Enhancing the energy barrier and hysteresis temperature in two benchtop-stable Ho(iii) single-ion magnets.

The energy barrier and hysteresis temperature in two benchtop-stable D5h-symmetry HoIII single-ion magnets were significantly enhanced via the variation of the halogen anion. The coexistence of a high energy barrier of 418 K and hysteresis temperature of 15 K was observed in the bromide-ion containing HoIII single-ion magnet.

Coercive Fields Above 6†T in Two Cobalt(II)-Radical Chain Compounds.

Lanthanide permanent magnets are widely used in applications ranging from nanotechnology to industrial engineering. However, limited access to the rare earths and rising costs associated with their extraction are spurring interest in the development of lanthanide-free hard magnets. Zero- and one-dimensional magnetic materials are intriguing alternatives due to their low densities, structural and chemical versatility, and the typically mild, bottom-up nature of their synthesis. Here, we present two one-dimensional cobalt(II) systems Co(hfac)2 (R-NapNIT) (R-NapNIT=2-(2'-(R-)naphthyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, R=MeO or EtO) supported by air-stable nitronyl nitroxide radicals. These compounds are single-chain magnets and exhibit wide, square magnetic hysteresis below 14 K, with giant coercive fields up to 65 or 102 kOe measured using static or pulsed high magnetic fields, respectively. Magnetic, spectroscopic, and computational studies suggest that the record coercivities derive not from three-dimensional ordering but from the interaction of adjacent chains that compose alternating magnetic sublattices generated by crystallographic symmetry.

Reversible structural transformation induced switchable single-molecule magnet behavior in lanthanide metal-organic frameworks.

Switchable "on/off" single-molecule magnet (SMM) behavior can be realized in lanthanide metal-organic frameworks (Ln-MOFs) tuned by the temperature-induced change of the coordination geometry of the lanthanide centers.

In Situ Generation of NiO Nanoparticles in a Magnetic Metal-Organic Framework Exhibiting Three-Dimensional Magnetic Ordering.

NiO nanoparticles were in situ formed in a new metal-organic framework (MOF), [Ni3(pyip)2(HCOO)2(H2O)2]n [1; H2pyip = 5-(pyridine-4-yl)isophthalic acid], which was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, transmission electron microscopy, and powder and single-crystal X-ray diffraction. The MOF 1 shows a 3,6-connected three-dimensional rtl topology network with a topological symbol of (4.62)2(42.610.83). Magnetic property studies showed that the combination of NiO nanoparticles within the magnetic MOF leads to the occurrence of long-range magnetic ordering below a critical temperature of 18 K.

Constraining the coordination geometries of lanthanide centers and magnetic building blocks in frameworks: a new strategy for molecular nanomagnets.

Single-molecule magnets (SMMs) and single-chain magnets (SCMs), also known as molecular nanomagnets, are molecular species of nanoscale proportions with the potential for high information storage density and spintronics applications. Metal-organic frameworks (MOFs) are three-dimensional ordered assemblies of inorganic nodes and organic linkers, featuring structural diversity and multiple chemical and physical properties. The concept of using these frameworks as scaffolds in the study of molecular nanomagnets provides an opportunity to constrain the local coordination geometries of lanthanide centers and organize the individual magnetic building blocks (MBBs, including both transition-metal and lanthanide MBBs) into topologically well-defined arrays that represent two key factors governing the magnetic properties of molecular nanomagnets. In this tutorial review, we summarize recent progress in this newly emerging field.

[Analyses of clinical features and efficacy of sudden deafness with vertigo and dizziness].

OBJECTIVE: To investigate the clinical characteristics and the effect of drug treatment for sudden hearing loss with vertigo or dizziness. METHODS: In a prospective, randomized, single blinded randomized multicenter clinical study, patients with sudden deafness, ranging in age from 18 to 65 years old, with a duration less than 2 weeks, and with no any medical treatments were collected. In accordance with the hearing curve, those patients were divided into four types, i.e., low and intermediate frequency descent type; high frequency descent type; fall flat type; and total deafness type. Each type was treated by four different treatment options, according to the unified design of the random table, and randomly selected one of the options for treatment. The efficacy of the patients with sudden deafness with vertigo and dizziness was analyzed statistically after the follow-up for 4 weeks. SPSS 13.0 software was used to analyze the data. RESULTS: In August 2007 to October 2011, 33 hospitals in the country included 1 024 patients with sudden deafness in line with the inclusion criteria, of whom 296 (28.91%) were accompanied by vertigo/dizziness symptoms, 126 were males and 170 were females, with an average age of (41.2 ± 13.5) years old. types of the different audiometric curves of sudden deafness, the occurrence of complete deafness with vertigo/dizziness was the highest (44.93%), followed by flat down type (25.87%), high frequency descent type (21.28%) and low intermediate frequency descent type (18.54%). After the standard treatment, the vertigo and dizziness symptoms of the sudden deafness patients could disappear, and the hearing in each group was obviously improved. The hearing curative effect on patients accompanied by vertigo/dizziness of low frequency and intermediate frequency descent type was the best, and the total efficiency can reach up to 94.74%, with the cure rate of 68.42%; followed by flat type, in which the total effective rate was 80.76%, with the recovery rate of 22.12%; and the effects on patients in high frequency descent type and total deafness type effect were relatively poor, in which the total effective rates were 70.00% (recovery rate of 10.00%) and 65.32% (recovery rate of 5.65%), respectively. The total effective rate of patients with sudden deafness associated with halo had no statistical significance (P > 0.05), in comparison to that of patients without halo; but, the cure rate of patients with no vertigo/dizziness of total deafness and the high frequency decreased patients with sudden deafness was significantly higher than that of vertigo/dizziness patients, with a statistical difference (P < 0.05). CONCLUSIONS: The patients with sudden deafness in each type have a certain proportion of vertigo/dizziness, especially the deaf type. The possibility of hearing complete recovery in patients with vertigo/dizziness was significantly lower than that without vertigo/dizziness.

Noninvasive evaluation of the effect of endolymphatic sac decompression in Ménière's disease using magnetic resonance imaging.

CONCLUSIONS: This study is the first to demonstrate noninvasive evaluation of the effect of endolymphatic sac decompression (ESD) in Ménière's disease using magnetic resonance imaging (MRI). OBJECTIVE: To evaluate the effect of ESD for the treatment of Ménière's disease by applying noninvasive intratympanic gadolinium (Gd) perfusion through the eustachian tube and three-dimensional fluid-attenuated inversion MRI (3D-FLAIR MRI). METHODS: This was a prospective study. 3D-FLAIR MRI was performed with a 3 Tesla unit 24 h after intratympanic administration of Gd through the eustachian tube in five patients with intractable Ménière's disease before and 3 months after ESD, with a 2-year follow-up on the effect of ESD. RESULTS: Gd was present in the perilymph of the inner ear in all the patients, which clearly displayed the endolymphatic space on 3D-FLAIR MRI with a visible borderline between the perilymph and the endolymph. According to the normal values for the endolymphatic space, four of five patients had a ratio of more than 26% in the cochlea, and three of five patients had a ratio of more than 41% in the vestibule preoperatively. All the patients had a ratio of less than 26% in the cochlea and 41% in the vestibule postoperatively. ESD was effective in reducing the incidence and severity of vertigo attacks with significant improvement in 60% of patients.

Comparison of noninvasive evaluation of endolymphatic hydrops in Meniere's disease and endolymphatic space in healthy volunteers using magnetic resonance imaging.

CONCLUSIONS: The comparison of noninvasive standard evaluation of endolymphatic hydrops in Meniere's disease and the endolymphatic space in healthy volunteers using magnetic resonance imaging (MRI) evaluation should be carried out first. OBJECTIVE: To compare the standard evaluation of endolymphatic hydrops in Meniere's disease and the endolymphatic space in healthy volunteers in the cochlea and the vestibule in the same age group by applying noninvasive intratympanic gadolinium (Gd) perfusion through the eustachian tube and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI). METHODS: This was a prospective study. 3D-FLAIR MRI was performed with a 3 Tesla (3 T) unit 24 h after intratympanic administration of Gd through the eustachian tube in 6 patients with medically active and intractable Meniere's disease and 20 healthy volunteers. Pure tone test and tympanometry were performed 24 h before Gd was administered, and 24 h and 1 month after Gd administration. RESULTS: Gd was present in the perilymph of the inner ear, which clearly displayed the endolymphatic space on 3D-FLAIR MRI with a visible borderline between the perilymph and the endolymph. In 45-55-year-old healthy volunteers, the normal value for the endolymphatic space in the cochlea ranged between 8% and 26%, and that in the vestibule was between 20% and 41%. According to the normal value for the endolymphatic space, four of six patients had a ratio of more than 26% in the cochlea; moreover, four of six patients had a ratio of more than 41% in the vestibule. All the patients had a ratio of more than the normal value in the cochlea and/or the vestibule. No significant changes in pure tone test and tympanometry were noted.