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Aiming to significantly improve the accuracy of LIBS measurements, we have achieved a significant improvement in MW injection, further SNR enhancement we demonstrate here using multi-fiber to receive the plasma spectrum. Laser-induced breakdown spectroscopy (LIBS) is often limited by weak plasma emission and poor signal-to-noise ratio (SNR), which restrict its detection limits for trace element analysis. In this study, we investigated a dual-enhancement strategy that combines a coaxial multifiber bundle with microwave (MW) excitation. A six-fiber array (200 µm core, coaxial geometry) increased plasma light collection efficiency, yielding up to a six-fold improvement in broadband emission intensity compared to a single-fiber configuration. When coupled with a 2.45 GHz pulsed microwave source, emission signals were further amplified by two to three orders of magnitude. The combined multifiber–microwave approach produced a dramatic ~ 2000-fold enhancement in emission intensity and a two- to three-order-of-magnitude improvement in SNR relative to conventional LIBS. Preliminary measurements on aluminum alloys demonstrated that the limit of detection improved from 1.016 wt.% (no MW) to 0.590 wt.% (with MW) for aluminum (Al), and from 0.378 wt.% to 0.323 wt.% for iron (Fe). The MW effect alone provided a ~ 500-fold enhancement, while fiber bundling contributed more than a 7.5-fold gain, nearly proportional to the number of fibers. Together, these improvements yielded an overall SNR increase of approximately 1500-fold compared with standard LIBS. To our knowledge, this is the first report demonstrating the synergy between multifiber collection and microwave excitation in LIBS. These findings open new opportunities for extending LIBS detection limits in applications such as environmental monitoring, alloy characterization, and nuclear materials analysis.

We developed a semiconductor microwave system to improve the ignition process in a combustion system. Under atmospheric pressure conditions, large plasma was successfully ignited by a 2.45 GHz microwave, and it is characterized in comparison with standard spark plug ignition and laser ignition. The size of the microwave power source was also effectively reduced with the minimal size (100 × 60 mm2) that could fit in the palm of a hand. We then prototyped a microwave plug with a diameter of 4 mm, which is smaller than the standard spark plugs for passenger cars. The design and electric field strength are discussed in detail. Combustion experiments were conducted using a motorcycle engine and an actual light vehicle, and significant fuel efficiency improvement was experimentally obtained. We investigated the wear of the plug caused by continuous operation, and efficiently improved the endurance by swinging the resonance frequency between 2.4 and 2.5 GHz. In a passenger car engine experiment using a flat panel igniter, significant fuel efficiency improvement was confirmed. Further failure analysis revealed that the ceramic was severely damaged by a large current surge.

The relationship between the flow field and flame propagation is essential in determining the dynamics and effects of turbulent flow in an optical SI engine. In this study, high turbulence flow at stable operations was achieved using 12,000 rpm engine speed, 60 kPa absolute intake pressure, 14.7 A/F, and 15 deg. BTDC spark timing. The turbulent flow field and flame propagation interplay were analyzed through the simultaneous high-speed PIV measurements of the in-cylinder flow and flame front propagation under firing conditions. The intensity of the seeder used was optimized by changing the crank angle. Successful simultaneous detection of the flame front and turbulent flow was demonstrated. Strong turbulence was produced at the flame front simultaneously with the flame movement. After ignition timing, the flame accelerated in the unburned region, and a vital turbulence region occurred.

Quantitative and well-targeted design of modern alloys is extremely challenging due to their immense compositional space. When considering only 50 elements for compositional blending the number of possible alloys is practically infinite, as is the associated unexplored property realm. In this paper, we present a simple property-targeted quantitative design approach for atomic-level complexity in complex concentrated and high-entropy alloys, based on quantum-mechanically derived atomic-level pressure approximation. It allows identification of the best suited element mix for high solid-solution strengthening using the simple electronegativity difference among the constituent elements. This approach can be used for designing alloys with customized properties, such as a simple binary NiV solid solution whose yield strength exceeds that of the Cantor high-entropy alloy by nearly a factor of two. This study provides general design rules that enable effective utilization of atomic level information to reduce the immense degrees of freedom in compositional space without sacrificing physics-related plausibility. Designing complex concentrated alloys with targeted properties for high performance remains challenging because of their complex local atomic environments. Here, the authors show how to engineer atomic-level pressure to customize complexity-induced properties such as solid-solution strengthening.

We present deep near-infrared (NIR) imaging of Sh 2–209 (S209), a low-metallicity ([O/H] = −0.5 dex) H ii region in the Galaxy. From the NIR images, combined with astrometric data from Gaia EDR3, we estimate the distance to S209 to be 2.5 kpc. This is close enough to enable us to resolve cluster members clearly (≃1000 au separation) down to a mass-detection limit of ≃ 0.1 M ⊙, and we have identified two star-forming clusters in S209, with individual cluster scales ∼1 pc. We employ a set of model luminosity functions to derive the underlying initial mass functions (IMFs) and ages for both clusters. The IMFs we obtained for both clusters exhibit slightly flat high-mass slopes (Γ ≃ −1.0) compared to the Salpeter IMF (Γ = −1.35), and their break mass of ≃0.1 M ⊙ is lower than those generally seen in the solar neighborhood (∼0.3 M ⊙). In particular, because the S209 main cluster is a star-forming cluster with a larger number of members (∼1500) than the number (∼100) in regions previously studied in such environments, it is possible for the first time to derive the IMF in a low-metallicity environment with high accuracy over the wide mass range of 0.1–20 M ⊙.

Callogobius albipunctatus sp. nov. and Callogobius dorsomaculatus sp. nov. are described from Japan. Both species are included in the sclateri group, characterized by elongate ctenii on the caudal fin base scales, the female urogenital papilla with two lateral projections, and the presence of cephalic sensory papillae Row 20 (preopercular row). Callogobius albipunctatus is characterized by cephalic sensory papillae Row 16 (transverse mandibular rows) comprising 10 papillae rows and a posteriormost single papilla, connected pelvic fins with a low frenum and concave posterior margin, cephalic sensory canal pores B'D(s)FH', 25–29 longitudinal row scales, 8–10 transverse row scales, and 7–11 predorsal scales, and C. dorsomaculatus by Row 16 comprising 11 papillae rows and a posteriormost single papilla, connected pelvic fins with a concave posterior margin but lacking a frenum, cephalic sensory canal pores B'C(s)D(s)EFH' or B'C(s)D(s)EFGH', 20–26 longitudinal row scales, 7–9 transverse row scales, and 6–10 predorsal scales. The cephalic sensory system in juvenile C. albipunctatus is described. Row 16, which is represented by three patterns within the genus, is redefined.

This study explores the potential of utilizing microwaves to sustain the expansion of transient laser ablation plasma of Zr target. By application of microwaves on the plasma, we observe a significant enhancement with a two to three order of magnitude increase in the plasma emission intensity, and 18 times increase in the plasma’s spatial volume. We investigate the temperature change of the plasma and observe that it decreases from 10,000 K to approximately 3000 K. Electron temperature decreased with volume expansion owing to increased surrounding air interaction, while the plasma can be sustained in air using microwaves. The increase in electron temperature during temperature drop is indicative of non-equilibrium plasma. Our results emphasize the contribution of microwaves in promoting enhanced emission and plasma formation at controlled, low temperature, thereby demonstrating the potential of microwaves to enhance the accuracy and performance of laser-induced breakdown spectroscopy. Importantly, our study suggests that microwaves could also mitigate the generation of toxic fumes and dust during ablation, a critical benefit when handling hazardous materials. The system we've developed is highly valuable for a range of applications, notably including the potential to reduce the possible emergence of toxic fumes during the decommissioning of nuclear debris.

We report on the analysis of pure gadolinium oxide (Gd 2 O 3 ) and its detection when mixed in surrogate nuclear debris using microwave-enhanced fiber-coupled micro-laser-induced breakdown spectroscopy (MWE-FC-MLIBS). The target application is remote analysis of nuclear debris containing uranium (U) inside the Fukushima Daiichi Nuclear Power Station. The surrogate nuclear debris used in this study contained gadolinium (Gd), cerium (Ce), zirconium (Zr), and iron (Fe). Ce is a surrogate for U, and Gd 2 O 3 is an excellent hazard index because it is incorporated into some fuel rods. Gd detection is essential for assessing debris prior to the retrieval process. Surrogate debris was ablated by an 849 ps 1064 nm micro-laser under atmospheric pressure conditions while a helical antenna propagated 2.45 GHz 1.0 kW microwaves for 1.0 ms into the laser ablation, which was then characterized by a high-speed camera and high-resolution spectrometers. The results showed that microwave-induced plasma expansion led to enhanced emission signals of Gd I, Zr I, Fe I, Ce I, and Ce II. No self-absorption of Gd emissions was evident from the detection limit calibration graphs. Moreover, microwave irradiation decreased the standard deviations of the Gd and Ce emissions and lowered the Gd detection limit by 60%.

Interstitial alloying has become an important pillar in tuning and improving the materials properties of high-entropy alloys, e.g., enabling interstitial solid-solution hardening and for tuning the stacking fault energies. In this work we performed ab initio calculations to evaluate the impact of interstitial alloying with nitrogen on the fcc–hcp phase stability for the prototypical CrMnFeCoNi alloy. The N solution energies are broadly distributed and reveal a clear correlation with the local environments. We show that N addition stabilizes the fcc phase of CrMnFeCoNi and increases the stacking fault energy.

Medium and high entropy alloys (MEAs and HEAs) based on 3d transition metals, such as face-centered cubic (fcc) CrCoNi and CrMnFeCoNi alloys, reveal remarkable mechanical properties. The stacking fault energy (SFE) is one of the key ingredients that controls the underlying deformation mechanism and hence the mechanical performance of materials. Previous experiments and simulations have therefore been devoted to determining the SFEs of various MEAs and HEAs. The impact of local chemical environment in the vicinity of the stacking faults is, however, still not fully understood. In this work, we investigate the impact of the compositional fluctuations in the vicinity of stacking faults for two prototype fcc MEAs and HEAs, namely CrCoNi and CrMnFeCoNi by employing first-principles calculations. Depending on the chemical composition close to the stacking fault, the intrinsic SFEs vary in the range of more than 150 mJ/m 2 for both the alloys, which indicates the presence of a strong driving force to promote particular types of chemical segregations towards the intrinsic stacking faults in MEAs and HEAs. Furthermore, the dependence of the intrinsic SFEs on local chemical fluctuations reveals a highly non-linear behavior, resulting in a non-trivial interplay of local chemical fluctuations and SFEs. This sheds new light on the importance of controlling chemical fluctuations via tuning, e.g., the annealing condition to obtain the desired mechanical properties for MEAs and HEAs.