Insight into the Dynamic Nature of the Pt-CeO2 Interface in Dry Reforming of Methane.

Single-atom catalysts (SACs) are attractive in one-carbon (C1) chemistry because of their high atom efficiency. However, it is a great challenge for understanding the dynamic roles of SACs under operating conditions. Here, isolated Pt atoms trapped on defective CeO2 surface are investigated by experiments, especially operando techniques, which offers basic understanding of the nature and dynamic evolution of the Pt-CeO2 interface in dry reforming of methane (DRM). The Pt-Olattice configuration is highly active for CH4 dissociation at the expense of the Olattice atoms, which in turn promotes the H-assisted dissociation of CO2. The transformation of Pt atoms between positive and metallic states is driven by the DRM reaction, which is essential for rendering highly efficient catalysis. The dynamic evolution of Pt atoms favors to eliminate the reactive intermediates, such as carbonates and formates. The dynamic nature of the Pt-CeO2 interface in the DRM reaction shows a similar picture to the Yin and Yang transformation in ancient Chinese Tai Ji wisdom.

Nano-Bricks Assembly Toward 1D Metal Oxide Nanorods.

The rational design of hybrid nanocrystals structures facilitates electronic and energetic communication between different component, which can optimize their specific performance. In this study, an efficient approach for building intricate ZnO@h-CoO nanocomposites and their derivatives is presented, based on a lattice-match/mismatch mechanism. Due to the ultra-low lattice mismatch between ZnO and hexagonal CoO (as low as 0.18%), the h-CoO layer enables epitaxial growth on the ZnO templates, and ZnO can also grow epitaxially outside the CoO layer with ease. Similarly, the thickness of the epitaxial layer and the number of alternating layers can be adjusted arbitrarily. In contrast to h-CoO, the growth of cubic crystalline oxides (such as MnO) on ZnO results in the formation of nanoparticles due to a large mismatch index (following the Volmer-Weber models). Interestingly, when h-CoO is introduced as a further component into the MnO/ZnO composite, the cubic crystalline particles on the surface of the ZnO do not disturb the epitaxial growth of the h-CoO, allowing for the formation of nanocomposites with more components. Furthermore, additional units can be added to the nanocomposite further based on the lattice-match/mismatch mechanism, which is analogous to the building nano-bricks.

Electronic Metal-Support Interactions Between CuxO and ZnO for CuxO/ZnO Catalysts With Enhanced CO Oxidation Activity.

Metal-support interaction has been one of the main topics of research on supported catalysts all the time. However, many other factors including the particle size, shape and chemical composition can have significant influences on the catalytic performance when considering the role of metal-support interaction. Herein, we have designed a series of CuxO/ZnO catalysts as examples to quantitatively investigate how the metal-support interaction influences the catalytic performance. The electronic metal-support interactions between CuxO and ZnO were regulated successfully without altering the structure of CuxO/ZnO catalyst. Due to the lower work function of ZnO, electrons would transfer from ZnO to CuO, which is favorable for the formation of higher active Cu species. Combined experimental and theoretical calculations revealed that electron-rich interface result from interaction was favorable for the adsorption of oxygen and CO oxidation reaction. Such strategy represents a new direction to boost the catalytic activity of supported catalysts in various applications.

Detailed formation process of Co@C catalysts and the influence of structural regulation on catalytic properties.

Co@C is a novel class of catalysts with many structural advantages, such as highly dispersed active species, developed pore structure, and special encapsulated structure. Although considerable progress has been made in the development of new Co@C materials, research on the formation mechanism of these materials is lacking. Herein, the overall microcosmic structure of the Co@C catalyst was investigated by systematic characterization. Subsequently, a pseudo in situ method was employed to explore the detailed structure of the Co@C catalyst pyrolyzed at different temperatures. The special carbon environment of materials is essential for synthesizing materials during pyrolysis at high temperatures. Co ions were reduced to Co0 by the surrounding carbon atoms at a high temperature. In return, the surrounding carbon atoms were catalyzed by Co0 particles to form carbon nanotubes. However, with the obstruction of amorphous carbon atoms that are not in contact with Co0, the paths through which the carbon nanotubes move forward formed the porous structure of the catalyst, as well as the graphitic encapsulated structure. Further, the effects of pretreatment conditions on the structure and properties of the Co@C catalyst were studied systematically.

[Ultrasound-guided closed reduction and kirschner wires internal fixation for the treatment of Kilfoyleâ ¡and â ¢ medial condylar fracture of humerus in children].

OBJECTIVE: To explore clinical effectiveness and safety of ultrasound-guided closed reduction and K-wires internal fixation in treating of Kilfoyle Ⅱand Ⅲ medial condylar fracture of humerus in children. METHODS: Clinical data of 32 children with medial condylar fracture of humerus treated with closed reduction and internal fixation with K-wires under the guidance of ultrasound were retrospectively analyzed from January 2014 to August 2019, including 23 males and 9 females, age ranged from 3.2 to 12.8 years old with an average of (8.3±2.1) years old;According to classification of Kilfoyle, 12 patients classified to typeⅡ and 20 patients were type Ⅲ;5 patients combined with elbow dislocation;the time from injury to operation ranged from 1 to 5 days with an average of (3.1±1.3) days. Radiological evaluation of treatment results and complications were observed. At the final follow up, Mayo elbow performance score(MEPS) was used to evaluate elbow function. And humerus-ulna angle on the affect side and healthy side were measured and compared. RESULTS: All patients were followed up from 8 to 26 months with an average of(19.3±5.5) months. All fractures were healed well, the healing time ranged from 4 to 6 weeks with an average of (4.5±0.5) weeks. No infection, vascular and nerve injury, bone nonunion, trochlear necrosis, cubitus varus or valgus deformity were occurred. According to Mayo scoring, all patients were assessed as excellent. There was no significant difference in angle of humerus-ulna between affectedside (9.5±3.6)° and healthy side (9.1±3.5)°, and no difference in MEPS scores between affected side(95.3±2.5) and healthy side(96.3±2.2)(P>0.05). CONCLUSION: For Kilfoyle typeⅡand Ⅲ medial condylar fracture of humerus in children, closed reduction and internal fixation with K-wire under ultrasound guidance is a safe and effective method, and could promote in further.

[Progress on femorotibial mechanical axis of total knee arthroplasty].

Femorotibial mechanical axis (FTMA) is one of important factors influencing clinical effect after total knee arthroplasty (TKA). It is generally believed that the range of lower limb alignment after TKA is controlled within neutral FTMA ± 3 °, which has more advantages in improving joint function, prolonging prosthesis survival rate and reducing revision rate, and obtain better clinical results. Therefore, neutral FTMA is also considered to be the gold standard for TKA. However, with the application of computer-assisted surgery and other technologies, the alignment of FTMA is more accurate than before, but the clinical effect after surgery has not significantly improved. Some scholars have begun to question the necessity of neutral alignment of FTMA, and proposed alignment methods such as kinematics and retained residual deformity, which could achieve better clinical effects. In recent years, it has been reported that FTMA might not be the most important factor influencing postoperative clinical effects, and it is suggested that the arrangement and measurement of lower limbs and the effects on adjacent joint functions could affect clinical effect after TKA. The paper reviews neutral FTMA alignment is still an important factor for success of TKA. After a thorough evaluation according to the patient's condition, it should be appropriately applied in the case of neutral FTMA alignment; the operator should explore other factors which affect clinical outcome after TKA, and improve it to achieve the best therapeutic effect.

Insight into the Influence of the Graphite Layer and Cobalt Crystalline on a ZIF-67-Derived Catalyst for Fischer-Tropsch Synthesis.

Due to the special framework structure, ZIF-67 is a promising material as the precursor to prepare the Co@C catalysts with high cobalt loading and superior cobalt dispersion. Unfortunately, these Co@C-X catalysts exhibit not only unsatisfied activity but also high CH4 selectivity. This limited its further application due to the lack of in-depth analysis of the reasons behind it. In this work, the Co@C-X catalysts were prepared by pyrolyzing the ZIF-67 precursor at different temperatures. A series of characterizations were conducted to explore the behavior of the graphite carbon coated on cobalt species, realizing that the role of active Co sites on these Co@C catalysts was restricted by the graphite carbon layer since it suppressed the adsorption and activation of syngas on Co sites. TEOS was introduced to suppress the aggregation of cobalt species and more active sites were exposed after the graphite carbon layer was eliminated. As a result, the FTS performance was greatly improved by a factor of 5. The effect of O2 concentration on the microcrystalline size of Co and the reconfinement effect of SiO2 were investigated. The model catalyst was prepared and the key factors determining CH4 selectivity of the ZIF-67-derived Co@C catalyst were revealed. This provides a good basis for rational designing ZIF-67-derived Co-based FTS catalysts.

Stabilization of ε-iron carbide as high-temperature catalyst under realistic Fischer-Tropsch synthesis conditions.

The development of efficient catalysts for Fischer-Tropsch (FT) synthesis, a core reaction in the utilization of non-petroleum carbon resources to supply energy and chemicals, has attracted much recent attention. ε-Iron carbide (ε-Fe2C) was proposed as the most active iron phase for FT synthesis, but this phase is generally unstable under realistic FT reaction conditions (> 523 K). Here, we succeed in stabilizing pure-phase ε-Fe2C nanocrystals by confining them into graphene layers and obtain an iron-time yield of 1258 µmolCO gFe-1s-1 under realistic FT synthesis conditions, one order of magnitude higher than that of the conventional carbon-supported Fe catalyst. The ε-Fe2C@graphene catalyst is stable at least for 400 h under high-temperature conditions. Density functional theory (DFT) calculations reveal the feasible formation of ε-Fe2C by carburization of α-Fe precursor through interfacial interactions of ε-Fe2C@graphene. This work provides a promising strategy to design highly active and stable Fe-based FT catalysts.

Role of well-defined cobalt crystal facets in Fischer-Tropsch synthesis: a combination of experimental and theoretical studies.

Pure-phase cobalt nanocrystals with well-defined specific exposed facets were synthesized via controllable reduction of their CoO counterparts while retaining the same scale of particle size. Three different catalysts, i.e. hexagonal close-packed (hcp) Co pyramid with (10-11) and rodlike with (10-10) facets, as well as face-centred cubic (fcc) Co octahedron with (111) exposed were obtained and studied for Fischer-Tropsch synthesis (FTS) reaction. No noticeable changes of either the shape or the exposed facets were found under practical FTS reaction conditions. The hcp (10-11) facet exhibits the highest FTS activity and C5+ product selectivity with the lowest apparent activation energy and CH4 selectivity. Theoretical calculations of the energy barrier for CO dissociation and methanation of the reaction intermediate CHx rationalize the experimental results.

[Research progress on clinical diagnosis and treatment for external snapping hip].

External snapping hip(ESH) is a vague term used to describe palpable or auditory snapping with hip movements with or without pain. The pathogenesis of ESH is related to the specific anatomical structure and friction factor. The clinical symptom is auditory snapping during activities, physical examination, X-ray, magnetic resonance imaging(MRI), dynamic ultrasound and other imaging techniques can be used to diagnose. Conservative medical management includes rest, avoidance of aggravating activities, and antiinflammatory medications. Treatment Patients with mild symptoms can achieve good results by medication, rest and physiotherapy. Surgical treatment for patients with ineffective conservative treatment was performed. All kinds of open surgery method can achieve good clinical curative effect, arthroscopic surgery is gradually been promoted due to small trauma, less complications. Besides, there are some reports that traditional treatments such as massage, acupuncture and acupotomology have achieved good clinical results, which deserve further study and promotion.

[Experimental study on preventive effect of Yougui drink on femoral head necrosis in rats under micro CT].

OBJECTIVE: To explore the preventive effect of Yougui drink on femoral head necrosis in rats under micro CT. METHODS: Twenty-five SD rats were divided into steroid hormone group (group A, 10 rats ), Yougui drink group (group B,10 rats) and normal group (group C,5 rats)with random number table. Endotoxin were injected into abdominal cavity of rats in group A and B for 2 days, methylprednisolone sodium succinate were injected by gluteus for twice a week continued for 6 weeks; group B were gavaged by Yougui drink (veryday for 8 weeks; group C did not do any processing. All rats were killed on the 10th weeks,m icro CT were used to scan femoral head in vitro and preventive effect of Yougui drink (n femoral head necrosis in rats. RESULTS: There was statistical significance in BMD, BV/TV, Tb.N, Tb, Th, Thb, Sp, BS/TV and DA but no significance in SMI between group A and B. Comparison between A and C, there was significant meaning in BMD, BV/TV, Tb.N, Tb, Th, Tb, Sp, BS/TV, DA and SMI. CONCLUSION: Yougui drink on femoral head necrosis in rats under micro CT has preventive effect from BMD BV/TV, Tb.N, Tb, Th, Tb, Sp, BS/TV and DA.