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Using atom probe tomography (APT), transmission electron microscopy (TEM), and hardness tests, the effect of Sn and Cu on the evolution of Mg:Si ratios in clusters and subsequent precipitation hardening behavior of pre-aged Al-1.0Mg-0.6Si alloys are investigated, and the underlying mechanism is revealed by density functional theory (DFT) calculation of interaction energy. It is shown that, the doping of Sn and/or Cu increases the average Mg:Si ratio in clusters. This increase is attributed to the strong interaction of Sn/Cu with Mg solutes, which enhances the binding of Mg to Si-rich clusters and results in a higher proportion of clusters with Mg:Si ratios near 1 (0.75–1.25). Consequently, the enhanced precipitation of β'' precipitates during artificial aging is observed in Sn and/or Cu doped alloys, due to the ease of clusters with Mg:Si ratios near 1 transform into β'' precipitates, leading to an improved hardening response. Notably, the combined doping of Sn and Cu exhibits the strongest aggregation tendency towards Mg solutes, yielding the most pronounced strengthening effects on precipitation and hardening response during artificial aging. Furthermore, a schematic model detailing the evolution of Mg:Si ratios in clusters is proposed, based on the APT results and DFT calculation of interaction energy.

The impact of hot rolling finish temperature (HRFT) on the evolution of microstructure, texture, as well as formability—including deep drawability and bendability—of Al–Mg–Si alloy was studied in present work. The obtained results reveal that HRFT has a notable influence on the dynamic softening and dynamic precipitation behaviors during the hot rolling process of the investigated alloy. This leads to the volume fraction and number density of micro-sized Mg2Si particles increase as the increase of HRFT, those of nano-sized particles decrease, and the dislocation density decrease, in the hot-rolled sheets. These microstructural variations persist in the cold-rolled sheets, subsequently affecting the ultimate microstructure, texture, as well as formability of T4P sheets. The deep drawability improves as the HRFT rises, as indicated by the increase in normal anisotropy (r‾) and decrease in planar anisotropy (Δr). This is attributed to the weakening of texture intensity. The bendability, quantified by the minimum hemming factor (Rmin/t), deteriorates as the HRFT rises from 260 °C to 390 °C, attributed to the strengthening of P component along with the weakening of Cube component. Conversely, with the HRFT rises from 390 °C to 420 °C, the bendability improves dramatically due to the significant reduction in the average grain size. A combination of excellent deep drawability and bendability could be obtained by elevating the HRFT to 420 °C, attributed to the combined effect of weakened texture intensity and fine grains.

In this paper, the combined effect of Sn addition and solution treatment temperature on natural aging (NA) hardness behavior and microstructure of Al-0.4Mg-1.0Si alloy were investigated by hardness test, scanning electron microscope (SEM) and scanning transmission electron microscope (STEM). The evolutions of clusters characterized by three-dimensional atom probe (3DAP) during initials stages of NA are also investigated based on the slow in formation of clusters due to Sn addition. The results shown that a Sn-rich particles with round shape retained in Al matrix after quenching treatment when the added Sn content exceeds it limit solubility, which will reduce the Mg content of the designed alloy. The suppression of NA can be enhanced with the increase in the adding Sn content and solution treatment temperature, which is strongly related to the delay of the segregation of Mg and Si to form clusters due to more trapping vacancies by Sn atoms. The addition of Sn also revealed that the segregation of Si during NA is earlier than that of Mg atoms. The Si-rich clusters are formed preferentially during initial stage of NA, and Mg–Si co-clusters are formed after long period of NA. The Mg/Si ratio and average size of Sn-containing clusters in the 0.04%Sn and 0.1%Sn alloy are obviously higher than that of Sn-free clusters regardless of the 1 day NA or 14 days NA as more Mg atoms are dragged into Sn-containing clusters due to strong interaction between Sn and Mg atoms.

Multi-walled carbon nanotubes (MWCNTs) are widely recognized for their exceptional mechanical properties and potential to reinforce composite materials. However, the requirement for high MWCNT concentration remains a challenge in achieving effective reinforcement. In this study, using unzipped multi-walled carbon nanotubes (uMWCNTs) and transition metal filler as a means to significantly enhance the mechanical properties of polyamide 66 (PA66) and incorporating 0.2% w/w of uMWCNTs-Mn as filler allowed us to increase PA66's tensile strength by over 74% and its Young's modulus by over 100%. The structural and functional integrity of uMWCNTs-Mn and PA66 matrix were investigated in detail. This work reveals that the enhancement of mechanical properties is mainly due to the interfacial interaction between uMWCNTs-Mn sheets and the PA66 matrix, the coupling effect of manganese ions, and increases the crystallinity and reduces the size of microcrystals. This work's findings provide a novel approach to the preparation of high-performance composites with low concentrations of carbon nanostructures, which holds significant implications for the development of advanced materials.

Hydrogel sensors have drawn tremendous attention due to the combination of stretchability, biocompatibility, and convenient production. The integration of high mechanical strength, stretchability and a wide working range towards various application environment is still a great challenge. Herein, both the tough and highly stretchable hydrogel sensor was developed and showed large working range and good sensing capability towards various deformation and underwater motions. The hydrogel was constructed by the polymerization of acrylic acid, acrylamide and N, N-dimethyl acrylamide, and crosslinked by the zirconium hydroxide. The obtained hydrogel exhibits high mechanical strength (∼1.5 MPa), strain (∼1400%) with good toughness (∼12 MJ/m−3), recovery properties and high elasticity (G’∼23 KPa) which was beneficial for the stable sensing performance. It also showed high sensitivity in a wide working range (0–1300%), and exhibited stretching-dependent resistance signal monitoring capability on large, small, cyclic deformations, and various human motions (wrist, finger bending and swallowing). Moreover, it can detect various motions underwater, even monitor the pulse beating for healthcare in the liquid environment. This hydrogel with these comprehensive mechanical and sensing performances has great potential in the fields of artificial intelligence and electric skins, and further applied in the aquatic environment.

The mechanism for enhanced precipitation strengthening due to the addition of copper to Al-9.0Zn-1.5Mg (wt.%) alloys has been investigated by means of tensile test, transmission electron microscopy, anomalous small-angle X-ray scattering and three-dimensional atom probe. With the addition of copper increasing from 0% to 1.0%, and then 2.6%, the strength increment of peak-aged alloys due to precipitation strengthening increases from 274.8 MPa to 329.3 MPa, and then 343.0 MPa. Based on the copper-induced change of the parameters of clusters, GPI zones and η′ precipitates coexisting in the aged alloys, the enhanced precipitation strengthening has been discussed in detail by considering their coherent, modulus and short-order strengthening. In the alloy without copper, the coherent strengthening from η′ precipitates play a main role in precipitation strengthening. In copper-containing alloys, the contribution of clusters to strengthening become significant. The addition of copper decreases coherent strengthening and modulus strengthening from η′ precipitates, but increases modulus strengthening from GPI zones and clusters, and short-range order strengthening from clusters more apparently, and consequently enhances strength of the alloys after aging.

The combined effect of Sn and pre-aging on hardening and precipitation behavior of Al-1.0Mg-0.6Si(-0.3Cu) alloy was investigated by using hardness measurement, tensile test, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicated that the natural aging (NA) hardening of Al-1.0Mg-0.6Si (−0.3Cu) alloy was suppressed by pre-aging treatment, and the suppression of NA can be enhanced by the addition of Cu. However, the suppression of NA time of Al-1.0Mg-0.6Si and Al-1.0Mg-0.6Si-0.3Cu alloy, i.e., without obvious hardness increase after pre-aging treatment, is reduced to 5 and 7 days by the addition of Sn, which is not conducive to the suppression of NA. For subsequent artificial aging (AA) of the Al-1.0Mg-0.6Si (−0.3Cu) alloys, the AA precipitation of Al-1.0Mg-0.6Si alloy with pre-aging treatment is accelerated by the addition of Sn or Cu, particularly by adding both Sn and Cu, resulting in the increase in the bake hardening response. The effect of the evolution of clusters after pre-aging on underling mechanisms of NA and its AA were also discussed.

Constructing the interface passivation layer is of importance to accelerate the charge transfer and thus enhance the efficiency of quantum dots-sensitized solar cells (QDSCs). Here, an effective Cu:ZnSeS intermediate passivation layer (IPL), aiming at improving the charge transfer process, is fabricated on the surface of photoanodes via the facile successive ionic layer adsorption and reaction (SILAR) process. Electrical chemical analysis results exhibit that the Cu:ZnSeS IPL can efficiently hinder the charge recombination and accelerate the charge transport process due to the synergistic effect of ZnSeS alloy layer and Cu ions dopant. Meanwhile, the time-resolved photoluminescence (TRPL) spectroscopy demonstrates the Cu:ZnSeS IPL can not only reduce the surface traps but also accelerate hole capture. Importantly, the laser confocal Kelvin probe force microscopy (KPFM) measurement is first used to investigate the charge transport process via the change of surface potential in dark and under laser irradiation. In terms of the merits of Cu:ZnSeS IPL, the power conversion efficiency (PCE) of the resultant CdSeTe-based QDSCs reaches up to 9.46%, with an enhancement of 14%, compared to the traditional single ZnS passivation layer (∼8.32%). Besides, employing the Cu:ZnSeS intermediate passivation layer, the PCE of 11.64% was achieved, which is considered the highest reported in the reported CdSeTe QDSCs so far. This work demonstrates a facile and effective approach to modulating the charge transport process, thus enhancing the device performance.

Hydrogen-induced failure in a partially-recrystallized Al-Zn-Mg-Cu alloy with different aging conditions was studied by in-situ electrochemical hydrogen charging method, and the hydrogen-induced cracking mechanism was elucidated by investigating the microstructure-dominated deformation behavior. It was found that in naturally-aged and peak-aged samples, cracks initiate at sample surfaces, and deformation dominated by shearing facilitates hydrogen diffusion, resulting in a high hydrogen embrittlement susceptibility. However, in the over-aged sample, deformation dominated by bypassing cannot transport hydrogen efficiently, which exerts no effect on crack initiation at the sample center. In addition, the same cracking pattern exists on all samples in silicone oil and in-situ hydrogen charging environments. The grain boundary of recrystallized grains is prone to strain localization, leading to intergranular cracking. In unrecrystallized grains, transgranular cracks propagate along intersections of slip lines and subgrain boundaries. This study improves the understanding of hydrogen embrittlement in new generation Al-Zn-Mg-Cu alloy by linking the existing hydrogen embrittlement mechanism to the deformation behavior dominated by microstructures.

In this work, living diatoms (LDT) were fed Eu3+-complex-polysaccharide aggregates (EIPA), and the living diatoms integrated-EIPAs (LDT-E) in a completely new UV downconversion biophotonic material. The EIPAs were embedded inside siliceous cell walls of living diatoms. When dried, these diatoms (LDT-Es) are luminescent at 612 nm, due to the Eu3+-complex. As UV-downconversion material, LDT-E absorbs UV light in the band of 250–400 nm and converts into useful visible light, thus contributing to UV-protection and potentially to photocurrent generation in photovoltaic devices. This downconversion material from living diatom retains the porous characteristics of the diatom siliceous cells, as well as the diatom organic components. Most important is the absence of a chemical process to generate this biomaterial from natural living diatoms, in order to obtain UV-protection and downconversion.

We synthesized the two-dimensional Zn–Cu–In–S (ZCIS) semiconductor nanoplatelets and then modified their surface with 4-bromobenzenediazonium tetrafluoroborate. The surface modified ZCIS nanoplatelets were combined with the conventional photovoltaic hole transport layer material (HTL) PEDOT: PSS. The work function of the HTL increased from 5.04 eV to 5.17 eV, thus promoting the reduction of the energy potential barrier and increasing the internal electric field. It also effectively improves the light utilization by effectively increasing the absorption of light in the spectral range below 500 nm and converting them into the secondary emission in the 600–700 nm range. Such emission can be effectively utilized by the active layer to increase the open-circuit voltage (Voc) and short-circuit current (Jsc) of the cell, resulting in an increase in the overall cell power conversion efficiency (PCE) from 12.29%–13.14%.

The graphene oxide-silica, GO-SiO2 (GS) nanoparticles synthesized by in-situ hydrolysis were grafted with block polymers polyethylene glycol (PEG) and low-molecular polyethylene terephthalate (LPET) using 3-isocyanatopropyltrimethicone (IPTES) as a bridge to prepare the additive GS-IPTES plus PEG-LPET (GSIP). This grafting process was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The GSIP of various contents was used as reinforcing fillers to prepare PET/GSIP composite by melt blending. The crystallization and mechanical properties of the PET/GSIP composite were dramatically enhanced with the addition of small amounts of GSIP. Compared with pure PET, the crystallization temperature of PET/GSIP was increased by 41 °C at 1 wt.% addition of GSIP. Moreover, the highest tensile strength was 91.2 MPa and the highest modulus was 14.7 GPa at 0.8 wt.% addition. The crystalline and mechanical properties improvements were attributed to the synergistic effects of GS and block polymer chains.

The fluorescent and quantum yield (QY) of graphene quantum dots has been improved in recent years by doped atoms, which have good application prospects in fluorescence sensors and biological imaging. Here, a one-step hydrothermal synthesis method was used to synthesize manganese ions bonded with boron and nitrogen-doped graphene quantum dots (Mn-BN-GQDs). Compared with the boron and nitrogen co-doping graphene quantum dots (BN-GQDs), the fluorescence properties and quantum yield of Mn-BN-GQDs are significantly improved. Meanwhile, Mn-BN-GQDs exhibit low toxicity and good fluorescence imaging in living cells and has high selectivity to Fe3+ ions. Therefore, this experiment design Mn-BN-GQDs as a fluorescence sensor to detect Fe3+ ions, providing strong evidence for the advanced high sensitivity, selectivity and wide detection range of the Mn-BN-GQDs as a fluorescence sensor. These results indicate a dual linear relationship with good linear relationships in the 10–100 μM and 100–800 μM ranges, and limit of detection are 0.78 μM and 9.08 μM, respectively. Cellular imaging results demonstrate that Mn-BN-GQDs can be used as fluorescence sensors in biological imaging. Mn-BN-GQDs can be used for fluorescence sensing in biological imaging in combination with low toxicity, QY and quantum dot lifetime.

The effects of three-stage homogenization on recrystallization and fatigue crack growth behavior of 7020 aluminum alloy were investigated. It was shown that a large amount of fine Al3Zr dispersoids form in the grain and near the grain boundaries of the alloy after three-stage homogenization. The ratio of volume fraction to radius for the Al3Zr dispersoids after three-stage homogenization increased by 171.2% compared with the one-stage homogenization. The recrystallization fraction was reduced from 29.5% for the one-stage homogenized alloy to 19.1% for the three-stage homogenized alloy. If the fatigue crack propagation encounters small recrystallized grains with high misorientation, the crack is easy to grow quickly along grain boundaries. When the stress intensity factor at the crack tip is 10MPa·m1/2, the fatigue crack growth rate (FCGR) of the one-stage homogenized alloy is 30.6% faster than that of the three-stage homogenized alloy.

Evolution of grain structure during isothermal multi-direction forging (MDF) of an Al-Zn-Mg-Cu alloy at 400 °C and 450 °C with strain rates from 10−3 s−1 to 10−5 s−1 was investigated with electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The results demonstrated that the evolution of grain structure was dominated by discontinuous dynamic recrystallization (DDRX), during which the continuous forming of new recrystallized grains at grain boundaries was found. Characteristics of DDRX was enhanced with the decrease of MDF strain rate or temperature, which promoted the formation of recrystallized grains at grain boundaries. Besides, the increase of total strain enhanced such grain refinement effect until the grain structure reached the stable state, in which fine recrystallized grains replaced most of the initial coarse grains.

In order to find a clean, efficient and sustainable new energy source that can replace fossil fuels, hydrogen energy is considered to be the most ideal choice. Electrocatalytic oxygen evolution plays a vital role in the development of hydrogen energy, promotes the research of new electrocatalysts, and is dedicated to find materials with high electrocatalytic efficiency. This article discusses in detail the major developments in OER electrocatalysts, including recently reported metal and non-metal based materials. Metal-based catalysts, although having the advantages of high catalytic activity, have disadvantages such as poor stability and low selectivity, which hinder the further application of such materials. Non-metallic based materials avoid such disadvantages and exhibit very substantial performance in overall water decomposition. This review provides useful knowledge of a well-designed OER electrocatalyst and a possible strategy for OER/HER dual-function catalytic performance for future development. Keywords: Oxygen evolution reaction (OER), Electrocatalyst, Metal-based electrocatalysts, Carbon-based electrocatalysts, Black phosphorous (BP)

Summary: Although microbe-associated molecular pattern (MAMP) molecules can promote cholesterol accumulation in macrophages, the existence of a host-derived MAMP inactivation mechanism that prevents foam cell formation has not been described. Here, we tested the ability of acyloxyacyl hydrolase (AOAH), the host lipase that inactivates gram-negative bacterial lipopolysaccharides (LPSs), to prevent foam cell formation in mice. Following exposure to small intraperitoneal dose(s) of LPSs, Aoah−/− macrophages produced more low-density lipoprotein receptor and less apolipoprotein E and accumulated more cholesterol than did Aoah+/+ macrophages. The Aoah−/− macrophages also maintained several pro-inflammatory features. Using a perivascular collar placement model, we found that Aoah−/− mice developed more carotid artery foam cells than did Aoah+/+ mice after they had been fed a high fat, high cholesterol diet, and received small doses of LPSs. This is the first demonstration that an enzyme that inactivates a stimulatory MAMP in vivo can reduce cholesterol accumulation and inflammation in arterial macrophages.

Trace amounts of heavy metal ions in the human body are essential for maintaining health. However, heavy metal ion excess or deficiency causes toxicity or disease. This study examines the sensitivity of luminescent europium complexes for the detection of Cu2+. Here, Eu3+ is complexed with1,10-phenanthroline (phen) and 4,4′,4-trimethyltriphenylamine (TTA) to form luminescent [Eu3+(TTA)3phen] complexes, encapsulated in silica (SiO2) nanoparticles. The silica nanoparticles are then formed into a composite with a blend of chitosan and polyethylene oxide (PEO), to make electrospun nanofibers. The combination of Eu3+ complexes with SiO2 nanoparticles doped in chitosan enhances the fluorescence performance. Photophysical measurements show that when the Cu2+ concentration is 100 μmol/L, the fluorescence of the composite chitosan nanofibers can be quickly and sensitively quenched, and that concentrations as low as 10 μmol/L Cu2+ can be detected. Furthermore, the use of chitosan and PEO to prepare the material makes these new fluorescence-based copper sensing materials suitable for Cu2+ detection in biological systems.

Histidine Polypeptide-Hybridized Nanoscale Metal–Organic Framework (fH12/ZIF-8) can be produced effectively in water at room temperature without using any additives. The fluorescein label also provides a useful method to quantify the extent to which the anti-cancer drug doxorubicin (DOX) is loaded into or released from the resulting MOFs. In vitro studies have shown that fH12/ZIF-8 has the useful property of dissolving and controlled rates at low pH. It ruptured fastest in PBS buffer solution with pH 6.3, and the release rate reached 50% at 4 h. Furthermore, it showed that the addition of histidine polypeptides increases uptake by HepG-2 cells. This study integrates drug loading and detecting aspects into a single theranostic platform by a simple and efficient strategy, opening a new route for the construction of advanced drug delivery systems.

The combined effect of adding Sn and natural aging (NA) time on the precipitation and age-hardening rate of the Al-0.4Mg-1.0Si alloy was investigated by a hardness test, electrical resistivity test, differential scanning calorimetry (DSC) analysis, 3-D atom probe (3DAP) analysis, and transmission electron microscopy (TEM). The results showed that the NA of the Al-0.4 Mg-1.0Si alloy was suppressed by adding Sn. This suppression was ascribed to the suppression of the formation of clusters. The short NA time (less than 5 days) had a positive effect on the subsequent artificial aging (AA) in the Sn-added alloys, i.e., a fast AA-hardening rate was achieved. The positive effect of the NA on the AA in the Sn-added alloys increased as the amount of Sn increased, but decreased as the NA time increased. The AA was negatively affected by the NA when the NA time was increased to 14 days. The accelerated AA precipitation of the Sn-added alloys after a short NA time was responsible for the fast AA-hardening rate. This accelerated precipitation was related to the increased amount of retained quenched-in vacancies according to their NA resistivity curves and similarity of the chemical composition between the Sn-containing clusters and β'' phases.