Chitosan graft copolymers‐HA/DBM biocomposites: Preparation,characterization, and in vitro evaluation

The combination of biopolymer with a bioactive component takes advantage of the osteoconductivity and osteoinductivity properties. The studies on composites containing hydroxyapatite (HA), demineralized bone matrix (DBM) fillers and chitosan biopolymer are still conducted. In the present study, the bioactive fillers were loaded onto p(HEMA‐MMA) grafted chitosan copolymer to produce a novel biocomposites having osteoinductive and osteoconductive properties. The produced composites were assessed by TGA, XRD, FTIR, and SEM techniques to prove the interaction between both matrices. In vitro behavior of these composites was performed in SBF to verify the formation of apatite layer onto their surfaces and its enhancement. The results confirmed the formation of thick apatite layer containing carbonate ions onto the surface of biocomposites especially these containing HA‐DBM mixture and pMMA having bone cement formation in their structure. These a novel biocomposites have unique bioactivity properties can be applied in bone implants and tissue engineering applications as scaffolds in future. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

V<Subscript>2</Subscript><Emphasis Type="Italic">O</Emphasis><Subscript>5</Subscript>/SiO<Subscript>2</Subscript> as a Heterogeneous Catalyst in the Synthesis of bis(indolyl)methanes Under Solvent Free Condition

The heterogeneous catalyst of V₂ O ₅/SiO₂ was prepared and characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy. XRD of the silicon dioxide used reveals the amorphous nature while the spectrum of the prepared catalyst shows sharp intense peaks at about (20.2, 26.1, 31.0 and 47.3^°) and less intense sharp peaks at about (51.1, 55.2, 57.1 and 60.4^°) indicating formation of a crystalline phase with orthorhombic geometry. The FTIR spectra of the catalyst showed characteristic vibration stretching bands of V ?O at their specified position. An efficient and facile approach for the synthesis of bis(indolyl)methanes through a catalytic one pot reaction. Indole and aromatic aldehydes were stirred in the presence of a catalytic amount of the prepared and characterized heterogeneous catalyst V₂ O ₅/SiO₂ at 50^°C under solvent free condition. This procedure has advantages in competition with the previously reported methods, in terms of high yield, green catalyst, mild reaction condition, simple procedure, lack of toxicity, low cost, and simplicity of workup.     

术后辅助放化疗与单纯手术治疗在胃腺癌中的比较

Objective: Despite resection with curative intent, a majority of patients with gastric cancer will develop disease recurrence. Postoperative adjuvant chemo-radiotherapy increase the curability of surgery, prevent local recurrence and improve survival. Methods: Between December 2005 and February 2010, 33 patients were eligible for the study, 17 patients were randomly assigned for chemo-radiotherapy (GI) and 16 patients with surgery alone (GII). Patients in GI received chemotherapy (fluorouracil, 425 mg/m2/day, and leucovorin, 20 mg/m2/day, for 5 days) was initiated on day 1 and was followed by chemo-radiotherapy beginning 28 days after the start of the initial cycle of chemotherapy. Chemo-radiotherapy consisted of 4500 cGy of radiation at 180 cGy/day, five days/week for five weeks, with fluorouracil (400 mg/m2/day) and leucovorin (20 mg/m2/day) on the first four and the last four days of radiotherapy. One month after the completion of radiotherapy, two five-day cycles of fluorouracil (425 mg/m2/day) plus leucovorin (20 mg/m2/day) were given one month apart. Results: Grade 3 gastrointestinal toxicity was more common (23.2%) while grade 3 hematological toxicity were (5.8%). Both 3-year survival (53%) and disease free survival (41%) rates were higher in GI than in GII in which they were 43.7% and 31% respectively. Relapse rate was higher in GII (56.3%) than in GI (35.3%). Conclusion: The present study revealed that chemo-radiotherapy after gastric resection in patients with gastric adenocarcinoma improves survival and relapse rates with manageable toxicities. However, studies with larger number of patients are recommended to confirm our results.     

Welfare through regulatory means: eviction and repossession policies in Singapore*

The study and provision of welfare have long been synonymous with direct social spending. The provision of welfare through regulatory means poses a complementary perspective to the study of social policy. In this context, this paper focuses on policies aimed at preventing mortgage borrowers’ eviction and repossession in Singapore, a world leader in state-led owner occupancy but a welfare laggard in terms of social spending. The findings show a disparity between a high rate of arrears on housing credit, and a low level of eviction and repossession. We test several explanations for this disparity, and argue that it is the result of policy aiming to minimize eviction and repossessions. This policy is driven by institutional interdependencies within the state, which have tied citizens’ housing credit to other aspects of their individual welfare savings. The findings shed light on the central role of regulation in welfare.     

On voting-based consensus of cluster ensembles

Voting-based consensus clustering refers to a distinct class of consensus methods in which the cluster label mismatch problem is explicitly addressed. The voting problem is defined as the problem of finding the optimal relabeling of a given partition with respect to a reference partition. It is commonly formulated as a weighted bipartite matching problem. In this paper, we present a more general formulation of the voting problem as a regression problem with multiple-response and multiple-input variables. We show that a recently introduced cumulative voting scheme is a special case corresponding to a linear regression method. We use a randomized ensemble generation technique, where an overproduced number of clusters is randomly selected for each ensemble partition. We apply an information theoretic algorithm for extracting the consensus clustering from the aggregated ensemble representation and for estimating the number of clusters. We apply it in conjunction with bipartite matching and cumulative voting. We present empirical evidence showing substantial improvements in clustering accuracy, stability, and estimation of the true number of clusters based on cumulative voting. The improvements are achieved in comparison to consensus algorithms based on bipartite matching, which perform very poorly with the chosen ensemble generation technique, and also to other recent consensus algorithms.     

Fault Management in Distributed Systems: A Policy-Driven Approach

Managing the availability and performance of a distributed system involves monitoring the behavior of the system, identifying system problems, and correcting those problems. Each of these tasks requires some expertise, such as an understanding of the mechanics of the underlying system components. As the size and complexity of these systems increases, and the number of distributed applications executing on these systems increases, managing the availability and performance of distributed systems becomes more difficult. Little research has focused on embedding systems management expertise into a management application for a distributed system. In this paper we describe a rule-based management application for a commercially available distributed computing environment that is capable of monitoring the distributed system, detecting system service-related performance and availability problems, and generating corrective actions to correct the problems.     

Bacterial community composition and structure of biofilms developing on nanofiltration membranes applied to wastewater treatment

The structure and microbial communities of biofilms developing on cross-flow nanofiltration (NF) membranes at different temperatures (20, 25 or 34 degrees C) and operation lengths (8h-24days) were studied. Feedwater comprised tertiary quality wastewater effluent or synthetic media mimicking effluents of intermediate quality. After each run, the membranes were autopsied for bacterial enumeration, bacterial community composition and microscopy visualization (SEM, CLSM and AFM/NSOM). Community composition was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) coupled with sequence analysis of 16S rRNA gene fragments from dominant bands. Deposition of polysaccharides and initial bacterial colonization were observed within 8h, whereas developed biofilms markedly affecting membrane permeability were evident from days 2-3 onwards. Regardless of applied conditions, the heterotrophic plate counts in the biofilm were 3-4x10(6)CFU/cm(2) and the thickness of the biofouling layer was 20-30microm. From a total of 22 sequences obtained from 14 independent experiments, most species identified were Gram negative (19 of 22 sequences). Proteobacteria were found to be a prevalent group in all cases (16 of 22 sequences) and among it, the beta-subclass was the most predominant (8 sequences), followed by the gamma-subclass (5 sequences). Pseudomonas/Burkholderia, Ralstonia, Bacteroidetes and Sphingomonas were the dominant groups found in most cases. Even though the microbial population might be important with respect to biofouling patterns, membrane permeability decline seems to be more substantially influenced by the formation and accumulation of exopolymeric substances (EPS).     

Free-radical scavenging and antioxidative activities of some polysaccharides in emulsions

The antioxidant activity in linoleate emulsion systems, radical scavenging activity and inhibition of autoxidation in sunflower oil-in-water emulsions were studied in the presence of polysaccharide produced by Rhizobium meliloti (RPS), xanthan, curdlan, and carboxymethylcellulose (CMC) and compared to tertiary butylhydroxyquinone (TBHQ). The antioxidant activity in the linoleate emulsion was improved with increasing pH from 3 to 9 and concentration of polysaccharide from 20 to 60 mg/100 g emulsion, while it decreased with increase in storage temperature between 30 and 90 °C. The antioxidant activity of xanthan, curdlan, and RPS at concentration of 40 mg/100 g emulsion was equal to that of TBHQ at 20 mg/100 g emulsion. RPS showed the highest thermal stability and the lowest linoleic oxidation values compared to TBHQ, xanthan, and curdlan at 90 °C. The antioxidant activity of xanthan, curdlan, and RPS in linoleate emulsions at pH 3 and 5 was in the first order with significant (P<0.05) values compared to emulsion, prepared using TBHQ.Curdlan and RPS were effective in radical scavenging being 60-90% at pH values ranging between 3 and 7. They showed an ability to inhibit lipid oxidation in sunflower oil emulsions during holding time for 50 h at 60 °C. In general, the polysaccharides RPS and curdlan can be used as food additives having many functions as stabilizers, radical scavengers, and antioxidants in emulsified foods such as mayonnaise, salad dressings, and cake products.