In this study, manganese substituted strontium hexaferrite (SrFe
12−
x
Mn
x
O
19
;
x
= 0, 3, 5, and 7) prepared by the sol-gel auto-combustion method are studied. We observed that the substituted Mn ...preferentially goes to the 2a and 12k sites of Fe. Raman modes related to the 12k site suggest the stiffening of the lattice. The transformation of the grain's shape from hexagonal (
x
= 0 and 3) to rhombohedral (
x
= 7) was observed, as shown in the micrographs obtained from FESEM. The thermomagnetic curves show the shift of
T
C
to lower temperatures with the increase in the Mn content. From
x
= 5 onwards, the growth of another magnetic phase (FiM2) of lower coercivity apart from the parent phase (FiM1) of higher coercivity is seen. The FiM2 phase was found to increase with the Mn content in the sample (16.4(3)% for
x
= 5 but 66.2(5)% for
x
= 7). Although the magnetization for both FiM1 and FiM2 decreases with the increase in temperature, both magnetic phases behave in contrast to each other for
x
= 5 and
x
= 7. The study suggests a transformation of the compound from high magnetic anisotropy (
x
= 0) to low magnetic anisotropy (
x
= 7). The
x
= 5 composition sample displays the highest value of the first-order ME coefficient (0.83(2) mV × cm
−1
× Oe
−1
). The observed value for
x
= 5 composition is ∼2.5 times higher than that of the parent
x
= 0 composition sample (0.33(2) mV × cm
−1
× Oe
−1
). The studies thus suggest that the
x
= 5 composition is one of the viable candidates for magnetoelectric applications.
The highest strained compound SrFe
7
Mn
5
O
19
having highly distorted crystallographic sites, with a mixed ferrimagnetic phase, showing ∼118% enhancement in the linear magnetoelectric coupling (
α
/
d
-value) in comparison to the parent compound (SrFe
12
O
19
).
This work represents an effective approach to witness the true impedance profiles of the material. Here, a double-perovskite material LaYFe
2
O
6
is prepared by the sol–gel auto-combustion method, ...which is characterized by the x-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA)–differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (EIS) technique. The XRD measurement confirms the successful synthesis of the said material with orthorhombic crystal structure having symmetry P2
1
nm ( ~ 90%) and a slight contribution from Pbnm phase ( ~ 10%). The FESEM image suggests porous nature of the sample having grain size ~ 150 nm, sintered at 1473 K. TGA with simultaneous DSC measurement shows slight but gradual mass loss (related to adsorbed gases/vapors) above 400 K. The EIS shows influence of the adsorbed gases/vapors in the pores of the pellet on the impedance data. In this context, a homemade open-atmospheric impedance measurement setup is developed. The EIS measurement are done for (1) as-prepared sample, (2) sample preheated to 473 K before performing EIS, and (3) sample preheated to 400 K under vacuum. The process giving best result (having minimum effect of the adsorbed gases on the observed impedance spectra) is found by following the method (2).
In this study, manganese substituted strontium hexaferrite (SrFe12−xMnxO19; x = 0, 3, 5, and 7) prepared by the sol–gel auto-combustion method are studied. We observed that the substituted Mn ...preferentially goes to the 2a and 12k sites of Fe. Raman modes related to the 12k site suggest the stiffening of the lattice. The transformation of the grain's shape from hexagonal (x = 0 and 3) to rhombohedral (x = 7) was observed, as shown in the micrographs obtained from FESEM. The thermomagnetic curves show the shift of TC to lower temperatures with the increase in the Mn content. From x = 5 onwards, the growth of another magnetic phase (FiM2) of lower coercivity apart from the parent phase (FiM1) of higher coercivity is seen. The FiM2 phase was found to increase with the Mn content in the sample (16.4(3)% for x = 5 but 66.2(5)% for x = 7). Although the magnetization for both FiM1 and FiM2 decreases with the increase in temperature, both magnetic phases behave in contrast to each other for x = 5 and x = 7. The study suggests a transformation of the compound from high magnetic anisotropy (x = 0) to low magnetic anisotropy (x = 7). The x = 5 composition sample displays the highest value of the first-order ME coefficient (0.83(2) mV × cm−1 × Oe−1). The observed value for x = 5 composition is ∼2.5 times higher than that of the parent x = 0 composition sample (0.33(2) mV × cm−1 × Oe−1). The studies thus suggest that the x = 5 composition is one of the viable candidates for magnetoelectric applications.
•CoFe2O4/Cr2O3 nanocomposite is studied for the possession of magnetoelectricity.•Magnetoelectricity is observed up to 340 K i.e., above TN of Cr2O3.•Weak room temperature ferromagnetism is observed ...for the nanocomposite.•Impedance and modulus analysis of the nanocomposite reveal single relaxation mechanism.
Cobalt ferrite CoFe2O4 (CFO)/chromium oxide Cr2O3 (CR) nanocomposite is prepared by following the sol-gel autocombustion method in order to study its magnetoelectric (ME) properties. The presence of both the CFO (cubic) and CR (rhombohedral) phases is confirmed from the Rietveld refinement results of X-ray diffraction (XRD) patterns. Field emission scanning electron micrograph (FESEM) display the homogeneous distribution of particles with the average particle sizes of ~50–300 nm. A small opening of hysteresis in the magnetization (M)-magnetic field (H) plot signifies the existence of weak ferromagnetism in the sample. The frequency dependence of impedance responses subjected to applied magnetic fields are well described by impedance based Havriliak-Negami expression and revealed the presence of single relaxation which is attributed to the grains response. The involvement of p-type polaronic relaxation is confirmed from the obtained value of activation energy ≈0.39 eV. More interestingly, the direct magnetoelectric measurement shows the existence of linear magnetoelectricity up to 340 K and therefore provide applications in various ME-based devices.
In this study, manganese substituted strontium hexaferrite (SrFe
Mn
O
;
= 0, 3, 5, and 7) prepared by the sol-gel auto-combustion method are studied. We observed that the substituted Mn ...preferentially goes to the 2a and 12k sites of Fe. Raman modes related to the 12k site suggest the stiffening of the lattice. The transformation of the grain's shape from hexagonal (
= 0 and 3) to rhombohedral (
= 7) was observed, as shown in the micrographs obtained from FESEM. The thermomagnetic curves show the shift of
to lower temperatures with the increase in the Mn content. From
= 5 onwards, the growth of another magnetic phase (FiM2) of lower coercivity apart from the parent phase (FiM1) of higher coercivity is seen. The FiM2 phase was found to increase with the Mn content in the sample (16.4(3)% for
= 5 but 66.2(5)% for
= 7). Although the magnetization for both FiM1 and FiM2 decreases with the increase in temperature, both magnetic phases behave in contrast to each other for
= 5 and
= 7. The study suggests a transformation of the compound from high magnetic anisotropy (
= 0) to low magnetic anisotropy (
= 7). The
= 5 composition sample displays the highest value of the first-order ME coefficient (0.83(2) mV × cm
× Oe
). The observed value for
= 5 composition is ∼2.5 times higher than that of the parent
= 0 composition sample (0.33(2) mV × cm
× Oe
). The studies thus suggest that the
= 5 composition is one of the viable candidates for magnetoelectric applications.
The present work reports an enhanced magnetoelectric (ME) effect at room temperature (RT) and above in a nanocomposite of LaYFe2O6/poly(vinylidene fluoride)–hexafluoropropylene LaYFe2O6/P(VDF-HFP), ...which is prepared by the solution-casting method. Field-emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy reveal excellent phase-to-phase connectivity and an enhanced beta-phase fraction in the PVDF matrix by the incorporation of 10 wt % antiferromagnetic nanoparticles (NPs). This is also substantiated by the improved ferroelectric (electric-field-dependent polarization) response by a 10 wt % sample. At RT, this nanocomposite manifests a first-order ME coupling coefficient of ∼2.92 mV cm–1 Oe–1 and a second-order ME coupling coefficient of ∼0.051 μV cm–1 Oe–2 (significantly 1 order higher than that of pristine LaYFe2O6). The enhanced ME coefficient at RT and above makes it a viable candidate to address the challenges of ME-based device applications. A flexible, portable, lightweight, cost-effective magnetoelectric nanogenerator (MENG) fabricated from the nanocomposite film is able to harvest the wasted magnetic energy with an efficiency of 1.5%. As a demonstration, the harvested electric energy is stored in a capacitor, which, in turn, is used to power a light-emitting diode (LED). The present work hence suggests the deployment of this material for self-powered wearable devices.
The aim of this study was to estimate the prevalence and causes of visual impairment (VI) and blindness and diabetic retinopathy (DR) in Siwan district, Bihar.
A population-based cross-sectional ...study was done from January to March 2016 using the Rapid Assessment of Avoidable Blindness 6 (RAAB 6, incorporating DR module) methodology. All individuals aged ≥50 years were examined in 57 randomly selected clusters within the district.
A total of 3476 individuals were enumerated and 3189 (92%) completed examination. The overall prevalence of blindness and severe VI was 2.2% (95% confidence interval (CI): 1.6-2.8) and 3.4% (95% CI: 2.6-4.3), respectively. Untreated cataract was the leading cause of blindness (73%) and severe VI (93%). The cataract surgical coverage (CSC) at <3/60 was 71.5% for eyes and 89.3% for persons in this sample and the CSC was similar between the genders. Refractive error (71%) was the primary cause of early VI. The overall prevalence of known and newly diagnosed diabetes was 6.3% (95% CI, 5.4-7.2%). Prevalence of any DR, maculopathy, and sight-threatening DR was 15, 12.4, and 6%, respectively.
To conclude, as compared to previous reports, the prevalence of blindness and DR in Siwan district of Bihar was found to be lower and the CSC was higher. However, the problem of avoidable blindness remains a major problem in this region.
Surgical site infections (SSIs) are prevalent hospital-acquired infections that pose a significant risk to patients, often leading to complications and even death. The incidence of SSIs can vary ...among different hospitals due to various factors that influence their development.
The objective of this study was to examine the occurrence and determine the factors associated with Surgical Site Infections (SSI).
From August 2021 to July 2022, our tertiary care center conducted a retrospective observational study. The surgical sites were carefully assessed and categorized, and infected wounds underwent culture and sensitivity testing. The collected data was then analyzed using SPSS 13 software
: Among the 360 patients studied, 78 (22%) developed surgical site infections (SSI). Risk factors for SSI included age, gender, BMI, diabetes, blood transfusion, and longer preoperative waiting time. Staphylococcus aureus was the predominant pathogen, and resistance to tetracycline was common.
Surgical site infections (SSI) are prevalent, indicating a high incidence. Among the contributing factors, gender, extremes of BMI, diabetes mellitus, and blood transfusion emerge as influential risk factors associated with the occurrence of SSI.
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