Synthesis,Surface-Active Properties,and Antimicrobial Activities of New Neutral and Cationic Trimeric Surfactants

Neutral and cationic series of new trimeric β-hydroxy amino or ammonium surfactants were synthesized via a two-step process involving the Williamson etherification and regioselective oxirane ring opening with primary and tertiary amines, which afforded good to excellent yields. The synthesized compounds were obtained in high purity by a simple purification procedure on column chromatography. The critical micelle concentration (CMC), effectiveness of surface tension reduction (γ _CMC), surface excess concentration (Γ), and area per molecule at the interface (A) were determined and values indicate that the cationic series is characterized by good surface-active and self-aggregation properties. The antimicrobial activities are reported for the first time against representative bacteria and fungi for trimeric compounds. The antimicrobial potency was found to be dependent on the target microorganism (Gram-positive bacteria > fungi > Gram-negative bacteria), as well as both the neutral or ionic nature (cationic > neutral) and alkyl chain length (tri-C₁₂ > tri-C₁₈ > tri-C₈) of the compounds. The tri-C₈ and tri-C₁₈ compounds were found to be almost inactive and the tri-C₁₂ compounds, the most potent antimicrobial surface-active agents from the synthesized series. The trimeric C₁₂ cationic compound was found to be comparable to benzalkonium chloride against Gram-positive bacteria and fungi, in vitro. The antimicrobial effectiveness of this new compound and the facile two-step procedure for synthesizing it with an excellent overall yield (92%) provide a cost effective trimeric gemini surfactant.

The impact of Internet transmission on the uncertainty in the electric power quality estimation by means of a distributed measurement system

There is increasing evidence, in literature, that the estimation of the electric power quality requires the simultaneous measurement of several quantities and indices in all lines connected to the same point of common coupling. The increase in the performance that the measuring systems based on digital signal processing techniques has undergone during recent years and the capability of the digital systems of interconnecting and exchanging data are making these systems more and more appealing and cost-effective for power quality applications. Moreover, the availability of a world-wide, low-cost, and public-domain interconnection system, the Internet, is pushing the evolution of the remote measurement systems, where the measurement results provided by in-field measurement systems are collected and stored by a central unit, toward the distributed measurement systems, where different systems, located in different places, share the same data in order to perform a measurement. It is known that the major drawback of these systems is the lack of synchronization of the shared data, due to the variable and unpredictable throughput of the net, which may affect the uncertainty of the result of the measurement in a quite significant way. This paper analyzes a distributed measurement system for electric power quality measurements and shows how the possible detrimental effects of data transmission over an Internet connection can be reduced by means of a suitable use of averaging techniques, thus avoiding a strict and expensive synchronization between the different units of the distributed measurement system. Finally, an estimate of the effects of the possible transmission delays on the measurement uncertainty is given.     

Transcatheter arterial chemoembolization in cytoreduction of inoperable hepatocarcinomas

Transcatheter arterial chemoembolization (TAE) is often considered a mean of palliation for inoperable liver carcinomas. A few centers use a sequential treatment (TAE followed by surgery). However the role of TAE in bringing to surgery patients with hepatocarcinomas (HCC) considered inoperable at first diagnosis is debated. We report on the case of a 57 y.o. male diagnosed as having HCC, inoperable because of bilateral location and size. The patient was treated with repeated TAEs and the results were monitored with CT scans. After three TAEs, the main tumor mass volume was reduced 2.2 fold and the patient could undergo surgery; the postoperative period was uneventful, with no clinical signs of liver failure. Our experience leads us to suggest that TAE, further to being an option for palliation, can be a valuable tool to lead to surgery otherwise inoperable HCC patients.     

A neurofuzzy application for AC motor drives monitoring system

Currently industrial applications require suitable monitoring systems able to identify any decrease in efficiency resulting in economic losses. This paper shows that the information coming from a general purpose monitoring system can be usefully exploited to realize a sensorless instrument for the monitoring of an ac motor drive, and can be fed to a diagnostic tool for providing useful risk coefficients. The method is based on digital processing of the line signals acquired by means of a virtual instrument. The employed wavelet algorithms have been implemented within a Matlab environment, and risk coefficients are generated by means of suitable neurofuzzy algorithms.     

A procedure for the identification of the source of distortion in three-phase systems by means of the measurement of current components

The practical application of electric power theories under non-sinusoidal conditions relies on the availability of accurate and reliable methods for the identification of the source of distortion. The present paper proposes a current decomposition that allows to identify whether the source of distortion of the line signals is located after the metering section or before it. The proposed decomposition applies to three-phase systems under whatever conditions of distortion, asymmetry and unbalance. An instrument able to attain the proposed decomposition is also described and the results of some experimental work are reported as well as the measurement accuracy and sensitivity.