Hc Values Research Articles

Magnetic and structural characteristics of self-assembly Co-Ni-Zn ternary nanocrystals

With respect to the rapid growth of high-performance applications for magneto-electric alloys, extensive attempts have been made to develop the electroplating of nanocrystalline magnets coatings within high coercivity and excellent corrosion resistance. Herein we proposed a low-cost and practical electroplating of the substitution of Zn2 + ions in Ni-Co bath for the ternary Ni-Co-Zn soft-magnetic alloys. Anomalous co-deposition of Ni0.12Co0.88-xZnx (x = 0–0.36) alloys were aligned from sulfamate electrolytes within L-ascorbic acid (H2Asc) as complexant, in which the ratio (x) of atomic molar was regulated by dropping ZnCl2 concentrated solution based on Nernst theory and Cyclic-Voltammetry (CV) tests. Results validated that it yielded crystal growth within a narrow size of 150–250 nm, allowing the structural recombination of the spider-web-like ZnO tangled with Ni-Co nanocrystals. In addition to the enhanced corrosion behavior of the ternary Ni-Co-Zn alloys compared to binary Ni-Co, it was attributed to the coexistence of γ-Ni5Zn21 phase and [Zn(OH)4]2- colloidal-like corrosion products. More impressively, it depicted high coercivity (Hc) of ∼15.3 Oe and superior saturation magnetization (Ms) of ∼153.2 emu/g from VSM tests for Ni0.12Co0.64Zn0.24 (x = 0.24), which was due to the self-assembly of ZnO-rich dispersoids twined around GB regions to be magnetic isolation and restrict the movement of domain walls for higher coercivity. Especially for the sample (x = 0.24) after aged at 450 °C for 2 h, it achieved a superior Hc value of 45.8 Oe that was 3 times higher than those without ageing, which was correlated well with large internal stresses by the disordered stacking among hetero-atoms. So the integrated Ni-Co-Zn ternary soft magnets offered a promising approach to achieving high coercivity with excellent anti-corrosive properties, satisfying the stringent requirements of potential applications used in magnetic memory devices, etc.

Enhanced photodegradation of CuCo2O4 nanoflower for the dye degradation of Rhodamine B and Methyl Violet

The investigation examined into the effect of different hydrothermal reaction temperatures and durations on the formation of nanoflower-shaped CuCo2O4 nanostructures (CCO NPs). The structural, morphological, functional, optical, and magnetic properties of the synthesized CCO NPs were thoroughly examined. The optimal calcination temperature was determined using Thermogravimetric and Differential Thermal Analysis (TG/DTA), which identified 400 °C as the ideal temperature. Following X-ray Diffraction (XRD) analysis, pure CuCo2O4 samples were formed, with calculated average crystallite sizes of 27 nm for CCO-A, 48 nm for CCO-B, 30 nm for CCO-C, and 31 nm for CCO-D samples. Fourier Transform Infrared (FTIR) analysis provided additional confirmation of pure CuCo2O4 formation, with characteristic bands in the 665–662 cm-1 and 583–567 cm-1 ranges indicating the presence of CuO and CoO bonds. SEM, High-Resolution SEM (HRSEM) and High-Resolution Transmission Electron Microscopy (HRTEM) all supported the observation of a distinct flower-like structural morphology. The optical properties of an optimized sample were revealed by UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS) analysis, which revealed a band gap of 3.3 eV. According to Vibrating Sample Magnetometer (VSM) results, the magnetic behavior of CCO-D nanostructures at room temperature exhibited paramagnetic characteristics. The saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) values were determined to be 0.26218 emu/g, 2.7214 × 10–3 emu/g and 29.787 Oe, respectively. To evaluate photocatalytic performance, the CCO-D photocatalyst was used to degrade Methyl Violet and Rhodamine B dyes. CCO-D degraded MV dye with greater efficiency (93%) than RhB (85%) when exposed to sunlight. These findings highlight CCO-D's potential as a photocatalyst for the degradation of organic dyes.

In silico prediction of maximum perineal muscle strain during vaginal delivery by design of experiment

Background and objectiveThe prevalence of pelvic floor muscle injuries induced by childbirth is higher than 23 % in the general women population. Such injuries can lead to prolapses and other pathologies in future female life. Leveraging computational biomechanics, the study implements an advanced female pelvic floor model for computing the maximum pelvic muscle strain, which serves as an injury risk indicator. The design of experiment method, abbreviated as DoE, is used to compute the maximum strain for boundary values of bony pelvis dimensions, namely the anterior-posterior diameter (abbreviated as APD) and the transverse diameter (abbreviated as TD). This is done in combination with small, medium and large percentiles of fetal head circumference (abbreviated as HC). MethodsWe utilized a previously developed finite element model of a female pelvic floor, as a reference, and enhanced it with new features, including a more detailed tissue geometry and advanced constitutive material models. The APD and TD dimensions were sourced from the set of MRI of 64 nulliparous women. This data was used to estimate the boundary dimensions of the female bony pelvis, combining both small and large values of APD and TD. Together with the 10th and the 95th percentiles for HC, a three-dimensional domain was constructed to assess the maximum pelvic muscle strain. In boundary cases, the maximum pelvic muscle strain was computed across 8 full-factorial design models (each situated at one corner of the domain, thereby combining the minimum and the maximum values of APD, TD and HC). This was done to define a response surface that predicts the maximum pelvic muscle strain within the domain. The accuracy of this response surface prediction was validated using 15 additional intermediate design models. These models were placed at the center of the domain (1 point), the centres of the domain boundary surfaces (6 points), and midway along each domain boundary edge (8 points). ResultsThe maximum strain results for 8 combinations of APD, TD, and HC were employed to construct a linear response surface as a function of APD, TD, and HC. Tests at an additional 19 domain points served to evaluate the efficiency of the response surface prediction. The response surface demonstrated strong predictability, with an absolute average error of 1.52 %, an absolute median error of 1.52 %, and an absolute maximum error of 11.11 %. HC emerged as the most influencing dimension, accounting for 16 % of influence. ConclusionsThe reference finite element pelvic floor model was scaled to 8 full-factorial female-specific pelvic floor models, which represent the combination of boundary values for APD, TD, and HC. The maximum pelvic floor muscle strain from these 8 models was used to design a response surface. When implementing the DoE approach to construct the response, there was consistent predictability for the maximum perineal muscle strain, as validated by the additional 19 intermediate design models. As a result, the response surface methodology can serve as an initial predictor for potential childbirth-induced pelvic floor muscle injury.

Upper Critical Field and Tunneling Spectroscopy of Underdoped Na(Fe,Co)As Single Crystals.

A comprehensive study of superconducting properties of underdoped NaFe0.979Co0.021As single crystals by a combination of upper critical field measurements and incoherent multiple Andreev reflection effect (IMARE) spectroscopy is presented. The Hc2(T) temperature dependences are measured at magnetic fields up to 16 T with in-plane and out-of-plane field directions and considered within single-band and two-band models in order to estimate the Hc2(0) value. In IMARE spectroscopy probes, the magnitude, characteristic ratio, and temperature dependence of the superconducting order parameters (ΔL,S(T)) are determined locally and directly. A possible k-space anisotropy of the large superconducting gap is demonstrated. We show that usage of a quadruple of λij0 coupling constants obtained in the IMARE experiment can significantly reduce the number of free parameters required to fit the Hc2(T) dependence within a two-band approach (from six to two).

Effect of low sintering temperature on the structural and magnetic properties of M-type strontium hexaferrite

A pure M-type strontium hexaferrite with nominal composition SrFe12O19 has been prepared via the modified conventional citrate precursor method.The entirework emphasizes on improvingthe standardof hexagonal ferrite without undergoing high-temperature thermal treatments. By incorporating some adjustments in processing conditions, the prepared sampleis sintered at 800 °C and 910 °C, identified through thermalgravimetric analysis(TGA/DTA). The impact of the low-temperature sintering process on structural, spectroscopic, and magnetic properties are investigated via using different characterization techniques like XRD, FESEM, FTIR, Raman spectroscopy (RS), and VSM respectively. The XRD confirmed the formation of the M-phasealong withsome impurities of Fe2O3 and these results are strongly supported via both FTIR and RS. Similarly, FESEM analysis confirmed the formation of densely packed grains some hexagonal platelets. The magnetic properties of SrM hexaferrites show the increment of saturation magnetization Ms from 81 emu/g to 92 emu/g as the sintering temperature increases from 800 °C to 910 °C. Apart from the higher Ms for SrM hexaferrite, the Hc values 107 Oe and 262 Oe respectively are the vital findings of this research. This rare nature of SrM hexaferrite signifies the erection of soft character in hard SrM hexaferrites. Moreover the abrupt increase in the squarenes ratio (SQR) from 0.26 to 0.54 represents the transformation from multidomains to single domain. Material with such properties can be utilized in switching devices, recording media, high frequency applications.

Investigation of the effects of Cu layer thickness and annealing temperature under air atmosphere on the properties of Co/Cu multilayer films

In this study, the suitability of Co/Cu multilayer films with different physical conditions (varying thickness values and systematic annealing processes) in magnetic technology applications is discussed. Co/Cu films were deposited by the sputtering technique. The effects of different thicknesses of non-magnetic (Cu) layers and annealing temperature on magneto-structural properties were investigated. Different thicknesses of Cu layers were determined as 34 nm, 10 nm, 4 nm. Additionally, two annealed situations were considered to investigate the annealing effect. While the first one is exposing the films to 80 °C and 130 °C for 240 s, second one is annealing the films at 180 °C for different exposure times (50 s and 150 s). All films that have different thicknesses of Cu layers crystallized in (111) plane of the face centered cubic (fcc) structure. The intensity of this peak increased with increasing Cu layers thickness. Variation in the thickness of Cu layers has an important effect on the film surface. Saturation magnetization (Ms), coercivity (Hc) and squareness (Mr/Ms, Mr: remanent magnetization) were considerably affected by variation of the Cu content and film surface caused by the change in the thickness of the Cu layers. The film with 4 nm Cu layer thickness has the highest Ms, lowest Hc values and high Mr/Ms ratio. This indicates magnetically high efficient compared to the other films in the same series. The fcc structure continued to exist for the films annealed at 80 °C and 130 °C for 240 s. It was found that the annealing procedure transfigured the film surface and the differences in Ms and Hc values can be mostly attributed to this transfiguration because of the same film content revealed. An increase in Ms value, and a slight decrease in Hc and Mr/Ms values were detected for the annealed film at 130 °C, compared to the film annealed at 80 °C. It was also seen that the film structure was damaged at 180 °C because of excessive heat transfer.

FeTiB nanocrystalline films: Static and dynamic magnetic properties in accordance with phase composition and magnetic structure

Nanocrystalline Fe100–56.8Ti0–13.5B0–34.2 films 1.4 µm thick are prepared by dc magnetron deposition on glass substrates. The structure and magnetic properties of the films are comprehensively characterized and analyzed. The lattice parameter and the grain size of the bcc Fe-based phase (2-25 nm), parameters of the stochastic magnetic structure (the relative size and the effective anisotropy field of stochastic domains D1/2<Ha> and the local magnetic anisotropy field at the grain scale), saturation magnetization Ms, coercive field Hc, static permeability mst, and ferromagnetic resonance frequency fr of the films are quantitatively estimated and their interrelations are studied. As Ti and B contents increase, the phase composition of the films changes in accordance with the sequence αFe - αFe(Ti) - αFe(Ti) + TiB2 - amorphous, wherein Ms decreases from 2.1 to 0.3 T. The Hc values vary in the interval 7–70 Oe determined by the D1/2 <Ha> field or by other magnetic anisotropy sources. The μst values vary in the interval 20–140. The μst values obtained by the Lorentzian dispersion law adequately fall within the range of the calculated permeabilities, which is limited by the coercive field obtained from the hysteresis loops and the anisotropy field determined by Kittel equation. The μst values of the films are kept up to the frequencies of at least 1.5 GHz. The frequency dependences of the permeability of the films are analyzed taking into account the influence of skin effect and are considered in terms of Acher’s law. The obtained values of the Acher’s constant (less than 0.3) indicate the possibility of reaching the higher values of μst and fr at the expense of elimination of the perpendicular anisotropy, in particular, via the formation of thinner films as compared to the films under study (1.4 µm thick). According to the available literature data, the presented investigations, using the FeTiB films as an example, were performed for the first time.

Effect of complete suppression of androstenedione on auxological development in prepubertal patients with classical congenital adrenal hyperplasia.

Children with classical congenital adrenal hyperplasia (CAH) require glucocorticoid (GC) substitution due to impaired cortisol synthesis. To avoid over- or undertreatment, one has to consider auxology as well as biochemical parameters for adrenal derived steroids like androstenedione (A4) and 17-hydroxyprogesterone (17-OHP). There are no established reference values for A4 and 17-OHP in CAH. We performed a retrospective study in 53 prepubertal patients with CAH. Datasets of patients were included if the plasma A4 values of the respective clinical visit were under the limit of quantification. Related 17-OHP values were extracted as well as height/length, weight, dose of hydrocortisone, HC regimen, bone age and stages of pubertal development. Median hydrocortisone doses were in most observations within the recommended reference ranges. Hydrocortisone has a significant negative influence on 17-OHP values and HSDS. Age has a positive significant influence on 17-OHP, BMI-SDS, and HSDS. Median height standard-deviation-score (HSDS) was beneath 0 at all times, but showed an increasing trend in both sexes. Median body mass index standard-deviation-score (BMI-SDS) was above 0 at all times and showed an increasing trend as well. With guideline-compliant doses of hydrocortisone, suppression of A4 at the respective time of day is possible in prepubertal children. Although HC has a significant negative influence on HSDS, increasing values for HSDS and HC are observed with increasing age. Thus, A4 suppression at the respective time point does not hinder regular growth. An increase in body mass index can already be observed as early as in prepuberty.

CuS/SnS quantum dot-nanorod composites: Ferromagnetic and gigantic dielectric characteristics

In this study, new CuS/SnS nanocomposites were simply synthesized by coprecipitation route for capacitive energy storage applications. The results of the XRD analysis confirmed the formation of hexagonal CuS and orthorhombic α-SnS phases. The TEM images of CuS/SnS (1:1) and CuS/SnS (1:3) composites showed the formation of quantum dot particles (2–3 nm) besides nanorods particles (length 56–80 nm and diameter 9–16 nm). The TEM images of CuS/SnS (3:1) sample illustrated the formation of only quantum dot particles (2–3 nm). Infrared band gap energies of 0.8, 0.95 and 1.25 eV were measured for CuS/SnS (1:1), CuS/SnS (3:1) and CuS/SnS (1:3) composites, respectively. CuS/SnS (1:1) composite has a wide hysteresis loop until magnetic field of ±3500 Oe with magnetization (Ms) and coercivity (Hc) values of 0.009 emu/g and 1000 Oe, respectively. For CuS/SnS (1:3) composite, the hysteresis loop possesses a semi-ferromagnetic shape with measured magnetization value of 0.018 emu/g and Hc of 551 Oe. The ferromagnetic order can be attributed to defects as well as the surface interface interaction between CuS and SnS particles. Remarkably, CuS/SnS composites exhibit a giant dielectric constant (>106) with low temperature dependent, making them promising compositions for capacitive energy storage applications. At room temperature, CuS/SnS (1:1), CuS/SnS (3:1) and CuS/SnS (1:3) composites possess colossal dielectric constant values of ∼2.9 × 106, 5.5 × 105 and 6.3 × 106 at frequency of 42 Hz, respectively.

Experimental investigation of the effect of fuel oil, graphene and HHO gas addition to diesel fuel on engine performance and exhaust emissions in a diesel engine

Today, research for alternative fuels continues due to the increasing energy demand, exhaust emission restrictions, and depletion of fossil fuels. It is important to use diesel engines for the opening of new oil fields in Turkey and for the utilization of fuel oil to be produced in these oil fields. In this study, pure diesel (D) diesel 60% and fuel oil 40% (DF40) were supplied by volume with an ultrasonic mixer. 50 (DF4050 N) and 100 ppm (DF40100 N) graphene have been added to eliminate fuel oil's adverse combustion effects by keeping the fuel oil constant. In addition, HHO gas was added to improve the combustion even more with a flow rate of 5 (DF4050N5H and DF40100N5H) and 10 (DF4050N10H and DF40100N10H) lt/min into the intake manifold by using the HHO generator. Experiments were carried out at 3000 RPM constant speed at 3.2, 6.4, 7.9, and 12.8 Nm engine torque without any modification on the diesel engine. The effects of these mixtures on combustion performance and exhaust emissions were investigated. Exhaust gas temperature and emissions were measured in the experiments. According to the measurements, thermal efficiency, brake specific energy consumption (BSEC), HC, CO, CO2, particle emission, and NOx emission values are given. Brake specific energy consumption (BSEC), CO, HC, and particle emissions decreased, and thermal efficiency, NOx, CO2, and exhaust gas temperature increased with the engine torque value increased as a result of the experiments. Thermal efficiency and CO2 emission decreased, and BSEC, exhaust gas temperature, HC, CO, NOx, and particulate emissions increased by adding fuel oil to diesel fuel. The thermal efficiency was increased by adding graphene and HHO gas from the intake manifold to DF40 fuel. The thermal efficiency improved, and emissions decreased with the more addition of graphene and HHO gas. Adding HHO gas improved thermal efficiency significantly at the 12.8 Nm engine load. With the addition of graphene and HHO gas to DF40 fuel, the BSEC value was improved at high torque values. The effect of improving thermal efficiency is also understood from the decrease in CO emissions and the increase in CO2 emissions. HC and PM emissions decreased with the addition of graphene and HHO gas. It was observed that NOx and exhaust gas temperature increased with increasing thermal efficiency.

INVESTIGATION OF MAGNETIC HYSTERESIS PROPERTIES OF ISOTROPIC MAGNETICALLY HARD ALLOYS OF THE Fe-Cr-Co SYSTEM ALLOYED WITH TUNGSTEN

Hard magnetic alloys Fe-30Cr-20Co (wt.%) alloyed with tungsten in an amount of up to 3 wt.% were obtained by powder metallurgy. A study of magnetic properties showed that tungsten additions increase the values of the coercivity Hc and the maximum energy product (BH)max, but at the same time reduce the residual induction Br. This effect increases with increasing tungsten content in the material. The maximum values of Hc (55.8 kA/m) and (BH)max (17.2 kJ/m3) are observed in the alloy alloyed with 3 wt.% W. At the same time, the alloys studied in the work turned out to be sensitive to thermal conditions processing. According to X-ray phase analysis, after a full processing cycle, alloys contain a noticeable proportion of non-magnetic ɣ-phase, but the magnetic properties correspond to the level of cast analogues. During compression tests, all samples of tungsten alloyed alloys failed before reaching a deformation rate of 20%, while the unalloyed Fe-30Cr-20Co (wt.%) alloy deformed without failure under these conditions. Thus, tungsten additives reduce the ductility of the material.

THE EFFECT OF VARIATION OF TYPES OF SPARK PLUGS AND MIXTURE OF 90 OCTANE FUEL WITH METHANOL ON 110 CC MOTOR PERFORMANCE

Methanol (CH3OH) is an alcoholic compound that can be used as an alternative fuel. The high oxygen content in methanol allows for complete combustion and is combined with experiments using various types of spark plugs which is expected with a strong spark burning the fuel and air mixture so that the effect on performance increases. The research was carried out using an experimental method, namely by conducting various experiments using different types of spark plugs, namely nickel spark plugs, platinum spark plugs, iridium spark plugs and variations of 90 octane fuel mixtures with methanol ratios of 0%, 5%, 10% on performance with gas emission measurement criteria. throw away. The results of this study indicate that there is an effect of using 90 octane fuel on exhaust emissions, where the use of platinum spark plugs has the lowest CO value at 4500 rpm with a CO emission value of 2.20%, while the lowest HC value is at 4000 rpm of 1.90 ppm using iridium spark plugs

A study of crystallization behavior and magnetic property of Co-based alloy

The crystallization behavior and magnetic properties of Co-based alloy are investigated by DSC, XRD, TEM, VSM, and impedance analyzer. The results indicate that the non-isothermal crystallization of Co50Fe25Nb15B10 alloy has a significant glass transition with a supercooled liquid region of about 80 K. When the heat treatment is above crystallization temperature, some phases appear successively as the Co2B and (Co, Fe)21Nb2B6, and with the increase of annealing temperature, the values of coercivity Hc and saturation magnetic induction strength Bs increase correspondingly. After measuring the impedance effect of the Co-based alloy, it is found that the increase in impedance value is attributed to the decrease in magnetic anisotropy performance of the alloy, and the impedance curves of both amorphous and nanocrystalline alloys show a similar single peak trend. However, the crystallization phases after annealing form with a large size that hind the magnetization process resulting in a significant decrease of (ΔZ/Z)max value.

Enhanced magnetic hyperthermia efficiency in poly vinyl alcohol-coated zinc-substituted cobalt ferrite nanoparticles: Correlated effects of zinc content and applied magnetic field strength

Finding the interrelation among the magnetic response of the heat mediators to an alternating magnetic field (AMF) and other relevant parameters in magnetic hyperthermia therapy (MHT) can give the possibility to accurately design high-performance nanostructured magnetic nanoparticles (MNPs). In this context, the present work investigates the effect of the zinc substitution on magnetic properties and heat-generating ability of poly vinyl alcohol-coated Zn-substituted cobalt ferrite nanoparticles (PZC NPs) with different zinc contents (ZnxCo1−xFe2O4; x = 0, 0.15, 0.3, 0.4, 0.5, 0.7), synthesized using hydrothermal-assisted co-precipitation method. The obtained results showed that the PZC NPs with an average particle size ∼ 15 nm exhibit ferrimagnetic features and their coercivity (Hc) values decrease as the zinc content (x) increases. Moreover, as Zn2+ replaces Co2+ in the structure, saturation magnetization (Ms) increases up to about 52 emu/g for PZC-30 NPs (x =0.3) and then decreases for higher Zn contents. The hyperthermia measurements were performed at a fixed filed frequency (f=120kHz) and different magnetic field strengths (Happl=17,20,24.5kA/m). The results revealed that, as x increases, specific absorption rate (SAR) at each Happl first shows an increasing trend and then reaching a maximum value (at x=0.4) follows a decreasing trend. Moreover, the highest SAR (25.25 W/g) belongs to the magnetic fluid containing PZC-40 NPs at Happl=24.5kA/m. Furthermore, the Happl-dependency of the SAR values were obtained as a power law (SAR∼Happln) in which the exponent n rises as x decreases, suggesting that the optimal composition tends to shift to ones with the lower x at higher Happl. The obtained results, revealing the high impact of the interrelation between the chemical composition and the Happl on the MNPs heating efficiency, can shed more light on the way to design heat mediators with optimal performance through simultaneous control of the chemical composition and the Happl.

The Effect Of The Addition of Copper DB Killer On Yamaha Vixion 150cc Motorcycle on Exhaust Emissions

The addition of racing exhaust to a vehicle will greatly affect the quality of exhaust emissions. Racing exhausts that use the FreeFlow system which throws the remaining combustion gases out immediately without any deflection and catalyst in the racing exhaust. The addition of DB Killer uses nest-shaped copper material, besides reducing noise it also reduces excessive emissions and the material is easy to obtain, inexpensive, and has a simple manufacturing process. The advantage of DB Killer is that using a nest model copper plate catalyst material significantly reduces emissions compared to not using DB Killer. The DB Killer is installed at the end of a racing exhaust silencer and tested at different RPMs of 3500, 4500 and 5500. Tested using a gas analyzer to obtain CO, HC and CO2 values ​​for racing exhaust emissions without DB Killer and using a copper DB Killer. Obtaining the results of reducing exhaust emissions is much better and produces less noise. The result is a lower exhaust emission value because there is a DB Killer made of copper at the end of the exhaust silencer which can withstand emissions in the DB Killer which has a hollow design.

Influence of energy density on the microstructure, growth orientation, and anisotropy of magnetic properties in additively manufactured Fe-3.8wt%Si transformer steels

Fe-3.8wt%Si transformer steels were processed using two different additive manufacturing (AM) techniques, laser powder bed fusion (LPBF) and directed energy deposition (DED). While the LPBF processed samples exhibited a strong <001> orientation of the BCC grains along the build axis, the DED processed samples exhibited a randomized texture along the build axis. DED processed samples showed substantially coarser columnar grains as compared to their LPBF counterparts. The columnar grains exhibited a substantial number of low-angle sub-grain boundaries. All samples exhibited very good soft magnetic properties, with saturation magnetization (Ms) values ranging from 205 - 232 emu/gm, and coercivity (Hc) values ranging from 1.2 – 4.2 Oe. The Coercivity (Hc) values were significantly lower when the magnetic field was applied parallel to the build axis, as compared to being perpendicular, which can be rationalized based on the columnar nature of the grains, resulting in a higher number density of grain boundaries in case of the field applied perpendicular to the build axis.

Sol-Gel synthesis of Ni-doped Zn-based spinel nanoferrites with structural and dielectric characterizations along with magnetic analysis

Ni-doped zinc ferrites (NixZn1−xFe2O4, 0.00 ≤ x ≤ 0.20 in steps of 0.05) were successfully synthesized using a sol-gel self-combustion method. The addition of nickel was aimed at modifying the high-frequency dielectric and magnetic properties of zinc ferrites. Various characterizations, including XRD, FTIR, LCR, and VSM analyses, were conducted to examine the crystal structure, absorption bands, dielectric properties, and magnetic properties of the compounds. XRD patterns revealed a monophasic cubic spinel structure with a preferred (311) plane orientation. The incorporation of Ni resulted in an increased crystallite size as determined by the Scherrer equation and Williamson-Hall method. The lattice parameters and unit cell volume decreased, while X-ray density increased. FTIR transmittance spectra confirmed absorption bands associated with tetrahedral and octahedral bonding. Dielectric parameters were studied across a frequency range of 1 MHz to 3 GHz, with the Maxwell-Wagner model used to explain the observations. Both components of the complex dielectric constant decreased with increasing frequency, indicating normal dispersion behavior of spinel ferrites. The electric modulus revealed relaxation mechanisms, while AC conductivity demonstrated conduction mechanisms. Magnetic properties were characterized using M-H loops measured via VSM. Increasing the Ni concentration led to higher saturation magnetization (Ms), magnetic remanence (Mr), and coercivity (Hc). Magnetic moments and anisotropy constants were calculated based on observed values of Ms and Hc. In summary, the nickel-doped zinc ferrites exhibited notable structural, magnetic, and dielectric properties, suggesting their potential utility in microwave and high-storage magnetic devices.

Analisis Pengaruh Penambahan Octane Booster Dengan Bahan Bakar Pertalite Terhadap Emisi Gas Buang

Vehicles are the main thing in supporting daily activities. Currently, motorized vehicles are a necessity for the community. This increase in vehicle volume leads to an increase in air pollution due to exhaust emissions. The use of low-octane fuel will affect emissions and overall motor performance. One way to increase octane number is to give octane booster. This research was conducted to see the impact of adding octane booster on exhaust emissions. Exhaust emission tests are carried out to see the value of CO, CO2 and HC. In its implementation, the author uses a Megapro PGM-FI motorcycle with 150 cc. The test results resulted in the lowest CO content of 0.19% in pure pertalite fuel, the lowest CO2 of 3.10% in the addition of 3 ml octane booster, and the lowest HC of 213 ppm in the addition of 7 ml octane booster. While the highest CO content was 0.23% in the addition of 7 ml octane booster, the highest CO2 of 3.10% in the addition of 7 ml octane booster and in pure pertalite fuel, and the highest HC of 247 ppm in pure pertalite fuel.

Numerical Investigation of a Reactivity-Controlled Compression Ignition Engine Fueled with N-Heptane and Iso-Octane

In this numerical study, the effects of the premixed ratio, intake manifold pressure and intake air temperature on a four-cylinder, four-stroke, direct injection, low-compression-ratio gasoline engine, operated in reactivity-controlled compression ignition (RCCI) combustion mode at a constant engine speed of 1000 rpm, were investigated using Converge CFD software. The results of numerical analyses showed that the maximum in-cylinder pressure and heat release rate (HRR) increased and the combustion phase advanced depending on the rise in both intake manifold pressure and intake air temperature. The CA50 shifted by 18.5 °CA with an increment in the intake air temperature from 60 °C to 100 °C. It was observed that the combustion duration dropped from 44 °CA to 38 °CA upon boosting the intake manifold pressure from 103 kPa to 140 kPa. Moreover, a delay in the combustion phase occurred at a constant intake air temperature with an increasing premixed ratio. The maximum value of in-cylinder pressure was recorded as 36.15 bar (at 11 °CA aTDC) with the use of PRF20. Additionally, as the content of iso-octane in the fuel mixture was increased, combustion delay occurred, and the maximum value of in-cylinder temperature obtained was 11 °CA aTDC using PRF20 fuel at the earliest point. While HC and CO emissions reached the highest values at a 60 °C intake air temperature, NOx and soot emission values were detected at quite low levels at this temperature. The values of all these emissions increased with rising intake manifold pressure and reached their highest values at 140 kPa. In addition, while the highest HC and CO emission values were observed with the use of PRF60 fuel, the results revealed that the control of the combustion phase in the RCCI strategy is notably affected by the premixed ratio, intake manifold pressure and intake air temperature.

The influence of thermal barrier coating (TBC) on diesel engine performance powered by using Mimusops elengi methyl ester with TiO2 nanoadditive

This current exploration aims for enhancing engine performance by using Mimusops elengi methyl ester 20% and 80% diesel with 25 ppm TiO2 [MEME20 + 25 ppm of titanium oxide] nanoparticle additive for the low heat rejection (LHR) engine. The coating of the piston crown was made with an insulation of two layers, initially, bond coat of nickel chromium aluminium yttrium (NiCrAlY) 50 µm and a topcoat 250 µm (5% yttrium + 2% neodymium oxide + 93% zirconium oxide) using the plasma spray coating technique. In comparison to diesel, the engine performance with MEME 20 + 25 ppm of titanium oxide resulted in enhancement in brake thermal efficiency (BTE) of 7.06% and a decrease in brake specific fuel consumption (BSFC) of 16.38%. The CO, HC and smoke values were curtailed by 35.66%, 31.8% and 19.66%, respectively, equated with diesel fuel. The NO x and EGT were increased by 22.23% and 9.33%, respectively, with full load at 1500 rpm.