Light Mass Research Articles

A case study on dome structure of composite structural insulation panels with ANSYS simulations

Thin-shell dome structures are conventionally built with concrete. However, the building process is time-consuming and of high labor cost. Composite Structural Insulation Panels (CSIPs) have recently been regarded to be suitable for large-span civil structures, in terms of its light weight, easy processing, and mass production. Hence, this paper explores the feasibility of CSIPs domes applied in large-span dome structures. Compared with the performance of thin-shell concrete domes, the stiffness, strength, and stability of CSIPs domes are studied by means of refined finite element analysis. Results demonstrate CSIPs dome possesses good dynamic performance, bears larger nonlinear loads, and even copes with stress loads under earthquakes. Moreover, the stiffness should be handled in the onsite applications to fulfil the safety requirements.

Chiral Z′ in FASER, FASER2, DUNE, and ILC beam dump experiments

The origin of neutrino mass is a big unsolved problem of the Standard Model (SM) that motivate us to consider beyond the SM (BSM) scenarios where SM-singlet right-handed neutrinos (RHNs) are introduced to explain the origin of the light neutrino masses through the seesaw mechanism. There is a variety of ways which could lead us to this goal and one of them is a general U$(1)$ extension of the SM. In this scenario, three SM-singlet RHNs are introduced to cancel the gauge and mixed gauge gravity anomalies. After anomaly cancellation, we notice that the left- and right-handed charged fermions are differently charged under the general U$(1)$ gauge group evolving a chiral scenario. After the breaking of the general U$(1)$ symmetry, a neutral BSM gauge boson $(Z^\prime)$ acquires mass and it is a free parameter. Such $Z^\prime$, being lighter than $5$ GeV, could be probed at the intensity and lifetime frontiers like FASER, FASER2, DUNE, and ILC beam dump experiments. The estimated bounds are needed to be compared with the existing bounds. We find that existing constraints from Orsay, Nomad, PS191, KEK, LSND, CHARM experiments, and cosmological scenario like SN1987A can be compared in our case once estimated for chiral scenarios. Finally, we compare the parameter spaces showing viable ones that could be probed by FASER, FASER2, DUNE, and ILC beam dump experiments and already excluded regions from Orsay, Nomad, PS191, KEK, LSND, CHARM, and SN1987A for a chiral scenario.

Unified origin of dark matter self interactions and low scale leptogenesis

We propose a novel and minimal framework where a light scalar field can give rise to dark matter (DM) self-interactions, while enhancing the CP symmetry required for successful baryon asymmetry of the Universe via leptogenesis route. For demonstration purpose we choose to work in a scotogenic seesaw scenario where the lightest among the right handed neutrinos (RHN), introduced for generating light neutrino masses radiatively, play the role of DM while the heavier two can play non-trivial roles in generating DM relic as well as lepton asymmetry. While dark matter self-interactions mediated by an additional singlet scalar can alleviate the small scale issues of cold dark matter paradigm, the same scalar can give rise to new one-loop decay processes of heavy RHN into standard model leptons providing an enhanced contribution to CP asymmetry, even with sub-TeV scale RHN mass. The thermally under-abundant relic of DM due to large annihilation rates into its light mediator receives a late non-thermal contribution from a heavier RHN. With only five new particles involved in the scotogenic seesaw, each having non-trivial roles in generating DM relic and baryon asymmetry, the model can explain non-zero neutrino mass while being verifiable at different experiments related to DM direct detection, flavour physics and colliders. The mechanism we demonstrated here by using a scotogenic seesaw scenario is also applicable to other models.

Preparation of Bio-Based Aerogel and Its Adsorption Properties for Organic Dyes.

The effective utilization of biomass and the purification of dye wastewater are urgent problems. In this study, a biomass aerogel (CaCO3@starch/polyacrylamide/TEMPO-oxidized nanocellulose, CaCO3@STA/PAM/TOCN) was prepared by combining nanocellulose with starch and introducing calcium carbonate nanoparticles, which exhibited a rich three-dimensional layered porous structure with a very light mass. Starch and nanocellulose can be grafted onto the molecular chain of acrylamide, while calcium carbonate nanopores can make the gel pore size uniform and have excellent swelling properties. Here, various factors affecting the adsorption behavior of this aerogel, such as pH, contact time, ambient temperature, and initial concentration, are investigated. From the kinetic data, it can be obtained that the adsorption process fits well with the pseudo-second-order. The Langmuir isotherm model can fit the equilibrium data well. The thermodynamic data also demonstrated the spontaneous and heat-absorbing properties of anionic and cationic dyes on CaCO3@STA/PAM/TOCN aerogels. The adsorption capacity of Congo red (CR) and methylene blue (MB) by CaCO3@STA/PAM/TOCN was 277.76 mg/g and 101.01 mg/g, respectively. Therefore, cellulose and starch-based aerogels can be considered promising adsorbents for the treatment of dye wastewater.

Common origin of θ13 and dark matter within the flavor symmetric scoto-seesaw framework

To understand the observed pattern of neutrino masses and mixing as well as to account for the dark matter we propose a hybrid scoto-seesaw model based on the A4 discrete flavor symmetry. In this setup, including at least two heavy right-handed neutrinos is essential to employ the discrete flavor symmetry that mimics once popular tribimaximal neutrino mixing at the leading order via type-I seesaw. The scotogenic contribution then acts as a critical deviation to reproduce the observed value of the reactor mixing angle θ13 (within the trimaximal mixing scheme) and to accommodate potential dark matter candidates, pointing towards a common origin of θ13 and dark matter. The model predicts the atmospheric angle to be in the upper octant, excludes some regions on the Dirac CP phase, and restricts the Majorana phases too. Further, normal and inverted mass hierarchies can be distinguished for specific values of the relative phases associated with the complex light neutrino mass matrix. Owing to the considered flavor symmetry, contributions coming from the scotogenic mechanism towards the lepton flavor violating decays such as μ → eγ, τ → eγ vanish, and a lower limit on the second right-handed neutrino mass can be obtained. Prediction for the effective mass parameter appearing in the neutrinoless double beta decay falls within the sensitivity of future experiments such as LEGEND-1k and nEXO.

Fermion masses and mixings, dark matter, leptogenesis and $$g-2$$ muon anomaly in an extended 2HDM with inverse seesaw

We propose a predictive \(Q_4\) flavored 2HDM model, where the scalar sector is enlarged by the inclusion of several gauge singlet scalars and the fermion sector by the inclusion of right-handed Majorana neutrinos. In our model, the \(Q_4\) family symmetry is supplemented by several auxiliary cyclic symmetries, whose spontaneous breaking produces the observed pattern of SM charged fermion masses and quark mixing angles. The light active neutrino masses are generated from an inverse seesaw mechanism at one loop level thanks to a remnant preserved \(Z_2\) symmetry. Our model successfully reproduces the measured dark matter relic abundance and is consistent with direct detection constraints for masses of the DM candidate around \(\sim\) 6.3 TeV. Furthermore, our model is also consistent with the lepton and baryon asymmetries of the Universe as well as with the muon anomalous magnetic moment.

The effect of the digital printing of fabric on the morphology of passive bloodstains

Bloodstained fabrics found at crime scenes are likely to have had processing treatments, such as dyeing or printing, but the effect of the treatments on bloodstain morphology is not always considered. In order to study the effect of digital printing on bloodstain morphology, drip stains were created from five impact velocities (1.9–5.4 ms−1) on three different mass per unit areas (88–226 g/m²) of 100% cotton calico which had been digitally printed using reactive dye. Across all three printed fabrics, the bloodstains appeared visually similar, and no correlation was found between the dry bloodstain area and the impact velocity. When comparing the bloodstains on the printed fabric to those which had been created previously on the same fabric in a dyed and not-coloured state, the dry bloodstains on the printed fabric were statistically significantly larger (e.g. for the calico with the lightest mass per unit area, mean dry bloodstain area was 126.6, 64.4 and 44.3 mm² for the printed, dyed and not-coloured fabrics respectively). Examination of the larger bloodstains on the printed calico with the micro computed tomography scanner and scanning electron microscope, suggested that the printing process increased the wettability of the fabric, so the blood could spread more easily on the surface. This allowed the blood to coat the yarns, and wick into them before wicking along the intra-yarn spaces. The results presented in this paper showed that care must be taken when examining bloodstains at crime scenes. Depending on the fabric and the processing of the fabric the size of the blood stains may not increase with impact velocity as wicking may result in a larger bloodstain from a lower velocity. The bloodstain on the penetrated face of the fabric may be larger than on the impacted face and the same fabrics with different processing will produce different blood stain sizes and shapes.

Multifunctional carbon aerogels from typha orientalis for applications in adsorption: Hydrogen storage, CO2 capture and VOCs removal

Biomass-derived cellulose carbon aerogels with a 3D network structure were synthesized from Typha Orientalis (TO). The TO cellulose carbon aerogels feature light mass (3.65 mg/cm3), super-hydrophobicity, and large specific surface areas (1840 cm2/g). Because of the outstanding microporous volume and the abundant functional groups, the TO carbon aerogels can be used as multifunctional adsorbent materials in different applications. The results demonstrate that the material has 0.6 wt% hydrogen storage capacity at room temperature, 16 mmol/g CO2, 123.31 mg/g o-xylene and 124.57 mg/g o-dichlorobenzene adsorption capacity. The o-xylene adsorption capabilities of the sample were reduced by just 12% after four thermal regeneration cycles, demonstrating the realistically good reusability of TO cellulose carbon aerogels and is expected to be applied to dioxin removal. The current research can offer a green approach to fabricating ultra-light TO cellulose carbon aerogels with promising applications in energy storage and environmental protection. In addition, the preparation can be applied for the fabrication of other multifunctional aerogels by solid waste for different applications.

Neutrino mass and charged lepton flavor violation in an extended left-right symmetric model

We consider an U(1)Lμ−Lτ extended left-right symmetric gauge theory where the neutrino masses are generated through inverse seesaw mechanism. In this model the muon (g−2) anomaly is accounted for by the mediation of Zμτ, the gauge boson of U(1)Lμ−Lτ symmetry. The symmetries of the model require the light neutrino mass matrix to have a particular two-zero texture, which leads to non-trivial constraints in the minimum neutrino mass. In addition, the model predicts observable charged lepton flavor violation in μ−τ sector.

Advancements on process regulation for microalgae-based carbon neutrality and biodiesel production

Microalgae biotechnology is a promising pathway to cope with CO2 emission and energy crisis due to high CO2 fixation rate and lipids productivity. However, bottlenecks of high energy cost, low photosynthetic efficiency and poor economic feasibility severely hinder its commercialization. Understanding process mechanisms of microalgae photosynthetic CO2 fixation and lipids production, and thus seeking possible regulations to enhance weak links are potential process regulation strategy for augmented competitiveness. Firstly, mass transfer and conversion processes of microalgae photosynthesis involving CO2 and light were comprehensively illuminated in this review. In detail, mechanisms of CO2 and light transfer in microalgae suspension, bioavailable carbon and photon assimilation by microalgae cells, as well as intracellular mass conversion were illustrated. Besides, synergistic effects of light and CO2 on microalgae photosynthesis were depicted from perspective of electrons and protons supply-demand relationships between photosynthetic photo-reaction and dark-reaction steps in chlorophyll. Possible weak links in these processes were emphasized to provide guideline for regulation. Secondly, available regulation strategies for CO2 and light mass transfer, cellular assimilation and intracellular conversion were summarized. Subsequently, economic and environmental impacts of process regulation on microalgae CO2 fixation and biodiesel output were evaluated to lit up large-scale applicability. Finally, challenges and future directions of microalgae biotechnology were described to inspire in-depth research and engineering practice. This review may provide a novel process regulation standpoint for operating microalgae-based CO2 fixation and biodiesel production in the most efficient manner, further facilitating the applicability of microalgae biotechnology towards carbon neutrality and biodiesel production.

Low-threshold sapphire detector for rare event searches

Low mass nuclear recoil dark matter and coherent-elastic-neutrino-nucleus-scattering (CEνNS) searches confront similar challenges in choosing ultra-low threshold and large-mass detectors. We report experimental results from a 100 g single-crystal sapphire detector design with a diameter of 76 mm and thickness of 4 mm instrumented with transition edge sensors (TES). Sapphire is a crystal of aluminum oxide (Al2O3) and has been found to be a good candidate for light mass dark matter search experiments due to its lower atomic mass compared to other detector materials such as germanium and silicon. This new phonon-assisted sapphire detector was characterized to yield a baseline recoil energy resolution of 28.4 ± 0.4 eV. The detector is designed to be sensitive to low-energy rare interactions with an intention to investigate the low-mass region of dark matter phase-space and search for CEνNS at the reactor site.

Safety Assessment and Crash Compatibility of Heavy Quadricycle under Frontal Impact Collisions

An electric heavy quadricycle, categorized as an L7e vehicle, is an alternative solution for sustainable mobility with a lower carbon footprint and high energy consumption efficiency. However, accidental crashes of quadricycles with larger vehicle opponents can cause extensive damage to their structures and fatal injury to the occupants due to their geometry drawback in limited space in the front crumple zone. This work investigates the crashworthiness performance and safety assessment of the L7e vehicle under rigid wall crash tests and crash compatibility in car-to-car collisions with a sedan and an SUV. Crash scenarios are simulated using a nonlinear finite element analysis via LS-DYNA to evaluate structural crashworthiness and occupant injuries of a hybrid III 50th percentile male dummy. The compatible vertical alignment of the primary energy-absorbing structure substantially affects the safety of the quadricycle under a frontal crash. A secondary energy-absorbing component should be adapted to the L7e vehicle to achieve vertical alignment with different vehicle sizes. In addition, the typical rigid-wall frontal crash test at 50 kph considerably underestimates the structural damage and occupant injury of the L7e vehicle compared to car-to-car collisions. Thus, additional crash tests representing car-to-car collisions that account for the car’s smaller size and lighter mass should be included in the safety regulation for the L7e vehicle.

Ultralight N-doped platanus acerifolia biomass carbon microtubes/RGO composite aerogel with enhanced mechanical properties and high-performance microwave absorption

Biomass-derived carbon material, an ideal lightweight and sustainable electromagnetic wave (EMW) absorption material, has adjustable dielectric properties, which is one of its greatest advantages. However, how to comprehensively control its composite dielectric constant to achieve strong microwave absorption (MA), wide effective absorption bandwidth (EAB), light mass, and thin thickness is still challenging. In this study, the N-doped biomass carbon microtubes/RGO composite aerogel (N-BCMT/RGO) with a three-dimensional multistage pore network structure was prepared by using the waste Platanus acerifolia tree fruit-derived biomass microtubes as the base, through heteroatom doping and composite conductive material. Among them, the doping of nitrogen atoms introduces numerous defects and promotes the formation of a heterogeneous interface, which plays an important role in regulating conduction and polarization loss. Secondly, the introduction of conductive material effectively promotes the hopping and migration of electrons, which further enhances the conduction loss. Moreover, the close binding of BCMT and RGO causes N-BCMT/RGO aerogel to exhibit enhanced mechanical properties. The special multistage hole structure allows N-BCMT/RGO to exhibit good impedance matching and ultra-low density (0.0121 g/cm3), which also exhibits an ultra-wide EAB of 8.36 GHz and a minimum reflection loss (RLmin) of −55.45 dB at an ultra-low filler loading of 2 wt%. This opens up an avenue for the realization of novel microwave absorbers with light weight and high performance, and the proposed comprehensive control strategy for the composite permittivity of biomass-carbon materials provides new ideas for activating the MA behavior of metal-free carbon-based absorbers.

Leptogenesis in SO(10) models with A4 modular symmetry

We study the prediction for leptogenesis in two renormalizable supersymmetric SO(10) × A4 modular models in which the neutrino mass is dominantly generated by the type I seesaw mechanism. The evolution of the lepton asymmetries are described in terms of the three-flavored density matrix equations for three heavy Majorana neutrinos, where both vanishing initial condition and thermal initial condition of the right-handed neutrinos are considered. We also present an analytical approximation based on the Boltzmann equations. We find regions of parameter space compatible with the measured fermion masses and mixing parameters as well as the baryon asymmetry of the Universe. The predictions for the light neutrino masses, the effective mass in neutrinoless double beta decay and the leptonic CP violation phases are discussed.

Quantum oscillations in the magnetization and density of states of insulators

The observation of [Formula: see text]-periodic behavior in Kondo insulators and semiconductor quantum wells challenges the conventional wisdom that quantum oscillations (QOs) necessarily arise from Fermi surfaces in metals. We revisit recently proposed theories for this phenomenon, focusing on a minimal model of an insulator with a hybridization gap between two opposite-parity light and heavy mass bands with an inverted band structure. We show that there are characteristic differences between the QO frequencies in the magnetization and the low-energy density of states (LE-DOS) of these insulators, in marked contrast to metals where all observables exhibit oscillations at the same frequency. The magnetization oscillations arising from occupied Landau levels occur at the same frequency that would exist in the unhybridized case. The LE-DOS oscillations in a disorder-free system are dominated by gap-edge states and exhibit a beat pattern between two distinct frequencies at low temperature. Disorder-induced in-gap states lead to an additional contribution to the DOS at the unhybridized frequency. The temperature dependence of the amplitude and phase of the magnetization and DOS oscillations are also qualitatively different and show marked deviations from the Lifshitz-Kosevich form well known in metals. We also compute transport to ensure that we are probing a regime with insulating upturns in the direct current (DC) resistivity.

Concerted versus stepwise mechanisms of cyclic proton transfer: Experiments, simulations, and current challenges

Proton transfer (PT) is a process of fundamental importance in hydrogen (H)-bonded systems. At cryogenic or moderate temperatures, pronounced quantum tunneling may happen due to the light mass of H. Single PT processes have been extensively studied. However, for PT involving multiple protons, our understanding remains in its infancy stage due to the complicated interplay between the high-dimensional nature of the process and the quantum nature of tunneling. Cyclic H-bonded systems are typical examples of this, where PT can happen separately via a “stepwise” mechanism or collectively via a “concerted” mechanism. In the first scenario, some protons hop first, typically resulting in metastable intermediate states (ISs) and the reaction pathway passes through multiple transition states. Whilst in the concerted mechanism, all protons move simultaneously, resulting in only one barrier along the path. Here, we review previous experimental and theoretical studies probing quantum tunneling in several representative systems for cyclic PT, with more focus on recent theoretical findings with path-integral based methods. For gas-phase porphyrin and porphycene, as well as porphycene on a metal surface, theoretical predictions are consistent with experimental observations, and enhance our understanding of the processes. Yet, discrepancies in the PT kinetic isotope effects between experiment and theory appear in two systems, most noticeably in water tetramer adsorbed on NaCl (001) surface, and also hinted in porphycene adsorbed on Ag (110) surface. In ice I h, controversy surrounding concerted PT remains even between experiments. Despite of the recent progress in both theoretical methods and experimental techniques, multiple PT processes in cyclic H-bonded systems remain to be mysterious.

High-mobility two-dimensional carriers from surface Fermi arcs in magnetic Weyl semimetal films

High-mobility two-dimensional carriers originating from surface Fermi arcs in magnetic Weyl semimetals are highly desired for accessing exotic quantum transport phenomena and for topological electronics applications. Here, we demonstrate high-mobility two-dimensional carriers that show quantum oscillations in magnetic Weyl semimetal SrRuO3 epitaxial films by systematic angle-dependent, high-magnetic field magnetotransport experiments. The exceptionally high-quality SrRuO3 films were grown by state-of-the-art oxide thin film growth technologies driven by machine-learning algorithm. The quantum oscillations for the 10-nm SrRuO3 film show a high quantum mobility of 3.5 × 103 cm2/Vs, a light cyclotron mass, and two-dimensional angular dependence, which possibly come from the surface Fermi arcs. The linear thickness dependence of the phase shift of the quantum oscillations provides evidence for the non-trivial nature of the quantum oscillations mediated by the surface Fermi arcs. In addition, at low temperatures and under magnetic fields of up to 52 T, the quantum limit of SrRuO3 manifests the chiral anomaly of the Weyl nodes. Emergence of the hitherto hidden two-dimensional Weyl states in a ferromagnetic oxide paves the way to explore quantum transport phenomena for topological oxide electronics.

Reviving keV sterile neutrino dark matter

We propose a new production mechanism for keV sterile neutrino dark matter which relies neither on the oscillations between sterile and active neutrinos nor on the decay of additional heavier particles. The dark matter neutrinos are instead produced by thermal freeze-out, much like a typical WIMP. The challenge consists in balancing a large Yukawa coupling so that the sterile neutrinos thermalize in the early universe on the one hand, and a small enough Yukawa coupling such that they are stable on cosmological scales on the other. We solve this problem by implementing varying Yukawa couplings. We achieve this by using a three-sterile neutrino seesaw extension to the SM and embedding it in a Froggatt-Nielsen model with a single flavon. Because the vev of the flavon changes during the electroweak phase transition, the effective Yukawa couplings of the fermions have different values before and after the phase transition, thus allowing for successful dark matter genesis. Additionally, the hierarchy in the flavour structure is alleviated and the origin of the light neutrino masses is explained by the interplay of the seesaw and Froggatt-Nielsen mechanisms.

STUDY FOR FERMION DARK MATTER PRODUCTION IN PHOTON-PHOTON COLLISION

Fermion dark matter (FDM) production is investigated via photonphoton collision and the cross section of the FDM production is calculated in detail. Our results are evaluated at different values of the dark matter scale  and the light FDM mass.

Construction of novel PG/GeP2 and PG/SiP2 vdW heterostructures for high-efficiency photocatalytic water splitting

The development and design of environmentally friendly, low-cost efficient visible-light-driven water splitting photocatalysts is a kind of the most promising methods to solve current energy shortage problems. Herein, the brand new penta-graphene/GeP2 (PG/GeP2) and PG/SiP2 van der Waals (vdW) heterostructures are constructed. Their geometric structures, thermodynamic feasibilities, and optoelectronic properties for water splitting are systematically investigated through DFT calculation. The results show that the band-gap value and band-edge positions prove these heterostructures are promising candidates for water splitting. Meanwhile, The Gibbs free energy change proves that the water-splitting progress is spontaneous. Especially, PG/GeP2 has a type-II band alignment and an indirect bandgap of 2.63 eV, and the electrical properties of PG/GeP2 heterostructure under −2% strain are adjusted to better catalyze the water-splitting reaction, improve the light absorption characteristic and effective mass of carrier. The unique band alignment of these heterostructures photocatalysts leads to high solar-to-hydrogen energy conversion efficiencies up to 10.8%, which has a good commercial application prospect. Therefore, these studies predict that PG/GeP2 vdW heterostructure is important candidates as photocatalysts for overall water splitting.