The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Hypothesis: Poly(methyl methacrylate) (PMMA) latexes in nonpolar solvents are an excellent model system to understand phenomena in low dielectric media, and understanding their internal structure is critical to characterizing their performance in both fundamental studies of colloidal interactions and in potential industrial applications. Both the PMMA cores and the poly(12-hydroxystearic acid) (PHSA) shells of the latexes are known to be penetrable by solvent and small molecules, but the relevance of this for the properties of these particles is unknown. Experiments: These particles can be prepared in a broad range of sizes, and two PMMA latexes dispersed in n-dodecane (76 and 685 nm in diameter) were studied using techniques appropriate to their size. Small-angle scattering (using both neutrons and X-rays) was used to study the small latexes, and analytical centrifugation was used to study the large latexes. These studies enabled the calculation of the core densities and the amount of solvent in the stabilizer shells for both latexes. Both have consequences on interpreting measurements using these latexes. Findings: The PHSA shells are highly solvated (∼85% solvent by volume), as expected for effective steric stabilizers. However, the PHSA chains do contribute to the intensity of neutron scattering measurements on concentrated dispersions and cannot be ignored. The PMMA cores have a slightly lower density than PMMA homopolymer, which shows that only a small free volume is required to allow small molecules to penetrate into the cores. Interestingly, the observations are essentially the same, regardless of the size of the particle; these are general features of these polymer latexes. Despite the latexes being used as a model physical system, the internal chemical structure is complex and must be fully considered when characterizing them

Outcomes of COVID-19 in Patients with CLL: A Multicenter, International Experience.

Given advanced age, comorbidities, and immune dysfunction, CLL patients may be at particularly high risk of infection and poor outcomes related to coronavirus disease-19 (COVID-19). Robust analysis of outcomes for CLL patients, particularly examining effects of baseline characteristics and CLL-directed therapy, is critical to optimally manage CLL patients through this evolving pandemic. CLL patients diagnosed with symptomatic COVID-19 across 43 international centers (n=198) were included. Hospital admission occurred in 90%. Median age at COVID-19 diagnosis was 70.5 years. Median CIRS score was 8 (range 4-32). Thirty-nine percent were treatment-naïve ( watch and wait ) while 61% had received ≥1 CLL-directed therapy (median 2, range 1-8). Ninety patients (45%) were receiving active CLL therapy at COVID-19 diagnosis, most commonly BTK inhibitors (BTKi; n=68/90, 76%). At a median follow-up of 16 days, the overall case fatality rate (CFR) was 33%, though 25% remain admitted. Watch and wait and treated cohorts had similar rates of admission (89% vs. 90%), ICU admission (35% vs. 36%), intubation (33% vs. 25%), and mortality (37% vs. 32%). CLL-directed treatment with BTKi at COVID-19 diagnosis did not impact survival (CFR 34% vs. 35%), though BTKi was held during COVID-19 course for most patients. These data suggest that the subgroup of CLL patients admitted with COVID-19, regardless of disease phase or treatment status, are at high risk of death. Future epidemiologic studies are needed to assess SARS-CoV-2 infection risk, these data should be validated independently, and randomized studies of BTKi in COVID-19 are needed to provide definitive evidence of benefit