Continuous Metal Research Articles

Association of childhood and perinatal blood metals with children gut microbiome in a Canadian gestation cohort

BACKGROUND AND AIM: The gut microbiome is important in modulating health in childhood. Metal exposures affect multiple health outcomes, but their ability to modify bacterial communities in children is poorly understood. We assessed the associations of childhood and perinatal blood metals with childhood gut microbiome diversity, structure, species, and pathway alterations. METHODS: We assessed the gut microbiome using 16S rRNA amplicon sequencing and shotgun metagenomic sequencing in 6-7 year-old children participating in the GESTation and Environment (GESTE) cohort study. We assessed blood metal concentrations (cadmium, manganese, mercury, lead, selenium) at two time points, i.e., perinatal exposures at delivery (N=70) and childhood exposures at the 6-7 year follow up (N=68). We used covariate-adjusted models to determine microbiome associations with continuous blood metal levels, including linear regression (Shannon and Pielou diversity indexes), permutational multivariate analysis of variance (adonis) (weighted UniFrac, Bray-Curtis, unweighted UniFrac, and Jaccard distance matrices), and multivariable association model (MaAsLin2) (phylum, family, species, and pathway). RESULTS:Children's manganese and selenium exposure had significant associations with microbiome phylum (i.e., Verrucomicrobiota [coef=-0.305, q value =0.03]) and family (i.e., Eggerthellaceae [coef=-0.228, q value =0.05]) level differences. Individual species, including potential pathogens (i.e., Bacteriodes vulgatus, Eubacterium rectale) and beneficial species (i.e., Bifidobacterium longum, Faecalibacterium prausnitzii), had significantly higher relative abundance in relation to low level children or perinatal blood cadmium, mercury, and lead (q value 0.1). We found significant negative associations between childhood blood lead and acetylene degradation pathway abundance (q value 0.1). Finally, neither perinatal or childhood metal concentrations were associated with children's gut microbial inter- and intra-subject diversity. CONCLUSIONS:Our findings suggest both long-term and short-term associations between metal exposure and the childhood gut microbiome, with stronger associations observed with more recent exposure. Future epidemiologic analyses may elucidate whether the observed changes in the microbiome relate to children’s health. KEYWORDS: microbiome, heavy metals

Carbon Deposition on Heterogeneous Pt Catalysts Promotes the Selective Hydrogenation of Halogenated Nitroaromatics.

Pt-based heterogeneous metal catalysts are commonly used in the hydrogenation of nitro groups. However, the continuous large metal domain size and the complex interaction between the substrates and metal surface usually inevitably result in side reactions, such as dehalogenation of halogenated nitroaromatics. In this work, by simply treating the Pt-based catalysts with CO at elevated temperature, the Boudouard reaction taking place on Pt surface results in the deposition of carbon species thereon. The carbon deposition not only inhibits the dehalogenation by restricting the planar interaction of the aromatic group with the Pt surface that is segmented by C, the hydrogenation activity of the nitro group is also enhanced on the partially positively charged surface Pt sites created by the electron-withdrawing interstitial C. Such a simple treatment strategy is effective for fabricating Pt-based catalysts on different supports toward the selective hydrogenation of a wide range of halogenated nitroaromatics.

Electrochemical synthesis of continuous metal–organic framework membranes for separation of hydrocarbons

Electrochemical synthesis of continuous metal–organic framework membranes for separation of hydrocarbons

Effects of pin morphology on the interface defects of the FSWed lap joints of 2A12 aluminum alloy

The current work aims to study the effects of stirring pin morphology on the FSWed lap joints defects and mechanical properties. The 2A12 aluminum alloy friction stir welding lap joints were obtained using two shapes and three thread lengths of stirring pins by experiments. Besides the interface defects forming mechanism were studied by joints plastic metal flow numerical simulation. The results show that the conical pin can lead to uniform and continuous plastic metal velocity field which forms a Hook defect with sharp end, smaller deflection angle (minimum 8°) and larger size (maximum 0.18mm). It also will lead to a larger failure load (maximum is 9.5kN), and the fracture position easily occurs at the Advancing side (AS) of lower plate. The three section pin has a periodic shearing effect causing velocity difference between the arc edge and cutting section of the pin which forms a Hook defect with thicker end, larger deflection angle (maximum 42°) and smaller size (minimum 0.06mm). It also causes discontinuous wavy debris forms in the AS. The three section pin leads to a lower failure load (maximum is just 7.6kN), and the fracture position turns to occur at the lap interface. The increase of the thread length can promote the exchange of plastic metal in the thickness direction and interface materials flow velocity. So the angle (from 20°to 150°) and size (from 0.1mm to 0.6mm) of Hook increases but the height of Cold Lap reduces (increasing the effective sheet thickness of retreating side from 0.69mm to 0.95mm). In addition, the increase of the thread length can make the periodic shear effect of three section pin gradually weak. It is also found that the fracture position is closely related to the shape and the thread length of pins. When using conical pin, the fracture occurs at AS of lower plate or Retreating Side of Nugget Zone (NZ-RS) of upper plate; When using three section pin, the fracture occurs at the bonding interface. And with the increase of the thread length, the fracture position changes from the bonding interface to the NZ-RS of upper plate, and finally to the AS of lower plate.

A reproducible, low cost microfluidic microcavity array SERS platform prepared by soft lithography from a 2 photon 3D printed template

As they are widely implemented as features formed at a continuous metal surface, Surface-enhanced Raman spectroscopy (SERS) substrates are amenable to implementation in a microfluidic format. However, achieving reproducibility and repeatability in platform fabrication often requires methods that are complex and expensive, restricting transfer from laboratory prototyping to mass production. Herein, a new and robust, low cost technique for cavity array SERS substrate fabrication and its integration into a microfluidic device is described. The fabrication relies on 2-photon 3D printing of a master template and enables batch fabrication of reproducible arrays with sub-micron resolution and uncomplicated modification of the cavity architecture. With this approach, significant Raman signal enhancement of up to 6.7 × 107 through incorporation of nanostructures - plasmonic “hot-spots” and straightforward integration into microfluidic device was achieved. In addition, implementing the nano-sub-structuring to the cavities by 2-photon 3D printing approach, we obtain reproducible enhancements of SERS intensity of more than 4 fold in comparison to arrays fabricated using previously established sphere templating techniques. The fabricated microfluidic device showed detection capability for cholesterol analyte in solution in a simple demonstration where the array was modifed with thiolated cyclodextrin host to enable analyte capture.

Removal, distribution and retention of metals in a constructed wetland over 20 years

The A-01 wetland treatment system (WTS) was designed to remove metals (primarily copper) from the effluent at the A-01 National Pollution Discharge Elimination System (NPDES) outfall at the Savannah River Site, Aiken, SC. This research investigated metal removal, distribution and retention in the A-01 WTS over a period of 20 years. The findings are important for ensuring continued metal sequestration in the A-01 WTSs over time, providing management guidance for constructed wetlands, and investigating changes in metal remediation effectiveness as a wetland ages. During 20 years of operation, systematic water and sediment sampling validated the wetlands' performance. After passage through the treatment cells, Cu concentrations were well below permit limits during all years of operation, often falling below 10 μg L−1. Cu removal has been consistent over time, averaging about 80% despite large changes in influent Cu concentrations. Most divalent metals were rapidly removed from the water and held in the sediments shortly after the water entered the treatment wetland. Average removal of Pb from water by the wetland system was 67 and 74% in 2004 and 2020, respectively. Comparable values for Zn were 52 and 65%, respectively.Generally, the highest concentrations of Cu, Pb, and Zn were found in the sediment from the first cell in each pair of cells suggesting that most of the Cu, Pb, and Zn in the A-01 effluent was bound to the sediment quickly. Diffusive gradients in thin films (DGT) measurements of Cu and Zn in the sediments were much lower than bulk sediment concentrations. These results suggest that most of the Cu and Zn in the A-01 WTS sediments was not bioavailable, hence not toxic to aquatic organisms, as a likely consequence of adsorption to sediment particles and complexation with organic and inorganic substances.

First-order metal–ferromagnetic insulator phase transition induced by Rashba spin-orbit coupling on the puckered honeycomb lattice

We investigate the first-order metal–ferromagnetic insulator phase transition on the puckered honeycomb lattice, combining the cellular dynamical mean field theory with the continuous-time quantum Monte Carlo method. By analyzing the interplay among intrinsic spin–orbit coupling (SOC), Rashba SOC and on-site interaction, we show that the ferromagnetic (FM) order and the antiferromagnetic (AFM) order occur in different regimes. Rashba SOC allows the electron spin flipping, which leads to the phase transition from the metal to FM insulator induced by the increasing on-site interaction. In contrast to the usual continuous metal–antiferromagnetic insulator phase transition, we find that the metal–ferromagnetic insulator transition is first-order by computing the double occupancy. Furthermore, the complete phase diagrams of the Rashba SOC, on-site interaction and temperature are also demonstrated.

Evaluation of the hair cell regeneration and claudin b and phoenix gene expression during exposure to low concentrations of cadmium and zinc in early developing zebrafish larvae

Zebrafish possess hair cells on the body surface similar to that of mammals inner hear, in particular in the neuromasts, and due to its ability in regenerating damaged hair cells, is regularly used as a powerful animal model to study in vivo cytotoxicity.Among the factors leading to hair cell disruption, metal ions are of particular concern since they are important environmental pollutants. To date, several studies on zebrafish hair cell regeneration after metal exposure exist, while no data on regeneration during continuous metal exposure are available. In the present study, neuromast hair cell disruption and regeneration were assessed in zebrafish larvae for the first time during zinc (Zn) and cadmium (Cd) continuous exposure and a visual and molecular approach was adopted.Fluorescent vital dye DASPEI was used to assess hair cell regeneration and the gene expression of claudin b (cldnb) and phoenix (pho), was analyzed. Metallotionein-2 (mt2) gene expression was used as standard molecular marker of metal toxicity and confirmed the higher toxicity of Cd compared to Zn. In addition, Cd caused a delay in hair cell regeneration compared to Zn. Molecular analysis showed cldnb gene expression increased in relation to the metal concentrations used, confirming the involvement of this gene in hair cell regeneration. On the contrary, a dramatic decrease of pho gene expression was observed in Cd exposed groups, suggesting a negative impact of Cd on pho expression, thus negatively interfering with hair cell regeneration in zebrafish larvae exposed to this metal.

Understanding the relationship of electrochemical properties and structure of microstructure-controlled core shell gradient type Ni-rich cathode material by single particle measurement

• Ni-rich core-shell gradient material (CSG) was investigated by quantitative analysis using single particle. • The charge transfer resistances of CSG is more stable conventional NCM during cycle. • The lithium diffusion coefficient of CSG is 10 times higher than that of conventional NCM. To overcome those of drawbacks form Nickel-rich NCM cathode materials about poor cyclability and thermal instability at elevated temperatures and high voltage conditions, CSG (core shell gradient NCM) fabricated with the concentration gradient control has continuous and gradual transition metal composition concentration gradient. It has that the rod-shaped primary particles forming the interior had a directionality toward the center of the secondary particles. The correlation of gradient structure and electrochemical properties has been investigated for this study by single particle measurement. Quantitative evaluation of the electrochemical properties of the active material through single particle measurement showed more clearly the difference in the unique electrochemical properties between CSG which have a unique structure and conventional NCM (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ). The measured initial reversible capacity was measured as 0.52 nAh (NCM, 10.4 um diameter) and 1.34 nAh (CSG, 14 um diameter). In addition, rate capability showed that CSG had higher discharge capacity under the same current density condition. In addition, calculated charge transfer resistance of CSG was lower in all DOD (depth of discharge) regions than NCM by Tafel plot. The calculated by GITT lithium diffusion coefficient in CSG is found to be 10 times higher than conventional NCM in all lithiated states. This suggests that the high diffusion coefficient of CSG not only beneficial for excellent rate capability, but also sagnificantly improves cycle life by suppressing internal stress generated upon cycling.

Investigation of dimensional accuracy of metal droplet deposition under repulsion using a lattice Boltzmann approach

Purpose This paper aims to investigate the influence of droplet infiltration and sliding on the deposition size and make a uniform deposition by controlling the interaction between droplets, using the three-dimensional lattice Boltzmann method (LBM) based on the actual working condition. Design/methodology/approach D3Q19 Shan-Chen LB approach is developed and optimized based on the metal droplet deposition. The Carnahan-Starling equation of state and transition layers are introduced to maintain the greater stability and low pseudo velocities. In addition, an additional collision term is adopted to implement immersed moving boundary scheme to deal with no-slip boundaries on the front of the phase change. Findings The numerical results show that the new¬ incoming droplet wet and slide off the solidified surface and the rejection between droplets are the reasons for the deviation of the actual deposition length. The total length of the longitudinal section negatively correlates with the deposition distance. To improve the dimensional accuracy, the deposition distance and repulsion rate need to be guaranteed. The optimal deposition distance is found to have a negative linear correlation with wettability. Originality/value The numerical model developed in this paper will help predict the continuous metal droplet deposition and provide guidance for the selection of deposition distance.

Simple Design of a Wideband and Wide-Angle Insensitive Metamaterial Absorber Using Lumped Resistors for X- and Ku-Bands

We report a wideband and polarization-/wide-angle insensitive metamaterial absorber based on a symmetry structure associated with surface mount resistors. The proposed structure consists of a periodic array of a top metal symmetry resonator loading with four lumped resistors and a continuous metal ground plane separated by a dielectric substrate of FR-4. A prototype of the proposed absorber is fabricated and measured, confirming a good agreement between the measurement and simulation results. The proposed absorber shows polarization-insensitive behavior and the absorption response in a frequency range from 8-18 GHz covering the entire X- and Ku- bands with an absorptivity above 80$\%$ for a wide incident angle up to 40 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> for both transverse electric and transverse magnetic polarizations. Compared with the reported broadband absorbers using lumped resistors, our proposed absorber exhibits excellent characteristics in terms of compact and simple structure, high relative absorption bandwidth, and polarization and wide-incident insensitivity. Therefore, this design shows promising potential for both X- and Ku-band applications.

(IMCS Third Place Best Paper Award) Highly Selective and Sensitive Trimethylamine Gas Sensors Using Patterned Metal Oxide Nanofibers Prepared By Near-Field Electrospinning

IntroductionOxide nanofibers consisting of nanoparticles are excellent nanostructures for designing high performance gas sensors. To date, randomly tangled oxide nanofiber networks prepared by far-field electrospinning process (FFES) have been widely explored as the sensing materials. When the distance between spinneret needle and substrate is very short, the straight configuration of nanofibers can be directly written on the substrate without whipping. This is referred as near-field electrospinning (NFES), which can be applied to well-defined patterning of one-dimensional nanofibers for various new applications such as sensors, optoelectronic circuits, and functional nanoelectronics. The patterning of polymeric nanofibers has been demonstrated over a decade ago. In contrast, the fabrication of one-dimensional (1D) metal oxide nanopatterns remains challenging because it becomes difficult to control the chaotic whipping motion of the jet due to the acceleration of metal ions under the electric field. In the present study, grids, diamonds, and hexagrams composed of In2O3, Co3O4, and NiO nanofibers were prepared by NFES and their potential applications as gas sensors were investigated. The sensor using In2O3 nanofiber pattern exhibited an unprecedentedly high response (resistance ratio = 239) to 5 ppm trimethylamine (TMA) with negligible cross-responses to ubiquitous ethanol and other interference gases. Method Transparent solution containing 7 g of methanol (99 %), polyvinylpyrrolidone (PVP, 17.4 wt%, Mw = 1,300,000) and metal nitrates (indium nitrate hydrate, 1.4 wt%, 99.999%; cobalt nitrate hexahydrate, 1.7 wt%, 99.99%; nickel nitrate hexahydrate, 1.7 wt%, 99.99%) were stirred for 24 h at room temperature. The prepared clear solution was transferred to a glass syringe (1000 μL) with a 21-gauge needle, and electrospun onto a 4-inch Si/SiO2 wafer containing 76 sensor substrates (size: 1 × 1 cm2) in which Pt interdigitated electrodes (electrode width: 50 μm, electrode spacing: 5 μm) above a metallic collector. The flow rate is fixed as 0.005 μL min−1 at an applied voltage of 50 V and the distance between the tip and the collector is 1 mm. During electrospinning, the loader and collector moved toward x- and/or y-axis at a controlled moving velocity of 800 mm s−1, leading to the fabrication of precursor fiber patterns, for example, grids, diamonds, and hexagrams. The precursor patterns were annealed at 600 °C for 5 h in an air atmosphere, and converted into the corresponding patterns of In2O3, Co3O4, and NiO pattern sensors, respectively. The sensors were placed in a quartz tube furnace and heated at sensing temperature (In2O3: 350 °C; Co3O4: 225 °C; NiO: 300 °C). The dc-probe resistance of the sensor was measured using an electrometer interfaced with a computer. Results and Conclusions The well-defined patterns of continuous and cylindrical oxide nanofibers could be prepared by using highly volatile solvent (methanol) and by controlling the viscosity and electrical conductivity of spray solution, the distance between spinneret needle and substrate, and the moving velocity of spinneret needle. All the parameters had an optimum window, indicating that the sophisticated control or tuning of the parameters is essential to prepare well-organized and continuous precursor and/or metal oxide fibers via NFES. It is worthwhile to note that the longstanding problem of preparing elaborate nano-architectures consisting of 1D metal oxides has been solved for the first time by investigating the interrelations of the solution/working parameters in NFES systematically. Interestingly, the sensor using In2O3 nanofiber pattern on Pt electrodes exhibited unprecedented high selectivity and responses to TMA compared with other metal oxide nanostructures reported in the literature, whereas random networks of In2O3 nanofibers and dense thin In2O3 film with negligible Pt electrode exposure showed low response and selectivity to TMA. The intriguing trimethylamine sensing characteristics are explained in relation to the promotion of gas sensing reaction by catalytic Pt electrode, which is supported again by the high TMA selectivity of the sensors using the patterns of Co3O4 and NiO nanofibers. In addition, the highly increased sensitivity to analyte gases compared with thin film sensors can be attributed by the increased gas accessibility due to the sensor structures, which is composed of mono-layered In2O3 nanofibers with 200 nm diameter. The NFES-assisted patterning of metal oxide nanofibers can provide a new platform to design high performance gas sensors for a range of emerging applications.

Exposure to atmospheric metals using moss bioindicators and neonatal health outcomes in Portland, Oregon

Studying the impacts of prenatal atmospheric heavy-metal exposure is challenging, because biological exposure monitoring does not distinguish between specific sources, and high-resolution air monitoring data is lacking for heavy metals. Bioindicators - animal or plant species that can capture environmental quality - are a low-cost tool for evaluating exposure to atmospheric heavy-metal pollution that have received little attention in the public-health literature. We obtained birth records for Portland, Oregon live births (2008–2014) and modeled metal concentrations derived from 346 samples of moss bioindicators collected in 2013. Exposure estimates were assigned using mother's residential address at birth for six metals with known toxic and estrogenic effects (arsenic, cadmium, chromium, cobalt, nickel, lead). Associations were evaluated for continuous (cts) and quartile-based (Q) metal estimates and three birth outcomes (preterm birth (PTB; <37 weeks)), very PTB (vPTB; <32 weeks), small for gestational age (SGA; 10th percentile of weight by age and sex)) using logistic regression models with adjustment for demographic characteristics, and stratified by maternal race. Chromium and cobalt were associated with increased odds of vPTB (chromium - odds ratio (OR)cts = 1.09, 95% CI: 1.00, 1.17; cobalt - ORQ4vsQ1 = 1.33, 95% CI: 1.03, 1.71). Cobalt, chromium and cadmium were significantly associated with odds of SGA, although the direction of association differed by metal (cobalt - ORcts = 1.04, 95% CI: 1.01, 1.07; chromium - ORQ3vsQ1 = 0.91, 95% CI: 0.83, 0.99; cadmium - ORcts = 0.96, 95% CI: 0.93, 1.00). In stratified analyses, odds of SGA were significantly different among non-white mothers compared to white mothers with exposure to chromium, cobalt, lead and nickel. This novel application of a moss-based exposure metric found that exposure to some atmospheric metals is associated with adverse birth outcomes. These findings are consistent with previous literature and suggest that moss bioindicators are a useful complement to traditional exposure-assessment methods.

Metal Contamination in Sediments of Coastal Rivers around Dar es Salaam, Tanzania

Sediments from coastal rivers of Kizinga, Mbezi, Msimbazi, and Mzinga were used to determine contamination levels of Cd, Pb, Cr, Ni, Cu, Al, Mn, Fe, and Zn metals. Sampling and sample preparation were done as appropriate and analysis was done using high resolution inductively coupled plasma–mass spectrometry (HR ICP-MS). Higher levels of Cd, Pb, Cr, Al, Mn, Fe, and Zn were mainly observed in Msimbazi river. Whereas higher levels of Ni and Cu were observed in Kizinga river, higher levels of Mn were observed in Mbezi river. Mzinga river had lowest levels of most metals except Mn. Lowest levels of Mn were observed in Kizinga river. Despite of enrichment factor indicating varied contamination status of metals in rivers, geo-accumulation index, contamination factor, degree of contamination, modified degree of contamination, potential contamination index and environmental toxicity quotient have indicated that sediments from these rivers are polluted, with Msimbazi and Kizinga river sediments being more polluted. Pearson correlation and hierarchical cluster analyses have revealed that Cd, Cu, Pb, and Zn were strongly correlated to each other (r2&gt; 0.7, p &lt; 0.05), indicating that they similar anthropogenic origin, while Fe, Mn, Ni, Cr, and Al were strongly correlated to each other (r2&gt; 0.69, p &lt; 0.05), indicative of similar natural origin. This implies that there might be metal-related anthropogenic activities around or close to rivers that pose environmental and health risks. Urgent river management strategies are needed to minimise the continuous metal pollution of these rivers.

Orbital Ultrasonic Welding of Ti-Fittings to CFRP-Tubes

Hybrid structures are important for the automotive and aeronautical industry as they have the potential to reduce vehicle or aircraft weight and to improve fuel efficiency. Continuous ultrasonic metal welding is a promising technique for hydraulic applications in aircraft to realise tubular metal/fiber reinforced polymer (FRP) hybrids. Fluid proof connections between dissimilar components can be joined by continuous welding seams. Tubular metal/FRP hybrids, produced by a new advanced variant of ultrasonic metal welding, are investigated as a potential substitute for metallic hydraulic tubes. The oscillating welding system moves around the tubular joining partners to generate a sealed orbital connection. Homogeneous joint quality is required to assure the requested component strength. Therefore, the amplitude of sonotrode displacement and the welding force are controlled to keep the induced welding energy constant and the joint quality uniform. High mechanical strength is required for a safe application in the 5000 psi hydraulic system of current and future aircraft concepts. For this study metal injection molded (MIM) titanium fittings (TiAl6V4) and carbon fiber reinforced PEEK (CF-PEEK) tubes were investigated. Process parameters for metal/FRP hybrid joining were evaluated considering their mechanical and technological properties, as well as the microstructure of the hybrid interfacial area. The entire joining area of tubular joining partners has to be in close contact before welding to assure a continuous tight joint. Hence, the titanium fitting is thermally shrunk onto the CFRP tube before ultrasonic welding. The presented orbital ultrasonic welding technology was developed for prospective industrial use and future applications of ultrasonically welded tubular multi-material-components.

Single-Stranded DNA as Supramolecular Template for One-Dimensional Palladium(II) Arrays.

Atomic-level control over the position and growth of a single and continuous metal chain is an ambitious goal that often requires complex and costly processes. Herein, we demonstrate that 1Pd-DNA molecules, comprising a continuous single chain of PdII ions, can be prepared by a simple self-assembly reaction between the complex [Pd(Cheld)(CH3 CN)] (1Pd_CH3 CN) (Cheld=chelidamic acid) and single-stranded DNA homopolymers (ss-DNA) containing adenine (A) or 7-deazaadenine (X) bases. The single PdII -base pairs [1Pd(N1-A)] and [1Pd(N1-X)] were synthesized and characterized in solution and solid-state (X-ray diffraction) revealing an arrangement similar to that of natural Watson-Crick base pairs. Subsequently, 1Pd-DNA hybrids were prepared, characterized, and their structures studied by small-angle X-ray scattering (SAXS) and ab-initio calculations. The results indicate that the 1Pd-DNA structures resemble that of double-stranded DNA, with one strand being replaced by a supramolecular stack of continuous PdII complexes.

Single‐Stranded DNA as Supramolecular Template for One‐Dimensional Palladium(II) Arrays

AbstractAtomic‐level control over the position and growth of a single and continuous metal chain is an ambitious goal that often requires complex and costly processes. Herein, we demonstrate that 1Pd‐DNA molecules, comprising a continuous single chain of PdII ions, can be prepared by a simple self‐assembly reaction between the complex [Pd(Cheld)(CH3CN)] (1Pd_CH3CN) (Cheld=chelidamic acid) and single‐stranded DNA homopolymers (ss‐DNA) containing adenine (A) or 7‐deazaadenine (X) bases. The single PdII‐base pairs [1Pd(N1‐A)] and [1Pd(N1‐X)] were synthesized and characterized in solution and solid‐state (X‐ray diffraction) revealing an arrangement similar to that of natural Watson–Crick base pairs. Subsequently, 1Pd‐DNA hybrids were prepared, characterized, and their structures studied by small‐angle X‐ray scattering (SAXS) and ab‐initio calculations. The results indicate that the 1Pd‐DNA structures resemble that of double‐stranded DNA, with one strand being replaced by a supramolecular stack of continuous PdII complexes.

A fast numerical method of introducing the strengthening effect of residual stress and strain to tensile behavior of metal matrix composites

Thermal residual stress and strain (TRSS) in particle reinforced metal matrix composites (PRMMCs) are believed to cause strengthening effects, according to previous studies. Here, the representative volume element (RVE) based computational homogenization technique was used to study the tensile deformation of PRMMCs with different particle aspect ratios (AR). The influence of TRSS was assessed quantitatively via comparing simulations with or without the cooling process. It was found that the strengthening effect of TRSS was affected by the particle AR. With the average strengthening effect of TRSS, a fast method of introducing the strengthening effect of TRSS to the tensile behavior of PRMMCs was developed. The new method has reduced the computational cost by a factor 2. The effect of TRSS on continuous fiber-reinforced metal matrix composite was found to have a softening-effect during the entire tensile deformation process because of the pre-yield effect caused by the cooling process.

Ultra-Broadband Infrared Metamaterial Absorber for Passive Radiative CoolingSupported by the National Natural Science Foundation of China (Grant Nos. 52022018 and 52021001), and the Program for Changjiang Scholars and Innovative Research Team in University.

Infrared metamaterial absorber (MMA) based on metal-insulator-metal (MIM) configuration with flexible design, perfect and selective absorption, has attracted much attention recently for passive radiative cooling applications. To cool objects passively, broadband infrared absorption (i.e. 8–14 μm) is desirable to emit thermal energy through atmosphere window. We present a novel MMA composed of multilayer MIM resonators periodically arranged on a PbTe/MgF2 bilayer substrate. Verified by the rigorous coupled-wave analysis method, the proposed MMA shows a relative bandwidth of about 45% (from 8.3 to 13.1 μm with the absorption intensity over 0.8). The broadband absorption performs stably over a wide incident angle range (below 50°) and predicts 12 K cooling below ambient temperature at nighttime. Compared with the previous passive radiative coolers, our design gets rid of the continuous metal substrate and provides an almost ideal transparency window (close to 100%) for millimeter waves over 1 mm. The structure is expected to have potential applications in thermal control of integrated devices, where millimeter wave signal compatibility is also required.

Sacrificial gold coating enhances transport of liquid metal in pressurized fountain pen lithography

Liquid metals have attracted attention as functional components for moldable electronics, such as soft flexible connectors, wires or conductive ink. The relatively high surface tension (> 400 mN m−1) and the fact that liquid metals do not readily wet ceramic or oxide surfaces have led to devising unique techniques to spread the liquid and mold its shape. These techniques include surface modification, electrowetting and vacuum filling of channels. This work presents an injection technique based on pressurized fountain pen lithography with glass nanopipettes developed to directly pattern liquid metal on flat hard substrates. The liquid metals were eutectic alloys of Gallium, including Gallium-Indium (EGaIn), Gallium-Indium-Zinc and Gallium-Indium-Tin. The nanopipettes were coated internally with gold, acting as a sacrificial layer and facilitating the wetting of the pipette down to its pore, with an inner diameter of ~ 100–300 nm. By applying hydrodynamic pressure to the connected end of the pipette, the metal was extruded through the pore, forming long continuous (> 3 mm) and narrow (~ 1–15 µm) metal lines on silicon oxide and gold surfaces at room temperature and ambient conditions. With this robust platform, it is possible to pattern liquid metals on a variety of substrates and geometries down to the micron range.