Influence of deep cryogenic treatment on the thermal decomposition of Fe–C martensite

The beneficial effects of deep cryogenic treatment (DCT) at temperatures close to ?180 °C on certain mechanical properties of steels are well known, although the metallurgical base mechanism of DCT still needs further clarification. In this study, the thermal decomposition of steel martensite (100Cr6) subjected to low-temperature soaking over different periods (SDCT = 5 min at ?180 °C, LDCT = 24 h at ?180 °C) is investigated by means of differential scanning calorimetry and dilatometry. The results were compared with those for the same conventionally quenched and tempered steel. Isochronal annealing experiments at different heating rates were performed, in order to highlight the main tempering stages and to obtain their relevant activation energies. DCT was clearly shown to lower the Ea of the pre-precipitation process more intensely than in the quenched steel. This result may probably be ascribed to an increased dislocation density and to the activation of the carbon segregation process in larger amounts of martensite. The precipitation of transition carbides was also enhanced by the low-temperature conditioning of martensite. As expected, DCT transformed the retained austenite, so that the corresponding peaks almost disappeared from both the dilatometric and the DSC patterns.     

Near-optimal state feedback design for singularly perturbed systems by unified approach

A near optimal state feedback design for singularly perturbed systems by a unified approach using the delta operator is presented with an example of the aircraft longitudinal motion. The main contribution of this paper is to explore the use of the i -operator that has attracted a new attention in systems science. The i -operator system unifies the continuous system and the discrete system together without loosing any characteristics of both systems. The paper offers the following; Finite-word-length-characteristics are improved using the i -operator. Floating-point-operations are reduced by block diagonalization and by time-invariant optimal feedback gain from the algebraic Riccati equation. The results of adopting those approaches are illustrated in the simulation figures and compared with the earlier one.     

Thermal,hydrolytic, anticorrosive,and tribological properties of alkyd‐silicone hyperbranched resins with high solid content

Novel alkyd hyperbranched resins (AHBRs) modified with a Z‐6018 silicone (a polysiloxane intermediate) and with high solid content were synthesized by etherification reaction using an acid catalyst. Different molar ratios of AHBR to silicone were used. Structural, thermal, hydrolytic, anticorrosive, and tribological properties were studied using infrared (IR) analysis, nuclear magnetic resonance (NMR), vapor pressure osmometry (VPO), thermogravimetric analysis (TGA), acid value, electrochemical impedance spectroscopy (EIS), and pin‐on‐disk friction. IR and NMR provide evidence of grafting of the silicone on AHBR; the efficiency of grafting was quantified by TGA. Thermal stability was studied also by acid value analysis. Grafting increases the number average molecular mass, enhances thermal stability, and improves significantly hydrolytic stability. Corrosion resistance on steel is improved by two orders of magnitude, hence our modified materials can be used as highly effective anticorrosion coatings. Grafting lowers dynamic friction dramatically, more so at higher concentrations of silicone. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Individual Stair Ascent and Descent Walk Speeds Measured in a Korean High-Rise Building

The purpose of this study was to collect and analyze individual unimpeded stair ascent and descent walk speeds for the Korean population. To collect these data, a full-scale experiment was conducted in a 50-storey residential building in Korea involving 30 male and 30 female participants with an average age of 23.4 years. Each participant was required to ascend 50 floors and after a suitable rest period was then required to descend 50 floors using the stairs. Arrival times on each floor were recorded using video cameras, allowing floor by floor walk speeds to be determined and to assess whether fatigue affected the descent/ascent. The average descent speed for the male and female population was 0.83 m/s and 0.74 m/s, respectively, while the average ascent speed was 0.66 m/s and 0.48 m/s. However, there was no significant relationship between body mass index and stair walk speed or unimpeded horizontal walk speed and stair walk speed. During the descent, 50% of the population displayed a decrease in the walk speed over the final half of the descent with a maximum decrease of some 19%. However, some 50% of the population increased their travel speed during the final half of the descent. During the ascent, all participants decreased their speed over the first 20 floors by an average of approximately 60%. Implications of these findings for evacuation modeling/simulation are discussed.     

In situ monitoring of the biocatalysed partial hydrolysis of cocoa butter and palm oil fraction

Partial glycerides are widely used ingredients in confectionery products that can be produced from natural fats. In a biocatalytic partial hydrolysis of cocoa butter and palm oil fractions, a product mixture containing 1.5% monoglycerides and 5.5% diglycerides intended for the use in confectionery products was created. This study is a proof of principle that shows the feasibility of monitoring the biocatalytic partial hydrolysis of these two natural fats in situ with ATR-FTIR spectroscopy. An economic approach was utilised for calibration since partial glyceride calibration standards are costly and poorly available. The released compounds were quantified by means of chemometric modelling, and the model was validated with gas chromatography. Resulting root mean square errors were in the low per cent range. Additionally, the results indicate that distinction of the released free fatty acids is possible with ATR-FTIR spectroscopy.     

Chryseobacterium meningosepticum in a parapneumonic effusion in a chronic kidney disease patient on hemodialysis

Chryseobacterium meningosepticum is an uncommon human pathogen, which is an inhabitant of soil and water. It should be included in the list of suspected nosocomial infections, especially in patients with immunocompromised status. C. meningosepticum infections are not common but are clinically important because the organism is naturally resistant to multiple antibiotics. We report a case where the bacterium was isolated from the pleural fluid from a chronic kidney disease patient on hemodialysis, who developed pneumonia with complicated parapneumonic effusion. To the best of our knowedge, this is the first case where C. meningosepticum is isolated from the pleural effusion, from India.     

Polyfunctional macromonomers obtained from 2,2‐bis(hydroxymethyl) propanoic acid and tall oil fatty acids

Macromonomers (MMs) were obtained with different proportions of dimethylolpropionic acid (DMPA) and tall oil fatty acid (TOFA). The MMs were characterized by their acid value (AV), their hydroxyl value (OHV), IR spectroscopy, NMR, electrospray ionization–mass spectrometry, UV spectroscopy, rheological, differential scanning calorimetry, thermogravimetric analysis, gloss, flexibility, and adherence analyses. The presence of hydroxyl and ester groups and double bonds were confirmed by IR and NMR analyses. IR analysis showed that the intensity of the OH groups decreased with the addition of TOFA. In all cases, the AVs of the MMs were lower than those of DMPA and TOFA. By electrospray ionization–mass spectrometry, the formation of the DMPA homopolymers and structures with molecular weights higher than that of DMPA were observed. All of the MMs were amorphous. The viscosity of the MMs decreased with the addition of TOFA. The gloss values of the MMs at 85° were higher than 100, and the flexibility was good. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42029.