In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: The observation of intact non-covalent complexes by electrospray ionization mass spectrometry (ESI-MS) hinges on the ability to minimize in-source activation processes that take place during analyte desolvation. We explored the merits of replacing the sampling cone of a standard Z-spray source with a heated capillary that makes the desolvation process slower and more gradual. We employed well-characterized protein-RNA, RNA-RNA, and DNA-DNA assemblies to compare the alternative configurations.', 'Mass analysis evaluated the integrity of the complexes, whereas traveling wave ion mobility experiments assessed the stability of biomolecular structure. Analyses were performed back-to-back on the same samples on a Synapt G2 HDMS equipped with either the standard sampling cone or the heated-capillary apparatus. In each configuration, the source/capillary temperature was varied in controlled fashion, while keeping all other desolvation parameters constant to monitor the in-source dissociation of selected DNA duplexes. Ion mobility data were obtained from the same precursor by using the alternative configurations under the same settings.', 'Monitoring the percentage of associated complex demonstrated that the heated capillary provided softer desolvation that was more conducive to the detection of intact non-covalent interactions. This configuration failed to produce complete dissociation of 14bp and 24bp duplexes, even when the source/capillary temperature was increased well above their solution melting points. Analyzed by IMS-MS, a selected construct displayed just one conformation with the heated capillary, but two with the standard sampling cone.\Question: Does a simple heated-capillary modification improve the analysis of non-covalent complexes by Z-spray electrospray ionization?
The heated capillary minimizes in-source activation processes that can lead to unintended dissociation of complexes and perturbation of biomolecular structure, which rely on the integrity of non-covalent interactions. This effect can be attributed to the attenuation of the supersonic expansion typical of the Z-spray geometry and the greater ability to control the energy imparted to the system. This hardware modification will be expected to benefit the analysis of biomolecular structure performed on this particular instrumental platform.

Context: Nonviral vectors based on polyethylenimine (PEI) usually contain an excess of PEI that is not complexed to DNA. Since unbound PEI contributes to cellular and systemic toxicity, purification of polyplexes from unbound PEI is desirable.', 'Size exclusion chromatography (SEC) was used to purify PEI polyplexes of free PEI. Transfection properties of purified polyplexes and the effect of free PEI on gene delivery were studied in vitro and in vivo after systemic application into mice.', 'SEC did not change the size and zeta-potential of polyplexes. Independent of the amount of PEI used for complex formation, purified PEI polyplexes had the same final PEI nitrogen/DNA phosphate ratio of 2.5. Notably, purified PEI polyplexes demonstrated low cellular and systemic toxicity. High transfection efficiency was achieved with purified polyplexes at high DNA concentrations (8-15 microg/ml). At low DNA concentrations (2-4 microg/ml) gene transfer with purified particles was less efficient than with polyplexes containing free PEI both in vitro and in vivo. Mechanistic studies showed that free PEI partly blocked cellular association of DNA complexes but was essential for the following intracellular gene delivery. Adding free PEI to cells treated with purified particles with a delay of up to 4 h resulted in significantly enhanced transfection efficiency compared with non-purified particles or purified particles without free PEI.\Question: Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?
This study presents an efficient method to remove free PEI from PEI polyplexes by SEC. Our results from transfection experiments demonstrate that free PEI substantially contributes to efficient gene expression but also mediates toxic effects in a dose-dependent manner. Purified polyplexes without free PEI have to be applied at increased concentrations to achieve high transfection levels, but exhibit a greatly improved toxicity profile.

Context: Determining the reasons people choose to study nursing may help educators and managers develop student-focussed and enticing nursing programmes. In Australia, little research has been undertaken with students entering nursing programmes and the reasons for their choice.', 'The aim of this study was to determine why new students choose to enter nursing at university.', 'A descriptive survey design.', 'An urban university in Sydney, Australia.', 'Undergraduate nursing students at the beginning of their first year of study.', "An open-ended question relating to the reasons for students' choice of a nursing programme was included in the survey. The transcribed textual data were content analysed for words related to the students' choice.", "The students' reasons for entering nursing programmes were both personal and career related, with personal being more dominant. The reasons to start nursing were: being able to help and care for people, job security, the ability to enter tertiary education and the enjoyment or love of nursing.\Question: Do the reasons students choose to undertake a nursing degree?
Nursing remains a career of choice for young and mature students entering university. It is seen to provide security, interest and opportunity to help and care for others. Universities must focus on this as they develop programmes for a generation where multiple changes of career appear inevitable during their lifetime. The nursing profession needs to look at career pathways after graduation that provide these challenges within nursing itself.