Surface topography and tribological properties of coatings prepared from microparticle size polyurethane dispersions studied by atomic force microscopy

The surface topography and mechanical properties of coatings prepared using large particle size polyurethane dispersions (PUD) are investigated using atomic force microscopy (AFM) imaging, AFM-based force measurements, and friction force microscopy. PUD coatings, which are prepared from dispersions containing particles of micron size, have surface roughness of 250–300 nm and waviness of 2.5–3 μm resulting from the particle size. The surface moduli of the PUD coatings are varied by tuning the ratio of hard-to-soft segmentation in the polyurethanes and are found to be between 40 and 100 MPa. The friction coefficient obtained in the study is found to be correlated with both the surface modulus of the coatings and the adhesion between the probe and the samples and is well in line with the perceived feel of an experienced human panel. The data are very well behaved and clearly show the utility of this technique in characterizing these types of surfaces.     

CHARACTERISTICS OF MICROCUTTING FORCE VARIATION IN ULTRAPRECISION DIAMOND TURNING

An investigation of the characteristics of microcutting forces in diamond turning of crystalline materials is presented. The characteristics of the cutting forces were extracted and analyzed using statistical and spectrum analysis methods. A series of cutting experiments were done on a copper alloy and copper single crystals with different crystallographic orientations. Experimental results indicate that there exists a dominant frequency component and a periodicity of fluctuation of the cutting forces per workpiece revolution in the diamond turning of a single crystal material. The periodicity is closely related to the crystallographic orientation of the material being cut. As the depth of cut increases, the influence of crystallographic orientation of the single-crystal materials on microcutting forces is found to be more pronounced. Moreover, the cutting force ratio between the mean thrust force and the mean cutting force is found to vary with the depth of cut, and a large ratio was observed at a small depth of cut. These findings help to explain quantitatively the periodic fluctuations of microcutting forces (and hence the materials-induced vibration) in ultraprecision diamond turning, which are not encountered in conventional machining.     

Catalytic wall reactor: Catalytic coatings of stainless steel by VOx/TiO2 and Co/SiO2 catalysts

Catalytic wall (structured) reactors and structured supports are suitable to study the catalytic properties of nanosized materials. The coating of metallic (aluminum and stainless steel) plates by thin layers of active phase is presented in two cases, VO_x/TiO₂ and Co/SiO₂, catalysts used in the oxidative dehydrogenation (ODH) of propane and in Fischer–Tropsch synthesis (FTS) of clean fuels, respectively. The preparation of coated plates and their characterisation by various methods of physicochemical analysis are described. Both chemical and physical methods were used for coating. VO_x/TiO₂ layers were obtained by grafting of Ti (on Al or stainless-steel plates) and V (on TiO₂) alkoxides and use of sol–gel media or suspension. A silica primer was deposited (on stainless-steel plate) by plasma-assisted chemical vapour deposition (PACVD) onto which Co oxide and silica were coprecipitated from sol–gel. The catalytic experiments in the respective reactions were carried out in special plate reactors and compared with those of catalytic powders. The study shows that the coating of a metallic substrate by a catalyst is not straightforward and requires specific studies dealing with both chemistry (chemical affinity between substrate and catalytic layers) and catalytic engineering (catalytic performance in taylor-made reactors).     

Thermal cracking of acid tars to asphalts as a process for utilization of refinery wastes

The feasibility of manufacture of asphaltic materials by means of the thermal cracking of acid tars was shown and a corresponding bench-scale unit was designed. The dependence of the viscosity characteristics of the obtained compositions on the temperature and time of the process was examined using the penetration technique.     

Radiation shielding of spacecraft in manned interplanetary flights.

During the interplanetary flights the crewmembers will be exposed to cosmic ray radiation with great risk for their health. The absorbed dose due to CR depends on the galactic (GCR) or solar (SCR) origin. GCRs are isotropic and relatively high in energy and deliver a dose nearly constant with time that can be reduced only by means of "heavy" passive protection. The outer walls of the spacecraft usually shield the SCRs up to a few tens of MeV, but during some exceptional solar bursts, a great number of particles, mainly protons, are ejected at higher energies. In this case the dose delivered in a few hours by a solar burst can easily exceed 1 year cumulated dose by GCRS. The high-energy component of SCRs is quasi-directional so that a shielding system based on a superconductive magnetic lens can reduce the daily dose of SCRs to the level delivered by GCRS.     

Sourdough fermented by Lactobacillus plantarum FST 1.7 improves the quality and shelf life of gluten-free bread

Lactobacillus plantarum FST 1.7 has been recently shown to produce antifungal compounds, which improve the shelf life of wheat bread. In the present study, this strain was investigated for its ability to improve the quality and shelf life of gluten-free bread. Effects of incorporation of sourdough fermented by strain FST 1.7 into a gluten-free bread mixture were compared to those obtained with sourdough fermented by the non-antifungal strain Lactobacillus sanfranciscensis TMW 1.52 as well as to those obtained with chemically or non-acidified batters. Fundamental rheological tests revealed that the addition of sourdough to the gluten-free mix led to an increase in firmness and increase in elasticity overtime (P < 0.05). Bread characteristics such as pH, total titratable acidity, and crumb hardness (5-day storage) were evaluated. Results showed that the biologically acidified gluten-free breads were softer after 5 days than the chemically acidified gluten-free breads (P < 0.001). Antifungal challenge tests employing conidial suspensions of Fusarium culmorum were carried out using the sourdough, non-acidified batter and bread. The rate of mould growth for the fungal species used was retarded by L. plantarum FST 1.7 when compared to the controls. In conclusion, the results of this study indicate that L. plantarum FST 1.7 can be used to produce gluten-free bread with increased quality and shelf life.     

Surface-acoustic-wave pulse transducer

Short pulses of surface acoustic waves are launched efficiently by an inline assembly of several finger-pair interdigital transducers, which are connected to successive taps of an electrical delay line, where the electrical time lag between two taps is equal to the acoustic delay between corresponding transducers.     

Characteristics of Low-fat Beef Patties Formulated with Carbohydrate-Lipid Composites

ABSTRACT: Chemical, physical, and sensory characteristics of low-fat beef patties containing carbohydrate-lipid composites (CLCs) were compared with those of all-beef patties. The CLC gels contained high-amylose cornstarch, maltodextrins, and canola oil. CLC patties had higher moisture, cooking yield, and fat retention than 20%-fat control patties. CLCs improved tenderness and juiciness and decreased cohesiveness of low-fat beef patties compared with 10%-fat control patties. Despite differences in CLC gel firmness, patties made with CLC gels containing corn, potato, and tapioca maltodextrins had similar physical and sensory properties. These results suggest that CLC gels perform well as a partial fat replacer in beef patties while providing flexibility in gel firmness selection.     

Use of Volatiles as Indicators of Lipid Oxidation in Muscle Foods

Lipid oxidation has long been recognized as a leading cause of quality deterioration in muscle foods and is often the decisive factor in determining food product storage life. Lipid oxidation generates a number of products, including volatile compounds, which are the major contributors to the development of rancid off‐flavors and odors. Over the years, methodologies have been developed to quantify lipid oxidation products in muscle foods. This article reviews the analytical methods that have been used to quantify volatile compounds as indicators of lipid oxidation in muscle foods. The sampling methodologies of distillation/solvent extraction and headspace analysis, and isolation methods associated with gas chromatographic (GC) and high‐performance liquid chromatography (HPLC) analyses are discussed. Within gas chromatographic methodologies, headspace (HS) sampling (static HS, dynamic purge‐and‐trap HS techniques, and solid‐phase microextraction [SPME]) are addressed.     

Luminescence properties of the Langmuir-Blodgett film of terbium(III) stearoylanthranilate

Terbium(III) stearoylanthranilate has been prepared as a high property Z-type Langmuir-Blodgett (LB) film on various substrates by a vertical transfer process. The UV-visible absorption spectra and the low angle X-ray diffraction peaks have been collected in order to investigate the molecular arrangement and aggregation in the LB films. The average molecular orientation in multilayer stacking was determined by Attenuated Total Reflection Spectroscopy. The influence of the chemical environment of terbium within the LB films on the luminescence properties has been discussed.