Back Flux Research Articles

Back flux during anaerobic oxidation of butane support archaea-mediated alkanogenesis

Microbial formation and oxidation of volatile alkanes in anoxic environments significantly impacts biogeochemical cycles on Earth. The discovery of archaea oxidizing volatile alkanes via deeply branching methyl-coenzyme M reductase variants, dubbed alkyl-CoM reductases (ACR), prompted the hypothesis of archaea-catalysed alkane formation in nature (alkanogenesis). A combination of metabolic modelling, anaerobic physiology assays, and isotope labeling of Candidatus Syntrophoarchaeum archaea catalyzing the anaerobic oxidation of butane (AOB) show a back flux of CO2 to butane, demonstrating reversibility of the entire AOB pathway. Back fluxes correlate with thermodynamics and kinetics of the archaeal catabolic system. AOB reversibility supports a biological formation of butane, and generally of higher volatile alkanes, helping to explain the presence of isotopically light alkanes and deeply branching ACR genes in sedimentary basins isolated from gas reservoirs.

Water transport across the membrane of a direct toluene electro-hydrogenation electrolyzer: Experiments and modelling

Toluene/methylcyclohexane is a promising liquid organic hydride for hydrogen storage and transport under ambient conditions. Direct toluene electro-hydrogenation electrolyzers, utilizing proton exchange membrane technology, offer benefits in reducing the reversible decomposition voltage and eliminating theoretical heat losses associated with conventional hydrogenation methods. Nevertheless, water transport across the membrane can inhibit the supply of toluene to reaction sites at the cathode. This study investigates water transport across the Nafion™ 117 membrane of an in-house electrolyzer cell, employing sulfuric acid and toluene solutions as the anode and cathode reactant, respectively, and operating at current densities from 0.1 to 0.8 A/cm2. The experiments show that the cathode toluene concentration has a negligible effect on drag water, while water flux increases with electric current and decreases with higher anode sulfuric acid concentrations. The modelling approach assumes electro-osmosis and diffusion mechanisms govern water transport. Simulations predict a linear decrease in the electro-osmotic drag coefficient from 2.3 to 1.6 as the sulfuric acid concentration rises from 0.1 to 1.5 mol/L, while the back diffusion flux increases linearly up to 2 mg/(min·cm2). These findings closely align with experimental data and previous literature, despite the high complexity of water transport in polymer electrolyte membranes.

Neural Network-Driven Sensorless Speed Control of EV Drive Using PMSM

To reduce pollution and energy consumption, particularly in the automotive industry, energy saving is the main concern, and hence, Electric vehicles (EVs) are getting significantly more attention than vehicles with internal combustion engines (IC engines). Electric motors used in Electric Vehicles (EVs) must have high efficiency for maximum utilization of the energy from the batteries or fuel cells. Also, these motors must be compact, lightweight, less expensive and very easily recycled. Further, to obtain better dynamic performance, various motor control strategies are used to control the speed of the motor. And to have increased reliability, sensorless speed control techniques that offer sufficiently high performance are used. The sensorless speed control techniques are largely divided into three groups: state observer methods, indirect measurement methods and saliency-based methods. Generally, the state observer uses back emf or flux linkage to estimate the speed of the motor. Since the back emf is directly proportional to the rotor speed, at low-speed back emf based method will give poor performance. The current-based Model Reference Adaptive System (MRAS) model is also popular for estimating low speed; however, assessments deteriorate during high performance applications such as EV. This paper presents an artificial neural network (ANN)-deployed sensorless speed control of permanent magnet synchronous motor (PMSM) drive used in EVs. In this paper, the estimation of speed using the current-based MRAS model is discussed and compared with the proposed ANN-based controller, which shows significant improvement in the performance of EV motor drives. The MATLAB simulation and experimental results are presented to validate the proposed algorithm.

One-dimensional modelling and simulation of multiple solution characteristics of hydrocarbon fuel flow excursion in scramjet parallel cooling channels

To investigate flow excursion of hydrocarbon fuel in parallel cooling channels of the scramjet, one-dimensional steady-state model of hydrocarbon fuel flow and heat transfer in parallel channels is developed and validated. Flow excursion occurs in the negative slope region of the fuel hydrodynamic curve. Multiple solutions (stable and unstable ones) of flow and temperature distributions are presented. Further simulations are developed at the pressure of 2.2–7.0 MPa, heat flux of 0.5–3.0 MW/m2. Influencing factors such as back pressure, hot resistance, heat flux, thermal deviation and parallel channels number are studied. Higher back pressure affects the fuel properties and negative slope of hydrodynamic curve disappears, which restrains the flow excursion. Hot resistance presents a non-monotonic influence on flow excursion. Hot resistance that is too large or too small suppresses flow excursion. Higher heat flux magnifies the flow excursion amplitude and narrows the flow range of multiple solutions. When channel number increases, the feature of multiple solutions is much more complex and the flow excursion modes becomes tricky.

Uncoupling Proteins and Regulated Proton Leak in Mitochondria.

Higher concentration of protons in the mitochondrial intermembrane space compared to the matrix results in an electrochemical potential causing the back flux of protons to the matrix. This proton transport can take place through ATP synthase complex (leading to formation of ATP) or can occur via proton transporters of the mitochondrial carrier superfamily and/or membrane lipids. Some mitochondrial proton transporters, such as uncoupling proteins (UCPs), transport protons as their general regulating function; while others are symporters or antiporters, which use the proton gradient as a driving force to co-transport other substrates across the mitochondrial inner membrane (such as phosphate carrier, a symporter; or aspartate/glutamate transporter, an antiporter). Passage (or leakage) of protons across the inner membrane to matrix from any route other than ATP synthase negatively impacts ATP synthesis. The focus of this review is on regulated proton transport by UCPs. Recent findings on the structure and function of UCPs, and the related research methodologies, are also critically reviewed. Due to structural similarity of members of the mitochondrial carrier superfamily, several of the known structural features are potentially expandable to all members. Overall, this report provides a brief, yet comprehensive, overview of the current knowledge in the field.

Control of Transport Water in Direct Toluene Electro-Hydrogenation Electrolyzer

Introduction Recently, to decrease carbon dioxide emissions, utilization of renewable energy has been expected. Therefore, the large-scale storage and transportation of hydrogen as secondary energy is needed for effective utilization of fluctuated and unevenly distributed renewable energy. Toluene (TL) / methylcyclohexane (MCH) organic hydride system is one of the best candidates of hydrogen energy carrier because TL and MCH are liquid at ambient temperature and pressure, and it would be able to use oil infrastructure. To improve the energy conversion efficiency for TL hydrogenation using renewable electricity, we have studied direct electro-hydrogenation of TL with water decomposition using proton exchange membrane (PEM). The rate-determining step at the cathode for the hydrogenation of TL is the mass transfer of TL to the cathode catalyst layer [1]. One of the major factors that inhibit the supply of TL to the reaction field is transport water from the anode through the membrane. The accumulation of the water in the catalyst layer inhibits the supply of TL and reduces the current efficiency, but its behavior has not been clarified. In this study, the influence of current density, sulfuric acid concentration supplied to the anode and cell temperature on the amount of the transport water were evaluated in order to control the water in direct TL electro-hydrogenation electrolyzer. Experimental A DSE® (De Nora Permelec, Ltd.) for the oxygen evolution and Nafion 117® (Du Pont) were used as the anode and PEM, respectively. Carbon paper (10BC, SGL carbon ltd.) loaded with 0.5 mg cm-2 of PtRu/C (TEC61E54, Tanaka Kikinzoku Kogyo) was also used as the cathode. The cathode was hot-pressed on the PEM at 120 oC and 15 MPa for 3 min to fabricate a membrane cathode assembly. The anode and cathode compartments were circulated 0-1.5 M (= mol dm-3) H2SO4 and 10% TL/MCH, respectively. Operation temperature of the electrolyzer conducted at 50-80 oC. As the electrochemical measurement, chronopotentiometry at 0.1-0.4 A cm-2 was conducted for 20 min, and the amount of water was evaluated by measuring the weight of it in the reservoir after electrolysis. The concentration of sulfuric acid of the water was determined by measuring the pH. Results and discussion The water permeates the PEM by electro-osmosis and diffusion, and the water flux is given by eq. 1 in the images [2]. The linear region of Fig. 1 would mean water flux had linear relation to current density with constant apparent electro-osmotic coefficient with constant back diffusion flux from eq. 1. The constant back diffusion would mean that the aqueous phase is formed in the cathode catalyst layer, and its activity would be constant.Figure 1 shows dependence of cell voltage and water flux at 60 oC with various sulfuric acid concentrations on current density. There was no significant difference in cell voltages except for 0 M. Relationships between the water flux and the current density were linear except 0.1 A cm-2 at 1.5 M. The water flux decreased as the sulfuric acid concentration increases except 0 M. The absolute value of the intercept by extrapolating the linear region increased with sulfuric acid concentration. The slope of the straight line also decreased as the sulfuric acid concentration increased. In addition, the water detected on the cathode side was sulfuric acid whose concentration was about one-tenth that of the anode. The sulfuric acid concentration in the membrane would also change with the anodic sulfuric acid concentration. The electro-osmotic coefficient obtained from the slope of Fig.1 would decrease with the increase of the sulfuric acid concentration in the membrane.Figure 2 shows the diffusion flux and the concentration difference between the anolyte and cathode side sulfuric acid, which transported from anode side, as functions of the anolyte concentration. They increased linearly with anolyte concentration. Correspondingly, the back diffusion flux, which is affected by the sulfuric acid concentration difference, would have increased linearly with increasing anolyte concentration. Acknowledgements This work was supported by the Toyota Mobility Foundation. Anode was supplied by De Nora Permelec Ltd. We appreciate the person concerned them. Reference [1] K. Nagasawa, Y. Sawaguchi, A. Kato, Y. Nishiki, S. Mitsushima, Electrocatalysis, 8, 164, (2017).[2] T. E. Springer, T. A. Zawodzinski, S. Gottesfeld, J. Electrochemical Society, 138, 2334, (1991). Figure 1

MINORITY CARRIERS MOBILITY DETERMINATION IN THE BASE REGION OF N+-P-P+ SILICON SOLAR CELL UNDER EFFECTS OF IRRADIATION FLUX, TEMPERATURE AND MAGNETIC FIELD

The aim of this study is to show the influence of temperature on the relative value of the short-circuit photocurrent density obtained from an n+-p-p+silicon solar cell front illuminated with modulated polychromatic light. The solar cell was already subjected to charged particules irradiation flux (Φp) and intensity (kl,) and remained under both magnetic field (B) and temperature (T). Thus, the graphical representation of the relative value of the short-circuit photocurrent density as a function of the square of the magnetic field (B) yields to determine the slope, which is related to the mobility of minority carriers in the base. It is obtained for a back surface field silicon solar cellunder both temperature and irradiation flux of charged particules.

Analysis of Effect of the Magnetization Distribution of Multi-Pole PM on SPMSM Performance Using Equivalent Magnetic Circuit Considering Dead Zone

In multi-pole permanent magnets (PMs) such a ring-type PMs, as multi-poles are magnetized in one segment, the ends of each pole are weakly magnetized, which is known as the dead zone. Thus, when analyzing characteristics of the motor with multi-pole PMs, accurate results can be obtained by considering the magnetization distribution. For this reason, this paper proposed an equivalent magnetic circuit (EMC) for external-rotor surface-mounted permanent magnet synchronous motors (SPMSMs) considering the dead zone to analyze the effects of the dead zone on the characteristics of the motor. As the magnetization in the dead zone gradually decreases toward the end of the pole, the magnetization distribution is assumed to have a trapezoidal shape. To describe the magnetization distribution, each pole was divided into several elements, and the equivalent residual magnetic flux density was applied to the elements of the dead zone. Finally, the validity of the proposed EMC was verified by comparing the back electro-motive force and air-gap magnetic flux density obtained by the EMC, finite-element analysis, and test.

Lyotropic Liquid Crystal-Based Membranes for Water Remediation: Fabrication, Characterization and Performance Evaluation.

In water remediation, biomimetic membranes are gaining much attention due to their selectivity, dynamic stability, nontoxicity, and biocompatibility. Lyotropic liquid crystals (LLCs) are self-organizing networks that can conform to an array of geometries with high pore densities. As such, LLCs are excellent membrane materials for water applications because they are water insoluble and are manipulated to conform to an array of morphologies that provide natural water channels that are readily tunable in size. They have the ability to create uniform pores, between the range of 1 and 5 nm, with large surface areas. Thus, this work focuses on the design, fabrication, and characterization of LLC-modified Janus-type membranes for forward osmosis applications. Physical characterization of the membranes was performed using scanning electron microscopy (SEM), and the results show an open-pore radius and the presence of both finger- and sponge-like pores depending on membrane preparation. The contact angle assessment indicates that as the membranes are further modified with other polymers (e.g., PAN), higher hydrophilicity and surface energy are achieved. Moreover, the Brunauer–Emmett–Teller (BET) analysis showed a significant variation in the pore distribution between membranes. Functionalized membranes presented satisfactory water flux and superior salt rejection compared to nonfunctionalized membranes. SupPACMoDS membranes are 83% more efficient at preventing salt back flux than the nonmodified version. This is credited to the thickness and pore structure provided by the PAN support layer in the membrane.

Design and Analysis of a Hybridly Excited Asymmetric Stator Pole Doubly Salient Machine

This article presents the design and analysis of a 12/7 (numbers of stator/rotor poles) hybridly excited asymmetric stator pole doubly salient machine (HEASPDSM) with a main focus on the special topology and operational principle by using the analytical and 2-D finite element analysis. A full comparison is conducted on the average torque, torque ripples, no-load back electromotive force and flux regulation capacity under the condition of different structural parameters, which can provide good references to the machine design. A 12/7 HEASPDSM is designed and the main performance indexes are analyzed in detail. Based on the parameters, the performance of 12/7 HEASPDSM is compared with traditional 6/7 doubly salient permanent magnet machine (DSPMM) with the same volume and thermal load. Finally, a prototype of the 12/7 HEASPDSM is manufactured and tested to validate the theoretical analysis. The results fully demonstrate that the HEASPDSM possesses the merits of strong flux regulation capability, higher torque density, and wider constant power speed range benefitted from the dc field winding than the traditional DSPMM.

The value of DCE-MRI in predicting IDH gene mutation of high-grade gliomas

Objective: To investigate the value of quantitative and semiquantitative parameters of DCE-MRI in predicting IDH gene mutation of high-grade gliomas before the operation. Methods: Twenty-six individuals with surgically and pathologically proved WHO Ⅲ-Ⅳ gliomas collected from April 2016 to June 2019 in First People's Hospital of Changzhou, were divided into two groups, IDH mutation group (7 cases, 27-67 years, 3 males and 4 females,) and IDH gene wild group (19 cases, 42-75 years, 12 males and 7 females) according to the results of molecular pathology. All individuals underwent conventional plain (T(1)WI, T(2)WI), enhanced MR scanning (T(1)WI) and dynamic contrast enhancement (DCE). Four quantitative parameters:volume transfer constant (K(trans)), ratio constant of back flux (Kep), extravascular extracellular space fractional volume (Ve), and blood plasma fractional volume (Vp), and four semiquantitative parameters: time to peak (TTP), maximum concentration (MAX Conc), initial area under the gadolinium concentration-time curve (IAUC) and maximum slope of decrease (MAX Slope) were measured. The independent samples t test (normal distribution and homogeneity of variance) or Mann-Whitney rank sum test (abnormal distribution or heterogeneity of variance) were used to compare the differences of quantitative and semiquantitative parameters between IDH gene mutation group and IDH gene wild type group. Receiver operating characteristic (ROC) curve was used to evaluate the efficiency of quantitative and semiquantitative parameters in predicting IDH gene mutation of high-grade gliomas. Results: The value of K(trans),TTP in IDH mutated group were 0.096 (0.080,0.135)/min and (3.95±0.34) s, respectively. The value of K(trans), TTP in IDH wild type group were 0.168 (0.132, 0.337)/min and (2.58±1.15) s, respectively. The value of K(trans) in IDH mutated group was significantly less than the value of K(trans) in IDH gene wild type group (Z value was -2.168, P value was 0.030). The value of K(trans) in IDH mutated group was significantly greater than the value of K(trans) in IDH gene wild type (Z value was -2.630, P value was 0.007). The area under the ROC curve (AUC) of K(trans) and TTP in predicting IDH gene mutation of high-grade gliomas was 0.782 and 0.842, respectively. The specificity of K(trans) was higher (73.7%), The sensitivity of TTP was the higher (100.0%). Combined K(trans)and TTP were the best for predicting IDH gene mutation of high-grade gliomas, AUC was 0.865. Conclusion: Quantitative and semiquantitative parameters of DCE-MRI can help to predict IDH gene mutation of high-grade gliomas before the operation.

Evaluation of energy spectrum around structural materials in radiation environments

Structural materials such as stainless steel (SUS) in nuclear reactor are exposed by the environment of ionizing radiations so that their corrosion and degradation take place. These radiation effects depend strongly on the quality of radiation (energy, kind) around the materials. The metallic materials with various thickness have been examined in previous works on the radiation effects, but not with a common thickness. The different thickness would give the different radiation quality, leading to the different results of radiation effects on the materials. In this work, when radiation sources of 137Cs, 90Sr and 90Y were assumed to be put in the front of a plain SUS304 plate as a typical material submerged in water, energy spectra of secondary photons and electrons at the front and back sides of plate were simulated with changing the thickness of plate, and spacing between the source and plate by using a Monte Carlo calculation code of PHITS.In the case of 137Cs gamma-ray (monochromatic 662 keV), the energy spectra at the front side was smaller than those at the back side due to the existence of plate. Then the dependence of spectra on the plate thickness was observed more clearly at the back side than at the front side. In the cases of 90Sr and 90Y beta-rays (maximum 546 and 2284 keV), the energy spectra were clearly different from those in the case of gamma-ray. At the front side, the energy and flux of electrons were higher than those of photons. Also, the energy spectra of electrons and photons were not dependent on the plate thickness. At the back side, the energy and flux of electrons were much lower than those of photons reversely. It was clearly shown how the energy spectra of photons and electrons varied with the incident radiation type, the spacing, and the thickness.The average energies of secondary radiations were further estimated, and the changes of incident radiation to the secondary ones were discussed especially in terms of the lowering of radiation energy.

A Hybrid Interior Permanent Magnet Variable Flux Memory Machine Using Two-Part Rotor

In this paper, a novel hybrid permanent magnet variable flux memory machine using two-part rotor is proposed whose rotor comprises an AlNiCo part and a NdFeB part adjacent to each other on the same shaft. With the proposed topology, flexible flux controllability can be achieved since the magnetization state of AlNiCo can be adjusted by a temporary current pulse. The detailed operating principles are described, and the split ratio and some key design parameters are optimized. Then, the electromagnetic performance of the proposed machine with emphases on back electromotive force, flux density, flux-weakening performance, and torque characteristics is investigated. Finally, 3-D finite-element validation is implemented and a machine prototype has been manufactured and tested to validate the analyses.

A Parallel Hybrid Excited Machine Using Consequent Pole Rotor and AC Field Winding

Hybrid excited (HE) machines with both permanent magnet (PM) and field winding excitations, inherit the benefits of PM machines and improve the flux regulation capability. This paper proposes a novel consequent pole HE (CPHE) machine. The PM pole pair and the iron pole are alternately placed on the rotor, while both the armature winding and ac field winding are located on the stator slots, which achieve the brushless excitation. Since the flux of the field winding goes through the iron poles, the PM and field winding exhibit parallel magnetic paths, which is favorable for the flux regulation and avoids the irreversible demagnetization of the PMs. In this paper, the operating principle of the proposed CPHE machine is illustrated. Moreover, the electromagnetic performance, including back electromotive force, torque, and flux regulation range considering different coil pitch of field winding is analyzed by finite-element analysis. It is demonstrated that the proposed machine exhibits flexible flux regulation capability, which is suitable for applications requiring wide speed range operation or voltage regulation.

Metabolic tracing unravels pathways of fungal and bacterial amino sugar formation in soil

SummaryThe present study aimed to reveal the steps in the formation of fungal and bacterial amino sugars (AS) from glucose. Glucose labelled uniformly and position‐specifically at C‐1, C‐2, C‐4 and C‐6 was applied to an agricultural soil. Fungal and bacterial pathways of AS formation were reconstructed by a new approach: 13C recovery from individual C positions of glucose in AS by IC‐O‐IRMS. Only 0.75% of 13C from initially applied glucose was incorporated into AS within 10 days and followed the order: glucosamine > galactosamine > muramic acid. Relative incorporation of 13C (% of AS‐C) had the largest values for bacterial muramic acid and the smallest for fungal galactosamine. This reflects faster turnover of bacterial than fungal cell walls. A maximum of 55% ± 19% of the 13C incorporated in glucosamine was derived from intact, untransformed glucose. The smallest recovery was observed for C‐1 and C‐4. Recovery of C‐1 even decreased from day 3 to day 10, reflecting the metabolization by the pentose phosphate pathway. To be incorporated into AS, metabolites resulting from either the pentose phosphate pathway or glycolysis needed to be reconstructed to glucose by the reversible pathways of gluconeogenesis. The direct formation of AS (e.g. intact recovery of the glucose precursor), as well as amino sugar formation from recycled metabolites allocated to the hexose pool by back flux, occurred in parallel. Bacterial muramic acid showed the most variation in the recovery of individual C positions during 10 days, which reflects its intensive transformation by glycolysis, pentose phosphate pathway and gluconeogenesis. It is explained by the lower metabolic activity of fungi than bacteria at steady‐state conditions. The present approach enabled us to analyse the biochemical pathways in bacteria and fungi, which will considerably improve our understanding of the formation and stabilization of microbially derived SOM compounds.Highlights Fungal and bacterial pathways of the formation of amino sugars from glucose are reconstructed Intact use of glucose is distinguished from recycling by a metabolic tracing approach Half of the precursor (glucose) is metabolized prior to incorporation into amino sugars Intracellular recycling plays a crucial role in microbial SOM formation

Multiparametric imaging-based differentiation of lymphoma and glioblastoma: using T1-perfusion, diffusion, and susceptibility-weighted MRI

To compare the diagnostic performance of T1 perfusion magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging (SWI) for differentiating primary central nervous system lymphoma (PCNSL) and glioblastoma (GBM). This retrospective study comprised a cohort of 70 patients with glioblastoma and 30 patients with PCNSL. T1 perfusion MRI-derived rCBV_corr (leakage corrected relative cerebral blood volume), apparent diffusion coefficient (ADC) derived from DWI, and intratumoural susceptibility signals intensity (ITSS) measured on SWI were evaluated in these 100 patients. The Mann-Whitney U-test was used for pairwise comparison between groups. The diagnostic performance for differentiating PCNSL from glioblastoma was evaluated by using univariate and multivariable logistic regression analyses and receiver operating characteristic (ROC) analysis. Minimum ADC, maximum rCBVs_corr, kep (back flux exchange rate), and ITSS scores were significantly lower in patients with PCNSL than in those with glioblastoma (p<0.05). On ROC analysis, ITSS showed the best discrimination ability for differentiation of GBM and PCNSL with an area under the ROC curve (AUC) of 0.80. rCBV_corr and ADC showed AUCs of 0.68 and 0.63, respectively. Multiparametric assessment using ADC, rCBV_corr, kep, and ITSS scores significantly increased the diagnostic ability for differentiating PCNSL from GBM as compared to mean ADC, mean rCBV_corr, and ITSS alone or a combination of these parameters. The multiparametric model could correctly discriminate 84% of tumours with a sensitivity and specificity of 90% and 70% with an AUC of 0.92. Multiparametric MRI evaluation using DWI, T1 perfusion MRI, and SWI enabled reliable differentiation of PCNSL and GBM in the majority patients, and these results support an integration of advanced MRI techniques for the diagnostic work-up of patients with these tumours.

Aerothermal Measurements from the ExoMars Schiaparelli Capsule Entry

The instrumentation package was developed to measure aerothermal parameters on the back cover of the ExoMars Schiaparelli lander during Martian entry. The aerothermal sensors called Combined Aerothermal and Radiometer Sensor (COMARS) combine four discrete sensors, measuring static pressure, total heat flux, temperature, and radiative heat flux. After passing all acceptance tests, the Schiaparelli capsule was launched on top of the Proton launcher on March 14, 2016. All sensors operated nominally during the complete entry phase. But the complete data package is not available due to an anomaly that led to the failure of Schiaparelli shortly before landing. Nevertheless, a subset of the flight data was transmitted real-time during the entry and was received by the ExoMars 2016 orbiter, with the exception of the plasma blackout phase. The radiative heat flux on the back cover close to the vehicle shoulder was measured successfully for the first time on a Mars entry vehicle. The measured maximum radiative contribution was 61% of the total heat flux at the first measurement point after the blackout phase and 33% for the next measured trajectory point 10 s later. These measurements confirm recent findings that radiative heating can be a significant portion of total heating on the back cover during Mars entry. The maximum back cover total heat flux rate was measured at approximately 9% of the calculated stagnation point heat flux on the front cover. All measured heat fluxes on the back cover were below the levels that were used to design the thermal protection system.

A new role for the exhaled nitric oxide as a functional marker of peripheral airway caliber changes: a theoretical study.

Although considered as an inflammation marker, exhaled nitric oxide (FENO) was shown to be sensitive to airway caliber changes to such an extent that it might be considered as a marker of them. It is thus important to understand how these changes and their localization mechanically affect the total NO flux penetrating the airway lumen ( JawNO), and hence FENO, independently from any inflammatory status change. In this work, a new model was used. It simulates NO production, consumption, and diffusion inside the airway epithelium, NO excretion from the epithelial wall into the airway lumen and, finally, its axial transport by diffusion and convection in the airway lumen. This model may also consider the possible presence of a fluid layer coating the epithelial wall. Simulations were performed. They show the great sensitivity of JawNO to peripheral airway caliber changes. Moreover, FENO shows distinct behaviors, depending on the location of the caliber change. Considering a bronchodilation, absence of FENO change was associated with dilation of central airways, FENO increase with dilation down to pre-acinar small airways, and FENO decrease with intra-acinar dilation due to the amplification of the back diffusion flux. The presence of a fluid layer was also shown to play a significant role in FENO changes. Altogether, the present work theoretically supports that specific FENO changes in acute situations are linked to specifically located airway caliber changes in the lung periphery. This opens the way for a new role for FENO as a functional marker of peripheral airway caliber change. NEW & NOTEWORTHY Using a new model of nitric oxide production and transport, allowing realistic simulation of airway caliber change, the present work theoretically supports that specific changes of the molar fraction of nitric oxide in the exhaled air, occurring without any change in the inflammatory status, are linked to specifically located airway caliber changes in the lung periphery. This opens the way for a new role for FENO as a functional marker of peripheral airway caliber change.

Heating of the polar caps of old radio pulsars

The X-ray luminosity and temperature of the polar cap heated by the back flux of positrons from a radio pulsar with a period P ∼ 1 s and a magnetic field B ~ 1012 G have been estimated. An additional source of X-ray emission—a thin, hotter semiring on the polar-cap periphery—is shown to also exist. It is heated by the back flux of electrons from the light cylinder. Furthermore, the electric field near the hot semiring accelerates the ions of the surface layer that leave the neutron-star magnetosphere. The semiring area is smaller than the polar-cap area approximately by a factor of 100, i.e., at the same luminosity the temperature is higher by a factor of 3. The observed X-ray emission from old radio pulsars is the emission from thin hot polar-cap semirings. The emission from the polar caps themselves is strongly attenuated by interstellar absorption.

Field-Weakening Performance Improvement of the Yokeless and Segmented Armature Axial Flux Motor for Electric Vehicles

In order to avoid the unsafe operation and raise efficiency of yokeless and segmented armature axial flux motors at high speed, the control current of air gap flux is expected to be as small as possible with the same field-weakening effect. To reduce the control complexity, a new structure of module poles with a combination of permanent magnet and soft magnetic material is proposed, which has the characteristics of lower d-axis reluctance and a higher performance of yokeless and segmented armature axial flux motor with surface mounted permanent magnet. According to finite element analysis (FEA), the flux distributions of a rotor pole in no-load and demagnetization condition are contrasted, and under this new configuration, the derivative analytical models of back electromotive-force (EMF), electromagnetic torque, and air gap flux are validated, moreover, the influence of soft magnetic material of rotor poles on controlling the air gap flux is investigated in different load. Based on a particular objective function, the combination of permanent magnet and soft magnetic material is optimized. The results show that optimal solution of field-weakening performance of yokeless and segmented armature axial flux motors can be improved effectively and legitimately.