Z-type Structure Research Articles

Construction of Ni2P/ZnO nanoflowers Z-type structure for enhanced photocatalytic activity

Construction of Ni2P/ZnO nanoflowers Z-type structure for enhanced photocatalytic activity

Enhanced photocatalytic activity and antibacterial potential of a novel ternary ZnO-Ag2MoO4-AgI heterojunction photocatalyst

The construction of heterojunctions is a recognized strategy for enhancing photogenerated carrier separation. This research introduces a novel ZnO-Ag2MoO4-AgI photocatalyst with a double Z-type heterojunction, made using a straightforward precipitation technique. The precise position of energy levels endowed the ternary photocatalyst with the ability of directional electron flow, while the Z-type structure exhibits strong redox capabilities and facilitates the effective separation of photogenerated charge carriers. The structural characteristics, the photocatalytic activities, the antibacterial properties, and the cytotoxicity of the catalysts were evaluated. The results demonstrate that the catalytic ability of ternary composites work synergistically, surpassing the individual and binary photocatalysts. Notably, the ternary composites with 30 % AgI content exhibit the highest catalytic activity, achieving complete degradation of Rhodamine B in 30 minutes, and up to 71.2 % degradation of Norfloxacin in 60 minutes. Furthermore, more than 99.998 % of Staphylococcus aureus, and 100 % of Escherichia coli were eliminated within 40 minutes, while Human colorectal adenocarcinoma epithelial cells mortality reached 91.98 % at a dose of 250 μg/mL. Our study underscores the potential of this strategy for photocatalytic degradation of organic contaminants, and as an antibacterial agent, providing innovative insights into the design of ZnO-based heterostructure photocatalysts.

Insights into structure-performance relationship in radial flow fixed bed reactor for CO2 methanation

The extraction of petroleum and natural gas is often accompanied by a large number of associated gases, especially the high CO2 content reservoirs facing the emission of a large amount of CO2. CO2 methanation is recognized as one of the suitable candidates for CO2 utilization to reduce the emission of CO2. Because of the highly exothermic nature of the reaction, however, it is very important to enhance the heat transfer process inside the reactor and inhibit the formation of hot spots. In the fixed bed reactor, the heat transfer in the radial direction is greatly limited compared with that in the axial direction. Thus, this work adopted the radial flow reactor to evaluate the CO2 methanation process by the means of a numerical model based on OpenFOAM. Four types of radial flow reactor configurations, namely centrifugal Z-type, centrifugal Π-type, centripetal Z-type, and centripetal Π-type, were compared. The fluid flow, heat transfer, and reaction performances for these reactors were discussed under consistent operating conditions. Results show that the centrifugal Π-type structure has the most uniform flow field. In terms of heat transfer and reaction performance, the centripetal Z-type structure is the best among the four radial flow reactor configurations. These findings provide a theoretical basis and technical guidance for designing and developing radial flow reactors.

CFD Investigation on Secondary Flow Characteristics in Double-Curved Subsea Pipelines with Different Spatial Structures

Double-curved pipes are widely employed as essential components of subsea pipeline systems. Considering the layout flexibility and application diversity, there are various spatial structures for the double-curved combinations. However, few studies have compared the flow characteristics in different double-curved pipes. The dissipations of the corresponding downstream flow have not been thoroughly investigated, which are crucial for the measurement accuracy and flow assurance. In this paper, the turbulent flow in double-curved pipes with different spatial structures (i.e., Z-, U-, and spatial Z- type) was numerically studied by employing the ω-Reynolds stress model. The major purpose was to develop an in-depth knowledge on the secondary flow characteristics in different double-curved pipes and quantify the dissipations of the downstream flow. The effects of the spatial angle and interval distance of the two curves on the flow fields are taken into consideration, and the swirl intensity Si is introduced to evaluate the secondary flow dissipation. It is found that the secondary flows in the Z- and U-type structures are in opposite directions when the interval distance is short (3D), and the secondary flow in the spatial Z-type exhibits an oblique symmetric form. Only in the Z-type pipe with a short interval distance the secondary flow exhibits an exponential dissipation, and the fully developed flow is easier to achieve than the other cases. However, as the interval distance increases, the directions of the secondary flow in the U- and Z-type structures are the same, and the flow dissipations in all the structures return to the exponential types. The obtained dissipation rates for the secondary flow downstream of Z-, U-, and spatial Z-pipes with the 9D interval distance were 0.40, 0.25, and 0.20, respectively. The results are expected to guide the design of pipeline layouts and provide a reference for the arrangements of flowmeters in a complex subsea pipeline system.

Magnetoelectric effects in shear-mode magnetostrictive/piezoelectric composite with a Z-type structure

A shear-mode trilayer magnetoelectric (ME) laminate heterostructure comprising giant magnetostrictive materials (GMMs) and a piezoelectric plate has been prepared in this study. Based on theoretical calculations, the piezoelectric plate with a Z-type structure is subjected to more stress from the magnetostrictive material, which indicates that the stress transfer capacity of the Z-type structure is higher than that of the traditional S-type structure. Experimental research demonstrated that the magnetoelectric coupling coefficient of the Z-type structure is 1.5 times higher than that of the S-type structure. Its ME coupling coefficient exceeded frequency response range was 8 times that of the S-type structure, and vibration displacement was ∼ 2.2 times that of the S-type structure. Finite element simulations have also been performed to calculate the voltage distribution of the shear-mode trilayer ME laminate heterostructure. Since such broadband ME structures are capable of magnetic field detection, this research elucidates the applicability of ME laminate heterostructures for transducing, sensing, and energy harvesting.

Design a J-type air-based battery thermal management system through surrogate-based optimization

Battery thermal management system is of great importance to the performance and safety of electric vehicles. The conventional U- and Z-type air-based structures may fail to meet the thermal requirements under changing working conditions. This paper proposes a novel J-type air-based battery thermal management system by integrating the U-type and Z-type structures. A comparative parametric study of key design variables and priori optimized structures is first conducted with a newly developed battery electro-thermal model. Based on the parametric analyses, the grouped-channel optimizations are performed using surrogate-based optimization. Results show that there are 35.3%, 46.6%, and 31.18% reduction in temperature rise for U-, Z-, and J-type, respectively. The pros and cons of the J-type structure are further explored by comparing with the optimal U- and Z-type structures. A further J-type optimization regarding the manifold configuration is also conducted to show that the optimal settings of the air-based cooling system vary across working conditions, and the J-type structure is able to be adaptively controlled to satisfy the cooling requirement. Corresponding experiments are also conducted to validate the modeling and optimization results.

Simulation of two types fuel cell stack models to investigate the relationship between air flow distribution and structure

For solid oxide fuel cell (SOFC) stacks, it is generally agreed that the distribution qualities of the fuel and air flows would determine the temperature and pressure distribution within the stack. The flow distribution within the stack is considered to depend largely on the geometry of the stack. According to the direction of inlet flow and outlet flow, the designs of the stack can be divided into U-type structure and Z-type structure, and stacks with two structural characteristics should have some similar flow characteristics. Researchers generally have different degrees of understanding of Z- or U-type characteristics, but there are few intuitive experiments and reports on these two types of structures at a larger stack scale. In this paper, two typical one-in-one output stacks with 30 layers in Z-type and U-type models are developed to investigate the general flow distribution.

Strengthening effects of interstitial nitrogen on rhenium

Introducing interstitial nitrogen atoms into the rhenium lattices is accepted for enhancing the mechanical and thermal properties of the metal. Here, we present an experimental study on the strengthening effects of interstitial nitrogen in rhenium on bulk modulus B0 and elastic shear constant C44 by comparing the difference in the compression and vibration behaviors between Re3N and Re in the in situ high pressure angle dispersive X-ray diffraction and high-pressure Raman scattering. The incorporation of interstitial N atoms introduces the covalent bonding and the special Z-type structure along the c-axis, which caused the bulk modulus B0 and elastic shear constant C44 increase by 14% and 15%, and the incompressibility of the c-axis is obviously enhanced. In addition, this work well explains the strengthening effects of interstitial N atoms on mechanical and vibrational properties.

Z-type electronic structure and enhanced photocatalytic performance of silver tungstate – phosphorus and aluminum co-doped zinc oxide heterogeneous catalysts

The Z-type electronic structure visible-light-driven silver tungstate–phosphorus and aluminum co-doped zinc oxide (Ag2WO4−PAZO) heterogeneous catalyst was synthesised by a facile hydrothermal method, wherein the proposed Z-type photocatalytic mechanism was supported by the characterisation of X-ray photoelectron spectroscopy, UV–vis diffuse reflection spectroscopy, reactive species, etc. The photocatalytical capacity was demonstrated by degrading the tetracycline hydrochloride (TC-HCl) antibiotics, and it was necessary to eliminate serious pollution caused by the abuse of TC-HCl. In addition, the heterogeneous catalyst showed higher photoactivity than single PAZO or Ag2WO4 catalyst, which was due to its lower photoexcited electron-hole separation. Multiple measurements were applied to characterise the morphology and optical property of the heterogeneous catalyst. The Ag2WO4−PAZO heterogeneous materials also showed more stability compared with Ag2WO4 material.

Magnetocrystalline Properties of Sr<sub>1.4</sub>Ba<sub>1.6</sub>Co<sub>2</sub>Fe<sub>24</sub>O<sub>41</sub>

Multiferroic Ba1.6Sr1.4Co2Fe24O41 with a Z-type hexagonal structure was obtained through the proteic sol-gel process with a single-phase, combined with thermal treatment at 1200 °C for 2 h. XRD analysis revealed the formation of a single phase, with preferential orientation in the case of a sample in pellet form. Magnetometry measurements revealed a low coercive field characteristic of Z-type hexaferrite, plus an electrical resistivity of approximately 2 × 109 Ω.cm that was considerably higher than expected.

Improvement of Soft Magnetic Properties on Hexagonal Ferrites

The substitution of elements was carried out to improve the soft magnetic properties in hexagonal ferrites. A series of Ba3Co2RxFe24-xO41 samples (R=La, Nd, Gd, Dy, Ho, Yb) with Z-type structure were made. The initial permeability of Gd3+-substituted sample (x=0.1) was the highest of all samples, because the apparent specific anisotropy field of the sample was the lowest. The substituted sample Ba3Co2Mn0.5xTi0.5xFe24-xO41 with x=0.4 had the maximum μ' of 25.7 and μ' × fr product of 17.6 GHz. The M-T curve showed an anomalous drop below the Curie temperature, which reflected the change from in-plane magnetic anisotropy to vertical one with increasing temperature. BaCoxTixFe12-2xO19 (x=1-3) were prepared. The initial permeability increased to 27 for a sample with x=1.15. The reason for this may be that the coercivity becomes small as a result of the decrease in the anisotropic magnetic field. SrCo2+yMe4+yFe12-2yO19 (Me=Zr, Hf) samples were also fabricated. For SrCoyZryFe12-2yO19 (y=0-1.2), magnetization increased slightly for the sample of y=0.4, and then decreased with increasing y. Coercivity drastically decreased up to y=1.2. Magnetic behavior of the Co-Hf substituted sample was similar to that of the Co-Zr substituted one.

Incorporation in Langmuir and Langmuir–Blodgett films of symmetric fluorine substituted bent-core liquid crystals: Morphological and optical properties

Molecular mono- and multilayer films of a symmetric fluorine substituted bent-core liquid crystalline (LC) compound with hydrocarbon end-chains were prepared by the Langmuir and Langmuir–Blodgett (LB) technique. Langmuir films were characterized by surface pressure isotherms and Brewster angle microscopy. Likewise LB-films deposited onto amorphous glass substrates were characterized by ultraviolet–visible spectroscopy, the optical second harmonic generation technique and atomic force microscopy (AFM). Results show optimal non-centrosymmetric Z-type LB-film deposition for moderate number of layers ( n < 20); thereafter, an apparent collapse of the Z-type structure occurs, giving rise to a decrease of the nonlinear optical (NLO) properties. AFM, NLO and linear optical measurements suggest a uniform molecular coverage on the glass substrates and anisotropic orientational distribution; where, according to NLO-experimental data, the LC-bent-shaped molecules are preferably aligned toward the dipping direction with the net molecular polarization perpendicularly aligned to the substrate layer. This observation leads us to implement a simplified model based on the monomeric rod-like approximation, in order to estimate the significant NLO-tensor components.

Sequence-dependent structural effects in left-handed DNA

About 25 years ago the DNA sequence d(CGCGCG)2 was crystallized, and the structure solved as a left-handed helix, dubbed Z-DNA. Many crystal structures of variants of this first sequence have since been obtained. In our laboratory we have focused on what happens to the helical structure, inter-helical interactions, and the solvent interactions when a single A:T (adenine–thymine) base pair replaces a G:C (guanine–cytosine) base pair in the hexameric sequence. We present here a review of these studies. The review addresses three topics. In the first part, it discusses the effect of A:T base pairs on the structure of Z-DNA. The crystal structures demonstrate that the degree of structural perturbation that an A:T base pair produces depends on its position in the sequence, as this alters the length of the G:C tract. The presence of four continuous G:C base pairs appears to be necessary and sufficient to nucleate a Z-type structure. In the second part, the review deals with interactions between helices and crystal packing modes in Z-DNA. It examines the consequences to these aspects, of the presence of an A:T base pair in the sequence. Hexameric duplexes may be approximated as cylinders. This leads to degeneracy in crystal packing modes in Z-DNA, particularly at low resolution. The presence of a single A:T base pair breaks the two-fold symmetry in the sequence and gives rise to directionality in the cylinders. This has interesting effects on the inter-helical interactions, and therefore on the crystal packing. Metal ion and solvent interactions are discussed in the third section of the review. Different ions have different modes of binding to the helices. Some of these are specific to the sequence and lead not only to subtle, but well-marked, variations in the helical structure, but also to differences in helical contacts and therefore crystal packing. In some cases they induce disorder in crystal packing. In others, the ions interact with the helices in a non-specific manner. Contents 1. Introduction 338 2. Sequence-dependent structure 339 3. Crystal packing 344 4. Solvent and ion interaction 350 Acknowledgements 353 References 353 Subject index 355

Ｃｏ含有Ｚ型フェライトの高周波磁気特性に及ぼす希土類イオン置換効果

Ba3Co2RxFe24-xO41 (R: rare-earth element, x = 0−0.5) samples with Z-type structure were prepared by the conventional ceramic method. A series of Ba3Co2RxFe24-xO41 samples (R = La, Nd, Gd, Dy, Ho, Yb) were made. The frequency dependence of the initial permeability of all samples was measured in frequency range of 0.01−1.8 GHz. The initial permeability (at 0.1 GHz) of Ba3Co2R0.1Fe23.9O41 (x = 0.1, R = Gd, Dy, Ho, Yb) samples was higher than of the Co2Z ferrite without substitution. In particular, the initial permeability of Gd3+-substituted Z-type ferrite sample (x = 0.1) was the highest of all samples. The crystal structure of Ba3Co2RxFe24-xO41 (x = 0.1) was a single phase of the Z-type structure. As a result, rare-earth ions formed a solid solution of Co2Z ferrite. The measured lattice constant of these samples (x = 0, 0.1) indicates that La ions substituted for Ba ions and Gd, Dy, Ho, and Yb ions substituted for Fe ions. The apparent specific anisotropy field HA of a Gd3+-substituted Z-type ferrite sample (x = 0.1) was the lowest of the Ba3Co2RxFe24-xO41 samples (x= 0, 0.1). It would therefore appear that the magnetic anisotropy was changed by substitution between Gd ions and Fe ions in Co2Z ferrites. But verification by other determination is necessary.

X-ray and neutron diffraction studies on iron-substituted Z-type hexagonal barium ferrite: Ba 3Co 2− xFe 24+ xO 41 ( x=0–0.6)

Z-type hexagonal ferrite samples in which cobalt are partially substituted with iron, Ba 3Co 2− x Fe 24+ x O 41 ( x=0, 0.2, 0.4, 0.6), were prepared by the ceramics process under a sintering oxygen partial pressure, P O 2 =21.3 or 101.3 kPa, at 1573 K. The influence of the substitution ratio and oxygen partial pressure on the complex permeability was investigated by examining the cobalt distribution over various cation sites in the Z-type structure with the neutron powder diffraction analysis performed at 294 K. The Rietveld analysis performed on the neutron diffraction patterns indicated: (a) cobalt ions occupy only four sites (12k, 4e, 2a and 2d) out of 10 possible sites, (b) only 2a site accepts substituting cobalt ions, and (c) the magnetic spins lie in the basal plane of the hexagonal structure.

Infrared reflection absorption and sum frequency generation spectroscopic study on the structures of the LB films of palmitoyl- l- and dl-ornithine and palmitoyl- l- and dl-lysine

Infrared reflection absorption (IRA) were measured for the Langmuir–Blodgett (LB) films of palmitoyl-lysine (PL) and palmitoyl-ornithine (PO) with various mixing ratios of the l- and d-enantiomers. The introduction of the d-enantiomers to the LB films consisting of the l-enantiomers in PO–LB does not cause any frequency shifts of the amide I and II bands of the peptide groups in PO–LB, while the introduction causes appreciable frequency changes in PL–LB. The IRA spectra of the LB films soaked in D 2O indicated a much higher H/D exchange rate of the peptide groups for PL–LB than that for PO–LB. These results proved the existence of a more flexible molecular assembly in PL–LB compared to that in PO–LB. The SFG spectrum of PL–LB ( d/l = 0/10) gives rise to peaks at 3220 and 3160 cm −1, which are absent in the SFG spectra of PO–LB ( d/l = 0/10). The peaks are ascribable to water molecules in an ordered arrangement, which play as a channel for the H/D exchange process. The bound water molecules render PL–LB more hydrophilic than PO–LB, which explains the fact that the PL–LB forms a Z-type structure and PO–LB a Y-type structure.

Correlation between Magnetic Property and Cation Distribution in Z-type Hexagonal Barium-Ferrite (Ba3Co2-xFe24+xO41) by Neutron Diffraction

ABSTRACTZ-type hexagonal ferrite samples in which cobalt is partially substituted with iron, Ba3Co2-xFe24+xO41(x= 0, 0.2, 0.4, 0.6), were prepared by the ceramic process under a sintering oxygen partial pressure,PO2= 21.3 or 101.3 kPa, at 1573 K. The influence of the substitution ratio and oxygen partial pressure on the complex permeability was investigated by examining the cobalt distribution over various cation sites in the Z-type structure with the neutron powder diffraction analysis performed at 294 K (neutron wave length was 1.006Å). The neutron diffraction pattern was studied with the Rietveld method. A significant difference in the preferential occupation of cobalt on various kind of cation sites was observed between the samples obtained underPO2= 21.3 and 101.3 kPa. Almost all cobalt atoms are on the 12koctahedral site at the boundary between S- and R-blocks in the sample ofx= 0,PO2= 21.3 kPa. On the other hand, in the sample ofx= 0,PO2= 101.3 kPa, cobalt atoms are as well on other sites, the 12koctahedral site at the boundary between S- and T-blocks, the 4etetrahedral site in S-block, the 2aoctahedral site in T-block and the 2dfive fold (trigonal bypiramid) site in T-block.

Ｇｄイオン置換によるＺ型フェライトの高周波初透磁率の改善

Ceramics made from a series of room-temperature ferrimagnetic mixed oxides, Ba3Co2GdxFe24-xO41 (x = 0-1.0), with Z-type structure, were prepared by the conventional powder metallurgy method. A series of Ba3Co2GdxFe24-xO41 samples were made with BaCO3, CoO, Gd2O3, and α-Fe2O3 as starting materials. The frequency dependence of the initial permeability of all samples was measured. The initial permeability of Ba3Co2Gd0.1Fe23.9O41 was 22.3 (at 0.1 GHz), which was the highest of all the samples. It was a remarkably high value compared with those reported for isotropic samples. The crystal structure was determined by the x-ray diffraction method; a single phase of the Z-type structure was obtained for Ba3Co2GdxFe24-xO41 (x = 0.01, 0.1). Gadolinium ions formed a solid solution of Co2Z ferrite. This is one of the reasons for the high initial permeability. The other reasons are higher densification and the change in magnetic anisotropy caused by a small quantity of Gd ions forming a solid solution of the Z-phase.

磁性材料 Ｍｎ置換Ｚ型ヘキサゴナルフェライトの結晶相および高周波磁気特性

A series of room-temperature ferromagnetic mixed oxides, Ba3Co2MnxFe24-xO41, with z-type structure, has been synthesized by high temperature solid-state reaction. Ba3Co2MnxFe24-xO41 was made from BaCO3, CoO, Mn2O3 and α-Fe2O3. The structure was determined by x-ray diffraction method; single phase with z-type structure was obtained for Ba3Co2MnxFe24-xO41(x=0, 1, 2). Frequency dependence of initial permeability of all samples was investigated. The initial permeability of Ba3Co2Mn1Fe23O41 was 13 (at 0.1 MHz), which was highest of all samples. One of the reasons is due to the change of magnetocrystalline anisotropy which caused by Mn ions and Fe ions. The other is decrease of the magnetostriction caused by Jahn-Teller effects which induced by Mn3+ ions.

Second-harmonic generation from alternate-layer and Z-type Langmuir–Blodgett films: optimisation of the transparency/efficiency trade-off

Langmuir–Blodgett (LB) films of (E)-4-[(N-octadecyl-5,6,7,8-tetrahydro-5-isoquinolylidene)methyl]-N,N-dialkylaniline octadecyl sulfate, where the donor group is dimethylamino (1a), diethylamino (1b), dibutylamino (1c) and dihexylamino (1d), have optimum susceptibilities when the dyes are co-deposited in a 1∶1 mole ratio with octadecanoic acid. Alternate-layer structures of the mixed films, interleaved with poly(tert-butyl methacrylate), are non-centrosymmetric and the second-harmonic intensity increases with thickness as to N>100 bilayers. Furthermore, when the dialkylamino group is sufficiently hydrophobic, i.e. for 1c and 1d, the dyes form non-centrosymmetric Z-type structures without interleaving spacer layers. The optimum susceptibilities, chromophore tilt angles, thicknesses and refractive indices of the interleaved and non-interleaved mixed films are as follows: alternate-layer (1b), = 67 pm V−1 at 1.064 µm for φ = 37°, l = 4.08 nm bilayer−1, nω = 1.50 and n2ω = 1.58; Z-type (1c), = 76 pm V−1 for φ = 33°, l = 3.15 nm layer−1, nω = 1.52 and n2ω = 1.58. The moderately high susceptibilities arise from an optimised transparency/efficiency trade-off, the films in this series being transparent at the fundamental wavelength (1.064 µm) and having a very slight absorbance of 5 × 10−4 per active layer at 532 nm.