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G Marston

Publications and source records attributed to G Marston.

7 recordsLinked to original sources
PubMed2004

Dissociative electron attachment to dinitrogen pentoxide, N2O5.

Electron attachment was studied in gaseous dinitrogen pentoxide, N(2)O(5), for incident electron energies between a few meV and 10 eV. No stable parent anion N(2)O(5) (-) was observed but several anionic fragments (NO(3) (-), NO(2) (-), NO(-), O(-), and O(2) (-)) were detected using quadrupole mass spectrometry. Many of these dissociative pathways were found to be coupled and provide detailed information on the dynamics of N(2)O(5) fragmentation. Estimates of the cross sections for production of each of the anionic fragments were made and suggest that electron attachment to N(2)O(5) is amongst the most efficient attachment reactions recorded for nonhalogenated polyatomic systems.

Journal Article↗
PubMed2002

People with intellectual disability, sensory impairments and behaviour disorder: a case series.

BACKGROUND: Sensory impairments (SIs) are more prevalent in people with intellectual disability (ID). Both conditions lead to higher rates of emotional and behavioural problems than in the general population. The identification of psychiatric disorders in this group can be difficult, particularly in those with severe ID and limited communication skills. METHOD: The present paper presents a series of 18 case reports of individuals with ID, SI and behavioural problems. RESULTS: The majority of cases were young male caucasians with congenital rubella syndrome and autistic spectrum disorder, referred because of self-injurious behaviour (SIB) or aggression. Nine cases were treated with autidepressants, five underwent environmental changes and two had medication reduced. All showed some improvement. CONCLUSIONS: The benefits of comprehensive assessments, the use of standardized assessment tools and trials of treatments are discussed in the context of making psychiatric diagnoses.

Adult↗
PubMed2000

Reactions of hydroxyl radicals with alkenes in low-temperature matrices.

The reactions of hydroxyl radicals with a number of stable alkenes have been studied in low-temperature matrices. The reactions were initiated by broad band UV-visible irradiation of matrices containing H2O2, and the alkene under investigation. The hydroxyalkyl radical products were identified principally by comparison of their spectra with the spectra of corresponding stable alcohols. Accordingly, IR spectra were recorded for the following series of alcohols isolated in argon matrices--methanol, ethanol, ethanol-d6, propan-1-ol, propan-2-ol, butan-2-ol, 2-methylpropan-1-ol (iso-butyl alcohol), 2-methylpropan-2-ol (tert-butyl alcohol), 2-methylbutan-2-ol (tert-amyl alcohol), 3-methylbutan-2-ol and 2,3-dimethylbutan-2-ol. The hydroxyalkyl radicals, which appear to be formed from the alkenes studied were as follows--from ethene, 2-hydroxyethyl radical: from cis- or trans-but-2-ene. 1-methyl-2-hydroxypropyl radical; from propene, 1-methyl-2-hydroxyethyl and 2-hydroxypropyl radicals; from but-1-ene. 1-hydroxymethylpropyl and 2-hydroxybutyl radicals; from 2-methylpropene (iso-butene), 1,1-dimethyl-2-hydroxyethyl and 2-methyl-2-hydroxypropyl radicals; the radical products from buta-1,3-diene and isoprene could not be identified. In the cases, where two radical products were possible, i.e. when propene, but-1-ene or 2-methylpropene were the substrates, it was found that the concentration of the secondary or tertiary radical always exceeded that of the primary radical. However, the relative concentration of these radicals appears to be determined by subsequent photolysis to give carbonyl compounds. There seems, therefore, to be little preference for the secondary and tertiary radicals over the primary radicals in the primary addition process. Comments on the mechanism of the transformation from radical to carbonyl compound based upon identification of intermediates within the matrix and isotopic substitution experiments are made. The characterisation of the 2-hydroxyethyl radical has been backed up by experiments utilising isotopic substitution with 13C and D (2H). The other radicals have been identified with varying degrees of certainty. Those radicals, which are observed at the highest concentration and which are, therefore, characterised more certainly are--2-hydroxyethyl (1), from ethene: 1-methyl-2-hydroxypropyl (2), from cis- and trans-but-2-ene; 1-methyl-2-hydroxyethyl (3), from propene; 1-hydroxymethylpropyl (5), from but-1-ene; and 1,1- dimethyl-2-hydroxyethyl (8), from 2-methylpropene.

Alcohols↗
PubMed2000

Reactions of alkenes with ozone in the gas phase: a matrix-isolation study of secondary ozonides and carbonyl-containing reaction products.

Gas phase ozonolysis reactions of the alkenes ethene, cis- and trans-but-2-ene, isoprene and the monoterpenes alpha-pinene, beta-pinene, beta-carene, limonene and beta-myrcene have been carried out and the reaction products have been trapped in O2-doped-argon matrices onto a Csl window held at 12 K. Products have been identified by IR spectroscopy. Comparison with previous matrix spectra, where secondary ozonides have been generated either in situ by annealing or in solution reactions allows a positive identification of the secondary ozonides of ethene and of cis- and trans-but-2-ene to be made. These observations are backed up by experiments utilising the isotopes 13C and 2H (D). It appears that secondary ozonides have also been formed from isoprene and the range of monoterpenes studied; this hypothesis is based upon the similarity of spectral features seen in the products of these reactions within those of the simpler alkenes. A number of other primary and secondary products are also identified from these reactions. Ethene gives formaldehyde as a primary product and acetaldehyde as a secondary product; it is found that the yield of acetaldehyde compared to formaldehyde increases as the reaction times are increased. Formaldehyde, one of the expected primary products, is formed by ozonolysis of beta-pinene, although the other expected primary product, nopinone, is not seen. A range of secondary reaction products have been identified from the ozonolysis of the monoterpenes studied.

Alkenes↗
PubMed2000

Problem behaviors associated with 15q- Angelman syndrome.

Caregivers of persons with Angelman syndrome completed the Aberrant Behavior Checklist and Reiss Screen for Maladaptive Behavior. Seventy-three replies were received, and comparisons were made with other published data. Responses indicated that 15q- Angelman syndrome is associated with such problems as lack of speech, overactivity, restlessness, and eating and sleep problems. Episodes of inappropriate laughter were only reported for 57%, despite being considered a cardinal feature of the syndrome; eating problems (64%) and a fascination with water (68%) were reported more frequently. Overactivity was more of a problem for children; Aberrant Behavior Checklist Factor IV (Hyperactivity) was negatively correlated with age. Scores were mostly lower than for previously studied etiological groups. Therapeutic effort should be put into programs to address these problems.

Adolescent↗
PubMedDate not supplied

Gonorrheal disease among children in a university hospital.

In the current veneral disease epidemic the pediatrician may observe every clinical expression of gonococcal infection. Review of outpatient records at the University of Maryland Pediatric Clinic (Baltimore, Md.) showed frequent utilization of this health-care facility by girls with genitourinary complaints and a high rate of recovery of Neisseria gonorrhoeae from those patients from whom specimens were obtained for culture. The adolescent girl is the most likely pediatric patient to have genitourinary complaints that indicate a diagnosis of gonorrhea. Overall, 16.3% of girls and 37.2% of boys who had speciments cultured for N. gonorrhoeae had positive results. Although the older teenager (15--18 years of age) was most likely to have a positive culture, high rates comparable to those reported in venereal disease clinics were found for all age groups. Half of the cases of gonorrhea in girls aged 15 to 18 years took the clinical form of pelvic inflammatory disease. Most gonococcal infections in prepubertal children were in girls 2 to 5 years of age and resulted from presumed sexual abuse. Vulvovaginitis was the initial symptom in all cases. Prepubertal boys infected with N. gonorrhoeae all had urethritis; three of seven admitted to voluntary sexual activity.

Adolescent↗