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Proceedings of the National Academy of... Oct 2023Macromolecules bearing open-shell entities offer unique transport properties for both electronic and spintronic devices. This work demonstrates that, unlike their...
Macromolecules bearing open-shell entities offer unique transport properties for both electronic and spintronic devices. This work demonstrates that, unlike their conjugated polymer counterparts, the charge carriers in radical polymers (i.e., macromolecules with nonconjugated backbones and with stable open-shell sites present at their pendant groups) are singlet cations, which opens significant avenues for manipulating macromolecular design for advanced solid-state transport in these highly transparent conductors. Despite this key point, magnetoresistive effects are present in radical polymer thin films under applied magnetic fields due to the presence of impurity sites in low (i.e., <1%) concentrations. Additionally, thermal annealing of poly(4-glycidyloxy-2,2,6,6- tetramethylpiperidine-1-oxyl) (PTEO), a nonconjugated polymer with stable open-shell pendant groups, facilitated better electron exchange and pairwise spin interactions resulting in an unexpected magnetoresistance signal at relatively low field strengths (i.e., <2 T). The addition of 4-hydroxy-2,2,6,6-tetramethylpiperidin-N-oxy (TEMPO-OH), a paramagnetic species, increased the magnitude of the MR effect when the small molecule was added to the radical polymer matrix. These macroscopic experimental observables are explained using computational approaches that detail the fundamental molecular principles. This intrinsic localized charge transport behavior differs from the current state of the art regarding closed-shell conjugated macromolecules, and it opens an avenue towards next-generation transport in organic electronic materials.
PubMed: 37862383
DOI: 10.1073/pnas.2308741120 -
Chemosphere Dec 2023The global level of attention has been raised for photocatalytic pollutant removal technologies for degrading organic pollutants because of rising concerns about their...
The global level of attention has been raised for photocatalytic pollutant removal technologies for degrading organic pollutants because of rising concerns about their toxicity. In this study, NiFeO/TiO core shells and pure samples of NiFeO and TiO were synthesized using the sol-gel process and used to degrade naphthalene which is one among the polycyclic aromatic hydrocarbons (PAHs) pollutant. The synthesized materials were evaluated using a variety of analytical techniques, and the typical NiFeO/TiO core-shell results showed good purity and a lack of other impurity structures. Through morphological characterization, the core-shell structure of NiFeO/TiO has been established. However, the activity of visible light degradation was boosted by the generation of hydroxyl radicals after the electron-hole pair was delayed. Additionally, a lower band gap in NiFeO/TiO than in pure materials promotes photocatalytic activity. Similarly, photocatalytic naphthalene elimination by the core-shell achieved 67% efficiency after 150 min of visible light exposure. Furthermore, the produced core-shell has a high magnetic property, making separation from the photo-irradiated solutions easier; as a result, recycling was likely successful up to three cycles. The photocatalytic mechanism of the NiFeO/TiO composite was proposed. This research could also be applied to the degradation of other polycyclic aromatic hydrocarbon contaminants.
PubMed: 37758072
DOI: 10.1016/j.chemosphere.2023.140274 -
Small (Weinheim An Der Bergstrasse,... Dec 2023The evolution and formation process of two-dimensional metal-organic frameworks (MOFs) primarily arise from the anisotropic growth of crystals, leading to variations in...
The evolution and formation process of two-dimensional metal-organic frameworks (MOFs) primarily arise from the anisotropic growth of crystals, leading to variations in photocatalytic performance. It is crucial to achieve a synergistic combination of anisotropic electron transfer direction and dimension reduction strategies. In this study, a novel approach that effectively blocks crystal growth accretion through the coordination of solvent molecules is presented, achieving the successful synthesis of impurity-free two-dimensional nanosheet Zn-PTC with exceptional hydrogen evolution reaction (HER) performance (15.4 mmol g h ). The structural and photophysical characterizations validate the successful prevention of crystal accretion, while establishing correlation between structural anisotropy and intrinsic charge transfer mode through transient spectroscopy. These findings unequivocally demonstrate that electron transfer along the [001] direction plays a pivotal role in the redox performance of nano-Zn-PTC. Subsequently, by coupling the photocatalytic performance and density functional theory (DFT) simulation calculations, the carrier diffusion kinetics is explored, revealing that effective dimension reduction along the ligand-to-metal charge transfer (LMCT) direction is the key to achieving superior photocatalytic performance.
PubMed: 37635096
DOI: 10.1002/smll.202305308 -
Nanotechnology Oct 2023Two-electron oxygen reduction reaction (2eORR) for HOproduction is regarded as a more ecologically friendly substitute to the anthraquinone method. However, the search...
Two-electron oxygen reduction reaction (2eORR) for HOproduction is regarded as a more ecologically friendly substitute to the anthraquinone method. However, the search of selective and cheap catalysts is still challenging. Herein, we developed a neutral-selective and efficient nonprecious electrocatalyst that was prepared from a commercial activated carbon (AC) by simply microwave-assisted ash impurity elimination and hydrogen peroxide oxidation for surface functional sites optimization. The oxygen configuration can be tuned with enriching carboxyl group up to 6.65 at.% by the dosage of hydrogen peroxide (mass ratio of HO/C = ∼0-8.3). Chemical titration experiments identified the carbonyl groups as the most potential active sites, with selectivity boosted by the additional carboxyl groups. The microwave-assisted moderate-oxidized activated carbon (MW-AC5.0) demonstrated optimal 2eORR activity and selectivity in neutral electrolyte (0.1 M KSO), with HOselectivity reaching ∼75%-97%, a maximum HOproduction rate (1.90 mol·g·[email protected] V) and satisfying faradaic efficiency (∼85%) in gas-diffusion-electrode. When coupled with Fenton reaction, it can degrade a model organic pollutant (methylene blue [MB], 50 ppm) to colorless in a short time of 20 min, indicating the potential applications in the environmental remediation.
PubMed: 37797607
DOI: 10.1088/1361-6528/ad0055 -
ACS Applied Materials & Interfaces Sep 2023Quasi-two-dimensional (quasi-2D) perovskites exhibit excellent performance when applied to light-emitting diodes (LEDs). However, quasi-2D perovskite films generally...
Quasi-two-dimensional (quasi-2D) perovskites exhibit excellent performance when applied to light-emitting diodes (LEDs). However, quasi-2D perovskite films generally have nonuniform phases and irregular internal crystal structures, which degrade the device's performance. Here, we propose using a Dion-Jacobson (DJ)-type organic spacer to modulate the phase distribution of the Ruddlesden-Popper (RP) quasi-2D perovskite. A DJ-type organic spacer cation, 1.6-hexamethylenediamine (HDABr), was introduced into the perovskite as the second spacer cation with propylamine hydrobromide (PABr). As DJ-type and RP-type perovskites have similar spacings, RP-DJ style does not cause a chaotic crystalline structure; instead, it modulates the perovskite crystallization and narrows the phase distribution. In parallel, there is a substantial improvement in the maximum luminance, current efficiency, external quantum efficiency, and device stability of the quasi-2D perovskite LEDs. This work provides a novel concept for combining the organic spacer cations for quasi-2D perovskites.
PubMed: 37646254
DOI: 10.1021/acsami.3c03110 -
Journal of Chromatography. B,... Sep 2023As cases of multidrug resistant bacterial infections increase, scientists and clinicians around the world are increasingly turning to bacteriophages as alternatives to...
As cases of multidrug resistant bacterial infections increase, scientists and clinicians around the world are increasingly turning to bacteriophages as alternatives to antibiotics. Even though our understanding of phage has increased significantly since the early days of its discovery, over a century ago, the currently used tools and technologies for phage purification for therapeutic applications are severely limited. Bacteriophages are produced by bacterial cultures, and impurities such as endotoxins must therefore be removed before clinical use. We present an anion exchange bind-and-elute membrane chromatographic method for purifying T7 bacteriophage from Escherichia coli culture supernatant that removes undesirable impurities, while ensuring a high viable phage count in the purified product. Our method does not involve the use of chemicals such as organic solvents and caesium chloride that could typically leave residual toxicity in the final product. It also does not require expensive equipment, such as an ultracentrifuge. Using our method, that is based on an in-house designed membrane module, 65% of viable T7 phage was recovered, and up to 94% endotoxins could be removed. The method, which took approximately 15 min, is rapid and scalable, and produces quite pure bacteriophage samples in a single step. It therefore potentially represents a major improvement over the status quo, and shows the way ahead for streamlining phage manufacturing for therapeutic use.
Topics: Bacteriophages; Chromatography; Endotoxins; Anions; Solvents
PubMed: 37689032
DOI: 10.1016/j.jchromb.2023.123867 -
Environmental Technology Feb 2024The lack of safe drinking water is among the main problems to be faced by many areas of the world due to climate change, unrestrained population increases, and...
The lack of safe drinking water is among the main problems to be faced by many areas of the world due to climate change, unrestrained population increases, and unsustainable usage of water sources. Therefore, research projects focusing on water quality, pollution, and control for sustainable water sources are in high demand to manage any unexpected changes in water sources. Drinking water sources may be contaminated with organic and inorganic chemicals, disinfection by-products, and microorganisms. Different treatment processes to remove these contaminants from water may be limited because of their high costs and time-consuming or require a multiple-barrier approach to improving performance. Therefore, there is a great need to develop an effective process for removing impurities. The primary objective of this study is to assess the effectiveness of algae-based activated carbons and develop a unique, low-cost sustainable process for wastewater treatment. Activated carbons were produced from pelletised algae powder using carbonisation and chemical activation. Chemical activation was carried out with calcium chloride (CaCl) and zinc chloride (ZnCl) as chemical agents. Furthermore, Brunauer-Emmett-Teller (BET) along with scanning electron microscopy (SEM) techniques were used to analyse the morphology, surface area, as well as the porosity of the prepared activated carbons to build a water column filter. Based on the results, algae-based carbon with CaCl activation provided a better surface area (197.7486 m/g) and cumulative pore volume (0.105284 cm/g). The filtration process using algae-based activated carbon can be a promising technique for water treatment with some further improvement and modifications.
Topics: Charcoal; Spirulina; Drinking Water; Calcium Chloride; Adsorption; Water Purification
PubMed: 36263868
DOI: 10.1080/09593330.2022.2138557 -
Waste Management & Research : the... Nov 2023With the continuous development of new energy vehicles, the number of decommissioned lithium iron phosphate (LiFePO) batteries has been constantly increasing. Therefore,...
With the continuous development of new energy vehicles, the number of decommissioned lithium iron phosphate (LiFePO) batteries has been constantly increasing. Therefore, it is necessary to recover metal from spent LiFePO batteries due to the high potential for environmental protection and high resource value. In this study, sodium persulfate (NaSO) was selected as the oxidant to regulate and control the oxidation state and proton activity of the leaching solution through its high oxidizing ability. Selective recovery of lithium from LiFePO batteries was achieved by oxidizing LiFePO to iron phosphate (FePO) during the leaching process. This paper reports an extensive investigation of the effects of various factors, including the acid concentration, initial volume fraction of the oxidant, reaction temperature, solid-liquid ratio, and reaction time, on lithium leaching. Li reached a high leaching rate of 93.3% within 5 minutes even at a low concentration of sulphuric acid (HSO), and high-purity lithium carbonate (LiCO) was obtained through impurity removal and precipitation reactions. In addition, the leaching mechanism was analysed by both X-ray diffraction and X-ray photoelectron spectroscopy characterization. The results show that the obtained high lithium-ion (Li) leaching efficiency and fast Li leaching time can be ascribed to the superior oxidizing properties of NaSO and the stability of the crystal structure of LiFePO during the oxidative leaching process. The adopted method has significant advantages in terms of safety, efficiency and environmental protection, which are conducive to the sustainable development of lithium batteries.
Topics: Lithium; Metals; Electric Power Supplies; Recycling; Oxidants; Iron; Phosphates
PubMed: 37102334
DOI: 10.1177/0734242X231168051 -
Journal of the American Chemical Society Jan 2024Recombinant enzymes have gained prominence due to their diverse functionalities and specificity and are often a greener alternative in biocatalysis. This context makes...
Recombinant enzymes have gained prominence due to their diverse functionalities and specificity and are often a greener alternative in biocatalysis. This context makes purifying recombinant enzymes from host cells and other impurities crucial. The primary goal is to isolate the pure enzyme of interest and ensure its stability under ambient conditions. Covalent organic frameworks (COFs), renowned for their well-ordered structure and permeability, offer a promising approach for purifying histidine-tagged (His-tagged) enzymes. Furthermore, immobilizing enzymes within COFs represents a growing field in heterogeneous biocatalysis. In this study, we have developed a flow-based technology utilizing a nickel-infused covalent organic framework (Ni-TpBpy COF) to combine two distinct processes: the purification of His-tagged enzymes and the immobilization of enzymes simultaneously. Our work primarily focuses on the purification of three His-tagged enzymes β-glucosidase, cellobiohydrolase, and endoglucanase as well as two proteins with varying molecular weights, namely, green fluorescent protein (27 kDa) and BG Rho (88 kDa). We employed Ni-TpBpy as a column matrix to showcase the versatility of our system. Additionally, we successfully obtained a Ni-TpBpy COF immobilized with enzymes, which can serve as a heterogeneous catalyst for the hydrolysis of -nitrophenyl-β-d-glucopyranoside and carboxymethylcellulose. These immobilized enzymes demonstrated catalytic activity comparable to that of their free counterparts, with the added advantages of recyclability and enhanced stability under ambient conditions for an extended period, ranging from 60 to 90 days. This contrasts with the free enzymes, which do not maintain their activity as effectively over time.
Topics: Metal-Organic Frameworks; Biocatalysis; Enzymes, Immobilized; Indicators and Reagents; Catalysis
PubMed: 38159294
DOI: 10.1021/jacs.3c11169 -
Yakugaku Zasshi : Journal of the... 2024Quantitative NMR (qNMR) has been adopted by documentary standards, including the Japanese Pharmacopoeia (JP), United States Pharmacopoeia (USP), and International...
Quantitative NMR (qNMR) has been adopted by documentary standards, including the Japanese Pharmacopoeia (JP), United States Pharmacopoeia (USP), and International Organization for Standardization (ISO), owing to its reliability and efficiency. Note that qNMR can be used for quantifying target components using the signal integration ratio of an analyte to a reference. In qNMR, a modern NMR instrument with high resolution and sensitivity is used to record reliable spectra. This instrument can detect small signals from impurities in a solvent, which may result in inaccurate signal integration in the spectrum. In this study, we investigated the influence of solvent quality on qNMR accuracy focusing on organic impurities, water content, and deuteration ratio. If signals from organic impurities and signals from the analyte overlap, the duplication of signal integration will directly affect the qNMR analytical result. To examine overlapping, we performed blank solvent tests. Additionally, a high water content and low deuteration ratio affect the detection sensitivity, thus reducing the signal-to-noise (S/N) ratio of the target. Thus, these factors must be considered to obtain accurate qNMR results.
Topics: Solvents; Reproducibility of Results; Magnetic Resonance Spectroscopy; Reference Standards; Water
PubMed: 38556309
DOI: 10.1248/yakushi.23-00151-4