Replication of sub‐micron features using amorphous thermoplastics

A comprehensive experimental study was carried out to replicate sub‐micron features using the injection molding technique. For the experiments, five different plastic materials were selected according to their flow properties. The materials were polycarbonate (PC), styrene‐butadiene block copolymer (SBS), impact modified poly(methyl methacrylate), methyl methacrylate‐acrylonitrile‐butadiene‐styrene polymer (MABS), and cyclic olefin copolymer (COC). Nanofeatures down to 200‐nm line width and with aspect ratios (aspect ratio = depth/width) of 1:1 could be replicated. In all selected materials, the greatest differences between the materials emerged when the aspect ratio increased to 2:1. The most favorable results were obtained with the use of high flow polycarbonate as the molding material. The best replication results were achieved when melt and mold temperatures were higher than normal values.     

One Question,Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists

Fragment‐based lead discovery is gaining momentum in drug development. Typically, a hierarchical cascade of several screening techniques is consulted to identify fragment hits which are then analyzed by crystallography. Because crystal structures with bound fragments are essential for the subsequent hit‐to‐lead‐to‐drug optimization, the screening process should distinguish reliably between binders and non‐binders. We therefore investigated whether different screening methods would reveal similar collections of putative binders. First we used a biochemical assay to identify fragments that bind to endothiapepsin, a surrogate for disease‐relevant aspartic proteases. In a comprehensive screening approach, we then evaluated our 361‐entry library by using a reporter‐displacement assay, saturation‐transfer difference NMR, native mass spectrometry, thermophoresis, and a thermal shift assay. While the combined results of these screening methods retrieve 10 of the 11 crystal structures originally predicted by the biochemical assay, the mutual overlap of individual hit lists is surprisingly low, highlighting that each technique operates on different biophysical principles and conditions.     

Characterization of piezoelectric ceramics using the burst/transient method with resonance and antiresonance analysis

In this paper, a comprehensive methodology for characterizing the high power resonance behavior of bulk piezoelectric ceramics using the burst method is described. In the burst method, the sample is electrically driven at its resonance frequency, and then either a short circuit or an open circuit condition is imposed, after which the vibration decays at the resonance or antiresonance frequency, respectively. This decay can be used to measure the quality factor in either of these conditions. The resulting current in the short circuit vibration condition is related to the vibration velocity through the “force factor.” The generated voltage in the open circuit vibration condition corresponds to the displacement by the “voltage factor.” The force factor and the voltage factor are related to material properties and physical dimensions of the sample. Using this method, the high power behavior of the permittivity, compliance, effective piezoelectric charge constant, electromechanical coupling factor, and material losses can be determined directly by measuring the resonance (short circuit) and antiresonance (open circuit) frequencies, their corresponding quality factors, the force factor A, and the voltage factor B. The experimental procedure to apply this method is described and demonstrated on commercially available hard and semi‐hard PZT materials of geometry.     

Development and Validation of a Method for the Determination of Fatty Acid Methyl Ester Contents in Tung Biodiesel and Blends

The aim of this study was to develop and validate a method for the analysis of fatty acid methyl ester (FAMEs) content in tung biodiesel and blends with soybean biodiesel. The limits of detection (LOD) and quantification (LOQ), linearity, robustness, accuracy and precision were evaluated by using gas chromatography with mass spectrometry detection and impact electron ionization. The analytical curves showed correlation coefficients values higher than 0.99. The LOD and LOQ were 0.78 and 2.5 mg L⁻¹ for all FAMEs, respectively. The values of accuracy were between 86 and 117%, with relative standard deviation lower than 8%. The method was applied to tung biodiesel and tung and soybean biodiesel blends in the following proportions: 15:85, 20:80, 25:75 (%v/v). All of them showed good performance. Since the method was also applied to soybean biodiesel, the efficiency of the method for the analysis of both pure tung biodiesel and blends with different raw materials was confirmed and the robustness of the method was evidenced.     

Application of a Technofunctional Caseinate Hydrolysate to Replace Surfactants in Ice Cream

There is a demand for a clean label of ice cream in the food industry. To meet this requirement, alternative surfactants and hydrocolloids without an additive number have to be found. Here, a caseinate hydrolysate with improved interfacial properties was investigated as such an additive. Replacing only the surfactant resulted in ice cream characteristics, comparable to using a commercial emulsifier (INS 472b). Thus, a clean labeling of the surfactant using this hydrolysate is possible. By contrast, replacing the hydrocolloid additionally led to an unfavorable ice cream texture and stability.     

Reconfiguring flexible machine modules of a PCB assembly line

Assembly of electronic components to Printed Circuit Boards (PCB) is a complicated manufacturing process and therefore its control is usually divided into several subtasks which are handled separately. We consider the combined task of determining a machine configuration and line balancing for a single assembly line of interconnected, reconfigurable machine modules and one PCB type in production. The modules can be tailored to the needs of each PCB type by suitable assignments for placement heads, nozzles and feeders. Out of these, the component-to-machine assignment appears to be most difficult and we propose five different solution methods for it; brute force, random, greedy, local search and genetic algorithm. The genetic algorithm outperformed the other methods in practical test.     

Aerobic Oxidation of Benzylic Alcohols in Water by 2,2,6,6‐Tetramethylpiperidine‐1‐oxyl (TEMPO)/Copper(II) 2‐N‐Arylpyrrolecarbaldimino Complexes

Novel copper(II) 2‐N‐arylpyrrolecarbaldimine‐based catalysts for the aerobic oxidation of benzylic alcohols mediated by the 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) radical are reported. The catalytic activity for both synthesized and in situ made complexes in alkaline water solutions was studied revealing high efficiency and selectivity (according to GC selectivity always >99%) for both of these catalytic systems. For example, quantitative conversion of benzyl alcohol to benzaldehyde can be achieved with the in situ prepared bis[2‐N‐(4‐fluorophenyl)‐pyrrolylcarbaldimide]copper(II) catalysts in 2 h with atmospheric pressure of O₂ at 80 °C. Interestingly, these catalysts can utilize dioxygen as well as air or hydrogen peroxide as the end oxidants, producing water as the only by‐product.     

Electrochemical reduction of oxygen on thin-film Pt electrodes in acid solutions

The electrochemical reduction of oxygen on thin-film platinum electrodes in 0.1 M HClO₄ and 0.05 M H₂SO₄ solutions has been investigated using the rotating disk electrode (RDE) method. Thin films of Pt (0.25-20 nm thick) were prepared by vacuum evaporation onto glassy carbon substrate. The surface morphology of Pt films was examined by transmission electron microscopy (TEM). The specific activity of O₂ reduction was higher in HClO₄ and decreased with decreasing film thickness. In H₂SO₄, the specific activity was lower and appeared to be independent of the Pt loading. The values of Tafel slopes close to −120 mV dec⁻¹ in high current density range and −60 mV dec⁻¹ in low current density range were obtained for all electrodes in both solutions, indicating that the mechanism of O₂ reduction is the same for thin-film electrodes as for bulk Pt. The number of electrons transferred per O₂ molecule was close to four for all thin Pt films studied.