Effect of storage on wall-bound phenolics in green asparagus   总被引：2，自引：0，他引：2  

Rodriguez-Arcos RC  Smith AC  Waldron KW 《Journal of agricultural and food chemistry》2002,50(11):3197-3203

The cell walls of green asparagus spears have been analyzed for their phenolic and carbohydrate composition as modified by postharvest storage. Esterified phenolic components were released by sequential alkaline hydrolysis and identified and quantified by diode array HPLC. Significant quantities of ferulic acid (FA) and its derivatives were found to increase at least 3-fold during storage, particularly in walls from the lower parts of the stem, where accompanying changes in sugar composition were also observed. In fresh asparagus, >60% of the total FA was in the form of diferulic acid, and this increased to approximately 70% after 3 days of storage. The main FA dehydrodimers were 8-8-, 8-O-4-, and 8-5-diferulates. These have been detected in other monocotyledonous and dicotyledonous plants, but as a smaller proportion of the total FA. The possible roles phenolic esters might have in relation to the mechanical, textural, and wound-response properties of asparagus spears are discussed.  相似文献   

UNCERTAINTY IN THE ESTIMATION OF CRITICAL LOADS: A PRACTICAL METHODOLOGY     

Zak  Susan K.  Beven  Keith  Reynolds  Brian 《Water, air, and soil pollution》1997,98(3-4):297-316

Critical loads of acid deposition for forest soils, ground and surface water resources are calculated utilising a variety of mathematical models. The estimation of the predictive uncertainty inherent in these models is important since the model predictions constitute the cornerstone of the development of emissions abatement policy decisions in Europe and the United Kingdom. The Generalised Likelihood Uncertainty Estimation (GLUE) approach is presented here as a tool for estimating the predictive uncertainty of PROFILE, a steady-state geochemical model that is widely applied within the critical loads community. GLUE is based on Monte Carlo simulation and explicitly recognises the possible equifinality of parameter sets. With this methodology it is possible to make an assessment of the likelihood of a parameter set being an acceptable simulator of a system when model predictions are compared to observed field data. The methodology is applied to a small catchment at Plynlimon, Mid-Wales. The results highlight that there is a large amount of predictive uncertainty associated with the model at the site: three of the six chosen field characteristics lie within the predicted distribution. The study also demonstrates that a wide range of parameter sets exist that give acceptable simulations of the site characteristics as well as a broad distribution of critical load values that are consistent with the site data. Additionally, a sensitivity analysis of model parameters is presented.  相似文献   

Biochemical activities in peat sterilized by gamma-irradiation     

Keith A. Brown 《Soil biology & biochemistry》1981,13(6):469-474

Peat is effectively sterilized by 4 Mrad of γ-irradiation and microbial sulphate-reducing activity is abolished by this dose. Enzymatic activities persist to a variable extent, but have higher inactivation coefficients than are usually encountered with soil enzymes. Inactivation coefficients (Mrad^?1) in surface peat, and in peat from 25–30 cm depth were as follows: β-d-glucosidase 0.144, 0.176: β-d-galactosidase 0.409, 0.458; $\text{β-N-}\text{acetyl-}\text{d}\text{-glucosaminidase}$ 0.201, 0.284; exo-l,4-β-d-xylosidase 0.268, 0.178: arylsulphatase 0.168, 0.174; 4-nitrophenylphosphatase 0.102, 0.118; “dehydrogenase” 0.094. 0.050; thiosulphate: cyanide sulphur transferase 0.079, 0.021. The greater radiosensitivity of the peat enzymes may be because of the absence of protection afforded by adsorption onto clay minerals, the nature of humic-colloid enzyme complex, or as a result of greater indirect damage caused by the products of radiolysis of water.  相似文献   

Nitrogen fixation by free-living heterotrophic bacteria in an oak forest: The effect of liming     

Keith Jones  David Bangs 《Soil biology & biochemistry》1985,17(5):705-709

Nitrogen-fixing heterotrophic bacteria, mainly Clostridium butyricum and, less frequently, Enterobacter agglomerons and Klebsiella pneumoniae, are found throughout the aerial and soil layers of an oak forest. However they are only active in nitrogen fixation in the soil. Soil slurry experiments show that the main factors limiting N₂ fixation in the forest are low temperature, low pH and shortage of C sources. Raising the pH of the soil with lime to pH 6, which is the optimum for N₂ fixation by C. butyricum in soil slurries, more than doubles the rate of N₂ fixation (as measured by in situ¹⁵N₂ methods) from 7.84 to 16.1 kg N ha^?1yr^?1. The N fixed by C. butyricum can rapidly be taken up by oak seedlings and translocated to the actively-growing leaves.  相似文献   

Reply     

Paul W. Shaffer  Richard P. Hooper  Keith N. Eshleman  M. Robbins Church 《Water, air, and soil pollution》1989,47(1-2):179-182

  相似文献   

Comparison of natural and roasted Turkish tombul hazelnut (Corylus avellana L.) volatiles and flavor by DHA/GC/MS and descriptive sensory analysis   总被引：1，自引：0，他引：1  

Alasalvar C  Shahidi F  Cadwallader KR 《Journal of agricultural and food chemistry》2003,51(17):5067-5072

  相似文献   

MAGNETIC RESONANCE IMAGING OF THE BRAIN OF NORMAL NEONATAL FOALS     

M. Keith  Chaffin  DVM  MS  Michael A.  Walker  DVM  Newell H.  Mcarthur  DVM  MS  PhD  Elias E.  Perris  DVM  Nora S.  Matthews  DVM 《Veterinary radiology & ultrasound》1997,38(2):102-111

Magnetic resonance imaging (MRI) was performed on gthe brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Interavenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic struictures of the brain and head. MRI of the bgrain is feasible for selected neonantal equine patients.  相似文献   

THE ORIGIN OF THE CYCADS     

Chamberlain CJ 《Science (New York, N.Y.)》1925,61(1569):73-77

  相似文献   

Effect of maturity of corn silage at harvest on the performance of feeder heifers     

C C Chamberlain  H A Fribourg  K M Barth  J H Felts  J M Anderson 《Journal of animal science》1971,33(1):161-166

  相似文献   

Effect of acetylsalicylic acid on vascular damage and myointimal proliferation in canine pulmonary arteries subjected to chronic injury by Dirofilaria immitis     

R G Schaub  J C Keith  C A Rawlings 《American journal of veterinary research》1983,44(3):449-454

The effect of aspirin (ASA) on pulmonary artery response to chronic injury induced by Dirofilaria immitis was assessed in the dog. Eight dogs were studied for 30 days after adult heartworms were transplanted into the pulmonary arteries. Four dogs were treated with ASA (325 mg/day given orally) starting 3 days before the transplantation was done. Evan's blue dye was used to locate areas of vascular damage. Vascular morphology was assessed by scanning electron microscopy and light microscopy. According to results of the morphologic studies, nontreated dogs had extensive endothelial damage and significant adhesion of leukocytes and blood platelets. Blood vessels of ASA-treated dogs had less endothelial damage. Platelet adhesion on areas of vascular damage was less than that observed in nontreated dogs. Myointimal proliferative lesions were observed in both nontreated and ASA-treated dogs. However, the lesions in nontreated dogs were larger (means 68 +/- 7 mm2) and more complex than those in ASA-treated dogs (means 20 +/- 1 mm2). The results indicated that aspirin may protect against development of myointimal proliferation resulting from chronic vascular injury. The mechanism of the ASA protection may result from a combination of antiplatelet and anti-inflammatory effects, as well as a direct protective effect on vascular endothelium.  相似文献