bluuebunny/crossref_metadata_2025 huggingface dataset:
Bandgap variation of a locally resonant metamaterial induced by temperature variation and pre-tension in the shape memory alloy resonators
Authors: Yin Chao , Geng Yunhui , Shen Xing , Yang Yang , Fan Siyun , Wang Taoxi
Published: March 2022

Elastic/acoustic metamaterials with local resonance (LR) arrays have bandgaps that can forbid or suppress the propagation of elastic waves. In this paper, the shape memory alloy (SMA) is utilized in the metamaterial structure to yield variable bandgaps. The relationship between LR bandgap and temperature during heating and cooling is obtained using a metamaterial beam with a periodic array of SMA resonators, and the effect of pre-tension of SMA on the bandgap of this SMA-based metamaterial structure is explored. The experimental results show that the bandgap of this structure varies along with temperature variation. However, as the elastic modulus of SMA varies differently between situations of heating and cooling, such bandgap variation phenomenon differs as well. Additionally, it is concluded that introducing pre-tension in the SMA resonators broadens the variable range of the bandgap during heating although such deformation gradually vanishes due to shape memory effect. It is also verified by simulation that, apart from pre-tension, pre-bending and pre-torsion in the SMA resonators also have significant impact on the bandgap of this structure. Moreover, higher-order bandgaps are observed varying in a similar way as the first-order bandgap, but the entire variation range is more remarkable. By carefully choosing and adjusting the pre-deformation types and parameters, it is possible to manipulate simultaneously both the starting frequency and the width of the bandgap.
Generation of vector beams with different polarization singularities based on metasurfaces
Authors: Liu Danhua , Zhou Changda , Lu Peiyao , Xu Jilian , Yue Zhiyuan , Teng Shuyun
Published: March 2022

In view of wide applications of vector beams and powerful light manipulation ability of metasurfaces, this paper studies the generation of two kinds of vector beams with different polarization singularities based on metasurfaces. One kind of vector beams are the linearly polarized vector beam with uncertain polarization orientation and the other kind of vector beams are the elliptically polarized vector beam with hybrid polarization states with uncertain polarization orientation, ellipticity and handedness. These vector beams can be decomposed into two or more uniform polarization states carrying the spiral phases. The metasurfaces consisting of rotated cross nanoholes are designed to generate vector beams on basis of the decomposition of vector beams and phase modulation of nanoholes. The simulation results verify the availability of the designed metasurfaces and the experiment results validate the generation of two kinds of vector beams. The generation of complex vector beams based on compact metasurfaces can bring more application possibilities of vector beams in classical physics and quantum sciences.
Electrical and structural characteristics of fish skin gelatin as alternative biopolymer electrolyte
Authors: Nadzrin Norlin , Manan Ninie S A , Aziz Shujahadeen B , Kadir Mohd F Z
Published: March 2022

This article presented new sequences of fish gelatin (FG) as a polymer host for solid polymer electrolytes (SPEs) impregnated with ammonium nitrate (NH4NO3) and the impact of different amounts of salt on the properties of the formed electrolyte were investigated. X-ray diffraction (XRD) analysis revealed that the electrolyte containing 25 wt.% NH4NO3 salt to be the most amorphous in nature. Fourier transform infrared (FTIR) spectroscopy analysis showed that the peak of amide III shifted to a lower wavenumber as salt increased to 25 wt.%, indicating the occurrence of interaction between the salt and polymer. The effect of variation amount of salt on the film morphology was studied using FESEM. The ionic conductivity of the undoped pure FG film at room temperature recorded a maximum value of

1.52
±
0.30

×

10

−
5

S

cm

−
1

at 25 wt.% NH4NO3 and the activation energy dropped to 0.454 eV. All electrolytes showed a linear conductivity-temperature plot at elevated temperatures, indicating that they all follow the Arrhenius rule. All of the electrolytes used in this study are non-Debye type, according to dielectric analysis. The findings provided in this article could help to improve the usage of FG as an alternate source of SPE in electrochemical power sources as a replacement for hazardous electrolytes.
Effects of magnetic field on the evolution of the wave function of a charged particle with an angular momentum
Authors: He Pei-Song , Zhu Yao-Hui
Published: March 2022

We have calculated the effect of a magnetic field on the evolution of angular momentum eigenfunctions of a charged particle. An additional harmonic potential is supplemented to trap the wave packet. We find the probability density of the wave function is oscillating in the radial direction with a time period determined by the strength of the effective harmonic potential. When the magnetic field is along the z direction, if the initial wave function is an eigenfunction of

L

ˆ

z

, the probability density of the particle remains axis-symmetric. While for the case of an eigenfunction of

L

ˆ

x

, it is anisotropic in the x−y plane and rotates with a time period inverse proportional to the strength of the external magnetic field. We also extend the results in a phenomenological way to the case with an external magnetic field that varies harmonically in time.
Super Twisting Nonlinear Fractional Order Sliding Mode Control of Aerodynamic Heat Simulation Heating System Based on Time Delay Estimation
Authors: Lv X D , Zhang G M , Ouyang H M , Gao P , Bai Z Q
Published: March 2022

This paper proposes a novel super twisting nonlinear fractional order sliding mode control (STNFOSMC) method based on time delay estimation (TDE) for Aerodynamic Heat Simulation Heating System (AHSHS). Firstly, based on uncertainties and external disturbances of AHSHS, TDE is an observation. Secondly, the nonlinear function, fractional differentiation and fractional integration are added into the sliding mode surface for improving the control quality of sliding stage, and the super twisting approach rate accelerates the control speed and weakens the chattering phenomenon in the arrival phase. Then, a Lyapunov function is utilized to prove the stability of the control method. Finally, compared with the traditional PID, the superiority of the proposed control method is verified.
Swing Suppression Task in Double-pendulum Tower Cranes Using Robust Adaptive Sliding Mode Controller
Authors: Tian Zheng , Ouyang Huimin , Yu Lili
Published: March 2022

In actual applications, tower crane systems are usually suffered from underactuated characteristic, double-pendulum effect, frictions, model uncertainties and disturbances etc. As a result of these problems, the control of tower cranes for accurate positioning and effective swing suppression becomes more difficult. To this end, we propose a robust adaptive sliding mode controller, which has adaptive gains varying by the system tracking error and adaptive terms to compensate the lumped disturbances in all DOF (degrees of freedom). Therefore, the system convergence rate is effectively increased and the disturbances-related factors are suppressed. Simulation results show that the proposed method can handle the actual conditions better.
Application of Game Theory to Decision Making in Green Energy Promotion
Authors: Haitao Qiao
Published: March 2022

With the promotion and use of intelligent decision systems, intelligent green energy choice decision systems are also maturing. This paper uses the game theory approach of cost- benefit analysis basic local social and energy environment characteristics to analyse how to balance energy efficiency and economic benefits when choosing green energy by guiding and motivating building owners’ decisions to achieve the best environmental energy economic benefits. This paper uses green roof technology as a case study. Because it not only protects the natural environment and improves human living standards, but also creates economic benefits in many ways, it is important to incorporate such a decision theory into an intelligent decision-making system to improve the efficiency and intelligence of the decision and to provide a realistic proposal for the government to choose subsidies for environmental, economic and social benefits.
Design and Application of a Transient Response Test Module
Authors: Wang Fang , Wu Hesong , Wang Bin
Published: March 2022

The transient characteristics of low dropout regulator (LDO) are very important to the final imaging effect of mobile phone camera. This design is a test module developed for the transient response test of LDO products. This module is cost-efficient and time-efficient and function-trimmed, and the test results are quantifiable and repeatable which satisfy the needs of transient response test of LDO products. This article describes the test principle of transient response and the hardware design and implementation of transient response module. The validity of such modules shown by the result of a real test of a 1A LDO. More importantly, it points out the details that should be paid attention to in the test process. It provides a reference for IC design engineers and application test engineers, and one can easily build modules according to this paper for practical testing.
A Duration-distance Based Correction Strategy to Improve Cut-in Scenario Experience for Mass Production Adaptive Cruise Systems
Authors: Lu Yong , Yang Diange , Yang Jingning , Guo Jia , He Yichao , Tian He
Published: March 2022

The adaptive cruise system needs to meet the acceptance conditions of the vehicle manufacturer before mass production. One of the crucial evaluation scenarios is cut-in, especially when the distance between the target vehicle and the ego vehicle is close and the relative speed has little difference, or the vehicle in front suddenly brakes. In this paper, the desired acceleration and jerk of the adaptive cruise system are calculated using kinematic equations. The ego vehicle reaches the state of the target vehicle after a period of predicted time, where the predicted time is determined by the relative speed and distance between the two vehicles. To improve the subjective experience of the driver in the cut-in scene, the authors propose a fuzzy logic correction strategy based on the duration-distance of the target vehicle, which changes the trend of acceleration by reshaping the jerk. Cut-in simulation and real-vehicle test results show that this strategy can reduce the discomfort caused by rapid acceleration changes to the driver under the premise of ensuring the safety of the ego vehicle.
Substation Defect Detection Network Based on the Attention Model
Authors: Wang Zongzeng , Wang Peiyuan , Wang Yongjun , Yang Peiqiang , Cheng Lin
Published: March 2022

Applications of intelligent robot iterative inspection system in substation are attracting extensive interests. The defect detection in inspection system must consider both real-time and accuracy on small database samples. This paper proposes a defect detection network based on the attention model. We combine a triplet attention module with Yolo-v5 network for producing richer representations of defect features, which can improve the accuracy in calculating fast situation. We also give a robust data enhancement mechanism for extending the database. The experiment dataset contains actual images gathering from substation and they are labelled as PASCAL VOC dataset format by safety inspectors with many years of experience. The experiment results can demonstrate that the proposed method can effectively improve the accuracy without reducing the real time performance.
Hybrid DC Circuit Breaker with Integrated Self-charging and Current Limiting
Authors: Wang Jun , Pang Sumin , Wu Xin , Zhong Yilin , Kang Qiong , Tao Chuangchuang
Published: March 2022

With the rapid development of DC power systems in recent years, more stringent requirements have been put forward for the fast reliability of DC circuit breakers. At present, in the medium voltage DC circuit breaker, the mechanical switch commonly uses an external secondary power supply to charge the mechanism drive capacitor, which has the problems of large breaker size and high cost. In this paper, we propose a DC circuit breaker topology that uses short-circuit current to charge the mechanism drive capacitor of the mechanical switch. When the short-circuit current rises, a voltage drop is formed across the series inductor, and this voltage charges the drive capacitor in parallel through a diode, avoiding the use of a secondary power supply to charge the drive capacitor and reducing the complexity of the DC circuit breaker system. The operating principle of the circuit breaker is analysed and the rationality of the proposed scheme is verified by simulation calculations.
Study on Overvoltage Rise Rate Suppression Method for DC Interruption
Authors: Long Chen , Wu Yifei , Yang Yang , Yao Zhaomin , Xiao Yu , Kang Qiong , Zhang Feng , Tao Chuangchuang
Published: March 2022

DC circuit breaker is the key equipment for control and protection in the medium and high voltage DC system. Mechanical DC circuit breakers have transient overvoltage in breaking, which may lead to re-breakdown of the breaker or even breaking failure in severe cases. In this paper, the transient overvoltage in the breaking process of typical mechanical DC circuit breakers is studied. An improved topology which can supress the transient voltage is propose. The effect of different capacitance and resistance parameters on weakening the transient voltage is investigated, and the adaptability of the proposed method to different breaking currents is studied.
A Fish Feeding Robot Prototype with a Water Level Control System Using a Proportional – Integral Controller
Authors: Muhammad Abdul Kadir , Dermawan
Published: March 2022

The purpose of this study is to develop a fish feeding robot prototype that equipped with a water level control system for pond use and to propose an effective control scheme for the robot prototype and the water level control system. The system used in this paper consists of a feed storage tank, a feed distribution mechanism, a feed ejection mechanism, an ejector position turning mechanism, a water level control system, a base and a solar panel system for energy sources. The three mechanisms used three DC motors as actuator, respectively. The water level control system used a water pump to pump water out of pond when the level of water exceeds the maximum level limit, and an ultrasonic sensor to measure the level of water in pond. On – Off and proportional – integral (PI) controllers used to control DC motors of the three mechanisms, and the water level control system, respectively. Performances of the robot prototype with the water level control system were examined through laboratory scale experiments. The result of the conducted experiments are presented and discussed.
Synthesis of Asynchronous Control and Synchronization for Multi-Robot System under Finite Horizon Temporal Task
Authors: Xu Ning , Chen Runfeng , Huang Yuchong , Chen Yiting , Li Jie
Published: March 2022

This paper proposes a novel control synthesis method for cooperative multi-robot systems to fulfil a global mission given as linear temporal logic on finite traces (LTLf). Transition systems are used as the form of distributed controllers, such that the robots are driven to act asynchronously and synchronize on shared actions for necessary local coordination. An automated control synthesis method is proposed, which generates provably correct distributed controllers by two steps: (i) synthesizing satisfiable global controllers for the parallel composition of the uncontrolled system, such that the global specification is met; (ii) searching for a decomposable global controller among them over the synchronization scheme to obtain decomposed distributed controllers. The method is integrated into a closed-loop mission execution framework, of which the applicability is demonstrated with a simulation based on ROS.
Influence of Transverse Vibration Amplitude on the Loosening of Bolted Joint by Finite Element Simulation
Authors: Luo Hanwu , Zhang Guoli , Zhang Jie , Shang Xin , Yang Jialun , Liu Bin
Published: March 2022

A detailed finite element (FE) model of M20 bolted joint is established. Using the FE model, the loosening processes of bolted joint under different transverse vibration amplitude are simulated. The results show that there exists a critical transverse vibration amplitude. When the transverse vibration amplitude is smaller than the critical transverse vibration amplitude, the bolted joint will not loosen. When it is larger than the critical transverse vibration amplitude, the bolted joint will loosen. The larger the transverse vibration amplitude is, the faster the bolted joint loosens. Based on clamping force, nut rotation angle, bolt torsion deformation and slip of thread contact surface, the mechanism of the influence of transverse vibration amplitude on the loosening of the bolted joint is analyzed.
Disturbance Compensation-Based Nonlinear Control for Pneumatic Artificial Muscle Systems With Hardware Experiments
Authors: Liu Gendi , Chen Yiheng , Sun Ning , Yang Tong , Qin Yanding , Fang Yongchun
Published: March 2022

Owing to variable stiffness, natural compliance, and similarities with skeletal muscles, pneumatic artificial muscles (PAMs) have been widely utilized in the fields of bionic robots, medical rehabilitation, and industrial manufacturing. However, in addition to high nonlinearities, time variation, and uncertainties, PAMs are extremely sensitive to external disturbances in practical applications, most of which are unknown, complicated, and constantly changing. Regarding these challenging issues, a disturbance compensation-based robust control method is proposed in this paper, which realizes satisfactory tracking control of PAM systems without a prior knowledge of exact models. Particularly, without assuming that disturbances or their first-order derivatives are invariable, a high-order disturbance observer is proposed to estimate lumped disturbances and their nth-order derivatives. On this basis, a nonlinear feedback controller is designed to simultaneously ensure that the observation errors converge to zero in finite time and the tracking error converges to zero asymptotically. Further, based on Lyapunov techniques, the stability analysis for the equilibrium point of the closed-loop system is provided in detail. Finally, the practicability and the robustness of the proposed method are validated by hardware experiments on a self-built horizontal PAM platform.
Wearable Cable-driven Lower Limb Assistive Device with Demonstration System for Walking Assistance
Authors: Zhao Changchen , Lu Xingzhou , Li Jinwen , Zhao Zheng , Feng Yuanjing
Published: March 2022

Flexible assistive device has become an active research topic in recent years due to their promising application prospect in rehabilitation and medical care. Existing devices suffer from the balance between wearable lightness and control effectiveness. This paper introduces a cable-driven lower limb assistive device with a demonstration system for walking assistance. We rely on plantar pressure sensors to determine the gait phase and employ pose sensors to obtain the trajectory of the hip joint angle. We model the human lower limb based on the Lagrangian method and employ the PID algorithm to control the motor’s drive torque during the swing phase. Simulation results demonstrate the effectiveness of the control algorithm on the model’s trajectory tracking and the robustness to disturbance of the flexible device to provide partial walking assistance. Additionally, a software demonstration system based on Unity 3D is designed to monitor the wear’s motion status in real-time, which provides visual feedback for better rehabilitation training.
Research on U-Net based Underwater Holothurian Recognition Method
Authors: Wang Wei , Xing Bowen , Zhang Lan , Wang Wugui
Published: March 2022

Holothurians can integrate into nearby environment by changing body color which increased the difficulty of version identification. A U-Net network based visual recognition algorithm suitable for underwater organisms was proposed. The backbone feature extraction network adopted VGG16. In additional, upper sampling was used twice for feature fusion. Test results shown that the algorithm has high recognition accuracy and good feature extraction for holothurian with different shapes in natural environment.
Safety Helmet Wearing Detection Based on YOLOv5 of Attention Mechanism
Authors: Xu Z P , Zhang Y , Cheng J , Ge G
Published: March 2022

Aiming at problems of low accuracy and strong detection interference of the existing safety helmet wearing detection algorithms, an object detection algorithm by adding the squeeze-and-excitation block based on the YOLOv5 algorithm is proposed in this paper. The proposed method can not only obtain the weight of picture channel, but also accurately separate the foreground and background of the picture. Keeping all parameters unchanged, the proposed method and the YOLOv5 algorithm are applied to detect the safety helmet data set in the experiment. The result shows that the YOLOv5 algorithm with the squeeze-and-excitation block has an average detection accuracy of 94.5% for safety helmets and an average detection accuracy of 92.7% for human heads. The mAP value detected by the proposed method is 2% ∼2.5% higher than using YOLOv5 algorithm directly.
A Continuous Gesture Segmentation and Recognition Method for Human-Robot Interaction
Authors: Fan Jinlong , Yue Yang , Wang Yu , Wan Bei , Li Xudong , Hua Gengpai
Published: March 2022

The process of human-computer cooperation using gesture recognition can make people get rid of the limitations of traditional input devices such as mouse and keyboard, and control artificial intelligence devices more efficiently and naturally. As a new way of human-robot interaction (HRI), gesture recognition has made some progress. There are many ways to realize gesture recognition combined with visual recognition, motion information acquisition and EMG signal. The research on isolated language gesture recognition has been quite mature, but the expression semantics of isolated gestures is single. In order to improve the interaction efficiency, the application of continuous gesture recognition is essential. This paper studies its application in continuous sign language sentence recognition based on inertial sensor and rule matching recognition algorithm. The recognition rate of nine single HRI gestures is 92.7%, and the HRI of combined gestures is realized.
DM-Net:a Depth-separable convolution and Multi-Scale Network for retinal blood vessel segmentation
Authors: Li Wei , Wu Cong , Cheng YuQing , Yang Zhi
Published: March 2022

Retina segmentation plays an important role in the medical field,In recent years, some proposed networks have some problems, such as single receptive field, huge parameters, and difficulty in training, which affect the segmentation results. In this paper, a U-Net-based DM-Net with deep separable convolution and multi-scale is proposed, a residual multiscale module is designed to reduce the parameters and improve the feature extraction ability. In order to cope with the feature information fusion at different levels and the sudden decrease in the number of feature channels in the decoder, the channel attention mechanism is applied. Experiments on the public data set CHASE_DB 1 show that DM-Net has achieved good results compared with other networks, especially in ACC (0.9748) and SP (0.9882). At the same time, it has few parameters and fast convergence speed.
DOI correction for gamma ray energy reconstruction based on energy segment in 3D position-sensitive CdZnTe detectors
Authors: Li Y. , Gong P. , Tang X. , Hu Z. , Wang P. , Tian F. , Wu S. , Ye M. , Zhou C. , Zhu X.
Published: March 2022

The amplitude of the induced signal in 3D CdZnTe detector depends on the depth of interaction (DOI). Therefore, calibrating the detector by using DOI correction technology plays a crucial role in improving the energy resolution of the detectors to gamma rays. The current DOI correction method focuses on the single energy gamma rays, and its application to multiple energy gamma-rays are not found. In this study, we propose an improved energy correction algorithm with excellent correction results in the multiple energy gamma-ray detection. In the experiment, the DOI correction factors of a CdZnTe detector under different energies are discussed. The energy resolution and peak height of multiple energy peaks in the energy spectrum are significantly improved by using the segment energy correction method. We also extend the DOI correction method to the gamma detectors used in the Compton imaging, and the influence of this method on the Compton imaging quality is also discussed.
For a single 60Co point source, the intrinsic efficiency increases from 6.5‰ to 8.3‰.
Biodegradable iron-silicon implants produced by additive manufacturing
Authors: Bondareva J V , Dubinin O N , Kuzminova Y O , Shpichka A I , Kosheleva N V , Lychagin A V , Shibalova A A , Pozdnyakov A A , Akhatov I S , Timashev P S , Evlashin S A
Published: March 2022

Due to many negative and undesirable side effects from the use of permanent implants, the development of temporary implants based on biocompatible and biodegradable materials is a promising area of modern medicine. In the presented study, we have investigated complex-shaped iron-silicon (Fe–Si) scaffolds that can be used as potential biodegradable framework structures for solid implants for bone grafting. Since iron and silicon are biocompatible materials, and their alloy should also have biocompatibility. It has been demonstrated that cells, mesenchymal stromal cells derived from the human umbilical cord (UC-MSC) and 3T3, were attached to, spread, and proliferated on the Fe–Si scaffolds’ surface. Most of UC-MSC and 3T3 remained viable, only single dead cells were observed. According to the results of biological testing, the scaffolds have shown that deposition of calcium phosphate particles occurs on day one in the scaffold at the defect site that can be used as a primary marker of osteodifferentiation. These results demonstrate that the 3D-printed porous iron-silicon (Fe–Si) alloy scaffolds are promising structures for bone grafting and regeneration.
Multifaceted tannin crosslinked bioinspired dECM decorated nanofibers modulating cell–scaffold biointerface for tympanic membrane perforation bioengineering
Authors: Hussain Zahid , Ding Pi , Zhang Liwei , Zhang Yajie , Ullah Salim , Liu Yuanshan , Ullah Ismat , Wang Zhili , Zheng Penghui , Pei Renjun
Published: March 2022

Tympanic membrane (TM) perforation leads to persistent otitis media, conductive deafness, and affects life quality. Ointment medication may not be sufficient to treat TM perforation (TMP) due to the lack of an underlying tissue matrix and thus requiring a scaffold-based application. The engineering of scaffold biointerface close to the matrix via tissue-specific decellularized extracellular matrix (dECM) is crucial in instructing cell behaviour and regulating cell-material interaction in the bioengineering domain. Herein, polycaprolactone (PCL) and TM-dECM (from Sprague–Dawley rats) were combined in a different ratio in nanofibrous form using an electrospinning process and crosslinked via tannic acid. The histological and biochemical assays demonstrated that chemical and enzymatic decellularization steps removed cellular/immunogenic contents while retaining collagen and glycosaminoglycan. The morphological, physicochemical, thermomechanical, contact angle, and surface chemical studies demonstrated that the tannin crosslinked PCL/dECM nanofibers fine-tune biophysical and biochemical properties. The multifaceted crosslinked nanofibers hold the tunable distribution of dECM moieties, assembled into a spool-shaped membrane, and could easily insert into perforated sites. The dECM decorated fibers provide a preferable biomimetic matrix for L929 fibroblast adhesion, proliferation, matrix adsorption, and f-actin saturation, which could be crucial for bioengineering. Overall, dECM patterning, surface hydrophilicity, interconnected microporosities, and multifaceted nanofibrous biosystem modulate cell–scaffold performance and could open opportunities to reconstruct TMP in a biomimetic fashion.
Biomass stocks in California’s fire-prone forests: mismatch in ecology and policy
Authors: Bernal Alexis A , Stephens Scott L , Collins Brandon M , Battles John J
Published: March 2022

Restoration of fire-prone forests can promote resiliency to disturbances, yet such activities may reduce biomass stocks to levels that conflict with climate mitigation goals. Using a set of large-scale historical inventories across the Sierra Nevada/southern Cascade region, we identified underlying climatic and biophysical drivers of historical forest characteristics and projected how restoration of these characteristics manifest under future climate. Historical forest conditions varied with climate and site moisture availability but were generally characterized by low tree density (∼53 trees ha−1), low live basal area (∼22 m2 ha−1), low biomass (∼34 Mg ha−1), and high pine dominance. Our predictions reflected broad convergence in forest structure, frequent fire is the most likely explanation for this convergence. Under projected climate (2040–2069), hotter sites become more prevalent, nearly ubiquitously favoring low tree densities, low biomass, and high pine dominance. Based on these projections, this region may be unable to support aboveground biomass >40 Mg ha−1 by 2069, a value approximately 25% of current average biomass stocks. Ultimately, restoring resilient forests will require adjusting carbon policy to match limited future aboveground carbon stocks in this region.
Climate-induced fire regime amplification in Alberta, Canada
Authors: Whitman Ellen , Parks Sean A , Holsinger Lisa M , Parisien Marc-André
Published: March 2022

Acting as a top-down control on fire activity, climate strongly affects wildfire in North American ecosystems through fuel moisture and ignitions. Departures from historical fire regimes due to climate change have significant implications for the structure and composition of boreal forests, as well as fire management and operations. In this research, we characterize the relationship between trends in climate and fire regime characteristics, for a study area predominantly in Alberta, Canada. We examined trends of fire and climate in northwestern boreal forests using time series analysis of downscaled historical annual climate, fire history (1970–2019), and fire severity (the impacts of wildfire on plants and organic biomass; 1985–2018). We represented fire severity using the relativized burn ratio (RBR) calculated from multispectral Landsat imagery. The climate of the study area has significantly warmed and dried over the past 50 years. Over the same period the annual number of large wildfires, area burned, and fire sizes in the study area significantly increased. Furthermore, the likelihood, area, and number of extreme short-interval reburns (≤15 years between fires; 1985–2019) also significantly increased. During the study period, the portion of forested unburned islands within fire perimeters significantly declined, and fire severity (RBR) increased in open conifer and mixedwood forests. These fire regime changes are significantly correlated with annual climate variability, and a path analysis supports the hypothesis that annual climate patterns have led to fire regime shifts. The increasing fire activity in this region has implications for forest ecology and habitat availability, as the disruption of the fire regime is likely to alter forest recovery. Managers may face increasing challenges to fire suppression if the observed trends of increasing hotter and drier annual climate in the study area persist, driving extreme fire activity.
A modeler’s guide to studying the resilience of social-technical-environmental systems
Authors: Tamberg Lea A , Heitzig Jobst , Donges Jonathan F
Published: March 2022

The term ‘resilience’ is increasingly being used in Earth system science and other disciplines which study what could be called ‘social-technical-environmental systems’—systems composed of closely interacting social (e.g. economic and political), technical (e.g. energy production infrastructure), and environmental components (e.g. climate and the biosphere). However, the diversity of resilience theories and a certain (intended) openness of proposed definitions can lead to misunderstandings and may impede their application to complex systems modelling. We propose a guideline that aims to ease communication as well as to support systematic development of research questions and models in the context of resilience. It can be applied independently of the modelling framework or underlying theory of choice. At the heart of this guideline is a checklist consisting of four questions to be answered: (1) Resilience of what? (2) Resilience regarding what? (3) Resilience against what? (4) Resilience how? We refer to the answers to these resilience questions as the ‘system’, the ‘sustainant’, the ‘adverse influence’, and the ‘response options’. The term ‘sustainant’ is a neologism describing the feature of the system (state, structure, function, pathway, …) that should be maintained (or restored quickly enough) in order to call the system resilient. The use of this proposed guideline in the field of Earth system resilience is demonstrated for the application example of a potential climate tipping element: the Amazon rainforest. The example illustrates the diversity of possible answers to the checklist’s questions as well as their benefits in structuring the modelling process. The guideline supports the modeler in communicating precisely what is actually meant by ‘resilience’ in a specific context. This combination of freedom and precision could help to advance the resilience discourse by building a bridge between those demanding unambiguous definitions and those stressing the benefits of generality and flexibility of the resilience concept.
Hourly accounting of carbon emissions from electricity consumption
Authors: Miller Gregory J , Novan Kevin , Jenn Alan
Published: March 2022

Carbon accounting is important for quantifying the sources of greenhouse gas (GHG) emissions that are driving climate change, and is increasingly being used to guide policy, investment, business, and regulatory decisions. The current practice for accounting emissions from consumed electricity, guided by standards like the GHG protocol, uses annual-average grid emission factors, although previous studies have shown that grid carbon intensity varies across seasons and hours of the day. Previous case studies have shown that annual-average carbon accounting can bias emission inventories, but none have shown that this bias is substantial or widespread. This study addresses this gap by calculating emission inventories for thousands of residential, commercial, industrial, and agricultural facilities across the US, and explores the magnitude and direction of this bias compared to hourly accounting of emissions. Our results show that annual-average accounting can over- or under-estimate carbon inventories as much as 35% in certain settings but result in effectively no bias in others. Bias will be greater in regions with high variation in carbon intensity, and for end-users with high variation in their electricity consumption across hours and seasons. As variation in carbon intensity continues to grow with growing shares of variable and intermittent renewable generation, these biases will only continue to worsen in the future. In most cases, using monthly-average emission factors does not substantially reduce bias compared to annual averages. Thus, the authors recommend that hourly accounting be adopted as the best practice for emissions inventories of consumed electricity.
Spatial variability of global lake evaporation regulated by vertical vapor pressure difference
Authors: Farooq Umar , Liu Heping , Zhang Qianyu , Ma Yulong , Wang Jingfeng , Shen Lian
Published: March 2022

Evaporation (E) from about 300 million lakes worldwide without plant physiological constraints directly reflects hydrological response to atmospheric forcings. However, it remains inadequately understood about what regulate spatial variability of global lake E across seasons. Here we show that vertical vapor pressure difference (

e

D

) accounts for 66% of the spatial variability of annual E, followed by wind speed (16%). The

e

D

is also the predominant factor modulating diurnal variability in E and causing greater E at night than during the daytime. As a consequence, spatial variability in nighttime E strongly regulates that in global E across seasons. Therefore, the observed widespread, heterogeneous changes in lake surface temperature that imply spatial variability in

e

D

may have contributed to changes in global E variability.
Bayesian inference of scaled versus fractional Brownian motion
Authors: Thapa Samudrajit , Park Seongyu , Kim Yeongjin , Jeon Jae-Hyung , Metzler Ralf , Lomholt Michael A
Published: March 2022

We present a Bayesian inference scheme for scaled Brownian motion, and investigate its performance on synthetic data for parameter estimation and model selection in a combined inference with fractional Brownian motion. We include the possibility of measurement noise in both models. We find that for trajectories of a few hundred time points the procedure is able to resolve well the true model and parameters. Using the prior of the synthetic data generation process also for the inference, the approach is optimal based on decision theory. We include a comparison with inference using a prior different from the data generating one.
3D bioprinted, vascularized neuroblastoma tumor environment in fluidic chip devices for precision medicine drug testing
Authors: Nothdurfter Daniel , Ploner Christian , Coraça-Huber Débora C , Wilflingseder Doris , Müller Thomas , Hermann Martin , Hagenbuchner Judith , Ausserlechner Michael J
Published: March 2022

Neuroblastoma is an extracranial solid tumor which develops in early childhood and still has a poor prognosis. One strategy to increase cure rates is the identification of patient-specific drug responses in tissue models that mimic the interaction between patient cancer cells and tumor environment. We therefore developed a perfused and micro-vascularized tumor-environment model that is directly bioprinted into custom-manufactured fluidic chips. A gelatin-methacrylate/fibrin-based matrix containing multiple cell types mimics the tumor-microenvironment that promotes spontaneous micro-vessel formation by embedded endothelial cells. We demonstrate that both, adipocyte- and iPSC-derived mesenchymal stem cells can guide this process. Bioprinted channels are coated with endothelial cells post printing to form a dense vessel—tissue barrier. The tissue model thereby mimics structure and function of human soft tissue with endothelial cell-coated larger vessels for perfusion and micro-vessel networks within the hydrogel-matrix. Patient-derived neuroblastoma spheroids are added to the matrix during the printing process and grown for more than two weeks. We demonstrate that micro-vessels are attracted by and grow into tumor spheroids and that neuroblastoma cells invade the tumor-environment as soon as the spheroids disrupt. In summary, we describe the first bioprinted, micro-vascularized neuroblastoma—tumor-environment model directly printed into fluidic chips and a novel medium-throughput biofabrication platform suitable for studying tumor angiogenesis and metastasis in precision medicine approaches in future.
The cell viability assay analysis and physicochemical characterization of porous hydroxyapatite scaffold using honeycomb and paraffin wax as polymeric porogen for bone tissue engineering
Authors: Sari W , Sari M , Yusuf Y
Published: March 2022

To fabricate and characterize the porous hydroxyapatite-based scaffold, honeycomb as a natural polymer (HA/HCB) and paraffin wax (HA/Wax) were used. The fabrication of scaffold using the porogen leaching method was varied temperatures between 700, 900, and 1100 °C. Theoretically, the temperature of calcination influenced the morphology of the scaffold, crystallite size, functional group, and porosity. According to the previous study, the crystallite size of the polymer scaffold is less than 100 nm. The HA-based scaffold was analyzed by the Energy Dispersive X-Ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM), X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and tested by the cell viability. According to the XRD results, the crystallite size of HA/HCB scaffold decreases, while scaffold HA/Wax crystallite size tends to decrease when calcination temperature increases. As calcination temperature increases, porosity tends to be small for both HA/HCB and HA/wax scaffolds. The scaffold HA/HCB 900 °C has interconnected pores, uniform, and small porosity. In contrast, the scaffold HA/Wax 900 °C has fewer interconnected pores and non-uniform particles. The FTIR result of the HA/HCB 900 °C has C-H functional group, affecting cell viability. Through MTT (3-(4,5-Dimethylthiazol-2-yl)−2,5 diphenyltetrazolium bromide) assays, the cell viability value of the HA/Wax 900 °C was greater than the HA/HCB 900 °C for 48 h incubated time. It is caused by the alkane chains on HA/HCB, causing the death of cells. Considering cell viability assay studies for the nanocomposite scaffold, the obtained results confirm the non-toxicity of the material.
Ocimum tenuiflorum L mediated green synthesis of silver and selenium nanoparticles: antioxidant activity, cytotoxicity and density functional theory studies
Authors: Olawale Femi , Ariatti Mario , Singh Moganavelli
Published: March 2022

Inorganic nanoparticles (NPs) have found extensive application in medicine and pharmaceutics. Although chemical synthesis of NPs is the most commonly employed technique, it is often associated with toxicities due to the nature of the precursors and the experimental conditions used. Hence, there is a need for a safer biosynthetic approach. The current study involves the green synthesis of silver (Ag) and selenium (Se) NPs using an aqueous Ocimum tenuiflorum inflorescence extract. Total phenol and HPLC-MS based phytochemical analysis of the extract was performed. NPs were analysed using UV-visible, and Fourier transform infrared (FTIR) spectroscopy, electron microscopy (EM), x-ray diffraction (XRD) and nanoparticle tracking analysis (NTA). Surface plasmon resonance bands at 433 nm and 285 nm confirmed the synthesis of the Ag and SeNPs, respectively. NPs were monodisperse, small (<65 nm), with good stability and significant antioxidant activity. Cytotoxicity evaluated in the human embryonic kidney (HEK293), cervical carcinoma (HeLa) and breast adenocarcinoma (MCF-7) cells showed a dose-dependent trend with Se possessing better biocompatibility in the normal HEK293 cells than Ag. Density functional theory identified anthocyanins (delphinidin-5-O-beta-d-glucoside and delphinidin-3-O-glucoside) to have the most favourable NP-reducing and stabilising potential from the identified plant compounds.
An epigenetic small molecule screen to target abnormal nuclear morphology in human cells
Authors: Atanasova Kalina R. , Chakraborty Saptarshi , Ratnayake Ranjala , Khare Kshitij D. , Luesch Hendrik , Lele Tanmay P.
Published: March 2022

Irregular nuclear shapes are a hallmark of human cancers. Here we performed a high-throughput small molecule screen toward abnormal nuclear morphology. Several compounds regularized nuclear shapes in noncancer and cancer cells. This approach of targeting nuclear abnormalities may be useful for screening new types of cancer therapies.
A Combined Biomarker of Bright CD38 and MYC ≥55% Is Highly Predictive of Double-/Triple-Hit High-Grade B-Cell Lymphoma
Authors: Alsuwaidan Abdullah , Koduru Prasad , Fuda Franklin , Manuel Jaso Jesse , Chen Mingyi , Rosado Flavia , Luu Hung S , Sweed Nathan , Garcia Rolando , Doucet Meggie , Desai Neil B , Kumar Kiran A , Awan Farrukh T , Ramakrishnan Geethakumari Praveen , Chen Weina
Published: March 2022

Objectives

Diagnosis of high-grade B-cell lymphoma with MYC and BCL2 or BCL6 rearrangements (double-/triple-hit lymphoma [DTHL]) appears to mandate fluorescence in situ hybridization (FISH) testing for all large B-cell lymphoma (LBCL). Given the low incidence of DTHL, we aimed to identify flow cytometry (FC) and immunohistochemistry (IHC) features of DTHL that could be used to develop an optimal screening strategy. This combined FC-IHC approach has not yet been studied.

Methods

We compared features of 40 cases of DTHL and 39 cases of diffuse LBCL (DLBCL) without MYC rearrangement.

Results

Bright CD38 expression (CD38bright) by FC, high MYC expression (≥55%), and double-expressor phenotype by IHC were significantly associated with DTHL. The biomarker combining FC and IHC, CD38bright and/or MYC ≥55%, was superior to FC and IHC markers alone in predicting DTHL. Restricting FISH testing to approximately 25% of LBCL based on CD38brightand/or MYC ≥55% would detect approximately 95% of DTHL-BCL2 and approximately 75% of DHL-BCL6.

Conclusions

Our study demonstrated that the novel biomarker of CD38bright and/or MYC ≥55% is highly predictive of DTHL. Awareness of the advantages and limitations of this screening strategy would facilitate development of a rational diagnostic workflow to provide high-quality patient care.