Hydrolysis of titanium alkoxide and effects of hydrolytic polycondensation parameters

Titanium alkoxides hydrolyse vigorously with water producing polycondensates whose equivalent oxide content varies from 70% to over 90%. This variation reflects the average molecular size and the nature of the terminal bonds. Hydrolysis conditions also affect the molecular and particle morphologies modifying the crystallization and sintering behaviour of oxide materials derived from polycondensates. It is also possible to form clear polymer solutions under excess water hydrolysis with the addition of certain acids. Investigations show that there is a window in the acid concentration which provides long-term solution stability. The gels formed from these clear solutions shrink in their liquor under certain conditions and the introduction of hydrogen peroxide into the liquor (surrounding the gel) causes vigorous gel shrinkage.     

Comparing alternative classifiers for database marketing: The case of imbalanced datasets

There are various algorithms used for binary classification where the cases are classified into one of two non-overlapping classes. The area under the receiver operating characteristic (ROC) curve is the most widely used metric to evaluate the performance of alternative binary classifiers. In this study, for the application domains where the high degree of imbalance is the main characteristic and the identification of the minority class is more important, we show that hit rate based measures are more correct to assess model performances and that they should be measured on out of time samples. We also try to identify the optimum composition of the training set. Logistic regression, neural network and CHAID algorithms are implemented for a real marketing problem of a bank and the performances are compared.     

Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

Competitive removal of Pb2+, Cd2+, and Zn2+ by poly(acrylamide‐co‐maleic acid) hydrogels/differential pulse polarographic determination

Poly(acrylamide‐co‐maleic acid) [P(AAm/MA)] hydrogels, with various compositions, were prepared from ternary mixtures of acrylamide (AAm)/maleic acid (MA)/water by using ⁶⁰Co γ‐rays. The effect of composition of these hydrogels, on the competitive removal of Pb²⁺, Cd²⁺, and Zn²⁺ ions from aqueous solution, was investigated. The hydrogel compositions and their adsorption behaviors were determined by use of differential pulse polarography, a very sensitive electroanalytical technique. It was observed that the external stimuli of pH, temperature, and ionic strength have an important role on the adsorption. The increments of MA content in P(AAm/MA) hydrogels caused a significant increase in the adsorption these ions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2401–2406, 2004     

The effect of atmospheric plasma treatment of recycled carbon fiber at different plasma powers on recycled carbon fiber and its polypropylene composites

To increase the mechanical properties of recycled carbon fiber-reinforced polypropylene (PP) composites, recycled carbon fibers (RCF) were subjected to atmospheric plasma treatment at different plasma powers (100, 200, and 300 W). The changes on surface topography and roughness of RCF were examined by atomic force microscopy. Plasma treatment of RCF increased the roughness value of RCF. The variation of surface elemental compositions and tensile strength of RCF were determined by using X-ray photoelectron spectroscopy and tensile test, respectively. Plasma-treated RCF-reinforced PP composites were fabricated using high speed thermo-kinetic mixer. Plasma treatment of RCF at 100 W increased the tensile and flexural strength values of RCF-reinforced PP composites considerably by 17 and 11%, respectively. However, plasma treatment of RCF at higher plasma powers (200 W and 300 W) decreased tensile and flexural strength values of composites because of the etching of RCF. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47131.     

Web Authoring for Accessibility (WAfA)

Conventional thought from the Semantic Web community equates the use of ontologies with the representation of the meaning of content. Here, we skew this viewpoint by describing our ontology, Web Authoring for Accessibility (WAfA), which investigates the way ontologies can describe the semantic structure of documents. By understanding the way heterogeneous XHTML (Extensible Hypertext Mark-up Language) documents are structured we can better transform documents, currently inaccessible to visually impaired users. WAfA performs two tasks: (1) it allows us to flexibly model an XHTML document within the context of navigation and orientation through the Web resource; (2) it enables non-expert users to quickly annotate a Web document by providing a ‘lingua franca’ between author and Web Accessibility Domain Experts. Here we describe our ontology, its use, novelty, and importance.     

Behavior change through wearables: the interplay between self-leadership and IT-based leadership

Electronic Markets - Physical inactivity is a global public health problem that poses health risks to individuals and imposes financial burdens on already strained healthcare systems. Wearables...     

Alumina gels that form porous transparent Al2O3

Formation of a porous transparent Al₂O₃ from aluminium alkoxides has been previously reported. During the process, alkoxides are hydrolyzed and the resultant hydroxide is peptized to a clear sol. The sol then must be gelled and pyrolyzed to 500° C to obtain the aluminium oxide. This paper discusses the gel state and the requirements for the system to retain its integrity during the drying and pyrolysis. Influence of electrolytes on the sol-gel transformation shows that there is a critical electrolyte concentration at which the gelling volume goes through a pronounced minimum. Deviation in either direction of this electrolyte concentration causes a sharp increase in the relative gelling volume and detrimentally effects the capability of the gel to retain its integrity. The sols that gel at concentrations less than ～4 g equivalent oxide per 100 ml do not retain their integrity during pyrolysis.