Background and Objectives: Snowball sampling is applied when samples with the target characteristics are not easily accessible. This research describes snowball sampling as a purposeful method of data collection in qualitative research. Methods: This paper is a descriptive review of previous research papers. Data were gathered using English keywords, including "review," "declaration," "snowball," and "chain referral," as well as Persian keywords that are equivalents of the following: "purposeful sampling," "snowball," "qualitative research," and "descriptive review." The databases included Google Scholar, Scopus, Irandoc, ProQuest, Science Direct, SID, MagIran, Medline, and Cochrane. The search was limited to Persian and English articles written between 2005 and 2013. Results: The preliminary search yielded 433 articles from PubMed, 88 articles from Scopus, 1 article from SID, and 18 articles from MagIran. Among 125 articles, methodological and non-research articles were omitted. Finally, 11 relevant articles, which met the criteria, were selected for review. Conclusions: Different methods of snowball sampling can be applied to facilitate scientific research, provide community-based data, and hold health educational programs. Snowball sampling can be effectively used to analyze vulnerable groups or individuals under special care. In fact, it allows researchers to access susceptible populations. Thus, it is suggested to consider snowball sampling strategies while working with the attendees of educational programs or samples of research studies.

In this study, a simple and green strategy was reported to prepare bimetallic nanoparticles (NPs) by the combination of zinc oxide (ZnO) and copper oxide (CuO) using Sambucus nigra L. extract. The physicochemical properties of these NPs such as crystal structure, size, and morphology were studied by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), and transmission electron microscopy (TEM). The results suggested that these NPs contained polygonal ZnO NPs with hexagonal phase and spherical CuO NPs with monoclinic phase. The anticancer activity of the prepared bimetallic NPs was evaluated against lung and human melanoma cell lines based on MTT assay. As a result, the bimetallic ZnO/CuO NPs exhibited high toxicity on melanoma cancer cells while their toxicity on lung cancer cells was low.

In this research, silver-doped zinc oxide (SdZnO) nanoparticles (NPs) were synthesized in an environmental-friendly manner. The synthesized NPs were identified by UV-vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Finally, the antimicrobial activity of synthesized ZnO and SdZnO NPs was performed. It was observed that by doping silver, the size of ZnO NPs was changed. By adding silver to ZnO NPs, the antimicrobial effect of ZnO NPs was improved. Antibacterial test against gram-positive bacterium Streptococcus mutants showed that SdZnO NPs with a low density of silver had higher antibacterial activity than ZnO NPs; Therefore, SdZnO NPs can be used as a new antibacterial agent in medical applications.

Background: Nurses form the largest group of burn care treatment team. They have valuable experiences regarding the care of burned patients that needs to be explored. Therefore, the present study was aimed to explain the experiences of nurses who work in the burn unit. Materials and Methods: This qualitative study was conducted in the burn units of Zabol and Zahedan Hospitals in 2018. Accordingly, the data were collected through a semi-structured deep interview with 16 nurses. Purposeful sampling method was used for data collection. The data were analyzed using a thematic analysis approach. Results: The data analysis ultimately led to the development of 4 themes and 16 sub-themes. The extracted themes included burden of burn unit, toil of burn unit as a deal with God, need for continuing the education program, and work-life imbalance. Conclusions: Nurses in burn unit experience many challenges that can affect their job and life, which require special attention of the authorities, their families, and other colleagues. For better patient care, there is a need for up-to-date facilities and training. The hospital managers should pay more attention to the nursing staff of the burn units through increasing staff number, changing the working units, and offering financial and motivational vacations.

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Nurses and policy makers should have special attention to consequences of stress in patients undergoing hemodialysis. It plays an important role to provide a framework for appropriate supportive measures and gives the opportunity for nurses to manage the problems facing these patients. Please cite this paper as: Introduction:Chronic renal failure (CRF) is a common problem in today's world. Patients with hemodialysis are subjected to stress even more severe than others. Objectives: This study aimed to explain patients' perception with hemodialysis about stress exposure and its consequences. Patients and Methods:This study is a qualitative approach based on directed content analysis. The data were collected using semi-structured in-depth interviews with patients treated with hemodialysis. Participants were selected using purposive sampling method and data saturation was reached by conducting 11 interviews so that, the new finding was not added. Data analysis was simultaneously conducted based on Grant's model of the consequence of exposure to stress. The validity and reliability of the data was confirmed using peer review method and results were also confirmed by participants. Results: Four themes, including support, psychological outcomes, adherence to treatment and physical trouble, 12 categories and 33 sub-categories were obtained during data analysis process. According to the results, "support" was added. Conclusion:The results showed that patients, with the help of available supportive resources, confront with the difficulties that lie ahead and reduce the hemodialysis-related stress in themselves. Support resources including; family, medical personnel, similar patients, friends and community resources.

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Thinking about death is one of the most common problems of critically ill patients with COVID-19 in ICUs. Therefore, this study aims to explore the experiences of critically ill patients with COVID-19 about death and dying. This is a descriptive phenomenology approach. Participants in this study had 12 participants who were purposefully selected. The data collection method was semi-structured through interviews. Data were analyzed based on Colaizzi’s approach. Data analysis generated two main themes, including personal, and non-personal; challenge thinking about death, and eight sub-themes. Thinking about the death of critically ill COVID-19 patients is a significant challenge that affects the patient’s health and prolongs the treatment process. Therefore, it should be careful in the patient’s treatment and care program.