Search Results (496)

One of the promising research areas involving carborane derivatives is boron neutron capture therapy (BNCT). Due to the high boron atom content in carborane molecules, these compounds are considered potential candidates for BNCT-based cancer treatment. Despite ongoing studies on various biologically active carboranyl-containing compounds, the search continues for substances that meet the stringent requirements of effective BNCT agents. In this study, the synthesis of carboranyl-containing derivatives of β-arylaliphatic acids is described, along with the investigation of their reactivity with primary and secondary amines, as well as with metals and their hydroxides. The molecular structures of the synthesized compounds were confirmed using Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, and mass spectrometry (LC-MS). Cytotoxicity of the water-soluble compound potassium 3-(2-isopropyl-1,2-dicarba-closo-dodecaboran-1-yl)-3-phenylpropanoate was evaluated using several cell lines, including HdFn and MCF-7. Full article

This research presents the development and management principles of mobile resonant electrical systems designed for high-voltage generation, intended for non-destructive diagnostics of insulation in high-power electrical equipment. The core of the system is a series inductive–capacitive (LC) circuit characterized by a high quality (Q) factor and operating at high frequencies, typically in the range of 40–50 kHz or higher. Practical implementations of the LC circuit with Q-factors exceeding 200 have been achieved using advanced materials and configurations. Specifically, ceramic capacitors with a capacitance of approximately 3.5 nF and Q-factors over 1000, in conjunction with custom-made coils possessing Q-factors above 280, have been employed. These coils are constructed using multi-core, insulated, and twisted copper wires of the Litzendraht type to minimize losses at high frequencies. Voltage amplification within the system is effectively controlled by adjusting the current frequency, thereby maximizing voltage across the load without increasing the system’s size or complexity. This frequency-tuning mechanism enables significant reductions in the weight and dimensional characteristics of the electrical system, facilitating the development of compact, mobile installations. These systems are particularly suitable for on-site testing and diagnostics of high-voltage insulation in power cables, large rotating machines such as turbogenerators, and other critical infrastructure components. Beyond insulation diagnostics, the proposed system architecture offers potential for broader applications, including the charging of capacitive energy storage units used in high-voltage pulse systems. Such applications extend to the synthesis of micro- and nanopowders with tailored properties and the electrohydropulse processing of materials and fluids. Overall, this research demonstrates a versatile, efficient, and portable solution for advanced electrical diagnostics and energy applications in the high-voltage domain. Full article

Wild ales represent a diverse category of spontaneously fermented beers, influenced by complex microbial populations and variable ingredients. This study employed an integrated metabolomic profiling approach combining proton nuclear magnetic resonance (¹H NMR) spectroscopy, liquid chromatography–mass spectrometry (LC-MS), and spectrophotometric assays (DPPH and FRAP) to characterize the molecular composition and antioxidant potential of 22 wild ales from six countries. A total of 53 compounds were identified and quantified using NMR, while 62 compounds were identified by using LC-MS. The compounds in question included organic acids, amino acids, sugars, alcohols, bitter acids, phenolic compounds, and others. Ingredient-based clustering revealed that the addition of dark fruits resulted in a significant increase in the polyphenolic content and antioxidant activity. Concurrently, herb-infused and light-fruit beers exhibited divergent phytochemical profiles. Prolonged aging (>18 months) has been demonstrated to be associated with increased levels of certain amino acids, fermentation-derived aldehydes, and phenolic degradation products. However, the influence of maturation duration on the antioxidant capacity was found to be less significant than that of the type of fruit. Country-specific metabolite trends were revealed, indicating the influence of regional brewing practices on beer composition. Correlation analysis was employed to identify the major contributors to antioxidant activity, with salicylic, dihydroxybenzoic, and 4-hydroxybenzoic acids being identified as the most significant. These findings underscore the biochemical intricacy of wild ales and exemplify metabolomics’ capacity to correlate compositional variation with functionality and authenticity in spontaneously fermented beverages. Full article

This paper introduces an enhanced bi-directional full-bridge resonant converter designed for Vehicle-to-Grid (V2G) systems. A key innovation lies in the incorporation of an auxiliary LC resonant circuit connected via a tertiary transformer winding. This circuit dynamically modifies the magnetizing inductance based on operating frequency, enabling soft-switching across all primary switches, specifically, Zero-Voltage Switching (ZVS) at turn-on and near Zero-Current Switching (ZCS) at turn-off across the entire load spectrum. Additionally, the converter supports both Constant Current (CC) and Constant Voltage (CV) charging modes at distinct, fixed operating frequencies, thus avoiding wide frequency variations. A 3.3 kW prototype developed for onboard electric vehicle charging applications demonstrates the effectiveness of the proposed topology. Experimental results confirm high efficiency in both charging and discharging operations, achieving up to 98.13% efficiency in charge mode and 98% in discharge mode. Full article

Rouxiella badensis DSM 100043^T had been previously proven to produce a novel glucoselipid biosurfactant which has a very low critical micelle concentration (CMC) as well as very good stability against a wide range of pH, temperature, and salinity. In this study, we performed a function-based library screening from a R. badensis DSM 100043^T genome library to identify responsible genes for biosynthesis of this glucoselipid. The identified open reading frames (ORFs) were cloned into several constructs in Escherichia coli for gene permutation analysis and the individual products were analyzed using high-performance thin-layer chromatography (HPTLC). Products of interest from positive expression strains were purified and analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and nuclear magnetic resonance (NMR) for further structure elucidation. Function-based screening of 5400 clones led to the identification of an operon containing three ORFs encoding acetyltransferase GlcA (ORF1), acyltransferase GlcB (ORF2), and phosphatase/HAD GlcC (ORF3). E. coli pCAT2, with all three ORFs, resulted in the production of identical R. badensis DSM 100043^T glucosedilipid with Glu-C_10:0-C_12:1 as the main congener. ORF2-deletion strain E. coli pAFP1 primarily produced glucosemonolipids, with Glu-C_10:0,3OH and Glu-C_12:0 as the major congeners, predominantly esterified at the C-2 position of the glucose moiety. Furthermore, fed-batch bioreactor cultivation of E. coli pCAT2 using glucose as the carbon source yielded a maximum glucosedilipid titer of 2.34 g/L after 25 h of fermentation, which is 55-fold higher than that produced by batch cultivation of R. badensis DSM 100043^T in the previous study. Full article

Background: Exfoliation glaucoma (XFG) represents a form of deleterious ocular aging of unclear etiology. We evaluated prediagnostic nuclear magnetic resonance (NMR)-based metabolites in relation to XFG risk, expanding on our prior findings of XFG-related metabotypes using liquid chromatography-mass spectrometry (LC-MS). Methods: We identified 217 XFG cases and 217 matched controls nested within three prospective health professional cohorts with plasma collected a mean 11.8 years before case identification. Plasma metabolites were analyzed using the targeted NMR Nightingale platform. Conditional logistic models and Metabolite Set Enrichment Analysis were performed. Multiple comparison issues were addressed using the number of effective tests (NEF) and false discovery rate (FDR). Results: Among 235 profiled metabolites, higher glucose was significantly associated with a lower risk of XFG (odds ratio (95%CI) = 0.42 (0.26, 0.7); NEF = 0.03). Among metabolite classes, lipoprotein subclasses and branched-chain amino acids were inversely associated, while relative lipoprotein lipid concentrations were adversely associated (FDR < 0.05). Conclusion: NMR profiling revealed that glucose, branched-chain amino acids, lipoprotein subclasses, and relative lipoprotein lipid concentrations may play important roles in XFG etiology. Full article

Many novel microwave devices have been developed based on the left-handed (LH) structure. This paper studies three CMOS standing-wave oscillators (SWOs) using an LH LC network. The first SWO is a class-B VCO, and the second SWO is a class-C SWO. The SWOs are implemented with the TSMC 0.18 μm 1P6M CMOS process technology. The SWOs utilize two units of an LH LC resonator, and the LC resonator is shunted with a pair of cross-coupled transistors to compensate for the loss in the LC resonator. The first and second SWOs utilize two O-shaped inductors to form a unit cell with capacitors. The third SWO utilizes an eight-shaped inductor and an orthogonal transformer to conserve the die area and suppress the magnetic coupling noise. The die area of the third oscillator is 0.986 × 0.756 mm². The SWO can generate differential signals in the frequency range of 8.3 GHz–9.3 GHz (10.83%), and its measured figure of merit (FOM) is −188.6 dBc/Hz at a 1 MHz offset frequency. Full article

In order to break through the difficulties with a very-low-frequency (VLF) miniaturized antenna with small power capacity and low radiation efficiency, this paper proposes a high-radiation-field-strength magnetic loop antenna based on a nanocrystalline alloy magnetic core. A high-permeability nanocrystalline toroidal core (μ_r = 50,000, B_s = 1.2 T) is used to optimize the thickness-to-diameter ratio (t = 0.08) and increase the effective permeability to 11,000. The Leeds wires, characterized by their substantial carrying capacity, are manufactured through a toroidal winding process. This method results in a 68% reduction in leakage compared to traditional radial winding techniques and enhances magnetic induction strength by a factor of 1.5. Additionally, this approach effectively minimizes losses, thereby facilitating support for kilowatt-level power inputs. A cascaded LC resonant network (resonant capacitance 2.3 μF) and ferrite balun transformer (power capacity 3.37 kW) realize a 20-times amplification of the input current. A series connection of a high-voltage isolation capacitor blocks DC bias noise, guaranteeing the stable transmission of 1200 W power, which is 6 times higher than the power capacity of traditional ring antenna. At 7.8 kHz frequency, the magnetic field strength at 120 m reaches 47.32 dBμA/m, and, if 0.16 pT is used as the threshold, the communication distance can reach 1446 m, which is significantly better than the traditional solution. This design marks the first instance of achieving kilowatt-class VLF effective radiation in a compact 51 cm-diameter magnetic loop antenna, offering a highly efficient solution for applications such as mine communication and geological exploration. Full article

Background/Objectives: In the context of accelerating climate change and growing food insecurity, improving crop resilience to abiotic stresses such as drought, salinity, heat, and cold is a critical agricultural and scientific challenge. Understanding the biochemical mechanisms that underlie plant stress responses is essential for developing resilient crop varieties This review aims to provide an integrative overview of how metabolomics can elucidate biochemical mechanisms underlying stress tolerance and guide the development of stress-resilient crops. Methods: We reviewed the recent literature on metabolomic studies addressing abiotic stress responses in various crop species, focusing on both targeted and untargeted approaches using platforms such as nuclear magnetic resonance (NMR), liquid chromatography–mass spectrometry (LC-MS), and gas chromatography–mass spectrometry (GC-MS). We also included emerging techniques such as capillary electrophoresis–mass spectrometry (CE-MS), ion mobility spectrometry (IMS-MS), Fourier transform infrared spectroscopy (FT-IR), and data-independent acquisition (DIA). Additionally, we discuss the integration of metabolomics with transcriptomics and physiological data to support system-level insights. Results: The reviewed studies identify common stress-responsive metabolites, including osmoprotectants, antioxidants, and signaling compounds, which are consistently linked to enhanced tolerance. Novel metabolic biomarkers and putative regulatory hubs are highlighted as potential targets for molecular breeding and bioengineering. We also address ongoing challenges related to data standardization and reproducibility across analytical platforms. Conclusions: Metabolomics is a valuable tool for advancing our understanding of plant abiotic stress responses. Its integration with other omics approaches and phenotypic analyses offers promising avenues for improving crop resilience and developing climate-adaptive agricultural strategies. Full article

In this paper, a capacitively coupled-fed reconfigurable wideband bandpass filter (BPF) is proposed based on liquid crystal (LC) technology, which achieved three transmission poles across varying bias voltages (V_B). An open-ended stepped impedance resonator configuration enables multi-mode resonance, offering significantly wider bandwidth compared to uniform-impedance resonators. The fractional bandwidth (FBW) and transmission pole positions are determined by the impedance ratio of the two resonators, allowing the filter to meet specific design requirements. An analytical methodology employing multilayer transmission line formulations and resonant frequency ratios was used to predict the modal stability of transmission poles under dielectric constant variation, which was subsequently validated through simulation. Experimental results show that the center frequency can be adjusted from 10.76 to 9.47 GHz with a maximum V_B of 30 V, achieving a tuning range of 12.71%. The normalized 3 dB FBW exceeds 64.66%, and the return loss remains above 10 dB from 0 to 30 V, offering the widest FBW among the reported LC BPFs without pole merging or mode collapse. The frequency response of the fabricated filter shows good agreement with the simulation results. Full article

This work proposes two voltage-controlled oscillators using noise-filtering technique. The first one is a 24-GHz voltage-controlled oscillator, and the second one is based on a push–push architecture with a $\mathsf{\lambda }$/4 transmission line to further increase the frequency up to 48 GHz. The designs are implemented and verified in a standard 90-nm CMOS process. Typically, the current mirror transistor in the tail current has a nonlinear effect. When the transistor operates in the nonlinear region, noise will be introduced. Therefore, a set of LC filters with a resonant frequency at 2$f_0$ are added to the design of this section to filter the noise at 2$f_0$ through the capacitor to the ground. The measurement results show that the design of a single oscillator has an oscillation frequency of 24.37 GHz, a tuning range of 6.5%, and a phase noise of −97.19 dBc/Hz @1MHz. The measurement results of the push–push architecture show that the double oscillation frequency is 49.8 GHz, the tuning range is 7.2%, and the phase noise is −80.52 dBc/Hz @1MHz. The chip areas of 24-GHz LC VCO and 48-GHz push–push LC VCO are 0.68 mm × 0.69 mm and 0.7 mm × 0.7 mm, respectively. Full article

This paper presents an RF switch chip with a wide operating bandwidth from 6 to 18 GHz, designed for RF front-end applications in mobile communications. A series-parallel topology combined with a stacked transistor structure was employed to improve power handling while maintaining low insertion loss and high isolation. To further optimize isolation and return loss, LC resonant circuits were introduced by utilizing off-state transistors as capacitive elements. Compared to existing designs, the proposed switch achieved an improved trade-off between bandwidth, power capacity, and port performance. Measurement results showed insertion loss below 1.917 dB, isolation above 38.839 dB, return loss better than 13.075 dB, and 1 dB input compression point above 32 dBm at 12 GHz, confirming the effectiveness and novelty of the broadband design. Full article

Electrospray mass spectrometry off-line profiling monitored the recovery of targeted indole alkaloids from a fortified crude extract of Catharanthus roseus (790 mg) using semi-preparative high-performance countercurrent chromatography (HPCCC) fractionation. Visualization of selected single-ion traces projected the HPCCC molecular weight elution profile. Experimental partition-ratio values K_D and peak widths for detected metabolites were determined. Structural characterization of metabolites and co-elution effects were monitored in the scan range m/z 100–2000. In this study, the biphasic solvent system containing n-hexane–n-butanol–water with 0.5% ion-pair reagent trifluoro-acetic acid [1:1:2, v/v/v] was used based on partition ratio K_D-value liquid chromatography–electrospray ionization–mass spectrometry (LC-ESI-MS) analysis prediction. The monitoring of target ions resulted in the isolation of six major concentrated indole alkaloids (akuammicine, catharanthine, perivine, vindoline, vindorosine, and 19R-vindolinine), which were fully elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Full article

This study aims to unveil the marine invertebrate Sidnyum elegans, a Mediterranean ascidian, as a natural resource for the early development of new treatments for triple-negative breast cancer (TNBC). Nine different fractions obtained via medium-pressure liquid chromatography (MPLC) of the butanol-soluble material of the ascidian were evaluated in proliferating MDA-MB-231 cells in a range of 10–50 µg/mL. Among them, the SEB-5 fraction was found to be the most effective in reducing cell proliferation and concomitantly inducing apoptosis, revealed via MTT assay and FACS analysis using Annexin V/PI dual staining. Furthermore, we investigated the effect of this fraction on cell cycle phases, revealing that SEB-5 can arrest the cells in the G0/G1 phase. This latter effect was then confirmed via transcriptomic analysis, showing that treatment with SEB-5 reduced the expression of cyclinB1, CDC25a, and CDK1. Finally, to evaluate the potential antimetastatic effect of SEB-5, a wound-healing assay was performed showing the ability of SEB-5 to reduce MDA-MB-231 cell migration. The chemical characterization of SEB-5 components was performed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS/MS) and nuclear magnetic resonance (NMR) spectroscopy. This analysis revealed the presence of a terpenoid and polyketide-like compounds, including the alkyl sulfate 1 and phosphoeleganin 2, along with three novel phosphoeleganin-related products 3–5. Full article

Microbial biosurfactants have become increasingly attractive as promising ingredients for environmentally friendly products. The reasons for this are their generally good performance and biodegradability, low toxicity, production from renewable raw materials, and benefits for the environment perceived by consumers. In this study, we investigated the chemical structure and properties of a novel glycolipid from a new biosurfactant-producing strain, Rouxiella badensis DSM 100043^T. Bioreactor cultivation was performed at 30 °C and pH 7.0 for 28 h using 15 g/L glycerol as a carbon source. The glycolipid was successfully purified from the ethyl acetate extract of the supernatant using medium pressure liquid chromatography (MPLC). The structure of the glycolipid was determined by one- and two-dimensional (¹H and ¹³C) nuclear magnetic resonance (NMR) and confirmed by liquid chromatography electrospray ionization mass spectrometry (LC-ESI/MS). NMR analysis revealed the hydrophilic moiety as a glucose molecule and the hydrophobic moieties as 3-hydroxy-5-dodecenoic acid and 3-hydroxydecanoic acid, which are linked with the glucose by ester bonds at the C2 and C3 positions. Surface tension measurement with tensiometry indicated that the glucose–lipid could reduce the surface tension of water from 72.05 mN/m to 24.59 mN/m at 25 °C with a very low critical micelle concentration (CMC) of 5.69 mg/L. Moreover, the glucose–lipid demonstrated very good stability in maintaining emulsification activity at pH 2–8, a temperature of up to 100 °C, and a NaCl concentration of up to 15%. These results show that R. badensis DSM 100043^T produced a novel glycolipid biosurfactant with excellent surface-active properties, making it promising for further research or industrial applications. Full article