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Erosion behavior and mechanism of boronised steels
LIU Li, LING Guo-ping, LIU Tao, LI Jian
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 278-282.
https://doi.org/10.1631/jzus.2002.0278
Boronising of steels is a hardening process to get high surface hardness. The erosion resistance of boronised steels was researched with the use of four kinds of erodent, i.e. glass, alumina, quartz and silicon carbide. The erosion rate increases rapidly with erodent hardness and severe erosion occurs with high impacting angle range of hard particles. SEM analysis indicated that chipping is caused by repetitive impacting of glass and quartz, whereas by alumina and silicon carbide impacting, chipping, and that plastic flow take place simultaneously and the erosion rate reaches the peak value when the impacting angle is above 60°.
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Consistency maintenance for constraint in role-based access control model
HAN Wei-li, CHEN Gang, YIN Jian-wei, DONG Jin-xiang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 292-297.
https://doi.org/10.1631/jzus.2002.0292
Constraint is an important aspect of role-based access control and is sometimes argued to be the principal motivation for role-based access control (RBAC). But so far few authors have discussed consistency maintenance for constraint in RBAC model. Based on researches of constraints among roles and types of inconsistency among constraints, this paper introduces corresponding formal rules, rule-based reasoning and corresponding methods to detect, avoid and resolve these inconsistencies. Finally, the paper introduces briefly the application of consistency maintenance in ZD-PDM, an enterprise-oriented product data management (PDM) system.
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Principal component analysis using neural network
YANG Jian-gang, SUN Bin-qiang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 298-304.
https://doi.org/10.1631/jzus.2002.0298
The authors present their analysis of the differential equation dX(t)/dt=AX(t)-XT(t)BX(t)X(t), where A is an unsymmetrical real matrix, B is a positive definite symmetric real matrix, X∈Rn; showing that the equation characterizes a class of continuous type full-feedback artificial neural network; We give the analytic expression of the solution; discuss its asymptotic behavior; and finally present the result showing that, in almost all cases, one and only one of following cases is true. 1. For any initial value X0∈Rn, the solution approximates asymptotically to zero vector. In this case, the real part of each eigenvalue of A is non-positive. 2. For any initial value X0 outside a proper subspace of Rn, the solution approximates asymptotically to a nontrivial constant vector &Ytilde;(X0). In this case, the eigenvalue of A with maximal real part is the positive number λ=‖(X0)‖2B and (X0) is the corresponding eigenvector. 3. For any initial value X0 outside a proper subspace of Rn, the solution approximates asymptotically to a non-constant periodic function &Ytilde;(X0,t). Then the eigenvalues of A with maximal real part is a pair of conjugate complex numbers which can be computed.
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Analysis of bulked segregants to identify molecular markers linked with cocoon weight and cocoon shell weight in the silkworm Bombyx mori L
Sateesh Kumar, XU Meng-kui, CHEN Yu-yin, Ponnuvel, K.M., Datta, R.K.
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 348-354.
https://doi.org/10.1631/jzus.2002.0348
Two silkworm strains viz, B20 A (high cocoon shell ratio) and C.Nichi (low cocoon shell ratio) were sib mated for 10 generations to determine the homozygosis. Both bulked segregant analysis(BSA) and near isogenic lines (NIL) studies were done to identify the RFLP markers closely linked to cocoon shell parameters. Three hundred and fifty-two random clones were identified as the low copy number sequence and used for identification of Restriction Fragment Length Polymorphic (RFLP) marker linked to cocoon weight and cocoon shell character. In the bulk segregant analysis, DNA from the parents (B20 A, C.Nichi), F1 and F2 progeny of high shell ratio (HSR) and low shell ratio (LSR) were screened for hybridization with the random clones. Polymorphic banding pattern achieved through southern hybridization with different probes indicated the probable correlation of polymorphism with high and low cocoon shell character which are possible landmarks in identifying the putative marker(s) for the cocoon shell character. Out of the 100 probes tried with parents, F1, F2 and their bulks, 10 probes were found to be closely linked to cocoon shell characters.
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Phosphate-solubilizing microbes in rhizosphere soils of 19 weeds in southeastern China
CHEN Xin, TANG Jian-jun, FANG Zhi-guo, HU Shuijin
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 355-361.
https://doi.org/10.1631/jzus.2002.0355
Low phosphorus (P) availability is one of the most important factors limiting plant growth in red soils across southeastern China. Many non-symbiotic microorganisms in rhizosphere can enhance P solubility, but little is known about the magnitude of their phosphorus-solubilizing ability (PSA) and the difference in phosphorus-solubilizing microorganisms (PSM) among plant species. The number of phosphorus-solubilizing microorganisms and their PSA in rhizosphere soils of 19 weed species in a citrus orchard on red soil at Changshan, Zhejiang, China, were investigated. Inorganic P (powdered phosphate rock, PR) and organic P (lecithin, OP) were respectively used as the sole P-source to examine the PSA of isolated microbes. The PS actinomycetes community varied greatly among the different weed rhizospheres while the PS fungus community showed to be most stable to the weed rhizosphere. The highest number of PR-PS and OP-PS bacteria was found in rhizosphere soil of Mollugo pentaphyll, and the highest number of PR-PS and OP-PS actinomycetes was found in rhizosphere soil of Polygonum lapathifolium. The highest number of PR-PS fungi was found in Erigeron annuus and Mollugo pentaphyll rhizosphere soil, and the highest number of OP-PS fungi was found in rhizosphere soil of Mazus stachydifolius. Mazus stachydifolius showed the strongest PR-PS ability (6340.75 μg) while Eragrostis pilosa showed the strongest OP-PS ability (1301.84 μg). The PR-PS ability and OP-PS ability of Mollugo pentaphyll was 4432.87 μg and 1122.05 μg respectively. A significant correlation between the number of PR-PSM and OP-PSM was found. Significant correlation was only found between the PR-PS fungi number and its PSA (r=0.75, P<0.05) and between the number of OP-PS fungi and its PSA (r=0.87, P<0.01). It indicated that plant species had significant influence on components of the non-symbiotic PSM community and their activity in its rhizosphere soil. Fungi play a leading role in phosphorus solubilization in weed rhizopshere. It suggested that weed conservation could benefit soil microbe development in agroecosystems, especially in the initial stage of agroecosystem development because there is less organic carbon in bare soil. The results suggested that weed conservation could increase PSA of PSM.
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Study on the submerged fermentation (SMF) of termitomyces eurrhizus
ZHANG Ming, ZHENG Xiao-dong, CHEN Xi-nai, YIN Yuan-ming
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 362-366.
https://doi.org/10.1631/jzus.2002.0362
The influence of KH2PO4, peptone and brown sugar on Termitomyces fuliginosu\'s mycelium formation was studied with the application of the design of quadratic rotation general combination based on determining the growth curve. A quadratic regression model of biomass to the doses of the above three factors was established. The model fit well and therefore the optimum fermentation condition was obtained. Responses of biomass to the three single factors and to their interactions were discussed. Thus, the highest level of biomass, 21.1 g/L, appeared under the optimized conditions when the initial KH2PO4, peptone and brown sugar were 1 g/L, 4 g/L and 72 g/L respectively.
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Application of GlycoProtein IIb/IIIa antagonist (Integrilin) in peri-percutaneous transluminal catheter angioplasty and stent implantation in Chinese
WANG Jia-nan, SUN Yong
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 371-373.
https://doi.org/10.1631/jzus.2002.0371
Objective: to report the application of GPIIb/IIIa antagonist (Integrilin) in peri-percutaneous transluminal catheter angioplasty and stent implantation in Chinese. Method: Twenty-one patients who underwent percutaneous transluminal catheter angioplasty(PTCA) and stent implantation were included. After arterial puncture, integrilin was injected at dose of 180 μg/kg, and then maintained at 2 μg/kg·min for 18 hours. Asprine, plavix(clopidogrel) and heparin were used at the same time. ACT, PT, KPTT and blood routine were routinely monitored. Results: All sheaths were drawn out 2 to 4 hours after the procedure.. There was no severe complication such as hematoma, acute and subacute thrombosis in coronary artery, or thrombocytopenia. ACT returned to less than 150 seconds in 2 hours in 15 patients; in 4 hours in 6 patients. There was no significant difference between the pre- and post-procedure value of PT and platelet count. KPTT was significantly higher than pre-procedure value at 2 hours after the procedure. No recurrence of angina pectoris was observed in the first nine patients within one year follow-up, and no restenosis occurred in stents in the five patients who had coronary angiography one year later. Conclusion: Application of GPIIb/IIIa receptor antagonist (Integrilin) in peri-percutaneous transluminal catheter angioplasty and stent implantation in combination with aspirin and plavix could significantly reduce the dosage and duration of heparin with benefit of shortening the indwelling time of sheaths, but did not increase risk of bleeding or lead to thrombosis in stent.
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Ultra-Cut biopsy guided by ultrasonography for liver lesions: experience of 392 clinical cases
PAN Hong-ming, FAN xiao-ming, WANG Hai-yun, WU Jin-min
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2002, 3(3): 374-377.
https://doi.org/10.1631/jzus.2002.0374
We conducted a retrospective study of the accuracy of liver biopsies in 392 patients with liver lesions. Postbiopsy diagnosis was 297 cases of primary liver cancers, 79 cases of secondary malignant tumors, 2 cases of non-Hodgkin\'s lymphoma, 10 cases of focal nodular hyperplasia, 2 cases of chronic inflammation, 1 tuberculosis case and 1 schistosomiasis case. Biopsy provided histological diagnosis in 100% of cases, sensibility and specificity of Ultra-Cut biopsy was 98.95% and 100% for the diagnosis of malignancy respectively; positive predictive value, 100%; negative predictive value, 71.43%; and accuracy, 98.98%. We identified no major procedure related complications despite the presence of thrombocytopenia in 37.5% of cases. Pain was the only reported adverse effect of liver biopsy (10.97%), and 11 patients required analgesics. We concluded that Ultra-Cut liver biopsy was a safe and effective technique, and was invaluable in the investigation and management of patients with liver lesions.
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25 articles
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