Controlling Internal Pore Sizes in Bicontinuous Polymeric Nanospheres

Complex polymeric nanospheres were formed in water from comb-like amphiphilic block copolymers. Their internal morphology was determined by three-dimensional cryo-electron tomographic analysis. Varying the polymer molecular weight (MW) and the hydrophilic block weight content allowed for fine control over the internal structure. Construction of a partial phase diagram allowed us to determine the criteria for the formation of bicontinuous polymer nanosphere (BPN), namely for copolymers with MW of up to 17?kDa and hydrophilic weight fractions of ?0.25; and varying the organic solvent to water ratio used in their preparation allowed for control over nanosphere diameters from 70 to 460?nm. Significantly, altering the block copolymer hydrophilic–hydrophobic balance enabled control of the internal pore diameter of the BPNs from 10 to 19?nm

The effect of climate change on avian offspring production: A global meta-analysis

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to repro- ductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young

Bicontinuous Nanospheres from Simple Amorphous Amphiphilic Diblock Copolymers

Bicontinuous nanospheres have been observed (although rarely) from a variety of block copolymers with architectural and compositional complexity, and often in the presence of additives. Unlocking key features involved in their formation presents possibilities for bicontinuous aggregates with varied functionality and application. An attractive prospect is the ability to form them from much simpler polymeric structures derived from facile syntheses. To that end, we herein report the formation of bicontinuous aggregates from simple amorphous amphiphilic diblock copolymers of poly(ethylene oxide)-b-poly(n-butyl methacrylate), analogous to our previous report of the same from a semicrystalline comb-like block copolymer. Moreover, we demonstrate that polymorphism can be achieved by altering the relative block proportions and the nonselective cosolvent. We find that the polymeric structure is not the dominating factor in the formation of bicontinuous nanospheres but that the choice of cosolvent for the hydrophilic block appears to have greater influence on determining the end morpholog