Environmentally friendly phthalocyanine catalysts for water decontamination—Non-photocatalytic systems

Macrocyclic porphyrin-like compounds known as phthalocyanines (Pcs) have been shown to produce singlet oxygen species upon illumination with light of an appropriate wavelength. Singlet oxygen is an effective agent for complete oxidation of common water-soluble pollutants including chlorinated phenols. The most active are, in this respect, phthalocyanines bearing Al, Zn and Si central atoms. Although these compounds were proofed to be virtually non-toxic, the presence of the Al³⁺ and Zn²⁺ ions may contradict this. On the other hand e.g. iron phthalocyanine (FePc) does not represent any danger from this point of view. However, due to the specific coordination of its central metal ion and also because of the number of electrons occupying its valence orbitals, the FePc cannot be effectively activated by the photon flux. Here we report on an alternative system in the dark. It is based on the initial catalytic decomposition of various peroxo substances by metal Pc, producing oxidising species which can decompose chlorinated phenols. A series of Pcs and peroxo substances were compared and the reaction system optimised. It was shown that the highest activity was revealed for the system comprising of FePc and tert-butylhydroperoxide. Iron phthalocyanine was also successfully immobilised on an Al₂O₃ solid matrix, and this heterogeneous system was tested analogously to the homogeneous one. Virtually zero leaching of the anchored complex was detected and the activity was found to be comfortably high.     

Evaluation of mycotoxin-contaminated cereals for their use in animal feeds in Hungary

In the period between December 5, 1991 and September 17, 1998, 760 maize, 367 wheat, 119 soybean, 222 barley, 85 bran, 32 triticale, 60 oat, 14 rye and 22 sunflower samples were investigated for the presence and concentration of seven fusariotoxins (T-2 toxin, zearalenone, deoxynivalenol, nivalenol, diacetoxyscirpenol, HT-2 toxin, fusarenone-X) and OTA. The comparison of analytical data with those of the relevant literature revealed that although the incidence rate and/ or concentration of Fusarium mycotoxins and OTA in Hungarian-grown cereals is occasionally considerable, the position of the country is not worse than the average of countries. Our findings indicate that soybean tends to be good substrate for trichothecene-producing fungi and the rate of contamination is regarded as substantial. The commodities were assorted into one of three quality categories. The proportion of objectionable samples was only 3.0, 2.2, 2.3 and 1.7% in maize, wheat, barley and soybean samples, respectively. However, this low rate of objection might still be a source of great economic loss. The proportion of objectionable samples was much higher in the case of bran, oat and triticale (7.1, 6.7, and 6.3%, respectively). The results of the present investigation indicate a need for regular screening for mycotoxins of importance and individual appraisal of each commodity from the point of their use in animal feeds.     

Bezier surface/surface intersection

The computational requirements and accuracy of two methods for finding the intersection of Bezier surfaces are examined. In both methods, the existence of an intersection curve is confirmed by using the convex hull property of such surfaces. The first method evaluates the intersection by recursive subdivision of two patches with overlapping hulls. The second method detects a point on the intersection curve and then incrementally traces the intersection in the parametric spaces of the two surfaces. With both methods, the intersection of a pair of first-order planar patches must be solved analytically. The intersection is approximated by first-order Bezier patches in the first case and by planar triangles in the second. Overall, the method of incremental tracing is shown to give more accurate results than the method of recursive subdivision     

Coronary artery fistula as a complication of percutaneous transluminal coronary angioplasty

The aim of this study was to assess the quality of storage of tetanus vaccine in accident and emergency (A&E) departments and also of the awareness of Department of Health guidelines. A postal questionnaire was sent to 50 randomly selected major A&E departments in the British Isles, enquiring about awareness of Department of Health guidelines (Department of Health, 1990). Forty (80%) A&E departments responded. Only 14 were aware of the Department of Health guidelines and in only 18 was there a member of staff taking responsibility for vaccine storage. The study found that safe storage of vaccine, and therefore guarantee of efficacy, is not occurring in the majority of A&E departments. Unnoticed failure of refrigerators could be exposing patients to the risk of tetanus infection.     

Uncertainty of pesticide residue concentration determined from ordinary and weighted linear regression curve

Determination of pesticide residues is based on calibration curves constructed for each batch of analysis. Calibration standard solutions are prepared from a known amount of reference material at different concentration levels covering the concentration range of the analyte in the analysed samples. In the scope of this study, the applicability of both ordinary linear and weighted linear regression (OLR and WLR) for pesticide residue analysis was investigated. We used 782 multipoint calibration curves obtained for 72 different analytical batches with high-pressure liquid chromatography equipped with an ultraviolet detector, and gas chromatography with electron capture, nitrogen phosphorus or mass spectrophotometer detectors. Quality criteria of the linear curves including regression coefficient, standard deviation of relative residuals and deviation of back calculated concentrations were calculated both for WLR and OLR methods. Moreover, the relative uncertainty of the predicted analyte concentration was estimated for both methods. It was concluded that calibration curve based on WLR complies with all the quality criteria set by international guidelines compared to those calculated with OLR. It means that all the data fit well with WLR for pesticide residue analysis. It was estimated that, regardless of the actual concentration range of the calibration, relative uncertainty at the lowest calibrated level ranged between 0.3% and 113.7% for OLR and between 0.2% and 22.1% for WLR. At or above 1/3 of the calibrated range, uncertainty of calibration curve ranged between 0.1% and 16.3% for OLR and 0% and 12.2% for WLR, and therefore, the two methods gave comparable results.     

Melt rheology of blends of semicrystalline polymers. I. Degradation and viscosity of poly(ethylene terephthalate)–polyamide-6,6 mixtures

Melt rheology of poly(ethylene terephthalate)–polyamide-6,6, and their blends was studied between 240°C and 300°C, in capillary and rotational rheometers. The flow curves were determined in the range of rate shear from about 10^?2to 10⁵ (s^?1). The results indicate a considerable degree of compatibility, presence of associations between the two types of macromolecules, and cocrystallization. A new mechanism of flow for the blends has been proposed. The study also considers the kinetics of thermal degradation.     

Ten-year trends of heart disease risk factors in the Halifax County MONICA population. MONItoring of trends and determinants in CArdiovascular disease

OBJECTIVE: To investigate trends in heart disease risk factors (RFs) in the general population of Halifax County, Nova Scotia during a 10-year period. DESIGN: Two independent random samples of the population of Halifax County were surveyed in 1985 and 1995; age ranges were 25-64 years and 25-74 years. Blood pressure, cholesterol and body weight were measured. Smoking and health history were obtained by questionnaire. MAIN RESULTS: Participation rate was 66.3% in 1985 and 1995. All RFs were negatively correlated with education attainment. RF changes from 1985 to 1995 were related to education level. Among survey participants, mean body mass index increased from 26.7 kg/m2 to 27.6 kg/m2 (P + 0.005) for men, and from 25.5 kg/m2 to 27.3 kg/m2 (P < 0.00001) for women. Average smoking rate increased from 32.0% to 34.6% (not significant) in men and from 27.7% to 29.1% (not significant) in women. Age-specific smoking rate increased by 13% (P = 0.14) in younger women and decreased by 10% in older women. (P = 0.00). Mean levels of blood cholesterol decreased by 0.2 mmol/L (P = 0.002) in men and 0.1 mmol/L (P = 0.20) in women. Systolic blood pressure increased by 6.3 mmHg (P < 0.0001) in men and by 7.9 mmHg (P < 0.0001) in women, being steepest in the lower education group. Mortality predicted from RFs declined between the survey years, but less than the observed mortality. This discrepancy may result from the effect of medical care or the delayed effect of RF changes. CONCLUSIONS: Some risk factors show a disturbing trend, indicating that an increased effort or a change in strategy is needed to combat the risk of ischemic heart disease.     

An Adaptive Secure and Efficient Routing Protocol for Mobile Ad Hoc Networks

The rapidly emerging wireless service requirements and deployment demands over last few decades necessitates the application of Mobile Ad hoc Networks in many areas. These application areas vary from social networks to safety-critical domains such as environmental monitoring, disaster rescue operations, military communications, etc. The potency of the ad hoc network deployment in a specific context is significantly affected by the underlying routing protocol. Hence, developing an efficient and secure routing protocol for MANETs is an important task in order to achieve the service level requirements and to satisfy the deployment demands effectively. However, development of such routing protocol is a challenging problem due to the inherent characteristics of ad hoc networks: frequent topology changes, open wireless medium, and limited resource constraints, etc. In addition, the stringent requirements: mobility, performance, security, trust and timing constraints, etc. add complexity to this problem. In this paper, we present an adaptive routing protocol for MANETs, which dynamically configures the routing function with respect to the metrics: (1) the varying requirement parameters and (2) the contextual features as per the desired application context. The requirement models include various performance, security, and functional parameters. On the other hand, the contextual features include mobility of nodes/groups of nodes, nodes’ trust values, resource constraints of nodes, geographical context, roles of individual nodes etc. Our routing protocol is evaluated with extensive simulation test cases and the efficacy of the protocol is reported.