Quality and reliability assurance for electronic systems—actions and results

The changes in the quality assurance organization introduced in recent years in a Swiss firm have led to a substantial improvement in the production quality of electronic circuit boards and to an increase in the reliability of electronic systems. This article demonstrates that the operational reliability of such systems is determined to a great extent by weak points in the electronic components. It follows that an analysis of the causes and the avoidance of such weak points are paramount in controlling the reliability of electronic systems.     

Amorphous Films of Ternary Zinc and Tin Oxides for Transparent Electronics

Amorphous films of two varieties of zinc stannate (ZnSnO₃ and Zn₂SnO₄) have been considered that were fabricated by radio-frequency sputtering of ceramic compound targets containing ZnO and SnO₂ in 1: 1 and 2: 1 ratios. The elemental and phase compositions of the films and their optical and electrical parameters were determined. The transparency of the films in the visible spectral range is on average 87%. Zinc stannate amorphous films have a high electrical conductivity in contrast to amorphous ZnO and SnO₂. This phenomenon, which makes it possible to use zinc stannate amorphous films in transparent and flexible electronics, is explained.     

A comparative analysis of meta-heuristic approaches for facility layout design problem: a case study for an elevator manufacturer

In this study, a facility layout problem having NP-hard problem characteristic is attempted to be solved by using two different meta-heuristic approaches—Genetic Algorithm (GA) and Simulated Annealing (SA)—and a hybrid approach—Genetic Algorithm/Simulated Annealing (HGASA). The case study is completed for a company which can be seen as a small or a medium size enterprise. First, parameter values of GA and SA are determined by testing for various combinations of them. Then, the algorithms are run for one hundred times. The results of the algorithms are compared based on their fitness values and calculation time requirements using the paired-t test, mean and standard values. The results show that SA performs better than the others in terms of the fitness values and the time requirements. In this study, we also test the performance of our GA, SA and HGASA methodologies using some of the well-known test problems from the literature. We obtain very close results to those in literature.     

Carbonaceous Materials-12: a Novel Highly Sensitive Graphene Oxide-Based Carbon Electrode: Preparation,Characterization, and Heavy Metal Analysis in Food Samples

Graphene oxide (GO) was covalently attached to glassy carbon (GC) electrode (GC–O–GO) for fabricating nanosensors to determine trace Pb²⁺ and Cd²⁺ using differential pulse anodic stripping voltammetry (DPASV). Surface characterization of the nanofilm-covered electrode was performed via electrochemical cyclic voltammetry (CV), transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques. Surface pKa of the GO covalent attached GC (GC–O–GO) was calculated via CV. Under optimal conditions, a linear response was found for Pb²⁺ and Cd²⁺ in the range from 1?×?10^?8 to 1?×?10^?12 M. The limit of detections (LODs) of Pb²⁺ and Cd²⁺ were 0.25 pM and 0.28 pM, respectively. The method shows good reproducibility, and stability was successfully applied to measure Pb²⁺ and Cd²⁺ levels in rice, soya, milk, and tap water samples, with good agreement with those obtained by the standard inductively coupled plasma optical emission spectrometry (ICP-OES) method. The method was evaluated by application with the simultaneous determination of the ions in food samples (n?=?6) using the standard addition method. The recoveries of the Pb²⁺ and Cd²⁺ were up to 98 %.     

Volterra kernel estimation for nonlinear communication channels using deterministic sequences

We present a new exact method for the identification of communication channels with nonlinearities. The channel is modelled as a third-order discrete Volterra filter and the Volterra kernels are measured using deterministic input sequences and the corresponding channel outputs. The solutions are in closed form, exact and kernels are estimated in a nonrecursive manner, thus eliminating error propagation. Complex inputs and complex kernels are allowed, which permits the use of PSK or QAM modulated signals for the identification of the bandpass Volterra channel. Simulation examples and comparison with other methods in the literature are provided to verify the method.     

Seeding of the Reaction-Bonded Aluminum Oxide Process

The effect of the initial α-Al₂O₃ particle size in the reaction-bonded aluminum oxide (RBAO) process on the phase transformation of aluminum-derived γ-Al₂O₃ to α-Al₂O₃, and subsequently densification, was investigated. It has been demonstrated that if the initial α-Al₂O₃ particles are fine (∼0.2 μm, i.e., 2.9 × 10¹⁴γ-Al₂O₃ particles/cm³), then they seed the phase transformation. The fine α-Al₂O₃ decreases the transformation temperature to ∼962°C and results in a finer microstructure. The smaller particle size of the seeded RBAO decreases the sintering temperature to as low as ∼1135°C. The results confirm that seeding can be utilized to improve phase transformations and densification and subsequently to tailor final microstructures in RBAO-derived ceramics.     

Electrochemical Behaviors of 2-Amino-3-Hydroxypyridine onto the Glassy Carbon Sensor Electrode: Simultaneous and Independent Determinations of Quercetin, Galangin, 3-Hydroxyflavone, and Chrysin

Flavonoids, with high antioxidant activity in fruits and vegetables, are natural vegetable dyes synthesized from phenylalanine. They are very essential for human health due to their activity as free radical acceptors. In this paper, the availability in the determination of quercetin (Que), galangin (Gal), 3-hydroxyflavone (3HF), and chrysin (Chr) of a modified glassy carbon (GC) sensor electrode using 2-amino-3-hydroxypyridine (AHP) was examined separately and simultaneously by cyclic voltammetry (CV). Surface characterization of modified electrodes was performed using CV, electrochemical impedance spectroscopy, and scanning electron microscopy techniques. The modification of AHP onto the GC electrode surface was carried out between ?150 and +600 mV potential range using 100 mV?s^?1 scanning rate with 30 cycles. The binding of flavonoid derivatives onto the modified surface was performed between +300 and +1,700 mV potential range using 100 mV?s^?1 scanning rate with 10 cycles. The usability of the modified electrode was examined in the determination of some flavonoids by square wave voltammetry. From the experimental results, it was found out that Que, 3HF, and Chr; Gal, 3HF, and Chr; and 3HF and Chr can be determined simultaneously by using an AHP-modified GC sensor electrode. Also, these molecules can easily be determined separately by using the modified electrode.     

Biologically Active Tissue Factor-Bearing Larger Ectosome-Like Extracellular Vesicles in Malignant Effusions from Ovarian Cancer Patients: Correlation with Incidence of Thrombosis

The development of malignant effusions such as ascites reflects a massive progression of a malignant disease. In patients with ovarian carcinoma, a high amount of ascites (>500 mL) is an independent negative prognostic marker. The composition and constituents of ascites reflect the inflammatory environment of the underlying tumor. Increased cellular resistance of ascites-derived tumor cells and the development of venous thromboembolic events (VTE) are major risks for these patients, especially in patients with advanced ovarian carcinoma. In this study, we discuss the release of tissue factor-bearing extracellular vesicles (TF⁺ EVs) from tumor cells into the environment (ascites fluid) and their systemic spreading as a possible causal explanation of the pathologic coagulation status in these patients. We obtained ascites from patients with advanced ovarian carcinoma, collected during surgery or therapeutic paracentesis (n = 20). Larger ectosome-like EVs were isolated using sequential centrifugation, quantified by high-resolution flow cytometry and analyzed using nanoparticle tracking analysis. Furthermore, the pro-coagulant properties (TF activity) of EVs were determined. Compared to published TF activities of EVs from healthy persons, TF activities of EVs derived from ascites of patients with ovarian cancer were very high, with a median of 80 pg/mL. The rate of VTE, as reported in the patient files, was high as well (35%, 7 out of 20). Furthermore, all but one patient with VTE had EV concentrations above the median within their ascetic fluid (p < 0.02). Since VTE continues to be a frequent cause of death in cancer patients, prophylactic antithrombotic treatment might be worth considering in these patients. However, given the risk of bleeding, more clinical data are warranted. Although the study is too small to enable reaching a conclusion on direct clinical implementation, it can well serve as a proof of principle and a rationale to initiate a prospective clinical study with different patient subgroups. We also show ex vivo that these larger ectosome-like EVs induce intracellular ERK phosphorylation and tumor cell migration, which is not directly related to their pro-coagulative potency, but might help to understand why cancer patients with thromboembolic events have a poorer prognosis.     

Texture development in Fe-doped alumina ceramics via templated grain growth and their application to carbon nanotube growth

Fe-doped alumina (Fe-Al₂O₃) materials with a controlled microstructure could be designed for some special uses such as a substrate for carbon nanotube growth. In this study, Fe-doped Al₂O₃ ceramics with varying degrees of texture were prepared via Templated Grain Growth method and utilized for carbon nanotube synthesis by Catalytic Chemical Vapor Deposition in order to investigate how α-Al₂O₃ crystal orientation affects carbon nanotube growth in polycrystalline ceramics. The degree of texture increased with the Fe content in the presence of liquid phase. Three kinds of carbon filaments (few-wall carbon nanotubes bundles, individual multi-wall nanotubes and carbon nanofibres) were observed over Fe-doped Al₂O₃ ceramics with varying degrees of texture depending on the surface roughness, crystallographic orientation and the size of the catalyst nanoparticles. While well-textured substrates with a rough surface led to a small amount of randomly oriented carbon nanotube bundles, perpendicularly oriented individual multi-wall nanotubes were obtained over relatively smooth single crystal α-Al₂O₃ platelet surfaces (basal planes) which remained in the matrix without growing.