Hydrogen Bonding Effect on the Oxygen Binding and Activation in Cobalt(III)-Peroxo Complexes.

Cobalt(III)peroxo complexes serve as model metal complexes mediating oxygen activation. We report a systematic study of the effect of hydrogen bonding on the O2 binding energy and the O-O bond activation within the cobalt(III)peroxo complexes. To this end, we prepared a series of tris(pyridin-2-ylmethyl)amine-based cobalt(III)peroxo complexes having either none, one, two, or three amino groups in the secondary coordination sphere. The hydrogen bonding between the amino group(s) and the peroxo ligand was investigated within the isolated complexes in the gas phase using helium tagging infrared photodissociation spectroscopy, energy-resolved collision-induced dissociation experiments, and density functional theory. The results show that the hydrogen bonding stabilizes the cobalt(III)peroxo core, but the effect is only 10-20 kJ mol-1. Introducing the first amino group to the secondary coordination sphere has the largest stabilization effect; more amino groups do not change the results significantly. The amino group can transfer a hydrogen atom to the peroxo ligands, which results in the O-O bond cleavage. This process is thermodynamically favored over the O2 elimination but entropically disfavored.

Enantioselective synthesis of chiral porphyrin macrocyclic hosts and kinetic enantiorecognition of viologen guests.

The construction of macromolecular hosts that are able to thread chiral guests in a stereoselective fashion is a big challenge. We herein describe the asymmetric synthesis of two enantiomeric C 2-symmetric porphyrin macrocyclic hosts that thread and bind different viologen guests. Time-resolved fluorescence studies show that these hosts display a factor 3 kinetic preference (ΔΔG ‡ on = 3 kJ mol-1) for threading onto the different enantiomers of a viologen guest appended with bulky chiral 1-phenylethoxy termini. A smaller kinetic selectivity (ΔΔG ‡ on = 1 kJ mol-1) is observed for viologens equipped with small chiral sec-butoxy termini. Kinetic selectivity is absent when the C 2-symmetric hosts are threaded onto chiral viologens appended with chiral tails in which the chiral moieties are located in the centers of the chains, rather than at the chain termini. The reason is that the termini of the latter guests, which engage in the initial stages of the threading process (entron effect), cannot discriminate because they are achiral, in contrast to the chiral termini of the former guests. Finally, our experiments show that the threading and de-threading rates are balanced in such a way that the observed binding constants are highly similar for all the investigated host-guest complexes, i.e. there is no thermodynamic selectivity.

Towards the development of a biobased economy in Europe and India.

India has emerged as a key player with a high potential to develop a biomass and biobased economy due to its large geographic size and the massive amounts of agricultural and non agricultural biomass produced. India has joined hands with Europe to synchronize its efforts to create and facilitate the development of a biobased economy in this country. This paper aims to examine common research and development actions between the European Union (EU) and India to facilitate the development of these biobased economies. As a base, a thorough study has been performed considering the biomass potential and current status of the bioeconomy in both the EU and India based on the distillation of a series of 80 potential recommendations. The recommendations were grouped into four major categories: (1) biomass production, (2) by-products/waste, (3) biorefineries and (4) policy, market, and value-added products. A questionnaire was designed and distributed to key stakeholders belonging to: academia, industry, and policymakers in both India and the EU. A total of 231 responses were received and analyzed, based on the key recommendations made for the essential research and development topics that are of prime importance to develop biobased economies in both the EU and India. The findings of this study suggest recognizing the value-added contributions made by biobased products such as: food, feed, valuable materials and chemicals in both regions. It is important to reduce the overall process costs and minimize the environmental impacts of such a biobased economy.

Analysis of by-product formation and sugar monomerization in sugarcane bagasse pretreated at pilot plant scale: differences between autohydrolysis, alkaline and acid pretreatment.

Sugarcane bagasse is an interesting feedstock for the biobased economy since a large fraction is polymerized sugars. Autohydrolysis, alkaline and acid pretreatment conditions combined with enzyme hydrolysis were used on lignocellulose rich bagasse to acquire monomeric. By-products found after pretreatment included acetic, glycolic and coumaric acid in concentrations up to 40, 21 and 2.5 g/kg dry weight bagasse respectively. Alkaline pretreated material contained up to 45 g/kg bagasse DW of sodium. Acid and autohydrolysis pretreatment results in a furan formation of 14 g/kg and 25 g/kg DW bagasse respectively. Enzyme monomerization efficiencies of pretreated solid material after 72 h were 81% for acid pretreatment, 77% for autohydrolysis and 57% for alkaline pretreatment. Solid material was washed with superheated water to decrease the amount of by-products. Washing decreased organic acid, phenol and furan concentrations in solid material by at least 60%, without a major sugar loss.

Improved starch recovery from potatoes by enzymes and reduced water holding of the residual fibres.

During the industrial extraction of starch from potatoes (Seresta), some starch remains within undisrupted potato cells in the fibrous side-stream. The aim of this study was to investigate if enzymatic degradation of cell wall polysaccharides (CWPs) can enhance starch recovery and lower the water holding capacity (WHC) of the "fibre" fraction. The use of a pectinase-rich preparation recovered 58% of the starch present in the "fibre" fraction. Also, the "fibre" fraction retained only 40% of the water present in the non-enzyme treated "fibre". This was caused by the degradation of pectins, in particular arabinogalactan side chains calculated as the sum of galactosyl and arabinosyl residues.

Effects of an educational video film in fatigued children and adolescents: a randomised controlled trial.

BACKGROUND: In many cases standard management for chronic fatigue syndrome (CFS) in children and adolescents is ineffective. OBJECTIVE: To evaluate the efficacy of a video film intervention in preventing the development of persistent fatigue and significant school absence in fatigued children and adolescents. DESIGN: Randomised controlled trial. PARTICIPANTS: 91 patients with fatigue; 50 were randomly assigned to receive the intervention (video film plus usual care) and 41 to usual care only. INTERVENTION: A video film on CFS and coping behaviour. MAIN OUTCOME MEASURES: Self-reported fatigue severity, physical activity, motivation, concentration and school absence. RESULTS: 79 patients had complete data at 12 months (42 in the video film and 37 in the usual care group). Mean fatigue severity and school absenteeism scores did not differ significantly, but in the intervention group the score for reduced motivation was higher (difference 2.9 (CI 0.1 to 5.7), p=0.038). 18% more patients in the intervention compared to the usual care group also had persistent fatigue with significant school absence. The odds of developing persistent fatigue and of missing >50% of school classes was 3.3 times higher in the intervention than in the usual care group (OR 3.3 (CI 1.0 to 11.3), p=0.046). CONCLUSION: This particular video film intervention plus usual care in children and adolescents with unexplained fatigue did not prevent an unfavourable outcome and possibly had an adverse effect in that it reduced motivation and increased the incidence of persistent fatigue with significant school absence. The use of this particular film is not recommended.

Adolescent chronic fatigue syndrome: a follow-up study.

OBJECTIVE: To describe the symptomatic and educational long-term outcomes, health care use, and risk factors of nonrecovery in adolescent chronic fatigue syndrome (CFS). DESIGN: Follow-up study. SETTING: Academic pediatric hospital. PARTICIPANTS: Sixty adolescents with CFS. INTERVENTIONS: Regular care. OUTCOME MEASURES: The Checklist Individual Strength, Child Health Questionnaire, and a general questionnaire regarding further symptoms, school attendance, work attendance, and treatment. RESULTS: Complete measurements were returned for 54 adolescents (90%). At initial assessment, their mean (SD) age was 16.0 (1.5) years and 20.4% were male. The mean follow-up duration was 2.2 years. At follow-up, the mean (SD) age was 18.2 (1.5) years; 28 adolescents (51.9%) had nearly complete improvement of symptoms but 26 (48.1%) did not experience improvement. Adolescents who attended school (n = 41) had missed an average of 33% of classes during the last month. The rest (n = 13) had worked an average of 38.7% of a full-time job during the last month. A total of 66.7% of subjects were treated by a physiotherapist, 38.9% were clinically treated in rehabilitation, 48.1% had received psychological support, and 53.7% had used alternative treatment. CONCLUSIONS: About half of the adolescents had recovered from CFS at follow-up. The other half was still severely fatigued and physically impaired. Health care use had been high, and school and work attendance were low. Older age at inclusion was a risk factor, and pain, poor mental health, self-esteem, and general health perception at outcome were associated with an unfavorable outcome. Future research should focus on customizing existing treatment and studying additional treatment options.

Carcinoid heart disease: the role of urinary 5-hydroxyindoleacetic acid excretion and plasma levels of atrial natriuretic peptide, transforming growth factor-beta and fibroblast growth factor.

BACKGROUND: Serotonin excretion plays a role in the development of carcinoid heart disease (CHD), but the exact pathogenesis is not known. In the current study, the authors evaluated 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA) excretion, as well as plasma levels of transforming growth factor-beta (TGF-beta), fibroblast growth factor (FGF), and atrial natriuretic peptide (ANP) in patients with and without CHD determined by ultrasound examination. METHODS: Urine and plasma samples were obtained for 37 patients and cardiac ultrasound was performed during follow-up in 1999 and 2000. Median 5-HIAA excretion was calculated for the period between diagnosis and ultrasound examination. CHD was defined as the thickening of the tricuspid valve with additional III-IV/IV tricuspid valve regurgitation. RESULTS: CHD was found in 9 of 37 patients (24%). No significant differences were found for age, gender, presence, and duration of liver metastases. All CHD patients had symptoms of the carcinoid syndrome compared with 71% of the non-CHD patients (P = 0.159). Median 5-HIAA excretion was significantly higher in the CHD group compared with the non-CHD group: 576 micromol/24 hours versus 233 micromol/24 hours (P = 0.02). No difference in TGF-beta and FGF plasma levels was observed between both groups (P = 0.139 and P = 0.985, respectively), nor was there a correlation with morphology of the tricuspid valve or degree of dilatation of the right atrium/ventricle. However, the CHD group had higher median ANP levels than the non-CHD group: 48 ng/L and 25 ng/L, respectively (P = 0.026). CONCLUSIONS: High levels of 5-HIAA excretion and plasma ANP were found to be associated with CHD. No significant relation with TGF-beta or FGF was been found.