Porous,Sintered Glass‐Ceramics from Inorganic Polymers Based on Fayalite Slag

The present paper deals with the synthesis of porous, sintered glass‐ceramics obtained at temperatures below 1150°C, originating from inorganic polymers based on fayalite slag. Firing led to the evaporation of water, dehydroxylation, and oxidation of Fe²⁺ above 345°C. For heating >700°C, the Si–O stretching band shifted from the 1160 and 750 cm^?1 to the 1255 and 830 cm^?1 region, due to a structural reorganization of the amorphous phase, whereas Fe–O bands appeared at 550 cm^?1. The final microstructure consisted predominantly of an amorphous phase, hematite, and franklinite. The open porosity and compressive strength decreased and increased, respectively, as the firing temperature increased. The final values suggest properties comparable to that of structural lightweight concrete, still, the materials synthesized herein, are lighter, and made primarily from secondary resources.     

Solution Structure of the Leader Sequence of the Patellamide Precursor Peptide,PatE1–34

The solution structure of the leader sequence of the patellamide precursor peptide was analysed by using CD and determined with NOE‐restrained molecular dynamics calculations. This leader sequence is highly conserved in the precursor peptides of some other cyanobactins harbouring heterocycles, and is assumed to play a role in targeting the precursor peptide to the post‐translational machinery. The sequence was observed to form an α‐helix spanning residues 13–28 with a hydrophobic surface on one side of the helix. This hydrophobic surface is proposed to be the site of the initial binding with modifying enzymes.     

Atmospheric transport of polybrominated diphenyl ethers and polychlorinated biphenyls to the Baltic Sea

The atmospheric transport of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) was compared by measuring concentrations in air and deposition on an island located in the central basin of the Baltic Sea. Median sigmaPBDE and sigmaPCB concentrations (gaseous + particle) were 8.6 and 7.4 pg m(-3), respectively. Airborne PCBs were mainly found in the gaseous phase, while most of the PBDEs were detected on particles, which agrees with predicted particle/gas distributions. SigmaPBDE levels were dominated by the decabrominated BDE209 followed bythe tetrabrominated BDE47 and pentabrominated BDE99. BDE209 is a marker for the environmental distribution of the commercial deca-BDE formulation (>99.5% BDE209), whereas BDE47 and BDE99 are markers for the commercial penta-BDE mixture. General correlations between PBDEs and PCBs suggested similarities in sources and transport mechanism, while more detailed examination of the data identified notable behaviors and exceptions. Differences in regression slopes among tetra-, penta-, and decabrominated PBDEs may reflect different transport processes and the change in usage pattern. Tetra- and pentabrominated PBDEs may originate from secondary sources such as air surface exchange in a manner similar to that of the PCBs, while the deca-BDE209 formulation still has primary sources. The tribrominated BDE17 was also detected and is proposed to be a breakdown product due to atmospheric debromination processes. PBDEs had higher washout ratios than PCBs, explaining their higher concentrations compared to PCBs in precipitation (median of 6.0 and 0.5 ng L(-1) for sigmaBDE and sigmaPCB concentrations ("dissolved" + particle), respectively) than in air. The calculated yearly deposition of PBDEs and PCBs indicated that the atmospheric input of PBDEs to the Baltic Proper is currently exceeding that of the PCBs by a factor of 40, while that of the PCBs is decreasing.     

High prevalence of adynamic bone disease diagnosed by biochemical markers in a wide sample of the European CAPD population

BACKGROUND: Adynamic bone disease (ABD) has been described in the current dialysis population to have an unexpectedly high prevalence. Moreover, it is clearly more prevalent in CAPD patients, compared to haemodialysis patients. Recently we demonstrated that both a low (< or = 27 U/1) level of bone alkaline phosphatase (BAP) as determined by an optimized agarose gel electrophoretic technique and a low (< or = 150 pg/ml ) level of iPTH are good markers of ABD with sensitivities of 78.1% and 80.6% and specificities of 86.4% and 76.2% respectively. METHODS: In this study (n = 212), the prevalence of ABD in the European CAPD population was evaluated by means of these biochemical markers. Clinical data on the patients included were recorded at the moment of blood sampling. In patients under CAPD treatment for longer than 9 months, we calculated an index of calcium exposure through PD fluid. RESULTS: In this population with a low exposure to aluminium, the prevalence of ABD as indicated by either a low level of BAP or PTH was 43%. The following risk factors could be identified: advanced age, shorter time on renal replacement therapy, male gender, and high calcium content of PD fluid. The index of calcium exposure was significantly higher in the patients with low BAP and low iPTH levels compared to those with either BAP > or = 27 U/1 or iPTH > 150 pg/ml. The latter finding gives further support to the hypothesis that a high calcium load administered to renal failure patients may lead to 'oversuppressed' parathyroids in ABD. In a subgroup of patients with a high level of BAP associated with a low iPTH level a profile previously shown to be associated in the presence of aluminium overload, significantly higher serum aluminium levels were noted. suggesting that even in patients with low exposure to aluminium, this element still can affect bone metabolism. CONCLUSION: A high prevalence of ABD--as diagnosed by biochemical markers--was observed in the European CAPD population. A number of risk factors could be put forward. The aetiology and pathogenesis of this type of renal osteodystrophy remain to be elucidated, but appear, however, to be multifactorial.     

Evaluation of a modified enzymatic test for the detection of tetracyclines in milk.

The tetracycline galactosidase (TG) test, a new method for the detection of tetracycline residues in raw milk based on the inhibition of beta-galactosidase biosynthesis in Escherichia coli, was previously validated with spiked milk samples. It has now been applied to milk from cows treated with oxytetracycline. In view of the occurrence of false positives, related to highly elevated somatic cell counts (>10(6)/ml), the improved TG test was developed, in which a heating step (80 degrees C, 15 min) preceded the original TG test protocol. A good agreement with other assays (Delvotest SP, the Bacillus cereus microtiter test, the LacTek tetracycline milk screening test, the Charm HVS-8100 tetracycline test) as well as with high-pressure liquid chromatography was obtained. No false negatives were observed with reference to the established maximum residue limit for tetracyclines of 100 microg/kg milk.     

Trace organic solutes in closed-loop forward osmosis applications: Influence of membrane fouling and modeling of solute build-up

In this study, trace organics transport in closed-loop forward osmosis (FO) systems was assessed. The FO systems considered, consisted of an FO unit and a nanofiltration (NF) or reverse osmosis (RO) unit, with the draw solution circulating between both units. The rejection of trace organics by FO, NF and RO was tested. It was found that the rejection rates of FO were generally comparable with NF and lower than RO rejection rates. To assess the influence of fouling in FO on trace organics rejection, FO membranes were fouled with sodium alginate, bovine serum albumin or by biofilm growth, after which trace organics rejection was tested. A negative influence of fouling on FO rejection was found which was limited in most cases, while it was significant for some compounds such as paracetamol and naproxen, indicating specific compound-foulant interactions. The transport mechanism of trace organics in FO was tested, in order to differentiate between diffusive and convective transport. The concentration of trace organics in the final product water and the build-up of trace organics in the draw solution were modeled assuming the draw solution was reconcentrated by NF/RO and taking into account different transport mechanisms for the FO membrane and different rejection rates by NF/RO. Modeling results showed that if the FO rejection rate is lower than the RO rejection rate (as is the case for most compounds tested), the added value of the FO-RO cycle compared to RO only at steady-state was small for diffusively and negative for convectively transported trace organics. Modeling also showed that trace organics accumulate in the draw solution.     

A Thermodynamic Model of the EAF Process for Stainless Steel

A time‐dependent thermochemical model has been developed for the electric arc furnace (EAF) process for stainless steel production. Time dependency is implemented by a stepwise input of energy and matter into an equilibrium reactor. The equilibrium calculations are performed using data from FACT‐databases and implemented using the programming library ChemApp. The material input for the model was generated by reconciliation of industrial data and the energy input is approximated from the industrial data and scaled through an efficiency factor. The model is used to calculate the evolution of temperature and composition of gas, slag and metal phases with time. Agreement of the end composition in the metal phase with industrial data is good. In the slag phase, however, Cr, Fe, Mn and Si are oxidized significantly less than expected due to excess formation of CO‐gas. The dynamics of the slag composition are examined in more detail. Here a fair agreement is reached for the main slag components. However, for Cr, Fe and Mn the model cannot predict the dynamics, which seem to be strongly kinetically controlled. The results of the equilibrium model can thus provide some insight into the kinetics of the process.     

Synthesis and reactions of polytetrahydrofuran with thiolanium end groups

Living polytetrahydrofuran can be terminated with thiolane to form the corresponding thiolanium-terminated polymers. The thus obtained monotelechelic or ditelechelic polymers are unreactive towards water, but can selectively couple with charged nucleophiles by a nucleophilic ring-opening reaction of the terminal thiolanium ions. This process has been used to prepare well-defined homopolymers such as star polymers, segmented polymers or model networks.