Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions

Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1–3% (w?w^?1) aqueous ammonium bifluoride (NH₄HF₂). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH₄HF₂ solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels manyfold below those reported previously for this methodology. Notably, MDLs for Be of <0.01 ng L^?1 /0.1 ng per sample have been attained, which are superior to MDLs routinely reported for this element by means of the most widely used ultra-trace elemental measurement technique, inductively coupled plasma mass spectrometry (ICP-MS). Very low MDLs for Be are essential in consideration of reductions in OELs for this element in workplace air by health organisations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly designed occupational air sampler inserts are illustrated.     

A simple non-invasive method to detect and monitor hypercapnia: the sodium [13C]bicarbonate breath test

Arterial partial pressure of carbon dioxide (paCO(2)) is commonly evaluated by an invasive test, the arterial blood gas analysis (ABG). The sodium [(13)C]bicarbonate breath test (SBT) can potentially estimate arterial paCO(2). We studied 55 subjects with respiratory disorders and performed the ABG and the SBT to determine if the SBT can predict hypercapnia. The percentage of (13)CO(2) recovered in exhaled breath at 30 minutes (PDR(30)) alone was able to discriminate clinically significant hypercapnia (>53 mmHg) with a sensitivity of 82 % and specificity of 93 % (p<0.001). To evaluate the clinical utility of the SBT as a non-invasive substitute to repeated ABG, we monitored the progress of seven chronic obstructive pulmonary disease (COPD) patients on therapy with both the ABG and the SBT. The PDR(30) values from the SBT were able to correctly predict improvement or worsening of paCO(2) with 100 % accuracy. In conclusion, the SBT is a simple test that can be used in clinical practice to detect clinically significant hypercapnia and monitor COPD patients before and after therapy.     

Asymmetric hydrogenation of alkenes with planar chiral 2-phosphino-1-aminoferrocene-iridium(I) complexes

The first highly enantioenriched and enantiopure planar chiral 2-phosphino-1-aminoferrocene ligands and their Ir(COD)BAr_F complexes are reported. The ligands display bidentate coordination behavior towards iridium, as indicated by trends in ³¹P and ¹H NMR spectra of the phosphine moieties and the α to nitrogen substituents of the amines. All of the new complexes showed good reactivity as catalysts in promoting asymmetric hydrogenation of several prochiral alkenes, with enantioselectivities up to 92%. Iridium complexes of dimethylaminoferrocene derivatives containing P-Ar groups [PPh₂ and P(o-tol)₂] gave the highest levels of asymmetric induction.     

Simultaneous PET–MRI in oncology: a solution looking for a problem?

With the recent development of integrated positron emission tomography–magnetic resonance imaging (PET–MRI) scanners, new possibilities for quantitative molecular imaging of cancer are realized. However, the practical advantages and potential clinical benefits of the ability to record PET and MRI data simultaneously must be balanced against the substantial costs and other requirements of such devices. In this review, we highlight several of the key areas where integrated PET–MRI measurements, obtained simultaneously, are anticipated to have a significant impact on clinical and/or research studies. These areas include the use of MR-based motion corrections and/or a priori anatomical information for improved reconstruction of PET data, improved arterial input function characterization for PET kinetic modeling, the use of dual-modality contrast agents, and patient comfort and practical convenience. For widespread acceptance, a compelling case could be made if the combination of quantitative MRI and specific PET biomarkers significantly improves our ability to assess tumor status and response to therapy, and some likely candidates are now emerging. We consider the relative advantages and disadvantages afforded by PET–MRI and summarize current opinions and evidence as to the likely value of PET–MRI in the management of cancer.     

Synthesis of novel furo-pyran derivatives via reaction between an isocyanide and alkylidene-substituted Meldrum’s acid

An unexpected four-component (3+1) reaction of an alkyl isocyanide with alkylidene-substituted Meldrum’s acid in CH₂Cl₂ at room temperature produces imino-furopyranones in good yields. The structures of the products are deduced from their IR, ¹H NMR, and ¹³C NMR spectra and by X-ray analysis. The products are structurally similar to 2H-furo[2,3-c]pyran-2-one natural products.     

A generalization of the schwarz alternating method to an arbitrary number of subdomains

Summary We give a generalization of the Schwarz alternating method to an arbitrary number of subdomains. As applications, we prove that the method converges for the main second-order boundary value problems, as well as for the system of linear elasticity.For the Dirichlet problems it is proved that the method converges geometrically and some numerical examples are given.     

Optimizing State Patrol Manpower Allocation

One of the most difficult tasks of state highway patrol administrators is allocation of manpower; i.e. determining the most effective level of operational manpower for patrol tasks. Typically, administrators resolve the allocation problem by relying on prior statistical data and by employing subjective analysis. In general, only limited systematic analyses have been applied to the problem. This paper presents an integer goal programming model for allocating highway patrolmen to road segments within a patrol region. The model is demonstrated via a case example of the Nebraska State Patrol. The results of the model are valuable to the patrol administrator for considering departmental goals and priority structure, in addition to available historical data, in the assignment of state patrol manpower.     

UV-DNA Damage in Mouse and Human Cells Induces the Expression of Tumor Necrosis Factor α

Ultraviolet light induces the expression of tumor necrosis factor α (TNFα) in many mammalian cells. We have examined the signal for this induction in a human DNA repair-deficient cell line carrying a transgene composed of the murine TNF regulatory sequences fused to the chloramphenicol acetyltransferase (CAT) structural gene. When compared by fluence, UVC was a more efficient inducer of CAT than was UVB, but they were equivalent inducers when compared by the frequency of cyclobutyl pyrimidine dimers produced by each source. Further, treatment of UV-irradiated cells with the prokaryotic DNA repair enzyme T4 endonuclease V in-creased the level of repair of dimers and concomitantly reduced CAT gene expression. Membrane-bound TNFα expression was increased by UV and reduced by repair of dimers. Finally, in the TNFcat transgene system, DNA damage directly to the cell with the transgene was required as cocultivation of unirradiated TNFcat cells with UV-irradiated cells did not increase CAT activity. These results show that DNA damage is a signal for the induction of TNFa gene expression in mouse and human cells.