Thermal, microbial, and corrosion resistant metal-containing poly(Schiff) epoxy coatings

Metal-containing epoxy resins [Er?CM(II)] have been prepared by the reaction of Schiff base metal complexes and epichlorohydrin in basic medium. All the synthesized monomers and polymers were characterized by elemental, spectral (IR, ¹H-NMR, and ¹³C-NMR), and thermal analysis. Coatings of the metal-containing epoxy resins were prepared on naval steel strips and subjected to physicomechanical and anticorrosive tests. The surface morphology and thickness of the coatings was found to be 75?±?10???m. The Zn(II) chelated epoxy resin showed lower I _corr values of 0.482, 0.520, and 1.02???A/cm² in NaCl, NaOH, and HCl solution (3.5?wt%), respectively. In addition, the antimicrobial activity of the prepared coating strips was carried out by using minimum inhibitory concentration and minimum bactericidal concentration methods against S. aureus, B. subtilis, E. coli, and P. aeruginosa. It was found that the Er?CCu(II) showed higher antibacterial activity than other metal chelated epoxy resins.     

Causal memory: definitions,implementation, and programming

Summary The abstraction of a shared memory is of growing importance in distributed computing systems. Traditional memory consistency ensures that all processes agree on a common order of all operations on memory. Unfortunately, providing these guarantees entails access latencies that prevent scaling to large systems. This paper weakens such guarantees by definingcausal memory, an abstraction that ensures that processes in a system agree on the relative ordering of operations that arecausally related. Because causal memory isweakly consistent, it admits more executions, and hence more concurrency, than either atomic or sequentially consistent memories. This paper provides a formal definition of causal memory and gives an implementation for message-passing systems. In addition, it describes a practical class of programs that, if developed for a strongly consistent memory, run correctly with causal memory. Mustaque Ahamad is an Associate Professor in the College of Computing at the Georgia Institute of Technology. He received his M.S. and Ph.D. degrees in Computer Science from the State University of New York at Stony Brook in 1983 and 1985 respectively. His research interests include distributed operating systems, consistency of shared information in large scale distributed systems, and replicated data systems. James E. Burns received the B.S. degree in mathematics from the California Institute of Technology, the M.B.I.S. degree from Georgia State University, and the M.S. and Ph.D. degrees in information and computer science from the Georgia Institute of Technology. He served on the faculty of Computer Science at Indiana University and the College of Computing at the Georgia Institute of Technology before joining Bellcore in 1993. He is currently a Member of Technical Staff in the Network Control Research Department, where he is studying the telephone control network with special interest in behavior when faults occur. He also has research interests in theoretical issues of distributed and parallel computing especially relating to problems of synchronization and fault tolerance.This work was supported in part by the National Science Foundation under grants CCR-8619886, CCR-8909663, CCR-9106627, and CCR-9301454. Parts of this paper appeared in S. Toueg, P.G. Spirakis, and L. Kirousis, editors,Proceedings of the Fifth International Workshop on Distributed Algorithms, volume 579 ofLecture Notes on Computer Science, pages 9–30, Springer-Verlag, October 1991The photograph of Professor J.E. Burns was published in Volume 8, No. 2, 1994 on page 59This author's contributions were made while he was a graduate student at the Georgia Institute of Technology. No photograph and biographical information is available for P.W. Hutto Gil Neiger was born on February 19, 1957 in New York, New York. In June 1979, he received an A.B. in Mathematics and Psycholinguistics from Brown University in Providence, Rhode Island. In February 1985, he spent two weeks picking cotton in Nicaragua in a brigade of international volunteers. In January 1986, he received an M.S. in Computer Science from Cornell University in Ithaca, New York and, in August 1988, he received a Ph.D. in Computer Science, also from Cornell University. On August 20, 1988, Dr. Neiger married Hilary Lombard in Lansing, New York. He is currently a Staff Software Engineer at Intel's Software Technology Lab in Hillsboro, Oregon. Dr. Neiger is a member of the editorial boards of theChicago Journal of Theoretical Computer Science and theJournal of Parallel and Distributed Computing.     

Nanocrystalline wurtzite Si–nickel silicide composite thin films with large band gap and high resistivity

Stabilization of wurtzite Si nanocrystals embedded in a metal/metal silicide matrix by the metal induced crystallization process is demonstrated. The process involves the growth of 50 nm thick Ni films on borosilicate glass (BSG) substrates followed by 700 nm thick amorphous Si films and annealing of this multilayered stack at 550 °C in furnace atmosphere for 1 h. The presence of wurtzite Si is established based on electron diffraction studies and is also confirmed by the Raman signature of wurtzite Si at 504 cm⁻¹. It is shown that the growth of wurtzite Si is mediated by the formation of Nickel Silicide, as evidenced by the Raman signal at 294 cm⁻¹. The films exhibit a band gap greater than 1.9 eV with dc resistances of the order of 10 GΩ. It is proposed that such high resistivities should make this form of Si ideal for PV and microwave device applications.     

Vital Sign Monitoring System for Healthcare Through IoT Based Personal Service Application

The most burning issues worldwide at present are the availability, accessibility, and affordability of the equitable healthcare services for all. It is getting more severe for developing countries due to increasing population and chronic diseases. The emerging technological interventions in the field of Internet of Things (IoT)-based healthcare systems are a promising solution to meet the general public's healthcare needs. Therefore, an IoT-enabled vital sign monitoring system has been presented in this paper. The presented system can monitor various vital signs in real-time and store the recorded trends locally. The system can also send the data into cloud for further analysis. Abnormality detection with alert notification and automatic calculation of early warning score has been implemented. An Android application is developed to store the vital signs records on a personal server to avoid the burden and maintenance cost of the central medical server. The presented system is straightforward, compact, portable and easy to operate through personal service application. Also, the presented system is compared with the most recent work available in the field.

     

Effect of sintering parameters on the dynamic hysteresis scaling behavior of Ba0.85Sr0.15Zr0.1Ti0.9O3 ceramics

This article presents the effect of processing parameters on the ferroelectric hysteresis behavior of Ba_0.85Sr_0.15Zr_0.1Ti_0.9O₃ (BSZT) ceramics. The ferroelectric hysteresis scaling relations for coercive field (E_c) and remnant polarization (P_r) as a function of temperature have been proposed. The power law temperature exponents based on scaling were systematically established for all the hysteresis parameters. The temperature dependent scaling of E_c and P_r at sintering temperature of 1400, 1425, 1450 and 1475°C yields E_cαT^0.43, E_cαT^0.84, E_cαT^0.50, E_cαT^0.37 and P_rαT^?1.73, P_rαT^?1.55, P_rαT^?1.73, P_rαT^?1.69 respectively. Additionally, the scaling relations for the samples sintered at 1450°C at different time intervals of 3, 4, 5 and 6 hrs were also established. Finally, to understand the domain dynamics, back switching polarization (P_bc) as a function of temperature (T) was also estimated by Arrhenius law and the average activation energy was evaluated.     

Duplex real-time PCR assay using SYBR Green to detect and quantify Malayan box turtle (Cuora amboinensis) materials in meatballs,burgers, frankfurters and traditional Chinese herbal jelly powder

The Malayan box turtle (Cuora amboinensis) (MBT) is a vulnerable and protected species widely used in exotic foods and traditional medicines. Currently available polymerase chain reaction (PCR) assays to identify MBT lack automation and involve long targets which break down in processed or denatured tissue. This SYBR Green duplex real-time PCR assay has addressed this research gap for the first time through the combination of 120- and 141-bp targets from MBT and eukaryotes for the quantitative detection of MBT DNA in food chain and herbal medicinal preparations. This authentication ensures better security through automation, internal control and short targets that were stable under the processing treatments of foods and medicines. A melting curve clearly demonstrated two peaks at 74.63 ± 0.22 and 78.40 ± 0.31°C for the MBT and eukaryotic products, respectively, under pure, admixed and commercial food matrices. Analysis of 125 reference samples reflected a target recovery of 93.25–153.00%, PCR efficiency of 99–100% and limit of detection of 0.001% under various matrices. The quantification limits were 0.00001, 0.00170 ± 0.00012, 0.00228 ± 0.00029, 0.00198 ± 0.00036 and 0.00191 ± 0.00043 ng DNA for the pure meat, binary mixtures, meatball, burger and frankfurter products, respectively. The assay was used to screen 100 commercial samples of traditional Chinese herbal jelly powder from eight different brands; 22% of them were found to be MBT-positive (5.37 ± 0.50–7.00 ± 0.34% w/w), which was reflected through the Ct values (26.37 ± 0.32–28.90 ± 0.42) and melting curves (74.63–78.65 ± 0.22°C) of the amplified MBT target (120 bp), confirming the speculation that MBT materials are widely used in Chinese herbal desserts, exotic dishes consumed with the hope of prolonging life and youth.     

Phenomenological understanding of flash sintering in MnCo2O4

The dual role of electric field in the flash sintering process of conducting MnCo₂O₄ is demonstrated. The flash and conventionally sintered MnCo₂O₄ samples produced at different temperatures are characterized using energy dispersive X-ray and micro-Raman spectroscopy to elucidate the micro-level spatial distribution of evolved phases. Raman signal mapping over the two ways sintered samples exposes differently grown areas of cobalt oxide based secondary phase. Electrical conductivity of conventionally sintered sample is recorded as a function of temperature and E-field and is utilized to discover the charge carrier activation mechanism during the flash effect. The conductivity before the flash-onset is shown to be comparable to that occurs by Poole-Frenkel effect and Phonon-assisted tunneling i.e. by the mechanism that occurs before the dielectric breakdown of semiconductors and insulators. The observed results, finally, confirm that catalyst like drift action of E-field on cobalt oxide formation is responsible for enhancement in the flash-sintering.     

Heat and mass transfer in MHD boundary layer flow of a second-grade fluid past an infinite vertical permeable surface

Heat and mass transfer of non-Newtonian fluids is increasingly being studied by researchers due to its applications in many branches of science and engineering, such as metallurgical processes, polymer extrusion, glass blowing, crystal growing, and so forth. The present work is mainly concerned with the unsteady laminar magnetohydrodynamic flow of a heat-generating or absorbing second-grade fluid past an infinite vertical porous plate. The nondimensional governing equations are solved for the best analytical solution. Results for various flow characteristics are presented through graphs and tables delineating the effect of various parameters characterizing the flow. For engineering interest, the shear stresses, Nusselt number, and Sherwood number are computed and exchanged of views with reference to the important parameters. Our analysis explored that the influences of a chemical reaction and fluid oscillations reduced the concentration distribution in the entire liquid region. The rotation effect decreases the shear stress, whereas it is augmented through an increase in the permeability of porous medium and second-grade fluid parameters' impact.     

New antimicrobial polyurea: Synthesis,characterization, and antibacterial activities of polyurea‐containing thiosemicarbazide–metal complexes

A novel class of polymer–metal complexes was prepared by the condensation of a polymeric ligand with transition‐metal ions. The polymeric ligand was prepared by the addition polymerization of thiosemicarbazides with toluene 2,4‐diisocyanate in a 1 : 1 molar ratio. The polymeric ligand and its polymer–metal complexes were characterized by elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, and ¹³C‐NMR and ¹H‐NMR spectroscopy. The geometries of the central metal ions were determined by electronic spectra (UV–visible) and magnetic moment measurement. The antibacterial activities of all of the synthesized polymers were investigated against Bacillus subtilis and Staphylococcus aureus (Gram positive) and Escherichia coli and Salmonella typhi (Gram negative). These compounds showed excellent antibacterial activities against these bacteria with the spread plate method on agar plates, and the number of viable bacteria were counted after 24 h of incubation period at 37°C. The antibacterial activity results revealed that the Cu(II) chelated polyurea showed a higher antibacterial activity than the other metal‐chelated polyureas. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008