Rediscovering the Isospecific Ring-Opening Polymerization of Racemic Propylene Oxide with Dibutylmagnesium

Rediscovering the Isospecific Ring-Opening Polymerization of Racemic Propylene Oxide with Dibutylmagnesiu

Selective Semihydrogenation of Alkynes with N‑Graphitic-Modified Cobalt Nanoparticles Supported on Silica

For the first time N-graphitic-modified cobalt nanoparticles (Co/phen@SiO₂-800) are shown to be active in the semihydrogenation of alkynes to alkenes. Key to success for efficient catalysis is both the modification of the metal nanoparticles by nitrogen-doped graphitic layers and the use of silica as support. Several internal alkynes are converted to the <i>Z</i> isomer in high yields with up to 93% selectivity. In addition, a variety of terminal alkynes, including sensitive functionalized compounds, are readily converted into terminal alkenes. Notably, this non-noble-metal catalyst allows for the purification of alkenes by selective hydrogenation of the corresponding alkyne in the presence of an excess of olefin

The Role of Adsorbed and Lattice Oxygen Species in Product Formation in the Oxidative Coupling of Methane over M₂WO₄/SiO₂ (M = Na, K, Rb, Cs)

MnOx–Na2WO4/SiO2 is one of the best-performing catalysts in the oxidative coupling of methane (OCM) to C2 hydrocarbons (C2H6 and C2H4). The current mechanistic concepts related to the selectivity to the desired products are based on the involvement of crystalline Mn-containing phases, the molten Na2WO4 phase, surface Na–WOx species, and the associated lattice oxygen. Using in situ X-ray diffraction, operando UV–vis spectroscopy, spatially resolved kinetic analysis of product formation in steady-state OCM tests, and temporal analysis of products with isotopic tracers, we show that these phases/species are not categorically required to ensure high selectivity to the desired products. M2WO4/SiO2 (M = Na, K, Rb, Cs) materials were established to perform similarly to MnOx–Na2WO4/SiO2 in terms of selectivity–conversion relationships. The unique role of the molten Na2WO4 phase could not be confirmed in this regard. Our alternative concept is that the activity of M2WO4/SiO2 and product selectivity are determined by the interplay between the lattice oxygen of M2WO4 and adsorbed oxygen species formed from gas-phase O2. This lattice oxygen cannot convert CH4 to C2H6 but oxidizes CH4 exclusively to CO and CO2. Adsorbed monoatomic oxygen species reveal significantly higher reactivity toward overall CH4 conversion and efficiently generate CH3 radicals from CH4. These reactive intermediates couple to C2H6 in the gas phase and are oxidized, to a lesser extent, by the lattice oxygen of M2WO4 to CO and CO2. Adsorbed diatomic oxygen is involved in the direct CH4 oxidation to CO2. The electronegativity of alkali metal in M2WO4 was established to affect the catalyst ability to generate adsorbed oxygen species from O2. This knowledge opens the possibility to influence product selectivity by controlling the coverage by adsorbed and lattice oxygen via reaction conditions or catalyst design

Ex vivo effect of interferon-β1a and methylprednisolone.

<p>Effect of <i>ex vivo</i> treatment of blood mononuclear cells (MNCs, n = 11) with interferon-β1a (IFN-β) and/or methylprednisolone (MP) for 24 hours on surface expression of CD25 and CD71 on CD4+ T cells and expression of <i>FOXP3</i> mRNA.</p

Endogenous and Recombinant Type I Interferons and Disease Activity in Multiple Sclerosis

<div><p>Although treatment of multiple sclerosis (MS) with the type I interferon (IFN) IFN-β lowers disease activity, the role of endogenous type I IFN in MS remains controversial. We studied CD4+ T cells and CD4+ T cell subsets, monocytes and dendritic cells by flow cytometry and analysed the relationship with endogenous type I IFN-like activity, the effect of IFN-β therapy, and clinical and magnetic resonance imaging (MRI) disease activity in MS patients. Endogenous type I IFN activity was associated with decreased expression of the integrin subunit CD49d (VLA-4) on CD4+CD26^high T cells (Th1 helper cells), and this effect was associated with less MRI disease activity. IFN-β therapy reduced CD49d expression on CD4+CD26^high T cells, and the percentage of CD4+CD26^high T cells that were CD49d^high correlated with clinical and MRI disease activity in patients treated with IFN-β. Treatment with IFN-β also increased the percentage of CD4+ T cells expressing CD71 and HLA-DR (activated T cells), and this was associated with an increased risk of clinical disease activity. In contrast, induction of CD71 and HLA-DR was not observed in untreated MS patients with evidence of endogenous type IFN I activity. In conclusion, the effects of IFN-β treatment and endogenous type I IFN activity on VLA-4 expression are similar and associated with control of disease activity. However, immune-activating effects of treatment with IFN-β may counteract the beneficial effects of treatment and cause an insufficient response to therapy.</p> </div

Immune activation and disease activity.

<p>Relapse risk, magnetic resonance imaging disease activity, T cell and dendritic cell activation in blood samples obtained 9–12 hours after an injection of interferon-β in 23 MS patients treated with interferon-β for six months.</p

T cell activation, <i>CXCL10</i> and <i>MX1</i> expression.

<p>The relationship between the percentage of CD4+CD26^high T cells expressing CD49d or CXCR3 and the expression of <i>MX1</i> and <i>CXCL10</i> mRNA in blood mononuclear cells from untreated patients with relapsing-remitting multiple sclerosis was analysed by Spearman rank correlation coefficients (SRCC).</p

T cell activation and relapse risk.

<p>Relationship between CD4+ T cell expression of HLA-DR and relapse risk in 39 patients from whom blood samples were obtained 36–48 hours after an injection of interferon-β. Patients were dichotomized around the median and relapse risk was analysed in Kaplan-Meier plots and with the log-rank test in all patients and in subgroups of patients with a shorter duration of treatment or disease duration.</p

Overview of the patient material.

<p>Overview of the patient material.</p

Coefficient of variation of the healthy controls and the patients.

<p>The plot shows mean coefficient of variation and 95% confidence intervals. After the injection of contrast agent the mean CV for patients was significantly larger than that of controls. This was not the case prior to the injection of contrast agent.</p