Search Results (6,522)

Despite the significant advancements in treatment and prevention, the fight against cancer is ongoing worldwide. This study evaluated the pharmacological properties and anticancer activity of Afzelia quanzensis bark, traditionally used by the indigenous communities of KwaZulu Natal and Eastern Cape Provinces of South Africa to treat cancer and related illnesses. Phytochemical screening, high-performance liquid chromatography–diode array detection (HPLC-DAD), and Fourier-transform infrared spectroscopy (FTIR) analyses were carried out using established protocols. The antioxidant activity was assessed via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity and nitric oxide radicals. The anticancer activity was evaluated using the MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). Phytochemical analysis revealed the presence of saponins, flavonoids, terpenoids, alkaloids, steroids, cardiac glycosides, and phlobatannins. The HPLC-DAD analysis detected seven distinctive peaks in the aqueous extract and three distinctive peaks in the methanolic extract. The FTIR spectra of the aqueous extract displayed characteristic peaks corresponding to O-H, C=O, C=C, and =C–H functional groups. Among the tested extracts, the methanol extract exhibited the strongest antioxidant activity, followed by the ethanolic extract, in both DPPH and nitric oxide. The methanol extract showed a higher cell proliferation inhibition against the DU-145 cancer cell line with the percentage of inhibition of 37.8%, followed by the aqueous extract with 36.3%. In contrast, limited activity was observed against PC-3, SK-UT-1, and AGS cell lines. The results demonstrated notable dose-dependent antioxidant and antiproliferative activities supporting the ethnomedicinal use of Afzelia quanzensis bark in cancer management. These findings warrant further investigation into its bioactive constituents and mechanisms of action. Full article

This study evaluated biomass accumulation and phenolic compound production in seven Hypericum species (H. androsaemum, H. calycinum, H. hirsutum, H. kalmianum, H. olympicum, H. perforatum, and H. triquetrifolium) cultivated in vitro under varying growth regulator treatments and culture periods. Shoots were grown on Murashige and Skoog (MS) medium supplemented with benzyladenine (BA) or meta-topoline (mT) and analyzed after 40 and 60 days. MS medium supplemented with 0.2 mg/L BA was the most effective condition for promoting biomass across all species, with shoot fresh weight increasing significantly at 60 days, particularly in H. olympicum, H. perforatum, and H. triquetrifolium. High-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) identified 13 phenolic compounds, including flavonols, hydroxycinnamic acids, anthocyanins, phloroglucinols, and naphthodianthrones. Phenolic profiles were species-specific and influenced by culture period. H. kalmianum accumulated the highest total phenolic content (37.6 mg/g DW), while H. olympicum was the top producer of hypericin and pseudohypericin. These results highlight the crucial role of culture conditions in regulating both biomass and phytochemical production and provide a promising approach for producing bioactive metabolites in Hypericum species through in vitro systems. Full article

To enable multi-channel parallel spectral analysis in array-based devices such as micro-light-emitting diodes (Micro-LEDs) and line-scan spectral confocal systems, the development of compact array spectrometers has become increasingly important. In this work, a novel spectrometer architecture based on a microlens array grating (MLAG) is proposed, which addresses the major limitations of conventional spectrometers, including limited parallel detection capability, bulky structures, and insufficient spatial resolution. By integrating dispersion and focusing within a monolithic device, the system enables simultaneous acquisition across more than 2000 parallel channels within a 10 mm × 10 mm unit consisting of an f = 4 mm microlens and a 600 lines/mm blazed grating. Optimized microlens and aperture alignment allows for flexible control of the divergence angle of the incident light, and the system theoretically achieves nanometer-scale spectral resolution across a 380–780 nm wavelength range, with inter-channel measurement deviation below 1.25%. Experimental results demonstrate that this spectrometer system can theoretically support up to 2070 independently addressable subunits. At a wavelength of 638 nm, the coefficient of variation (CV) of spot spacing among array elements is as low as 1.11%, indicating high uniformity. The spectral repeatability precision is better than 1.0 nm, and after image enhancement, the standard deviation of the diffracted light shift is reduced to just 0.26 nm. The practical spectral resolution achieved is as fine as 3.0 nm. This platform supports wafer-level spectral screening of high-density Micro-LEDs, offering a practical hardware solution for high-precision industrial inline sorting, such as Micro-LED defect inspection. Full article

Cyborg insects offer a biologically powered solution for locomotion control, but conventional methods typically rely on invasive electrical stimulation. Here, we introduce a noninvasive, phototaxis-based strategy to steer walking Endebius florensis beetles using light-emitting diode (LED) stimuli. Electroretinogram recordings revealed spectral sensitivity to blue, green, and yellow light, with reduced response to red. Behavioral assays demonstrated robust positive phototaxis to blue light and negative phototaxis to yellow. Using these findings, we built a wireless microcontroller-based backpack emitting directional blue light to induce steering. The beetles reliably turned toward the activated light, achieving angular deflections over 60° within seconds. This approach enables repeatable, trauma-free insect control and establishes a new paradigm for biohybrid locomotion systems. Full article

The development of three types of UV radiation-based photoreactors using light-emitting diodes (LEDs) is presented. In this work, three pattern irradiation arrangements, direct radiation, internal radiation, and external radiation, were tested for deactivation of a typical model contaminant in wastewater under the same conditions. All photoreactors allow the adjustment of optical power and irradiation time and include a sensor for temperature monitoring in the solution. In this case, phenol was used as a model contaminant with TiO₂ as a photocatalyst in a batch-type reactor at pH 7. The results showed that the highest degradation efficiency was achieved after 120 min, reaching 97.79% for the internal-radiation photoreactor, followed by 90.17% when the direct-radiation photoreactor was used, and 85.24% for the external-radiation photoreactor. Phenol degradation served as the basis for validating reactor performance, given its persistence and relevance as an indicator in advanced oxidation processes. It was concluded that the arrangement of LEDs in each photoreactor significantly influences phenol degradation under the same reaction conditions. Full article

Free-space optical (FSO) communications have emerged as a promising complement to conventional radio-frequency (RF) systems due to their high bandwidth, low interference, and license-free spectrum. Visible-light FSO communication, using laser diodes or LEDs, offers potential for short-range data links, but performance is highly wavelength-dependent under varying atmospheric conditions. This study presents an experimental evaluation of three visible laser diodes at 650 nm (red), 532 nm (green), and 405 nm (violet), focusing on their optical output power, quantum efficiency, and modulation behavior across a range of driving currents and frequencies. A custom laboratory testbed was developed using an Atmega328p microcontroller and a Visual Basic control interface, allowing precise control of current and modulation frequency. A silicon photovoltaic cell was employed as the optical receiver and energy harvester. The results demonstrate that the 650 nm red laser consistently delivers the highest quantum efficiency and optical output, with stable performance across electrical and modulation parameters. These findings support the selection of 650 nm as the most energy-efficient and versatile wavelength for short-range, cost-effective visible-light FSO communication. This work provides experimentally grounded insights to guide wavelength selection in the development of energy-efficient optical wireless systems. Full article

The aim of this work is to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) against oral MDR (multi-drug-resistant) Candida spp. infections related to orthodontic treatment with palatal expanders through in vitro study. Methods: PDT protocol: Curcumin + H₂O₂ was used as a photosensitizer activated by a 460 nm diode LED lamp, with an 8 mm blunt tip for 2 min in each spot of interest. In vitro simulation: A palatal expander sterile device was inserted into a custom-designed orthodontic bioreactor, realized with 10 mL of Sabouraud dextrose broth plus 10% human saliva and infected with an MDR C. albicans clinical isolate CA95 strain to reproduce an oral palatal expander infection. After 48 h of incubation at 37 °C, the device was treated with the PDT protocol. Two samples before and 5 min after the PDT process were taken and used to contaminate a Petri dish with a Sabouraud field to evaluate Candida spp. CFUs (colony-forming units). Results: A nearly 99% reduction in C. albicans colonies in the palatal expander biofilm was found after PDT. Conclusion: The data showed the effectiveness of using aPDT to treat palatal infection; however, specific patient oral micro-environment reproduction (Ph values, salivary flow, mucosal adhesion of photosensitizer) must be further analyzed. Full article

Meta-heuristic algorithms are the dominant techniques for parameter estimating for solar photovoltaic (PV) models. Current algorithms are primarily designed with a focus on search performance and convergence speed, but they fail to account for the significant difference in the lengths of the feasible regions for each decision variable in the solar parameter estimation problem. The consideration of variable length difference in algorithm design may be beneficial to the efficiency for solving this problem. A gray predictive evolutionary algorithm with adaptive threshold adjustment strategy (GPEat) is proposed in this paper to estimate the parameters of several solar photovoltaic models. Unlike original GPEs and their existing variants with fixed thresholds, GPEat designs an adaptive threshold adjustment strategy (ATS), which adaptively adjusts the threshold parameter of GPE to be proportional to the length of each dimensional variable of the PV problem. The adaptive change of the threshold helps GPEat to select suitable operators for different dimensions of the PV problem. Several sets of experiments are conducted based on single-, double-, and triple-diode models and PV panel models. The experimental results indicate the highly competitive in parameter estimation for solar PV models of the proposed algorithm. Full article

In this paper, a novel 4H-SiC LDMOS structure with a trench heterojunction in the source (referred as to THD-LDMOS) is proposed and investigated for the first time, to enhance the reverse recovery performance of its parasitic diode. Compared with 4H-SiC, silicon has a smaller band energy, which results in a lower built-in potential for the junction formed by P+ polysilicon and a 4N-SiC N-drift region. A trench P+ polysilicon is introduced in the source side, forming a heterojunction with the N-drift region, and this heterojunction is unipolar and connected in parallel with the body PiN diode. When the LDMOS operates as a freewheeling diode, the trench heterojunction conducts first, preventing the parasitic PiN from turning on and thereby significantly reducing the number of carriers in the N-drift region. Consequently, THD-LDMOS exhibits superior reverse recovery characteristics. The simulation results indicate that the reverse recovery peak current and reverse recovery charge of THD-LDMOS are reduced by 55.5% and 77.6%, respectively, while the other basic electrical characteristics remains unaffected. Full article

Diamond, renowned for its exceptional electrical, physical, and chemical properties, including ultra-wide bandgap, superior hardness, high thermal conductivity, and unparalleled stability, serves as an ideal candidate for next-generation high-power and high-temperature electronic devices. Among diamond-based devices, Schottky barrier diodes (SBDs) have garnered significant attention due to their simple architecture and superior rectifying characteristics. This review systematically summarizes recent advances in diamond SBDs, focusing on both metal–semiconductor (MS) and metal–interlayer–semiconductor (MIS) configurations. For MS structures, we critically analyze the roles of single-layer metals (including noble metals, transition metals, and other metals) and multilayer metals in modulating Schottky barrier height (SBH) and enhancing thermal stability. However, the presence of interface-related issues such as high densities of surface states and Fermi level pinning often leads to poor control of the SBH, limiting device performance and reliability. To address these challenges and achieve high-quality metal/diamond interfaces, researchers have proposed various interface engineering strategies. In particular, the introduction of interfacial layers in MIS structures has emerged as a promising approach. For MIS architectures, functional interlayers—including high-k materials (Al₂O₃, HfO₂, SnO₂) and low-work-function materials (LaB₆, CeB₆)—are evaluated for their efficacy in interface passivation, barrier modulation, and electric field control. Terminal engineering strategies, such as field-plate designs and surface termination treatments, are also highlighted for their role in improving breakdown voltage. Furthermore, we emphasize the limitations in current parameter extraction from current–voltage (I–V) properties and call for a unified new method to accurately determine SBH. This comprehensive analysis provides critical insights into interface engineering strategies and evaluation protocols for high-performance diamond SBDs, paving the way for their reliable deployment in extreme conditions. Full article

In this work, we demonstrate high-efficiency 385 nm AlGaN-based near-ultraviolet micro light emitting diode (NUV-Micro LED) arrays. The epi structure is prepared using a novel AlN-inserted superlattice electrical blocking layer which enhances hole spreading in the p-type region significantly. The NUV-Micro LED arrays in this work comprise 228 chips in parallel with wavelengths at 385 nm, and each single chip size is 15 × 30 μm². Compared with conventional bulk AlGaN-based EBL structures, the NUV-Micro LED arrays that implemented the new hole spreading enhanced superlattice electrical blocking layer (HSESL-EBL) structure proposed in this work had a remarkable increase in light output power (LOP) at current density, increasing the range down from 0.02 A/cm² to as high as 97 A/cm². The array’s light output power is increased up to 1540% at the lowest current density 0.02 A/cm², and up to 58% at the highest current density 97 A/cm², measured under room temperature (RT); consequently, the WPE is increased from 13.4% to a maximum of 30.18%. This AlN-inserted HESEL-EBL design significantly enhances both the lateral expansion efficiency and the hole injection efficiency into the multi quantum well (MQW) in the arrays, improving the concentration distribution of the holes in MQW while maintaining good suppression of electron leakage. The array’s efficiency droop has also been greatly reduced. Full article

Using light-emitting diodes (LEDs), we examined how different light wavelengths influence the hypersensitive response (HR) in tobacco plants infected with Pseudomonas syringae pv. tomato (Pst). Pst-infiltrated plants exhibited greater resistance to Pst infection under green and blue light compared to white and red light, as indicated by reduced HR-associated programmed cell death, lower H₂O₂ production, and up to 64% reduction in membrane damage. During the late stage of HR, catalase and ascorbate peroxidase activities peaked under green and blue LEDs, with 5- and 10-fold increases, respectively, while superoxide dismutase activity was higher under white and red LEDs. Defense-related genes CHS1, PALa, PR1, and PR2 were more strongly induced by white and red light. The plants treated with green or blue LEDs during Pst infection prompted faster degradation of phototoxic Mg-porphyrins and exhibited smaller declines in F_v/F_m, electron transport rate, chlorophyll content, and LHCB expression compared to those treated with white or red LEDs. By contrast, the induction of the chlorophyll catabolic gene SGR was 54% and 77% lower in green and blue LEDs, respectively, compared to white LEDs. This study demonstrates that light quality differentially affects Pst-mediated HR, with green and blue light more effectively suppressing HR progression, mainly by reducing oxidative stress through enhanced antioxidative capacity and mitigation of photosynthetic impairments. Full article

(1) Background: The concentration of lamotrigine, an antiepileptic drug very often used in bipolar disorder, is most often determined in the blood, with many inconveniences. An alternative may be to use saliva as a diagnostic material for this purpose. The development of a method to determine lamotrigine in saliva as a biological material significantly improves patient comfort during sampling. The developed method uses solid-phase extraction for the isolation of the drug from saliva for the first time. (2) Methods: This study aimed to develop a method to determine lamotrigine in saliva using solid-phase extraction (SPE) for isolation and liquid chromatography with a diode array detector (LC-DAD) for quantitative analysis. (3) Results: The method was validated by determining its linearity in the concentration range 10–2000 ng/mL (R² > 0.99), and the intra- and inter-day precision expressed as coefficient of variation (CV%) did not exceed 15%. (4) Conclusions: The developed method was used to determine the salivary concentration of lamotrigine in patients treated with the studied compound, confirming its usefulness in bipolar disorder (BD). Full article

Thermal management is an area of study in electronics focused on managing temperature to improve reliability and efficiency. When temperatures are too high, cooling systems are activated to prevent overheating, which can lead to reliability issues. To monitor the temperatures, sensors are often placed on-chip near hotspot locations. These sensors should be very small to allow them to be placed among compact, high-activity circuits. Often, they are connected to a central control circuit located far away from the hot spot locations where more area is available. This paper proposes sensing units for a novel temperature sensing architecture in the TSMC 180 nm process. This architecture functions by approximating the current through the sensing unit at a reference voltage, which is used to approximate the temperature in the digital back end using fitting functions. Sensing units are selected based on how well its temperature–current relationship can be modeled, sensing unit area, and power consumption. Many sensing units will be experimented with at different reference voltages. These temperature–current curves will be modeled with various fitting functions. The sensing unit selected is a diode-connected p-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) with a size of W = 400 nm, L = 180 nm. This sensing unit is exceptionally small compared to existing work because it does not rely on multiple devices at the sensing unit location to generate a PTAT or IPTAT signal like most work in this area. The temperature–current relationship of this device can also be modeled using a 2nd order polynomial, requiring a minimal number of trim temperatures. Its temperature error is small, and the power consumption is low. The range of currents for this sensing unit could be reasonably made on an IDAC. Full article

Background: Clinical diagnostics, food industries, and biotechnological processes typically use an enzyme called alpha-amylase to metabolize carbohydrates. Objective: The aim of this study is to investigate how low-level laser irradiation (LLLI) affects alpha-amylase activity towards determining the usability of LLLI in non-invasive enzymatic modulation. Methods: Enzyme solutions were irradiated at 10, 20, 30, and 40 J/cm² utilizing 589 nm and 532 nm diode-pumped solid-state lasers. The iodine–starch colorimetric method was used to quantify post-irradiation enzymatic activity, with inverse correlations found between absorbance and activity levels. Modulation was determined by the wavelength and dosage. Results: Enzymatic activity significantly improved when utilizing 589 nm irradiation at lower doses, maximizing at 120% at 20 J/cm² (p < 0.01). Neutral or inhibitory effects were revealed when higher doses were applied. Enzymatic activity showed progressive inhibition when 532 nm irradiation was applied, declining to 75% at 40 J/cm² (p < 0.01). Conclusions: These outcomes indicate that conformational flexibility and catalytic efficiency occur when applying lower-energy photons at 589 nm, whilst oxidative stress and impaired enzymatic function are induced by higher-energy photons at 532 nm. This is consistent with the biphasic dose–response characteristic of photobiomodulation. Full article