The oxidation of 5-hydroxymethyl-2-furfural was studied under mild reaction conditions using TiO2-supported Au and Au-Cu catalysts synthesized from pre-formed nanoparticles. Bimetallic gold-copper ...catalysts display superior activity as compared to monometallic gold. Moreover, after reaction, the bimetallic Au-Cu catalysts can be recovered by filtration and reused without significant loss of activity and selectivity whereas gold materials are not stable. STEM-HAADF imagining and XEDS spectra obtained from bimetallic materials show that particles are homogeneous AuCu alloys. No AuCu ordering or segregation effects were noted from these analyses, and the Au:Cu ratio was quite consistent from particle-to-particle irrespective of its absolute size, proving the efficiency of the original method of synthesis utilized. Isolation effects of gold by copper in the alloy nanoparticles is imagined to play a pivotal role in the reaction. The effect of oxygen pressure, metal loading, reaction time, amount of base and temperature were studied in detail and a 99% yield of furandicarboxylic acid was achieved under optimized reaction conditions.
The direct synthesis of hydrogen peroxide offers a potentially green route to the production of this important commodity chemical. Early studies showed that Pd is a suitable catalyst, but recent work ...indicated that the addition of Au enhances the activity and selectivity significantly. The addition of a third metal using impregnation as a facile preparation method was thus investigated. The addition of a small amount of Pt to a CeO2‐supported AuPd (weight ratio of 1:1) catalyst significantly enhanced the activity in the direct synthesis of H2O2 and decreased the non‐desired over‐hydrogenation and decomposition reactions. The addition of Pt to the AuPd nanoparticles influenced the surface composition, thus leading to the marked effects that were observed on the catalytic formation of hydrogen peroxide. In addition, an experimental approach that can help to identify the optimal nominal ternary alloy compositions for this reaction is demonstrated.
Small change with great effect: The addition of a small amount of Pt to a AuPd/CeO2 catalyst can significantly enhance its performance in the direct synthesis of H2O2. The contour diagram shows the productivity of catalysts with different metal ratios (blue/yellow: low/high productivity).
We report the preparation of Au−Pd nanocrystalline catalysts supported on activated carbon prepared via a sol-immobilization technique and explore their use for the direct synthesis of hydrogen ...peroxide and the oxidation of benzyl alcohol. In particular, we examine the synthesis of a systematic set of Au−Pd colloidal nanoparticles having a range of Au/Pd ratios. The catalysts have been structurally characterized using a combination of UV−visible spectroscopy, transmission electron microscopy, STEM HAADF/XEDS, and X-ray photoelectron spectroscopy. The Au−Pd nanoparticles are found in the majority of cases to be homogeneous alloys, although some variation is observed in the AuPd composition at high Pd/Au ratios. The optimum performance for the synthesis of hydrogen peroxide is observed for a catalyst having a Au/Pd 1:2 molar ratio. However, the competing hydrogenation reaction of hydrogen peroxide increases with increasing Pd content, although Pd alone is less effective than when Au is also present. Investigation of the oxidation of benzyl alcohol using these materials also shows that the optimum selective oxidation to the aldehyde occurs for the Au/Pd 1:2 molar ratio catalyst. These measured activity trends are discussed in terms of the structure and composition of the supported Au−Pd nanoparticles.
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► Preparation of Au and Au–Cu TiO2 supported catalysts from pre-formed nanoparticles. ► Cu presence allowed a remarkable increase of the catalytic behavior. ► Stability of Au–Cu ...catalysts was much higher than that shown by the Au material.
5-Hydroxymethyl-2-furfural (HMF) oxidation to furandicarboxylic acid (FDCA) was performed under mild reaction conditions using TiO2-supported Au and Au–Cu catalysts synthesized from pre-formed nanoparticles of different composition. Catalysts were characterized by BET, XRD and XPS. The Au3Cu1/TiO2 catalyst exhibited the best catalytic performance for FDCA yield. Moreover, after reaction, bimetallic Au–Cu catalysts with high gold content can be recovered by filtration and reused without significant loss of activity and selectivity; whereas, the monometallic gold materials are not stable.
Objectives
(i) To assess the effects of mechanical overloading on implant integration in rat tibiae, and (ii) to numerically predict peri‐implant bone adaptation.
Materials and methods
Transcutaneous ...titanium implants were simultaneously placed into both tibiae of rats (n = 40). After 2 weeks of integration, the implants of the right tibiae were stimulated daily for 4 weeks with loads up to 5N (corresponding to peak equivalent strains of 3300 ± 500 με). The effects of stimulation were assessed by ex vivo mechanical tests and quantification of bone mineral density (BMD) in selected regions of interests (ROIs). Specimen‐specific finite element models were generated and processed through an iterative algorithm to mimic bone adaptation.
Results
Bilateral implantation provoked an unstable integration that worsened when mild (2–4N) external loads were applied. In contrast, a stimulation at 5N tended to “counterbalance” the harmful effects of daily activity and, if applied to well‐integrated specimens, significantly augmented the implants' resistance to failure (force: +73% P < 0.01, displacement: +50% P < 0.01 and energy: +153% P < 0.01). Specimen‐specific numerical predictions were in close agreement with the experimental findings. Both local and overall BMD variations, as well as the implants' lateral stability, were predicted with small errors (0.14 gHA/cm3 and 0.64%, respectively).
Conclusions
The rats' daily activity detrimentally affects implant integration. Conversely, external stimulations of large magnitudes counterbalance this effect and definitively improve integration. These changes can be predicted using the proposed numerical approach.
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder consisting of progressive loss of motor neurons. TDP‐43 has been identified as a component of ubiquitin‐immunoreactive inclusions ...of motor neurons in ALS. We focused on the diffuse cytoplasmic TDP‐43 immunoreactivity in ALS neurons, and quantitatively assessed it in comparison with skein/round TDP‐43 and ubiquitin immunostaining in motor neurons of 30 sporadic ALS cases. The percentage of spinal motor neurons with cytoplasmic TDP‐43 immunoreactivity was higher than that of ubiquitin‐immunoreactive ones. The percentage of TDP‐43‐positive motor neurons was independent of neuron counts in anterior horns, while the percentage of ubiquitinated neurons was inversely correlated. Aiming to define the cytosolic localization of TDP‐43, the immunoblot analysis of spinal cord and frontal cortex showed that full‐length TDP‐43, the 45 kDa form and ubiquitinated TDP‐43 are found in the soluble inclusion‐free fraction. The present data suggest that delocalization, accumulation and ubiquitination of TDP‐43 in the cytoplasm of motor neurons are early dysfunctions in the cascade of the events leading to motor neuron degeneration in ALS, preceding the formation of insoluble inclusion bodies. Being cytoplasmic accumulation an ongoing event during the course of the illness, a therapeutic approach to this incurable disease can be envisaged.
Immediate implant placement required for a narrow mandibular ridge is a serious challenge for clinicians. The present case shows a modification in the split-crest technique that simplifies implant ...placements to avoid the risk of a mal fracture of the buccal cortex.
Sphingolipids are polar membrane lipids present as minor components in eukaryotic cell membranes. Sphingolipids are highly enriched in nervous cells, where they exert important biological functions. ...They deeply affect the structural and geometrical properties and the lateral order of cellular membranes, modulate the function of several membrane-associated proteins, and give rise to important intra- and extracellular lipid mediators. Sphingolipid metabolism is regulated along the differentiation and development of the nervous system, and the expression of a peculiar spatially and temporarily regulated sphingolipid pattern is essential for the maintenance of the functional integrity of the nervous system: sphingolipids in the nervous system participate to several signaling pathways controlling neuronal survival, migration, and differentiation, responsiveness to trophic factors, synaptic stability and synaptic transmission, and neuron-glia interactions, including the formation and stability of central and peripheral myelin. In several neurodegenerative diseases, sphingolipid metabolism is deeply deregulated, leading to the expression of abnormal sphingolipid patterns and altered membrane organization that participate to several events related to the pathogenesis of these diseases. The most impressive consequence of this deregulation is represented by anomalous sphingolipid-protein interactions that are at least, in part, responsible for the misfolding events that cause the fibrillogenic and amyloidogenic processing of disease-specific protein isoforms, such as amyloid β peptide in Alzheimer's disease, huntingtin in Huntington's disease, α-synuclein in Parkinson's disease, and prions in transmissible encephalopathies. Targeting sphingolipid metabolism represents today an underexploited but realistic opportunity to design novel therapeutic strategies for the intervention in these diseases.
NF-κB-inducing kinase (NIK), an oncogenic drug target that is associated with various cancers, is a central signalling component of the non-canonical pathway. A blind screening process, which ...established that amino pyrazole related scaffolds have an effect on IKKbeta, led to a
optimization process that identified the aminopyrazole
as a low μM selective NIK inhibitor. Compound
effectively inhibited the NIK-dependent activation of the NF-κB pathway in tumour cells, confirming its selective inhibitory profile.
The direct synthesis of hydrogen peroxide from molecular H2 and O2 represents a green and economic alternative to the current anthraquinone process used for the industrial production of H2O2. In ...order for the direct process to compete with the anthraquinone process, there is a need for enhanced H2O2 yields and H2 selectivity in the process. We show that Au-Pd-exchanged and supported Cs-containing heteropolyacid catalysts with the Keggin structure are considerably more effective in achieving high H2O2 yields in the absence of acid or halide additives than previously reported catalysts. The Au-Pd-exchanged Cs-heteropolyacid catalysts also show superior H2O2 synthesis activity under challenging conditions (ambient temperature, water-only solvent and CO2-free reaction gas). Au plays a crucial role in achieving the improved performance of these heteropolyacid-based catalysts. The heteropolyacid limits the subsequential hydrogenation/decomposition of H2O2.
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