Examination of phase changes in the CuAl high-temperature shape memory alloy with the addition of a third element

In the present study, a ternary CuAl-based alloy was produced by adding 2% chromium, niobium, titanium and hafnium instead of 2% copper from the Cu₈₈Al₁₂ (% in mass) shape memory alloy, and the phase changes in the alloy were examined. As a result of the X-ray analyses performed at room temperature, the α phase, which is rich in copper, was detected in the main sample, i.e., the Cu₈₈Al₁₂ alloy, and the β ₁ ¹ and γ ₁ ^? phases were detected in the four of the Cu₈₆Al₁₂Cr₂, Cu₈₆Al₁₂Nb₂, Cu₈₆Al₁₂Ti₂ and Cu₈₆Al₁₂Hf₂ alloys. All of phases were clearly seen in SEM images. As a result of the mapping performed during chemical analysis, it was observed clearly that there appeared a precipitation phase in the Cu₈₆Al₁₂Cr₂, Cu₈₆Al₁₂Nb₂, Cu₈₆Al₁₂Ti₂ alloys due to the additions. It was also observed that the additions were effective in forming a martensite phase in the Cu₈₈Al₁₂ alloy. In differential scanning calorimetry (DSC) measurements, which were taken to support these measurements, no martensitic phase transformations were detected in dual primary alloy (Cu₈₈Al₁₂); however, a clear martensite phase transformation was detected in ternary alloys (Cu₈₆Al₁₂Cr₂, Cu₈₆Al₁₂Nb₂, Cu₈₆Al₁₂Ti₂ and Cu₈₆Al₁₂Hf₂) in the first DSC measurement. Then, when the DSC cycle was applied to the ternary alloy, both the austenite transformation and martensite transformation temperatures were clearly seen, and it was claimed that all the alloys showed high-temperature shape memory alloy properties.     

Analysis of customer lifetime value and marketing expenditure decisions through a Markovian-based model

The general aim of this study is to provide a guide to the future marketing decisions of a firm, using a model to predict customer lifetime values. The proposed framework aims to eliminate the limitations and drawbacks of the majority of models encountered in the literature through a simple and industry-specific model with easily measurable and objective indicators. In addition, this model predicts the potential value of the current customers rather than measuring the current value, which has generally been used in the majority of previous studies. This study contributes to the literature by helping to make future marketing decisions via Markov decision processes for a company that offers several types of products. Another contribution is that the states for Markov decision processes are also generated using the predicted customer lifetime values where the prediction is realized by a regression-based model. Finally, a real world application of the proposed model is provided in the banking sector to show the empirical validity of the model. Therefore, we believe that the proposed framework and the developed model can guide both practitioners and researchers.     

Synthesis and characterization of cannabimimetic aminoalkylindole based 5‐(4‐alkyl‐1‐naphthoylamino)‐1,3,4‐thiadiazole‐2‐sulfonamides

A novel series of cannabimimetic aminoalkylindole‐based sulfonamide derivatives was synthesized. These new compounds were synthesized by reacting acyl chlorides of naphthoic acids with deacetylated acetazolamide in the presence of N‐ethyl‐morpholine to give structures incorporating 1‐naphthoyl groups of cannabimimetic aminoalkylindoles and a five‐membered heteroring typical of antiglaucoma sulfa drugs. The synthesized compounds were characterized using standard techniques. Photoluminescence of these derivatives was also studied, where more electron‐donating groups on the aromatic ring at the para‐position caused an increase in the intensity of the main peaks and shifts to higher emission wavelengths. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:707–714, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20738     

Chemical composition and antimicrobial activity of essential oil of Achillea cretica L. (Asteraceae) from Turkey

Hydrodistilled volatile oil from the aerial parts of Achillea cretica L. (Asteraceae) was analysed by a combination of GC and GC/MS. Seventy-six components were identified, constituting 86.4% of the oil. The main constituents of the essential oil were caryophylladienol-II (13.4%), β-maaliene (6.1%), neo-intermedeol (6.0%), carvone (4.9%), spathulenol (4.5%), palmitic acid (3.3%) and selina-3,11-dien-6α-ol (3.2%). The antimicrobial activity was evaluated by the broth-dilution method on nine microbial strains and showed to be quite strong against the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus. The antibacterial properties of A. cretica justify its use in traditional medicine for the treatment of wounds, contaminated through bacterial infections.     

Electrocatalytic Reduction of Oxygen at Glassy Carbon Electrodes Coated with Diazonium‐derived Porphyrin/Metalloporphyrin Films

In this study, the influence of the film structure was investigated on the electrocatalytic oxygen reduction at GC electrodes covered with porphyrin and metalloporphyrin rings via the diazonium modification method. For that purpose, primarily, tetraphenylporphyrin (TPP) films on GC electrode surfaces were prepared by electroreduction of in situ generated diazonium salts of 5‐(4‐aminophenyl)‐10,15,20‐triphenylporphyrin (APP) and 5,10,15,20‐tetrakis(4‐aminophenyl)porphyrin (TAPP) molecules. Next, the formation of metalloporphyrin films on the modified surfaces was accomplished through the complexation reactions of surface porphyrin rings with metal ions in the salt solutions containing Mn(II), Fe(III) and Co(II) ions. The resulting porphyrin and metalloporphyrin layers were identified with XPS and ICP‐MS. The electrochemical barrier properties of the films on GC surfaces were examined by cyclic voltammetry in K₃Fe(CN)₆ aqueous solution. The electrocatalytic abilities of the resulting films were also investigated for the oxygen electrochemical reduction by employing cyclic voltammetry in PBS solutions saturated with oxygen. The results showed that the oxygen reduction potentials on modified GC electrodes were shifted to less negative potentials compared to that of bare GC electrode. Also, it was obtained that the oxygen reduction reaction was more effective on the GC electrodes modified with TPP rings by using TAPP molecules than those prepared by using APP molecules.     

The Effect of Iron and Copper as an Essential Nutrient on Mitochondrial Electron Transport System and Lipid Peroxidation in Trichoderma harzianum

Iron and copper are essential nutrients for all living organisms as cofactors of many enzymes and play important roles in electron transport system (ETS) enzymes which have heme and iron–sulfur centers. In the present study, ETS enzymes, namely, succinate dehydrogenase (SDH) and cytochrome c oxidase (COX), activities as well as adenine nucleotides and lipid peroxidation (LPO) levels of eukaryotic model Trichoderma harzianum grown in varied concentrations of iron (0–20 mg/l) and copper (0–25 mg/l) mediums have been examined. SDH and COX activities increased up to 10 mg/l of iron. COX and SDH activities increased significantly up to 15 and 1 mg/l of copper, respectively. ATP and ADP levels showed a positive correlation with SDH activity with respect to iron–copper concentrations. The trends of AMP were similar with those of ATP and ADP for iron concentrations, while AMP levels elevated until 5 mg/l of copper. As an indicative marker of membrane damage, LPO levels increased with iron and copper concentration. In conclusion, iron and copper concentrations are of critical importance on activities of the ETS enzymes besides adenine nucleotides and LPO levels by maintenance of this metal homeostasis.     

Electrochemical investigation of 1,3,5-triphenylformazan and its nitro derivatives in dimethyl sulfoxide.

Cyclic voltammetric (CV) and chronoamperometric (CA) behaviors of 1,3,5-triphenylformazan (TPF), 3-(p-nitrophenyl)-1,5-diphenylformazan (PNF) and 3-(m-nitrophenyl)-1,5-diphenylformazan (MNF) were studied in dimethyl sulfoxide medium. TPF was found to give a single sharp cathodic CV peak corresponding to a gain of one-electron per molecule. The diffusion coefficient and the number of electrons transferred were calculated using the Baranski equation with the CV-data obtained by an ultramicroelectrode. Standard rate constants for the reduction were calculated by the Klingler-Kochi technique. The electrochemical data obtained support the mechanism proposed by Umemoto.     

Evaluation of lab-scale EUV microscopy using a table-top laser source

High brightness Extreme Ultraviolet (EUV) sources for laboratory operation are needed in nano-fabrication and actinic (“at-wavelength”) inspection of the masks for high volume manufacturing in next generation lithography. Laser-plasma EUV sources have the required compactness and power scalability to achieve the demanding requirements. However, the incoherent emission lacks the brightness for single-shot high contrast imaging. On the other hand, fully coherent sources are considered to be unsuitable for full-field sample illumination and prone to speckles. We evaluate the capabilities of a lab-scale amplified-spontaneous-emission (ASE) EUV laser source to combine brightness and high quality imaging with full-field imaging, along with rapid acquisition and compactness.     

Monte Carlo simulations of bremsstrahlung photon yields from thin targets with electron beams between 10 and 40 MeV

A linear accelerated electron beam is a powerful source of highly energetic photons that can be used for various nuclear applications. In this work, the bremsstrahlung photon yields from thin targets such as Ta, Nb, Cu and Al have been calculated using the FLUKA simulation code. The simulation calculations were performed for incident electrons with energies in the range of 10–40 MeV and targets with thicknesses between 4×10^?4 and 10^?3 radiation lengths.