Μm Average Size Research Articles

Preparation of a modified crosslinked chitosan/polyvinyl alcohol blended affinity membrane for purification of His‐tagged protein

ABSTRACTBased on a crosslinked chitosan (CS)/polyvinyl alcohol (PVA) matrix membrane, an immobilized metal ion affinity membrane (IMAM) using Cu2+ and Ni2+ ions as affinity ligands was prepared for purification of the His‐tagged recombinant protein. The affinity membrane possessed a favorable membrane structure including 1.39 μm average pore size and 0.33 mL·cm−2·s−1 water flux under 0.08 MPa pressure at 25 °C. The Cu2+ and Ni2+ ions capacities immobilized on the IMAM were 155.6 and 137.3 μmol·disk−1, respectively. The IMAM had an excellent specific affinity to His‐tagged protein. About 10‐fold purification factor for the model protein was obtained in a batch adsorption, and serine hydroxymethyl transferase could be purified to a single band in sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis from its crude extract solution with an affinity membrane cartridge by a dynamic purification process. This work provides a promising IMAM for the purification of His‐tagged recombinant proteins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47347.

Ultralow loss and temperature stability of Li3Mg2NbO6-xLiF ceramics with low sintering temperature

Novel temperature stable Li3Mg2NbO6-xLiF (x = 0.5–8 wt %) ceramics with ultralow loss were fabricated by the solid-state reaction process. The influence of LiF addition on the sintering, grain growth and morphology, and improved microwave dielectric characteristics was investigated. A single orthorhombic Li3Mg2NbO6 structure could be confirmed by Raman spectra and XRD patterns. Dense and homogeneous microstructure could be obtained with ∼10 μm average grain size. Results demonstrated that the εr values were relevant to bulk density and the high Q×f values were influenced by the large grain sizes. The τf values depend on porosity corrected dielectric constant. Notably, the remarkably desirable microwave dielectric characteristics: εr = 15.4, Q×f = 100,000 GHz, τf = −3.1 ppm/°C were achieved for the Li3Mg2NbO6 ceramics with x = 6 wt% sintered at 925 °C, which could be applied for ultra-low loss LTCC applications.

Effect of gas-induced semisolid process on solidification parameters and dendrite coherency point of Al–4.3Cu alloy using thermal analysis

Semisolid processing of Al–4.3%Cu (A206) alloy was carried out using gas-induced semisolid (GISS) process in different conditions. The flow rate of inert gas, 1, 2, and 4 L min−1, starting temperature for gas purging (the temperature of superheated melt), 670, 660, and 650 °C, and the duration of gas purging, 10, 20, and 30 s, were three key process variables which were changed during this investigation. Thermal analysis was successfully implemented through CA-CCTA technique for GISS samples as well as conventionally cast sample. The two-thermocouple thermal analysis technique was utilized to determine the dendrite coherency point of GISS sample and conventionally cast sample. The results showed that gas purging into the melt led to temperature drop of the melt to its liquidus temperature. In fact, copious nucleation is induced by cooling effect of inert gas bubbles. GISS process delays the dendrite coherency point from 644.2 to 637.3 °C which leads to increase the solid percentage from 9 to 21% at this point and therefore enhance the casting characteristics. It is found that inert gas purging into the molten metal, regardless of the process parameters, leads to the microstructural modification from fully dendritic to globular structure. Microstructural evaluation showed that the best sample which included fine grains of 76 μm in average size and with high level of globularity of 0.86 was achieved from a semisolid sample in which the gas purging started at 670 °C and its duration time was 20 s with the gas flow rate of 4 L min−1.

Anomalocardia brasiliana shellfish shells as a novel and ecofriendly adsorbent of Nylosan Brilliant Blue acid dye.

Malacoculture waste (Anomalocardia brasiliana) shellfish shells (ABSS) were evaluated as adsorbents of Nylosan Brilliant Blue (NBB) acid dye. The ABSS were thermally activated at 1,000 °C for 10 h and then characterized by Fourier-transform infrared spectroscopy, analysis of specific surface area (BET), X-ray diffraction (XRD), and scanning electron microscopy. Point of zero charge (PZC) analysis of ABSS verified pHPZC 13.0. The study of kinetics showed that the pseudo-second-order model fit the experimental data best and the system reached equilibrium within 5 min. Adsorption isotherms followed the Langmuir-Freundlich isotherm and ABSS reached an outstanding maximum adsorption capacity of 405 mg·g-1 under the following optimum conditions: pH 12.4, 303 K, 450 rpm, 2.0 g of adsorbent, and 150 μm average particle size. These conditions were obtained after a previous statistical analysis of the variables. Enthalpy and Gibbs energy obtained in the thermodynamics experiments were -23.79 kJ·mol-1 and -4.07 kJ·mol-1, respectively. These parameters confirm that the process is exothermic, spontaneous, and indicative of the physical nature of the adsorption. The adsorption of NBB onto ABSS tended to be more favorable at a lower temperature. Low value of enthalpy suggested that weak binding forces, such as electrostatic interactions, govern the sorption mechanism. ABSS high availability in the environment, its low toxicity and high efficiency make it a promising ecofriendly adsorbent of textile dyes.

Investigation of the effect of vertical immersed tube diameter on heat transfer in a gas-solid fluidized bed

In this work, the influence of the vertical tube diameter on the performance of the heat transfer is conducted in a gas-solid fluidized bed of 0.14 m inside diameter. The heat transfer coefficient is measured using an advanced fast-response heat transfer probe. Two tube diameters of (0.0254 and 0.0127 m) were used to study the reliance of the heat transfer coefficient of the immersed vertical tubes on the tube diameter, using glass beads solid particles of 365 μm average size and 2500 kg/m3 solid density (Geldart B particles), with a static bed height of 0.35 m. The experiments were conducted at different superficial gas velocities, axial heights (H/D), and three radial positions (r/R). It was found for all used operating conditions and measurement positions inside the bed that the local heat transfer coefficient is increased with an increase in the vertical tube diameter such that an enhancement in the heat transfer coefficient occurred when the immersed tube diameter increased from 0.0127 to 0.0254 m. The current common correlations available in the literature do not predict our experimental results well. Therefore, a new regression correlation was predicted using JMP®12 statistical software based on relevant dimensionless groups, with a good mean relative deviation value of 4.59% between the experimental and predicted data.

The effect of silica nanoparticles on the pore structure of hydrating cement paste: a spatially resolved low-field NMR study

ABSTRACTThe hydration process of four different cement-based materials at different depths inside the sample was investigated using localised nuclear magnetic resonance relaxation measurements. All the samples are based on white Portland cement (CEM I 42.5 R), with a water-to-cement ratio of 0.5. One sample is a simple cement paste and the other three additionally contain 5% (by mass of cement) silica nanoparticles (50–200 nm size), silanised silica nanoparticles (with silane A 174) or silica fume (80% silica; 0.15 µm average size). The localised transverse relaxation measurements were performed using a single-sided NMR instrument. The relaxation rates were monitored for 48 h during the hydration process at different depths inside the sample. The results showed that the presence of nanoparticles influences not only the speed of hydration overall, but also the homogeneity of the materials.

The impact of vertical internals array on the key hydrodynamic parameters in a gas-solid fluidized bed using an advance optical fiber probe

The effect of a circular configuration of intense vertical immersed tubes on the hydrodynamic parameters has been investigated in a gas-solid fluidized bed of 0.14 m inside diameter. The experiments were performed using glass beads solid particles of 365 μm average particle size, with a solid density of 2500 kg/m3 (Geldart B). An advanced optical fiber probe technique was used to study the behavior of six essential local hydrodynamic parameters (i.e., local solids holdup, particles velocity, bubble rise velocity, bubble frequency, and bubble mean chord length) in the presence of vertical immersed tubes. The experimental measurements were carried out at six radial positions and three axial heights, which represent the three key zones of the bed: near the distributor plate, the middle of the fluidizing bed, and near the freeboard of the column. Furthermore, four superficial gas velocities (u/umf = 1.6, 1.76, 1.96, and 2.14) were employed to study the effect of operating conditions. The experimental results demonstrated that the vertical internals had a significant effect on all the studied local hydrodynamic characteristics such that when using internals, both the solids holdup and bubble mean chord length decreased, while the particles velocity, bubble rise velocity, and bubble frequency increased. The measured values of averaged bubble rise velocities and averaged bubble chord lengths at different axial heights and superficial gas velocities have been compared with most used correlations available in the literature. It was found that the measured values are in good agreement with values calculated using predicted correlation for the case without vertical internals. While, the absolute percentage relative error between the measured and calculated values of these two hydrodynamic parameters indicate large differences for the case of vertical internals.

Development and Characterization of Tungsten Disulfide Ink for Ink-jet Printing

ABSTRACTIn this work, a printable tungsten disulfide (WS2) based ink is developed from readily available WS2 powder (0.6 µm average particle size), and an ink-jet printing based deposition method for a tungsten disulfide film is presented. WS2 flake coverage and bulk electrical characteristics under three different irradiance conditions are examined and discussed. Presence of excitons in the absorbance of the inks is performed by optical UV-Vis spectrometry. Metrics using the A exciton peak generated by the few-layered flakes are used to calculate the average flake lateral dimensions, the concentration of WS2 in the inks after size selection and filtering, as well as the average monolayer count of the flakes. After printing, scanning electron microscopy is used to confirm average flake lateral size and average flake area coverage, while an atomic force microscope is used to confirm flake thickness.

Fabrication and Phase Transition of La2-X Lu x Zr2O7 Transparent Ceramics

Materials with A2B2O7 formula have been drawing the attention of researchers for a diversity of applications, such as fast-ion conductors, photocatalysts, thermal barrier coatings, matrices for immobilization of highly active radionuclides from nuclear wastes and host materials for scintillators. A2B2O7 materials have three crystal phases decided by the ionic radius ratios (r A/r B). According to the rule of Subramanian et al [1], pyrochlore phase was favored when r A/r B lay within the range of 1.46~1.78. Defective fluorite phase is stable for r A/r B < 1.46, whilst the monoclinic phase is stable for r A/r B > 1.78. In this study, a new series of La2-x Lu x Zr2O7 (x = 0~2.0) transparent ceramics [2] with high density and average atomic number, which are hoped to be scintillator matrix, were fabricated by vacuum sintering and an interesting phenomenon was found. As Lu content increased, the crystal phase gradually transformed from pyrochlore to defective fluorite phase with the existence of a two-phase region (x = 0.6 ~ 1.2) (Figure 1). The appearance of a two-phase region illustrated that Subramanian’s theory is not available when there is large difference in ionic radii of the elements that occupy at Ln position (r La 3+ = 1.160 Å, r Lu 3+ = 0.977 Å). In addition, the grain growth of pyrochlore phase was inhibited due to the appearance of defective fluorite phase. Grain sizes of samples dominated by pyrochlore phase were 11~14 μm. Samples with two phases (x = 0.6~1.2) have much smaller grain sizes (< 3 μm), while samples dominated by defective fluorite phase have larger grain sizes (82~60 μm). All the samples (except for x = 0) are transparent and the highest in-line transmittance is reached to 72.4% (1100 nm) at x = 1.2 though two phases coexist. To verify that the two-phase region was not an accident, we fabricated LaLuZr2O7 powder by combustion method instead of solid state reaction and sintered in the same way. From XRD results, two phases are observed in both the synthesized powder and ceramic. Also, With 2 ~ 3 μm average grain size, the LaLuZr2O7 ceramic reaches high transparency with an in-line transmittance of 73.4% at 1100 nm, which is slightly higher than that made by solid state reaction method, showing the advantage of combustion method in synthesizing good powder. Rayleigh-Gans-Debye scattering theory was used to explain the high transmittance of the ceramics with two phases. When the refractive indices of the coexisting two phases are close to each other and the average grain size is smaller than 10 μm, the two phases have little influence on transparency of the ceramics. [1] Subramanian MA, Aravamudan G, Subba Rao GV. Oxide pyrochlores-A review. Prog Solid State Chem 1983, 15: 55-143. [2] Z.J. Wang, G.H. Zhou, X.P. Qin, F. Zhang, J.P. Ai, P. Liu, S.W. Wang. Fabrication and phase transition of La2-xLuxZr2O7 transparent ceramics. J Eur Ceram soc 2014, 34: 3951–3958. Figure 1

Effects of ultrasonic agitation prior to deposition and additives in the bath on electrodeposited Ni-B/hBN composite coatings

Ni-B/hBN composite coatings were successfully deposited by conventional electroplating method on mild steel substrate. Electrodeposition was carried out in Watts type nickel electrolite and trimethylamine borane (TMAB) was used as boron element source. hBN particles with 1 μm average powder size were used as reinforcements. In this study, the effects of additives in the bath and ultrasonic mixing before deposition on the composite coating properties were evaluated. Crystal structure, morphology and composition of composite coatings were investigated by X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. Also corrosion behavior of composite coatings was analysed via Tafel extrapolation and open circuit potential techniques in 3.5% wt. NaCl solution. The results showed that the composite coatings that have compact and smooth properties were obtained and ultrasonic agitaiton significantly influenced corrosion resistance of composite coatings and uniform distribution of incorporated hBN particles. It was found that corrosion rate of the composite coatings was 76.7% and 78.5% lower than that of composite coatings produced in the bath without ultrasonic mixing and without ultrasonic mixing plus additives, respectively.

Metal-Coated Cenospheres Obtained via Magnetron Sputter Coating: A New Precursor for Syntactic Foams

Syntactic foams (SFs) and metal matrix syntactic foams (MMSFs) represent an advanced type of metal matrix composites (MMCs) based on hollow microspheres as particulate reinforcement. In general, SF and MMSFs allow tailoring of properties through choice of matrix, reinforcement, and volume fraction of the latter. A further handle for property adjustment is surface modification of the reinforcing particles. The present study introduces cenospheres for use as filler material in SF and MMSFs and as lightweight filler with electromagnetic interference shielding properties in civil engineering, which have been surface coated by means of physical vapor deposition, namely vibration-assisted sputter coating using a magnetron sputtering system. Altogether four types of such cenosphere-based composite powders (CPs) with an original particle size range of 50–125 µm (average particle size d50 75 µm) were studied. Surface films deposited on these were composed of Cu, stainless steel, Ti, and Ti-TiN double layers. For Cu coatings, the deposited metal film thickness was shown to be dependent on the sputtering energy. Scanning electron microscope backscattering images revealed nonporous films uniform in thickness directly after sputtering. Film thickness varied between 0.15 µm and 2.5 µm, depending on coating material and sputtering parameters. From these materials, samples were produced without addition of metal powders, exhibiting metal contents as low as 8–10 wt.% based on the coating alone. Obtained samples had an apparent density of 1.1–1.9 g/cm3 and compressive strengths ranging from 22 MPa to 135 MPa.

Diamond powder incorporated oxide layers formed on 6061 Al alloy by plasma electrolytic oxidation

In this study, diamond powder was incorporated into oxide layers formed on 6061 Al alloy by using plasma electrolytic oxidation (PEO) method. Diamond powder, 1.5 μm in average size, was added in an amount of 0, 3, 6 and 9 g/L, respectively, into the electrolyte containing 0.15 M Na2SiO3 and 0.16 M H3BO3. Phases, microstructure and composition of the oxide layers were investigated by XRD, SEM and EDX analyses. Micro-hardness of the coatings was measured using a micro-indenter. Corrosion performance of PEO coatings was evaluated using potentiodynamic polarization in a solution of 3.5% NaCl. Wear resistance was evaluated using a ball-on-disk tribometer. Both XRD and EDX spectra prove the incorporation of diamond into the coating. With increasing content of diamond powder in the electrolyte, analytical results indicate that the thickness, roughness, corrosion and wear resistance of the coatings increase. PEO coatings obtained with an optimum diamond powder content 6 g/L shows the best performance. The best corrosion resistance is 9.70 × 108 Ω cm2, the highest micro-hardness 855 HV, the lowest average friction coefficient 0.29, and showing the least weight and volume losses after wear tests. Performance of the coatings deteriorates when obtained at a higher content of added diamond powder, 9 g/L. This is due to the sudden increase of both porosity and roughness of the coatings. The variation in coating performance is explained based on the evolution of phase, microstructure, micro-hardness, porosity and roughness with the amount of diamond incorporation.

A comparison of pretreatments on hydroxyapatite formation on Ti by biomimetic method

In this study, hydroxyapatite coating on titanium material substrate was successfully performed by using biomimetic method. Titanium plates immersed in 1.5 SBF at pH 7.4 and 37 °C were analyzed at the end of the first, second, and fourth weeks. At the end of the first week, the immersion process was continued with the sample exposed to the optimum selected surface pretreatment. Three different treatments have been applied to determine the optimum surface treatment: each substrate immersed into NaOH, HCl, and NaOH + HCl solutions before heat treatment at 600 °C for 1 h and immersed in NaOH solution was selected the optimum surface treatment. The presence of biphasic hydroxyapatite (HA, Ca5(PO4)3(OH)) and tricalcium phosphate (TCP, Ca3(PO4)2) on Ti surfaces were confirmed by XRD. SEM studies showed that denser HA coating which have nano-sphere-like morphology formed on Ti pretreated with NaOH solution at the end of first week than other hydroxyapatite (HA)-coated Ti pretreated with NaCl and NaOH + NaCl solutions and coating thickness increased by increasing immersion time. The HA coating thickness of the samples immersed in optimum pretreatment solution was found as 178 and 340 μm for at the end of second and fourth weeks, respectively. The particle size analysis of the biphasic HA powders scraped from the coating layer on the substrate before and after sintering was carried out by Zetasizer and it showed that HA powders have 0.58 μm average particle size and their particle size distribution has less dimensional dispersion after sintering. Energy-dispersive X-ray spectroscopy (EDS) analysis revealed that the Ca/P ratio in HA powders was near to 1.5. Raman and Fourier transform-infrared spectroscopy (FTIR) results combined with the X-ray diffraction (XRD) indicated the presence of biphasic hydroxyapatite after biomimetic coating process and increment in crystallinity of the powders after sintering. It was found that HA nucleation on Ti pretreated with NaOH solution was higher than Ti pretreated with other solutions which is confirmed by electrochemical impedance spectroscopy (EIS).

Effect of Barothermal Processing on the Solid-State Formation of the Structure and Properties of 16 at % Si–Al Hypereutectic Alloy

We describe barothermal processing (hot isostatic pressing) of a 16 at % Si–Al binary alloy for 3 h at a temperature of 560°C and pressure of 100 MPa for 3 h, in combination with measurements of heat effects during cooling. The results demonstrate that this processing leads to the fragmentation of the silicon structural constituent and ensures a high degree of homogenization of the as-prepared alloy. Heat treatment of the 16 at % Si–Al alloy at 560°C and a pressure of 100 MPa leads to a thermodynamically driven enhanced silicon dissolution, up to ~10 at %, in the aluminum matrix, resulting in the formation of a supersaturated solid solution, which subsequently decomposes during cooling. We analyze the complete porosity elimination process, which makes it possible to obtain a material with 100% relative density. According to differential barothermal analysis, microstructural analysis, and scanning and transmission electron microscopy data, barothermal processing of the 16 at % Si–Al alloy produces a bimodal size distribution of the silicon phase constituent: microparticles 3.6 μm in average size and nanoparticles down to ~1 nm in diameter. The Al matrix has been shown to contain a high density of edge dislocations. Barothermal processing reduces the thermal expansion coefficient and microhardness of the hypereutectic alloy. We conclude that solid-state barothermal processing is an effective tool for completely eliminating microporosity from the 16 at % Si–Al alloy, reaching a high degree of homogenization, and controlling the microstructure of the alloy, in particular by producing high dislocation density in the aluminum matrix.

Tungsten Matrix Material for Diffusion Barium Tungsten Cathode

As the core component of the diffusion cathode, the performance of porous tungsten matrix material will directly affect the output performance and life of microwave source. Therefore, the preparation of porous tungsten matrix is the key process of making a cathode material. In this paper, the industrial tungsten powder was used as raw material, whose particle size was modulated by fluidic classification firstly. Then via cold isostatic pressing and hydrogen sintering in high temperature, the porous tungsten sintered body was obtained. Finally, by the process of copper infiltration, machining and copper removal, the porous tungsten matrix was achieved. The result showed that compared with raw material tungsten powder, the classified tungsten powder’s particle size distribution was narrowed and its tap density obviously increased, indicating that it had better particle stacking performance. Setting the temperature between 1900°C and 2050°C the high temperature hydrogen sintering experiment was conducted, and it was found that the volume shrinkage ratio of tungsten sintered body increased with the sintering temperature, and correspondingly, its total porosity decreased from 24.4% at 1900°C to 20.8% at 2050°C. It was characterized by MIP (mercury intrusion porosimetry) that at high temperature between 1950~2050°C, the porous tungsten matrix with an open porosity of 21±1%, 1.30~1.60μm average pore size, a close cell ratio less than 1% and the skeleton strength greater than 150MPa was obtained. Thus this porous tungsten matrix is an ideal material to be applied to highly reliable diffusion bariated tungsten cathode manufacturing.

Fatigue Properties of Ultra-Fine Grain Austenitic Stainless Steel and the Effect of Hydrogen

The fatigue properties of ultra-fine grain austenitic steel (UFG16-10), which has a 1 μm average grain size, were studied as part of the project aimed at the development of high-strength low-cost stainless steels for hydrogen service. The fatigue properties of the UFG16-10 were compared with that of a coarse grain material with the same chemical composition (CG16-10) and two kinds of commercial steels, JIS SUS316 and JIS SUH660. The fatigue strength of the UFG16-10 was 2.8 times higher than that of the CG16-10. The effect of hydrogen on the fatigue limit of the UFG16-10 was not significant. However, the fatigue life of the UFG16-10 was reduced by hydrogen in the short life regime. In the fatigue crack growth test, the UFG16-10 showed a good crack growth resistance that was equivalent to that of the SUH660 and significantly higher than that of the SUS316. However, the crack growth rate was significantly accelerated by hydrogen. The cause of the hydrogen-assisted fatigue crack growth of the UFG16-10 was transformation of the microstructure at the crack tip from austenite to strain-induced martensite. This was also the cause of the reduced fatigue life of the hydrogen-charged UFG16-10.

Influence of Porosity and Pore-Size Distribution in Ti6Al4 V Foam on Physicomechanical Properties, Osteogenesis, and Quantitative Validation of Bone Ingrowth by Micro-Computed Tomography.

Cementless fixation for orthopedic implants aims to obviate challenges associated with bone cement, providing long-term stability of bone prostheses after implantation. The application of porous titanium and its alloy-based implants is emerging for load-bearing applications due to their high specific strength, low stiffness, corrosion resistance, and superior osteoconductivity. In this study, coagulant-assisted foaming was utilized for the fabrication of porous Ti6Al4 V using egg-white foam. Samples with three different porosities of 68.3%, 75.4%, and 83.1% and average pore sizes of 92, 178, and 297 μm, respectively, were prepared and subsequently characterized for mechanical properties, osteogenesis, and tissue ingrowth. A microstructure-mechanical properties relationship study revealed that an increase of porosity from 68.3 to 83.1% increased the average pore size from 92 to 297 μm with the subsequent reduction of compresive strength by 85% and modulus by 90%. Samples with 75.4% porosity and a 178 μm average pore size produced signifcant osteogenic effects on human mesenchymal stem cells, which was further supported by immunocytochemistry and real-time polymerase chain reaction data. Quantitative assessment of bone ingrowth by micro-computed tomography revealed that there was an approximately 52% higher bone formation and more than 90% higher bone penetration at the center of femoral defects in rabbit when implanted with Ti6Al4 V foam (75.4% porosity) compared to the empty defects after 12 weeks. Hematoxylin and eosin (H&E) and Masson trichrome (MT) staining along with energy-dispersive X-ray mapping on the sections obtained from the retrieved bone samples support bone ingrowth into the implanted region.

Echinostoma macrorchis (Digenea: Echinostomatidae): Metacercariae in Cipangopaludina chinensis malleata Snails and Adults from Experimental Rats in Korea.

A survey was performed to know the infection status of echinostome metacercariae in Cipangopaludina chinensis malleata snails from Korea. Total 75 snails collected in 5 localities, i.e., Imsil-gun, Jeollabuk-do, Hwasun-gun and Shinan-gun (Aphae and Jido), Jeollanam-do, and Jinju-si, Gyeongsangnam-do, were examined for metacercariae by the artificial digestion method. Infection rates of metacercariae were 80.0%, 66.7%, 100%, 60.0%, and 73.3%, and their densities were 39, 32, 183, 19, and 30 per snail infected, respectively. The metacercariae were round, 105–118×105–118 μm in size, with a thin cyst wall, collar spines on the head collar, and excretory granules in 2 canals of excretory tube. Adult flukes were elongated, ventrally curved, and 5,167×939 μm in average size. Head collar distinct, bearing 45 collar spines with 5 end groups on each side. Oral sucker subterminal, pharynx well developed, and esophagus somewhat short. Cirrus sac well developed, with a saccular seminal vesicle, and ventral sucker very large. Ovary elliptical and on the median line of the body. Testes tandem and slightly lobed. Eggs operculated, elliptical, and 90–103×55–60 μm in size. By scanning electron microscopy, the head collar was prominent with 45 collar spines resembling horns of younger stags. Scale-like tegumental spines were densely distributed on the body surface between the head collar and ventral sucker. Conclusively, it has been first confirmed that the life cycle of E. macrorchis is indigenously maintained in Korea, and C. chinensis malleata snails are popularly infected with the metacercariae of this echinostome.

New Record of Aspidogaster ijimai Kawamura, 1913 (Trematoda: Aspidogastridae) from Cyprinus carpio in Korea.

Aspidogastrid trematodes (Subclass Aspidogastrea) are a relatively small group with a characteristic adhesive disc and parasitize in a variety of cold-blooded hosts. Until now, only 2 species in the genus Cotylaspis, i.e., C. coreensis and C. sinensis, have been reported as the aspidogastrid trematode in the Republic of Korea (=Korea). In the present study, we intended to describe a species of aspidogastrids collected from the small intestine of the common carp, Cypri-nus carpio, in a faunistic point of view. Total 51 specimens were collected from a carp caught in Nakdong-gang (River) on May 2015. Some of them were prepared as the specimens for light microscopic observations, and some others were prepared for SEM. They were slightly elongated without head lobes, 2,432×840 μm in average size, and had characteristic adhesive discs with 4 rows and 46 alveoli in average. The ovary was reniform and was located in the posterior-upper part of the body. The single testis was larger than the ovary and was located below the ovary. The uterus was coiled containing numerous eggs and distributed in the posterior 2/3 of the body. The vitellaria were follicular, and distributed from the mid-level of testis to near the posterior end. The morphological characters with dimensions of our specimens were closely identical with those of Aspidogaster ijimai previously described. A new aspidogastrid is added among the Korean trematode fauna by the present study.

Enhanced magnetic properties of xSrFe12O19/(1 − x)CoFe2O4 composites

xSrFe12O19/(1 − x)CoFe2O4 (0 ⩽ x ⩽ 1.0) composites with about 2 µm average particle size were prepared by a conventional solid-state route. Results show that the xSrFe12O19/(1 − x)CoFe2O4 composites exhibit a typical single-phase magnetic behavior, suggesting the existence of an exchange-coupling effect. The saturation magnetization (Ms) of the composites sintered at 1230 °C increases from 49.05 to 64.84 A · m2 · kg−1 with the increase of CoFe2O4 content. Compared with single-phase CoFe2O4, the coercivity (Hc) of the composites is enhanced markedly from 10.47 to 116.66 kA · m−1. The enhancement of magnetic properties is ascribed to the high coercivity of SrFe12O19, high saturation magnetization (Ms) of CoFe2O4 and the exchange-coupling effect between SrFe12O19 and CoFe2O4 ferrites.