RESUMEN
Lanthanides are widely assumed not to form covalent bonds due to the localized nature of their 4f valence electrons. This work demonstrates that the ionic bond of Sm(II) with cyclononatetraenyl (η9-C9H9-) in [Sm(η9-C9H9)2] can be modulated and becomes more covalent by photon-induced transfer of Sm 4f electrons to Sm 5d orbitals. This photon-induced change in bonding properties facilitates a subsequent reconfiguration of [Sm(η9-C9H9)2]. As a result, Sm-C bond length contraction is detected and the local Sm coordination environment exhibits more extensive disorder. Both Sm 4f and 5d electrons have increased participation in covalent Sm-ligand interactions. The Sm L3-edge valence band resonant inelastic X-ray scattering (VB-RIXS), high-resolution X-ray absorption near-edge structure (HR-XANES), and quantum chemical computations showcase a spectroscopic methodology for in-depth studies of bond covalency of lanthanide atoms.
RESUMEN
OBJECTIVE: This study assessed both executive function (EF) and prospective memory (PM) in a group of current smokers (CS) to observe whether deficits in both sets of memory processes co-existed in smokers, comparing this group with a group who had never smoked (NS). METHOD: An existing-groups design was used to compare smokers with the NS group on a Reserve Digit Span Task (RDST) that measured EF and the Cambridge Prospective Memory Test (CAMPROMPT) measuring PM. Age, mood, other drug use and IQ were also measured and controlled for in the study. RESULTS: After omitting anyone using an illegal substance and observing no between-group differences in age, gender, anxiety, depression, alcohol use and IQ, the CS group performed significantly worse on the RDST and recalled significantly fewer time-based and event-based tasks on CAMPROMPT, compared with the NS group. CONCLUSIONS: Both EF and PM deficits were evident in the same cohort of CS when compared with a NS group, a finding which is novel in the current literature. Since both EF and PM are interrelated in that they share common resources in the brain, the finding that both sets of deficits co-existed in smokers suggests that persistent cigarette smoking impedes these underlying resources.
RESUMEN
OBJECTIVE: This study assessed self-reported and objective prospective memory (PM) processes in smokers and a never-smoked comparison group. If persistent smoking does impair PM, then one would expect smokers recall being lower on a study that requires them to remember everyday activities when compared with a never-smoked group. METHOD: An existing-groups design was used to compare a group of smokers with a never-smoked group on the self-report Prospective Memory Questionnaire (PMQ) and the Prospective Remembering Video Procedure (PRVP) measuring objective PM. An example of the location-action combination from the PRVP is 'At Thornton's shop' (location), 'Buy a bag of sweets' (action). Participants who reported using an illegal substance (e.g. ecstasy, cannabis), who drank excessively or were 'binge drinkers', or who reported suffering from a clinical condition, such as depression, were excluded from the study. Age, weekly 'safe levels' alcohol use, and strategy use were also measured and controlled for in the study. Each person was tested individually in a quiet laboratory setting on a university campus. RESULTS: After controlling for variations in age, weekly alcohol use, and strategy use, smokers recalled significantly fewer location-action combinations on the PRVP when compared with a never-smoked group, with no between-group differences on self-reported PM as measured by the PMQ. CONCLUSIONS: The findings suggest objective PM deficits are associated with persistent smoking - a relatively unexplored area of research. This cannot be attributed to other drug use, mood, or strategy use. The findings also suggest smokers lack self-awareness of such PM deficits. This study extends the area by utilising a more naturalistic object measure of PM and incorporating strict controls into the study.
RESUMEN
BACKGROUND: Smokers, previous smokers and a never smoked group were compared on self-reported and real world prospective memory (PM - the cognitive ability of remembering to carry out particular actions at some future point in time). METHODS: Twenty-seven current smokers, 24 people who had never smoked and 18 previous smokers were compared using an existing groups design. Scores on the long and short term PM subscales of the Prospective and Retrospective Memory Questionnaire (PRMQ) and scores on a Real World Prospective Memory Task (RWPMT) constituted the dependent measures. Smoking and other drug use were assessed by a Recreational Drug Use Questionnaire. The Hospital Anxiety and Depression Scale gauged levels of anxiety and depression. The National Adult Reading Test measured IQ, and retrospective memory was measured using the PRMQ. Gender, age, anxiety and depression, IQ, alcohol use and the retrospective memory scores, were measured as covariates and controlled for in the analysis. RESULTS: A series of univariate ANCOVAs were applied to the main PM data across the three groups, controlling for variations in age, gender, mood, IQ, alcohol use and retrospective memory scores. These revealed no significant between-group differences on self-reported PM; however smokers recalled significantly fewer action-location combinations than the never smoked and previous smoker groups on the objective RWPMT. CONCLUSIONS: Existing smokers showed reduced performance on RWPMT when compared to the never smoked group and previous smokers. Real-world PM impairments should be added to a growing list of neuropsychological sequelae associated with persistent smoking.
