Noninvasive Assessment of Kidney Injury by Combining Structure and Function Using Artificial Intelligence-Based Manganese-Enhanced Magnetic Resonance Imaging.

Contrast-enhanced magnetic resonance imaging (MRI) is seriously limited in kidney injury detection due to the nephrotoxicity of clinically used gadolinium-based contrast agents. Herein, we propose a noninvasive method for the assessment of kidney injury by combining structure and function information based on manganese (Mn)-enhanced MRI for the first time. As a proof of concept, the Mn-melanin nanoprobe with good biocompatibility and excellent T1 relaxivity is applied in MRI of a unilateral ureteral obstruction mice model. The abundant renal structure and function information is obtained through qualitative and quantitative analysis of MR images, and a brand new comprehensive assessment framework is proposed to precisely identify the degree of kidney injury successfully. Our study demonstrates that Mn-enhanced MRI is a promising approach for the highly sensitive and biosafe assessment of kidney injury in vivo.

Characteristic pollutants risk assessment of modified manganese residue utilization in sintered product.

The resource disposal of electrolytic manganese residue can effectively solve the problem of environmental pollution caused by it, among which the problem of heavy metal pollution is the most prominent. In this study, a new type of eco-friendly brick mixed with electrolytic manganese residue was designed. The influence of the content of electrolytic manganese residue on its macroscopic properties, microscopic properties, and leaching characteristics was analyzed by test methods such as compressive strength test, radioactivity test, XRF, XRD, FTIR, and ICP test of bricks. The results showed that the manganese content in the EMR leachate was 8120 mg/L, which exceeded the Chinese standard. The leaching experiment of ordinary aqueous solution of sintered bricks mixed with 20% EMR showed that the content of heavy metals was far lower than the Chinese national standard. There was no non-carcinogenic risk of heavy metals in the strong acid leaching solution of sintered bricks mixed with 20% EMR. Only the carcinogenic risk values of Cr for adults and children were 4.21 × 10-4 and 9.82 × 10-4 respectively, both exceeding the USEPA limit, but the application scene of sintered bricks was difficult to achieve strong acidity, so it was judged that it had no carcinogenic risk to the human body. Characteristic heavy metals such as Mn, Cr, and As existed stably in sintered bricks through substitution and encapsulation. In addition, the compressive strength and radioactivity of EMR sintered bricks met the requirements of the Chinese national standard "Fired Ordinary Bricks." This product can be used as national standard MU20 grade brick. This study provided an efficient method for the safe and environmentally friendly disposal of EMR in a sustainable control system.

Design and performance of an epithermal neutron flux detector using 55Mn(n,γ)56Mn reaction for BNCT.

The measurement of the epithermal neutron (0.5 eV - 10 keV) flux of a boron neutron capture therapy (BNCT) treatment beam is a critical issue to its quality assessment and evaluation of the radiation dose to the treated patients. In this work, an activation detector using 55Mn(n,γ)56Mn reaction is designed by Monte Carlo simulations to measure the epithermal neutron flux of BNCT treatment beam. The detector is spherical and it has an absorber/moderator/absorber/manganese (Mn) foil arrangement from outside to inside. The activation material, i.e., Mn foil, is located at the geometrical center of the detector. After the design, the performance of the detector is evaluated by Monte Carlo simulations using the treatment neutron beams of operating reactor-based BNCT facilities. The results and related analysis indicate that the proposed detector will be efficiently applicable in the quality assessment of BNCT treatment beam and evaluation of the radiation dose to the treated patients.

A low cost of phosphate-based binder for Mn2+ and NH4+-N simultaneous stabilization in electrolytic manganese residue.

Electrolytic manganese residue (EMR) is a solid waste remained in filters after using sulfuric acid to leaching manganese carbonate ore. EMR contains high concentration of soluble manganese (Mn2+) and ammonia nitrogen (NH4+-N), which seriously pollutes the environment. In this study, a low cost of phosphate based binder for Mn2+ and NH4+-N stabilization in EMR by low grade-MgO (LG-MgO) and superphosphate was studied. The effects of different types of stabilizing agent on the concentrations of NH4+-N and Mn2+, the pH of the EMR leaching solution, stabilizing mechanisms of NH4+-N and Mn2+, leaching test and economic analysis were investigated. The results shown that the pH of the EMR leaching solution was 8.07, and the concentration of Mn2+ was 1.58 mg/L, both of which met the integrated wastewater discharge standard (GB8978-1996), as well as the concentration of NH4+-N decreased from 523.46 mg/L to 32 mg/L, when 4.5 wt.% LG-MgO and 8 wt.% superphosphate dosage were simultaneously used for the stabilization of EMR for 50 d Mn2+ and NH4+-N were mainly stabilized by Mn3(PO4)2·2H2O, MnOOH, Mn3O4, Mn(H2PO4)2·2H2O and NH4MgPO4·6H2O. Economic evaluation revealed that the treatment cost of EMR was $ 11.89/t. This study provides a low-cost materials for NH4+-N and Mn2+ stabilization in EMR.

An open source and reduce expenditure ROS generation strategy for chemodynamic/photodynamic synergistic therapy.

The therapeutic effect of reactive oxygen species (ROS)-involved cancer therapies is significantly limited by shortage of oxy-substrates, such as hypoxia in photodynamic therapy (PDT) and insufficient hydrogen peroxide (H2O2) in chemodynamic therapy (CDT). Here, we report a H2O2/O2 self-supplying nanoagent, (MSNs@CaO2-ICG)@LA, which consists of manganese silicate (MSN)-supported calcium peroxide (CaO2) and indocyanine green (ICG) with further surface modification of phase-change material lauric acid (LA). Under laser irradiation, ICG simultaneously generates singlet oxygen and emits heat to melt the LA. The exposed CaO2 reacts with water to produce O2 and H2O2 for hypoxia-relieved ICG-mediated PDT and H2O2-supplying MSN-based CDT, acting as an open source strategy for ROS production. Additionally, the MSNs-induced glutathione depletion protects ROS from scavenging, termed reduce expenditure. This open source and reduce expenditure strategy is effective in inhibiting tumor growth both in vitro and in vivo, and significantly improves ROS generation efficiency from multi-level for ROS-involved cancer therapies.

A novel method for the stabilization of soluble contaminants in electrolytic manganese residue: Using low-cost phosphogypsum leachate and magnesia/calcium oxide.

Electrolytic manganese residue (EMR) contains a large amount of NH4+-N and Mn2+ and can negatively impact the environment. A stabilization treatment of soluble contaminants in the EMR is necessary for its reuse and safe stacking. This study presents experimental results for the stabilization of NH4+-N and Mn2+ in the EMR using phosphogypsum leachate as a low-cost phosphate source and MgO/CaO (PLMC) process. The results demonstrated that the stabilization efficiency of NH4+-N and Mn2+ was 93.65% and 99.99%, respectively, under the following conditions: a phosphogypsum leachate dose of 1.5 mL g-1, an added MgO dose of 0.036 g g-1, an added CaO dose of 0.1 g g-1 and a reaction time of 2 h. The stabilization effect of the PLMC process was higher and more cost effective than that of using Na3PO4·12H2O and MgO/CaO. The concentration of NH4+-N and Mn2+ in the leaching liquor decreased to 80 mg L-1 and 0.5 mg L-1, respectively, after the stabilization under the optimum conditions. The stabilization characteristics indicated that NH4+-N was stabilized to form NH4MgPO4·6H2O (struvite) and that Mn2+ was stabilized to form Mn5(PO4)2(OH)4, Mn3(PO4)2·3H2O and Mn(OH)2. PO43--P, F-, and heavy metal ions of the phosphogypsum leachate were removed from the leaching liquor and stabilized in the treated EMR.

Assessment of the health risk related to exposure to ultrafine, fine, and total particulates and metals in a metal finishing plant.

The materials and byproducts of the processes used in the metal finishing industry are released as particle contaminants into the air in the workplace. The present study aimed to determine the concentrations and size distributions of these particles and of elements chromium, nickel, copper, manganese, cobalt, and lead (Cr, Ni, Cu, Mn, Co, and Pb, respectively) in a metal finishing industry and evaluate their potential health risks. Particles that are airborne from the dipping baths in the plant were sampled using a Sioutas cascade impactor at five different size fractions (PM>2.5, PM1.0-2.5, PM0.5-1.0, PM0.25-0.5, PM<0.25) and gravimetric analyses were conducted on the sampled filters. The GF-AAS 600 graphite atomic absorption spectrophotometer (PerkinElmer Corporation, Waltham, MA, USA) was used to analyze the elements and the method of USEPA was used to assess the health risk. The ratio of fine particles (PM2.5) to total suspended particles (TSPs) was 0.6. We observed that 50% of TSPs were composed of PM1.0 and that 68-88% of the metals were found in the fine particle fractions. Pb, Cr, and Mn were significantly positively correlated in the PM1.0 fraction, and the highest linear relationship was found between Pb and Cr (r = 0.85, p < 0.01). The total hazard quotient (HQ) for PM2.5 was 1.43, which is higher than the acceptable limit of 1.0. The excess lifetime cancer risk (ELCR) for hexavalent chromium (Cr[VI]) in PM2.5 was 6.09 × 10-5 for female workers and 6.54 × 10-5 for male workers, which are higher than the acceptable limit of 1.0 × 10-6, while total ELCRs for female and male workers were 6.21 × 10-5 and 6.21 × 10-5, respectively. The lifetime cancer risk associated with Cr(VI) in Cr electroplating plants should be taken into consideration as a significant health risk for the workers.

Simultaneous optimizing removal of manganese and ammonia nitrogen from electrolytic metal manganese residue leachate using chemical equilibrium model.

Electrolytic metal manganese residue leachate (EMMRL) was produced from long-term deposition of electrolytic metal manganese residue. EMMRL contains huge amount of manganese and ammonia nitrogen which could seriously damage the ecological environment. In this study, a chemical equilibrium model-Visual MINTEQ was used to simultaneously optimize removal of manganese and ammonia nitrogen from EMMRL with chemical precipitation methods. In the laboratory experiment, the effect of different N: P ratios and pH were investigated, and the characterization of the precipitates was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The results showed that over 99.9% manganese and 96.2% ammonia nitrogen were simultaneously removed, respectively, when molar ratio of N:P was 1:1.15 at pH 9.5. Moreover, the experimental results corresponded well with the model outputs with respect to ammonia nitrogen and manganese removal. Manganese was mainly removed in the form of MnHPO4·3H2O and manganite, and ammonia nitrogen was mainly removed in the form of struvite. Economic evaluation indicated the chemical precipitation methods can be applied in the factory when the price of precipitation was higher than 0.295 $/kg.

Assessment of saliva, hair and toenails as biomarkers of low level exposure to manganese from drinking water in children.

We evaluated hair, toenails, and saliva (whole and supernatant) as biomarkers of exposure to manganese (Mn) in 274 school age children (6-13 years) consuming well water in southeastern New Brunswick, Canada. Mn concentrations in tap water ranged from <0.03 to 1046µgL-1 (geometric mean 5.96µgL-1). The geometric mean of Mn intake resulting from the consumption of water was 0.25 (0-34.95) µg kg-1day-1. Both Mn concentration in water and Mn intake were significantly correlated with Mn in hair (r=0.60 and r=0.53, respectively), Mn in toenail (r=0.29 and r=0.37 respectively) and to a lesser extent with Mn in saliva supernatant (r=0.14 and r=0.18, respectively). Mn in whole saliva did not correlate with Mn in water or Mn intake. Both Mn in hair and Mn in toenail allowed to discriminate the most exposed group from the least exposed group, based on Mn in water and Mn intake from water. In this group of children with low level Mn exposure, Mn concentrations in hair, and toenails reflected reasonably well Mn exposure from drinking water, whereas Mn content in saliva correlated less strongly.

A rapid T1 mapping method for assessment of murine kidney viability using dynamic manganese-enhanced magnetic resonance imaging.

PURPOSE: Dynamic manganese-enhanced MRI (MEMRI) allows assessment of tissue viability by tracing manganese uptake. We aimed to develop a rapid T1 mapping method for dynamic MEMRI to facilitate assessments of murine kidney viability. METHODS: A multi-slice saturation recovery fast spin echo (MSRFSE) was developed, validated, and subsequently applied in dynamic MEMRI at 16.4T on ischemic mouse kidneys after 4 weeks of unilateral renal artery stenosis (RAS). Baseline T1 values and post-contrast R1 (1/T1 ) changes were measured in cortex (CO), outer (OSOM), inner (ISOM) strips of outer medulla, and inner medulla (IM). RESULTS: Validation studies showed strong agreement between MSRFSE and an established saturation recovery Look-Locker method. Baseline T1 (s) increased in the stenotic kidney CO (2.10 [1.95-2.56] vs. 1.88 [1.81-2.00], P = 0.0317) and OSOM (2.17 [2.05-2.33] vs. 1.96 [1.87-2.00], P = 0.0075) but remained unchanged in ISOM and IM. This method allowed a temporal resolution of 1.43 min in dynamic MEMRI. Mn2+ uptake and retention decreased in stenotic kidneys, particularly in the OSOM (ΔR1 : 0.48 [0.38-0.56] vs. 0.64 [0.61-0.69] s-1 , P < 0.0001). CONCLUSION: Dynamic MEMRI by MSRFSE detected decreased cellular viability and discerned the regional responses to RAS. This technique may provide a valuable tool for noninvasive evaluation of renal viability. Magn Reson Med 80:190-199, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Simultaneous stabilization/solidification of Mn2+ and NH4+-N from electrolytic manganese residue using MgO and different phosphate resource.

This study examined simultaneous stabilization and solidification (S/S) of Mn2+ and NH4+-N from electrolytic manganese residue (EMR) using MgO and different phosphate resource. The characteristics of EMR NH4+-N and Mn2+ S/S behavior, S/S mechanisms, leaching test and economic analysis, were investigated. The results show that the S/S efficiency of Mn2+ and NH4+-N could reach 91.58% and 99.98%, respectively, and the pH value is 8.75 when the molar ratio of Mg:P is 3:1 and the dose of PM (MgO and Na3PO4·12H2O) is 8wt%. In this process, Mn2+ could mainly be stabilized in the forms of Mn(H2PO4)2·2H2O, Mn3(PO4)2·3H2O, Mn(OH)2, and MnOOH, and NH4+-N in the form of NH4MgPO4·6H2O. Economic evaluation indicates that using PM process has a lower cost than HPM and HOM process for the S/S of Mn2+ and NH4+-N from EMR at the same stabilization agent dose. Leaching test values of all the measured metals are within the permitted level for the GB8978-1996 test suggested when the dose of PM, HPM and HOM is 8wt%.

First-Principles Interaction Analysis Assessment of the Manganese Cation in the Catalytic Activity of Glycosyltransferases.

The energetic effect of water substitution reactions in hexacoordinated [Mn(H2O)6-nLzn]2+nz complexes with L = methanol, formic acid, formamide, formate, imidazole, and diphosphate is quantitatively analyzed at the MP2/triple-ζ level of theory. Subsequently, the state-of-the-art open shell symmetry-adapted perturbation theory (SAPT) analysis of the interaction energies of Mn2+···ligand dimers with selected O-, S-, and N-binding ligands is presented and compared to similar interactions of Mg2+ and Zn2+ ions. We find that the induction energies in the dimers with manganese are almost twice as large as in dimers with magnesium. The total interaction energies rise in the order Mn2+ < Mg2+ < Zn2+. The calculations of the Mn2+ → Mg2+ replacement reaction suggest that metal-dependent glycosyltransferases influence the binding preference of Mn2+ over Mg2+ by inserting amino acids that coordinate the metal via nitrogen or sulfur into their active site.

A greener approach for resource recycling: Manganese bioleaching.

In view of unremitting diminution of mineral resources, rising energy economics along with increasing global consumption of Manganese (Mn), development of environment friendly technologies for tapping alternate sources of Mn has gained importance lately. Mn recovery from mining residues using conventional approaches is extremely expensive due to high capital and energy costs involved. However lean grade ores present in millions of tons awaits the development of competent and cost effective extractive process. Mn recovery by biomining with diverse microbes is thereby recommended as a superior and green alternative to the current pyro metallurgical techniques. The synergistic effects of different factors are known to influence microbial leaching of mineral ores which includes microbiological, mineralogical, physicochemical and process parameters. Bacterial bioleaching is mostly due to enzymatic influence, however fungal bioleaching is non enzymatic. Genomic studies on microbial diversity and an insight of its metabolic pathways provides unique dimension to the mechanism of biomining microorganisms. The extraction of Mn has a massive future prospective and will play a remarkable role in altering the situation of ever-decreasing grades of ore. This review aims to encompass the different aspects of Mn bioleaching, the plethora of organisms involved, the mechanisms driving the process and the recent trends and future prospects of this green technology.

Luminescence and advanced mass spectroscopic characterization of sodium zinc orthophosphate phosphor for low-cost light-emitting diodes.

A new rare-earth-free NaZnPO4:Mn(2+) (NZP:Mn) phosphor powder has been developed by our group and investigated meticulously for the first time using secondary ion mass spectroscopy and chemical imaging techniques. The studies confirmed the effective incorporation of Mn(2+) into the host lattice, resulting in an enhancement of photoluminescence intensity. Phase purity has been verified and structure parameters have been determined successfully by Rietveld refinement studies. The NZP:Mn phosphor powder exhibits strong absorption bands in the ultraviolet and visible (300-470 nm) regions with a significant broad yellow-green (~543 nm) emission due to the characteristic spin forbidden d-d transition ((4)T1→(6)A1) of Mn(2+) ions, indicating weak crystal field strength at the zinc-replaced manganese site. The decay constants are a few milliseconds, which is a pre-requisite for applications in many display devices. The results obtained suggest that this new phosphor powder will find many interesting applications in semiconductor physics, as cost-effective light-emitting diodes (LEDs), as solar cells and in photo-physics.

Microstructures, mechanical properties and cytotoxicity of low cost beta Ti-Mn alloys for biomedical applications.

The microstructures, mechanical properties and biocompatibility of low cost ß-type Ti-(6-18)Mn alloys were investigated after solution treatment. Ti-9 Mn exhibits the best combination of tensile strength and elongation among the fabricated alloys, and its performance is comparable to or superior to those of Ti-6Al-4V ELI (Ti-64 ELI) in terms of every parameter evaluated. A hardness of 338 HV, a Young's modulus of 94 GPa, a 0.2% proof stress of 1023 MPa, an ultimate tensile strength of 1048 MPa and elongation of 19% were obtained for Ti-9 Mn. Furthermore, the cell viability and metallic ion release ratios are comparable to those of commercially pure titanium, making this alloy promising for biomedical applications. The Young's modulus is also lower than that of Ti-64 ELI (110 GPa), which can possibly reduce the stress shielding effect in implanted patients. STATEMENT OF SIGNIFICANCE: This study evaluates mechanical and biological performance of low cost solution treated ß-type Ti-(6, 9, 13 and 18 mass%)Mn alloys. It includes alloys containing a Mn content range higher than most previously published works (which is around or lower than 8 mass%). Furthermore, the effects of the ω phase and the ß phase stability of the alloys over some mechanical properties and microstructures are discussed. Ion release behavior under simulated body fluids and cell viability are also evaluated. For the case of the Ti-9 Mn, a mechanical and biological performance that is comparable to or superior than that of the widely used Ti-6Al-4V ELI and commercially pure Ti was observed.

Determinants of occupational exposure to metals by gas metal arc welding and risk management measures: a biomonitoring study.

Welding fumes contain various toxic metals including chromium (Cr), nickel (Ni) and manganese (Mn). An assessment of the risk to health of local and systemic exposure to welding fumes requires the assessment of both external and internal doses. The aims of this study were to test the relevance in small and medium sized enterprises of a biomonitoring strategy based on urine spot-samples, to characterize the factors influencing the internal doses of metals in gas metal arc welders and to recommend effective risk management measures. 137 welders were recruited and urinary levels of metals were measured by ICP-MS on post-shift samples collected at the end of the working week. Cr, Ni and Mn mean concentrations (respectively 0.43, 1.69 and 0.27 µg/g creatinine) were well below occupational health guidance values, but still higher than background levels observed in the general population, confirming the absorption of metals generated in welding fumes. Both welding parameters (nature of base metal, welding technique) and working conditions (confinement, welding and grinding durations, mechanical ventilation and welding experience) were predictive of occupational exposure. Our results confirm the interest of biomonitoring for assessing health risks and recommending risk management measures for welders.

Physical and biophysical assessment of highly fluorescent, magnetic quantum dots of a wurtzite-phase manganese selenide system.

Combining fluorescence and magnetic features in a non-iron based, select type of quantum dots (QDs) can have immense value in cellular imaging, tagging and other nano-bio interface applications, including targeted drug delivery. Herein, we report on the colloidal synthesis and physical and biophysical assessment of wurtzite-type manganese selenide (MnSe) QDs in cell culture media. Aiming to provide a suitable colloidal system of biological relevance, different concentrations of reactants and ligands (e.g., thioglycolic acid, TGA) have been considered. The average size of the QDs is ∼7 nm, which exhibited a quantum yield of ∼75% as compared to rhodamine 6 G dye(®). As revealed from time-resolved photoluminescence (TR-PL) response, the near band edge emission followed a bi-exponential decay feature with characteristic times of ∼0.64 ns and 3.04 ns. At room temperature, the QDs were found to exhibit paramagnetic features with coercivity and remanence impelled by TGA concentrations. With BSA as a dispersing agent, the QDs showed an improved optical stability in Dulbecco's Modified Eagle Media(®) (DMEM) and Minimum Essential Media(®) (MEM), as compared to the Roswell Park Memorial Institute(®) (RPMI-1640) media. Finally, the cell viability of lymphocytes was found to be strongly influenced by the concentration of MnSe QDs, and had a safe limit upto 0.5 µM. With BSA inclusion in cell media, the cellular uptake of MnSe QDs was observed to be more prominent, as revealed from fluorescence imaging. The fabrication of water soluble, nontoxic MnSe QDs would open up an alternative strategy in nanobiotechnology, while preserving their luminescent and magnetic properties intact.

Economic and environmental characterization of an evolving Li-ion battery waste stream.

While disposal bans of lithium-ion batteries are gaining in popularity, the infrastructure required to recycle these batteries has not yet fully emerged and the economic motivation for this type of recycling system has not yet been quantified comprehensively. This study combines economic modeling and fundamental material characterization methods to quantify economic trade-offs for lithium ion batteries at their end-of-life. Results show that as chemistries transition from lithium-cobalt based cathodes to less costly chemistries, battery recovery value decreases along with the initial value of the raw materials used. For example, manganese-spinel and iron phosphate cathode batteries have potential material values 73% and 79% less than cobalt cathode batteries, respectively. A majority of the potentially recoverable value resides in the base metals contained in the cathode; this increases disassembly cost and time as this is the last portion of the battery taken apart. A great deal of compositional variability exists, even within the same cathode chemistry, due to differences between manufacturers with coefficient of variation up to 37% for some base metals. Cathode changes over time will result in a heavily co-mingled waste stream, further complicating waste management and recycling processes. These results aim to inform disposal, collection, and take-back policies being proposed currently that affect waste management infrastructure as well as guide future deployment of novel recycling techniques.

Manganese cobaltite/polypyrrole nanocomposite-based air-cathode for sustainable power generation in the single-chambered microbial fuel cells.

Manganese cobaltite nanorods (MnCo2O4 NRs) were prepared and tested as potential air-cathode catalyst for the single-chambered microbial fuel cells (sMFC). The power generation of sMFC increases with MnCo2O4 NRs loading to the cathode. The Polypyrrole (PPy) and Vulcan XC were used as conducting support to the MnCo2O4 NRs to form composites either by in situ or by mechanical mixing in the cathode fabrication. The cyclic voltammetry, linear sweep voltammetry and electrochemical impedance studies reveal that the in situ-MnCo2O4 NRs/PPy composite has higher catalytic activity than that of mechanically mixed-MnCo2O4NRs/PPy composite because of higher interfacial contact between MnCo2O4 NRs and PPy. The maximum volumetric power density with in situ-MnCo2O4 NRs/PPy, mechanically mixed-MnCo2O4 NRs/PPy, MnCo2O4 NRs/Vulcan XC and catalyst-free (only Vulcan XC) cathode was measured to be 6.11, 5.05, 4.22, and 1.77 W/m(3), respectively, in the sMFC. This suggests that PPy is not only a better conducting support than that of conventionally used Vulcan XC but also the cathode composite fabrication process is important for enhanced performance. The synergetic effect of MnCo2O4 NRs and PPy was found to play an important role for the improved energy recovery and it could be applied as an efficient and inexpensive cathode catalyst for the sMFC.

Bonner sphere measurements of 241Am-B and 241Am-F neutron energy spectra unfolded using high-resolution a priori data.

High-resolution neutron energy spectra, covering the entire energy range of interest, for two standard radionuclide neutron sources ((241)Am-B and (241)Am-F) have been derived from Bonner sphere measurements by using high-resolution a priori data in the unfolding process. In each case, two a priori spectra were used, one from a two-stage calculation and also one from a combination of the calculated spectrum with a high-resolution measured spectrum. The unfolded spectra are compared with those published elsewhere and show significant differences from the ISO- and IAEA-recommended spectra for (241)Am-B and (241)Am-F, respectively. Values for the fluence-average energy and fluence-to-dose-equivalent conversion coefficients are presented for the new spectra, and the implications of the new spectra for the emission rates of the sources when measured by the manganese bath technique are also determined.