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In order to improve the stability of semiconductor laser fiber coupling efficiency, based on the coupling principle, the optimal parameters for semiconductor laser fiber coupling were simulated to be θ = 45°, r = 3.25 μm, and z = 5.65 μm. By optimizing the structure and position of the lens fiber, it has been experimentally proven that the maximum fiber coupling efficiency of the 980 nm semiconductor laser can reach 87.1%, and the average coupling efficiency can also reach 84%. After temperature cycling and aging experiments, the average coupling efficiency of the device was 81.7%, indicating a decrease in coupling efficiency. At the same time, the effect of fiber stress on the reliability of coupling efficiency was analyzed, and the stability and consistency of the device before and after temperature cycling were explored. In future work, it will be necessary to further optimize the thermal stress caused by UV glue curing and tail pipe soldering, find suitable process parameters, and obtain stable and reliable coupling modules.

It is often assumed that an animal's metabolic rate can be estimated through measuring the whole-organism oxygen consumption rate. However, oxygen consumption alone is unlikely to be a sufficient marker of energy metabolism in many situations. This is due to the inherent variability in the link between oxidation and phosphorylation; that is, the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by mitochondria (P/O ratio). In this article, we describe how the P/O ratio can vary within and among individuals, and in response to a number of environmental parameters, including diet and temperature. As the P/O ratio affects the efficiency of cellular energy production, its variability may have significant consequences for animal performance, such as growth rate and reproductive output. We explore the adaptive significance of such variability and hypothesize that while a reduction in the P/O ratio is energetically costly, it may be associated with advantages in terms of somatic maintenance through reduced production of reactive oxygen species. Finally, we discuss how considering variation in mitochondrial efficiency, together with whole-organism oxygen consumption, can permit a better understanding of the relationship between energy metabolism and life history for studies in evolutionary ecology.

The amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motoneurons death. Mutations in the superoxide dismutase 1 (SOD1) protein have been identified to be related to the disease. Beyond the different altered pathways, the mitochondrial dysfunction is one of the major features that leads to the selective death of motoneurons in ALS. The NSC-34 cell line, overexpressing human SOD1(G93A) mutant protein [NSC-34(G93A)], is considered an optimal in vitro model to study ALS. Here we investigated the energy metabolism in NSC-34(G93A) cells and in particular the effect of the mutated SOD1(G93A) protein on the mitochondrial respiratory capacity (complexes I-IV) by high resolution respirometry (HRR) and cytofluorimetry. We demonstrated that NSC-34(G93A) cells show a reduced mitochondrial oxidative capacity. In particular, we found significant impairment of the complex I-linked oxidative phosphorylation, reduced efficiency of the electron transfer system (ETS) associated with a higher rate of dissipative respiration, and a lower membrane potential. In order to rescue the effect of the mutated SOD1 gene on mitochondria impairment, we evaluated the efficacy of the exosomes, isolated from adipose-derived stem cells, administrated on the NSC-34(G93A) cells. These data show that ASCs-exosomes are able to restore complex I activity, coupling efficiency and mitochondrial membrane potential. Our results improve the knowledge about mitochondrial bioenergetic defects directly associated with the SOD1(G93A) mutation, and prove the efficacy of adipose-derived stem cells exosomes to rescue the function of mitochondria, indicating that these vesicles could represent a valuable approach to target mitochondrial dysfunction in ALS.The amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motoneurons death. Mutations in the superoxide dismutase 1 (SOD1) protein have been identified to be related to the disease. Beyond the different altered pathways, the mitochondrial dysfunction is one of the major features that leads to the selective death of motoneurons in ALS. The NSC-34 cell line, overexpressing human SOD1(G93A) mutant protein [NSC-34(G93A)], is considered an optimal in vitro model to study ALS. Here we investigated the energy metabolism in NSC-34(G93A) cells and in particular the effect of the mutated SOD1(G93A) protein on the mitochondrial respiratory capacity (complexes I-IV) by high resolution respirometry (HRR) and cytofluorimetry. We demonstrated that NSC-34(G93A) cells show a reduced mitochondrial oxidative capacity. In particular, we found significant impairment of the complex I-linked oxidative phosphorylation, reduced efficiency of the electron transfer system (ETS) associated with a higher rate of dissipative respiration, and a lower membrane potential. In order to rescue the effect of the mutated SOD1 gene on mitochondria impairment, we evaluated the efficacy of the exosomes, isolated from adipose-derived stem cells, administrated on the NSC-34(G93A) cells. These data show that ASCs-exosomes are able to restore complex I activity, coupling efficiency and mitochondrial membrane potential. Our results improve the knowledge about mitochondrial bioenergetic defects directly associated with the SOD1(G93A) mutation, and prove the efficacy of adipose-derived stem cells exosomes to rescue the function of mitochondria, indicating that these vesicles could represent a valuable approach to target mitochondrial dysfunction in ALS.

To overcome the efficiency degradation caused by independently designing transmission ratios and evaluating mechanical losses in hybrid electric vehicle drivetrains, this study proposes a unified transmission ratio–efficiency coupled modeling and optimization framework for multi-row planetary gear transmissions. An improved kinematic model based on topological analysis is integrated with a refined multi-source loss model for meshing, bearing, churning, and windage losses. The resulting nonlinear coupled system is solved using a Newton–Raphson method with adaptive step-size regulation. This approach enables the prediction of speed distribution, torque balance, and transmission efficiency under varying operating conditions. An enhanced multi-objective particle swarm optimization (MOPSO) algorithm is then employed to identify high-efficiency zones and to optimize key structural and lubrication parameters. Bench-test verification is conducted through efficiency MAP measurements, thermal endurance tests, and dynamic response evaluations. The results indicate a mean efficiency prediction error of 1.38% and stable thermal and transient behavior. After optimization, the high-efficiency zone coverage increases from 68.5% to 78.6%, and the comprehensive efficiency rises from 92.8% to 95.6%. Overall, the proposed framework provides a computationally efficient and engineering-applicable approach for the systematic design and optimization of planetary gear transmissions.

In optical communication technology, the coupling efficiency (CE) remains a big challenge. The slight misalignment between the fiber and the lens causes light to bounce back from the fiber end, which creates reflected intensity noise (RIN). This research presents a theoretical framework for estimating RIN in the case of laser diode (LD) excitation of triangular index fiber (TIF) through a single-mode upside down tapered cylindrical microlens (UDTCML) on the circular core fiber tip. The analysis takes care of different RIN values based on possible lateral misalignments in case of two wavelengths, 1.3 µm and 1.5 µm, and TIFs with three different V numbers in the coupling system. Using the ABCD matrix formalism, we analytically evaluate the CE when there is a lateral mismatch and thereof RIN as well. It deserves mentioning in this connection that increase of lateral mismatch causes both increase of loss due to RIN and decrease of coupling efficiency as well. The results given are useful for reducing RIN and improving CE. This information will benefit the designers and packagers concerned with optical couplers.

Energy coupling efficiency has an important effect on welding quality in pulsed laser spot welding. In this paper, laser spot welding experiments are conducted on 3 mm AZ31 magnesium alloy using an AC-500 W Nd:YAG pulsed laser welder. Results show that the rectangular pulse (R) energy coupling is the most efficient when peak power is less than or equal to 3 kW, but the energy coupling of ramp-up pulse (R-U) is the most efficient when peak power is greater than 3 kW. When the peak power is 4 kW, the energy coupling efficiency of laser spot welding under R-U pulse is the highest. At this time, the cross-sectional area of welding spot reaches 1.3 mm 2 , peak temperature is 1550 ℃, the metal loss of melting pool is 4.4 mg, the depth-to-width ratio of keyhole is 1.06, and the laser absorptance is 0.9. In addition, a numerical model of velocity field of transient keyhole laser spot welding is established by using ANSYS, and the shape and size of keyhole are calculated during laser spot welding. The mechanism of pulse shaping to improve the energy coupling efficiency of deep-melt laser welding of magnesium alloys is revealed.

To fully utilize the advantages of Si3N4 and Silicon-On-Insulator to achieve a high-efficiency wideband grating coupler, we propose and numerically demonstrate a grating coupler based on Si3N4 and a Silicon-On-Insulator heterogeneous integration platform. A two-dimensional model of the coupler was established and a comprehensive finite difference time domain analysis was conducted. Focusing on coupling efficiency as a primary metric, we examined the impact of factors such as grating period, filling factor, etching depth, and the thicknesses of the SiO2 upper cladding, Si3N4, silicon waveguide, and SiO2 buried oxide layers. The calculations yielded an optimized grating coupler with a coupling efficiency of 81.8% (−0.87 dB) at 1550 nm and a 1-dB bandwidth of 540 nm. The grating can be obtained through a single etching step with a low fabrication complexity. Furthermore, the fabrication tolerances of the grating period and etching depth were studied systematically, and the results indicated a high fabrication tolerance. These findings can offer theoretical and parameter guidance for the design and optimization of high-efficiency and broad-bandwidth grating couplers.

HighlightsSynergistic effect triggers the Ostwald ripening for the downward recrystallization of perovskite to form buried submicrocavities as light output coupler.The simulation suggests the buried submicrocavities can improve the light out-coupling efficiency from 26.8% to 36.2% for near-infrared light.Light-emitting diodes yields peak external quantum efficiency increasing from 17.3% at current density of 114 mA cm−2 to 25.5% at current density of 109 mA cm−2 and a radiance increasing from 109 to 487 W sr−1 m−2 with low rolling-off.Embedding submicrocavities is an effective approach to improve the light out-coupling efficiency (LOCE) for planar perovskite light-emitting diodes (PeLEDs). In this work, we employ phenethylammonium iodide (PEAI) to trigger the Ostwald ripening for the downward recrystallization of perovskite, resulting in spontaneous formation of buried submicrocavities as light output coupler. The simulation suggests the buried submicrocavities can improve the LOCE from 26.8 to 36.2% for near-infrared light. Therefore, PeLED yields peak external quantum efficiency (EQE) increasing from 17.3% at current density of 114 mA cm−2 to 25.5% at current density of 109 mA cm−2 and a radiance increasing from 109 to 487 W sr−1 m−2 with low rolling-off. The turn-on voltage decreased from 1.25 to 1.15 V at 0.1 W sr−1 m−2. Besides, downward recrystallization process slightly reduces the trap density from 8.90 × 1015 to 7.27 × 1015 cm−3. This work provides a self-assembly method to integrate buried output coupler for boosting the performance of PeLEDs.

Using the ABCD matrix framework, we estimate the coupling optics (CO) between a laser diode (LD) and a tapered cylindrical lensed circular core triangular index fiber (TIF). It is essential to note that the coupling optics provide nice performance in the vertical plane, whereas the horizontal plane exhibits inferior results. Taking care of the performance in the vertical plane only, we theoretically predict and assess the coupling efficiency (CE) using ABCD matrix formalism. We provide analytical formulae for coupling efficiencies. The said studies have been carried out for two frequently utilized wavelengths, namely 1.3 and 1.5 µm. In terms of coupling efficiency, the wavelength of 1.5 µm has been identified to be more effective. Our theory addresses the narrow aperture that the cylindrical microlens (CML) provides. The findings indicate the possibility of ensuring improved optical signal transmission by optimizing lens radius and distance of the laser source from the coupler. It will be highly beneficial to the designers and packagers dealing with this kind of coupler.

The fiber mode field overlap integral method is employed to analyze the influencing factors of coupling efficiency, as well as the effects of axial and radial alignment errors on coupling efficiency under different relative apertures of coupling lenses. The results indicate that there exists an optimal relative aperture of the coupling lens that maximizes coupling efficiency; however, at this optimal point, coupling efficiency is more susceptible to radial errors. Regarding axial and radial errors, when the relative aperture of the coupling lens is at its optimal value, the tolerance for alignment errors is minimal. Conversely, when the relative aperture exceeds the optimal value, both coupling efficiency and tolerance for alignment decrease. When the relative aperture is less than the optimal value, the requirement for installation accuracy decreases while the tolerance becomes larger. The trend of the simulation results aligns with the experimental data. This study provides instructive significance regarding the trade-off between coupling efficiency requirements and alignment accuracy in the design of actual polarization-maintaining fiber coupling systems.