Residual disinfection with N-halamine based antimicrobial paints

An N-halamine acrylamide monomer was copolymerized with the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid to produce water-dispersible/soluble polymers. The polymers were added into a water-based latex paint and the treated paints were rendered antimicrobial upon chlorination with dilute household bleach. The chlorinated paints were exposed to fluorescent and ultraviolet light for several periods of time. The bound chlorine on the polymers was remarkably stable and the remaining chlorine on the treated paints after several weeks of light exposure was sufficient to provide 6-log inactivations of both Gram-positive and Gram-negative bacteria within 5–10 min of contact time. The samples exposed light could be rechlorinated to their initial chlorine loadings, indicating that the polymers were also very stable toward light irradiation. This study describes an effective approach to prepare antimicrobial surfaces providing long-term disinfection.     

A fuzzy DEMATEL-based solution approach for facility layout problem: a case study

Facility layout in production systems is a difficult activity since both qualitative and quantitative factors affect the location decision, and also influence and causal relationship between these factors should be determined for a better location. In this respect, it is demonstrated in this study that fuzzy decision-making trial and evaluation laboratory (fuzzy DEMATEL) method can effectively be used in handling facility layout problems in practice. The qualitative factors that described by linguistic terms can be taken into account through fuzzy structure of the method. Considering this, a fuzzy DEMATEL-based solution approach for facility layout problem is proposed in this study. The proposed approach takes into account both qualitative and quantitative location factors. To address the need in practice, six important location factors are considered in this study. These are material flow, information flow, personnel flow, equipment flow, environmental condition, and supervision of personnel. This study differs from the previous works in that it applies fuzzy DEMATEL method to facility layout problem. To explore the viability of the proposed approach, a real world problem in a machinery industry firm is handled.     

自水解预处理对稻草化学成分及酶解性能的影响

研究了自水解处理对稻草秸秆主要化学成分及酶解糖化效率的影响。结果显示:在100～160℃下对稻草进行自水解预处理,酸溶木质素的脱除程度随着自水解温度的升高而增大,而Klason木质素含量几乎没有变化,几乎全部SiO2仍然保留在预处理后草片中;稻草高聚糖的降解程度随着自水解温度的升高而增加,但由于自水解液酸性较弱,大量高聚糖仍保留在草片中;自水解预处理有利于促进稻草的酶解糖化,随着自水解预处理温度的升高和酶用量的增大,酶解液中各种聚糖得率均有不同程度的提高,但自水解温度的影响显得更为重要;经160℃自水解预处理的稻草在40 FPU/g混合酶用量下,葡聚糖和木聚糖的总转化率约为68%和45%,总糖转化率近60%。     

Combined experimental and kinetic modeling studies for the conversion of gasoline range hydrocarbons from methanol over modified HZSM-5 catalyst

The reaction was carried out in fixed bed reactor. The effect of process variables on the activity of oxalic acid treated 0.5 wt% ZnO/7 wt% CuO/HZSM5 catalyst for the conversion of methanol to gasoline range hydrocarbons was studied. The catalyst was prepared by incipient wetness impregnation method. After impregnation the catalyst was treated with oxalic acid. The validity of kinetic model proposed for the methanol to gasoline range hydrocarbon process at zero time on stream was studied, from the experimental results obtained in a wide range of operating conditions. The kinetic parameters for various models were calculated by solving the equation of mass conservation in the reactor for the lumps of the kinetic models. The kinetic model fitted well for simulating the operation in the fixed bed reactor in the range of 635 to 673 K, with regression coefficient (R²) higher than 0.96.     

Development and characterization of an enzymatic method for the rapid determination of gamma hydroxybutyric acid

Gamma hydroxybutyric acid (GHB) is a regulated therapeutic drug, which naturally occurs in mammalian brain tissues as an intermediate of the GABA (gamma aminobutyric acid) neurotransmitter metabolism. The increasing misuse of GHB as a narcotic or abusing drug in recent years calls for the development of a simple and rapid screening method as an alternative to the currently available, technically demanding diagnostic methods. We have developed a rapid enzymatic assay based on the GHB dehydrogenase of Ralstonia eutropha. The enzyme is expressed as a recombinant protein in Escherichia coli and characterized in terms of reaction mechanism and kinetic parameters for the catalysis of conversion of GHB into succinic semialdehyde (SSA). The concomitant NADH production enables spectrophotometric monitoring of the reaction and the quantification of GHB in physiological fluids depending on initial velocities. We have tested a panel of twelve serum and urine samples containing GHB concentrations from 0.0 to 2.1 mmol/L. GHB dehydrogenase activity obeys a non classical bi bi ping pong mechanism exhibiting substrate inhibition by NAD+. With an optimal NAD+ concentration of 3.7 mmol/L in the reaction, the enzyme yields a K(M) of 1.0 mmol/L for GHB and a Vmax of 3.37 mmol/min/mg. The assay shows a linear standard curve from 0.1 to at least 1 mmol/L of GHB. Spiking experiments result in mean recoveries of 92% for urine and 114% for serum, respectively. The comparison to an ion chromatographic reference method exhibits a mean difference of 10% divergence from the target values in urine and 9% in serum, respectively.     

Options to reduce the environmental impacts of residential buildings in the European Union—Potential and costs

A typology of buildings representative of the building stock for the EU-25 was developed characterizing 72 building types in terms of their representativity, geographical distribution, size, material composition, and thermal insulation. The life cycle impacts of the building types were calculated for different environmental impact categories both at building and EU-25 level. The use phase of buildings, dominated by the energy demand for heating is by far the most important life cycle phase for existing and new buildings. The environmental impacts were allocated to single building elements. Ventilation, heat losses through roofs and external walls are important for a majority of single- and multi-family houses. Three improvement options were identified: additional roof insulation, additional façade insulation and new sealings to reduce ventilation. The measures yield a significant environmental improvement potential, which, for a majority of the buildings types analyse represent at least 20% compared to the base case. The major improvement potentials at EU-level lie with single-family houses, followed by multi-family houses. Smaller reductions are expected for high-rise buildings due to the smaller share in the overall building stock. For both roof insulation and reduced ventilation, the measures were shown to be economically profitable in a majority of buildings.     

Mercury levels in cord blood and meconium of healthy newborns and venous blood of their mothers: clinical, prospective cohort study

OBJECTIVES: The purpose of this study is to investigate the chronic mercury intoxication in pregnant women and newborns living in Istanbul, Turkey. METHODS: The research was carried out as a prospective with 143 pregnant women and their newborns. Venous blood from the mother, cord blood from the neonate, and meconium were collected for mercury analysis. Frequency of fish and vegetable-eating and the number of teeth filled were investigated. Analyses were made in cold vapor Atomic Absorption Spectrophotometer (AAS, microg/L). RESULTS: Mercury levels were 0.38+/-0.5 microg/L (0-2.34) in venous blood of pregnant women, 0.50+/-0.64 microg/L (0-2.36) in umbilical cord blood and 9.45+/-13.8 microg/g (0-66.5) in meconium. Maternal blood mercury level was lower than the known toxic limit for humans (EPA, 5 microg/L). Mercury levels of the maternal venous blood were significantly correlated with umbilical cord blood. The primary risk factors affecting mercury levels were eating fishmeals more than twice a week and having filled teeth more than five. The fact that the mother had a regular vegetable diet everyday reduced the mercury levels. Increased levels of mercury in the mother and umbilical cord blood could lead to retarded newborns' weight and height. CONCLUSION: Pregnant women living in Istanbul may be not under the risk of chronic mercury intoxication. Fish consumption more than twice per week and tooth-filling of mother more than five may increase mercury level. On the contrary, regular diet rich in vegetable decreases the mercury level.     

Effects of condensing moist air on shock induced oscillation around an airfoil in transonic internal flows

Shock induced oscillation around an airfoil in transonic internal flow fields are often observed due to complex shock wave boundary layer interaction. However, in actual flow where finite amount of water vapor is present in the air, the rapid expansion of the flow may give rise to non-equilibrium condensation. Effects of condensing moist air on unsteady shock induced oscillation were numerically studied for total back pressure to reservoir pressure ratios of 0.73–0.65. Results showed that in case with condensing moist air flows, the root mean square of shock induced pressure oscillation and the oscillation frequency were reduced significantly compared with those without the non-equilibrium condensation. However, there was an increase of total pressure loss for condensing moist air flows.     

Structural and magnetic analysis of nanocrystalline lead europium sulfide (PbxEuyS)

We report the synthesis and characterization of nanocrystalline Pb_xEu_yS, a potentially important dilute magnetic semiconductor. The thermolysis of mixed precursors was adapted for the formation of homogeneous alloyed nanocrystals. Energy dispersive spectroscopy provided the atomic composition for Pb_xEu_yS nanocrystals, which we juxtaposed with the ratio of the precursors. X-ray diffraction and magnetization measurements of the nanocrystals provided evidence that no phase separation occurred for europium concentrations of up to y = 0.15.