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Substitutional nitrogen impurities within the diamond lattice, known as P1 centers, have unpaired electrons that can mediate microwave driven dynamic nuclear polarization (DNP). In this paper we explore DNP of the bulk C spins in micrometer-sized P1 diamond particles and demonstrate a 550-fold DNP enhancement of the bulk C spins at room temperature in a 9 T magnetic field or 250 GHz for ≈ 2 electrons. We study the DNP mechanisms, exploring their dependence on sample spinning frequency and microwave irradiation frequency using both continuous wave and frequency swept microwave irradiation, and discuss the results alongside recent DNP studies in the literature. Even with a modest microwave irradiation power of 160 mW from our frequency swept solid-state microwave source, we achieve a significant C signal enhancement, ε = 270 at room temperature. The enhancements were found to increase with the magic angle spinning (MAS) frequency, ω/2π, and the results provide mechanistic insights into how different electron populations contribute to the observed DNP efficiency. These findings are inherently interesting and of practical importance in view of the recently reported diamond rotors fabricated from P1 high-pressure, high-temperature (HPHT) diamond.
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http://dx.doi.org/10.1021/acs.jpclett.4c02612 | DOI Listing |
J Org Chem
September 2025
National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, School of Chemistry and Environment, Yunnan Minzu University, Kunming 650500, P. R. China.
We herein describe a novel decarboxylation/cyclization sequence involving a three-component reaction of dialkyl 2-(alkoxymethylene)malonate, amines, and terminal alkyne ester or internal alkyne ester catalyzed by CsCO under microwave conditions. These two types of highly chemo- and regioselective transformations were accomplished by different reaction channels to furnish a wide range of functionalized 8-hydroxyisoquinoline-1(2)-ones (21 examples) and 2-pyridones (18 examples) in good to excellent yields and might provide new opportunities for the discovery of N-heterocyclic drugs and other functional molecules.
View Article and Find Full Text PDFTurkiye Parazitol Derg
September 2025
Department of Medical Physics, Faculty of Paramedicine, Arak University of Medical Sciences, Arak, Iran.
Objective: Drug resistance in poses a significant challenge, prompting the need for alternative treatments. This research aimed to explore the combined treatment of chemical or phytomedicines and microwaves radiation.
Methods: The strain was cultivated on non-nutrient agar.
Org Lett
September 2025
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata-700009, India.
This study introduces microwave-assisted, Fe(III)-catalyzed ring-opening annulations of isoxazoles, enabling the rapid and selective synthesis of 1,4-diacyl pyrroles and substituted pyridines. By leveraging microwave irradiation and transition metal catalysis, this approach enhances the reaction efficiency, reduces reaction times, and promotes high regioselectivity under mild conditions. Under thermal conditions, the Ru(II) catalyst led to the synthesis of nicotinamide derivatives.
View Article and Find Full Text PDFCarbohydr Polym
November 2025
Department of Inorganic, Organic and Biochemistry, Faculty of Chemical Sciences and Technologies, University of Castilla-La Mancha, Ciudad Real, 13005, Spain. Electronic address:
This study investigates the extraction, optimization, and characterization of pectin from pistachio industry waste (PIW) using microwave-assisted subcritical water extraction (MASWE) without acid. Two different low-methoxyl pectins (LMP) were observed. The first pectin variant (MASWE100) was extracted at a pressure of 3 MPa, a temperature of 100 °C, and an irradiation time of 4 min.
View Article and Find Full Text PDFJ Mater Chem B
September 2025
Department of Orthopedics, Northern Jiangsu People's Hospital Affiliated to Yangzhou University, 225000, China.
Implant-related infections (IRIs) pose a major challenge in orthopedic applications due to the persistence of biofilms, which are highly resistant to conventional antibiotics. This study introduces oxygen vacancy-engineered Zn-Fe spinel nanoparticles as microwave-responsive antibacterial agents. The oxygen vacancies in the spinel structure enhance reactive oxygen species (ROS) generation under microwave irradiation, providing a dual-mode antibacterial mechanism of thermal and oxidative stress.
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