Monthly Archives: September 2023

Monitoring Rheological Changes Using Acoustic Emissions for Complex Formulated Fluids Manufacturing

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Monitoring Rheological Changes Using Acoustic Emissions for Complex Formulated Fluids Manufacturing

Passive acoustic emissions were detected by a new rheometric device to monitor the manufacture and rheological changes of complex fluids, live and in situ; a simplified output was then transferred to machine learning algorithms. Power-law and Herschel-Bulkley model fluids were studied on the laboratory and pilot scales. Offline rheometry was used to validate the obtained rheological properties.


Abstract

The measurement capabilities of a newly developed in-situ rheometric device based on a single passive acoustic emission sensor and machine learning algorithms were investigated. Two surfactant structured fluids demonstrating complex non-Newtonian rheology (Power-law and Herschel-Bulkley models) were examined. Furthermore, a static evaluation on the laboratory scale in comparison to dynamic processing on the pilot scale was conducted. The results indicate that the machine learning algorithms of this technology can identify, in > 90 % of scenarios, the correct type of rheology or the manufacturing process step across both scales. This identification is based on solving a classification problem using quadratic support vector machine learning algorithms, which have proven to deliver the most robust predictions across a choice of 24 different algorithms tested. Additionally, a new format of in situ rheology display was introduced, referred to as RRF™ factor.

Improving the Antibiofouling and Operational Properties of PVDF Membranes Using Synthesized Cu‐SiO2 Nanoparticles in a Submerged Membrane Bioreactor

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Improving the Antibiofouling and Operational Properties of PVDF Membranes Using Synthesized Cu-SiO2 Nanoparticles in a Submerged Membrane Bioreactor

PVDF/Cu-SiO2 (1 wt %) composite membranes showed higher hydrophilicity and a lower irreversible fouling ratio in membrane bioreactors. They showed better resistance to Escherichia coli, and membranes containing 0.5 and 1.0 wt % of Cu-SiO2 nanoparticles were stabilized after 28 days of release testing.


Abstract

The effects of synthesized hydrophilic Cu-SiO2 nanoparticles on the morphology and antibiofouling performance of polyvinylidene fluoride (PVDF) membranes in a membrane bioreactor system were examined. As a result, the pure water flux of the PVDF membrane increased from 47.61 to 71.93 L m−2h−1 in the presence of 1.0 wt % Cu-SiO2 nanoparticles. Also, the better-developed finger-like bulk pores and thicker sponge-like surface pores for the nanocomposite membranes confirmed the lower phase inversion rate. The total fouling ratio of the membranes was reduced from 53.79 % to 24.13 % in the presence of 1.0 wt % Cu-SiO2 nanoparticles, while the flux recovery ratio increased from 54.61 % to 88.73 %. In addition, extracellular polymeric substances analysis showed lower protein and carbohydrate formed on the membrane surface for the nanocomposite membranes.

Effect of Synthetic Conditions on the Structure and Properties of Nb14W3O44 Anode for Lithium‐Ion Batteries

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Effect of Synthetic Conditions on the Structure and Properties of Nb14W3O44 Anode for Lithium-Ion Batteries

Niobium tungsten oxide Nb14W3O44 was synthesized by hydrothermal reaction of niobium oxalate and ammonium tungstate and subsequent calcination, and the synthetic conditions and structure were optimized for its use as an anode material in lithium-ion batteries. The nearly pure phase Nb14W3O44 with a particle size of 1–2 μm shows good rate performance and cycle stability with high capacity retention.


Abstract

Niobium tungsten oxide is a potential replacement for graphite in fast-charge lithium-ion batteries due to its high rate performance and high stability. Herein, Nb14W3O44 anode was synthesized by hydrothermal reaction of niobium oxalate and ammonium tungstate and sequent calcination of niobium tungsten oxide precursors. Compared with the traditional solid-state method, the particle size and calcination time of Nb14W3O44 obtained by the modified method are greatly reduced. Through orthogonal experiments, the optimal synthesis conditions were determined, and it was found that hydrothermal conditions have an important influence on the particle size of the final product, while the calcination temperature and time greatly affect the purity of the product and thus influence its specific capacity during cycles.

One‐Step Synthesis of Pseudo‐Boehmite by Carbonation in a Microchannel Reactor

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One-Step Synthesis of Pseudo-Boehmite by Carbonation in a Microchannel Reactor

A reversed liquid-to-gas contact mode in the microchannel reactor can significantly improve the carbonization method for the synthesis of high-purity mesoporous pseudo-boehmite. The transfer mass details were simulated by computational fluid dynamics. The NaAlO2 droplets were surrounded by the CO2 gas flow in the microchannel, which is the key to the two-phase mixing efficiency.


Abstract

Pseudo-boehmite with a high specific surface area and large pore volume was continuously synthesized in a microchannel reactor using the carbonation method. The effects of the microchannel on the prepared pseudo-boehmite, strongly present in gas-liquid mixing efficiency, were studied. In time scale, the crystallinity of pseudo-boehmite in the microchannel, without the aging process of high-temperature stirring, reaches the standard of industrial products. Besides, the fluid and mass transfer effect of the gas-liquid mixing process in the microreactor was simulated under experimental conditions in computational fluid dynamics. The result illustrated the base-liquid surround by the acid-gas model in the microreactor, which is significantly different from the batch reactor.

Pyrolysis of Spherical Wood Particles in a Packed Bed – Comparison between Resolved and Unresolved Discrete Element Method/Computational Fluid Dynamics

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Pyrolysis of Spherical Wood Particles in a Packed Bed – Comparison between Resolved and Unresolved Discrete Element Method/Computational Fluid Dynamics

Two discrete element method/computational fluid dynamics coupling approaches are compared: One method resolves the particle shape in the fluid flow, the other one does not. Differences between these two methods with regard to the evolution of particle-based parameters (mass, temperature) are reported. A bulk of thermally thick, pyrolyzing spherical particles is taken for the numerical study.


Abstract

The combined discrete element method/computational fluid dynamics (DEM/CFD) approach allows for the description of reacting granular assemblies passed by a gas flow. Especially for thermally thick particles, the spatial resolution of the solid object volumes, their surfaces, and of the interstitial flow domain controls the quality of results while at the same time driving computational costs. To evaluate the differences between resolved and unresolved DEM/CFD approaches, pyrolysis of a bulk of spherical wood particles enclosed by a cylindrical heating surface and passed by hot nitrogen is numerically examined. The unresolved simulation is based on the averaged volume method (AVM). For the resolved simulation, the so-called blocked-off (BO) method is applied. The results show that the total mass conversion rate of solid particles into gaseous volatiles is faster when employing the resolved BO approach. The better spatial resolution of local flow field and particle surface representation leads to a more detailed prediction of convective and radiative heat transfer to the particles, but is associated with the penalty of a six-fold computing time.

Relationship Between Stress Modulated Metallicity and Plasmon in Graphene Nanoribbons

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Nanoscale quantum plasmon is an important technology that restricts the application of optics, electricity, and graphene photoelectric devices. Establishing a structure-effect relationship between the structure of graphene nanoribbons (GNRs) under stress regulation and the properties of plasmons is a key scientific issue for promoting the application of plasmons in micro-nano photoelectric devices. In this study, zigzag graphene nanoribbon (Z-GNR) and armchair graphene nanoribbon (A-GNR) models of specific widths were constructed, and density functional theory (DFT) was used to study their lattice structure, energy band, absorption spectrum, and plasmon effects under different stresses. The results showed that the Z-GNR band gap decreased with increasing stress, and the A-GNR band gap changed periodically with increasing stress. The plasmon effects of the A-GNRs and Z-GNRs appeared in the visible region, whereas the absorption spectrum showed a redshift trend, indicating the range of the plasmon spectrum also underwent significant changes. This study provides a theoretical basis for the application of graphene nanoribbons in the field of optoelectronics under strain-engineering conditions.

Recent Progress in Polymer Waste‐Derived Porous Carbon for Supercapacitors

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Recent Progress in Polymer Waste-Derived Porous Carbon for Supercapacitors

In this paper, the PWCM electrode prepared from polymer wastes in recent years was reviewed, and the effect of different preparation methods on the electrode performance was compared.


Abstract

Due to the high power density, fast charging speed, and long cycling stability, supercapacitors have been developed rapidly in the area of electrical energy storage devices in the past decades. During the application of supercapacitors, it was found that the properties of the electrode material can greatly affect the supercapacitor performance. Recently, electrode materials based on polymer waste-derived carbon materials (PWCM) have attracted much attention because of the low preparation cost, good electrode performance, and great benefits for environmental protection. This review aims to describe the recent research development and summarize the investigation state in the field of the PWCM electrodes prepared from polyethylene, polypropylene, polyethylene terephthalate, polystyrene, etc. The preparation method and the electrode performance of the PWCM electrodes are compared. The relationship among the preparation methods, material structure, and electrochemical performance of the PWCM electrodes was explored. Furthermore, the prospects for the application of the PWCMs were provided.

Construction of the Bioconjugate Py‐Macrodipa‐PSMA and Its In Vivo Investigations with Large 132/135La3+ and Small 47Sc3+ Radiometal Ions

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To harness radiometals in clinical settings, a chelator forming a stable complex with the metal of interest and targets the desired pathological site is needed. Toward this goal, we previously reported a unique set of chelators that can stably bind to both large and small metal ions, via a conformational switch. Within this chelator class, py-macrodipa is particularly promising based on its ability to stably bind several medicinally valuable radiometals including large 132/135La3+, 213Bi3+, and small 44Sc3+. We report a 10-step organic synthesis of its bifunctional analogue py-macrodipa-NCS, which contains an amine-reactive –NCS group that is amenable for bioconjugation reactions to targeting vectors. The hydrolytic stability of py-macordipa-NCS was assessed, revealing a half-life of 6.0 d in pH 9.0 aqueous buffer. This bifunctional chelator was then conjugated to a prostate-specific membrane antigen (PSMA)-binding moiety, yielding the bioconjugate py-macrodipa-PSMA, which was subsequently radiolabeled with large 132/135La3+ and small 47Sc3+, revealing efficient and quantitative complex formation. The resulting radiocomplexes were injected into mice bearing both PSMA-expressing and PSMA-non-expressing tumor xenografts to determine their biodistribution patterns, revealing delivery of both 132/135La3+ and 47Sc3+ to PSMA+ tumor sites. Urine analysis, however, revealed partial radiometal dissociation, suggesting that py-macrodipa-PSMA needs further structural optimization.

Copper‐Catalyzed Highly Stereoselective Hydrodifluoroallylation of Cyclopropenes and Alkenyl Boronates with 3,3‐Difluoroallyl Sulfonium Salts

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Copper-Catalyzed Highly Stereoselective Hydrodifluoroallylation of Cyclopropenes and Alkenyl Boronates with 3,3-Difluoroallyl Sulfonium Salts†

A copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts (DFASs) has been developed. The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions. The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products.


Comprehensive Summary

Despite the paramount applications of organofluorine compounds in life and materials sciences, efficient strategies for stereoselectively constructing the C(sp3)-CF2R bond at the stereogenic center remain limited. Here, we report a copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts (DFASs). The use of DFASs overcomes the previous challenge of suppressing the reduction of fluoroalkylating reagents with M-H species. The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions. Using chiral phosphine ligand could provide gem-difluoroallyl borylalkanes with high enantioselectivities, paving a new way for the catalytic asymmetric fluoroalkylation with ubiquitous alkenes. The advantages of this protocol are synthetic convenience, high functional group tolerance, and the synthetic versatility of the resulting gem-difluoroallyl cyclopropanes and borylalkanes. The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products and the rapid synthesis of bioactive molecule analogs.

DFT Calculations and Synthesis Reveal: Key Intermediates, Omitted Mechanisms, and Unsymmetrical Bimane Products

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DFT Calculations and Synthesis Reveal: Key Intermediates, Omitted Mechanisms, and Unsymmetrical Bimane Products

We studied the mechanism behind the formation of fluorescent syn-bimane. This work combines theoretical and experimental approaches. Our computational study supports Kosower's mechanism while introducing a crucial diaziridine intermediate. Our results suggest the rate-limiting step is the formation of a diazoketene. The reaction of 4,5-dimethyl-2,3-diazacyclopentadienone with diphenylcyclopropenone produced the unexpected unsymmetrical anti-(Me,Me)(Ph,Ph)bimane.


Abstract

Theoretical and experimental mixed approaches are complementary and valuable. Our DFT calculations support the mechanism suggested by Kosower, adding to it a key diaziridine intermediate that determines the relative product distribution of this reaction. Our results are consistent with the formation of the diazoketene intermediate as the rate-limiting step. Based on curve fittings, first or second-order kinetics cannot be ruled out. This may indicate that more than one mechanism is simultaneously at play in this transformation. This unexpected outcome led us to study an alternative cyclopropenone intermediate. Although cyclopropenone is not likely to be formed under thermal conditions, adding it to the reaction mixture results in bimane structures. The most staggering finding from this investigation was the unanticipated generation of the unsymmetrical anti-(Me,Me)(Ph,Ph)bimane. The optimization of this route towards unsymmetrical bimanes will require additional investigation.