Search Results (15,563)

High-resolution short-wave infrared (SWIR) imaging requires photodetectors (PDs) with simultaneously low dark current and high responsivity. To achieve this goal, we demonstrate low-defect bulk germanium-on-insulator (bulk-GeOI) PDs designed for enhanced 1550 nm absorption and suppressed dark current via a resonant cavity and low-defect material platform. Devices were fabricated by direct bonding low-defect bulk Ge and thinning it to ~1300 nm, with an intrinsic layer thickness of only 800 nm. This design avoids epitaxial defects to lower intrinsic dark current while forming a resonant cavity for enhanced responsivity at 1550 nm. Precise doping and Al₂O₃/Si₃N₄ bilayer sidewall passivation were employed. From a design perspective, using low-defect bulk Ge minimizes the defects from epitaxial growth and reduces intrinsic dark current, while thinning the Ge layer enhances the resonant cavity effect to improve 1550 nm responsivity. Experimentally, despite the thin absorbing layer, our devices achieved nA-level dark currents (e.g., 18 nA at −1 V for 10 μm devices) alongside high responsivities. Detailed analysis indicates that this dark current is predominantly attributed to surface and sidewall defects from mesa etching, with minimal contribution from low-defect bulk material defects, validating the effectiveness of the bulk-Ge approach in suppressing intrinsic bulk leakage. Optically, the devices achieved high responsivities of 0.85 A/W (1310 nm) and 0.72 A/W (1550 nm), corresponding to external quantum efficiencies of 80.6% and 57.7%, respectively. This work establishes the bulk-GeOI platform as a promising path toward high-performance SWIR PDs, successfully decoupling high responsivity from bulk leakage and paving the way for future gains through refined surface and interface engineering. Full article

When it comes to active or semi-active suspension, one of many design challenges is the ability to dynamically change the damping rate of a shock absorber. Two fundamental means of accomplishing variable damping are by changing the restriction imposed on the fluid or changing the viscosity of the fluid. One way to change the restriction imposed on the fluid is by using a valve controlled by a solenoid. As more current flows through the solenoid a plunger gets pulled into the center of the coil, which acts against a mechanical spring that pushes it to a default state. There are specific kinds of fluids, such as ferrofluids or magnetorheological fluids, that change their viscosity in the presence of magnetic fields. This paper aims to guide the reader through the design of an electromagnetic damper, how to derive theoretical performance criteria from a semi-active suspension system, and design optimization considerations. The design will test three different coil specifications, including size, wire size, location, applied voltage, and amperage. The experimental evaluation was conducted as a qualitative proof-of-concept to verify the presence of field-dependent viscosity and damping behavior under low-frequency manual excitation. Quantitative performance assessment was performed using analytical and numerical modeling to determine whether the proposed design satisfies semi-active suspension damping requirements. Full article

Fluopyram is a widely used nematicide with a growing number of varieties registered both domestically and overseas. However, its absorption, transportation, and metabolism behaviors in plants have not been fully elucidated, thus hindering comprehensive assessment of the risks associated with its use. This study investigated the plant uptake, distribution, and metabolic behavior of fluopyram through 168 h hydroponic experiments. Fluopyram was easily absorbed by the roots of the tested crops, and almost 90.5% and 70.9% of fluopyram was transformed in cucumber and tomato, respectively, leading to the tentative identification of 16 metabolites using Quadrupole Time-of-Flight mass spectrometry. The metabolic reactions involved were hydroxylation, hydroxylation–dechlorination, dehydrogenation, dechlorination, and glucuronidation conjugation. Most metabolites were detected in leaves, suggesting that they have considerable potential to accumulate in the upper parts, even the edible parts. Model prediction indicated that fluopyram and high-toxicity metabolites (M430A, M412C) pose significant risks to aquatic ecosystems across trophic levels, while M574A and M574B showed reduced toxicity due to glucuronidation conjugation. These findings deepen our understanding of the behavioral characteristics of fluopyram within plants, and serve as an important reference for comprehensively assessing its risks. Full article

Postharvest fungal decay is a primary cause of losses in blueberries, motivating the development of sustainable alternatives to conventional fungicides. This study aimed to develop and evaluate antifungal active films based on polylactic acid (PLA) enriched with citronella essential oil to control phytopathogenic fungi associated with blueberry spoilage. PLA films containing 7.5, 10, and 12.5% (w/w) citronella essential oil were produced by solvent casting and characterized for water vapor transmission rate and nanomechanical properties. The antifungal effect was tested in vitro against Epicoccum nigrum, Alternaria alternata, and Cladosporium herbarum. Active films exhibited concentration-dependent antifungal activity, with C. herbarum being the most sensitive fungus. The incorporation of citronella essential oil did not significantly alter the water vapor barrier properties of PLA, while mechanical analysis revealed a reduction in elastic modulus only at the highest concentration. The antifungal mechanism was elucidated using scanning electron microscopy, fatty acid profiling, absorbance at 260 nm, and conductivity measurements. The results indicate that the released citronella essential oil induced membrane disruption and morphological damage in fungal hyphae, with species-specific responses. Overall, PLA–citronella essential oil films represent a promising biodegradable packaging solution to control postharvest blueberry losses. Full article

Regional financial integration in East Africa remains shallow, yet contagion risks persist due to market fragility and illiquidity. Using daily data from 2014 to 2025 from the Nairobi Securities Exchange (NSE), Dar es Salaam Stock Exchange (DSE), Rwanda Stock Exchange (RSE), and Uganda Securities Exchange (USE), this study examines volatility spillovers, dynamic connectedness, and contagion through autoregressive moving average – generalised autoregressive conditional heteroscedasticity (ARMA–GARCH) diagnostics, asymmetric dynamic conditional correlation (ADCC–GARCH) correlations, and the Diebold–Yilmaz framework. The results show weak spillovers and limited connectedness in tranquil periods, reflecting persistent segmentation. However, systemic stress triggers abnormal surges in correlations and connectedness, consistent with contagion as a temporary amplification of cross-market linkages. The NSE emerges as the dominant transmitter, driven by liquidity and cross-listings, while the USE acts as a passive absorber. The RSE and DSE alternate between marginal transmitters and receivers depending on conditions. These findings support the Adaptive Market and Financial Instability Hypotheses, underscoring the need for harmonised regulation, liquidity reforms, and adaptive risk management to bolster resilience. Full article

This study investigated the aroma characteristics of three grades of raw tea leaves and their corresponding jasmine tea products from Guangxi, China. Aromatic profiles of jasmine tea varieties were analysed using two-dimensional gas chromatography-olfactory-mass spectrometry (GC×GC-O-MS), stir bar sorptive extraction (SBSE), and descriptive sensory evaluation. Chemometric methods were applied to compare sensory scores with instrumental data. Volatile compound concentrations and relative odour activity values (r-OAVs) were calculated. The results indicated significant differences in base tea leaf quality: high-grade tea leaf G1 exhibited pure, sweet characteristics, serving as an excellent aroma-absorbing carrier. The scenting process significantly imparted jasmine fragrance to the finished product, although its efficacy was constrained by tea leaf grade. GH1 finished tea exhibited a fresh, vibrant, and rich aroma with a sweet, mellow fragrance and high floral integration. In contrast, GH3, due to its inferior base material quality, yielded a weak aroma after scenting with limited quality improvement. The initial quality of the tea base is the fundamental determinant of the upper limit of the finished jasmine tea’s sensory quality, while the scenting process is the core means of shaping its signature floral aroma. The combination of high-quality tea leaves and precise scenting techniques is essential for developing the fresh, vibrant, and rich flavour profile of premium jasmine tea. This study reveals that the flavour formation of jasmine tea originates from the foundational quality of the tea leaves, providing a theoretical basis for monitoring the aroma quality of jasmine tea produced from different grades of tea leaves. Full article

Urbanisation is a major driver of ecological change, altering the composition and functioning of ecosystems through land use conversion, pollution, and environmental fragmentation. Although some authors reported that air pollutants could be absorbed and detoxified by the endophytic microbiome of urban trees, the specific mechanisms by which urban air pollution shapes the endophytic microbiome and, consequently, the trees’ capacity for pollutant degradation, remain largely unexplored. The aim of the present study was to: (1) analyse the structure of endophytic bacteriome of the phyllosphere of three widely planted ornamental tree species—Tilia tomentosa, Fraxinus excelsior, and Pinus nigra, growing at four locations within the city of Plovdiv, Bulgaria, with different anthropogenic load; and (2) assess the effects of host species and urban environmental exposure on bacteriome diversity, taxonomic composition, and functional capacity. Functional profiling based on 16S rRNA gene sequencing revealed enrichment of the metabolic pathways associated with nitrogen cycling, carbon metabolism, and hydrocarbon degradation, particularly in samples originating from more urbanised or polluted locations. These predicted functional traits suggest that endophytic bacteria may actively contribute to detoxification processes within plant tissues. Tilia tomentosa and Fraxinus excelsior were enriched in nitrogen and carbon cycling pathways, including denitrification, methanol oxidation, and methanotrophy—functions associated with oxidative stress mitigation and nutrient regulation. In contrast, Pinus nigra showed higher relative abundance of chemoheterotrophy, ureolysis, and sulphur respiration, indicating a more conservative and stress-tolerant microbiome. Although the study involved only one settlement, these results suggest that endophytic communities may contribute to urban tree sustainability by supporting ecosystem functions under stress conditions. By integrating microbial ecology with urban environmental assessment, this research provides new insights into the adaptive potential of endophytic microbiota in urban forests and highlights their importance in the sustainable management of green infrastructure through microbiome-informed strategies. Full article

We have demonstrated a high-power, polarization-maintaining all-fiber amplifier operating at a repetition rate of 1 MHz. The seed laser is a Semiconductor Saturable Absorber Mirror (SESAM) mode-locked oscillator with an 18.1 nm full width in half-maximum (FWHM) spectrum. The pulse duration is stretched to 1.1 ns using temperature-controlled chirped fiber Bragg gratings (TCFBGs) and subsequently amplified in a 40 µm core Yb-doped fiber, achieving a maximum output power of 37 W. The amplified laser exhibits excellent beam quality with an M² factor of 1.04. The pulse duration is compressed to 207 fs in a single-grating compressor with 86% efficiency, yielding an average power of 32 W, a pulse energy of 32 µJ, and a peak power of 154.6 MW. This high-power all-fiber femtosecond laser is a promising source for scientific and industrial applications. Full article

Heavy metal contamination in coastal and ballast waters motivates the development of low-cost, environmentally compatible filtration media. This study investigates how 6 MeV electron-beam irradiation (0–100 Gy) modifies the surface electronic and chemical properties of quartz-rich Baltic Sea sands collected from four Latvian coastal locations (Riga, Salacgriva, Ventspils, and Liepaja), and how these modifications affect chromium removal from aqueous K₂CrO₄ solutions. Surface electronic behavior was evaluated by near-threshold photoelectron emission spectroscopy (PEES), including electron work function (EWF) and analysis of differentiated spectra, while irradiation-associated changes in near-surface chemistry were assessed by X-ray photoelectron spectroscopy (XPS). Filtration performance was quantified by UV–Vis absorbance of filtrates. Across all sands, EWF values remained within ~4.7–4.9 eV; however, irradiation effects were strongly site-dependent. Liepaja sand exhibited the most pronounced response, including an EWF increase at 40 Gy, a shift in the differentiated PEES peak toward higher photon energies at ≥40 Gy, and the largest integrated photoemission intensity across doses, consistent with an elevated relative photoemission response under identical acquisition and processing conditions. XPS trends for Liepaja were consistent with irradiation-driven modification of the Si–O environment, while other sites showed comparatively minor changes. Filtration results mirrored these observations: Liepaja sand demonstrated the clearest dose-dependent enhancement in chromium removal with a non-monotonic feature at 40 Gy, consistent with competing formation and transformation of oxygen-related surface-reactive centers. Overall, the results show that electron-beam irradiation can modestly enhance Cr(VI) removal by natural quartz sands, with the magnitude governed by site-specific near-surface electronic structure and its dose-dependent evolution. Full article

Cannabinoids are of considerable current interest for use in pharmaceutical and non-medical consumer products. While there have been significant efforts to understand their chemical stability under ambient conditions, only sparse attention has been paid to characterising their photostability. Here, we present UVA (365 nm) and UVB (280 nm) photolysis measurements of eight representative cannabinoids, including natural compounds (THC, CBD, THCA, CBDA), metabolites (THC-COOH, THC-OH), and synthetic analogues (JWH-018, MDMB-FUBINACA). Measurements were performed using a novel online-electrospray mass spectrometry (MS) approach, where online photolysis of cannabinoid solutions was conducted with laser light-emitting diodes. MS detection was used to monitor precursor compound decay and photoproduct formation. Complementary results obtained via UV–Vis spectroscopy of photolysed cannabinoid solutions are also presented. For THC, CBD, THC-COOH, THC-OH, THCA and CBDA, significant photodegradation was observed with 280 nm photolysis, both through the appearance of photoproducts detected by MS and via time-dependent changes in the solution UV–Vis absorption profiles. In contrast, the synthetic cannabinoids (JWH-018 and MDMB-FUBINACA) showed negligible degradation with UVB photolysis, consistent with their relatively low absorbance propensity through the mid-UV region. No significant photodegradation was observed for UVA (365 nm) photolysis of any of the cannabinoids. The results presented here constitute the first directly comparable set of photolysis measurements for key phytocannabinoids. Full article

Two-dimensional (2D) Ruddlesden–Popper (RP) tin halide perovskites have attracted considerable attention as lead-free photovoltaic absorbers; however, the impact of organic A-site cations on their structure and pressure-dependent optoelectronic behavior remains underexplored. In this study, density functional theory (DFT) is used to investigate the structural, electronic, and optical properties of A₂SnI₄ (A = GUA⁺, DMA⁺, MA⁺) under ambient conditions and under hydrostatic pressure. All three compounds adopt layered frameworks in which the organic cations occupy the interlayer region, while SnI₆ octahedra form the inorganic slabs. Band-gap calculations are performed using HSE06 for ambient pressure, known for its accuracy in electronic structure predictions, and PBE for pressure simulations, due to its computational efficiency in large-scale systems. At ambient pressure, Hybrid-functional (HSE06) calculations indicate that all three materials are direct-gap semiconductors, with band gaps of 2.25 eV for MA2SnI₄, 2.98 eV for DMA2SnI4, and 2.85 eV for GUA2SnI4. Under hydrostatic compression, DMA₂SnI₄ shows comparatively modest band-gap variation and saturates near 1.7 eV. In contrast, GUA₂SnI₄ and MA₂SnI₄ exhibit pronounced band-gap narrowing, including a pressure-induced direct-to-indirect transition near 2 GPa, with band gaps decreasing to 0.59 eV (GUA₂SnI₄) and 0.34 eV (MA₂SnI₄) at elevated pressures. Overall, these findings highlight that A-site chemistry, combined with hydrostatic pressure, enables tuning the electronic and optical responses in tin-based 2D RP perovskites, demonstrating their promise as tunable, lead-free photovoltaic absorbers. Full article

Microalgae are rich in protein and phenolics, thereby having great potential for production of functional foods and nutraceuticals. However, despite featuring high nutritional value, these compounds often suffer from low stability and bioaccessibility. In this study, phenolics and protein extracted from Chlorella vulgaris were conjugated at different ratios (2.5–10%) and the structure and bioactivity of the conjugates were comprehensively characterized. The fluorescence intensity of protein decreased from 340 to 130–98 a.u. after conjugation and the UV-vis absorbance dropped from 1.6 to 0.5 a.u., which confirms the alteration of the chromophore area. The FTIR spectra revealed shifts in the C=O, N-H, and C-N bands, and the ¹H NMR spectra showed the broadening of signals and appearance of new peaks, indicating covalent bond formation through the Schiff base and Michael addition reactions. Conjugation significantly increased the antioxidant activities, in terms of ABTS inhibition by 644%, 257%, and 97%, as well as the ACE inhibitory activity, by 13.5%, 17.5%, and 19.7% for the 2.5%, 5% and 10% conjugates, respectively. The 2.5% conjugate showed the highest bioaccessibility (144%), which was 2.5 times that of free phenolics. Overall, this study proves that conjugation is an effective approach to enhancing the bioactivity and bioaccessibility of microalgae-derived compounds and unravel the structure–activity relationship of conjugates. The findings can promote the valorization of microalgae for product development in the food and nutraceutical industries. Full article

While diverse previously fabricated pristine and hydrogenated borophene lattices have been characterized predominantly by their metallic nature, a recent experimental breakthrough has introduced α′–B₈H₄, a semiconducting hydrogenated borophene phase, opening new avenues for boron-based nanoelectronics. Spurred by this breakthrough, herein we utilize a comprehensive first-principles framework to investigate the critical properties of α′–B₈H₄ monolayer. Stability analyses confirm the considerable dynamical and thermal robustness of the α′–B₈H₄ monolayer. Calculations using hybrid functionals show that suspended single-layer α′–B₈H₄ exhibits an indirect semiconducting behavior, with band gaps of 2.06 eV and 2.45 eV predicted by HSE06 and PBE0, respectively. Optical response calculations reveal strong in-plane absorbance in the UV region, with the first notable peak at ~3.65 eV and the main peak occurring between 4.20 and 4.45 eV, both of which are clearly within the ultraviolet range. Mechanical analysis reveals that α′–B₈H₄ exhibits decent in-plane strength (>10 N/m), while phononic transport calculations yield a moderately low room-temperature lattice thermal conductivity of ~20 W/m·K, both displaying slight anisotropic behavior. These results provide a comprehensive first-principles characterization of the α′–B₈H₄ monolayer, highlighting the rare emergence of semiconducting behavior in borophene derivatives and underscoring its potential for UV optoelectronics and nanoscale device applications. Full article

Surgical wound complications, particularly surgical site infection (SSI), remain common despite advances in perioperative care, and modern dressings—including emerging smart systems—are intended to optimize moisture balance, reduce bioburden, and support monitoring of healing. This narrative review, informed by PRISMA 2020, synthesized comparative clinical evidence on postoperative dressings across surgical specialties. PubMed and Embase were searched for peer-reviewed comparative human studies published in 2015–2025 involving adults undergoing surgery with primary closure or secondary intention healing. Outcomes included SSI, time to epithelialization/closure, scar outcomes, pain, peri-wound skin integrity, and dressing change frequency. Nine studies met the inclusion criteria across orthopedics, general and endocrine surgery, otolaryngology, maxillofacial surgery, and surgical oncology. In hip/knee arthroplasty, hydrofiber dressings were associated with lower SSI rates versus standard/absorbent dressings. A meta-analysis suggested that moist and silver-based dressings generally outperformed gauze, with ionic silver ranking highest for healing and metallic silver for SSI prevention, and hydrocolloids reduced dressing change frequency. Oxygen diffusion therapy improved scar outcomes after cervicotomy, and chitosan gel reduced synechiae after endoscopic sinus surgery. Evidence in oncologic surgery was inconclusive, and heterogeneity in interventions, endpoints, and follow-up limited pooling. Overall, advanced postoperative dressings may improve selected outcomes compared with traditional gauze, but effects appear procedure- and context-dependent; future studies should standardize outcomes, extend follow-up, and incorporate cost-effectiveness and patient-reported measures, alongside evaluation of sensor-enabled smart dressings. Full article

Colloidal PbSe quantum dots are promising candidates as saturable absorbers for ultrafast fiber lasers, but their performance is often limited by surface-related defects and chemical instability, leading to aggregation under optical pumping. In this study, we present a freestanding PbSe/PbS quantum dot-polystyrene composite saturable absorber film, with PbS overcoating on PbSe to enhance surface passivation and oxidation resistance. The composite exhibits a saturation intensity of 5.76 kW·cm⁻², a modulation depth of 33%, and an optical damage threshold of 13.6 mJ·cm⁻². When integrated into a bidirectionally pumped erbium-doped fiber laser in the anomalous-dispersion regime, the device demonstrates self-starting soliton mode locking at an ultralow pump threshold of 6 mW, generating 1.06 ps pulses with a radio-frequency signal-to-noise ratio of approximately 65 dB. The spectra remain stable over an 8-month period, showing excellent environmental and operational durability. These findings confirm that PbSe/PbS quantum dots in a polymer matrix offer a robust, low-threshold saturable absorber platform for ultrafast fiber lasers. Full article