Spark Discharge Doping—Achieving Unprecedented Control over Aggregate Fraction and Backbone Ordering in Poly(3-hexylthiophene) Solutions

The properties of semiconducting polymers are strongly influenced by their aggregation behavior, that is, their aggregate fraction and backbone planarity. However, tuning these properties, particularly the backbone planarity, is challenging. This work introduces a novel solution treatment to precisely control the aggregation of semiconducting polymers, namely current-induced doping (CID). It utilizes spark discharges between two electrodes immersed in a polymer solution to create strong electrical currents resulting in temporary doping of the polymer. Rapid doping-induced aggregation occurs upon every treatment step for the semiconducting model-polymer poly(3-hexylthiophene). Therefore, the aggregate fraction in solution can be precisely tuned up to a maximum value determined by the solubility of the doped state. A qualitative model for the dependences of the achievable aggregate fraction on the CID treatment strength and various solution parameters is presented. Moreover, the CID treatment can yield an extraordinarily high quality of backbone order and planarization, expressed in UV–vis absorption spectroscopy and differential scanning calorimetry measurements. Depending on the selected parameters, an arbitrarily lower backbone order can be chosen using the CID treatment, allowing for maximum control of aggregation. This method may become an elegant pathway to finely tune aggregation and solid-state morphology for thin-films of semiconducting polymers

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log10 increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence