Investigation of a rapid infrared heating assisted mineralization of soybean matrices for trace element analysis.

A fast sample preparation procedure based on use of infrared (IR) assisted heating for mineralization of soybean derived samples has been developed for their subsequent multielement analysis by inductively coupled plasma optical emission spectrometry (ICP-OES) and flame atomic absorption spectrometry (FAAS). A cold finger was examined for refluxing of acid vapors to determine its impact on efficiency and economy of digestion. The optimized procedure, based on 1 g subsamples, 8 mL of HNO3 (65% w/w) and exposure of the mixture to a 500 W IR source for 5 min without refluxing, permitted accurate determination of all analytes in NIST SRM 1568b (rice flour). Detection limits using ICP-OES were (µg/kg) 97, 1.0, 39, 185, 0.47 and 1200 for Ca, Cu, Fe, K, Mn and P, respectively, and 18 for Zn by FAAS. The IR-assisted digestion approach provided a low cost, easy to use system having great potential for implementation in routine analysis of trace elements in soybean and similar matrices.

Scientists raise alarms about fast tracking of transoceanic canal through Nicaragua.

Seeking economic growth and job creation to tackle the nation's extreme poverty, the Nicaraguan government awarded a concession to build an interoceanic canal and associated projects to a recently formed Hong Kong based company with no track record or related expertise. This concession was awarded without a bidding process and in advance of any feasibility, socio-economic or environmental impact assessments; construction has begun without this information. The 278 km long interoceanic canal project may result in significant environmental and social impairments. Of particular concern are damage to Lake Cocibolca, a unique freshwater tropical lake and Central America's main freshwater reservoir; damage to regional biodiversity and ecosystems; and socio-economic impacts. Concerned about the possibly irreparable damage to the environment and to native communities, conservationists and the scientific community at large are urging the Nicaraguan government to devise and reveal an action plan to address and mitigate the possible negative repercussions of this interoceanic canal and associated projects. Critical research needs for preparation of a comprehensive benefit-cost analysis for this megaproject are presented.

Structural abnormalities in the substantia nigra and neighbouring nuclei in Tourette's syndrome.

Although midbrain nuclei (substantia nigra, ventral tegmental area, and periaqueductal grey) are considered candidate loci of pathology in Tourette's syndrome (TS), few imaging studies have examined midbrain structure. The objective of this study was to evaluate the presence of subtle structural abnormalities in the midbrain of patients with TS. High-field magnetic resonance imaging (MRI) (1.5- and 3-T) was used in 23 patients with TS and in 20 age- and sex-matched normal control subjects. Tics symptoms were rated using the Yale Global Tic Severity Scale and comorbid neuropsychiatric disorders were evaluated with standardised psychiatric rating scales. MRI scans revealed subtle structural abnormalities consistent with expanded perivascular spaces (EPVS) in the substantia nigra (compacta and reticulata) and neighbouring nuclei in 6 (26%) patients with TS, but in none of the normal control subjects (P = 0.045). Stereotyped movements were more frequent (P = 0.017) amongst TS patients with midbrain EPVS than in TS patients with normal MRI. Parkinsonism, posttraumatic stress disorder and autistic spectrum disorders exclusively occurred in TS patients with midbrain EPVS. There were no significant between-group differences in other comorbid neuropsychiatric disorders and in tics. Although EPVS are generally viewed as incidental findings, our results suggest that when EPVS are located in the midbrain they may be symptomatic. These abnormalities would reduce the actual number of neurons in specific midbrain nuclei (e.g., substantia nigra) and disrupt their connectivity with limbic, associative, and motor circuits.

Structures and thermodynamics of biphenyl dihydrodiol stereoisomers and their metabolites in the enzymatic degradation of arene xenobiotics.

A key step in the metabolic degradation of biphenyl xenobiotics is catechol formation upon dehydrogenation of cis- and trans-dihydrodiols in prokaryotic and eukaryotic pathways, respectively. Structure and thermodynamics of stereoisomers of cis-, trans-2,3-biphenyl-dihydrodiols (I) and their dehydrogenation products (hydroxyketones, II), as well as final catechol (2,3-biphenyldiol, III) are studied by means of ab initio MP2/6-311++G(2df,2p)//MP2/6-311G(d,p) calculations. Formation of stereoisomers I and II is exothermic and endergonic, whereas III is enthalpically and entropically driven. Dehydrogenations are endothermic (DeltaHR0 approximately 1.5-4 kcal mol(-1)) and exergonic (DeltaGR0 approximately -5 to -7.5 kcal mol(-1)) without noticeable differences between cis and trans pathways, although the same keto stereoisomer II-(2S) is found to be the more favored product from both cis- and trans-I. The final II --> III tautomerization is thermodynamically enhanced (DeltaHR0 approximately -27, DeltaGR0 approximately -28 kcal mol(-1)) but the process is shown to have a large activation energy if it had to occur via unimolecular path. Although this tautomerization is generally assumed to be a nonenzymatic process as it involves rearomatization of an oxygenated ring, proton transfer with an anionic intermediate might be a more probable process.