We have studied the oxidation behaviors of aluminum (Al) nanopowders with different particle sizes using a real-time synchrotron X-ray scattering during annealing in air. The Al nanopowders with small particle size of 78 nm at room temperature (RT) were a single crystal. The surface of the nanopowders was first oxidized to amorphous Al oxide near 450 °C, and then crystallized to γ-Al₂O₃ phase at 550 °C. The inside of the nanopowders existed as crystal Al phase at 680 °C, high compared to the melting temperature of Al bulk, 660 °C. In contrast, the Al nanopowders with large particle size of 816 nm at RT have multi grains inside a particle. The surface and grain boundary of the powders were first oxidized to amorphous Al oxide near 470 °C, and then crystallized to γ-Al₂O₃ phase at 550 °C. The inside of the powders existed as amorphous Al phase at 620 °C, melted at 656 °C, and then oxidized gradually above 656 °C.
The zirconia used in dental implants requires excellent mechanical and chemical properties such as high strength, high biological performance, corrosion resistance, and phase stability. In this study, after we prepared a highly fluidized solution of calcium phosphate, we fabricated a hydroxyapatite (HA) coating layer on a zirconia substrate using the sol-gel method to enhance its biocompatibility and bone-bonding ability. We dipped the zirconia substrate into the calcium phosphate sol to obtain the HA-coated film, which was dried at room temperature. The phase change and microstructural evolution were examined while the coating dried and during heat treatment. The biological activity of the coated and as-received substrates was evaluated using an in vitro experiment and the results were compared. The HA-coated film showed a highly dense and uniform layer structure, while its physical and biological properties depended on the starting substrate, coating times, and processing conditions.
Dramatic increases in fossil fuel consumption inevitably led to the emission of huge amounts of CO₂ gas, causing abnormalities in the climate system. Despite continuous efforts to resolve global atmospheric problems through CO₂ capture and separation, success has been limited by poor CO₂ selectivity in the CO₂/N₂ mixture. Herein, we demonstrate the fabrication of a three-dimensional (3D) nanostructure from two-dimensional transition metal carbides (Ti₃C₂Tx, MXene), and assess its utility as an adsorbent in a CO₂ capture system. Through structural and textural analysis, we confirm that the as-prepared MXene possesses high size uniformity with a thickness of ~2.5 nm, and that an MXene aerogel interconnected by MXene nanosheets has a 3D porous architecture with micro/nano porosity (Barrett-Joyner-Halenda (BJH) pore size = 11.4 nm). Moreover, the MXene aerogel exhibits favorable adsorption behavior for CO₂, due to the high-quality MXene nanosheets even with a low specific surface area. Our approach could lead to significant advances in CO₂ capture by adsorbents and open up new opportunities for mass production.
In thermoelectric modules, multiple n-type and p-type thermoelectric elements are electrically connected in series on a Cu electrode that is bonded to a ceramic substrate. Defects in the bond between the thermoelectric elements and the Cu electrode could impact the performance of the entire thermoelectric module. This study investigated the effect of plating layers on the bonding strength of p-type Bi-Te thermoelectric elements. Ni and Pd electroplating was applied to Bi-Te thermoelectric elements; further, electroless Ni-P immersion gold (ENIG) plating was applied to Cu electrodes bonded to ceramic substrates. Forming a Pd/Ni electroplating layer on the surface of thermoelectric elements and an ENIG plating layer on the surface of the Cu electrode improved the bonding strength by approximately 3.5 times. When the Pd/Ni and ENIG plating layers were formed on Bi-Te elements and Cu substrates, respectively, the solderability greatly increased; as the solderability increased, the thickness of the diffusion layer formed with the solder layer increased. The improved bonding strength of the Pd/Ni plated thermoelectric element bonded on the ENIG plated substrate is attributed to the enhanced solderability due to the rapid inter-diffusion of Pd and Au into the solder layer and the formation of a stable and non-defected solder reaction interface layer.
A dense nanostructured 2HfB₂-SiC composite was simultaneously synthesized and consolidated by the pulsed current activated sintering method in one step within very short time (two minutes) from mechanically activated 2Hf, B₄C and Si powders. Simultaneous combustion synthesis and consolidation were achieved through the combination of the effects of the pulsed current and mechanical pressure. A highly dense 2HfB₂-SiC composite with 97.5% relative density was achieved under the simultaneous application of a pressure of 80 MPa and the pulsed current. The fracture toughness of the 2HfB₂-SiC composite was higher than that of monolithic HfB₂.
A new solid solution, (1-x)Bi0.5Na0.5TiO₃+xBaCoO3-δ materials, was fabricated using the sol-gel method. X-ray diffraction showed that the crystal structure of the compound exhibited rhombohedral symmetry and is similar to the crystal structures of host Bi0.5Na0.5TiO₃ materials. Distortions in the structures and reduction in the optical band gaps of the Bi0.5Na0.5TiO₃ materials were possibly due to the random incorporation of Ba and Co cations into host lattice materials. The magnetic properties of the Bi0.5Na0.5TiO₃ materials were tuned by controlling the concentrations of BaCoO3-δ as the solid solution. We expect that our work will provide valuable information on current methods for integrating ferromagnetic properties into lead-free ferroelectric materials for the development of multiferroic materials.
Hierarchical nanoparticles are of great interest because they possess unique physicochemical properties and multiple functionalities, providing a wealth of possibilities for various applications. In this work, we have developed a well-designed method to prepare hierarchical magnetic nanoparticles Fe₃O₄@mSiO₂@CS by integrating a solvothermal method for synthesizing the Fe₃O₄ core, a dualtemplating micelle system for preparing a layer of mesoporous silica (mSiO₂) shell, and a silane coupling method via γ-glycidoxypropyltrimethoxysilane for binding a chitosan (CS) layer on the silica surface. The porous hierarchical nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering nanoparticle size analyzer, and specific surface area and pore size analyzer. The loading capacity and the release behavior of the as-prepared nanoparticles for doxorubicin hydrochloride were studied, and it was found that the drug release rate was faster at pH 6.0 than at pH 7.4, revealing the pH-responsive property of the nanoparticles.
This research aimed to prepare 166Dy₂O₃-iPSMA/166Ho₂O₃-iPSMA nanoparticles (166Dy₂O₃/166Ho₂O₃-iPSMA NPs) and assess the radiation absorbed dose produced by the nanosystem to hepatic cancer cells by using experimental in vitro and in vivo biokinetic data. Dy₂O₃NPs were synthesized and functionalized with the prostate-specific membrane antigen inhibitor peptide (iPSMA). Fourier transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM), dynamic light scattering (DSL) and zeta potential analyses indicated the formation of Dy₂O₃-iPSMA NPs (46.11 ± 13.24 nm). After neutron activation, a stable 166Dy₂O₃/166Ho₂O₃- iPSMA nanosystem was obtained, which showed adequate affinity to the PSMA receptor in HepG2 cancer cells (Kd = 9.87 ± 2.27 nM). in vitro studies indicated high 166Dy₂O₃/166Ho₂O₃-iPSMA internalization in cancer cells, with high radiation doses to cell nuclei (107 Gy) and cytotoxic effects, resulting in a significant reduction in HepG2 cell viability (decreasing to 2.12 ± 0.31%). After intratumoral administration in mice, the nanosystem biokinetic profile indicated significant retention into the tumoral mass, producing ablative radiation doses (>70 Gy).
A ratiometric fluorescent deoxyribonucleic acid probe was synthesized using the photoinduced electron transfer mechanism, involving the interactions between different fluorescent components and electron acceptors. Double-emission carboxyl functionalized semiconducting polymer dots were synthesized using the nanoprecipitation method and applied as the flurophore, while methylene blue was used as the electron acceptor. Photoinduced electron transfer between different polymer dots components and methylene blue can achieve ratiometric modulation of the overall fluorescence in the system. The addition of deoxyribonucleic acid restores the fluorescence intensity, because the stronger interactions between deoxyribonucleic acid and methylene blue results in methylene blue being separated from the polymer dots. Under the optimized experimental conditions, system fluorescence was restored to its maximum when the concentration of deoxyribonucleic acid reached 200 nM, the linear range was 0.006-200 nM (R² = 0.995). This probe was reasonably free from interference, showing a good response to deoxyribonucleic acid, with strong application data from actual samples.
In the present study, we aimed to investigate the catalytic role of the newly reported MCM-41 -based nanocomposite in which the low acidity of this mesoporous moiety was favourably improved via the stabilization of zirconium nanoparticles and was magnetized to make a facile work-up procedure as an applicable and efficient method. The prepared Fe₃O₄@MCM-41 @ZrCI₂ nanocomposite was successfully characterized using different analyses and then it was favourably exploited for the synthesis of spirooxindoles as the most prominent spiro compounds. As predicted, Fe₃O₄@MCM- 41 @ZrCI₂ showed considerable efficiency in the promotion of the studied reaction.
The Zn₃V₃O8 was synthesized by solvothermal method combined with heat treatment using Zn(NO₃)₃ · 6H₂O and NH₄VO₃ as raw materials. The Zn₃V₃O8 was doped by Co2+ to form Zn2.88Co0.12V₃O8. The samples were characterized by X-ray diffraction and scanning electron microscopy techniques. Electrochemical tests showed that the initial discharge specific capacity for Zn2.88Co0.12V₃O8 was 640.4 mAh·g-1 when the current density was 100 mA·g-1, which was higher than that of pure Zn₃V₃O8 (563.5 mAh · g-1). After 80 cycles, the discharge specific capacity of Zn2.88Co0.12V₃O8 could maintain at 652.2 mAh · g-1, which was higher than that of pure Zn₃V₃O8 (566.8 mAh·g-1) under same condition. The Zn2.88Co0.12V₃O8 owned better rate performances than those of pure Zn₃V₃O8 also. The related modification mechanisms were discussed in this paper.
The design of efficient, stable, durable and noble metal free electro catalysts for oxygen evolution reaction (OER) are of immediate need, but very challenging task. In this study, iron induction into cobalt oxide (Co₃O₄) has resulted composite structure by wet chemical method. The iron impurity has brought an electronic disorder into Fe₃O₄/cobalt oxide composite thereby efficient oxygen evolution reaction is demonstrated. An addition of iron content into composite resulted the alternation of morphology from Nano rods to clusters of nanoparticles. The successive addition of iron into composite system reduced the onset potential of OER as compared to the pristine cobalt oxide. A Tafel slope of 80 mVdec-1 indicates the favorable oxygen evolution reaction kinetics on the sample 4. An over-potential of 370 mV is required to reach a 10 mAcm-2 current density which is acceptable for a nonprecious catalyst. The catalyst is highly durable and stable for 30 hours. Electrochemical impedance spectroscopy further provided a deeper insight on charge transfer resistance and sample 4 has low charge transfer resistance that supported the OER polarization curves. The sample 4 has more electrochemical active surface area of 393.5 cm². These obtained results are exciting and highlighting the importance of composite structure and leave a huge space for the future investigations on composite materials for energy related applications.
In order to explore the effect of nanobubble-based ultrasound imaging technology on the treatment of ureteral stenosis, a total of 120 patients, who were confirmed as ureteral stenosis by surgery, pathology or multiple imaging examinations at a designated hospital of the study from December 2015 to December 2018, were selected as research objects and were divided into three groups of targeted nanobubble (TN) group, blank nanobubble (BN) group and control (CT) group with 40 cases in each group. The TN group utilized the nanobubbles with a particle size of (499.52±72.87) nm as carriers to compare and analyze patients’ ultrasound images for the predisposition and etiology of ureteral stenosis and the sonogram variations of hydronephrosis, renal pelvis; the BN group utilized the blank nanobubble with a particle size of (446.71±45.36) nm as carriers to perform ultrasound imaging and diagnostic analysis of ureteral stenosis; the CT group directly conducted ureteral stenosis treatment with ultrasound imaging technology. The results showed that the total coincidence rates of the targeted diagnosis for ureteral stenosis of the TN, BN and CT group were 94.38%, 87.52%, and 67.94%, respectively; the coincidence rates of different examination methods for different diagnostic parts were different and the diagnostic coincidence rates of TN group for pelvic ureteral transition area, end of ureter, and the area between pelvic ureteral transition area and end of ureter were 82.91%, 79.66%, and 75.17%, respectively; the diagnostic coincidence rates of BN group for those were 80.32%, 94.77%, respectively and 92.18% and the CT group were 58.66%, 72.14%, and 66.48%, respectively; the diagnosis coincidence rates for ureteral stenosis etiology of the TN, BN and CT group were 93.81%, 82.66% and 64.57%, respectively. Therefore, it was believed that the nanobubble-based ultrasound examination can accurately diagnose the site of ureteral stenosis through the exploration of hydronephrosis and ureteral dilatation with the advantages of simplicity, no pain, repeatable examination, and no impact on renal function, and having high clinical value for diagnosing ureteral stenosis.
A cerium-doped YAG (Y₃Al5O12) phosphor is used as a rare-earth element phosphor for blue light absorption and yellow light emission for a white light source. A solution combustion synthesis, which is a method for producing nano-powder, is a reaction that is spontaneous ignition by reaction heat released through oxidation/reduction reaction between metal nitrate and fuel. Since the reaction speed is fast and it does not go through a separate firing process, it is a method of easily synthesizing nano-powder by simple process. In this study, YAG:Ce nano-powders were prepared by using various fuels in the combustion synthesis method. Depending on the kind of the additive fuel, the reaction of the combustion synthesis process was different, and the shape of the powder particles according to the fuels was also different. The agglomerated particles of nanoparticles were observed and the characteristics of YAG:Ce powders synthesized under various conditions were analyzed.
In this study, microstructure and sintering behaviors of the gas-atomized Al-(25 or 30) Cr-xSi alloy (x = 5, 10 and 20 at.%) during spark plasma sintering (SPS) process were investigated. Gas-atomized alloy powders were manufactured using Ar gas atomizer process. These alloy powders were consolidated using SPS process at different temperature under pressure 60 MPa in vacuum. Microstructures of the gas-atomized powders and sintered alloys were analyzed using scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometer (EDS), and transmission electron microscopy (TEM). Hardness of the SPS sintered alloys was measured using micro Vickers hardness tester. The Al-Cr-Si bulks with high Cr and Si content were produced successfully using SPS sintering process without crack and obtained fully dense specimens close to nearly 100% T. D. (Theoretical Density). The maximum values of the hardness were 834 Hv for the sintered specimen of the gas atomized Al-30Cr-20Si alloy. Enhancement of hardness value was resulted from the formation of the multi-intermetallic compound with the hard and thermally stable phases and fine microstructure by the addition of high Cr and Si.
The corrosion mechanisms for different corrosive media on the aged 7A46 aluminum alloy were systematically investigated at nanoscale level. The combination of empirical intergranular and exfoliation corrosion behavior was employed, and coupled with first-principles calculations. Results revealed that the dispersed distribution of matrix precipitates (MPs) leads to the enhancement of the corrosion resistance pre-ageing (PA) followed by double-ageing (PA-DA) alloy. The deepest corrosion depth of PA-DA alloy was in hydrochloric acid, and the calculation result demonstrates that the passivation effect in combination with the accumulation of corrosion products in nitric acid protect the PA-DA alloy from further corrosion.
This paper studies the characteristics and controlling factors of nanopores in organic-rich shale in the Niutitang Formation. Six samples were collected from the bottom of the formation at the Jiumen Outcrop, Guizhou Province. Experiments were conducted to investigate the pore structures of these high-maturity shale samples. The TOC contents vary between 4.81-17.51% with an average of 10.18%. The XRD data show that these samples are dominated by quartz (44%-71%), with a significant amount of clay minerals, such as illite, with a content of 8%-27.5%. Based on the low-pressure liquid N₂ sorption measurements, the pore structures can be divided into two groups. Group A including samples of N-2, N-3 and N-4, mainly develop slit-shaped pores, mesopores and macropores. Group B shown from samples N-1, N-5 and N-6, are mainly composed of narrow slitlike pores, which may provide more space for shale gas than slit-shaped pores. The mesopores, macropores, porosity and specific surface areas of group B are more developed than those of group A. With the comparison of pore structures in shales with various organic matter and mineral contents, the dissolution of quartz and feldspar can be the important factor controlling pore development. The evolution of diagenesis is closely related to pore evolution. This diagenesis has various types and complex effects on the pores, mainly including compaction, dissolution and cementation.
The mineral characteristics (occurrence, type, and content) of low-rank coal and their influence on coalbed methane (CBM) reservoirs are investigated at the micro- and nanoscales. Six coal samples of three representative coalmines were used to demonstrate the uniform tectonization from the Zhundong coalfield, NW China. Based on optical microscopy and scanning electron microscopyenergy dispersive spectrum (SEM-EDS) analysis, the mineral composition and occurrence characteristics were discussed. The micro- and nanoscale reservoir characteristics in low-rank coal (pore size distribution and adsorption capability) were studied by diverse methods, including lowtemperature N₂ adsorption/desorption, mercury intrusion porosimetry and CH₄ isotherm adsorption analysis. The coal reservoir nuclear magnetic T₂ spectra of porosity and movable fluid were obtained by combining low-field nuclear magnetic resonance (NMR) analysis, which has an advantage of determining pore fluid technology. The mineral content is highly variable (4˜16 vol.%) in the Xi Heishan prospecting area of the Qitai region. Kaolinite, goyazite, ankerite and anorthosite were microscopically observed to be filling in coal pores and microfractures, and the minerals are given priority to silicate minerals. There is a greater content of mesopores (100-1000 nm) and transition pores (10-100 nm), and they are well connected. The micropores (0-10 nm) are dominated by parallel plate, closed or wedge-shaped pores. Furthermore, the microfractures are mainly observed for types B (width ≥ 5 μm and length≤ 10 mm) and D (width<5 μm and length<300 μm). The results show that microfractures B and C (width< 5 μm and length ≥ 300 μm) are better connected, but the orientation and connectivity of type D are worse. The Langmuir volume and mesopore content decreased with increasing mineral content, which shows that the low-rank coal minerals filled some adsorption space; the reduced CBM adsorption capacity and cellular pore and intergranular pore filled with minerals affect the mesopore content. Therefore, mineral characterization significantly influences methane adsorption capacity and pore structure.
We investigate the effect of a semiconducting organic buffer layer (SOBL) on the injection and transport of charges in organic field-effect transistors (OFETs). Here, two different injection barriers at the source/organic semiconductor interface are respectively studied with the aid of a numerical simulation: one is intermediate (0.4 eV), and the other is large energy barriers (0.6 eV). The introduction of nanostructure buffer layer, or SOBL, exhibits the decrease of potential loss at the contact interfaces, improving the electrical performance of the OFETs. It is also found that the energy level as well as the mobility of the SOBL plays an important role in determining the injection properties at the metal/organic hetero-interfaces and thus improving the device performance. Our systematic investigation on the injection barrier by the introduction of the nanostructure buffer layer will provide a useful guideline for the fabrication of high-performance FETs with molecular semiconductors.
Bio-functionalized nanomaterials represent the cutting-edge research for a sensing biomolecules in nano-systems. Their physicochemical properties of porous silicon bring along advantages in sensing applications. Here, a modified biosensor based on the anti-C-reactive protein-modified porous silicon Bragg stack interferometer was developed to detect C-reactive protein. The SEM images of the surface and cross-sectional views of the Bragg stack porous silicon exhibited the pore sizes in the 10-20 nm range. The fabrication, optical characterization, and surface derivatization of the interferometer were also reported. This sensor was assessed by measuring the reflection peaks in the white light reflection spectrum. As a result, molecular binding was detected as a shift in the wavelength of these reflection peaks. In addition, a dramatic decrease in the reflectivity was observed in the reflectivity spectrum within 10 s, thereby indicating a C-reactive protein detection limit of 100 pM.
