Passive Leakage Research Articles

Kelp dissolved organic carbon release is seasonal and annually enhanced during senescence.

Macroalgae influence local and global biogeochemical cycles through their production of dissolved organic carbon (DOC). Yet, data remain scarce and annualized estimates are typically based on high growth periods without considering seasonal variability. Although the mechanisms of active exudation and passive leakage need clarifying, ecophysiological stress is known to enhance DOC release. Therefore, DOC leakage from seasonally senescent macroalgae may be overlooked. This study focuses on the annual kelp Saccharina japonica var. religiosa (class Phaeophyceae) from Oshoro Bay, Hokkaido, Japan. Three years (2020-2022) of seasonal data were collected and analyzed, with least squares mean DOC release rates established for kelp (n = 88) across 16 incubation experiments (t ≥ 4 d, DOC samples ≥1 · d-1) under different photosynthetically active radiation (PAR) treatments (200, 400, 1200, or 1500 μmol photons · m-2 · s-1). Differences in PAR, dry weight biomass (g DW), sea surface temperature, or salinity could not explain DOC release-rate variability, which was high between individual kelp. Instead, there were significant intra-annual differences, with mean DOC release rates (mg C · g-1 DW · d-1 ± standard error between n kelp) higher during the autumn "late decay" period (0.71 ± 0.10, n = 27) compared to the winter "early growth" period (0.14 ± 0.025, n = 10) and summer "early decay" period (0.25 ± 0.050, n = 24). This relationship between seasonal senescence and macroalgal DOC release is further evidence that long-term, place-based studies of DOC dynamics are essential and that global extrapolations are premature.

Systemic sclerosis and anorectal dysfunction: The Leeds experience.

Systemic sclerosis is an autoimmune disorder which frequently affects the gastrointestinal tract. Anorectal dysfunction is common in systemic sclerosis and is manifested mainly by atrophy of internal anal sphincter. Faecal incontinence is the result of internal anal sphincter atrophy secondary to systemic sclerosis. In this study, we aimed to assess the internal anal sphincter in 17 patients with faecal incontinence and systemic sclerosis using anorectal manometry and endoanal ultrasound and compare them with an age and gender-matched control group without systemic sclerosis. Most patients have limited cutaneous systemic sclerosis. Majority of the patients with systemic sclerosis and faecal incontinence presented with symptoms of faecal leakage and urgency. Systemic sclerosis patients had low basal sphincter pressures. The mean thickness of internal anal sphincter in systemic sclerosis group was significantly lower than the control group (p < 0.001). Rectal sensation is preserved in systemic sclerosis. There was no difference in the mean thickness of the external anal sphincter between the two groups. To conclude internal anal sphincter is atrophic in systemic sclerosis resulting in decreased resting sphincter pressures and passive faecal leakage. Further investigations and studies are needed to determine the natural course of faecal incontinence in systemic sclerosis, associated risk factors and efficacy of therapeutic interventions.

Assessment of non-revenue water in the urban water distribution system network in Cameroon (Central Africa)

ABSTRACT This paper aims to assess non-revenue water (NRW) in the urban water distribution system in Cameroon. The methodological approach used in this study was based on online searches using the databases such as Google Scholar, Web of Science, PubMed, and the International Water Association. These online searches have been completed through field observations and interviews with institutional and non-institutional stakeholders in the urban water sector. Results indicate that the total volume of NRW in the urban area of Cameroon was 100.26 million m3/year, which represents 52.5% of the total system input volume. About 2 million people could be supplied by cutting Cameroon's NRW to half the present level. Findings also suggest that the water utility (Camwater) practices passive leakage control, meaning that Camwater repairs only those leaks that are visible. Reducing NRW can be achieved through leakage detection and pipe replacement, pressure management, water metering, and a program to identify, remove, and replace illegal connections.

Protection System Architecture for All-Electric Aircraft

To reduce emissions from the aviation industry and meet the targets set by different countries, research has been focused on investigating all-electric aircraft. To make this vision practical, superconducting machines are expected to power the propellers, as they are half the size and a third the weight of conventional machines. The main purpose of this paper is to do a higher-level study of a reliable holistic protection system for all-electric aircraft; that can reduce heat leakage and be able to detect faults reliably. Thus, three main protection systems were investigated; 1) cryogenic voltage source converter superconducting magnetic energy storage system (VSC-SMES), 2) cryogenic dc breaker integrated with superconducting fault current limiter (SFCL), and 3) machine learning algorithm for fault detection. By immersing the protection system at cryogenic temperature, the paper has shown that passive leakage can be eliminated, and thus more energy can be saved for the fuel cell. The paper has also demonstrated that using machine learning for the SFCL-dc-breaker system can consistently eliminate faults and protect the system.

Passive air leakage detection mechanism for enhanced vacuum suction actuator efficiency

Passive air leakage detection mechanism for enhanced vacuum suction actuator efficiency

The effect of the blood sampling method on the risk of mechanical hemolysis of erythrocytes in healthy calves and with endogenous intoxication syndrome

In the conditions of the milk production complex in the Voronezh region, where Holstein cattle are kept, studies were conducted to study the degree of injury to blood cells during its selection by various methods in healthy calves and with endogenous intoxication syndrome. In healthy animals, blood sampling by passive leakage does not affect the membranes of erythrocytes. When using vacuum systems, there are no visual signs (hemolysis) of cell destruction, but changes in their cytoskeleton occur with an increase in the sensitivity of membranes to negative pre-analytical factors. In animals with endogenous intoxication syndrome, there are explicit or hidden destruction of erythrocyte membranes, which are manifested by an increase in the content of extra-erythrocyte hemoglobin, the degree of physiological hemolysis, sensitivity to intra- and extravascular hemolytic factors. As a result, already when selecting blood samples by passive gravity, there is a risk of hemolysis, and when using a vacuum system, it is observed in most samples. Therefore, when examining sick animals, it is necessary to take into account the high probability of laboratory diagnostic error at the pre-analytical stage that occurs due to hemolysis of erythrocytes with hypersensitivity to extravascular cytolytic factors, including mechanical effects during blood sampling.

Comparative study of free respiration in liver mitochondria during oxidation of various electron donors and under conditions of shutdown of complex III of the respiratory chain

The present work shows that the rate of free respiration of liver mitochondria (in the absence of ATP synthesis (state 4) during the oxidation of succinate is 1.7 times higher than during the oxidation of glutamate with malate. In turn, in the case of oxidation of ferrocyanide with ascorbate, this value is 3.1 times greater than in the case of succinate oxidation. A similar pattern is also observed upon stimulation of free respiration by low concentrations (5 and 10 μM) of the protonophore uncoupler 2,4-dinitrophenol (DNP). It is found that the passive leakage rate of protons in state 4 is the same if the H+/O ratios are 10, 6, and 2 upon the oxidation of glutamate with malate, succinate, and ferrocyanide with ascorbate, respectively. At these values of the H+/O ratio, low concentrations of DNP stimulate passive proton leakage equally during the oxidation of these respiration substrates. In the case of succinate oxidation, bypassing complex III by N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) to the maximum degree, as well as switching this complex completely to idle mode by α,ω-hexadecanedioic acid (HDA) cause a 3-fold stimulation of respiration in state 4. We conclude that at mitochondrial free respiration the values of the H+/2e− ratio for complexes I, III, and IV of the respiratory chain are 4, 4, and 2, respectively. It is assumed that the free respiration of mitochondria is carried out by simple diffusion of protons through the inner membrane, and the rate of this diffusion depends on the total number of protons released by the complexes of the electron transport chain into the intermembrane space.

Rate and fate of dissolved organic carbon release by seaweeds: A missing link in the coastal ocean carbon cycle.

Dissolved organic carbon (DOC) release by seaweeds (marine macroalgae) is a critical component of the coastal ocean biogeochemical carbon cycle but is an aspect of seaweed carbon physiology that we know relatively little about. Seaweed-derived DOC is found throughout coastal ecosystems and supports multiple food web linkages. Here, we discuss the mechanisms of DOC release by seaweeds and group them into passive (leakage, requires no energy) and active release (exudation, requires energy) with particular focus on the photosynthetic "overflow" hypothesis. The release of DOC from seaweeds was first studied in the 1960s, but subsequent studies use a range of units hindering evaluation: we convert published values to a common unit (μmol C · g DW-1 · h-1 ) allowing comparisons between seaweed phyla, functional groups, biogeographic region, and an assessment of the environmental regulation of DOC production. The range of DOC release rates by seaweeds from each phylum under ambient environmental conditions was 0-266.44μmol C · g DW-1 · h-1 (Chlorophyta), 0-89.92μmol C · g DW-1 · h-1 (Ochrophyta), and 0-41.28μmol C · g DW-1 · h-1 (Rhodophyta). DOC release rates increased under environmental factors such as desiccation, high irradiance, non-optimal temperatures, altered salinity, and elevated dissolved carbon dioxide (CO2 ) concentrations. Importantly, DOC release was highest by seaweeds that were desiccated (<90 times greater DOC release compared to ambient). We discuss the impact of future ocean scenarios (ocean acidification, seawater warming, altered irradiance) on DOC release rates by seaweeds, the role of seaweed-derived DOC in carbon sequestration models, and how they inform future research directions.

A Low-Noise and Fast-Settling UHF RFID Receiver With Digitally Controlled Leakage Cancellation

UHF RFID reader suffers from a strong transmitter (Tx) leakage signal coupled to a receiver (Rx), especially for an area-compact single-antenna implementation. Then, several Tx leakage cancellation schemes have been developed not to saturate the Rx and to minimize the performance degradation. This brief proposes a UHF RFID reader Rx with a low noise performance and a fast settling time by employing a digitally controlled leakage cancellation method in both passive and active realizations. A digitally-controlled passive vector reflector enhances the Tx to Rx isolation ratio by providing the optimum load impedance. An active anti-leakage feedback loop adaptively tracks the time-varying leakage and generate the phase-inverted leakage replica to suppress the leakage. The prototype chip is fabricated in a CMOS 55 nm process and the area of the chip is 2.1 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.8$ </tex-math></inline-formula> mm. The passive leakage cancellation (PLC) with a vector reflector endures the 1 dBm leakage with a low Rx noise figure of 12.5 dB and 35.7 mW power consumption. The active leakage cancellation (ALC) with an anti-leakage feedback loop covers 6 dBm leakage with a fast settling time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.6~\mu \text{s}$ </tex-math></inline-formula> and 58 mW power consumption.

Pelvic floor architectural defects in female patients with urge fecal incontinence versus passive fecal leakage: a dynamic ultrasound study.

Fecal incontinence (FI) has two primary subtypes: urgency fecal incontinence (UFI) and passive fecal leakage (PFL). The pathophysiology underlying the subtypes is incompletely understood. To compare the bowel habits, physical examinations and pelvic floor anatomical defects in patients with UFI-dominant FI versus patients with PFL-dominant FI. This is a retrospective cross-sectional study of female patients who presented with fecal incontinence symptoms to our tertiary urogynecology center. All subjects underwent a comprehensive history, physical examination, 3D-static pelvic floor ultrasound, and 2D-dynamic ultrasound of the posterior compartment. Patients with UFI-dominant FI were compared to patients with PFL-dominant FI. One hundred forty-five patients were included in the analysis; 57 categorized as UFI-dominant FI, 69 PFL-dominant FI and 19 categorized as having "both" leakage patterns. In comparing bowel habits, patient with UFI-dominant FI had more frequent bowel movements (15.5 ± SD 13.0/week vs. 10.9 ± SD 7.6 /week, p = 0.022) and were more likely to have loose stools (48.2% vs. 26.1%, p = 0.01). No statistically significant differences were observed in the prevalence of external anal sphincter defect (11.3% vs. 17.2%, p = 0.38) or internal anal sphincter defect (11.3% vs. 19%, p = 0.26) between groups. Finally, patients with UFI-dominant FI had a higher incidence of rectal hypermobility (loss of rectal support on Valsalva) (58% vs. 36.9%, p = 0.025). Patients with urge-predominant FI have increased frequency of bowel movements, looser stools, and increased rectal folding diagnosed via dynamic ultrasound as compared to patients with passive-dominant FI.

Bounding passive light-source side channels in quantum key distribution via Hong-Ou-Mandel interference

Passive side-channel attacks in quantum key distribution (QKD) aim at obtaining information about the quantum signals without disturbing them and hence compromise real-world QKD security. Currently, there are no reliable tools for the assessment of QKD signal generation imperfections. In this work we propose a generic experimental method which allows to upper-bound QKD light-source imperfections and directly integrate them into the modern security proofs. The method relies on Hong-Ou-Mandel interference between different emitted signals: the maximum interference visibility reveals overall signal distinguishability that could lead to passive side-channel information leakage. We apply it for the standard decoy-state BB84 protocol and calculate a lower bound on the secret key rate for realistic values of interference visibility. The method can be readily implemented in practical QKD setups and is especially relevant for multiple-laser QKD systems such as the one installed on the Micius satellite.

Multi-objective characterization of an inflatable space structure with a quasi-static experimental deflation and finite element analysis

We propose a methodology for the multi-objective characterization of a light, single layer orthotropic fabric inflatable space structure. The presented approach focuses on a custom in-situ experimental quasi-static deflation, semi-empirical development of flow coefficients and structural integrity loss parameters as well as process validation with finite element analysis. The experiments are designed to investigate a collapse of a thin, deployable, one segmented inflatable structure caused by a simulated single leak and passive porous leakage through the fabric material. The acquisition of real time data with a custom designed standalone ambient conditions sensing platform and the wireless internal sensing unit furnishes pressures, temperatures, mass flow rates, dynamic strains and accelerations. Synchronously, geometric changes in the shape of the structure's representative area are recorded utilizing photogrammetry. The non-wireless and wireless outputs are treated with a series of smoothing, best-fitting and refining operations and combined with the corresponding sequence of active surface area photogrammetric results. The formulation of inflatable characterization parameters and a single leak/passive porous leakage structural integrity loss ratios allows for an in depth description of the inflatable structure behavior. A closer examination of the experimental data shows that the majority of the structural integrity loss ~97% is attributed to the sudden and relatively short leak due to puncture and the remaining ~3% to the slow and prolonged pressure loss caused by the passive porous areal leakage through the membrane. A semi-empirical framework based on a thermodynamic equilibrium produces sets of single leak, passive porous leakage and active area coefficients to be validated with the Ls-DYNA® finite element simulation of a polyurethane coated nylon fabric inflatable structure model. We use implicit and explicit fea of a control volume deflation to validate the aforementioned coefficient curves and constants. The subsequent comparison with the experimental internal temperature, internal pressure and mass flow rates results in a 1.83%, 0.61% and 1.19% difference respectively for the single leak events. The successive contrasting with the experimental internal temperature, internal pressure and active area produces 2.04%, 1.26% and 1.68% difference for the passive porous leakage respectively. We demonstrated that the multi-objective, structural integrity loss characterization techniques for the space structures have promising capabilities for the application in inflatable structures of diverse shapes and sizes.

Reducing Passive Drug Diffusion from Electrophoretic Drug Delivery Devices through Co-Ion Engineering.

Implantable electrophoretic drug delivery devices have shown promise for applications ranging from treating pathologies such as epilepsy and cancer to regulating plant physiology. Upon applying a voltage, the devices electrophoretically transport charged drug molecules across an ion‐conducting membrane out to the local implanted area. This solvent‐flow‐free “dry” delivery enables controlled drug release with minimal pressure increase at the outlet. However, a major challenge these devices face is limiting drug leakage in their idle state. Here, a method of reducing passive drug leakage through the choice of the drug co‐ion is presented. By switching acetylcholine's associated co‐ion from chloride to carboxylate co‐ions as well as sulfopropyl acrylate‐based polyanions, steady‐state drug leakage rate is reduced up to sevenfold with minimal effect on the active drug delivery rate. Numerical simulations further illustrate the potential of this method and offer guidance for new material systems to suppress passive drug leakage in electrophoretic drug delivery devices.

A comprehensive overview of the complex world of the endo- and sarcoplasmic reticulum Ca2+-leak channels

Inside cells, the endoplasmic reticulum (ER) forms the largest Ca2+ store. Ca2+ is actively pumped by the SERCA pumps in the ER, where intraluminal Ca2+-binding proteins enable the accumulation of large amount of Ca2+. IP3 receptors and the ryanodine receptors mediate the release of Ca2+ in a controlled way, thereby evoking complex spatio-temporal signals in the cell. The steady state Ca2+ concentration in the ER of about 500 μM results from the balance between SERCA-mediated Ca2+ uptake and the passive leakage of Ca2+. The passive Ca2+ leak from the ER is often ignored, but can play an important physiological role, depending on the cellular context. Moreover, excessive Ca2+ leakage significantly lowers the amount of Ca2+ stored in the ER compared to normal conditions, thereby limiting the possibility to evoke Ca2+ signals and/or causing ER stress, leading to pathological consequences. The so-called Ca2+-leak channels responsible for Ca2+ leakage from the ER are however still not well understood, despite over 20 different proteins have been proposed to contribute to it. This review has the aim to critically evaluate the available evidence about the various channels potentially involved and to draw conclusions about their relative importance.

Ultrasound-Responsive Nanocarriers in Cancer Treatment: A Review.

The safe and effective delivery of anticancer agents to diseased tissues is one of the significant challenges in cancer therapy. Conventional anticancer agents are generally cytotoxins with poor pharmacokinetics and bioavailability. Nanocarriers are nanosized particles designed for the selectivity of anticancer drugs and gene transport to tumors. They are small enough to extravasate into solid tumors, where they slowly release their therapeutic load by passive leakage or biodegradation. Using smart nanocarriers, the rate of release of the entrapped therapeutic(s) can be increased, and greater exposure of the tumor cells to the therapeutics can be achieved when the nanocarriers are exposed to certain internally (enzymes, pH, and temperature) or externally (light, magnetic field, and ultrasound) applied stimuli that trigger the release of their load in a safe and controlled manner, spatially and temporally. This review gives a comprehensive overview of recent research findings on the different types of stimuli-responsive nanocarriers and their application in cancer treatment with a particular focus on ultrasound.

Early Detection of Aortic Degeneration in a Mouse Model of Sporadic Aortic Aneurysm and Dissection Using Nanoparticle Contrast-Enhanced Computed Tomography.

[Figure: see text].

Improving the reliability of metal structures of transport and technological machines during operation in the Arctic

In the course of the study, we analyzed the main factors affecting the brittle fracture of the elements of welded structures made of structural steels, associated with its unexpectedness and the absence of noticeable plastic deformations at metal stresses much lower than the yield point. During experiments, the relationship between the magnetic parameter Hp and the structure of structural steels during thermal cycling was revealed. This became possible due to the high sensitivity of passive magnetic flux leakage testing when monitoring the structural transformations of metal during cyclic heating and cooling. We provide examples of the formation of ultrafine-grain structures in industrial structural steels based on the results of thermal cycling and analyze factors affecting the final grain size. It is shown that the degree of steel microstructure refinement depends on the chemical composition and initial structure of steels as well as the number of thermal cycling cycles. It was established that an increase in the number of thermal cycling cycles and the degree of steel alloying, the presence of a finer-grain initial structure, and preliminary cold plastic deformation during stage-by-stage monitoring using passive magnetic flux leakage testing contribute to the formation of a finer-grain structure. A decrease in the average grain size shifts the temperature of metal transition from ductile to brittle fracture to the region of lower temperatures, which increases the reliability of welded metal structures of transport and technological machines used in the Arctic.

STRUCTURAL CHANGES IN STRUCTURAL STEELS DURING THERMAL CYCLING

Introduction: During experimental studies of structural steels responsible for the reliability of metal structures used, for example, in hoisting and transporting machinery, we established a correlation between the magnetic parameter Hp and characteristic changes in the metal microstructure during thermal cycling. It is shown that the Нр parameter depends on the initial structural state of steel, the amount and mass fraction of alloying elements, and the number of heating/cooling cycles. Methods: We found that an increase in the number of heating/cooling cycles and the amount of alloying elements, as well as preliminary cold plastic deformation with stage-by-stage control of structural changes using passive magnetic flux leakage testing results in a finer-grained structure, which was confirmed by metallographic analysis. Results: The paper considers specifics of structural changes in steels with different initial structures during thermal cycling. It is shown that the final grain size depends on the number of treatment cycles, the amount of alloying elements, and the initial microstructure. It is the fine-grain structure that improves the most important performance characteristics of steels: strength, cyclic strength, and cold brittleness.

The use of passive cable theory to increase the threshold of nociceptors in people with chronic pain

Background Chronic pain is one of the disorders that cost any society high expenses. The major mechanisms responsible for the conversion of pain from acute to chronic are still unclear. One major mechanism of these mechanisms is the hypersensitivity of nociceptors to any noxious stimulus. Treatment approaches for chronic pain have not targeted the abnormal function of nociceptors or achieved long-time relief of pain yet. Objectives To outline the effectiveness of passive cable theory to decrease the hypersensitivity of nociceptors in patients with chronic pain and renormalize the abnormal hypersensitivity of nociceptors. Major Findings applying the concept of the passive cable theory in the treatment of chronic pain would decrease the hypersensitivity of nociceptors and produce a decrease in chronic pain levels. This could occur through increasing the passive background leakage of ions in the opposite direction against their major flow direction. During the major flow of ions through the cell membrane occurs with any noxious stimulus, a background passive leakage of the same ions occurs in the opposite direction. This leakage helps in increasing the postsynaptic potentials and prolongs their decay phase. In turn, this decreases the hyperexcitability of the central nervous system, which commonly occurs in chronic pain. Both decreases in the peripheral and central sensitization would decrease the depletion of β-arrestin-2, which leads to a decrease in the descending painful mechanism. Conclusion The use of passive cable theory would be a useful intervention to decrease the hypersensitivity of peripheral nociceptors and hyper-excitability of the central nervous system, which are common mechanisms of persisted chronic pain. This helps to renormalize the abnormal mechanism commonly occur in chronic pain and would cause a prolonged decrease in chronic pain.

Defective Sec61α1 underlies a novel cause of autosomal dominant severe congenital neutropenia

BackgroundThe molecular cause of severe congenital neutropenia (SCN) is unknown in 30% to 50% of patients. SEC61A1 encodes the α-subunit of the Sec61 complex, which governs endoplasmic reticulum protein transport and passive calcium leakage. Recently, mutations in SEC61A1 were reported to be pathogenic in common variable immunodeficiency and glomerulocystic kidney disease.ObjectiveOur aim was to expand the spectrum of SEC61A1-mediated disease to include autosomal dominant SCN.MethodsWhole exome sequencing findings were validated, and reported mutations were compared by Western blotting, Ca2+ flux assays, differentiation of transduced HL-60 cells, in vitro differentiation of primary CD34 cells, quantitative PCR for unfolded protein response (UPR) genes, and single-cell RNA sequencing on whole bone marrow.ResultsWe identified a novel de novo missense mutation in SEC61A1 (c.A275G;p.Q92R) in a patient with SCN who was born to nonconsanguineous Belgian parents. The mutation results in diminished protein expression, disturbed protein translocation, and an increase in calcium leakage from the endoplasmic reticulum. In vitro differentiation of CD34+ cells recapitulated the patient’s clinical arrest in granulopoiesis. The impact of Q92R-Sec61α1 on neutrophil maturation was validated by using HL-60 cells, in which transduction reduced differentiation into CD11b+CD16+ cells. A potential mechanism for this defect is the uncontrolled initiation of the unfolded protein stress response, with single-cell analysis of primary bone marrow revealing perturbed UPR in myeloid precursors and in vitro differentiation of primary CD34+ cells revealing upregulation of CCAAT/enhancer-binding protein homologous protein and immunoglobulin heavy chain binding protein UPR-response genes.ConclusionSpecific mutations in SEC61A1 cause SCN through dysregulation of the UPR.