Search

A manganese-catalyzed radical relay strategy for the remote trifluoromethylation–peroxidation of unactivated alkenes is disclosed. The electrophilic CF3 group was added to the C＝C double bonds to afford remote C-centered radicals upon 1,5-HAT, which could be efficiently trapped by Mnn+1OOBu-t species to deliver 1,6-difunctionalized products selectively under mild conditions. t-BuOOH serves as both the oxidant and the peroxy precursor in this transformation. [ABSTRACT FROM AUTHOR]

Background Context: In the treatment of multiple disc herniations, the decision of whether to include the presumed asymptomatic lumbar disc herniation (asLDH) at adjacent segments remains uncertain. On the one hand, the untouched asLDH might soon become symptomatic and require treatment. On the other hand, additional surgery involving more segments will introduce greater risk, complications, and cost.Purpose: To investigate the prognosis of untreated asLDH after open fusion or percutaneous endoscopic lumbar discectomy (PELD) on symptomatic lumbar disc herniation (LDHs) in patients.Study Design: This is a retrospective cohort study.Patient Sample: A total of 371 patients with multiple disc herniations who underwent open discectomy and fusion or PELD only for symptomatic levels from January 2012 to July 2018 were included.Outcome Measures: The primary outcome of interest was the development of symptomatic LDH at the previous asLDH of both groups that required reoperation. A second analysis was performed to compare the reoperation rate due to deterioration of asLDH among different severity grades of herniation. Reoperation rates of the original surgery at the symptomatic segment in both fusion and PELD groups were also reviewed.Methods: The patients were divided into two groups based on the surgical procedure, with 264 patients undergoing fusion surgery and 107 patients undergoing PELD. Clinical and imaging follow-ups were performed at routine intervals for more than 3 years. The reoperation rates due to deterioration of previously asLDH and failure of original surgery were investigated and compared between the two groups, as well as among the different severity grades of herniation.Results: The follow-up times were 48.2±24.2 and 41.1±17.5 months for the fusion and the PELD groups, respectively. The overall reoperation rate at the previous adjacent asLDH was 6.7% (25/317). According to the severity of the asLDH, a higher grade of asymptomatic herniation yielded a significantly higher rate of reoperation rate in both groups. If the nerve root was displaced by disc material prominently (nG2), the reoperation rate of asLDHs was 42.9% (3/7) in the fusion group and 20% (3/15) in the PELD group. Twenty out of 264 patients (7.6%) in the fusion group and 5 out of 107 patients (4.7%) in the PELD group required reoperation due to deterioration of asLDH. Reoperation rates due to failure of the original surgery were 7.6% (20/264) in the fusion group and 8.4% (9/107) in the PELD group.Conclusions: With multilevel LDHs, if the asLDH is left untreated, the reoperation rate is closely related to the degree of herniation. When confronting an asLDH graded as G2, a high possibility of reoperation should be clearly discussed with the patient, regardless of open fusion or PELD techniques. Considering that fusion and minimally invasive nonfusion techniques did not yield significantly different overall reoperation rates, ongoing degeneration seemed to have a greater contribution in terms of the deterioration of asLDH. [ABSTRACT FROM AUTHOR]

The reasonable control of the dispersion of noble metals is an important topic for heterogeneous catalysts. In this manuscript, PdCu/C, AuCu/C and PdAuCu/C were prepared by the galvanic reduction method to ensure that Pd and Au follow the distribution of Cu nanoparticles. The catalysts were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy‐dispersive spectrometer elemental mappings and lines scans. Both the Pd and Au had very high dispersion no matter whether they were introduced individually or simultaneously. The Pd and Au were distributed mainly on the Cu nanoparticles as evidenced by the energy‐dispersive spectrometer elemental mappings and lines scans. The reduction of 4‐nitrophenol was used as a model reaction for the prepared catalysts. PdCu/C and AuCu/C showed high activity for this reaction compared to the literature, and the activity could be further increased by the introduction of Pd and Au in an appropriate ratio at the same time. The normalized reaction rate reached 2.005 s−1 mM−1 for the PdAuCu/C‐2.0, in which the mole ratio of Pd to Au was 2.0. [ABSTRACT FROM AUTHOR]

The bifunctional organic ligand ((HOOCC5H4NN(CONH(CH2)3Si(OCH2CH3)3)2 (abbreviated as ANA-Si) was synthesized using 5-aminonicotinic acid (ANA) and the silane coupling agent 3-(triethoxysilyl)-propyl isocyanate (TEPIC). Simultaneously, two novel nanocomposites core-shell SiO2/ANA-Si-Dy and core-shell-shell SiO2/ANA-Si-Dy/SiO2 were successfully prepared. The prepared nanocomposites were characterized by Fourier transform infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), high-resolution transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. SEM and TEM analysis indicate that the prepared nanocomposite SiO2/ANA-Si-Dy was a core-shell structure, which formed by SiO2 microspheres core coated with dysprosium organic complex shell. Correspondingly, the core-shell-shell nanocomposite formed by this core-shell nanocomposite coated with a SiO2 layer. The further analysis can be found that the diameters of the SiO2 core, core-shell and core-shell-shell nanocomposites were about 200–205 nm, 220–225 nm and 230–235 nm, respectively. The core-shell-shell nanocomposite was found to have better luminescence intensity and longer lifetime than the core-shell nanocomposite. In addition, the core-shell-shell nanocomposite has excellent luminescence stability in aqueous solution. Therefore, the core-shell-shell nanocomposite with bright luminescence, high stability and long lifetime may present potential applications in the field of biology. [ABSTRACT FROM AUTHOR]

In this paper, novel core–shell (CS) structure composites SiO2@ANA-Si–Eu and SiO2@ANA-Si–Eu–L (L = phen, TTA) were prepared by the condensation of 5-N-bis(amidopropyltriethoxysilyl) nicotinic acid (HOOCC5H4NN(CONH(CH2)3Si(OCH2CH3)3)2, abbreviated as ANA-Si) and a SiO2 microsphere with a diameter of 200 nm in the absence of surfactants. The as-synthesized CS structure composites possess good dispersion, uniform size and excellent luminescence properties. Furthermore, silica modified core–shell–shell (CSS) structure composites SiO2@ANA-Si–Eu@SiO2 and SiO2@ANA-Si–Eu–L@SiO2 were successfully prepared by a sol–gel method using CS structure composites as the core and amorphous silica as the shell. Compared with the CS structure composites, CSS structure composites exhibited a stronger luminescence intensity in the solid state. Furthermore, an improved luminescence stability property of the CSS structure composites was found in aqueous medium. CSS structure composites exhibited improved luminescence, high stability and good solubility, which provided potential for their wide use in advanced phosphors, molecular biomarkers and luminescent tracers. [ABSTRACT FROM AUTHOR]