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The distribution and subcellular localization of toxic metal ions in plant tissues are of great significance for plants to cope with metal stresses, which could provide valuable insights into the mechanisms underlying plant metal tolerance. To explore the distribution of aluminum (Al) at the subcellular level after entering Pinus massoniana, four aluminum concentrations of 0, 0.5, 1.0, 2.0 mmol·L-1 were set up in this study. The growth status of P. massoniana and the distribution characteristics of aluminum at the subcellular level under different Al concentrations were studied by pot experiment. The results were as follows: (1) P. massoniana exhibited significant growth enhancement under 0.5 mmol·L-1 Al treatment, and the biomass, seedling height, root length, as well as the number of lateral roots were all significantly promoted. However, higher Al concentrations (≥1 mmol·L-1) led to diminished growth promotion effects and inhibited root growth and cell viability in P. massoniana root tips. (2) Translocation of Al from roots to shoots in P. massoniana was limited. The absorbed Al was mainly deposited in the roots (P

In acid soil, aluminum (Al) toxicity is one of the main factors limiting agricultural output. As is known to all, the cell wall is the first line of defense against metals that serves as a significant target of Al toxicity and also is crucial for Al detoxification. However, nothing is known about how this process is transcriptionally regulated. Here, we describe recent findings to understand the role of two kinds of transcription factors in regulating the cell wall composition and modification in response to Al stress in Arabidopsis thaliana. ANAC017 encodes a NAM, ATAF1/2, and cup-shaped cotyledon 2 (NAC) transcription factor, loss function of ANAC017 enhanced Al tolerance with the decreased Al content and xyloglucan content in the cell wall. Next, we characterized one xyloglucan endotransglucosylase/hydrolase (XTH), XTH31, which is previously reported to participate in Al stress, acted downstream of ANAC017 to regulate Al tolerance in Arabidopsis. In addition, we also identified MYB103, an R2R3-type transcription factor. MYB103 disruption caused Al sensitivity, and myb103 mutants’ xyloglucan had a high O-acetylation level. Additionally, it was discovered that TRICHOME BIREFRINGENCE-LIKE27 (TBL27), which is in charge of xyloglucan’s O-acetylation, functions downstream of MYB103 through the direct binding of the MYB103 to the promoter of the TBL27 to influence Arabidopsis’s sensitivity to Al. In summary, our research showed that two distinct molecular modules modulate Arabidopsis cell wall composition and modification to positively influence Al resistance.

Considering the challenges faced when joining multi-materials where welding is not possible, such as with polymers and metal, adhesives can be used to bond them. In this study, two chemically different adhesives, namely epoxy and silicone, were used to bond PVC/Al. Infrared spectra of a mixed adhesive revealed the presence of overlapping peaks with PVC, namely -CH2, -CH3 around 2800-3000 cm [ABSTRACT FROM AUTHOR]

In this research, Al-B4C functionally graded materials (FGMs) with a continuously gradient distribution of B4C in an aluminum matrix having three different composition ratios, namely Al-98 vol.% + B4C-2 vol.%, Al-96 vol.% + B4C-4 vol.%, and Al-94 vol.% + B4C-6 vol.%, were fabricated by a novel method of sound-wave-assisted vibrational casting methodology comprising of a specifically designed mechanical vibration-assisted casting setup. The distribution of B4C-reinforcing particles in the Al matrix and the influence of B4C on the microstructure and properties of the Al-B4C FGMs were investigated. The processing of such an engineered material with spatially varying properties to optimize performance through the gradual distribution of reinforcing particles was accomplished by the fluidization of particles in a liquid medium (molten Al) via the generation of Faraday waves at the thin bottom of the mold by vertical vibration of a specific amplitude and frequency and wave exposure time. According to the dispersion of B4C in the Al matrix, the microstructure of samples fabricated in three different locations exhibited fairly good gradient changes, and variations in the micro-hardness were also observed. The average micro-hardness (HV) of FGMs so produced exhibits a gradual change in hardness from 37 HV in inner (A) region to 347 HV in outer (C) region. The present work provides flexibility in controlling the numerous spatially varying patterns of reinforcement dispersion in a molten metal bath to obtain the desired microstructure of FGMs. [ABSTRACT FROM AUTHOR]

A multispectral camera records image data in various wavelengths across the electromagnetic spectrum to acquire additional information that a conventional camera fails to capture. With the advent of high-resolution image sensors and color filter technologies, multispectral imagers in the visible wavelengths have become popular with increasing commercial viability in the last decade. However, multispectral imaging in longwave infrared (LWIR, 8–14 μm) is still an emerging area due to the limited availability of optical materials, filter technologies, and high-resolution sensors. Images from LWIR multispectral cameras can capture emission spectra of objects to extract additional information that a human eye fails to capture and thus have important applications in precision agriculture, forestry, medicine, and object identification. In this work, we experimentally demonstrate an LWIR multispectral image sensor with three wavelength bands using optical elements made of an aluminum (Al)-based plasmonic filter array sandwiched in germanium (Ge). To realize the multispectral sensor, the filter arrays are then integrated into a three-dimensional (3D) printed wheel stacked on a low-resolution monochrome thermal sensor. Our prototype device is calibrated using a blackbody and its thermal output has been enhanced with computer vision methods. By applying a state-of-the-art deep learning method, we have also reconstructed multispectral images to a better spatial resolution. Scientifically, our work demonstrates a versatile spectral thermography technique for detecting target signatures in the LWIR range and other advanced spectral analyses. [ABSTRACT FROM AUTHOR]

The processes at the interface between ionic liquids (ILs) and metals are a key factor for understanding especially in electrochemical deposition, nanoscale tribology applications and batteries. In the present work, the interfaces of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Py1,4]TFSI) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]TFSI) and platinum and aluminum were investigated by depositing thin IL films and studying them with X-ray photoelectron spectroscopy (XPS) in ultrahigh vacuum. It is found that there is no evidence of a decomposition reaction of either IL on platinum; however, the imidazolium cation of [EMIm]TFSI shows a strong interaction with the surface in the monolayer regime. In contrast, [Py1,4]TFSI and [EMIm]TFSI show massive decomposition on the aluminum surface without applying any electrochemical potential. The spectra for the [TFSI]− anion components show cleavage of C-F or N-S bonds in both cases. Both cleavage of a single fluorine atom and complete cleavage were observed, leading to further decomposition reactions of the anion. Consequently, new components such as AlOOH, Al(OH)3, Al2S3, Al2(SO4)3 and AlF3 appear at the interface. In addition, there is also evidence of decomposition of the cation by the splitting off hydrogen atoms or parts of the alkyl chain in both ILs. [ABSTRACT FROM AUTHOR]

The resistance spot welding (RSW) method was used to join aluminum alloy AA 1050 and copper alloy UNS C50100 sheets. Mechanical properties of the joints were examined. The influence of welding process parameters on tensile shear force of the joints was discussed. The design of experiments (DOE) method was used to analyze the influence of welding parameters on the mechanical properties of the joints. Three RSW parameters were used: welding current, squeeze time, and welding time. The results showed that the joint shear stress increased with increasing the welding current until a value of 12000 Amp. Then the shear stress decreased. The tensile shear stress increased with increasing the welding and squeeze time. As a consequence, it can be possible to weld copper with aluminum by RSW.

Aluminum (Al) excess and hypercholesterinaemia are established risks of Alzheimer's disease (AD). The aim of this study was to establish an AD-resembling hypercholesterinaemic animal model—with the involvement of 8 week and 48 week-old Fischer-344 rats—by Al administration for the safe and rapid verification of β-amyloid-targeted positron emission tomography (PET) radiopharmaceuticals. Measurement of lipid parameters and β-amyloid–affine [11C]C-Pittsburgh Compound B ([11C]C-PIB) PET examinations were performed. Compared with the control, the significantly elevated cholesterol and LDL levels of the rats receiving the cholesterol-rich diet support the development of hypercholesterinaemia (p ≤ 0.01). In the older cohort, a notably increased age-related radiopharmaceutical accumulation was registered compared to in the young (p ≤ 0.05; p ≤ 0.01). A monotherapy-induced slight elevation of mean standardised uptake values (SUVmean) was statistically not significant; however, adult rats administered a combined diet expressed remarkable SUVmean increment compared to the adult control (SUVmean: from 0.78 ± 0.16 to 1.99 ± 0.28). One and two months after restoration to normal diet, the cerebral [11C]C-PIB accumulation of AD-mimicking animals decreased by half and a third, respectively, to the baseline value. The proposed in vivo Al-induced AD-resembling animal system seems to be adequate for the understanding of AD neuropathology and future drug testing and radiopharmaceutical development. [ABSTRACT FROM AUTHOR]

Considering the challenges faced when joining multi-materials where welding is not possible, such as with polymers and metal, adhesives can be used to bond them. In this study, two chemically different adhesives, namely epoxy and silicone, were used to bond PVC/Al. Infrared spectra of a mixed adhesive revealed the presence of overlapping peaks with PVC, namely –CH2, –CH3 around 2800–3000 cm−1 and Si–CH3 at 1260 cm−1. Mechanical testing on single-lap shear specimens of PVC/Al prepared using mixed adhesive showed the enhancement in the adhesive strength was ~5 times higher compared to the adhesive strength of PVC/Al joints made with only silicone adhesive.

The structural, electronic, and quantum transport properties of Al/P co-doped disconnected armchair silicene nanoribbons (ASiNRs) with Al and P atoms are explored using first-principles calculations. The structural properties reveal that the co-doping with Al and P in disconnected nanoribbons is structurally stable. The current findings show that the electronic and transport characteristics are greatly influenced by doping position. Interestingly, the transport characteristics of pristine disconnected ASiNR based device are found to be similar to pristine ASiNR device. Here, it is also worth mentioning that the co-doped disconnected two-probe ASiNR devices show remarkable nonlinear current-voltage characteristics, this pledges for their potential employment as rectifiers, oscillators, etc. For co-doped disconnected ASiNRs devices, the computed rectification ratio (RR) and reverse rectification ratio (RRR) are 86.49 and 36, respectively. The intriguing rectifying mechanism can be elucidated by the localized and delocalized frontier orbitals, as well as the modulation of the transmission spectra with the supply voltage. The observed RR suggests that the co-doped disconnected ASiNRs could be used in futuristic ultra low power nanoscale nano-switching devices. [ABSTRACT FROM AUTHOR]

All animals, other than Platyhelminthes, produce eggs containing yolk, referred to as "entolecithal" eggs. However, only Neoophora, in the phylum Platyhelminthes, produce "ectolecithal" eggs (egg capsules), in which yolk is stored in the vitelline cells surrounding oocytes. Vitelline cells are derived from vitellaria (yolk glands). Vitellaria are important reproductive organs that may be studied to elucidate unique mechanisms that have been evolutionarily conserved within Platyhelminthes. Currently, only limited molecular level information is available on vitellaria. The current study identified major vitellaria-specific proteins in a freshwater planarian, Dugesia ryukyuensis, using peptide mass fingerprinting (PMF) and expression analyses. Amino acid sequence analysis and orthology analysis via OrthoFinder ver.2.3.8 indicated that the identified major vitellaria-specific novel yolk ferritins were conserved in planarians (Tricladida). Because ferritins play an important role in Fe (iron) storage, we examined the metal elements contained in vitellaria and ectolecithal eggs, using non-heme iron histochemistry, elemental analysis based on inductively coupled plasma mass spectrometry and transmission electron microscopy– energy-dispersive X-ray spectroscopy analysis. Interestingly, vitellaria and egg capsules contained large amounts of aluminum (Al), but not Fe. The knockdown of the yolk ferritin genes caused a decrease in the volume of egg capsules, abnormality in juveniles, and increase in Al content in vitellaria. Yolk ferritins of D. ryukyuensis may regulate Al concentration in vitellaria via their pooling function of Al and protect the egg capsule production and normal embryogenesis from Al toxicity. [ABSTRACT FROM AUTHOR]

In this study, a thick film copper-nickel alloy (Cu-Ni alloy) was fabricated by using a novel technique which combines thick film process and galvanic chemical replacement. First, a thick film Al electrode was screen printed and sintered at 600 °C on the aluminum oxide (Al2O3) substrate which served as a reactant. Sequentially, the Al electrode on Al2O3 substrate was immersed into a copper sulfate (CuSO4) solution at 40 °C for 15–30 min to carry out the first galvanic replacement reactions of the partial Al electrode into Cu. After which it was immersed into an NiSO4 solution 80 °C for 15 min to carry out the second galvanic replacement reactions of the remaining Al electrode into Ni to form Cu-Ni layers on the Al2O3 substrate. To make a thick film Cu-Ni alloy, the Cu-Ni layers on Al2O3 substrate were annealed at high temperatures for interdiffusion of Cu and Ni. A thick film Al electrode on an Al2O3 substrate is immersed into a CuSO4(aq) solution at 40 °C for 15 min and sequentially immersed in an NiSO4(aq) solution at 80 °C for 15 min. Then, after further annealing at 800 °C for 30 min in a reducing atmosphere, the Cu and Ni composition ratio in the thick film Cu-Ni alloy is approximately 1:1, reflecting Cu-Ni alloy resistor with a very promising temperature coefficient of resistance (TCR) performance (115 ppm/°C). [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity is considered to be the most harmful abiotic stress in acidic soils that today comprise more than 50% of the world’s arable lands. Barley belongs to a group of crops that are most sensitive to Al in low pH soils. We present the RNA-seq analysis of root meristems of barley seedlings grown in hydroponics at optimal pH (6.0), low pH (4.0), and low pH with Al (10 μM of bioavailable Al3+ ions). Two independent experiments were conducted: with short-term (24 h) and long-term (7 days) Al treatment. In the short-term experiment, more genes were differentially expressed (DEGs) between root meristems grown at pH = 6.0 and pH = 4.0, than between those grown at pH = 4.0 with and without Al treatment. The genes upregulated by low pH were associated mainly with response to oxidative stress, cell wall organization, and iron ion binding. Among genes upregulated by Al, overrepresented were those related to response to stress condition and calcium ion binding. In the long-term experiment, the number of DEGs between hydroponics at pH = 4.0 and 6.0 were lower than in the short-term experiment, which suggests that plants partially adapted to the low pH. Interestingly, 7 days Al treatment caused massive changes in the transcriptome profile. Over 4,000 genes were upregulated and almost 2,000 genes were downregulated by long-term Al stress. These DEGs were related to stress response, cell wall development and metal ion transport. Based on our results we can assume that both, Al3+ ions and low pH are harmful to barley plants. Additionally, we phenotyped the root system of barley seedlings grown in the same hydroponic conditions for 7 days at pH = 6.0, pH = 4.0, and pH = 4.0 with Al. The results correspond to transcriptomic data and show that low pH itself is a stress factor that causes a significant reduction of root growth and the addition of aluminum further increases this reduction. It should be noted that in acidic arable lands, plants are exposed simultaneously to both of these stresses. The presented transcriptome analysis may help to find potential targets for breeding barley plants that are more tolerant to such conditions.

Aluminum (Al) toxicity is considered to be the most harmful abiotic stress in acidic soils that today comprise more than 50% of the world's arable lands. Barley belongs to a group of crops that are most sensitive to Al in low pH soils. We present the RNA-seq analysis of root meristems of barley seedlings grown in hydroponics at optimal pH (6.0), low pH (4.0), and low pH with Al (10 μM of bioavailable Al3+ ions). Two independent experiments were conducted: with short-term (24 h) and long-term (7 days) Al treatment. In the short-term experiment, more genes were differentially expressed (DEGs) between root meristems grown at pH = 6.0 and pH = 4.0, than between those grown at pH = 4.0 with and without Al treatment. The genes upregulated by low pH were associated mainly with response to oxidative stress, cell wall organization, and iron ion binding. Among genes upregulated by Al, overrepresented were those related to response to stress condition and calcium ion binding. In the long-term experiment, the number of DEGs between hydroponics at pH = 4.0 and 6.0 were lower than in the short-term experiment, which suggests that plants partially adapted to the low pH. Interestingly, 7 days Al treatment caused massive changes in the transcriptome profile. Over 4,000 genes were upregulated and almost 2,000 genes were downregulated by long-term Al stress. These DEGs were related to stress response, cell wall development and metal ion transport. Based on our results we can assume that both, Al3+ ions and low pH are harmful to barley plants. Additionally, we phenotyped the root system of barley seedlings grown in the same hydroponic conditions for 7 days at pH = 6.0, pH = 4.0, and pH = 4.0 with Al. The results correspond to transcriptomic data and show that low pH itself is a stress factor that causes a significant reduction of root growth and the addition of aluminum further increases this reduction. It should be noted that in acidic arable lands, plants are exposed simultaneously to both of these stresses. The presented transcriptome analysis may help to find potential targets for breeding barley plants that are more tolerant to such conditions. [ABSTRACT FROM AUTHOR]

Aluminum and indium codoping zinc oxide (AIZO) films have been deposited simultaneously on polyethylene terephthalate (PET) substrate by radio frequency (RF) magnetron sputtering technique at room temperature (from a ceramic target) prepared with a mixture of zinc oxide (ZnO), aluminum (Al), and indium oxide (In2O3) of varying RF power range from 50 to 100 W and working pressure range from 2.5 to 15 mTorr. In order to obtain an acceptable performance rate with high-quality conducting thin films, the effect of correlation between the electrical, optical, and microstructural properties was investigated. The electrical resistivity significantly declined, and the carrier concentration improved as a result of In2O3 and Al incorporation within the ZnO and the increasing RF power. In this case, the best optical and electrical results were deposited at the RF power of 100 W with the working pressure of 2.5 mTorr. We were practicable to fabricate AIZO/PET electrodes of the lowest resistivity ($7.6\times 10^{-3}\,\Omega $ -cm), the highest mobility, carrier concentration ($8.29\times 10^{3}$ cm2/vs and $9.8\times 10^{20}$ cm−3, respectively), and the maximum transmittance (83%–96%) along an energy bandgap range of 3.3–3.65 eV with a well crystalline structure showing a roughness surface of the AIZO films and a suitable Herzberg–Teller (HT). Thus, according to these expressions, we could be responsible for preparing AIZO/PET with improved electrical property and microstructure of great applications for flexible electronic devices. [ABSTRACT FROM AUTHOR]

Titanium filaments were prepared by the extraction of powder metallurgy fabricated aluminum + titanium composite in sodium hydroxide solution. During the hot extrusion consolidation process, ultrafine aluminum powder particles heavily deformed the titanium powder particles into the titanium filaments of high aspect ratio and micrometric size, which were homogeneously embedded and arrayed in the aluminum matrix. The microstructure and chemistry of extracted titanium filaments were characterized in detail. For the demonstration purpose, the titanium filaments were sintered into a porous material. [ABSTRACT FROM AUTHOR]

Pigeonpea is an important economic crop in the world and is mainly distributed in tropical and subtropical regions. In order to further expand the scope of planting, one of the problems that must be solved is the impact of soil acidity on plants in these areas. Based on our previous work, we constructed a time series RNA sequencing (RNA-seq) analysis under aluminum (Al) stress in pigeonpea. Through a comparison analysis, 11,425 genes were found to be differentially expressed among all the time points. After clustering these genes by their expression patterns, 12 clusters were generated. Many important functional pathways were identified by gene ontology (GO) analysis, such as biological regulation, localization, response to stimulus, metabolic process, detoxification, and so on. Further analysis showed that metabolic pathways played an important role in the response of Al stress. Thirteen out of the 23 selected genes related to flavonoids and phenols were downregulated in response to Al stress. In addition, we verified these key genes of flavonoid- and phenol-related metabolism pathways by qRT-PCR. Collectively, our findings not only revealed the regulation mechanism of pigeonpea under Al stress but also provided methodological support for further exploration of plant stress regulation mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, the feasibility of an innovative surface alloying technique was successfully demonstrated in which Cr-Al alloying layer was fabricated on an Al substrate by high current pulsed electron beam (HCPEB) to enhance the surface properties. The microstructures of the alloying layer were investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The microhardness and corrosion resistance were also examined. After surface alloying by HCPEB irradiation, a mixture of Al and Cr elements was formed, which generated a Cr-Al alloying layer on the surface of Al substrate. Meanwhile, abundant nanostructured intermetallic compounds, such as Al 8 Cr 5 , AlCr 2 and Al 13 Cr 2 , together with ultrafine Cr particles and Al (Cr) solid solution, were also formed in the alloying layers. In addition, both the microhardness and corrosion resistance were dramatically improved due to the addition of Cr element and the modified layer microstructure. • The Cr-Al alloying layer was obtained on Al substrate under HCPEB irradiation. • Cr particles were dissolved into Al matrix to form an alloying layer. • Intermetallic phase and Al (Cr) solid solution were formed in the alloying layers. • The microhardness and corrosion resistance were increased by HCPEB irradiation. [ABSTRACT FROM AUTHOR]

An analytical and experimental study of nanofilm aluminum (Al) for ultra-high dynamic range surface plasmon resonance (SPR) biosensor is presented in this article. A thin film of 16 nm Al is proposed for metallic sensing layer for SPR sensor. For the protective layer, a 10 nm of gold (Au) layer was configured on top of Al as a protection layer. This ultra-high dynamic range of SPR biosensor reached the bulk refractive index sample limit up to 1.45 RIU. For the analytical study, with the assumption of anisotropic refractive indices experiment, the dynamic range showed a refractive index value of around 1.58 RIU. The refractive index value limit achieved by the proposed sensing design is potentially implemented in various applications, such as in chemical detection and environmental monitoring study with high refractive index solution sample. The experimental results are presented as a proof-of-concept of the proposed idea. [ABSTRACT FROM AUTHOR]

Cobalt and nickel have become important strategic resources because they are widely used for renewable energy technologies and rechargeable battery production. Cementation, an electrochemical deposition of noble metal ions using a less noble metal as an electron donor, is an important option to recover Co and Ni from dilute aqueous solutions of these metal ions. In this study, cementation experiments for recovering Co2+ and Ni2+ from sulfate and chloride solutions (pH = 4) were conducted at 298 K using Al powder as electron donor, and the effects of additives such as activated carbon (AC), TiO2, and SiO2 powders on the cementation efficiency were investigated. Without additives, cementation efficiencies of Co2+ and Ni2+ were almost zero in both sulfate and chloride solutions, mainly because of the presence of an aluminum oxide layer (Al2O3) on an Al surface, which inhibits electron transfer from Al to the metal ions. Addition of nonconductor (SiO2) did not affect the cementation efficiencies of Co2+ and Ni2+ using Al as electron donor, while addition of (semi)conductors such as AC or TiO2 enhanced the cementation efficiencies significantly. The results of surface analysis (Auger electron spectroscopy) for the cementation products when using TiO2/Al mixture showed that Co and Ni were deposited on TiO2 particles attached on the Al surface. This result suggests that conductors such as TiO2 act as an electron pathway from Al to Co2+ and Ni2+, even when an Al oxide layer covered on an Al surface.

The future applications of hyperbolic metamaterials demand stacks of materials with alternative ultra-thin conductive/dielectric films with good homogeneity of the thickness and reduced roughness level. In this work, the technology of pulsed-DC magnetron sputtering of aluminum was optimized using the Taguchi method in order to fabricate Al films with improved roughness level. The performed structural characterization proved the smaller Al domains and better homogeneity of the surface. The optimized process was used to fabricate a multilayer structure of Al/HfOx as the metamaterial media. The fabricated structures were optically characterized in the UV/VIS range. The presented findings demonstrated the tunability effect of the effective reflectance of the examined stacks. The presented results are promising for the future application of multilayer structures in novel photonic devices based on hyperbolic metamaterials.

Abstract The deformation and strengthening behavior of an ultra-fine grained (UFG) Al fabricated via powder metallurgy was investigated over a wide range of homologous temperatures (T H). Our results reveal that the presence of a high density of γ-Al 2 O 3 nanoparticles, located primarily at high angle grain boundaries (HAGBs), promoted remarkable stabilization of the Al grain structure up to T H = 0.94. The 0.2% strain offset yield stress (YS 0.2) of the materials annealed at 600 °C for 24 h with grain sizes (d 3D) of 0.57, 1.67, 2.33 and 2.99 μm was systematically studied from room temperature (RT) to 600 °C. Our study reveals that with decreasing d 3D the strain hardening ability of the materials gradually decreased, and this behavior became pronounced at elevated T , which was attributed to the onset of plastic instability. The YS 0.2 of the materials at all T followed the relation YS 0.2 = a + k d 3D −0.5. As determined on the basis of data interpolation, a positive transition from an established Hall-Petch (HP) relation at RT occurred at d 3D = ∼8 μm. As the parameter a was negative at RT and 300 °C the documented strength–structure relationship cannot be explained on the basis of a Hall-Petch relation. The γ-Al 2 O 3 particles located at HAGBs did not contribute notably to RT strengthening, whereas GBs played a significant role in the overall strength. The materials showed a high YS 0.2 up to a T H of 0.94. The YS 0.2 was observed to be linearly correlated with the reciprocal square root of the d 3D and the coefficient k followed k = 224.4–0.376 T relation. The HP model overestimated the YS 0.2 values at elevated T namely for the materials with a smaller d 3D. It is proposed that softening occurred as a result of the γ-Al 2 O 3 particles densely distributed within a 3D network, which were included in Hansen's strengthening model; particle strengthening played a role at elevated T. Highlights • Deformation and strengthening of a stable ultra and fine-grained Al at 25–600 °C. • Al grain structure effectively stabilized by a 3D network of Al 2 O 3 nanoparticles. • Yield stress at all temperatures shows a linear dependence with Al grain size. • A major contribution occurs due to grain boundary strengthening. • A strength–structure relationship that cannot be rationalized using Hall-Petch law. [ABSTRACT FROM AUTHOR]

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Abstract An aluminum material stabilized with a 1.6 vol% of nanometric Al 2 O 3 dispersoids, named HITEMAL, was fabricated by hot extrusion of a fine atomized Al powder. The Al 2 O 3 dispersoids stemmed from a native Al 2 O 3 films on an aluminum powder surface. An extruded rod of the material was then cold-deformed out into a thin wire by rotatory swaging, hydro extrusion and rolling. Such severely deformed HITEMAL was studied as a prospective outer sheath stabilizer material for MgB 2 core superconductor wires. An emphasis was put on the effect of annealing realized at various temperatures close to the melting point of Al, which is typically applied to form an in-situ MgB 2 superconductive core, on the mechanical and electrical properties of the HITEMAL wire. A systematic investigation was performed of changes to a severely deformed Al grain structure and Al 2 O 3 dispersoids upon annealing the as-deformed wire from 595 to 655 °C for 30 min. Mechanical and electrical properties of the wire were measured at room and cryogenic temperatures. The results showed that the ultrafine-grained Al + 1.6 vol% Al 2 O 3 wire exhibited advantageous properties, and surface integrity after annealing up to 642 °C. It is thus a lightweight material of choice for outer sheaths of MgB 2 superconductors. Graphical abstract Unlabelled Image Highlights • Al wire fabricated from a fine Al powder was studied as outer sheath material for lightweight MgB 2 superconductors. • The effect of annealing realized at 595-655 °C on microstructure, mechanical and electrical properties was investigated. • The as-rolled wire showed ultrafine-grained Al structure with 1.6% of nanometric Al 2 O 3 dispersoids dispersed in Al matrix. • The Al 2 O 3 dispersoids effectively stabilized Al grain structure during annealing, and only minor Al grain growth occurred. • Wires annealed up to 642 °C showed attractive strength and electrical resistivity at room and cryogenic temperatures. [ABSTRACT FROM AUTHOR]

SUMMARY: This paper reports low temperature hermetic wafer bonding using Al/Sn/Al/Sn/Al as a bonding layer. The Al surface of the bonding layer was oxidized in air, but hermetic sealing was demonstrated without surface treatment at 370 °C to 390 °C, which was lower than the maximum temperature of complementary metal oxide semiconductor (CMOS) backend process (400 °C). For the successfully sealed samples, the bonding layer was considerably compressed and squeezed, and the remaining thickness was only <16% of the initial one, that is, the reduction rate was >84%. On the other hand, the samples without Sn layers inserted, that is, using a pure Al bonding layer, were not hermetically sealed at similar temperatures, showing the reduction rate smaller than 70%. A clear correlation between the reduction rate and the yield of hermetic sealing was observed. Taking account of analytical results and Al‐Sn phase diagram, it is suggested that Al‐Sn liquid phase in Al grain boundaries enhances the grain slip deformation of the bonding layer and fractionates the surface Al oxide layer during the bonding process. The function of Sn for Al‐Al bonding suggested in this paper is useful for wafer‐level hermetic micro electro mechanical systems (MEMS) packaging at low temperature. [ABSTRACT FROM AUTHOR]

Using carbon nanotubes (CNTs) as a reinforcement in metal matrix composites (MMCs) is a concentrated topic for materials and processing design in the area of composites science. In this paper, we review our recent development on CNT reinforced powder metallurgy aluminum (Al) MMCs, including the significant issues of processing, microstructures and properties. Main findings on CNT dispersion, composite consolidation, interface microstructures and strengthening mechanisms are introduced. [ABSTRACT FROM AUTHOR]

Ti/Al/Mg impedance-graded material sheet is an alternative to the homogeneous single-layer sheets, which has been presented to improve shielding performance through the high efficient absorption and dissipation of fragment kinetic energy. Nevertheless, one limitation of the Ti/Al/Mg gradient material is associated with the weak Al/Mg interface. The purpose of this study is to investigation the interfacial bonding mechanism of Al/Mg gradient material interface. Microstructure characteristics at the Al/Mg interface have been investigated. It shows that an isolated island structure preferentially generates at the crystal defect as a consequence of interdiffusion, which is composed of Al _3 Mg _2 and Al _12 Mg _17 . Then such intermetallic compounds (IMCs) grow to continuous layers with distinct convex. Finally, the interface is fully transformed into flat. A theoretical analysis and calculation have been carried out to explain the thermodynamically feasibility of IMCs. The evolution mechanism of voids at the interface is also discussed. Fractographic analysis performed on selected specimens shows typical brittle cleavage fracture characteristics, and detailed analyses reveal that the fracture failure is associated with brittle IMCs.

With a high-current pulsed electron beam (HCPEB) irradiation on a pre-deposited W coating onto Al substrate, surface alloying of W-Al coating was realized to result in the improvement of corrosion resistance. W coating was deposited onto the Al surface using an air-pressurized spraying gun. The experimental results show that, the surface defects were formed on the surface layers after 15-pulsed irradiation. With increasing number of pulses, the corresponding size and density decreased and the surface became much smoother. Meanwhile, W particles were dissolved into the Al matrix and an alloying layer of about 10 μm in thickness was formed. The newly formed alloying layer was mainly composed of the ultrafine Al 4 W, W and Al as the major phases. The corrosion property of the HCPEB treated samples was dramatically enhanced due to the addition of W element and the modified microstructure. [ABSTRACT FROM AUTHOR]

Despite the physiological importance of aluminum (Al) phytotoxicity for plants, it remained unknown if, and how, calcineurin B-like calcium sensors ( CBLs) and CBL-interacting protein kinases ( CIPKs) are involved in Al resistance., We performed a comparative physiological and whole transcriptome investigation of an Arabidopsis CBL1 mutant ( cbl1) and the wild-type ( WT)., cbl1 plants exudated less Al-chelating malate, accumulated more Al, and displayed a severe root growth reduction in response to Al. Genes involved in metabolism, transport, cell wall modification, transcription and oxidative stress were differentially regulated between the two lines, under both control and Al stress treatments. Exposure to Al resulted in up-regulation of a large set of genes only in WT and not cbl1 shoots, while a different set of genes were down-regulated in cbl1 but not in WT roots. These differences allowed us, for the first time, to define a calcium-regulated/dependent transcriptomic network for Al stress responses., Our analyses reveal not only the fundamental role of CBL1 in the adjustment of central transcriptomic networks involved in maintaining adequate physiological homeostasis processes, but also that a high shoot-root dynamics is required for the proper deployment of Al resistance responses in the root. [ABSTRACT FROM AUTHOR]

The paper focuses on the development of AA6061 single reinforced composites with 5 wt.% of graphite, 5 wt.% of boron carbide and a hybrid composite reinforced with 5 wt.% graphite + 5 wt.% boron carbide + 5 wt.% cerium oxide. The microstructures of manufactured single reinforced composite and hybrid composite were studied using optical microscope. The mechanical properties like hardness and tensile strength were also studied. The Vickers microhardness of graphite reinforced composites decreased from 45 VHN to 36 VHN and of boron carbide reinforced composites increased from 45 VHN to 74 VHN, while that of hybrid composites increased from 45VHN to 68VHN. The Brinell macrohardness of graphite reinforced composites decreased from 30 BHN to 25 BHN and of boron carbide reinforced composites increased from 30 BHN to 50 BHN, while that of hybrid composites increased from 30 BHN to 44 BHN. The ultimate tensile strength of graphite reinforced composites decreased from 160 MPa to 138 MPa and of boron carbide reinforced composites increased from 160 MPa to 195 MPa, while that of hybrid composite increased from 160 MPa to 175 MPa. [ABSTRACT FROM AUTHOR]

Aluminum (Al) Hybrid Metal Matrix Composites (HMMCs) are extensively used in aerospace, automotive and other industries, replacing the usage of single reinforced metal matrix composite material. In the last five years, due to the advancement of technology, HMMCs have witnessed largely enhanced application and usage. HMMCs exhibit robust and well-enhanced properties when compared to the single reinforced composite materials. In this review, different types of reinforcements used by the researchers are discussed. Further, the volume fraction of reinforcement and the types of fabrication method adopted are also examined. Selecting suitable process parameter for the fabrication of composite material is important, which results in equal distribution of reinforcement in the matrix material. For machining, composite material nontraditional machine was adopted by most of the researchers; especially Wire Electrical Discharge Machine (WEDM) and Electrical Discharge Machine (EDM) are widely used due to their dimensional accuracy and less distortion over the surface of the workpiece. The application of Al HMMCs, problems encountered in the machining of HMMCs and the future possible research trends in this area are also discussed. [ABSTRACT FROM AUTHOR]

Energetic composite materials are very important in military purpose and building explosion but, the role of polymer binder and the materials interfaces has been little reported. Here, we prepared energetic composites consisting of aluminum (Al), iron oxide (FeO) and polymer, as the fuel, oxidizer and binder, respectively. Two different methods, i.e. physical mixing and compression molding were employed to form blended powder and composite film, respectively. The use of partially fluorinated polymer such as poly(vinylidene fluoride) (PVDF) resulted in large improvement in exothermic energy compared to that of hydrocarbon polymer such as poly(vinyl pyrrolidone) (PVP), representing that fluorocarbon groups are actively involved in the reaction and PVDF acts as an oxidizer as well as binder. Furthermore, the Al/FeO/PVDF film prepared by compression molding exhibited much higher exothermic energy than the blended powder, indicating the importance of intimate contact property of energetic materials for energy release. [ABSTRACT FROM AUTHOR]

Bulk Al materials with average grain sizes of 0.47 and 2.4 µm, were fabricated by quasi-isostatic forging consolidation of two types of Al powders with average particle sizes of 1.3 and 8.9 μm, respectively. By utilizing the native amorphous Al 2 O 3 (am-Al 2 O 3 ) film on the Al powders surfaces, a continuous, ∼7 nm thick, am-Al 2 O 3 network was formed in situ in the Al specimens. Systematic investigation of the changes to the am-Al 2 O 3 network embedded in the Al matrix upon heating and annealing up to 600 °C was performed by transmission electron microscopy (TEM). At the same time, the stability of the Al grain structure was studied by transmission Kikuchi diffraction (TKD), electron back-scatter diffraction (EBSD), and TEM. The am-Al 2 O 3 network remained stable after annealing at 400 °C for 24 h. In-situ TEM studies revealed that at temperatures ≥450 °C, phase transformation of the am-Al 2 O 3 network to crystalline γ-Al 2 O 3 particles occurred. After annealing at 600 °C for 24 h the transformation was completed, whereby only nanometric γ-Al 2 O 3 particles with an average size of 28 nm resided on the high angle grain boundaries of Al. Due to the pinning effect of γ-Al 2 O 3 , the Al grain and subgrain structures remained unchanged during annealing up to 600 °C for 24 h. The effect of the am-Al 2 O 3 →γ-Al 2 O 3 transformation on the mechanical properties of ultrafine- and fine-grained Al is discussed from the standpoint of the underlying mechanisms. [ABSTRACT FROM AUTHOR]

Mg/Al was bonded successfully via vacuum diffusion bonding in this paper. Microstructure evolution, the growth kinetic of IMCs, diffusion behaviors and mechanical properties were investigated, and their relations were discussed. The results indicate that, the multi-layer diffusion couple at the joint consisted of Al-based solid solution (α), Al 3 Mg 2 layer (β), Al 12 Mg 17 layer (γ), and Mg-based solid solution (δ). In addition, Mg/Al vacuum diffusion bonding was a diffusion-controlled process. Growth kinetic equations of the intermetallic phases were developed and the calculation results were in good agreement with the experimental data. The different interdiffusion coefficients calculated could characterize the nature of the differences in growth-rate. Microhardness was measured by the nanoindentation hardness tester. The result showed that the microhardness of the transition layer was higher than those of Al and Mg base metals due to intermetallic phases. Mechanical properties of the bonded joints were investigated by shear strength, the graphs of shear fracture showed a brittle fracture which occurred at the joint interface. [ABSTRACT FROM AUTHOR]

A1 induced a nucleolus and some nucleolar material containing argyrophilic proteins extruded from the nucleus into the cytoplasm of root tip cells of some plants exposed to excessive Al. However, limited information has been available about cytological effects of Al on nucleolus and nucleolar proteins in cereal crops. For a better understanding of the toxic effects of Al on nucleolus and nucleolar proteins, effects of Al on nucleolus in root tips of Hordeum vulgare L. were examined. The results obtained by silverstaining showed that some small nucleolar particles containing argyrophilic proteins were distributed in nucleoplasm and cytoplasm. Data from indirect immuno-fluorescent technique confirmed that these proteins were nucleophosmin (B23), nucleolin (C23) and fibrillarin, which were both in nucleoplasm and cytoplasm. Western immuno-blot analysis revealed that the contents of the three major nucleolar proteins increased significantly when compared with control. [ABSTRACT FROM AUTHOR]

Background Masson pine (Pinus massoniana) is one of the most important timber species with adaptable, fast growing, versatile advantages in southern China. Despite considerable research efforts, the cellular and molecular mechanisms of A1 toxicity and resistance in P. massoniana are still poorly understood. The effects of Al on uptake and translocation of Al and other minerals, cell division and nucleolus in P. massoniana were investigated. Results The results indicated that Al accumulated mainly in the roots, and small amounts were transported to aboveground organs. In the presence of Al, the contents of Mg and Fe in stems increased and decreased in roots. Accumulation of Mn in the organs was inhibited significantly. Evidence from cellular experiments showed that Al had an inhibitory effect on the root growth at all concentrations (10-5 - 10-2 M) used. Chromosome fragments, chromosome bridges, C-mitosis and chromosome stickiness were induced during mitosis in the root tip cells. Al induced the formation of abnormal microtubule (MT) arrays, consisting of discontinuous wavy MTs or short MT fragments at the cell periphery. MT organization and function of the mitotic spindle and phragmoplast were severely disturbed. The nucleolus did not disaggregate normally and still remained its characteristic structure during metaphase. Nucleolar particles containing argyrophilic proteins were accumulated and leached out from the nucleus to the cytoplasm. Evidence confirmed that these proteins contained nucleophosmin (B23), nucleolin (C23) and fibrillarin. Western immunoblot analysis revealed that the contents of three nucleolar proteins increased significantly. Conclusion Based on the information provided in this article, it is concluded that root tips of plants are the most sensitive organ to environmental stresses and the accumulation of Al ions primarily is in roots of P. massoniana, and small amounts of Al are transported to aboveground. Root apical meristems play a key role in the immediate reaction to stress factors by activating signal cascades to the other plant organs. Al induces a series of the cellular toxic changes concerning with cell division and nucleolus. The data presented above can be also used as valuable and early markers in cellular changes induced by metals for the evaluation of metal contamination. [ABSTRACT FROM AUTHOR]

Results from our previous investigation indicated that Al could affect the nucleolus and induce extrusion of silver-staining nucleolar particles containing argyrophilic proteins from the nucleolus into the cytoplasm in root tip cells of Vicia faba L. So far, the nucleolar proteins involved have not been identified. It is well known that nucleophosmin (B23), nucleolin (C23), and fibrillarin are three major and multifunctional nucleolar proteins. Therefore, effects of Al on B23, C23, and fibrillarin in root tip cells of V. faba exposed to 100 μM Al for 48 h were observed and analyzed using indirect immunofluorescence microscopy and Western blotting. The results from this work demonstrated that after 100 μM of Al treatment for 48 h, B23 and C23 migrated from the nucleolus to the cytoplasm and fibrillarin from the nucleolus to the nucleoplasm. In some cells, fibrillarin was present only in the cytoplasm. Western blotting data revealed higher expression of the three major nucleolar proteins in Al-treated roots compared with the control and that the B23 content increased markedly. These findings confirmed our previous observations. [ABSTRACT FROM AUTHOR]