Spin-frustrated polyoxometalates, K(11)H[(VO)(3)(SbW(9)O(33))(2)].27H(2)O (1) and K(12)[(VO)(3)(BiW(9)O(33))(2)].29H(2)O (2), containing approximately equilateral and isosceles (VO)(3)(6+)-triangles (V(IV)...V(IV) separation of 5.4-5.5 A) sandwiched by two diamagnetic alpha-B nonatungstate ligands ([SbW(9)O(33)](9)(-) and [BiW(9)O(33)](9)(-)) with approximate D(3)(h) symmetry, are found to show magnetization jumps with distinct hysteresis for the S = (1)/(2) <--> S = (3)/(2) level crossing under fast sweeping pulsed magnetic fields (approximately 10(3) T/s) at T < or = 0.5 K. This unusual phenomenon is attributed to the theoretical prediction of half step magnetization, which is expected for an antiferromagnetic spin triangle with antisymmetrical Dzyaloshinky-Moriya interaction. The degeneracy of the S = (1)/(2) states for 1 is removed by slightly lower symmetry effects of triangular structure for 2. The calorimetry of 1 and 2 shows the heat capacity anomaly at 2 < or = T < or = 20 K which is associated with a thermal excitation from the S = (1)/(2) ground states to the S = (3)/(2) state at zero field. Zero-field splitting energies (5-7 K) between S = (1)/(2) and S = (3)/(2) states for 1 and 2, readily estimated by the level-crossing field for the magnetization, allow us to measure the hyperfine-structural 22 lines due to three equivalent I = (7)/(2) (51)V nuclei, the fine-structural triplet line of the S = (3)/(2) excited state, and the g anisotropy on the high-frequency ESR spectra. The spin-frustrated (VO)(3)(6+)-triangle for 1 and 2 is a good model of the magnetization between pure quantum states S = (1)/(2) and (3)/(2) and provides a new class of single-molecule magnets.
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http://dx.doi.org/10.1021/ic049669n | DOI Listing |
JAMA Intern Med
January 2025
Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada.
Importance: The optimal antiviral drug for treatment of nonsevere influenza remains unclear.
Objective: To compare effects of antiviral drugs for treating nonsevere influenza.
Data Sources: MEDLINE, Embase, CENTRAL, CINAHL, Global Health, Epistemonikos, and ClinicalTrials.
Chem Biodivers
December 2024
Department of Biochemistry, Government College Women University, Faisalabad, Pakistan.
The current study was conducted to characterize the vinegar extract of Nigella sativa and evaluate its biological activities using in vitro and in vivo studies. The N. sativa extract (NSE) was prepared by macerating seeds in a mixture of water and synthetic vinegar (1:10).
View Article and Find Full Text PDFDalton Trans
January 2025
State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430200, China.
The quest for novel nonlinear optical (NLO) polymorphs is pivotal for advancing laser technology and frequency conversion applications. We present a detailed study on the synthesis and properties of the 2 polymorph of CHNOZn, which exhibits an enhanced second harmonic generation (SHG) effect, 0.3 times that of KDP, nearly 8-fold higher than the 422 phase.
View Article and Find Full Text PDFCureus
December 2024
Department of Environmental Health Engineering, Faculty of Public Health, Sri Ramachandra Institute of Higher Education and Research (Deemed to be University), Chennai, IND.
Background Chronic kidney disease (CKD) is prevalent in India, particularly among underprivileged populations. Government initiatives such as the Dr. YSR Aarogyasri Health Insurance Scheme aim to provide affordable healthcare to economically impoverished individuals with kidney diseases.
View Article and Find Full Text PDFBackground And Aims: We evaluated the association between endoscopic outcomes following risankizumab induction and subsequent rates of hospitalization and surgery through 52 weeks of risankizumab (both doses) maintenance therapy in patients with Crohn's disease (CD).
Methods: Patients with moderately to severely active CD and clinical response to 12-week risankizumab induction were rerandomized to continued therapy or drug withdrawal in the phase 3 FORTIFY maintenance trial. Incidence rates (events/100 person-years) of CD-related hospitalization and surgery, and the composite of both, through 52 weeks of maintenance were compared between patients achieving vs not achieving predefined endoscopic outcomes following induction.
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