To see the other types of publications on this topic, follow the link: Series Iron Loss.
Journal articles on the topic 'Series Iron Loss'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Series Iron Loss.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Wang, Kang, Ruituo Huai, Zhihao Yu, Xiaoyang Zhang, Fengjuan Li, and Luwei Zhang. "Comparison Study of Induction Motor Models Considering Iron Loss for Electric Drives." Energies 12, no. 3 (2019): 503. http://dx.doi.org/10.3390/en12030503.
Full textAbstract:
In a variety of motor models, the effects of iron-loss (ILS) on motor control accuracy and efficiency are generally ignored. This makes it difficult for the motor control system to obtain accurate control parameters (especially on high speed and low load conditions), and limits the improvement of motor control accuracy. This paper aims to clarify the influence of different ILS modeling and observation methods on motor control performance. Three equivalent models of motors with iron losses are compared. These models are: A parallel model, a series model and the simplified traditional model. Three tests are conducted to obtain the effect of ILS perturbation on ILS estimation results, and then to derive the sensitivity of the motor state and torque to the perturbation. These test conditions include: Ideal no-load, heavy-load, locked-rotor, and ILS perturbations during speed regulation. Simulation results show that the impedance and excitation characteristics of the series model and the parallel model are similar, and the traditional model has the best speed regulation smoothness. The ILS estimation errors of the series model is nearly constant and easy to compensate. For accurate ILS observation results, the series model can achieve better control accuracy.
2
LEPIARCZYK, Dariusz, Wacław GAWĘDZKI, and Jerzy TARNOWSKI. "A STUDY OF TRIBOLOGICAL LOAD CAPACITY OF VARIOUS FRICTION PAIRS." Tribologia 272, no. 2 (2018): 91–97. http://dx.doi.org/10.5604/01.3001.0010.6310.
Full textAbstract:
The paper presents and experimentally verifies a testing method of friction pairs between various materials: steel-cast iron, cast iron-cast iron, and cast iron-ferodo. The applied methodology for the evaluation of tribological mating of a friction part allows for determining the time series of friction torque and mechanical power transmitted by a friction pair at slippage. Time series of parameters variability in the investigated friction process after the loss of contact are presented. In addition, relationships are presented that allow for determining the basic friction pair parameters: friction torque, friction coefficient, and mechanical power. This is a basis for determining the tribological load capacity of a friction pair whose measure has been assumed as the maximum value of torsional torque and mechanical power transmitted by the tested specimens.
3
Hanaa, Elsherbiny, Kamal Ahmed Mohamed, and A. Elwany Mahmoud. "Online efficiency optimization of IPMSM for electric vehicles." International Journal of Power Electronics and Drive Systems (IJPEDS) 12, no. 3 (2021): 1369–78. https://doi.org/10.11591/ijpeds.v12.i3.pp1369-1378.
Full textAbstract:
This paper presents an online efficiency optimization method for the interior permanent magnet synchronous motor (IPMSM) drive system in an electric vehicle (EV). The proposed method considers accurately the total system losses including fundamental copper and iron losses, harmonic copper and iron losses, magnet loss, and inverter losses. Therefore, it has the capability to always guarantee maximum efficiency control. A highly trusted machine model is built using finite element analysis (FEA). This model considers accurately the magnetic saturation, spatial harmonics, and iron loss effect. The overall system efficiency is estimated online based on the accurate determination of system loss, and then the optimum current angle is defined online for the maximum efficiency per ampere (MEPA) control. A series of results is conducted to show the effectiveness and fidelity of proposed method. The results show the superior performance of proposed method over the conventional offline efficiency optimization methods.
4
Jinhwan Jung and Kwanghee Nam. "A vector control scheme for EV induction motors with a series iron loss model." IEEE Transactions on Industrial Electronics 45, no. 4 (1998): 617–24. http://dx.doi.org/10.1109/41.704890.
Full text
5
Elsherbiny, Hanaa, Mohamed Kamal Ahmed, and Mahmoud A. Elwany. "Online efficiency optimization of IPMSM for electric vehicles." International Journal of Power Electronics and Drive Systems (IJPEDS) 12, no. 3 (2021): 1369. http://dx.doi.org/10.11591/ijpeds.v12.i3.pp1369-1378.
Full textAbstract:
<span>This paper presents an online efficiency optimization method for the interior permanent magnet synchronous motor (IPMSM) drive system in an electric vehicle (EV). The proposed method considers accurately the total system losses including fundamental copper and iron losses, harmonic copper and iron losses, magnet loss, and inverter losses. Therefore, it has the capability to always guarantee maximum efficiency control. A highly trusted machine model is built using finite element analysis (FEA). This model considers accurately the magnetic saturation, spatial harmonics, and iron loss effect. The overall system efficiency is estimated online based on the accurate determination of system loss, and then the optimum current angle is defined online for the maximum efficiency per ampere (MEPA) control. A series of results is conducted to show the effectiveness and fidelity of proposed method. The results show the superior performance of proposed method over the conventional offline efficiency optimization methods.</span>
6
Weber, L., C. Völker, A. Oschlies, and H. Burchard. "Iron profiles and speciation of the upper water column at the Bermuda Atlantic time-series Study site: a model based sensitivity study." Biogeosciences Discussions 4, no. 2 (2007): 823–69. http://dx.doi.org/10.5194/bgd-4-823-2007.
Full textAbstract:
Abstract. A one-dimensional model of the biogeochemistry and speciation of iron is coupled with the General Ocean Turbulence Model (GOTM) and a NPZD-type ecosystem model. The model is able to simulate the temporal patterns and vertical profiles of dissolved iron (dFe) in the upper ocean at the Bermuda Atlantic Time-series Study site reasonably well. Subsurface model profiles strongly depend on the parameter values chosen for the loss processes for iron, colloidal aggregation and scavenging onto particles. Current estimates for these parameters result in depletion of dFe. A high stability constant of iron-binding organic ligands is required to reproduce the observed degree of organic complexation below the mixed layer. A solubility of atmospherically deposited iron higher than 2% lead to dFe concentrations incompatible with observations. Despite neglecting ultraviolet radiation, the model produces diurnal variations and mean vertical profiles of H2O2 and iron species that are in good agreement with observations.
7
Odawara, S., and K. Fujisaki. "Fundamental Iron Loss Characteristics of Ring Cores Connected in Series and Parallel under Inverter Excitation." Journal of the Magnetics Society of Japan 40, no. 3 (2016): 61–66. http://dx.doi.org/10.3379/msjmag.1603r002.
Full text
8
Weber, L., C. Völker, A. Oschlies, and H. Burchard. "Iron profiles and speciation of the upper water column at the Bermuda Atlantic Time-series Study site: a model based sensitivity study." Biogeosciences 4, no. 4 (2007): 689–706. http://dx.doi.org/10.5194/bg-4-689-2007.
Full textAbstract:
Abstract. A one-dimensional model of the biogeochemistry and speciation of iron is coupled with the General Ocean Turbulence Model (GOTM) and a NPZD-type ecosystem model. The model is able to simulate the temporal patterns and vertical profiles of dissolved iron (dFe) in the upper ocean at the Bermuda Atlantic Time-series Study site reasonably well. Subsurface model profiles strongly depend on the parameter values chosen for the loss processes for iron, colloidal aggregation and scavenging onto particles. Estimates for these parameters based on observations in particle-rich waters result in depletion of dFe. A high stability constant of iron-binding organic ligands is required to reproduce the observed degree of organic complexation below the mixed layer. The scavenging residence time for iron in the model is shortest in spring and summer, because of the larger abundance of particles, and increases with depth towards values on the order of a hundred years. A solubility of atmospherically deposited iron higher than 2% lead to dFe concentrations incompatible with observations. Despite neglecting ultraviolet radiation, the model produces diurnal variations and mean vertical profiles of H2O2 and iron species that are in good agreement with observations.
9
Hussain, Sajid, and David Lowther. "The prediction of iron losses under PWM excitation using the classical Preisach model." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 35, no. 6 (2016): 1996–2006. http://dx.doi.org/10.1108/compel-03-2016-0126.
Full textAbstract:
Purpose The losses incurred in ferromagnetic materials under PWM excitations must be predicted accurately to optimize the design of modern electrical machines. The purpose of this paper is to employ mathematical hysteresis models (i.e. classical Preisach model) to predict iron losses in electrical steels under PWM excitation without compromising the computational complexity of the model. Design/methodology/approach In this paper, a novel approach based on the dynamic inverse Preisach model is proposed to model the iron losses. The PWM magnetic flux density waveform is decomposed into its harmonic component using Fourier series and a weighted Everett function is computed based on these harmonic components. The Preisach model is applied for the given flux waveform and results are validated against the measurements. Findings The paper predicts the total iron loss by computing a weighted Everett function based on the harmonics present in PWM waveform. Moreover, it formulates the possibility of utilizing the classical Preisach model to predict iron losses under PWM excitation. Research limitations/implications The approach is still limited in terms of its application at high frequencies. This work may eventually lead toward the accurate prediction of iron loss under PWM excitation in electromagnetic machine design. Practical implications The paper provides a simple approach applying the Preisach model for the prediction of iron losses under PWM excitation. The proposed approach does not require additional experimental data beyond B-H loops measured under sinusoidal excitation. Originality/value A novel approach is presented to incorporate the frequency dependence into a static inverse Preisach model. The approach extends the ability of the static Preisach model to compute total iron loss under PWM excitation using a weighted Everett function.
10
Sun, Xiaodong, Zhuicai Zhou, Long Chen, Zebin Yang, and Shouyi Han. "Performance analysis of segmented rotor switched reluctance motors with three types of winding connections for belt-driven starter generators of hybrid electric vehicles." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, no. 3 (2018): 1258–70. http://dx.doi.org/10.1108/compel-08-2017-0342.
Full textAbstract:
Purpose Inductance, torque and iron loss are the key parameters of switched reluctance motors for belt-driven starter generators. This paper aims to present the analysis of a segmented rotor switched reluctance motor (SSRM) with three types of winding connections for hybrid electric vehicle applications by using a two-dimensional finite element method. Design/methodology/approach The rotor of the studied SSRM consists of a series of discrete segments, while the stator is made up of exciting and auxiliary teeth. First, the concept and structures of the different winding connections are introduced. Then, the magnetic flux path of the three types of winding connections for the SSRM is described. Second, the magnetic flux distributions in the three parts, i.e. the stator yoke, the stator tooth and the rotor segment, are described in detail to calculate the iron losses. Third, three SSRMs with the different winding arrangements are analyzed and compared to evaluate the distinct features of the studied SSRM. The analysis and comparison mainly include self-inductances, mutual inductances, phase currents, output torque and iron loss. Findings It is found that the self-inductances of the three types of winding connections are almost equal, and only the SSRM1 has a positive mutual inductance. In addition, the current waveforms of SSRM1 and SSRM2 are regular. However, it is irregular in SSRM3. It is shown that SSRM1 has better characteristics, such as higher output torque, high power density, lower torque ripple and iron loss. Originality/value This paper proposes and analyzes three novel winding connections for the SSRM to provide guidance for enhancing the output torque and reducing the iron loss to achieve high efficiency.
11
Rosato, Barbara Eleni, Roberta Marra, Vanessa D’Onofrio, et al. "SEC23B Loss-of-Function Suppresses Hepcidin Expression by Impairing Glycosylation Pathway in Human Hepatic Cells." International Journal of Molecular Sciences 23, no. 3 (2022): 1304. http://dx.doi.org/10.3390/ijms23031304.
Full textAbstract:
Biallelic pathogenic variants in the SEC23B gene cause congenital dyserythropoietic anemia type II (CDA II), a rare hereditary disorder hallmarked by ineffective erythropoiesis, hemolysis, erythroblast morphological abnormalities, and hypo-glycosylation of some red blood cell membrane proteins. Abnormalities in SEC23B, which encodes the homonymous cytoplasmic COPII (coat protein complex II) component, disturb the endoplasmic reticulum to Golgi trafficking and affect different glycosylation pathways. The most harmful complication of CDA II is the severe iron overload. Within our case series (28 CDA II patients), approximately 36% of them exhibit severe iron overload despite mild degree of anemia and slightly increased levels of ERFE (the only erythroid regulator of hepcidin suppression). Thus, we hypothesized a direct role of SEC23B loss-of-function in the pathomechanism of hepatic iron overload. We established a hepatic cell line, HuH7, stably silenced for SEC23B. In silenced cells, we observed significant alterations of the iron status, due to both the alteration in BMP/SMADs pathway effectors and a reduced capability to sense BMP6 stimulus. We demonstrated that the loss-of-function of SEC23B is responsible of the impairment in glycosylation of the membrane proteins involved in the activation of the BMP/SMADs pathway with subsequent hepcidin suppression. Most of these data were confirmed in another hepatic cell line, HepG2, stably silenced for SEC23B. Our findings suggested that the pathogenic mechanism of iron overload in CDA II is associated to both ineffective erythropoiesis and to a specific involvement of SEC23B pathogenic variants at hepatic level. Finally, we demonstrated the ability of SEC23B paralog, i.e., SEC23A, to rescue the hepcidin suppression, highlighting the functional overlap between the two SEC23 paralogs in human hepatic cells.
12
Mamedov, E. Sh, T. N. Kulibekova, D. S. Veliyeva, Z. S. Safaraliyeva, and I. R. Rushinaz. "SYNTHESIS OF S,P,N-CONTAINING ORGANIC COMPOUNDS AND THEIR THERMOSTABILITY WITH RESPECT TO METALS." Azerbaijan Chemical Journal, no. 4 (November 14, 2023): 97–103. http://dx.doi.org/10.32737/0005-2531-2023-4-97-103.
Full textAbstract:
The results of thermal studies of some derivatives of dithiophosphoric, xanthogenic, dithiocarbamic acids are presented. The thermal parameters of the compounds were determined both in pure form and in the presence of iron and copper powders. Their chemical activity with respect to iron and copper was studied. It has been found that the temperature at which the thermal stability of the studied compounds is maintained exceeds 1700С, and they are chemically active with respect to iron and copper: the lower the interaction temperature within the same row with iron and copper and the lower its mass loss corresponding to this temperature, the more effective it is like an extreme pressure (EP) additive. It has been found that compounds of the same series, reacting with metal by the type of synchronous and exchange reactions, have better indicators of extreme pressure properties than compounds interacting with metal by the type of asynchronous reaction
13
Czader, Magdalena, Mingsheng Wang, Larry D. Cripe, Liang Cheng, and Attilio Orazi. "Loss of Heterozygosity in Bone Marrows of Patients with Iron-Deficiency Anemia." Blood 108, no. 11 (2006): 4863. http://dx.doi.org/10.1182/blood.v108.11.4863.4863.
Full textAbstract:
Abstract The management of patients with low-risk myelodysplastic syndromes (LR-MDS) transitioned from supportive care to active therapeutic interventions focused on the improvement of hematopoiesis. Thus, it is now critical to early identify patients with this disorder for optimal management. The diagnosis of myelodysplastic syndrome is based on clinical data, morphologic features of the bone marrow and conventional cytogenetic analysis. However, the majority of patients with LR-MDS do not demonstrate abnormal marrow karyotypes. In addition, changes in bone marrow morphology similar to those seen in LR-MDS, i.e. mild dysplasia with no increase in blasts, occur in a variety of systemic illnesses. Thus, there is a need for more objective diagnostic methods. The detection of loss of heterozygosity (LOH) can be supportive of the diagnosis of MDS as it is widely accepted that genetic lesion(s), including loss of tumor suppressor genes, lead to clonal expansion of hematopoietic populations in myelodysplasia. Indeed, previous studies and our pilot series showed high incidence of allelic imbalance in MDS. However, there is no data on the baseline LOH in bone marrows of age-matched controls without primary bone marrow disorder. To further explore the utility of LOH analysis in refining the diagnosis of LR-MDS, we investigated the incidence of allelic imbalance in bone marrows of patients with iron-deficiency anemia. The LOH analysis was performed using DNA extracted from formalin-fixed, paraffin-embedded bone marrow clot sections. Unrelated non-neoplastic tissues from the same patients served as controls. The oligonucleotide primers were selected based on previously reported high frequency of involvement in MDS and AML (D1S450, D11S1363, IRF1, D11S1338 and WT1). Nineteen patients were included in the study [median age 71 years, range 38–81 years; 8 males; median hemoglobin and MCV of 9.4 g/dL and 86 fL (normal range 80–94 fL)]. All patients showed depleted iron stores on bone marrow aspirate smears. Review of bone marrow morphology and subsequent follow-up showed no evidence of primary bone marrow disorder. Karyotypes, available in 7 patients, were normal, with the exception of one case showing loss of chromosome Y. Ninety two percent of the samples were informative. The overall frequency of LOH for all loci was 16% (12–21%, Tab. 1). LOH was seen in 10 cases (1 locus involved in 6 cases, 2 loci affected in 4 patients). LOH was not seen at any loci in the control samples from 19 non-bone marrow tissues from the same patients. In conclusion, we demonstrated a significant rate of LOH in non-neoplastic bone marrow tissue. For selected loci, the frequency of LOH approximates the rate seen in MDS samples. However, in the contrary to MDS group, no more than two markers were involved in any one patient with iron-deficiency anemia. The use of LOH analysis in the diagnosis of MDS may require selection of the primers based upon the background frequency of LOH in normal populations. The detection of LOH at numerous loci (more than two), may still serve as a valuable ancillary diagnostic tool. A prospective study of larger series will be necessary to confirm these findings and to address their clinical and biological significance. Tab. 1 Overall frequency of LOH (%) at the studied loci in bone marrows with iron-deficiency. Samples IRF1 D11S1363 D1S450 D11S1338 WT1 *Data from 16 MDS cases (Modern Pathology2004;17 suppl 1:255A) Iron-deficiency anemia 12 18 21 16 12 MDS* 31 26 20 19 40
14
Porter, JB, KP Hoyes, RD Abeysinghe, PN Brooks, ER Huehns, and RC Hider. "Comparison of the subacute toxicity and efficacy of 3-hydroxypyridin-4- one iron chelators in overloaded and nonoverloaded mice." Blood 78, no. 10 (1991): 2727–34. http://dx.doi.org/10.1182/blood.v78.10.2727.2727.
Full textAbstract:
Abstract Five orally effective iron chelators of the 3-hydroxypyridin-4-one series have been administered intraperitoneally to iron-overloaded and nonoverloaded male mice at a dose of 200 mg/kg/24 h for a total of 60 days to investigate the effect on iron loading and toxicity. There was a significant reduction in hepatic iron at the end of the study in the iron-overloaded mice with all compounds studied using chemical iron quantitation (P less than .001) and with Perls' stain (P less than .01). Liver iron removal with the hydroxypyridinones ranged from 37% with CP20 to 63% with CP51, compared with 46% removal for desferrioxamine (DFO). There was no significant reduction in splenic or cardiac iron with any chelator. There were no deaths in iron-overloaded animals receiving any of the hydroxypyridin-4-ones, but significantly more deaths in the nonoverloaded groups as a whole (P less than .03). No weight loss was observed with any chelator. Significant reductions in hemoglobin and white cell count were observed with CP20(L1). No histologic abnormalities of kidney, spleen, bone marrow, or stifle joints were observed. Intracytoplasmic inclusion bodies were observed in the centrilobular hepatocytes of animals administered each of the hydroxypyridin-4-ones, while the DFO-treated and control groups showed no such changes.
15
Porter, JB, KP Hoyes, RD Abeysinghe, PN Brooks, ER Huehns, and RC Hider. "Comparison of the subacute toxicity and efficacy of 3-hydroxypyridin-4- one iron chelators in overloaded and nonoverloaded mice." Blood 78, no. 10 (1991): 2727–34. http://dx.doi.org/10.1182/blood.v78.10.2727.bloodjournal78102727.
Full textAbstract:
Five orally effective iron chelators of the 3-hydroxypyridin-4-one series have been administered intraperitoneally to iron-overloaded and nonoverloaded male mice at a dose of 200 mg/kg/24 h for a total of 60 days to investigate the effect on iron loading and toxicity. There was a significant reduction in hepatic iron at the end of the study in the iron-overloaded mice with all compounds studied using chemical iron quantitation (P less than .001) and with Perls' stain (P less than .01). Liver iron removal with the hydroxypyridinones ranged from 37% with CP20 to 63% with CP51, compared with 46% removal for desferrioxamine (DFO). There was no significant reduction in splenic or cardiac iron with any chelator. There were no deaths in iron-overloaded animals receiving any of the hydroxypyridin-4-ones, but significantly more deaths in the nonoverloaded groups as a whole (P less than .03). No weight loss was observed with any chelator. Significant reductions in hemoglobin and white cell count were observed with CP20(L1). No histologic abnormalities of kidney, spleen, bone marrow, or stifle joints were observed. Intracytoplasmic inclusion bodies were observed in the centrilobular hepatocytes of animals administered each of the hydroxypyridin-4-ones, while the DFO-treated and control groups showed no such changes.
16
Urasaki, N., T. Senjyu, and K. Uezato. "Relationship of Parallel Model and Series Model for Permanent Magnet Synchronous Motors Taking Iron Loss Into Account." IEEE Transactions on Energy Conversion 19, no. 2 (2004): 265–70. http://dx.doi.org/10.1109/tec.2004.827291.
Full text
17
Zhang, Jingwei, Honghua Wang, Sa Zhu, and Tianhang Lu. "Multi-Physics Multi-Objective Optimal Design of Bearingless Switched Reluctance Motor Based on Finite-Element Method." Energies 12, no. 12 (2019): 2374. http://dx.doi.org/10.3390/en12122374.
Full textAbstract:
The bearingless switched reluctance motor (BSRM) integrates the switched reluctance motor (SRM) with the magnetic bearings, which avoids mechanical bearings-loss and makes it promising in high-speed applications. In this paper, a comprehensive framework for the multi-physics multi-objective optimal design of BSRMs based on finite-element method (FEM) is proposed. At first, the 2-D electromagnetic model of a fabricated initial design prototype is built and solved by the open-source FEM software, Elmer. The iron loss model in Elmer based on the Fourier series is modified by a transient iron loss model with less computation time. Besides, a simplified lumped-parameter (LP) thermal model of the BSRM is applied to estimate the temperature rise of BSRM in the steady state. Then, the comprehensive framework for the multi-physics multi-objective optimal design of BSRMs based on FEM is proposed. The objectives, constraints, and decision variables for optimization are determined. The multi-objective genetic particle swarm optimizer is utilized to obtain the Pareto front of optimization. The electromagnetic performance of the final optimal design is compared with the initial design. Comparison results show that the average electromagnetic torque and the efficiency are significantly enhanced.
18
Hussain, Ghulam, Shanta Batool, Yuruo Zheng, Shuyi Li, and Xiawa Wang. "Structural, Optical, Charge-Transport, and Dielectric Properties of Double-Perovskite La2Co1−zFezMnO6 (z = 0, 0.2–1.0)." Materials 15, no. 18 (2022): 6249. http://dx.doi.org/10.3390/ma15186249.
Full textAbstract:
A series of double-perovskite La2Co1−zFezMnO6 (z = 0, 0.2–1.0) ceramics were synthesized using a well-established sol–gel method. The series of samples with a monoclinic phase and a P21/n symmetry were characterized by XRD, FTIR, conductivity, and capacitance measurement to extract charge-transport and dielectric characteristics at room temperature. The obtained IR spectra fitted well with the Lorentz oscillator model to calculate the damping factor, optical frequency, and oscillator strength and compared with the theory, which gave better agreement. The calculated activation energies from the Arrhenius plot supported the semiconducting nature of all samples. The temperature and frequency-dependent dielectric parameters, such as the real part (εr′), imaginary part (ε″) of the dielectric constant, dielectric loss (tanδ), and ac-conductivity (σac) were extracted. The dielectric constant (εr′, ε″) and dielectric loss (tanδ) were enhanced at a low frequency, while the ac-conductivity (σac) displayed higher values at higher frequencies. The enhancement in the dielectric parameters with increasing iron concentrations arose due to the higher surface volume fraction of iron (Fe3+) ions than the cobalt (Co3+) ions. The radius of the Fe3+ (0.645 Å) was relatively higher than the Co3+ ions (0.61 Å), significantly influenced by the grains and grain boundaries, and enhanced the barrier for charge mobility at the grain boundaries that play a vital role in space charge polarization.
19
Held, Melissa R., Richard D. Bungiro, Lisa M. Harrison, Iqbal Hamza, and Michael Cappello. "Dietary Iron Content Mediates Hookworm Pathogenesis In Vivo." Infection and Immunity 74, no. 1 (2006): 289–95. http://dx.doi.org/10.1128/iai.74.1.289-295.2006.
Full textAbstract:
ABSTRACT Hookworm infection is associated with growth delay and iron deficiency anemia in developing countries. A series of experiments were designed in order to test the hypothesis that host dietary iron restriction mediates susceptibility to hookworm infection using the hamster model of Ancylostoma ceylanicum. Animals were maintained on diets containing either 10 ppm iron (iron restricted) or 200 ppm iron (standard/high iron), followed by infection with A. ceylanicum third-stage larvae. Infected animals fed the standard diet exhibited statistically significant growth delay and reduced blood hemoglobin levels compared to uninfected controls on day 20 postinfection. In contrast, no statistically significant differences in weight or hemoglobin concentration were observed between infected and uninfected animals fed the iron-restricted diet. Moreover, iron-restricted animals were observed to have reduced intestinal worm burdens on day 10 and day 20 postinfection compared to those of animals maintained on the standard/high-iron diet. In a subsequent study, animals equilibrated on diets containing a range of iron levels (10 ppm, 40 ppm, 100 ppm, or 200 ppm) were infected with A. ceylanicum and followed for evidence of hookworm disease. Infected animals from the intermediate-dietary iron (40- and 100-ppm) groups exhibited greater weight loss and anemia than those in the low (10-ppm)- or high (200-ppm)-iron diet groups. Mortality was also significantly higher in the intermediate-dietary-iron groups. These data suggest that severe dietary iron restriction impairs hookworm development in vivo but that moderate iron restriction enhances host susceptibility to severe disease.
20
Sharon, Ilan. "‘Transition Dating’ – a Heuristic Mathematical Approach to the Collation of Radiocarbon Dates from Stratified Sequences." Radiocarbon 43, no. 2A (2001): 345–54. http://dx.doi.org/10.1017/s0033822200038200.
Full textAbstract:
A heuristic approach, nicknamed “transition dating,” was used to date sequences of early Iron Age contexts using a series of 14C determinations. The basic principles of transition dating are simple and intuitive: 1) attempt to date transitions between periods, phases, etc. rather than the phases themselves, and 2) the most plausible date for that transition is one that is later than the dates from contexts preceding it, and is still earlier than the dates succeeding it. Hypotheses regarding the actual date of each transition may be evaluated using an appropriate loss function. These loss functions can also be adjusted or weighted by the user to account differentially for the various factors causing the distortion or “fuzz” in the dates.
21
Raju, Mudhunuru Varma, Harsha Vardhan, Reddy Raghunatha Reddy Byra, Bharath Kumar Shanmugam, and Harish Hanumanthappa. "Enhanced Recovery of Iron Values from Low-Grade Ores and Tailings through Reverse Cationic Flotation." Disaster Advances 18, no. 5 (2025): 170–76. https://doi.org/10.25303/185da1700176.
Full textAbstract:
India is well-known for its rich deposits of high-quality hematite ores, making it a vital player in the global market. As the availability of high-grade iron ores diminishes, the need to process low-grade ores, fines and slimes through beneficiation is becoming increasingly important to meet market requirements. The creation of fines and slimes leads to a mineral loss of about 20 to 25% of the overall mineral value during processing. This research investigates the beneficiation of iron ore tailings using reverse cationic flotation, with Sokem reagent acting as a collector and starch serving as a depressant. A series of comparative assessments involving magnetic separation and gravity separation were performed. An initial mineralogical examination showed that hematite and goethite were the main iron-bearing minerals, accompanied by quartz and kaolinite as significant gangue materials. The selective flocculation technique proved effective, enhancing the iron grade from 41.05% to 57.03% Fe, with a recovery rate of 47.35%. After desliming, the outcomes improved further, yielding 58.25% Fe and a recovery of 29.00%. These results underline the potential for successful beneficiation of iron ore tailings, offering valuable insights for enhancing the recovery of high-grade iron from low-grade ores and reducing mineral losses during processing.
22
Gould, Richard A. "The Wreck of the Barque North Carolina, Bermuda, 1880: An Underwater Crime Scene?" American Antiquity 70, no. 1 (2005): 107–28. http://dx.doi.org/10.2307/40035271.
Full textAbstract:
Archaeological and historical research in 1999–2001 on the loss of the 3-masted, iron barque “North Carolina” produced a series of anomalies and coincidences suggesting that the ship was sunk intentionally. The wreck lies along the southwest edge of Bermuda’s reef system. At first it appeared to be that of a fairly typical sail-propelled, iron-hulled cargo ship of a general type built in the United Kingdom during the late nineteenth century. The original research design for the “North Carolina” project sought to test how representative this shipwreck was as an example of that shipbuilding tradition. Archaeological surveys as well as published and archival accounts of the ship's loss, however, revealed discrepancies that were explored further. The project evolved into the investigation of a possible 120-year-old crime scene. The “North Carolina” offers a case study of how scientifically grounded archaeology applied with due regard for critical issues of cultural context can reveal systemic as well as proximate factors that affect past human behavior—including possible criminal behavior.
23
Hsuan, J. J. "The ability of salts to inhibit the reaction between periodate anions and ovotransferrin." Biochemical Journal 238, no. 3 (1986): 931–34. http://dx.doi.org/10.1042/bj2380931.
Full textAbstract:
The reaction between periodate anions and apo-ovotransferrin results in the rapid abolition of the iron-binding ability of the protein and the loss of approximately 4 mol of tyrosine/mol of protein. The degree of inhibition exerted by a variety of salts on the rate of this reaction is found to be inconsistent with the lyotropic series and suggests the existence of a complex anion-binding site in the apoprotein. The existence of this site may explain the action of periodate anions on ovotransferrin.
24
Benfeito, Sofia, Carlos Fernandes, Santiago Vilar, Fernando Remião, Eugenio Uriarte, and Fernanda Borges. "Exploring the Multi-Target Performance of Mitochondriotropic Antioxidants against the Pivotal Alzheimer’s Disease Pathophysiological Hallmarks." Molecules 25, no. 2 (2020): 276. http://dx.doi.org/10.3390/molecules25020276.
Full textAbstract:
Alzheimer disease (AD) is the most common neurodegenerative disease featuring progressive and degenerative neurological impairments resulting in memory loss and cognitive decline. The specific mechanisms underlying AD are still poorly understood, but it is suggested that a deficiency in the brain neurotransmitter acetylcholine, the deposition of insoluble aggregates of fibrillar β-amyloid 1–42 (Aβ42), and iron and glutamate accumulation play an important role in the disease progress. Despite the existence of approved cholinergic drugs, none of them demonstrated effectiveness in modifying disease progression. Accordingly, the development of new chemical entities acting on more than one target is attracting progressively more attention as they can tackle intricate network targets and modulate their effects. Within this endeavor, a series of mitochondriotropic antioxidants inspired on hydroxycinnamic (HCA’s) scaffold were synthesized, screened toward cholinesterases and evaluated as neuroprotectors in a differentiated human SH-SY5Y cell line. From the series, compounds 7 and 11 with a 10-carbon chain can be viewed as multi-target leads for the treatment of AD, as they act as dual and bifunctional cholinesterase inhibitors and prevent the neuronal damage caused by diverse aggressors related to protein misfolding and aggregation, iron accumulation and excitotoxicity.
25
Puente-Córdova, Jesús, M. Reyes-Melo, Luis Palacios-Pineda, Imperio Martínez-Perales, Oscar Martínez-Romero, and Alex Elías-Zúñiga. "Fabrication and Characterization of Isotropic and Anisotropic Magnetorheological Elastomers, Based on Silicone Rubber and Carbonyl Iron Microparticles." Polymers 10, no. 12 (2018): 1343. http://dx.doi.org/10.3390/polym10121343.
Full textAbstract:
This article focuses on studying the rheological behavior of isotropic and anisotropic magnetorheological elastomers (MREs), made of carbonyl iron microparticles dispersed into a silicone–rubber matrix by considering 20 and 30 wt % of microparticles. Sample sets were prepared for each composition, with and without the application of an external magnetic field. Experimental measurements of the material rheology behavior were carried out by a shear oscillatory rheometer at constant temperature, to determine both the shear storage modulus (G′) and shear loss modulus (G′′) for all characterized samples. Then, experimental data collected from the isotropic and the anisotropic material samples were used to plot the Cole-Cole diagrams to quantify the interfacial adhesion between carbonyl iron microparticles and the silicone-rubber matrix. Furthermore, the Fractional Zener Model (FZM) with two spring-pots in series is used for quantitative analysis of collected experimental data.
26
Preza, Gloria, Augustine Fernandes, Richard J. Clark, David J. Craik, Tomas Ganz, and Elizabeta Nemeth. "Structural Aspects of Hepcidin-Ferroportin Binding." Blood 112, no. 11 (2008): 119. http://dx.doi.org/10.1182/blood.v112.11.119.119.
Full textAbstract:
Abstract Hepcidin, a 25-amino acid peptide hormone, is the principal regulator of plasma iron concentrations in a wide range of organisms, from humans to fish. The hepcidin receptor is the iron channel ferroportin (Fpn), which exports iron from duodenal enterocytes, macrophages and hepatocytes into plasma. Hepcidin binding to Fpn results in internalization and degradation of the ligand-receptor complex and reduced iron efflux from cells into plasma. Abnormal production of hepcidin or abnormal interaction with Fpn causes a spectrum of iron disorders. We analyzed the nature of the interaction and critical structural features of hepcidin and Fpn. The binding of hepcidin to Fpn showed an unusual temperature dependence, with loss of binding/internalization at temperatures lower that 15C. To establish whether initiation of internalization stabilized binding, we used Fpn mutated at Tyr302 and Tyr303, which does not internalize and showed that the mutant was still able to bind 125I-hepcidin, with a similar EC50 and temperature dependence as wt Fpn. We next addressed Fpn structural features required for interaction with hepcidin. Several Fpn mutations in humans cause a phenotype consistent with resistance to hepcidin. We thus generated Fpn plasmids carrying the specific human mutations, transiently transfected cells with the mutants, and measured 125I-hepcidin binding to cells. The results showed that thiol form of Cys326 is essential for hepcidin binding since substitution of this Cys with Ser or Thr preserved the iron exporting function of Fpn but resulted in a complete loss of hepcidin binding, as did the treatment of cells with non-permeable sulfhydryl alkylating agents. The essential role of the C326 residue in hepcidin binding accounts for the early and severe iron overload in patients with C326S or Y substitution. We also showed that the N-terminus of hepcidin is essential for its binding to Fpn. The sequential truncation of five N-terminal residues resulted in a gradual reduction in activity. Ala scanning of the N-terminus showed that Phe4 and Ile6 substitutions resulted in &gt;80% and 50% decrease in binding respectively. To understand the requirements for biological activity at position 4, we tested a series of Phe4 analogues. Substitution with a similar hydrophobic residue, cyclohexylalanine, had no effect on activity; substitution with polar Tyr caused a 50% reduction in activity; substitution with charged residues Lys or Asp resulted in a complete loss of activity, as did substitution with D-Phe. The results indicated that position 4 requires a bulky hydrophobic residue and that the interaction with Fpn is stereospecific. Similarly, substitution of Ile at position 6 with charged residues caused a complete loss of activity. Understanding the molecular framework responsible for hepcidin-Fpn interaction will facilitate the development of drug leads for a range of iron disorders.
27
Rouabah, Z., B. Abdelhadi, F. Anayi, and F. Zidani. "On-line losses minimization of induction motor vector control." Archives of Electrical Engineering 60, no. 3 (2011): 257–68. http://dx.doi.org/10.2478/v10171-011-0024-5.
Full textAbstract:
On-line losses minimization of induction motor vector controlConventional field-orientated Induction motor drives operate at rated flux even at low load. To improve the efficiency of the existing motor it is important to regulate the flux of the motor in the desired operating range. In this paper a loss model controller (LMC) based on the real coded genetic algorithm is proposed, it has the straightforward goal of maximizing the efficiency for each given load torque. In order to give more accuracy to the motor model and the LMC a series model of the motor which consider the iron losses as a resistance connected in series with the mutual inductance is considered. Digital computer simulation demonstrates the effectiveness of the proposed algorithm and also simulation results have confirmed that this algorithm yields the optimal efficiency.
28
Yang, Peng, Qian Hao, Junsheng Zhang, Fang Liang, Xiaoning Bo, and Peifen Wang. "Generation of Abundant Defects in Ferrite Carbon Magnetic Nanomaterials for Eliminating Electromagnetic Interference in Communication." Materials 15, no. 19 (2022): 6650. http://dx.doi.org/10.3390/ma15196650.
Full textAbstract:
A series of novel ferrite carbon nanomaterials are considered to obtain the potential advantages in elimination of the electromagnetic interference effects. Herein, the iron nanoparticles coated on amorphous carbon were prepared by facile agar-gel synthesis. Meanwhile, the synergy between carbon supporting and ferrite nanomaterials could be proved to promote the absorption properties. Among all samples, the iron nanoparticles coated on amorphous carbon show the highest microwave absorption properties, achieving the maximum reflection loss (RL) of −14.3 dB at 6 GHz (5.5-milimeter thickness), and the bandwidths over −10 dB (90% absorption) was 2.5 GHz. Combining analysis results, it is confirmed that the as-prepared iron nanoparticles have the highest surface area, homogeneous distribution, abundant defect, and well-defined pore structure, which could significantly affect the absorption properties at 6 GHz. Furthermore, the abundant defects derived from the interface were the essential reason for the improved absorption properties. Overall, it provided a new strategy to design an effective method to absorb nanomaterials for the elimination of electromagnetic interference, especially the coordination of metal species and carbon supporting.
29
Khudaverdyan, A. Yu. "The Anthropology of Infectious Diseases of Bronze Age and Early Iron Age from Armenia." Dental Anthropology Journal 24, no. 2-3 (2018): 42–54. http://dx.doi.org/10.26575/daj.v24i2-3.61.
Full textAbstract:
This study reviews the evidence for thepresence of specific infectious diseases in Armenianskeletal series of Bronze Age and Early Iron Age.Throughout human history, pathogens have beenresponsible for the majority of human deaths. Factorssuch as age, sex, and nutritional status can influencewhether an individual contracts and develops aparticular infection, while environmental conditions,such as climate, sanitation, pollution, and contact withothers will affect the susceptibility of a population. Thefrequencies of such signs as osteomyelitis, peridontaldisease, leprosy, abscesses, and so forth, testify that thepeople experienced a variety of forces and durations—both internal and external—of stressful influences.Individuals from Sevan region may have had morechronic infections due to continued exposure to pathogensduring their lives as well as traumatic injuries. Sevenindividuals had nasopharyngeal lesions consistent with adiagnosis of leprosy. Dental caries was less severe in theSevan region, although dental abscesses (51 individuals)and antemortem tooth loss (87 individuals) were moreprevalent. In contrast, periodontal disease (8/18 adults)and antemortem loss (8/18 adults) of the molars weremore prevalent at the Shiraksky plain. Data focusing onclimate influence, migratory, and cultural habits in thepast are discussed.
30
Fu, Xiaotong, Shuai Yan, Zhifu Chen, Xiaoyu Xu, and Zhuoxiang Ren. "A Practical Hybrid Hysteresis Model for Calculating Iron Core Losses in Soft Magnetic Materials." Energies 17, no. 10 (2024): 2326. http://dx.doi.org/10.3390/en17102326.
Full textAbstract:
Accurately calculating the losses of ferromagnetic materials is crucial for optimizing the design and ensuring the safe operation of electrical equipment such as motors and power transformers. Commonly used loss calculation models include the Bertotti empirical formula and hysteresis models. In this paper, a new hybrid hysteresis model method is proposed to calculate losses—namely, the combination of the Jiles–Atherton hysteresis model (J–A) and the Fourier hysteresis model. The traditional Jiles–Atherton hysteresis model is mainly suitable for fitting the saturation hysteresis loop, but the fitting error is relatively large for internal minor hysteresis loops. In contrast, the Fourier hysteresis model is suitable for fitting the minor hysteresis loops because the corresponding magnetic induction strength or magnetic field is lower and the waveform distortion is small. Moreover, Fourier series expansion can be expressed with fewer terms, which is convenient for parameter fitting. Through examples, the results show that the hybrid hysteresis model can take advantage of the strengths of each model, not only reducing computational complexity, but also ensuring high fitting accuracy and loss calculation accuracy.
31
Zhao, Xiong, Junying Zhang, Lu Ma, Wubin Wang, and Mingxing Zhang. "Study on the Performance and Mechanism of Morpholine Salt Volatile Corrosion Inhibitors on Carbon Steel." Coatings 14, no. 8 (2024): 997. http://dx.doi.org/10.3390/coatings14080997.
Full textAbstract:
A series of morpholine salt volatile corrosion inhibitors (VCIs) were synthesized via solid-phase chemical reactions. The corrosion inhibition performance was assessed using evaporation weight loss, VCI capability, and corrosion weight loss tests. The corrosion inhibition mechanisms of the morpholine salt VCIs for carbon steel in atmospheric conditions were explored through electrochemical testing under thin film electrolytes, X-ray photoelectron spectroscopy (XPS), and computational simulations. Morpholine carbonate exhibited higher volatility. Corrosion weight loss tests showed an >85% reduction for steel treated with morpholine benzoate or morpholine carbonate. The inhibitors’ inhibition mechanism, elucidated through X-ray photoelectron spectroscopy (XPS) and computational simulations, revealed that morpholine carbonate and benzoate form protective layers via physical and chemical adsorption on the steel surface, coordinating with iron atoms through nitrogen and oxygen atoms. Quantum chemical calculations demonstrated that morpholine carbonate had stronger adsorption energy and electron transfer capabilities, indicating superior corrosion inhibition performance over morpholine benzoate.
32
Chambaz, A., M. Kreuzer, M. R. L. Scheeder, and P. A. Dufey. "Characteristics of steers of six beef breeds fattened from eight months of age and slaughtered at a target level of intramuscular fat – II. Meat quality." Archives Animal Breeding 44, no. 5 (2001): 473–88. http://dx.doi.org/10.5194/aab-44-473-2001.
Full textAbstract:
Abstract. Meat quality of Angus (AN), Simmental (SI), Charolais (CH), Limousin (LI), Blonde d'Aquitaine (BL), and Piedmontese (PI) steers (n = 22 per breed group) was measured in the M. longissimus dorsi (M.l.d.) and the M. biceps femoris, regio glutea (M.b.f.). Animals were fattened in two subsequent series on a forage-based diet until a target level of 3.5 % intramuscular fat (IMF) was reached aecording to real-time ultrasound assessments in the live animals or until 15 months of fattening had passed. Series 1 was performed in a tie-stall barn while a loosehousing system with straw bedding was applied in series 2. The actually measured IMF contents in M.l.d. were 3.35, 3.47, 3.49, 3.48, 2.34 and 2.40 % for AN, SI, CH, LI, BL and PI, respectively. Breed group differences in IMF content were mostly accompanied by a contrary Variation either in muscle water or protein content. Muscle cholesterol levels were similar for all breeds amounting to 47 and 51 mg/100 g on average in M.l.d. and M.b.f, respectively. Early and late postmortem muscle pH was relatively similar among breeds, but water-holding capacity, measured as losses due to drip, ageing, thawing and cooking, was unfavourably high in AN (drip loss excepted) in both muscles. Cooking loss tended to be lowest in PI, drip loss in SI. The AN showed the palest meat. In line with lightness, heme iron contents were clearly lowest in both muscles in the AN steers. There was no relationship found between IMF and shear force among breed groups. No significant differences between breed groups occurred in M.l.d. collagen solubility and shear force. Apart from breed differences, there were several differences noted between fattening series, namely clearly better water-holding capacity and lower shear force of the meat from series 2 (group housing) than from series 1 (tied System). The results indicate that in steers of similar IMF content and raised under the same feeding and management conditions, differences in most M.l.d. and M.b.f. quality traits were apparent, with the exception of shear force and M.l.d. collagen solubility.
33
Jackson, Amanda Claire, Makayla Schissel, James Harper, and Aleh Bobr. "RBC Exchange Transfusion As an Adjunct Therapy to Control Iron Overload in Patients with Transfusion-Dependent Thalassemia." Blood 142, Supplement 1 (2023): 5249. http://dx.doi.org/10.1182/blood-2023-186597.
Full textAbstract:
Background Patients with transfusion-dependent thalassemia (TDT) require red blood cell (RBC) transfusions as frequently as every 2-4 weeks to maintain a pre-transfusion hemoglobin of 9.0-10.5 g/dL for patients without cardiac complications. Chronic RBC transfusions increase body iron stores leading to iron deposition in liver, pancreatic, and cardiac tissues. Deferoxamine, deferiprone, and deferasirox are the iron chelators currently licensed for clinical use to manage iron overload in TDT patients with side effects ranging from nausea to nephrotoxicity and hearing loss. RBC exchange transfusion (RBCX), particularly in conjunction with isovolumic hemodilution, has been utilized for patients with sickle cell disease as a means of stabilizing iron overload. The 2015 ASFA Red Blood Cell Exchange consensus supports RBCX to reduce or prevent iron overload in sickle cell disease. Review of literature shows that RBCX can be beneficial as an acute intervention for patients with TDT and pulmonary hypertension however there is a paucity of literature documenting chronic RBCX use in TDT patients with iron overload. Case series This series presents five patients with TDT who were transitioned from chronic simple RBC transfusions to chronic RBCX after developing treatment-refractory iron overload as evidenced by serum ferritin elevation. Patients were treated on a transfusion schedule with a pre-transfusion goal hemoglobin of 9.5g/dL or higher and interval 4-6 weeks. Patient A is a 14 year-old male who developed significant iron overload (peak ferritin of 7077) on deferasirox 20 mg/kg/day and MRI T2 imaging suggestive of iron deposition. After transition to RBCX, ferritin decreased significantly with a post-RBCX mean of 1382. Blood utilization was 4200 ml three months pre-RBCX and 5625 ml three months post-RBCX. Patient B is a 23 year-old male with a peak ferritin of 1310 prior to RBCX on 23 mg/kg/day of deferasirox complicated by mild hearing loss. Serum ferritin has shown stabilization, with a mean post-RBCX ferritin of 880. Blood utilization was 2400 ml three months pre-RBCX and 8100 ml three months post-RBCX. Patient C is a 17 year-old male with a peak ferritin of 1400 with deferasirox management complicated by acute renal injury. Mean serum ferritin of 633 post-RBCX. Blood utilization was 1200 ml three months pre-RBCX and 5200 ml three months post-RBCX. Patient D is a 17 year-old male managed on 23 mg/kg/day of deferasirox with a peak ferritin of 3060 on pre-RBCX. The patient transitioned to chronic RBCX with mean serum ferritin of 1073. Blood utilization was 1800 ml three months pre-RBCX and 7700 ml three months post-RBCX. Patient E is a 17 year-old male with peak ferritin of 3404 despite 20 mg/kg/day of deferasirox prior to chronic RBCX. Mean serum ferritin after transition to RBCX was found to be 1282. Blood utilization was 1500 ml three months pre-RBCX and 4900 ml three months post-RBCX. All 5 patients have tolerated RBC exchange procedures without complications. Serum ferritin levels pre- and post-RBC exchange were trended pre- and post- RBCX (Figure 1). Serum ferritins were averaged together for each patient to obtain an equal number of time points considered prior to and after starting RBCX therapy. Descriptive statistics (Table 1) were used to summarize average ferritin levels for the patient group. A Wilcoxon signed-rank test was performed to assess the median difference in ferritin level from pre-RBCX to post-RBCX. All analyses were conducted in SAS version 9.4. P &lt;0.05 is considered statistically significant. Median pre-RBCX ferritin level for the study group is 2489.3 (Inter-quartile range (IQR): 1190.0, 2659.0). The median post-RBCX ferritin level for the series is 1329.3 (IQR: 941.0, 1711.0). After subtracting the post-RBCX ferritin level from the pre-RBCX ferritin level, the median change for the group is 457 (IQR: 249.0, 1160.0) (p=0.06). Conclusion This case series documents the successful clinical application of chronic RBCX in TDT patients as a means of stabilizing serum ferritin levels over time. Mean ferritin levels were significantly lower, clinically, after transitioning from chronic simple RBC transfusion to RBCX (Table 1), though analysis is limited due to cohort size. Blood utilization increased after transitioning to RBCX. Next steps in evaluating our practice for the patient group will be to evaluate iron deposition status with MRI T2* imaging.
34
Benmessaoud, Youcef, Frédéric Dubas, and Mickael Hilairet. "Combining the Magnetic Equivalent Circuit and Maxwell–Fourier Method for Eddy-Current Loss Calculation." Mathematical and Computational Applications 24, no. 2 (2019): 60. http://dx.doi.org/10.3390/mca24020060.
Full textAbstract:
In this paper, a hybrid model in Cartesian coordinates combining a two-dimensional (2-D) generic magnetic equivalent circuit (MEC) with a 2-D analytical model based on the Maxwell–Fourier method (i.e., the formal resolution of Maxwell’s equations by using the separation of variables method and the Fourier’s series) is developed. This model coupling has been applied to a U-cored static electromagnetic device. The main objective is to compute the magnetic field behavior in massive conductive parts (e.g., aluminum, magnets, copper, iron) considering the skin effect (i.e., with the eddy-current reaction field) and to predict the eddy-current losses. The magnetic field distribution for various models is validated with 2-D and three-dimensional (3-D) finite-element analysis (FEA). The study is also focused on the discretization influence of 2-D generic MEC on the eddy-current loss calculation in conductive regions. Experimental tests and 3-D FEA have been compared with the proposed approach on massive conductive parts in aluminum. For an operating point, the computation time is divided by ~4.6 with respect to 3-D FEA.
35
Elbashir, Khalid Elsir, Celine Richard, Tomas Bryndziar, et al. "Sensorineural Hearing Loss in Children with Sickle Cell Disease: A Series of Four Cases." Blood 144, Supplement 1 (2024): 5316. https://doi.org/10.1182/blood-2024-208939.
Full textAbstract:
Background The World Health Organization defines hearing loss as hearing thresholds of 20 dB or more in one or both ears. There is a paucity of literature on hearing impairment in individuals with sickle cell disease (SCD). Vaso-occlusion caused by sickled erythrocytes resulting in hypoxia of the organ of Corti and cochlear damage is hypothesized to cause hearing impairment in SCD. (Abdelmahmuod et al., 2020; Rissatto-Lago, 2022) Sensorineural hearing loss (SNHL) and conductive hearing loss (CHL) prevalence in the general population in the United States is estimated to be 11.6%, with both ears being equally affected. (Rein et al., 2024) SNHL accounts for most cases of hearing loss in SCD, and its prevalence in SCD is greater than in the general population. In pediatric patients with SCD, the SNHL prevalence ranges from 3.8% to 28.8%. (Lago et al., 2018) Furthermore, a French study focusing on pediatric patients with SCD reported that even children with normal hearing were found to harbor auditory processing disorders and subclinical audiology issues. (Bois et al., 2019) SCD-related hearing loss may be underdiagnosed in this patient population, as periodic audiology screening is recommended only for those on iron chelation therapy. Method This is a case series describing 4 pediatric patients (&lt;18 years of age) with SCD not on chelation therapy, who were diagnosed with SNHL based on clinical symptoms and confirmed by a diagnostic audiogram. Demographic, laboratory, imaging, healthcare utilization, and medication use data for these patients were extracted from the Sickle Cell Clinical Research and Intervention Program (SCCRIP; NCT02098863) database, and clinical characteristics, audiological data, and outcomes for these patients were extracted from medical records by retrospective chart review. Results All 4 patients with SNHL had normal newborn hearing screenings and were screened for hearing loss based on symptoms and/or clinical suspicion. Other risk factors for SNHL, such as history of pneumococcal infections, noise-induced hearing loss, trauma, malignancies, genetic disorders, and exposure to ototoxic medications were ruled out. The age at diagnosis of hearing loss ranged from 5 to 16 years. Three patients had HbSS, and one had HbSC genotype. All 4 patients were on hydroxyurea therapy, with fetal hemoglobin levels ranging from 8% to 40%. Three of the 4 patients had moderate to severe hearing loss at the time of the audiology diagnosis and were prescribed hearing aids. High healthcare utilization was noted in these individuals, with the average annual number of emergency department visits and hospital admissions before the SNHL diagnosis ranging from 1 to 4 and 2 to 6, respectively. Three patients had sickle retinopathy, and 3 patients had obstructive sleep apnea. Conclusion In this case series, we highlight 4 patients with SCD with SNHL without an identified etiology, suggesting that the underlying SCD pathophysiology may be contributing to the development of SNHL in this patient population, and may present early in life. In this case series, all 4 patients were not on chelation therapy and not receiving screening audiograms, hence were diagnosed only when their symptoms were severe (moderate-severe deafness). Given the high prevalence of SNHL and subclinical hearing impairment in SCD reported in the literature, early and periodic routine audiology screening should be considered for all patients with SCD. Prospective studies of larger cohorts should be conducted to ascertain the role of SCD as an independent risk factor for SNHL, identify other risk factors in this population, and evaluate the role of SCD disease-modifying therapies in preventing SNHL in this patient population.
36
Sertphon, Darunee, Phimphaka Harding, Keith Murray, et al. "Solvent Effects on the Spin Crossover Properties of Iron(II) Imidazolylimine Complexes." Crystals 9, no. 2 (2019): 116. http://dx.doi.org/10.3390/cryst9020116.
Full textAbstract:
A series of Fe(II) complexes, fac-[Fe(4-ima-Bp)3](Y)2⋅sol (Y = ClO4; sol = 3EtOH 1, 3MeOH 2; Y= BF4; sol = EtOH⋅4H2O 3, 4H2O 4 and 3.5MeCN 5) have been prepared and structurally and magnetically characterized. The low temperature structures of 1, 2 and 5 have been determined by X-ray crystallography with LS Fe(II) centres found in all cases. Extensive C–H···π interactions between the cations form 2D layers, which are linked to one another through N-H···O and O-H···O hydrogen bonds, resulting in high cooperativity. Despite 5 containing MeCN, N-H···O/F hydrogen bonds, and C–H···π and π-π interactions combine to give similar 2D layers. Magnetic measurements reveal moderately abrupt spin crossover for 1-4; becoming more gradual and only 50% complete in 1 due to solvent loss. The MeCN solvate shows more gradual SCO and reinforces how subtle changes in packing can significantly influence SCO behaviour.
37
Winatapura, Didin Sahidin, Ade Mulyawan, Ari Adi Wisnu, and Yunasfi. "Synthesis, Structure, Magnetic and Absorption Properties of Nd Doped Y3Fe5O12 Garnets Prepared by Mechanochemical Method." Key Engineering Materials 855 (July 2020): 52–57. http://dx.doi.org/10.4028/www.scientific.net/kem.855.52.
Full textAbstract:
Neodymium substituted yttrium iron garnet (YIG) nanoparticles with compositional variation of NdxY3−xFe5O12 where x = 0.0, 0.2, 0.5 and 0.8 was prepared by mechanochemicals method using high energy milling (HEM). The characterization was done using X-rays diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). It was found that the mechanical milling followed by sintering promotes the complete structural formation of the yttrium iron garnet (YIG) structure. The XRD patterns confirm the complete introduction of Nd3+ ion into the YIG with an addition of Nd doping concentration. nanocrystalline particles with high purity and sizes ranging from 0.12μm to 0.16μm were obtained. The magnetization value, Ms from all Nd-doped samples were obtained in the range between 34 to 37emu.g-1. The magnetic coercivity (Hc) was achieved of 0.012kOe (12Oe) for the non-doped sample (YNd-0) and then increase with the addition of neodymium concentration. The increase in Hc for all the sample series can be attributed to an enhancement of the magnetocrystalline anisotropy with anisotropic Fe2+. The variation of the reflection loss (RL) versus frequency was observed in Nd doped YIG, Y1-xNdxFe5O12 with x = 0.0 – 0.8 in the frequency range of 7 –12 GHz. The optimum reflection loss (RL) was found to be 8.66(-dB) at 9.5GHz in Y2.2Nd0.8Fe5O12 (YNd-08) for x = 0.8.
38
Leonowicz, Marcin, Joanna Kozłowska, and Łukasz Wierzbicki. "Rheological Fluids for Energy Absorbing Systems." Applied Mechanics and Materials 440 (October 2013): 13–18. http://dx.doi.org/10.4028/www.scientific.net/amm.440.13.
Full textAbstract:
Two types of non-Newtonian fluids, magneto rheological (MRF) and shear thickening (STF) fluids, respectively were chosen as candidates for energy dissipation study in smart body armour. A series of magneto rheological fluids was synthesized on a basis of synthetic oil and carbonyl iron. The shear modules for the MRF containing 75 wt% of carbonyl iron, obtained in a magnetic field of 230 kA/m were as follows: complex shear modulus G* - 1.2 MPa, storage modulus G-1.2 MPa and loss modulus G 0.35 MPa. The studies revealed also that the silica fumed, dispersed in polypropylene glycol or polyethylene oxide, demonstrates shear thickening properties. The best combination of the properties (high viscosity, obtained at high shear rate) represents the material composed of the silica fumed (SF) and PEO300. Change of the volume fraction of the SF and variation of the molecular weight of the oligomer enables tailoring of the STF properties. Ballistic tests revealed that the structures containing PE bags with MRF (in magnetic field) or STF can enhance the protective performance of body armours providing their flexibility.
39
Biguzzi, Eugenia, Simona Maria Siboni, and Flora Peyvandi. "How I treat gastrointestinal bleeding in congenital and acquired von Willebrand disease." Blood 136, no. 10 (2020): 1125–33. http://dx.doi.org/10.1182/blood.2019003702.
Full textAbstract:
Abstract Gastrointestinal (GI) bleeding is distinctive of severe von Willebrand disease (VWD), generally arising in older patients; in most cases, blood transfusion and hospitalization are required. The presence of arteriovenous malformations is often described when endoscopic examinations are performed. Patients with congenital type 3, 2A, and 2B are those most frequently affected by this symptom, possibly due to the loss of high-molecular-weight multimers of von Willebrand factor (VWF). GI bleeding can also occur in patients affected by acquired von Willebrand syndrome. Endoscopic examination of the GI tract is necessary to exclude ulcers and polyps or cancer as possible causes of GI bleeding. In congenital VWD, prophylaxis with VWF/factor VIII concentrates is generally started after GI-bleeding events, but this therapy is not always successful. Iron supplementation must be prescribed to avoid chronic iron deficiency. Possible rescue therapies (high-dose statins, octreotide, thalidomide, lenalidomide, and tamoxifen) were described in a few case reports and series; however, surgery may be necessary in emergency situations or if medical treatment fails to stop bleeding. In this article, we present several clinical cases that highlight the clinical challenges of these patients and possible strategies for their long-term management.
40
Moosmann, Bernd, Mario Schindeldecker, and Parvana Hajieva. "Cysteine, glutathione and a new genetic code: biochemical adaptations of the primordial cells that spread into open water and survived biospheric oxygenation." Biological Chemistry 401, no. 2 (2020): 213–31. http://dx.doi.org/10.1515/hsz-2019-0232.
Full textAbstract:
AbstractLife most likely developed under hyperthermic and anaerobic conditions in close vicinity to a stable geochemical source of energy. Epitomizing this conception, the first cells may have arisen in submarine hydrothermal vents in the middle of a gradient established by the hot and alkaline hydrothermal fluid and the cooler and more acidic water of the ocean. To enable their escape from this energy-providing gradient layer, the early cells must have overcome a whole series of obstacles. Beyond the loss of their energy source, the early cells had to adapt to a loss of external iron-sulfur catalysis as well as to a formidable temperature drop. The developed solutions to these two problems seem to have followed the principle of maximum parsimony: Cysteine was introduced into the genetic code to anchor iron-sulfur clusters, and fatty acid unsaturation was installed to maintain lipid bilayer viscosity. Unfortunately, both solutions turned out to be detrimental when the biosphere became more oxidizing after the evolution of oxygenic photosynthesis. To render cysteine thiol groups and fatty acid unsaturation compatible with life under oxygen, numerous counter-adaptations were required including the advent of glutathione and the addition of the four latest amino acids (methionine, tyrosine, tryptophan, selenocysteine) to the genetic code. In view of the continued diversification of derived antioxidant mechanisms, it appears that modern life still struggles with the initially developed strategies to escape from its hydrothermal birthplace. Only archaea may have found a more durable solution by entirely exchanging their lipid bilayer components and rigorously restricting cysteine usage.
41
Zakiyya, Hanna, and Tamas Kekesi. "(Digital Presentation) The Role of Iron in the Zinc Electrodeposition from Chloride Media for Recovering Zinc from Spent Pickling Liquors." ECS Meeting Abstracts MA2022-02, no. 27 (2022): 1045. http://dx.doi.org/10.1149/ma2022-02271045mtgabs.
Full textAbstract:
Electrodeposition of Zn from chloride media had been studied by potentiodynamic method to understand the characteristics of Zn recovery from spent pickling liquor (SPL). Various concentration, pH, agitation speed and impurities contamination were examined in the series of experiments. The influence of Zn concentration in the range of 30-150 g/dm3 relevant to the real SPL were studied along with acidity level change (pH 1.5-5.5). It was found that the cathodic deposition started with the uniform patern followed by sponge-like deposit and as the concentration of the electrolyte near the cathode surface decreased, the dendritic deposition start to grow, especially at the edge of the cathodes. It was found that the effect of iron concentration on the polarization curves of zinc from SPL is complex. Initially it has a negative effect on the generated cathodic current because of the enhancement of hydrogen bubble formation. At a higher concentration range, however, iron deposits at a relatively higher rate. Further increased iron concentrations may make the composition of the Zn-Fe deposit dominantly in favor of iron, resulting in a hydrogen dominated cathodic mechanism. It is also characterised by the loss of the dendritic structure – attributed mostly of zinc deposition when hydrogen bubbles are not blocking the cathode. As the gas evolution becomes more characteristic, the deposit tends to become more powdery. Under such conditions the cathode becomes smoother and the active surface is reduced. Increasing the stirring speed, the powder was easily detached from the cathode surface. Iron, however can enhance the cathodic deposition process of zinc. With 30 – 60 g/dm3 iron in the 90 g/dm3 Zn solution, an increased iron concentration resulted in a significant increase in the mass of the deposited zinc. This may be interpreted by a beneficial effect of the increased hydrogen evolution enhancing the zinc ion transport to the electrode surface. However further increments of iron had a contrary effect, possibly by the locally increased – and generally detected – pH of the solution indirectly causing a superficial precipitation of hydroxides. Technically pure zinc could be deposited from only low-iron (< < 30 g/dm3) zinc solutions (of 90 g/dm3 Zn) at relatively vigorous stirring speeds. High iron concentration in the solution is definitely unsuitable for obtaining the aimed quality of cathode zinc.
42
Todaro, Serena, Francesco Frusteri, Dariusz Wawrzyńczak, et al. "Copper and Iron Cooperation on Micro-Spherical Silica during Methanol Synthesis via CO2 Hydrogenation." Catalysts 12, no. 6 (2022): 603. http://dx.doi.org/10.3390/catal12060603.
Full textAbstract:
A series of mono- and bi-metallic copper and iron samples were prepared by impregnation method on micro-spherical silica and used for the synthesis of methanol via CO2 hydrogenation. Compared with conventional carrier oxides, micro-spherical silica has obvious advantages in terms of absorption capacity and optimal distribution of active phases on its surface, also exhibiting excellent heat resistance properties and chemical stability. The prepared catalysts were characterized by various techniques including XRF, XRD, SEM, TEM, H2-TPR and CO2-TPD techniques, while catalytic measurements in CO2 hydrogenation reaction to methanol were performed in a fixed bed reactor at a reaction pressure of 30 bar and temperature ranging from 200 to 260 °C. The obtained results revealed that the mutual interaction of copper–iron induces promotional effects on the formation of methanol, especially on systems where Fe enrichment on the silica support favours the presence of a larger concentration of oxygen vacancies, consequently responsible for higher CO2 adsorption and selective methanol production. Surface reconstruction phenomena rather than coke or metal sintering were responsible for the slight loss of activity recorded on the catalyst samples during the initial phase of reaction; however, with no appreciable change on the product selectivity.
43
Freeman, Hugh J. "Clinical Spectrum of Biopsy-Defined Celiac Disease in the Elderly." Canadian Journal of Gastroenterology 9, no. 1 (1995): 42–46. http://dx.doi.org/10.1155/1995/290893.
Full textAbstract:
Thirty patients (17 females and 13 males) with adult celiac disease initially diagnosed after age 60 were seen during a 12-year period. Diagnosis in each patient was based on small intestinal biopsy and a clinical as well as histological response to a strict gluten-free diet. Diarrhea, weight loss and/or anemia, usually due to iron deficiency, were present in the majority of patients and often lead to other diagnostic considerations, including colon cancer, prior to definition of celiac disease. No patient in this series had a known family history of celiac disease. Dermatitis herpetiformis and thyroid hypofunction were frequently detected in this elderly population, possibly reflecting the autoimmune and systemic nature of celiac disease. Neoplastic disease was common in this age group, suggesting that particular vigilance in follow-up is required, especially for lymphoma, in elderly patients with celiac disease.
44
Bica, Ioan, and Gabriela-Eugenia Iacobescu. "Magneto-Dielectric Effects in Polyurethane Sponge Modified with Carbonyl Iron for Applications in Low-Cost Magnetic Sensors." Polymers 14, no. 10 (2022): 2062. http://dx.doi.org/10.3390/polym14102062.
Full textAbstract:
In this study, magnetizable polyurethane sponges (MSs) were obtained from commercial absorbent polyurethane sponges (PSs) doped with carbonyl iron microparticles (CIPs). Based on MSs, we manufactured cylindrical capacitors (CCs). The CCs were subjected to both a magnetic field and an alternating electric field, with a frequency of f=1 kHz. Using an RLC bridge, we measured the series electric capacitance, Cs, and the tangent of the loss angle, Ds. From the functions Cs=Cs(δ)CCs and Ds=Ds(δ)CCs, we extracted the components of the complex dielectric permittivity. It was found that the CIPs embedded in the MS matrix aggregated, leading to magneto-dielectric effects such as the enhancement of the complex dielectric permittivity components when applying the magnetic field as a principal effect and the enhancement of the electric capacitance and time constant of the capacitors as a secondary effect. The obtained results represent landmarks in the realization of low-cost magnetic field sensors, deformation and mechanical stress transducers in the robotics industry, etc.
45
McConachie, Sean, Krista Wahby, Zinah Almadrahi, and Sheila Wilhelm. "Early Experiences With PEGylated Carboxyhemoglobin Bovine in Anemic Jehovah’s Witnesses: A Case Series and Review of the Literature." Journal of Pharmacy Practice 33, no. 3 (2018): 372–77. http://dx.doi.org/10.1177/0897190018815373.
Full textAbstract:
Jehovah’s Witnesses (JW) represent a complex patient population due to their refusal to accept blood transfusions on religious grounds. Pharmacologic management of anemic JW patients is limited to stimulation of hematopoiesis by iron and erythropoietin supplementation and reduction of blood loss by prothrombin complex concentrates (PCCs). Hemoglobin-based oxygen carriers (HBOCs) represent the only pharmacologic modality for JW patients capable of acutely increasing a patient’s oxygen carrying capacity in the setting of organ failure, yet clinical safety and efficacy data are lacking in this population. We report 3 cases in which the HBOC, PEGylated carboxyhemoglobin bovine (Sanguinate®), was requested under emergent circumstances for severely anemic (hemoglobin <5 g/dL) JW patients who refused blood transfusions. Two patients received PEGylated carboxyhemoglobin infusions for severe anemia, while the third patient died prior to receiving the medication. One patient who received Sanguinate died after 5 units of medication. The other patient’s hemoglobin recovered and she was discharged in stable condition. This series demonstrates the complex nature of the critically anemic JW population and highlights the clinical considerations of using HBOCs in clinical practice and the critical need for further research before they can be broadly recommended.
46
Reynolds, Gavin, Simon Epps, Alyson Huntley, and Denize Atan. "Micronutrient Deficiencies Presenting with Optic Disc Swelling Associated with or without Intracranial Hypertension: A Systematic Review." Nutrients 14, no. 15 (2022): 3068. http://dx.doi.org/10.3390/nu14153068.
Full textAbstract:
Idiopathic intracranial hypertension (IIH) is a neurological disorder characterised by optic disc swelling secondary to raised intracranial pressure (ICP) of unknown cause. Obesity is the most established and prevalent risk factor in developed countries. As obesogenic diets are high in calories and nutrient-poor, there may be associated nutritional deficiencies that contribute to the clinical presentation of IIH. Yet none, aside from iron deficiency, are currently included in the inclusion or exclusion criteria for the diagnosis of IIH. Our primary aim was to determine which micronutrient deficiencies, aside from iron deficiency, could present with optic disc swelling associated with or without intracranial hypertension that could potentially meet current IIH diagnostic criteria. To this end, we conducted a systematic search of articles published between 1 January 1980 and 18 December 2020 reporting cases of optic disc swelling associated with micronutrient deficiencies. In total, 65 cases met the eligibility criteria from initial searches: all were case reports and case series with a high risk of bias. Our findings suggest that patients with IIH or unexplained optic disc swelling ought to be screened, investigated, and treated for associated micronutrient deficiencies in vitamin A, B1 and B12; and weight loss interventions in IIH patients ought to promote better nutrition in addition to overall calorie restriction.
47
Xu, Weihui, Yushuai Ruan, Weishu Wang, and Xiaoke He. "Experimental Study on No-Load Loss Characteristics of an Alternating Current Excitation Motor." Electronics 13, no. 1 (2023): 1. http://dx.doi.org/10.3390/electronics13010001.
Full textAbstract:
An AC excitation power supply will produce a series of harmonic currents in motors compared to the conventional power supply, increase the time harmonic component, and then generate a harmonic magnetic field; harmonics will cause motor vibrations and noise in the motor and will produce a corresponding additional loss, increasing the motor temperature rise; these key technical problems need to be solved in domestic pumped storage AC excitation motor engineering applications. Herein, the no-load loss characteristic test of a 3 MW alternating current excited motor was mainly carried out using a test prototype of the 3 MW alternating current excitation motor. Further, with the aid of the finite element method, the numerical study of the no-load loss characteristics of a 3 MW alternating current excited motor was performed. The relationship between the key factors such as the no-load characteristics, no-load loss characteristics, and constant loss and voltage per unit value is analyzed, and the variation law of the no-load core loss of motors under different loads is explored. The results demonstrate that, under no-load conditions, when the applied voltage was less than the rated voltage, the voltage was proportional to the current. When the applied voltage was more significant than the rated voltage, the current increased as the voltage increased, but the relationship between the two was no longer proportional. The constant loss of the motor maintained a linear relationship with the square of the unit value of the voltage scale. When the square of the unit value of the voltage scale was zero, the loss was equivalent to the wind friction loss under no load. The core loss increased with the increase in load, and the greater the load, the faster the increase rate of the motor iron loss. The comparison deviation between the test and simulation results was less than 10%. The simulation and experimental results verified the effectiveness of finite element modeling and the finite element calculation method.
48
Hirose, Masanori, Kaoru Yamamoto, Hirofumi Miyahara, Kazunori Sakata, and Keisaku Ogi. "Abrasion Behavior of High Cr-V-Nb Cast Iron." Key Engineering Materials 457 (December 2010): 243–48. http://dx.doi.org/10.4028/www.scientific.net/kem.457.243.
Full textAbstract:
A series of abrasion tests on high Cr-V-Nb cast irons revealed that the addition of MC type carbide formers, V and Nb, remarkably enhances the abrasion resistance of high Cr cast iron, and the abrasion resistance becomes higher with the increase in MC type carbides[1]. Therefore, hyper eutectic Fe-4.7%C-15%Cr-7%V-5%Nb-5%Mo alloy melt was poured into 30kg and 1kg sand mold castings to distribute different sizes of primary and eutectic carbides in hardenable matrix. The abrasion test specimens cut from each casting were austenitized at 1323K for 1h then cooled in air. These specimens were tempered at 773K for 1h followed by air cooling. The hardness of specimens was 1015-1018HV50. The rubber wheel abrasion test, a typical 3 body type one, was performed on these quenched and tempered specimens with 56-107, 107-150 and 297 μm dia. silica grit. The testing load was 86.3N and 172.5N, and the rubber wheel rotation speed was varied from 1s-1 to 4s-1. Though the higher testing load increases the wear loss, the wear rate expressed by the wear volume/( testing load × wear distance) changes depending on the wear condition and the microstructure. In case of 30kg cast specimen, the silica grit preferentially attack and scrape off the matrix, and the wear rate increases with the increase in the testing load. The fine carbides in 1kg cast specimens effectively protect the matrix from the attack of silica grit, and the wear rate decreases with increasing load which causes silica grit blunt and fracture. However, fine carbides tend to be fractured by silica grit and diminish the protective effect. Based on the worn surface structures, the abrasion mechanism is discussed comparing those of steel and eutectic 25%Cr cast iron.
49
Aulbert, E. "Die Anämie bei malignen Tumorerkrankungen." Nuklearmedizin 28, no. 06 (1989): 247–54. http://dx.doi.org/10.1055/s-0038-1629498.
Full textAbstract:
The cellular uptake and lysosomal accumulation of 67Ga-labelled transferrin within tumors of different malignancy were examined using tissue fractionation and immunological techniques. As tumor models the slowly growing Morris hepatoma 5123C, the moderately growing Novikoff hepatoma and the fast and aggressive Yoshida hepatoma AH 130 were investigated. Isolation of subcellular fractions of tumor homogenates was performed by differential centrifugation and density-gradient centrifugation. The intracellular 67Gatransferrin was found to be highly concentrated within the purified lysosomes. The transferrin within the lysosomal fraction was identified by radial immunodiffusion technique using monospecific antiserum. The accumulation of 67Gatransferrin by the tumors resulted in a faster disappearance of 67Ga-transferrin from the blood. This loss of circulating 67Ga-transferrin correlated with the proliferation activity and the spread of the tumors. Since transferrin is indispensible for the utilization of iron by the heme-synthesizing red cell precursors, transferrin concentration in the blood is the limiting factor for the utilization of iron in hemoglobin synthesis. Thus, in a further series of experiments we investigated the development of anemia in tumor-bearing rats. With increasing tumor mass a progressive fall of hemoglobin concentration was found. The anemia was more severe in the faster growing Novikoff hepatoma than in the slowly growing Morris hepatoma. The most significant reduction of hemoglobin concentration was found in the very fast growing Yoshida hepatoma. After total tumor resection hemoglobin concentration and red blood cell count normalized completely within 6-8 weeks. We conclude from these data that the uptake of transferrin by the tumor cells results in a faster disappearance of transferrin from the blood. This loss of circulating transferrin correlates with tumor mass and proliferation activity and is one of the factors responsible for the anemia seen in patients with malignant tumors.
50
Arnaouteli, Sofia, D. A. Matoz-Fernandez, Michael Porter, et al. "Pulcherrimin formation controls growth arrest of theBacillus subtilisbiofilm." Proceedings of the National Academy of Sciences 116, no. 27 (2019): 13553–62. http://dx.doi.org/10.1073/pnas.1903982116.
Full textAbstract:
Biofilm formation byBacillus subtilisis a communal process that culminates in the formation of architecturally complex multicellular communities. Here we reveal that the transition of the biofilm into a nonexpanding phase constitutes a distinct step in the process of biofilm development. Using genetic analysis we show thatB. subtilisstrains lacking the ability to synthesize pulcherriminic acid form biofilms that sustain the expansion phase, thereby linking pulcherriminic acid to growth arrest. However, production of pulcherriminic acid is not sufficient to block expansion of the biofilm. It needs to be secreted into the extracellular environment where it chelates Fe3+from the growth medium in a nonenzymatic reaction. Utilizing mathematical modeling and a series of experimental methodologies we show that when the level of freely available iron in the environment drops below a critical threshold, expansion of the biofilm stops. Bioinformatics analysis allows us to identify the genes required for pulcherriminic acid synthesis in other Firmicutes but the patchwork presence both within and across closely related species suggests loss of these genes through multiple independent recombination events. The seemingly counterintuitive self-restriction of growth led us to explore if there were any benefits associated with pulcherriminic acid production. We identified that pulcherriminic acid producers can prevent invasion by neighboring communities through the generation of an “iron-free” zone, thereby addressing the paradox of pulcherriminic acid production byB. subtilis.