Showing papers by "Jun Ma published in 2004"

A Novel Approach to High Performance Elastomer by Using Clay

Abstract: A novel method was developed to prepare an exfoliated styrene butadiene rubber (SBR)/clay nanocomposite with a strong interface between the clay layers and the rubber. An exfoliation mechanism was proposed and verified based on X-ray diffraction (XRD)/transmission electron microscopy (TEM) analyses of the intercalation/exfoliation phenomena after each step of the process. The significant improvements of mechanical properties may give the first evidence that both exfoliation and a strong interface play critical roles in nanoreinforcement.

A novel method for preparation of disorderly exfoliated epoxy/clay nanocomposite

Abstract: Disorderly exfoliated epoxy/clay nanocomposite was first prepared by a novel method. The reaction mechanism and structure were proven by 1HNMR, XRD, and TEM.

Regulation for distribution of metastatic cervical lymph nodes of 512 cases of nasopharyngeal carcinoma

Abstract: BACKGROUND & OBJECTIVE To identify the target volume of radiotherapy is more and more important. This study was designed to explore the regulation for the distribution of metastatic cervical lymph nodes of nasopharyngeal carcinoma (NPC) and to recommend the delineation of clinical target volume of the neck for three-dimensional conformal radiotherapy in NPC. METHODS From Jan. 2003 to Jun. 2004, 512 of cases of NPC, histologically diagnosed, received enhanced transversal CT scan. The cervical node was divided into six levels (I-VI) plus retropharyngeal nodes according to RTOG guidelines proposed in 2003. RESULTS Of 512 patients, 328 (64.1%) had cervical lymphadenopathy at presentation. Of the 328 neck positive cases, the node involvement was unilateral in 61.3% patient and bilateral in 38.7%. 328 (64.1%) cases showed enlargement of retropharyngeal node, and unilateral 50.9%, bilateral 49.1%. The involvement for levelIto level VI and retropharyngeal area in node-positive cases was 3.0%, 97.9%, 46.0%, 9.5%, 13.7%, 0% and 74.4%. Of the node-positive patient, the incidence of skip metastasis was from 4.6% to 6.5%. 25.3% of the node-positive cases showed involvement, which is beyond CTV for the neck of stage N0 recommended by RTOG. CONCLUSIONS The cervical node involvement of NPC is spread orderly down the neck, and the incidence of skip metastasis is lower. Retropharyneal node was the first echo node to metastases of NPC. The retropharyngeal node, level II, and level III were the most frequently involved area. Level Ia and level VI were never involved. There are few cases with positive nodes beyond CTV for the neck of stage N0 recommended by RTOG. Our data is helpful for the delineation cervical target in the 3-D conformal radiotherapy of NPC.

An incremental algorithm for mining classification rules in incomplete information systems

Abstract: One of important research areas in data mining is to develop methods to update knowledge by using the existing knowledge, since it can generally enhance mining efficiency, especially for very large database. Rough set, a new mathematical tool to deal with vagueness and uncertainty, has been successfully applied in data mining. Presently, several approaches based on rough set have been proposed for mining tasks when knowledge updates. However, it only aims at complete information systems. In fact, many information systems are incomplete in practical application. Therefore, in order to support more effective data mining tasks, it is meaningful to develop approaches to update knowledge in incomplete information systems (US). A method for incremental updating approximations of a concept was proposed by T. R. Li, et al (2003), which may realize adding and deleting a few attributes simultaneously at a time. Based on this method, we develop an incremental algorithm for mining classification rules from IIS. Complexity analysis of the algorithm and example show that our method can realize updating knowledge effectively.

A new algorithm for mining fuzzy association rules

Abstract: We introduce a new algorithm for mining the fuzzy association rules by removing redundant fuzzy association (RFA) rules. Firstly, we analyze some properties of fuzzy association rules and give the definition of RFA rules. Secondly, using the degree of implication on fuzzy implication operator, we introduce a new algorithm to mine fuzzy association rules from frequent itemsets. Finally, an example is given to illustrate our idea.

Catalytic ozonation of trace nitrobenzene in water by iron hydroxide

Abstract: Laboratory produced iron hydroxide was tested for its activity in catalytic ozonation of trace nitrobenzene (NB) in water. The catalysis mechanism was deduced from the effect of tert butanol on the reaction and the difference of catalytic activity between several typical transition metal oxides. Effects of catalyst dose, pH, bicarbonate ion, and times of catalyst reuse on NB removal were also examined. The iron hydroxide showed high catalytic activity on ozonation of NB with removal rate of NB dissolved in distilled water increased by 44.8% at reaction time of 20min. The catalysis follows a hydroxyl radical pathway and is affected by density of hydroxyl groups on the oxide. An optimal catalyst dosage of 100mg/L existed in this experiment. Solution pH near pH of zero charged surface of the oxide favored NB removal and bicarbonate concentration of 2 38mmol/L significantly reduced it. The oxide was used for five times with no significant change of its activity and no dissolution was observed.

An algorithm for mining lower closed itemsets

Abstract: The generalized association rule base(GARB) presented by Li(2003) can efficiently solve the problem of quantity of rule in the process of acquiring rule by traditional association rule mining algorithms. Therefore, how to deduce all rules contained in the rule of GARB becomes an urgent issue in order to support more effective decision-making. In this paper, the notation of lower closed itemset of an itemset was proposed and some properties of it are proved. Then, it is concluded that the above problem can be solved if all the lower closed itemsets of frequent closed itemset(FCI) are obtained. Finally, an algorithm for mining all lower closed itemsets of an itemset was given and its validity is proved.