An Adaptable Ct-Derived 3D-Printed Alignment Fixture Minimizes Errors in Whole-Bone Biomechanical Testing

Biomechanical testing of long bones can be subject to undesirable errors and uncertainty due to malalignment of specimens with respect to the mechanical axis of the test frame. To solve this problem, we designed a novel, customizable alignment and potting fixture for long bone testing. The fixture consisted of 3D-printed components modeled from specimen-specific CT scans to achieve a predetermined specimen alignment. We demonstrated the functionality of this fixture by comparing benchtop torsional test results to specimen-matched finite element models and found a strong and statistically significant correlation (R2 = 0.9536, p < 0.001). Additional computational models estimated the impact of malalignment on mechanical behavior in both torsion and axial compression. Results confirmed that torsion testing is relatively robust to alignment artifacts, with absolute percent errors less than 8% in all malalignment scenarios. In contrast, axial testing was highly sensitive to setup errors, experiencing absolute percent errors up to 40% with off-center malalignment and up to 130% with angular malalignment. This suggests that whenever appropriate, torsion tests should be used preferentially as a summary mechanical measure. When more challenging modes of loading are required, pre-test clinical-resolution CT scanning can be effectively used to create potting fixtures that allow for precise pre-planned specimen alignment. This may be particularly important for more sensitive biomechanical tests (e.g. axial compressive tests) that may be needed for industrial applications, such as orthopaedic implant design.

An image analysis method for determining boiling front in minichannel heat exchanger

In this work a numerical method for determining boiling front in short time period of flow was presented. A non-stationary boiling in rectangular eleven minichannels (0.25 mm x 0.25 mm x 32 mm) was recorded using Phantom v1610 high speed camera with the speed of 6000 fps. In the algorithm correlation between subsequent frames was computed. Frames were divided into reference and test frames. In each iteration a part of a reference frame called ‘reference gate’ and moving part of a test frame called ‘moving gate’ were considered. A two-dimensional correlation coefficient was calculated. Such method allowed to identify the location of boiling front in each minichannel separately.

A Frame-Theoretic Model of Bayesian Category Learning

Bayesian models of category learning typically assume that the most probable categories are those that group input stimuli together around a maximally optimal number of shared features. One potential weakness of such feature list approaches, however, is that it is unclear how to weight observed features to be more or less diagnostic for a given category. In this theoretically oriented paper, we develop a frame-theoretic model of Bayesian category learning that weights the diagnosticity of observed attribute values in terms of their position within the structure of a frame (formalised as distance from the frame’s central node). We argue that there are good grounds to further develop and empirically test frame-based learning models, because they have theoretical advantages over unweighted feature list models, and because frame structures provide a principled means of assigning weights to attribute values without appealing to supervised training data.

On the lifetime of bioinformatics web services

Web services are used through all disciplines in life sciences and the online landscape is growing by hundreds of novel servers annually. However, availability varies, and maintenance practices are largely inconsistent. We screened the availability of 2396 web tools published during the past 10 years. All servers were accessed over 133 days and 318 668 index files were stored in a local database. The number of accessible tools almost linearly increases in time with highest availability for 2019 and 2020 (∼90%) and lowest for tools published in 2010 (∼50%). In a 133-day test frame, 31% of tools were always working, 48.4% occasionally and 20.6% never. Consecutive downtimes were typically below 5 days with a median of 1 day, and unevenly distributed over the weekdays. A rescue experiment on 47 tools that were published from 2019 onwards but never accessible showed that 51.1% of the tools could be restored in due time. We found a positive association between the number of citations and the probability of a web server being reachable. We then determined common challenges and formulated categorical recommendations for researchers planning to develop web-based resources. As implication of our study, we propose to develop a repository for automatic API testing and sustainability indexing.

Adding RFC 4814 Random Port Feature to Siitperf: Design, Implementation and Performance Estimation

Siitperf is the World’s first free software RFC 8219 compliant SIIT (also called stateless NAT64) tester written in C++ using DPDK, which is also suitable for benchmarking IPv4 / IPv6 network interconnect devices in RFC 2544 / RFC 5180 compliant ways. Originally, siitperf followed RFC 2544 Appendix C.2.6.4 test frame format resulting in “hard coded” source and destination UDP port numbers. RFC 4814 Section 4.5 recommended random, uniformly distributed source and destination port numbers, which can make a very significant difference, when the DUT (Device Under Test) has multiple CPU cores, what is very common today. Therefore, adding this feature to siitperf is essential to be able to produce meaningful benchmarking results. In this paper, we disclose the design, implementation and performance estimation of this extension of siitperf.

Damage evaluation of a full-scale RC frame exposed to multiple extreme loads

Purpose The occurrence of multiple hazards in extreme conditions is not unknown nowadays, but the sustainability of the reinforced concrete structures under such scenarios form competitive challenges in civil engineering profession. Among all, fire following earthquake (FFE) is categorized under multiple extreme load scenarios which causes sequential damages to the structures. This paper aims to experiment a full-scale RC frame sub-assemblage for the FFE scenario and assess each stage of damage through the nondestructive testing method. Design/methodology/approach Two levels of simulated earthquake damages, i.e. immediate occupancy (IO) level and life safety (LS) level of structural performance were induced to the test frame and then, followed by a realistic compartment fire of 1 h duration. Also, the evaluation of damage to the RC frame after the fire subsequent to the earthquake was carried out by obtaining the ultimate capacity of the frame. Ultrasonic pulse velocity and rebound hammer test were conducted to assess the structural endurance of the damaged frame. Cracks were also marked during mechanical damages to the test frame to study the nature of its propagation. Findings Careful visual inspection during and after the fire test to the test frame were done. To differentiate between concrete chemically affected by the fire or physically damaged is an important issue. In situ inspection and laboratory tests of concrete components have been performed. Concrete from the test frame was localized with thermo-gravimetric analysis. The UPV results exhibited a sharp decrease in the strength of the concrete material which was also confirmed via the DTA, TGA and TG results. It is important to evaluate the residual capacity of the entire structure under the FFE scenario and propose rehabilitation/retrofit schemes for the building structure. Research limitations/implications The heterogeneity in the distribution of the damage has been identified due to variation of fire exposure. The study only highlights the capabilities of the methods for finding the residual capacity of the RC frame sub-assemblage after an occurrence of an FFE. Originality/value It is of find kind of research work on full-scale reinforced concrete building. In this, an attempt has been made for the evaluation of concrete structures affected by an FFE through nondestructive and destructive methods.

Rapid Retrofit of Reinforced Concrete Frames after Progressive Collapse to Increase Sustainability

A structural progressive collapse is usually a local failure, in which the damage is concentrated at beams that bridge the removal column and the column itself. In many cases, retrofitting the damaged structure is more economical and more sustainable than reconstructing the entire structure. A progressive collapse test of a 1/3 scale, four-bay by two-story reinforced concrete (RC) frame was conducted, after which the structure was retrofitted with carbon fiber reinforced polymer (CFRP) wraps and retested. The center column in the first story was removed and the frame was pushed down quasistatically under displacement control to investigate the progressive collapse performances of the retrofitted RC frame. The test results were represented systematically at different areas in terms of the resistance forces, crack developments, and local and global failure modes. Numerical models were built to verify the test frame before and after the retrofitting. A design method was proposed to retrofit an RC frame using CFRP wraps after a progressive collapse. The test frame was redesigned to improve the retrofitting and used as an example to demonstrate the rationality of the proposed retrofit design method. The results indicated that the proposed retrofitting technology rapidly restored the frame structure to its original capacity before the progressive collapse occurred, whilst consistently satisfying the priorities of being economical and sustainable.

Gold Nanorod Integrated Electrochemical Sensing for Hyperglycaemia on Interdigitated Electrode

Gestational diabetes (hyperglycaemia) is an elevated blood sugar level diagnosed during the period of pregnancy and affects the baby’s health. Hyperglycaemia has been found within the gestational weeks between 24 and 28, and the foetus has also the possibility of getting out prior to this test frame; it causes excessive birth weight, early birth, low-blood sugar level, respiratory distress syndrome, and type-2 diabetes to the mother. It creates a mandatory situation to identify the hyperglycaemia at least during the pregnancy weeks from 18 to 20. Further, a continuous monitoring of the level of glucose is necessary for the proper delivery. In this work, a method is introduced for glucose detection at 0.06 mg/mL, assisted by gold nanorod (GNR)-conjugated glucose oxidase (GOx) on interdigitated electrode sensor. In the absence of GNR, GOx shows the limit of glucose detection to be 0.25 mg/mL. Moreover, with GOx-GNR the reactions of all the glucose concentrations have recorded higher levels of the current from the baseline. With the specificity analysis, it was found that the glucose only reacts with GOx-GNR and discriminates other sugars efficiently. This method of detection is useful to diagnose and continuously monitor the glucose level during the pregnancy period.