► A new Bayesian inference based two-stage support vector regression approach. ► Strong ability to identify and reconcile biased measurements under uncertainty. ► High accuracy and robustness for ...soft sensor predictions in batch bioprocess. ► Improved performance than SVR method in handling process uncertainty. ► Applied to fed-batch penicillin cultivation process with satisfactory results.
Inherent process and measurement uncertainty has posed a challenging issue on soft sensor development of batch bioprocesses. In this paper, a new soft sensor modeling framework is proposed by integrating Bayesian inference strategy with two-stage support vector regression (SVR) method. The Bayesian inference procedure is first designed to identify measurement biases and misalignments via posterior probabilities. Then the biased input measurements are calibrated through Bayesian estimation and the first-stage SVR model is thus built for output measurement reconciliation. The inferentially calibrated input and output data can be further used to construct the second-stage SVR model, which serves as the main model of soft sensor to predict new output measurements. The Bayesian inference based two-stage support vector regression (BI-SVR) approach is applied to a fed-batch penicillin cultivation process and the obtained soft sensor performance is compared to that of the conventional SVR method. The results from two test cases with different levels of measurement uncertainty show significant improvement of the BI-SVR approach over the regular SVR method in predicting various output measurements.
Abstract
Na-ion cathode materials operating at high voltage with a stable cycling behavior are needed to develop future high-energy Na-ion cells. However, the irreversible oxygen redox reaction at ...the high-voltage region in sodium layered cathode materials generates structural instability and poor capacity retention upon cycling. Here, we report a doping strategy by incorporating light-weight boron into the cathode active material lattice to decrease the irreversible oxygen oxidation at high voltages (i.e., >4.0 V vs. Na
+
/Na). The presence of covalent B–O bonds and the negative charges of the oxygen atoms ensures a robust ligand framework for the NaLi
1/9
Ni
2/9
Fe
2/9
Mn
4/9
O
2
cathode material while mitigating the excessive oxidation of oxygen for charge compensation and avoiding irreversible structural changes during cell operation. The B-doped cathode material promotes reversible transition metal redox reaction enabling a room-temperature capacity of 160.5 mAh g
−1
at 25 mA g
−1
and capacity retention of 82.8% after 200 cycles at 250 mA g
−1
. A 71.28 mAh single-coated lab-scale Na-ion pouch cell comprising a pre-sodiated hard carbon-based anode and B-doped cathode material is also reported as proof of concept.
Replacement of CC unit with its isoelectronic BN unit in aromatics provides a new class of molecules with appealing properties, which have attracted great attention recently. In this Concept, we ...focus on BN‐substituted polycyclic aromatics with fused structures, and review their synthesis, photophysical, and redox properties, as well as their applications in organic electronics. We also present challenging synthetic targets, large BN‐ substituted polycyclic aromatics, such as regioregular BN heterosuperbenzenes, which can be viewed as BN‐doped nanographenes. Finally, we propose an atomically precise bottom‐up synthesis of structurally well‐defined BN‐doped graphenes.
A new super hero! BN substitution in aromatic systems could provide a new family of interesting compounds. In this Concept, the development of BN‐substituted polycyclic aromatics is reported, and their synthesis, properties and electronic applications are summarized. From monocyclic BN‐substituted benzene to polycyclic BN heteroaromatics (like BN heterosuperbenzene), the possible ways to structurally well‐defined BN‐doped graphenes are proposed.
Sodium‐ion batteries have gained much attention for their potential application in large‐scale stationary energy storage due to the low cost and abundant sodium sources in the earth. However, the ...electrochemical performance of sodium‐ion full cells (SIFCs) suffers severely from the irreversible consumption of sodium ions of cathode during the solid electrolyte interphase (SEI) formation of hard carbon anode. Here, a high‐efficiency cathode sodiation compensation reagent, sodium oxalate (Na2C2O4), which possesses both a high theoretical capacity of 400 mA h g−1 and a capacity utilization as high as 99%, is proposed. The implementation of Na2C2O4 as sacrificial sodium species is successfully realized by decreasing its oxidation potential from 4.41 to 3.97 V through tuning conductive additives with different physicochemical features, and the corresponding mechanism of oxidation potential manipulation is analyzed. Electrochemical results show that in the full cell based on a hard carbon anode and a P2‐Na2/3Ni1/3Mn1/3Ti1/3O2 cathode with Na2C2O4 as a sodium reservoir to compensate for sodium loss during SEI formation, the capacity retention is increased from 63% to 85% after 200 cycles and the energy density is improved from 129.2 to 172.6 W h kg−1. This work can provide a new avenue for accelerating the development of SIFCs.
The development of sodium‐ion batteries has been hindered so far by the irreversible consumption of sodium ions of the cathode during the solid electrolyte interphase formation. Therefore, in search of a safe, cost‐effective, and highly efficient cathode sodiation reagent, the feasibility of Na2C2O4 as a sodium reservoir source for enhancing the performance of sodium‐ion batteries is investigated.
Chemical modification of electrode materials by heteroatom dopants is crucial for improving storage performance in rechargeable batteries. Electron configurations of different dopants significantly ...influence the chemical interactions inbetween and the chemical bonding with the host material, yet the underlying mechanism remains unclear. We revealed competitive doping chemistry of Group IIIA elements (boron and aluminum) taking nickel‐rich cathode materials as a model. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen. Density functional theory calculations reveal, Al is preferentially bonded to oxygen and vice versa, and shows a much lower diffusion barrier than BIII. In the case of Al‐preoccupation, the bulk diffusion of BIII is hindered. In this way, a B‐rich surface and Al‐rich bulk is formed, which helps to synergistically stabilize the structural evolution and surface chemistry of the cathode.
A model study has been performed on Group IIIA element (boron and aluminum) co‐doped high‐nickel layered oxide cathode materials to understand competitive doping chemistry. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen, resulting in the formation of a B‐rich surface and an Al‐rich bulk.
Layered transition metal oxide P2‐Na2/3Ni1/3Mn2/3O2 usually suffers from large‐volume phase transitions and different Na‐vacancy ordering during sodium (de)intercalation, incurring rapid capacity ...decline and poor rate capability. Herein, an effective strategy based on synergetic effect of selected multiple metal ions is designed for P2‐type cathodes with improved performance. The role of tetravalent titanium provides high redox potential, inactive divalent magnesium stabilizes the structure, and the monovalent lithium smooths the electrochemical curves. The combined analysis of in operando X‐ray diffraction, in operando X‐ray absorption spectroscopy and density functional theory calculations demonstrates the contribution of multi‐metal ions converts the unfavorable and large‐volume P2 to O2 transition into a moderate “Z”‐intergrowth structure by increasing the energy barrier of transition metal slab gliding. As a consequence, the resultant P2‐Na0.7Li0.03Mg0.03Ni0.27Mn0.6Ti0.07O2 electrode delivers a reversible capacity of 134 mAh g−1, a working voltage of 3.57 V, excellent cycling stability (82% of capacity retention after 200 cycles), and superior rate performance (110 mAh g−1 at 4 C). Full cells fabricated with a hard carbon anode achieve an energy density of 296 Wh kg−1. This study presents a route to rationally design cathode materials with this functionalization to improve the cell performance for sodium‐ion batteries.
Herein, a co‐substitution strategy is proposed for P2‐Na2/3Ni1/3Mn2/3O2 to realize high‐energy sodium‐ion batteries. On account of the synergetic effects of Li+ (suppressing Na‐vacancy ordering), Ti4+ (increasing redox potential), and Mg2+ (stabilizing structure), the as‐obtained Na0.7Li0.03Mg0.03Ni0.27Mn0.6Ti0.07O2 electrode demonstrates moderate phase transition behavior and superior electrochemical performance.
Mitofusin-2 (MFN2) is a dynamin-like GTPase that plays a central role in regulating mitochondrial fusion and cell metabolism. Mutations in MFN2 cause the neurodegenerative disease Charcot-Marie-Tooth ...type 2A (CMT2A). The molecular basis underlying the physiological and pathological relevance of MFN2 is unclear. Here, we present crystal structures of truncated human MFN2 in different nucleotide-loading states. Unlike other dynamin superfamily members including MFN1, MFN2 forms sustained dimers even after GTP hydrolysis via the GTPase domain (G) interface, which accounts for its high membrane-tethering efficiency. The biochemical discrepancy between human MFN2 and MFN1 largely derives from a primate-only single amino acid variance. MFN2 and MFN1 can form heterodimers via the G interface in a nucleotide-dependent manner. CMT2A-related mutations, mapping to different functional zones of MFN2, lead to changes in GTP hydrolysis and homo/hetero-association ability. Our study provides fundamental insight into how mitofusins mediate mitochondrial fusion and the ways their disruptions cause disease.
► A particle filter driven dynamic Gaussian mixture model is developed. ► Particle filtered Bayesian inference probability index for fault detection. ► Particle filtered Bayesian contribution ...decomposition for fault diagnosis. ► Superior capability in handling dynamic operating scenario changes in processes.
Complex non-Gaussian processes may have dynamic operation scenario shifts so that the conventional monitoring methods become ill-suited. In this article, a new particle filter based dynamic Gaussian mixture model (DGMM) is developed by adopting particle filter re-sampling method to update the mixture model parameters in a dynamic fashion. Then the particle filtered Bayesian inference probability index is established for process fault detection. Furthermore, the particle filtered Bayesian inference contributions are decomposed among different process variables for fault diagnosis. The proposed DGMM monitoring approach is applied to the Tennessee Eastman Chemical process with dynamic mode changes and the results show its superiority to the dynamic principal component analysis (DPCA) and regular Gaussian mixture model (GMM) in terms of fault detection and diagnosis accuracy.
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