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At least 1,621 records · Page 90Linked to original sources
PubMed2006

Influence of organic matter on municipal solid waste incinerator bottom ash carbonation.

The biodegradation of organic matter in municipal solid waste incinerator (MSWI) bottom ash was studied in order to investigate the interaction between the CO(2) produced by microbial respiration and bottom ash. Respiration tests were performed on bottom ash at different moisture contents in an incubator at 30 degrees C. O(2) consumption and CO(2) production were monitored and quantified. Leaching tests were carried out at the end of the experiments. Total organic carbon (TOC) leaching had decreased. Over a period of three weeks, pH decreased from 10.7 to 8.2 and bottom ash was considered to be fully carbonated. This showed that the organic matter found in bottom ash can provide a substrate for microbial activity. The CO(2) produced by microbial respiration was directly dissolved in bottom ash pore water in order to be mineralized in carbonate form. The origin of the carbon dioxide which induces maturation of bottom ash on weathering areas has never been really discussed and is often presumed to be atmospheric CO(2). However, biodegradation of organic matter could contribute for a large part to this phenomenon, depending on field-scale physico-chemical weathering conditions.

Bacteria, Aerobic↗
PubMed2005

Cognitive impairment and diffuse white matter atrophy in alcoholics.

OBJECTIVE: Diffuse brain white matter atrophy is often seen in chronic alcoholics, but its relation with cognitive impairment remains to be solved. In order to address this issue, in alcoholics with cognitive impairment at different levels, we studied relations of the central sensory conduction time (CSCT) or brain magnetic resonance imaging (MRI) findings with the cognitive function. METHODS: Subjects were 35 alcoholics with mild cognitive impairment (mini-mental state examination score, MMSE, >/=24; mean+/-SD, 27.7+/-1.9), 12 with moderate to severe cognitive impairment (MMSE<24; 20.3+/-2.7), 15 with Alzheimer's disease (AD) (MMSE, 18.9+/-4.3) (disease control) and 20 healthy volunteers (MMSE, 28.5+/-1.6) (normal control). Median nerve SEPs were recorded in the all subjects, and the latencies and amplitudes of their N9, N11, P13/14, N20 and P25 components were measured. The ventriculocranial ratio (VCR) and the width of cortical sulci were measured on MRIs. These physiological parameters and MRI findings were compared between the 4 groups of the subject, and correlations between those all features were also analyzed. RESULTS: CSCT and VCR were significantly greater in alcoholics with moderate to severe cognitive impairment than those in the other 3 groups. Pearson's product-moment correlation analyses of the alcoholics disclosed that both the CSCT and VCR had significant negative correlations with the MMSE score. Moreover, the CSCT and VCR were positively correlated. CONCLUSIONS: Both physiological and morphological estimates of the white matter function (CSCT and VCR) had a significant correlation with the cognitive dysfunction. SIGNIFICANCE: The diffuse white matter atrophy may be one of the factors causing cognitive impairment in chronic alcoholics.

Aged↗
PubMed2005

Cerebral white matter hyperintense lesions are associated with unstable carotid plaques.

OBJECTIVES: The aim of this study was to determine whether unstable carotid plaques, a known risk factor for cerebral emboli, are associated with cerebral white matter lesions. METHODS: Seventy-one symptomatic patients undergoing magnetic resonance imaging prior to carotid endarterectomy for high grade carotid stenosis were included in this study. The number and volume of white matter hyperintense lesions (WMHL) on fluid attenuated inversion recovery brain scans were compared according to the morphology of carotid plaque based upon the American Heart Association (AHA) histological classification. RESULTS: Of the 57 patients who had good quality brain scans and non-fragmented carotid plaques, 15 plaques were defined as stable (type V) and 42 as unstable (type VI). After adjustment for the major risk factors affecting WMHL, unstable carotid plaques were found to be associated with more WMHL in the ipsilateral cerebral hemisphere than stable plaques (transformed means 2.50+/-1.2 vs. 1.53+/-1.1, p=0.016), however, there was only a trend towards larger WMHL volumes (p=0.079). CONCLUSIONS: The observed association between unstable carotid plaques and the number of white matter lesions suggest that thromboembolic plaque activity may contribute to the development of leukoaraiosis, in particular smaller individual lesions. Larger studies are warranted to confirm this finding and explore the potential clinical impact for selecting candidates for carotid endarterectomy.

Aged↗
PubMed2004

Effects of dissolved organic matter on toxicity and bioavailability of copper for lettuce sprouts.

It is well known that dissolved organic matter in soil solution may affect the toxicity or bioavailability of heavy metals to plants, but existing information on various organic substances is insufficient for treating problems with heavy metal-contaminated soils. To clarify how dissolved organic matter alters the toxicity and bioavailability of metals, we germinated lettuce seeds exposed to solutions containing Cu and several kinds of dissolved organic matters. Low molecular weight organic acids (citric, malic, and oxalic acids) increased the toxicity and bioavailability of Cu, but low concentrations of the synthetic chelators ethylenediamine tetra-acetic acid (EDTA) and diethylenetriamine penta-acetic acid (DTPA) decreased the toxicity and bioavailability of Cu. In contrast, humic acid appeared to be the most effective organic substance for detoxifying Cu, even though it did not significantly decrease the bioavailability of Cu. Consequently, the bioavailability and toxic effects of Cu in soil depend on the nature of coexisting organic substances in the soil solution.

Biological Availability↗
PubMed2005

Identifying the source, transport path and sinks of sewage derived organic matter.

Since sewage discharges can significantly contribute to the contaminant loadings in coastal areas, it is important to identify sources, pathways and environmental sinks. Sterol and fatty alcohol biomarkers were quantified in source materials, suspended sediments and settling matter from the Ria Formosa Lagoon. Simple ratios between key biomarkers including 5beta-coprostanol, cholesterol and epi-coprostanol were able to identify the sewage sources and effected deposition sites. Multivariate methods (PCA) were used to identify co-varying sites. PLS analysis using the sewage discharge as the signature indicated approximately 25% of the variance in the sites could be predicted by the sewage signature. A new source of sewage derived organic matter was found with a high sewage predictable signature. The suspended sediments had relatively low sewage signatures as the material was diluted with other organic matter from in situ production. From a management viewpoint, PLS provides a useful tool in identifying the pathways and accumulation sites for such contaminants.

Environmental Monitoring↗
PubMed2005

Unconfined compression of white matter.

The porous properties of brain tissue are important for understanding normal and abnormal cerebrospinal fluid flow in the brain. In this study, a poroviscoelastic model was fitted to the stress relaxation response of white matter in unconfined compression performed under a range of low strain rates. A set of experiments was also performed on the tissue samples using a no-slip boundary condition. Results from these experiments demonstrated that the rheological response of the white matter is primarily governed by the intrinsic viscoelastic properties of the solid phase. The permeability of white matter was found to be of the order of 10(-12) m4/Ns.

Animals↗
PubMed2005

Enhanced removal of organic matter and ammoniacal-nitrogen in a column experiment of tidal flow constructed wetland system.

A tidal flow constructed wetland system was investigated for the removal of organic matter and ammoniacal-nitrogen from diluted piggery wastewater. The results demonstrated that the operation of tidal flow enhanced the transfer of oxygen into wetland matrices. The supply of oxygen by the operation (473 gO2/m2d) matched the demand for wastewater treatment. The overall oxygen consumption rate in the system was considerably higher than the typical rate obtainable in conventional wetlands; most oxygen being used for the decomposition of organic matter. Compared with conventional systems, the tidal flow system demonstrated greater efficiency in the removal of organic matter. Significant nitrification did not take place, although 27-48% ammonia was removed from the wastewater. Immobilization by microbial cells and adsorption were the likely routes to remove ammonia under the specific experiment conditions. Percentage removals of BOD5, NH4-N and SS increased after effluent recirculation at a ratio of 1:1 was employed.

Ammonia↗
PubMed2004

Histological and immunocytochemical characterization of neurons located in the white matter of the spinal cord of the pigeon.

In the spinal cord of birds a considerable number of neuronal somata is located outside the gray matter. Some of these neurons form segmental marginal nuclei, which lie at the border of the spinal cord near the dentate ligament. In lumbosacral segments these marginal nuclei form accessory lobes which bulge into the vertebral canal. These lobes consist in neurons which are embedded into glia-derived glycogen cells. Furthermore, there are neurons in the white matter near the accessory lobes and numerous paragriseal cells lying in the lateral and ventral funiculus. Glycogen cells are present both in the lobes and in the glycogen body which fills the lumbosacral spinal rhomboid sinus. Immunoreactivity of glial fibrillary acidic protein, a marker of astrocytes, was used to characterize the surrounding of marginal neurons. Astrocytes were numerous in cervical marginal nuclei but rare in accessory lobes. There is cytological (distribution of Nissl substance) and immunocytochemical evidence (immunoreactivity of medium-sized neurofilament, glutamic acid decorboxylase and glutamatergic AMPA receptor subtype GluR2/3) that neurons of the accessory lobes and the nearby white matter are similar, whereas paragriseal cells are different.

Animals↗
PubMed2004

Kinetic study on the sorption of dissolved natural organic matter onto different aquifer materials: the effects of hydrophobicity and functional groups.

The subsurface sorption of Suwannee River fulvic acid (SRFA) and humic acid (SRHA) onto a synthetic aquifer material (iron-oxide-coated quartz) and two natural aquifer materials (Ringold sediment and Bemidji soils) was studied in both batch and column experiments. The hypothesis that hydrophobic effects followed by ligand exchange are the dominant mechanism contributing to the chemical sorption happening between dissolved natural organic matter (NOM) and the mineral surfaces is supported by observations of several phenomena: nonlinear isotherms, faster sorption rates versus slower desorption rates, phosphate competition, a solution pH increase during NOM sorption, and functional groups and aromaticity-related sorption. In addition, high-pressure size exclusion chromatography (HPSEC) and carboxylic acidity showed that lower molecular weight NOM components of SRHA are preferentially sorbed to iron oxide, a result in contrast to that for SRFA. Phosphate increased the desorption of sorbed NOM as well as soil organic matter. All of these trends support ligand exchange as the dominant reaction between NOM and the iron oxide surfaces; however, if the soil surface has been occupied by soil organic matter, then the sorption of NOM is more due to hydrophobic effect.

Adsorption↗
PubMed2006

Investigating sorption-driven dissolved organic matter fractionation by multidimensional fluorescence spectroscopy and PARAFAC.

Soil organic matter is involved in many ecosystem processes, such as nutrient supply, metal solubilization, and carbon sequestration. This study examined the ability of multidimensional fluorescence spectroscopy and parallel factor analysis (PARAFAC) to provide detailed chemical information on the preferential sorption of higher-molecular-weight components of natural organic matter onto mineral surfaces. Dissolved organic matter (DOM) from soil organic horizons and tree leaf tissues was obtained using water extracts. The suite of fluorescence spectra was modeled with PARAFAC and it was revealed that the DOM extracts contained five fluorescing components: tryptophan-like (peak location at excitation <255 nm:emission 342 nm), tyrosine-like (276 nm:312 nm), and three humic-substance-like components (<255 nm:456 nm, 309 nm:426 nm, <255 nm:401 nm). In general, adsorption onto goethite and gibbsite increased with increasing DOM molecular weight and humification. PARAFAC analysis of the pre- and post-sorption DOM indicated that the ordering of sorption extent was humic-like components (average 91% sorption) > tryptophan-like components (52% sorption) > tyrosine-like components (29% sorption). This differential sorption of the modeled DOM components in both the soil organic horizon and leaf tissue extracts led to the fractionation of DOM. The results of this study demonstrate that multidimensional fluorescence spectroscopy combined with PARAFAC can quantitatively describe the chemical fractionation process due to the interaction of DOM with mineral surfaces.

Adsorption↗
PubMed2006

Depth profiles of radiocarbon and carbon isotopic compositions of organic matter and CO2 in a forest soil.

Depth profiles of the specific activities of (14)C and carbon isotopic compositions (Delta(14)C, delta(13)C) in soil organic matter and soil CO(2) in a Japanese larch forest were determined. For investigating the transport of CO(2) in soil, specific activities of (14)C, Delta(14)C and delta(13)C in the organic layer, and atmospheric CO(2) in the same forest area were also determined. The specific activity of (14)C and Delta(14)C in the soil organic matter decreased with the increase in depth of 0-60cm, while that of soil CO(2) did not vary greatly at a soil depth of 13-73cm and was more prevalent than that of atmospheric CO(2). Peaks of specific activities of (14)C appeared at the depth of 0-4cm and Delta(14)C values were positive in the depth range from 0 to 15cm. These results suggest that the present soil at a depth of 0-4cm had been produced from the mid-1950s up until 1963, and the bomb C had reached the depth of 15cm in the objective soil area. The delta(13)C in the soil organic matter increased at the depth of 0-55cm, while that of soil CO(2) collected on 8 November 2004 decreased rapidly at the depth of 0-13cm and only slightly at the depth of 53-73cm. By combining the Delta(14)C and delta(13)C of the respective components and using the Keeling plot approach it was made clear that the entering of atmospheric CO(2) showed a large contribution to soil CO(2) at the depth of 0-13cm and a negligible contribution at the depth of 53-73cm for soil air collected on 8 November 2004. Respiration of live roots was presumed to be the main source of soil CO(2) at the depth of 53-73cm on 8 November 2004.

Carbon Dioxide↗
PubMed2005

Effects of particle size, organic matter and ionic strength on the phosphate sorption in different trophic lake sediments.

The trophic status and development of lake system is significantly influenced by the phosphate sorption at the sediment-water interface. The effects of organic matter, particle size and ionic strength on the phosphate sorption by sediments were investigated in this study. The results show that maximum phosphate sorption capacity (Qmax), equilibrium phosphate concentration (EPC0), phosphate sorption efficiency (k) and phosphate sorption rate decreased as particle size increased for all the studied sediments. But the reliable desorbed phosphorus (RDP) increased. Qmax, EPC0, k and RDP of different particle size fractions varied and there were no obvious differences among different trophic lake sediments. Qmax, EPC0 increased while k and RDP decreased as the pollution level of lake sediment increased. The phosphate sorption mainly occurred within 0.5 h. Power function and simple Elovich models were the best kinetic models for the phosphate sorption of the different particle size fractions. Qmax and phosphate sorption rate decreased with the decreasing of organic matter content of sediments and the increasing of ionic strength. This study suggests that ionic strength and organic matter had similar effects on the phosphate sorption for different trophic lake sediments.

Absorption↗
PubMed2004

Morphometry of cervical segments grey matter in the male rat spinal cord.

The cervical portion of the spinal cord is an area frequently affected by alterations of medical and veterinary importance. Since there is scarce quantitative anatomical data on this region, we undertook a morphometric study of the grey matter of all segments of the rat cervical spinal cord of male rats in order to generate reference patterns to be used in future experimental studies. Using image analysis software, the total spinal cord length and grey and white matter area of each segment was recorded. The morphometric characteristics of the neurones populating the laminae of the grey matter of the cervical segments was also recorded. Neurones were classified into small, medium and large sizes for each lamina and statistically compared. The present data fill an anatomical information gap by providing quantitative data about the normal anatomical features of the rat cervical cord. The anatomical data found could be used to better understand the physiological relevance of that region in the rat.

Animals↗
PubMed2004

An autopsied case of Sjogren's syndrome with massive necrotic and demyelinating lesions of the cerebellar white matter.

A 69-year-old woman developed subacute cerebellar ataxia and tremors in all four limbs in April 1996. Laboratory examination showed elevated antibodies against Ro and La. Head magnetic resonance imaging showed T(2) high-intensity lesions in the cerebellar white matter bilaterally and later in the pons. In April 2000, she died of multiple organ failure with incidental colon cancer. The autopsy showed atrophic parotid glands with an accumulation of lymphocytes around the ducts, confirming the diagnosis of Sjogren's syndrome histopathologically. The neuropathological examination revealed severe necrotic lesions in the cerebellar white matter bilaterally with several foci of perivenous demyelination in the periphery of the lesions and similar demyelinated areas in the pons. Immunohistochemistry with anti-JC virus antibody demonstrated no positive inclusions. A single focus of granulomatous arteritis was observed in one subarachnoid artery. The combination of Sjogren's syndrome, granulomatous angitis, and foci of perivenous demyelination suggests that an autoimmune mechanism played an important role in causing the necrotic lesions in the cerebellar white matter in this case.

Aged↗
PubMed2005

Comparison of polycyclic aromatic hydrocarbon distributions and sedimentary organic matter characteristics in contaminated, coastal sediments from Pensacola Bay, Florida.

In this study, we examined the distribution of polycyclic aromatic hydrocarbons (PAHs) in a contaminated coastal area and the characteristics of the natural organic matter in tandem. We present a detailed study of PAH concentration, distribution, and organic matter characteristics of three core samples from Pensacola Bay, Florida. Solid-state 13C Nuclear Magnetic Resonance (NMR), pyrolysis gas chromatography coupled with mass spectrometry (GC-MS), and tetramethyl ammonium hydroxide (TMAH) thermochemolysis GC-MS were applied to obtain structural details about the sedimentary organic matter. Elemental compositions (carbon and nitrogen) and estimates of black carbon contents are also reported. These coastal sediments were found to contain more PAHs in the upper 15 cm layers than in the bottom 15-25 cm samples. The samples that contained the most PAHs also contained the least amount of aromatic carbon and contained a significant amount of paraffinic carbon. Lignin-derived pyrolysis and TMAH thermochemolysis products were abundant and generally higher in all of the samples in comparison to those reported for modern coastal sediments, indicating a large flux of terrestrial carbon. The black carbon contents were found to range from 4.3% to 6.8%, which are significantly lower than other reports of black carbon in sediments, which represent as much as 65% of the total organic carbon content. The low black carbon content suggests that this type of refractory carbon may not be as responsible for regulating PAH distribution as indicated by other researchers.

Carbon Isotopes↗
PubMed2006

Defective translation initiation causes vanishing of cerebral white matter.

Leukoencephalopathy with vanishing white matter (VWM) is one of the most prevalent inherited white-matter disorders, especially in Caucasian populations. VWM is unusual because of its sensitivity to febrile infections and minor head trauma. The basic defect of this enigmatic brain disease resides in the regulation of initiation of protein synthesis. Recently, undue activation of the unfolded-protein response has emerged as an important factor in the pathophysiology of VWM. Here, we discuss the mechanisms that might be responsible for the selective involvement of the brain white matter in VWM. At present, VWM research is in need of an animal model to study disease mechanisms and therapeutic interventions.

Animals↗
PubMed2006

Advances in white matter imaging: a review of in vivo magnetic resonance methodologies and their applicability to the study of development and aging.

Several newer magnetic resonance imaging (MRI) techniques are increasingly being applied to the study of white matter development and pathology across the lifespan. These techniques go beyond traditional macrostructural volumetric methods and provide valuable information about underlying tissue integrity and organization at the microstructural and biochemical levels. We first provide an overview of white matter development and discuss the role of white matter and myelin in cognitive function. We also review available studies of development that have employed traditional volumetric measures. Then, we discuss the contributions of four newer imaging paradigms to our understanding of brain development and aging. These paradigms are Diffusion Tensor Imaging (DTI), Magnetization Transfer Imaging (MTI), T2-Relaxography, and Magnetic Resonance Spectroscopy (MRS). Studies examining brain development during childhood and adulthood as well as studies of the effects of aging are discussed.

Aging↗
PubMed2006

Neuroprotection of alpha-phenyl-n-tert-butyl-nitrone on the neonatal white matter is associated with anti-inflammation.

Our previous study has demonstrated that alpha-phenyl-tert-butyl-nitrone (PBN) provided neuroprotection to the neonatal white matter following cerebral hypoxia-ischemia (HI). Free radical scavenging was involved in the neuroprotection of PBN. To investigate if other mechanisms contribute to the neuroprotection of PBN, postnatal day 4 SD rats were subjected to bilateral common carotid artery ligation, followed by 8% oxygen exposure for 20min. A single dose of PBN (100mg/kg, i.p.) was given prior to the hypoxic exposure. Expression of inflammatory cytokines: interleukin-1beta (IL-1beta), inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) was determined by RT-PCR, ELISA and immunohistochemistry. Activation of transcriptional factor nuclear factor-kappa B (NF-kappaB) was measured by ELISA. PBN significantly inhibited HI-induced up-regulation of IL-1beta, TNF-alpha and iNOS mRNA expression at 4h following HI. PBN treatment also reduced the brain concentration of IL-1beta significantly and decreased the number of IL-1beta- or iNOS-expressing cells in the white matter area at 12h following HI. Moreover, PBN suppressed the HI-induced NF-kappaB activation at 1h after HI. The overall results indicate that besides free radical scavenging, anti-inflammation might partly contribute to the neuroprotection afforded by PBN on neonatal white matter following cerebral HI.

Animals↗