Facile fabrication of graphene encapsulating 3d transition metal nanoparticles as highly active and anti-poisoning catalysts for selective hydrogenation of nitroaromatics.

Graphene encapsulating 3d transition metal nanoparticles (Ni, Co, Fe@G) are successfully fabricated through pyrolysis of complexes which are simply prepared via "acid-base reactions" between metal hydroxides and carboxylic acid such as citric acid. In particular, the Ni@G catalyst exhibits outstanding catalytic activity and selectivity (>99%) toward the reduction of various nitroaromatics under mild conditions (1 MPa H2, 60 °C), even in the presence of poisons (CO and thiophene etc.). This "acid-base reactions" based method provides a facile and scalable approach to prepare graphene encapsulating 3d transition metals with wide ranges of applications.

A Magnetically Separable Pd Single-Atom Catalyst for Efficient Selective Hydrogenation of Phenylacetylene.

Selective hydrogenation of alkynes to alkenes plays a crucial role in the synthesis of fine chemicals. However, how to achieve high selectivity and effective separation of the catalyst and substrate while obtaining high activity is the key for this reaction. In this work, a Pd single-atom catalyst is anchored to the shell of magnetic core-shell particles that consist of a Ni-nanoparticles core and a graphene sheets shell (Ni@G) for semi-hydrogenation of phenylacetylene, delivering 93% selectivity to styrene at full conversion with a robust turnover frequency of 7074 h-1 under mild reaction conditions (303 K, 2 bar H2 ). Moreover, the catalyst can be recovered promptly from the liquid phase due to its magnetic separability, which makes it present good stability for enduring five cycles. Experimental and theoretical investigations reveal that H2 and substrates are activated by atomically dispersed Pd atoms and Ni@G hybrid support, respectively. The hydrogenation reaction occurs on the surface of Ni@G via hydrogen spillover from the metal to the support. Such a strategy opens an avenue for designing highly active, selective, and magnetically recyclable catalysts for selective hydrogenation in liquid reaction systems.

[Anterior segmental decompression and double-plate fixation for treatment of skip cervical spondylotic myelopathy].

OBJECTIVE: To evaluate the clinical outcomes and values of anterior segmental decompression and double-plate fixation (ASDDF) for treatment of skip cervical spondylotic myelopathy (SCSM). METHODS: Between June 2005 and June 2008, 17 patients with SCSM were treated with ASDDF. There were 10 males and 7 females with an average age of 58.8 years (range, 41-74 years) and an average disease duration of 9.7 months (range, 6-39 months). According to Japanese Orthopaedic Association (JOA) score system, 2 patients were rated as extreme severe condition, 7 as severe, 7 as moderate, and 1 as mild. MRI images showed 42 affected cervical disc levels, including 26 disc levels with high-intensity intramedullary lesions on T2, 4 with low-intensity intramedullary lesions on T1, and 12 with significant cord compression but no signal change; according to Nagata classification scale, there were 5 abnormal segments at class I, 21 at class II, and 16 at class III. The rate of fusion, the Cobb angle, and the range of motion (ROM) of the cervical spine were measured preoperatively and postoperatively by the X-ray examinations. The improvement of the neurological function was evaluated by the JOA score. RESULTS: The average time of follow-up was 28.6 months (range, 24-58 months). After operation, dysphagia occurred in 2 cases (symptom relief after 1 month), hoarseness in 1 case (symptom relief after 3 months of methylcobalamin treatment), and degeneration of adjacent segments without symptom in 3 cases. The X-ray films showed the fusion rate of 100% at 12 months after operation without displacement, resorption or collapse of bone graft, and without breakage or loosening of plate and screw. The Cobb angles were (13.3 +/- 10.4) degrees preoperatively, (15.8 +/- 10.8) degrees immediately postoperatively, and (15.4 +/- 11.4) degrees at last follow-up; the ROM of the cervical spine were (41.3 +/- 17.4) degrees preoperatively and (23.8 +/- 18.8) degrees at last follow-up; and the JOA scores were 8.2 +/- 2.9 preoperatively, 13.7 +/- 3.0 at 12 months postoperatively, and 13.9 +/- 2.8 at last follow-up. All indexes showed significant differences between before operation and after operation (P < 0.05). The results of JOA scores were excellent in 8 cases, good in 6, fair in 2, and poor in 1 with an average improvement rate of 66.8% (range, 14%-88%) for the neurological function. CONCLUSION: Adequate decompression, high rate of fusion, solid mechanical stability, improvement of total cervical lordosis, and the neurological function can be achieved through ASDDF for treatment of SCSM.