Modelling the mechanical response of Japanese lacquer (urushi) to varying environmental conditions

Urushi is a complex natural polymer that has been used to protect and decorate objects for many hundreds of years. Urushi is an important material as decorated objects can obtain great value and historical worth. A star item of urushi lacquerwares, the Mazarin Chest, property of Victoria & Albert (V&A) Museum in London, is famous as one of the finest pieces of Japanese lacquerware in the world, dating back to as early as the late 1630s. These urushi lacquerwares are often exposed to environments that are detrimental to both their aesthetic appeal and structural performance, and restoration and conservation procedures are needed to preserve these objects over long periods of time. However, the precise behaviour of urushi lacquers is not sufficiently understood to allow accurate prediction of the material response to environmental effects or of the effectiveness of any proposed conservation procedure. Thus a need exists for a comprehensive understanding of this material and a finite element (FE) model to predict the mechanical response to varying environmental conditions. The aim of this research was to model the hygro-mechanical effects during the environmental ageing process of urushi films by means of FE modelling, which will help to make decisions about the environmental conditions required for storage and exhibition. This was achieved by a combination of experimental and computational methods. A synthetic thermosetting (crosslinked) lacquer, polyurethane (PU), was initially studied to develop the methodology of the experimental and numerical studies and to provide a comparison to the natural lacquer. Experimental work was carried out to characterise the material behaviour of both materials, such as hygroscopic expansion, moisture diffusion kinetics and mechanical behaviour under various environmental conditions. Moisture diffusion in the two lacquer films was well described by Fick s law. However, different sorption isotherm models, Flory-Huggins model for PU and Guggenheim-Anderson-de-Boer (GAB) model for urushi, were required to model the equilibrium sorption of these two materials. The mechanical properties of the lacquer films were found to have a complex dependence on environmental conditions. The tensile properties of both lacquer films were shown to change significantly after UV ageing. With increasing time of ultraviolet (UV) irradiation, Young s Modulus and tensile strength increased dramatically, but the maximum strain decreased. With water absorption, both Young s modulus and tensile strength decreased, and maximum strain increased. The two lacquer films were found to behave with a non-linear viscoelasticity, which was highly dependent on environmental conditions. A modified Burger s model was found to provide a good fit to experimental creep data for the PU lacquer well at different stress levels, suggesting this is a satisfactory method for characterising PU rheological behaviour. A novel modified generalized Kelvin fluid (MGKF) model was found to be a powerful non-linear viscoelastic model capable of representing the rheological behaviour of the urushi below the yield stress. However, in order to include the post yield behaviour a visco-elastic-plastic model is required. A hygro-mechanical model of the urushi behaviour based on the MGKF viscoelastic model was developed and tested. Through careful determination of the mechanical behaviour the constitutive properties of a thin layer of lacquer were determined and used as an input to a FE based model of the deformation and stresses that develop in response to changes in the environmental conditions. The model was validated using experimental results that showed the depth averaged stress in a thin layer deposited on a glass substrate, which allowed insight into the time dependent and spatially varying stresses within the layer. It was shown that the regions of highest stress were found in areas of highest moisture ingress, emphasising the need for control of the environment in which urushi covered artefacts are stored. In order to perform a predictive study on the bending behaviour of urushi films with cracks, as can be seen in aged lacquers, a model with a grooved urushi film on an aluminium substrate was created and subjected to bending loads. The time-dependency of the urushi material properties seems to hardly affect the bending behaviour of the model, however, the profile of the displacement field around the groove was found to be considerably affected by the geometry of the groove. To evaluate the effectiveness of a traditional Japanese consolidation method for lacquerware objects, known as urushi-gatame, a strain-based progressive damage failure model was used to model the continuum failure in the bi-material strip under an increasing bending load. The behaviour of damage initiation and evolution was modelled for an unfilled groove, a filled groove with fresh filler and filled groove with UV aged filler. From the finite element analysis (FEA) results, the introduction of the filler, as a simple mimic of the consolidation method, does enable the strip to sustain a higher bending load. However, this effectiveness is weakened as the material is aged, with it behaving similar to a groove without any filler

A Multi-Robot Cooperation Framework for Sewing Personalized Stent Grafts

This paper presents a multi-robot system for manufacturing personalized medical stent grafts. The proposed system adopts a modular design, which includes: a (personalized) mandrel module, a bimanual sewing module, and a vision module. The mandrel module incorporates the personalized geometry of patients, while the bimanual sewing module adopts a learning-by-demonstration approach to transfer human hand-sewing skills to the robots. The human demonstrations were firstly observed by the vision module and then encoded using a statistical model to generate the reference motion trajectories. During autonomous robot sewing, the vision module plays the role of coordinating multi-robot collaboration. Experiment results show that the robots can adapt to generalized stent designs. The proposed system can also be used for other manipulation tasks, especially for flexible production of customized products and where bimanual or multi-robot cooperation is required.Comment: 10 pages, 12 figures, accepted by IEEE Transactions on Industrial Informatics, Key words: modularity, medical device customization, multi-robot system, robot learning, visual servoing, robot sewin

Table_1_Trends in economic burden of type 2 diabetes in China: Based on longitudinal claim data.DOCX

ObjectiveDiabetes is a major health issue in China that has a significant economic burden on society. Understanding the economic impact of diabetes can help policymakers make informed decisions about healthcare spending and priorities. This study aims to estimate the economic burden of patients with diabetes in an urban setting in China and to identify the impact of hospitalization and complications on health care costs for people with diabetes.MethodsThe study was conducted in a sample city located in eastern China. All patients diagnosed with diabetes before January 2015 were identified from the official health management information system, and their social demographics and records of their health care uses and costs were extracted from the claim database from 2014 to 2019. Six groups of complications were identified according to ICD-10 codes. The diabetes-related direct medical cost (DM cost) was described for patients in stratified groups. A multiple linear regression model was applied to identify the effect of hospitalization and complications on the DM cost of diabetic patients.ResultsOur research included 44,994 patients with diabetes, the average annual DM costs for diabetic patients increased from 1,292.72 USD in 2014 to 2,092.87 USD in 2019. The costs of diabetes are closely related to hospitalizations and the type and number of complications. The average annual DM cost of patients who were hospitalized was 2.23 times that of those without hospitalization, and it rose as the number of complications increased. Cardiovascular complications and nephropathic complications were the complications that had the greatest impact on patients’ DM costs, increasing by an average of 65 and 54%, respectively.ConclusionThe economic burden of diabetes in urban China has increased significantly. Hospitalization and the type and number of complications have significant impacts on the economic burden of patients with diabetes. Efforts should be made to prevent the development of long-term complications in the population with diabetes.</p

Prediction of PPI not included in the models on variant species by using “Multiple Query” mode^a.

a<p>Protein1 and Protein2 represent two query proteins in “Multiple Query” mode respectively.</p>b<p>Reference number for experiment validation.</p

Machine Learning-Assisted Design of Thin-Film Composite Membranes for Solvent Recovery

Organic solvents are extensively utilized in industries as raw materials, reaction media, and cleaning agents. It is crucial to efficiently recover solvents for environmental protection and sustainable manufacturing. Recently, organic solvent nanofiltration (OSN) has emerged as an energy-efficient membrane technology for solvent recovery; however, current OSN membranes are largely fabricated by trial-and-error methods. In this study, for the first time, we develop a machine learning (ML) approach to design new thin-film composite membranes for solvent recovery. The monomers used in interfacial polymerization, along with membrane, solvent and solute properties, are featurized to train ML models via gradient boosting regression. The ML models demonstrate high accuracy in predicting OSN performance including solvent permeance and solute rejection. Subsequently, 167 new membranes are designed from 40 monomers and their OSN performance is predicted by the ML models for common solvents (methanol, acetone, dimethylformamide, and n-hexane). New top-performing membranes are identified with methanol permeance superior to that of existing membranes. Particularly, nitrogen-containing heterocyclic monomers are found to enhance microporosity and contribute to higher permeance. Finally, one new membrane is experimentally synthesized and tested to validate the ML predictions. Based on the chemical structures of monomers, the ML approach developed here provides a bottom-up strategy toward the rational design of new membranes for high-performance solvent recovery and many other technologically important applications

The top 10 potential protein partners of FBXO6 in human by SPPS “Single Query” search.

<p>The top 10 potential protein partners of FBXO6 in human by SPPS “Single Query” search.</p

An overview of SPPS server.

<p>An overview of SPPS server.</p

Ultrahigh Conductivity in Two-Dimensional InSe via Remote Doping at Room Temperature

Conductivity of two-dimenstional (2D) materials, which largely determines the efficiency and reliability of nanodevices, is proportional to the product of carrier concentration and mobility. Conventional doping, such as ionic substitution or introduction of vacancies, increases carrier concentration and decreases carrier mobility due to the scattering or trapping of carriers. We propose a remote-doping strategy that enables the simultaneous enhancement of both parameters. Density functional theory calculations in 2D InSe reveal that adsorbing the molecule tetrathiafulvalene (TTF) and applying a 4% external tensile strain leads to an increase in the carrier concentration of the TTF-InSe system that is 13 orders of magnitude higher than that of the pristine counterpart, whereas the carrier mobility is enhanced by 35% compared with the InSe monolayer. As a consequence of the synergetic role of molecule doping and strain engineering, ultrahigh conductivity of 1.85 × 10⁵ S/m is achieved in the TTF-InSe system at room temperature

Data_Sheet_1_Climate and vegetation and their impact on stable C and N isotope ratios in bat guano.zip

Cave guano deposits represent a relatively untapped paleoecological archive that can provide information about past vegetation, climate, and bat diet over several millennia. Recent research suggests that carbon isotope values (δ13C) measured in guano accumulations from insectivorous bats reflect the relative abundance of C3 and C4 plants on the landscape while nitrogen isotope values (δ15N) may reflect precipitation amount. Together, these proxies can provide useful information for restoration practitioners seeking to understand how plant species composition has changed over time in relation to climate and land use. To better calibrate these proxies for use in restoration, we compared instrumental records of precipitation and satellite imagery of vegetation with isotope values measured in modern bat guano from Mary Lawson Cave, a large limestone cavern located in central Missouri. Mary Lawson Cave hosts a maternity colony of insectivorous gray bats (Myotis grisescens), and as such, contains significant guano accumulations. In the fall of 2018, we collected a 60 cm long guano core that dates to 1999 cal AD at its base. Guano core δ13C values decrease from the base toward the surface (from ~-26 to -27‰) whereas δ15N values increase toward the surface even after accounting for ammonia volatilization (from ~3 to 5‰). Presently, the landscape around Mary Lawson Cave is dominated by a deciduous forest and pasture. Given that the land cover has changed very little over this period, the decline in δ13C values toward the present likely reflects a shift in land management on farms and/or increases in invasive C3 species. Rainfall amounts from nearby Lebanon, Missouri, are significantly positively correlated with guano δ15N values, a relationship that is notably opposite that observed previously in soil and plants. We argue that heavy fertilizer application and significant grazing intensity could lead to the accumulation of large pools of excess labile nitrogen which would be vulnerable to leaching during precipitation events. The relationship between guano δ15N values and precipitation may differ for materials from less agriculturally impacted locations or periods and should be extended into the past with caution.</p

Additional file 1 of The creation and validation of predictive models to assess the risk of unfavorable outcomes following hybrid total arch repair for Stanford type A aortic dissection

Supplementary Material 1: Supplementary File 1. Supplementary data for the study populatio