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1.
β-glucanase was purified from a solid-state culture ofTrichoderma reesei on wheat bran in three steps which comprised ammonium sulfate precipitation, Sephadex G-100 chromatography, and DEAE-Sephadex A-50 chromatography. The molecular mass was determined to be 35.21 kilodaltons by sodium dodecyl sulfate-12.5% polyacrylamide gel electrophoresis. The β-glucanase at low pHs was more stable than that at high pHs, and optimum pH was 5.0. The optimum temperature was 60°C, and β-glucanase was relatively stable at below 40°C for 60 min. TheK m of the enzyme on β-glucan was 10.86 mg/ml, and theV max on β-glucan was 14286 μmol of glucose equivalents per mg of the pure enzyme per min. The β-glucanase activity was significantly inhibited by Fe3+ ions, and was reduced in the presence of Cu2+ ions, Mn2+ ions and Mg2+ ions at 5 mmol/L and 10 mmol/L, respectively. The β-glucanase activity was stimulated by Co2+ ions, Ca2+ ions, Zn2+ ions, and Fe2+ ions at 1 mmol/L and 5 mmol/L, respectively. Project supported by Foundation for University Key Teacher of the State Ministry of Education, the National Natural Science Foundation of China (No. 30000118) and Zhejiang Provincial Natural Science Foundation of China (No. 399409).  相似文献   

2.
This paper discusses stress intensity factor (SIF) calculations for surface cracks in round bars subjected to combined torsion and bending loadings. Different crack aspect ratios, a/b, ranging from 0.0 to 1.2 and relative crack depths, a/D, ranging from 0.1 to 0.6 were considered. Since the loading was non-symmetrical for torsion loadings, a whole finite element model was constructed. Then, the individual and combined bending and torsion loadings were remotely applied to the model. The equivalent SIF method, F*EQ, was then used explicitly to combine the individual SIFs from the bending and torsion loadings. A comparison was then carried out with the combined SIF, F*FE, obtained using the finite element analysis (FEA) under similar loadings. It was found that the equivalent SIF method successfully predicted the combined SIF for Mode I. However, discrepancies between the results determined from the different approaches occurred when F III was involved. It was also noted that the predicted F*FE using FEA was higher than the F*EQ predicted through the equivalent SIF method due to the difference in crack face interactions.  相似文献   

3.
The use of a biotrickling filter was investigated for a pilot field-scale elimination of NH3 gas and other odorous gases from a composting plant in Tongzhou District, Beijing. The inlet gas flow rate was 3500 m3/h and NH3 concentration fluctuated between 2.76–27.84 mg/m3, while the average outlet concentration was 1.06 mg/m3 with an average of 94.9% removal. Critical volumetric loading (removal efficiency=100%) was 11.22 g-N/(m3·h). The odor concentration removal was 86.7%. NH3 removal efficiency decreased as the free ammonia (FA) in the trickling liquid increased. The pressure drop was maintained at about 50 Pa/m and was never more than 55 Pa/m. During the experiment, there was neither backflushing required nor any indication of clogging. Overall, the biotrickling filter was highly efficient and cost-effective for the simultaneous biodegradation of NH3 and other odorous gases from composting, suggesting the possibility of treating odorous gases at the industrial level.  相似文献   

4.
The evolution of the surface oxide film along the depth direction of typical aluminum alloy under medium-temperature brazing was investigated by means of X-ray photoelectron spectroscopy （XPS）. For the alloy with Mg content below 2.0wt%, whether under cold rolling condition or during medium-temperature brazing process, the en-richment of Mg element on the surface was not detected and the oxide film was pure Al2O3. However, the oxide film grew obviously during medium-temperature brazing process, and the thickness was about 80 nm. For the alloy with Mg content above 2.0wt%, under cold rolling condition, the original surface oxide film was pure Al2O3. However, the Mg element was significantly enriched on the outermost surface during medium-temperature brazing process, and MgO-based oxide film mixed with small amount of MgAl2O4 was formed with a thickness of about 130 nm. The alloy-ing elements of Mn and Si were not enriched on the surface neither under cold rolling condition nor during medium-temperature brazing process for all the selected aluminum alloy, and the surface oxide film was similar to that of pure aluminum, which was almost entire Al2O3.  相似文献   

5.
Pigeons were trained in a duration-comparison procedure to peck one key if the comparison duration (c) was 1 sec shorter than a standard duration (s), and another key if c was 1 sec longer than s. During training, the s-c delay was 1 sec, and the total duration of an s-c pair was not predictive of the correct choice. In Experiment 1, during equal-duration pair test trials, pigeons increasingly responded long (i.e., c τ s) as the s-c delay was lengthened. In Experiment 2, we demonstrated that s affected long responding on equal-duration test trials, even at the 8-sec s-c delay. In Experiment 3, long responding increased as the s-c delay was lengthened, even when stimulus conditions during the s-c delay differed from those during the intertrial interval (ITI). Additional analyses indicated that it was unlikely that the increase in long responding was due to the pigeons’ adding the s-c delay to c and comparing the total against the duration of s. The increase in long responding with an increase in s-c delay is more consistent with subjective shortening of s than with confusion between the s-c delay and the ITI.  相似文献   

6.
To construct and identify further a recombinant of Adeno-associated virus and interferon-gamma for gene therapy, the full-length IFN-γcDNA containing signal peptide was amplified by PCR, and then cloned into the pUC18. After screening, the fragment from the positive clone was then subcloned into pwp19. After the correct recombinant was identified by digestion with SacI and BamHI, it was transfected into lymphocyte cell line H9 mediated by calcium phosphate, and the expression of IFN-γ was detected by RT-PCR and ELISA. The result showed that the IFN-γ were expressed in the H9 cells transfected with pwp/IFN-γ. The so constructed recombinant plasmid pwp19/IFN-γ containing the full-length IFN-γ gene was expressed in mammalian cells. Project (39570653) supported by NFSC.  相似文献   

7.
为镉的检测寻求一种快速、简便的新方法。通过玻碳悬汞电极测定淡水鱼中镉含量,考查了电沉积电位、电沉积时间、平衡电位、平衡时间对测定结果的影响。结果：当pH值为1.0～2.5、电沉积电位为-1.25V、电沉积时间为60s、平衡电位为-1.0V、平衡时间为30s时,测定结果最好。测定镉的线性范围为0～16ng,检出限为0.24ng/mL,回收率为98.6%～101.2%,相对标准偏差为2.4%。该法操作快速、简便,结果准确、可靠。  相似文献   

8.
Dissection is a unique multisensory educational experience and is essential to learning the anatomical construction of the human and animal bodies. This study aims to introduce a specialized design for the assessment of dissection and to discuss the assessment's attributes. The design was a product of the “assessment drives learning” concept and was developed to motivate students to dissect. Students were awarded “dissection points” based on prior group dissection and identification of structures. Students' perception of the design was examined, and content analysis was performed. The assessment consisted of two parts: the first assigning each student group structures to “pin” on their previously dissected cadavers; the second was a group peer evaluation. The most critical factor for the assessment's success was careful selection of structures assigned to students to pin. The assessment was fit for the purpose, valid, reliable, and had a significant educational impact. Eighty-three percent of students (n = 116) recommended maintaining the assessment design, as they felt it promoted a deep approach to learning as well as teamwork while reducing stress to a minimum. A strong correlation (Spearman's rho = 0.46, P < 0.0001) was present between the high rating of the design and the number of structures learned, as well as, high rating and lower stress level (Spearman's rho = 0.40, P < 0.0001). There was no apparent influence of grades on student perception of the effectiveness of the assessment. This specific design of evaluation could be used as part of anatomy education in veterinary and medical schools.  相似文献   

9.
INTRODUCTION In 1998 gastrointestinal pathologists reached aconsensus on the definition of chronic atrophic gas- tritis (CAG), which was described as programmed loss of gastric gland and/or replacement by intestinal glands in gastric mucosa. CAG was recognized to be closely related with development of gastric cancer and listed as precancerous lesions in this meeting (Genta, 1998). According to Correa (1992)’s cascade of gas-tric carcinogenesis, gastric cancer was believed to develop fr…  相似文献   

10.
The purpose of this article was twofold. The first purpose was to test the validity of the Teachers’ Sense of Self-Efficacy Scale (TSES) in five settings—Canada, Cyprus, Korea, Singapore, and the United States. The second purpose was, by extension, to establish the importance of the teacher self-efficacy construct across diverse teaching conditions. Multi-group confirmatory factor analysis was used to better understand the measurement invariance of the scale across countries, after which the relationship between the TSES, its three factors, and job satisfaction was explored. The TSES showed convincing evidence of reliability and measurement invariance across the five countries, and the relationship between the TSES and job satisfaction was similar across settings. The study provides general evidence that teachers’ self-efficacy is a valid construct across culturally diverse settings and specific evidence that teachers’ self-efficacy showed a similar relationship with teachers’ job satisfaction in five contrasting settings.  相似文献   

11.
A 24-membered ring macrolide compound,macrolactin A has potential applications in pharmaceuticals for its anti-infectious and antiviral activity.In this study,macrolactin A was produced by a marine bacterium,which was identified as Bacillus subtilis by 16S ribosomal RNA(rRNA) sequence analysis.Electrospray ionization mass spectrometry(ESI/MS) and nuclear magnetic resonance(NMR) spectroscopy analyses were used to characterize this compound.To improve the production,response surface methodology(RSM) involving Box-Behnken design(BBD) was employed.Faeces bombycis,the main by-product in sericulture,was used as a nitrogen source in fermentation.The interactions between three significant factors,F.bombycis,soluble starch,and(NH4)2SO4 were investigated.A quadratic model was constructed to fit the production and the factors.Optimum medium composition was obtained by analysis of the model.When cultivated in the optimum medium,the production of macrolactin A was increased to 851 mg/L,2.7 times as compared to the original.This study is also useful to find another way in utilizing F.bombycis.  相似文献   

12.
Following simultaneous discrimination training with pigeons, in which responding to the S−was reinforced on half of the trials and responding to the S− was never reinforced, we examined the effect on the S− of presenting the S− by itself and the effect on the S+ of presenting the S− by itself (relative to an S− or an S− for which there had been no single-stimulus presentations). For Group A−, responding to the S− presented by itself was always reinforced, whereas for Group A−, such responding was extinguished. For Group B−, responding to the S− presented by itself was always reinforced, whereas for Group B+, responding was extinguished. Although both Group A+ and Group A−tended to avoid their associated S− (relative to a control S−), Group A+ avoided its associated S− less than did Group A−. In contrast, although for Group B−, presentation of the S− alone increased the pigeons’ preference for its associated S−(relative to a control S+), for Group B−, presentation of the S−alone had little effect on its preference for its associated S+. These results suggest that presentation of one stimulus from a simultaneous discrimination has two independent and sometimes opposite effects on the other discriminative stimulus. First, it reduces the strength of within-event conditioning between the S+ and the S−, and second, if the value of the singly presented stimulus has increased, some of its newly acquired value will transfer retroactively to the stimulus with which it was originally paired.  相似文献   

13.
The effects of trial (T) and intertrial (I) durations were examined in two Pavlovian conditioning experiments with rats, in which a noise conditioned stimulus (CS) was paired with food delivery. In Experiment 1,T was either 10 or 20 sec, andI ranged from 15 to 960 sec, in separate groups of rats. The acquisition rate and final level of conditioned responding showed ratio invariance: They were better predicted by theI/T ratio than byI orT alone. In Experiment 2, theI/T ratio was 6.0 in all the groups, andT was 20, 40, 80, or 160 sec. Ratio invariance was not observed: Despite the commonI/T ratio, the rate of acquisition, final level of conditioned responding, and the ability of the CS to block conditioning of another stimulus differed among the groups. At the same time, the temporal distribution of conditioned responding withinT was similar in all the groups throughout conditioning and extinction and showed superpositioning when normalized acrossT. Many but not all aspects of the data were consistent with scalar timing theory.  相似文献   

14.
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15.
Statistical power was estimated for 3 randomization tests used with multiple-baseline designs. In 1 test, participants were randomly assigned to baseline conditions; in the 2nd, intervention points were randomly assigned; and in the 3rd, the authors used both forms of random assignment. Power was studied for several series lengths (N = 10, 20, 30), several effect sizes (d = 0, 0.5, 1.0, 1.5, 2.0), and several levels of autocorrelation among the errors (p 1 = 0, .1, .2, .3, .4, and .5). Power was found to be similar among the 3 tests. Power was low for effect sizes of 0.5 and 1.0 but was often adequate (> .80) for effect sizes of 1.5 and 2.0.  相似文献   

16.
ABSTRACT

The psychosocial theory of Gerotranscendence, is proposing an alternative and positive view of aging and states that human development is a lifelong process. Applying the concept of Gerotranscendence into the older adults’ lives may have the potential to provide a more positive view of aging and a better care for a growing population. First; and to do this, we need to use a proper, valid and reliable measure. The purpose of this cross-sectional and methodological study was to assess the psychometric properties of the Persian version of the short-form Gerotranscendence scale (GS-S) in community-dwelling Iranian older adults. First the scale was translated to Persian, and culturally adapted. Then pre-testing and cognitive interviewing implemented in a sample consisted of 10; and stability of the scale in a sample of 30 older adults, respectively. Confirmatory factor analysis and internal consistency of the scale were done with 250 older adults. The three-factor structure was confirmed. The model showed a good fit, and all the indices were satisfactory (RMSEA = 0.063; NNFI = 0.093; CFI = 0.095; IFI = 0.096; GFI = 0.095; and χ2/df = 2). Cronbach’s alpha of the scale was 0.72 and coefficient omega was 0.82. Test-retest reliability (ICC) was 0.88, P < .001; and standard error of measurement was 1.16 (CI = %95). Minimal detectable change (MDC) was 3.2 and minimal important change (MIC) was 1.4. This study supports the use of the GS-S as a measure of life span development among the Iranian older adults.  相似文献   

17.
During Jan. 1995 to Dec. 1996, monthly investigations on the zoobenthic communities of West Lake, samples were collected from six sampling stations. A total of 26 species of macrozoobenthos were identified. The seasonal changes in density and biomass of zoobenthos in this lake were analyzed. The annual mean densities were 980∼2751 ind/m2 and mean biomass was 19.69–122.80 g/m2. The densities in winter and early spring were higher than those in summer and autumn. Comparative study of theprevious data (1982 to 1983) collected by the authors, showed that the succession of zoobenthic communities, dominated byProcludius choreus in density andBellamya purificata in biomass, had been occurred in Xiaonan sub-lake after Qiantang River water was drawn into it; and that the species and biomass of zoobenthos were then increased and the density was decreased. In other sub-lakes, the dominant species wereLimnodrilus hoffmeisteri andTokunagayusurika akamusi in density andBranchiura sowerbyi andTokunagayusurika akamusi in biomass. The water quality was bad in these sub-lakes because these dominant species are indicators of eutrophication. According to the Margalef index and Goodnight index, West Lake is still an eutrophic lake. Only the water quality of Xiaonan sub-lake was improved after water drawn from the Qiantang River was introduced into it. Project supported by the Evironmental Protection Bureau of Hangzhou, China.  相似文献   

18.
Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.  相似文献   

19.
利用同位素示踪法研究14C-艾氏剂在树麻雀中的分布和代谢.结果表明,树麻雀摄食了14C-艾氏剂标记饲料24h后,14C-艾氏剂及其代谢物主要分布于脂肪组织中,浓度是其它组织的5～70倍.艾氏剂在各组织中的分布趋势为脂肪＞气管＞胃＞肝脏＞肠＞脾脏＞羽毛＞心脏＞胰脏＞肾＞剩余部分＞肌肉＞眼＞脑.艾氏剂在树麻雀中被代谢为狄氏剂,后者占可提取态14C活度的91.1%～100%.而母体艾氏剂的比例在各器官组织中都为0.  相似文献   

20.
The utility of Orlando and Thissen’s (2000, 2003) S-X2 fit index was extended to the model-fit analysis of the graded response model (GRM). The performance of a modified S-X2 in assessing item-fit of the GRM was investigated in light of empirical Type I error rates and power with a simulation study having various conditions typically encountered in applied testing situations. The results show that the Type I error rates were controlled adequately around the nominal alpha by S-X2. The power of the S-X2 statistic was much lower when the source of misfit was multidimensionality than when it was due to discrepancy from the true GRM curves. Once the data size increased sufficiently, however, appropriate power was obtained regardless of the source of the item-misfit. In summary, the generalized S-X2 appears to be a promising index for investigating item fit for polytomous items in educational and psychological assessments.  相似文献   

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