Random poly(ε‐caprolactone‐L‐alanine) by direct melt copolymerization

A series of random polyesteramides (PEAs) with a range of molar composition from 90/10 to 50/50 were synthesized by direct melt polycondensation of ε‐caprolactone and l ‐alanine. Their structure was fully characterized by Fourier transform IR and NMR spectroscopy. The resulting copolymers are completely amorphous with the exception of PEA‐90/10 which possesses a semicrystalline structure. These PEAs present increasing glass transition temperatures at increasing l ‐alanine contents and exhibit fairly good thermal stability with 10% mass loss temperatures reaching 315 °C. © 2020 Society of Industrial Chemistry     

A method to estimate local deposition conditions using film profiles in features

A method to estimate the local partial pressures and temperature during low pressure chemical vapor deposition (LPCVD) proceses using film profile data is demonstrated using the chemistry of blanket tungsten deposition by the hydrogen reduction of tungsten hexafluoride. EVREST, the computer program which performs the estimates, uses EVOLVE, a physically based process simulator for ballistic transport and heterogeneous reactions in features on patterned wafers, to compute film profiles for a given set of deposition conditions. In order to validate the estimation method and to demonstrate EVREST, test calculations are performed using film profiles generated by EVOLVE instead of experimental scanning electron microscopy cross-sections. Calculated films profiles are compared with the generated film profiles (the data) and the simulated deposition conditions are adjusted using an algorithm based on Marquardt's method to minimize the sum of squared differences between points on the calculated and generated profiles. Test calculations confirm that film profiles in more than one feature can be used to improve the reliability of the partial pressure and temperature estimates.     

Optimal imperfect preventive maintenance policy for equipment leased during successive periods

In this paper, we consider randomly failing equipment leased several times during their life cycle with a given warranty period. A mathematical model is developed to determine the optimal efficiency levels of preventive maintenance (PM) to be performed on the equipment between successive lease periods, maximising the expected total profit of the lessor over the equipment life cycle. The model considers the expected leasing revenue as well as the equipment acquisition cost and the average PM and repair costs. PM actions allow reducing the age of the equipment to a certain extent with a corresponding cost depending on the PM level adopted. The efficiency of the PM is determinant of the expected revenue during the next lease period. Given a set of K possible PM levels and the number of lease periods n over the equipment life cycle, K^{n?1 PM} strategies are possible. A genetic algorithm is proposed in order to obtain nearly optimal policies in situations where the number of possibilities K^n?1 is very high. Obtained numerical results are discussed. Small- and big-size instances of the problem are considered in the case of a service company in the oil and gas industry specialised in leasing specific equipment such as separators, to oil companies for production activities with a limited duration of several months like well testing or short production tests.     

Direct electrochemistry for the imidazole complex of microperoxidase-11 in dimethyl sulfoxide solution at naked electrode substrates including glassy carbon, gold, and platinum

The effect of the total water content on the persistence and rate of direct heterogeneous electron transfer between the imidazole complex of microperoxidase-11 (im-MP-11) and naked gold, platinum, and glassy carbon (GC) in dimethyl sulfoxide (DMSO) solutions containing 0.1 M tetra-n-butylammonium perchlorate was investigated using cyclic voltammetry. Electron transfer between im-MP-11 and Au, Pt, and GC has been found to be persistent for more than 1 h and at least quasi-reversible [k(s)' = (8.7 ± 0.1) × 10(-4) cm/s (Au), k(s)' = (7.2 ± 1.3) × 10(-4) cm/s (Pt), and k(s)' = (5.7 ± 1.0) × 10(-4) cm/s (GC)] in dimethyl sulfoxide containing an absolute water content between 0.1 and 1.8%. The heterogeneous electron transfer rate constant is independent of the total water content of the DMSO solution when between 0.1 and 1.8% water is present.     

Polyamides incorporating furan moieties. 5. Synthesis and characterisation of furan-aromatic homologues

2,2′-Bis (5-chloroformyl 2-furyl) propane and various aromatic diamines were used as monomers in the study of their interfacial polycondensation and the properties of the ensuing furanic-aromatic polyamides. The effects of such variables as the nature of the organic phase, the temperature, the reaction time, and the type and concentration of the catalyst were investigated as well as the properties of the polyamides in terms of structure, average chain length, T_g, T_m and thermal stability.     

TMT-HCC: A tool for text mining the biomedical literature for hepatocellular carcinoma (HCC) biomarkers identification

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. New insights into the pathogenesis of this lethal disease are urgently needed. Chromosomal copy number alterations (CNAs) can lead to activation of oncogenes and inactivation of tumor suppressors in human cancers. Thus, identification of cancer-specific CNAs will not only provide new insight into understanding the molecular basis of tumor genesis but also facilitate the identification of HCC biomarkers using CNA.     

Optimization of printing parameters for improvement of mechanical and thermal performances of 3D printed poly(ether ether ketone) parts

Many processing parameters can be adjusted to optimize the fused filament fabrication (FFF) process, a popular and widely used additive manufacturing techniques for plastic materials. Among those easily adjusted parameters are the nozzle temperature, printing speed, raster orientation, and layer thicknesses. Using poly(ether ether ketone) (PEEK) as the base material, a design of experiments analysis was performed on the main FFF parameters. A response surface methodology was applied to analyze the results and to maximize the output responses. Results have shown that the nozzle temperature is the most influential parameter on tensile properties and the crystallinity degree of printed PEEK by FFF process. Parts produced with optimized FFF parameters were then subjected to an annealing treatment to induce a relaxation of residual stress and to enhance crystallinity. The best properties for 3D printed PEEK parts were achieved with annealed parts prepared at 400°C with a printing speed of 30 mm/s, 0.15 mm layer thickness and raster orientation of [0°/15°/−15°]. The resulting parts have mechanical properties comparable to those of injected PEEK.     

Preparation of nanocomposite dispersions based on cellulose whiskers and acrylic copolymer by miniemulsion polymerization: Effect of the silane content

A one‐step method was used to prepare stable aqueous nanocomposite dispersions based on cellulose whiskers extracted from the rachis of the date palm tree and a poly(styrene‐co‐2‐ethyl hexylacrylate) copolymer via miniemulsion polymerization. A reactive silane, i.e., methacryloxypropyl triethoxysilane was added to stabilize the dispersion and favor the anchoring of the whiskers on polymer particles. Dynamic light scattering was used to study the effect of the silane and whiskers contents on the average particle size of the polymer. Nanocomposites materials were prepared from these dispersions using a casting/evaporation method. The effect of the silane and whiskers contents on the thermal and mechanical properties were studied using differential scanning calorimetry and dynamic mechanical analysis. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

UV resonance Raman probe of heme-bound imidazole established by 15N-labeling of hemoglobin

Recent studies of Cu, Zn superoxide dismutase, and of zinc-finger peptides have established that histidine ligands can be detected in ultraviolet resonance Raman (UVRR) spectra, following NH/D exchange of the imidazole. UVRR spectroscopy therefore offers promise for monitoring histidine ligation in heme proteins. In this work, we characterize heme-bound histidine UVRR bands for N-acetyl-microperoxidase-8 (MP-8) and microperoxidase-11 (MP-11), and also for hemoglobin (Hb). The Hb UVRR spectra are dominated by tyrosine and tryptophan contributions, but a band appears at 1340 cm⁻¹ in D₂O solution, which is assigned to a mode of Fe-bound imidazole. This band shifted 24 cm⁻¹ in protein which was labeled with ¹⁵N via expression of the Hb gene in E. coli grown on ¹⁵NH₄⁺. In MP-11, the position of this band is insensitive to ligation or oxidation state changes, but it is 2 cm⁻¹ lower in deoxyHb than in the CO adduct. This shift may reflect mechanical forces on the proximal histidine in the T state, and/or changes in its H-bonding.