Experimental Determination of Magnetic Anisotropy in Exchange-Bias Dysprosium Metallocene Single-Molecule Magnets.

We investigate a family of dinuclear dysprosium metallocene single-molecule magnets (SMMs) bridged by methyl and halogen groups [Cp'2 Dy(µ-X)]2 (Cp'=cyclopentadienyltrimethylsilane anion; 1: X=CH3 - ; 2: X=Cl- ; 3: X=Br- ; 4: X=I- ). For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that the orientation of them are perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms. The orientation of the magnetic easy axis for 1 deviates from the normal direction (by 10.3°) due to the stronger equatorial interactions between DyIII and methyl groups. Moreover, its magnetic axes show a temperature-dependent shifting, which is caused by the competition between exchange interactions and Zeeman interactions. Studies of fluorescence and specific heat as well as ab initio calculations reveal the significant influences of the bridging ligands on their low-lying exchange-based energy levels and, consequently, low-temperature magnetic properties.

Comparison of Arthrodesis and Non-fusion to Treat Lisfranc Injuries.

OBJECTIVE: "Lisfranc joint injury" is comprised of a tarsometatarsal joint-complex injury. The Lisfranc complex injury is always a challenge for orthopedists, and the optimum treatment is still up for debate. Anatomic reduction and stable internal fixation prove to have no satisfactory outcomes. This research aims to compare the clinical curative effects, complications and radiographic features of arthrodesis and non-fusion of the Lisfranc joint in the follow-up of the patients who suffered Lisfranc injuries. METHODS: A comparative retrospective study of 25 patients with acute or subacute Lisfranc complex injuries was conducted between September 2013 and March 2015 in the First Affiliated Hospital of Soochow University. All patients were classified by Myerson classification. Eight patients were treated with arthrodesis, while 17 patients received non-fusion operations. The clinical curative effects, complications and image differences were compared between the two groups. American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score, Short Form-36 (SF-36) and Visual Analogue Scale (VAS) score were evaluated for each patient during the follow-up. All statistics were analyzed using the SPSS software system. RESULTS: All fractures healed for both the arthrodesis group and the non-fusion group. Patients in the arthrodesis group had a higher AOFAS score compared with patients in the non-fusion group (94.00 vs. 88.58, P = 0.034). Complications occurred in eight patients (8/17, 47%) in the non-arthrodesis group, including the second and third phalanx abduction (1), talipes cavus (2), eversion deformity of front foot (3), eversion deformity of calcaneus (1), as well as postoperative infection (1). Only two patients (2/8, 25%) in the arthrodesis group suffered complications. One was a limitation of motion of the front foot and pain during walking; the other was an eversion deformity of front foot. CONCLUSION: Primary arthrodesis has advantages compared to primary open reduction and internal fixation (ORIF): reduced foot deformity rates, sustained biomechanical morphology of the feet, reduced complications, higher level of function recovery, shorter time of surgical procedures, fewer complications, higher AOFAS score and fewer frequency of complications. According to our research, primary arthrodesis may be a better choice for treating Lisfranc injury.

Can Non-Kramers Tm(III) Mononuclear Molecules be Single-Molecule Magnets (SMMs)?

In recent years, plentiful lanthanide-based (Tb(III) , Dy(III) , and Er(III) ) single-molecule magnets (SMMs) were studied, while examples of other lanthanides, for example, Tm(III) are still unknown. Herein, for the first time, we show that by rationally manipulating the coordination sphere, two thulium compounds, 1[(Tp)Tm(COT)] and 2[(Tp*)Tm(COT)] (Tp=hydrotris(1-pyrazolyl)borate; COT=cyclooctatetraenide; Tp*=hydrotris(3,5-dimethyl-1-pyrazolyl)borate), can adopt the structure of non-Kramers SMMs and exhibit their behaviors. Dynamic magnetic studies indicated that both compounds showed slow magnetic relaxation under dc field and a relatively high effective energy barrier (111 K for 1, 46 K for 2). Magnetic diluted 1 a[(Tp)Tm0.05 Y0.95 (COT)] and 2 a[(Tp*)Tm0.05 Y0.95 (COT)] even exhibited magnetic relaxation under zero dc field. Relativistic ab initio calculations combined with single-crystal angular-resolved magnetometry measurements revealed the strong easy axis anisotropy and nearly degenerated ground doublet states. The comparison of 1 and 2 highlights the importance of local symmetry for obtaining Tm SMMs.