Sungkyunkwan University

About: Sungkyunkwan University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Thin film & Graphene. The organization has 28229 authors who have published 56428 publications receiving 1352733 citations. The organization is also known as: 성균관대학교.

Dye-sensitized MoS2 photodetector with enhanced spectral photoresponse.

Abstract: We fabricated dye-sensitized MoS2 photodetectors that utilized a single-layer MoS2 treated with rhodamine 6G (R6G) organic dye molecules (with an optical band gap of 2.38 eV or 521 nm). The proposed photodetector showed an enhanced performance with a broad spectral photoresponse and a high photoresponsivity compared with the properties of the pristine MoS2 photodetectors. The R6G dye molecules deposited onto the MoS2 layer increased the photocurrent by an order of magnitude due to charge transfer of the photoexcited electrons from the R6G molecules to the MoS2 layer. Importantly, the photodetection response extended to the infrared (λ < 980 nm, which corresponded to about half the energy band gap of MoS2), thereby distinguishing the device performance from that of a pristine MoS2 device, in which detection was only possible at wavelengths shorter than the band gap of MoS2, i.e., λ < 681 nm. The resulting device exhibited a maximum photoresponsivity of 1.17 AW–1, a photodetectivity of 1.5 × 107 Jones, and ...

Crystal Structure of a Junction Between B-DNA and Z-DNA Reveals Two Extruded Bases

Abstract: The existence of left-handed DNA (or Z-DNA) was reported in 1979, and marked by a Nature cover. This week's cover story is the determination of the crystal structure of the junction between left-handed DNA and ‘normal’, right-handed DNA or B-DNA. Each time a DNA segment turns to Z-DNA, two of these B–Z junctions are created. Z-DNA often forms transiently during transcription and other physiological processes, then relaxes to the less energetic B form. The three-dimensional structure shows that the junction is very tight, and that a base pair is pushed out of the double helix, one base on each side of the junction. This adjustment maintains the base stacking that is a major stabilizing factor. These displaced bases may be sites for DNA modification. On the cover, a molecule containing a B–Z junction is shown in the centre, with Z-DNA, naturally, to the left and B-DNA to the right. Left-handed Z-DNA is a higher-energy form of the double helix, stabilized by negative supercoiling generated by transcription or unwrapping nucleosomes1. Regions near the transcription start site frequently contain sequence motifs favourable for forming Z-DNA2, and formation of Z-DNA near the promoter region stimulates transcription3,4. Z-DNA is also stabilized by specific protein binding; several proteins have been identified with low nanomolar binding constants5,6,7,8,9. Z-DNA occurs in a dynamic state, forming as a result of physiological processes then relaxing to the right-handed B-DNA1. Each time a DNA segment turns into Z-DNA, two B–Z junctions form. These have been examined extensively10,11,12, but their structure was unknown. Here we describe the structure of a B–Z junction as revealed by X-ray crystallography at 2.6 A resolution. A 15-base-pair segment of DNA is stabilized at one end in the Z conformation by Z-DNA binding proteins, while the other end remains B-DNA. Continuous stacking of bases between B-DNA and Z-DNA segments is found, with the breaking of one base pair at the junction and extrusion of the bases on each side (Fig. 1). These extruded bases may be sites for DNA modification.

Fast Normalized Cross-Correlation

Abstract: Normalized cross-correlation has been used extensively for many signal processing applications, but the traditional normalized correlation operation does not meet speed requirements for time-critical applications. In this paper, a new fast algorithm for the computation of the normalized cross-correlation (NCC) without using multiplications is presented. For a search window of size M and a template of size N the fast NCC requires only approximately 2N?(M?N+1) additions/subtractions without multiplications. Simulation results with 100,000 test signals show that the use of the fast NCC instead of the traditional approaches for the determination of the degree of similarity between a test signal and a reference signal (template) brings about a significant improvement in terms of false negative rate, identification rate and computational cost without a significant increase in false positive rate, especially when the signal-to-noise ratio (SNR) is higher than 3 dB.