Milled Samples Research Articles

Tuning Optical Properties of Graphene Oxide under Compressive Strain Using Wet Ball Milling Method

We report on the effect of compressive stress on the optical properties of graphene oxide using a wet ball milling technique. For this purpose, graphene oxide was prepared using the modified Hummer’s method and subsequently processed with wet ball milling. X-ray diffraction infers a peak at 9.655° which is the allowed reflection for the graphene oxide. The Williamson-Hall method is used to quantify the strain on the 10 hrs and 20 hrs ball milled graphene oxide samples and is found to be 4.2% and 4.8% respectively. Although we applied strain on the graphene oxide, it actually helped to reduce the defects which are confirmed by the intensity drop-off of D-peak in Raman spectroscopy. Indeed there exists a band gap alteration of 0.14 eV for an applied compressive strain of ~4.8%, hinting that the reduction in oxygen functional groups and the same is confirmed with the Fourier Transform Infrared Spectroscopy (FTIR). The present results would be helpful in developing graphene oxide based flexible memories and optoelectronic devices.

Nutrient Composition, Amylose Content and Pasting Characteristics of Some Elite Accessions of Nerica Rice

Eighteen elite lines of Nerica rice were assessed for proximate, amino acid composition, amylose content and pasting viscosity. The aim was to nominate the lines for further multilocational yield trails and eventual release as varieties. The lines were parboiled by soaking in hot water (75oC) for 9-20hrs and then steamed for 40-45minutes at75oC in a steamer. Raw and parboiled samples were dehusked and polished and used in subsequent evaluations. The results indicated that protein varied from7.47+0.21to 11.73+0.15% parboiled samples and from 6.87+ 1.01to 11.65+ 0.51% for the unparboiled or raw samples. Fat also varied from 5.57+ 4.22- 6.00+ 0.54 the parboiled samples and from 5.33 to 6.33+ 0.5% for the unparboiled samples. The amino acid profile showed that both parboiled and unparboiled samples met the Food and Agricultural Organization (FAO) requirements for infants, adolescent and adults for histidine, threonine, valine and isoleucine and leucine. Both samples and the check were however deficient in lysine (4.01-4.60). Parboiling did not significantly (p<0.5) improve the proximate and amino acids composition of samples. The unparboiled milled samples had higher amylose content (23.84 – 50.85%) compared to(12.85 – 31.81%) of the parboiled samples. The amylose content of the parboiled samples placed them in the intermediate amylose category. The pasting properties showed that raw samples exhibited conventional non-waxy cereal pasting characteristics while the parboiled samples indicated destructuring in the pasting profile. The results were indicative that the NERICA LINES would have high cooking qualities.

Carbon-Substituted Hematite and Magnetite Nanoparticles

ABSTRACTGraphite-doped hematite and magnetite nanoparticles systems (∼50 nm) were prepared by mechanochemical activation for milling times ranging from 2 to 12 hours. Their structural and magnetic properties were studied by 57Fe Mössbauer spectroscopy. The spectra corresponding to the hematite milled samples were analyzed by considering two sextets, corresponding to the incorporation of carbon atoms into the iron oxide structure. For ball milling time of 12 hours a quadrupole split doublet has been added, representing the contribution of ultrafine particles. The Mössbauer spectra of graphite-doped magnetite were resolved considering a sextet and a magnetic hyperfine field distribution, corresponding to the tetrahedral and octahedral sublattices of magnetite, respectively. A quadrupole split doublet was incorporated in the fitting of the 12-hour milled sample. The recoilless fraction for all samples was determined using our previously developed dual absorber method. It was found that the recoilless fraction of the graphite-doped hematite nanoparticles decreases as function of ball milling time. The f factor of graphite-containing magnetite nanoparticles for the tetrahedral sites stays constant, while that of the octahedral sublattice decreases as function of ball milling time. These findings reinforce the idea that carbon atoms exhibit preference for the octahedral sites of magnetite.

Mössbauer Study of Graphite-Containing Iron Oxide Nanoparticles

Graphite-doped hematite and magnetite nanoparticles systems (~50 nm) were prepared by mechanochemical activation for milling times ranging from 2 to 12 hours. Their structural and magnetic properties were studied by 57Fe Mossbauer spectroscopy. The spectra corresponding to the hematite milled samples were analyzed by considering two sextets, corresponding to the incorporation of carbon atoms into the iron oxide structure. For ball-milling time of 12 hours a quadrupole split doublet has been added, representing the contribution of ultrafine particles. The Mossbauer spectra of graphite-doped magnetite were resolved considering a sextet and a magnetic hyperfine field distribution, corresponding to the tetrahedral and octahedral sublattices of magnetite, respectively. A quadrupole split doublet was incorporated in the fitting of the 12-hour milled sample. The recoilless fraction for all samples was determined using our previously developed dual absorber method. It was found that the recoilless fraction of the graphite-doped hematite nanoparticles decreases as function of ball-milling time. The f factor of graphite-containing magnetite nanoparticles for the tetrahedral sites stays constant, while that of the octahedral sublattice decreases as function of ball-milling time. These findings reinforce the idea that carbon atoms exhibit preference for the octahedral sites of magnetite.

Nanocrystalline/nanosized manganese substituted nickel ferrites – Ni1−xMnxFe2O4 obtained by ceramic-mechanical milling route

Manganese substituted nickel ferrites, Ni1−xMnxFe2O4 (x=0, 0.3, 0.5 and 0.7) have been obtained by a combined method, heat treatment and subsequent mechanical milling. The samples were characterised by X-ray diffraction, differential scanning calorimetry and magnetic measurements. The increase of the Mn2+ cations amount into the spinel structure leads to a significant expansion of the cubic spinel structure lattice parameter. The crystallite size decreases with increasing milling time up to 120min, more rapidly for the nickel–manganese ferrites with a large amount of Mn2+ cations (x=0.7). After only 15min of milling the mean crystallites size is less than 25nm for all synthesised ferrites. The Néel temperature decreases by increasing Mn2+ cation amount from 585°C for x=0 up to 380°C for x=0.7. The magnetisation of the ferrite increases by introducing more manganese cations into the spinel structure. The magnetisation of the milled samples decreases by increasing milling time for each ratio among Ni and Mn cations and tends to be difficult to saturate, a behaviour assigned to the spin canted effect.

고에너지 볼 밀링이 Skutterudite계 CoSb&lt;sub&gt;3&lt;/sub&gt;의 열전 및 전하 전송 특성에 미치는 영향

In this study, we investigate the effect of high-energy ball milling on thermoelectric transport properties in double-filled <TEX>$CoSb_3$</TEX> skutterudite (<TEX>$In_{0.2}Yb_{0.1}Co_4Sb_{12}$</TEX>). <TEX>$In_{0.2}Yb_{0.1}Co_4Sb_{12}$</TEX> powders are milled using high-energy ball milling for different periods of time (0, 5, 10, and 20 min), and the milled powders are consolidated into bulk samples by spark plasma sintering. Microstructure analysis shows that the high-energy ball milled bulk samples are composed of nano- and micro-grains. Because the filling fractions are reduced in the bulk samples due to the kinetic energy of the high-energy ball milling, the carrier concentration of the bulk samples decreases with the ball milling time. Furthermore, the mobility of the bulk samples also decreases with the ball milling time due to enhanced grain boundary scattering of electrons. Reduction of electrical conductivity by ball milling has a decisive effect on thermoelectric transport in the bulk samples, power factor decreases with the ball milling time.

Effects of wood species and retention levels on removal of copper, chromium, and arsenic from CCA-treated wood using sodium hypochlorite

Chemical extraction, bioremediation, and electrodialytic processes have been extensively studied for removal of copper, chromium, and arsenic from wood treated with chromated copper arsenate (CCA). However, one problem has not been addressed: the effects of wood species and retention levels on remediation efficiency. The objectives of this study were to investigate the effects of wood species and retention levels on removal of copper, chromium, and arsenic from CCA-treated wood samples using sodium hypochlorite. Our results showed that sodium hypochlorite (NaOCl) was very effective for removal of copper, chromium, and arsenic from CCA-C treated milled wood samples for all three species used in this study. The Cu, Cr, and As extraction efficiencies for red pine were 95 % Cu, 97 % Cr and 94 % As, for maple were 95 % Cu, 97 % Cr, and 98 % As at 4.0 kg m−3 retention levels, and for aspen were 95 % Cu, 92 % Cr, and 91 % As at 9.6 kg m−3 retention level, respectively. However, the results showed that wood species and initial retention levels of CCA-treated wood products played very important roles in terms of removal of Cu, Cr, and As.

Microwave reflection loss of magnetic/dielectric nanocomposites of BaFe12O19/TiO2

In this research, mixtures of barium ferrite (BaFe12O19) and titanium oxide (TiO2) powders were subjected to intensive milling to produce BaFe12O19/TiO2 nanocomposites. The effect of milling time and titanium oxide content on magnetic properties and microwave reflection loss of the samples were investigated by XRD, SEM, TEM, VSM and Microwave Network Analyzer. XRD results revealed that a nanocomposite forms after 10 h of milling. The average crystallite size of BaFe12O19 in the mixture with 50% titanium oxide was 83 and 13 nm in 10 and 40 h milled samples. The coercivity decreased from 2411 to 1156 Oe and saturation magnetization decreased from 26.0 to 15.2 emu/g after 20 h milling of the initial BaFe12O19 with 50% TiO2. The microwave reflection loss of BaFe12O19 increases by addition of TiO2 and processing the mixture via mechanical milling. Microwave reflection loss analysis showed that by increasing the milling time to 20 h, the reflection loss increases in major part of the X band frequencies. The reflection loss of BaFe12O19 with 35% TiO2 after 20 h milling reaches to maximum value of −10.7 dB at 11.5 GHz in the X-band. The reflection loss of the samples with 35% TiO2 milled for 20 h showed that sample with 3.7 mm is at/near to the matching thickness. The effect of particles morphology on microwave reflection loss was also discussed.

Erratum: “Effects of process control agents on the synthesis of nano-crystalline barium hexaferrite”

Nano size particles of barium hexaferrite were produced by conventional mixed oxide ceramic method from BaCO3 and αFe2O3 as starting materials with a Fe/Ba molar ratio of 11. The mixture of precursors was intensively milled by high energy ball mill and the The influence of various process control agents (PCA) on the process has been investigated. Analysis of the XRD patterns indicates that PCA can strongly alter the morphology and phase composition of ball milled powder particles. In all milled samples, BaCO3 completely decomposed and slight displacement of reflections of hematite phase due to the dissolving of various ions like Ba or C in its lattice is observed. Nano size particles exhibiting angular shape together with some amorphous structure were observed in the sample processed in the presence of NaCl. Barium hexaferrite magnetic phase was partially formed in sample milled in the presence of stearic acid.

Deoxynivalenol in the wheat milling process and wheat-based products and daily intake estimates for the Southern Brazilian population

Fusarium head blight of wheat is caused by the Fusarium species that produces mycotoxins, such as deoxynivalenol (DON). The distribution of DON in wheat products can lead to high economic and health impacts. The objective of this study was to evaluate the natural distribution of DON in the wheat milling process and wheat-based products, as well as the daily intake estimates for the Southern Brazilian population. The fractions of wheat grains (milled wheat, finished flour and bran) were produced in a mill. Additionally, wheat-derived products, such as pasta, bread and crackers were analyzed. The bran fraction had the highest mean concentration of DON (2278 μg kg−1), followed by milled wheat and finished flour (1895 μg kg−1 and 1305 μg kg−1). The distribution factor in the finished flour (69%) fraction demonstrates that DON was reduced when compared to milled wheat, by contrast of bran fraction that presents higher DON levels (120%). A percentage of 35% bran, 35% finished flour and 30% milled wheat samples would not be in compliance with future Brazilian regulations for DON levels. From the wheat-based products analyzed, 17% of whole bread and 10% of salted cracker products were contaminated with DON, with a median of 437 μg kg−1 and 624 μg kg−1, respectively. The finished flour was the fraction that most contributes to the daily intake of DON in Southern Brazil, representing 89.6% of the provisional maximum tolerable daily intake.

Qualitative classification of milled rice grains using computer vision and metaheuristic techniques.

Qualitative grading of milled rice grains was carried out in this study using a machine vision system combined with some metaheuristic classification approaches. Images of four different classes of milled rice including Low-processed sound grains (LPS), Low-processed broken grains (LPB), High-processed sound grains (HPS), and High-processed broken grains (HPB), representing quality grades of the product, were acquired using a computer vision system. Four different metaheuristic classification techniques including artificial neural networks, support vector machines, decision trees and Bayesian Networks were utilized to classify milled rice samples. Results of validation process indicated that artificial neural network with 12-5*4 topology had the highest classification accuracy (98.72%). Next, support vector machine with Universal Pearson VII kernel function (98.48%), decision tree with REP algorithm (97.50%), and Bayesian Network with Hill Climber search algorithm (96.89%) had the higher accuracy, respectively. Results presented in this paper can be utilized for developing an efficient system for fully automated classification and sorting of milled rice grains.

Post-thinning using Ar ion-milling system for transmission electron microscopy specimens prepared by focused ion beam system.

We investigate Ar ion-milling rates and Ga-ion induced damage on sample surfaces of Si and GaAs single crystals prepared by focused ion beam (FIB) method for transmission electron microscopy observation. The convergent beam electron diffraction technique with Bloch simulation is used to measure the thickness of the Ar-ion milled samples to calculate the milling rates of Si and GaAs single crystals. The measurement shows that an amorphous layer is formed on the sample surface and can be removed by further Ar-ion milling. In addition, the local symmetry breaking induced by FIB is investigated using quantitative symmetry measurement. The FIBed-GaAs sample shows local symmetry breaking after FIB milling, although the FIBed-Si sample has no considerable symmetry breaking.

Synthesis and hydrogen absorption/desorption properties of Mg–Nb2O5-SWCNT/MWCNT nanocomposite prepared by reactive milling

Mg–Nb2O5-SWCNT and Mg–Nb2O5-MWCNT composites were prepared by ball-milling in a hydrogen reactive atmosphere (P = 3.0 MPa) for different periods of time, and their sorption behaviors and microstructure were investigated systematically. The results showed that the hydriding and dehydriding kinetics of Mg–Nb2O5-SWCNT and Mg–Nb2O5-MWCNT 1 h milled samples were markedly improved. At 573 K, these two composites could absorb 5.81–4.88 wt% hydrogen under initial hydrogen pressure of 3.0 MPa, and desorb 5.14–4.01 wt% hydrogen within 600 s. Furthermore, these 1 h milled composites could also absorb hydrogen in a moderate temperature range between 298 K and 573 K. However, the Mg–Nb2O5-SWCNT 1 h milled sample had better hydriding/dehydriding kinetics than the Mg–Nb2O5-MWCNT 1 h milled sample. The apparent activation energies for the hydrogen absorption and desorption of the Mg–Nb2O5-SWCNT 1 h milled sample were estimated to be 12.84 kJ/mol and 102.69 kJ/mol from the Kissinger's plot. These figures were lower than those of a pure Mg sample with the same milling time, which were 3.14 and 2.0 times higher, respectively. The desorption temperature and the dehydrogenation enthalpy of the Mg–Nb2O5-SWCNT 1 h milled sample were 140 K and 20.72 kJ/mol, respectively, which were lower than those of pure Mg/MgH2.

Synthesis, bioactivity and zeta potential investigations of chlorine and fluorine substituted hydroxyapatite

Chlorine and fluorine substituted hydroxyapatites (HA-Cl–F) with different degrees of ion replacement were successfully prepared by the one step mechanochemical activation method. X-ray diffraction (XRD) and FT-IR spectra indicated that substitution of these anions in milled powders resulted in the formation of pure hydroxyapatite phase except for the small observed change in the lattice parameters and unit cell volumes of the resultant hydroxyapatite. Microscopic observations showed that the milled product had a cluster-like structure made up of polygonal and spherical particles with an average particle size of approximately ranged from 20±5 to 70±5nm. The zeta potential of milled samples was performed at three different pH (5, 7.4, and 9). The obtained zeta potential values were negative for all three pH values. Negative zeta potential was described to favor osseointegration, apatite nucleation, and bone regeneration. The bioactivity of samples was investigated on sintered pellets soaked in simulated body fluid (SBF) solution and apatite crystals formed on the surface of the pellets after being incubated for 14days. Zeta potential analysis and bioactivity experiment suggested that HA-Cl–F will lead to the formation of new apatite particles and therefore be a potential implant material.

Comparison of structure and magnetic properties of Mn–Zn ferrite mechanochemically synthesized under argon and oxygen atmospheres

Nanocrystalline Mn0.5Zn0.5Fe2O4 ferrite was successfully synthesized by ball milling a powder mixture of MnO, ZnO, and Fe2O3 under argon and oxygen atmospheres. The effects of the milling time, milling atmosphere, and annealing temperature on the milled powders were examined. X-ray diffractometry (XRD), scanning electron microscopy, and transmission electron microscopy were used to evaluate the powder particle structure. The XRD results indicated that after 20 h of ball milling the MnO–ZnO–Fe2O3 powder reacted with a solid-state diffusion reaction route producing Mn–Zn ferrite nanoparticles in the milled samples with both atmospheres. However, some Fe3O4 phase alongside Mn–Zn ferrite, both being spinel-phase, was detected for 40 h milled powders in the argon atmosphere. Those milled powders in the argon atmosphere had smaller crystallite size than the other ones. In the final stage of milling (40 h), the average crystallite size and lattice strain were 20 nm and 0.51%, respectively, ans 25 nm and 0.48% for milled samples in the argon and oxygen atmospheres, respectively. Vibrating sample magnetometer results indicate that the saturation magnetization and coercivity were 34 emu/g and 30 Oe, 18 emu/g and 70 Oe, respectively, for the 40 h milled samples in argon and oxygen, which were annealed at 800 °C for 2 h.

Preparation of flower-like ZnO architectures assembled with nanosheets for enhanced photocatalytic activity

As an important semiconductor metal oxide, various methods have been developed for preparation of ZnO architectures owing to their excellent properties and extensive applications. In this paper, two kinds of 3D flower-like ZnO architectures assembled with numerous nanosheets were successfully synthesized by a simple hydrothermal route assisted by sodium dodecyl sulfate (SDS), origining from the different alkali environment created by urea and hexamine (HMT). SEM and TEM results revealed that the two products had hydrangea-like and rose-like nanostructures with uniform particle sizes, respectively. XRD results confirmed that the growth process of ZnO involved a phase transformation from intermediate compound basic zinc carbonate to ZnO. Base on the experimental results, the formation mechanisms of two kinds of flower-like ZnO undergoing nucleation, oriented growth and self-assembly processes were discussed. The photocatalytic results indicated that both samples exhibited high photocatalytic activities and good cycling stability for the degradation of rhodamine B (RhB), which was almost completely degraded within 25min, in comparison to those milled samples (above 45min). The excellent performances were mainly ascribed to their unique nanostructure, good stability, and uniform particle size.

Synthesis of lead–borate glasses using high energy ball milling (attritor)

High energy ball milling (attritor) was performed to synthesize amorphous PbO–25mol%B2O3 at room temperature. The milled samples were subsequently melted with a less cost-effective way in contrast to other conversional methods. The milled samples were examined by X-ray diffraction and Fourier transform infrared spectroscopy to investigate their amorphization. The absorption of infrared radiation increases with milling time due to change in the dipole moment of the molecule while the crystallinity decreases. As a result of mechanical deformation higher defect concentration generated in the powder and thus aiding in amorphization. After convenient thermal treatments at 600°C for 2h, brittle lead oxide borate single phase was formed with 270.7nm crystallite size.

Structural, thermal and magnetic characteristics of Fe3O4/Ni3Fe composite powder obtained by mechanosynthesis-annealing route

Soft magnetic Fe3O4/Ni3Fe composite powder has been synthetized, starting from Fe, Ni and Fe2O3 powders via mechanosynthesis and subsequent annealing. The incipient formation of Fe3O4 is noticed for the sample milled for 2 h. Formation of Ni3Fe and Fe3O4 does not occur completely after milling for 10 h and as a consequence the presence of a small amount of unreacted Fe2O3 can be found. Subsequent annealing led to the complete reaction between the precursors. Even for the un-milled homogenized mixture of precursors, a partial formation of Ni3Fe and Fe3O4 occurs during annealing. For the milled and annealed samples, the complete formation of the composite Fe3O4/Ni3Fe occurs after 6 h of milling. The DSC measurements and the XRD patterns of the samples subjected to DSC analysis revealed the formation of FeO phase for the starting sample and the samples milled short times (up to 1 h). The complete of the Fe3O4 is noticed upon increasing milling time. The first magnetization curves reveal a two-stage evolution for the milled samples. For milling times up to 3 h, when the Fe2O3 phase is still significant, the value of magnetization has tendency to decrease. Due to the progressive Fe3O4 and Ni3Fe formation, the value of magnetization increases for the samples milled for longer durations. The value of magnetization after annealing is larger than the magnetization value of the milled samples as a result of complete formation of ferrite phase.

Estudio de los cambios microestructurales del Ni al ser sometido a molienda de alta energía

Research by this working group's takes as a principal aim the study and manufacture of bulk metal glass based copper (Cu-Ni-Zr) by mechanical alloying. First, the characterization of the milled pure copper, Cu-Ni and Cu-Zr binary alloys and Cu-Ni-Zr ternary alloys in the same conditions of high energy millings. In this work, the microstructural change of Nickel to be subjected to high energy milling is presented. For this purpose a SPEX 8000D mill with the following conditions of milling: argon, stearic acid, BPR = 10:1, with milling time from 1 to 60 hours, 1 h of effective milling followed by a rest period of 0,5 h. Subsequent to the milling samples were analyzed by ray-X diffraction, transmission electron microscopy and atomic absorption spectroscopy, obtaining the crystallite size, lattice parameters and Fe contamination. The results show that nickel when subjected to mechanical milling reaches a crystallite size of about 10 nm which is asymptotic from 5 h; the lattice parameter increases with increasing milling time, possibly due to increased interfacial component together with the incorporation of Fe, due to the high percentage contamination at 60 h.

English

Tiger nut (Cyperus esculentus) was subjected to different fermentation methods such as traditional, back slope and control. The raw and fermented samples were analyzed for mineral, amino and fatty acids. The results of mineral analysis revealed potassium and sodium as the most abundant mineral element with their value ranging from 546 to 91.6 mg/100 g and 64.00 to 3383.33 mg/100 g, respectively while copper was found in trace amount with value ranging from 0.03 mg/100 g to 0.05 mg/100 g. All the fermented samples shows significant increase in calcium ranging from 8.50 to 9.83 mg/100 g compared to raw samples (7.66 mg/100 g). Amino acid result showed arginine (23.02 g/100 g) as the most abundant amino acid present in back slope fermented tiger nut while tyrosine was the least amino acid (0.05 g/100 g). The oil in tiger nut showed a greater percentage of oleic acid (73.08%) which was recorded in back slope fermented milled sample. The overall result of the investigation revealed that back slope fermentation was the best method that may enhance mineral, amino and fatty acids content of tiger nut. Key words: Tiger nut, mineral, amino acid, fatty acid, fermentation.