808 research outputs found
Experimental and ab-initio calculated vcd spectra of the first OH-stretching overtone of (1R)-(-) and (1S)-(+)-endo-borneol
The near infrared (NIR) absorption and NIR-vibrational circular dichroism (NIR-VCD) spectra
of dilute solutions of the two enantiomers of endo-borneol have been measured in the first
OH-stretching overtone region (1600–1300 nm). By density functional theory (DFT) we calculate
mechanical parameters, i.e. the harmonic mechanical frequency and the anharmonicity constant
for the OH stretching, and anharmonic electrical parameters; i.e. the dependence on OH-bond
length of atomic polar tensors and atomic axial tensors. We evaluate transition integrals for the
calculations of rotational and dipole strengths by Morse anharmonic wavefunctions depending on
mechanical harmonic frequencies and mechanical anharmonicity parameters that are calculated
ab initio. Experimental and calculated spectra compare quite well and this fact allows us to
associate differently signed NIR-VCD features with different conformational states of the
OH-bond. Absorption features for the fundamental and for the second overtone of the OH
stretching are also compared with experiment
NIR-VCD, vibrational circular dichroism in the near-infrared: Experiments, theory and calculations
The first well documented experiments of Near Infrared Vibrational Circular
Dichroism (NIR-VCD) were performed around 1975. We review the thirty year history
of NIR-VCD, encompassing both instrumental development and theoretical/computational
methods that allow interpretation of experimental spectra, harvesting useful structural
information therefrom. We hope to stimulate interest in this still scarcely explored
spectroscopy of chiral molecule
Harmonic and Anharmonic Features of IR and NIR Absorption and VCD Spectra of Chiral 4-X-[2.2]Paracyclophanes
The vibrational absorption spectra and vibrational circular dichroism (VCD) spectra of both enantiomers of
4-X-[2.2]paracyclophanes (X ) COOCD3, Cl, I) have been recorded for a few regions in the range of 900-
12000 cm-1. The analysis of the VCD spectra for the two IR regions, 900-1600 cm-1 and 2800-3200 cm-1,
is conducted by comparing with DFT calculations of the corresponding spectra; the latter region reveals
common motifs of vibrational modes for the three molecules for aliphatic CH stretching fundamentals, whereas
in the mid-IR region, one is able to identify specific signatures arising from the substituent groups X. In the
CH stretching region between 2900 and 2800 cm-1, we identify and interpret a group of three IR VCD bands
due to HCH bending overtone transitions in Fermi resonance with CH stretching fundamental transitions.
The analysis of the NIR region between 8000 and 9000 cm-1 for X ) COOCD3 reveals important features
of the aromatic CH stretching overtones that are of value since the aromatic CH stretching fundamentals are
almost silent. The intensifying of such overtones is attributed to electrical anharmonicity terms, which are
evaluated here by ab initio methods and compared with literature data
The anomaly-free quantization of two-dimensional relativistic string. I
An anomaly-free quantum theory of a relativistic string is constructed in
two-dimensional space-time. The states of the string are found to be similar to
the states of a massless chiral quantum particle. This result is obtained by
generalizing the concept of an ``operator'' in quantum field theory.Comment: LaTeX, 19 pages, no figure
Dipole and rotational strengths for overtone transitions of a C2-symmetry HCCH molecular fragment using Van Vleck perturbation theory
Contact transformation theory up to second order is employed to treat CH-stretching overtone
transitions and to calculate dipole and rotational strengths. A general Hamiltonian describing two
interacting CH-stretching oscillators is considered, and the Darling–Dennison resonance is
appropriately taken into account. The two CH bonds are supposed to be dissymmetrically disposed,
so as to represent a chiral HCCH fragment, endowed with C2 symmetry. Analytical expressions of
transition moments and dipole and rotational strengths are given in the hypothesis of general electric
and magnetic dipole moments with quadratic dependence on coordinates and momenta. Dipole and
rotational strengths are then calculated together with frequencies for the fundamental and first three
overtone regions in the simplifying hypothesis of the valence optical approach on the
coupled-oscillator framework. Simplified analytical expressions thereof in the relevant parameters
are presented
Basic Human Values and Moral Foundations Theory in ValueNet Ontology
Values, as intended in ethics, determine the shape and validity of moral and social norms, grounding our everyday individual and community behavior on commonsense knowledge. The attempt to untangle human moral and social value-oriented structure of relations requires investigating both the dimension of subjective human perception of the world, and socio-cultural dynamics and multi-agent social interactions. Formalising latent moral content in human interaction is an appealing perspective that would enable a deeper understanding of both social dynamics and individual cognitive and behavioral dimension. To formalize this broad knowledge area, in the context of ValueNet, a modular ontology representing and operationalising moral and social values, we present two modules aiming at representing two main informal theories in literature: (i) the Basic Human Values theory by Shalom Schwartz and (ii) the Moral Foundations Theory by Graham and Haidt. ValueNet is based on reusable Ontology Design Patterns, is aligned to the DOLCE foundational ontology, and is a component of the Framester factual-linguistic knowledge graph
The Racing Mind and the Path of Love: automatic extraction of image schematic triggers in knowledge graphs generated from natural language
Embodied Cognition and Cognitive Metaphors Theory take their origin from our use of language: sensorimotor triggers are disseminated in our daily communication, expression and commonsense knowledge. We propose, in this work, a first attempt of image-schematic triggers automatic extraction, starting from knowledge graphs automatically generated from natural language. The methodology proposed here is conceived as a modular addition integrated in the FRED tool, able to generate knowledge graphs from natural language, while it has its foundation in querying ImageSchemaNet, the Image Schematic layer developed on top of FrameNet and integrated in the Framester resource. This methodology allows the extraction of sensorimotor triggers from WordNet, VerbNet, MetaNet, BabelNet and many more
At risk policy and early intervention programmes for underperforming students: Ensuring success?
Purpose - The purpose of this paper is to examine a University's at risk program and ask is the intervention strategy working? The program seeks to assist at risk students who may be experiencing difficulties transitioning, for example from school into university. The program also seeks to identify problems and suggest remediation strategies before attrition
Lymphocyte Subsets and Inflammatory Cytokines of Monoclonal Gammopathy of Undetermined Significance and Multiple Myeloma
Almost all multiple myeloma (MM) cases have been demonstrated to be linked to earlier monoclonal gammopathy of undetermined significance (MGUS). Nevertheless, there are no identified characteristics in the diagnosis of MGUS that have been helpful in differentiating subjects whose cancer may progress to a malignant situation. Regarding malignancy, the role of lymphocyte subsets and cytokines at the beginning of neoplastic diseases is now incontestable. In this review, we have concentrated our attention on the equilibrium between the diverse lymphocyte subsets and the cytokine system and summarized the current state of knowledge, providing an overview of the condition of the entire system in MGUS and MM. In an age where the therapy of neoplastic monoclonal gammopathies largely relies on drugs capable of acting on the immune system (immunomodulants, immunological checkpoint inhibitors, CAR-T), detailed knowledge of the the differences existing in benign and neoplastic forms of gammopathy is the main foundation for the adequate and optimal use of new drugs
Multimodal, open-source big data analysis in asthma: A novel approach to inform public health programming
Asthma is a chronic respiratory disease affecting over 358 million people worldwide; for this reason analysing big data on asthma from different countries could give a more detailed picture of current disease burden. We aim to investigate the correlations between asthma and key socio-demographic parameters from different world databases. We found a direct correlation with the gross domestic product (GDP) per capita and its nominal counterpart, with wealthiest countries seen to have the highest prevalence of asthma, as also confirmed by a similar correlation with the human development index (HDI). A positive correlation was also seen between asthma prevalence and a number of socio-cultural data being representative of a good life quality index and prevalent in more developed and wealthier countries. Concerning medical data, an inverse relationship was seen between asthma prevalence and helminthiasis. Those data indicate a higher prevalence for asthma in more developed countries, where socio-economic status is higher and also the access to medical care is more ubiquitous. The approach used in our study highlighted the role of medical literacy and access to healthcare facilities in the correct diagnosis of asthma and vice versa. Our data appear to be suitable in terms of a health programming approach because of the high burden of disease worldwide
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