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111.
Integrated synthesis and extraction of short‐chain fatty acid esters by supercritical carbon dioxide
Marta Lubary Peter J. Jansens Joop H. ter Horst Gerard W. Hofland 《American Institute of Chemical Engineers》2010,56(4):1080-1089
We developed an efficient, integrated reaction‐extraction process for the production of short‐chain fatty acid ethyl esters (FAEE) from milk fat, using carbon dioxide as the only processing solvent. FAEE were synthesized using a short‐chain fatty acid selective lipase. The expansion of the liquid mixture of reactants by dense carbon dioxide enhanced the apparent lipase selectivity. In situ extraction of FAEE by a continuous flow of supercritical carbon dioxide proved to increase the lipase production rate. When the integrated process was operated with alternated periods of synthesis and product removal, the overall selectivity for short‐chain FAEE increased as well, as a result of the combination of the selectivities of lipase and extraction solvent. A two‐fold increase of the lipase productivity was achieved at these conditions, compared to a single batch reaction. The developed process enables the synthesis and isolation of high‐value fatty acid derivatives from a natural source such as milk fat. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
112.
To better understand the effects of increased N input and dry periods on soil nitrous oxide (N2O) emission, we examined a unique data-set of weather, soil microclimate, N input, and N2O emissions (using the eddy covariance method), measured at a fertilized grassland over the period 2003–2008. We found that
the N2O emission (11.5 kg N ha−1 year−1), the ratio of N2O emission to N input (3.4), and the duration of elevated N2O flux (57 days) in 2003 were about two times greater than those of the following years. 2003 had the highest annual N input
(343 kg N ha−1 year−1) which exceeded the agronomical requirements for Irish grasslands (up to 306 kg ha−1 year−1). In the summer of 2003, the site had a significantly higher soil temperature, lower WFPS and lowest rainfall of all years.
Large N2O emission events followed rainfall after a long dry period in the summer of 2003, attributed to dominant nitrification processes.
Furthermore, in the non summer periods, when temperature was lower and WFPS was higher and when there were prior N applications,
lower N2O emissions occurred and were attributed to dominant denitrification processes. Throughout the study period, the N input and
soil dryness related factors (duration of WFPS under 50%, summer average WFPS, and low rainfall) showed exponential relationships
with N2O emission and the ratio of N2O emission to N input. Based on these findings, we infer that the observed anomalously high N2O emission in 2003 may have been caused by the combined effects of excess N input above the plant uptake rate, elevated soil
temperature, and N2O flux bursts that followed the rewetting of dry soil after an unusually long dry summer period. These results suggest that
high N input above plant uptake rate and extended dry periods may cause abnormal increases in N2O emissions. 相似文献
113.
Gerard E. O’Connor Jeffrey Evans Scott Black Neil Fettell Beverley Orchard Ron Theo 《Nutrient Cycling in Agroecosystems》2010,86(2):269-286
Nitrate is known to accumulate under legume crops. The effects of legume crop, inoculation, row width, sowing rate, sowing
date, and intra-cropping with wheat, on the amount and soil distribution of mineral N, residual soil water, crop biomass and
crop N were studied at Wagga Wagga in south-east Australia. After removal of most of the above-ground plant material, the
treatment effects on the biomass, N content, grain yield and grain N of wheat, established in the following season, were also
measured. In a later experiment at Wagga, the recovery of 15N applied to the mid-row of lupin crops established at three row
widths was estimated at crop maturity. At Condobolin, row width effects on the soil distribution of mineral N, biomass, N
accumulation and N fixation of crop legumes and cereals, were determined. At physiological maturity, at Wagga Wagga, very
little nitrate was left beneath cereals. Significantly more was left under legume crops, mostly below 30 cm of soil depth,
and it was distributed differently depending on crop, inoculation, and sampling location. More nitrate was left under pea
and faba than under lupin, and in response to inoculation. Mixing wheat with narrow-leaf lupin did not prevent nitrate accumulation
in soil. For most of the legumes more nitrate was left in the mid-row than in the in-row; and more nitrate was left at the
mid-row of lupin crops sown with wider rows. The additional nitrate left with wider rows increased the growth, N content,
grain yield and protein of wheat established in the following season. 15N labelled nitrate applied mid-row was used less effectively
by lupin as row width increased, in a dry season. At Condobolin, lupin established with wide rows used less soil nitrate than
with narrower rows but maintained crop N by increased N fixation. In contrast, field pea maintained N demand by increasing
nitrate uptake at intermediate row spacing. The study shows that the amount of nitrate accumulated in soil during legume cropping
is susceptible to agronomic management, particularly crop selection, row width and inoculation; and that variation in the
amount of this nitrate may carry forward to impact wheat production in the follow-on season. 相似文献
114.
Gerard M. Carroll Susie M. Miller Monte L. Helm 《Inorganic chemistry communications》2010,13(4):534-536
The preparation of the novel (cis-P,P′-diphenyl-1,4-diphospha-cyclohexane)molybdenum(0)tetracarbonyl complex is described. The spectral data and X-ray structure of the title complex are reported. The results of the crystallographic work show a distorted octahedral complex around the metal center, the first of its kind reported for the P,P′-diphenyl-1,4-diphospha-cyclohexane ligand. 相似文献
115.
Aminou Mohamadou Gerard A. van Albada Ilpo Mutikainen Urho Turpeinen Jan Reedijk 《Inorganic chemistry communications》2010,13(10):1221-1224
A novel hexagonal-based honeycomb compound with overall formula {[KCr(C2O4)3][Cu(pypn)(H2O)](H2O)4} is reported in which pypn is with the tetradentate ligand (N,N′-bis(2-pyridylmethyl)-1,3-propanediamine). The [KCr(C2O4)3]2? moiety forms a hexagonal honeycomb structure, while the five-coordinated [Cu(pypn)(H2O)]2+ moiety is located in between the layers, partly filling the holes in the cavities. The synthesis, X-ray crystal structure and some spectroscopic properties are presented. The coordination of Cr(III) is octahedral, with a CrO6 chromophore, and the K+ ion is in a KO6 environment (K–O distances vary from 2.36 to 2.48 ?). The [KCr(C2O4)3]2? layers have the K+ ions in a Λ conformation, while the Cr(III) ions in the Δ conformation. The geometry around the Cu(II) is five-coordinated with four nitrogens from the chelating pypn ligand in a plane and the apical position being occupied by the oxygen atom of the coordinating water molecule. The packing of the cationic and the anionic layers appears to be of special interest. 相似文献
116.
A comparison of SWAT, HSPF and SHETRAN/GOPC for modelling phosphorus export from three catchments in Ireland 总被引:4,自引:0,他引:4
Recent extensive water quality surveys in Ireland revealed that diffuse phosphorus (P) pollution originating from agricultural land and transported by runoff and subsurface flows is the primary cause of the deterioration of surface water quality. P transport from land to water can be described by mathematical models that vary in modelling approach, complexity and scale (plot, field and catchment). Here, three mathematical models (soil water and analysis tools (SWAT), hydrological simulation program-FORTRAN (HSPF) and système hydrologique Européen TRANsport (SHETRAN)/grid oriented phosphorus component (GOPC)) of diffuse P pollution have been tested in three Irish catchments to explore their suitability in Irish conditions for future use in implementing the European Water Framework Directive. After calibrating the models, their daily flows and total phosphorus (TP) exports are compared and assessed. The HSPF model was the best at simulating the mean daily discharge while SWAT gave the best calibration results for daily TP loads. Annual TP exports for the three models and for two empirical models were compared with measured data. No single model is consistently better in estimating the annual TP export for all three catchments. 相似文献
117.
Gerard M O'Brien Christopher C Wheatley Carlos Iglesias Nigel H Poulter 《Journal of the science of food and agriculture》1994,65(4):391-399
Two rapid semi-quantitative assays for total cyanogens in cassava were evaluated. These were the well-known rapid picrate paper test, and a recently proposed rapid paper test involving the reagent tetra base (TB, 4,4′- methylenebis-(N, N-dimethylaniline)). A precise colorimetric assay was used as a control in the evaluative work. After primary evaluation, both assay methods underwent some modification regarding the interpretation of sample scores. As a result, the reliability of the picrate assay was greatly improved. The TB assay was modified in the interests of safety. Evaluation of this assay over a range of temperatures between 20 and 35°C showed no significant temperature effects upon performance when the new scoring interpretation system was used. The level of endogenous linamarase activity in the sample was found to be an influential factor in rapid assay performance. In a series of comparative trials in three distinct ecosystems, the newly modified picrate assay produced correct results in 68% of cases. This compared with 66% of results correct in the TB assay. It was observed that the TB assay performed more reliably with low cyanogen samples, whilst the picrate assay was more reliable with intermediate cyanogen samples. 相似文献
118.
Summary The IIW method is shown to be one of the most precise and that it may be programmed to advantage. 相似文献
119.
Stewart Jonathan W.; Quitkin Frederic M.; McGrath Patrick J.; Bruder Gerard E. 《Canadian Metallurgical Quarterly》1999,108(4):707
A previous study showed that depressed patients who improved with tricyclic antidepressant medication had dichotic complex tones test results suggesting right-hemisphere dysfunction relative to nonresponders and controls (G. E. Bruder et al., 1990). A new sample of 68 depressed patients completed dichotic consonant-vowel (CV) and complex tones (CT) tests and then were treated with imipramine or placebo. A significant Ear?×?Test?×?Treatment?×?Response interaction was accounted for by significantly poorer left-ear accuracy for CVs among imipramine responders compared with nonresponders, placebo responders, and controls. CV left-ear accuracy was also significantly greater among placebo responders than placebo nonresponders; and controls. The results only partially replicate the prior study in that evidence of right-hemisphere dysfunction in tricyclic responders was seen for the CV test but not the CT test. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
120.
Yong Xu Chuan Liu William Scheideler Peter Darmawan Songlin Li Francis Balestra Gerard Ghibaudo Kazuhito Tsukagoshi 《Organic Electronics》2013,14(7):1797-1804
We report on a study seeking an optimized contact configuration for organic transistors that minimizes contact effects but maintains smallest contact size. We begin with the bulk access resistance in staggered transistors which results from the charge transport through the organic semiconductor film. Bulk access resistance is an intrinsic contributor to the contact resistance which has been little understood due to lack of a reliable study tool. In this work, we utilize the inner transported power inside the semiconductor film as a medium to investigate the contact resistance and the relevant contact effects. We examine the influences of the organic film thickness (tSC), the channel length (L), the underlying charge transport and various organic semiconductor materials with variable carrier mobility. A roughly optimal contact length (LC) of LC0 ≈ 6tSC is obtained. The results reveal that besides the device architecture the underlying charge transport should be also taken into account in designing organic transistors for practical application. 相似文献