Full Absorption Research Articles

EFFECTS OF FLOW STATES ON ELITE ATHLETES IN TEAM SPORTS: A SYSTEMATIC REVIEW

The flow state has materialized as a condition of possibility for the search for the best performance in sports, both individual and collective. The objective of this systematic review of studies was to identify which form the “state of flow” influenced the sports performance of team sports athletes. Up from references to selected databases (for example, Web of Science Core Collection; SPORTDiscus (EBSCO-Host); PsycINFO and Pubmed), the results showed that 1946 articles were obtained, with the exclusion of duplicate studies (n = 407). Among the 46 articles that emerged from the analysis, the data excluded 37 studies, and considering an amount of 9 articles which were included in the final section of the systematic review and carried out in the period from 2015 to 2020. As a result, the flow state enhances a full absorption involvement of team-sport athletes. Emotional states tend to be part of an athlete's success. Knowing the three essential fields that comprise this scope (flow-mindfulness-performance) allows us to raise questions for the future, inherent to the effects of performance and the magnitude of the athlete's response depending on their individual characteristics, action possibilities, task constraints, and how much this influences their state of flow at the individual and collective levels.

An Excel fitting routine for correcting protein absorption spectra for scatter

Protein concentrations are often determined in a non-destructive manner by measuring the absorbance at 280 nm. However, light scattering in protein samples can complicate such assessment. We here describe a simple Excel Solver-based fitting routine to correct full protein UV absorption spectra for both Rayleigh and Mie scattering. Using samples displaying various degrees of natural and artificially induced scattering, we show that our multi-wavelength fitting method is not only capable of aiding in the determination of protein concentrations but can also be employed in the spectral analysis of protein structural changes that are accompanied by alterations in scatter intensity.

Absorption of Microwaves During Plasma Heating at the Second Harmonic of Electron Cyclotron Resonance in Tokamaks and Stellarators: Linear Theory and Experiment

We study the microwave absorption during electron cyclotron resonance heating (ECRH) by the extraordinary wave at second harmonic (X2 mode) in the T-10 tokamak and TJ-II stellarator in a wide range of plasma densities, and compare experiments with the classical formulas for the absorption of the injected ECR power. Empirical relations for the absorption efficiency and for the critical plasma density {{n}_{{{text{cr}}}}}, which separates the regions with full and partial absorption of the injected ECR power, are obtained using the numerical simulation of the heat transport with the transport model of canonical profiles. It is shown that in both devices, the range of densities exists, where the absorption predicted by the classical formulas is almost full, while according with the empirical formula, only a small fraction of the power is absorbed. The obtained relations allow ones to optimize the conditions of ECRH in toroidal systems for magnetic plasma confinement.

Non-Hermitian control between absorption and transparency in perfect zero-reflection magnonics

Recent works in metamaterials and transformation optics have demonstrated exotic properties in a number of open systems, including perfect absorption/transmission, electromagnetically induced transparency, cloaking or invisibility, etc. Meanwhile, non-Hermitian physics framework has been developed to describe the properties of open systems, however, most works related to this focus on the eigenstate properties with less attention paid to the reflection characteristics in complex frequency plane, despite the usefulness of zero-reflection (ZR) for applications. Here we demonstrate that the indirectly coupled two-magnon system not only exhibits non-Hermitian eigenmode hybridization, but also ZR states in complex frequency plane. The observed perfect-ZR (PZR) state, i.e., ZR with pure real frequency, is manifested as infinitely narrow reflection dips (~67 dB) with infinite group delay discontinuity. This reflection singularity of PZR distinguishes from the resonant eigenstates but can be adjusted on or off resonance with the eigenstates. Accordingly, the absorption and transmission can be flexibly tuned from nearly full absorption (NFA) to nearly full transmission (NFT) regions.

Ti3+ self-doped TiO2 anchored with iron oxide quantum dots as an efficient persulfate catalyst for the enhanced removal of typical phenolic pollutants from water under visible light

In this work, a facile impregnation–calcination route was proposed for the synthesis of Ti3+ self−doped TiO2 anchored with iron oxide quantum dots (FeQDs/TiO2−x) as an efficient visible light−derived persulfate catalyst for organic degradation. After the successful co−doping of Fe3+ and Ti3+, the obtained FeQDs/TiO2−x exhibited quasi−full visible light absorption, with the maximum absorption edge broadened to 791 nm; furthermore, its charge separation and interfacial transport capacity were significantly enhanced, as evidenced by the fact that the lifetime of the photogenerated electrons was prolonged from 6.17 to 10.34 ns. In addition, the surface Fe3+ species on FeQDs/TiO2−x can be effectively reduced to Fe2+ by the separated electrons, establishing an efficient cycle between Fe3+ and Fe2+. Therefore, the obtained FeQDs/TiO2−x nanocomposite exhibited enhanced catalytic performance for the degradation of phenolic pollutants via PS activation under visible light. Specifically, 50 mg/L bisphenol A (BPA) and acetaminophen (AAP) can be completely degraded by FeQDs/TiO2−x with faster reaction rate constants and higher mineralization rates compared to its counterparts, including TiO2, TiO2−x, and FeQDs/TiO2. Based on the results of material characterization, degradation experiments, identification of reactive oxidizing species, and chemical quenching experiments, the mechanism of the enhanced photocatalytic activity of FeQDs/TiO2−x was elucidated. Our results demonstrated the high potential of FeQDs/TiO2−x for wastewater treatment.

Simultaneous optimization of conduction and polarization losses in CNT@NiCo compounds for superior electromagnetic wave absorption

Polarization and conduction losses are the two most crucial dielectric loss mechanisms for carbon-based composites, but their synergistic effects in different frequency bands need to be further revealed. More importantly, for polarization and conduction losses, the strengthening of one party always comes at the expense of the other, which inevitably limits the overall performance of the absorbers. Herein, we have developed a composite of CNT and NiCo hybrid particles via a scalable wet chemical process and annealing method. Through the adjustment of the precursor and the annealing temperature, the conduction and polarization losses of the composite are optimized simultaneously. The optimized samples achieved the full absorption of the X and Ku bands under conditions of low filling rate and thin thickness. Further theoretical and experimental studies have revealed conduction loss and polarization loss laws at different frequency ranges. The synergistic effect of conductive loss and magnetic loss in the low-frequency region ensures that the sample exhibits high microwave dissipation performance. However, in the medium and high-frequency part, the magnetic loss can be almost ignored and the timely replenishment of polarization loss keeps the wave-absorbing performance at a high level. The excellent multi-band absorption characteristics make the as-obtained absorbers meet the needs of future applications.

One step synthesis of novel CuS-ZnS/SiO2@n-octadecane nanocapsules with full spectral absorption range and high photothermal conversion efficiency

In this manuscript, CuS-ZnS/SiO2@n-octadecane nanocapsules were prepared by a simple one-step Cu2+ and Zn2+ co-deposition method. The results of XRD, SEM, TEM, FTIR and XPS show that nanocapsules composed of CuS-ZnS/SiO2 shell and n-octadecane core material were successfully prepared, and the particles deposited was proved to be composite structure of CuS-ZnS. The solution concentration, reaction temperature and pH value have significant effects on the morphology of the nanocapsules prepared. The appropriate conditions are 0.02 mol/L CuSO4, 0.02 mol/L Zn(CH3COO)2, 60 °C, and no additional pH adjustment. Under the optimum conditions, the melting enthalpy reached 45.11 J/g, and after 100 times of cold and hot cycles, the melting enthalpy of the sample only decreased by 3.2%, showing good thermal stability. The CuS-ZnS composite structure makes CuS-ZnS/SiO2 nanocapsules exhibit a wider spectrum absorption performance. The absorption effect of CuS-ZnS/SiO2 nanocapsules to ultraviolet light is significant, compared to the slight reducing of the visible light, while the absorption of near-infrared light is strong. The photothermal conversion efficiency of the samples is significantly improved from 9.7% to 86.6%. Hence, the prepared nanocapsules achieve full spectral absorption, which has a broad application prospect in solar thermal utilization.

Low-cost photoreactors for highly photon/energy-efficient solar-driven synthesis

Low-cost photoreactors for highly photon/energy-efficient solar-driven synthesis

Constructing Core-Shell NiCo2O4@PPy nanocomposites with controllable dielectric properties toward wide-band microwave absorption

Nickel cobaltate@polypyrrole composite nanomicrospheres (NiCo2O4@PPy) were successfully synthesized by in situ oxidation polymerization on the surface of NiCo2O4 microspheres with polypyrrole layer as a shell. The impedance matching can be optimized by modulating the amount of polypyrrole, so as to obtain the best wave absorption performance. Furthermore, the full absorption of multiple bands can be realized under different thickness. The absorption mechanism of EMW is specifically analyzed, that is, the appropriate impedance matching and the large dielectric and magnetic losses caused by the electromagnetic synergistic effect generated by the heterogeneous interface of NiCo2O4 and PPy. NiCo2O4@PPy-0.8 achieves remarkable impedance matching in a wide frequency range compared with other samples, thus obtaining superior absorption performance. When the thickness of NiCo2O4@PPy-0.8 is 2.3 mm, the effective absorption bandwidth (EAB, RL exceeding −10 dB) at 10 wt% loading reaches 7.14 GHz (ranging from 10.86 GHz to 18 GHz, covering the whole Ku band), and the minimum reflection loss (RLmin) is −57.85 dB. This work provides an encouraging method for lightweight ultra-wideband electromagnetic wave absorption of multilayer structures based on nickel-cobalate matrix.

Boosting radical innovativeness through start‐up acquisitions: the role of decision autonomy and structural integration

Since start‐ups often own cutting‐edge technology and knowledge, acquiring a start‐up can provide buyers with a unique opportunity to boost their radical innovativeness. As a result, start‐up acquisitions have increasingly gained importance. Acquirers, however, face difficult decisions on target autonomy and integration, which often constitute a dilemma. We analyzed survey data from 118 M&A and integration managers in charge of corporate start‐up acquisitions. Our results show that a start‐up's decision‐making autonomy supports acquirer's radical innovativeness. The structural integration of the target reinforces the positive effect of decision autonomy. Our work with the focus on post‐merger integration and the start‐up context contributes to M&A literature in several ways. We uncover a hybrid integration approach, showing that a combination of high target decision autonomy and the full absorption (i.e., structural integration) of the start‐up by the acquiring organization is most beneficial for acquirer's radical innovativeness.

Measurement of the Acoustic Relaxation Absorption Spectrum of CO2 Using a Distributed Bragg Reflector Fiber Laser

Reconstruction of the acoustic relaxation absorption curve is a powerful approach to ultrasonic gas sensing, but it requires knowledge of a series of ultrasonic absorptions at various frequencies around the effective relaxation frequency. An ultrasonic transducer is the most widely deployed sensor for ultrasonic wave propagation measurement and works only at a fixed frequency or in a specific environment like water, so a large number of ultrasonic transducers operating at various frequencies are required to recover an acoustic absorption curve with a relative large bandwidth, which cannot suit large-scale practical applications. This paper proposes a wideband ultrasonic sensor using a distributed Bragg reflector (DBR) fiber laser for gas concentration detection through acoustic relaxation absorption curve reconstruction. With a relative wide and flat frequency response, the DBR fiber laser sensor measures and restores a full acoustic relaxation absorption spectrum of CO2 using a decompression gas chamber between 0.1 and 1 atm to accommodate the main molecular relaxation processes, and interrogates with a non-equilibrium Mach-Zehnder interferometer (NE-MZI) to gain a sound pressure sensitivity of −45.4 dB. The measurement error of the acoustic relaxation absorption spectrum is less than 1.32%.

Triple band terahertz metamaterial absorber within (0.4-0.46thz) frequency range

An ultrathin Terahertz Triple-band ideal meta material absorber with a brand-new design that is straightforward has been presented. The suggested terahertz meta material absorber has a unit cell that is made up of two D-shaped resonators with slots and a ground metallic plane. These elements are separated from one another by a polyimide dielectric substrate that has a thickness of 500 micrometers. The absorber construction that has been presented provides three distinct absorption peaks within the narrow frequency range of (0.4-0.46 THz) without producing any interference. In order to get a deeper comprehension of the mechanism behind the absorption process, an investigation into the electric field, the magnetic field, the surface current distribution, and the independence of the polarization angle has been carried out. It is anticipated that the configuration of the terahertz absorber that has been described would find use in applications relating to the lowering of radar cross-section, detection, imaging, and sensing. One of the contributions of this study is the description of a downsized and compact triple-band terahertz meta material absorber. In order to generate the unit cell of a terahertz absorber, an identical I-typed resonator, which is represented by a rectangular patch with two very small notches, is first deposited on top of a dielectric sheet and then a metallic mirror. The terahertz regime reveals three distinct frequency spots, and the design of the very small structure allows for virtually full absorption of all of them.

Synthesis of novel Sn1-xFexS nanocomposites with narrow band gap energy for absorption of full broad spectrum

SnS is a low cost photocatalyst for solar energy conversion due to its narrow bandgap energy. However, the fast recombination of the electron-hole pair reduces its reactivity under light radiation. In this novel research, a series of Sn1-xFexS heterostructures containing various proportions of Fe2+ ions are synthesized by a facile hydrothermal route using SnCl2 as a low cost and non-toxic precursor. The as-synthesized samples are well characterized using XRD, DRS, HRTEM, XPS and PL analysis. Fe2+ ions alter the optical properties, and the band gap energy of SnS is influenced by the concentration of Fe in each nanocomposite. It is obvious to notice that the increase in the concentration of Fe in the nanocomposites is accompanied by an increase in the recombination rate of the charge carriers, which reduces the photocatalytic efficiency of Sn1-xFexS compared with pristine SnS. The decomposition of rhodamine B dye under a UV mercury lamp is carried out to compare the efficiency of the as-synthesized samples and to explore a clear relationship between optical properties and the photodegradation efficiency. The removal of RhB dye is carried out through a tandem adsorption-photocatalytic process on the surface of pristine SnS nanoparticles. Nevertheless, the removal of RhB dye on the nanocomposite surface is performed through a predominant photocatalytic process, indicating that Fe2+ ions are strongly adsorbed on the active sites of SnS hindering the adsorption process. The exceptional photocatalytic efficiency results from the strong absorbability of SnS to a full absorption spectrum due to its narrow band gap energy.

Rational design of high-performance soluble intrinsic black polyimide with full absorption of visible light

With the rapid development of photoelectric devices, the demand for black polyimide (BPI) with excellent masking ability is growing, but existing BPI doped with black substrates has serious insulation and mechanical performance deficiencies. To solve the problem, the intrinsic BPI with excellent comprehensive performance is highly desirable. In this work, tetraphenylcyclopentadienone (TPCP) was chosen as a chromophore, a novel diamine (TPCPtPPDA) containing TPCP grafted with biphenyl groups was synthesized, and TPCPtPPDA was then polymerized with 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) to obtain a black polyimide (TPCPtPPPI). The TPCPtPPPI showed full absorption of visible light with cutoff wavelength (λcut) high to 713 nm and Commission International Eclairage (CIE) lab color parameter L* of 0.82. By calculating the frontier molecular orbitals and the nature of electron transitions, the excellent light absorption property was attributed to the electron transition from HOMO to LUMO occurring in the diamine moieties, with the charge transfer mainly from the terphenyl moieties in 2 and 5 positions to the central cyclopentadienone core. Meanwhile, TPCPtPPPI also had excellent thermal, electrical and mechanical performances and solubility by introduction of rigid non-planar propeller-shaped structure. This work provides a promising strategy for constructing high-performance soluble intrinsic BPI and related polymers with full absorption of visible light.

Light-Driven Fuel Cell with a 2D/3D Hierarchical CuS@MnS Z-Scheme Catalyst for H2O2 Generation

A photoelectrocatalytic (PEC) oxygen reduction reaction (ORR) strategy with fuel-efficient and cost-effective catalysts for on-demand hydrogen peroxide (H2O2) production is booming as an attractive alternative to the conventional anthraquinone process. Herein, we constructed a novel two-dimensional (2D)/three-dimensional (3D) hierarchical CuS@MnS p-p Z-scheme catalyst with full spectrum absorption and strong coupling interface by regulating the crystal structure, morphology, and photocharge transfer mechanism, which was used as a photocathode for PEC synthesis of H2O2 with a yield of 1.65 mM within 180 min. Taking advantage of a coupling strategy with Sn3O4/Ni foam, the as-prepared two-compartment cell with water oxidation reaction and ORR exhibited boosted activity and stability for the dual production of H2O2. An energy-saving H2O2 generation system was also constructed with a direct hydrazine/O2 fuel cell, realizing the significant advantage in reducing electricity consumption during the H2O2 synthesis. Moreover, the onsite generation of H2O2 remarkably accelerated the degradation of pollutants via a cascade heterogeneous Fenton reaction with a Fe anode. This work provides a new strategy for designing a multifunctional PEC system for the production of high-value chemicals, energy recovery, and pollutant degradation.

Static Metasurface Reflectors With Independent Magnitude and Phase Control Using Coupled Resonator Configuration

A static metasurface reflector based on a novel coupled resonator configuration is proposed to independently control the reflection phase and magnitude of linearly polarized incident fields and is demonstrated experimentally in the millimeter-wave Ka-band around 30 GHz. The proposed concept is illustrated using a unit cell design consisting of a rectangular ring coupled with a rectangular slot resonator backed by a grounded dielectric slab. By geometrically tuning various dimensions of the two resonators, a near-perfect amplitude–phase coverage is achieved at a fixed design frequency of 30 GHz. To demonstrate the flexible beam-forming capability of the proposed metasurface reflectors, illustrative examples of fixed beam steering with varying reflection magnitudes and asymmetric dual-beam patterns with specified reflection magnitude, reflection angles, and beamwidths are successfully shown. Compared to the standard method based on polarization rotation and resistive loadings with discrete values, the proposed technique does not generate undesired cross-polarization field reflection and provides continuous magnitude tuning including full absorption, along with wide phase coverage.

Formula omitted] spectrometer of [formula omitted]-decay electrons with Si(Li)-detectors

We present a description of the originally developed β-spectrometer consisting of two Si(Li)-detectors with sensitive area thickness above 8 mm and 4π-geometry. The full absorption spectrometer allows for direct measurements of β-spectra, disregarding the corrections to response function induced by the electron backscattering from the crystal surface. In case of β-spectra of transitions to the excited state of the daughter isotope additional 3″ BGO-detector is used in order to detect the γ-quanta in coincidence with the pair of Si(Li)-spectrometers.

Hierarchical structures of carbon nanotubes anchored on core-sheath microrads toward electromagnetic wave absorption and shielding with Joule heating and superhydrophobic capacities

Hierarchical structures with synergistic dielectric-magnetic compositions are highly desired for electromagnetic wave absorption and interference shielding applications. Fabricating lightweight and high-performance electromagnetic protection composites with additional functions are demanded to suppress severe electromagnetic radiation and interference pollution. Herein, a unique three-dimensional hierarchical structure consisting of 1D multi-walled carbon nanotubes anchored on 1D MXene@CF core-sheath microrods are rationally proposed via electrostatic self-assembly and hydrothermal strategy as well as subsequent thermal-catalysis treatment. The multi-walled carbon nanotubes encapsulated with magnetic CoNi nanoparticles are immobilized onto core-sheath microrods matrix, constructing effective 1D/1D electron migration bridges and the uniformly dispersed magnetic component to facilitate magnetic coupling effect. Consequently, profiting from the optimized impedance matching, enhanced conduction loss, dielectric polarization, and magnetic loss, the as-prepared sample shows an outstanding absorption capacity with reflection loss value of −56.8 dB and X-band full absorption. When used as electromagnetic shielding materials, the composites exhibit exceptional electromagnetic interference shielding properties. In addition, the upgraded mechanical strength, remarkable voltage-driven Joule heating and superhydrophobic properties endow the absorbers with multi-scenario adaptability and long life-time applications. This work provides well-designed hierarchical structures for high-performance electromagnetic absorbing and shielding with the great prospect of multifunctional applications.

Synthesis of nitrogen-doped carbon dots with 3-aminoquinoline and citric acid as an absorbent in full ultraviolet bands and application of transparent sunscreen umbrella

In recent years, as the global climate continues to deteriorate, the harm of ultraviolet(UV) radiation to the human body is increasing, but the development of commercial UV-blocking products has not followed the corresponding update. Carbon dots (CDs) are excellent candidates for UV absorbers because of their multi-functional groups, high stability, and low toxicity. In this study, full UV bond absorbing CDs (3A-CDs) were synthesized by a one-step hydrothermal method using anhydrous Citric acid(CA) and 3-aminoquinoline as raw materials. The 3A-CDs have super high UV absorption efficiency, light-aging resistance, and acid and alkaline resistance. Subsequently, different concentrations of 3A-CDs were doped into PVA to prepare 3A-CDs@PVA films with excellent full UV bond absorption and good mechanical properties. Finally, 3A-CDs@PVA films were sandwiched between two pieces of transparent umbrella cloth. The 0.3 wt% 3A-CDs@PVA film with transparent umbrella cloth can achieve a blocking efficiency of more than 97.2% in the full UV bands. Also, SPF is greater than 50, PFA is PA++++, and the visible light transmittance is as high as 93.8%. This study provides a new application and prospect for the development of CDs and their composite products into new, efficient, and durable UV-blocking products.

Synthesis, microstructure and electromagnetic properties of Hf-based SiBCN ceramics

In this work, two kinds of ceramic polymers, polyborosilazane and polyhafnoxane, were mixed by a precursor blending method, followed by curing and pyrolysis to obtain Hf-based SiBCN ceramics. Through FTIR and NMR characterization of cured product, it can be found that the two precursors underwent cross-linking reaction during the curing process, resulting in the increase of crystallization temperature of HfO2 and β-SiC, and the formation of new components (HfB2 and HfN) during pyrolysis. When the pyrolysis temperature increases, the average values of the real part and imaginary part of the dielectric constant of Hf-based SiBCN ceramics increased from 7.2 to 4.9 to 9.0 and 6.6, respectively, resulting from the precipitation of HfB2 and HfC(N) with high dielectric constants. The effective absorption width decreased from 3.4 to 2.5 GHz, and the minimum value of reflection coefficient increased from −14.9 to −12.2 dB, which is caused by poor impedance matching. After being oxidized at 500 °C for 50 h in air, the free carbon basically disappears, and the full X-band absorption can be realized for the Hf-based SiBCN ceramic pyrolyzed at 1500 °C with a thickness of 2.8 mm.