RESUMEN
Functional nanoparticles encapsulated within metal-organic frameworks (MOFs) as an emerging class of composite materials attract increasing attention owing to their enhanced or even novel properties caused by the synergistic effect between the two functional materials. However, there is still no ideal composite structure as platform to systematically analyze and evaluate the relation between the enhanced catalytic performance of composites and the structure of MOF shells. In this work, taking RhCoNi ternary alloy nanoflowers, for example, first the RhCoNi@MOF composite catalysts sheathed with different structured MOFs via a facile self-sacrificing template process are successfully fabricated. The structure type of MOF shells is easily adjustable by using different organic molecules as etchant and coordination reagent (e.g., 2,5-dihydroxyterephthalic acid or 2-methylimidazole), which can dissolve out the Co or Ni element in the alloy template in a targeted manner, thereby producing ZIF-67(Co) or MOF-74(Ni) shells accordingly. With the difference between the two MOF shells in the aperture sizes, the as-prepared two RhCoNi@MOF composites preform distinct size selectivity during the alkene hydrogenation. This work would help us to get more comprehensive understanding of the intrinsic role of MOFs behind the enhanced catalytic performance of nanoparticle@MOF composites.
RESUMEN
Noble metal nanoparticles embedded in metal-organic frameworks (MOFs) are composite catalysts with enhanced or novel properties compared to the pristine counterparts. In recent years, to determine the role of MOFs during catalytic process, most studies have focussed on the confinement effect of MOFs, but ignored the structural flexibility of MOFs. In this study, we use two composite catalysts, Pt@ZIF-8 [Zn(mIM)2 , mIM=2-methyl imidazole] with flexible structure and Pt@ZIF-71 [Zn(DClIM)2 , DClIM=4,5-dichloroimidazole] with rigid structure, and hydrogenation of cinnamaldehyde as model reaction, to show the confinement effect and the structure flexibility of MOF matrices on the catalytic performance of composite catalysts. Both catalysts showed high selectivity for cinnamic alcohol with the confinement effect of the aperture. But, compared to Pt@ZIF-71, Pt@ZIF-8 exhibited higher conversion but lower selectivity owing to the flexible structure. The above results remind us that we will have to consider both the aperture size of MOFs and structure flexibility to select the proper MOF matrices for the composite materials to achieve the optimized performance.
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There is no consensus on how to establish models of osteonecrosis of the femoral head (ONFH) in large mammals. The aim of this study was to investigate the effectiveness of a novel canine model of ONFH, induced by a navigated injection of absolute ethanol. Using three-dimensional reconstruction and rapid prototyping manufacturing techniques, a new template was designed and processed to navigate the ethanol injection. The femoral heads of 18 adult dogs were injected with ethanol. Macroscopic, X-ray and histological examinations were performed at 3, 6, and 9 weeks after the operation. Further, computed tomography (CT), magnetic resonance imaging (MRI), and radionuclide scans were performed 6 weeks postoperatively. Three weeks after the operation, the femoral heads showed evidence of osteonecrosis including increasing numbers of empty lacunae, decreased hematopoietic cells, and destroyed adipose tissue in the medullary cavity, which increased in severity at the subsequent follow-up evaluations at 6 and 9 weeks. Fractured trabeculae and fibrous tissue were noted 9 weeks postoperatively. Image analysis also revealed evidence of osteonecrosis, such as several osteopenic areas with sclerotic rims on the X-ray, several areas of low bone mineral density with sclerosis on the CT scan, increased uptake of the nuclide species in MRI, and an inhomogeneous long T2 signal on the radioisotopic images. Ethanol injection navigated by our novel template was successful in establishing a canine model of ONFH. This model can be used to test new treatment modalities for human ONFH.
Asunto(s)
Etanol/toxicidad , Necrosis de la Cabeza Femoral/inducido químicamente , Osteonecrosis/inducido químicamente , Animales , Modelos Animales de Enfermedad , Perros , Distribución AleatoriaRESUMEN
Interbody fusion cages made of poly-ether-ether-ketone (PEEK) have been widely used in clinics for spinal disorders treatment; however, they do not integrate well with surrounding bone tissue. Ti-6Al-4V (Ti) has demonstrated greater osteoconductivity than PEEK, but the traditional Ti cage is generally limited by its much greater elastic modulus (110 GPa) than natural bone (0.05-30 GPa). In this study, we developed a porous Ti cage using electron beam melting (EBM) technique to reduce its elastic modulus and compared its spinal fusion efficacy with a PEEK cage in a preclinical sheep anterior cervical fusion model. A porous Ti cage possesses a fully interconnected porous structure (porosity: 68 ± 5.3%; pore size: 710 ± 42 µm) and a similar Young's modulus as natural bone (2.5 ± 0.2 GPa). When implanted in vivo, the porous Ti cage promoted fast bone ingrowth, achieving similar bone volume fraction at 6 months as the PEEK cage without autograft transplantation. Moreover, it promoted better osteointegration with higher degree (2-10x) of bone-material binding, demonstrated by histomorphometrical analysis, and significantly higher mechanical stability (P < 0.01), shown by biomechanical testing. The porous Ti cage fabricated by EBM could achieve fast bone ingrowth. In addition, it had better osseointegration and superior mechanical stability than the conventional PEEK cage, demonstrating great potential for clinical application.
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Trasplante Óseo/instrumentación , Vértebras Cervicales/cirugía , Cetonas/química , Oseointegración , Polietilenglicoles/química , Fusión Vertebral/instrumentación , Titanio/química , Aleaciones , Animales , Benzofenonas , Materiales Biocompatibles , Fenómenos Biomecánicos , Vértebras Cervicales/diagnóstico por imagen , Módulo de Elasticidad , Diseño de Equipo , Femenino , Polímeros , Porosidad , Rango del Movimiento Articular , Ovinos , Factores de Tiempo , Microtomografía por Rayos XRESUMEN
There are a lot of reports and reviews about osteonecrosis of the talus (ONT), yet reports about the animal model of ONT to evaluate proper therapeutic approaches are rarely heard. In our study, a novel animal model was established. Pure ethanol was injected into the cancellous bone of sheep's talus. Macroscopic observation, X-ray, CT and histology were performed at two, four, 12 and 24 weeks postoperatively. It was revealed that the trabeculae of talar head began to change their structure after two weeks postoperatively compared to the normal talus. The ONT was obvious at the end of the fourth week, and their outstanding feature was the damage of trabeculae bone and formation of cavities. CT scans and pathological changes of the subjects all showed characteristics of the early stage of osteonecrosis, also the sections of the specimens confirmed necrosis of tali. By 12 weeks, the phenomenon of necrosis still existed but fibrous tissue proliferated prominently and bone reconstruction appeared in certain area. Most specimens (3/4) got late stage necrosis which presented as synarthrosis in X-ray and mass proliferation of fibrous tissue in histology at the end of 24 weeks. The novel animal model of ONT was successful, and it is inclined to deteriorate without any intervention. The study provides us a new way to evaluate various treatments on ONT in laboratory, which may eventually pave way to clinical applications.
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Osteonecrosis/diagnóstico por imagen , Osteonecrosis/patología , Astrágalo/patología , Animales , Modelos Animales de Enfermedad , Etanol/efectos adversos , Femenino , Osteonecrosis/inducido químicamente , Osteonecrosis/cirugía , Ovinos , Tomografía Computarizada por Rayos XRESUMEN
We present the case of a 55-year-old woman who presented with laboratory studies concerning for acute myeloid leukemia (AML) as well as obstructive cholestasis. In similar previously reported cases, concerns of chemotherapy toxicity exacerbated by liver dysfunction or concerns of untreated, concurrent cholecystitis in a neutropenic patient often delay initiation of chemotherapy for full medical workup. At admission, our patient was started on the cytoreductive agent hydroxyurea. By day 10 of her medical workup, her liver function had improved with total bilirubin levels normalizing. At that time, full-dose 7 + 3 induction with cytarabine and daunorubicin was then initiated.
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This study was undertaken to assess the effect of different surface microtopograph of Ti-Nb-Zr-Sn alloy on the biological behavior and soft tissue integration of rabbits' lacertus fibroblast. The lacertus fibroblasts of Achilles tendon of rabbits were cultured and inoculated on the surface of smooth Ti-flake (control group), and on the surface of sand blast, microgrooves, thread Ti-flakes respectively (3 treatment groups). The cell's growth ratio and attaching status were examined by MTT test and scanning electron microscopy (SEM). The rabbits' lacertus fibroblasts proliferated regularly on the surface of Ti-flakes, and most results of their inter-group comparison showed statistically significant difference (P<0.05), thus indicating the different effects of different surface microtopographs on cell's proliferation; By SEM, the cells were noted to have no obvious directivity on smooth surface; they attached irregularly on the sand blast surface. But in the other two groups, they were oriented regularly along the texture. The cells were almost shuttle-like on the four kinds of surface except for a part of irregular cells on the sand blast surface, and there were plentiful cell-cell junctions. Under high power lens, we found cells with limpid microvilli in the experiment samples. Owing to the cell's fast proliferation and regular attachment in the experiment, we concluded that the regular microgrooved surface was more suitable for meeting the requirement of the soft tissues' physiological function.
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Tendón Calcáneo/citología , Aleaciones/química , Proliferación Celular , Fibroblastos/citología , Titanio/química , Animales , Células Cultivadas , Fibroblastos/ultraestructura , Conejos , Propiedades de SuperficieRESUMEN
BACKGROUND: Anatomical studies show that facial fat is partitioned into distinct compartments, with the nasolabial fat pad in a superficial compartment and the deep medial cheek fat in a deep compartment. Gross morphologic differences may exist between these fat depots, but this has never been established at the cellular level. METHODS: Adipose tissue specimens from nasolabial fat and deep medial cheek fat pads were obtained from 63 cadaveric specimens (38 female and 25 male cadavers) aged 47 to 101 years (mean, 71 years). Thirty-seven cadavers had a normal body mass index (≤25 kg/m) and 26 cadavers had a high body mass index (>25 kg/m). Cross-sectional areas of individual adipocytes were calculated digitally and averaged from histologic sections of the adipose tissue samples. RESULTS: The average adipocyte size of nasolabial fat is significantly (p < 0.0001) larger than that of deep medial cheek fat. The average adipocyte size in both nasolabial and deep medial cheek fat is significantly (p < 0.0001) larger in subjects with high compared with low body mass index. Although the overall average adipocyte size is significantly (p < 0.0001) larger in female than in male subjects, this sexual dimorphism is lost in the nasolabial fat depots of overweight subjects and in the deep medial cheek depots of normal-weight subjects. CONCLUSIONS: The significantly smaller adipocyte size in deep medial cheek fat relative to nasolabial fat in elderly subjects supports the theory that deep and superficial facial fat pads are morphologically different. Future investigation of the metabolic and structural properties of these fat compartments will help us understand the different patterns of volumetric facial aging.
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Adipocitos/citología , Índice de Masa Corporal , Mejilla/anatomía & histología , Caracteres Sexuales , Grasa Subcutánea/citología , Anciano , Anciano de 80 o más Años , Cadáver , Tamaño de la Célula , Disección , Femenino , Humanos , Labio/citología , Masculino , Persona de Mediana Edad , Nariz/citología , RitidoplastiaRESUMEN
Osteonecrosis of the talus (ONT) may severely affect the function of the ankle joint. Most orthopedists believe that ONT should be treated at an early stage, but a concise and effective surgical treatment is lacking. In this study, porous titanium alloy rods were prepared and implanted into the tali of sheep with early-stage ONT (IM group). The curative effect of the rods was compared to treatment by core decompression (DC group). No significant differences in bone reconstruction were observed between the two groups at 1 month after intervention. After 3 months, the macroscopic view of gross specimens of the IM group showed ordinary contours, but the specimens of the DC group showed obvious partial bone defects and cartilage degeneration. Quantitative analysis of the reconstructed trabeculae by micro-CT and histological study suggested that the curative effect of the IM group was superior to that of the DC group at 3 months after intervention. These favorable short-term results of the implantation of porous titanium alloy rods into the tali of sheep with early-stage ONT may provide insight into an innovative surgical treatment for ONT.