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Derek Jones

Publications and source records attributed to Derek Jones.

7 recordsLinked to original sources
PubMed2006

Temporary anion states and dissociative electron attachment to isothiocyanates.

The temporary anion states of isothiocyanates CH3CH2=C=S (and CH3CH2N=C=O for comparison), C6H5CH2N=C=S, and C6H5N=C=S are characterized experimentally in the gas phase for the first time by means of electron transmission spectroscopy (ETS). The measured vertical electron attachment energies (VAEs) are compared with the virtual orbital energies of the neutral-state molecules supplied by MP2 and B3LYP calculations with the 6-31G* basis set. The calculated energies, scaled with empirical equations, reproduce satisfactorily the experimental VAEs. The first VAE is also closely reproduced as the total energy difference between the anion and neutral states calculated at the B3LYP/6-31+G* level. Due to mixing between the ring and N=C=S pi-systems, C6H5N=C=S possesses the best electron-acceptor properties, and its lowest-lying anion state is largely localized at the benzene ring. The anion states with mainly pi*C=S and pi*N=C character lie at higher energy than the corresponding anion states of noncumulated pi-systems. However, the electron-acceptor properties of isothiocyanates are found to be notably larger than those of the corresponding oxygen analogues (isocyanates). The dissociative electron attachment (DEA) spectra show peaks close to zero energy and at 0.6 eV, essentially due to NCS- negative fragments. In spite of the energy proximity of the first anion state in phenyl isothiocyanate to the DEA peak, the zero-energy anion current in the benzyl derivative is about 1 order of magnitude larger.

Anions↗
PubMed2006

Temporary anion states and dissociative electron attachment in diphenyl disulfide.

The temporary anion states of gas-phase diphenyl disulfide are characterized by means of electron transmission (ET) and dissociative electron attachment (DEA) spectroscopies. The measured energies of vertical electron attachment are compared to the virtual orbital energies of the neutral state molecule supplied by MP2 and B3LYP calculations with the 6-31G basis set. The calculated energies, scaled with empirical equations, reproduce satisfactorily the attachment energies measured in the ET spectrum. The first anion state of diphenyl disulfide is stable, thus escaping detection in ETS. The vertical and adiabatic electron affinities, evaluated with B3LYP/6-31+G calculations as the energy difference between the neutral and anion states, are predicted to be 0.37 and 1.38 eV, respectively. The anion current displayed in the DEA spectrum has a sharp and intense peak at zero energy, essentially due to the C6H5S- negative fragment. In agreement, according to the calculations, the localization properties of the first anion state are strongly S-S antibonding, and the energetic requirement for its dissociation along the S-S bond is fulfilled even at zero energy.

Anions↗
PubMed2005

Empty level structure in phenyl and benzyl isocyanates.

The energies of the lowest-lying anion states of phenyl (C6H5N=C=O) and benzyl (C6H5CH2N=C=O) isocyanates have been determined experimentally in the gas phase for the first time using electron transmission spectroscopy (ETS), and their localization properties have been evaluated using HF/6-31G, MP2/6-31G*, and B3LYP/6-31G* calculations. The lowest-lying anion state of phenyl isocyanate, mainly of benzene ring character but with some contribution also from the N=C=O pi-system, lies at significantly higher energy than that of other benzenes substituted by pi-functionals, such as benzaldehyde or styrene. The scaling with the use of suitable empirical equations of the virtual orbital energies (VOEs) for orbitals with predominantly pi*(ring) character calculated for the neutral-state molecules leads to vertical attachment energies (VAEs) which closely correspond to those determined experimentally, whereas those calculated for the predominantly pi*(CO) and pi*(NC) orbitals (3rd and 4th LUMO, respectively) are significantly different from the corresponding measured values notwithstanding the fact that the calculations reproduce the shortening of the N=C and C=O double bonds.

Journal Article↗
PubMed2005

HIV facial lipoatrophy: causes and treatment options.

BACKGROUND: Human immunodeficiency virus (HIV)-associated facial lipoatrophy is becoming epidemic and may seriously affect quality of life. OBJECTIVE: To review the possible causes and treatment options for HIV facial lipoatrophy. METHODS: This article is based on a review of the medical literature and the author's clinical experience in treating HIV facial CONCLUSION: Although absorbable injectable fillers and implants are helpful in treating HIV facial lipoatrophy, they are limited by cost and the short duration of correction. Newer forms of longer-lasting fillers (poly-L-lactic acid [Sculptra]) and permanent injectable fillers (liquid injectable silicone) are proving useful for treatment of this condition.

Adipose Tissue↗
PubMed2003

Falls from trucks: a descriptive study based on a workers compensation database.

BACKGROUND: Falls from heights, including falls from nonmoving trucks, are a known cause of serious workplace injuries [1,2,4,6,7,14,15]. Subsequent to the Workplace Safety and Insurance Board (WSIB) of Ontario implementing an industry sector management approach for service delivery the principle author noted a number of serious injuries as a consequence of falls from trucks or truck trailers. A literature search revealed limited articles, specifically relating to injuries sustained in falls from trucks or truck trailers. It was therefore decided to further investigate the scope of the problem. METHODS: A search of the Province of Ontario, Workplace Safety & Insurance Board (WSIB) database for the year 1997 was conducted to identify all claims, within the Transportation Sector, where a reported accident had been classified as a fall from a non-moving vehicle. The data extracted from identified claims constitutes the basis of this study. There were 1026 claims initially identified. Each identified claim was reviewed to determine if the study entry criteria; (1) a fall occurred and (2) the fall originated from a truck, its trailer or the cargo, were met. Of the identified claims 352 met the study inclusion criteria. A retrospective file review was conducted on each claim entered into the study and the study variables recorded on a predefined data sheet. RESULTS: The most frequent sites of falls were the back of the truck or trailer, the truck step and the cargo being transported. More than one injury was sustained by 23.6% of the study population. The major injuries identified included; 214 strains/sprains, 117 contusions and 101 fractures. One year post accident 89.4% of the study population had returned to work, of these 84.9% were on full duties and the remaining 4.5% were on modified duties. The total costs associated with the 352 injured workers included in this study amounted to $5,313,901.27. INTERPRETATION: Falls from trucks often result in significant injuries with considerable periods of disability and related costs. As falls from three specific locations i.e. the back of trucks/trailer, the cargo and the truck step made up 83% of the total falls efforts at prevention might best be directed to further investigate causal factors involved in the falls from these high frequency areas. A prospective study, including a detailed interview, with workers suffering a fall from a truck would assist in understanding factors that contribute to falls from trucks or truck trailers.

Accidental Falls↗
PubMed2003

Employment and chronic non-cancer pain: insights into work retention and loss.

OBJECTIVES: To explore the work experiences of three individuals who have chronic non-cancer pain and to identify factors which may affect their ability to remain in employment. METHODS: Three cases were selected from a data set of six, to illustrate distinct employment history scenarios. All participants had a diagnosis of rheumatoid arthritis. Data was gathered using semi-structured, in-depth interviews that were audiotaped and later transcribed for qualitative, content analysis. Themes identified were those which related to employment experiences and appeared to be important factors influencing the retention of work. FINDINGS: Four main themes were identified: the nature of physical barriers to employment, autonomy at work, social networks, and the importance and motivation to remain in employment. CONCLUSION: These findings support existing research in relation to chronic pain and employment in general and expands upon the nature and importance of social support at work. It is suggested that the qualitative methodology illustrated here, which explores the perspectives of those still in employment (as well as those who have stopped working) may be a useful approach to investigating this important area of research.

Aged↗