Loss-tailoring single-mode high-power supersymmetric lasers.

Diode lasers with high beam quality and high power have many promising applications. However, high beam quality is always in conflict with high power. In this Letter, we theoretically and experimentally confirm the mode instability property of supersymmetric structures at higher operating currents. Meanwhile, we propose a loss-tailoring diode laser based on a supersymmetric structure, which enables the higher-order lateral modes to obtain higher losses, raises the excitation threshold of the higher-order lateral modes, and achieves a stable fundamental-lateral-mode output at higher current operation. The device obtained a quasi-single-lobe lateral far-field distribution with the full width at half maximum (FWHM) of 7.58° at 350 mA under room temperature, which is a 65% reduction compared to the traditional Fabry-Perot (FP) diode lasers. Moreover, the M2 of 2.181@350 mA has an improvement of about 37% over traditional FP and supersymmetric structure lasers.

Doping profile architecture towards lower loss and higher efficiency for laser diodes.

A doping optimization model towards lower loss and higher efficiency at the target operating current is investigated. This model considers the effect of doping concentration on the series resistance and the internal loss. 780 nm lasers doped with a normal doping profile (Dop_normal) and an optimized doping profile (Dop_optimize) are both designed and fabricated. After doping optimization, the power loss decreased by 17%, the output power of the lasers increased by 26% and the electro-optical conversion efficiency increased by 22%. The model provides significant theoretical guidance for the optimization of the laser doping.

Optimized performance of 905†nm semiconductor lasers by using the high strain quantum well.

We propose and experimentally demonstrate that the lasing power and characteristic temperature (T0) of 905 nm semiconductor lasers can be optimized by use of the high strain quantum well (HSQW). To fix the lasing wavelength around 905 nm, HSQW with a higher ndium (In) content of the InGaAs gain material than that of the commonly used low strain quantum well (LSQW) requires a thickness-reduced quantum well. Thus, the HSQW has the following two advantages: stronger quantum size effects caused by the deep and thin quantum well, and higher compressive strain caused by a high In content of the InGaAs gain material. With the similar epitaxial structure, laser diodes with HSQW have a characteristic temperature T0 of 207 K and can deliver a higher lasing power with less power saturations. The high strain quantum well optimization method can be extended to other laser diodes with a wavelength near 900 nm with low In content InGaAs quantum wells and other similar low-strain gain material systems.

Accurate and efficient machine learning models for predicting hydrogen evolution reaction catalysts based on structural and electronic feature engineering in alloys.

Predictive materials design of high-performance alloy electrocatalysts is a grand challenge in hydrogen production via water electrolysis. The vast combinatorial space of element substitutions in alloy electrocatalysts offers a wealth of candidate materials, but presents a significant challenge in terms of experimental and computational exploration of all possible options. Recent scientific and technological developments in machine learning (ML) have offered a new opportunity to accelerate such electrocatalyst materials design. Herein, by incorporating both the electronic and structural properties of alloys, we are able to construct accurate and efficient ML models and predict high-performance alloy catalysts for the hydrogen evolution reaction (HER). We have identified the light gradient boosting (LGB) algorithm as the best-performed method, with an excellent coefficient of determination (R2) value reaching 0.921 and the corresponding root-mean-square error (RMSE) being 0.224 eV. The average marginal contributions of alloy features towards ΔGH* values are estimated to determine the importance of various features during the prediction processes. Our results indicate that both the electronic properties of constituent elements and the structural adsorption site features play the most critical roles in the ΔGH* prediction. Furthermore, 84 potential alloys with |ΔGH*| values less than 0.1 eV are successfully screened out of 2290 candidates selected from the Material Project (MP) database. It is reasonable to expect that the ML models with structural and electronic feature engineering developed in this work would provide new insights in future electrocatalyst developments for the HER and other heterogeneous reactions.

Electrically driven supersymmetric semiconductor laser arrays with single-lobe far-field patterns.

Semiconductor laser arrays based on the third-order supersymmetric (SUSY) transformation are proposed to increase the mode discrimination between fundamental supermode and high-order supermodes. The distance between the edge waveguide of the main array and that of the superpartners is optimized. Then, the electric field distributions of different modes are also calculated, which show that, except for the fundamental supermode, the high-order supermodes penetrate deeper into the superpartner arrays, which accounts for the increased loss of high-order supermodes. The fabricated third-order SUSY laser array can emit light with a single-lobe far-field pattern under an injection current of 70 mA, which is a promising candidate for optical couplings between lasers and optical elements.

High-efficiency spectral beam combining of an individual laser diode bar with polarization multiplexing.

In this Letter, a new strategy for the spectral beam combining (SBC) of an individual laser diode (LD) bar based on a polarization multiplexing external cavity is proposed and demonstrated. The maximum combining efficiency is up to 95.51%, which leads to an output power of 76.6 W and an electro-optic conversion efficiency of 48.33% under continuous wave operation at a current of 100 A. Compared to the conventional SBC, the combining efficiency, the output power, and the electro-optical conversion efficiency present improvements of 12%, 10W, and 6%, respectively. The results show that this novel SBC method is a prospective technique for increasing the combining efficiency of LD bars.

Curvature effects on the bifunctional oxygen catalytic performance of single atom metal-N-C.

Understanding the fundamental relationship between the structural information of electrocatalysts and their catalytic activities plays a key role in controlling many important electrochemical processes. Recently, single-atom catalysts (SACs) with the so-called MN4 structure, consisting of a central transition metal quadruply bound to four pyridine nitrogen atoms all situated in an extended carbon-based matrix, have attracted intensive scientific attention owing to their exceptional catalytic performance. In this work, we perform the first-principles density functional theory (DFT) calculations to explore the curvature effects of the carbon matrix surfaces on the catalytic activities for two fundamental electrochemical processes, namely, the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Our DFT results suggest that the curved surface structure can weaken the interaction between the metal atom and the N-doped carbon matrix, modify the electronic structure of the metal atom, and thus increase the adsorption strength of the reaction intermediates, resulting in enhanced OER and ORR catalytic activities of MN4 catalysts. More importantly, a prediction model is developed to evaluate the bifunctional catalytic activities of such catalysts based on their directly obtained parameters including the surface curvature of the catalysts, the number of d electrons of the metal element, and the electronegativity of the metal atom and its coordination atoms in MN4 catalysts. This prediction model not only provides some candidates, for example, FeN4, CoN4 and OsN4 for the ORR; CoN4, NiN4, RuN4, RhN4 and IrN4 for the OER; and CoN4, RuN4, IrN4 and OsN4 for the bifunctional ORR and OER, but also reasonably links the structure of catalysts with their catalytic performance, providing new possibilities for the quick design of high-performance catalysts.

Large animal models for the study of tendinopathy.

Tendinopathy has a high incidence in athletes and the aging population. It can cause pain and movement disorders, and is one of the most difficult problems in orthopedics. Animal models of tendinopathy provide potentially efficient and effective means to develop understanding of human tendinopathy and its underlying pathological mechanisms and treatments. The selection of preclinical models is essential to ensure the successful translation of effective and innovative treatments into clinical practice. Large animals can be used in both micro- and macro-level research owing to their similarity to humans in size, structure, and function. This article reviews the application of large animal models in tendinopathy regarding injuries to four tendons: rotator cuff, patellar ligament, Achilles tendon, and flexor tendon. The advantages and disadvantages of studying tendinopathy with large animal models are summarized. It is hoped that, with further development of animal models of tendinopathy, new strategies for the prevention and treatment of tendinopathy in humans will be developed.

A fourteen-component high-entropy alloy@oxide bifunctional electrocatalyst with a record-low ΔE of 0.61 V for highly reversible Zn-air batteries.

Nanostructured high-entropy materials such as alloys, oxides, etc., are attracting extensive attention because of their widely tunable surface electronic structure/catalytic activity through mixing different elements in one system. To further tune the catalytic performance and multifunctionality, the designed fabrication of multicomponent high-entropy nanocomposites such as high-entropy alloy@high-entropy oxides (HEA@HEO) should be very promising. In this work, we design a two-step alloying-dealloying strategy to synthesize ultra-small HEA nanoclusters (∼2 nm) loaded on nanoporous HEO nanowires, and the compositions of both the HEA and HEO can be adjusted separately. To demonstrate this concept, a seven-component HEA (PtPdAuAgCuIrRu) clusters@seven-component HEO (AlNiCoFeCrMoTi)3O4 was prepared, which is highly active for both oxygen evolution and reduction reactions. Our comprehensive experimental results and first-principles density functional theory (DFT) calculations clearly show that better oxygen evolution reaction (OER) performance is obtained by optimizing the composition of the HEO support, and the seven-component HEA nanocluster is much more active for the ORR when compared with pure Pt due to the modified surface electronic structure. Specifically, the high-entropy composite exhibits an OER activity comparable to the best reported value, and the ORR activity exceeded the performance of commercial Pt/C in alkaline solutions with a record-low bifunctional ΔE of 0.61 V in 0.1 M KOH solution. This work shows an important route to prepare complex HEA@HEO nanocomposites with tuned catalytic performance for multifunctional catalysis and energy conversion.

High-brightness and high-efficiency diode laser module based on double wavelength division multiplexing external cavities.

In this Letter, a new, to the best of our knowledge, external cavity structure based on double wavelength division multiplexing external cavities is proposed and demonstrated. The electro-optical conversion efficiency is improved and the brightness of the spectral beam combining diode lasers is enhanced. One wavelength division multiplexing external cavity is placed on the rear-side of the laser emitters to provide the strong optical feedback for wavelength locking and the other wavelength division multiplexing external cavity is placed on the front-side of laser emitters to combine three emitter beams to one beam. A maximum output power of up to 7.5 W is obtained and the brightness of the laser diode is 100 MW cm-2 sr-1 with an electro-optical conversion efficiency of 46.5%. Compared with a standard cavity for spectral beam combining, the use of double wavelength division multiplexing external cavities results in an electro-optical conversion efficiency improvement of 6.5%. The whole structure provides a new technology to achieve high-brightness and high electro-optical conversion efficiency for a laser diode source.

High-power laser diode at 9xx nm with 81.10% efficiency.

In this study, a low-resistance, low-loss, continuously gradual composition extreme double asymmetric (CGC-EDAS) epitaxial structure is designed to improve efficiency. The structure and facet reflectivity of the broad area (BA) lasers are optimized to maximize the power conversion efficiency (PCE). In the experiment, the peak PCE of 75.36% is measured at 25°C. At 0°C, a peak PCE of 81.10% is measured and the PCE can still reach 77.84% at an output power of 17.10 W, which, to the best of our knowledge, is the highest value to date for any BA lasers.

Electrically injected supersymmetric semiconductor lasers with narrow vertical divergence angle.

Electrically injected supersymmetric (SUSY) semiconductor lasers are proposed and fabricated. Two successive SUSY transformations are applied to the main array arranged along the direction of epitaxial growth, which can remove the propagation constants of the fundamental mode and the leaky mode of the main array from the superpartner while keeping those of other high-order modes. The SUSY laser possesses an excellent mode discrimination and favors the lasing of the fundamental mode. The fabricated SUSY laser can emit light with a single-lobe vertical far-field pattern with the full width at half maximum of 16.87° under an injection current of 1.4 A.

High-power tunable dual-wavelength diode laser with a composite external cavity.

A high-power tunable dual-wavelength composite external cavity architecture obtained by means of a holographic grating and a volume Bragg grating is proposed and demonstrated. The tunable frequency difference of the dual-wavelength output is from 0.41 THz to 3.89 THz. We obtain an output power of 2.1 W when the frequency difference is 1.86 THz. The side-mode suppression ratio of more than 29 dB is suppressed over the entire tunable dual-wavelength output range. The two corresponding wavelengths of the dual-wavelength output basically maintain the same intensity with the smallest power difference of only 0.10%.

Exploiting the Synergistic Electronic Interaction between Pt-Skin Wrapped Intermetallic PtCo Nanoparticles and Co-N-C Support for Efficient ORR/EOR Electrocatalysis in a Direct Ethanol Fuel Cell.

The development of low-Pt catalysts with high activity and durability is critical for fuel cells. Here, Pt-skin wrapped sub-5 nm PtCo intermetallic nanoparticles are successfully mounted on single atom Co-N-C support by exploiting the barrier effect of Co-anchor. According to a collaborative experimental and computational investigation, the increased oxygen reduction reaction activity of PtCo/Co-N-C arises from the direct electron transfer from PtCo to Co-N-C, and the resulting optimal d-band center of Pt. Owing to such unique electronic structure interaction and synergistic effect, the specific and mass activities of PtCo/Co-N-C are up to 4.20 mA cm-2 and 2.71 A mgPt-1 , respectively, with barely degraded stability after 40 000 CV cycles. The PtCo/Co-N-C also exhibits outstanding activity as an ethanol electrocatalyst. This work shows a new and effective route to boost the overall efficiency of direct ethanol fuel cells in acidic media by integrating intermetallic low-Pt alloys and single atom carbon support.

The Differential Expression of CD47 may be Related to the Pathogenesis From Myelodysplastic Syndromes to Acute Myeloid Leukemia.

Myelodysplastic syndrome (MDS) can lead to the development of peripheral blood cytopenia and abnormal cell morphology. MDS has the potential to evolve into AML and can lead to reduced survival. CD47, a member of the immunoglobulin family, is one molecule that is overexpressed in a variety of cancer cells and is associated with clinical features and poor prognosis in a variety of malignancies. In this study, we analyzed the expression and function of CD47 in MDS and AML, and further analyzed its role in other tumors. Our analysis revealed significantly low CD47 expression in MDS and significantly high expression in AML. Further analysis of the function or pathway of CD47 from different perspectives identified a relationship to the immune response, cell growth, and other related functions or pathways. The relationship between CD47 and other tumors was analyzed from four aspects: DNA methyltransferase, TMB, MSI, and tumor cell stemness. Changes in gene expression levels have a known association with aberrant DNA methylation, and this methylation is the main mechanism of tumor suppressor gene silencing and clonal variation during the evolution of MDS to AML. Taken together, our findings support the hypothesis that the differential expression of CD47 might be related to the transformation of MDS to AML.

Preparation and Evaluation of Liposomes and Niosomes Containing Total Ginsenosides for Anti-Photoaging Therapy.

Ginsenosides are the principal bioactive compounds of ginseng. Total ginsenosides (GS) contain a variety of saponin monomers, which have potent anti-photoaging activity and improve the skin barrier function. To enhance the efficiency of GS transdermal absorption, GS liposomes (GSLs) and GS niosomes (GSNs) were formulated as delivery vehicles. Based on the clarified and optimized formulation process, GSL and GSN were prepared. The structure, cumulative transmittance, skin retention, total transmittance, and bioactivity of GSLs and GSNs were characterized. GSL and GSN were shown to inhibit lipid peroxidation and increase the contents of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in human keratinocytes (HaCaTs). In addition, HaCAT cell migration, proliferation, and GS cellular uptake were significantly increased. The therapeutic effects of GSL and GSN were also evaluated in a rat model of photoaging. Histopathological changes were assessed in rat skin treated with GSL, GSN, or GS by hematoxylin-eosin (H&E) and aldehyde fuchsine staining. Malondialdehyde (MDA), SOD, GSH-Px, matrix metalloproteinases (MMPs), interleukin-6 (IL-6), interleukin-1ß (IL-1ß), and tumor necrosis factor-α (TNF-α) expression levels were determined. Results indicated that the optimal formulation of GSL used soybean lecithin (SPC) as the phospholipid, with a lipid-drug ratio of 1:0.4 and a phospholipid-cholesterol ratio of 1:3.5. The optimal temperature for the preparation process of GSN by ethanol injection was 65°C, with a ratio of the organic phase to aqueous phase of 1:9. It was demonstrated that the cumulative release rate, skin retention rate, and total transmission rate of GSL-7 at 24 h were higher than those of GSN-4 and GS. GSL-7 significantly inhibited skin lipid peroxidation caused by ultraviolet (UV) radiation. In addition, GSL-7 reduced the contents of MMPs and inflammatory cytokines in skin tissue. In conclusion, GSL-7 may reduce skin aging caused by UV radiation and contribute to skin tissue repair.

Theoretically Revealed and Experimentally Demonstrated Synergistic Electronic Interaction of CoFe Dual-Metal Sites on N-doped Carbon for Boosting Both Oxygen Reduction and Evolution Reactions.

Heteronuclear double-atom catalysts, unlike single atom catalysts, may change the charge density of active metal sites by introducing another metal single atom, thereby modifying the adsorption energies of reaction intermediates and increasing the catalytic activities. First, density functional theory calculations are used to figure out the best combination by modeling two transition-metal atoms from Fe, Co, and Ni onto N-doped graphene. Generally, Fe and Co sites are highly active for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), respectively. The combination of Co and Fe to form CoFe-N-C not only further improves the Fe's ORR and Co's OER activities but also greatly enhances the Co site's ORR and Fe site's OER activities. Then, we synthesize the CoFe-N-C by a two-step pyrolysis process and find that the CoFe-N-C exhibits exceptional ORR and OER electrocatalytic activities in alkaline media, significantly superior to Fe-N-C and Co-N-C and even commercial catalysts.

Nanotechnology in cervical cancer immunotherapy: Therapeutic vaccines and adoptive cell therapy.

Immunotherapy is an emerging method for the treatment of cervical cancer and is more effective than surgery and radiotherapy, especially for recurrent cervical cancer. However, immunotherapy is limited by adverse effects in clinical practice. In recent years, nanotechnology has been widely used for tumor diagnosis, drug delivery, and targeted therapy. In the setting of cervical cancer, nanotechnology can be used to actively or passively target immunotherapeutic agents to tumor sites, thereby enhancing local drug delivery, reducing drug adverse effects, achieving immunomodulation, improving the tumor immune microenvironment, and optimizing treatment efficacy. In this review, we highlight the current status of therapeutic vaccines and adoptive cell therapy in cervical cancer immunotherapy, as well as the application of lipid carriers, polymeric nanoparticles, inorganic nanoparticles, and exosomes in this context.

Amelioratory Effect of Melatonin on Cognition Dysfunction Induced by Sevoflurane Anesthesia in Aged Mice.

Background: Postoperative cognitive dysfunction (POCD) can be described as a clinical phenomenon characterized by cognitive impairment in patients, particularly elderly patients, after anesthesia and surgery. Researchers have focused on the probable effect of general anesthesia drugs on cognitive functioning status in older adults. Melatonin is an indole-type neuroendocrine hormone with broad biological activity and potent anti-inflammatory, anti-apoptotic, and neuroprotective effects. This study investigated the effects of melatonin on cognitive behavior in aged mice anesthetized with sevoflurane. In addition, melatonin's molecular mechanism was determined. Objectives: This study aimed to investigate the mechanisms of melatonin against sevoflurane-induced neurotoxicity. Methods: A total of 94 aged C57BL/6J mice were categorized into different groups, namely control (control + melatonin (10 mg/kg)), sevoflurane (sevoflurane + melatonin (10 mg/kg)), sevoflurane + melatonin (10 mg/kg) + phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) inhibitor LY294002 (30 mg/kg), and sevoflurane + melatonin (10 mg/kg) + mammalian target of rapamycin (mTOR) inhibitor (10 mg/kg). The open field and Morris water maze tests were utilized to assess the neuroprotective effects of melatonin on sevoflurane-induced cognitive impairment in aged mice. The expression levels of the apoptosis-linked proteins, PI3K/Akt/mTOR signaling pathway, and pro-inflammatory cytokines in the brain's hippocampus region were determined using the Western blotting technique. The apoptosis of the hippocampal neurons was observed using the hematoxylin and eosin staining technique. Results: Neurological deficits in aged, sevoflurane-exposed mice were significantly decreased after melatonin treatment. Mechanistically, melatonin treatment restored sevoflurane-induced down-regulated PI3K/Akt/mTOR expression and significantly attenuated sevoflurane-induced apoptotic cells and neuroinflammation. Conclusions: The findings of this study have highlighted the neuroprotective effect of melatonin on sevoflurane-induced cognitive impairment via regulating the PI3K/Akt/mTOR pathway, which might be effective in the clinical treatment of elderly patients with anesthesia-induced POCD.

Electronic Interaction between In Situ Formed RuO2 Clusters and a Nanoporous Zn3V3O8 Support and Its Use in the Oxygen Evolution Reaction.

The catalytic activity and durability of RuO2 clusters toward the oxygen evolution reaction (OER) are strongly associated with their support; however, how the electronic interaction would enhance the catalytic performance is still not quite clear. Herein, hierarchical nanoporous and single-crystal Zn3V3O8 nanosheets are adopted to anchor in situ formed RuO2 clusters. X-ray photoelectron analysis reveals significant binding energy changes of both Ru and V due to the creation of strong Ru-O-V bonding interaction, which would lead to the reconstruction of the electronic structure of the Zn3V3O8 matrix and RuO2 clusters. The ultrastrong electronic interaction also results in superior OER activity, indicated by a small overpotential at 10 mA cm-2 (228 mV) and a shallow Tafel slope of 46 mV dec-1. First-principles simulation further reveals the synergistic effect derived from the unique RuO2@Zn3V3O8 couple, which effectively regulates the electronic structure for the OER process. In addition, the created interfacial chemical bond and the confined microporous structure of the Zn3V3O8 substrate could prevent the RuO2 clusters from detachment and aggregation, making the nanocomposite a promising long-term stable OER electrocatalyst.