Internal Metal Research Articles

The internal metallicity distributions of simulated galaxies from EAGLE, Illustris, and IllustrisTNG at z = 1.8–4 as probed by gamma-ray burst hosts

ABSTRACT Massive stars are thought to be progenitors of long gamma-ray bursts (GRBs), most likely with a bias favouring low-metallicity progenitors. Because galaxies do not have a constant metallicity throughout, the combination of line-of-sight absorption metallicity inferred from GRB afterglow spectroscopy and of host galaxy global metallicity derived from emission lines diagnostics represents a powerful way to probe both the bias function for GRB progenitors and the chemical inhomogeneities across star-forming regions. In this study, we predict the relationship between Zabs and Zemiss using three different hydrodynamical cosmological simulations: Illustris, EAGLE, and IllustrisTNG. We find that while the qualitative shape of the curve relating emission versus absorption metallicity remains the same, the predicted relationship between these two observables is significantly different between the simulations. Using data for the host galaxy of GRB121024A for which both Zabs and Zemiss have been measured, we find marginal support for the Illustris simulation as producing the most-realistic internal metallicity distributions within star-forming galaxies at cosmic noon. Overall, all simulations predict similar properties for the bulk of the GRB host galaxy population, but each has distinct features in the tail of the Zabs-Zemiss distribution that in principle allow to discriminate between models if a sufficiently large sample of observations are available (i.e. N ≳ 11 on average). Substantial progress is expected in the near future, with upcoming JWST/NIRspec observations of 10 GRB host galaxies for which absorption metallicity from the afterglow spectra exists.

Вільна конвекція — дослідження регулярного теплового режиму в різних шарах по висоті рідини

The rate of cooling (heating) of experimental liquids is investigated separately for five thermocouples located at different heights of the experimental probe. Research is carried out on an experimental stand in the system "environment I — body II", where "environment I" is water, and "body II" is the investigated liquid medium in a thin metal cylindrical shell under conditions of free convection. The rate of cooling (heating) is studied for test liquids: water, sunflower oil, distilled glycerin. The analysis of cooling (heating) processes during free convection of non-stationary heat exchange is carried out. This paper presents research carried out on an experimental stand, which consists of an external metal vessel, containing the environment with a temperature of t1, an internal cylindrical metal vessel containing an experimental liquid medium with a temperature of t2. Accordingly, probes with five thermocouples are placed in hot and cold liquids to take temperature values at a fixed time Non-stationary heat conduction processes occur during heating or cooling of bodies, substances, gaseous media and are accompanied by a change in enthalpy. Non-stationary and stationary processes of body heating due to the internal heat source, the electric heater, are considered in laboratory practice to determine the thermophysical properties of materials, bodies of substances and where cooling occurs due to the surrounding air. The analysis of the excess temperature, carried out separately for each thermocouple, placed along the height of the cylindrical volume, shows that the linearity of the dependence Ln ϑ = f(τ) is preserved, while the influence of free convection on the value of m is manifested. The value of m depends on the height of the liquid layer in which the temperature is measured.

Micro-environment Corrosion Strength Based on Quartz Crystal Microbalance

Equipment service environment often has a certain corrosive, accelerate equipment corrosion, affect the integrity of equipment. In order to accurately monitor the micro-environment corrosion strength of the equipment, the multi-channel quartz crystal microbalance calibration test and the crystal vibration sensor temperature supplement test were carried out to realize the frequency-quality signal conversion of the quartz crystal vibration sensor and improve the accuracy of data acquisition of the device. Using a multi-channel quartz crystal microbalance, For an equipment micro-environment under the hot and humid ocean environment, Packaging box under warm and wet acid rain environment, For 30h, respectively, 65h Continuous in situ monitoring, The test data showed that the mass gain of a 30h copper crystal vibration sensor is 0.5 μg, The rate of mass change was 0.017 μg/h, High corrosion strength, Metal materials in this area are prone to corrosion, Key protection is required; The 65h mass temperature increase: 0.022 μg, The rate of mass change was 0.000034 μg/h, Low corrosion strength, The internal metal material is corroded slowly.

End-of-Charge Temperature Rise and State-of-Health Evaluation of Aged Lithium-Ion Battery

An increasing demand to repurpose used lithium-ion batteries in secondary applications is driving the need to develop methods of evaluating the state-of-health of used batteries. In this paper, we discover a self-terminated end-of-charge temperature rise (ECTR) phenomenon in 18650 lithium-ion cells, both recycled from the field and aged under controlled conditions in the lab. ECTR is characterized by an additional temperature rise near the end of the charging process and is accompanied by low coulombic efficiency. A higher charge rate and longer inactive time at low state-of-charge appear to increase the occurrence of ECTR. The intensity of ECTR is found to closely correlate with the excess charge capacity but is less affected by the charge current or cell impedance. ECTR is weakly dependent on the remaining cell capacity in recycled cells, and the controlled aging study shows that aging condition, not remaining capacity or internal resistance, determines the presence and intensity of ECTR behavior, which indicates that usable capacity or internal resistance should not be the single criterion to effectively evaluate the state-of-health of used cells intended for repurposing. We hypothesize that the origin of the ECTR is due to the formation of an internal lithium metal short that forms near the end of the charge process and self-terminates over time. The investigation of ECTR in this work provides a new criterion and approach to evaluate the state-of-health of cells required to safely handle aged/recycled cells.

Investigation into Friction and Wear Characteristics of 316L Stainless-Steel Wire at High Temperature

The damping performance of metal rubber is highly correlated with the tribological properties of the internal metal wires. In this paper, the friction and wear characteristics of 316L stainless-steel wire are investigated under different temperatures, loads, crossing angles, and working strokes. Results show that the friction coefficient increases from 0.415 to 0.635 and the wear depth increases from 34 μm to 51 μm, with the temperature rising from 20 °C to 400 °C. High temperature will soften metal materials and promote the oxidation of metal. Softened materials can be easily sheared and removed under friction action, resulting in high wear depth. However, when a continuous oxide film with high hardness is formed under higher temperature, the oxide film can work as a wear-resisting layer to prevent further wear of the wire to a certain degree. At the same temperature, the loads, crossing angles, and working strokes change the wear resistance by affecting the surface stress, debris removal efficiency, etc., and high temperature will aggravate this change. The results pave the way for the design and selection of materials for high-temperature metal rubber components.

High-precision abundances of first-population stars in NGC 2808: confirmation of a metallicity spread

Photometric investigations have revealed that Galactic globular clusters (GCs) exhibit internal metallicity variations amongst the so-called first-population stars, which until now were considered to have a homogeneous initial chemical composition. This is not fully supported by the sparse spectroscopic evidence, which so far gives conflicting results. Here, we present a high-resolution re-analysis of five stars in the Galactic GC NGC 2808 taken from the literature. Target stars are bright red giants with nearly identical atmospheric parameters belonging to the first population according to their identification in the chromosome map of the cluster, and we measured precise differential abundances for Fe, Si, Ca, Ti, and Ni to the ∼0.03 dex level. Thanks to the very small uncertainties associated with the differential atmospheric parameters and abundance measurements, we find that target stars span a range of iron abundance equal to 0.25 ± 0.06 dex. The individual elemental abundances are highly correlated with the positions of the stars along the extended sequence described by first-population objects in the cluster chromosome map: bluer stars have a lower iron content. This agrees with inferences from the photometric analysis. The differential abundances of all other elements also show statistically significant ranges that point to intrinsic abundance spreads. The Si, Ca, Ti, and Ni variations are highly correlated with iron variations and the total abundance spreads for all elements are consistent within the error bars. This suggests a scenario in which short-lived massive stars exploding as supernovae contributed to the self-enrichment of the gas in the natal cloud while star formation was still ongoing.

Anion Binding as a Strategy for the Synthesis of Porous Salts.

Porous salts have recently emerged as a promising new class of ultratunable permanently microporous solids. These adsorbents, which were first reported as ionic solids based on porous cations and anions, can be isolated from a wide variety of charged, permanently porous coordination cages. A challenge in realizing the full tunability of such systems, however, lies in the fact that the majority of coordination cages for which surface areas have been reported are comprised of charge-balanced inorganic and organic building blocks that result in neutral cages. As such, most reported permanently porous coordination cages cannot be used as reagents in the synthesis of porous salts. Here, we show that the facile reaction of TBAX (TBA+ = tetra-n-butylammonium; X = F- and Cl-) with molybdenum paddlewheel-based coordination cages of the M4L4 and M24L24 lantern and cuboctahedra structure types, respectively, affords charged cages by virtue of coordination of halide anions to the internal and/or external metal sites on these structures, as confirmed by single-crystal X-ray diffraction, X-ray photoelectron spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. At a practical level, the TBAX/cage reactions, which are fully reversible upon isolation of the cage with the appropriate solvent, solubilize otherwise rigorously insoluble cages. This method significantly increases the solution processability of these highly porous solids. Toward the formation of new porous salts, halide binding also serves to incorporate charge on neutral cages and make them amenable to simple salt metathesis reactions to afford new porous salts based on anions and cations with intrinsic porosity. A combination of diffraction methods and a suite of spectroscopic tools confirms speciation of the isolated solids, which represent a new class of highly tunable porous salts. Ultimately, this work represents a roadmap for the preparation of new porous solids and showcases the utility and broad applicability of anion binding as a strategy for the synthesis of porous salts.

Molecular Dynamics Simulations of Polydopamine Nanosphere's Structure Based on Experimental Evidence.

In this work, we show how to obtain internal monodispersed gold nanoparticles inside polydopamine (PDA) nanospheres that are also externally decorated with gold. The number of internal nanoparticles is affected by the size of the PDA nanosphere used, and the lower limit in the number of gold nanoparticles in the center of decorated nanospheres, one single gold nanoparticle, has been reached. In addition, extensive molecular dynamics simulations of PDA nanospheres based on four different chemical motifs, in the presence of water and with different sizes, have been performed to gain insight into the arrangements capable of accommodating cavities. In particular, PDA nanospheres based on pyranoacridinotrione (PYR) units provide good agreement with the experimental attainment of internal metal nanoparticles. In these, the stacking of PYR units leads to a particular morphology, with large portions of space occupied by the solvent, that would explain the observed formation of gold nanoparticles inside the PDA nanosphere.

In situ investigation of aluminum oxide under irradiation by electron beam at atomic-scale

It has yet to be experimentally proven whether the native aluminum oxide layer can still effectively protect pure aluminum from further degradation under an irradiation environment. Here, we directly investigate the microstructure evolution of amorphous Al2O3 in real time by using an electron beam as an irradiation source with in-situ transmission electron microscopy (TEM). At the atomic scale, crystalline Al2O3 grains were found to nucleate and grow along amorphous substrate. With continuous irradiation, both amorphous and newly formed crystalline Al2O3 were removed completely, and then the internal fresh aluminum was exposed. By regulating electrons, new oxides quickly formed on the fresh metal surface and merged with adjacent old oxides, finally leaving a uniform amorphous oxide protection layer. Our work provides experimental evidence for understanding the protection mechanism for the oxide layer on its internal metal under a special service environment.

Collapse of composite-repaired cylinders with internal metal loss subjected to external hydrostatic pressure

The present study investigates the collapse performance of composite-repaired cylinders with internal metal loss subjected to external pressure. Three groups of intact, thinned, and repaired cylinders were designed, analytically verified, fabricated, geometrically measured, externally tested, and numerically modeled. Each group had three nominally identical cylinders to ensure the repeatability of experiments. The cylinders had the same end closure, effective length, total length, external radius, and intact thickness for an equivalent comparison. The thinned cylinder was considered as the intact cylinder with internal metal loss, whereas the repaired cylinder was considered as the thinned cylinder with composite reinforcement. The results indicated that the external loading capacity of cylinders with internal metal loss could be fully restored and even enhanced by composite reinforcement. Composite-repaired cylinders are much less sensitive to initial geometrical imperfections than intact cylinders.

Toxicokinetics and toxicodynamics of chromium in the soil invertebrate Enchytraeus crypticus (Oligochaeta)

Chromium emissions led to increased concentrations in soil, where it can affect soil organisms to relevant levels. With the aim of better understanding the effects of Cr throughout time, its toxicokinetics-toxicodynamics (TKTD) were evaluated in the soil model organism Enchytraeus crypticus to assess the development of internal concentrations and consequent toxic effects. To achieve this goal, organisms were exposed in LUFA 2.2 soil spiked with increasing CrCl3 concentrations. During the 21-day exposure period, survival, internal concentrations, and reproduction were evaluated at several time points up to 21 days. Uptake and elimination rate constants were 0.0044 kg soil/kg organism/day and 0.023 per day, respectively. Internal Cr concentrations increased with time, generally reaching equilibrium within 14 days with an estimated LC50inter (based on internal metal concentrations) of 57.7 mg Cr/kg body DW. Internal Cr concentrations were regulated by the organisms up to exposure to 360 mg Cr/kg soil DW, where the elimination rate was highest, but at 546 mg Cr/kg soil DW the animals were no longer able to eliminate Cr, and the internal concentrations were well above the estimated LC50inter. At day 21, exposure to 546 mg Cr/kg soil DW significantly reduced survival by 23 %, while reproduction EC50 was 344 mg Cr/kg soil DW. This study highlights the advantages of using a TKTD approach to understand the development of internal metal concentrations in time and relate it to the phenotypical effects observed. Toxicity is better understood when also taking into account time and not just exposure concentration alone.

Broadband Graphene-Based Electro-Optic Chiral Polarization Conversion for Terahertz Pulse Shaping

Terahertz (THz) radiation is ideally suited for noninvasive testing and short-distance data transmission. Actively controlling the polarization of THz waves is highly desirable in measurement systems. Although significant developments of THz active devices has been achieved through introducing the electromagnetic resonance structure (e.g., metamaterials), the bandwidth is limited. Here, we propose a graphene-based electrically reconfigurable polarization conversion across a broadband THz region (0.3 to 0.9 THz) for controlling the chiral polarization of terahertz pulse. By electrically controlling the graphene conductivity, we can switch the device reflection in-between total internal reflection and metal mirror reflection to realize a frequency-independent phase change, which enables a tunable waveplate with a high dynamic range for manipulating the polarization of THz waves. Because of the frequency-independent modulation property, we achieved tunable chiral polarization THz waveforms in the time domain for the first time, from right-handed to left-handed polarization. This work opens up a new mechanism for designing novel THz modulators for THz circular dichroism.

Structural Design of Ocean Temperature and Depth Sensor with Quick Response and High Sensitivity

The electrical sensing elements used in the traditional XBT (Expendable Bathythermograph) have problems such as low sensitivity and slow response time, and it is difficult to overcome the complex marine environment using the time–depth formula. In this paper, an ocean temperature depth sensor based on brass diaphragm and liquid filling is designed. The stress response time of FBGs with different lengths and the heat transfer time of different liquid materials are compared, and it is found that a fast response of 51 ms can be obtained by using GaInSn liquid for temperature sensing. The center deflection changes of brass diaphragms with different radii are analyzed, and the brass diaphragms with radius and thickness of 10 mm and 1 mm are selected, which still have good elastic properties under the pressure of 5 MPa. The influence of the inner metal shell section radius on the temperature and depth sensitivity is analyzed. When the final section radius is 3 mm, the temperature sensitivity of the sensor is 1.065 nm/°C, the pressure sensitivity is 1.245 nm/MPa, and the response time of temperature and depth is relatively close. Compared with the traditional temperature and depth sensors using empirical formulas for calculation, the data accuracy is improved, and a wide range of sensitivity can be tuned by adjusting the size of the internal metal shell, which can meet the needs of ocean temperature and depth data detection with high sensitivity and fast response time.

Metal sandwich and ion complexes in cyclacene nanobelts

Cyclacene carbon nanobelts represent the last unsynthesized building blocks of carbon nanotubes and are the shortest possible hydrogen capped nanotubes of zigzag type. Recent theoretical predictions indicate that stable cyclacene isomers containing Dewar benzene derived structures may exist. The properties of the Hückel-[n]cyclacene nanobelt complexes containing alkali metal and halide ions (n = 5-8), with zero to two Dewar benzenoid structures present, and transition metal complexes (n = 6, 8) with zero and two Dewar structures present, have been calculated using density functional theory. The halides, alkali metals, and transition metals were initially placed centrally within the belt cavities, and binding interactions have been observed for both positive and negative ions. The most stable isomeric forms are found to change for several of the belt sizes, depending on which ions are present. Internal transition metal sandwich complexes with η6-haptic bonds are also indicated to form within the cyclacene belts containing two Dewar benzenoids.

An ultra-thin interlayer bimetallic sulfide for enhancing electrons transport of supercapacitor electrode

Improving the sluggish reaction kinetics and intrinsic inferior electrical conductivity of metal oxides has always been a difficult and important issue. Integration engineering is proposed to effectively solve the above problem, namely, composite modification of metal oxides by materials with high conductivity and high specific surface area. Herein, a nanobelt of bimetallic sulfide/transition metal oxide (CoNiS/MoO3, CSM) composite is designed to improve the electrical conductivity of metal oxides without affecting the morphologic characteristics of materials. Thin-layer CoNiS acts as a channel for electrons and provides a protection for internal metal oxides. And then, in-situ polymerization polyaniline is utilized to strengthen the overall material and improve the specific surface area of the composite material. The CoNiS/MoO3@Polyaniline (CSMP) composites exhibit a considerably high specific capacitance (1884 F g−1 at 1 A g−1) and noticeable cycling capability (92.9 % capacitance retention at 20 A g−1 after 3000 cycles) in three-electrode systems. When CSMP composites are assembled into asymmetric supercapacitor devices, the resultant devices deliver a superior energy density of 86 Wh kg−1 at a power density of 840 W kg−1, admirable cycling stability of 95.6 % and high coulombic efficiency of 99.4 % after 10,000 repeated cycles. In particular, the charge storage mechanism is analyzed in detail based on CV tests, revealing that the surface-controlled capacitive process gradually dominates as scan rate increases. The excellent electrochemical performance well confirms the superiority of the synergistic effects of each component and the elaborate design of the conducting interlayer.

Leveraging negative capacitance ferroelectric materials for performance boosting of sub-10 nm graphene nanoribbon field-effect transistors: a quantum simulation study

In this paper, an ultrascaled ballistic graphene nanoribbon field-effect transistor (GNRFET) endowed with a compound double-gate based on metal-ferroelectric-metal (MFM) structure is proposed to overcome the limitations encountered with its conventional counterpart. The ballistic transistor is computationally investigated by solving self-consistently the non-equilibrium Green’s function formalism and the Poisson solver in conjunction with the Landau–Khalatnikov equation. The numerical investigation has included the ferroelectric-induced amplified internal metal voltage, the role of the ferroelectric thickness in boosting the device performance, the assessment of the switching and subthreshold performance, and the analysis of the FE-GNRFET scaling capability. The simulations revealed that the MFM-based gate can significantly boost the performance of GNRFETs, including the switching behavior, the on-current, the off-current, the current ratio, the swing factor, the intrinsic delay, and the scaling capability. More importantly, the proposed MFM GNRFET was found able to provide sub-thermionic subthreshold swing even with sub-10 nm gate lengths, which is very promising for low-power applications. The obtained results indicate that the MFM-based gating approach can give new impulses to the GNRFET technology.

A review of phase change materials (PCMs) in electronic device cooling applications

Due The portable electronic devices in everyday life have been getting increasingly compact day by day, and with the advancement in wireless technology, they are expected to facilitate multitasking. In this context, efficient heat dissipation to maintain consistent thermal performance has become quite a challenge. Phase change materials (PCMs) have emerged as a viable option to eliminate problems regarding the thermal management of compact electronics. This review looks into the different types of PCMs investigated by researchers so far, especially in the case of cooling compact electronic devices. It also discusses the parameters critical to its efficiency and implementation, encapsulation, etc. The merit of internal fins, nanomaterials, and metal foams as thermal conductivity enhancers along with shortcomings in the current literature have also been noted in this review.

Improvement of Device Characteristics of Low Temperature IGZO Thin-film Transistors through Laser Post Annealing

High-performance thin-film transistors (TFTs) produced at low temperatures are required for ultrahigh- resolution and flexible display applications. The scientific community has been studying unconventional techniques to investigate low voltage flexible devices and low power flexible circuits for the past decade. In particular, metal oxide semiconductors, such as indium gallium zinc oxide (IGZO), have made significant progress as amorphous silicon replacements for electronics and commercial displays. On the other hand, developing metal oxide transistors with low processing temperatures remains a difficulty. The hightemperature annealing process causes very instability in the plastic substrate. Here, we introduce IGZO TFTs that shows enhanced electrical properties environmental stability by laser post-annealing. After annealing process, the laser post-annealing process was given at 80 MHz, pulse width 140 fs, for 50 seconds. The improved electrical characteristics of this laser post-annealed IGZO TFTs were: 9.03 cm<sup>2</sup>/Vs; 2.2×10<sup>7</sup> on/off current ratio. The IGZO TFT to which laser post-annealing was applied had a flat surface, and it was confirmed that the combination of internal metal and oxygen was urged, and the leakage current problem was improved by suppressing excessive generation of oxygen vacancy. Furthermore, the voltage transfer curve was measured after fabricating the N-MOS logic inverter circuit, this inverter showed a value of 80.8% the total noise margin.

Insights to the 3D internal morphology and metal oxidation states of single atmospheric aerosol particles by synchrotron-based methodology

The morphology and metal oxidation states of atmospheric aerosols are pertinent to their formation processes and ensuing interactions with surrounding gases, vapors and other environments upon deposition, such as human respiratory tract, soil and water. Although much progress has been made in recent years through single-particle techniques, considerably less is known with respect to the three-dimensional (3D) internal morphology of single atmospheric aerosol particles due to the limited penetration depth of electron microscopy. In this study, for the first time, a novel synchrotron-based transmission X-ray microscopy (TXM) methodology has been developed to visualize the 3D internal chemical mixing state and structure of single particles. The results show that the TXM is more applicable to the imaging of solid particles containing high-density elements, e.g., iron (Fe), aluminum (Al), silicone (Si), carbon (C) and sulfur (S), and/or solid particles of sizes larger than about 100 nm. In addition, the TXM is capable to reveal the fine 3D topographic features of single particles. The derived 3D internal and external information would be difficult to discern in the 2D images from electron microscopy. The TXM 3D images illustrate that aerosol particles exhibit complex internal mixing state and structure, e.g., homogeneously-, heterogeneously-mixed, multiple inclusions, fibrous, porous, and core-shell configuration. When coupled with the synchrotron-based X-ray fluorescence spectrometry (XRF) and absorption near-edge spectroscopy (XANES) of an X-ray nanoprobe in the energy range of 4–15 keV, the 3D morphology of single particles is further supplemented with the spatial distribution and oxidation sates of selected elements, including Fe, vanadium (V), manganese (Mn), chromium (Cr) and arsenic (As). The presented cross-platform, synchrotron-based methodology shows promise in complementing existing single-particle techniques and providing new insights to the heterogeneity of single-particle micro-physicochemical states relevant to the aerosol chemistry, optical properties, and their environmental and health impacts.

Fretting wear evolution model of the metal filaments inside metal rubber

Metal rubber (MR) is a porous material which possesses macroscopic damping properties through the dry friction between the internal helical metal wires. Due to its complex topological structure, the research on the fretting wear of MR is rarely reported in the literature. In the present work, a double-body wear model of metal filaments is constructed by the master-slave composite method. The friction and wear conditions of the dynamic and static metal wires inside the MR are analyzed under different contact angles, loads, and vibration amplitudes. The results indicate that the wear area and volume of the dynamic wire under each working condition are significantly larger than those of the static wire, while the case for the wear depth is the opposite. After wear, the wires exhibit an obvious stress concentration phenomenon, which is distributed along the wire wear contour area, and the wear profile has a high sensitivity to the contact angle. In order to further investigate the difference in the wear degree of the static and dynamic wires inside the MR, the fretting amplitude is introduced to describe the wear scar area of the dynamic wire, the special wear scar area is reorganized regularly, and the wear volume of the wire is approximated by the regional combination, deriving and constructing a fretting wear evolution model suitable for MR wires. This evolution model can simultaneously predict the wear degree of dynamic and static wires, and its prediction accuracy is high. The prediction accuracy under each working condition is basically less than 10%; thus, the proposed model can be effectively applied to the fretting wear prediction of MR ultra-fine wire contact pairs. This work provides theoretical guidance for the life prediction and other aspects of MR materials.