Theoretical and experimental investigation into the IR-VUV ion dip spectroscopy of amino acids and analogue systems

2010 Fall.Includes bibliographic references.Covers not scanned.Print version deaccessioned 2022.Amino acids are among the fundamental building blocks of life, and as such have been, and continue to be, of much interest for study. While gas phase spectroscopic studies can be very useful in obtaining information about molecular species (in this case various naturally occurring amino acids), the use of computational and theoretical methods can aid these studies in providing a more complete understanding of the properties and behaviors of these species. Here presented are the results of IR-VUV ion dip spectroscopy, coupled with a high-level theoretical examination of the spectroscopic results, including MP2 and CASSCF calculations. In IR-VUV ion dip spectroscopy, the isolated neutral molecules are ionized by a single photon of 10.5 eV energy 118 nm. If the neutral ground state amino acids are exposed to IR radiation prior to ionization, an IR spectrum can be determined by observation of the ion intensity of the different fragment mass channels. Species specifically studied include numerous naturally occurring aliphatic and aromatic amino acid species, and amino acid analogue species. In the case of the aliphatic amino acids, conformer specific decomposition pathways are observed spectroscopically, and further elucidated both through the study of III amino acid analogue species and through high level multiconfigurational CASSCF calculations. It is shown that upon ionization, the localized character of the charge, coupled with the geometry of the neutral parent molecule, directs the decomposition reaction of the molecule. In simple, small aliphatic amino acid and analogue species, these factors are unique to the conformation of the molecule, leading to conformer specific decomposition chemistry. In the amino acid species, the localized charge tends to occur either on one of the available moieties (carboxylic acid, amine, etc.), or on the carbon-carbon bond, depending on the conformer. The IR-VUV ion dip spectra obtained from the aromatic amino acid species, however, clearly demonstrate different photodecomposition behavior in the aromatic species when compared to the simple, smaller aliphatic species. The conformer specific chemistry which was observed in the smaller molecules was not evident in the aromatic species. This is likely due to the aromatic moiety containing the lowest energy, localized ion state for the molecule which does not lead to ion fragmentation. Thus, the conformer specific decomposition chemistry observed in the non-aromatic species is no longer observed in those species which contain an aromatic moiety

The Chediak-Higashi Syndrome: Spectrum of Giant Organelles in Peripheral Blood Cells

The presence of giant organelles in the cytoplasm of peripheral blood elements is diagnostic for the Chediak-Higashi syndrome. These abnormal cytoplasmic inclusions are found within neutrophils, eosinophils, basophils, lymphocytes, monocytes, and platelets. Their fine structural characteristics differ. Neutrophils demonstrate striking variability in the size, shape, and internal features of their giant organelles. Lymphocytes contain two different types of giant inclusions, one with a smoothly homogeneous substructure, the other with structures resembling microtubules. Emphasizing the ultrastructural similarities and differences of these anomalous granulations may provide valuable clues for understanding the basic defect of this inherited disorder

Mobile collocated interactions with wearables: past, present, and future

This Special Issue focuses on the emerging use of wearable technologies for mobile collocated interactions. Rather than merely listing off the articles that follow, we wish to introduce this Special Issue by discussing the past, present, and future of this field in HCI through its theories, ongoing designs and research efforts, and emerging frame- works. We conclude by providing an overview of a series of workshops on the topic, and introduce the two main articles that comprise this Special Issue

Inviscid text entry and beyond

The primary focus of our workshop is on exploring ways to enable inviscid text entry on mobile devices. In inviscid text entry, it is the user's creativity that is the text-creation bottleneck rather than the text entry interface. The inviscid rate is estimated at 67 wpm while current mobile text entry methods are typically 20-40 wpm. In this workshop, participants will discuss and demonstrate early work into novel methods that allow very rapid text entry, even if such methods currently are quite error-prone. In addition to submitting a position paper, participants are strongly encouraged to bring a demo to present during the workshop's interactive Show-and-Tell session. As well as exploring new entry methods, the workshop will discuss experimental tasks and evaluation methodologies for researching inviscid text entry. Looking beyond the speed of entry, the workshop will explore often overlooked aspects of text entry such as user adaptation, post-entry correction/revision/formatting, entry of diverse types of text, and entry when a user's input or output capabilities are limited. Finally, the workshop serves to strengthen the community of text entry researchers who attend CHI, as well as provide an opportunity for new members to join this community

Proxemics mobile collocated interactions

Recent research on mobile collocated interactions has been looking at situations in which collocated users engage in collaborative activities using their mobile devices. However, existing practices fail to fully account for the culturally-dependent spatial relationships between people and their digital devices (i.e. the proxemic relationships). Building on the ideas of proxemic interactions, this workshop is motivated by the concept of 'proxemic mobile collocated interactions', to harness new or existing technologies to create engaging and interactionally relevant experiences. Such approaches would allow devices to not only react to presence and interaction, but also other indicators, such as the interpersonal distance people naturally use in everyday life. The aim of this one-day workshop is to bring together a community of researchers, designers and practitioners who are interested in exploring proxemics and mobile collocated interactions

Adenoviruses in Fecal Samples from Asymptomatic Rhesus Macaques, United States

Isolates contained fiber genes similar to those of adenovirus strains that cause infectious diarrhea in humans

Investigation of strength limiting mechanisms in aramid fibers

Aramid fibers owe their high tensile strength and stiffness to their orderly fibrillar structure. The synergistic effect of individual fibrils comprising an aramid fiber, and the interfibrillar interactions determine the strength of an individual fiber. In order to study the existence and role of statistical defects in failure initiation of aramid fibers, quasi-static tensile tests were performed with individual fibers of different molecular compositions and gage lengths in the range of 100 µm–10 mm. The experimental results pointed out to a relative insensitivity of the tensile strength to the fiber gage length, which suggested that failure initiation is governed by processes and/or flaws active at length scales well below micron scale. Therefore, differences in tensile strength between the particular types of aramid fibers discussed in this study were attributed to interfibrillar interactions. The magnitude of the latter was assessed by longitudinal crack growth experiments with individual fibers, as interfibrillar interactions are expected to be similar to the van der Waals interactions between the hydrogen bonded macromolecular sheets comprising the aramid fibers. The initial fracture experiments showed stable crack propagation under relatively constant force taking place for very large lengths of individual fibers. This presentation will provide the current results on the cohesive energy measurements on two types of aramid fibers designed to provide high tensile strength

Phylogenetic classification of Escherichia coli O157:H7 strains of human and bovine origin using a novel set of nucleotide polymorphisms

Novel SNPs from human and bovine O157:H7 E. coli isolates are mapped, revealing that the majority of human disease is caused by a bovine subset of this strain