Warming open‐field plots using arrays of infrared heaters has proven feasible for conducting experiments to determine the likely effects of global warming on various ecosystems. To date, however, ...such experiments have been done for only a few degrees (≤3.5°C) of warming, yet climate projections, especially for high latitudes, indicate that future warming may be 10°C or more. Therefore, there is a need to conduct such experiments with more heating, which increases expense. To estimate energy requirements and costs for such temperature free‐air controlled enhancement (T‐FACE) experiments, improved theory was developed whereby: (i) the canopy temperature of an unheated plot is computed using the well‐accepted Monin–Obukhov similarity theory, with some constraints to calculate aerodynamic resistance; (ii) the desired amount of warming is added; and (iii) the energy balance is re‐solved to obtain the additional infrared radiation needed from the heaters to attain the desired temperature of the heated plots. Performance data are presented from T‐FACE experiments with 3‐m‐diameter plots conducted over six wheat (Triticum aestivum L.) crops and for 1‐wk periods over soybean Glycine max (L.) Merr. and northern mixed‐grass prairie. The T‐FACE system over wheat provided warming temperatures for day and night that were within 0.1°C of the desired setpoint differences. The measured or predicted energy requirements of the T‐FACE system for raising the wheat canopy temperatures averaged about 7.0 kWh m−2 d−1. Predictions of canopy temperatures and infrared heating requirements agreed with measurements most of the time for wheat, soybean, and prairie.
Goal-directed therapy has a secure place in perioperative care. Algorithms are based on Starling’s law of the heart, notwithstanding that this does not numerically define volume or heart performance ...variables. These have been developed based on a Guytonian view of the circulation and are implemented in a computerized decision support system (Navigator™). We studied the feasibility and performance of the graphical display of the system in an intervention and a control group of patients undergoing major abdominal surgery.
Patients were randomized to either graphically (intervention) or numerically (control) guided administration of therapy. Goals were set and treatments and concordance with guidance noted, where applicable. Anaesthesia was provided by one of three experienced anaesthetists well acquainted with Navigator™. The primary objective was to determine whether the use of graphical display decision support more efficiently enables the achievement of oxygen delivery targets. This was quantitated as percentage time in the target zone and averaged standardized distance from the target centre.
The mean percentage time in the target zone was 36.7% for control and 36.5% for intervention. The averaged standardized difference was 1.5 in control and 1.6 in intervention. There was no significant difference in fluid balances. There was a high level of concordance between decision support recommendation and anaesthetist action (84.3%).
In experienced hands, the addition of a graphical display for haemodynamic guidance resulted in a similar time in target and averaged standardized difference. The haemodynamic guidance system should be explored in a comparative study to anaesthesia management without guidance.
Experimentation with dynamics of soil carbon pools as affected by elevated CO2 can better define the ability of terrestrial ecosystems to sequester global carbon. In the present study, 6 N HCl ...hydrolysis and stable-carbon isotopic analysis (δ13C) were used to investigate labile and recalcitrant soil carbon pools and the translocation among these pools of sorghum residues isotopically labeled in the 1998-1999 Arizona Maricopa free air CO2 enrichment (FACE) experiment, in which elevated CO2 (FACE: 560 μmol mol-1) and ambient CO2 (Control: 360 μmol mol-1) interact with water-adequate (wet) and water-deficient (dry) treatments. We found that on average 53% of the final soil organic carbon (SOC) in the FACE plot was in the recalcitrant carbon pool and 47% in the labile pool, whereas in the Control plot 46% and 54% of carbon were in recalcitrant and labile pools, respectively, indicating that elevated CO2 transferred more SOC into the slow-decay carbon pool. Also, isotopic mixing models revealed that increased new sorghum residue input to the recalcitrant pool mainly accounts for this change, especially for the upper soil horizon (0-30 cm) where new carbon in recalcitrant soil pools of FACE wet and dry treatments was 1.7 and 2.8 times as large as that in respective Control recalcitrant pools. Similarly, old C in the recalcitrant pool under elevated CO2 was higher than that under ambient CO2, indicating that elevated CO2 reduces the decay of the old C in recalcitrant pool. Mean residence time (MRT) of bulk soil carbon at the depth of 0-30 cm was significantly longer in FACE plot than Control plot by the averages of 12 and 13 yr under the dry and wet conditions, respectively. The MRT was positively correlated to the ratio of carbon content in the recalcitrant pool to total SOC and negatively correlated to the ratio of carbon content in the labile pool to total SOC. Influence of water alone on the bulk SOC or the labile and recalcitrant pools was not significant. However, water stress interacting with CO2 enhanced the shift of the carbon from labile pool to recalcitrant pool. Our results imply that terrestrial agroecosystems may play a critical role in sequestrating atmospheric CO2 and mitigating harmful CO2 under future atmospheric conditions.
The Na+ or K+ cation−π interaction has been experimentally probed by using synthetic receptors that comprise diaza-18-crown-6 lariat ethers having ethylene sidearms attached to aromatic π-donors. The ...side chains are 2-(3-indolyl)ethyl (7), 2-(3-(1-methyl)indolyl)ethyl (8), 2-(3-(5-methoxy)indolyl)ethyl (9), 2-(4-hydroxyphenyl)ethyl (10), 2-phenylethyl (11), 2-pentafluorophenylethyl (12), and 2-(1-naphthyl)ethyl (13). Solid-state structures are reported for six examples of alkali metal complexes in which the cation is π-coordinated by phenyl, phenol, or indole. Indole-containing crown, 7, adopts a similar conformation when bound by NaI, KI, KSCN, or KPF6. In each case, the macroring and both arenes coordinate the cation; the counteranion is excluded from the solvation sphere. NMR measurements in acetone-d 6 solution confirm the observed solid-state conformations of unbound 7 and 7·NaI. In 7·Na+ and 7·K+, the pyrrolo, rather than benzo, subunit of indole is the π-donor for the alkali metal cation. Cation−π complexes were also observed for 10·KI and 11·KI. In these cases, the orientation of the cation on the aromatic ring is in accord with the binding site predicted by computational studies. In contrast to the phenyl case (11) the pentafluorophenyl group of 12 failed to coordinate K+. Solid-state structures are also reported for 7·NaPF6, 10·NaI, 11·NaI, 13·KI, 13·KPF6, and 9·NaI, in which cation−π complexation is not observed. Steric and electrostatic considerations in the π-complexation of alkali metal cations by these lariat ethers are thought to account for the observed complexation behavior or lack thereof.
The self-irradiation damage generated by alpha decay of Pu results in the formation of lattice defects and helium and uranium atoms. Over time, microstructural evolution as a result of the ...self-irradiation may influence the physical and mechanical properties of the material. Transmission electron microscopy investigations of Pu-Ga alloys ranging in age up to 42 years old, reveal the presence of nanometre-sized helium bubbles. The number density of bubbles and the average size have been determined for eight different age materials. The nucleation and growth of these bubbles have been modelled with rate equations.
A one-dimensional heat transfer method was used to determine the thermal conductivity for a range of coal ash and synthetic ash samples at elevated temperatures. The effect of parameters such as ...temperature, porosity, and sintering time were investigated. The thermal conductivity of the samples was generally observed to increase with increasing temperature. During heating of the samples, softening of minerals and sintering reactions resulted in changes in the physical structure of the ash, which then altered the observed thermal conductivity. The thermal conductivity of sintered ash samples was found to be higher than that of unsintered samples. The sintering temperature and sintering time were found to increase the observed thermal conductivity irreversibly. A decrease in sample porosity was also observed to increase the thermal conductivity. Chemical composition was found to have little effect on the thermal conductivity, apart from influencing the extent of sintering.
Predictions of the thermal conductivity of ash samples based on Rayleigh's model are also presented. The thermal conductivity of slag and particulate structures was modelled by considering spherical pores distributed in a continuous slag phase. A particulate layer structure was modelled by considering solid particles dispersed in a continuous gas phase. The Brailsford and Major model of random distribution for mixed phases gives results within 20% of the measured values for a partially sintered sample.
Bituminous chars with a strongly non-uniform porous structure have not been accounted for in existing pore models used to predict reactivity. A new approach has been developed to predict a particle ...structure parameter used in the random pore model. The reaction rate has been correlated with the carbon burn-off. Six bituminous coal chars were produced by pyrolysis in a pressurised drop tube furnace and their reaction rates were measured under various conditions using a pressurised thermogravimetric analyser. The char morphology and the porous structure of the char particles were obtained using image analysis. The porous structure of char particles was also characterised using mercury porosimetry. It is shown that after high-pressure pyrolysis, most of the char particles are of a high porosity, low surface area and a non-uniform porous structure with a large central void surrounded by a thin shell which will influence apparent char reactivity and ash formation. Image analysis also confirmed that the maceral composition of the coals and the pyrolysis pressure influence char morphology. A maximum reaction rate for each char was observed at a carbon conversion of 10–20
wt% during both char combustion and gasification. The particle structure parameters were predicted based on the measured porosity and surface area of macropores and micropores in the particle, and show reasonable agreement with those derived from experimental measurements. The predicted reaction rate agrees well with experimental measurements obtained under various conditions.
Uretero-ileal strictures (UES) following urinary diversion are therapeutically challenging. We compared the efficacy, safety and renal outcome following therapeutic endo-urological techniques (EUTs) ...and open surgical revision of the anastomosis (SRA) for UES.
We retrospectively analysed all EUTs and SRAs performed for UES in 2 hospitals between 1987 and 2015. Restenosis was defined as recurrent radiographically diagnosed hydronephrosis and re-intervention. Renal function (estimated glomerular filtration rate eGFR) decrease was correlated with the number of EUTs per patient.
Eighty-five UES were treated with 105 EUTs and 31 open revisions. Due to total obstruction, 28 (27%) EUTs were aborted. During a median follow-up of 33 months, restenosis occurred following 53 out of 77 (69%) completed EUTs and 4 out of 31 (13%) SRAs (p < 0.001 on univariable and multivariable analyses). No serious (Clavien ≥3b) EUT-related complications occurred vs. 5 (19%) related to SRA (p < 0.001). The number of finalised EUTs was independently associated with eGFR loss (β = 12.3 mL/min/1.73 m2 loss per EUT, p = 0.008), with a significant cutoff value of >1 EUTs. SRA did not affect renal function (β = 6.8 mL/min/1.73 m2 loss, p = 0.276).
Although EUTs are less invasive, they have an inferior efficacy to SRA. Our results suggest that a maximum of one EUT may be attempted without significantly compromising renal function.
Four coals containing iron mineral pyrite (FeS2) and siderite (FeCO3) were combusted in a laboratory drop tube furnace at temperatures of 1300, 1450, and 1600 °C under oxidizing and reducing ...conditions. Results for the behavior of pyrite mineral were in agreement with the established literature. The behavior of siderite mineral was determined and comparisons made. Coals containing pyrite minerals were determined to have potential to produce ash deposition and slagging at lower temperatures than coals containing siderite mineral. Reducing conditions were determined to lower the temperature at which ash deposition and slagging may occur for coals containing iron minerals compared to oxidizing conditions. With respect to ash deposition and slagging, it was determined that the iron levels in a coal are not definitive, but rather the iron mineral type (pyrite or siderite), mineral association (included or excluded), degree of association of included minerals, and the type of included alumino−silicate minerals have important roles.
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