The open access article I find in the field of aging is implementing evidence-based interventions in health care: application of the replicating effective programs framework. The article is published in an open access journal Implementation Science.

Implementation Science is from United Kingdom and it is an open access, peer-reviewed online journal, its impact factor is 3.47. The aims of this journal is to publish research relevant to the scientific study of methods to promote the  research findings into routine healthcare in clinical, organisational or policy contexts.

Implementation science is an  interdisciplinary research area, and the journal is not constrained by any particular research method. Articles of high scientific  using the most appropriate methods to produce valid answers to research questions are published in this journal.  In addition, the journal also publish articles describing intervention development, evaluations of the process by which effects are achieved, economic evaluations of implementation, and the role of theory relevant to implementation research and articles that present novel methods for studying implementation processes and interventions.

I think this journal is a good model of open access. All articles published by Implementation Science are free and permanently accessible online immediately after publication. There is no subscription charges or registration barriers. Authors of articles published in Implementation Science are the copyright holders of their articles and have granted to any third party, in advance, the right to use, reproduce or disseminate the article, according to the BioMed Central copyright and license agreement.