Leaching of monolithic and granular alkali activated slag-fly ash materials, as a function of the mixture design.

This study explores the leaching of oxyanionic metalloid species (As, Mo, Se, V and Cr) from alkali activated slag-fly ash materials (AAM), dependent on various mixture parameters i.e., activator molarity, slag-fly ash precursor/binder compositions, liquid to binder ratio, curing time and strength. The analyses focusses on the leaching of potentially hazardous elements in a monolithic and granular material state. For monolithic state AAMs (concrete) overall leaching is within comparable range with traditional Portland cement and in both systems their leaching is far below the regulatory leaching limit values even though AAM strongly differs in mixture composition. For granular state AAMs (aggregate) the parameters, activator alkalinity and the slag-fly ash precursor/binder composition, significantly influence the leaching. The release of As and V strongly increases with a higher activator molarity as an effect of changes in the system alkalinity and related material pH. The release of As, Mo, Se and V strongly increase with a higher fly ash content within the precursor/binder composition. Overall, the leaching of aggregate state AAMs meets the Dutch leaching limits for open application of granular building materials, when the fly ash content within the binder composition ≤ ≈30 wt%. Typically, the pH dependent leaching data show oxyanionic metalloid species have a relatively high leaching potential, being less effectively bound as a result of the amorphous AAM microstructure. However, the leachable concentrations of a AAM system are within the bandwidth with that of blended (slag and or fly ash) Portland cement system.

Leaching, geochemical modelling and field verification of a municipal solid waste and a predominantly non-degradable waste landfill.

In spite of the known heterogeneity, wastes destined for landfilling can be characterised for their leaching behaviour by the same protocols as soil, contaminated soil, sediments, sludge, compost, wood, waste and construction products. Characterisation leaching tests used in conjunction with chemical speciation modelling results in much more detailed insights into release controlling processes and factors than single step batch leaching tests like TCLP (USEPA) and EN12457 (EU Landfill Directive). Characterisation testing also can provide the potential for mechanistic impact assessments by making use of a chemical speciation fingerprint (CSF) derived from pH dependence leaching test results. This CSF then forms the basis for subsequent chemical equilibrium and reactive transport modelling to assess environmental impact in a landfill scenario under relevant exposure conditions, including conditions not readily evaluated through direct laboratory testing. This approach has been applied to municipal solid waste (MSW) and predominantly non-degradable waste (PNW) that is representative of a significant part of waste currently being landfilled. This work has shown that a multi-element modelling approach provides a useful description of the release from each of these matrices because relevant release controlling properties and parameters (mineral dissolution/precipitation, sorption on Fe and Al oxides, clay interaction, interaction with dissolved and particulate organic carbon and incorporation in solid solutions) are taken into consideration. Inclusion of dissolved and particulate organic matter in the model is important to properly describe release of the low concentration trace constituents observed in the leachate. The CSF allows the prediction of release under different redox and degradation conditions in the landfill by modifying the redox status and level of dissolved and particulate organic matter in the model runs. The CSF for MSW provides a useful starting point for comparing leachate data from other MSW landfills.

High performance of treated and washed MSWI bottom ash granulates as natural aggregate replacement within earth-moist concrete.

Municipal solid waste incineration bottom ash was treated with specially designed dry and wet treatment processes, obtaining high quality bottom ash granulate fractions (BGF) suitable for up to 100% replacement of natural gravel in concrete. The wet treatment (using only water for separating and washing) significantly lowers the leaching of e.g. chloride and sulfate, heavy metals (antimony, molybdenum and copper) and dissolved organic carbon (DOC). Two potential bottom ash granulate fractions, both in compliance with the standard EN 12620 (aggregates for concrete), were added into earth-moist concrete mixtures. The fresh and hardened concrete physical performances (e.g. workability, strength and freeze-thaw) of high strength concrete mixtures were maintained or improved compared with the reference mixtures, even after replacing up to 100% of the initial natural gravel. Final element leaching of monolithic and crushed granular state BGF containing concretes, showed no differences with the gravel references. Leaching of all mixtures did not exceed the limit values set by the Dutch Soil Quality Degree. In addition, multiple-life-phase emission (pH static test) for the critical elements of input bottom ash, bottom ash granulate (BGF) and crushed BGF containing concrete were assessed. Simulation pH lowering or potential carbonation processes indicated that metal (antimony, barium, chrome and copper) and sulfate element leaching behavior are mainly pH dominated and controlled, although differ in mechanism and related mineral abundance.

Life cycle assessment and residue leaching: the importance of parameter, scenario and leaching data selection.

Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens, due to the potential leaching of toxic substances. In waste LCA studies where residue utilisation is included, leaching has generally been neglected. In this study, municipal solid waste incineration bottom ash (MSWI BA) was used as a case study into three LCA scenarios having different system boundaries. The importance of data quality and parameter selection in the overall LCA results was evaluated, and an innovative method to assess metal transport into the environment was applied, in order to determine emissions to the soil and water compartments for use in an LCA. It was found that toxic impacts as a result of leaching were dominant in systems including only MSWI BA utilisation, while leaching appeared negligible in larger scenarios including the entire waste system. However, leaching could not be disregarded a priori, due to large uncertainties characterising other activities in the scenario (e.g. electricity production). Based on the analysis of relevant parameters relative to leaching, and on general results of the study, recommendations are provided regarding the use of leaching data in LCA studies.

Low IQ scores in schizophrenia: primary or secondary deficit?

BACKGROUND: Schizophrenia is consistently associated with lower IQ compared to the IQ of control groups, or estimated premorbid IQ. It is not likely that the IQ scores deteriorate during the prodromal phase or first psychotic episode; they are already present before the onset of the prodromal phase and have been detected in childhood. METHODS: We investigated cognitive functioning and IQ levels in a group of 36 patients with schizophrenia or other psychotic disorders. RESULTS: The IQ scores in our sample were lower than average. The IQ showed a relation with attention, memory, speed of information processing and some aspects of executive functioning. However, when IQ scores were corrected for processing speed, they were no longer below average. CONCLUSIONS: These findings are important in considering the value of intelligence levels in schizophrenia. IQ scores should be judged in combination with cognitive functioning and school career to assess a patients capabilities in society. Cognitive functions and other variables might have a considerable influence on IQ scores. This rises the question of whether the low IQ scores are a primary or secondary deficit. Schizophrenia patients may have normal IQs, but could be less capable of making an IQ-test.

Construct validity of concepts of attention in healthy controls and patients with CHI.

The present study aimed to examine the construct validity of three aspects of attention, namely focused, divided, and supervisory control of attention. Factor-analytic techniques were applied to scores of healthy subjects on a series of neuropsychological tests tapping these aspects of attention. The two components found did not match the hypothesized aspects and were labeled as Memory-driven Action and Stimulus-driven Reaction. The second question was whether the same components could be found in a group of patients with CHI. The pattern of attentional functions found in healthy subjects had changed qualitatively in patients with CHI. A possible explanation for this result in terms of a shift from automatic to controlled processing is discussed.

[Cognitive impairments among older drivers: medical examination and driving test]. / Autorijden bij ouderen met cognitieve functiestoornissen: medische keuring en rijtest.

The aim of this study was to gain insight in the prevalence of cognitive impairments among active older drivers and in driving performance of cognitively impaired ones. The study was implemented in the existing Dutch relicensing procedure for older drivers and consisted of three evaluation moments: a medical screening (for all subjects), a neuropsychological assessment and a test-drive (for candidates with cognitive impairments). In total, 2992 drivers were medically evaluated. In 4% of cases indications for impaired cognitive functioning were observed that could be evaluated and confirmed with neuropsychological tests. Eighty subjects performed an on-road test. Of these subjects, 57% were allowed to renew their driver's license, while in the remaining 43% no new licenses or restricted licenses were issued. During the test-drive, slow reactions and attention deficits were the most important causes for impaired fitness to drive.

Acute behavioural disturbances related to imaging studies and outcome in mild-to-moderate head injury.

The frequency of behavioural disturbances early after injury in relation to outcome was prospectively investigated in a series of 67 patients with mild-to-moderate head injury (as defined by GCS on admission). In more than half of the patients, behavioural disturbances were observed. Restlessness occurred in 40% of patients, whereas agitation was seen in 19% of patients. In all patients, restlessness and agitation disappeared before resolution of PTA. In multiple regression analysis, restlessness and PTA were found to be separate factors in predicting outcome. On imaging studies, twice as many lesions were seen in patients with restlessness and agitation (81% compared to 39%), mainly localized in the frontotemporal region. In two thirds of patients with early behavioural disturbances, residual emotional and cognitive impairments were seen 1 year after injury. This study suggests that behavioural disturbances in the early phase after injury are related to frontotemporal lesions and lends support for the view of the existence of a separate profile of patient behaviour in mild-to-moderate head injury.

Fitness to drive in older drivers with cognitive impairment.

This paper is a literature review on assessment of fitness to drive in older drivers with cognitive impairment. Early studies on dementia and driving generally failed to distinguish between safe and unsafe drivers on the basis of cognitive test performance. Predictive studies demonstrated that cognitively impaired persons as a group perform significantly worse than controls on both neuropsychological and driving measures. A high prevalence of cognitive impairment was found in groups of older drivers involved in traffic accidents and crashes. However, a large range in neuropsychological test scores has been found. Low to moderate correlations could be established between neuropsychological test results and on-road driving performance, making it difficult to discriminate between cognitively impaired subjects who are fit or unfit to drive. The review concludes with a discussion of methodological difficulties in the field of dementia and driving, including participant selection, the choice of neuropsychological tests, and the operationalization of driving performance.

Executive functioning, attention and frontal lesions in patients with chronic CHI.

To study the presence and nature of dysexecutive problems after CHI, a series of unstructured tasks tapping executive functioning were selected. These were administered to a group of 51 participants with CHI in the chronic stage (i.e. several years post-injury) and to 45 healthy controls. In addition, well-known structured tests of attention and planning were administered. Of the executive tasks, only the Executive Route Finding task showed a significant difference between both groups. A multivariate analysis on the attention tests showed a significant difference between groups, indicating that patients in the chronic stage still process information slower than controls. Within the patient group, patients with and without frontal focal lesions were also compared on executive and attention tests. No differences were found with respect to the latter. However, patients with frontal lesions performed worse on a measure of the Executive Route Finding task. It is concluded that patients with CHI, especially when they have frontal damage, have to rely more heavily on externally provided cues, but this dysexecutive problem can only be demonstrated in tasks that resemble daily life tasks by providing very little structure.

Unilateral pallidotomy in PD: a controlled study of cognitive and behavioral effects. The Netherlands Pallidotomy Study (NEPAS) group.

OBJECTIVE: To investigate whether unilateral pallidotomy affects cognitive and behavioral functioning. METHODS: At baseline and after 6 months we assessed neuropsychological functioning in 35 patients with advanced PD. After baseline examination, patients were randomized to pallidotomy within 1 month (6 left-sided, 13 right-sided) or to pallidotomy after follow-up assessment 6 months later (n = 16; control group). We performed neuropsychological tests of language, visuospatial function, memory, attention, and executive functions. Self ratings and proxy ratings of memory problems and dysexecutive symptoms were also collected. RESULTS: No significant differences over time were found between pallidotomy and control groups, with the exception of a decrease of verbal fluency in the left-sided pallidotomy group. CONCLUSIONS: Unilateral pallidotomy is relatively safe with respect to cognition and behavior. Left-sided pallidotomy may lead to minor deterioration in verbal fluency. The sample size of this study is too small, however, to rule out the possibility of infrequent but clinically important side effects.

Computed tomography and magnetic resonance imaging in mild to moderate head injury: early and late imaging related to outcome.

Serial magnetic resonance imaging (MRI) and computed tomographic (CT) studies were performed in mild to moderate head injury to evaluate whether early and late imaging have additional value in predicting outcome in this category of patients. During 1-year follow-up of a series of 67 patients, a CT scan on admission was performed together with MRI studies within 1 to 3 months and 6 to 12 months after injury. With CT, intracranial lesions were seen in 62% of patients compared with 44% with early and 19% with late MRI, located predominantly in the frontal and temporal regions. More than half of the lesions revealed with CT resulted in focal atrophy on MRI. Outcome was found to be worse in patients with edema and lesions on CT. Likewise, abnormalities detected with MRI were associated with poor outcome scores. In multiple regression analysis, only lesions in the frontal regions detected with early MRI were found to be predictive of outcome. With late MRI, only focal atrophy in the frontotemporal regions was found to be predictive of outcome. The findings in this study suggests that MRI studies may be valuable for predicting long-term outcome in patients with mild to moderate HI.

Regional specific changes of cerebral metabolism in systemic lupus erythematosus identified by positron emission tomography.

In order to test the hypothesis whether the pathogenesis of cerebral systemic lupus erythematosus (SLE) may include an immune-mediated deficit in specific vulnerable brain regions, the regional cerebral metabolism in 9 patients with diffuse as well as focal cerebral symptoms was compared with that of 10 age-matched control subjects. The cerebral distribution of 2-[18F]fluoro-2-deoxy-D-glucose (FDG) uptake was measured by means of positron emission tomography. Subsequently performed statistical parametric mapping showed (i) a relative increase in metabolism in the striatum and (ii) regional decreases in the premotor cortex as a common feature in the patient group. Region of interest measurements of absolute FDG uptake confirmed these findings. The increased striatal activity may support the presence of a direct immune response against neuronal tissue in SLE, similar to the cross-reaction against inhibitory components in striatal tissue provoked by streptococcal antigens.

One year outcome in mild to moderate head injury: the predictive value of acute injury characteristics related to complaints and return to work.

OBJECTIVES: To determine the prognostic value of characteristics of acute injury and duration of post-traumatic amnesia (PTA) for long term outcome in patients with mild to moderate head injury in terms of complaints and return to work. METHODS: Patients with a Glasgow coma score (GCS) on admission of 9-14 were included. Post-traumatic amnesia was assessed prospectively. Follow up was performed at 1, 3, 6, and 12 months after injury. Outcome was determined by the Glasgow outcome scale (GOS) 1 year after injury and compared with a more detailed outcome scale (DOS) comprising cognitive and neurobehavioural aspects. RESULTS: Sixty seven patients were included, mean age 33.2 (SD 14.7) years and mean PTA 7.8 (SD 7.3) days. One year after injury, 73% of patients had resumed previous work although most (84%) still reported complaints. The most frequent complaints were headache (32%), irritability (34%), forgetfulness and poor concentration (42%), and fatigue (45%). According to the GOS good recovery (82%) or moderate disability (18%) was seen. Application of the DOS showed more cognitive (40%) and behavioural problems (48%), interfering with return to work. Correlation between the GOS and DOS was high (r=0.87, p<0.01). Outcome correlated with duration of PTA (r=-0.46) but not significantly with GCS on admission (r=0.19). In multiple regression analysis, PTA and the number of complaints 3 months after injury explained 49% of variance on outcome as assessed with the GOS, and 60% with the DOS. CONCLUSIONS: In mild to moderate head injury outcome is determined by duration of PTA and not by GCS on admission. Most patients return to work despite having complaints. The application of a more detailed outcome scale will increase accuracy in predicting outcome in this category of patients with head injury.

Lightning stroke and neuropsychological impairment: cases and questions.

OBJECTIVE: To objectify neuropsychological impairments in survivors of lightning stroke with lasting complaints about poor concentration and inability to divide their attention. DESIGN: A series of six cases of lightning stroke were studied. All patients had lost consciousness and reported amnesia of varying length. Assessment took place between one and four years after injury, ensuring that their neurological state had stabilised. They were tested with a neuropsychological battery with an emphasis on attention and memory. Personality and emotional reaction to the accident were assessed with questionnaires and a lightning fear scale. Complaints were recorded by means of a trauma complaints list including 10 questions on symptoms of the post-traumatic stress disorder. RESULTS: Patients reported fatigue and lack of energy as their main complaints. In addition, poor concentration, irritability, and emotional lability were mentioned often. Neuropsychological tests disclosed mild impairments in memory, attention, and visual reaction times. Two patients could be classified as depressed, and one of these also showed convincing signs of the post-traumatic stress disorder. CONCLUSION: As the lasting complaints and impairments could not be explained, for all six cases, as resulting from head injury concomitant with lightning stroke, cerebral hypoxia or a post-traumatic stress syndrome, it is concluded that lightning stroke can result in subtle cognitive impairments. It is speculated that most complaints of these survivors are caused by a vegetative dysregulation, a disorder that has often been noted in the literature on the effects of electrical injury to the nervous system. Such a dysregulation might cause both the main complaint of fatigue and the mild cognitive impairments identified with the present test battery.

Deficits of attention after closed-head injury: slowness only?

The performance of a group of 60 severely closed-head-injured patients in the subacute stage of recovery on a series of tests addressing focused, divided, and sustained attention, and supervisory attentional control was compared to the performance of a matched group of 60 healthy controls. Patients performed significantly worse on each test with time pressure (those addressing focused and divided attention), indicating basic slowness of information processing, and on the self-paced tasks for supervisory attentional control. No indication was found of a sustained attention deficit. In a subsequent analysis the influence of the demonstrated slowness of information processing and other possibly confounding cognitive factors was controlled for by means of covariance analyses. This resulted in a disappearance of group differences on tests for focused and divided attention. The only difference that remained concerned a test for supervisory attentional control.

Brain activity related to serial cognitive performance resembles circuitry of higher order motor control.

Differences between two states of cerebral activation were studied in eight subjects by positron emission tomography (PET) of regional cerebral blood flow (rCBF) and subsequent statistical parameter mapping. Subjects had to respond to a row of numbers presented on tape. In one condition they had to repeat each number. In the other condition the last heard number had to be added to the number presented before. Cerebral activity specifically related to the serial addition task was distributed over supplementary motor area (SMA), left premotor cortex and superior dorsal parietal cortex bilaterally, without significant involvement of prefrontal cortex. This indicated circuitry related to mental performance characterised by a fixed strategy of executing serial manipulation of numbers within "internal space". The main aim of this communication is to discuss the similarity between circuitry underlying higher order motor control and pure cognitive performance.

The fronto-temporal component in mild and moderately severe head injury.

The history of the identification of the so-called (fronto-)temporal lobe contusion is reviewed. Treatment of minor head injuries actually starts with the right diagnosis. Injuries of the temporal lobe, characterized by a comparatively long period of post-traumatic amnesia should be distinguished from minor head injuries (cerebral concussion). Treatment of minor head injuries should include good information and explanation of the medical aspects of minor head injuries to prevent the so called post-concussional syndrome, with long lasting sequelae. Changes of neurotransmitter metabolism in various kinds of head injuries have been known for many years. Treatment with precursors of neurotransmitters (particularly physostigmine and L-DOPA) can be useful in unconsciousness and amnestic syndromes.

Cobalt-55 positron emission tomography in traumatic brain injury: a pilot study.

Traumatic brain injury is usually assessed with the Glasgow coma scale (GCS), CT, or MRI. After such injury, the injured brain tissue is characterised by calcium mediated neuronal damage and inflammation. Positron emission tomography with the isotope cobalt-55 (Co-PET) as a calcium tracer enables imaging of affected tissue in traumatic brain injury. The aim was to determine whether additional information can be gained by Co-PET in the diagnosis of moderate traumatic brain injury and to assess any prognostic value of Co-PET. Five patients with recent moderately severe traumatic brain injury were studied. CT was performed on the day of admission, EEG within one week, and MRI and Co-PET within four weeks of injury. Clinical assessment included neurological examination, GCS, neuropsychological testing, and Glasgow outcome scale (GOS) after one year. Co-PET showed focal uptake that extended beyond the morphological abnormalities shown by MRI and CT, in brain regions that were actually diagnosed with EEG. Thus Co-PET is potentially useful for diagnostic localisation of both structural and functional abnormalities in moderate traumatic brain injury.