Atomic-Number (Z)-Correlated Atomic Sizes for Deciphering Electron Microscopic Molecular Images

With the advent of atomic-resolution transmission electron microscopy (AR-TEM) achieving sub-{\AA}ngstrom image resolution and submillisecond time resolution, an era of visual molecular science where chemists can visually study the time evolution of molecular motions and reactions at atomistic precision has arrived. However, the appearance of experimental TEM images often differs greatly from that of conventional molecular models, and the images are difficult to decipher unless we know in advance the structure of the specimen molecules. The difference arises from the fundamental design of the molecular models that represent atomic connectivity and/or the electronic properties of molecules rather than the nuclear charge of atoms and electrostatic potentials that are felt by the e-beam in TEM imaging. We found a good correlation between the atomic number (Z) and the atomic size seen in TEM images when we consider shot noise in digital images. We propose here Z-correlated (ZC) atomic radii for modeling AR-TEM images of single molecules and ultrathin crystals, with which we can develop a good estimate of the molecular structure from the TEM image much more easily than with conventional molecular models. Two parameter sets were developed for TEM images recorded under high-noise (ZCHN) and low-noise (ZCLN) conditions. The new molecular models will stimulate the imaginations of chemists planning to use AR-TEM for their research.Comment: 27 pages, 6 figure

A case of colon lipoma presenting with intussusception

　An 84-year-old man, who had been found to have a submucosal tumor in the ascending colon two years before, was admitted to our hospital for right lower quadrant abdominal pain and melena. An abdominal computed tomography (CT) scan showed intussusception in the ascending colon, resulting from a fat-density tumor. The intussusception was located by colonoscopy. Since the colonic tumor was enlarged in comparison with two years ago and had an ulcer at the top of the tumor, there was the possibility of malignancy and recurrence of intussusception. He underwent a laparoscopy-assisted right colectomy with lymph node dissection. Pathologically, the tumor of the ascending colon was a benign lipoma

A case of appendiceal diverticulum resected by laparoscopic surgery with preoperative diagnosis of appendiceal tumor

　Appendiceal diverticulum is rare. We encountered a case of appendiceal diverticulum with chronic appendicitis. A 56-year-old man presented to our hospital with right lower abdominal pain. An abdominal computed tomography (CT) scan showed swelling of the appendix body and the wall thickness of the base of the appendix. Due to the possibility of appendiceal tumor, we performed a laparoscopy-assisted ileocecal resection with lymph node dissection. The appendix had a diverticulum with chronic inflammation, but it did not have a neoplastic lesion

High-pressure-induced water penetration into 3-­isopropylmalate dehydrogenase

Structures of 3-­isopropylmalate dehydrogenase were determined at pressures ranging from 0.1 to 650 MPa. Comparison of these structures gives a detailed picture of the swelling of a cavity at the dimer interface and the generation of a new cleft on the molecular surface, which are accompanied by water penetration

Excited state modulation of C70 dimerization in a carbon nanotube under a variable electron acceleration voltage

Cinematographic recording of chemical reactions with transmission electron microscopy provides information unavailable by any other analytical methods. Studies have thus far remained mostly phenomenological, lacking information on the reactive species involved. To gain insight into the nature of the reactive species, we need to obtain kinetic information under various temperatures and variable acceleration voltages, i.e., electronic energy supply. We studied the mechanism of [2 + 2] dimerization of [70] fullerene in a carbon nanotube as an example. We describe herein a statistical analysis of individual reaction events of the dimerization that revealed dose-dependent first-order kinetics and voltage-dependent crossover from a singlet to a triplet mechanism, as highlighted by the pre-exponential factor (the frequency of excitation) that is a million times larger for the singlet reaction than for the triplet one. Comparison with the results of a recent study of [60] fullerene dimerization lets us propose that electron-impact excitation of the carbon nanotube is the first step, followed by energy transfer to fullerene molecules and their dimerization via an excited state. The results show that a variable-voltage kinetic study is indispensable for discussing the mechanism of chemical transformations under electron microscopic observation.11Nsciescopu