The effects of post-deposition annealing conditions on structure and created defects in Zn0.90Co0.10O thin films deposited on Si(100) substrate

We analyze the effect of post-deposition annealing conditions on both the structure and the created defects in Zn0.90Co0.10O thin films deposited on the Si (100) substrates by RF magnetron sputtering technique using home-made targets. We concentrated on understanding the homogeneity of substituted Co+2 ions and the annealing effects on the amount of defects in the ZnO lattice. Orientations of thin films are found to be in the [0002] direction with a surface roughness changing from 67±2 nm to 25.8±0.6 nm by annealing. The Co+2 ion substitutions, changing from 7.5±0.3 % to 8.8±0.3 %, cause to form Zn–O–Co bonds instead of Zn–O–Zn and split the Co2p energy level to Co2p1/2 and Co2p3/2 with 15.67±0.06 eV energy difference. In addition, the defects in the lattice were revealed from the correlations between Zn–O–Co bonds and intensity of Raman peak at around 691 cm-1. Furthermore, the asymmetry changes of O1s peak positions in X-ray Photoelectron Spectra (XPS) were also found to be in accordance with the Raman results

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Karbon İlişkili Malzemeler

This chapter discusses the emergence conditions of energy states arisenfrom the interaction of electromagnetic waves with an optically active planar slab cov-ered by graphene sheets. All energy configurations inside and outside the graphenelayers are explicitly revealed. In particular, we specialize to some certain cases ofmaximal energy storage by imposing the spectral singularity condition, and showthat energy density stored within graphene layers can be increased tremendouslybecause of the presence of graphene layers surrounding the complex potential slab.Method presented here relies on the most fundamental principles embracing itspower from Maxwell’s equations and employing the whole control of transfer matrixformalism of scattering theory. In this respect, various situations are discussed to seehow graphene sheets can be handled in order to increase the energy storage within aslab. It is attained that both graphene layers are required and there must be currentsflowing in the same direction in order to preserve the parity invariance. If the parityinvariance is broken, energy stored inside the slab slumps to much lower values.Besides, it is illustrated that graphene features can be effectively used in order toenhance energy storage efficiently. Predictions proposed in this work are perceptiblysupported by the corresponding graphical demonstrations. The suggested method isquite illustrative and instructive, and give rise to extend all other cases by followingsimilar steps. These observations and predictions suggest a concrete and sound wayof forming graphene-related energy storage device

The magnetization in (Zn1-xCox)Ga2O4 (x=0.05, 0.10, and 0.20) diluted magnetic semiconductors depending on Co atoms in tetrahedral and octahedral sites

The present study describes magnetic interactions in (Zn1-xCox)Ga2O4 (x = 0.05, 0.10, and 0.20) particles dependant on Co atoms in both tetrahedral and octahedral sites. The effects of substituted Co atoms to magnetic character are analyzed using Curie-Weiss law. The ferromagnetic character is found dominant in (Zn1-xCox)Ga2O4 semiconductors for x values lower than 0.10; in addition, a specific hysteresis with 139 +/- 50 Oe coercivity is observed for 5% Co-doped ZnGa2O4. The high Co amount in tetrahedral site increased the number of antiferromagnetic couplings and the hysteresis at 300 K disappeared for (Zn0.80Co0.20)Ga2O4 particles. Furthermore, the Co+3 ions in the octahedral site decreased mu(eff) values, per Co amounts, in the range of 4.89 +/- 0.01 mu(B)/Co to 4.44 +/- 0.02 mu(B)/Co, because of enhancing paramagnetic behaviors

Synthesis of Iron Gallate (FeGa2O4) Nanoparticles by Mechanochemical Method

The study was focused on optimizing the procedure of synthesizing iron gallate (FeGa2O4) nanoparticles by mechanochemical techniques. Due to a lack of information in the literature about the sequence of synthesis procedures of FeGa2O4 structures, the study is based on the establishment of a recipe for FeGa2O4 synthesis using mechanochemical techniques. Rotation speed, grinding media, and milling durations were the optimized parameters. At the end of each step, the structure of the resulting samples was investigated using the X-ray diffraction (XRD) patterns of samples. At the end of the processes, the XRD patterns of the samples milled under an air atmosphere were coherent with the XRD pattern of the FeGa2O4 structure. XRD patterns were analyzed employing Rietveld refinements to determine lattice parameters under the assumption of an inverse spinel crystal formation. Furthermore, a fluctuation at band gap values in the range of 2.39 to 2.55 eV was realized and associated with the excess Fe atoms in the lattice, which settled as defects in the crystal structures

Domain state-dependent magnetic formation of Fe3O4 nanoparticles analyzed via magnetic resonance

Magnetic properties, arising from surface exchange and interparticle interactions of the Fe3O4 (magnetite) nanoparticles, were investigated in the temperature range of 5-300 and 120-300 K using vibrating sample magnetometer technique and electron spin resonance spectroscopy, respectively. The research was based on to figure out the origin of intraparticle interactions and the change of interparticle interactions in wide size range Fe3O4 nanoparticles. The analyses were done for samples having almost same particle size distributions. The average particle sizes were changed in between 30 +/- A 2 and 34 +/- A 2 nm. The observed magnetization values were demonstrated the mixture of single-domain size particles, exhibiting both single-domain (SD) and superparamagnetic (SPM) states. The symmetry of resonance curves changed according to the ratio of SD and SPM-stated particles in mixture under located temperature. The changes of anisotropy up to domain state were understood by freezing magnetic moment in glycerol matrix from room temperature to 120 K under 5-kG field. The shift of H (R) values to higher magnetic fields and the more symmetric resonance spectrum proved the effect of anisotropy and interparticle interactions fields on magnetic behave. In addition, the origin of intra-interaction was exposed from Fe3+ centers and exchange coupling in between Fe2+, Fe3+, and O-, and Fe3+ centers found from g factor (g)

Interparticle interaction effects on magnetic behaviors of hematite (alpha-Fe2O3) nanoparticles

The interparticle magnetic interactions of hematite (alpha-Fe2O3) nanoparticles were investigated by temperature and magnetic field dependent magnetization curves. The synthesis were done in two steps; milling metallic iron (Fe) powders in pure water (H2O), known as mechanical milling technique, and annealing at 600 degrees C. The crystal and molecular structure of prepared samples were determined by X-ray powder diffraction (XRD) spectra and Fourier transform infrared (FTIR) spectra results. The average particle sizes and the size distributions were figured out using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The magnetic behaviors of alpha-Fe2O3 nanoparticles were analyzed with a vibrating sample magnetometer (VSM). As a result of the analysis, it was observed that the prepared alpha-Fe2O3 nanoparticles did not perform a sharp Morin transition (the characteristic transition of alpha-Fe2O3) due to lack of unique particle size distribution. However, the transition can be observed in the wide temperature range as "a continuously transition". Additionally, the effect of interparticle interaction on magnetic behavior was determined from the magnetization versus applied field (sigma(M)) curves for 26 +/- 2 nm particles, dispersed in sodium oxalate matrix under ratios of 200:1, 300:1, 500:1 and 1000:1. The interparticle interaction fields, recorded at 5K to avoid the thermal interactions, were found as similar to 1082 Oe for 26 +/- 2 nm particles. (C) 2011 Elsevier B.V. All rights reserved

Size dependent heating ability of CoFe2O4 nanoparticles in AC magnetic field for magnetic nanofluid hyperthermia

We investigated the size dependent magnetic properties and heating mechanism of spinel CoFe2O4 nanoparticles, which synthesized using the nonhydrolytic thermal decomposition method. The size of CoFe2O4 nanoparticles was arranged with the variation of solvent type, reflux time, and reflux temperature. The optimum size range was determined for magnetic fluid hyperthermia. The particles with 9.9 +/- 0.3 nm average diameter have the highest heating ability in the AC magnetic field having 3.2 kA/m amplitude and 571 kHz frequency. The maximum specific absorption rate of 22 W/g was obtained for 9.9 +/- 0.3 nm sized CoFe2O4 nanoparticles. The calculations and experimental results showed the dominancy of Brownian relaxation at the heat production of synthesized 9.9 +/- 0.3 nm nanoparticles. In contrary, the magneto-heating in 5.4 +/- 0.2 nm particles mainly originated from Neel relaxation

Magnetic behaviour of iron nanoparticles passivated by oxidation

This study is to understand the effect of oxidation, especially magnetically, on iron nanoparticles. According to generation of the oxidated iron nanoparticles, mechanical alloying technique was used and nanosized magnetite (Fe3O4) maghemite (gamma-Fe2O3) and hematite (alpha-Fe2O3) particles were obtained as the resultant samples. The reactance to the thermal treatment was determined by differential thermal analysis and thermogravimetric (DTA-TG) measurements. X-ray powder diffractions (XRD) helped to exhibit the structure of the sample by ICDD cards and to determine the size of nanoparticles by using the Scherrer formula. On the other hand, VSM (vibrating sample magnetometer) measurements were determined to understand the magnetic behaviour. Through the transformation of Fe3O4 to other iron-oxides, two exothermic peaks were observed at around 169.11 degrees C and 562.61 degrees C by DTA analysis. Beside of this, the experimental results demonstrate the effects of mechanical milling parameters, atmosphere and lubricant, to the structure and to the size of the resultant particles and the change of magnetic behavior of the iron-oxide and iron nanoparticles when they approach to superparamagnetic region, especially in single domain region