Low Intensity Research Articles

The Role of the Aleutian Low in the Relationship between Spring Pacific Meridional Mode and Following ENSO

Abstract The spring Pacific meridional mode (PMM) is an important precursor of El Niño–Southern Oscillation (ENSO). However, recent studies reported that only about half of the spring PMM events were followed by ENSO events. This study examines the role of internal climate variability in modulating the impact of PMM on ENSO using 100-member ensemble simulations of the Max Planck Institute Earth System Model (MPI-ESM). The relationship between spring PMM and following winter ENSO shows a large spread among the 100 members. The variation of spring Aleutian low (AL) intensity is identified to be an important factor modulating the PMM–ENSO relation. The spring AL affects the PMM–ENSO relationship by modifying PMM-generated low-level zonal wind anomalies over the tropical western Pacific. The strengthening of the spring AL is accompanied by westerly wind anomalies over the midlatitude northwestern Pacific, leading to sea surface temperature (SST) cooling there via an enhancement of upward surface heat flux. This results in increased meridional SST gradient and leads to northerly wind anomalies over the subtropical northwestern Pacific, which turn to surface westerly wind anomalies after reaching the equatorial western Pacific due to the conservation of potential vorticity. Thus, the low-level westerly (easterly) wind anomalies over the tropical western Pacific associated with the positive (negative) spring PMM were strengthened (weakened), which further contributes to an enhanced (a weakened) PMM–ENSO relation. The mechanism for the modulation of the AL on the spring PMM–ENSO relationship is verified by a set of AGCM simulations. This study suggests that the condition of the spring AL should be considered when predicting ENSO on the basis of the PMM. Significance Statement Spring Pacific meridional mode (PMM) is a predictor of ENSO, but not all spring PMM events are accompanied by the occurrence of ENSO events. This study aims to explore the influence of internal climate variability on the relationship between spring PMM and following ENSO. It is revealed that the Aleutian low exerts a crucial modulation on the spring PMM–ENSO relationship. The underlying physical mechanisms for the impact of the Aleutian low on the relationship between spring PMM and ENSO are further examined. The results of this study have important implications for improving the prediction of ENSO.

Tracking the nitrogen leaching from different sources in bioretention systems with a process-based model

Bioretention systems are a typical stormwater management technology intended to reduce runoff and non-point source pollution. Multiple sources can contribute to nitrogen (N) leaching from bioretention systems, including the current rainfall-runoff (i.e., immediate leaching), recent rainfall-runoffs (i.e., fast leaching) and long-ago legacy N (i.e., slow leaching), however, there is a lack of methods to quantify these contributions. Here, a process-based Bioretention System (BRS) model for N leaching simulations was verified with artificially-labeled 15N data besides N data to reduce predictive uncertainties. The BRS model was then coupled with an Nitrogen Source Apportionment (NSA) module for N leaching tracking to quantify the contributions from different sources. Results from a bioretention system showed that additional 15N data reduced the predictive uncertainty of total N (TN) concentrations by 23 %. Immediate leaching, fast leaching and slow leaching increased, decreased and remained steady during the leaching process and accounted for 79.54 ± 5.08 %, 2.80 ± 1.74 % and 17.66 ± 4.11 % of N leaching, respectively. The dominant immediate leaching can be significantly weakened by a submerged zone, a shorter antecedent dry periods (ADP), a lower rainfall intensity or influent concentration. This study provides a framework to quantify N leaching from multiple sources with implications for long-term N leaching management.

Luminescent properties of Tm3+-activated phosphors with rosiaite structure

A series of solid solutions with compositions of La1-xTmxGa0.5Sb1.5O6 (x = 0.03, 0.05, 0.1) and La1-x-y-zTmxTbyDyzGa0.5Sb1.5O6 (x = 0.04, 0.07, 0.1; y = 0.04, 0.07, 0.1; z = 0.04, 0.04, 0.06) has been synthesized. It is shown that all the compounds have rosiaite structure (PbSb2O6, sp.gr. P-31m). Morphology, spectral-luminescent characteristics and color coordinates of the samples were studied. It was found that luminescence spectrum of thulium-activated samples recorded upon 351 nm excitation is typical for Tm3+ ions. At the same time, under excitation by radiation with λ = 457 nm and a power density of J = 4.7 kW/cm2, broadband thermal emission is observed, against which the bands corresponding to the 1G4→3H6, 1G4→3F4, 3F4→3H6 и 3H4→3H6 transitions of Tm3+ are detected. The luminescence spectra of the samples co-activated with Tm3+, Tb3+ and Dy3+are characterized by a relatively low intensity of the Tm3+ emission, which may be due to efficient energy transfer processes between Tb3+ and Dy3+ ions. A shift from the blue to the green color regions is observed in the color coordinates of the co-activated samples upon 351 nm excitation. Radiation with λ = 457 nm led to a shift in the emission colour to orange. Thus, it is shown that it is possible to create phosphors emitting in the blue, green and orange spectral regions by changing the wavelength of exciting radiation and activator composition for compounds with rosiaite structure.

Capacitive and Efficient Near-Infrared Stimulation of Neurons via an Ultrathin AgBiS2 Nanocrystal Layer.

Colloidal nanocrystals (NCs) exhibit significant potential for photovoltaic bioelectronic interfaces because of their solution processability, tunable energy levels, and inorganic nature, lending them chemical stability. Silver bismuth sulfide (AgBiS2) NCs, free from toxic heavy-metal elements (e.g., Cd, Hg, and Pb), particularly offer an exceptional absorption coefficient exceeding 105 cm-1 in the near-infrared (NIR), surpassing many of their inorganic counterparts. Here, we integrated an ultrathin (24 nm) AgBiS2 NC layer into a water-stable photovoltaic bioelectronic device architecture that showed a high capacitive photocurrent of 2.3 mA·cm-2 in artificial cerebrospinal fluid (aCSF) and ionic charges over 10 μC·cm-2 at a low NIR intensity of 0.5 mW·mm-2. The device without encapsulation showed a halftime of 12.5 years under passive accelerated aging test and did not show any toxicity on neurons. Furthermore, patch-clamp electrophysiology on primary hippocampal neurons under whole-cell configuration revealed that the device elicited neuron firing at intensity levels more than an order of magnitude below the established ocular safety limits. These findings point to the potential of AgBiS2 NCs for photovoltaic retinal prostheses.

Seismic Fragility and Reliability of Base-Isolated Structures with Regard to Superstructure Ductility and Isolator Displacement Considering Degrading Behavior

ABSTRACT The present study investigates the effects of the degradation of mechanical properties (pinching, stiffness degradation, and strength degradation) in load-deformation relationship of the superstructures equipped with friction pendulum systems on the seismic fragility and reliability results. An equivalent two-degree-of-freedom model is employed, in which the Bouc-Wen hysteretic model characterizes the inelastic behavior of both the superstructure and the isolator. To examine a wide variety of system combinations with different structural properties and degradation severity, a comprehensive parametric study is performed. Incremental dynamic analyses are carried out to develop fragility functions. Subsequently, the seismic reliability of both the superstructure and the isolation level is assessed. Results indicate that the negative effects of degrading behavior are more prominent in stiff superstructures as it significantly decreases structural capacity and reliability indices. It is demonstrated that the system is primarily influenced by pinching behavior rather than degradation in strength and stiffness, especially at low intensity levels that correspond to lower limit-states. In the majority of investigated systems, the seismic demand in the isolator decreases when superstructures undergo degrading behavior. Overall, such effects should be considered in the reliability-based design procedure to attain design consistency in terms of reliability. The results of this paper that account for the degrading effects enable reliable estimations of key parameters essential for the design of the superstructure and the isolator.

Spatial Heterogeneity and Driving Mechanisms of Cultivated Land Intensive Utilization in the Beibu Gulf Urban Agglomeration, China

Cultivated land intensive utilization (CLIU) exhibits spatial heterogeneity that is influenced by both natural and anthropogenic factors, with land dissected into different scale systems; however, CLIU has not yet been systematically explored. This study takes the Beibu Gulf urban agglomeration, a national-level model area for integrated land and sea development in China, as an example to investigate the spatial heterogeneity of CLIU and explore its driving factors through multiple econometrical and geographical methods, including identifying its underlying mechanisms. The results indicate that (1) the CLIU index is 0.334, its Gini coefficient is 0.183, and its comprehensive level has a low intensity and obvious spatial nonequilibrium characteristics. Hypervariable density (50.33%) and the intraprovincial gap (45.6%) are the main sources. (2) Among the independent effects of single factors, the multiple cropping index (0.57), labor force index (0.489), and intensification of construction land (0.375) exert the most influence on CLIU spatial variation. The interaction effects of two factors primarily manifested as nonlinear enhancements, with the interaction between the labor force index and multiple cropping index being particularly noteworthy (0.859). (3) The geographically weighted regression coefficients reveal that temperature (0.332), multiple cropping index (0.211), and labor force index (0.209) have relatively large and positive impacts on CLIU, while slope (−0.1), precipitation (−0.087), and population urbanization (−0.039) have relatively small and negative impacts; all factors exhibit spatial nonstationarity. The spatial heterogeneity of CLIU in the Beibu Gulf urban agglomeration is characterized by patterns’ nonequilibrium and factors’ nonstationarity. The driving mode of multiple factors on CLIU is manifested as follows: natural factors of cropland utilization provide basic guarantees, internal factors of CLIU provide positive enhancement, and external factors of land intensive utilization provide auxiliary promotion.

Coherent beam combining of two all-PM thulium-doped fiber chirped pulse amplifiers

In this paper, we report a coherent beam combining (CBC) system that involves two thulium-doped all-polarization maintaining (PM) fiber chirped pulse amplifiers. Through phase-locking the two channels via a fiber stretcher by using the stochastic parallel gradient descent (SPGD) algorithm, a maximum average power of 265 W is obtained, with a CBC efficiency of 81% and a residual phase error of λ/17. After de-chirping by a pair of diffraction gratings, the duration of the combined laser pulse is compressed to 690 fs. Taking into account the compression efficiency of 90% and the main peak energy proportion of 91%, the corresponding peak power is calculated to be 4 MW. The laser noise characteristics before and after CBC are examined, and the results indicate that the CBC would degrade the low frequency relative intensity noise (RIN), of which the integration is 1.74% in [100 Hz, 2 MHz] at the maximum combined output power. In addition, the effects of the nonlinear spectrum broadening during chirped pulse amplification on the CBC efficiency are also investigated, showing that a higher extent of pulse stretching is effective in alleviating the spectrum broadening and realizing a higher output power with decent combining efficiency.Graphical

Fabrication of a coral-like barium titanate nano-piezoelectric coating and its effect on promoting osteogenic differentiation of bone marrow mesenchymal stem cell in vitro

Objective: To investigate the biocompatibility of coral-like barium titanate nano-piezoelectric coatings and the influence of ultrasound-excited piezoelectric effect on the early osteogenic differentiation. Methods: The barium titanate nano-piezoelectric coating (the coating group) was prepared on the surface of titanium metal by anodic oxidation, hydrothermal reaction and high-temperature annealing, and polished titanium specimens were used as control group. The surface morphology, composition, and crystal phase and hydrophilicity of the two groups of titanium specimens were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and contact angle meter. The piezoelectric properties of the materials were characterized by piezoresponse force microscopy (PFM). Rat bone marrow mesenchymal stem cells (BMSC) were cultured and identified and seeded the surface of titanium specimens in two groups. The cells seeded on blank culture plates were used as blank group. After low intensity pulsed ultrasound intervention, cell proliferation and live/dead staining were detected to evaluate cytocompatibility of the coatings. Alkaline phosphatase (ALP) activity of each group was detected by ALP staining kit, and the expression of osteogenesis-related genes [integrin, bone morphogenetic protein 2 (BMP-2), Runt-related transcription factor 2 (RUNX2)] was detected by real-time fluorescent quantitative PCR (RT-qPCR) to evaluate the effect of the coating on promoting the early osteogenic differentiation of BMSC. Results: The surface of titanium specimens in the coating group showed a uniform coral-like morphology, and the diameter of the coral tentacles was 70-100 nm. The main component was tetragonal barium titanate. The surface hydrophilicity of the coating group (water contact angle 10.12°±0.93°) was significantly better than that of the control group (water contact angle 78.32°±0.71°) (F=10 165.91, P<0.001). The coating has a stable piezoelectric property with a piezoelectric constant of about 5 pC/N. Cell experiments showed that, with or without ultrasound, the cell proliferation activity of the coating group was significantly lower than that of the blank group and the control group on the third day (P<0.05). On the fifth day, with or without ultrasound, there was no significant difference in cell proliferation activity between the three groups (P>0.05). After 7 days of culture, the ALP activity of the coating group was significantly higher than that of the blank group and the control group (P<0.05). The results of RT-qPCR showed that the mRNA expression of integrin and BMP-2 in the coating group with ultrasound was significantly higher than that in the other groups with ultrasound, and was higher than that of the coating group without ultrasound (P<0.05). The expression of integrin mRNA in the control group with ultrasound was significantly higher than that in the control group without ultrasound (P<0.05). The expression of RUNX2 mRNA in the coating group with ultrasound was significantly higher than that in the coating group without ultrasound (P<0.05). Conclusions: The coral-like barium titanate nano-piezoelectric coating exhibits favorable biocompatibility and stable piezoelectric property, and facilitates the early osteogenic differentiation of BMSC under the excitation of low-intensity pulsed ultrasound.

An examination of urban green spaces usage behaviours and self-perceived mental health benefits: findings from two urban green neighbourhoods in Pakistan

ABSTRACT The present study examined urban green space users’ self-perceived mental health benefits of visiting green spaces in Pakistan – one of South Asia’s rapidly urbanizing countries. By using a quantitative-based cross-sectional survey, 384 participants were surveyed in green urban neighbourhood settings. It was found that most green space users believed that their visits to green spaces have at least some positive effects on the different parameters of their mental health, such as stress or anxiety levels, mood, energy levels, optimism levels, confidence levels, or concentration levels, among others. The study explored that the frequency and duration of green space usage and intensity of activity performed in the green space have an important role in determining the degree of the self-perceived mental health benefits of visiting green spaces, suggesting the importance of green interventions, including physical changes in the environment and social promotion activities to encourage green space usage among urban dwellers. Moreover, the study revealed low green space usage and activity intensity levels among certain sub-population groups compared to others, such as women, young adults, or the elderly, highlighting the need to ensure equity of access to green spaces for all sub-population groups and prioritize them in intervention strategies.

Exploring natural genetic diversity in a bread wheat multi-founder population: Dual imaging of photosynthesis and stomatal kinetics.

A better understanding of crop phenotype under dynamic environmental conditions will help inform the development of new cultivars with superior adaptation to constantly changing field conditions. Recent research has shown that optimising photosynthetic and stomatal conductance traits holds promise for improved crop performance. However, standard phenotyping tools such as gas-exchange systems are limited by their throughput. In this work, a novel approach based on a bespoke gas-exchange chamber allowing combined measurement of the quantum yield of photosystem II (PSII) with an estimation of stomatal conductance via thermal imaging, was used to phenotype a range of bread wheat (Triticum aestivum L.) genotypes, that were a sub-set of a multi-founder experimental population. Datasets were further supplemented by measurement of photosynthetic capacity and stomatal density. First, we showed that measurement of stomatal traits using our dual imaging system compared to standard IRGA methods showed good agreement between the two methods (R2=0.86) for the rapidity of stomatal opening (Ki), with the dual-imager method resulting in less intra-genotype variation. Using the dual-imaging methods, and traditional approaches we found broad and significant variation in key traits, including photosynthetic CO2 uptake at saturating light and ambient CO2 concentration (Asat), photosynthetic CO2 uptake at saturating light and elevated CO2 concentration (Amax), the maximum velocity of Rubisco for carboxylation (Vcmax), time for stomatal opening (Ki), and leaf evaporative cooling. Anatomical analysis revealed significant variation in flag leaf adaxial stomatal density. Associations between traits highlighted significant relationships between leaf evaporative cooling, leaf stomatal conductance under low (gsmin) and high (gsmax) light intensity, and the operating efficiency of PSII (Fq'/Fm'), highlighting the importance of stomatal conductance and stomatal rapidity in maintaining optimal leaf temperature for photosynthesis in wheat. Additionally, gsmin and gsmax were positively associated, indicating that potential combination of preferable traits (i.e. inherently high gsmax, low Ki and maintained leaf evaporative cooling) are present in wheat. This work highlights for the first time the effectiveness of thermal imaging in screening dynamic stomatal conductance in a large panel of wheat genotypes. The wide phenotypic variation observed suggested the presence of exploitable genetic variability in bread wheat for dynamic stomatal conductance traits and photosynthetic capacity for targeted optimisation within future breeding programs.

Best Practices to Directly Assess Heterogeneous Singlet Oxygen Photosensitization by Phosphorescence

AbstractLiterature proves that the direct detection of 1O2(1Δg) at the solid gas interface is systematically performed from its phosphorescence using high intensity excitation sources (i.e., lasers), which lead to quasi‐ubiquitous chemical problems, such as sensitizer degradation, and photophysical counter‐active issues such as ultrafast exciton migration, singlet‐singlet and triplet‐triplet annihilation, and thermally activated delayed fluorescence mediated by 1O2(1Δg). To avoid these inconveniences, low excitation intensity is required but leads to serious analytical challenges. The best practices to reliably detect 1O2(1Δg) phosphorescence at various interfaces using a standard excitation source and near‐IR detector. The two main practices consist in a gas purging test for reliable identification of 1O2(1Δg), and in a particularly fine optimization of the angle made by excitation beam versus substrate plane. These practices are applied to porphyrin sensitizers H2TPP and ZnTPP, either neat or physiosorbed on glass, quartz, paper and hospital bandages, graphene oxide (GO), and embedded inside electrospun polystyrene fibers and spin coated poly(methyl methacrylate) films. Porphyrin‐based metal‐organic framework PCN‐224, freshly activated, is also examined.

Diaphragm thickness and mobility elicited by two different modalities of inspiratory muscle loading in heart failure participants: A randomized crossover study.

To analyze diaphragmatic thickness, at end-inspiration and end-expiration, diaphragmatic thickening index and mobility via US under two different modalities of inspiratory muscle loading, in two different modalities of inspiratory muscle loading and different load intensities at full-vital capacity maneuvers and the relationship between diaphragmatic thickness with pulmonary function tests in participants with HF. This randomized crossover trial, enrolled with 17 HF subjects, evaluated diaphragm thickness (Tdi, mm), fractional thickness (TFdi, %), and mobility (mm) US during low and high intensities (30% and 60% of maximal inspiratory pressure-MIP) with two modalities of inspiratory muscle loading mechanical threshold loading (MTL) and tapered flow-resistive loading (TFRL). Both MTL and TFRL produced a increase in Tdi, but only with high intensity loading compared to baseline-2.21 (0.26) vs. 2.68 (0.33) and 2.73 (0.44) mm; p = .01. TFdi was greater than baseline under all conditions, except during low intensity of TFRL. Diaphragm mobility was greater than baseline under all conditions, and high intensity of TFRL elicited greater mobility compared to all other conditions. Additionally, baseline Tdi was moderately correlated with pulmonary function tests. MTL and TFRL modalities elicit similar increases in diaphragm thickness at loads, but only during high intensity loading it was greater than baseline. Diaphragm mobility was significantly greater than baseline under both loads and devices, and at high intensity compared to low intensity, although TFRL produced greater mobility compared to modalities of inspiratory muscle loading. There is an association between diaphragm thickness and pulmonary function tests.

Frequency multiplexed dual-pulse fiber-optic Φ-OTDR for a fading-free distributed fiber sound sensor

Distributed fiber-optic sensor utilizing optical interference signal detection of the Rayleigh backscattering (RBS) light along the fiber under test (FUT) has greatly progressed over the past 20 years. It can now realize real-time sound signal recovery along the FUT with a good fidelity and high sensitivity. However, the performance of the practical distributed fiber-optic sound sensor is still limited by the fading problem, as invalid spatial channels at unknown positions arise due to the low signal intensity at these positions and the resulting near-zero signal-to-noise ratio (SNR). In this paper, we propose a novel, to the best of our knowledge, fading-free fiber sensor structure by incorporating an acousto-optic frequency shift (AOFS) loop into the light source in a dual-pulse phase optical time domain reflectometry (Φ-OTDR). As a result of stable frequency shifting and feedback within the loop, the loop source can output a high-repetition-rate narrow pulse train consisting of multiple separated frequencies. This pulse train is further shaped into two pulse bursts by an acousto-optic modulator (AOM) and an in-balanced fiber-optic Mach–Zehnder interferometer (MZI). The pulse bursts are then sent into the sensing fiber, while the RBS light is detected using an Avalanche photodiode after an erbium-doped fiber amplifier. The experimental results show that the proposed structure is capable of vibration signal recovery with a good SNR all along the FUT. The fading-free performance is evaluated under different AOFS loop gains, showing significant potential in practical fiber sensor network applications.

Establishing equivalent circuits of mounted, high-power VCSEL arrays for iToF cameras

Solid-state indirect time-of-flight (iToF) cameras are crucial to numerous short-to-medium-range applications, owing to their advantages in terms of system integrability and long-term reliability. However, due to the low light intensity, the sensing range of iToF cameras is generally limited to a few meters, which hinders their wide applications. Further increasing the sensing range requires not only higher-power laser diodes but also well-designed driver circuits, which are based on prior knowledge of the laser diodes’ equivalent circuits (ECs). However, experimental studies on ECs of a mounted, high-power vertical-cavity surface-emitting laser (VCSEL) array that comprehensively incorporates all parasitic components, especially parasitic stemming from printed circuit boards (PCBs), remain absent. In this Letter, an 850 nm VCSEL array with a 15.3 W peak power and a 581 MHz bandwidth is fabricated, and more importantly, its EC is experimentally established. Leveraging the accurate EC, a compact iToF camera with a sensing range up to 11.50 m is designed. In addition, a modified precision model is proposed to better evaluate the iToF camera’s performance.

Short- and long-term patient-reported outcomes of subcutaneous implantable cardioverter-defibrillator therapy

Abstract Background The safety and efficacy of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy are well-established. However, there is a paucity of patient-reported outcome data, despite the increasing emphasis on incorporating patients' perspectives into quality care assessments. Current guidelines also recommend evaluating psychological status and addressing distress in defibrillator patients. Purpose This study aims to assess perioperative and postoperative pain during S-ICD implantation, along with patient acceptance during follow-up. We also explore associations between these outcomes, clinical characteristics, and implantation variables. Methods A total of 149 consecutive patients (87% male, mean age 53±13 years, body mass index 27±4 Kg/m², ejection fraction 39±14%) who underwent S-ICD implantation across 11 centers were analyzed. Short-term endpoints included pain during and 6 hours after the procedure. Pain intensity was rated on a 10-point visual analogue scale. Long-term endpoint was S-ICD patient acceptance measured (on a 0-to-100 point scale) by the Florida Patients Acceptance Survey (FPAS) score and its components: Return to Function (RTF), Device-Related Distress (DRD), Positive Appraisal (PA), and Body Image Concerns (BIC). The survey was administered 12 months post-implantation. Results The S-ICD generator was positioned in an intermuscular pocket in 140 (94%) patients. Serratus anterior plane block (SAPB) was performed in 103 (69%) patients. 72 (48%) patients underwent the defibrillation testing. Implantation success was reported in all patients without operative complications. Overall, pain intensity during implantation was 2 [25th-75th percentile: 1-4], and 1 [1-2] for static pain and 2 [1-3] for dynamic pain, 6 hours post-procedure. SAPB was associated with significantly lower pain intensity during implantation (2 [1-3] vs. 4 [2-5], p&amp;lt;0.001) and non-significantly lower values of dynamic pain intensity 6 hours post-procedure (1 [1-2] versus 2 [1-3], p=0.076). The other tested variables, i.e. age, sex, body habitus, ejection fraction, omission of defibrillation testing, were not associated with different pain levels. S-ICD acceptance scores were favorable overall (total FPAS 77 [63-87], RTF 69 [56-88], DRD 25 [10-45], PA 88 [75-100], BIC 13 [0-38]). Patients who underwent SAPB exhibited better RTF (75 [56-88] versus 63 [50-69], p=0.002) and PA (88 [75-100] versus 75 [69-94], p=0.004). Conclusions S-ICD implantation resulted in minimal discomfort, especially with novel anesthetic techniques. Overall, patients reported good acceptance of the S-ICD. Improved acceptance was observed in patients who underwent SAPB, highlighting the significance of enhanced patient implantation experience for long-term outcomes.

The contribution of energy systems during 30-second lower body Wingate anaerobic test in combat sports athletes: Intermittent versus single forms and gender comparison.

Combat sports, encompassing a range of activities from striking and grappling to mixed and weapon-based disciplines, have witnessed a surge in popularity worldwide. These sports are demanding, requiring athletes to harness energy from different metabolic pathways to perform short, high-intensity activities interspersed with periods of lower intensity. While it is established that the anaerobic alactic (ATP-PC) and anaerobic lactic systems are pivotal for high-intensity training sessions typical in combat sports, the precise contribution of these systems, particularly in varied training modalities such as single (SMT) and intermittent (IST) forms of the 30-second Wingate test, remains inadequately explored. This study aims at comparing performance outputs, physiological responses and gender differences during the SMT and IST forms of the 30-second Wingate test. Thirty-three highly trained combat sports athletes (17 women, 16 men; 10 boxing, 8 wrestling, 8 taekwondo and 7 karate) randomly performed SMT and IST. The IST consisted of three 10-second all-out attempts separated by 30 seconds of passive recovery, whereas the SMT was a single 30-second maximal effort. Resting, exercise and post-exercise oxygen uptake and peak blood lactate value were used to determine the metabolic energy demands via the PCr-LA-O2 method. The findings showed that total metabolic energy expenditure (TEE), ATP-PCr system contribution and the output of mechanical variables were higher in the IST than in the SMT form (all p<0.001). In contrast, the contribution of glycolytic and oxidative systems was higher in the SMT form (all p<0.001). However, exercise form and gender interaction were not significant (p>0.05). In combat sports, performance is not only determined by physiological and technical skills but also by metabolic energy input and efficiency. Therefore, our results can provide a comparison regarding the effects of exercise type and gender on metabolic energy metabolism to design the training of combat sports athletes.

#2865 The impact of glomerular C3 deposition in membranous nephropathy prognosis

Abstract Background and Aims Membranous nephropathy (MN) is one of the most frequent causes of nephrotic syndrome in non-diabetic adults. Studies on MN have suggested a preponderant role of the complement. C3 deposits are common in primary and secondary MN and appear to be related to increased proteinuria. The prognostic role of proteinuria is well established, but the importance of C3 glomerular deposition in disease course is not clear. Our study aims to investigate the role of glomerular C3 deposition in the evolution of membranous nephropathy. Method We conducted a single-center retrospective study including 39 patients with histological diagnosis of MN. The patients were assembled in two groups according C3 deposition intensity in kidney biopsy: low intensity (C3+) and high intensity (C3 2 or more ++). The primary outcome was the development of end-stage kidney disease (ESKD). The rate of remission, the rate of relapse and a decreased of at least 30% of the estimated glomerular filtration rate (eGFR) was defined as secondary outcomes. Results Thirty-nine patients were included, 26 (66.7%) were male with a mean age at biopsy of 54 ± 17.5 years. Twenty-six (66.7%) patients had hypertension at diagnosis and four patients had a thrombotic event. The mean eGFR was 88.7 ± 34.3 ml/min/1.73 m2, and median UPCR was 5.55 g/g. Most patients had primary MN (82.1%). The patients with higher C3 deposition were more likely to response to ACEi/ARB (72.2% vs 42.9%, p = 0.06) and 29 patients did immunosuppression therapy during the follow-up period. There were no significant differences between groups, except the body mass index (BMI), which it was higher in the high C3 group (25.52 ± 3.14 vs 27.42 ± 5.45, p = 0.03) and the presence of thrombosis, which all occurred in the high C3 group (0 vs 4, p = 0.023). During a mean follow-up of 6 ± 4.2 years, 7 (17.9%) patients developed ESKD and 11 (33.3%) patients had a decreased of at least 30% eGFR at five years. The group with low C3 deposition had a higher rate of remission (81.0% vs 61.1%, p = 0.03), reaching remission earlier (9.75 ± 322.92 vs 17.8 ± 32, p = 0.021) comparing with the high C3 deposition. The rate of relapse was similar in both groups. Conclusion There is growing evidence that complement activation has a role in the pathophysiology and, probably, in prognosis of MN. Previous studies have correlated low serum C3 levels with poor long-term renal survival. In our study, the extensive C3 deposition in kidney biopsies was associated with lower and delayed remission rate. Furthermore, it was associated with more thrombotic complications. More patients of the higher C3 deposition group developed ESKD. It was not statistically significant, probably because of the small size of the sample, a limitation of our study. Nonetheless, we believe that C3 deposition is indicative of a worse prognosis of MN and therapeutic modulation of the complement can be a promising treatment strategy in MN.

#1976 Non-IgA mesangial proliferative glomerulonephritis in a patient with IgA deficiency, a case report

Abstract Background and Aims IgA deficiency (IgAD) is the most common primary immunoglobulin deficiency in western countries. This entity is associated with increased risk of other autoimmune diseases. Mesangial proliferative glomerulonephritis (MesPGN) is a histological pattern defined by mesangial cell proliferation and expansion of the extracellular matrix within the mesangium. The clinical presentation can vary, from nephrotic syndrome to isolated hematuria. 30-40% of MesPGN cases are associated with IgA nephropathy. Other common diagnostic entities that present with this pattern include IgM nephropathy, C1q nephropathy or lupus nephritis, as well as Hepatitis B or C virus infection; idiopathic MesPGN is poorly described in the literature. To the best of our knowledge, this is the first report of idiopathic MesPGN associated with IgAD. Results A 17-year old woman with a background of IgAD and occasional episodes of bronchitis in her childhood presented in January 2022 with nonspecific abdominal pain and macroscopic hematuria. She had been suffering these symptoms for the last few weeks, usually after physical exercise. She was normotensive and showed no fever, skin rashes or other symptoms. Laboratory tests revealed normal renal function (serum creatinine 0.65 mg/dL), urinary albumin-to-creatinine ratio of 23.9 mg/g, a 24-h protein excretion ranging from 40 to 240 mg and non-dysmorphic hematuria of up to 51-150 erythrocytes/field. Additional laboratory tests repeatedly showed only low IgA serum levels, with normal ANA, ANCA or complement levels. Renal ultrasound showed both kidneys with normal size and cortical thickness. A CT urogram observed multiple, bilateral, non-obstructive small-sized kidney stones and a persistent nephrogram. Genetic tests were negative for Alport syndrome-related mutations. Additional workup included occult blood in the stool, stool culture, rectal biopsy and colonoscopy, which were all negative. Symptoms persisted during the following 12 months. A kidney biopsy was performed, finding 40 glomeruli with normal optical appearance, none of them sclerosed. Discrete mesangial expansion and cell proliferation was observed, with capillary lumens with occasional congestion but without thrombi or fibrinoid necrosis. Tubules and interstitium showed no sign of sclerosis or fibrosis, with conserved basement membranes and brush borders. In vessels, subintimal fibrosis, hyalinosis or concentric arteriolar hyperplasia or endarteritis were ruled out. Immunofluorescence showed low-intensity, discrete granular C3 mesangial deposits and no deposition of IgA, IgG, IgM, fibrinogen, C4, C1q or albumin. A diagnosis of non-IgA MesPGN was reached. The patient stopped performing intense physical exercise on a regular basis. This translated in hematuria and abdominal pain of much lower intensity. The patient is currently receiving only supportive therapy and maintains a normal renal function, with persistence of microscopic non-dysmorphic hematuria and occasional, low-grade proteinuria as described. Conclusion MesPGN is the most diagnosed form of glomerulonephritis worldwide. However, most cases are associated with granular IgA deposition in the mesangium, which was absent in this case. Idiopathic, non-IgA MesPGN is a much rarer condition that has been considered by some authors as a form focal segmental glomerulosclerosis or minimal change disease, although others believe it to be a separate condition. IgAD has been previously associated with Crohn's disease, which could explain this patient's symptoms. Crohn's disease has also been associated with non-IgA MesPGN in a low number of patients. Nevertheless, no findings in the patient workup were suggestive of Crohn's disease. A capsule endoscopy study will be performed to clearly rule out such diagnosis.

Robust Algorithms for the Analysis of Fast-Field-Cycling Nuclear Magnetic Resonance Dispersion Curves

Fast-Field-Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry is a powerful, non-destructive magnetic resonance technique that enables, among other things, the investigation of slow molecular dynamics at low magnetic field intensities. FFC-NMR relaxometry measurements provide insight into molecular motion across various timescales within a single experiment. This study focuses on a model-free approach, representing the NMRD profile R1 as a linear combination of Lorentzian functions, thereby addressing the challenges of fitting data within an ill-conditioned linear least-squares framework. Tackling this problem, we present a comprehensive review and experimental validation of three regularization approaches to implement the model-free approach to analyzing NMRD profiles. These include (1) MF-UPen, utilizing locally adapted L2 regularization; (2) MF-L1, based on L1 penalties; and (3) a hybrid approach combining locally adapted L2 and global L1 penalties. Each method’s regularization parameters are determined automatically according to the Balancing and Uniform Penalty principles. Our contributions include the implementation and experimental validation of the MF-UPen and MF-MUPen algorithms, and the development of a “dispersion analysis” technique to assess the existence range of the estimated parameters. The objective of this work is to delineate the variance in fit quality and correlation time distribution yielded by each algorithm, thus broadening the set of software tools for the analysis of sample structures in FFC-NMR studies. The findings underline the efficacy and applicability of these algorithms in the analysis of NMRD profiles from samples representing different potential scenarios.

#2984 SLE associated fibrillary glomerulonephritis vs SLE nephritis with fibrils: can a straightforward distinction always be made?

Abstract Background and Aims Fibrillary glomerulonephritis (FGN) is an uncommon but serious kidney disease with unclear aetiology, variable prognosis, and a not well-established treatment. FGN has been associated with autoimmune diseases including SLE. Other aetiologies comprise diabetes, malignancies, HCV and chronic infections. Our goal is to discuss the pathologic and clinical differential diagnosis conundrums that a patient with a suspected SLE presented. Method We present the case of a 53-year-old woman evaluated for proteinuria (1 g/24 h), and glomerular haematuria. Renal function was normal. She referred mild arthralgias for the past two years. Her medical history was unremarkable for diabetes and hypertension. ANA and anti-dsDNA were positive. The rest of the immunological work-up was normal as well as protein immunofixation/free light chains. HCV, HBV, and HIV serology was negative. A thorough evaluation for malignancy was negative. A renal biopsy was performed. Results The renal biopsy showed enlarged glomeruli with mesangial matrix expansion (Congo-red negative), mild mesangial hypercellularity and focal endocapillary hypercellularity without hyaline deposits, fibrinoid necrosis or crescents, without significant chronic lesions (Fig. 1). A probable diagnosis based on light microscope could be that of a lupus nephritis class III with low activity and low chronicity indices. Immunofluorescence demonstrated weak or moderate immunofixation of IgG (2+), IgA(1+), C3(2+), C1q(1+), κ(1+) and λ(1+) in the mesangium and segmentally in the capillary walls with a smudgy appearance. IgM, C4, fibrinogen and albumin were negative. The lack of a full-house pattern and, more significantly, the low C1q intensity raised some questions about the validity of a lupus nephritis diagnosis. Ultrastructural evaluation revealed abundant fibrils that occupied the mesangium and permeated the glomerular basement membranes (GBMs). Fibrils were non branching and randomly oriented with a mean diameter of ∼15 nm (range: 11,87 nm -18,84 nm) (Fig. 2). No electron dense deposits, fingerprint deposits or tubuloreticular inclusions were detected. Immunohistochemical staining for DNA-J heat-shock protein family member B9 (DNAJB9) was then performed showing strong positivity in the mesangial matrix and GBMs. Interestingly, C4d was also strongly positive with the same pattern as DNAJB9. The diagnosis of fibrillary glomerulonephritis was suggested, mostly based on ultrastructural evaluation and immunohistochemical findings. Conclusion It is well known that the characteristic features of lupus nephritis (intense C1q staining, full-house staining, extraglomerular deposits, tubuloreticular inclusions, and combined subendothelial and subepithelial deposits) are, in some cases, neither universally present nor specific for lupus nephritis. Of special interest is the identification of fibrils in the renal biopsy of an SLE patient. The crucial importance of distinguishing between SLE associated FGN and SLE nephritis with fibrils is based on the generally poor renal prognosis of FGN as well as the unsatisfactory performance of immunosuppression. The differential diagnosis can be very challenging especially when DNAJB9 is not available.