Stochastic Nucleation for Feedback‐Controlled Cooling Crystallization without Seeding

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Stochastic Nucleation for Feedback-Controlled Cooling Crystallization without Seeding

The dispersion of batch time considering stochastic nucleation in an L-arginine-water system was estimated by repetitive computer simulation in the case of internally seeded cooling crystallization with direct nucleation control. Mathematical models and conditions used in the simulation are explained and results of the simulation are described.


Abstract

The dispersion of batch time, i.e., the time for finalizing batch crystallization satisfying batch end conditions, in internally seeded cooling crystallization with direct nucleation control (DNC) was estimated by computer simulation. The batch time is considered to disperse at such crystallization due to stochastic nucleation. In this study, first, a population balance equation was digitized for numerical calculation, and the simulation was developed in MATLAB. Then, repetitive simulations of internally seeded cooling crystallization considering stochastic nucleation with DNC were performed. Finally, the batch time of each simulation was arranged. As a result, it was found that there is little batch time dispersion in crystallization controlled by DNC and without adding seed.

One‐Pot Polyol Synthesis and Scalable Production of Rh−Pd Alloy Nanorods with Tunable Compositions

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One-Pot Polyol Synthesis and Scalable Production of Rh−Pd Alloy Nanorods with Tunable Compositions

Combining different precious metals to generate alloy nanocrystals with desirable shapes and compositions remains a challenge. In this work, we demonstrate that Rh−Pd alloy nanorods with well-distributed and tunable compositions can be synthesized using a one-pot polyol method.


Abstract

Combining different precious metals to generate alloy nanocrystals with desirable shapes and compositions remains a challenge because of the low miscibility between these metals and/or the different reduction potentials of their salt precursors. Specifically, Rh and Pd are considered to be immiscible in the bulk solid over the entire composition range. Here we demonstrate that Rh−Pd alloy nanorods with well-distributed and tunable compositions can be synthesized using a one-pot polyol method. The success of our synthesis relies on the introduction of bromide as a coordination ligand to tune the redox potentials of Rh(III) and Pd(II) ions for the achievement of co-reduction. The atomic ratio of the Rh−Pd alloy nanorods can be facilely tuned by changing the molar feeding ratio between the two precursors. We also systematically investigate the effects of water on the morphology of the Rh−Pd alloy nanocrystals. In an attempt to promote future use of these alloy nanorods, we successfully scale up their synthesis in a continuous-flow reactor with no degradation to the product quality.

Chemical and Photophysical Triggers for the Reduction of Pt(IV) Prodrugs for Anticancer Therapy

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Chemical and Photophysical Triggers for the Reduction of Pt(IV) Prodrugs for Anticancer Therapy

Platinum(II) complexes are widely as chemotherapeutic agents worldwide. Despite their application, these compounds are associated with severe side effects and lack of tumor selectivity. To address these issues, researchers have explored platinum(IV) prodrugs that remain stable and inactive in the body, but can be rapidly converted into active analogs using specific triggers. This article critically reviews the mechanisms of chemical and photophysical triggers for activating platinum(IV) prodrugs.


Abstract

Platinum(II) complexes are used in approximately 50% of chemotherapeutic treatments worldwide. Despite their undoubtful clinical success, these compounds are associated with severe side effects and poor tumor selectivity. To overcome these drawbacks, the development of platinum(IV) molecular prodrugs and nanoparticle formulations that remain stable and therapeutically inactive in a biological environment, but could be quickly reduced into the therapeutically active analogs through a specific trigger have been thought. Within this article, the mechanisms for chemical and photophysical triggers for the activation of platinum(IV) prodrugs have been critically reviewed.

Recent Advances in Electrochemical, Ni‐Catalyzed C−C Bond Formation

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Recent Advances in Electrochemical, Ni-Catalyzed C−C Bond Formation


Abstract

Nickel-catalyzed cross-electrophile coupling (XEC) is an efficient method to form carbon-carbon bonds and has become an important tool for building complex molecules. While XEC has most often used stoichiometric metal reductants, these transformations can also be driven electrochemically. Electrochemical XEC (eXEC) is attractive because it can increase the greenness of XEC and this potential has resulted in numerous advances in recent years. The focus of this review is on electrochemical, Ni-catalyzed carbon-carbon bond forming reactions reported since 2010 and is categorized by the type of anodic half reaction: sacrificial anode, sacrificial reductant, and convergent paired electrolysis. The key developments are highlighted and the need for more scalable options is discussed.

Estimation of Lysozyme Concentration on a Membrane Surface Using a Membrane Crystallization Method

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Estimation of Lysozyme Concentration on a Membrane Surface Using a Membrane Crystallization Method

A membrane crystallization method using ultrafiltration was investigated to obtain high-quality protein crystals for structural analysis. Membrane surface concentrations, which could not be measured, can be estimated by simulation. The membrane surface concentration increased rapidly during initial pressurization at any pressure, which was found to be the initial stage of crystal formation.


Abstract

High-quality single crystals are necessary for structural analysis of proteins. However, it is difficult to obtain high-quality single crystals in a short time. Therefore, a membrane crystallization method was applied in which lysozyme is concentrated on the membrane surface using an ultrafiltration membrane. Membrane surface concentrations, which cannot be measured, were calculated based on the measurable permeation flux. At all operating pressures, the measured and simulated permeation fluxes were in close agreement, allowing the membrane surface concentration to be estimated. The membrane surface concentration increased rapidly at all pressures during the initial pressurization, indicating that crystals were formed at an early stage.

Lithium‐Ion Battery Cathode Recycling through a Closed‐Loop Process Using a Choline Chloride‐Ethylene Glycol‐Based Deep‐Eutectic Solvent in the Presence of Acid

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Lithium-Ion Battery Cathode Recycling through a Closed-Loop Process Using a Choline Chloride-Ethylene Glycol-Based Deep-Eutectic Solvent in the Presence of Acid

A novel closed-loop method for Li and Co recovery from a lithium cobalt oxide (LCO) material using a deep eutectic solvent (DES) based on choline chloride (ChCl) and ethylene glycol (EG) with an additional source of protons. This process allowed to quantitatively recover Co and Li, highlighting the importance of adding a precise amount of protons to drive Co dissolution. In addition, the DES was used in three successive leaching/recovery cycles without any degradation.


Abstract

This study evaluates the ability of a choline chloride:ethylene glycol-based deep eutectic solvent (DES) to dissolve lithium cobalt oxide (LCO) which is used as a cathode active material in Li-ion batteries. Both a commercial powder and spent cathodes have been used. It was demonstrated that if HCl is added in a small proportion, a rapid and efficient LCO dissolution can be achieved. Indeed, if more than three protons are added per one cobalt atom present in the LCO structure, a complete dissolution of the material is accomplished within 2 h at 80 °C. This result might be considered as a viable alternative compared to the literature where much longer reaction times and higher temperatures are applied to achieve similar results with the same DES system used either pure or in presence of additional reducing agents. It was further demonstrated that Co and Li can be fully precipitated after Li2CO3 addition. This precipitation does neither pollute the DES nor leads to its degradation provided the pH does not exceed 10. Finally, it was shown that two additional reuse cycles can be carried out without any decrease of recovery efficiency, while no degradation products have been detected within the DES phase.