ferroelectric (tetragonal) to paraelectric (cubic) phase transition in all samples. BTO and BTMO crystals display between normal ferroelectric and ideal relaxor behavior while BTWO crystal approaches to ideal relaxor ferroelectric behavior identified as canonical relaxor. Moreover, solid–liquid state anisotropy during the phase transition in all samples has been illustrated in terms of Fröhlich entropy. Apart from this, in BTO and BTWO samples, the conduction mechanism is highly dominated by the frequency of applied field compared to BTMO sample. Moreover, all studied samples exhibit semiconducting behavior with positive temperature coefficient of resistance (PTCR) effect in between 300 K and 450 K. The BTMO sample with maximum PTCR peak (2.9%/K at 415K) may find suitability for temperature controlled device application.

The Playful Role of the Girl in Empedocles’ B100

AbstractEmpedocles’ B100 contains an analogy between a girl handling a clepsydra and respiration. This article argues that proposals to establish Love (Bollack 1965, Gheerbrant 2017) or Persephone (Rashed 2008) as the girl’s respiratory equivalent are rendered unlikely by differences between their respective causal roles. Rather than her gender, this article emphasises the importance of the girl’s age: Empedocles required a playful child to handle the clepsydra. This child’s play results in the extra phase of submerging the clepsydra while the upper vent is open, which Empedocles needed to form a parallel for the first static phase of respiration.

Compact and broadband mode demultiplexer using a subwavelength grating engineered MMI coupler

A compact and broadband mode demultiplexer (DEMUX) using a subwavelength grating (SWG) engineered multimode interference (MMI) coupler is proposed and analyzed in detail. To effectively separate the input T E 0 and T E 1 modes, the input port is formed by cascading two tapers, connected by a silicon wire, in a single SWG MMI coupler. Moreover, by partially tailoring the grating duty cycle of the SWGs, an extra phase shifter is directly integrated in the MMI coupler, parallel to the input port for adjusting the phase in mode conversion. The input T E 0 mode can pass through the first taper and the silicon wire while being cut off and evolve into SWGs in the second taper, so that it is hardly affected by the extra phase shifter and directly mapped into the output port via MMI. On the contrary, the input T E 1 mode is cut off in the first taper and evolves through the sidewall of the first taper into two T E 0 -like components in the SWG region. Then an extra π / 2 phase shift between them is generated by the phase shifter. Finally, they are combined into the output T E 0 mode via MMI. By carefully choosing the structural parameters, the proposed T E 0 / T E 1 mode DEMUX shows a broad bandwidth of 350 nm from 1520 to 1870 nm for insertion loss < 1.0 d B and cross talk < − 10 d B and achieves a low insertion loss of 0.37 dB/0.40 dB and cross talk of − 18.50 d B / − 17.00 d B for T E 0 / T E 1 input at 1550 nm, within a short device length of only 18.6 µm. In addition, the device also shows a good fabrication tolerance to the deviations of structure parameters.

Urea and PVP assisted modified hydrothermal synthesis of spherical LiNi0.4Co0.2Mn0.4O2 cathode materials for battery application

Spherical LiNi0.4Co0.2Mn0.4O2 powders are synthesized via the modified hydrothermal method with the presence of urea and polyvinyl pyrrolidone (PVP). For comparison, LiNi0.4Co0.2Mn0.4O2 powders are also synthesized via the normal hydrothermal method without urea and PVP. In the normal hydrothermal process, incomplete compound formation with extra Li2MnO3 phase is observed. Whereas, phase-pure LiNi0.4Co0.2Mn0.4O2 powders with the well-ordered layered structure are obtained via the modified hydrothermal process. The modified hydrothermal process considerably reduces the cation disorder of Li+/Ni2+ and yields spherical-shaped particles. The LiNi0.4Co0.2Mn0.4O2 powders synthesized via the modified hydrothermal process delivers a high discharge capacity of 159 mAh/g at 0.1 C with the capacity retention of 94% at 0.3 C after 100 cycles. On contrary, the powder synthesized via the normal hydrothermal process delivers a low specific capacity of 126 mAh/g at 0.1 C with capacity retention of only 74% at 0.3 C after 100 cycles. Based on the results of electrochemical impedance and galvanostatic intermittent titration, the charge transfer resistance and charge diffusion coefficient of the sample synthesized via the modified hydrothermal process are found to be 16 ohm and 7.5 × 10−12 cm2/s, respectively. The present study reveals the feasibility to prepare phase-pure LiNi0.4Co0.2Mn0.4O2 cathode with a promising high-rate performance by adding PVP and urea during the hydrothermal synthesis process.

Optical and microstructural characterization of nanocrystalline Cu doped ZnO diluted magnetic semiconductor thin film for optoelectronic applications

A series of Zn 1-x Cu x O nanocrystalline films were deposited on a silica substrate using e-beam evaporation technology. The physical properties of the deposited film were closely examined using x-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), atomic force microscopy (AFM), and spectroscopic ellipsometry (SE). The deposited film's structure revealed the formation of a hexagonal wurtzite structure, with no extra phases found. According to AFM analysis, the deposited Zn 1-x Cu x O (x = 0.0, 0.04, 0.08, 0.12, 0.16, and 0.2) film has nanocrystalline characteristics. The present findings show that increasing Cu content up to x ≤ 0.2 reduces the direct optical energy gap E g from 3.286 eV (x = 0) to 2.934 eV (x = 0.2), which can be attributed to the sp-d exchange coupling. The refractive index dispersion extracted from SE analysis for Cu-doped ZnO thin films increased as the Cu dopant increased. In addition, the refractive index dispersion of the deposited film was studied using a single oscillator model proposed by Wemple-DiDomenico (WDD). It was found that the oscillator energy E o decreases as the Cu concentration increases, while the dispersion energy E d increases. As a result of the improvement in the optical energy band gap and the tunability of the values of the dispersive oscillator parameters E o , E d , n 0 , ε 0 , M -1 , and M -3 with increasing Cu doping levels, Cu doped ZnO films are a good candidate for optoelectronic device applications. • E-beam techniques is used to deposit a series of thin film of Cu doped ZnO. • The deposited film's structure show the formation of a hexagonal wurtzite structure. • SE technique is used to obtained the direct energy gap and found that E g is reduced from 3.286eV to 2.934eV with Cu concentration increases from 0 up to 0.2. • The SE analysis reveal that refractive index dispersion of Cu-doped ZnO thin films has increased as the Cu dopant has increased.

Polymer Nanocomposites with High Energy Density Utilizing Oriented Nanosheets and High-Dielectric-Constant Nanoparticles.

The development of high-energy-density electrostatic capacitors is critical to addressing the growing electricity need. Currently, the widely studied dielectric materials are polymer nanocomposites incorporated with high-dielectric-constant nanoparticles. However, the introduction of high-dielectric-constant nanoparticles can cause local electric field distortion and high leakage current, which limits the improvement in energy density. In this work, on the basis of conventional polymer nanocomposites containing high-dielectric-constant nanoparticles, oriented boron nitride nanosheets (BNNSs) are introduced as an extra filler phase. By changing the volume ratios of barium titanate (BT) and BNNSs, the dielectric property of polymer nanocomposites is adjusted, and thus the capacitive energy storage performance is optimized. Experimental results prove that the oriented BNNSs can suppress the propagation of charge carriers and decrease the conduction loss. Using poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) as the polymer matrix, the P(VDF-HFP)/BNNS/BT nanocomposite has a higher discharged energy density compared with the conventional nanocomposite with the freely dispersed BT nanoparticles.

Passband-Flattened Frequency-Tunable Optical Fiber Multiwavelength Filter with Composite Combination of Waveplates.

We propose a passband-flattened frequency-tunable optical multiwavelength filter with a composite combination of waveplates, which is realized by harnessing a polarization-diversified loop structure. The proposed filter comprises a polarization beam splitter (PBS), two polarization-maintaining fiber (PMF) segments of equal length, an ordered waveplate combination (OWC) of a half-wave plate (HWP) and a quarter-wave plate (QWP) before the first PMF segment, and an OWC of a QWP and an HWP before the second PMF segment. The second PMF segment is butt-coupled to one port of the PBS so that its slow axis is oriented at 22.5° for the horizontal axis of the PBS. Based on the filter transmittance derived through the Jones calculus, we found the orientation angle (OA) sets of the four waveplates, which could induce an extra phase shift Φ from 0° to 360° in the passband-flattened transmittance function. From the transmission spectra calculated at the eight selected OA sets, which caused Φ to increase from 0° to 315° by steps of 45°, it was confirmed that the passband-flattened multiwavelength spectrum can be continuously tuned by properly controlling the OAs. This indicates continuous wavelength tunability based on composite OWCs. Then, this theoretical prediction was verified by experimental demonstration.

Synthesis and characterization of a solid solution series of the type Bi<sub>2</sub>M<sub>x</sub>Mn<sub>4-x</sub>O<sub>10</sub> (M = Cr<sup>3+</sup>, Co<sup>3+</sup> and 0.0 ≤ x ≤ 2.0.)

Bi2Mn4O10 was synthesized from corresponding metal salts in glycerin by using an organic precursor-based glycerin nitrate method. The precursor was heated at various temperatures (300 – 800 °C) for about 18 hours to determine the lowest synthesis temperature for the formation of Bi2Mn4O10. The XRD patterns of the calcined samples revealed that the desired mullite type phase started to form at 600 °C, which became more crystalline with further increase of calcination temperature. Attempts were also taken to prepare chromium and cobalt incorporated solid solution series with nominal composition Bi2MxMn4-xO10 (M = Cr3+ and Co3+) by the same procedure. The XRD data of these series exhibited mullite type single phase up to x = 0.7 and 0.1 compositions for chromium and cobalt, respectively. For further insertion of M, an extra phase appeared along with the mullite type phase.
 J. Bangladesh Acad. Sci. 45(1); 13-26: June 2021

Real-time motion-induced error compensation for 4-step phase-shifting profilometry.

Phase-shifting profilometry has been widely used in high-accuracy three-dimensional (3D) shape measurement. However, for dynamic scenarios, the object motion will lead to extra phase shift and then motion-induced error. Convenient and efficient motion-induced error compensation is still challenging. Therefore, we proposed a real-time motion-induced error compensation method for 4-step phase-shifting profilometry. The four phase-shifting images are divided into two groups to calculate two corresponding wrapped phases, one from the first three fringes and the other from the last three fringes. As the motion-induced error doubles the frequency of the projected fringes, the average phase can effectively compensate the motion-induced error because there is a π/2 phase shift between the adjacent frames. Furthermore, we designed a time sequence by recycling the projection fringes in a proper order, and the efficiency of 3D reconstruction could be effectively improved. This method performs pixel-wise error compensation, based on which we realized 50 fps real-time 3D measurement by GPU acceleration. Experimental results demonstrate that the proposed method can effectively reduce the motion-induced error.

A low-sintering temperature microwave dielectric ceramic for 5G LTCC applications with ultralow loss

In next-generation mobile and wireless communication systems, low sintering temperature and excellent dielectric properties are synergistic objectives in the application of dielectric resonators/filters. In this work, Li2Ti0·98Mg0·02O2·96F0.04–1 wt% Nb2O5 (LTMN) ceramics were fabricated, and their sintering temperature was successfully lowered from 1120 °C to 750 °C by adjusting the mass ratio of B2O3–CuO (BC) additive. The optimum dielectric properties (ԑr ~ 24.44, Q × f ~ 60,574 GHz and τf ~ 22.8 ppm/°C) were obtained in BC-modified LTMN ceramics sintered at 790 °C. Even if their sintering temperature was lowered to 750 °C, the lowest temperature among the Li2TiO3-based dielectric ceramics currently used for LTCC technology, excellent dielectric properties (ԑr ~ 23.77, Q × f ~ 51,636 GHz) were still maintained. Additionally, no extra impurity phase was detected in BC-modified LTMN ceramics co-fired with Ag at 790 °C, indicating that BC-modified LTMN ceramics have a bright prospect in high-performance LTCC devices for 5G applications.

Generation of Geometric Extra Phase and Accompanying Temporal Effects in Asymmetric Optically Compensated IPS-LCDs and FFS-LCDs

This paper reports the generation of an extra phase and the accompanying temporal effects in an asymmetric optically compensated in-pane-switching (IPS) liquid crystal (LC) system and a fringe-field-switching (FFS) liquid crystal display (LCD) exhibiting a twofold faster response speed in the switching-off process compared with that in single and symmetric IPS-LCDs and FFS LCDs for the first time. To explain the experimental results, we derived an approximate analytical formula for the optical output intensity that includes an extra phase advancement and conducted simulations to achieve normally black operation using a dynamic optical retarder.

Studies on electrical properties of Fe doped ZnO nanostructured oxides synthesized by sol–gel method

We report the results of the studies on electrical properties of Zn1–xFexO (x = 0.10, 0.15 and 0.20) nanoparticles synthesized using sol–gel method. X–ray diffraction (XRD) measurement confirms the presence of extra phase of ZnFe2O4 in all the samples which gets enhanced with increase in Fe concentration. Surface morphological studies using atomic force microscopy (AFM) suggest the reduction in grain size with increase in Fe doping level in ZnO. All the dielectric parameters show dispersion nature and dielectric constant has been found to increase with Fe content. The obtained dielectric behavior has been understood on the basis of Maxwell–Wagner (M − W) mechanism and Koop's theory. Frequency dependent electrical conductivity has been understood on the basis of Jonscher's universal power law that suggests a conduction of charge carrier through correlated barrier hopping (CBH) mechanism. Impedance spectroscopy measurements have been explained on the basis of crystal cores and crystal boundary density. Grain boundary contribution in conduction mechanism is identified by fitting equivalent circuit model on cole–cole plots. Temperature and magnetic field dependent variation in electrical properties of studied samples has been understood on the basis of structure–property correlations.

Development of a modified quick, easy, cheap, effective, rugged, and safe method based on melamine sponge for multi-residue analysis of veterinary drugs in milks by ultra-performance liquid chromatography tandem mass spectrometry

The purpose of this study was to develop a modified QuEChERS method based on melamine sponge for rapid determination of multi-class veterinary drugs in milks by UPLC-MS/MS. Through simple infiltration and extrusion, fast and convenient matrix purification could be achieved within several seconds, and there was no need of extra phase separation operations. Good linearity with correlation coefficient (R2) ≥0.999 was obtained for all drugs in the range of 2~500 µg·kg−1. The obtained matrix effects were within ±20% for all monitored drugs. The recoveries of all monitored drugs ranged from 60.7% to 116.0% at three spiked levels (50, 100, and 200 µg·kg−1), with relative standard deviations less than 7.4%. Comparatively low LODs and LOQs were obtained in the ranges of 0.1~3.8 µg·kg−1 and 0.2~6.3 µg·kg−1, respectively. Compared with conventional purification adsorbents, melamine sponge yielded an equal or higher purification performance with matrix removal rate as high as 52.5% and acceptable recoveries in range of 60%-120% for all monitored drugs. The satisfactory results have demonstrated the good potential of melamine sponge in matrix purification for rapid determination of multiclass residues in food safety.

Enhancement of multifunctional optoelectronic and spintronic applications of nanostructured Cr-doped SnO2 thin films by conducting microstructural, optical, and magnetic measurements

A chemical synthesis method was used to produce Cr-doped SnO2 nanoparticles. By using the TEM technique, the nanocrystalline nature of the Sn1-xCrxO2 (0.0 ≤ x ≤ 0.1) nanopowder was confirmed. With different Cr concentrations, the electron beam deposition technique was used to deposit a series of Sn1-xCrxO2 nanocrystalline thin films on a silica substrate. X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and vibrating sample magnetometry (VSM) techniques were used to examine the physical properties of the deposited films. The nanocrystalline nature of the Sn1-xCrxO2 (0.0 ≤ x ≤ 0.1) thin film was confirmed by XRD and AFM morphology measurements. The XRD spectrum of the Sn1-xCrxO2 nanocrystalline film demonstrated a tetragonal crystal structure with no detectable extra phases. The optical measurements showed that as the Cr content increases, the direct optical energy gap Eg decreases without any sign of solubility limit up to x ≤ 0.1. The decrease in Eg is attributed to the sp-d exchange interaction. Also, the spectral behavior of the refractive index dispersion of the Cr-doped SnO2 indicates that as the Cr dopant increases, the refractive index of the deposited film also increases, which is attributed to the increase in the polarizability. Moreover, as the Cr content raises the atomic number, the density of the deposited film increases from 1.43 × 1022 cm−3 for SnO2 to 1.57 × 1022 cm−3 for Sn0·9Cr0·1O2. Further, the behavior of the refractive index dispersion of the deposited film was revealed using a single oscillator model proposed by Wemple-DiDomenico (WDD). Our calculations revealed that as the Cr concentration increases, the value of oscillator energy Eo decreases owing to the decrease in Eg, whereas the value of dispersion energy Ed increases because of the chemical structural changes such as the lattice parameters. Finally, the magnetic studies revealed that incorporating a small fraction of Cr into SnO2 produces room temperature ferromagnetism in the film, which is gradually suppressed by a further increase in Cr doping. These findings indicate that the Cr-doped SnO2 film can be recommended for optoelectronic and spintronic device applications.

Defects induced enhancement of antifungal activities of Zn doped CuO nanostructures

CuO nanostructures doped with different concentration of Zn have been synthesized by a simple low-cost combustion method. The prepared samples have been tested by the various techniques such as X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Optical absorption spectroscopy, Photoluminescence, and X-ray photoelectron spectroscopy (XPS). XRD confirmed the presence of the monoclinic phase of CuO along with an extra ZnO phase in the CuO:Zn. TEM results confirmed almost spherical - shaped nanoparticles as well as some irregular shaped NPs for pure CuO and Zn doped CuO with the average size from 24 to 55 nm. The change in morphology revealed a structural change in the CuO:Zn crystal due to different concentration of the Zn. The chemical study was done by XPS and the results were also correlated with XRD based results. The role of localized defects was compared and interpreted for the change in the luminescence spectral bands, micro-stains and oxidation states of the CuO:Zn for the different concentrations. CuO:Zn nanostructures demonstrated significant antifungal activities against two South African plant pathogens, Alternaria alternata CGJM3078 and Alternaria alternate CGJM3006, in comparison to pure CuO samples. The result showed that the pure and Zn doped CuO samples could be used as a good antifungal agent that could have an extensive applications in the agricultural and biotechnological industries.

Increasing the topological diversity of light with modulated Poincaré beams

We introduce a wide class of singular inhomogeneously polarized beams characterized by a nonuniform rotation rate of the local polarization azimuth about a C- or a V-point. They are obtained by adding an extra phase modulation with an m-fold rotational symmetry to the helical wavefronts underpinning Poincaré beams. The resulting modulated Poincaré beams have been theoretically studied and experimentally generated using tailored space-varying-axis plates based on liquid crystals.

The relationship between serum magnesium and bio-electrical impedance variables in patients undergoing dialysis

Introduction: The relationships between serum magnesium(Mg) levels and body composition or clinical outcomes of incident dialysis patients remain unclear. The aim of this study was to evaluate the possible correlations between magnesium and bio-electrical impedance variables, a method of determining body composition in two groups of hemodialysis(HD) and peritoneal dialysis(PD) patients. Methods: This prospective observational study examined the relationships between Serum Mg levels and Bio-impedance variables including total body fat, body cell mass, extra cellular mass, total body water (TBW), intra and extra cellular water (ICW and ECW), ECW/ICW and phase angle (PA) in incident 38 HD and 34 PD patients since December of 2012 in Mashhad Imam Reza Hospital dialysis center. The correlation between Mg and bio-impedance variables was assessed applying the student test and Pearson’s correlation coefficient. Results: the average concentration of serum Mg was 1.22 mmol/L in HD patients and 1.20 mmol/L in PD patients which is well above the reference range in normal population. the average amount of body water and also ICW in patients were significantly higher than HD patients. Our statistical analysis showed no significant relation between serum Mg and Bio-electrical impedance variables in HD patients, however in PD patients, a statistically significant correlation was found between serum Mg and ECW (r = 0.48, p = 0.02), ICW (r =- 0.48, p = 0.02), and ECW/ICW (r = 0.43, p = 0.02). Conclusion: we speculated that there is a link between serum Mg level and intravascular and extravascular water content in PD patients, however we cannot prove any correlation between serum Mg level and Bio-impedance variables in such patients. This could be considered as a sign of Mg role in healthy cell function in PD patients.

Resistive and magnetoresistance behaviors of BiFeO3 incorporated La0.7Ca0.3MnO3 composites

Micronsized matrix of La0.7Ca0.3MnO3 (LCMO) was synthesized by solid state reaction route whereas BiFeO3 (BFO) nanoparticles were synthesized by sol–gel method. Different contents of BFO nanoparticles were incorporated into the micronsized LCMO matrix lattice to prepare their composites. X–ray diffraction (XRD) measurement was performed to understand the crystalline phases present in these composites. Structural investigation suggests the dual phase nature of all the composites (consist of LCMO and BFO phases). No extra phases other than two, LCMO and BFO phases, can be found in the XRD patterns. Transport and magnetotransport properties have been studied by recording the temperature and magnetic field dependent resistance of the composites. Resistivity behavior shows that all the composites exhibit metal to insulator transition at TP which is highly sensitive to magnetic field and BFO content. The values of resistivity are also influenced by the applied magnetic field and BFO content in the composites. Since all three composites with different BFO contents (i.e. 0, 10 and 20%) exhibit low temperature resistivity minimum behavior, various theoretical models and mechanisms have been employed to understand the responsible charge conduction across the composite lattices. All composites exhibit negative magnetoresistance (MR) which has been discussed in detail on the basis of role of high resistive nanoparticles of BFO incorporated within the micronsized LCMO matrix.

Implant-associated osteomyelitis: Development, characterisation, and application of a porcine model.

Implant-associated osteomyelitis: Development, characterisation, and application of a porcine model.

The ethics of patient and public involvement across the research process: towards partnership with people with aphasia

ABSTRACT Background: Conducting Patient and Public Involvement (PPI) in health research is a way of building knowledge that incorporates the experience of service users, adds research impact, and helps avoid wasting resources on findings that have little relevance to people or cannot be implemented. We argue that there is a need to extend ethical considerations currently focused on research participants with aphasia to encompass and guide expectations of involvement in partnerships with people with aphasia across the research lifecycle. Method: We use the 2018 revision of the Australian National Statement on Ethical Conduct in Human Research as the framework for this article. The National Statement is underpinned by values based on respect for human beings, research merit and integrity, justice, and beneficence. While the National Statement outlines the ethical standards for conducting human research with research participants in Australia, the ideas and principles within it draw on international norms. Building on the seven elements of the research process introduced in Chapter 3 of the National Statement, we develop a model for examining ethics and PPI across the research lifecycle. This model revolves around an extra phase, Element Zero, required for the preparation of PPI for both researchers and research partners with aphasia. Results: There are many ethical considerations when involving patients and members of the public across the research lifecycle. Ethical questions that arise in relation to patients and the public as partners (whether in a role of consultant, advisor, collaborator or within user-controlled projects) may differ from those associated with participants. The nature of the relationships built through the PPI process requires a clear extension of the remit for research ethics to encompass ethical reflection both before the design of a project and after a project has ended as represented by the Ethics and PPI Research Lifecycle Model. Conclusion: The role of people with aphasia as partners in research recognises their expertise and potential to improve the relevance and impact of research endeavours. Reflecting on the ethical implications of this is crucial, protecting, empowering and enabling both researchers and partners with aphasia to engage with each other through respectful and positive research relationships.