bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on High Voltage Protection of Arc Thruster Power Control Unit
Authors: Peng Zheng , Li Zongliang , Li Ze , Song Fei , Li Zhong , Liu Yizhuo
Published: August 2023

The arc propulsion system needs a high-voltage (3800 V) pulse to break down the working medium in the thruster and form a stable arc. The arc thruster power control unit (ATPU) is prone to producing high voltage discharge when the high voltage pulse is output. According to the high voltage breakdown mechanism, this paper puts forward control measures to prevent the high voltage breakdown.
LEO Satellite Localization of Receiver in Motion Using Signal Frequency of Arrival
Authors: Guo Fangfang , Shen Yuyao
Published: August 2023

This study presents a localization algorithm for moving the receiver based on LEO satellite downlink Doppler signals. This algorithm could provide an alternative to pseudo-range based GNSS. Considering the asynchrony between satellites and the existence of a relative clock skew, we used sequential measurements at multiple receiving moments to obtain a sufficient number of observations. And we performed motion offset compensation for the receiver position and velocity at different moments. Simulation results show that the algorithm can achieve good localization accuracy.
A Digital Twin Based Residual Stress Prediction Method for Turbine Blades
Authors: Mou Sheng , Bu Kun , Liu Jun , Ren Shengjie , Zhang Ruiyuan , Bai Boxian
Published: August 2023

The investment casting process is the conventional method for manufacturing turbine blades, and the residual stress generated through this process is widely regarded as a critical factor that markedly impacts the quality and serviceability of turbine blades. However, real-time measurement of residual stress is extremely complex and expensive, especially for single-crystal turbine blades. Current experimental measurement techniques such as X-ray or neutron diffraction can only measure residual stresses at specific points or within a very small area. Studies on residual stress of turbine blades are mainly performed by finite element (FE) simulation, but the accuracy is difficult to guarantee due to the inability to establish accurate mathematical models for complex physical systems. To address this issue, this paper proposes utilizing a digital twin (DT) model to predict residual stresses in turbine blades. By combining real-time sensor and FE simulation data, the DT model is able to update and correct the mathematical models, resulting in more accurate predictions compared to traditional FE simulations.
A Fast Image Matching Method Based on Improved SURF
Authors: Jiang Haili , Liu Panpan , Yang Qingqing , Xu Liang , Zhang Shuai
Published: August 2023

In order to solve the problems of low matching accuracy, slow speed and high system overhead in image matching methods, a rotation binary descriptor construction method based on Speed Up Robust Features (SURF) feature point detection is designed by using different Fast Library for Approximate Nearest Neighbors (FLANN) parameters and the filtering mechanism to screen out wrong matches according to the types of feature descriptors constructed in different feature extraction algorithms. This method ensures scale and rotation invariant while simplifying the representation of feature descriptors and speeding up the calculation speed in the initial stage of matching by combining the binary characteristics of descriptors. Finally, the Hamming distance is used as the filtering mechanism to improve the success rate of the final matching. The experimental results show that the accuracy of image matching is improved by 1.5% and the matching time is improved by 0.116s, while the robustness of the image to noise and rotation is ensured.
Early warning signals of changing resilience in the biogeochemistry and biology of a northern hardwood forest
Authors: Contosta Alexandra R , Battles John J , Campbell John L , Driscoll Charles T , Garlick Sarah R , Holmes Richard T , Likens Gene E , Rodenhouse Nicholas L , Rogers Shannon H , Templer Pamela H , Vadeboncoeur Matthew A , Groffman Peter M
Published: August 2023

Resilience is the ability of ecosystems to maintain function while experiencing perturbation. Globally, forests are experiencing disturbances of unprecedented quantity, type, and magnitude that may diminish resilience. Early warning signals are statistical properties of data whose increase over time may provide insights into decreasing resilience, but there have been few applications to forests. We quantified four early warning signals (standard deviation, lag-1 autocorrelation, skewness, and kurtosis) across detrended time series of multiple ecosystem state variables at the Hubbard Brook Experimental Forest, New Hampshire, USA and analyzed how these signals have changed over time. Variables were collected over periods from 25 to 55 years from both experimentally manipulated and reference areas and were aggregated to annual timesteps for analysis. Long-term (>50 year) increases in early warning signals of stream calcium, a key biogeochemical variable at the site, illustrated declining resilience after decades of acid deposition, but only in watersheds that had previously been harvested. Trends in early warning signals of stream nitrate, a critical nutrient and water pollutant, likewise exhibited symptoms of declining resilience but in all watersheds. Temporal trends in early warning signals of some of groups of trees, insects, and birds also indicated changing resilience, but this pattern differed among, and even within, groups. Overall, ∼60% of early warning signals analyzed indicated decreasing resilience. Most of these signals occurred in skewness and kurtosis, suggesting ‘flickering’ behavior that aligns with emerging evidence of the forest transitioning into an oligotrophic condition. The other ∼40% of early warning signals indicated increasing or unchanging resilience. Interpretation of early warning signals in the context of system specific knowledge is therefore essential. They can be useful indicators for some key ecosystem variables; however, uncertainties in other variables highlight the need for further development of these tools in well-studied, long-term research sites.
A study on stabilizing mechanism of flap countermeasures mitigating VIV of a box girder bridge section
Authors: Tam Phan Duc , Katsuchi Hiroshi , Jiaqi Wang , Tamura Hiroshi , Hirao Kensho
Published: August 2023

As bridge spans stretch, the structure becomes more flexible and susceptible to dynamic wind effects causing harmful wind-induced vibration. The biggest issue with the design of long-span bridges is the possibility of vibration caused by vortices. This study examines the mechanism of the decrease in the amplitude of vortex-induced vibration for the box girder using a flap countermeasure. Aerodynamic countermeasures such as a flap have successfully increased bridge deck aerodynamic stability. However, their stabilizing mechanism has yet to be fully understood. Based on the proposed approach, a wind tunnel experiment and a CFD technique are used to investigate the aerodynamic instability of the bridge girder in the presence of aerodynamic countermeasures. The flow fields surrounding the bridge deck, both with and without the flap, are examined, and the experiment outcomes are compared. Flow imagery is utilized to explain and understand the modified flow properties surrounding the bridge girder in the presence of aerodynamic countermeasures that minimize vibration amplitude. Indeed, installing flaps on a girder leads to increased turbulence over the surface and at the leeward side, which disrupts vortex formation and decreases lift forces on the structure. In addition, the results revealed that the efficiency of the flap is related to the installed location of the flap and the flap length. This research provides a reliable framework for designing the flap countermeasure and significantly improves the aerodynamic stability of a deck-flap system.
Buckling analysis of functionally graded plates in thermal environment by using a meshfree method
Authors: Ngo Binh Khanh , Le Tel Doc Tu , Lo Vay Siu , Nguyen Vy Khac , Truong Thien Tich
Published: August 2023

In material, the pre-stress state caused by temperature variation of the working environment is one of the main reasons which cause buckling in structures. This paper aims to analyse the critical temperature rise to cause buckling in functionally graded material (FGM) under different boundary conditions. Reissner-Mindlin plate theory is employed in this paper with the radial point interpolation method (RPIM). The RPIM has the advantage compared to other meshfree methods in the satisfaction of the Kronecker delta property which allows directly imposing boundary conditions on scattered nodes. Factors affecting to thermal buckling phenomenon are investigated. The accuracy of solutions will be shown by comparing them to reliable results in previous studies
Investigation of the shear behavior of ultra-high performance concrete girder by simulation approach
Authors: Dao Cong-Binh , Mai Viet-Chinh , Vu Ngoc-Quang , Pham Hoang
Published: August 2023

The present study investigates the shear behavior of the Ultra High Performance Concrete girder strengthened by steel bars and stirrups by simulation approach. Utilizing the Concrete Damage Plasticity model that involves strength reduction and nonlinear behavior of the material, 3D simulation models are established and analyzed by the commercial software Abaqus. The numerical simulation model is verified by comparing the test data to ensure reliability. Numerical simulation models were then developed to investigate the relationship of shear force with parametric studies of shear span to depth ratio, steel bar ratio and stirrups spacing. Based on the obtained results, the simulation model and test results show a good agreement. The relation between the shear capacity of UHPC girder and parametric studies was also enlightened.
Application of steel frame viaduct for mountainous roads in Vietnam: Case studies in Quang Ngai Province and Lam Dong Province
Authors: Tung Dang Dang , Tuan Nguyen Canh
Published: August 2023

Vietnam’s mountainous highways are increasingly affected by landslides each year, with climate change being a major cause. The government has allocated significant funds to repair, rehabilitate, and maintain these highways, but conventional methods like excavation and embankment are not always effective for roads that pass through unstable, large-angle slopes that have a high risk of landslides. This results in additional rehabilitation costs following natural disasters. To address this issue, JFE Civil Engineering & Construction Corporation has developed a new solution for constructing mountainous highways in Vietnam - a viaduct that functions as a space steel frame supported by steel pipe columns and beams. Prefabricated in a factory and transported to the construction site, the steel beams are then assembled, and steel piles are driven deep into the ground for a rigid pile-to-ground connection. These proposed structures offer sustainable and cost-effective solutions for mountainous highways with minimal impact on the surrounding environment. Two case studies in Quang Ngai Province and Lam Dong Province are presented as preliminary designs to demonstrate the feasibility of this solution.
Rotating uniform eddy current probe using four rectangular excitation coils with ferrite cores for cracks detection in conductive materials
Authors: Trung Le Quang , Miyazaki Seishu , Kasai Naoya , Sekino Kouichi
Published: August 2023

In this study, we introduce a new rotating uniform eddy current (RUEC) probe designed to identify artificial cracks in conductive materials. The RUEC probe comprises four rectangular coils, divided into two sets of diagonally positioned coils. By providing two alternating current sources with a 90° phase difference to the two sets of coils, a RUEC distribution with uniform amplitude in all directions can be produced on the surface of the test specimen. Furthermore, ferrite cores are integrated into the four coils to enhance the crack detection ability. To confirm that the RUEC probe model produces RUECs with uniform amplitude in all directions on the test specimen surface, we conducted finite element method (FEM) simulations. We then conducted experiments with the RUEC probe to identify artificial cracks of varying sizes on the test specimen. The experimental results demonstrate that the RUEC distribution on the test specimen surface enabled successful detection of cracks in all directions with the probe.
A case study of processing abnormal GNSS monitoring data of a cable-stayed bridge in Vietnam
Authors: Le Van Hien , Vo Duy Hung
Published: August 2023

Global Navigation Satellite System (GNSS) plays an important role in the real-time monitoring of superstructures, especially for long-span cable-stayed bridges. Currently, GNSS has been applied to integrate a Structural Health Monitoring system (SHMs) of many long-span cable-stayed bridges worldwide through its advantages in observing a large displacement of structures and monitoring the global deformation of bridges. However, some studies of actual GNSS monitoring data of a cable-stayed bridge showed that there are a lot of abnormal data occurrences such as missing data or several abnormal data. This paper investigates the application of some methods for processing the GNSS abnormal data acquired from an actual cable-stayed bridge in Vietnam. Firstly, a long-term monitoring dataset of an actual bridge was acquired for the study experiment. A clean-short dataset was used to investigate the accuracy and applicability of some methods in the interpolation of abnormal data, for example, linear formula, Moving Average, Artificial Neural Network, and Hampel Identifier. Some criteria are used to assess the difference between the interpolated data and actual data such as Root Mean Square Error (RMSE) or correlated coefficients with temperature data. Otherwise, the applied methods were then assessed their abilities and effectiveness in real applications, for instance, creating an automatic interpolated program of abnormal data.
Study on detecting deterioration in beam structure stiffness using deformed shape
Authors: Ngo Han-Cuong , Ha Tuan Minh , Fukada Saiji , Ho Duc-Duy
Published: August 2023

This study presents a diagnostic technique for identifying the loss of stiffness of homogeneous beams using only the deformed shape in an effort to develop more effective building health monitoring instruments. Method based on a correlation between beam deformation at two damaged and undamaged selection states. Diagnostic indicators such as the correlation coefficient (CC) and the absolute value of the mean deviation ratio (MAPD) are extensively used to determine the presence of decreased stiffness. Using an approach based on finite element analysis, the deformation line data is computed. Various failure scenarios are proposed to evaluate the beam damage detection sensitivity of the indicators. In the case of beam damage, the CC index value is less than 1, and in the absence of damage, it is equal to 1. Similarly, for the MAPD index, the value is greater than 0 in the case of damage to the beam and 0 in the case of no assumed failure. The result demonstrates that the deformed line data can be used to calculate the assessment indicators for determining the onset of damage in homogeneous beams. Indicators that have not yet determined the location of the local stiffness decline on the beam when using input data are the deformed shape corresponding to the survey examples in this study.
Roadway departure crashes in Vietnam: identifying the sequence of events, causes, and countermeasures by applying the crash reconstruction technique
Authors: Nguyen Dinh Vinh Man , Vu Anh Tuan
Published: August 2023

The horizontal curve segment is where traffic crashes often occur in rural areas of Vietnam. Although many safety countermeasures have been implemented, their effectiveness still needs to improve. The main reason is that the implemented countermeasures are unfit for the crash causes. More specifically, determining crash causes and contributory factors to the severity of crashes needs to be more accurate because of the need for more critical data and specialized analytical tools. This study applies the crash reconstruction technique to simulate, reconstruct, and analyze crashes that occurred at horizontal curve segments to address the abovementioned issues. The study results have reproduced the sequence of events, crash causes, and contributory factors to the severity of roadway departure crashes of four-wheeled vehicles in rural areas. This research is a scientific foundation to help researchers choose the suitable technique to reconstruct traffic crashes and identify the appropriate solutions for enhancing traffic safety at horizontal curve segments in Vietnam.
Proposed severity ranking for ASTM E3303-21 protocol to quantify asphalt pavement cracking from automated 3D surveys
Authors: Nguyen Teron , Pin Kelvin Lee Yang , Tan Jun Yew , Ho Nyok Yong
Published: August 2023

Cracking is one of the essential indicators to evaluate pavement surface conditions; however, it is challenging to rate pavement cracking automatically from 3D digital images. Recently, a two-level automated crack rating system was proposed for pavement management in Singapore where Level 1 provides detailed crack information including cracking extent, types, and severity. Level 2 is a macro-indicator ranging from 0 to 5 based on crack extent over a 10-m length pavement section, with 0 being excellent condition and 5 being very bad condition. On the other hand, the new ASTM E3303-21 standard has introduced the Pavement Surface Cracking Metric which is a dimensionless measure equivalent to crack density and the Pavement Surface Cracking Index which provides ratings of pavement cracking ranging from 0 to 100, with 0 being the worst possible condition and 100 being the best possible condition. This study was conducted to compare and potentially bridge the gaps between the two mentioned cracking rating methods. Cracking data were collected from the Singapore road network using the Laser Crack Measurement System-2 (LCMS-2). Based on the study findings, three severity ranks (low, medium, and high) were proposed to facilitate the inclusion of the ASTM E3303-21 cracking protocol into Pavement Condition Index calculations.
Effects of PET and RFCC on the dynamic modulus, phase angle, and complex viscosity of asphalt concrete
Authors: Do Cao-Phan , Le Anh-Thang , Nguyen Manh-Tuan
Published: August 2023

With economic and social development, the total amount of domestic and industrial solid waste discharged is considerable. In 2020, Vietnam generated about 2.2 million tons of plastic waste and 2 million tons of industrial solid waste. And most of them are landfilled and take a long time to decompose. This has dramatically affected the environment, costly land resources, and considerable transportation, burial, and management costs of those landfills. Therefore, many scientists have studied to recycle these wastes. There are two approaches to using recycled waste in hot mix asphalt (HMA). Waste plastic changes the properties of the asphalt binder, and solid waste replaces coarse particles in an asphalt mixture. During the research on using recycled waste for asphalt concrete, PET (Poly Ethylene Terephthalate) and RFCC (Residue Fluid Catalytic Cracking) were chosen for the study. This paper presents a study on the influence of PET (with 0.2% content in HMA) and RFCC (with 5% content in HMA) on the viscoelastic property of asphalt concrete based on dynamic modulus, phase angle, and complex viscosity values. At high temperatures, HMA using PET and RFCC exhibit complete elastic behavior (φ ≈ 50) in contrast to the viscous elastic behavior of the control sample (φ ≈ 150). Compared control sample, RFCC significantly increased the stiffness of HMA at low and high temperatures; with the dynamic modulus of HMA using RFCC increased 1.1 times at low and 1.6 times at high temperatures; the viscosity of HMA using RFCC and PET decreased 10 times and 7 times at low temperatures.
Evaluating potential expansion and strength of compacted steel slag aggregates at different compaction density
Authors: Nguyen Cuong T. , Pham Phuong N. , Nam Huynh Phuong , Le Chau D.
Published: August 2023

Steel slag aggregates can be utilized as unbound materials for road bases or as fine/coarse aggregates in asphalt/cement paving concrete. However, the availability of free lime (f-CaO) in the materials is detrimental to volumetric stability, affecting the strength or durability of resulting paving products incorporating steel slag aggregates. This paper investigates the potential expansion of fine and coarse steel slag aggregates compacted at different compaction densities. The experimental results exhibited a higher stability of the coarse granular mixture exposed to water than the fine one. Also, more compaction increased expansibility in the fine mix, especially at high compaction density. Furthermore, the graded steel slag aggregate exhibited higher strength than the other aggregates. The findings provide reference information on the useability of steel slag in cement-based materials, like the replacement of coarse aggregate is better than the fine ones in volume stability of steel slag concrete.
Use of marble dust and linz-donawitz slag for the production of pervious concrete
Authors: Singh Tarunbir , Kaur Gaganpreet , Singh Pavitar
Published: August 2023

Nowadays, the development of infrastructure is in full swing, which exploits natural resources and causes environmental pollution. Furthermore, cement is the most essential commodity for construction material mainly concrete, and its production is rapidly increasing to fulfil the demand for construction. The cement production is regarded as the one of the key causes of CO2 emissions, which adversely affect the atmosphere by causing global warming. In addition to this, the ecosystem may suffer from marble quarrying and construction material processing. Nonetheless, waste marble can be used as a by-product if managed in accordance with regional, national, and international environmental laws. On the other hand, Currently, LD slag is disposed of in landfills, which exacerbates the scarcity of available land and contaminates groundwater through the leaching of heavy metals. The waste materials have the potential to be used in the development of infrastructure materials. The infrastructure development has aggravated the issue of rainwater runoff and flash flooding in rainy seasons because of inappropriate drainage. The elimination of sand in pervious concrete reduces its strength performance its practical applications are still limited. This study is aimed toward the permeability improvement of conventional pavement concrete by the implementation of pervious concrete and also to improve its strength characteristics. In this study, an attempt has to be made to replace the cement with marble dust up to a replacement level of 0% to 20% with an interval of 5%. Also, natural aggregate is replaced with Linz-Donawitz (LD) slag by 5%, 15%, 25%, and 35%. From the study, it is found that the use of marble dust and LD slag improves the strength properties, but reduces the permeation properties.
Properties of Concrete Containing Large Volumes of Ground Granulated Blast Furnace Slag and Ground Coal Bottom Ash with Lime Kiln Dust
Authors: Ban Cheah Chee , Hui David Wong Zhong , Jia Liew Jia , Ping Kevin Khaw Le
Published: August 2023

Currently, there is no report on the combined use of ground coal bottom ash (GCBA) and ground granulated blast furnace slag (GGBS) as supplementary cementitious material (SCM) with lime kiln dust (LKD) as an additive in mortar. Hence, the current work aimed to investigate the impact of the addition of LKD on the properties of ternary blended cement mortar consisting of a large volume of GCBA and GGBS as SCM. The total substitution level of cement was up to 80%, where 50% of GGBS was combined with 0 to 30% of ground CBA. LKD was used with a content of 0%, 4% and 8%. A polycarboxylate-ether-based superplasticiser was used to achieve the mortar’s flow diameter of 200 ± 10 mm. Also, the fine aggregate-to-binder and water-to-binder ratios were fixed at 3.0 and 0.4, respectively. The result revealed that the setting time of the mortar increased by increasing the cement replacement level by GCBA. Besides, the setting time was reduced with increased LKD content. All the mortar mixtures are considered good quality according to the ultrasonic pulse velocity (UPV) results. The UPV values decrease with the increased GCBA replacement ratio but increase with extended curing ages. The mortar incorporating up to 15% GCBA achieved comparable or greater strength than the control mortar (50% OPC and 50% GGBS) at a curing age beyond 28 days. Moreover, increased strength performance was noticed with increased LKD content from 0% to 8%.
A comparison of countermeasures against landslide on the road No.152, Sapa Town, Lao Cai Province, Vietnam
Authors: Aung T Z , Naing C T T , Nguyen L C , Nguyen K T
Published: August 2023

Landslide hazards are one of the most common geological disasters due to the impacts of natural factors, mainly rainfall, and human activities, such as the construction of transport infrastructure and mining projects. In Vietnam, most of the landslides and slippage frequently occur in mountainous areas, especially in Lao Cai province during the rainy season. In 2021, a slope failure happened near the Mong Hoa valley, on Road No. 152, sections Km 2+728.26–Km 2+827.04 in Cau May ward, Sapa town, Lao Cai province. In this study, topographical features, geomorphological features, hydrological features, geological investigation, and laboratory tests were performed to analyse the slope stability. This study used the Limit Equilibrium Method (LEM) and the Finite Element Method (FEM) to analyse the slope stability, and several countermeasures were proposed for this slope such as the retaining wall, ground anchors, and soil nails. This numerical result showed that the ground anchors and soil nails are the suitable method to prevent the instability of the slope. This study shows that compared with the traditional LEM method and advanced FEM method is that it can capture more results not only safety factor but also horizontal displacement and load anchor result. As a result, this analysis showed that the safety factor value in the finite element method was greater than that in the limit equilibrium method.
Unsaturated hydraulic property of recycled concrete aggregates blended with autoclaved aerated concrete grains for unbound road base and subbase materials in Vietnam
Authors: Pham Van Nam , Nguyen Quoc Cuong , Nguyen Hoang Giang , Kawamoto Ken
Published: August 2023

Roadbed materials of base and subbase layers are frequently unsaturated caused by rainfall, drainage, and evaporation. However, the movement of water in these layers is still poorly understood because of lacking data on unsaturated properties such as the water retention curve (WRC) and unsaturated hydraulic conductivity (K). This study, therefore, recycled concrete aggregates (RCA) blended with autoclaved aerated concrete (AAC) grains (% of substitution on the mass basis from 0 to 50%) were used to examine the WRC and K for unbound roadbed materials in Vietnam using the evaporation method. Natural aggregates (NA) and Toyoura sand were used as control and reference material. Results showed that compared to NA100% and RCA100%, the water capacity of RCA mixed samples was much improved by blending AAC grains. Toyoura sand showed higher water capacity at saturation compared to RCA100% and NA100%, but quickly became lowest when matric potential exceeds 10 kPa. Toyoura sand showed the highest saturated hydraulic conductivity, but decreased dramatically around 10 kPa, while other tested samples remained higher K. The original van Genuchten – Mualem model was well fitted for Toyoura sand and underestimated for other tested samples, but showed an agreement with estimated conductivity parameter ranging from – 3.0 to -4.4.
An analytical and numerical study on influence of the load transfer shallow mixing layer on stress-induced and settlement of ground improved by CDM columns
Authors: Zar T , Nguyen TD , Nguyen CL
Published: August 2023

In the literature, there are a few analytical methods for evaluating stress induced on the CDM column heads and most of them involve the use of geosynthetics embedded layers, except the method of ALiCC. However, the ALiCC method still has some limitations in actual designs. This paper presents numerical analysis (by using Plaxis software) and analytical analysis (by using the ALiCC method) on the influence of thickness and stiffness of the SM layer (without the use of geosynthetics embedded layers) on stress induced on column heads and settlement of the improved ground. A typical parametric case and actual project case were taken into analyses. Analysis results from the examined cases indicate that, as expected, when the thickness or stiffness of the SM layer increases, the settlement of the ground decreases and the stress induced on the column head increases. An important finding from this study is that the maximum stress induced in the CDM column is typically not on the head of the columns but at the middle depths where soil layers are softer than the SM layer and the bearing layer at the column toes.
Mapping domain junctions using 4D-STEM: toward controlled properties of epitaxially grown transition metal dichalcogenide monolayers
Authors: Dosenovic Djordje , Dechamps Samuel , Vergnaud Celine , Pasko Sergej , Krotkus Simonas , Heuken Michael , Genovese Luigi , Rouviere Jean-Luc , den Hertog Martien , Le Van-Jodin Lucie , Jamet Matthieu , Marty Alain , Okuno Hanako
Published: August 2023

Epitaxial growth has become a promising route to achieve highly crystalline continuous two-dimensional layers. However, high-quality layer production with expected electrical properties is still challenging due to the defects induced by the coalescence between imperfectly aligned domains. In order to control their intrinsic properties at the device scale, the synthesized materials should be described as a patchwork of coalesced domains. Here, we report multi-scale and multi-structural analysis on highly oriented epitaxial WS2 and WSe2 monolayers using scanning transmission electron microscopy (STEM) techniques. Characteristic domain junctions are first identified and classified based on the detailed atomic structure analysis using aberration corrected STEM imaging. Mapping orientation, polar direction and phase at the micrometer scale using four-dimensional STEM enabled to access the density and the distribution of the specific domain junctions. Our results validate a readily applicable process for the study of highly oriented epitaxial transition metal dichalcogenides, providing an overview of synthesized materials from large scale down to atomic scale with multiple structural information.
Numerical analysis for the normal force of magnetorheological fluids
Authors: Zheng Ji-Nan , Zheng Xiang-Pan , Lin Xiu-Fang , Chen Shu-Mei
Published: August 2023

As one of the most important mechanical parameters of magnetorheological fluids (MRF), the normal force has been studied by a large number of researchers using various experimental equipment and methods. However, it is difficult to reveal the effects of particle microstructure characteristics on the normal force of MRF by experimental methods, especially for such factor as the particle size distribution. To advance this research area, a numerical method for calculating the normal force of MRF is proposed in this study. The accuracy of the simulation model is verified with the experimental results measured by a plate-plate magnetorheometer. The results show that the simulated values agree well with the experimental data, which indicates the feasibility of calculating the normal force of MRF using numerical methods and provides a new research idea for a more intuitive and comprehensive analysis of the normal force characteristics of MRF. Besides, the simulated data show that the increase in magnetic field intensity and particle volume fraction will sufficiently enhance the normal force of MRF and improve the response time of MRF. For the MRF with the same particle volume fraction, a decline in the average particle diameter will increase the normal force. Moreover, increasing the dispersion of particle size of MRF particles can also improve its normal force.
CAM photosynthesis in Bulnesia retama (Zygophyllaceae), a non-succulent desert shrub from South America
Authors: Mok Daniel , Leung Arthur , Searles Peter , Sage Tammy L , Sage Rowan F
Published: August 2023

Background and Aims

Bulnesia retama is a drought-deciduous, xerophytic shrub from arid landscapes of South America. In a survey of carbon isotope ratios (δ13C) in specimens from the field, B. retama exhibited less negative values, indicative of CAM or C4 photosynthesis. Here, we investigate whether B. retama is a C4 or CAM plant.

Methods

Gas-exchange responses to intercellular CO2, diurnal gas-exchange profiles, δ13C and dawn vs. afternoon titratable acidity were measured on leaves and stems of watered and droughted B. retama plants. Leaf and stem cross-sections were imaged to determine whether the tissues exhibited succulent CAM or C4 Kranz anatomy.

Key Results

Field-collected stems and fruits of B. retama exhibited δ13C between −16 and −19 ‰. Plants grown in a glasshouse from field-collected seeds had leaf δ13C values near −31 ‰ and stem δ13C values near −28 ‰. The CO2 response of photosynthesis showed that leaves and stems used C3 photosynthesis during the day, while curvature in the nocturnal response of net CO2 assimilation rate (A) in all stems, coupled with slightly positive rates of A at night, indicated modest CAM function. C4 photosynthesis was absent. Succulence was absent in all tissues, although stems exhibited tight packing of the cortical chlorenchyma in a CAM-like manner. Tissue titratable acidity increased at night in droughted stems.

Conclusions

Bulnesia retama is a weak to modest C3 + CAM plant. This is the first report of CAM in the Zygophyllaceae and the first showing that non-succulent, xerophytic shrubs use CAM. CAM alone in B. retama was too limited to explain less negative δ13C in field-collected plants, but combined with effects of low stomatal and mesophyll conductance it could raise δ13C to observed values between −16 and −19 ‰. Modest CAM activity, particularly during severe drought, could enable B. retama to persist in arid habitats of South America.
Locomotor performance differs between foraging and predator escape but is not related to survival in hatchling lizards
Authors: Norris M Christopher , Robbins Travis R , Warner Daniel A
Published: August 2023

Behaviour is influenced by many factors, including morphology, performance capabilities and the surrounding environment. Behavioural adjustments in response to these factors have important fitness consequences, and therefore behaviour should be considered when evaluating relationships among morphology, performance and fitness. We used hatchling fence lizards (Sceloporus undulatus) to test if sprinting speed and movement behaviours (e.g. latency to approach prey, number of pauses when fleeing or foraging) differ between foraging and anti-predator contexts and if these behaviours are associated with body size, locomotor performance capacity and survival. We quantified maximal sprint performance of individuals and evaluated their running speed in laboratory trials of foraging (moving towards crickets) and predator escape (response to a swooping avian predator). We show that hatchlings run at ~17–36% of total capacity when foraging. Although the most common anti-predator behaviour was to remain still, those that fled from the predator ran at full burst speed. However, foraging and escape speed/behaviours were not associated with body size or locomotor capacity. Hatchlings were subsequently released at our field site for a recapture study to assess phenotypic relationships with survival. We found no evidence that survival was influenced by performance or behaviour, but body size was positively related to survival in the field. These results highlight how seemingly important fitness-relevant behavioural and performance traits may not mediate the relationship between body size and survival.
O01 Clinical aspects of psoriasis flares and risk factors for developing a post-infectious flare in children with SARS-CoV-2 infection: data from the Chi-PsoCov registry
Authors: Mahé Emmanuel , di Lernia Vito , Fortina Anna Belloni , Lesiak Aleksandra , Brzezinski Piotr , Topkarci Zeynep , Murashkin Nikolay , Torres Tiago , De La Cruz Helena Vidaurri , Maruani Annabel , Chiriac Anca , Bursztejn Anne-Claire , Van Den Reek Juul , Epishev Roman , Severino-Freire Maella , Akinde Maria , Luca Catalina , Thomas Jayakar , Zitouni Jinane , McPherson Tess , Mahil Satveer , Smith Catherine , Flohr Carsten , Bachelez Hervé
Published: August 2023

The international Chi-PsoCov registry showed that biologics did not increase the risk of severe forms of COVID-19 in children with psoriasis. It was shown that COVID-19 may induce de novo psoriasis or flares of known psoriasis. We focused on children who developed a flare of psoriasis after infection, phenotypic aspects of the flares, and searched for associated factors. We included 149 children from February 2021 to May 2022 in 14 countries. The 11 who developed de novo psoriasis were excluded. We excluded 160 children (M / F = 1; mean age 12.4 years; plaque psoriasis 64.7%). Psoriasis worsened within 1 month of onset of COVID-19 in 26 cases (17.4%). For other children, psoriasis improved (n = 1; 0.6%) or remained same (n = 122; 81.9%). In 24 patients whose condition worsened, the phenotype was unchanged, and in 2, there were phenotype changes: plaque psoriasis to guttate or inverse psoriasis. Demographic characteristics, phenotype/severity of psoriasis or COVID-19 severity were not associated with flares. Only the use of systemic treatments at the time of infection protected against the occurrence of flares (50.0% vs. 27.3%, P = 0.049). In this study SARS-CoV-2 infection was associated with psoriasis flares in 17% of cases. In the majority of cases that worsened, the phenotype preceding the infection was preserved. These flares are not associated with the severity of psoriasis, severity of COVID-19 or other clinical parameters. Only systemic treatments seem to reduce this risk, probably by ‘controlling’ the flare. It is possible that a genetic susceptibility, not explored here, also explains this susceptibility to infection.
O03 Langerhans cell histiocytosis: case series of presentations to dermatology in the BRAF era
Authors: Coyle Conor , Bovijn Louise , Blanco Esther , McPherson Tess
Published: August 2023

Langerhans cell histiocytosis (LCH) is a rare disease driven by MAPK pathway mutations. This condition is on a spectrum, from single-system to life-threatening multisystem disease. Identification of the BRAF mutation is leading to improved understanding and targeted therapies. However, there is limited information on genetic status, phenotype and dermatological features. Fourteen patients were seen in the Paediatric Dermatology department in period 2015–2022: 11 males and 3 females; 9 patients had multisystem LCH; 8 patients had cutaneous manifestations of LCH; and 4 had limited cutaneous LCH. Six patients were diagnosed in the department and typically had multiple incorrect diagnoses and treatments prior to review. Clinical features varied from widespread skin involvement, scalp/groin intertrigo, flexural ulcerations and telangiectatic papules. Eight had LCH diagnosed in other tissues by oncology and referral advice on cutaneous symptoms were sought. Most patients have required input from dermatology throughout treatment. Biopsies were taken when unclear diagnosis and/or pathology would influence treatment. Several consultations revealed benign pathologies including keratosis pilaris and dermatitis requiring topical treatment advice only. All five patients with BRAF v600 mutation had multisystem disease including diabetes insipidus, adrenal insufficiency, gut and bone lesions. Two patients with severe LCH and BRAF mutations are being treated successfully with dabrafenib. Our series demonstrates the important role of dermatology in the diagnosis and management of LCH. This series confirms clinical heterogeneity and an association of BRAF V600E mutation with multiorgan disease. Ongoing work should expand our knowledge of the relationship of genetic alterations with clinical phenotypes and comorbidities.
O07 Faceless PHACES
Authors: Albela Henrietta , O’Neill Claire , Glover Mary , Solman Lea , Polubothu Satyamaanasa
Published: August 2023

PHACES syndrome (posterior fossa – haemangioma – arterial – cardiac – eye – sternal) is a multisystem disorder which often presents first with a facial, segmental infantile haemangioma (IH). Prompt recognition of this subtype of IH is key to enable early detection of neurological/ophthalmological/cardiac anomalies. As per international consensus guidelines, the presence of a facial segmental haemangioma > 5 cm triggers screening for associated extracutaneous anomalies. We present three infants with absent/minimal facial haemangioma, but who fulfilled extracutaneous criteria of PHACES syndrome. Patient 1 was a 3-week-old female who presented with a 1–2-cm linear superficial left post-auricular IH. PHACES screening revealed an atrial septal defect, intracranial haemangiomas and hypoplastic cerebrovasculature. Patient 2, a 9-month-old girl, was admitted to intensive care following acute respiratory deterioration. Examination revealed a segmental IH of the occipital scalp. PHACES screening revealed a vascular ring, right aortic arch, aberrant subclavian artery, subglottic and mediastinal IH and narrowing/tortuosity of the left internal carotid artery. Patient 3, a 4-month-old male, was referred for evaluation of three superficial IH, all < 0.5 cm, one on the right post-auricular skin and two on the right forehead. He suffered acute collapse at 2 weeks of life leading to a diagnosis of obstructed total anomalous pulmonary–venous connection requiring emergency surgical correction. PHACES screening revealed bilateral dysplastic/torturous internal carotid arteries. We present three cases of PHACES syndrome without the classic facial segmental IH. Clinicians should be aware of the spectrum of IH observed in PHACES syndrome to enable prompt screening of those presenting with atypical scalp and post-auricular lesions.
O08 Mesenchymal stromal cells infusions in children with recessive dystrophic epidermolysis bullosa (MissionEB): a randomized controlled trial
Authors: Bageta Maria L , Balboa Pablo Lopez , Glover Rachel , Cooper Cindy , Papaioannou Diana E , Julious Steven , Dimairo Munya , Biggs Katie , Petrof Gabriela , Martinez Anna E
Published: August 2023

Recessive dystrophic epidermolysis bullosa (RDEB) is one of the most severe forms of epidermolysis bullosa caused by loss-of-function mutations in the type VII collagen gene (COL7A1) leading to extensive skin and mucosal fragility and systemic complications. No active treatment is currently available. This study assesses whether repeated infusions of allogeneic umbilical cord-derived mesenchymal stromal cells are safe and can benefit children with RDEB. This is a double-blinded, randomized (1 : 1), placebo-controlled crossover trial with an internal dose de-escalation trial for safety and a further 12-month open-label study following review of the data. Around 36 participants with RDEB who are older than 6 months and younger than 16 years are being recruited at Great Ormond Street Hospital and Birmingham Children's Hospital. Participants will receive two intravenous infusions (days 0 and 14), at a dose of 2–3 × 106 cells kg–1 that could be adjusted to 1–1.5 × 106 cells kg–1 based on observed toxicities. Outcomes assessed at 3 and 6 months from day 0 in each crossover period include changes in EBDASI, iscorEB, pain, itch and quality of life scores. This is the largest cell-therapy study in children with RDEB. Previous nonrandomized trials have suggested that intravenous mesenchymal stromal cells are safe in children with RDEB and indicated early evidence of benefit. There was a need for a robust controlled study to validate these findings. The study is funded by the National Research Collaboration Programme (NIHR127963), an NHS England and NHS Improvement and National Institute for Health Research partnership, and Cure EB. ISRCTN registry (ISRCTN14409785).
P06 Atopic dermatitis and psoriasis in children, and SARS-CoV-2 infection: different impact of the infection on these dermatoses, and of these dermatoses on the infection?
Authors: Mahé Emmanuel , Zitouni Jinane , de la Breteque Maud Amy
Published: August 2023

The SARS-CoV-2 pandemic has raised many questions regarding chronic inflammatory dermatoses and their treatments. Atopic dermatitis (AD) and psoriasis are chronic inflammatory dermatoses with different immunological profiles. Their susceptibility to infections also differs. We were interested in the link between SARS-CoV-2 infection and these two dermatoses in children: different impact of the infection on AD and psoriasis (disease flare-ups), and of these two dermatoses on the severity of this infection (severity). This was a single-centre study of children with AD or psoriasis or those who developed these dermatoses within 1 month of infection, and who developed a SARS-CoV-2 infection. Thirty-two children with AD and 66 with psoriasis were included. Age, sex, frequency of overweight and frequency of systemic treatments (systemic or biotherapy) were not different in the two groups. The frequency of symptomatic forms and the duration of symptoms were not statistically different between the two groups. In 15.6% of AD and 12.7% of psoriasis (P = 0.69), a worsening of symptoms was noted in the month following the onset of the infection. De novo psoriasis was diagnosed in three cases, but no AD. There was no difference in the impact of SARS-CoV-2 infection on the evolution of these two dermatoses, with the possible exception of the appearance of post-infection psoriasis, which was not observed with AD. Similarly, these two diseases did not seem to have a different impact on the severity of SARS-CoV-2 infection. These results should be confirmed with larger cohorts such as Secure-AD and Chi-PsoCov.
P09 A case series of anetodermic pilomatrixomas
Authors: Vetsiou Evangelia , Gass Julia , McDonald Sarah , Stefanos Niki , Rytina Ed , Burrows Nigel
Published: August 2023

Pilomatrixoma is a benign tumour that arises from the base of the hair follicle matrix. Anetodermic changes overlying the tumour occur in only 2% of the cases. The aim of this study is to evaluate a case series of paediatric patients who presented with anetodermic pilomatrixoma to our Paediatric Dermatology department. A retrospective analysis of all our paediatric cases with a clinical diagnosis of anetodermic pilomatrixoma within the last 4 years was made. Data were collected according to age at time of presentation, suspected clinical diagnosis, histopathological features, treatment and postoperative outcomes. Five cases were identified. All were referred as a rapidly growing tumour. The median age of onset was 15 years. The male : female ratio was 3 : 2; one presented on the neck, two on the upper limbs and two on the back. Two out of three patients reported that the lesions were painful. Clinical suspicion of anetodermic pilomatrixoma (large, atrophic, wrinkled lesion overlying a firm subcutaneous mass) was made prior to surgical removal. Four were confirmed histopathologically. Simple excision was carried out without any postoperative complications. There have been no recurrences. Anetodermic pilomatrixoma, also referred to as pseudobullous pilomatrixoma, is a rare variant of pilomatrixomas, occurring more frequently in the upper body. It presents with identifiable features but should be differentiated from other skin tumours. Pain can be a symptom due to the size of the lesion. Surgical removal is the gold standard treatment with a low recurrence rate.