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Charge reduction reactions are important for native mass spectrometry (nMS) because lower charge states help retain native-like conformations and preserve noncovalent interactions of protein complexes. While mechanisms of charge reduction reactions are not well understood, they are generally achieved through the addition of small molecules, such as polyamines, to traditional nMS buffers. Here, we present new evidence that surface-active, charge reducing reagents carry away excess charge from the droplet after being emitted due to Coulombic repulsion, thereby reducing the overall charge of the droplet. Furthermore, these processes are directly linked to two mechanisms for electrospray ionization, specifically the charge residue and ion evaporation models (CRM and IEM). Selected protein complexes were analyzed in solutions containing ammonium acetate and selected trialkylamines or diaminoalkanes of increasing alkyl chain lengths. Results show that amines with higher surface activity have increased propensities for promoting charge reduction of the protein ions. The electrospray ionization (ESI) emitter potential was also found to be a major contributing parameter to the prevalence of charge reduction; higher emitter potentials consistently coincided with lower average charge states among all protein complexes analyzed. These results offer experimental evidence for the mechanism of charge reduction in ESI and also provide insight into the final stages of the ESI and their impact on biological ions.

Objectives: To provide ultrasound baselines for spleen length in homozygous sickle cell disease (HbSS) and in normal controls with a HbAA genotype. Methods: The Jamaican cohort study identified 311 babies with HbSS and 246 matched HbAA controls during the screening of 100,000 consecutive deliveries in Kingston, Jamaica from 1973 to 1981. Ultrasonography commenced in 1988 when the youngest patients were aged 6 years at which time deaths, emigrations and default had reduced the numbers to 206 HbSS and 89 controls. It continued annually until 2000. Results: The spleen was visualized in all HbAA controls but in only 1103/2138 (52%) scans in HbSS. Where available, mean splenic lengths were significantly lower in HbSS (77–103 mm in males, 70–83 mm in females) compared to normal controls (89–101 mm in males, 86–95 mm in females). Assessed by statistical modelling after adjusting for body height, the splenic ratio (splenic length/body height) declined over the age range 12–20 years in HbSS, consistent with progressive splenic fibrosis. Genetic factors known to inhibit sickling, α thalassemia and fetal hemoglobin level (HbF) significantly reduced the decline in splenic ratio. Clinical splenomegaly was an insensitive measure of splenic enlargement as only 50% of patients aged 18 years and above with spleens measuring ≥150 mm on ultrasonography had palpable spleens. Conclusions: An age-related decline in splenic length occurred in HbSS and occurred more slowly with genetic factors known to inhibit sickling. The standards provided may be of value in assessing minor degrees of subclinical acute splenic sequestration. Advances in knowledge These are the first standards available for splenic length in HbSS. They may be useful in detecting red cell sequestration, not apparent from clinical splenomegaly and also provide a model for identifying factors inhibiting vaso-occlusion.

In radially staged lean direct injection (LDI) systems, pilot fuel plays an important role in cooling the mains fuel gallery in regions of the flight envelope where the mains fuel is stagnant. Under these conditions, managing wetted wall temperatures is vital to avoid the formation of carbonaceous particles, which become deposited on the surfaces of the fuel gallery and can lead to a deterioration in system performance. The prediction of wetted wall temperatures therefore represents an important aspect of the injector design phase. Such predictions are often based on injector thermal models, which tend to rely on the application of convective boundary conditions from empirical heat transfer correlations. The use of these correlations leads to questions over the accuracy of predicted wetted wall temperatures and therefore uncertainty over the probability of deposition. This paper seeks to improve on the current situation by applying the inverse conduction technique to determine heat transfer coefficients (HTCs) specific to the pilot fuel gallery. These HTCs are crucial for determining wetted wall temperatures in the pilot and mains fuel galleries and principally govern the risk of deposition in the stagnant mains. The pilot heat transfer data are further examined alongside measurements of the pilot residence time distribution, which together control the risk of pilot deposition at low fuel flow rates. Both the heat transfer and residence time measurements demonstrate the opportunity for future fuel gallery design refinement and provide the supporting data to facilitate this.