The human eye wavefront aberrator based on the Shack-Hartmann wavefront sensor (SHWFS) has become a common device for detecting eye aberrations in modern ophthalmology clinics. In order to eliminate the problem of spot and subaperture matching in traditional methods, we use deep learning method to directly map Hartmann spot pattern and corresponding Zernike coefficient, so as to expand the dynamic range of measurement. The lightweight network realizes to fully extract high dimensional feature information and achieves high precision measurement of diopter and astigmatism. The experimental results show that the proportion of the network falling into the tolerant error range (±0.25D) in diopter and astigmatism measurement reaches 94.2% and 100%. This method can measure the low order aberrations of human eyes effectively without changing the SHWFS setting, and at the same time ensure the accuracy and dynamic range, which has been verified by the real machine.
DNA methylation is one of the earliest known modification pathways, and it regulates gene expression, which in turn influences many biological processes. Direct, label-free detection of DNA methylation with high sensitivity remains a great challenge. Surface-enhanced Raman scattering (SERS), a non-invasive and label-free vibration spectroscopy technique, offers sensitive intrinsic chemical information that makes it an attractive option for DNA analysis. In this study, we employed iodide-modified silver nanoparticles to generate highly consistent SERS signals of DNA at micromolar concentrations in aqueous solutions. This enabled the acquisition of single-base sensitive DNA fingerprint details pertaining to base methylations (such as 5-methylcytosine). As a proof of concept, the SER spectra of a DNA and its methylated counterpart were compared and analyzed, resulting in an obvious identification of DNA methylation. In particular, we first designed two DNA sequences, the sole change being that one of the nucleotides, cytosine, is replaced with a 5-methylcytosine. Further SERS experimental study revealed that methylating a single cytosine in the DNA strand caused a subtle but evident alteration in the SERS spectrum. A new Raman peak emerged at 760 cm-1 the Raman peak at 792 cm-1 moved to 790 cm-1, and there was a noticeable drop in the peak intensity ratio between 1572 cm-1 and 1634 cm-1. This approach may provide a novel and easy-to-use tool for the label-free identification of single-molecule DNA mutations or modifications, furthering the advancement of ultra-sensitive genomic research in the future.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.