Low-energy Photons Research Articles

Investigation and structural of phosphate glasses at low photon energy through: optical and attenuation properties

This paper presents a novel low-cost phosphate glass preparation by using the melt quenching technique. It was investigated for use in diagnostic protective applications. The range of UV-VIS wavelength is used to estimate the optical energy gap. The MAC denotes the mass attenuation coefficients of the present glass were computed at low photon energies between 15 and 200 KeV using the MIKE program. The manufactured glasses parameters viz; the mean free path, half value layer, tenth value layer, effective atomic number, effective electron density, and linear attenuation coefficient denotes as follows; 𝑀𝑀𝑀𝑀𝑀𝑀, 𝐻𝐻𝐻𝐻𝐻𝐻, 𝑇𝑇𝑇𝑇𝑇𝑇, 𝑍𝑍𝑒𝑒𝑒𝑒𝑒𝑒, 𝑁𝑁𝑒𝑒𝑒𝑒𝑒𝑒, 𝑎𝑎𝑎𝑎𝑎𝑎 𝐿𝐿𝐿𝐿𝐿𝐿 were determined. Furthermore, the molar volume, oxygen molar volume, and optical packing density of fabricated glass were assessed. The third-order susceptibility (χ(3) and non-linear refractive index of the present glass were determined. From previous results, it can be concluded that the glass has unique attenuation characteristics, therefore, can be used for radiation protection at low energy 15 to 200 KeV.

Design and fabrication of a sandwich detector for material discrimination and contrast cancellation in dual-energy based x-ray imaging

Dual-energy imaging represents a versatile and evolving technology with wide-ranging applications in medicine and beyond. Recent technological developments increased the potential for improved diagnostic accuracy and expanded imaging capabilities across various fields. The purpose of this work is to design and develop an energy-integrating multilayer detector, known as a sandwich detector, aimed at single-shot dual-energy imaging tasks such as material discrimination and contrast cancellation. The sandwich detector uses two complementary metal oxide semiconductor advanced pixel sensors of 50 μm pixel size. The top and bottom sensors detect low-energy (LE) and high-energy (HE) photons, with sensors coupled with 250 and 600 μm scintillators, respectively. For better spectral separation between layers without excessively affecting the detected statistic in the bottom layer, the insertion of a 0.25-mm Cu filter between the layers was found to be the optimal choice, from among the tested 0-, 0.25-, and 0.5-mm filter options. The thickness selection for scintillator and intermediate Cu filter was carried out through a dual-energy simulation model. The experiments confirmed the model's reliability in selecting the optimal thicknesses of the intermediate Cu filter, thereby providing reassurance also on the choice of the top scintillator.

Extrapolation of Monte Carlo–Derived Noble Gas Air-Submersion Effective Dose Rate Coefficients for Selected Occupational Settings to Other Geometries and Radionuclides

External exposures to airborne radioactivity at nuclear power sites are typically based on semi-infinite clouds with uniform concentrations and corresponding effective dose rate coefficients (EDRCs), along with the simplifying assumption that the radioactive clouds extend to infinity around the receptor of interest. The two regulatory models that are typically employed for finite-cloud adjustments to submersion doses, namely, Regulatory Guide 1.183 for hemispherical clouds and the International Commission on Radiological Protection (ICRP) document ICRP-30 for spherical clouds, were purposely oversimplified to facilitate their implementation. As a result, dose projections can be significantly underestimated under certain circumstances, particularly with radionuclides emitting low-energy photons and/or particles. In addition, these adjustments do not account for scatter radiation off surrounding walls, ceilings, and floors of typical occupational settings. In recognition of these limitations and for the mitigation thereof, Veinot et al. published an article [Rad. and Environ. Biophy., Vol. 56, p. 453 (2017)] that provided monoenergetic photon, electron, and positron EDRCs based on elaborate Monte Carlo computations for submersion in three typical occupational settings at nuclear facilities (namely, an office, a laboratory, and a warehouse). Included in the article were also EDRCs for exposure to 45 noble gases airborne within the said occupational settings. However, extrapolation of the results to other settings was limited due to geometry variations. Even so, as described in the present paper, the Veinot et al. article provided the basis for the definition of a straightforward model for extrapolation of the Monte Carlo–derived EDRCs to other occupational settings and radionuclides. The objective of the EDRC extrapolation model in this paper is to provide a simple but comprehensive approach to licensing-basis submersion dose calculations consistent with the recommendations in ICRP Publication 103. The model is reasonably accurate and applicable to submersion volumes that are smaller than an office and larger than a typical warehouse, as would be needed for control room habitability evaluations. It is emphasized that the model is only suitable for the external dose computation of airborne noble gases and particulates; dose contributions via the inhalation pathway and from direct shine from contaminated surfaces need to be evaluated separately. The EDRC extrapolation model was programmed into an Excel workbook (OccuSetEDRCs-R0.xlsx) that is available to interested parties; see Supplementary Data section for further details. The model can handle all 1252 radionuclides in ICRP-107 and submersion volumes ranging between about 40 and 4000 m3, with an upper estimated error of about 10% on average for large submersion volumes.

Direct Observation of Circularly Polarized Nonlinear Optical Activities in Chiral Hybrid Lead Halides.

Circularly polarized light emission is a crucial application in imaging, sensing, and photonics. However, utilizing low-energy photons to excite materials, as opposed to high-energy light excitation, can facilitate deep-tissue imaging and sensing applications. The challenge lies in finding materials capable of directly generating circularly polarized nonlinear optical effects. In this study, we introduce a chiral hybrid lead halide (CHLH) material system, R/S-DPEDPb3Br8·H2O (DPED = 1,2-diphenylethylenediammonium), which can directly produce circularly polarized second harmonic generation (CP-SHG) through linearly polarized infrared light excitation, exhibiting a polarization efficiency as high as 37% at room temperature. To understand the spin relaxation mechanisms behind the high polarization efficiency, we utilized two models, so-called D'yakonov-Perel' (DP) and Bir-Aronov-Pikus (BAP) mechanisms. The unique zigzag inorganic frameworks within the hybrid structure are believed to reduce the dielectric confinement and exciton binding energy, thus enhancing spin polarization, especially in regions with a high excitation pump fluence based on the DP mechanism. In the case of low excitation pump fluence, the BAP mechanism dominates, as evidenced by the observed decrease in the polarization ratio from CP-SHG measurement. Using density functional theory analysis, we elucidate how the distinctive 8-coordination environment of lead bromide building blocks effectively suppresses spin-orbit coupling at the conduction band minimum. This suppression significantly diminishes spin-splitting, thereby slowing the spin relaxation rate.

Ultracompact Lab-on-a-Chip Device for Surface-Enhanced Coherent Anti-Stokes Raman Scattering.

This paper introduces an ultracompact lab-on-a-chip device with a size of [Formula: see text] for surface-enhanced coherent anti-Stokes Raman scattering. This device comprises of a unique hybrid plasmonic-photonic vertical coupler, for light-coupling between the device and a light source, and a heptamer plasmonic nanotweezer for trapping and manipulation of nanoparticles. The coupler with its nanoscale size of [Formula: see text] offers maximum coupling efficiency and directivity of -4.2 dB and 17.8 dB with a 3 dB bandwidth across the wavelength range of [Formula: see text]. Based on a finite element method, it is theoretically shown that the tear-drop based nanotweezer can empower the device to yield a very high Raman gain of ≥ 1017 , making the detection at the single-molecule level possible. The proposed device can exhibit low damage to bioparticles through the use of near infrared wavelengths range with lower energy photons. Due to its short optical path, this device is expected to improve the Raman signal to noise ratio by reducing the level of background in-coherent Raman signals. Finally, thanks to its configuration, this device can enable the creation of parallel measurement channels, paving the way toward the development of high-throughput and mass-produced biosensors.

Hybrid spectral CT system with clinical rapid kVp-switching x-ray tube and dual-layer detector for improved iodine quantification.

Spectral computed tomography (CT) is a powerful diagnostic tool offering quantitative material decomposition results that enhance clinical imaging by providing physiologic and functional insights. Iodine, a widely used contrast agent, improves visualization in various clinical contexts. However, accurately detecting low-concentration iodine presents challenges in spectral CT systems, particularly crucial for conditions like pancreatic cancer assessment. In this study, we present preliminary results from our hybrid spectral CT instrumentation which includes clinical-grade hardware (rapid kVp-switching x-ray tube, dual-layer detector). This combination expands spectral datasets from two to four channels, wherein we hypothesize improved quantification accuracy for low-dose and low-iodine concentration cases. We modulate the system duty cycle to evaluate its impact on quantification noise and bias. We evaluate iodine quantification performance by comparing two hybrid weighting strategies alongside rapid kVp-switching. This evaluation is performed with a polyamide phantom containing seven iodine inserts ranging from 0.5 to 20 mg/mL. In comparison to alternative methodologies, the maximum separation configuration, incorporating data from both the 80 kVp, low photon energy detector layer and the 140 kVp, high photon energy detector layer produces spectral images containing low quantitative noise and bias. This study presents initial evaluations on a hybrid spectral CT system, leveraging clinical hardware to demonstrate the potential for enhanced precision and sensitivity in spectral imaging. This research holds promise for advancing spectral CT imaging performance across diverse clinical scenarios.

Tuning the physical properties of inorganic novel perovskite materials Ca3PX3 (X=I, Br and Cl): Density function theory

In photovoltaic technology, inorganic perovskite solar cells formed from halide have developed into a noteworthy prospect, primarily attributable to their exceptional efficiency, cost-effectiveness, and straightforward manufacturing techniques. Lead-free A3BX3 inorganic perovskites have generated significant attention within the environmentally friendly solar industry thanks to their extraordinary characteristics encompassing thermoelectricity, optoelectronics, and elasticity. This research focuses on the attributes of the structural, electrical, and optical inorganic halide perovskites Ca3PX3 (X = I, Br, and Cl) using the first-principles density-functional theory (FP-DFT). According to the electronic band structures, Ca3PI3, Ca3PBr3, and Ca3PCl3 show semiconductor characteristics with a straight bandgap of 1.4909 eV, 1.9502 eV, and 2.2058 eV, respectively, at the Γ(gamma)-point. Whenever one takes consideration into account the spin-orbital coupling (SOC) effect, the bandgap of the Ca3PI3, Ca3PBr3, and Ca3PCl3 perovskites is minimized to 1.2382 eV, 1.6456 eV, and 1.9056 eV. All these structures' bandgaps are compressed under compressive strain while they expand with tensile strain. The optical properties indicate that these materials have outstanding visible light consumption capabilities due to their distinct band features, comprising functions of dielectric, consumption coefficient, and function of electron collapse. Observations indicate that the dielectric constant peaks of Ca3PX3 (where X represents I, Br, or Cl) exhibit a redshift, moving towards lower photon energy levels as compressive strain increases. Conversely, they show a blueshift behavior, shifting to a greater amount of photon energy levels by applying tensile strain. Therefore, these characteristics render Ca3PX3 perovskites highly suitable for optimizing light guidance for solar power and energy retention tools.

Ternary organic bulk-heterojunction strategy enables efficient light utilization for perovskite solar cells

Extending the photoresponse into the near-infrared region (NIR) is an urgent research topic in perovskite solar cells. A ternary bulk heterojunction (BHJ) layer composited with PC61BM, D18-Cl and Y6 was deposited onto the perovskite to broaden light absorption. The ternary BHJ layer can absorb low-energy photons in the NIR region (800–920 nm) and generate excitons. Subsequently, these excitons dissociate into free electrons and holes at the donor-acceptor interface, thus extending the device's photo response up to 920 nm. Moreover, due to the good electron transport capabilities of the acceptors Y6 and PC61BM in the BHJ film, the BHJ layer also acts as the electron transport layer in the inverted PSC device. The inverted P–I–N device based on perovskite/BHJ achieved an external quantum efficiency (EQE) up to 30% in the near-infrared range. Compared to control PSCs, the short-circuit current (JSC) increased from 21.64 to 24.35 mA cm−2, resulting in a high PCE of 19.88%. Additionally, the high hydrophobic surface of the ternary layer contributes to the good long-term stability of the device. The results demonstrate that the ternary organic bulk heterojunction is an effective strategy for achieving efficient light utilization in the near-infrared region and enhancing power conversion efficiency in perovskite solar cells.

Revealing the Structural, Elastic, Electronic, and Optical Properties of K2ScCuCl6 and K2YCuCl6: An In-Depth Exploration Using Density Functional Theory.

The optoelectronic, structural, and elastic properties of K2ScCuCl6 and K2YCuCl6 double perovskite compounds were thoroughly investigated in this study using density functional theory. It is observed that both compounds exhibit exceptional structural and mechanical stability. The structural stability is assessed using Goldsmith's tolerance factor (tG), with values approaching unity indicating a reliable cubic perovskite structure. Phonon stability was ensured by the absence of negative energy formations and only real frequencies in the phonon calculations. Applying the finite displacement method also provided further evidence of the compounds' thermodynamic stability. The electronic properties analysis revealed that K2ScCuCl6 and K2YCuCl6 are narrow band gap semiconductors, with band gap values of 1.8 and 2.5 eV, respectively. This was confirmed by analyzing the density of states. Furthermore, the optical properties exhibited transparency at lower photon energies and significant absorption at higher energies. These exciting findings suggest that K2ScCuCl6 and K2YCuCl6 have promising applications in high-frequency UV devices.

Grid/lattice therapy: consideration of small field dosimetry.

Small-field dosimetry used in special procedures such as gamma knife, Cyberknife, Tomotherapy, IMRT, and VMAT has been in evolution after several radiation incidences with very significant (70%) errors due to poor understanding of the dosimetry. IAEA-TRS-483 and AAPM-TG-155 have provided comprehensive information on small-fields dosimetry in terms of code of practice and relative dosimetry. Data for various detectors and conditions have been elaborated. It turns out that with a suitable detectors dose measurement accuracy can be reasonably (±3%) achieved for 6 MV beams for fields >1×1cm2. For grid therapy, even though the treatment is performed with small fields created by either customized blocks, multileaf collimator (MLC), or specialized devices, it is multiple small fields that creates combined treatment. Hence understanding the dosimetry in collection of holes of small field is a separate challenge that needs to be addressed. It is more critical to understand the scattering conditions from multiple holes that form the treatment grid fields. Scattering changes the beam energy (softer) and hence dosimetry protocol needs to be properly examined for having suitable dosimetric parameters. In lieu of beam parameter unavailability in physical grid devices, MLC-based forward and inverse planning is an alternative path for bulky tumours. Selection of detectors in small field measurement is critical and it is more critical in mixed beams created by scattering condition. Ramification of small field concept used in grid therapy along with major consideration of scattering condition is explored. Even though this review article is focussed mainly for dosimetry for low-energy megavoltage photon beam (6 MV) but similar procedures could be adopted for high energy beams. To eliminate small field issues, lattice therapy with the help of MLC is a preferrable choice.

Precise control of hole transport layer integration on PDTS-DTTFBT: PC71BM organic solar cells

Efforts to enhance the commercial viability of organic solar cells (OSCs) prioritize high power conversion efficiency(PCE). This study proposes precision tuning of the photoactive layer thickness in the nanoscale as an innovative method to boost efficiency. Utilizing PDTS-DTTFBT: PC71BM, an organic blend, as the active layer aims to capture a broad photon range while addressing optical losses due to low-energy photons rather than mere absorption. The study integrates PEDOT: PSS and molybdenum trioxide (MoO3) as hole transport layers, alongside C60, PC60BM, and ZnO electron transport layers. Meticulous analysis of their photon absorption, reflectance, charge carrier generation, and localized energy variance emphasizes their impact on the efficiency of PDTS-DTFFBT: PC71BM active films. Notably, incorporating MoO3 as the hole transport layer significantly mitigated losses and altered localized energy, culminating in an impressive 17.69% efficiency at an optimized blend thickness of 120 nm. Augmenting blend thickness directly boosts PCE and current density until reaching optimal thickness, while diminishing fill factor, with minimal effect on open-circuit voltage. These results highlight the efficacy of this methodology in enhancing the performance of organic solar cells.

New optically stimulated luminescence dosimetry film optimized for energy dependence guided by Monte Carlo simulations

Optically stimulated luminescence (OSL) film dosimeters, based on BaFBr:Eu2+ phosphor material, have major dosimetric advantages such as dose linearity, high spatial resolution, film re-usability, and immediate film readout. However, they exhibit an energy-dependent over-response at low photon energies because they are not made of tissue-equivalent materials. In this work, the OSL energy-dependent response was optimized by lowering the phosphor grain size and seeking an optimal choice of phosphor concentration and film thickness to achieve sufficient signal sensitivity. This optimization process combines measurement-based assessments of energy response in narrow x-ray beams with various energy response calculation methods applied to different film metrics. Theoretical approaches and MC dose simulations were used for homogeneous phosphor distributions and for isolated phosphor grains of different dimensions, where the dose in the phosphor grain was calculated. In total 8 OSL films were manufactured with different BaFBr:Eu2+ median particle diameters (D50): 3.2 μm, 1.5 μm and 230 nm and different phosphor concentrations (1.6%, 5.3% and 21.3 %) and thicknesses (from 5.2 to 49 μm). Films were irradiated in narrow x-ray spectra (N60, N80, N-150 and N-300) and the signal intensity relative to the nominal dose-to-water value was normalized to Co-60. Finally, we experimentally tested the response of several films in Varian 6MV TrueBeam STx linear accelerator using the following settings: 10 × 10 cm2 field, 0deggantry angle, 90 cm SSD, 10 cm depth. The x-ray irradiation experiment reported a reduced energy response for the smallest grain size with an inverse correlation between response and grain size. The N-60 irradiation showed a 43% reduction in the energy over-response when going from 3 μm to 230 nm grain size for the 5% phosphor concentration. Energy response calculation using a homogeneous dispersion of the phosphor underestimated the experimental response and was not able to obtain the experimental correlation between grain size and energy response. Isolated grain size modeling combined with MC dose simulations allowed to establish a good agreement with experimental data, and enabled steering the production of optimized OSL-films. The clinical 6 MV beam test confirmed a reduction in energy dependence, which is visible in small-grain films where a decrease in out-of-field over-response was observed.

Study of Laser-Induced Multi-Exciton Generation and Dynamics by Multi-Photon Absorption in CdSe Quantum Dots.

Multi-exciton generation by multi-photon absorption under low-energy photons can be thought a reasonable method to reduce the risk of optical damage, especially in photoelectric quantum dot (QD) devices. The lifetime of the multi-exciton state plays a key role in the utilization of photon-induced carriers, which depends on the dynamics of the exciton generation process in materials. In this paper, the exciton generation dynamics of the photon absorption under low-frequency light in CdSe QDs are successfully detected and studied by the temporal resolution transient absorption (TA) spectroscopy method. Since the cooling time of hot excitons extends while the rate of auger recombination is accelerated when incident energy is increased, the filling time of defect states is irregular, and exciton generation experiences a transition from single-photon absorption to multi-photon absorption. This result shows how to change the excitation. Optical parameters can prolong the lifetime of excitons, thus fully extracting excitons and improving the photoelectric conversion efficiency of QD optoelectronic devices, which provides theoretical and experimental support for the development of QD optoelectronic devices.

Triplet-triplet annihilation photon upconversion-mediated photochemical reactions.

Photon upconversion is a method for harnessing high-energy excited states from low-energy photons. Such photons, particularly in the red and near-infrared wavelength ranges, can penetrate tissue deeply and undergo less competitive absorption in coloured reaction media, enhancing the efficiency of large-scale reactions and in vivo phototherapy. Among various upconversion methodologies, the organic-based triplet-triplet annihilation upconversion (TTA-UC) stands out - demonstrating high upconversion efficiencies, requiring low excitation power densities and featuring tunable absorption and emission wavelengths. These factors contribute to improved photochemical reactions for fields such as photoredox catalysis, photoactivation, 3D printing and immunotherapy. In this Review, we explore concepts and design principles of organic TTA-UC-mediated photochemical reactions, highlighting notable advancements in the field, as well as identify challenges and propose potential solutions. This Review sheds light on the potential of organic TTA-UC to advance beyond the traditional photochemical reactions and paves the way for research in various fields and clinical applications.

Amplified Spontaneous Emission from Electron-Hole Quantum Droplets in Colloidal CdSe Nanoplatelets.

Two-dimensional cadmium selenide nanoplatelets (NPLs) exhibit large absorption cross sections and homogeneously broadened band-edge transitions that offer utility in wide-ranging optoelectronic applications. Here, we examine the temperature-dependence of amplified spontaneous emission (ASE) in 4- and 5-monolayer thick NPLs and show that the threshold for close-packed (neat) films decreases with decreasing temperature by a factor of 2-10 relative to ambient temperature owing to extrinsic (trapping) and intrinsic (phonon-derived line width) factors. Interestingly, for pump intensities that exceed the ASE threshold, we find development of intense emission to lower energy in particular provided that the film temperature is ≤200 K. For NPLs diluted in an inert polymer, both biexcitonic ASE and low-energy emission are suppressed, suggesting that described neat-film observables rely upon high chromophore density and rapid, collective processes. Transient emission spectra reveal ultrafast red-shifting with the time of the lower energy emission. Taken together, these findings indicate a previously unreported process of amplified stimulated emission from polyexciton states that is consistent with quantum droplets and constitutes a form of exciton condensate. For studied samples, quantum droplets form provided that roughly 17 meV or less of thermal energy is available, which we hypothesize relates to polyexciton binding energy. Polyexciton ASE can produce pump-fluence-tunable red-shifted ASE even 120 meV lower in energy than biexciton ASE. Our findings convey the importance of biexciton and polyexciton populations in nanoplatelets and show that quantum droplets can exhibit light amplification at significantly lower photon energies than biexcitonic ASE.

Study of poly allyl diglycol carbonate Kinetics treatment induced by ultrasonic frequency plasma

This research reveals the possibility of altering the structural, surface, fluorescence, and optical characteristics of CR-39 polymer detector by the effect of Ultrasonic frequency (UF) plasma argon gas. The samples were exposed to the plasma at different times ranging from 20 min to 100 min. Fourier Transform Infrared (FTIR) Spectroscopy, contact angle goniometer, surface roughness tester, photoluminescence spectroscopy, and UV/Vis Spectroscopy have been applied to analyze alterations of CR-39 polymeric films to understand the mechanisms of produced alterations by plasma treatment. The obtained FTIR spectra demonstrated that the plasma treatment-related changes in the absorption bands are associated with the treatment time, leading to two critical processes, degradation, and crosslinking. In comparison to the untreated surface, the surface wettability results showed that the liquids' contact angle decreased after treatment with a UF plasma source. This modification in the treated surface denotes an increase in polar groups there, which causes the surface to change to a hydrophilic state. The surface roughness of the samples following plasma treatment showed that UF plasma significantly changed the surface morphology of the CR-39 films. After plasma exposure, considerable emission bands were produced, and the photoemission spectra of the treated film showed a fluorescence response. As the exposure time increased, more fluorescence peaks were formed due to the increase in defects. The UV/Vis spectra showed that the modified films' absorption edges were moved toward lower photon energies. This resulted in a smaller optical energy gap, which led to an expansion of the carbon cluster. Additionally, the untreated sample's transmittance dropped from 92% to 47% for the treated film. In contrast to untreated films, a change in optical characteristics was seen in treated films.

Derivation of the Schrödinger equation from QED

The Schrödinger equation relates the emergent quantities of wavefunction and electric potential and is postulated as a principle of quantum physics or obtained heuristically. However, physical consistency requires that the Schrödinger equation is a low-energy dynamical condition we can derive from the foundations of quantum electrodynamics. Due to the small value of the electromagnetic coupling constant, we show that the electric potential accurately represents the contributions of intermediate low-energy photon exchanges. Then, from the total nonrelativistic energy relation, we see that the dominant term of the electron wavefunction is a superposition of plane waves that satisfies the Schrödinger equation. Our derivation shows that the Schrödinger equation is not an energy conservation relation because its middle term does not represent the electron kinetic energy as assumed. We analyze the physical content of the Schrödinger equation and verify our assessments by calculating and evaluating the physical quantities in the ground state of the hydrogen atom. Furthermore, we explain why nonrelativistic quantum dynamics differs from classical dynamics. Undergraduate students can follow the derivation because it involves fundamental physical concepts and mathematical expressions, and we explain every step.

New Physics – The Negation of Einstein’s Theories of Relativity

From ontological considerations alone, a new revolutionary quantum dynamical-materialist dialectical (Quantum Dialectics or QD) perspective of space-time-matter-motion achieves a new quantitative mass-energy-velocity relation for any ponderable fundamental particles. This new relation, based on the quantum uncertainty principle, gives the mass m of any free fundamental particle at its origin, in terms of the inverse cube of its velocity v. This quantitative relation is different and is a negation of the one derived from mechanical-metaphysical (Classical Mechanics or CM) approach since Isaac Newton and its relativistic post-quantum formulation of Albert Einstein. This new mass-energy-velocity relation is in conformity with known knowledge and is appropriately substantiated by the recent reports that “high-energy photons of gamma radiation from a distant galaxy arrived at Earth four minutes after lower-energy photons, although they were apparently emitted at the same time”; and another saying that “the time delays of gamma-ray photons are inversely proportional to their energy”. These findings would contradict Einstein's theory of relativity, which says that all photons (particles of light) must move at the same speed c. QD considers matter-antimatter particle pairs in their elementary virtual forms and kinetic motion as an eternal quantum dynamical process of existence and non-existence (Being-Nothing) arising from abstract space and abstract time in a contradiction to each other. The virtual particles can transition to real particles through quantum tunnelling or when equivalent energy becomes available. Any existence in this view is a contradiction; vulnerable to change, motion, evolution, development etc. The aggregation of the elementary particles and their motions mediated by chance and necessity, give rise to the phenomenology of this infinite, eternal and ever-changing universe. The CM approach on the contrary is based on epistemology and considers that matter (ordinary + light) and motion have an esoteric origin from the mystery of the single act of creation by God; of a finite universe in the finite past; where the premise of conservation laws and “ex nihilo nihil fit” prevail. In its relativistic version, this approach makes a fundamental difference between ponderable matter and light and in fact question the existence of particulate matter. Two axiomatic assumptions, one by Newton of one-sided universal gravitational attraction and the other by Einstein that the velocity of light c is an absolute and universal constant has brought in unphysical objects and phenomena into scientific discourse leading to century-long confusion and scholastic debates among the physicists; with no end in sight!

High-entropy strategy for high-temperature broadband infrared radiation and low thermal conductivity

Developing high-performance infrared radiation ceramic materials with desired broadband emissivity while reducing thermal conductivity to prevent heat transfer is highly desirable for emerging industrial and aerospace applications. Nevertheless, it remains a grand challenge to simultaneously meet these requirements in existing infrared radiation ceramic materials. Herein, a high-entropy strategy is employed to enhance the high-temperature infrared radiation property with a high emissivity above 0.9 at room temperature and 0.68 at 1200 °C across the entire range of wavelength (1–14 μm), and integrate a low thermal conductivity (<0.88 W m−1 K−1 at 1000 °C) and remarkable mechanical properties. High-entropy rare earth (RE) disilicates ((Y0.4Yb0.4Tm0.1Lu0.05Ho0.05)2Si2O7) ceramic coating with high lattice entropy has a more complex electronic structure, inducing lattice distortion and extra multi-mode vibrations, which boosts the emissivity in mid-infrared range (3–14 μm). Meanwhile, the high-entropy strategy prompts the formation of impurity energy levels as gap states, achieving optical absorption at low photon energies, and thus enhancing the emissivity in near-infrared range (1–3 μm). Simultaneously, (Y0.4Yb0.4Tm0.1Lu0.05Ho0.05)2Si2O7) ceramic coating owns diffusion-mediated thermal transport properties with strong phonon scattering, assisted further by the lamellar porous structure, thereby enabling a low thermal conductivity. The excellent mechanical properties ensure the reliability of the coating in extreme environments. All these merits render the high-entropy ceramic coating competitive for the development of high-temperature broadband high-emissivity thermal radiation materials.

The Hirshfeld topological surfaces, volumes, and their voids charge density interplay on radiation shielding properties: A case study of carbide-based ceramics

Transition metal carbides (TMCs) are explored for their potential as radiation shielding materials, with a focus on their γ-ray attenuation properties. These high-density materials, including WC, TaC, HfC, NbC, and VC, are evaluated across an energy range of 0.015–15.0 MeV. Notably, at low incoming photon energy (0.0150 MeV), these TMCs exhibit mass attenuation coefficients (MAC) (TMC, MAC (g/cm2)): (WC, 130.417), (TaC, 125.730), (HfC, 120.873), (NbC, 23.751), and (VC, 32.377) and effective atomic numbers (Zeff) from 22.69 to 73.68. These values surpass those of silicon dioxide (SiO2), highlighting the superior γ-ray attenuation capabilities of TMCs. TMCs exhibit a distinct trend in MAC values, with tungsten carbide (WC) consistently demonstrating the highest MAC values, making it the most efficient γ-ray attenuator. Hafnium carbide (HfC) closely follows, with tantalum carbide (TaC) exhibiting lower MAC values, while niobium carbide (NbC) and vanadium carbide (VC) display the lowest values. These differences can be attributed to variations in material composition and structure. Furthermore, the study delves into the impact of charge density within Hirshfeld voids on LAC values, revealing that as X⁴⁺ … C interactions increase due to higher charge density, LAC values rise. This fine-tuning of topological and charge density distributions within the crystal's voids offers a promising avenue to optimize these materials for enhanced radiation shielding effectiveness. Overall, this research contributes to the understanding of the potential utility of TMCs in radiation shielding applications, showcasing the interplay between crystal structure, composition, and charge distribution as key factors in determining their radiation attenuation capabilities.