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1.
Although various antioxidants have been tested as therapeutics for endotoxemic subjects, the results of their efficacy are conflicting. Antioxidant biofactor (AOB) is a unique processed grain food that exhibits strong antioxidant activity (Minamiyama et al, J Nutr Sci Vitaminol, 40: 467-477, 1994). The present study was carried out to test the effect of AOB on hepatic injury in rats induced by lipopolysaccharide (LPS). Intravenous administration of LPS induced liver injury with a concomitant increase in hepatic generation of nitric oxide (NO) and 4-hydroxy-2-nonenal (HNE) modified proteins in the control group. The administration of AOB significantly inhibited the LPS-induced hepatic injury and generation of HNE-modified proteins and increased the survival rate of endotoxemic rats without affecting NO generation and plasma levels of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). AOB scavenged superoxide radicals without affecting NO production by LPS-stimulated macrophage cell line J 774.2 cells. AOB also inhibited lipid peroxidation induced by LPS in the cells. These results suggested that AOB might scavenge superoxide radicals and decrease toxic metabolites including HNE, thereby inhibiting liver injury in endotoxemic rats.  相似文献   

2.
By controlling Dy vapor deposition process, the amount of Dy that diffused into the magnet was increased gradually from 0.1 wt.% to 0.3 wt.%. Compared with the original status, the coercivity increment was not proportional to the Dy diffusion amount. Subsequent H_(cj) and Dy content gradient data showed that slope of the 0.3 wt.% sample gradient was bigger than that of 0.1 wt.% one, and the gaps between outer flakes and inner flakes enlarged with the increasement of Dy diffusion amount. Although Dy mostly enriched in triple-junction regions in electron-probe microscope analysis(EPMA) images, the following Auger depth graph showed that Dy content was as high as 3.0 at.% in 1.5 mm deep center. It proved that Dy tended to get into the main phase rather than stayed in the grain boundary during the diffusion process, and over-diffusion of Dy in the main phase was unhelpful for the coercivity enhancement.  相似文献   

3.
4.
晶粒尺寸对大塑性变形的两相合金超塑性的影响   总被引:1,自引:0,他引:1  
在室温下对共晶铅锡合金( Pb-62% Sn)进行了高压扭转变形( HPT)。采用不同时间的自退火制备不同晶粒尺寸的样品。最长的自退火时间为12天。通过研究这些样品在室温下不同的拉伸行为,从而获得了关于超塑性性能的结果。之后,本文通过将这些结果与等通道挤压( ECAP)获得的样品进行比较,不仅证明了所有样品都具有良好的超塑性,而且具有小晶粒尺寸的样品更容易在大应变速率的条件下获得超塑性。  相似文献   

5.
Riluzole is used clinically in patients with amyotrophic lateral sclerosis. As oxidative stress, in addition to excitotoxicity, may be a major mechanism of motoneuron degeneration in patients with amyotrophic lateral sclerosis, we examined whether riluzole protects against nonexcitotoxic oxidative injury. Probably reflecting its weak antiexcitotoxic effects, riluzole (1-30 microM) attenuated submaximal neuronal death induced by 24-h exposure to 30 microM kainate or NMDA, but not that by 100 microM NMDA, in cortical cultures. Riluzole also attenuated nonexcitotoxic oxidative injury induced by exposure to FeCl3 in the presence of MK-801 and CNQX. Consistent with its antioxidative effects, riluzole reduced Fe3+-induced lipid peroxidation, and inhibited cytosolic phospholipase A2. By contrast, riluzole did not attenuate neuronal apoptosis induced by staurosporine. Rather unexpectedly, 24-48-h exposure to 100-300 microM riluzole induced neuronal death accompanied by nuclear and DNA fragmentations, which was attenuated by caspase inhibitor carbobenzyloxy-Val-Ala-Asp-fluoromethyl ketone but not by protein synthesis inhibitor cycloheximide. The present study demonstrates that riluzole has direct antioxidative actions, perhaps in part by inhibiting phospholipase A2. However, in the same neurons, riluzole paradoxically induces neuronal apoptosis in a caspase-sensitive manner. Considering current clinical use of riluzole, further studies are warranted to investigate its potential cytolethal effects.  相似文献   

6.
The present work aimed to verify the digestibility of cooked whole food grain legumes. Samples of beans (Phaseolus vulgaris and Vigna sinensis), chickpeas (Cicer arietinum) and lentils (Lens culinaris) were used in the experiment. The interrelationship between the insoluble dietary fiber presented in the food grain legumes and the low protein digestibility was studied. The insoluble dietary fiber and the proteic nitrogen presented in the neutral detergent fiber (NDF) were determined. "In vivo" digestibility was performed in rats fed with diets containing cooked grain legumes, casein and protein free diet. The experiments were performed on rats over a period of 21 days. High excretion of nitrogen was observed by rats fed with cooked food grain legumes compared to casein diet. "In vitro" digestibility was performed by enzymatic hydrolysis with pepsin and trypsin. No significant differences was found between "in vivo" and "in vitro" digestibility. The heat treatment caused increased in the values of insoluble dietary fiber by the complexation of its components with protein and aminoacids. The results obtained showed the increased of the insoluble dietary fiber, in the cooked samples compared with raw samples. Significant values of protein nitrogen were found in the NDF, suggested that it was originated by complexation with proteins and aminoacids. This fact contributed to become proteic nitrogen nonavailability decreasing consequently the digestibility of the proteins.  相似文献   

7.
Mice were employed to study the sedative and anticonvulsive effects of Rhizoma Pinelliae processed by different methods. The results showed that of raw Rhizoma Pinelliae and its infusion were equally sedative and had anticonvulsive effect against the convulsion caused by cardiazol, but no anticonvulsion effect against that caused by strychnine.  相似文献   

8.
One of the most commonly overlooked parameters in grain boundary engineering initiatives is solute—interface interactions involving solute concentrations typically in the ppm range. In this work, experimental evidence is presented that demonstrates the significant effect of such interactions upon (1) the specific properties desired of “special” grain boundaries (e.g. resistance to corrosion) and (2) the resultant grain boundary character distribution following materials processing. Regarding the latter, it is shown how solute—grain boundary interactions impact significantly on the delicate balance of geometric (crystallographic), energetic, and kinetic influences. which ultimately dictates the grain boundary character distribution of engineered materials.  相似文献   

9.
Five primiparous Holstein cows (55 d in milk) that were fitted with ruminal and duodenal cannulas were used in a 4 x 5 incomplete Latin square to determine the effects of blends of steam-flaked and dry-rolled corn on site and extent of nutrient digestion and milk yield and composition. Diets were fed as total mixed rations and consisted of 45% forage and 55% concentrate; each diet contained 27% corn grain. Dietary treatments were composed of blends of dry-rolled and steam-flaked corn in ratios of 100:0, 67:33, 33:67, and 0:100. Intake of dry matter; digestibilities of dry matter, organic matter, acid detergent fiber, cellulose, neutral detergent fiber, fatty acids, and N; and microbial efficiency were unaffected by diet. Ruminal, postruminal, and total tract digestion of starch increased linearly, and starch passage to the duodenum decreased linearly, as the proportion of dry-rolled corn in the diet decreased. Ruminal propionate and valerate increased linearly, and acetate, butyrate, isovalerate, and the acetate to propionate ratio decreased linearly, as proportions of dry-rolled corn in the diet decreased; however, no changes in total volatile fatty acid concentrations in ruminal fluid were observed. Ruminal fluid pH was similar across diets. A decrease in dry-rolled corn decreased ruminal ammonia N and plasma urea N linearly. Milk yield and composition, as well as milk N fractions, were similar across diets. Although changes in fatty acid composition of milk fat were small, linear decreases in percentages of trans-C16:1 and cis-9- and cis-10-C18:1, as well as a linear increase in the percentage of C18:2 occurred as the proportion of dry-rolled corn in the diet decreased. An increased proportion of dry-rolled corn in the diet decreased digestion of starch in the rumen, and patterns of volatile fatty acid concentrations shifted accordingly. However, no effects on lactational parameters were observed.  相似文献   

10.
11.
Gravitational effects on grain coarsening during liquid-phase sintering   总被引:1,自引:0,他引:1  
Grain growth in liquid-phase sintering (LPS) is often treated as an extension of Ostwald ripening. However, the inherent grain contact at high solid contents leads to coalescence and other conflicts with most coarsening theories. Consequently, grain growth rates during LPS significantly deviate from the predictions of most coarsening theories. This study compares grain sizes of tungsten heavy alloys sintered on Earth and under microgravity conditions. The microgravity samples consistently produced a smaller grain size. A case is made for a gravity contribution to coarsening during LPS. Such a concept provides a rationalization for previously reported differences in sintered grain size with location in compacts sintered on Earth.  相似文献   

12.
OBJECTIVE: To determine the effects of food on methotrexate (MTX) absorption in patients receiving MTX for the treatment of rheumatoid arthritis (RA). METHODS: Standard pharmacokinetic variables were determined in patients with RA after their usual maintenance dose of MTX, under fasting conditions and after they ate a standard breakfast. RESULTS: No significant differences in area under the serum concentration versus time curve, maximal MTX concentration after dosing (Cmax), time to Cmax), bioavailability, urinary MTX, renal clearance of MTX, or creatinine clearance were observed between the 2 dosing conditions. CONCLUSION: We observed no significant effect of food on MTX absorption or bioavailability. Patients may consume MTX without regard to meals.  相似文献   

13.
The author investigated the antioxidant effect of irbesartan[2-butyl-3-({4-[2-(2H-1,2,3,4-tetrazol-5-yl)phenyl]phenyl}methyl)-1,3-diazaspiro[4.4]non-1-en-4-one],an angiotensin receptor biocker(ARB),on the oxidation of erythrocytes induced by 2,2-[azobis(2-amidinopropane)hydrochloride](AAPH)and H2O2.The value of half concentration(IC50)of irbesartan to scavenge radicals was measured by reacting it with 2,2-[azinobis(3-ethylbenzothiazoline-6-sulfonate)radical cation](ABTS+).Activities of the catalase(CAT),superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and the content of malondialdehyde(MDA)in liver tissue and blood serum of normal-rats were measured by means of spectrophotometry to study the antioxidation function of irbesartan.Results of experiments show that irbesartan can scavenge ABTS+ and superoxide radicals effectively as well as inhibit AAPH-,H2O2-induced hemolysis of erythrocytes,Irbesartan can also increase the activities of GSH-Px,SOD,CAT and decrease the content of MDA of normal rats.So irbesartan is a good antioxidant.  相似文献   

14.
In this study, the influence of the content of Al and Co in the diffusion source on the magnetic performance and microstructure of the diffused magnet was studied by grain boundary diffusion treatment with Pr70Al30–xCox (x = 0 at%, 10 at%, 15 at%, 20 at%, 30 at%) alloys. When the Co content in the diffusion source increases from 0 at% to 10 at%, the coercivity enhancement in the Pr70Al20Co10 diffused magnet is the highest, increased from 1.62 to 2.24 T, higher than 2.01 T of the Pr70Al30 diffused magnet. With further increase of Co content in the diffused source, the coercivity of the diffused magnet decreases gradually, the coercivity of Pr70Al15Co15, Pr70Al20Co10 and Pr70Co30 diffused magnet is 2.15, 1.99 and 1.81 T, respectively. Microstructural analysis shows that plenty of continuous grain boundary phases (CGBPs) can be formed in the Pr70Al20Co10 diffused magnet under the synergistic effect of Al and Co, which leads to the enhancement of magnetic isolation between more adjacent grains. However, the amount of CGBP in the diffused magnets gradually decreases with the further increase of Co content in the diffusion source.  相似文献   

15.
A ductile cast iron was continuously hot-and-warm-rolled or one-step-forged from a temperature in the austenite range (900 °C to 1100 °C) to a temperature below the A 1 temperature. Various amounts of reduction were used (from 60 to more than 90 pct). Tensile properties including tensile strength and total elongation were measured along the directions parallel and transverse to the rolling direction and along the direction transverse to the forging direction. The tensile ductility and strength both increase with a decrease in the amount of hot-and-warm working (HWW). Compared with the results obtained by other investigators, the present results showed higher strengths and ductilities over the same range of reduction in thickness. The improvement in properties is related to the lower temperature of the postprocessing heat treatment given in this study (600 °C) compared to other studies (900 °C). The low temperature of heat treatment leads to a structure of fine graphite in a matrix of ferrite and carbides, whereas the high temperature of heat treatment leads to coarse graphite in a matrix of carbide-free ferrite. The delay in failure from the presence of the small graphite constituent results in an increase in tensile ductility with an accompanying increase in tensile strength.  相似文献   

16.
Exposure to flour dust may induce chronic respiratory manifestations as well as acute ventilatory effects. We compared the prevalence of respiratory symptoms, ventilatory impairment, and variations in pulmonary function over the workshift in a group of mill workers exposed to wheat flour and in referent workers. One hundred and forty-two men exposed to flour in a mill and 37 referent workers were included in this study. Each subject completed a standardized questionnaire. Pulmonary function tests were performed before and after the workshift. The assessment of environmental exposure to flour showed high concentrations during some jobs with a high percentage of inhalable particles and a low concentration of respirable particles. The exposed workers had a significantly higher prevalence of usual cough and usual phlegm than the referents. The prevalence of asthma, based on the questionnaire, was similar. Before the workshift, the exposed workers had significantly lower mean lung function values for peak flow rate and forced expiratory flow rate at 75% of the vital capacity than the referents. After the workshift, all the lung function values showed a slight decrease, significant for forced vital capacity and forced expiratory volume during 1 s in both groups. Among the exposed workers, the asthmatic subjects had a significantly higher decrease across the shift than the nonasthmatic workers. This result is probably linked to bronchial hyperreactivity. Among nonasthmatic subjects, the decrease was larger in nonexposed workers than in exposed workers. A higher prevalence of respiratory symptoms and lower pulmonary function values were observed among mill workers by comparison with referents. Moreover, the data suggest that asthmatic status and the time of spirometric measurements need to be taken into account in epidemiological studies on exposure to airborne allergens. In addition, the study does not exclude a healthy worker effect with selection of dust-resistant subjects or better identification of asthmatic subjects among the workers exposed to an allergenic substance than among the nonexposed workers.  相似文献   

17.
18.
The grain boundary diffusion process(GBDP) of Tb can improve the coercivity of sintered Nd-Fe-B magnets.In this study,the effect of AI on the diffusion of Tb in the GBDP was investigated.The content of diffused Tb-Al was precisely controlled by adjusting the magnetron sputtering process.The Tb equivalent of Al was also studied.Results show that AI promotes the diffusion of Tb deeper into the magnet,reducing the thickness of the shell in the core-shell structure.This study is helpful for further ...  相似文献   

19.
《Acta Metallurgica》1980,28(10):1315-1332
We analyze the growth of cavities along grain interfaces by the combined processes of grain boundary diffusion and plastic dislocation creep in the adjoining grains. It is shown that the coupling between the processes can be expressed in terms of a parameter L, which has the dimensions of length and which is a function of material properties, temperature and applied stress; L decreases with increasing temperature and stress and has, e.g., values in the range of 0.25 to 25 μm for various pure metals when stressed to 10−3 × shear modulus at 0.5 Tm. The contribution of dislocation creep to the cavity growth rate is shown to be negligible when L is comparable to or larger than the cavity spacing, but significant interactions occur, leading to growth rates very much in excess of those predicted on the basis of boundary diffusion alone, when L is comparable to or smaller than the cavity size. The coupling occurs because extensive dislocation creep allows local accommodation of matter diffused into the grain boundary from the cavity walls.The cavity growth rate is analyzed by formulating a new variational principle that governs combined processes of grain boundary diffusion and non-linear viscous creep, and by implementing this principle through the finite-element method to obtain numerical solutions. Results for the cavity growth rate are presented for a wide range of ratios of L to cavity spacing, and of cavity radius to spacing. Also, results are presented for the total growth time of cavities from an initial size to final coalescence.  相似文献   

20.
《Acta Metallurgica》1987,35(2):307-315
Mean field theory of a rigid grain boundary segregation in binary mixture is developed on the basis of local equilibrium and geometrical considerations. The application of the Guggenheim adsorption isotherm equation to the problem of internal interfaces is proved to be valid for the case of regular substitutional solid solution. The segregation coefficient is found to be a function of a new interaction constant which yields the relative stability of an interface between a crystal made of pure solute and a crystal of pure solvent, with respect to the stability of grain boundaries in solvent and solute materials. Three typical structures are obtained when a local miscibility gap is formed and two other structures when the bulk tends to order. Segregation can stabilize new boundary structures which may involve changes in the intergranular translation, faceting, etc.  相似文献   

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