Pure Elements Research Articles

Efficient generation of longitudinally polarized light needle with diffractive optical elements

Longitudinally polarized beams have unique properties that are different from a traditional transversely polarized beam. By modulating the amplitude, phase and polarization of the incident beam, various longitudinal polarization fields can be obtained in a large-numerical aperture focusing system. Here we propose a simple and efficient method to generate longitudinally polarized light needle with pure phase element and radially polarized Gaussian beam. The phase element is designed with simulated annealing algorithm. The high purity longitudinally polarized light needle formed near the focal point has a horizontal full width at half maximum of 0.39λ and a non-diffraction distance of 4λ. This method can be employed to design other pure phase elements for generating beams with special longitudinal polarization distributions.

Ionic thermoelectric effect of pure cement paste and its temperature sensing performance

Incorporating functional fillers into the cement matrix can provide cement-based materials with electronic carriers to enhance the electronic thermoelectric effect for the utilization in the future intelligent infrastructures. However, incorporating multiple types and high amounts of functional fillers might increase the cost, degrade the mechanical properties, and hinder the wider application of the intelligent cement-based composites. In this study, the electrical conductivity and the thermoelectric effect of the pure cement paste after sealed curing, after drying, and after leaching are investigated as a potential highly efficient thermoelectric material. The mechanism of the ionic thermoelectric effect is discovered and evaluated. The temperature sensing properties of the pure cement paste under the gradient heating and the temperature cycles are measured. In addition, a cement-based temperature sensor is further developed, and its temperature sensing performance is tested. It is found that the pure cement paste exhibits an ionic thermoelectric effect due to the existence of ions in the pore solution, with the advantages of high Seebeck coefficient, high electrical conductivity, and low cost. The temperature sensor consisting of four pure cement paste elements saturated for 3 hrs followed by leaching for 72 hrs endorses a good sensing performance to temperature changes. The findings in this study show promising utilization possibilities of the thermoelectric cement-based materials in the field of constructing intelligent infrastructures.

Electrochemical Performance and Hydrogen Storage of Ni–Pd–P–B Glassy Alloy

The search for hydrogen storage materials is a challenging task. In this work, we tried to test metallic glass-based pseudocapacitive material for electrochemical hydrogen storage potential. An alloy ingot with an atomic composition of Ni60Pd20P16B4 was prepared via arc melting of extremely pure elements in an Ar environment. A ribbon sample with a width of 2 mm and a thickness of 20 mm was produced via melt spinning of the prepared ingot. Electrochemical dealloying of the ribbon sample was conducted in 1 M H2SO4 to prepare a nanoporous glassy alloy. The Brunauer-Emmett-Teller (BET) and Langmuir methods were implemented to obtain the total surface area of the nanoporous glassy alloy ribbon. The obtained values were 6.486 m2/g and 15.082 m2/g, respectively. The Dubinin-Astakhov (DA) method was used to calculate pore radius and pore volume; those values were 1.07 nm and 0.09 cm3/g, respectively. Cyclic voltammetry of the dealloyed samples revealed the pseudocapacitive nature of this alloy. Impedance of the dealloying sample was measured at different frequencies through use of electrochemical impedance spectroscopy (EIS). A Cole-Cole plot established a semicircle with a radius of ~6 Ω at higher frequency, indicating low interfacial charge-transfer resistance, and an almost vertical Warburg slope at lower frequency, indicating fast diffusion of ions to the electrode surface. Charge-discharge experiments were performed at different constant currents (75, 100, 125, 150, and 200 mA/g) under a cutoff potential of 2.25 V vs. Ag/AgCl electrode in a 1 M KOH solution. The calculated maximum storage capacity was 950 mAh/g. High-rate dischargeability (HRD) and capacity retention (Sn) for the dealloyed glassy alloy ribbon sample were evaluated. The calculated capacity retention rate at the 40th cycle was 97%, which reveals high stability.

Surface tension of liquid Ti, V and their binary alloys measured by electromagnetic levitation

AbstractThe surface tension of the liquid Ti-V system is systematically measured using the oscillating drop technique during electromagnetic levitation. Temperature- and compositional dependence are both investigated. The entire compositional range is covered. A linear decrease with increasing temperature is found for the pure elements as well as for all investigated alloys. The surface tension generally increases with increasing V-content. The obtained data are in good agreement with the Butler model for the ideal solution. Additionally, the Butler model for the regular solution was evaluated in the context of the obtained surface tension data. In contrast to many other Ti-based alloys, the Butler model for the regular solution yields no additional benefit for Ti-V, since there is only a neglectable small deviation between the calculations for the ideal and regular solution. Segregation effects are modeled using the Butler equation for an ideal solution. The findings are discussed considering already existing trends for the mixing behavior of liquid Ti-alloys. The results strongly suggest, that the Ti-V system obeys in general the ideal solution law.

Computational design of corrosion-resistant and wear-resistant titanium alloys for orthopedic implants

Titanium alloys are promising candidates for orthopedic implants due to their mechanical resilience and biocompatibility. Current titanium alloys in orthopedic implants still suffer from low wear and corrosion resistance. Here, we present a computational method for optimizing the composition of titanium alloys for enhanced corrosion and wear resistance without compromising on other aspects such as phase stability, biocompatibility, and strength. We use the cohesive energy, oxide formation energy, surface work function, and the elastic shear modulus of pure elements as proxy descriptors to guide us towards alloys with enhanced wear and corrosion resistance. For the best-selected candidates, we then use the CALPHAD approach, as implemented in the Thermo-Calc software, to calculate the phase diagram, yield strength, hardness, Pourbaix diagram, and the Pilling-Bedworth (PB) ratio. These calculations are used to assess the thermodynamic stability, biocompatibility, corrosion resistance, and wear resistance of the selected alloys. Additionally, we provide insights about the role of silicon on improving the corrosion and wear resistance of alloys.

Photocatalytic and antibacterial properties of NaTaO3 nanofilms doping with Mg2+, Ca2+ and Sr2+

In this research, we prepared pure and alkaline earth metal elements (Mg2+, Ca2+ and Sr2+) doped NaTaO3 nanofilms by a simple hydrothermal method. Compared with traditional powder photocatalysts, they possess better stability and recycling performance, which makes them more practical in wastewater treatment. The as-prepared NaTaO3 crystals show nanoscale grain size that increases its redox ability owing to the small size effect and surface effect. After further introduction of Mg2+, Ca2+ and Sr2+, the band gaps were reduced to 2.83, 3.01 and 2.96 eV, respectively. Meanwhile, elemental doping induces a phase transition in the crystal structure of NaTaO3, creating an additional energy level that improves its responsiveness to visible light. According to the results, Mg-NaTaO3 catalyst possessed a higher photodegradation efficiency of 80.1 % for methylene blue solution under visible light irradiation. Furthermore, the photocatalytic bactericidal performance of different samples was investigated with Gram-positive and negative bacteria. In particular, the ROS (⋅O2–, ⋅OH, 1O2) induced by Mg-NaTaO3 could effectively destroy cell membranes, and the inhibition effect on E. coli and S. aureus reached 99.99 % within 50 min. Lastly, the results of cyclic photocatalytic experiments showed that Mg-NaTaO3 still had a high photodegradation capacity (75.2 %) and sterilization performance (98.8 %) after three cycles.

Fermi-Liquid Nonadiabatic Highly Compressed Cesium Iodide Superconductor

The experimental discovery that compressed sulfur hydride exhibits superconducting transition temperature of Tc=203 K by Drozdov et al. (Nature 2015, 525, 73–76) sparked studies of compressed hydrides. This discovery was not a straightforward experimental examination of a theoretically predicted phase, but instead it was a nearly five-decade-long experimental quest for superconductivity in highly compressed matters, varying from pure elements (hydrogen, oxygen, sulfur), hydrides (SiH4, AlH3) to semiconductors and ionic salts. One of these salts was cesium iodide, CsI, which exhibits the transition temperature of Tc≅1.5 K at P=206 GPa (Eremets et al., Science 1998, 281, 1333–1335). Detailed first principles calculations (Xu et al., Phys Rev B 2009, 79, 144110) showed that CsI should exhibit Tc~0.03 K (P=180 GPa). In an attempt to understand the nature of this discrepancy between the theory and the experiment, we analyzed the temperature-dependent resistance in compressed CsI and found that this compound is a perfect Fermi liquid metal which exhibits an extremely high ratio of Debye energy to Fermi energy, ℏωDkBTF≅17. This implies that direct use of the Migdal–Eliashberg theory of superconductivity to calculate the transition temperature in CsI is incorrect, because the theory is valid for ℏωDkBTF≪1. We also showed that CsI falls into the unconventional superconductors band in the Uemura plot.

Soma

Soma is an abstract comic exploring the relationship between the creative act and mental health with an emphasis on embodiment. The title derives from the Greek term as used in Homer’s Iliad, where the word is used to refer not simply to the body, but to the dead body and also refers to the intoxicant used in Vedic ritual. As an abstract comic, the emphasis is not on narrative momentum or the development of an argument, but rather the cultivation of a tone or mood. In line with this, the comic’s visual approach partly takes its inspiration from black metal and other extreme forms of music, where the lyrics’ deliberate indecipherability recasts them as pure musical elements rather than conveyors of information. In a similar vein Soma’s use of words is intended as primarily rhythmical rather than information-bearing; rendered in such a way as to make them at times illegible, they become subsumed into the design. This strategy lies parallel to the aim of the comic as a whole: the reintegration of mind and body through the creative act here imagined as an act of self-cannibalization, recasting, in the terms of the title, the dead body as a ritual intoxicant.

Prognostic relevance of mixed histological subtypes in invasive breast carcinoma: a retrospective analysis

PurposeThe prognostic and therapeutic power of special histological subtypes in breast cancer in pure form or in combination with other histological subtypes is still not established, and diagnostic guidelines are cautious regarding prognostic power based on the histological subtype alone. Therapy decisions are guided in most cases independently of the histological subtype and are directed by biomarkers and tumor stage. In this study, we analyzed a comprehensive large retrospective breast cancer cohort with a special focus on histological subtype (other than ductal non-special type or lobular carcinoma) and correlated pure or mixed histological forms with pathological tumor stage and overall disease-free survival.Materials and methodsA total of 827 breast cancer cases with pure or mixed special histological types were retrospectively analyzed. Survival information was available in 645 of 827 cases.ResultsA total of 293 cases had pure forms, and 534 cases had mixed histological subtypes. The most common pure special types were mucinous (23.9%), micropapillary (21.2%), high-grade metaplastic (13%), male breast cancer (8.2%), cribriform (6.8%), metastases (6.1%), apocrine and papillary (each 5.46%), NST with medullary and clear cell pattern (up to 3.4%) and high-grade neuroendocrine carcinomas (2.7%). Mixed forms were most frequently encountered in NST carcinomas with micropapillary components (41.8%), followed by mucinous (9.93%) and cribriform (6.74%) mixed patterns. In univariate analysis, no pure form had prognostic relevance compared with any mixed form with the basic pure element. Pooling pure histological subtypes with tumor stage and age in a linear random-effects model, the cribriform subtype had the most favorable prognosis, while male breast cancer showed the poorest outcome (p < 0.001). All other frequent pure forms had intermediate prognostic power (p < 0.001).ConclusionOur results show that the analyzed special histological breast cancer subtypes (other than ductal and lobular carcinomas) do not carry prognostic information alone, either in pure form or in any combination with other subtypes. Prognostic groups including special subtypes, however, can strongly stratify breast cancer if tumor stage, age and biomarkers are included in the prognostic measurements.

Selenium and Tellurium Separation: Copper Cementation Evaluation Using Response Surface Methodology

In recent years, high demands for Se and Te in the solar panels and semiconductors industry have encouraged its extraction from primary and secondary sources. However, the two elements’ similar chemical and physical properties make pure element production, Se or Te, arduous. This work is aimed to investigate the significant factors of Se and/or Te recovery in the copper cementation process using the response surface methodology. The test was carried out in two series, for Te and Se, so that H2SO4, CuSO4, Te(or Se) concentration, and temperature are the factors of experimentation. According to response surface methodology (RSM) results for both test series (i. e. Se and Te), 50 g/L H2SO4, 15 g/L Cu, and 35 °C, 3000 mg/L Se (or 750 mg/L Te) was specified for higher Se recovery (97%), and the lowest Te extraction (2%) as an optimum condition, so that could make a suitable separation process. Hence, the cementation test was conducted in the simultaneous presence of Se and Te, so the separation index became 5291. Moreover, the cementation test was carried out in the pregnant leach solution of copper anode slime, and the separation factor was measured to be 606. On the other hand, the thermodynamic evaluation and XRD patterns of the process’s sediments confirm that Se is precipitated as Cu2Se and Cu1.8Se, whereas no Te components are detected in the sediments.

Microstructural characteristics and mechanical properties of Si-B alloys for functional and structural ultra-high temperature applications

Silicon boron alloys have been recognized as important materials for e.g. a direct usage in ultra-high temperature latent heat thermal energy storage systems or as a batch materials for processing boron enhanced silicide-based composites. In this work, we put new experimentally driven insights on a structure of selected Si-B binary alloys. For this reason, four Si-xB alloys (x = 2.5; 8, 13.5; 86 (at%)) were fabricated from pure elements by using a crucible-less electric arc melting technique. Nominal compositions of the alloys were selected in accordance to Si-B phase diagram as hypoeutectic, eutectic, hypereutectic and corresponding to the stoichiometric composition of SiB6 intermetallic phase, respectively. The fabricated Si-xB alloys were subjected to a detailed structural characterization. Additionally, a hardness, elastic moduli and fracture toughness of each phase constituent were examined through a micro-indentation technique. A co-existence of various silicon borides, namely SiB4, SiB6 and SiBn, has been experimentally documented. Obtained results allows receiving a description of each alloy in terms of microstructure, crystal structure and mechanical properties of involved phases. It was found that mechanical properties (both microhardness and Young modulus) increases with raising boron content in recognized Si-B phases. The fracture toughness of silicon borides assessed through indentation experiments was found to be in the rage of 2.13–3.29 MPa·m1/2.

Coupling physics in machine learning to investigate the solution behavior of binary Mg alloys

The solution behavior of a second element in the primary phase (α(Mg)) is important in the design of high-performance alloys. In this work, three sets of features have been collected: a) interaction features of solutes and Mg obtained from first-principles calculation, b) intrinsic physical properties of the pure elements and c) structural features. Based on the maximum solid solubility values, the solution behavior of elements in α(Mg) are classified into four types, e.g., miscible, soluble, sparingly-soluble and slightly-soluble. The machine learning approach, including random forest and decision tree algorithm methods, is performed and it has been found that four features, e.g., formation energy, electronegativity, non-bonded atomic radius, and work function, can together determine the classification of the solution behavior of an element in α(Mg). The mathematical correlations, as well as the physical relationships among the selected features have been analyzed. This model can also be applied to other systems following minor modifications of the defined features, if required.

Research on joint inversion of volcanic shortwave infrared emissivity and temperature based on day and night images

ABSTRACT In order to solve the problem of inaccurate emissivity obtained by empirical or experimental measurements in traditional volcanic inversion methods, which leads to the discrepancy between the temperature inversion results and the actual temperature, this paper constructs a joint inversion model of volcanic temperature and emissivity, and solves the volcanic temperature and emissivity simultaneously from the image element scale.In order to obtain the two unknown parameters of volcanic temperature and emissivity simultaneously, the study image element is assumed to be a pure image element and Lambertian body, and based on the blackbody radiation law and energy conservation law, the volcanic radiation energy transfer equation under different irradiance conditions is established and solved jointly. In this paper, the study area is Halemaʻumaʻu crater in Hawaii, and the short-wave infrared band of Landsat 8 satellite day and night remote sensing images with an imaging interval of 36 hours are used as the study data, and the temperature and emissivity are calculated using the golden mean and parabolic interpolation method with the same emissivity of the same image element in both scenes and the temperature approximation as the constraints. The results are as follows: the temperature inversion of the study area has a banding phenomenon, the temperature of the lava lake is 800–1050 K and the emissivity is 0.5–0.7; the temperature of the crater surface outside the lava lake is 500–800 K and the emissivity is 0.7–1.0. The inversion results are consistent with the actual situation. The results show that the method can realize the simultaneous inversion of volcanic temperature and emissivity parameters on the image element scale, which provides a new method for the inversion of volcanic temperature and emissivity.

Revisit the VEC criterion in high entropy alloys (HEAs) with high-throughput ab initio calculations: A case study with Al-Co-Cr-Fe-Ni system

Valence electron concentration (VEC) was treated as a useful parameter to predict the stability of solid solution phases. However, the available experimental data to support this criterion is far from enough. In the current study, the high-throughput ab initio modeling is applied to investigate the relative stability of FCC and BCC single crystals of the Al-Co-Cr-Fe-Ni high entropy alloys (HEAs) by using the special quasi-random structure (SQS) approach. The predictions start with pure elements of the Al-Co-Cr-Fe-Ni system and are continued with binaries, ternaries, and quaternary compositions, which come up with 180 compositions (360 structures). After that, the reliability of the VEC criterion is testified. The results show that the VEC criterion not only works for the stable structure but also works effectively for metastable structure when both FCC and BCC are not thermodynamic stable. However, it is found that the old VEC criterion proposed by Guo et al. fails to work effectively for compositions containing high concentrations of light-weight metals such as Al at VEC< 5. To solve this problem, the present work proposed a new VEC rule to define the stability of FCC and BCC structures at the ground state. With the implementation of the new VEC rule, the effectiveness of the VEC rule (EVEC) of both FCC and BCC structures is enhanced, especially for pure elements and binary compositions, indicating that this rule does not only work effectively for multicomponent systems but also works for low-order systems. • The Effectiveness of empirical VEC rule in the Al-Co-Cr-Fe-Ni system was systematically discussed. • The HT-ab initio calculations were performed to investigate the relative stability of FCC and BCC structure in the Al-Co-Cr-Fe-Ni system. • 180 compositions (360 structures) were investigated based on the Special Quasi-random Structures (SQS) method. • A new VEC criterion was proposed based on the results of the HT-calculations.

Chapman–Enskog derivation of multicomponent Navier–Stokes equations

There are several reasons to extend the presentation of Navier–Stokes equations to multicomponent systems. Many technological applications are based on physical phenomena that are present in neither pure elements nor in binary mixtures. Whereas Fourier's law must already be generalized in binaries, it is only with more than two components that Fick's law breaks down in its simple form. The emergence of dissipative phenomena also affects the inertial confinement fusion configurations, designed as prototypes for the future fusion nuclear plants hopefully replacing the fission ones. This important topic can be described in much simpler terms than it is in many textbooks since the publication of the formalism put forward recently by Snider [Phys. Rev. E 82, 051201 (2010)]. In a very natural way, it replaces the linearly dependent atomic fractions by the independent set of partial densities. Then, the Chapman–Enskog procedure is hardly more complicated for multicomponent mixtures than for pure elements. Moreover, the recent proposal of a convergent kinetic equation by Baalrud and Daligault [Phys. Plasmas 26, 082106 (2019)] demonstrates that the Boltzmann equation with the potential of mean force is a far better choice in situations close to equilibrium, as described by the Navier–Stokes equations, than Landau or Lenard–Balescu equations. In our comprehensive presentation, we emphasize the physical arguments behind Chapman–Enskog derivation and keep the mathematics as simple as possible. This excludes, as a technical non-essential aspect, the solution of the linearized Boltzmann equation through an expansion in Hermite polynomials. We discuss the link with the second principle of thermodynamics of entropy increase, and what can be learned from this exposition.

Impact-based forecasting for improving the capacity of typhoon-related disaster risk reduction in typhoon committee region

The two most common types of disasters caused by natural hazards in the Asia-Pacific region are floods and storms, many of them associated with typhoon (tropical cyclone) related impacts. To improve the capacity of typhoon-related disaster risk reduction so as to maximum reduce the losses of people’s life and properties, the decision makers and the public are imminently demanding the information of the targeted impact caused by typhoon. As the front line in hydro-meteorological disaster prevention and mitigation against the typhoon-related disasters, National Meteorological and Hydrological Services (NMHSs) in TC Members have recognized that forecasting impact became more important than forecasting pure causing-disaster elements. Impact-based forecasting signals an evolution from “what the weather will be” to “what the weather will do”. Many things change as impact based forecasts evolve from previous weather forecasts. To enhance impact-based typhoon forecasting, the Typhoon Committee added it into the new updated Strategic Plan 2022–2026. This paper briefed generally the concept of impact based forecasting, introduced the implementation and progresses on typhoon impact based forecasting in TC Members in recent years, and initially discussed the measures and direction for enhancement of impact-based typhoon forecasting and early warning services in future.

Effect of mechanical alloying of Ti and B in pre alloyed gas atomized powder on carbide dispersed austenitic matrix of Iron based hardfacing alloy

In fast breeder reactors Austenitic Stainless steel structural components like grid plates, sleeves, etc. are in contact under stress in a flowing liquid sodium environment at temperatures up to 823 K. To tackle self-welding characteristics, hardfacing alloys are required. In the present work, Thermocalc software was used to arrive at suitable composition of alloy consisting of Fe-20Cr-2C-18Ni-2Mn-4Si-2Ti-1B. This proposed alloy was atomized in argon atmosphere. Due to loss of Ti and B in atomization, additional alloying in the form of pure elements and ferro alloys were made by mechanical alloying in attritor ball milling setup with BPR of 10:1 (by wt.) in ultra-high purity (UHP) argon atmosphere. Mechanical alloyed powder exhibits sphericity of 0.908, apparent density of 4.3 g/cc and flow rate of 17 s per 50 g of powder. Laser cladding of 1-3 mm thick overlay layer was made on 10 mm thick SS 316 plate and its characterization was made by optical microscopy, SEM, XRD and micro-hardness. Weld overlay showed moderate distribution of complex carbides in the austenitic matrix and resultant improved hardness in the range of 445–474 HV by mechanical alloying as compared to prealloyed atomized powder.

Selective Chemical Substitution of Cu in the Structure of TiAl3 Type InPd3: Experimental and Theoretical Studies

AbstractInPd3‐xCux (x=0–1) were prepared by high temperature synthesis starting from the highly pure constituent elements. The crystal structures were determined by X‐ray diffraction. In the structure of InPd3‐xCux (x=0–1), Cu stabilizes the TiAl3‐type InPd3 and selectively substitutes one of the two Pd positions and at the limiting composition ordered InPd2Cu is formed where Cu completely occupies that position. The intriguing selective substitution was investigated by first‐principles total energy calculations followed by electronic structure and chemical bonding analysis.

Highly selective adsorption of rare earth elements by honeycomb-shaped covalent organic frameworks synthesized in deep eutectic solvents

One of the key factors to obtain a highly pure individual rare earth element (REE) is to prepare adsorbents with high selectivity and adsorption capacity. Covalent organic frameworks (COFs), which encompass a variety of properties, including regular/tunable pore size, high specific surface area and easy functionalization, could be effective as adsorbents for separating rare earth elements (REEs). In this paper, TpPa COFs were successfully synthesized using an eco-friendly deep eutectic solvent (DES) as the reaction medium instead of toxic organic solvents at room temperature. TpPa COFs have a good separation effect on the nine REEs investigated in this work. Among them, the separation factors (β) of Eu/Yb, Eu/Tm and Eu/La are 15.34, 14.70 and 10.78, respectively, indicating that the TpPa COFs have good separation performance. Further discoveries showed that the adsorption and separation mechanism of the TpPa COFs for REEs in this experiment may be due to the coordination of REE ions with O to form a stable structure. This study blazed a trial for a green and facile synthesis strategy of TpPa COFs and expanded its implementation as a solid adsorbent in the separation of REEs.

Anisotropic Thermal Expansion and Electronic Structure of LiInSe2.

Optical quality cm-sized LiInSe2 crystals were grown using the Bridgman–Stockbarger method, starting from pure element reagents, under the conditions of a low temperature gradient of 5–6 degrees/cm and a slight melt overheating. The phase purity of the grown crystal was verified by the powder XRD analysis. The thermophysical characteristics of LiInSe2 were determined by the XRD measurements in the temperature range of 303–703 K and strong anisotropy of the thermal expansion coefficients was established. The following values of thermal expansion coefficients were determined in LiInSe2: αa = 8.1 (1), αb = 16.1 (2) and αc = 5.64 (6) MK−1. The electronic structure of LiInSe2 was measured by X-ray photoelectron spectroscopy. The band structure of LiInSe2 was calculated by ab initio methods.