Observation of damage initiation for trans-laminar fracture using in situ fast synchrotron x-ray radiography and ex situ x-ray computed tomography

Trans-laminar fracture is an important topic for engineering composites. In this study, trans-laminar fracture initiation in quasi-isotropic carbon/epoxy laminates made of non-crimp fabrics was examined using in situ fast synchrotron X-ray radiography and ex situ X-ray computed tomography. The maximum split lengths were measured by in situ radiography and were compared with the predicted values in a detailed FE model using cohesive elements. Ex situ computed tomography scans were also conducted to confirm that no fibre breakage occurs before the final load drop in the experiments. In situ and ex situ observations are complementary for the understanding of damage initiation

Cost-effective fabrication of bio-inspired nacre-like composite materials with high strength and toughness

A cost-effective one-step densification process based on bi-directional freeze casting was investigated to produce nacre-like alumina/poly (methyl methacrylate) (PMMA) composites with a unique micro-layered (μL) architecture. This method has the advantage of shorter processing time, as it requires only sintering once instead of twice as in the fabrication of conventional brick-and-mortar (BM) composites via freeze casting. By tuning the processing parameters, composites with different ceramic content and layer thickness were obtained. The resultant mechanical properties of μL composites showed that ceramic content and wall thickness affected mechanical properties significantly. The μL composite with fine ceramic walls (8 μm) and relatively high ceramic fraction (72 vol%) exhibited an exceptional combination of high flexural strength (178 MPa) and fracture toughness (12.5 MPa m1/2). The μL composites were also compared with the conventional BM composites. Although the fracture behaviour of both composites exhibited similar extrinsic toughening mechanisms, the μL composites with longer ceramic walls displayed superior mechanical properties in terms of strength and fracture toughness in comparison with the BM composites comprising short ceramic walls (i.e. bricks), due to the effectiveness of stress transfer of load-bearing ceramic phase within the composites

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

An investigation into placemaking for the new SUB : board games & graffiti wall

Upon the new scheduled opening of the AMS new Student Union Building, restaurants, and social spaces will be released for students to occupy. In an attempt to connect all students into engaging and using the new Student Union Building as a vibrant social lounge space, different types of entertainment are being considered. The purpose of this report is to define the process of placemaking in the new SUB while assessing triple bottom line analysis on interactive board games and graffiti walls; the analysis consists of an economic, social, and environmental assessment. Research through these sections was gathered through academic papers, websites, and primary survey sources. Two different types of entertainment solutions are reviewed; these are interactive electronic design walls for creating ideas and the other are board games for leisure purposes. A thorough analysis of each type of entertainment set was performed to focus on the economic effect, durability of each entertainment categories, and the social aspects for each type. This report concludes that design boards are more suitable for engaging students with one another in the new SUB. The design board walls are easily erased and replaced, economically saving in a long term, and also more durable with less individual pieces, meeting all requirements in the desired triple line assessment. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”Applied Science, Faculty ofUnreviewedUndergraduat

4D microstructural changes in dentinal tubules during acid demineralisation

Objective Dental erosion is a common oral condition caused by chronic exposure to acids from intrinsic/extrinsic sources. Repeated acid exposure can lead to the irreversible loss of dental hard tissues (enamel, dentine, cementum). Dentine can become exposed to acid following severe enamel erosion, crown fracture, or gingival recession. Causing hypersensitivity, poor aesthetics, and potential pulp involvement. Improving treatments that can restore the structural integrity and aesthetics are therefore highly desirable. Such developments require a good understanding of how acid demineralisation progresses where relatively little is known in terms of intertubular dentine (ITD) and peritubular dentine (PTD) microstructure. To obtain further insight, this study proposes a new in vitro method for performing demineralisation studies of dentine. Methods Advanced high-speed synchrotron X-ray microtomography (SXM), with high spatial (0.325 µm) and temporal (15 min) resolution, was used to conduct the first in vitro, time-resolved 3D (4D) study of the microstructural changes in the ITD and PTD phases of human dentine samples (~0.8×0.8×5 mm) during 6 h of continuous acid exposure

Neutron Bragg edge tomography characterisation of residual strain in a laser-welded Eurofer97 joint

Nuclear fusion is a potential source of electricity which can address the environmental problems posed by fossil fuels. Eurofer97 steel is a primary structural material for breeding blanket and divertor components in fusion Tokamaks. Assembling and maintaining the structural integrity of these in-vessel components requires remote joint techniques, such as laser welding, although it induces immersive residual stress. The interaction of the residual strain and the heterogeneous microstructure degrades the mechanical performance of fusion components. However, an inspection of bulk residual strain distribution is still challenging. This study presents the residual strain distribution in the bulk of the weldment using volumetric tomographic reconstruction. A neutron Bragg edge imaging technique is used to obtain 2D angular projections. The 3D volumetric strain map is reconstructed from 2D residual strain projections using the filtered back projection technique. It is found that the laser welding technique generates a uniform residual strain field in the through-thickness direction. The results also demonstrate the potential of reconstructing volumetric residual strain distribution in bulk materials using fewer projections to reduce data redundancy and acquisition time for the neutron Bragg edge imaging technique

Multi-scale structural and mechanical characterisation in bioinspired polyurethane-based pancreatic cancer model

In this work, novel bioinspired polyurethane (PU) scaffolds were fabricated via freeze casting for PU-based Pancreatic Ductal Adenocarcinoma (PDAC) model. In order to reproduce the tumour micro-environment that facilitates cellular kinetics, the PU scaffolds were surface modified with extracellular matrix (ECM) proteins including collagen and fibronectin (Col and FN). Synchrotron-based small- and wide-angle X-ray scattering (SAXS/WAXS) techniques were applied to probe structural evolution during in situ mechanical testing. Strains at macroscopic, nano-, and lattice scales were obtained to investigate the effects of ECM proteins and pancreatic cell activities to PU scaffolds. Significant mechanical strengthening across length scales of PU scaffolds was observed in specimens surface modified by FN. A model of stiffness modulation via enhanced interlamellar recruitment is proposed to explain the multi-scale strengthening mechanisms. Understanding multi-scale deformation mechanisms of a series of PU scaffolds opens an opportunity in developing a novel pancreatic cancer model for studying cancer evolution and predicting outcomes of drug/treatments

The use of time-of-flight neutron Bragg edge imaging to measure the residual strains in W/Cu dissimilar joints for fusion reactors

The European DEMOnstration power plant (EU DEMO) project is currently leading the research endeavours within the fusion field with the goal of developing a next generation fusion reactor. Given the challenging nature of the application, it is essential to establish methodologies that can provide convenient and reliable characterisation of the chosen materials within DEMO. In this paper, the recently developed Time-of-Flight Neutron Bragg Edge Imaging (TOF-NBEI) was used on Tungsten (W)/ Copper (Cu) dissimilar joints sample mock-ups of the cooling system design used in the critical divertor component with the goal of mapping the residual stresses across the sample. Residual strain mapping was performed on the W phase with considerable tensile residual strains identified close to the W-Cu interface. The large-grain microstructure of the Cu phase was analysed using the energy-resolved neutron radiographs. The results will be used as a basis for future TOF-NBEI experiments of tungsten monoblocks related to DEMO