Implementation of a ”data filter” for the UK National Marine Monitoring Programme

The implementation of a strategy for the assessment of the validity of environmental monitoring data – a ”data filter”– is described. The approach was developed through the UK National Marine AQC Scheme for application to data collected during the UK National Marine Monitoring Programme. Data reported for the year 1999, by nine laboratories, for 74 determinand-matrix combinations were assessed on the basis of the completeness of their supporting quality assurance and quality control information. The approach to the establishment of criteria of acceptability for quality information is described. Received: 28 August 2001 Accepted: 29 November 2001     

Global weathering of aromatic engineering thermoplastics

The rates of gloss loss and color shift for 24 aromatic engineering thermoplastics at nine exposure sites world-wide have been compared relative to a commercial Miami exposure site. The scatter among individual samples was large, but on average, light dose alone was enough to account for almost all of the rate differences among the various sites for these materials. Temperature, humidity, rainfall, and acid rain seemed to play minor roles for most samples. Samples containing no particulate pigment had more erratic gloss loss and showed some dependency on the amount of rainfall. The overall “cleanliness” of the samples seemed to be an important factor in gloss retention, and washing protocols during the exposure period and before readings were important variables in cases of slow erosion and/or no particulate pigment. Microbial growth (fungus) was observed on Miami samples after 12–18 months of exposure, but none was seen at any other site.

Relative to Miami defined as 1.0, the average rates of color shift and gloss loss were approximately 0.67 in the northern U.S., 0.8 in the central U.S., and 1.15 in the U.S. desert southwest. Southern Europe was nearly as harsh as Miami, while Northern Europe was comparable to the northern U.S. Northern Europe was found to be somewhat harsher than expected while the northern U.S. was slightly less harsh than expected based on light dose or temperature-weighted light dose. These conclusions apply only to aromatic engineering plastics and should not be assumed to hold for other kinds of materials, such as polyolefins or coatings, without experimental verification.     

Efficient penetration of the basal plane (0001) face of ice Ih by HF at Ts=150 K: dependence on incidence energy, incidence angle, and rotational energy

Classical trajectory simulations are carried out to investigate the influence of incidence energy, incidence angle, and rotational energy on the penetration of the basal plane (0001) face of ice I(h) by HF at a surface temperature (T(s)) of 150 K. The interaction of HF with ice is modelled by pair interactions, with the pair potential fitted to ab initio (Hartree-Fock+MP2) calculations. The penetration of ice by HF occurs already at very low incidence energies, viz., E(i)>/=20 kJ mol(-1). This is much lower than the threshold incidence energy obtained for penetration of ice by HCl (E(i) approximately 96.5 kJ mol(-1)); the calculated average barrier to penetration of ice by HF is 16.0 kJ mol(-1) and is much lower than that previously reported for HCl. As was the case for HCl, penetration of ice by HF decreases with decreasing incidence energy and increasing incidence angle. Though in general, the penetration probability is independent of the molecule's initial rotational energy, penetration beyond the second bilayer (deep penetration) is suppressed by initial rotation. This suggests that, like was found for HCl, the steering operative in deep penetration is inhibited by initial rotation. Finally, because HF is a weak acid experimental observation of HF penetrated into ice may well be possible using infrared spectroscopy, and we suggest experiments along this line.     

Decomposition of 3-connected graphs

Cunningham and Edmonds [4[ have proved that a 2-connected graphG has a unique minimal decomposition into graphs, each of which is either 3-connected, a bond or a polygon. They define the notion of a good split, and first prove thatG has a unique minimal decomposition into graphs, none of which has a good split, and second prove that the graphs that do not have a good split are precisely 3-connected graphs, bonds and polygons. This paper provides an analogue of the first result above for 3-connected graphs, and an analogue of the second for minimally 3-connected graphs. Following the basic strategy of Cunningham and Edmonds, an appropriate notion of good split is defined. The first main result is that ifG is a 3-connected graph, thenG has a unique minimal decomposition into graphs, none of which has a good split. The second main result is that the minimally 3-connected graphs that do not have a good split are precisely cyclically 4-connected graphs, twirls (K _3,n for somen3) and wheels. From this it is shown that ifG is a minimally 3-connected graph, thenG has a unique minimal decomposition into graphs, each of which is either cyclically 4-connected, a twirl or a wheel.Research partially supported by Office of Naval Research Grant N00014-86-K-0689 at Purdue University.     

Mercapto acid compounds of tellurium(II): stabilization of tellurium---sulfur bonded compounds via intramolecular chelation

A series of tellurium (II0 compounds of general formula (RS)₂Te (R = C₆H₅---, 2-C₁₀H₇---, HOOCCH₂CH₂---, HOOCCH(Me)---, HOOCCH₂---, 2-(HOOC)C₆H₄---, HOOCCH₂CH(COOH)---, NaOOCCH₂CH₂---, NH₄OOCCH₂CH₂---) have been prepared and characterized. The tellurium compounds containing carboxylic acid or salt groups are isolated as stable, light-yellow solids which are soluble in alcohols or in water, and this stability is thought to be due to tellurium---carbonyl oxygen interactions within the molecule. Bis(benzenethio)tellurium---(II) and bis(2-naphthalenethio)tellurium(II) have been synthesized and are unstable both in the solid state and in solution. Nixed derivatives containing one aryl and one sulfide bonded to tellurium (ArTeSCH₂CH₂COOH) have also been prepared, and the reactions of these compounds with dichlorobis(benzonitrile)palladium(II) yield palladium complexes containing two tellurium ligands.     

Multiply charged ions in ionspray tandem mass spectrometry

Multiply charged anions of some 30 species containing multiple carboxylic, sulphonic and/or phosphoric groups generated by ionspray were studied by using tandem mass spectrometry (MS/MS). Two trends emerged: (1) lower-charged ions are preferentially evaporated, and (2) for more highly charged ions, evaporability is a function of ion size. Triply and quadruply charged ions were observed for azo dyes with molecular masses in the 700-900 Dalton range. Daughter-ion mass spectra of selected multiply charged ions are presented.     

Preparation,characterization, and binding profile of imprinted semi-IPN cryogel composite for aluminum

Human body is greatly exposed to aluminum due to its high abundance in the environment. This nonessential metal is a threat to the patients of chronic renal disorders, as it is easily retained in their plasma and quickly accumulates in different tissues. Thus, there is great need to remove it from the aqueous environment. In this study, Al³⁺ imprinted semiinterpenetrating polymer network (semi-IPN)-based cryogel composite was prepared and applied for the purification of environmental and drinking water samples from aluminum. Poly (2-hydroxyethyl methacrylate) (pHEMA) discs were produced via cryogenic treatment and imprinted semi-IPN was introduced to the 3-(trimethoxysilyl) propyl acrylatemodified macroporous cryogel discs. The adsorption properties and selectivity of the aluminum (III) imprinted semi-IPN cryogel composite were studied in detail. The imprinted semi-IPN cryogel composite showed good selectivity towards aluminum (III) ions with the imprinting factor (IF) of 76.4 in the presence of competing copper (II), nickle (II), and iron (III) ions. The maximum adsorption capacity of 271 μmol g^-1 was obtained for aluminum (III) at pH 7.0 within 10 min using imprinted semi-IPN cryogel composite. The good selectivity and reusability of aluminum (III)-imprinted semi-IPN cryogel composite makes this material an eligible candidate for the purification of drinking water from aluminum (III) leaving important minerals remained in the water.