Medium frequency magnetron self-sputtering of copper

It is well known that the magnetron self-sustained sputtering (SSS) process can be achieved in the direct current (DC) operation mode (DC-SSS) if certain conditions are fulfilled: high self-sputtering yield of the target material (theoretically Y>1), appropriate magnetron source design, high target power density to ensure high ionization level of the sputtered material. The main disadvantage of the DC-SSS process is the instability related to possibility of an arc formation. The author postulates that magnetron plasma pulsing can minimize this problem.In this paper, voltage and current waveforms of medium frequency (MF) powered magnetron source are analysed. A simple electrical model, explaining dynamics of MF magnetron discharge is presented. The method to achieve MF magnetron SSS process is proposed and experimentally verified. The results of MF magnetron SSS (MF-SSS) process are presented for the first time (to the author's knowledge). The experiments were performed using a planar magnetron source equipped with a copper target of 50 mm in diameter and 6 mm thick. The magnetron source was powered by a resonant (110 kHz) power supply. The target power density during MF-SSS process was about 490 W/cm².     

Atomically Precise Prediction of 2D Self‐Assembly of Weakly Bonded Nanostructures: STM Insight into Concentration‐Dependent Architectures

A joint experimental and computational study is reported on the concentration‐dependant self‐assembly of a flat C₃‐symmetric molecule on a graphite surface. As a model system a tripodal molecule, 1,3,5‐tris(pyridin‐3‐ylethynyl)benzene, has been chosen, which can adopt either C_3h or C_s symmetry when planar, as a result of pyridyl rotation along the alkynyl spacers. Density functional theory (DFT) simulations of 2D nanopatterns with different surface coverage reveal that the molecule can generate different types of self‐assembled motifs. The stability of fourteen 2D patterns and the influence of concentration are analyzed. It is found that ordered, densely packed monolayers and 2D porous networks are obtained at high and low concentrations, respectively. A concentration‐dependent scanning tunneling microscopy (STM) investigation of this molecular self‐assembly system at a solution/graphite interface reveals four supramolecular motifs, which are in perfect agreement with those predicted by simulations. Therefore, this DFT method represents a key step forward toward the atomically precise prediction of molecular self‐assembly on surfaces and at interfaces.     

An analysis of the causes of a BWE counterweight boom support fracture

A bucket wheel excavator (BWE) collapsed in a brown coal mine. As a result of a tie rod fracture the counterweight boom, the discharge boom and several other components of the other assemblies underwent plastic deformation. This paper presents the results of computer simulations of the collapse. A finite element method analysis of the counterweight boom tie rod showed stress concentrations exceeding the allowable level. Also material tests of the fracture surface were carried out to identify the causes of the collapse. Macroscopic and microscopic images of areas within the fracture were obtained. Measurements of hardness and microhardness in the vicinity of the weld were performed. The FEM analyses and material tests showed that the causes of the collapse were design and welding faults.     

High-pressure investigations of positive ion-molecule reactions in a mixtureof H2S and CH4

The positive ion-molecule reactions in the mixtures of hydrogen sulfide and methane have been examined by means of quadrupole mass spectrometer with the high-pressure ion source. The concentration of hydrogen sulfide in mixtures ranged from 10% to 90% with 10% increment. For each mixture major bimolecular ion-molecule reactions have been identified in the total pressure range from 0.7 to 33.3 Pa. The electron energy for all measurements was fixed at 300 eV and the repeller potential was maintained at 5 V. Relative intensities of ion currents for the observed ions C⁺, CH⁺, CH₂⁺, CH₃⁺, CH₄⁺, CH₅⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, S⁺, HS⁺, H₂S⁺, H₃S⁺, H₃³⁴S⁺, CHS⁺, CH₃S⁺, S₂⁺, HS₂⁺ and H₂S₂⁺ were determined as a function of total gas pressure inside the ion source collision chamber, repeller potential and concentration of methane in the mixture.     

Characterisation of enzymatically oxidised lignosulfonates and their application on lignocellulosic fabrics

BACKGROUND: The ‘double function’ of laccase, from the ascomycete Myceliophthora, to depolymerise/polymerise lignin was studied in this work. A lignosulfonate (LS) compound was oxidised by enzymatic action and several techniques were applied to measure the polymeric changes obtained. This study was focused on the attachment level of the oxidised LS at the flax surface. RESULTS: Modified solutions were studied in terms of surface charge. Zeta potential values obtained showed an increase of polymerisation after several days of incubation. The change in molecular weight after LS polymerisation was detected using gel permeation chromatography. An increase of 1700 Da was achieved. Fourier transform infrared and UV‐visible spectroscopy techniques were applied and the results showed an increase of the degree of polymerisation. The colour strength of flax fabrics incubated with oxidised LS solutions was also measured and an increase of K/S (K, absorption coefficient; S, scattering coefficient) after enzymatic oxidation was observed. CONCLUSION: The oxidised lignin products obtained show good potential for use in natural surface modification of textile materials containing flavonoids. These findings have important practical implications for lignocellulosic fibre coloration, where new polymers can replace harsh chemicals in the textile industry. Copyright © 2009 Society of Chemical Industry     

The effect of selected parameters of formation on properties of alginate/Ca2+/oligochitosan capsules

Optimization of the technological parameters affecting the mechanical properties and permeability of capsules is essential to produce capsules with improved properties for cell immobilization. In the present paper, the effect of different parameters on the technological properties of alginate/Ca²⁺/oligochitosan capsules has been investigated. The correct adjustment of the alginate concentration in the polymer matrix and the oligochitosan molar mass, concentration and coating time, have been found to be key parameters in obtaining porous and mechanically stable alginate/Ca²⁺/oligochitosan capsules. Results showed that an increase in the coating time and concentration of the alginate generated more stable capsules with a reduced membrane cut‐off. Furthermore, we have established some correlations between capsule properties and the effectiveness of chitosan binding within the capsule's membrane. Data addressed herein could be a valid tool to fabricate optimized alginate/Ca²⁺/oligochitosan capsules with a potential for use in cell immobilization technology. Copyright © 2006 Society of Chemical Industry     

The G-Protein-Coupled Estrogen Receptor (GPER/GPR30) in Ovarian Granulosa Cell Tumors

Ovarian granulosa cell tumors (GCTs) are thought to arise from cells of the ovarian follicle and comprise a rare entity of ovarian masses. We recently identified the G-protein-coupled estrogen receptor (GPER/GPR30) to be present in granulosa cells, to be regulated by gonadotropins in epithelial ovarian cancer and to be differentially expressed throughout folliculogenesis. Thus, supposing a possible role of GPER in GCTs, this study aimed to analyze GPER in GCTs. GPER immunoreactivity in GCTs (n = 26; n (primary diagnosis) = 15, n (recurrence) = 11) was studied and correlated with the main clinicopathological variables. Positive GPER staining was identified in 53.8% (14/26) of GCTs and there was no significant relation of GPER with tumor size or lymph node status. Those cases presenting with strong GPER intensity at primary diagnosis showed a significant reduced overall survival (p = 0.002). Due to the fact that GPER is regulated by estrogens, as well as gonadotropins, GPER may also be affected by endocrine therapies applied to GCT patients. Moreover, with our data supposing GPER to be associated with GCT prognosis, GPER might be considered as a possible confounder when assessing the efficacy of hormone-based therapeutic approaches in GCTs.     

A comparative performance study of common and popular task‐centric programming frameworks

Programmers today face a bewildering array of parallel programming models and tools, making it difficult to choose an appropriate one for each application. An increasingly popular programming model supporting structured parallel programming patterns in a portable and composable manner is the task‐centric programming model. In this study, we compare several popular task‐centric programming frameworks, including Cilk Plus, Threading Building Blocks, and various implementations of OpenMP 3.0. We have analyzed their performance on the Barcelona OpenMP Tasking Suite benchmark suite both on a 48‐core AMD Opteron 6172 server and a 64‐core TILEPro64 embedded many‐core processor. Our results show that the OpenMP offers the highest flexibility for programmers, and this flexibility comes to a cost. Frameworks supporting only a specific and more restrictive model, such as Cilk Plus and Threading Building Blocks, are generally more efficient both in terms of performance and energy consumption. However, Intel's implementation of OpenMP tasks performs the best and closest to the specialized run‐time systems. Copyright © 2013 John Wiley & Sons, Ltd.     

Electrical properties of the DGEBA/PANI-Ag composites

The metallopolymer polyaniline-silver (PANI-Ag) was synthesized and used as conductive filler in crosslinked diglycidyl ether of bisphenol A (DGEBA) epoxy network. The hybrid organic/inorganic PANI-Ag powders were successfully synthesized via in situ chemical oxidation of polyaniline-emeraldine base (PANI-EB) by the capped Ag⁺ on the polyaniline-emeraldine base (PANI-EB) surface. The UV–Vis and FT-IR spectra confirmed the pernigraniline structure (PN) of PANI in the hybrid PANI-Ag. The PANI-Ag dispersion in epoxidic matrix was analyzed by optical microscopy (OM). The images analysis from OM showed that the particle agglomerate size of the metallopolymer increased with increasing PANI-Ag concentration in the DGEBA composite, owing to the aggregation effect. The dc conductivity and impedance spectroscopy of the DGEBA/PANI-Ag composite was measured at different PANI-Ag concentrations in the DGEBA network. The electrical dc conductivity of the PANI-Ag was 35.1 S cm⁻¹ and was dependent of the PANI-Ag concentration in DGEBA matrix. The real and imaginary part of impedance complex measurements indicates a strong interfacial polarization at low frequency for both PANI-Ag and DGEBA/PANI-Ag, respectively. The imaginary part of impedance complex Im(Z) data decrease with the PANI-Ag hybrid concentration in the frequencies range of 10²–10⁶ Hz. The dependence of the Im(Z) on the frequency exhibited a relaxation process in both, PANI-Ag and DGEBA/PANI-Ag composite with 10 phr of PANI-Ag powder.