Flux Measurements Research Articles

Deuterium MRI of serine metabolism in mouse models of glioblastoma.

Serine is a major source of one-carbon units needed for the synthesis of nucleotides and the production of intramitochondrial nicotinamide adenine dinucleotide phosphate (NADPH), and it plays an important role in cancer cell proliferation. The aim of this study was to develop a deuterium (2H) MRS imaging method for imaging tumor serine metabolism. Sequential (2H) spectra and spectroscopic images were used to monitor the metabolism of [2,3,3-2H3]serine in patient-derived glioblastoma cells in vitro and in tumors obtained by their orthotopic implantation in mouse brain. [14,14-2H2] 5,10-methylene-tetrahydrofolate, [2H]glycine, [2H]formate, and labeled water were detected in cell suspensions and water labeling in spectroscopic images of tumors. Studies in cells and tumors with variable mitochondrial content and inhibitor studies in cells demonstrated that most of the labeled serine was metabolized in the mitochondria. Water labeling in the cell suspensions was correlated with formate labeling; therefore, water labeling observed in tumors could be used to provide a surrogate measure of flux in the pathway of one-carbon metabolism in vivo. The method has the potential to be used clinically to select patients for treatment with inhibitors of one-carbon metabolism and subsequently to detect their early responses to such treatment.

Low-Power Magnetic Displacement Sensor Based on RISC-V Embedded System.

With the emergence of RISC-V architecture in embedded devices, its inherent low-power features have propelled its extensive adoption across various industrial settings. Displacement sensors leveraging Hall sensors and magnetic flux measurement present notable benefits including cost-effectiveness and compact design. This study undertakes the porting of Hall sensors onto RISC-V architecture embedded devices, validating their functionality within displacement sensors. Empirical investigations substantiate that the ported system consistently delivers comparable outcomes to those obtained from x86 architecture systems employing PM-MFM methods, affirming its reliability and performance in practical applications.

Heat flow density measurement during non-destructive testing

The object of the study is the development of a device capable of accurately and reliably measuring heat flux density in various environments. The development of a heat flux density meter designed for non-destructive analysis of thermal processes in various fields of application is presented. The developed device is intended for evaluating the thermal insulation condition of underground pipelines. The functionality of the heat flow device relies on comparing standard temperature values with experimental ones measured on the soil surface. To ensure accurate and reliable measurement of heat flux density, the basis is a thermoelectric battery converter, which uses the auxiliary wall method. The heat flow density measuring device is constructed in the shape of a restricted cylinder, with one base serving as the working surface, while the second base establishes thermal contact with the body at ambient temperature. Embedded heaters enable the generation of heat flow through the thermoelectric sensor in directions perpendicular to its base. For calibrating the heat flux device, experiments were conducted using a standard copper-constantan calibration table. Temperature increments were determined from thermo electromotive force, and tests were performed on an existing heating network. The conducted measurements validate the fundamental feasibility of employing the proposed device for implementing the non-destructive thermal testing method on underground heating mains. The results of the experiment can be used not only for research, but also for monitoring and regulating processes in various fields of science and technology. The developed heat flux meter promises a significant contribution to the development of modern methods for analyzing thermal processes. The dimensions of the thermoelectric battery converter are also determined and the coefficient (kq) should be in the range from 4.0 to 12.0 W/(m2⋅mV), and the electrical resistance should be in the range of 12–20 kOhm

In‐Phase PDO and El Niño Events Enhance the Summer CO2 Emissions in Saline Lakes on the Qinghai‐Tibet Plateau

AbstractSaline lakes contributions to the carbon cycle is crucial to the Qinghai‐Tibetan Plateau (QTP) carbon budget. Here, based on the 8‐year direct measurement of CO2 flux over the Qinghai Lake (QHL) and 83 collected CO2 flux data estimated by pCO2 sampling from 45 lakes over the QTP, we identified the interannual variations of CO2 flux and its response to the extreme climate events. Results showed: (a) the QHL CO2 absorption weakened in the spring, autumn and winter and turn to CO2 emissions in the summer during 2013–2020; (b) with higher Ts and less precipitation, coupling of positive Pacific Decadal Oscillation (PDO) and El Niño enhanced the summer CO2 emissions; and (c) the PDO and ENSO had obvious superposition effect on the decrease of CO2 absorption in autumn. Our results show the potential mechanism of lake CO2 flux responses to extreme climate and further defines the significance of the QTP carbon budget and cycling.

Gas geothermometry, soil CO2 degassing, and heat release estimation to assess the geothermal potential of the Alpehue Hydrothermal Field (Sollipulli volcano, Southern Chile)

The Alpehue Hydrothermal Field (AHF) near the Sollipulli Volcano in the Southern Volcanic Zone of Chile shows promise as a significant geothermal resource. A comprehensive geothermal exploration survey was conducted, including the evaluation of hydrothermal gases, geothermometer calculations, and CO2 flux measurements, to assess the AHF's geothermal potential. Our results indicate that the hydrothermal gasses at the AHF primarily originate from primitive, mantle-derived sources, with some contribution from crustal sediments. Two different CO2 populations of fluxes were identified. One corresponds to the background emission related to the soil biological activity (mean ∼7.7 g·m−2·d−1), and the other, much more significant, emanates from an endogenous source related to the Alpehue hydrothermal reservoir (mean ∼461 g·m−2·d−1). Reservoir temperatures were calculated using gas geothermometry yielding average temperatures of 249 °C. The calculated heat flow rate of the AHF is approximately 3.3 MW and the heat flux corresponds to 156 thermal MW⋅km−2, which could be considered a medium geothermal potential comparable to other systems worldwide. Although further studies are needed to fully address its exploitability, this study presents favorable characteristics of the AHF that make it a promising avenue for further exploration.

Micromachined needle-like calorimetric flow sensor for sap flux density measurement in the xylem of plants

Miniaturized silicon thermal probes for plant’s sap flow measurement, or micro sap flow sensors, have advantages in minimum invasiveness, low power consumption, and fast responses. Practical applications in sap flow measurement has been demonstrated with the single-probe silicon micro sensors. However, the sensors could not detect flow directions and require estimating zero sap flow output that leads to significant source of uncertainty. Furthermore, silicon-needles would break easily during the insertion into plants. We present the first three-element micro thermal sap flow sensor packaged on a durable printed circuit board needle that can measure bidirectional flows with improved dynamics and precision. The performance of the newly designed calorimetric flow sensor was confirmed through precision calibration and field test on tomato stems. A calibration curve for a tomato stem was obtained with a sensitivity of 0.299 K/(µL mm−2 s−1) under the maximum temperature increase of 4.61 K. Results from the field test for one month revealed a correlation between the measured sap flux density and related conditions such as solar radiation, vapor pressure deficit, sunshade and irrigation. The developed sensor will contribute to practical long-term sap flow monitoring for small and delicate plants with minimal physical invasion.

Ultra-low-frequency LOFAR spectral indices of cluster radio halos

A fraction of galaxy clusters harbor diffuse radio sources known as radio halos. The prevailing theory regarding their formation is based on second-order Fermi reacceleration of seed electrons caused by merger-driven turbulence in the intra-cluster medium. This mechanism is expected to be inefficient, which implies that a significant fraction of halos should have very steep energy spectra ($ We start investigating the potential and current limitations of the combination of the two surveys conducted by LOFAR, LoTSS (144 MHz) and LoLSS (54 MHz), to probe the origin of radio halos. We followed up the 20 radio halos detected in Data Release 1 of LoTSS, which covers the HETDEX field, with the LoLSS survey, and we studied their spectral properties between 54 and 144 MHz. After removing compact sources, nine halos were excluded due to unreliable halo flux density measurements at 54 MHz. Our main finding is that 7 out of 11 (sim 64<!PCT!>) exhibit an ultra-steep spectrum ($ < -1.5$), which is a key prediction of turbulent reacceleration models. We also note a tentative trend for more massive systems to host flatter halos, although the currently poor statistics do not allow for a deeper analysis. Our sample suffers from low angular resolution at 54 MHz, which limits the accuracy of the compact-source subtraction. Nevertheless, this study is the first step toward providing compelling evidence for the existence of a large fraction of radio halos with a very steep spectrum, which is a fundamental prediction of turbulent reacceleration models. In this regard, the forthcoming second data release of LoLSS, along with the integration of LOFAR international stations and the instrumental upgrade to LOFAR2.0, will improve both the statistics and the low-frequency angular resolution, allowing us to determine the origin of radio halos in galaxy clusters conclusively.

Biocalorimetry-aided monitoring of fungal pretreatment of lignocellulosic agricultural residues

The present study aimed to investigate whether and how non-invasive biocalorimetric measurements could serve for process monitoring of fungal pretreatment during solid-state fermentation (SSF) of lignocellulosic agricultural residues such as wheat straw. Seven filamentous fungi representing different lignocellulose decay types were employed. Water-soluble sugars being immediately available after fungal pretreatment and those becoming water-extractable after enzymatic digestion of pretreated wheat straw with hydrolysing (hemi)cellulases were considered to constitute the total bioaccessible sugar fraction. The latter was used to indicate the success of pretreatments and linked to corresponding species-specific metabolic heat yield coefficients (YQ/X) derived from metabolic heat flux measurements during fungal wheat straw colonisation. An YQ/X range of about 120 to 140 kJ/g was seemingly optimal for pretreatment upon consideration of all investigated fungi and application of a non-linear Gaussian fitting model. Upon exclusion from analysis of the brown-rot basidiomycete Gloeophyllum trabeum, which differs from all other here investigated fungi in employing extracellular Fenton chemistry for lignocellulose decomposition, a linear relationship where amounts of total bioaccessible sugars were suggested to increase with increasing YQ/X values was obtained. It remains to be elucidated whether an YQ/X range being optimal for fungal pretreatment could firmly be established, or if the sugar accessibility for post-treatment generally increases with increasing YQ/X values as long as “conventional” enzymatic, i.e. (hemi)cellulase-based, lignocellulose decomposition mechanisms are operative. In any case, metabolic heat measurement–derived parameters such as YQ/X values may become very valuable tools supporting the assessment of the suitability of different fungal species for pretreatment of lignocellulosic substrates.Key points• Biocalorimetry was used to monitor wheat straw pretreatment with seven filamentous fungi.• Metabolic heat yield coefficients (YQ/X) seem to indicate pretreatment success.• YQ/X values may support the selection of suitable fungal strains for pretreatment.

Development and experimental testing of an innovative nondestructive thermal sensor utilizing the thermal interrogation method for detecting leakage in water plastic pipes

Leak detection in water pipelines is still an important issue in real-world industrial systems. Thus, a new nondestructive thermal sensor design based on the thermal interrogation method has been developed to detect and estimate the real-time leaks in water plastic pipes without environmental interference. The proposed thermal interrogation method utilizes a combination of heat flux and temperature measurements on the upstream and downstream outside plastic pipe surfaces. These measurements are obtained by using heat flux sensors and thermocouples that are covered by thin-film polyimide electric heaters. The interrogation method approach delivers that at constant input heat flux, the difference in sensor temperature values is dependent on the leakage volume flow rates. The sensor was tested over a range of water leakage volume flow rate from 0.1 m3/h to 1.3 m3/h and a range of water temperature from 21 °C to 25 °C. The water leakage volume flow rates were correlated to the difference in temperature values between the upstream and downstream sensors. The measurement results reveal that this sensor can be used to detect and estimate the real-time water leakage volume flow rate with high accuracy and repeatability for plastic pipes.

A new measurement of the mean transmitted flux in the Ly α and Ly β forest

ABSTRACT We present new measurements of the mean transmitted flux in the hydrogen $\rm {Ly\,\alpha }$ and a relative transmitted flux measurement in $\rm {Ly\,\beta }$ using 27 008 quasar spectra from the Fourteenth Data Release (DR14) of the Extended Baryon Oscillation Spectroscopic Survey. Individual spectra are first combined into 16 composites with mean redshifts in the range of $2.8\lt z\lt 4.9$. We then apply Markov Chain Monte Carlo (MCMC) inference to produce a piecewise fit of the effective $\tau _{\rm {Ly\,\alpha }}$ (corrected for metal lines and optically thick absorption) assuming a spline point distribution. We also perform a relative $\Delta \tau _{\rm {Ly\,\beta }}$ measurement with the same data set, finding $\Delta \tau _{\rm {Ly\,\beta }}\lt 0.35$ at $z\lt 4.8$. The 6–8 per cent precision measurements in the rest frame 1075–1150 Å at ${\it z} \ \lt \rm {4.0}$ and 10–12 per cent precision measurements in the same region at ${\it z} \ \gt \rm {4.0}$ on $\tau _{\rm {Ly\,\alpha }}$, and our determinations of $\Delta \tau _{\rm {Ly\,\beta }}$, are dominated by systematic errors, likely arising from bias and uncertainties in estimates of the quasar continuum. Our $\tau _{\rm {Ly\,\alpha }}$ values show a smooth increase by a factor of 5 over the redshift range $z=2.4-4.4$.

Mapping urban haze.

Direct airborne measurements of emission fluxes reveal major sources over California.

Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses

Livestock manure contributes to global warming due to greenhouse gas (GHG) emissions, especially nitrous oxide (N2O) and methane (CH4). In the arid and semi-arid lands of Sub-Saharan Africa (SSA), extensive pastoral grazing systems are common, with cattle grazing in the savanna during the day and kept in enclosures (called bomas in Kenya) during the night. Manure is usually not removed from bomas but left to accumulate, leading to excessive local nitrogen loads, making these bomas an overlooked N2O emission hotspot in SSA that is currently not accounted for in national and regional GHG budgets. Here, we present the first in-situ isotope measurements of N2O fluxes from 37 cattle bomas along an age gradient ranging from 0 to 5 years after boma abandonment in Kenya along with functional gene analysis of soil and manure samples. The isotopic composition of the emitted N2O from bomas suggests that on average 91 ± 8% N2O was produced via bacterial denitrification and/or nitrifier denitrification, with little variation across boma age class. We also found high levels of N2O reduction to N2 across all sample sites (81 ± 9%), indicating high levels of N2O consumption. The abundances of denitrification-related genes (nirK and narG) were significantly higher than those of nitrification-related genes (amoA: AOA and AOB) in the cattle manure samples taken from the bomas, corroborating N2O emissions largely being attributed to denitrification. Significant abundance of the reduction-related gene (nosZ) also corroborated the high potential for microbial N2O reduction in bomas. Thus, by combining dual-isotope and functional gene analysis, we were able to identify source processes that govern N2O emissions from these systems. More generally, making use of the manure by spreading it in the vicinity of the bomas or on dedicated forage plots could provide a win-win by enhancing savanna productivity while simultaneously mitigating GHG emissions.

Temperature-dependent emissions dominate aerosol and ozone formation in Los Angeles.

Despite declines in transportation emissions, urban North America and Europe still face unhealthy air pollution levels. This has challenged conventional understanding of the sources of their volatile organic compound (VOC) precursors. Using airborne flux measurements to map emissions of a wide range of VOCs, we demonstrate that biogenic terpenoid emissions contribute ~60% of emitted VOC OH reactivity, ozone, and secondary organic aerosol formation potential in summertime Los Angeles and that this contribution strongly increases with temperature. This implies that control of nitrogen oxides is key to reducing ozone formation in Los Angeles. We also show some anthropogenic VOC emissions increase with temperature, which is an effect not represented in current inventories. Air pollution mitigation efforts must consider that climate warming will strongly change emission amounts and composition.

A Reference Meteor Magnitude for Intercomparable Fluxes

The rate at which meteors pass through Earth’s atmosphere has been measured or estimated many times over; existing flux measurements span at least 12 astronomical magnitudes, or roughly five decades in mass. Unfortunately, the common practice of scaling flux to a universal reference magnitude of +6.5 tends to collapse the magnitude or mass dimension. Furthermore, results from different observation networks can appear discrepant due solely to the use of different assumed population indices, and readers cannot resolve this discrepancy without access to magnitude data. We present an alternate choice of reference magnitude that is representative of the observed meteors and minimizes the dependence of flux on population index. We apply this choice to measurements of recent Orionid meteor shower fluxes to illustrate its usefulness for synthesizing independent flux measurements.

Quantifying the carbon sequestration potential of different soil management practices aimed at increasing organic content in soil and reducing the usage of chemical inputs

<p>The global imperative to address climate change and promote sustainable agriculture has underscored the critical role of soil management practices in enhancing carbon sequestration and reducing greenhouse gas emissions. This research focuses on quantifying the carbon sequestration potential of diverse soil management techniques aimed at increasing organic content in soil while minimizing the use of chemical inputs. It integrates a multidisciplinary approach, conducting field experiments across diverse agroecological regions with different soil types and cropping systems. Key practices under investigation include cover cropping, crop rotations, conservation tillage, compost application, organic amendments, integrated pest management (IPM), and precision agriculture. The study assesses their impact on soil organic carbon levels, greenhouse gas emissions, soil health indicators, and crop productivity through comprehensive data collection and analysis techniques. Statistical analyses and modeling are employed to quantify carbon sequestration rates, evaluate treatment effects, and assess environmental and agronomic benefits. These practices are implemented in controlled trials to assess their impact on soil organic carbon (SOC) levels, greenhouse gas emissions (CO2, CH4, N2O), soil health indicators (microbial biomass, nutrient cycling, soil structure), and crop productivity. Data collection and analysis techniques involve comprehensive soil sampling, greenhouse gas flux measurements, soil health assessments, and crop yield monitoring over multiple growing seasons. Statistical analyses and modeling approaches are employed to quantify the carbon sequestration rates, assess treatment effects on soil health and greenhouse gas emissions, and evaluate the overall environmental and agronomic benefits of the soil management practices. The study aims to contribute valuable insights into evidence-based strategies for promoting sustainable soil management practices that enhance carbon sequestration while maintaining or improving agricultural productivity. The findings will have implications for informing agricultural policies, guiding farm management decisions, and advancing research on climate-smart agriculture. By quantifying the carbon sequestration potential of different soil management practices, this research contributes to the broader goal of achieving climate resilience, environmental sustainability, and food security in agricultural systems.</p>

Modeling of phosphate flux induced by flood resuspension on a macrotidal estuarine mudflat (Seine, France)

Coastal marine sediments can be either major scrubbers or eutrophication contributors to surface waters. Standard methods for direct measurement of nutrient fluxes at the sediment-water interface do not consider hydrodynamic forcing although several ex-situ studies suggest that sediment resuspension can dramatically increase dissolved fluxes. We provide a new model to quantify dissolved phosphate (PO43−) resuspension flux (JR) based on physical representation of its identified components: diffusion stimulation by exposure of deeper sediment layer with higher PO43− concentration in the porewater (JD), pore water mixing with overlying water (JM) and net adsorption/desorption from suspended sediments (JK). This approach was applied to field data from a Seine intertidal mudflat periodically submitted to millimetric erosion. On a tidal scale, the model output reveals a JR of 272.3 ± 360.0 μmol m−2 h−1 (± 52% from parameter uncertainty), well above flux calculated by application of Fick's first law (0.15 ± 0.85 μmol m−2 h−1) or by ex situ core incubation (40.8 μmol m−2 h−1). Iron bound phosphorus within suboxic layers buffers PO43− concentrations in superficial sediments leading to negligible contributions of JD and JM to total fluxes. Conversely, JK appears to be the main exchange pathway, even though improvements in turbidity measurement would allow this term to be defined more precisely. Correction required to enhance and control model robustness are described. These results show the importance of considering the dissolved PO43− resuspension flux in dynamic environments.

Induction of DEPP1 by HIF Mediates Multiple Hallmarks of Ischemic Cardiomyopathy.

HIF (hypoxia inducible factor) regulates many aspects of cardiac function. We and others previously showed that chronic HIF activation in the heart in mouse models phenocopies multiple features of ischemic cardiomyopathy in humans, including mitochondrial loss, lipid accumulation, and systolic cardiac dysfunction. In some settings, HIF also causes the loss of peroxisomes. How, mechanistically, HIF promotes cardiac dysfunction is an open question. We used mice lacking cardiac pVHL (von Hippel-Lindau protein) to investigate how chronic HIF activation causes multiple features of ischemic cardiomyopathy, such as autophagy induction and lipid accumulation. We performed immunoblot assays, RNA sequencing, mitochondrial and peroxisomal autophagy flux measurements, and live cell imaging on isolated cardiomyocytes. We used CRISPR-Cas9 gene editing in mice to validate a novel mediator of cardiac dysfunction in the setting of chronic HIF activation. We identify a previously unknown pathway by which cardiac HIF activation promotes the loss of mitochondria and peroxisomes. We found that DEPP1 (decidual protein induced by progesterone 1) is induced under hypoxia in a HIF-dependent manner and localizes inside mitochondria. DEPP1 is both necessary and sufficient for hypoxia-induced autophagy and triglyceride accumulation in cardiomyocytes ex vivo. DEPP1 loss increases cardiomyocyte survival in the setting of chronic HIF activation ex vivo, and whole-body Depp1 loss decreases cardiac dysfunction in hearts with chronic HIF activation caused by VHL loss in vivo. Our findings identify DEPP1 as a key component in the cardiac remodeling that occurs with chronic ischemia.

Comparison between Direct and Indirect Heat Flux Measurement Techniques: Preliminary Laboratory Tests

Direct and indirect approaches can be employed for estimating the heat flow through components in different application fields. In the building sector, the thermometric method is often applied by professionals for thermal transmittance evaluations. However, miscalculations can derive from inaccurate total heat transfer coefficients, and a consensus regarding the appropriate value to employ remains to be determined. Here, an apparatus was realized for laboratory tests and heat flux measurements were performed following direct and indirect approaches. Data acquired through a common heat flow sensor were compared with those computed through a post-processing based on radiative and convective estimations. The results were affected by the specific correlation adopted for computing the convective coefficients, with the percentage differences ranging from −9.8% to −0.4%. New measurement systems could be designed for automatically computing heat fluxes through indirect approaches, thus providing alternative solutions in the panorama of non-destructive tests for building energy diagnosis.

Measurement of solar pp neutrino flux using electron recoil data from PandaX-4T commissioning run* *This project is supported in part by the grants from the National Science Foundation of China (12090060, 12090063, 12105052, 12005131, 11905128, 11925502), the Office of Science and Technology, Shanghai Municipal Government (22JC1410100), and the National Science Foundation of Sichuan Province, China (2024NSFSC1371). We are grateful for

The proton-proton ( ) fusion chain dominates the neutrino production in the Sun. The uncertainty of the predicted neutrino flux is at the sub-percent level, whereas that of the best measurement is (10%). In this study, for the first time, we measure solar neutrinos in the electron recoil energy range from 24 to 144 keV using the PandaX-4T commissioning data with 0.63 tonne year exposure. The neutrino flux is determined as , which is consistent with the Standard Solar Model and existing measurements, corresponding to an upper flux limit of at 90% C.L..

Numerical investigation of mixing and heat transfer in a 7.9 m JP-8 pool fire

The response of objects engulfed in, and adjacent to, large-scale pool fires is of interest in accident and safety assessments. In this study, Fuego, a low-Mach turbulent reacting flow code was used to study conjugate heat transfer in a 7.9 m diameter JP-8 pool fire. Simulations were designed to replicate past experimental measurements (Blanchat et al., 2006) of incident heat flux to three cylindrical calorimeters in and around the pool fire. Two turbulent combustion models were compared directly - the eddy dissipation concept and a more recently developed unsteady flamelet model. First and second order spatial and temporal discretization schemes were also compared to assess the performance of low-dissipation numerical operators. Heat flux predictions to the transportation size calorimeter outside the fire were within experimental uncertainties. Inside the fire, experimental measurements were higher than predicted values and may have been a consequence of soot deposition and augmented participating media radiation from soot and fuel vapor. Simulation predictions improved in cases where turbulent kinetic energy and mixing were more resolved. This work, and others referenced herein, suggest that spatial resolution on the order of 0.5–1.0 cm may be required to fully resolve fluid instabilities, vortex production between fire plumes and crosswind, soot production, and fuel-air mixing. This presents a substantial computational challenge for safety assessments of engulfed objects in fully turbulent pool fires.