Low Angle Region Research Articles

Mesoporous SO42− / kit-6-catalyzed hydrocracking of waste chicken oil

In this study, we studied the hydrocracking of waste chicken oil (WCO) catalyzed by mesoporous SO42−/KIT-6. The study included WCO extraction, SO42−/KIT-6 catalyst synthesis, hydrocracking, and catalytic characterization. XRD patterns revealed intense peaks in the low-angle region, with shoulder peaks showing an increase in sulphate loading from 10% to 30%. The BET-specific surface area for the pure KIT-6 supports measured at 1003 m2/g, indicative of a well-defined mesoporous structure. Thermogravimetric analysis (TGA) showed a two-stage weight loss, attributed to the elimination of hydrated water (about 200 °C) and decomposition of sulphate ions (400–450 °C). SEM analysis highlighted the surface morphology of the active SK-2 catalyst. Hydrocatalytic and catalytic cracking reactions were performed, and about 99.8% conversion was achieved with 20 mL/H H2 flow, whereas higher production of bioliquids was observed at a flow of 15 mL/h. The hydrocracking mechanism was also studied to understand the formation of lower hydrocarbons. GC analyses of simulated distilled gasoline, kerosene, and diesel showed diverse hydrocarbon compositions. For engine testing, non-hydrocracked fuel rose to 28 kW at 3000 rpm and declined to 21 kW at 3500 rpm. Emission analysis revealed decreasing trends in NOX emissions of hydrogen-rich blends, with values of 65 ppm, 54 ppm, and 48 ppm for petrol, NHBL, and HBL, respectively. Similarly, SO2 emissions reduced from petrol to NHBL and HBL at 910 ppm, 800 ppm, and 600 ppm, respectively, suggesting reduced environmental impact. CO emissions exhibited a substantial reduction in NHBL (0.90%) and HBL (0.54%) compared to petrol (2.70%), emphasizing the cleaner combustion characteristics. Our results provide a comprehensive exploration of waste chicken oil hydrocracking, emphasizing catalyst synthesis, fuel characterization, engine performance, and environmental impact, thereby contributing valuable insights to the field of sustainable bioenergy.

Determination of upper limit of Guinier approximation on dilute polydisperse system in SAXS

For a dilute polydisperse system in small-angle X-ray scattering (SAXS), Guinier’s law can be used to perform an approximate analysis to determine the mean radius of gyration of scatterers in a sample and extend the scattering curve to the lower angle region. The main idea of the law is that the Guinier plot appears linear in the vicinity of the scattering vector equaling zero. In this short contribution, a differential method is proposed to uniquely determine the upper limit of the effective range of the Guinier approximation on dilute polydisperse systems. The theoretical simulation is mainly performed on the typical spherical scatterers in several dilute polydisperse systems to explore the relationship between the upper limit and the shape and size of the scatterers. The SAXS experiment on a sample of silicon dioxide colloid is carried out to verify the feasibility of the new method.

Magnetic Mesoporous Silica for Targeted Drug Delivery of Chloroquine: Synthesis, Characterization, and In Vitro Evaluation.

Malaria is a dangerous tropical disease, with high morbidity in developing countries. The responsible parasite has developed resistance to the existing drugs; therefore, new drug delivery systems are being studied to increase efficacy by targeting hemozoin, a parasite paramagnetic metabolite. Herein, magnetic mesoporous silica (magMCM) was synthesized using iron oxide particles dispersed in the silica structure for magnetically driven behavior. The X-ray diffractogram (XRD) and Mössbauer spectra show patterns corresponding to magnetite and maghemite. Furthermore, Mössbauer spectroscopy revealed superparamagnetic behavior, attributed to single magnetic domains in particles smaller than 10 nm. Even in the presence of iron oxide particles, the hexagonal structure of MCM is clearly identified in XRD (low-angle region) and the channels are visible in TEM images. The drug chloroquine (CQ) was encapsulated by incipient wetness impregnation (magMCM-CQ). The N2 adsorption-desorption isotherms show that CQ molecules were encapsulated in the pores, without completely filling the mesopores. BET surface area values were 630 m2 g-1 (magMCM) and 467 m2 g-1 (magMCM-CQ). Encapsulated CQ exhibited rapid delivery (99% in 3 h) in buffer medium and improved solubility compared to the non-encapsulated drug, attributed to CQ encapsulation in amorphous form. The biocompatibility assessment of magMCM, magMCM-CQ, and CQ against MRC5 non-tumoral lung fibroblasts using the MTT assay after 24 h revealed no toxicity associated with magMCM. On the other hand, the non-encapsulated CQ and magMCM-CQ exhibited comparable dose-response activity, indicating a similar cytotoxic effect.

Parameter study for critical heat flux under external reactor vessel cooling condition based on a mechanism model

External reactor vessel cooling has been adopted an important method to implement In Vessel Retention severe accident mitigation strategy for many advanced passive pressurized water reactors. Critical heat flux is one of the important criteria to evaluate the success or failure of this strategy. The uncertainty of engineering factors in practical design and operation conditions may make influence on critical heat flux more or less. In this paper, a parameter study for critical heat flux was carried out based on a new critical heat flux mechanism model. This mechanism model is developed based on the mechanism of liquid film dryout, and the predicted results of this model are in good agreement with the experimental results. Five important parameters, namely, coolant subcooling degree, geometry of lower head, system pressure, flow rate and heating power shape are analyzed based on this mechanism model. The results of parameter study show that the decrease of inlet coolant temperature and lower head radius are beneficial to the increase of critical heat flux. And the critical heat flux increases with the increase of system pressure. While the change of flow rate and heating power shape have little effect on critical heat flux. Under the condition of same circumference, the critical heat flux of spherical lower head is higher than that of elliptical lower head in the middle and low inclination angle region, while the trend is opposite in high inclination angle region, but not significant.

Phosphotungstic acid immobilized over SnO2 mesoporous material as a heterogeneous catalyst for fructose to 5-hydroxymethylfurfural conversion

5-Hydroxymethylfurfural (HMF) is regarded as an essential platform chemical due to its flexible nature that could be converted into a variety of value-added compounds including production of liquid fuels and fine chemicals. We have developed a phosphotungstic acid (PTA) immobilized over SnO2 mesoporous material by hydrothermally employing Pluronic P123 as a structure directing agent (SDA) to obtain a heterogeneous catalyst for fructose to HMF conversion, and the catalyst is designated as MSnPTA. The powder X-ray diffraction patterns in low angle region, type IV isotherm and fringes of the catalyst confirmed the mesoporosity of the material. The catalyst is comprised of BET surface area of 85.86 m2/g and average pore diameter of 7.9 nm. Spherical shape through worm like structure formed small particles facilitated the large surface area of the MSnPTA catalyst that prefer to occur the catalytic reaction. The uniform elemental distribution of PTA over SnO2 ascribed more active sites, resulting in high acidity of the catalyst as measured by TPD of ammonia, which increased the conversion of fructose to high yield of HMF in a short reaction time. The yield of the HMF increased as increasing the amount of catalyst and temperature as expected.

Retraction to: A mathematical model to characterize the degree of coalification based on the low-angle region of the X-ray diffractogram.

Retraction to: A mathematical model to characterize the degree of coalification based on the low-angle region of the X-ray diffractogram.

69‐4: Collimating and Recycling Linear Evaporation Source for AMOLED Mass Production

It is important in AMOLED pixel forming process to reduce low angle region flux of particles emitted from thermal evaporation source. Because it can cause the mask shadow effect, nozzle clogging and material waste. We developed Collimating and Recycling source. It has unique nozzle structure that can make low angle flux go down to recycling basket and pass only high angle flux through final nozzle. It can make collimating flux that is similar with cosine to the tenth. And it can recycle material 70%.

Interacting-heads motif explains the X-ray diffraction pattern of relaxed vertebrate skeletal muscle

Electron microscopy (EM) shows that myosin heads in thick filaments isolated from striated muscles interact with each other and with the myosin tail under relaxing conditions. This “interacting-heads motif” (IHM) is highly conserved across the animal kingdom and is thought to be the basis of the super-relaxed state. However, a recent X-ray modeling study concludes, contrary to expectation, that the IHM is not present in relaxed intact muscle. We propose that this conclusion results from modeling with a thick filament 3D reconstruction in which the myosin heads have radially collapsed onto the thick filament backbone, not from absence of the IHM. Such radial collapse, by about 3–4 nm, is well established in EM studies of negatively stained myosin filaments, on which the reconstruction was based. We have tested this idea by carrying out similar X-ray modeling and determining the effect of the radial position of the heads on the goodness of fit to the X-ray pattern. We find that, when the IHM is modeled into a thick filament at a radius 3–4 nm greater than that modeled in the recent study, there is good agreement with the X-ray pattern. When the original (collapsed) radial position is used, the fit is poor, in agreement with that study. We show that modeling of the low-angle region of the X-ray pattern is relatively insensitive to the conformation of the myosin heads but very sensitive to their radial distance from the filament axis. We conclude that the IHM is sufficient to explain the X-ray diffraction pattern of intact muscle when placed at the appropriate radius.

Diversity of intergranular corrosion and stress corrosion cracking for 5083 Al alloy with different grain sizes

5083 Al alloy sheets with different grain sizes (8.7−79.2 μm) were obtained by cold rolling and annealing. Their microstructures, intergranular corrosion (IGC), stress corrosion cracking (SCC), and crack propagation behaviors were investigated. The results showed that samples with coarse grains exhibit better IGC resistance with a corrosion depth of 15 μm. The slow strain rate test results revealed that fine-grained samples exhibit better SCC resistance with a susceptibility index (ISSRT) of 11.2%. Furthermore, based on the crack propagation mechanism, grain refinement can improve the SCC resistance by increasing the number of grain boundaries to induce the corrosion crack propagation along a tortuous path. The grains with {011} orientation could hinder crack propagation by orientating it toward the low-angle grain boundary region. The crack in the fine-grained material slowly propagates due to the tortuous path, and low H+ and Cl− concentrations.

Theoretical comparison of lattice parameter and particle size determination of pure tin oxide nanoparticles from powder X-ray diffraction

SnO2 is an n-type semiconductor and a transparent conducting oxide and has apt properties in a gas sensing material, photovoltaic cells, fuel cells, batteries etc., Nanocrystalline tin oxide (SnO2) powders with different grain sizes were prepared by chemical co-precipitation method. Synthesised nanopowder XRD data were analyzed with different tools. X-ray diffraction (XRD) analysis mainly used to determine the crystal structure of nanomaterials such as ZnO, CuO, CdO and SnO2, etc., Pure SnO2 test conditions were set to be Cu-Kα XRD source, accelerating voltage 40 kV, acceleration currency 40 mA, scan range 20–80° with Ni filter (λ = 0.154056 nm). The pure SnO2 sample was exhibiting different crystalline peaks from the powder XRD study. The diffraction peak of pure tin oxide nanoparticles possesses a tetragonal rutile structure with space group P42/mnm. The FULLPROF Suite program was used for Rietveld–type analysis for pure SnO2powder diffraction data. The resultant data were compared with Nelson-Riley, Williamson-Hall plot, and Debye-Scherer methods. The lattice parameters and particle size of pure SnO2were agreed with the ICDD.No.01-077-0447data. The main advantages of these methods are low angle regions and a small number of peaks needed.

Design of a broadband blade and DRA hybrid antenna with hemi-spherical coverage for wireless communications of UAV swarms

Blade antennas are widely used for airborne communications owing to their light weight and wide bandwidth. However, radiation pattern of a blade antenna is monopole-like and yields a deep null towards its top direction. This will cause serious blind spots for the aircraft towards its top and bottom directions, which is not desirable for future avionic networks. To solve this issue, a dielectric resonator antenna (DRA) is added to the blade antenna and forms a new design. A rectangular DRA is adopted in this paper to illustrate the main idea. The rectangular DRA operates in the lowest TE111 mode and its radiation pattern covers the high elevation angle region. The blade antenna, on the other hand, has a nearly omni-directional radiation pattern in the low elevation angle region. Combination of the DRA and blade antenna can provide a hemispherical coverage with relatively small ripples. A closed-form model is presented to explain the radiation mechanism of the hybrid antenna. For verification, a prototype antenna is designed, fabricated and measured. Its impedance bandwidth covers 1.3–2.4 GHz and its radiation patterns yield small ripples in the top hemi-sphere until 2.1 GHz.

A study on the erosion-corrosion behaviour of engineering materials used in the geothermal industry

Erosion-corrosion can be a significant issue for engineering components used in the geothermal industry. This study assesses the erosion-corrosion behaviour of a wide range of engineering alloys which are used in various parts of geothermal power plants. The evaluated materials comprised a carbon steel, low-alloy steel, three grades of stainless steel together with Ni–Cr alloy (Inconel 625) and Ti–6Al–4V. Tests were conducted by utilising a submerged 90° impinging slurry jet consisting of silica sand particles suspended in an acidic (pH 4) aqueous solution consisting of 3.5% NaCl. Gravimetric mass losses, in-situ potentiodynamic polarisation scans and an enhanced volumetric analysis technique were used to assess the influence of hydrodynamic conditions on the erosion-corrosion behaviour of the test materials. The effect of applied cathodic protection was also examined. Post-test metallurgical examination was also conducted via SEM. The results showed the distinct differences between low alloy steels and “corrosion resistant” alloys – with the former demonstrating substantial material loss in the low-angle corrosive wear region due to large amounts of corrosion-related damage. Both superaustenitic stainless steel (UNS S31254) and Inconel 625 (UNS N06625) exhibited the greatest erosion-corrosion resistance of the test materials – with Inconel 625 demonstrating the greatest resistance to high angle corrosive wear. The relevance of the findings to materials selection and other methods of protection against surface degradation in geothermal power plants is discussed.

Alkynyl-Based sp 2 Carbon-Conjugated Covalent Organic Frameworks with Enhanced Uranium Extraction from Seawater by Photoinduced Multiple Effects

Biofouling is a major obstacle to the efficient extraction of uranium from seawater due to the numerous marine microorganisms in the ocean. Herein, we report a novel amidoxime (AO) crystalline cova...

Novel optical properties and induced magnetic moments in Ru-doped hybrid improper ferroelectric Ca3Ti2O7

Hybrid improper ferroelectric Ca3Ti2O7 and Ca3Ti19Ru0.1O7 ceramics were successfully synthesized by conventional solid-state reaction method. Two strongest diffraction peaks located around 2θ = 33° shifted towards the lower angle region with Ru substitution, reflecting structure variation. Grain growth and higher oxygen vacancy concentration after doping resulted in a reduction in the coercive field about 20 kV/cm. Optical bandgap estimated by UV-vis diffuse reflectance (DR) spectrum and X-ray photoelectron spectroscopy (XPS) valence band spectra showed a decreasing trend due to the existence of impurity energy level upon Ru doping, which was consistent with the results of first-principles calculations. The origin of the unexpected induced magnetic moments in Ru-dope Ca3Ti2O7 is also discussed.

Crack propagation during Charpy impact toughness testing of Ti−Al−V−Mo−Zr alloy tubes containing equiaxed and lamellar microstructures

Numerous reports have elucidated the importance of impact toughness measurements for investigating the damage tolerance of a material. However, the effect of heat treatment parameters on impact toughness and the crack propagation mechanism in titanium alloys has rarely been addressed. Herein, the impact toughness of extruded Ti−Al−V−Mo−Zr alloy that comprises equiaxed and lamellar α microstructures has been investigated by conducting Charpy impact tests. The resulting fracture surface and alloy microstructure were examined by scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. The obtained results revealed that the colony size decreased after a solid solution and aging treatment, whereas subcritical annealing and slow cooling led to the globularization of lamellar α grains. After globularization, the impact toughness of the alloy increased by 69.2% and 50.0%, respectively; however, the impact toughness of the sample after the solid solution and aging treatment decreased by 61%. During impact testing, the direction of crack propagation was oriented toward the low-angle boundary region. Furthermore, a dissolved secondary phase was formed in the vicinity of the fracture surface, which increased the resistance of the alloy to crack propagation. The present study provides significant guidance for the preparation of titanium alloys with superior impact toughness properties.

Narrow Band Emission of Pr3+-Activated Oxide-Oxynitride Pervskites Under Near-UV Lights Controlled By Bandgap Engineering

In this study, the photoluminescence of Pr3+-acitvated oxide-oxynitride perovskites, CaMxTa1-xO2+xN1-x (M : Zr and Hf) with the range from 0.0 to 1.0 were investigated. This solid-solution system should be expected that the wavelength at maximum exciation intensity is widely adjusted along with bandgap energy between valence and conduction bands by the control of the O/N and Zr (or Hf) /Ta ratios [1]. Thus, the sharp emission peak from Pr3+ in the solid-solution system can be excited by near-UV or blue lights if the width of bandgap energy is adujusted from 2.8 to 3.2 eV. The solid-solution sample were prepred by polymerizable complex method. The obtained precursors were heat-treated under NH3 gas flow at 900-1100oC. XRD patterns indicated that all the samples were of single phase with orthorombic perovskite structure. In the case of CaZrxTa1-xO2+xN1-x, XRD patterns also show the shift of diffraction peaks to low angle region by increasing with Zr4+ concentaration. The absorption was shifted to high-energy sides with increasing Zr4+ concentration. Especially, the bandgap energy were sucessfully adjusted from 2.7 to 3.2 eV while the x was changed from 0.25 to 0.90 by the control of the Zr4+/Ta5+ and O/N ratios. Furthremore, the solid-solution system showed the intersting photoluminous behavior. The single emission peaks were observed at 612 nm when the bandgap enegries were adjusted at around 3.0 eV for the samples with x from 0.55 to 0.70, Such red emission peak can be assigned to the electron transition between 1D2 and 3H4 levels of Pr3+ ions (Fig. 1). In contrast, when the bandgap energy became larger than 3.0 eV, the PL spectra was gradually changed. Several emission peaks were observed in the range from 490 to 750 nm, which can be assinged as the electron transition between 3P0 to 3H4, 3H5 and 3F2 levels [2]. This behavior should be atributed to the width of the bandgap energy of the host compounds. This work was partially supported by JSPS “KAKENHI” (15K06445) and (18K04714). [Reference] [1] Wu et al., Int. J. Hydrogen Energy, 37 (2012) 13704, [2] Nakamura et al., J. Sol-Gel Sci Technol, 61 (2012) 362.

Anomalous Trapping of Low Pitch Angle Electrons by Coherent Whistler Mode Waves

AbstractChorus emissions composed of coherent whistler mode waves are responsible for pitch angle scattering of energetic electrons. This scattering is closely related to energetic electron precipitation into the atmosphere, contributing to pulsating auroras. Conventionally, energetic electrons are considered to satisfy the cyclotron resonance condition over the energy range of a few to tens of kiloelectron volts and are scattered toward the loss cone by waves. However, previous simulation studies indicate that low pitch angle electrons tend to be scattered away from the loss cone by coherent whistler mode waves. We examine the mechanism of anomalous trapping at low pitch angles, deriving a particle equation with low pitch angle assumptions. An additional term that is conventionally neglected represents the Lorentz force caused by the wave magnetic field and the parallel particle velocity. Therefore, due to the large v‖×Bw Lorentz force, low pitch angle electrons satisfying the cyclotron resonant condition are scattered away from the loss cone and effectively trapped by waves. We perform test particle simulations in a one‐dimensional dipole magnetic field with a whistler mode wave model and reproduce the anomalous trapping of electrons. The simulation results show that the majority of electrons at high and moderate pitch angles are scattered toward low pitch angle regions while low pitch angle electrons are strongly scattered toward high pitch angle regions. Consequently, a coherent chorus element produces a bump in the electron pitch angle distribution.

Noble and Base-Metal Nanoparticles Supported on Mesoporous Metal Oxides: Efficient Catalysts for the Selective Hydrogenation of Levulinic Acid to γ-Valerolactone

The selective hydrogenation of levulinic acid, LA to γ-valerolactone, GVL in water and solvent-free systems using mesoporous TiO2, NiO and MnO2 metal oxides supported noble and base-metal nanoparticles was investigated. BET results showed that all the synthetized materials were mesoporous with type IV isotherms and type I hysteresis. The p-XRD peaks observed in the low angle region confirm the successful formation of the meso-structured materials, whereas the wide-angle diffraction patterns show that the crystalline structure of the pure nanocatalysts is maintained upon deposition of the metal. TPR results showed that the reduced supported nanocatalysts consist of metallic Ru, Pd, Cu and Cr, and the average particle sizes obtained from HRTEM were found to be of 2 to 6 nm in diameter. The as-synthetized reusable nanocatalysts were revealed to be highly efficient for the conversion of LA to GVL. The best performance with complete conversion of LA and > 95% GVL selectivity was obtained from the TiO2 and MnO2-based nanocatalysts when water was used as a solvent. The order of reactivity of the supported metal nanoparticles was established as: Pd ≈ Ru > Cu > Cr. With an activity, TOF of up to 277273 h−1/mol, the low cost copper-based nanocatalysts could be an alternative to the high cost noble metal-based catalysts.

Geometrical dependence on the stress and slip tendency acting on the subduction megathrust of the Nankai seismogenic zone off Kumano

We assess the dependence of megathrust geometry near the updip edge of the Nankai seismogenic zone according to the slip tendency of the megathrust based on a reprocessed 3D PSDM seismic volume image and International Ocean Discovery Program (IODP) NanTroSEIZE drilling data off the coast of the Kii Peninsula, central Japan. The plate boundary fault surface is manually picked from the 3D seismic volume and is divided into three groups: low dip (10°–15°) trending NW to N in the NE region, intermediate dip (~ 25°) trending north in the western region, and high dip (30°–40°) trending NW in the SE corner. We then calculate the overburden (Sv) by converting the modeled 3D velocity to bulk density. Here, Sv ranges from 100 MPa near the SW edge to 160 MPa on the NE corner. In order to derive horizontal principal stresses (SH and Sh) and the pore fluid pressure (Pp), we assign the ratio of horizontal-to-vertical principal stresses, r (= SH/Sv), and the ratio of pore fluid pressure-to-vertical stress, λ (= Pp/Sv) based on IODP drilling data. The directions of SH and the slip on the fault are set parallel to the plate convergence vector (N55W). Assuming a triaxial condition (SH > Sh = Sv), the slip tendency (Ts) can be calculated from the dip angle and dip azimuth of the fault surface, r, and λ. We found that Ts is sensitive to the variation in fault geometry. For r = 1.2 and λ = 0.7 (normalized pore pressure ratio λ* = 0.25), Ts is low (~ 0.1) in the low-angle dip region and higher (> 0.2) in the high-angle dip region. This suggests that the high-angle fault is optimally oriented under this condition. Low Ts in the low-angle dip region would correspond to a weaker region due to a low frictional strength, assuming that the fault surface should slip simultaneously. Using the high pore pressure ratio (λ* ~ 0.85) beneath the fault zone, the fault beneath IODP Site C0002 is very close to failure if r > 1.2.

OFDM chirp radar for adaptive target detection in low grazing angle

Low-altitude target detection is of great importance in radar applications, especially for military radar to counter the targets penetrated from low grazing angles. However, it is a challenge to detect the targets in low grazing angle area due to severe multipath reflection effects. In this study, the authors propose orthogonal frequency division multiplexing (OFDM) chirp waveform for target detection in low grazing angle region. The OFDM chirp waveform has better peak-to-average-power ratio level and provides larger time-bandwidth product than that of conventional OFDM waveform, which is beneficial for target detection. Two different radar schemes, namely, OFDM chirp radar and OFDM chirp multiple-input multiple-output (MIMO) radar, are studied under the Earth's curvature geometry model with the consideration of realistic multipath reflection effects. The generalised likelihood ratio test algorithm is developed by jointly exploiting the advantages of OFDM chirp waveform and MIMO configuration in increased degrees of freedom. In addition, an adaptive algorithm is further applied to enhance the target detection performance. All proposed schemes are verified by numerical results.