First-principles thermodynamic screening approach to photo-catalytic water splitting with co-catalysts

We adapt the computational hydrogen electrode approach to explicitly account for photo-generated charges and use it to computationally screen for viable catalyst/co-catalyst combinations for photo-catalytic water splitting. The hole energy necessary to thermodynamically drive the reaction is employed as descriptor for the screening process. Using this protocol and hybrid-level density-functional theory we show that water oxidation on bare TiO2 surfaces is thermodynamically more complex than previously thought. This motivates a screening for suitable co-catalysts for this half-reaction, which we carry out for Au particles down to the non-scalable size regime. We find that almost all small Au clusters studied are better suited for water photo-oxidation than an extended Au(111) surface or bare TiO2 facets.Comment: 5 pages, 3 figure

Oxidation of allylic and benzylic alcohols to aldehydes and carboxylic acids

An oxidation of allylic and benzylic alcohols to the corresponding carboxylic acids is effected by merging a Cu-catalyzed oxidation using O2 as a terminal oxidant with a subsequent chlorite oxidation (Lindgren oxidation). The protocol was optimized to obtain pure products without chromatography or crystallization. Interception at the aldehyde stage allowed for Z/E-isomerization, thus rendering the oxidation stereoconvergent with respect to the configuration of the starting material

Adaptation to an MCFA-rich diet : effect on gastric tolerance, the capacity for MCFA oxidation, and performance while ingesting exogenous carbohydrate and structured oils during endurance exercise : a thesis presented in partial fulfilment of the requirements for the degree of Master of Sport Science at Massey University

Introduction: Elevating the availability of fatty-acids to the muscle can potentially benefit endurance exercise performance by reducing intramuscular-glycogen utilisation. Digestion of triglycerides containing long-chain fatty acids (LCFAs) is slow, and fatty acids must pass through the carnitine palmityl transferase (CPT) transport system to enter the mitochondria, which potentially limits fat oxidation during prolonged-heavy exercise. Conversely, medium-chain triglycerides (MCTs) are rapidly digested and their constituent fatty acids (MCFAs) by-pass the CPT transport system. Ingestion of MCFAs may therefore supply mitochondrial acetyl-CoA, potentially reducing the requirement for glycolytic flux during exercise. However, studies comparing carbohydrate (CHO) with CHO-containing MCFA-rich exercise supplements have revealed inconsistent results, probably because of the variation in gastrointestinal (GI) distress suffered by participants associated with MCT ingestion. Purpose: To investigate whether 2-weeks of dietary adaptation to MCFA-rich supplements reduces the severity of gastrointestinal (Gl) distress, or increases the rate of MCFA oxidation during endurance exercise. A decrease in ratings of GI distress, or an increase in MCFA oxidation was anticipated to lead to performance benefits. Method: Nine well-trained male endurance cyclists participated in a double-blind, pseudo-randomised. triple-crossover protocol. Participants were 37 ± 7.26 years, 81.36 ± 7.67 kg. training at least 8-10 h per week and riding competitively. Mean VO2 max and peak power output (PPO) were 4.84 ± 0.46 L-min-1 and 357.33 ± 20.55 W respectively. The effects of a 2-week MCFA-rich diet +13 C-enriched MCFA+CHO exercise supplement (MC-MC) on GI distress, MCFA-oxidation rate and sprint performance variables were compared against a 2-week LCFA-rich diet with either: (a) a13 C-enriched MCFA+CHO exercise supplement (LC-MC), or (b) a CMO-only supplement (LC-CHO). Dietary and exercise MCFA-rich supplements were consumed in the form of randomised-structured triacylglycerols made with a 3:1 molar ratio of MC- and LCFAs randomly esterified to glycerol backbones. Participants followed a controlled training regime whilst on the diets. The performance test consisted of a 3-h ride at 50% PPO followed by 10 maximal sprints. At rest and every 20-min throughout the ride, participant ratings of GI and exertion sensations were recorded, followed by external respiratory-gas analysis, collection of a breath sample for breathl3 C-enrichment analysis, a venous blood sample and ingestion of a supplement. Similarly, after sprints 1, 4, 7 and 10 participants recorded their GI ratings followed by a blood sample. Results: Peak MCFA-oxidation rates were 0.38 g-min-1(95% Cl 0.31-0.47) and 0.43 g-min-1(0.30-0.61, p-value = 0.21) in the MC-MC and LC-MC conditions respectively, but there was no evidence for CHO sparing following MCFA adaptation. Participant ratings of GI distress decreased slightly during exercise with 2-weeks of a diet high in MCFAs relative to LCFAs. Ratings of reflux, bloatedness, nausea, and urge to vomit were, respectively, 1.34 (0.88-3.14), 1.03 (0.74-2.27), 0.81 (0.62-1.69) and 0.93 (0.64-245) scale units lower in the MC-MC condition relative to LC-MC. The attenuation in GI distress corresponded with a tendency toward increased sprint mean power, which was 3.4% (± 5.9%, 0.25) higher in the MC-MC condition relative to LC-MC. However, sprint mean power was still lower in both the MC-MC (6.8% ± 2.8%, <0.0001) and LC-MC (10.4% ± 5.5%, 0.0004) conditions relative to LC-CHO. Mechanism covariate analysis illustrated a negative effect of the GI distress marker nausea on sprint performance. For every 1 unit increase in nausea for the MC-MC and LC- MC conditions, sprint power decreased by 6 W (± 3.8,0.004) relative to LC-CHO. Conclusion: No clear metabolic adaptation was evident with high dietary MCFA relative to LCFA. In addition, MCFA-rich exercise supplements caused a decrement in performance relative to CHO ingestion in both MC-MC and LC-MC conditions, suggesting that light- moderate GI distress still causes substantial performance detriments. There was little evidence to support the ingestion of randomised structured triglycerides high in MCFA with the intention of enhancing endurance performance

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

The present work addresses the development of an eco-friendly and cost-efficient protocol for the oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones by mechanical processing under air. Ball milling was shown to promote the quantitative conversion of a broad set of alcohols into carbonyl compounds with no trace of an over-oxidation to carboxylic acids. The mechanochemical reaction exhibited higher yields and rates than the classical, homogeneous, TEMPO-based oxidation

Blood lactate clearance after maximal exercise depends on active recovery intensity

AIM: High-intensity exercise is time-limited by onset of fatigue, marked by accumulation of blood lactate. This is accentuated at maximal, all-out exercise that rapidly accumulates high blood lactate. The optimal active recovery intensity for clearing lactate after such maximal, all-out exercise remains unknown. Thus, we studied the intensity-dependence of lactate clearance during active recovery after maximal exercise.&lt;p&gt;&lt;/p&gt; METHODS: We constructed a standardized maximal, all-out treadmill exercise protocol that predictably lead to voluntary exhaustion and blood lactate concentration &#62;10 mM. Next, subjects ran series of all-out bouts that increased blood lactate concentration to 11.5±0.2 mM, followed by recovery exercises ranging 0% (passive)-100% of the lactate threshold.&lt;p&gt;&lt;/p&gt; RESULTS: Repeated measurements showed faster lactate clearance during active versus passive recovery (P&#60;0.01), and that active recovery at 60-100% of lactate threshold was more efficient for lactate clearance than lower intensity recovery (P&#60;0.05). Active recovery at 80% of lactate threshold had the highest rate of and shortest time constant for lactate clearance (P&#60;0.05), whereas the response during the other intensities was graded (100%=60%&#62;40%&#62;passive recovery, P&#60;0.05).&lt;p&gt;&lt;/p&gt; CONCLUSION: Active recovery after maximal all-out exercise clears accumulated blood lactate faster than passive recovery in an intensity-dependent manner, with maximum clearance occurring at active recovery of 80% of lactate threshold

Geochemical reactivity of subsurface sediments as potential buffer to anthropogenic inputs: a strategy for regional characterization in the Netherlands

Geochemical reactivity of subsurface sediments as potential buffer to anthropogenic inputs: a strategy for regional characterization in the Netherland

Effects of processing on the stability of molybdenum oxide ultra-thin films

The effects of wet chemical processing conventionally employed in device fabrication standards are systematically studied on molybdenum oxide (MoOx) ultra-thin films. We have combined x-ray photoelectron spectroscopy (XPS), angle resolved XPS and x-ray reflectivity techniques to provide deep insights into the changes in composition, structure and electronic states upon treatment of films with different initial stoichiometry prepared by reactive sputtering. Our results show significant reduction effects associated with the development of gap states in MoOx, as well as changes in the composition, density and structure of the films, systematically correlated with the initial oxidation state of Mo.Comment: 16 pages, 5 figures, Appendix include

EU Peatlands: Current Carbon Stocks and Trace Gas Fluxes

Peatlands in Europe has formed a significant sink for atmospheric CO2 since the last glacial maximum. Currently they are estimated to hold ca. 42 Gt carbon in the form of peat and are therefore a considerable component in the European carbon budget. Due to the generally wet soil conditions in peatlands they are also significant emitters of the strong greenhouse gas (GHG) methane (CH4) and in some cases also of nitrous oxide (N2O). The EU funded CarboEurope-GHG Concerted Action attempts to develop a reliable and complete greenhouse gas budget for Europe and this report aims to provide a review and synthesis of the available information about GHG exchanges in European peatlands and their underlying processes. A best estimate for all the European countries shows that some are currently sinks for atmospheric CO2 while others are sources. In contrast, for CH4 and N2O, only the sources are relevant. Whilst some countries are CO2 sinks, all countries are net GHG emitters from peatlands. The results presented, however, carry large uncertainties, which cannot be adequately quantified yet. One outstanding uncertainty is the distribution of land use types, particular in Russia, the largest European peat nation. The synthesis of GHG exchange, nevertheless, indicates some interesting features. Russia hosts an estimated 41% of European peatlands and contributes most to all GHG exchanges (CO2: 25%, CH4: 52%, N2O: 26%, Total: 37%). Germany is the second-largest emitter (12% of European total) although it contains only 3.2% of European peatlands. The reason is the use of most of the peatland area for intensive cropland and grassland. The largest CO2 emitters are countries with large agricultural peatland areas (Russia, Germany, Belarus, Poland), the largest N2O emitters are those with large agricultural fen areas (Russia, Germany, Finland). In contrast, the largest CH4 emitters are concentrated in regions with large areas of intact mires, namely Russia and Scandinavia. High average emission densities above 3.5 t C-equiv. ha-1 are found in the Southeast Mediterranean, Germany and the Netherlands where agricultural use of peatlands is intense. Low average emission densities below 0.3 t C-equiv. ha-1 occur where mires and peatland forests dominate, e.g. Finland and the UK. This report concludes by pointing at key gaps in our knowledge about peatland carbon stocks and GHG exchanges which include insufficient basic information on areal distribution of peatlands, measurements of peat depth and also a lack of flux datasets providing full annual budgets of GHG exchanges