排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
Effect of temperature and temperature fluctuation on thermophilic anaerobic digestion of cattle manure 总被引:9,自引:0,他引:9
The influence of temperature, 50 and 60 degrees C, at hydraulic retention times (HRTs) of 20 and 10 days, on the performance of anaerobic digestion of cow manure has been investigated in completely stirred tank reactors (CSTRs). Furthermore, the effect of both daily downward and daily upward temperature fluctuations has been studied. In the daily downward temperature fluctuation regime the temperatures of each reactor was reduced by 10 degrees C for 10 h while in the daily upward fluctuation regime the temperature of each reactor was increased 10 degrees C for 5 h. The results show that the methane production rate at 60 degrees C is lower than that at 50 degrees C at all experimental conditions of imposed HRT except when downward temperature fluctuations were applied at an HRT of 10 days. It also was found that the free ammonia concentration not only affects the acetate-utilising bacteria but also the hydrolysis and acidification process. The upward temperature fluctuation affects the maximum specific methanogenesis activity more severely as compared to imposed downward temperature fluctuations. The results clearly reveal the possibility of using available solar energy at daytime to heat up the reactor(s) without the need of heat storage during nights, especially at an operational temperature of 50 degrees C and at a 20 days HRT, and without the jeopardising of the overheating. 相似文献
2.
3.
Titia?de?MesEmail author Grietje?Zeeman Gatze?Lettinga 《Reviews in Environmental Science and Biotechnology》2005,4(4):275-311
Estrone (E1), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) discharged from sewage treatment plants (STPs) into surface
waters, are seen as a threat effecting aquatic life by its estrogenic character. Therefore, much research is conducted on
the fate and removal of these compounds. Since these compounds are present in influents and effluents in the ng/l range, methods
for detection deserve special attention. Most important processes that play a role in the removal of estrogens are: adsorption,
aerobic degradation, anaerobic degradation, anoxic biodegradation and photolytic degradation. Halflifes tend to vary and are
remarkably shorter when low initial concentrations are applied. In general anaerobic conditions result in longer halflifes
then aerobic conditions. EE2 shows far most persistence of the compounds, thereby also the estrogenic effect in vitro is about 2–3-fold higher compared to E2. The three compounds show a higher affinity to sorb to sludge compared to other tested
adsorption materials like sediment. Aerobic degradation is far the most efficient in removing these compounds, but adsorption
seems to play a significant role in retaining the estrogens inside full-scale STPs. Removal rates in full scale plants depend
on the HRT, SRT and loading rates, but lack of information on the exact dependency so far prevents an optimal design able
to fully eliminate estrogens from wastewater. 相似文献
4.
El-Mashad Hamed M. van Loon Wilko K.P. Zeeman Grietje Bot Gerard P.A. Lettinga Gatze 《Reviews in Environmental Science and Biotechnology》2003,2(1):53-66
Agricultural wastes represent an important source of bio-energy and valuable products. In Egypt, 18% of the agricultural wastes
is used directly as fertiliser. Another 30% is used as animal food. The remainder is burnt directly on the fields or is used
for heating in the small villages, using low efficiency burners. These wastes can be used more efficiently as a source of
energy and as organic fertiliser. The anaerobic bioconversion of these materials will result in a net energy production. The
utilisation of agricultural wastes for the production of energy and compost, combined with using solar energy will save fossil
fuel, improve health conditions and the general life quality in the villages.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Manintveld OC Te Lintel Hekkert M van den Bos EJ Suurenbroek GM Dekkers DH Verdouw PD Lamers JM Duncker DJ 《American journal of physiology. Heart and circulatory physiology》2007,292(3):H1551-H1560
Postconditioning (POC) is known as the phenomenon whereby brief intermittent ischemia applied at the onset of reperfusion following index ischemia limits myocardial infarct size. Whereas there is evidence that the algorithm of the POC stimulus is an important determinant of the protective efficacy, the importance of the duration of index ischemia on the outcome of the effects of POC has received little attention. Pentobarbital sodium-anesthetized Wistar rats were therefore subjected to index ischemia produced by coronary artery occlusions (CAO) of varying duration (15-120 min) followed by reperfusion, without or with postconditioning produced by three cycles of 30-s reperfusion and reocclusion (3POC30). 3POC30 limited infarct size produced by 45-min CAO (CAO45) from 45 +/- 3% to 31 +/- 5%, and CAO60 from 60 +/- 3% to 47 +/- 6% (both P < or = 0.05). In contrast, 3POC30 increased infarct size produced by CAO15 from 3 +/- 1% to 19 +/- 6% and CAO30 from 36 +/- 6 to 48 +/- 4% (both P < or = 0.05). This deleterious effect of 3POC30 was not stimulus sensitive because postconditioning with 3POC5 and 3POC15 after CAO30 also increased infarct size. The cardioprotection by 3POC30 after CAO60 was accompanied by an increased stimulation of Akt phosphorylation at 7 min of reperfusion and a 36% lower superoxide production, measured by dihydroethidium fluorescence, after 2 h of reperfusion. Consistent with these results, cardioprotection by 3POC30 was abolished by phosphatidylinositol-3-OH-kinase inhibition, as well as nitric oxide (NO) synthase inhibition. The deleterious effect of 3POC30 after CAO15 was accompanied by an increased superoxide production with no change in Akt phosphorylation and was not affected by NO synthase inhibition. In conclusion, the effect of cardiac POC depends critically on the duration of the index ischemia and can be either beneficial or detrimental. These paradoxical effects of POC may be related to the divergent effects on Akt phosphorylation and superoxide production. 相似文献
6.
Rianne M. Jongman Jan van Klarenbosch Grietje Molema Jan G. Zijlstra Adrianus J. de Vries Matijs van Meurs 《PloS one》2015,10(8)
Introduction
The pathophysiology of acute kidney injury (AKI) after cardiac surgery is not completely understood. Recent evidence suggests a pivotal role for the endothelium in AKI. In experimental models of AKI, the endothelial specific receptor Tie2 with its ligands Angiopoietin (Ang) 1 and Ang2 are deranged. This study investigates their status after cardiac surgery, and a possible relation between angiopoietins and AKI.Methods
From a cohort of 541 patients that underwent cardiac surgery, blood and urine was collected at 5 predefined time points. From this cohort we identified 21 patients who had at least 50% post-operative serum creatinine increase (AKI). We constructed a control group (n = 21) using propensity matching. Systemic levels of Ang1, Ang2, and sTie2 were measured in plasma and the AKI markers albumin, kidney injury molecule-1 (KIM-1) and N-acetyl-beta-D-glucosaminidase (NAG) were measured in the urine.Results
Ang2 plasma levels increased over time in AKI (from 4.2 to 11.6 ng/ml) and control patients (from 3.0 to 6.7 ng/ml). Ang2 levels increased 1.7-fold more in patients who developed AKI after cardiac surgery compared to matched control patients. Plasma levels of sTie2 decreased 1.6-fold and Ang1 decreased 3-fold over time in both groups, but were not different between AKI and controls (Ang1 P = 0.583 and sTie2 P = 0.679). Moreover, we found a positive correlation between plasma levels of Ang2 and urinary levels of NAG.Conclusions
The endothelial Ang/Tie2 system is in dysbalance in patients that develop AKI after cardiac surgery compared to matched control patients. 相似文献7.
Ganesh Ram R. Visweswaran Shima Gholizadeh Marcel H. J. Ruiters Grietje Molema Robbert J. Kok Jan. A. A. M. Kamps 《PloS one》2015,10(9)
Together with mesangial cells, glomerular endothelial cells and the basement membrane, podocytes constitute the glomerular filtration barrier (GFB) of the kidney. Podocytes play a pivotal role in the progression of various kidney-related diseases such as glomerular sclerosis and glomerulonephritis that finally lead to chronic end-stage renal disease. During podocytopathies, the slit-diaphragm connecting the adjacent podocytes are detached leading to severe loss of proteins in the urine. The pathophysiology of podocytopathies makes podocytes a potential and challenging target for nanomedicine development, though there is a lack of known molecular targets for cell selective drug delivery. To identify VCAM-1 as a cell-surface receptor that is suitable for binding and internalization of nanomedicine carrier systems by podocytes, we investigated its expression in the immortalized podocyte cell lines AB8/13 and MPC-5, and in primary podocytes. Gene and protein expression analyses revealed that VCAM-1 expression is increased by podocytes upon TNFα-activation for up to 24 h. This was paralleled by anti-VCAM-1 antibody binding to the TNFα-activated cells, which can be employed as a ligand to facilitate the uptake of nanocarriers under inflammatory conditions. Hence, we next explored the possibilities of using VCAM-1 as a cell-surface receptor to deliver the potent immunosuppressant rapamycin to TNFα-activated podocytes using the lipid-based nanocarrier system Saint-O-Somes. Anti-VCAM-1-rapamycin-SAINT-O-Somes more effectively inhibited the cell migration of AB8/13 cells than free rapamycin and non-targeted rapamycin-SAINT-O-Somes indicating the potential of VCAM-1 targeted drug delivery to podocytes. 相似文献
8.
Michiel Wagemakers Gesiena E van der Wal Rosa Cuberes Inés álvarez Eva Ma Andrés Jordi Buxens José M Vela Henk Moorlag Jan Jakob A Mooij Grietje Molema 《Translational oncology》2009,2(1):1-7
Cyclooxygenase 2 (COX-2) inhibitors have been shown to enhance tumor''s response to radiation in several animal models. The strong association of COX-2 and angiogenesis suggests that the tumor vasculature may be involved in this process. The current study investigated whether treatment with the COX-2 inhibitor E-6087 could influence response to local radiation in orthotopically growing murine gliomas and aimed to analyze the involvement of the tumor vasculature. GL261 glioma cells were injected into the cerebrum of C57bl/6 mice. From day 7 after tumor cell injection, mice were treated with COX-2 inhibitor at 50 mg/kg i.p. every third day. Radiation consisted of three fractions of 2 Gy given daily from day 9 to day 11. Mice were killed at day 21. The COX-2 inhibitor significantly enhanced the response to radiation, reducing mean volume to 32% of tumors treated with radiation only. The combination treatment neither increased apoptosis of tumor cells or stromal cells nor affected tumor microvascular density. In vitro, E-6087 and its active metabolite did not affect clonogenic survival of GL261 cells or human umbilical vein endothelial cell after radiation. In vivo, however, there was a nonsignificant increase in Angiopoietin (Ang)-1 and Tie-2 mRNA levels and a decrease of Ang-2 mRNA levels after combination treatment. These changes coincided with a significant increase in α-smooth muscle actin-positive pericyte coverage of tumor vessels. In conclusion, the antitumor effect of radiation on murine intracranial glioma growth is augmented by combining with COX-2 inhibition. Our findings suggest an involvement of the tumor vasculature in the observed effects. 相似文献
9.
We analyzed long-term winter survey data (1956–2007) for three endangered waterbirds endemic to the Hawaiian Islands, the
Hawaiian moorhen (Gallinula chloropus sandvicensis), Hawaiian coot (Fulica alai), and Hawaiian stilt (Himantopus mexicanus knudseni). Time series were analyzed by species–island combinations using generalized additive models, with alternative models compared
using Akaike information criterion (AIC). The best model included three smoothers, one for each species. Our analyses show
that all three of the endangered Hawaiian waterbirds have increased in population size over the past three decades. The Hawaiian
moorhen increase has been slower in more recent years than earlier in the survey period, but Hawaiian coot and stilt numbers
still exhibit steep increases. The patterns of population size increase also varied by island, although this effect was less
influential than that between species. In contrast to earlier studies, we found no evidence that rainfall affects counts of
the target species. Significant population increases were found on islands where most wetland protection has occurred (Oahu,
Kauai), while weak or no increases were found on islands with few wetlands or less protection (Hawaii, Maui). Increased protection
and management, especially on Maui where potential is greatest, would likely result in continued population gains, increasing
the potential for meeting population recovery goals. 相似文献
10.
Molema G 《Acta biochimica Polonica》2005,52(2):301-310
Tumor endothelial cells are actively involved in the neovascularization processes that accompany tumor growth. Their easy accessibility for systemically applied therapeutics makes them interesting targets for therapeutic intervention. Especially for drug targeting-based therapeutics that often consist of macromolecular moieties, the tumor endothelium is considered a much better target than the tumor cells located behind the vascular wall barrier. In this review, the general principles underlying the development and choices in the development of vascular drug-targeting strategies are discussed. An overview of target epitopes identified in the past two decades is followed by a summary of those strategies that directly or indirectly induced tumor blood flow blockade in vivo. The demonstrated therapeutic success in pre-clinical animal models in debulking large tumor masses and inhibiting tumor outgrowth warrant further development of these therapeutic approaches. Yet, more effort should be put in studies in which the efficacy of different effector activities aimed at the same target, of one effector activity aimed at different targets, and of multiple target strategies are be compared. Combining these data with proper inventories on the molecular basis of tumor endothelial heterogeneity in general will make possible the development of tumor vascular drug-targeting strategies towards clinical application. 相似文献