An instrument capable of measuring optical losses, transmission, and the radius of curvature of high reflectivity mirrors is presented. The measurement setup consists of two remote controlled hexapod systems with 6 degrees of freedom placed inside a vacuum enclosure. Mirror loss measurements are performed via the cavity ring-down time method using a linear resonant two-mirror Fabry-Perot cavity configuration. The use of high-precision positioning systems enables cavity loss mapping by transversely scanning the position of the cavity end mirror. Mirror surfaces of up to 30mm in diameter can be scanned, and the cavity length can be tuned by 120mm.

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.

PurposeAdditive manufacturing is a recent technology used in the production of composite materials. The use of continuous fibres as reinforcement is necessary to achieve high mechanical performance. However, making these materials more environmentally friendly is still challenging. The purpose of this study was to investigate the feasibility of 3D printing a composite made of continuous regenerated cellulose fibres using a standard 3D printer generally used for printing polymers.Design/methodology/approachThe production process was based on a pre-impregnated filament made from a tape containing continuous cellulose fibres and Pebax® matrix. 3D printed composite samples were fabricated using fused deposition modelling. The tape, filament and 3D printed composites were first analysed by means of modulated differential scanning calorimetry and micrography. Tensile tests were then performed, and the mechanical characteristics were determined at each step of the production process. Fracture surfaces were investigated by field-emission gun–scanning electron microscopy.FindingsResults showed that the mechanical behaviour of the material was maintained throughout the production process, and the 3D printed biocomposites had a stiffness equivalent to that of traditionally manufactured continuous cellulose fibre composites. The obtained 3D printed composites showed an increase in strength value by a factor of 4 and in tensile modulus by a factor of 20 compared to those of unreinforced Pebax® polymer.Originality/valueThis paper demonstrates the feasibility of 3D printing composites based on continuous cellulose fibres, paving the way for new biocomposites made by additive manufacturing.

The Einstein Telescope (ET), the European project for a third-generation gravitational-wave detector, has a reference configuration based on a triangular shape consisting of three nested detectors with 10 km arms, where each detector has a 'xylophone' configuration made of an interferometer tuned toward high frequencies, and an interferometer tuned toward low frequencies and working at cryogenic temperature. Here, we examine the scientific perspectives under possible variations of this reference design. We perform a detailed evaluation of the science case for a single triangular geometry observatory, and we compare it with the results obtained for a network of two L-shaped detectors (either parallel or misaligned) located in Europe, considering different choices of arm-length for both the triangle and the 2L geometries. We also study how the science output changes in the absence of the low-frequency instrument, both for the triangle and the 2L configurations. We examine a broad class of simple 'metrics' that quantify the science output, related to compact binary coalescences, multi-messenger astronomy and stochastic backgrounds, and we then examine the impact of different detector designs on a more specific set of scientific objectives.

In this work, optical profilometry and finite-element simulations are applied on buckled micromachined membranes for the stress analysis of ion-beam-sputtered Ta2O5 and SiO2 thin films. Layers with different thicknesses are grown on silicon substrates, and then several membranes with different geometries are manufactured with standard microsystem technologies; due to a high level of films’ compressive stress, buckled membranes are obtained. Thermally grown silica membranes are also produced for comparison. The residual stress values are determined by comparing the measured and simulated deflections of the membranes. The average stress state of Ta2O5 thin films is found to be −209 MPa. The SiO2 thin films are in a higher compressive stress state whose average value is −576 MPa. For comparison, the average stress in thermal SiO2 thin layers grown at 1130°C is found equal to −321 MPa, in good agreement with the literature.

Abstract The presence of geometric discontinuity in a material reduces considerably its resistance to mechanical stresses, therefore reducing the service life of materials. The analysis of structural behaviour in the presence of geometric discontinuities is important to ensure the proper use, especially if it is regarding a material of weak mechanical properties such as a polymer. The objective of the present work is to analyse the effect of the notch presence of variable geometric shapes on the tensile strength of epoxy-type polymer specimens. A series of tensile tests were carried out on standardised specimens, taking into account the presence or absence of a notch. Each series of tests contains five specimens. Two notch shapes were considered: circular (hole) and elliptical. The experimental results in terms of stress–strain clearly show that the presence of notches reduces considerably the resistance of the material, where the maximum stress for the undamaged specimen was 41.22 MPa and the lowest stress for the elliptical-notched specimen was 11.21 MPa. A numerical analysis by the extended finite element method (XFEM) was undertaken on the same geometric models; in addition, the results in stress–strain form were validated with the experimental results. A remarkable improvement was obtained (generally an error within 0.06%) for strain, maximum stress, Young’s modulus and elongation values. An exponential decrease was noted in the stress, strain, and Young’s modulus in the presence of a notch in the material.

The one dimensional polymer complex (C9H15N3)[CdCl4], was synthesized and characterized by X-ray crystallography, FT-IR vibrational, and thermal analysis, UV–Visible and photoluminescence (PL) spectroscopic investigations. The crystal structure crystallizes in the monoclinic space group C2/c with Z = 4. The experimental geometric data of the crystalline molecule and the results of density functional theory (DFT) generated utilizing computational methods at DFT/ωB97XD and DFT/B3LYP-D3/Gen/6-311++G(d, p)//LanL2DZ levels of theory were compared. Significantly, in order to reveal the vibrational modes of the named chemical, the Infrared and Raman spectra were registered. Then, 13C and 113Cd solid-state NMR was employed to characterize this hybrid material using a polar solvent to conduct an investigation of the optical characteristics for the UV–visible range. Consequently, utilizing the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO–LUMO) calculations, the molecule’s energy gap (Eg) was determined. More so, the PL tests revealed two peaks at about 400 and 423 nm while the Hirshfeld surface (HS) analysis and DFT calculations were also carried out to acquire insight into the role of weak molecular interactions in the complex that affect the self-assembly process and crystal packing. In addition, molecular docking experiments with the 6U3Y, 1SAX, and 2D45 receptors reveal ideal postures with intriguing binding affinities of −5.2, −5.6, and −5.7 kcal.mol−1, respectively. Lastly, thermo-differential analysis techniques (DTA) and thermogravimetric analysis techniques (TGA) were used to account for the thermal degradation of the current complex.