Oscillatory behavior of the magnetic properties of Nd–Fe–B films with Mo and Mo–Cu additions

A series of Ta/NdFeB/Ta thin films with Mo and Mo–Cu additions embedded by alloying and by stratification have been prepared by r.f. sputtering. The influence of additions, their embedding mode, and annealing temperature on the structural and magnetic behavior of Ta/NdFeB/Ta thin films is presented. The use of additions of Mo and Mo–Cu leads to refined grain structure and improvement in the hard magnetic characteristics of Ta/NdFeB/Ta thin films. The Ta/[NdFeBMo(540 nm)/Ta films and Ta/[NdFeB(180 nm)/MoCu(dnm)] × n/Ta multilayer films present enhanced coercivities and M_r/M_s ratios in comparison with the Ta/NdFeB(540 nm)/Ta films. The stratification of Ta/NdFeB/Ta thin films with Mo–Cu interlayers leads to an oscillatory behavior of hard magnetic characteristics of the Ta/[NdFeB(180 nm)/MoCu(dnm)] × n/Ta multilayer films, when the thickness, d, of Mo–Cu interlayers varies by increments of 1 nm. When the thickness of Mo–Cu interlayers varies by increments of 2 nm the oscillatory behavior of the magnetic characteristics is not revealed. For a thickness of the Mo–Cu interlayer of 3 nm in the Ta/[NdFeB(180 nm)/MoCu(3 nm)] × 3/Ta thin films annealed at 650 °C, the c-axis of part of the hard magnetic Nd₂Fe₁₄B grains is oriented out-of-plane.     

Investigation on the mixture formation,combustion characteristics and performance of a Diesel engine fueled with Diesel,Biodiesel B20 and hydrogen addition

An experimental and numerical study was performed to investigate the impact of Biodiesel B20 (blends 20% Rapeseed methyl ester with 80 % Diesel volumetric fraction) and different energetic fractions of hydrogen content (between 0 and 5%) on the mixture formation, combustion characteristics, engine performance and pollutant emissions formation. Experiments were carried out on a tractor Diesel engine, four-cylinders, four-stroke, 50 kW/2400 rpm, and direct injection. Simulations were conducted using the AVL codes (HYDSIM and BOOST 2013). Simulation results were validated against experimental data, by comparing the inline pressure, needle lift, in-cylinder pressure curves for Biodiesel B20 and pure Diesel fuels at 1400 rpm and 2400 rpm, respectively, under full load operating conditions. Good agreement with a maximum of 2.5% relative deviation on the peak results revealed that overall operation conditions Biodiesel B20 provides lower engine performance, efficiency, and emissions except the NOx which are slightly increased. The Biodiesel B20 has shorter ignition delay. By hydrogen addition to B20 with aspiration of the intake air flow the CO emissions, smoke, and total unburned hydrocarbon emissions THC decreased, while the NOx kept the same increasing trend for 1400 rpm and has not quite apparent trend for 2400 rpm. The enrichment by hydrogen of Diesel and B20 fuels has not a significant effect on ignition delay.     

Thermal conductivity of polyimide/boron nitride nanocomposite films

The thermal conductivity of polyimide/boron nitride (PI/BN) nanocomposite thin films has been studied for two sizes of BN nanofillers (40 and 120 nm) and for a wide range of content. A strong influence of BN particle size on the thermal conduction of PI has been identified. In the case of the largest nanoparticles (hexagonal‐BN), the thermal conductivity of PI/h‐BN (120 nm) increases from 0.21 W/mK (neat PI) up to 0.56 W/mK for 29.2 vol %. For the smaller nanoparticles (wurtzite‐BN), PI/w‐BN (40 nm), we observed two different behaviors. First, we see a decrease until 0.12 W/mK for 20 vol % before increasing for higher filler content. The initial phenomenon can be explained by the Kapitza theory describing the presence of an interfacial thermal resistance barrier between the nanoparticles and the polymer matrix. This is induced by the reduction in size of the nanoparticles. Modeling of the experimental results allowed us to determine the Kapitza radius a_K for both PI/h‐BN and PI/w‐BN nanocomposites. Values of a_K of 7 nm and >500 nm have been obtained for PI/h‐BN and PI/w‐BN nanocomposite films, respectively. The value obtained matches the Kapitza theory, particularly for PI/w‐BN, for which the thermal conductivity is expected to decrease compared to that of neat PI. The present work shows that it seems difficult to enhance the thermal conductivity of PI films with BN nanoparticles with a diameter <100 nm due to the presence of high interfacial thermal resistance at the BN/PI interfaces. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42461.     

Upon the characterization of semi-synthetic hydrogels based on poly (NIPAM) inserted onto collagen sponge

The preparation of a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto a collagen porous membrane, it was previous presented. The synthesis of the hydrogels was performed through radical copolymerization of N-isopropyl acrylamide (NIPAM) with diethylene glycol diacrylate (DEGDA) also as crosslinking agent, using ammonium persulfate as initiator and N,N,N′,N′-tetramethylethylene diamine activator, and it was achieved in the presence of the collagen matrix. In this paper the thus prepared hydrogels are characterized by Differential Scanning Calorimetry, Scanning Electron Microscopy and for their swelling capacities. A kinetic model was studied to investigate the swelling mechanism of the semi-interpenetrated polymeric network. The swelling behavior was found dependent on the hydrogel composition and to the external stimuli such as temperature and pH of environment. This manner of acting recommends these materials as smart materials with potential applications in tissue engineering and pharmaceutical field as for example bioproducts carrier matrices.     

Magnetic composites based on bovine serum albumin and poly(aspartic acid)

In this investigation, magnetic polymer composites were developed by using a magnetic field‐assisted strategy. To create the composite, an interpolymeric complex based on bovine serum albumin and poly(aspartic acid) used as a polymer matrix was mixed with pre‐synthesized magnetite nanoparticles and then exposed to a high‐frequency magnetic field. The formation of such composite was confirmed by FTIR‐spectra, scanning electron micrographs, dynamic light scattering measurements, and magnetic susceptibility analysis. The results revealed that the materials have a superparamagnetic behavior and an average hydrodynamic size ranging from 220 to 580 nm. The polymer matrix improved the colloidal stability of the magnetic filler. The proposed composites are expected to be promising candidates for biomedical applications, such as drug delivery systems. POLYM. ENG. SCI., 59:1409–1415 2019. © 2019 Society of Plastics Engineers     

Case study: an intelligent decision support system

Information technology applications that support decision-making processes and problem-solving activities have proliferated and evolved. Distributing used cars to various automobile auctions is a complicated problem with multiple variables. We developed a software system to address these complexities and implemented it on a real distribution problem for a large car manufacturer. The system detects data trends in a dynamic environment, incorporates optimization modules to recommend a near-optimum decision, and includes self-learning modules to improve future recommendations. A software system that combines prediction, optimization, and adaptation techniques has generated impressive profits for a large auto manufacturer.     

Compatibility of polystyrene/polyolefin blends containing compatibilizing agents, 2. Extraction behavior

Polystyrene (PS)/polyolefin (PO) blends in various mixing ratios compatibilized by a triblock copolymer polystyrene‐block‐poly(ethene‐co‐butylene)‐block‐polystyrene (SEBS) and a diblock copolymer polystyrene‐block‐poly(ethene‐co‐propene) (SEP) and subsequently γ‐irradiated were prepared. The blends have been subjected to extraction in different solvents (chloroform or toluene) for various periods of time to obtain porous films. The efficiency of the extraction and the morphology of the films have been assessed by infrared spectrometry (IR), optical and electronic microscopy, differential scanning calorimetry (DSC) and thermogravimetry (TG); glass transition, melting heat, thermal stability, overall kinetic parameters and weight losses have been evaluated. The extraction behavior is close related to compatibility of the components, so on the base of the obtained results optima compatibility ratios have been established.     

Transient thermal analysis of an ACF package assembly process

Transient thermal simulation was performed to analyze thermal response of the assembly process for a package using anisotropic conductive film (ACF). The main purpose of the study is to simulate the actual assembly and manufacturing process, in order to provide a first-hand approximation and insight of the thermal behavior of the package and ACF film during the process. Two assembly processes were modeled: a simplified process where the package was fixed at two different temperatures during assembly, and a detailed process where the package experienced a ramping heating process, followed by a constant temperature curing process. A full convection-conduction case was conducted first. The results indicate a weak hydrodynamic field and radiation effects, hence for computational purposes (reduced CPU time), it was decided to model the process using a conduction-only investigation. Results from the detailed process modeling indicated that during the initial ramping, within 0.02 s, the die and nozzle head experienced a small temperature drop due to the cooling effect of the ACF material and substrate. The ACF material also displayed a steep increase in temperature after contacting the die, followed by a short decay, then ramped up again. At the end of the 10-s ramping process, the ACF reached a temperature of almost 203°C, while the die was at 206°C. During the 5 s of curing, all parts reached steady state in less than 2 s     

A Smart Procedure for the Femtosecond Laser-Based Fabrication of a Polymeric Lab-on-a-Chip for Capturing Tumor Cell

Rapid prototyping methods for the design and fabrication of polymeric labs-on-a-chip are on the rise, as they allow high degrees of precision and flexibility. For example, a microfluidic platform may require an optimization phase in which it could be necessary to continuously modify the architecture and geometry; however, this is only possible if easy, controllable fabrication methods and low-cost materials are available. In this paper, we describe the realization process of a microfluidic tool, from the computer-aided design (CAD) to the proof-of-concept application as a capture device for circulating tumor cells (CTCs). The entire platform was realized in polymethyl methacrylate (PMMA), combining femtosecond (fs) laser and micromilling fabrication technologies. The multilayer device was assembled through a facile and low-cost solvent-assisted method. A serpentine microchannel was then directly biofunctionalized by immobilizing capture probes able to distinguish cancer from non-cancer cells without labeling. The low material costs, customizable methods, and biological application of the realized platform make it a suitable model for industrial exploitation and applications at the point of care.