Active Medium Research Articles (Page 1)

All-plastic thin-film organic lasers, in which all thelayers comprisingthe device (active medium, resonator and substrate) are of polymericnature, are very interesting because they offer the possibility totune the emission laser wavelength through mechanical deformation(bending). Here, we report all-plastic distributed feedback (DFB)lasers based on top-layer dichromated gelatin resonators (one-dimensionalgratings), active layers of polystyrene doped with perylene orangeand substrates of cellulose acetate (CA), showing a successful laserperformance, comparable to devices based on fused silica substrates.Remarkably, the emission wavelength of the prepared lasers can betuned by approximately 10 nm through mechanical deformation (bending)thanks to the polymeric nature of all the layers involved in the device.This tuning is primarily due to changes in the grating period, whilethe layer thickness remains constant. The potential of the devicesfor refractive index sensing is also demonstrated. These findingshighlight the potential of flexible top-layer resonator DFB lasersfor applications requiring adjustable emission wavelengths, such asportable or adaptive optical systems. Additionally, the use of CAsubstrates and simple fabrication processes make these devices costeffective and easy to produce, opening the door to scalable and low-costproduction for various optical applications.

Calculation of the Fresnel coefficients and conservation of power equations at the interface between two mediums require modifications when the mediums are complex. The Fresnel equations and new conservation equations were derived for both transverse electric and transverse magnetic polarizations that account for complex permittivity and complex permeability. The derived equations work for any combination of signs for the real and imaginary parts of permittivity and permeability to accurately handle active and passive mediums, positive and negative refractive indices, and positive and negative impedances. The results are verified, and a comprehensive set of benchmarking examples is provided for different combinations of complex constitutive parameters. Consideration of general complex constitutive parameters in the formulation is important for metrology and simulating metamaterials because it has not been considered anywhere in the literature.

Formation time optimization and evaluation of nanoporous GaN as an optically active medium for device applications

BACKGROUNDResearch has been increasingly conducted on the connection between mesenchymal stem cell (MSC)-conditioned medium (MSC-CM) and aging. However, most studies have focused on adipose-derived MSC-CM (ADMSC-CM), resulting in a research bias. We hypothesized that umbilical cord-derived MSCs, being younger than adipose-derived MSCs, would be more suitable for overcoming aging-related processes.AIMTo assess the efficacy and safety of umbilical cord-derived MSC-CM (UCMSC-CM) for preventing and treating skin aging.METHODSIn vitro and in vivo studies were conducted to compare UCMSC-CM with ADMSC-CM, the most studied active aging-preventive conditioned medium to date. Additionally, the most effective delivery method of UCMSC-CM for aged skin was identified.RESULTSUCMSC-CM had a higher content of effective factors, stimulated higher proliferation of fibroblasts, and strongly inhibited melanin production in B16F1 cells. In aged mice, UCMSC-CM application increased skin thickness, the number of Ki-67-positive cells, and the area of collagen deposition. UCMSC-CM was more effective than ADMSC-CM in preventing and treating skin aging. Additionally, a safety evaluation of UCMSC-CM performed in various animal models indicated that it was safe even when used directly on the skin.CONCLUSIONUCMSC-CM is effective and safe for preventing and treating skin aging.

ABSTRACT Amid accelerating urbanisation, the Confucian courtyard is often treated as relic rather than sophisticated vehicle of philosophical expression. This study reevaluates the courtyard sequence of the Confucius Mansion in Qufu to elucidate the interconnection of space, ritual, and environment within Confucian perspective, and to assess the significance of that integration for modern architecture. The research employs archival materials, on-site observation, visual mapping, and interviews with experts and building caretaker, adhering to a narrative-based qualitative approach that connects architectural form to cultural practice. Analysis shows that the mansion’s nine successive courts translate the abstract principles of confucianism alignment into an intelligible spatial order; that the courtyards act as climatic regulators and social condensers whose dimensions, planting and paving negotiate sunlight, monsoon winds and collective routines and their graded permeability produces a hierarchy of public, familial and ceremonial zones which materially encode Confucian ethics of kinship and governance. These findings demonstrate the courtyard is not static backdrop but active medium through which Confucianism orchestrates daily life and environmental adaptation. By articulating the mechanisms, rather than merely the symbols, of this relationship, the study contributes transferable framework for integrating cultural narrative, ecological performance and social structure in the future architectural and urban design.

Surface-emitting lasers featuring optical bound states in the continuum (BICs) have recently emerged as a promising alternative to vertical cavity surface-emitting lasers. However, structural damage caused by top-down fabrication processes remains as a major obstacle that limits device performance. Here, we overcome this bottleneck by demonstrating surface-emitting quasi-BIC lasers fabricated with a bottom-up, etching-free process. We epitaxially grow arrays of crystal phase–engineered InP nanosheets with atomically smooth sidewalls as both the laser active medium and a symmetry-broken quasi-BIC cavity, strategically optimizing coupling between spontaneous emission and the lasing mode. Furthermore, we leverage the dipole selection rule associated with the wurtzite crystal structure of the nanosheets for side mode suppression, achieving single-mode lasing at room temperature with lasing threshold as low as 14 μJ cm−2 pulse−1. Optimal light-cavity coupling is evidenced by spontaneous emission factors as high as 0.8, showcasing the potential of bottom-up BIC lasers in realizing near-thresholdless lasing at room temperature.

Impact of energy activation, thermal radiation, and porous medium on advection–diffusion transport of heat and mass in multi-nano-Casson fluid

BackgroundIn sepsis, oxidative stress (OS) triggers essential adaptive responses and emerging OS-related biomarkers show potential for enhancing sepsis diagnosis and therapy.MethodologyIn this study, we used single-cell datasets and the OS gene set to identify immune cell types with the highest oxidative activity across different sepsis states. Differential expression genes (DEG) between “high state” cells and “low state” cells were screened. High-dimensional weighted gene co-expression network analysis (hdWGCNA), combined with multiple machine learning methods, was used for the selection of hub genes. Expressions of hub genes were then validated. Cell–cell communication and transcription factor analysis were performed later. Real-time quantitative reverse transcription (qRT-PCR) and Western blotting validated expression of LILRA5 in both the cecal ligation and puncture (CLP) model and the lipopolysaccharide-induced sepsis model. Reactive oxygen species (ROS) levels were also detected in THP-1 cells after silencing LILRA5.ResultsIn the early stages of sepsis, oxidative activity reaches its peak, with macrophages displaying the highest OS among all cell types. Through the application of the “Quartile method”, all cells were clustered into three states based on OS activity (low, medium, and high). LILRA5, MGST1, PLBD1, and S100A9 were selected as hub genes and significantly upregulated in sepsis. LILRA5 was predominantly expressed in macrophages and was highly expressed in the early stage of macrophage. Specifically, LILRA5+ macrophages exhibit the strongest OS. LILRA5 showed a higher expression in both mouse sepsis models and the THP-1 cell after lipopolysaccharide stimulation. Silencing LILRA5 resulted in a significant reduction of ROS in THP-1 cells.ConclusionIn conclusion, our study has mapped the landscape of OS dynamics in sepsis and found that LILRA5+ macrophages in the early stage of sepsis exhibit the highest OS. LILRA5 emerges as a promising gene for modulating macrophage-mediated OS in sepsis.

Investigation of laminar flows of a chemically active gas-dust medium in a circular tube

The emergence of photoelectric memristors has opened up new opportunities for the research community to realize the neuro-synaptic functionalities of photoelectric systems. Neuromorphic photoelectric memristors (NPMs) can directly respond to non-contact photonic signals while possessing the desirable features of high bandwidth, zero latency, and low crosstalk. With their capability to integrate the sensing, memory, and computing features, they can mimic the human vision system. Here, we propose a perovskite oxide (ABO3)-based NPM, where the active medium is comprised of oxygen rich and oxygen deficient layers of barium strontium titanate. Along with the analog-type resistive switching behavior, the device current modulation also enables the imitation of long term-potentiation/depression behaviors of the human brain. The designed convolutional neural network model achieves high accuracy even when tested with the damaged (noisy) face images of the Olivetti Research Laboratory dataset. The photo-excitation and photo-inhibition phenomena of NPM are observed under 405 and 633 nm illumination, respectively, and further utilized to realize the spike-intensity, spike-width, spike-rate, and spike-number dependent synaptic plasticity behaviors. These findings significantly inspire future research in the field of perovskite oxide based transparent photoelectric synaptic resistive switching memory devices.

How proteins transduce environmental signals into mechanical motion remains a central question in biology. This study tests the hypothesis that blue light activation of AsLOV2 gives rise to concerted water movement that induce protein conformational extensions. Using electron and nuclear magnetic resonance spectroscopy, along with atomistic molecular dynamics simulations at high pressure, we find that activation, whether initiated by blue light or high pressure, is accompanied by selective expulsion of low-entropy, tetrahedrally coordinated “wrap” water from hydrophobic regions of the protein. These findings suggest that interfacial water serves as functional constituents to help reshape the protein’s free energy landscape during activation. Our study highlights hydration water as an active medium with the capacity to drive long-range conformational changes underlying protein mechanics and offers a new conceptual understanding for engineering externally controllable protein actuators for biomedical studies to smart materials.

ABSTRACT Extant research in medical sociology has highlighted the symbolic authority of the white coat (or lab coat) in shaping clinical power and patient trust. In parallel, costume studies scholarship has emphasized how costumes act as agents that perform, respond, and critique. This article brings these perspectives into dialogue through an analysis of the Mandarin-language TV documentary Life Matters (2019), a widely viewed series that follows physicians working in high-pressure hospitals in Shanghai. Applying a costume studies lens to this series, this article challenges dominant portrayals of medical professionals that routinely conflate clinical detachment with idealized heroism. By tracing how the white coat is worn, handled, and framed onscreen, this article reveals the role of the white coat in negotiating vulnerability, labour, and institutional identity. Ultimately, the article reframes the white coat as an active and affective medium through which physicians perform, contest, and reconfigure medical identity.

We experimentally validate the use of slow light dispersion engineering in active line-defect photonic crystal cavities to generate regular combs of modes around a wavelength of 1.55 µm. Our far-field and near-field optical spectroscopy measurements highlight that 11 frequency equidistant modes could be sustained over a bandwidth of 8.5 nm in a 45 µm-long cavity. The unprecedented use of slow light dispersion engineering with nearly constant group velocities between c/30 and c/40 in an active medium enables an 8-fold cavity length reduction compared to standard strip waveguides. We demonstrate that the equidistant comb of modes is related to the underlying dispersion-engineered slow-light guided mode, and we analyze its robustness against structural fluctuations due to fabrication. This paves the way towards the creation of compact and integrated mode-locked lasers.

While Lavandula angustifolia (lavender) and Melaleuca alternifolia (tea tree) are widely utilized in diverse products for their rich bioactive secondary metabolites, emerging evidence now fules concerns about their potential endocrine-disrupting activities. This study aimed to investigate the endocrine-disrupting potential of selected secondary metabolites from lavender and tea tree via an in silico molecular docking approach. Molecular interactions were evaluated against 18 human endrocine receptors using Endocrine Disruptome in silico tools and binding affinities were analyzed to assess potential toxicity. Docking analysis revealed that all lavender anda tea tree secondary metabolites have the potential to interact as androgen receptor antagonists, exhibiting minor, medium, and high probabilities of such activity. Additionally, more than 20% of lavender secondary metabolites and 10% of tea tree secondary metabolites are predicted to be capable of binding to the mineralocorticoid receptor, as well as thyroid receptors alpha and beta. These findings suggest a plausible mechanism by which these phytochemicals could exert endocrine-disruptor effects. In conclusion, the study provides preliminary computational evidence supporting the hypothesis that certain lavender and tea tree sceondary metabolites may act as endocrine-disrupting agents. Further in vitro and in vivo studies are warranted to assess their toxicological implications for long-term human exposure.

Optimization of rare-earth (RE) doped devices for laser applications necessitates a combination of precision material engineering and advanced performance enhancement strategies. This study presents a novel investigation, to our knowledge, into cluster dynamics in Er-doped glass, utilizing localized CO2 laser heating to simulate the high-temperature conditions typical of glass fabrication processes. Our findings demonstrate that, by a controlled heat exposure, it is possible to influence clustering in Er-doped glass. Minimized clustering leads to a significant improvement in material properties and ultimately device performance. Specifically, we achieved up to 25% increase in the radiative lifetime associated with the 4I13/2 → 4I15/2 radiative transition by exposing samples to elevated temperatures for several minutes. This rapid thermal treatment minimizes dopant mobility in sintered silica glass, thereby reducing cluster formation and improving the homogeneity of the active medium. These results provide a feasible pathway for enhancing the performance of erbium-based optical devices, including lasers and signal amplifiers, and underscore the potential of thermal processing as a versatile tool in photonic material optimization.

We propose and numerically test, to our knowledge, a novel concept for asymmetric vortex beam generation in a degenerate vertical external cavity surface emitting laser (DVECSEL). The method is based on a phase-locking ring array of lasers created inside a degenerate cavity with a binary amplitude mask containing circular holes. The diffraction engineering of the mask profile allows for controlling the complex coupling between the lasers. The asymmetry between different lasers is introduced by varying the hole diameters corresponding to different lasers. Several examples of masks with non-uniform or uniform circular holes are investigated numerically and analytically to assess the impact of non-uniform complex coupling coefficients on the degeneracy between the vortex and anti-vortex steady states of the ring laser arrays. It is found that the in-phase solution always dominates irrespective of non-uniform masks. The only solution to make one particular vortex solution dominant over other possible steady-state solutions consists of imprinting the necessary phase shift among neighboring lasers in the argument of their coupling coefficients. We also investigate the role of the Henry factor inherent to the use of a semiconductor active medium in the probabilities to generate vortex solutions. Analytical calculations are performed to generalize a formula previously reported [ Opt. Express 30, 15648 (2022)OPEXFF1094-408710.1364/OE.456946], for the limiting Henry factor to cover the case of complex couplings.

Abstract This paper presents the improved photovoltaic characteristics of organic solar cells (OSCs) consisting of low band gap (LBG) active medium and a combination of plasmonic nanostructures embedded in the cathode buffer layer (CBL) and on the upper surface of the bottom silver (Ag) layer of the OSCs. A combination of a 2-dimensional (2D) array of plasmonic nanostructures such as Ag nano-discs (Ag-NDs) present in the CBL of the OSC with a 2D array of either Ag nano-rings (Ag-NRs), Ag nano-discs (Ag-NDs), or Ag nano-hemispheres (Ag-HSs) above the bottom Ag layer of the OSCs, was employed for achieving enhanced performance of the OSCs. Finite-difference time-domain (FDTD) simulations were used to analyze the photon absorption (A(λ)), short circuit current density (JSC), and power conversion efficiency (PCE) of OSCs containing the plasmonic nanostructures. The results of our FDTD simulations demonstrate that these bulk heterojunction OSCs containing Ag-NDs arrays in the CBL primarily increase the A(λ) in the 650–900 nm spectral regime. On the other hand, our FDTD simulations also demonstrate that 2D arrays of Ag-NDs in the CBL in a combination with 2D arrays of either Ag-NRs, Ag-NDs, or Ag-HSs at bottom of the cells increase the light trapping in the visible and the NIR spectral region, thereby significantly increasing the JSC and PCE of the proposed OSCs. It is observed that while the inclusion of structures consisting of Ag-NDs array in the CBL in a combination with Ag-HSs array at bottom of the cells lead to enhancements in JSC and PCE of 40.36% and 40.36%, respectively, compared to a planar OSC, these enhancement values are only 32.22% and 32.1%, respectively, when only Ag-NDs are present only in the CBL. Hence, a combined structure of Ag-NDs array in the CBL and Ag nanoparticle array at the bottom of the OSC leads to an enhanced JSC and PCE compared to those in a planar OSC or to those when only the NDs are embedded only in the CBL.

This study examines the laser and its uses in medicine. It refers to light amplification by stimulated emission of radiation (SEER). This is electromagnetic radiation whose photons are equal in frequency and phase, and whose wavelengths interfere constructively, transforming into a light pulse. The history of laser development, which began in the mid-nineteenth century, is also studied. Lasers have evolved and their use in many fields has expanded. The components of the laser, including the active medium, the excited source, and the resonator, are also studied. The conditions for lasing are defined by three points: the presence of the active medium, the achievement of inverse rehabilitation. The laser's operating principle is also studied, which is based on three types of interactions: absorption, stimulated emission, and spontaneous emission. The characteristics of the laser are also studied, as its beam has four characteristics: monochromaticity, coherence, directivity, and brightness. The types of lasers, including solid-state lasers (such as ruby lasers), liquid lasers, chemical lasers, and others, are explained in detail in this research. Lasers have a wide range of practical applications. They are used in medicine, industry, mining, communications, and for measuring distances with extreme precision, among many other fields. In general, lasers are highly advanced and play a significant role in human life because they are linked to human health and medicine. Doctors will be able to use them more widely in the future to treat diseases using lasers.

Abstract Introduction Nowadays, pacemaker (PM) therapy remains associated with considerable peri– and post–procedural complications. Blind puncture of the subclavian vein for PM lead insertion is a routine procedure, but it carries the risk of potentially life–threatening complications, including pneumothorax, arteriovenous fistula, and injury or perforation of the subclavian artery, vein, or left internal mammary artery (LIMA). Case Presentation A 48–year–old woman with no prior cardiovascular history presented to the emergency department with frequent lipothymic episodes and dizziness. ECG revealed a 2:1 atrioventricular block, while transthoracic echocardiogram (TTE) showed normal biventricular function and excluded structural heart disease. After three unsuccessful attempts at left subclavian venous puncture and several lead repositioning attempts due to unstable pacing and sensing thresholds, a dual–chamber pacemaker was implanted. Immediately following the procedure, the patient developed severe hypotension, requiring pharmacological support, with labile stabilization of blood pressure. Chest fluoroscopy indicated hemopneumothorax, while TTE ruled out pericardial effusion. The initial diagnosis was active bleeding, prompting urgent femoral angiography. The angiography revealed active contrast medium extravasation from the proximal segment of the LIMA, leading to a massive hemothorax, with no other active bleeding sources identified (Figure 1). Endovascular repair was performed using two covered stents (2.5 x 23 mm and 3.0 x 13 mm), and contrast injection confirmed occlusion of the arterial hole. Despite this intervention, the patient required chest drain placement and blood transfusions (Figure 2). Due to the high risk of further bleeding and the secondary role of the LIMA, dual–antiplatelet therapy was not initiated. Comment Inadvertent perforation of the LIMA during a blind approach to the subclavian vein for PM implantation is an extremely rare but potentially life–threatening complication. Prompt identification of the bleeding source and immediate intervention are crucial to prevent mediastinal and thoracic hematomas, which can rapidly worsen hemodynamic instability. Covered stent deployment offers a rapid and effective solution, particularly in hemodynamically unstable patients. Endovascular repair should be considered the first option in critical patients, especially when the procedure can be performed by an experienced operator in peripheral interventions.Figure 1 Figure 2

Manufacturing of irregular shapes through force control in incremental sheet forming with active medium