Search Results (7,398)

Motivated by the rapid development of SERS technology, trace detection of various viruses in the sewage and body fluid environments and accurate positive and negative diagnosis of detection samples can be achieved. However, evaluating the environmental survival ability of viruses based on SERS technology remains an unexplored issue, but holds significant guiding significance for effective epidemic prevention and control as well as inactivation treatment. In this work, Au nanoarrays were fabricated on silicon substrates through a simple Ar ion sputtering route as ultra-sensitive SERS chips. With the synergistic contribution of the “lightning rod” effect and the enhanced coupling surface plasmon caused by the nanoarrays, the ultra-sensitive detection of SARS-CoV-2 S protein with a concentration of 1 pg/mL and SERS enhancement factor of 4.89 × 10⁹ can be achieved. Exploration of the environmental survival ability of the SARS-CoV-2 virus indicates that the Raman activity of SARS-CoV-2 S protein exhibited higher temperature tolerance from 0 °C to 60 °C than SARS-CoV S protein, suggesting that the SARS-CoV-2 virus has less temperature influence from increasing air temperature than the SARS-CoV virus to a certain extent, which explains the seasonal recurrence pattern and regional transmission pattern of the novel coronavirus that are different from the SARS virus. Full article

The Eastern Kazakhstan Gold Belt is a major black-shale-hosted gold province in Central Asia where the main types of deposits comprise mineralized zones with auriferous sulfides (micro- and nano-inclusions of gold and refractory gold) and quartz veins with visible gold. The quartz vein deposits are economically less important but may potentially represent the upper parts of bigger ore systems concealed at depth. In this work, the mineralogy of the quartz vein deposits and related wall rock alteration zones was studied using microscopy and SEM-EDS analysis, and the geochemical dispersion of the ore elements in primary alteration haloes was documented utilizing spatial distribution maps and statistical treatment methods. The studied auriferous quartz veins are classified as epizonal black-shale-hosted orogenic gold deposits. The veins generally have linear shapes with an average width of ca. 1 m and length up to 150 m and contain high-grade native gold with minor amounts of sulfides. In supergene oxidation zones, the native gold is closely associated with Fe-hydroxide minerals cementing brecciated zones within the veins. The auriferous quartz veins are usually enclosed by the wall rock alteration envelopes, where two types of alteration are distinguished. Proximal phyllic alteration (sericite-albite-pyrite ± chlorite, Fe-Mg-Ca carbonates, arsenopyrite, and pyrrhotite) develops as localized alteration envelopes, and pervasive carbonation accompanied by chlorite ± sericite and albite is the dominant process in the distal alteration zones. The rocks within the alteration zones are enriched in Au and chalcophile elements, and three groups of chemical elements showing significant positive mutual correlation have been identified: (1) an early geochemical assemblage includes V, P, and Co (±Ni), which are the chemical elements characteristic for black shale formations, (2) association of Au, As, and other chalcophile elements is distinctly overprinting, and manifests the main stage of sulfide-hosted Au mineralization, and (3) association of Bi and Hg (±Sb and U) includes the chemical elements that are mobile at low temperatures, and can be explained by activity of the late-stage hydrothermal or supergene fluids. The chalcophile elements show negative slopes from proximal to distal alteration zones and form overlapping positive anomalies on spatial distribution mono-elemental maps. Thus, the geochemical methods can provide useful tools to delineate the ore elemental associations and to outline reproducible anomalies for subsequent regional gold prospecting. Full article

Background: Gold nanoparticles (AuNPs) have several beneficial properties that make them effective as intracellular drug carriers, and their potential for various diagnostic and therapeutic applications is gaining recognition. Depending on their size and shape, AuNPs can cross the central nervous system (CNS) through the blood–brain barrier (BBB). In the CNS, they can exert a variety of influences on neuronal and glial cells, which can be both supportive—promoting cell health and function—and cytotoxic, potentially leading to cellular damage. The hypothalamus (HT) is the first region where nanoparticles (NPs) interact, as this neuroendocrine center is particularly sensitive to factors in the systemic circulation due to its function and location. This area is affected by systemic factors, including pro-opiomelanocortin (POMC) neurons, which regulate metabolic function and maintain homeostasis. The activity of mitochondria within these cells influences their response to both external factors and the presence of AuNPs, thereby facilitating a complex interplay between nanoparticle interactions and cellular metabolism in this vital brain region. Aims: This study investigates how AuNPs, at different concentrations and exposure times under in vitro conditions, affect the mitochondrial activity of POMC neurons, aiming to provide a comprehensive understanding of the mechanisms in the HT. Methods: The study investigates the effect of varying gold nanoparticle concentrations on the mitochondrial activity of POMC neurons over treatment periods of 1, 15, 24, and 48 h. Mitochondrial activity was measured using a Seahorse XFp Analyzer to provide high-resolution insights. Additionally, mitochondrial functionality was assessed through the detection of reactive oxygen species (ROS) and cell viability. Results: The findings indicated that the effects of gold nanoparticles on mitochondrial activity depend significantly on their concentration and exposure time. Specifically, exposure leads to an increase in early response systems, the citric acid cycle, and proton efflux, ultimately resulting in the inhibition of mitochondrial function and ATP production in POMC cells. This disruption may affect hypothalamic regulation and energy metabolism. Full article

One of the major challenges in diagnosing various diseases, including neurological and neurodegenerative disorders, as well as carcinogenesis, is detecting unlabeled neurotransmitters. Surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared spectroscopy (SEIRA) are promising methods for neurotransmitter biosensing and bioimaging. These methods are unique in that they are non-destructive and can identify molecular fingerprints. In this study, these methods were used to detect the following potent bradykinin (BK) antagonists: [D-Arg⁰,Hyp³,Thi⁵,D-Tic⁷,Oic⁸]BK, [D-Arg⁰,Hyp³,Thi⁵,D-Phe⁷,Thi⁸]BK, [D-Arg⁰,Hyp³,Igl⁵,D-Phe(5F)⁷,Oic⁸]BK, and [D-Arg⁰,Hyp³,Igl⁵,D-Igl⁷,Oic⁸]BK. The peptides were immobilized on a sensor surface consisting of silver (AgNPs) and gold (AuNPs) nanoparticles. These sensors have uniform particle sizes and small size distributions. Thanks to fast synthesis, easy handling, and reproducible results, these sensors enable routine testing. The vibrational structure of these peptides could not be determined using classical vibrational methods (Raman and IR) or surface-enhanced methods (SERS and SEIRA). This work presents the results of that research. Additionally, the SEIRA spectrum for BK or its analogs has not yet been published. This study presents research using SERS and SEIRA that shows that AgNP and AuNP sensors can detect the peptides under investigation. SERS is a more selective method than SEIRA because it allows for the differentiation of peptides based on the enhancement of certain bands in the SERS spectra. Furthermore, each peptide uniquely interacts with AuNPs, whereas all peptides bind to AgNPs via the C-terminus in different orientations. Consequently, the AuNP sensor is more selective than the AgNP sensor. Some bands were selected as markers for the sensing of specific peptides. Full article

This study assessed the physico-chemical and sensory effects of enriching composite cereal porridges, typically consumed in Uganda, with undried house crickets (Acheta domesticus), a rich source of protein and vitamin B₁₂. Composite flours containing 8.3% undried crickets, 66.7% maize, and 25.0% millet were compared to a control formulation with 73.0% maize and 27.0% millet, both extruded at 140 °C. Cricket enrichment slightly reduced lightness L* (59.99 vs. 61.28) and significantly increased aroma intensity (23,450 × 10⁴ AU vs. 18,210 × 10⁴ AU; p < 0.05), attributable to higher extrusion-induced Strecker degradation, Maillard reaction, and lipid oxidation. Rheological analysis revealed that paste made from cricket-enriched flour had lower critical strain (≈0.01%) and softened sooner than the control paste (≈0.03%) without becoming fragile. Both flours displayed stable paste-like behavior at stresses >10 Pa, with elastic moduli under 10⁴ Pa, which is typical for soft pastes. Reduced pasting values relative to native flours are attributable to starch pre-gelatinization during extrusion. Sensory evaluation showed positive hedonic ratings for both porridges, and a choice test indicated no significant consumer preference. Generally, physico-chemical and sensory changes were minimal, supporting the use of house crickets for nutrient enrichment of composite cereal porridges. Full article

The electrical properties of contacts to p-type nitride semiconductor devices, based on gallium nitride, were simulated by ab initio and drift-diffusion calculations. The electrical properties of the contact are shown to be dominated by the electron-transfer process from the metal to GaN, which is related to the Fermi-level difference, as determined by both ab initio and model calculations. The results indicate a high potential barrier for holes, leading to the non-Ohmic character of the contact. The electrical nature of the Ni–Au contact formed by annealing in an oxygen atmosphere was elucidated. The influence of doping on the potential profile of p-type GaN was calculated using the drift-diffusion model. The energy-barrier height and width for hole transport were determined. Based on these results, a new type of contact is proposed. The contact is created by employing multiple-layer implantation of deep acceptors. The implementation of such a design promises to attain superior characteristics (resistance) compared with other contacts used in bipolar nitride semiconductor devices. The development of such contacts will remove one of the main obstacles in the development of highly efficient nitride optoelectronic devices, both LEDs and LDs: energy loss and excessive heat production close to the multiple-quantum-well system. Full article

This study investigates microbial fuel cell (MFC) performance through the modification of Saccharomyces cerevisiae with gold nanoparticles (AuNPs) and polypyrrole (PPy). The yeast/AuNP-modified electrodes generated the highest median current of 2.57 nA, significantly outperforming the yeast/PPy-modified (0.82 nA) electrodes. Power density measurements further confirmed the superior performance of the yeast/AuNP-modified electrodes, showcasing a notable improvement in current densities and power outputs. Yeast/AuNP-modified graphite electrodes produced a higher power density of 22.8 mW/m², while exhibiting a lower current density compared to electrodes modified solely with yeast, which achieved a power density of 5.7 mW/m². These findings highlight the potential of AuNPs in significantly enhancing the electrochemical performance of yeast-based MFCs, providing a promising approach for the development of more efficient bioelectrochemical systems. Full article

This study investigated the concentrations of metals in stormwater runoff collected during two extreme flooding events on the American University of Sharjah (AUS) campus in the United Arab Emirates (UAE). Given the increasing frequency of intense rainfall in arid regions, stormwater contamination represents a growing environmental and public health concern. Stormwater samples were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES) to quantify metal concentrations. The results showed that iron (0.049–2.080 mg/L), aluminum (0.097–2.020 mg/L), and potassium (0.614–3.860 mg/L) were the most abundant metals detected. Lower concentrations were observed for manganese (0.000–0.058 mg/L), barium (0.000–0.073 mg/L), chromium (0.000–0.013 mg/L), nickel (0.000–0.038 mg/L), and vanadium (0.000–0.004 mg/L). These findings underscore the critical need for effective stormwater management in arid regions, where climate change is expected to increase the frequency and intensity of extreme weather events. Improved drainage systems and long-term monitoring are essential to mitigate the environmental and public health risks posed by stormwater contamination in rapidly urbanizing areas. Full article

The allostatic load index (AL_index) measures the cumulative physiological burden on the body due to stress. This prospective cohort study examined the relationships between certain molecular biomarkers, physical variables, and psychometric variables during deload and overload microcycles to contribute to developing an AL_index in professional team-sport athletes. Twelve elite male basketball players (18.3 [0.9] years; 77.2 [5.7] kg; 185 [9.0] cm) were monitored during two microcycles (deload and overload). Blood creatine kinase (CK) and urea levels, countermovement jump (CMJ), session-RPE (RPE × session duration [min], its exponentially weighted moving average [EWMA]), and a cumulative wellness score (sleep, stress, fatigue, muscle soreness, and mood) were assessed at different time points. Bayesian and robust statistics (Cohen’s ξ) were employed. CK rose from 222 U/L (deload) to 439 U/L (overload; +98%, large effect ξ = 0.65), while session-RPE load more than doubled (270 [269] AU to 733 [406] AU, ξ > 0.8). No difference was found in urea and wellness scores (cumulative or other components). CK levels showed moderate positive correlations with both EWMA of session-RPE (ρ = 0.346, p = 0.002) and reduced sleep quality (ρ = 0.25, p = 0.018). Bayesian modeling identified the EWMA of session-RPE as the strongest predictor of jump-defined fatigue (β = 0.012, 95% HDI [0.004, 0.021]), while CK demonstrated a small negative association (β = −0.009, HDI [−0.016, −0.001]). Finally, a principal component analysis (PCA) revealed that CK and the EWMA of session-RPE were robust indicators of physiological stress. A parsimonious index based on PCA loadings ([0.823 × CK] + [0.652 × EWMA of session-RPE]) demonstrated strong discriminative validity between microcycle phases (overload: 515, 95% HDI [442, 587] versus deload: 250, 95% HDI [218, 283], BF₁₀ > 100,000). CK and session-RPE may serve as sensitive biomarkers for inclusion in the AL_index for team sport athletes. Full article

Background: Dengue infection is a spreading vector borne disease with most severe infection-related fatalities occurring in adults. This study was conducted to explore prognostic indicators of dengue infection severity. Methods: This study included patients aged over 15 years who were diagnosed with dengue viral infection. Data were collected from nine hospitals across all regions of Thailand between January 2019 and December 2022. Diagnosis of dengue infection was confirmed by a positive result for the NS-1 antigen via RT–PCR, IgM antibody, or IgG antibody tests. Data including gender, age, BMI, underlying disease, clinical characteristics and laboratory findings were collected. Multivariable logistic regression with backward elimination was used to identify a set of prognostic factors. Results: The prognostic indicators of severe dengue were age < 55 years (OR = 6.13, p = 0.054), severe bleeding (bleeding from the gastrointestinal tract, hematemesis, melena, menorrhagia, or hematuria) (OR = 20.75, p < 0.001), pleural effusion (OR = 10.23, p < 0.001), and platelet ≤ 100,000 (/µL) (OR = 3.62, p = 0.035). These predictors were able to accurately estimate the severity of dengue infection with an area under the receiver operating curve (AuROC) of 0.836. Conclusions: The proposed four prognostic factors can be applied to predict severe dengue infections. These findings may inform the development of a risk scoring system to forecast severe dengue infection, early detection, and appropriate treatment during sickness. Full article

Mercury (Hg) is a globally recognized toxic element, and the Minamata Convention on Mercury entered into force in 2017 to address its associated risks. Under the United Nations Environment Programme, international efforts to reduce Hg emissions and monitor its environmental presence are ongoing. In support of these initiatives, we developed a simple and rapid mercury detection device based on a quartz crystal microbalance (QCM-Hg sensor), which utilizes the direct amalgamation reaction between Hg and a gold (Au) electrode. The experimental results demonstrated a proportional relationship between Hg concentration and the resulting oscillation frequency shift. Increased flow rates and prolonged measurement durations enhanced detection sensitivity. The system achieved a detection limit of approximately 1 µg/m³, comparable to that of commercially available analyzers. Furthermore, a measurement configuration integrating the reduction-vaporization method with the QCM-Hg sensor enabled the detection of mercury in aqueous samples. Based on the experimental results and the gas-phase detection sensitivity achieved to date, concentrations as low as approximately 0.05 µg/L appear to be detectable. These findings highlight the potential of the QCM-Hg system for on-site mercury monitoring. This review aims to provide a comprehensive yet concise overview of QCM-Hg sensor development and its potential as a next-generation tool for environmental and occupational mercury monitoring. Full article

With the increasing complexity of human–computer interaction scenarios, conventional digital human facial expression systems show notable limitations in handling multi-emotion co-occurrence, dynamic expression, and semantic responsiveness. This paper proposes a digital human system framework that integrates multimodal emotion recognition and compound facial expression generation. The system establishes a complete pipeline for real-time interaction and compound emotional expression, following a sequence of “speech semantic parsing—multimodal emotion recognition—Action Unit (AU)-level 3D facial expression control.” First, a ResNet18-based model is employed for robust emotion classification using the AffectNet dataset. Then, an AU motion curve driving module is constructed on the Unreal Engine platform, where dynamic synthesis of basic emotions is achieved via a state-machine mechanism. Finally, Generative Pre-trained Transformer (GPT) is utilized for semantic analysis, generating structured emotional weight vectors that are mapped to the AU layer to enable language-driven facial responses. Experimental results demonstrate that the proposed system significantly improves facial animation quality, with naturalness increasing from 3.54 to 3.94 and semantic congruence from 3.44 to 3.80. These results validate the system’s capability to generate realistic and emotionally coherent expressions in real time. This research provides a complete technical framework and practical foundation for high-fidelity digital humans with affective interaction capabilities. Full article

To exploit the near-infrared (NIR) light of MoO₃, the MoVO_x mixed oxide was synthesized using a one-pot approach. The effects of different electrodes, V doping, and bias on the optoelectronic properties were investigated. The photoelectric responses to light sources with wavelengths of 405, 532, 650, 780, 808, 980, and 1064 nm were studied using both Au and carbon electrodes with 6B pencil drawings. The results demonstrate that the MoVO_x nanoblets exhibit photocurrent switching characteristics across the broadband region of the light spectrum. Even when zero bias was applied and the mixed oxide sample was stored at room temperature for over two years, a good photoelectric signal was still observed. This demonstrates that the MoVO_x nanoblets present an interface where interfacial charge transfer forms a strong built-in electric field, promoting photogenerated charge separation and transfer while suppressing photogenerated carrier recombination, and exhibiting self-powered characteristics. Interestingly, reducing the power of the typical excitation light sources resulted in a transition from positive to negative photocurrent features. This reflects the result of an imbalance between the concentration of material defects and the concentration of photogenerated electrons. The MoVO_x nanoblets not only enhance charge transport performance, but also significantly improve the exploitation of near-infrared light. Doping with V significantly improves the nanocomposites’ near-infrared (NIR) photoelectric sensitivity. This study demonstrates that heavily doping aliovalent ions during the in situ preparation of nanocomposites effectively enhances their photophysical properties. It provides a straightforward approach to narrowing the band gap of wide-bandgap oxides and effectively avoiding the recombination of photogenerated carriers. Full article

The design of photocatalysts capable of generating localized surface plasmon resonance (LSPR) effects represents a promising strategy for enhancing photocatalytic activity. However, the mechanistic role of plasmonic nanoparticles-induced interfacial electric fields in driving photocatalytic processes remains poorly understood. To produce a Schottky junction, varying amounts of Au nanoparticles widely utilized to broaden the light absorption were loaded onto ultrathin carbon nitride sheets (Au/UCN). The Au/UCN-20 Schottky junction exhibits exceptional photocatalytic activity, achieving a hydrogen evolution rate (14.2 mmol·g⁻¹ over a 4 h period) while maintaining robust stability through five consecutive photocatalytic cycles. The LSPR activity of Au nanoparticles are responsible for the broadened light absorption spectrum of Au/UCN nanocomposites. The interfacial electric field generated at the Au /UCN heterojunction is proposed to enhance charge-transfer efficiency through Schottky barrier penetration of photocarriers, mediated by electric field-driven carrier migration, according to surface potential and finite-difference time-domain (FDTD). These findings uncover a previously obscured photocatalytic mechanism driven by LSPR-induced interfacial electric fields, pioneering a quantum-dot-directed strategy to precisely engineer charge dynamics in advanced photocatalysts via targeted manipulation of nanoscale electric field effects. Full article

Protein adsorption on dental zirconia (ZrO₂) surfaces plays a crucial role in plaque formation, tissue healing, and bone osseointegration. This study investigated and compared the adsorption behavior of three salivary antimicrobial proteins—peroxidase, lactoferrin, and lysozyme—on a ZrO₂ sensor and an Au sensor using a quartz crystal microbalance (QCM) operating at 27 MHz. Protein adsorption was determined from frequency decreases, and the apparent reaction rate constant (k_obs) was calculated by fitting frequency–time curves to a kinetic model. The amount of lactoferrin adsorbed on the ZrO₂ sensor was significantly higher than that of peroxidase and lysozyme (p < 0.05). Significantly smaller amounts of peroxidase and lysozyme were adsorbed onto the ZrO₂ sensor than the Au sensor (p < 0.05). The k_obs for lysozyme on the Au sensor was significantly higher than those for lactoferrin on sensors and for peroxidase on the Au sensor (p < 0.05). Differences in salivary antimicrobial protein adsorption between Au and ZrO₂ surfaces were influenced, in part, by electrostatic interactions between the proteins and the material surface. Full article