Gas impregnation of titanium alloys in heat treatment in a static atmosphere of argon

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 23, No. 4, pp. 38–43, July–August, 1987.     

Quantification of diacylglycerol species from cellular extracts by electrospray ionization mass spectrometry using a linear regression algorithm

Diacylglycerols (DAGs) play significant roles in both intermediate metabolism and signal transduction. These lipid species are second messengers involved in modulating a plethora of cellular processes. Evaluation of DAG species concentrations has been hampered by the lack of a reliable method for molecular species analysis within a complex mixture of cellular lipids. We describe a new method for quantitative analysis of DAG species from complex biological extracts based on positive mode electrospray ionization mass spectrometry without prior derivatization. Quantification is achieved using internal standards and calibration curves constructed by spiking cell extracts with different concentrations of DAG species containing various acyl chain lengths and degrees of unsaturation. The new mass spectral data processing algorithm incorporates a multiple linear regression model including a factor accountable for possible interactions between experimental preparations and the slope of the curve for the standards, allowing the examinations of the effects of sample origin conditions (such as cell types, phenotypes, etc.) and instrument variability on this slope. Internal standards provide a basis for quantification of 28 DAG molecular species detected in RAW 264.7 cells after stimulation of a G-protein coupled receptor with platelet activating factor. This method displays excellent reproducibility over the established range of concentrations with variations of < or =10% and is highly sensitive with a detection limit of 0.1-0.4 pmol/microL depending upon acyl chain composition. We have shown differential effects on various DAGs in response to a ligand which illustrates the importance of examining lipids at the molecular species level rather than as a single homogeneous entity.     

Temperature distribution in dental tissue after interaction with femtosecond laser pulses

Algebraic and numerical solutions are presented of the temperature rise in dental tissue due to interaction with ultrashort optical radiation. Results of the studies with femtosecond laser pulses show agreement between theory and experiment. A temperature rise of typically 5 K is found for a 40 millisecond train of 7 nJ, 70 fs laser pulses at a repetition rate of 80 MHz. The peak irradiance in our experimental studies was limited to 3x10(6) W/cm(2). Applications include photoacoustic imaging and tomography of dental tissue.     

Transformation of Cellulose via Two-Step Carbonization to Conducting Carbonaceous Particles and Their Outstanding Electrorheological Performance

In this study, cellulose was carbonized in two-steps using hydrothermal and thermal carbonization in sequence, leading to a novel carbonaceous material prepared from a renewable source using a sustainable method without any chemicals and, moreover, giving high yields after a treatment at 600 °C in an inert atmosphere. During this treatment, cellulose was transformed to uniform microspheres with increased specific surface area and, more importantly, conductivity increased by about 7 orders of magnitude. The successful transition of cellulose to conducting carbonaceous microspheres was confirmed through SEM, FTIR, X-ray diffraction and Raman spectroscopy. Prepared samples were further used as a dispersed phase in electrorheological fluids, exhibiting outstanding electrorheological effects with yield stress over 100 Pa at an electric field strength 1.5 kV mm⁻¹ and a particle concentration of only 5 wt%, significantly overcoming recent state-of-the-art findings. Impedance spectroscopy analysis showed clear interfacial polarization of this ER fluid with high dielectric relaxation strength and short relaxation time, which corresponded to increased conductivity of the particles when compared to pure cellulose. These novel carbonaceous particles prepared from renewable cellulose have further potential to be utilized in many other applications that demand conducting carbonaceous structures with high specific surface area (adsorption, catalyst, filtration, energy storage).     

On the Controlled Loading of Single Platinum Atoms as a Co-Catalyst on TiO2 Anatase for Optimized Photocatalytic H2 Generation

Single-atom (SA) catalysis is a novel frontline in the catalysis field due to the often drastically enhanced specific activity and selectivity of many catalytic reactions. Here, an atomic-scale defect engineering approach to form and control traps for platinum SA sites as co-catalyst for photocatalytic H₂ generation is described. Thin sputtered TiO₂ layers are used as a model photocatalyst, and compared to the more frequently used (001) anatase sheets. To form stable SA platinum, the TiO₂ layers are reduced in Ar/H₂ under different conditions (leading to different but defined Ti³⁺-O_v surface defects), followed by immersion in a dilute hexachloroplatinic acid solution. HAADF-STEM results show that only on the thin-film substrate can the density of SA sites be successfully controlled by the degree of reduction by annealing. An optimized SA-Pt decoration can enhance the normalized photocatalytic activity of a TiO₂ sputtered sample by 150 times in comparison to a conventional platinum-nanoparticle-decorated TiO₂ surface. HAADF-STEM, XPS, and EPR investigation jointly confirm the atomic nature of the decorated Pt on TiO₂. Importantly, the density of the relevant surface exposed defect centers—thus the density of Pt-SA sites, which play the key role in photocatalytic activity—can be precisely optimized.     

Pressure-affected flow properties of powder injection moulding compounds

The effect of pressure and temperature on the flow properties of the materials intended for Powder Injection Moulding (PIM) technology was studied using a single-piston capillary rheometer modified by additional backpressure chamber. The influence of pressure and temperature on shear viscosity has been quantified through pressure and temperature sensitivity coefficients derived from Carreau-Yasuda model. The temperature sensitivity of the 50 vol.% compound based on cemented carbide powder is lower than that of pure polymeric binder, and it varies only slightly with pressure. In contrast, the pressure sensitivity of compounds was found to be higher than that of pure polyolefin binder, and it is decreasing function of temperature. In addition, it is shown that temperature sensitivity of binder, which is considerably enhanced by pressure (in contrast to the PIM demands), cannot be determined as being equal to the properties of particular binder components.     

Combined power and inter-cell interference control for LTE based on role game approach

In this paper the application of Role Game Theory to Power Control (PC) and Inter-Cell Interference Control (ICIC) for Long Term Evolution (LTE) is considered. The authors propose an approach based on defining different roles of the users within a cell of the LTE network. The main idea is to apply different methods and algorithms for PC and ICIC depending on the classified by role subscriber. Such an approach will give the possibility for flexible application and combination of different PC and ICIC methods for achieving better performance.     

The Influence of Pectin from Apple and Gum Arabic from Acacia Tree on the Quality of Pizza

The aim of this work was to determine the effect of apple pectin and arabic gum on the organoleptic characteristics of pizza flans. Significant differences in the sensory characteristics, such as flavour and change during chewing as well as the quality between the pizza flan with the addition of hydrocolloids and the pizza flan without them were found out. The additions of hydrocolloids improve the quality and flavour of pizza flans. On the other hand, higher amounts of gum arabic from the acacia tree caused worse tenderness of the bakery product.      

Effects of Copper on the Hardenability of a Medium-Carbon Steel

Scrap-based steelmaking is gradually increasing the levels of residual copper present in modern steels. End-quench hardenability tests were conducted on medium-carbon steels containing up to 0.4 wt pct copper to evaluate if current methods are still accurate for predicting the ideal critical diameter as residual copper levels rise. The results indicate that copper’s contribution to hardenability, especially at lower concentrations, may be greater than conventional calculation methods indicate.     

Immobilization of bacteriocin nisin into a poly(vinyl alcohol) polymer matrix crosslinked with nontoxic dicarboxylic acid

This work is focused on novel methodology of poly(vinyl alcohol) crosslinking by non‐toxic dicarboxylic acid, glutaric acid. The cross‐linked system was used as a matrix for immobilization of bacteriocin nisin. Effect of the crosslinking degree on physico‐chemical, morphology, mechanical, and thermal properties of poly(vinyl alcohol) films were investigated by using swelling test, Fourier transform infrared spectroscopy, scanning electron microscopy, stress–strain analysis, differential scanning calorimetry, and thermogravimetry. Release profile of the nisin from the cross‐linked poly(vinyl alcohol) was studied by high performance liquid chromatography. Antibacterial activity of the prepared systems was tested by agar diffusion test and dilution and spread plate technique. Results showed suitability of glutaric acid as effective crosslinking agent of poly(vinyl alcohol) that acts synergistically with bacteriocin nisin against the tested Gram‐positive and Gram‐negative bacterial strains. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43674.