Controlled low-temperature molecular manipulation of sexiphenyl molecules on Ag(111) using scanning tunneling microscopy

A novel scanning tunneling microscope manipulation scheme for a controlled molecular transport of weakly adsorbed molecules is demonstrated. Single sexiphenyl molecules adsorbed on a Ag(111) surface at 6 K are shot towards single silver-atoms by excitation with the tip. To achieve atomically straight shooting paths, an electron resonator consisting of linear standing wave fronts is constructed. The sexiphenyl manipulation signals reveal a pi-ring flipping as the molecule moves from hcp to fcc site. Abinitio calculations show an incorporation of the Ag atom below the center of a pi-ring.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let

X-ray Spectroscopy of a Rare-Earth Molecular System Measured at the Single Atom Limit in Room Temperature

We investigate the limit of X-ray detection at room temperature on rare-earth molecular films using lanthanum and a pyridine-based dicarboxamide organic linker as a model system. Synchrotron X-ray scanning tunneling microscopy is used to probe the molecules with different coverages on a HOPG substrate. X-ray-induced photocurrent intensities are measured as a function of molecular coverage on the sample allowing a correlation of the amount of La ions with the photocurrent signal strength. X-ray absorption spectroscopy shows cogent M4,5 absorption edges of the lanthanum ion originated by the transitions from the 3d3/2 and 3d5/2 to 4f orbitals. X-ray absorption spectra measured in the tunneling regime further reveal an X-ray excited tunneling current produced at the M4,5 absorption edge of La ion down to the ultimate atomic limit at room temperature.Comment: 19 pages, 4 figure

One-Dimensional Lateral Force Anisotropy at the Atomic Scale in Sliding Single Molecules on a Surface

Using a q+ atomic force microscopy at low temperature, a sexiphenyl molecule is slid across an atomically flat Ag(111) surface along the direction parallel to its molecular axis and sideways to the axis. Despite identical contact area and underlying surface geometry, the lateral force required to move the molecule in the direction parallel to its molecular axis is found to be about half of that required to move it sideways. The origin of the lateral force anisotropy observed here is traced to the one-dimensional shape of the molecule, which is further confirmed by molecular dynamics simulations. We also demonstrate that scanning tunneling microscopy can be used to determine the comparative lateral force qualitatively. The observed one-dimensional lateral force anisotropy may have important implications in atomic scale frictional phenomena on materials surfaces

Trend of Human Papillomavirus Genotypes in Cervical Neoplasia Observed in a Newly Developing Township in Yangon, Myanmar

Persistent infection with oncogenic types of human papillomavirus (HPV) is the most important risk factor associated with cervical cancer. This study detected the oncogenic HPV genotypes in cervical neoplasia in relation to clinicopathological findings using a cross-sectional descriptive method in 2011 and 2012. Cervical swabs and colposcopy-directed cervical biopsy tissues were collected from 108 women (median age 45 years;range 20-78) showing cervical cytological changes at Sanpya General Hospital, Yangon, Myanmar. HPV DNA testing and genotyping were performed by polymerase chain reaction and restriction fragment length polymorphism. HPV was identified in women with cervical intraepithelial neoplasia (CIN) 1 (44.4%), CIN2 (63.2%), CIN3 (70.6%), and squamous cell carcinoma (SCC) (74.1%). The association between cervical neoplasia and HPV positivity was highly significant (p＝0.008). Most patients infected with HPV were between 40-49 years of age, and the youngest were in the 20- to 29-year-old age group. The most common genotype was HPV 16 (65.6%) with the following distribution:70% in CIN1, 41.7% in CIN2, 91.7% in CIN3, and 60% in SCC. HPV-31 was the second-most frequent (21.9%):30% in CIN1, 33.3% in CIN2, 8.3% in CIN3, and 15% in SCC. The third-most frequent-genotype was HPV-18 (7.8%):8.3% in CIN1, and 20% in SCC. Another genotype was HPV-58 (4.7%):16.7% in CIN1 and 5% in SCC. The majority of CIN/SCC cases were associated with HPV genotypes 16, 31, 18, and 58. If oncogenic HPV genotypes are positive, the possibility of cervical neoplasia can be predicted. Knowledge of the HPV genotypes distribution can predict the effectiveness of the currently used HPV vaccine

NSS5/SP-STM2 Joint International Conference

The NSS5/SP-STM2 conference was held in Athens, Ohio July 15-19, 2008. The conference brought together a prestigious group of scientists from all over the globe to focus for 3 ½ days on a variety of nanoscience topics, particularly on nanoscale spectroscopy and spin-polarized scanning tunneling microscopy. The conference was attended by many young scientists as well as senior scientists. Attendees to the conference were drawn from more than 10 countries and included 28 invited speakers, who are the leading scientists in their respective research areas. Included among the invited speakers were 4 plenary speakers - eminent scientists in their fields. The conference was divided into two parallel sessions – the NSS5 session and the SP-STM2 session