Enhanced luminescence of lanthanide complexes by silver nanoparticles for ciprofloxacin determination

We present the enhancement of luminescence of europium complex, Eu(3+)-ciprofloxacin (CIP), in the presence of silver nanoparticles (Ag NPs) for the CIP determination. The increment of the luminescence intensity of the Eu(3+)-CIP complex with Ag NPs was obtained due to the transfer of resonance energy to the fluorophores through the interaction of the excited-state fluorophores and surface plasmon electron in the metal nano surface. The luminescence intensity of Eu3+ was enhanced by complexation with CIP at 614 nm after excitation at 373 nm corresponding to the 5D0-7F2 transitions of Eu3+ ion. Based on the above phenomenon, a sensitive and rapid spectrofluorimetric method has been developed for the CIP determination. Linearity of the calibration curve was obtained in the range of 2.0 x 10(-10)-1.0 x 10(-8) g mL(-1) with correlation coefficient of 0.9992. The limit of detection of CIP was found to be 1.9 x 10(-11) g mL(-1) with the relative standard deviation (RSD) of 1.19% for 5 replicate measurements of 5.0 x 10(-7) g mL(-1) of CIP. The present method has been successfully applied for CIP determination in pharmaceutical and biological samples.     

A vehicle front frame crash design optimization using hole-type and dent-type crush initiator

The hole-type crush initiators according to various ratios of thickness to width (t/b) were studied. And the approximate equation to quickly predict the optimum size of the crush initiator by impact velocity for each ratio of thickness to width was introduced. Also, the simple rectangular and circular dent-type crush initiators of a front frame with non-uniform closed-hat section in a vehicle were studied for frontal crashworthiness according to various ratios of thickness to width (t/b).The optimum size and dent depth of a crush initiator, whose location is decided by the homogenization method, were studied by using design of experiment and response surface method. Design analysis results of the dent-type crush initiators were compared with those of the hole-type crush initiator of the same size as the dent-type crush initiators.The rectangular dent-type crush initiator absorbed more crash energy than the circular dent-type crush initiator. Dynamic mean crushing loads of a rectangular dent-type crush initiator of size equal to that of the hole-type crush initiator designed by the homogenization method were similar to those of the hole-type crush initiator.The trend curve of the optimum size rectangular dent-type crush initiator design is similar with the trend curve of hole-type crush initiator design. Therefore, the approximate equation used to predict the optimum size of the hole-type crush initiator can be applied to find the optimum size of the rectangular dent-type crush initiator.     

On identifying and estimating the cycle time of product development process

A timely introduction of a new product has become invaluable to the firm since the competitors are capable of introducing new or similar products once the driving technology becomes available. In order to generate a high profit from a new product, managers in other departments, such as marketing and production, have to plan ahead of time so that a seamless series of operations can be executed from product development to mass production. Needless to say, a competitive edge is given to the firm with better knowledge on product development process. Such knowledge, nonetheless, is not easy to acquire since a typical product development process is a complex network of many relationships among activities, which we call patterns. In addition to its complex topology, the product development process is often uncertain, iterative, and evolving over time; therefore, even studying individual islands of relationships (patterns) is challenging. Although there were some existing models that shed lights on some of these patterns, very little has been done to systematically analyze the product development process as a whole. In this paper, we develop analytical models that capture essential properties, including uncertainty, iteration and evolution, and estimate the cycle time of each pattern. With our proposed models, the cycle time of a set of patterns (or the whole product development process) can be effectively estimated. As demonstrated in a case study, our model provides valuable insights on how product development process progresses over time, while the corresponding time estimate can help managers to set appropriate manufacturing and marketing strategies.     

Nanoporous phloroglucinol-formaldehyde carbon aerogels for electrochemical use

Phloroglucinol-Formaldehyde (PF) organic aerogels were prepared from alcoholic sol-gel polycondensation of phloroglucinol with formaldehyde using KOH as base catalyst and followed by supercritical drying with carbon dioxide. Subsequent pyrolysis of PF organic aerogel under He flow produced carbon aerogels. Textural properties of PF organic and carbon aerogels were obtained by nitrogen adsorption-desorption, and their specific capacitances were measured by cyclic voltammetry. The resultant PF carbon aerogels were mostly mesoporous material with high surface area. The nanoporous structure and electrochemical behavior of PF carbon aerogels could be controlled by the molar ratio of phloroglucinol to catalyst (P/C) and carbonization conditions. PF carbon aerogels exhibited the highest surface area in excess of 1,200 m²/g and specific capacitance up to 250 F/g in comparison to other carbons.     

Attachment State of Mind, Learning Dispositions, and Academic Performance During the College Transition.

The purpose of this study was to examine the relation among attachment state of mind, students' learning dispositions, and academic performance during the college transition. Sixty-two students were involved in a short-term longitudinal study and were interviewed with the Adult Attachment Interview. Students' learning dispositions were assessed at the end of high school (Time 1) and halfway through their 1st semester in college (Time 2). Academic records were collected at Time 1 as well as at the end of the 1st, 2nd, and 3rd college semesters. Autonomous students showed better learning dispositions throughout the transition and were less likely than dismissing and preoccupied students to experience a decrease in these dispositions between Time 1 and Time 2. In addition, dismissing students obtained the lowest average of grades in college, and this association was mediated by changes in quality of attention during the transition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Incorporation of Aluminum into C–S–H Structures: From Synthesis to Nanostructural Characterization

C–A–S–H (C=CaO, A=Al₂O₃, S=SiO₂, H=H₂O in cement nomenclature) phases have been synthesized from CaO, SiO₂, and AlNaO₂. The initial CaO/SiO₂ (C/S_initial) ratios varied from 0.8 to 1.5 and the initial Al₂O₃/SiO₂ (A/S_initial) ratio was set to 0.1. Samples were characterized by X-ray diffraction and chemical analyses of their equilibrium solutions. This paper describes experiments using a low-voltage scanning transmission electron microscopy (STEM-in-SEM) imaging system that allows transmission observations in an environmental scanning electron microscope. Observations of the nanostructure were also performed by transmission electron microscopy (TEM). Two types of morphologies were clearly observed: fine fibrillar aggregates and small plates, the latter being particularly sensitive to beam damage. Despite their different appearance, both of these phases were amorphous, and the small plates were richer in aluminum. The fraction of the small plate phase increased with the C/S_initial ratio. TEM interpretations showed that C–A–S–H phases were not stable under the electron beam and high-magnification observations could significantly modify their structure. Images and chemical analyses acquired with STEM-in-SEM appeared as valuable sources of information because they offered a large observation field comparable to a transmission electron microscope and better magnification resolution than a classical scanning electron microscope.     

Development of linked analysis system for PWR severe accidents utilizing RELAP5 and MAAP4

The purpose of this study is to develop a severe accident (SA) analysis method that is more reliable thorough transferring the physical status of the plant predicted by RELAP5 computer code to MAAP4 computer code. The methodology of the linkage analysis is developed and the criterion of linkage time is suggested to utilize the RELAP5 thermal–hydraulic calculation to the maximum degree possible and thereby guarantee the continuity of calculation for hydrogen generation. The MAAP4 calculations after data transfer show the physically proper results based on RELAP5 data. Comparison with other code results for TMI-2 accident reveals that the result from the RELAP5–MAAP4 linked analysis lay in the span given by a number of results of TMI calculation from other SA code systems. The results of this study are expected to improve the SA analysis methodology by analyzing an SA scenario with more reliable thermal–hydraulic initial conditions.     

Simulation of water flows in multiple columns with small outlets

High-pressure die casting such as thixocasting and rheocasting is an effective process in the manufacturing automotive parts. Following the recent trend in the automotive manufacturing technologies, the product design subject to the die casting becomes more and more complex. Simultaneously the injection speed is also designed to be very high to establish a short cycletime. Thus, the requirement of the die design becomes more demanding than ever before. In some cases the product’s shape can have multiple slender manifolds. In such cases, design of the inlet and outlet parts of the die is very important in the whole manufacturing process. The main issues required for the qualified products are to attain gentle and uniform flow of the molten liquid within the passages of the die. To satisfy such issues, the inlet cylinder (‘bed cylinder’ in this paper) must be as large as possible and simultaneously the outlet opening at the end of each passage must be as small as possible. However these in turn obviously bring additional manufacturing costs caused by re-melting of the bed cylinder and increased power due to the small outlet-openings. The purpose of this paper is to develop effective simulation methods of calculation for fluid flows in multiple columns, which mimic the actual complex design, and to get some useful information which can give some contributions to the die-casting industry. We have used a commercial code CFX in the numerical simulation. The primary parameter involved is the size of the bed cylinder. We will show how the very small opening of the outlet can be treated with the aid of the porous model provided in the code. To check the validity of the numerical results we have also conducted a simple experiment by using water.     

Friction of Undulated Surfaces Coated with MoS2 by Pulsed Laser Deposition

Solid lubricants such as molybdenum disulfide can provide very low friction, but their effectiveness especially in the geometrically constrained sliding pairs is limited by plowing of coated surfaces by wear particles. Even in the presence of solid lubricants wear particles cause higher friction by plowing the interface. To minimize plowing, undulated surfaces with microgrooves perpendicular to the sliding direction can be used to trap wear particles. Smooth and undulated stainless steel surfaces were coated with molybdenum disulfide by pulsed laser deposition (PLD) and friction tested. Under identical test conditions, the friction coefficient of coated undulated surfaces is between 20–40 percent lower than that of coated smooth surfaces. The friction coefficient of undulated uncoated surfaces is about 100–350 percent less than that of smooth uncoated surfaces. Moreover, the entrapment of wear particles at the interfaces of geometrically constrained bearings may lead to seizure even when bearing surfaces are coated with solid lubricants. The use of undulated surf aces on these sliding systems has shown improved operating time and a reduced maintenance cycle.