Electron beam direct manufacturing, synonymously known as electron beam additive manufacturing, along with other additive “3-D printing” manufacturing processes, are receiving widespread attention as ...a means of producing net-shape (or near-net-shape) components, owing to potential manufacturing benefits. Yet, materials scientists know that differences in manufacturing processes often significantly influence the microstructure of even widely accepted materials and, thus, impact the properties and performance of a material in service. It is important to accelerate the understanding of the processing–structure–property relationship of materials being produced via these novel approaches in a framework that considers the performance in a statistically rigorous way. This article describes the development of a process model, the assessment of key microstructural features to be incorporated into a microstructure simulation model, a novel approach to extract a constitutive equation to predict tensile properties in Ti-6Al-4V (Ti-64), and a probabilistic approach to measure the fidelity of the property model against real data. This integrated approach will provide designers a tool to vary process parameters and understand the influence on performance, enabling design and optimization for these highly visible manufacturing approaches.
Souza et al discuss a study about the occurrence of Grapholita molesta, a major pest in fruit cultivation, attacking Litchi chinensis var. Bengal for the first time. The study was conducted in ...commercial and teaching orchards in Minas Gerais, Brazil, over three agricultural years. The attacks were observed on young tissues, branches, and fruits, resulting in drying of shoot tips and biogenic perforations with fecal residues. The larvae of G. molesta were identified as the cause of the damage. The infestation poses a new challenge for lychee growers and the scientific community, as G. molesta is a polyphagous insect, making its control difficult. They recommend thorough monitoring and research to understand the behavior of G. molesta in lychees and develop strategies for its control. Integrated pest management is suggested as an approach to minimize potential damage. The study highlights the importance of monitoring and analyzing pests in lychee orchards to support improved fruit quality and the development of suitable control methods.
The performance demanded for the Level-0 trigger of LHCb imposes very stringent requirements on the quality of the muon chambers. These chambers must pass a series of tests before being mounted in ...the experimental setup. The six tests adopted for the quality control of the chambers produced at the Laboratori Nazionali di Frascati (LNF) are described. After the wires are wound and glued on a cathode panel, the wire pitch is measured by two digital cameras with a precision of about 20 mum. The mechanical tension of the wire is deduced from its mechanical resonance frequency measured by an automated system based on a digital electrostatic method. The wire tension is obtained with a precision of about 1%. Once all elements are assembled, the gas tightness of a chamber is verified by monitoring the decrease rate of an overpressure applied to it. After a suitable high-voltage conditioning, the dark current is recorded and the gas gain uniformity of the chamber is measured using a collimated 137 Cs source which can be moved over the chamber surface. Finally, the detector is fully equipped with the front-end electronics, and its detection efficiency is tested with cosmic rays
We have demonstrated direct nanoscale transfer printing (nTP) of PdAu lines from a hard mold onto a hard substrate at room temperature without employing any flexible buffer layers or organic adhesion ...promoters or release agent layers. PdAu was evaporated onto the mold surface, and a Ti layer was deposited on top of the PdAu layer. By pressing the mold against a Si/SiO 2 substrate, the PdAu/Ti sandwich structure was directly transferred onto the SiO 2 surface. The molds used in these experiments were GaAs/AlGaAs sandwich structures fabricated by molecular beam epitaxy that we cleaved and selectively etched afterwards in order to generate 3-D grating structures with nanometer resolution on their edges. We fabricated positive multiline molds with different aspect ratios, linewidths between 15 and 100 nm, and spacings between lines ranging from 5 to 70 nm. We also fabricated negative single-line molds with a positive supporting structure comprising a single 16-nm-wide groove feature. The experiments revealed that direct hard-on-hard transfer of nanoscale structures from a mold onto a substrate can be used to fabricate PdAu gaps with widths down to 9 nm. We also performed electronic measurements on transfer patterns and demonstrated that transferred structures can be used as electrodes, which are electrically isolated by these gaps. Since isolation characteristics of gaps improved with decreasing gap length, we partitioned longer gap segments into multiple shorter ones by focused ion beam lithography and conventional optical lithography in combination with wet chemical or plasma etching of the mold or the substrate, respectively. In this paper, we give a detailed description of all technological aspects of the developed direct nTP technique, including mold preparation, patterning efficiency, short reduction techniques, and yield.
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