Study on the structure of mangrove polyflavonoid tannins with MALDI-TOF mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a suitable method for examining polyflavonoid tannin oligomers as it is capable to determine aspects of their oligomeric structure and characteristics, which are otherwise too difficult to determine by other techniques. It has been possible to determine by MALDI-TOF for Rhizophora apiculata mangrove polyflvonoid tannins that: (i) procyanidins oligomers formed by catechin/epicatechin, epigallocatechin, and epicatechin gallate monomers are present in great proportions; (ii) oligomers, up to nonamers, in which the repeating unit at 528–529 Da is a catechin gallate dimer that has lost both the gallic acid residues and an hydroxy group which are the predominant species; (iii) oligomers of the two types covalently linked to each other also occur. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of metal oxides on the microstructure of zinc ceramic

The effect of crystallization of ZnO on volt-ampere characteristics was investigated. It was shown that incorporation of Bi₂O₃, TiO₂, and SnO₂ causes crystal growth, while Sb₂O₅, CoO, and MnO slow crystal growth. The formation of a finely crystalline structure with thin layers of glass phase increases the volt-ampere characteristics. __________ Translated from Steklo i Keramika, No. 1, pp. 29–31, January, 2007.     

Photoluminescent enhancement of polyesters via photocrosslinking

A homologous series of soluble photoluminescent polyesters, namely poly{bis(4‐hydroxybenzylidene)acetone‐5‐(m‐alkyloxyisophthalate)}, PAI1‐PAI5 were designed and synthesized via polycondensation reaction. The branches of these polyesters consisted of flexible alkyloxy chains with different chain lengths in order to investigate their influence toward thermal stability as well as the photocrosslinking property. It was found that increasing length of the flexible chain would reduce the thermal stability of the polyesters. Irradiation of these polyesters under UV light induced photocrosslinking and showed fascinate enhancement in their photoluminescence property with greater emission intensity. This was evidenced visually from the transformation of a weak greenish blue emission to highly intense cloudy blue emission. The photocrosslinking system was further confirmed using spectroscopic methods. Morphology analysis using SEM showed that the photocrosslinked polyesters have a fiber‐like or thread‐like texture with more voids as compared to the virgin polyesters. This was because of the formation of cyclobutanes through photodimerization involving 2π + 2π cycloaddition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41504.     

Polarization-discrimination technique to maximize the lidar signal-to-noise ratio for daylight operations

The impact and potential of a polarization-selection technique to reduce the sky background signal for linearly polarized monostatic elastic backscatter lidar measurements are examined. Taking advantage of naturally occurring polarization properties in scattered skylight, we devised a polarization-discrimination technique in which both the lidar transmitter and the receiver track and minimize detected sky background noise while maintaining maximum lidar signal throughput. Lidar elastic backscatter measurements, carried out continuously during daylight hours at 532 nm, show as much as a factor of square root 10 improvement in the signal-to-noise ratio (SNR) over conventional unpolarized schemes. For vertically pointing lidars, the largest improvements are limited to the early morning and late afternoon hours, while for lidars scanning azimuthally and in elevation at angles other than vertical, significant improvements are achievable over more extended time periods with the specific times and improvement factors depending on the specific angle between the lidar and the solar axes. The resulting diurnal variations in SNR improvement sometimes show an asymmetry with the solar angle that analysis indicates can be attributed to changes in observed relative humidity that modifies the underlying aerosol microphysics and observed optical depth.     

Enhancement of boron removal in treatment of spent rinse from a plating operation using RO

Boron removal is a critical issue in the production of drinking water and of ultra-pure water in the electronics industry. Boron rejection in a RO process is typically in the range of 40-60%. The objective of this study was to distinguish the factor contributing to enhanced boron rejection in reclamation of a spent rinse stream from a plating operation. The effects of different known components used in the feed on boron removal were investigated in the laboratory. The results indicated that glycolic acid and antifoulants could not individually enhance boron rejection in a RO process. A high boron rejection of 95% was achieved as the concentration of iron in the feed was 10 times higher than that of boron, which might be due to formation of a complex between iron oxide and boron. The finding was confirmed in a pilot study.     

Rational Design of Nanoporous MoS2/VS2 Heteroarchitecture for Ultrahigh Performance Ammonia Sensors

2D transition metal dichalcogenides (TMDs) have received widespread interest by virtue of their excellent electrical, optical, and electrochemical characteristics. Recent studies on TMDs have revealed their versatile utilization as electrocatalysts, supercapacitors, battery materials, and sensors, etc. In this study, MoS₂ nanosheets are successfully assembled on the porous VS₂ (P‐VS₂) scaffold to form a MoS₂/VS₂ heterostructure. Their gas‐sensing features, such as sensitivity and selectivity, are investigated by using a quartz crystal microbalance (QCM) technique. The QCM results and density functional theory (DFT) calculations reveal the impressive affinity of the MoS₂/VS₂ heterostructure sensor toward ammonia with a higher adsorption uptake than the pristine MoS₂ or P‐VS₂ sensor. Furthermore, the adsorption kinetics of the MoS₂/VS₂ heterostructure sensor toward ammonia follow the pseudo‐first‐order kinetics model. The excellent sensing features of the MoS₂/VS₂ heterostructure render it attractive for high‐performance ammonia sensors in diverse applications.     

A new technique for the characterization of chaff elements

A new technique for the experimental characterization of electromagnetic chaff based on Inverse Synthetic Aperture Radar is presented. This technique allows for the characterization of as few as one filament of chaff in a controlled anechoic environment allowing for stability and repeatability of experimental results. This approach allows for a deeper understanding of the fundamental phenomena of electromagnetic scattering from chaff through an incremental analysis approach. Chaff analysis can now begin with a single element and progress through the build-up of particles into pseudo-cloud structures. This controlled incremental approach is supported by an identical incremental modeling and validation process. Additionally, this technique has the potential to produce considerable savings in financial and schedule cost and provides a stable and repeatable experiment to aid model valuation.     

A particle swarm approach for grinding process optimization analysis

Optimization is necessary for the control of any process to achieve better product quality, high productivity with low cost. The grinding of silicon carbide is not an easy task due to its low fracture toughness, therefore making the material sensitive to cracking. The efficient grinding involves the optimal selection of operating parameters to maximize the material removal rate (MRR) while maintaining the required surface finish and limiting surface damage. In this work, optimization based on the available model has been carried out to obtain optimum parameters for silicon carbide grinding via particle swarm optimization (PSO) based on the objective of maximizing MRR with reference to surface finish and damage. Based on statistical analysis for various constraint values of surface roughness and number of flaws, simulation results obtained for this machining process for PSO are comparatively better to genetic algorithm (GA) approach. In addition, the post-optimal robustness of PSO has also been studied. From simulation results together with the proposed robustness measurement method, it has been shown that PSO is a convergent stable algorithm.     

From ideals towards practice: paradigmatic mismatches and drifts in method deployment

There is considerable debate in the information systems literature on how systems development methods (SDMs) are used in practice. On one side are those who take the position that these methods are not used at all. The other side posits that SDMs are used but not in the manner intended by the method developers. In practice, SDMs are adapted and modified to meet project exigencies, which results in unique methods‐in‐use in each project. We subscribe to the latter view and extend the argument by proposing that SDM modifications happen due to mismatches between the paradigmatic values inherent in the SDM, the method users and the organizational context. Further, planned modifications themselves result in shifts of paradigmatic values inherent in the SDM. To examine our contention, we conduct a case study in which we trace an SDM from its development to its deployment and use in an organization. We show where the mismatches occurred and provide explanations for the mismatches. Our results indicate that paradigm differences explain most of the mismatches, and different factors contribute to the paradigm drifts simultaneously, even towards diverging orientations. We conclude that the true value of an SDM, in addition to its tool and technique use, is a basis for examining and self‐reflecting about paradigmatic values. This is an essential part of learning to develop systems.     

Cationic UV‐Curable Conductive Composites from Exfoliated Graphite

Electrically conductive, cationically UV‐cured composites were prepared using exfoliated graphite plates (EGP) with cycloaliphatic epoxy resin and polyalcohol binder system. Exfoliated graphite (EG) was obtained from natural flake graphite through chemical and thermal treatment. Sonication of EG in solvent produced EGP. Characterization of graphite samples by XRD showed structural similarity between original graphite and EGP. UV curing behavior was characterized using photoDSC. Electrical resistivity measurements of the composites as a function of EGP concentration showed that at low filler concentration the binder system can influence the electrical percolation behavior. Some formulations showed electrical percolation at less than 1 vol.‐% of EGP filler.