Search

Zinc coatings on Cu substrates were successfully electroplated from choline chloride (ChCl) with ethylene glycol (EG) based deep eutectic solvent with the current density varied from 10 to 40 mA cm−2 in air atmosphere at a temperature of 343 K. The effects of current density on the microstructure and corrosion performance were investigated in this paper. Smooth zinc coatings were obtained at the current density of 10 mA cm−2 with a current efficiency of over 90 %. With the increase in current density, there was a declining trend in the current efficiency and the surface quality of zinc coatings. Although there was no diffusion layer between the coating and substrates, all the zinc coatings still bonded well with the copper substrates. Compared with the smooth zinc coating electroplated at 10 mA cm−2, the zinc coating obtained at 40 mA cm−2 exhibited a better corrosion resistance in 3.5 wt.% NaCl aqueous solution due to the dense packing of the large number of flake zinc grains.

A well-established association exists between intrauterine bacteria and preterm birth. This study aimed to explore this further through documenting bacterial and cytokine profiles in Australian mid-gestation amniotic fluid samples from preterm and term births. Samples were collected during amniocenteses. DNA was extracted and the full-length 16S rRNA gene was amplified and sequenced. Levels of the cytokines IL-1β, IL-6, IL-10, TNF-α and MCP-1 were determined using the Milliplex MAGPIX system. Bacterial DNA profiles were low in diversity and richness, with no significant differences observed between term and preterm samples. No differences in the relative abundance of individual OTUs between samples were identified. IL-1β and TNF-α levels were significantly higher in samples containing reads mapping to Sphingomonas sp.; however, this result should be interpreted with caution as similar reads were also identified in extraction controls. IL-6 levels were significantly increased in samples with reads that mapped to Pelomonas sp., whilst TNF-α levels were elevated in fluid samples from pregnancies that subsequently delivered preterm. Bacterial DNA unlikely to have originated from extraction controls was identified in 20/31 (64.5%) mid-gestation amniotic fluid samples. Bacterial DNA profiles, however, were not predictive of preterm birth, and although cytokine levels were elevated in the presence of certain genera, the biological relevance of this remains unknown.

In the endeavor to maximize the refinement effect of primary Si and alleviate the inherent brittleness of hypereutectic Al-Si alloy, the approach of coating P as a modifier on powder was adopted. The ultimate aim was to create more heterogeneous fine AlP nucleus and enhance the nucleation efficiency of primary Si on AlP to refine the coarse primary Si to nano-scale during 3D printing. In the combination of large undercooling and high density of nucleation sites, the size of primary Si was successfully refined to 200-300 nm and the divorced eutectic was also induced to modify the microstructure of matrix. In the presence of nano-scale primary Si, the melting pool boundary (MPB) feature disappeared and the fracture mechanism also changed from load transfer to interfacial fracture. Compared with the pristine alloy, the ductility was increased four times without significantly changing the ultimate tensile strength (UTS) and wear resistance. The improvement of ductility is attributed to the refinement of primary Si, the disappearance of MPB features and the formation of divorced eutectic. The optimal tensile properties were: UTS-482 MPa, yield strength-320 MPa and ductility of 8.1% at 0.05 wt.% P. These are comparable to those for high-strength Al alloys.

Although many studies have indicated that orbitofrontal cortex plays an important role in the learning and retrieval of memory and subsequent decision-making, the role of ventrolateral orbital cortex (VLO) still remains unclear, especially related to fear and space.Four separate cohorts of rats were used in this study. After sham surgery and electrical lesion of bilateral VLO, four cohorts received active avoidance test, passive avoidance test, Morris water maze and T maze separately.Firstly, data shown that electrolytic lesions of bilateral VLO of Sprague-Dawley rats shortened the latency of rats to escape to darkroom in passive avoidance test. Besides, the damage of VLO also resulted in decrease of the number of active avoidance of rats from the third day during 5 consecutive days' training in active avoidance test. What's more, the impairment of VLO significantly shortened the exploring time in the target quadrant of rats in Morris water maze. Furthermore, VLO-lesions group shown lower correct alternation percentage than sham group in T maze.These results indicated that not only in the learning and retrieval of fear-related memory, VLO also plays an important role in the learning and retrieval of spatial-related memory guided by visual cues.

In this paper, the synergistic effects of Ce4+ ions incorporation into the (Bi2O2)2+ layer and Mo6+ ions at the Nb site on the electrical properties of CaBi2−xCexNb2−xMoxO9 high-temperature piezoelectric ceramics were studied. The appearance of pseudo-tetragonal phase owing to the introduction of Ce4+ ions is beneficial to the polarization switching, and thus, an enhanced piezoelectric response (d33 = 19 pC/N) was obtained in the x = 0.03 sample. Both the ferroelectric and dielectric properties of the doped samples are enhanced. Moreover, the reduction of the oxygen vacancies of the samples resulting from Mo6+ cations could also facilitate the improvement of electrical properties. As a result, a high Curie temperature (TC = 941 °C) and good electrical properties (Pr =14.3 µC/cm2, ρ = 1.1 × 105 Ω cm at 600 °C) were obtained in Ce/Mo-co-substituted CaBi2Nb2O9 ceramics. The results are rather important to explore the piezoelectric ceramics used in high-temperature environment.

An efficient fluidization process intensification method was proposed to prepare carbon nanotube (CNT)-enhanced high-performance SiO anodes for lithium-ion batteries. The introduction of graphite particles decreased bonding among SiO particles, inhibiting agglomerate growth and enhancing fluidization. The (SiO + G)/CNTs composites were synthesized by fluidized bed chemical vapor deposition with the CNTs grown in- situ, which ensured uniform dispersion and superior anchoring of the CNTs. The in- situ-grown CNTs and stacked graphite ensured excellent structural stability and conductivity. The synthesized (SiO + G)/CNTs delivered a stable reversible capacity of 466 mAh g−1 after 125 cycles and a capacity of ∼200 mAh g−1 at 2 A g−1. The charging results indicated that the 3D network structure comprising CNTs and graphite not only effectively buffered the electrode expansion but also greatly improved mechanical flexibility.

Combined with thermodynamic analysis and various characterizations, such as X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and so on, the reactio...

Powder metallurgy (P/M) route is commonly adopted to fabricate titanium-matrix composites (TMCs). However, majority of the reinforcements are distributed along the grain boundaries, but are absent within the grains, such that the desired mechanical properties are rarely obtained. We have developed a novel process of interfacial/intragranular reinforcement of TMC involving core-shell structured carbon nanotubes (CNTs)/amorphous-C coated Ti–6Al–4V composite powder. In comparison to pristine Ti–6Al–4V alloy, the addition of 0.25 wt% C led to more than 500 MPa increase in compressive yield strength. This is ascribed to the synergistic strengthening effect of interfacial-distributed CNTs/TiC nanoparticles and intragranular-distributed TiC nanoplatelets. The friction coefficient was effectively reduced by more than 30% because of the pinning effect of uniform TiC nanoplatelets that were deeply embedded inside the Ti–6Al–4V matrix.

Carbon nanotubes (CNTs) have been proved a significant role as the reinforcement material in improving the mechanical and electrical properties of metal matrix composites due to their high mechanical properties, excellent electrical and thermal conductivity as well as unique atomic structure. In addition, the dispersion of CNTs has been a key factor in fabricating of metal-based complex especially for copper (Cu) with performance improvement. In the present paper, the well dispersion of functionalized CNTs (F-CNTs) is obtained at the first time, accompanied by using pulse reverse electrodeposition (PRED) technology, leading to formation of the ultrahigh electrical conductivity composite films of Cu/F-CNTs. These composite films exhibit an ultrahigh electrical conductivity of up to 6.1 × 107 S/m (increased by 105.4% of that international annealed copper standard, IACS), but maintain a high hardness of 82.3 HV and tensile strength of 297.1 MPa. It is believed that this work opens new perspectives to develop ultrahigh electrical conductivity composite materials and would role as electric wire for reducing energy loss.

We developed a novel process of planting carbon nanotubes (CNTs) within spherical Ti-6Al-4V powder to fabricate a CNTs/Ti-6Al-4V composite powder. The new powder addressed the issues of spherical morphology maintaining and homogenous dispersion of CNTs, and thereby exhibited good printability. After printing, a relative density of 99.9% was obtained. Microstructurally, some CNTs were retained, while the remaining formed TiC nanoparticles and nanoplatelets via interfacial reaction and dissolution-precipitation mechanisms, respectively. The printed composites had tensile yield strength of 1162 MPa and elongation of 3.2% due to synergistic effect of bridge enhancement of TiC nanoplatelets and load transfer from matrix to CNTs.

A homogenous carbon nanotube (CNT)-Al composite powder used for 3D printing was prepared by in-situ impregnation of carbon nanotubes (CNTs) within Al powder. The use of powder substrates produced the unidirectional gas flow and made the synthesized CNTs bend and encircle on the surface of Al powder. The newly made CNT-Al composite powder thus had a good combination of spherical morphology and uniform dispersion of integrated CNTs. In addition, the high-laser-absorbing CNTs on the surface of Al powder improved the laser absorptivity of pure Al powder through surface chemical modification and surface roughening of Al powder. These advantages not only provided positive printing response including accurate control of geometrical dimensions and absence of metallurgical defects, but also enabled retention of CNTs along the grain boundaries and uniform distribution of Al4C3 nanorods inside the grains after printing. The printed bulk material from CNT-impregnated Al composite powder exhibited good tensile properties, because of the synergistic strengthening effect from highly efficient load transfer of intergranular CNTs and dispersion strengthening effect of intragranular Al4C3 nanorods.

Ultrafine or nano-sized of tungsten carbide (WC) is the key material to prepare ultrafine grained cemented carbides. In this paper, nano-sized WC powders were directly prepared by using industrial nano-needle violet tungsten oxide (WO2.72) as the raw material, a fluidized bed as the reactor, and CO as the carbonization gas. The relationship between particle sizes and reaction temperatures, residence times, atmospheres has been investigated systematically. In addition, the physical–chemical indexes (such as residual oxygen, total carbon and free carbon) of the products were measured. The results indicated that the particle size of WC increased with the increase of temperature from 800 to 950 °C. As the residence time increased, the particle size decreased gradually, and then increased due to slight sintering. The introduction of hydrogen reduced the carbonization rate, and is not beneficial to obtaining nano-sized WC. Products that satisfy the standard were obtained when WO2.72 reacted with CO at 850 °C, 900 °C and 950 °C for 3.0 h, 2.5 h and 2.0 h, respectively. The particle sizes of the three samples calculated from the specific surface area were 46.4 nm, 53.2 nm and 52.1 nm, respectively.

Hydrogenation of 1,3-butadiene over supported Pt particles has long been known as a structure sensitive reaction, yet the nature of this phenomenon has not been well understood. We have previously addressed the reaction pathway for 1,3-butadiene hydrogenation over ∼22 nm Pt particles. In this study, the behaviors of SiO2 supported ∼2.9 nm Pt particles towards 1,3-butadiene hydrogenation have been investigated with the aim of providing a fundamental explanation for the structure sensitivity of this reaction. Interestingly, it was found that the product distribution for the present catalyst towards 1,3-butadiene hydrogenation was sensitive to temperature. However, the evolution of 1,3-butadiene hydrogenation over the catalyst with temperature was not captured by in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The detected carbonaceous species on the Pt surface are more likely to be spectators rather than reaction intermediates for the formation of butenes and n-butane. To understand the behaviors of the catalyst, density functional theory (DFT) calculations were employed to explore the pathways for the formation of the products with low activation barriers. The results show that the coverage and the location of the hydrogen atom are the two key factors for the interpretation of the behavior of Pt particles towards 1,3-butadiene hydrogenation.

The current printable materials are mainly limited to Fe, Ti, Co, and Ni-based alloys because they have good laser absorptivity. However, a number of Al alloys that are highly reflective to a laser are incompatible with selective laser melting. We demonstrate here that the coating with a small amount of high laser-absorbing Ni on Al powder reduces laser reflectivity, improves its printability, and increases tensile strength to ~ 1.5 times that of printed pure Al.

A novel method of incorporating fluidized bed chemical vapor deposition (FBCVD) with electroless plating was developed to effectively prepare the core-shell structured high-Ni-content WC-Ni composite powders. FBCVD offered a unique approach to decorating Ni particles on WC particles. The small Ni particle acted as an active catalyst to effectively produce high-Ni-content composite powders in the subsequent electroless plating process. The particle size and quantity of decorated Ni particle determined the electroless plating rate. FBCVD pretreatment temperature and time had a conflicting influence on obtaining both the fine size and large quantity of deposited Ni particles. For the conditions tested, the maximum electroless plating rate of 2.93 mg/g/min was obtained using an optimal FBCVD pretreatment at 750 degrees C for 5 minutes, corresponding to a 0.11 wt. % Ni deposition and 50 nm particle size.

Synthesis of high melting point non-oxide ceramic powders with mesocrystal structure is an important and challenging task. TiN mesocrystals were fabricated for the first time by using metastable TiCl2. The new synthetic strategy opens up a window for designing reaction systems and fabricating new types of non-oxide mesocrystals with high melting points.

Brain-derived neurotrophic factor (BDNF) is one of the neurotrophic factors that promotes the survival and protection of neurons in many disorders. The potential protective effect of BDNF and its mechanisms on morphine addiction are unclear. In this study, morphine-induced conditioned place preference (CPP) in mice was used to show the effect of BDNF on rewarding behavior. Western blot assays were used to determine the changes caused by BDNF, for example, changes in total BDNF, tropomyosin-related kinase receptor B (TrkB), and cAMP response element binding protein (CREB) in the ventral tegmental area (VTA) and nucleus accumbens (NAc). The results showed that the BDNF-adeno-associated viral vector (BDNF-AAV) injected in the VTA, attenuated morphine-induced CPP with synergistic changes in BDNF/TrkB/CREB concentrations in the VTA and NAc in the CPP acquisition and recurrence phases; however, the attenuation was lower in the extinction phase, with different changes in molecules downstream of the BDNF.

This study aims to investigate the daylight in old shophouses in Georgetown, Penang, which have become guesthouses, with particular emphasis on visual comfort and the friendly courtyards. It depended on the climate-based daylighting metric. The study used computer simulation and on-site measurements to convince the shophouse owner. With the design of the courtyard space and the light sensitivity of human vision, the daylighting performance was evaluated in the entire space of the representative model of the traditional courtyard shophouse. The results were analyzed and design recommendations were presented to improve the overall visual environment.

Nano-sized TiC platelets/particles synergistically reinforced Ti-6Al-4V composites were fabricated by consolidating a novel designed core-shell C-coated Ti-6Al-4V (Ti-6Al-4V@C) powder. TiC nanoplatelets were present in α-Ti grains and TiC nanoparticles were distributed in β-Ti grains. The α-Ti was reinforced by the bridging enhancement derived from the TiC nanoplatelets, while the β-Ti was reinforced by the effective pinning effect of the TiC nanoparticles on dislocations. Their synergetic strengthening effect on the α-Ti and β-Ti contributed to the outstanding mechanical properties.

In this study, the reduction-carbonization property of WO3 obtained by thermal decomposition of ammonium paratungstate (APT) under N2 and air atmosphere in a fluidized bed was investigated. The decomposition property of APT in N2 and air was analyzed by TG analyzer. Phase, morphology, deoxidation rate and carbonization rate of the decomposed products in the reduction-carbonization process were investigated. It was found that APT could be rapidly decomposed into monoclinic WO3 in a fluidized bed in N2 or air atmosphere. Compared with N2 atmosphere, air was more favorable for the rapid decomposition of APT and the crystal transition of WO3. Under the same conditions, the products obtained in N2 atmosphere had smaller grain size, larger porosity, faster deoxidation rate and carbonization rate. Both WO3 obtained in the N2 and air could be reduced and carbonized to nano-sized WC with SBET particle sizes of 63.70 nm and 73.49 nm in a fluidized bed, respectively.

Cytokines produced by adipose and placental tissues (adipokines) have been implicated in the development of gestational diabetes mellitus (GDM). There is, however, limited research regarding the relationship between advancing pregnancy, maternal adipokine profile, insulin resistance and the development of GDM. Furthermore, no studies have investigated these parameters in women with a history of GDM who are at the highest risk of recurrence. This study examined the circulating concentrations of a number of adipokines associated with insulin resistance at two points in pregnancy, and determined whether they were altered in women who developed GDM.Non-diabetic women with a history of GDM in a previous pregnancy (n=123) had blood drawn at 14 and 28weeks of pregnancy for GDM diagnosis, together with assessment of a range of adipokine concentrations by multiplex assay (fatty acid-binding protein 4 [FABP4], leptin, chemerin, adiponectin and resistin).With advancing pregnancy, maternal adiponectin concentrations decreased, while leptin and resistin levels increased (p0.05). In women who developed GDM at 28weeks of pregnancy (42%), fasting and postprandial glucose levels were already significantly elevated by 14weeks (p0.05), while adiponectin concentrations were lower (p0.05). Adiponectin remained lower at the time of GDM diagnosis (p0.05), while the other adipokines were similar between groups at each timepoint.Maternal glucose and adipokine profile is altered early in pregnancy in women with a history of GDM who subsequently develop recurrent disease.

Using the concept of a metallic cylinder and a linearly tapered metallic baffle loaded in a circular waveguide to convert TM02 circular waveguide mode into TE11 circular waveguide mode, a novel and compact circular waveguide TM02-TE11 mode converter is designed, fabricated, and measured. The detailed design methods, experimental setups and results are presented in this study. Simulation results show that the purity of output fundamental TE11 mode of the converter exceeds 99.6% for an operating frequency of 9.4 GHz and the power capability is as high as 1.66 GW, the mode conversion efficiency is more than 90% from 9.23 to 9.83 GHz band and the relative bandwidth is about 6.38%. A good agreement between measurements and simulations is observed. The circular waveguide TM02-TE11 mode converter has many advantages, such as the simple structure, coaxial input and output, high conversion efficiency, proper bandwidth and high power-handling capability. When used in the field of high power microwave transmission and radiation, the proposed converter could significantly enhance the compactness of all the radiation systems.

Lithium-based ceramic tritium breeders would attack the blanket structural materials and produce brittle corrosion layers, causing potential safety hazard. Herein, coated breeders were proposed as advanced tritium breeders to address the issue. Carbon (C), titanium nitride (TiN) and titanium carbide (TiC) were investigated as inert protective shells because they show excellent stability and chemical compatibility with Li2TiO3 and Li4SiO4. Moreover, for the first time, the C and TiN coated Li2TiO3 and Li4SiO4 pebbles were successfully fabricated by fluidized bed chemical vapor deposition (FBCVD) process, which would significantly decrease the brittle corrosion layers and increase the safety. The deposition behavior and interface reactions were systemically investigated.

In this study, two kinds of 14Cr ODS alloys (14Cr-Al and 14Cr-Ti) were investigated to reveal the different effects between Al and Ti on the microstructures and mechanical properties of 14Cr ferritic ODS alloys. The microstructure information such as grains, minor phases of these two alloys has been investigated by high-energy X-ray diffraction and transmission electron microscopy (TEM). The in situ synchrotron X-ray diffraction tensile test was applied to investigate the mechanical properties of these two alloys. The lattice strains of different phases through the entire tensile deformation process in these two alloys were analyzed to calculate their elastic stresses. From the comparison of elastic stress, the strengthening capability of Y2Ti2O7 is better than TiN in 14Cr-Ti, and the strengthening capability of YAH is much better than YAM and AlN in 14Cr-Al ODS. The dislocation densities of 14Cr-Ti and 14Cr-Al ODS alloys during tensile deformation were also examined by modified Williamson-Hall analyses of peak broadening, respectively. The different increasing speed of dislocation density with plastic deformation reveals the better strengthening effect of Y-Ti-O particles in 14Cr-Ti ODS than that of Y-Al-O particles in 14Cr-Al ODS alloy. Keywords: Synchrotron X-ray diffraction, Tensile deformation, Nanoscale particles, Microstructure

Long-term thermal-aging treatments at 973 K were carried out on a 16Cr-oxide dispersion strengthened (ODS) ferritic steel in air with the aging time ranging from 10 h up to 5000 h. The microstructural evolution of the 16Cr-ODS samples during the thermal-aging treatments was characterized using field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Additionally, variations in the mechanical properties including Vickers micro-hardness, tensile properties, and Charpy impact toughness before and after thermal-aging treatments are reported. It was found that the 16Cr-ODS ferritic steel displayed a relatively good thermal-aging stability in respect to the microstructure and mechanical properties during the long-term thermal-aging treatments at 973 K. Keywords: Steel, Mechanical alloying, Electron microscopy, Mechanical characterization, Aging