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1.
Bioresour Technol ; 332: 125083, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33826983

RESUMEN

Electron donors have been widely used to improve denitrification performance. However, it is controversial which electron donor could be chosen. In this study, three electron donors were used to improve nitrogen removal from ecological floating beds (EFBs). The results showed that TN removal efficiency was 49-80%, 46-81%, and 45-79% in EFB-C (sodium acetate), EFB-S (sodium thiosulfate), EFB-Fe (iron scraps), respectively. Nitrification was limited in EFB-C and EFB-S while denitrification in EFB-Fe. The TN removal in the three EFBs were almost equivalent when HRT was 3 days. Lowest CH4 and N2O emissions were measured in EFB-Fe. Nitrifying and denitrifying bacteria were mainly concentrated in the root rhizospheres while iron cycle related and anammox bacteria were mainly concentrated on iron scraps surface. Heterotrophic denitrification and autotrophic denitrification were mainly attributed to TN removal in EFB-C and EFB-S, respectively. Autotrophic, heterotrophic denitrification and anammox contributed to TN removal in EFB-Fe.


Asunto(s)
Reactores Biológicos , Desnitrificación , Electrones , Nitrificación , Nitrógeno
2.
Bioresour Technol ; 332: 125100, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33838453

RESUMEN

To investigate how the seed microbial community structure affects the improvement of methanogenesis efficiency through direct interspecies electron transfer (DIET), a biomethane potential (BMP) test was conducted using sludge collected from a total of six anaerobic digesters. DIET-stimulating microbial populations were investigated by 16S rRNA gene sequence analysis. Correlations between microbial community composition and methane production performance by DIET were analyzed. The methane production rate increased under all conditions when granular activated carbon (GAC) was injected regardless of the inoculum type. However, redundancy analysis indicated a significant correlation between the inoculum microbial community and lag time. In a network analysis, Methanolinea species distributed in the inocula formed a single modularity with lag time, suggesting that the methanogens in the inocula might reduce the lag time of methanogenesis through DIET. Overall, this study revealed that the inoculum microbial community composition is an important factor affecting methane production efficiency by DIET.


Asunto(s)
Metano , Microbiota , Anaerobiosis , Reactores Biológicos , Transporte de Electrón , Electrones , ARN Ribosómico 16S/genética
3.
Molecules ; 26(5)2021 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-33800777

RESUMEN

Vanadium phosphate positive electrode materials attract great interest in the field of Alkali-ion (Li, Na and K-ion) batteries due to their ability to store several electrons per transition metal. These multi-electron reactions (from V2+ to V5+) combined with the high voltage of corresponding redox couples (e.g., 4.0 V vs. for V3+/V4+ in Na3V2(PO4)2F3) could allow the achievement the 1 kWh/kg milestone at the positive electrode level in Alkali-ion batteries. However, a massive divergence in the voltage reported for the V3+/V4+ and V4+/V5+ redox couples as a function of crystal structure is noticed. Moreover, vanadium phosphates that operate at high V3+/V4+ voltages are usually unable to reversibly exchange several electrons in a narrow enough voltage range. Here, through the review of redox mechanisms and structural evolutions upon electrochemical operation of selected widely studied materials, we identify the crystallographic origin of this trend: the distribution of PO4 groups around vanadium octahedra, that allows or prevents the formation of the vanadyl distortion (O…V4+=O or O…V5+=O). While the vanadyl entity massively lowers the voltage of the V3+/V4+ and V4+/V5+ couples, it considerably improves the reversibility of these redox reactions. Therefore, anionic substitutions, mainly O2- by F-, have been identified as a strategy allowing for combining the beneficial effect of the vanadyl distortion on the reversibility with the high voltage of vanadium redox couples in fluorine rich environments.


Asunto(s)
Álcalis/química , Suministros de Energía Eléctrica , Electrodos , Electrones , Fosfatos/química , Vanadio/química , Electroquímica , Oxidación-Reducción
4.
Int J Mol Sci ; 22(6)2021 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-33805783

RESUMEN

In anaerobic bioreactors, the electrons produced during the oxidation of organic matter can potentially be used for the biological reduction of pharmaceuticals in wastewaters. Common electron transfer limitations benefit from the acceleration of reactions through utilization of redox mediators (RM). This work explores the potential of carbon nanomaterials (CNM) as RM on the anaerobic removal of ciprofloxacin (CIP). Pristine and tailored carbon nanotubes (CNT) were first tested for chemical reduction of CIP, and pristine CNT was found as the best material, so it was further utilized in biological anaerobic assays with anaerobic granular sludge (GS). In addition, magnetic CNT were prepared and also tested in biological assays, as they are easier to be recovered and reused. In biological tests with CNM, approximately 99% CIP removal was achieved, and the reaction rates increased ≈1.5-fold relatively to the control without CNM. In these experiments, CIP adsorption onto GS and CNM was above 90%. Despite, after applying three successive cycles of CIP addition, the catalytic properties of magnetic CNT were maintained while adsorption decreased to 29 ± 3.2%, as the result of CNM overload by CIP. The results suggest the combined occurrence of different mechanisms for CIP removal: adsorption on GS and/or CNM, and biological reduction or oxidation, which can be accelerated by the presence of CNM. After biological treatment with CNM, toxicity towards Vibrio fischeri was evaluated, resulting in ≈ 46% detoxification of CIP solution, showing the advantages of combining biological treatment with CNM for CIP removal.


Asunto(s)
Ciprofloxacino/metabolismo , Electrones , Nanopartículas de Magnetita/química , Nanotubos de Carbono/química , Aguas del Alcantarillado/microbiología , Contaminantes Químicos del Agua/metabolismo , Adsorción , Aliivibrio fischeri/efectos de los fármacos , Aliivibrio fischeri/crecimiento & desarrollo , Anaerobiosis/fisiología , Biodegradación Ambiental , Reactores Biológicos , Ciprofloxacino/aislamiento & purificación , Humanos , Nanopartículas de Magnetita/ultraestructura , Methanobacterium/metabolismo , Methanobrevibacter/metabolismo , Methanosarcinales/metabolismo , Methanospirillum/metabolismo , Pruebas de Sensibilidad Microbiana , Nanotubos de Carbono/ultraestructura , Oxidación-Reducción , Contaminantes Químicos del Agua/aislamiento & purificación
5.
Nat Commun ; 12(1): 2079, 2021 04 06.
Artículo en Inglés | MEDLINE | ID: mdl-33824320

RESUMEN

Human manganese superoxide dismutase is a critical oxidoreductase found in the mitochondrial matrix. Concerted proton and electron transfers are used by the enzyme to rid the mitochondria of O2•-. The mechanisms of concerted transfer enzymes are typically unknown due to the difficulties in detecting the protonation states of specific residues and solvent molecules at particular redox states. Here, neutron diffraction of two redox-controlled manganese superoxide dismutase crystals reveal the all-atom structures of Mn3+ and Mn2+ enzyme forms. The structures deliver direct data on protonation changes between oxidation states of the metal. Observations include glutamine deprotonation, the involvement of tyrosine and histidine with altered pKas, and four unusual strong-short hydrogen bonds, including a low barrier hydrogen bond. We report a concerted proton and electron transfer mechanism for human manganese superoxide dismutase from the direct visualization of active site protons in Mn3+ and Mn2+ redox states.


Asunto(s)
Electrones , Protones , Superóxido Dismutasa/metabolismo , Aminoácidos/metabolismo , Aniones , Biocatálisis , Dominio Catalítico , Glutamina/metabolismo , Humanos , Ligandos , Neutrones , Multimerización de Proteína , Solventes , Superóxido Dismutasa/química
6.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(2): 163-166, 2021 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-33825375

RESUMEN

In order to adapt to different target shapes and protect the surrounding normal tissues, the design of two-dimensional electron beam radiotherapy planning requires additional lead blocks. But the Pinnacle treatment planning system can not directly shape the lead block conformity to the size of the beam field given by the doctor. Every time, physicists need to manually drag the lead block to form the required beam field. When meeting a two-dimensional electron beam treatment planning with the same field parameters as before, physicists need to rearrange the field for dose calculation, which greatly reduces the design efficiency of the two-dimensional electron beam treatment planning. In this study, we independently developed a two-dimensional electron beam radiotherapy planning system based on Qt Creator. The system can quickly design a two-dimensional electron beam radiotherapy plan, which reduces the repeated work of physicists.


Asunto(s)
Electrones , Planificación de la Radioterapia Asistida por Computador , Dosificación Radioterapéutica
7.
Sensors (Basel) ; 21(8)2021 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-33917742

RESUMEN

Positron emission tomography (PET) is a functional non-invasive imaging modality that uses radioactive substances (radiotracers) to measure changes in metabolic processes. Advances in scanner technology and data acquisition in the last decade have led to the development of more sophisticated PET devices with good spatial resolution (1-3 mm of full width at half maximum (FWHM)). However, there are involuntary motions produced by the patient inside the scanner that lead to image degradation and potentially to a misdiagnosis. The adverse effect of the motion in the reconstructed image increases as the spatial resolution of the current scanners continues improving. In order to correct this effect, motion correction techniques are becoming increasingly popular and further studied. This work presents a simulation study of an image motion correction using a frame-based algorithm. The method is able to cut the acquired data from the scanner in frames, taking into account the size of the object of study. This approach allows working with low statistical information without losing image quality. The frames are later registered using spatio-temporal registration developed in a multi-level way. To validate these results, several performance tests are applied to a set of simulated moving phantoms. The results obtained show that the method minimizes the intra-frame motion, improves the signal intensity over the background in comparison with other literature methods, produces excellent values of similarity with the ground-truth (static) image and is able to find a limit in the patient-injected dose when some prior knowledge of the lesion is present.


Asunto(s)
Electrones , Procesamiento de Imagen Asistido por Computador , Algoritmos , Humanos , Movimiento (Física) , Movimiento , Fantasmas de Imagen , Tomografía de Emisión de Positrones
8.
Int J Mol Sci ; 22(6)2021 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-33808887

RESUMEN

We investigate dissociative electron attachment to tirapazamine through a crossed electron-molecule beam experiment and quantum chemical calculations. After the electron is attached and the resulting anion reaches the first excited state, D1, we suggest a fast transition into the ground electronic state through a conical intersection with a distorted triazine ring that almost coincides with the minimum in the D1 state. Through analysis of all observed dissociative pathways producing heavier ions (90-161 u), we consider the predissociation of an OH radical with possible roaming mechanism to be the common first step. This destabilizes the triazine ring and leads to dissociation of highly stable nitrogen-containing species. The benzene ring is not altered during the process. Dissociation of small anionic fragments (NO2-, CN2-, CN-, NH2-, O-) cannot be conclusively linked to the OH predissociation mechanism; however, they again do not require dissociation of the benzene ring.


Asunto(s)
Electrones , Tirapazamina/química , Algoritmos , Aniones/química , Modelos Químicos , Fármacos Sensibilizantes a Radiaciones/química
9.
J Environ Manage ; 287: 112294, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33714046

RESUMEN

A novel heteroatomic N, P and S co-doped core-shell material (MnFe3O4@PZS) was synthesized by a simple polycondensation hydro-thermal method, and used as the cathode to cooperate with electron-catalysis to activate persulfate (S2O82-) (E-MnFe3O4@PZS-PDS) for tetracycline (TTC) degradation. Radical scavenger studies demonstrated that non-radicals including atomic H* and singlet oxygen (1O2) rather than sulfate and hydroxyl radicals were the crucial reactive oxygen species (ROS). Electrochemical analysis indicated that Mn doping could promote electro-catalytic process via diverting pathway from four/two-electron to one-electron to generate non-radical H*/1O2 at the cathode, including one-electron oxygen reduction reaction (1e-ORR) (O2→1O2), and one-electron hydrogen reduction reaction (1e-HRR) (H2O+e-→H∗), as evidenced by the lowest onset potential (0.072 V) together with electron transfer number (n = 1.65). Besides, the regeneration/reduction of FeⅡ/Ⅲ/MnⅡ/Ⅲ/Ⅳ and persulfate will not cause excessive consumption of electron and chemicals due to that could directly get the electron individually from the cathode and anode, and finally TTC could be completely degraded with low energy consumption (0.655 kWh m-3). This study provides new insights into the direct single electron activating PDS to produce non-radical H*/1O2 via core-shell catalytic MnFe3O4@PZS, and displays a promising application in wastewater treatment.


Asunto(s)
Electrones , Purificación del Agua , Catálisis , Electrodos , Oxidación-Reducción , Tetraciclina
10.
Int J Mol Sci ; 22(5)2021 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-33652878

RESUMEN

The incorporation of modified uracil derivatives into DNA leads to the formation of radical species that induce DNA damage. Molecules of this class have been suggested as radiosensitizers and are still under investigation. In this study, we present the results of dissociative electron attachment to uracil-5-yl O-(N,N-dimethylsulfamate) in the gas phase. We observed the formation of 10 fragment anions in the studied range of electron energies from 0-12 eV. Most of the anions were predominantly formed at the electron energy of about 0 eV. The fragmentation paths were analogous to those observed in uracil-5-yl O-sulfamate, i.e., the methylation did not affect certain bond cleavages (O-C, S-O and S-N), although relative intensities differed. The experimental results are supported by quantum chemical calculations performed at the M06-2X/aug-cc-pVTZ level of theory. Furthermore, a resonance stabilization method was used to theoretically predict the resonance positions of the fragment anions O- and CH3-.


Asunto(s)
Fármacos Sensibilizantes a Radiaciones/química , Algoritmos , Estabilidad de Medicamentos , Electrones , Gases/química , Metilación , Modelos Moleculares
11.
Int J Mol Sci ; 22(4)2021 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-33670770

RESUMEN

The new organic-inorganic compound (C6H9N2)2BiCl5 (I) has been grown by the solvent evaporation method. The one-dimensional (1D) structure of the allylimidazolium chlorobismuthate (I) has been determined by single crystal X-ray diffraction. It crystallizes in the centrosymmetric space group C2/c and consists of 1-allylimidazolium cations and (1D) chains of the anion BiCl52-, built up of corner-sharing [BiCl63-] octahedra which are interconnected by means of hydrogen bonding contacts N/C-H⋯Cl. The intermolecular interactions were quantified using Hirshfeld surface analysis and the enrichment ratio established that the most important role in the stability of the crystal structure was provided by hydrogen bonding and H···H interactions. The highest value of E was calculated for the contact N⋯C (6.87) followed by C⋯C (2.85) and Bi⋯Cl (2.43). These contacts were favored and made the main contribution to the crystal packing. The vibrational modes were identified and assigned by infrared and Raman spectroscopy. The optical band gap (Eg = 3.26 eV) was calculated from the diffuse reflectance spectrum and showed that we can consider the material as a semiconductor. The density functional theory (DFT) has been used to determine the calculated gap, which was about 3.73 eV, and to explain the electronic structure of the title compound, its optical properties, and the stability of the organic part by the calculation of HOMO and LUMO energy and the Fukui indices.


Asunto(s)
Bismuto/química , Electrones , Compuestos Orgánicos/química , Compuestos Orgánicos/síntesis química , Análisis Espectral , Cristalografía por Rayos X , Teoría Funcional de la Densidad , Enlace de Hidrógeno , Conformación Molecular , Refractometría , Espectrofotometría Ultravioleta , Espectrometría Raman , Temperatura , Vibración
12.
Molecules ; 26(4)2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33670107

RESUMEN

For decades one has strived to synthesize a compound with the longest covalent C-C bond applying predominantly steric hindrance and/or strain to achieve this goal. On the other hand electronic effects have been added to the repertoire, such as realized in the electron deficient ethane radical cation in its D3d form. Recently, negative hyperconjugation effects occurring in diamino-o-carborane analogs such as di-N,N-dimethylamino-o-carborane have been held responsible for their long C-C bonds. In this work we systematically analyzed CC bonding in a diverse set of 53 molecules including clamped bonds, highly sterically strained complexes such as diamondoid dimers, electron deficient species, and di-N,N-dimethylamino-o-carborane to cover the whole spectrum of possibilities for elongating a covalent C-C bond to the limit. As a quantitative intrinsic bond strength measure, we utilized local vibrational CC stretching force constants ka(CC) and related bond strength orders BSO n(CC), computed at the ωB97X-D/aug-cc-pVTZ level of theory. Our systematic study quantifies for the first time that whereas steric hindrance and/or strain definitely elongate a C-C bond, electronic effects can lead to even longer and weaker C-C bonds. Within our set of molecules the electron deficient ethane radical cation, in D3d symmetry, acquires the longest C-C bond with a length of 1.935 Å followed by di-N,N-dimethylamino-o-carborane with a bond length of 1.930 Å. However, the C-C bond in di-N,N-dimethylamino-o-carborane is the weakest with a BSO n value of 0.209 compared to 0.286 for the ethane radical cation; another example that the longer bond is not always the weaker bond. Based on our findings we provide new guidelines for the general characterization of CC bonds based on local vibrational CC stretching force constants and for future design of compounds with long C-C bonds.


Asunto(s)
Carbono/química , Modelos Moleculares , Vibración , Electrones , Enlace de Hidrógeno , Teoría Cuántica
13.
Molecules ; 26(4)2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33670175

RESUMEN

A range of solution-processed organic and hybrid organic-inorganic solar cells, such as dye-sensitized and bulk heterojunction organic solar cells have been intensely developed recently. TiO2 is widely employed as electron transporting material in nanostructured TiO2 perovskite-sensitized solar cells and semiconductor in dye-sensitized solar cells. Understanding the optical and electronic mechanisms that govern charge separation, transport and recombination in these devices will enhance their current conversion efficiencies under illumination to sunlight. In this work, density functional theory with Perdew-Burke Ernzerhof (PBE) functional approach was used to explore the optical and electronic properties of three modeled TiO2 brookite clusters, (TiO2)n=5,8,68. The simulated optical absorption spectra for (TiO2)5 and (TiO2)8 clusters show excitation around 200-400 nm, with (TiO2)8 cluster showing higher absorbance than the corresponding (TiO2)5 cluster. The density of states and the projected density of states of the clusters were computed using Grid-base Projector Augmented Wave (GPAW) and PBE exchange correlation functional in a bid to further understand their electronic structure. The density of states spectra reveal surface valence and conduction bands separated by a band gap of 1.10, 2.31, and 1.37 eV for (TiO2)5, (TiO2)8, and (TiO2)68 clusters, respectively. Adsorption of croconate dyes onto the cluster shifted the absorption peaks to higher wavelengths.


Asunto(s)
Teoría Funcional de la Densidad , Nanoestructuras/química , Energía Solar , Titanio/química , Adsorción , Compuestos de Calcio/química , Suministros de Energía Eléctrica , Electrónica , Electrones , Óptica y Fotónica/tendencias , Óxidos/química , Luz Solar
14.
Molecules ; 26(4)2021 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-33673291

RESUMEN

Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X2-azulene ligands (X = H, Me, CO2Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)5Cr(2-isocyano-1,3-X2-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime "workhorse" aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr-CNAz bond distances}, cyclic voltametric {E1/2(Cr0/1+)}, 13C NMR {δ(13CN), δ(13CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {νN≡C, νC≡O, kC≡O} analyses of the [(OC)5Cr(2-isocyano-1,3-X2-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ(13COtrans) vs. δ(13CN), δ(13COcis) vs. δ(13CN), and δ(13COtrans) vs. kC≡O,trans force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC6F5 and CNC2F3.


Asunto(s)
Cianuros/química , Electrones , Compuestos Heterocíclicos/química , Isotiocianatos/química , Azulenos/química , Cristalografía por Rayos X , Ligandos , Espectroscopía de Resonancia Magnética , Metales/química , Modelos Moleculares , Estructura Molecular
15.
AJR Am J Roentgenol ; 216(5): 1222-1228, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33760655

RESUMEN

OBJECTIVE. At its advent, CT was too slow to image the heart. Temporal resolution improved with electron beam CT (EBCT); subsequently, the heart could be imaged, eventually leading to the discovery of prognostic information obtained from the coronary calcium score. In the early 2000s, EBCT was replaced by MDCT. In this review, we discuss the rise and fall of EBCT and explore its legacy in cardiac imaging. CONCLUSION. Although MDCT rendered EBCT obsolete, EBCT leaves a legacy in cardiac imaging regarding both diagnosis and prognosis. The creators of MDCT emulated the strengths of EBCT and learned from its weaknesses. Moreover, EBCT showed that imaging surrogates can predict outcomes, and the origins of substrate-guided treatment can be traced to EBCT.


Asunto(s)
Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Electrones , Corazón/diagnóstico por imagen , Humanos
16.
J Vis Exp ; (169)2021 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-33779618

RESUMEN

A detailed protocol for preparing small molecule samples for microcrystal electron diffraction (MicroED) experiments is described. MicroED has been developed to solve structures of proteins and small molecules using standard electron cryo-microscopy (cryo-EM) equipment. In this way, small molecules, peptides, soluble proteins, and membrane proteins have recently been determined to high resolutions. Protocols are presented here for preparing grids of small-molecule pharmaceuticals using the drug carbamazepine as an example. Protocols for screening and collecting data are presented. Additional steps in the overall process, such as data integration, structure determination, and refinement are presented elsewhere. The time required to prepare the small-molecule grids is estimated to be less than 30 min.


Asunto(s)
Microscopía por Crioelectrón/métodos , Electrones
17.
Nat Commun ; 12(1): 1672, 2021 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-33723266

RESUMEN

X-ray free-electron lasers (XFELs) enable obtaining novel insights in structural biology. The recently available MHz repetition rate XFELs allow full data sets to be collected in shorter time and can also decrease sample consumption. However, the microsecond spacing of MHz XFEL pulses raises new challenges, including possible sample damage induced by shock waves that are launched by preceding pulses in the sample-carrying jet. We explored this matter with an X-ray-pump/X-ray-probe experiment employing haemoglobin microcrystals transported via a liquid jet into the XFEL beam. Diffraction data were collected using a shock-wave-free single-pulse scheme as well as the dual-pulse pump-probe scheme. The latter, relative to the former, reveals significant degradation of crystal hit rate, diffraction resolution and data quality. Crystal structures extracted from the two data sets also differ. Since our pump-probe attributes were chosen to emulate EuXFEL operation at its 4.5 MHz maximum pulse rate, this prompts concern about such data collection.


Asunto(s)
Hemoglobinas/química , Hemoglobinas/efectos de la radiación , Inyecciones a Chorro/métodos , Rayos Láser , Cristalografía por Rayos X , Electrones , Humanos , Inyecciones a Chorro/instrumentación , Técnicas de Sonda Molecular , Rayos X
18.
Bioresour Technol ; 330: 124965, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33735725

RESUMEN

With the increasing of data in wastewater treatment, data-driven machine learning models are useful for modeling biological processes and complex reactions. However, few data-driven models have been developed for simulating the microbial electrolysis cells (MECs) and traditional models are too ambiguous to comprehend the mechanisms. In this study, a new general data-driven two-stage model was firstly developed to predict CH4 production from in-situ biogas upgrading in the biocathode MECs via direct electron transfer (DET), named NARX-BP hybrid neural networks. Compared with traditional one-stage model, the model could well predict methane production via DET with excellent performance (all R2 and MES of 0.918 and 6.52 × 10-2, respectively) and reveal the mechanisms of biogas upgrading, for the new systematical modeling approach could improve the versatility and applicability by inputting significant intermediate variables. In addition, the model is generally available to support long-term prediction and optimal operation for anaerobic digestion or complex MEC systems.


Asunto(s)
Biocombustibles , Metano , Anaerobiosis , Reactores Biológicos , Electrólisis , Electrones , Aprendizaje Automático , Redes Neurales de la Computación
19.
Bioresour Technol ; 330: 124980, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33743275

RESUMEN

The role of direct interspecies electron transfer (DIET) on enhancement of methanogenesis has been studied. This mini-review updated the current researches on the potential role of DIET on enhanced performance for anaerobic digestion of organic substrates with effective strategies implemented. Since most experimental observations correlated with the DIET mechanism are yet to be consolidated, this article categorized and discussed the current experimental observations supporting DIET mechanism for methanogenesis, mainly based on those with supplement of carbon materials, from which the prospects and challenges for further studies to confirm the role of DIET in anaerobic digestion processes were highlighted.


Asunto(s)
Electrones , Metano , Anaerobiosis , Reactores Biológicos , Carbono , Transporte de Electrón
20.
Bioresour Technol ; 330: 124968, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33744733

RESUMEN

The down flow structured bed bioreactor (DFSBR) was applied to treat synthetic acid mine drainage (AMD) to reduce sulfate, increase the pH and precipitate metals in solutions (Co, Cu, Fe, Mn, Ni and Zn) using vinasse as an electron donor for sulfate-reducing bacteria (SRB). DFSBR achieved sulfate removal efficiencies between 55 and 91%, removal of Co and Ni were obtained with efficiencies greater than 80%, while Fe, Zn, Cu and Mn were removed with average efficiencies of 70, 80, 73 and 60%, respectively. Sulfate reduction increased pH from moderately acidic to 6.7-7.5. Modelling data confirmed the experimental results and metal sulfide precipitation was the mainly responsible for metal removal. The main genera responsible for sulfate and metal reduction were Geobacter and Desulfovibrio while fermenters were Parabacteroides and Sulfurovum. Moreover, in syntrophism with SRB, they played an important role in the efficiency of metal and sulfate removal.


Asunto(s)
Microbiota , Saccharum , Reactores Biológicos , Electrones , Concentración de Iones de Hidrógeno , Sulfatos
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