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.     

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.     

Synthesis and physical properties of new oxide AgMnO<Subscript>2</Subscript>

A novel oxide AgMnO₂ was prepared from LiMnO₂ via Ag⁺ → Li⁺ exchange in the eutectic melt AgNO₃-KNO₃. It crystallizes in a monoclinically distorted unit cell (SG C2/m) caused by the Jahn-Teller (J-T) ion Mn³⁺ (3d ⁴). The structure was refined by isotypy with the crednerite CuMnO₂. There are two long axial Mn–O of 264.2(0) pm and four equatorial bonds of 192.7(3) pm and Mn–O–Mn adjoining (83.07°) are bent below the ideal angle. The thermal variation of the magnetic susceptibility (χ/T ⁻¹) obeys a Curie-Weiss law with manganese in a trivalent, high spin (HS) state accommodated in elongated MnO₆ octahedra (14.8%). Direct coupling between Mn³⁺ involves negative exchange interactions through long-range antiparallel moments with a temperature θ _p = −436 K and a magnetic moment of 5.26 μ_B/Mn³⁺ slightly larger than the spin only moment. The title oxide is stable in air up to ∼680 °C before it decomposes into metal silver. It displays a semi-conducting behavior with an activation energy of ∼0.45 eV, characteristic of a conduction by low mobility polarons between Ag^+/2+ where nearly all polarons are bonded. The photoelectrochemical properties of AgMnO₂ have been investigated by photocurrent technique in 1 M KOH. The cathodic photocurrent J _ph provides unambiguous evidence of p-type character attributed to oxygen insertion (0.025 oxygen by formula unit) as required by the charge compensating mechanism. The valence band is made up of Ag−4d wave functions positioned at ∼5.14 eV below vacuum. A comparison with CuMnO₂ was also reported.     

Recombinant and chemical derivatives of apamin. Implication of post-transcriptional C-terminal amidation of apamin in biological activity

The use of the colicin A lysis protein to direct the extracellular release of a fusion protein from Escherichia coli was investigated as an approach for the preparation of recombinant animal toxins. Apamin, a bee venom neurotoxin, was used as the model toxin. It is reticulated by two disulfide bridges and interacts with small conductance Ca(2+)-activated K+ channels. Substantial amounts of free recombinant apamin were obtained by CNBr cleavage of the fusion protein [col-(1-171)-apa] and HPLC purification. It was recognized by conformation-dependent monoclonal antibodies with a K0.5 value close to that for natural apamin, indicating that folding was correct. In toxicity and binding experiments, the recombinant apamin displayed low activity. The recombinant and natural molecules differed by the amidation of the C-terminal histidine residue. Previous structure/activity relationship studies do not implicate this C-terminal residue in activity but the role of its amidation was not investigated. An apamin analog with a non-amidated C-terminal residue was then chemically synthesized. The biological properties of both recombinant and chemical molecules were determined. Amidation of the C-terminal alpha-carboxyl of apamin appears to be essential for full expression of its biological activity.     

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.     

In vivo study of hybrid biomaterial scaffold bioactive glass–chitosan after incorporation of Ciprofloxacin

The present study aimed to evaluate the effect of bioactive glass as well as the presence of Ciprofloxacin drug (%Cip) into bioactive glass–chitosan composite on the in vivo behavior of these scaffolds. These scaffolds were implanted in the femoral condyl of an ovariectomized rat. The serum and organs (liver and kidney) of the under investigated rats were analyzed. Also the physicochemical properties of the prepared implants were assessed using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) before and after implantation (at different periods of implantation). Biochemical and histological analyses of the under investigated rats proved the biocompatibility of the prepared scaffolds. The hydroxyapatite like layer was significantly precipitated on the surface of BG–CH scaffold than BG–CH–20Cip. In this same period, FT-IR of BG–CH shows complete disappearance of Si–O–Si. Their characteristics bands were replaced by P–O group arisen form bone apatite bands. Physicochemical results show progressive degradation of BG–CH and BG–CH–20Cip that occurred at the same time as replacement of the implant by an apatite layer. However, the bioresorbability and bioactivity of BG–CH are faster than those of BG–CH–20Cip. Therefore, the incorporation of the Ciprofloxacin in the BG–CH induces a retarding effect on the formation of the hydroxyapatite, and consequently on the ossification, without any side effects on the liver–kidney.