Adding melamine as additives in food products will lead to many diseases and even death. However, the present techniques of melamine detection require time-consuming steps, complicated procedures and expensive analytical apparatus. The fluorescent assay method was facile and highly sensitive. In this work, a fluorescence resonance energy transfer (FRET) system for melamine detection was constructed based on conjugated polymer nanoparticles (CPNs) and gold nanoparticles (AuNPs). The energy transfer efficiency is up to 82.1%, and the system is highly selective and sensitive to melamine detection with a lower detection limit of 1.7 nmol/L. Moreover, the interaction mechanism was explored. The results showed that the fluorescence of CPNs were firstly quenched by AuNPs, and then restored after adding melamine because of reducing FRET between CPNs and AuNPs. Lastly, the proposed method was carried out for melamine detection in powdered infant formula with satisfactory results.

Background Clinical internships are a critical transition period for nursing students to develop into nursing professionals and are essential for the solidification of their professional attitudes. Undergraduate nursing students face multiple sources of severe anxiety that affect their nursing career development during this period. This study aimed to understand the anxiety experienced by undergraduate nursing students in the later period of their internship periods in a Chinese educational context. Methods A descriptive qualitative study was conducted. A purposive sample of 17 undergraduate nursing interns with experiences of anxiety was selected from three teaching hospitals in Hunan Province, China. Data were collected through semi-structured interviews and analyzed using the Colaizzi seven-step method for data analysis. Results Three themes emerged: the sources of perceived anxiety, the psychological journey of coping with anxiety, and suggestions for nursing management and education. The sub-themes for the first theme included career decision dilemmas, competitive pressures for employment, worries about progress of the graduation projects, challenges of the nursing licensure examination, and low self-confidence in clinical competence. The second theme consisted of two sub-themes: negative avoidance and retreat, and positive preparation and response. The third theme consisted of policy support to create more employment opportunities, comprehensive guidance from nursing schools and hospitals, and psychological assistance and counseling. Conclusions This study revealed that undergraduate nursing students were prone to anxiety during the later period of their clinical internships. Specific sources of anxiety encompassed career decision-making, job pursuit, graduation, and licensure examination. Undergraduate nursing students adopted both positive and negative approaches in coping with anxiety during the later period of their clinical internships. Nursing educators and administrators should develop appropriate instructions and support systems to reduce anxiety among undergraduate nursing students.

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