Polyolefin waste to light olefins with ethylene and base-metal heterogeneous catalysts.

The selective conversion of polyethylene (PE), polypropylene (PP), and mixtures of these two polymers to form products with high volume demand is urgently needed because current methods suffer from low selectivity, produce large quantities of greenhouse gases, or rely on expensive, single-use catalysts. The isomerizing ethenolysis of unsaturated polyolefins could be an energetically and environmentally viable route to propylene and isobutylene; however, noble-metal homogeneous catalysts and an unsaturated polyolefin are currently required and the process has been limited to PE. We show that the simple combination of tungsten oxide on silica and sodium on gamma-alumina transforms PE, PP, or a mixture of the two, including postconsumer forms of these materials, to propylene or a mixture of propylene and isobutylene in greater than 90% yield at 320°C without the need for dehydrogenation of the starting polyolefins.

Palladium-Catalyzed Amination of Aryl Halides with Aqueous Ammonia and Hydroxide Base Enabled by Ligand Development.

The conversion of aryl halides to primary arylamines with a convenient and inexpensive source of ammonia has been a long-standing synthetic challenge. Aqueous ammonia would be the most convenient and least expensive form of ammonia, but such a palladium-catalyzed amination reaction with a high concentration of water faces challenges concerning catalyst stability and competing hydroxylation, and palladium-catalyzed reactions with this practical reagent are rare. Further, most reactions with ammonia to form primary amines are conducted with -butoxide base, but reactions with ammonium hydroxide would contain hydroxide as base.

Chemical Modification of Oxidized Polyethylene Enables Access to Functional Polyethylenes with Greater Reuse.

Polyethylene is a commodity material that is widely used because of its low cost and valuable properties. However, the lack of functional groups in polyethylene limits its use in applications that include adhesives, gas barriers, and plastic blends. The inertness of polyethylene makes it difficult to install groups that would enhance its properties and enable programmed chemical decomposition.

SARS-CoV-2 Infection and Vaccination Outcomes in Multiple Sclerosis.

Background And Objectives: The effects of the SARS-CoV-2 vaccination and infection on clinical outcomes, including relapse risk, have been insufficiently explored in people with multiple sclerosis (PwMS). The objectives of this study were to determine the incidence of new neurologic symptoms or symptom recrudescence among PwMS who received the SARS-CoV-2 vaccine, characterize outcomes after SARS-CoV-2 infection, and assess MS-specific determinants of vaccine hesitancy.

Methods: Online surveys that assessed incidence and severity of SARS-CoV-2 infection, vaccination status/type, reasons for vaccine deferral, and postvaccination symptoms were administered to PwMS.

Delayed Improvement of Left Ventricular Function in Newly Diagnosed Heart Failure Depends on Etiology-A PROLONG-II Substudy.

In patients with newly diagnosed heart failure with reduced ejection fraction (HFrEF), three months of optimal therapy are recommended before considering a primary preventive implantable cardioverter-defibrillator (ICD). It is unclear which patients benefit from a prolonged waiting period under protection of the wearable cardioverter-defibrillator (WCD) to avoid unnecessary ICD implantations. This study included all patients receiving a WCD for newly diagnosed HFrEF ( = 353) at our center between 2012 and 2017.