Search Results (363)

Rotor equipment material samples with varying degrees of degradation during long-term operation are characterized by lower (up to 17%) corrosion and hydrogen resistance compared to the initial state. The scheme of redistribution of carbides in structural components in the initial state and after long-term operation is presented. The schemes of the turning rotor shaft are visualized, while taking the microstructure features into account. During long-term service, the properties of steels are affected by changes in the parameters of structural components caused by the action of a hydrogen-containing environment. Based on the experimental data, the regression equation and approximation probability R² value describing the change in the electrochemical parameters of 38KhN3MFA rotor steel samples after 200, 225, 250, and 350 thousand hours of operation were obtained. During machining, an increase in hydrogen content was recorded in the chips, especially from degraded areas of the rotor shaft (up to 7.94 ppm), while in undegraded zones, it ranged from 2.1 to 4.4 ppm. A higher hydrogen concentration was correlated with increased surface roughness. The use of LCLs improved surface quality by 1.5 times compared to LCL_p. Dispersion caused by degradation contributed to hydrogen accumulation and changed the nature of material destruction. After repair, the rotors demonstrated stable operation for over 25 thousand hours, with no reappearance of critical defects observed during scheduled inspections. Full article

The voltage source converters convert the DC to AC in order to interface distributed generation units with the utility grid, typically using an LCL filter to smooth the modulated wave. However, the LCL filter can introduce resonance, potentially cause instability, and necessitate the use of damping techniques, such as active damping, which utilizes feedback from the current control loop to suppress resonance. This paper presents a comprehensive performance assessment of four current-feedback-based active damping (AD) techniques—converter current feedback (CCF), CCF with capacitor current feedback (CCFAD), grid current feedback (GCF), and GCF with capacitor current feedback (GCFAD)—under a broad range of realistic grid disturbances and low switching frequency conditions. Unlike prior works that often analyze individual feedback strategies in isolation, this study highlights and compares their dynamic behavior, robustness, and total harmonic distortion (THD) in eight operational scenarios. The results reveal the severe instability of GCF in the absence of damping and the superior inherent damping property of CCF while demonstrating the comparable effectiveness of GCFAD. Moreover, a simplified yet robust design methodology for the LCL filter is proposed, enabling the filter to maintain stability and performance even under significant variations in grid impedance. Additionally, a sensitivity analysis of switching frequency variation is included. The findings offer valuable insights into selecting and implementing robust active damping methods for grid-connected converters operating at constrained switching frequencies. The effectiveness of the proposed methods has been validated through both MATLAB/Simulink simulations and hardware-in-the-loop (HIL) testing. Full article

Background: Aicardi-Goutières Syndrome (AGS) is a rare neuroinflammatory condition characterized by early-onset symptoms that extend outside the nervous system. Due to the rarity of the disease, the pathogenesis is not well understood, and its diagnosis and treatment remain elusive. We recently demonstrated mitochondrial abnormalities and increased reactive oxygen species (ROS) levels in lymphoblastoid cell lines (LCLs) derived from RNASEH2B- and RNASEH2A-mutated AGS patients. On this background, we turned our attention to metformin, the first-choice drug for type 2 diabetes, as a possible treatment acting on oxidative stress in RNASEH2-mutant AGS cells. Methods and Results: By means of flow cytometry, we found that metformin treatment significantly decreases ROS production in RNASEH2B- and RNASEH2A-mutated AGS LCLs. Of note, metformin treatment reduces the green JC-1 monomeric signal and, concurrently, increases the red JC-1 signal in both mutated LCLs, accounting for restoration of the mitochondrial membrane potential. Immunofluorescence staining shows a decrease in 8-oxoG levels only in RNASEH2B- mutated AGS LCLs. Finally, the significant upregulation of Forkhead Box O3 (FOXO3), cytochrome C somatic (CYCS), and superoxide dismutase 2 (SOD2) mRNA levels in RNASEH2B-mutated AGS LCLs after metformin treatment points to FOXO3 signaling as a possible mechanism to reduce oxidative stress. Conclusions: In conclusion, even if these pilot results need to be confirmed on a larger cohort, we shed light on metformin treatment as a valid approach to ameliorate oxidative stress-related inflammation in AGS patients. Full article

LCL (inductor–capacitor–inductor) filters are widely used in grid-connected inverters, particularly in electric vehicle (EV) battery-to-grid systems, for harmonic suppression but introduce resonance issues that compromise stability. This study presents a novel sensorless active damping strategy based on μ-synthesis control for EV batteries connected to the grid via LCL filters, eliminating the need for additional current sensors while preserving harmonic attenuation. A comprehensive state–space and process noise model enables accurate capacitor current estimation using only grid current and point-of-common-coupling (PCC) voltage measurements. The proposed method maintains robust performance under ±60% LCL parameter variations and integrates a proportional-resonant (PR) current controller for resonance suppression. Hardware-in-the-loop (HIL) validation demonstrates enhanced stability in dynamic grid conditions, with total harmonic distortion (THD) below 5% (IEEE 1547-compliant) and current tracking error < 0.06 A. Full article

Localised cutaneous leishmaniasis (LCL) is a common neglected tropical disease in Ethiopia, which is mainly treated with intralesional (IL) pentavalent antimonial such as sodium stibogluconate (SSG) and/or cryotherapy. Both treatments are painful, and studies are lacking on the pain associated with these or affected individuals’ experiences of them. A cross-sectional, observational study was conducted at ALERT Comprehensive Specialized Hospital, Addis Ababa/Ethiopia. The socio-demographic and clinical data of individuals affected by LCL receiving IL SSG and/or cryotherapy was gathered, and their treatment was observed. Participants quantified their treatment-associated pain using the Wong–Baker Pain Scale. Health-related quality of life was measured using the (Children’s) Dermatology Life Quality Index. Adverse effects, participant experiences with local therapies, and dermatologists’ experiences and opinions of local LCL treatment were assessed using structured questionnaires. Of the thirty-six individuals with LCL included (64% male, 14% children), 52% reported a treatment-associated pain score ≥ 8. Cryotherapy administered with a cotton bud was associated with lower pain scores ≤ 6 (odds ratio: 0.15, 95% confidence interval: 0.03–0.89) compared to a cryotherapy spray device. There was wide variation in treatment administration. Local LCL treatment is painful, and most individuals experience significant pain. This study highlights the need for less painful but effective treatments, structured training, and clear standard operating procedures. Full article

The eight new copper(II), nickel(II), zinc(II), and iron(III) coordination compounds [Cu(L)Cl]₂ (1), [Cu(L)Br]₂ (2), [Cu(L)(NO₃)]₂ (3), [Cu(phen)(L)]NO₃ (4), [Ni(HL)₂](NO₃)₂·H₂O (5), [Ni(HL)₂]Cl₂ (6), [Zn(L)₂]·0.125H₂O (7), and [Fe(L)₂]Cl (8), where HL stands for 2-benzoylpyridine 4-allylthiosemicarbazone, were synthesized and characterized. ¹H, ¹³C NMR, and FTIR spectroscopies were used for characterization of the HL thiosemicarbazone. The elemental analysis, the FTIR spectroscopy, and the study of molar electrical conductivity were used for characterization of the coordination compounds 1–8. Also, the crystal structures of HL, its salts ([H₂L]Cl; [H₂L]NO₃), and complexes 1, 3, 5, 7, and 8 were determined using single-crystal X-ray diffraction analysis. Complexes 5, 7, 8 have mononuclear structures, while copper(II) complexes 1 and 3 have a dimeric structure with the sulfur atoms of the thiosemicarbazone ligand bridging two copper atoms together. Thiosemicarbazone HL and the complexes manifest antibacterial and antifungal activities. The studied substances are more active towards Gram-negative bacteria than towards Gram-positive bacteria and fungi. Complex 1 is the most active one towards Gram-positive bacteria and C. albicans, while the introduction of 1,10-phenanthroline into the inner sphere enhances the activity towards Gram-negative bacteria. Thiosemicarbazone and complexes 6 and 7 manifest antiradical activity that exceeds the activity of Trolox. HL and complex 1 manifest antiproliferative activity towards HL-60 cancer cells which exceeds the activity of their analogs with 2-formyl-/2-acetylpyridine 4-allylthiosemicarbazone. Full article

The quality of a grid-injected current in LCL-type grid-connected inverters (GCI) degrades under ultra-weak grid conditions, posing serious challenges to the stability of the GCI system. For this purpose, the sliding mode control (SMC) approach has been utilized to integrate DC energy seamlessly into the grid. The control performance of a GCI equipped with an LCL filter is greatly reduced when it is operating in a power grid with varying impedance and fluctuating grid voltages, which may result in poor current quality and possible instability in the system. A non-singular double integral terminal sliding mode (DIT-SMC) control is presented in this paper for a three-phase GCI with an LCL filter. The proposed method is presented in the α, β frame of reference without adopting an active or passive damping approach, reducing the computational burden. MATLAB/Simulink Version R2023b is leveraged to simulate the mathematical model of the proposed control system. The capability of the DIT-SMC method is validated through the OPAL-RT hardware-in-loop (HIL) platform. The effectiveness of the proposed method is first compared with SMC and integral terminal SMC, and then the DIT-SMC method is rigorously analyzed under resonance frequency events, grid impedance variation, and grid voltage distortions. It is demonstrated by the experimental results that the proposed control is highly effective in delivering a high-quality current into the grid, in spite of the simultaneous occurrence of power grid impedance variations in 6 mH and large voltage distortions. Full article

Multi-channel LED drivers are crucial for high-power lighting applications. Maintaining a constant average forward current is essential for stable LED luminous intensity, necessitating drivers capable of consistent current delivery across wide operating ranges. Meanwhile, achieving precise current sharing among channels without incurring high costs and system complexity is a significant challenge. Leveraging the constant-current characteristics of the LCL-T network, this paper presents a multi-channel DC/DC LED driver comprising a full-bridge inverter, a transformer, and a passive resonant rectifier. The driver generates a high-frequency AC bus with series-connected diode rectifiers, a structure that guarantees excellent current sharing among all output channels using only a single control loop. Fully considering the impact of higher harmonics, this paper derives an exact solution for the output current. A step-by-step parameter design methodology ensures soft switching and enhanced switch utilization. Finally, experimental verification was conducted using a prototype with five channels and 200 W, confirming the correctness and accuracy of the theoretical analysis. The experimental results showed that within a wide input voltage range of 380 V to 420 V, the driver was able to provide a stable current of 700 mA to each channel, and the system could achieve a peak efficiency of up to 94.4%. Full article

With the advancement in power electronics technology, variable-frequency drives have been widely adopted for motor operation due to their inherent benefits: control performance, extending equipment life, and energy savings. The most used technique is Sine Pulse Width Modulation, as it solely requires the modification of the reference signal (sine wave). However, Space Vector Pulse Width Modulation offers lower total harmonic distortion. Therefore, this study presents a technique for the control of induction motors operating in open-loop mode, utilizing a two-level voltage source inverter with a frequency range of 31 to 300 Hz. The proposed control system is modified to encompass between 930 and 1848 switching periods, varying the number of switching periods along with the frequency variation. This approach allows the use of a single LCL filter across the whole frequency spectrum. It is adapted for implementation in an 8-bit microcontroller, which has its inherent limitations, yet it achieves performance levels similar to those found in high-level processors like FPGAs and DSPs. The signals generated by the microcontroller are captured by a DAQ card and input into a MATLAB/Simulink model to observe and analyze the performance of the proposed control system. Full article

This paper investigates the system architecture and circuit topology of grid-connected inverters with embedded energy storage (EES), encompassing their modulation strategies and control methodologies. A mathematical model for an EES grid-connected inverter is derived based on capacitor current feedback control, from which the expression for the inverter’s output impedance is obtained. Building on this foundation, this study analyzes the influence of control parameters—such as the proportional coefficient, resonant coefficient, and switching frequency—on the inverter’s output impedance. Subsequently, the stability of single and multiple inverter grid-connected systems under various operating conditions is assessed using impedance analysis and the Nyquist criterion. Finally, the validity of the stability analysis based on the established mathematical model is verified through simulations conducted on the Matlab/Simulink platform, where models for both a single inverter and a two-inverter grid-connected system are constructed. Full article

Robotic cadaveric testing provides a controlled approach to studying knee ligament biomechanics under continuous motion, addressing limitations in static or mechanical loading testing. Our study describes an alternative method for soft-tissue strain measurement, followed by an investigation of this method on knee ligament strain and joint kinematics using a six-degree-of-freedom robotic system equipped with force and torque sensors. Six cadaveric knee specimens underwent controlled 90° flexion cycles, with uniaxial strain gauges sutured to the ACL, PCL, MCL, and LCL for strain measurement. Results indicate that the LCL exhibited the highest extension at 1.63 mm, while the ACL showed minimal extension at 0.09 mm. The MCL were at −0.76 mm and PCL at −1.76 mm contraction, suggesting a stabilizing function under flexion. Varus torque at 2.18 Nm at 90° flexion correlated with LCL strain, and PCL translation variability reflected its multi-planar engagement. These findings confirm ligament-specific strain responses under dynamic loading, highlighting that the LCL and PCL undergo the most significant length changes. Full article

Pseudomonas aeruginosa is a gram-negative opportunistic pathogen that poses a significant threat due to its increasing multidrug resistance, particularly in clinical settings. This study aimed to isolate and characterize a novel bacteriophage, phiLCL12, from hospital wastewater and evaluate its potential in combination with antibiotics to combat P. aeruginosa infections and biofilm formation. Transmission electron microscopy revealed that phiLCL12 possesses a long contractile tail. The isolated phage exhibited a broad host range of 82.22% and could adsorb up to 98% of its target within 4 min. It was effective against multidrug-resistant strains at both high and low multiplicities of infection (MOIs) levels in lysis tests. Taxonomic classification was determined using PhaGCN2 and Whole genomic analysis, and the results identified phiLCL12 as a member of the Pbunavirus. In vitro experiments demonstrated that phiLCL12 significantly enhanced biofilm clearance and inhibited biofilm formation when combined with sub-inhibitory concentrations of imipenem. Furthermore, in vivo experiments using a zebrafish model showed that phage–antibiotic synergy (PAS) improved survival rate compared to antibiotic treatment alone. This study demonstrates that phiLCL12 is effective in both eradicating and preventing P. aeruginosa biofilm formation. The combination of phiLCL12 and imipenem provides a synergistic effect, significantly enhancing survival outcomes in a zebrafish model. These findings highlight the potential of phage–antibiotic synergy as a promising therapeutic strategy against biofilm-associated infections. Full article

Background/Objective: Salinity is a growing problem affecting a large portion of global agricultural land, particularly in areas where water resources are scarce. The objective of this study was to provide physiological and molecular information on salt-tolerant citrus rootstocks to mitigate the detrimental effects of salinity on citriculture. Methods: Ten accessions belonging to eight Citrus species and four to Poncirus trifoliata Raf. were tested for salinity tolerance (0 and 15 mM NaCl for 1 year) in terms of vegetative and Cl⁻ tissue distribution traits. In addition, most accessions were evaluated for leaf Na⁺ and other cations. Results: All salt tolerant accessions tended to restrict the leaf Cl⁻ content, although in a lower degree than the Cleopatra mandarin. However, differences in their ability to restrict leaf [Na⁺] were evident, contributing to a classification of trifoliate and sour orange accessions that matched their genotypic grouping based on allele sharing at a marker targeting candidate gene coding for the NPF5.9 transporter within LCL-6 quantitative trait locus. Conclusions: Our markers targeting LCl-6 candidate genes coding for NPF5.9, PIP2.1, and CHX20 (citrus GmSALT3 ortholog) could be efficient tools for managing the detected salt tolerance diversity in terms of both Cl⁻ and Na⁺ homeostasis in rootstock breeding programs derived from these species, in addition to Citrus reshni. Full article

The high cost of platinum (Pt) catalysts impedes the widespread commercialization of proton exchange membrane fuel cells (PEMFCs). Reducing Pt loading will increase local oxygen transport resistance ($R_{\mathrm{Pt}}^{{\mathrm{O}}_2}$) and decrease performance. Due to the oxygen transport resistance, the reactants in the cathode catalyst layer (CCL) are not evenly distributed. The gradient structure can cooperate with the unevenly distributed reactants in CL to enhance the Pt utilization. In this work, a one-dimensional gradient CCL model considering $R_{\mathrm{Pt}}^{{\mathrm{O}}_2}$ is established, and the optimal gradient structure is optimized by combining the artificial neural network (ANN) model and the genetic algorithm (GA). The optimal structure parameters of non-gradient CCL are l_CL equal to 8.86 μm, r_C equal to 36.82 nm, and I/C equal to 0.48, with the objective of maximum current density (I_max); l_CL equal to 4.24 μm, r_C equal to 36.60 nm, and I/C equal to 0.76, with the objective of maximum power density (P_max). For the gradient CCL, the best gradient distribution enables Pt loading to increase from the membrane (MEM) side to the gas diffusion layer (GDL) side and the ionomer volume fraction to decrease from the MEM side to the GDL side. Full article

The use of certification systems in agriculture mitigates greenhouse gas (GHG) emissions and promotes sustainable low-carbon practices. Their implementation contributes to the rational use of resources and results in the development of a human-centric economy that prioritizes people’s actual needs towards sustainable economic growth. Some low-carbon certification systems for agricultural products have been developed in European Union (EU) countries and elsewhere; however, their reliability in assessing agricultural emissions at the farm level and the anticipated benefits are not yet adequately justified. This review paper presents and discusses the most important existing certification systems, namely, Solagro, Label bas Carbone/LCL, LEAF Marque Standard, and Wineries for Climate Protection, the one being developed in the frame of the ClimaMED LIFE project, and the one developed almost 10 years ago in the Republic of Korea. The structure of these systems and their benefits and challenges are discussed. More emphasis is given to the EU certification schemes and the impact they may have towards meeting the targets of the Green Deal, which aims to reduce GHG emissions at least 55% by 2030 compared to 1990 levels and make Europe climate neutral by 2050. Full article