Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity.

A common assumption regarding the residual organic matter, in bottom ash, is that it does not represent a significant pool of organic carbon and, beyond metal-ion complexation process, it is of little consequence to evolution of ash/leachate chemistry. This article evaluates the effect of residual organic matter and associated microbial respiratory processes on leaching of toxic metals (i.e. arsenic, copper, chromium, molybdenum, nickel, lead, antimony and zinc), eco-toxicity of ash leachates. Microbial respiration was quantified with help of a respirometric test equipment OXITOP control system. The effect of microbial respiration on metal/residual organic matter leaching and eco-toxicity was quantified with the help of batch leaching tests and an eco-toxicity assay - Daphnia magna. In general, the microbial respiration process decreased the leachate pH and eco-toxicity, indicating modification of bioavailability of metal species. Furthermore, the leaching of critical metals, such as copper and chromium, decreased after the respiration in both ash types (fresh and weathered). It was concluded that microbial respiration, if harnessed properly, could enhance the stability of fresh bottom ash and may promote its reuse.

Effects of substrate induced respiration on the stability of bottom ash in landfill cover environment.

The municipal solid waste incineration bottom ash is being increasingly used to construct landfill covers in Sweden. In post-closure, owing to increased cover infiltration, the percolating water can add external organic matter to bottom ash. The addition and subsequent degradation of this external organic matter can affect metal mobility through complexation and change in redox conditions. However, the impacts of such external organic matter addition on bottom ash stability have not been fully evaluated yet. Therefore, the objective of this study was to evaluate the impact of external organic matter on bottom ash respiration and metal leaching. The samples of weathered bottom ash were mixed with oven dried and digested wastewater sludge (1%-5% by weight). The aerobic respiration activity (AT4), as well as the leaching of metals, was tested with the help of respiration and batch leaching tests. The respiration and heavy metal leaching increased linearly with the external organic matter addition. Based on the results, it was concluded that the external organic matter addition would negatively affect the quality of landfill cover drainage.

Vertical InAs nanowire wrap gate transistors with f(t) > 7 GHz and f(max) > 20 GHz.

In this letter we report on high-frequency measurements on vertically standing III-V nanowire wrap-gate MOSFETs (metal-oxide-semiconductor field-effect transistors). The nanowire transistors are fabricated from InAs nanowires that are epitaxially grown on a semi-insulating InP substrate. All three terminals of the MOSFETs are defined by wrap around contacts. This makes it possible to perform high-frequency measurements on the vertical InAs MOSFETs. We present S-parameter measurements performed on a matrix consisting of 70 InAs nanowire MOSFETs, which have a gate length of about 100 nm. The highest unity current gain cutoff frequency, f(t), extracted from these measurements is 7.4 GHz and the maximum frequency of oscillation, f(max), is higher than 20 GHz. This demonstrates that this is a viable technique for fabricating high-frequency integrated circuits consisting of vertical nanowires.

Potential emissions from two mechanically-biologically pretreated (MBT) wastes.

The interaction of parameters determining the potential emissions of two different mechanically-biologically pretreated municipal solid wastes (MBT wastes) is elucidated in this work. The origins of the wastes are Germany and Sweden. By means of lab-scale experiments, increased stabilisation through composting is preferably determined by a decrease in respiration activity. Concurrently, the stabilisation is verified for the leachates by a decrease in COD, DOC, and BOD(5). Total organic carbon content reflects stabilisation less accurately. FT-IR and thermal analytical methods add valuable information about the state of degradation, especially when several distinct thermal parameters are taken into account. Mobility of Cr, Ni, Pb, and Zn produced by a batch leaching test with deionized water is reduced by the pretreatment of both materials. Mobility of copper unambiguously increased. A principle component analysis (PCA) of membrane fractionated leachates indicates an affinity of Cu to mobile humic acids or dissolved organic carbon. High Cr, Zn, and Ni contents in the solid co-occur with high contents of solid humic acids. To a lesser extent, this is also true for solid Cd, Cu, and Pb contents. Due to differences in required landfilling conditions, actual emissions and after-care phase length will depend on whether each waste is landfilled in Germany or Sweden.

Metal releases from a municipal solid waste incineration air pollution control residue mixed with compost.

The influence of 10 wt.% mature compost was tested on the heavy metal leachate emissions from a calcium-rich municipal solid waste incineration air pollution control residue (MSWI APC). Apart from elongated columns (500 and 1250 mm), an otherwise norm compliant European percolation test setup was used. More than 99% of the metals Al, As, Cd, Cr, Cu, Fe and Ni were left in the APC residue after leaching to a liquid-to-solid ratio (L/S) of 10. Apparent short-term effects of elevated leachate DOC concentrations on heavy metal releases were not detected. Zn and Pb leachate concentrations were one order of magnitude lower for L/S 5 and 10 from the pure APC residue column, which suggests a possible long-term effect of compost on the release of these elements. Prolonging the contact time between the pore water and the material resulted in elevated leachate concentrations at L/S 0.1 to L/S 1 by a factor of 2. Only Cr and Pb concentrations were at their maxima in the first leachates at L/S 0.1. Equilibrium speciation modelling with the PHREEQC code suggested portlandite (Ca(OH)2) to control Ca solubility and pH.

Enalaprilat versus cilazaprilat: a comparison of allergic skin reactions in the guinea pig.

ACE-inhibitors have for some time been used in the treatment of hypertension. Apart from inhibiting the conversion of angiotensin I to II, the drugs also affect the metabolism of some inflammatory agents, like bradykinin and substance P. Egg albumin (EA)-sensitized guinea pigs were pretreated with the ACE-inhibitors. Measurement of flare and wheal areas induced by an intradermal injection of EA, showed that enalaprilat significantly increased, whereas cilazaprilat slightly decreased, the reaction area. Enalaprilat also showed an enhancement in histamine and substance P (SP) contents in the skin. In vitro incubation of guinea pig biopsies with enalaprilat potentiated EA- but not SP-induced histamine release. The EA-induced effect was abolished if the animals were pretreated with capsaicin. The conclusion is that cilazaprilat, in contrast to enalaprilat, does not potentiate inflammatory reactions in the guinea pig.

Significance of group B streptococci in urine cultures from males and non-pregnant females.

Over a 2-year period, 1% of 24,000 urine cultures with possible relevant bacteria from males and non-pregnant females greater than or equal to 15 years of age were found to harbour group B streptococci (GBS) in quantities greater than or equal to 10(5) colony forming units (cfu)/ml; a further 0.9% harboured GBS in quantities greater than or equal to 10(4) but less than 10(5) cfu/ml. Patients with GBS in urine were evenly distributed by age. Those with greater than or equal to 10(5) cfu GBS/ml in voided urine more frequently had true bacteriuria (i.e. bacteria in the urine bladder) than did patients with less amounts (p = 0.01) as determined by suprapubic aspiration of 23 patients. One third (3/9) of the aspirated patients with greater than or equal to 10(5) cfu GBS/ml in simultaneously voided urine, had contaminated urine only and no true bacteriuria. The acute symptoms and clinical conditions of 128 patients with greater than or equal to 10(5) cfu GBS/ml urine were studied by matching 128 patients with negative urine cultures (less than 10(2) cfu/ml) and 128 patients with comparable quantity of Escherichia coli. The incidence of acute lower urinary tract symptoms in patients with GBS was greater than that in patients with negative urine cultures (p less than 0.01), and the same as that in patients with E. coli. The incidence of fever was lower in patients with GBS than in those with E. coli (p less than 0.01). The incidence of urinary tract abnormalities was greatest in patients with GBS in urine. No GBS serotype seems to have particular affinity to the urinary tract.

Prevention of recurrent acute cystitis by methenamine hippurate: double blind controlled crossover long term study.

In a randomised, double blind, long term, crossover study 1 g twice daily of methenamine hippurate was compared with placebo for its preventive effect on recurrent attacks of acute cystitis. Methenamine hippurate and placebo were interchanged every six months for two years. During one of the years patients took 250 ml extra fluid every morning and evening. Out of 21 enrolled patients, 14 completed the first year and 13 both years of treatment, which permitted the evaluation of 27 patient years. There were 52 episodes of acute cystitis caused by reinfection: 41 occurred during placebo treatment and only 11 during the methenamine hippurate regimen (p less than 0.01). Extra fluid intake did not reduce the incidence of acute cystitis, nor did it reduce the effect of methenamine hippurate. Methenamine hippurate is an effective prophylactic agent against recurrent acute cystitis and has the advantage of not inducing cross resistance to conventional antibiotics.

Evaluation of culture methods for isolation of group B streptococci.

Attempts were made to isolate group B streptococci (GBS) from 382 urethral and 140 rectal specimens by overnight incubation in three variants of Todd Hewitt broth, followed by subculture on human blood agar plates. All three broths prepared contained 5% sheep blood, but one contained no antibiotics (THB), while the other two contained gentamicin and nalidixic acid at concentrations of 0.8 microgram/ml and 1.5 micrograms/ml (THBL), and 8 micrograms/ml and 15 micrograms/ml (THBH), respectively. THBL gave the highest isolation frequency both for urethral and rectal specimens. While THBH was superior to THB for isolating GBS in rectal specimens, for urethral samples they were equally effective. Direct plating of 154 specimens on blood agar was less effective than was enrichment in any of the three broths followed by plating on blood agar.

Faecal carriage of group B streptococci.

A study of 1,138 primarily healthy subjects of various ages and sex was conducted to determine the faecal isolation rate of group B streptococci. Five percent of 284 neonates (less than or equal to 5 days old) and 4% of 267 healthy children (1-15 years old) were found to be faecal carriers. Adults were more frequently faecal carriers than children, group B streptococci being isolated in 15% of 361 adults and 11% of 226 pregnant patients. The isolation rate was independent of sex at all ages. Although group B streptococci were found more frequently in rectal than in faecal specimens from pregnant women (p less than or equal to 0.001), the isolation rate for faecal specimens could be increased by using a more selective broth. Forty-four percent of strains isolated from faeces of 105 subjects belonged to serotype III, 27% to type Ia, 15% to type Ib, 11% to type II and 3% were nontypeable. The same serotype of group B streptococci was usually present at different sites in each subject.

Skull growth after coronal suturectomy, periostectomy, and dural transection.

Using radiocephalometric procedures, the authors examined the separate effects of suturectomy, periostectomy, and dural transection on the growing skull in young rabbits. When the coronal suture was surgically removed during normal growth, The freed frontal and parietal bones separated at a significantly accelerated rate. No accelerated separation was found when only the overlying periosteum and aponeurosis were transected. Furthermore, no additional separation was observed when the dura mater and falx cerebri were transected following suturectomy. Analysis of growth at the adjacent frontonasal and anterior lambdoid sutures suggested that the accelerated separation of bones after suturectomy was compensated for by reduced growth at these adjacent sutures. The result of these compensatory actions was that the total length of the skull remained unchanged. This study not only supports earlier observations that sutures grow in response to extrinsic separative forces but, significantly, that the suture tissue itself, rather than the dura or pericranium, acts as a restraint during normal translatory growth.

Craniofacial growth following experimental craniosynostosis and craniectomy in rabbits.

Premature fusion of the coronal suture was produced in 9-day-old rabbits by immobilization of the suture area bilaterally with methyl-cyanoacrylate adhesive. The effects of suture fusion and its surgical release on suture growth and on skull morphology were evaluated by radiographic cephalometry. Immobilization resulted in significant changes in the angular dimensions in the vault toward an anteroposterior shortening. No permanent deformity was observed in the angular relationship between the cranial base and the facial skeleton. Craniectomy at 30 days, when a skull deformity had been established, resulted in rapid separation of the bones at the suture site which returned the deformed skull to a normal configuration by 90 days of age. Surgical removal of a normal suture in a control group also resulted in accelerated separation of the bones at the excised suture site, but it was less than after removal of an immobilized suture. The experimental data indicate that premature fusion of rapidly growing sutures results in consistent skull deformity. Early release of the fusion, when this is the primary abnormality, will result in spontaneous correction of the deformity.