bluuebunny/crossref_metadata_2025 huggingface dataset:
Problem-Based Teaching: An Exploratory Analysis of Discourse Methods of Peer Facilitators in a Summer Engineering Bridge Program
Authors: Sims Eric , Horton David , Steele Jaiah , Jarvis Jeanette , Greer Tomika W. , Stokes Donna W. , Henderson Jerrod A.
Published: June 2024

As engineering educators attempt to develop solutions to increase student retention and graduation rates and decrease student departures from their majors during the first two years of study, findings from a summer bridge program at a large minority-serving institution (MSI) show promise for practices that could potentially help to mitigate these issues. Summer bridge strategies have been shown to be effective in assisting in college students’ transition from first to sophomore year. This study comprises a case study of a chemical engineering summer bridge program in which undergraduate peer facilitators introduced sophomore-level chemical engineering material and energy balance course material to their peers. The goal of this study was to understand the types of discourse methods used during problem-solving sessions by peer facilitators and how students’ learning experiences were impacted. Data for this study were collected via video observations and a post-program open-ended survey. Authors found that peer facilitators created an environment where students felt encouraged and supported and could relate to facilitators and course materials in new ways. This work further illustrates promising practices of using peer facilitators that need further attention, along with the potential for how engagement and learning could be enhanced by the more formal preparation of peer facilitators.
Why, When, and for Whom Does Career Education in Secondary Schools Work? A Qualitative Study of Stakeholders’ Perspectives in The Netherlands
Authors: de Vries Nicky , Meeter Martijn , Huizinga Mariëtte
Published: June 2024

Career education in secondary schools plays a pivotal role in supporting students as they navigate the complex decision-making process involved in the transition to higher education. However, the evidence base regarding the effectiveness of career education is limited and fragmented, with a distinct lack of clarity regarding the underlying mechanisms. This study aimed to identify the best practices and underlying mechanisms of career education within Dutch secondary education. Based on focus group interviews with stakeholders with diverse interests and positions (N = 25), we identified five categories of best practice activities alongside a framework consisting of ten mediators, eight moderators, a meta-moderator, and four contextual factors. This framework, while reinforcing some previous identified mechanisms, brings new elements into focus, distinguishing additional mechanisms and their categorisation as mediators, moderators, and contextual factors. These findings may serve as a foundational framework for future research and can support schools in enhancing their career education curricula. It is crucial that career education activities align with the students’ current capacities and potential for growth, ensuring that these programs are responsive to students’ developmental stages and their zone of proximal development.
Facilitators and Barriers Perceived by German Teachers Considering Basic Life Support Education in School—A Qualitative Study
Authors: Dumcke Rico , Wegner Claas , Wingen Sabine , Rahe-Meyer Niels
Published: June 2024

This qualitative study aims to analyse the personal qualification, attitudes and the pedagogical concepts of German teachers as experts in their profession regarding basic life support (BLS) education in secondary schools. Thirteen (n = 13) secondary school teachers participated in semi-structured expert interviews and were interviewed for at least 20 to 60 min regarding BLS student education. Interviews were semi-structured with guiding questions addressing (1) personal experience, (2) teacher qualification for BLS and (3) implementation factors (e.g., personal, material and organisational). Audio-recorded interviews were analysed by content analysis, generating a coding system. School teachers provided a heterogeneous view on implementation-related processes in BLS education. Many teachers were educated in first aid, acknowledge its importance, but had no experience in teaching BLS. They want to assure being competent for teaching BLS and need tailored trainings, materials, pedagogical information and the incorporation into the curriculum. Also, the management of time constraints, unwilling colleagues, or young students being overwhelmed were commonly mentioned considerations. Concluding, teachers reported to be willing to teach BLS but a stepwise implementation framework incorporating practice-oriented qualification and educational goals is missing.
Electrical Resistance as an Aggregate Characteristic of Coke Properties for Electrochemical and Coke Production
Authors: Miroshnichenko Denis , Shmeltser Kateryna , Kormer Maryna , Soloviov Yevhen , Pyshyev Serhiy , Korchak Bohdan , Shved Mariia , Prysiazhnyi Yuriy
Published: June 2024

The influence of the component composition of coal batches and the final temperature of the coking process on the resistivity of coke was studied. Taking into account that the resistivity and reactivity are influenced by some common factors, such as the temperature level and coke readiness, which indicates the orderliness of its structure, the relationship between these indicators was established. The electrical resistivity can be considered a cumulative characteristic of coke properties, as evidenced by the mathematical dependencies of the change electrical resistance on the ash content, sulfur content, volatile yield, and petrographic composition. Analysis of the dependencies and their statistical evaluation indicate that the studied relationships are characterized by high values of correlation (0.6–0.84). The proposed regression equations can be recommended for optimizing the component composition and quality of production batches, given their significant impact on the resistivity of coke. This is especially relevant when coke is used in electrothermal processes, since the productivity and the electrical and thermal efficiency of the furnace depends on the resistivity of the coke in electrochemical processes in which carbon materials are used as anodes and lining elements and in the production of capacitor technology. As the resistivity test requires much less time to perform than the reactivity test, it can be considered as an alternative approach to the reactivity testing currently performed for quality control purposes.
TrustHealth: Enhancing eHealth Security with Blockchain and Trusted Execution Environments
Authors: Li Jun , Luo Xinman , Lei Hong
Published: June 2024

The rapid growth of electronic health (eHealth) systems has led to serious security and privacy challenges, highlighting the critical importance of protecting sensitive healthcare data. Although researchers have employed blockchain to tackle data management and sharing within eHealth systems, substantial privacy concerns persist as a primary challenge. In this paper, we introduce TrustHealth, a secure data sharing system that leverages trusted execution environment (TEE) and blockchain technology. TrustHealth leverages blockchain to design smart contracts to offer robust hashing protection for patients’ healthcare data. We provide a secure execution environment for SQLCipher, isolating all sensitive operations of healthcare data from the untrusted environment to ensure the confidentiality and integrity of the data. Additionally, we design a TEE-empowered session key generation protocol that enables secure authentication and key sharing for both parties involved in data sharing. Finally, we implement TrustHealth using Hyperledger Fabric and ARM TrustZone. Through security and performance evaluation, TrustHealth is shown to securely process massive encrypted data flows at a rate of 5000 records per second, affirming the feasibility of our proposed scheme. We believe that TrustHealth offers valuable guidelines for the design and implementation of similar systems, providing a valuable contribution to ensuring the privacy and security of eHealth systems.
A Robust and Adaptive AUV Integrated Navigation Algorithm Based on a Maximum Correntropy Criterion
Authors: Li Pinchi , Sun Xiaona , Chen Ziyun , Zhang Xiaolin , Yan Tianhong , He Bo
Published: June 2024

In the underwater domain where Autonomous Underwater Vehicles (AUVs) operate, measurements may suffer from the impact of outliers and non-Gaussian noise. These factors can potentially undermine the efficacy of integrated navigation algorithms. The Maximum Correntropy Criterion (MCC) can be utilized to enhance the robustness of AUV integrated navigation algorithms through the construction and maximization of the correntropy function. Notwithstanding, the underwater environment occasionally presents unknown time-varying noise, a situation for which the MCC lacks adaptability. In response to this issue, our study introduces a novel integrated navigation algorithm that synergizes the MCC and the Variational Bayesian approach, thereby augmenting both the robustness and adaptability of the system. Initially, we implement the MCC along with a mixture kernel function in an Unscented Kalman Filter (UKF) to strengthen the robustness of the AUV integrated navigation algorithms amidst the complexities inherent to underwater environmental conditions. Additionally, we utilize the Variational Bayesian method to refine the approximation of measurement noise covariance, thereby boosting the algorithm’s adaptability to fluctuating scenarios. We evaluate the performance of our proposed algorithm using both simulation and sea trial datasets. The experimental results reveal a significant enhancement in the Root Mean Square Error (RMSE) and navigation accuracy of our proposed algorithm. Notably, in a complex noise environment, our algorithm achieves, approximately, a 50% improvement in navigation accuracy over other established algorithms.
A Security Analysis of Cryptocurrency Wallets against Password Brute-Force Attacks
Authors: Byun Hyeonsu , Kim Jueun , Jeong Yunseok , Seok Byoungjin , Gong Seonghyeon , Lee Changhoon
Published: June 2024

Currently, the monetary value of cryptocurrencies is extremely high, leading to frequent theft attempts. Cyberattacks targeting cryptocurrency wallets and the scale of these attacks are also increasing annually. However, many studies focus on large-scale exchanges, leading to a lack of research on cryptocurrency wallet security. Nevertheless, the threat to individual wallets is real and can lead to severe consequences for individuals. In this paper, we analyze the security of the open-source cryptocurrency wallets Sparrow, Etherwall, and Bither against brute-force attacks, a fundamental threat in password-based systems. As cryptocurrency wallets use passwords to manage users’ private keys, we analyzed the private key management mechanism and implemented a password verification oracle. We used this oracle for brute-force attacks. We identified the private key management mechanism by conducting a code-level investigation and evaluated the three wallets’ security through practical experimentation. The experiment results revealed that the wallets’ security, which depends on passwords, could be diminished due to the password input space and the configuration of password length settings. We propose a general methodology for analyzing the security of desktop cryptocurrency wallets against brute-force attacks and provide practical guidelines for designing secure wallets. By using the analysis methods suggested in this paper, one can evaluate the security of wallets.
PMSM Sensorless Control Based on Moving Horizon Estimation and Parameter Self-Adaptation
Authors: Chen Aoran , Chen Wenbo , Wan Heng
Published: June 2024

The field of sensorless control of permanent magnet synchronous motor (PMSM) systems has been the subject of extensive research. The accuracy of sensorless controllers depends on the precise estimation of PMSM state quantities, including rotational speed and rotor position. In order to enhance state estimation accuracy, this paper proposes a moving horizon estimator that can be utilized in the sensorless control system of PMSM. Considering the parameter variations observed in PMSM, a nonlinear mathematical model of PMSM is established. A model reference adaptive system (MRAS) is employed to identify parameters such as resistance, inductance, and magnetic chain in real time. This approach can mitigate the impact of parameter fluctuations. Moving horizon estimation (MHE) is an estimation method based on optimization that can directly handle nonlinear system models. In order to eliminate the influence of external interference and improve the robustness of state estimation, a method based on MHE has been designed for PMSM, and a sensorless observer has been established. Considering the traditional MHE with large computation and high memory occupation, the calculation of MHE is optimized by utilizing a Hessian matrix and gradient vector. The speed and position of the PMSM are estimated within constraints during a single-step iteration. The results of the simulation demonstrate that in comparison to the traditional control structure, the estimation error of rotational speed and rotor position can be reduced by utilizing the proposed method. A more accurate estimation can be achieved with good adaptability and computational speed, which can enhance the robustness of the control system of PMSM.
Neutral Facial Rigging from Limited Spatiotemporal Meshes
Authors: Hou Jing , Weng Dongdong , Zhao Zhihe , Li Ying , Zhou Jixiang
Published: June 2024

Manual facial rigging is time-consuming. Traditional automatic rigging methods lack either 3D datasets or explainable semantic parameters, which makes it difficult to retarget a certain 3D expression to a new face. To address the problem, we automatically generate a large 3D dataset containing semantic parameters, joint positions, and vertex positions from a limited number of spatiotemporal meshes. We establish an expression generator based on a multilayer perceptron with vertex constraints from the semantic parameters to the joint positions and establish an expression recognizer based on a generative adversarial structure from the joint positions to the semantic parameters. To enhance the accuracy of key facial area recognition, we add local vertex constraints for the eyes and lips, which are determined by the 3D masks computed by the proposed projection-searching algorithm. We testthe generation and recognition effects on a limited number of publicly available Metahuman meshes and self-collected meshes. Compared with existing methods, our generator has the shortest generation time of 14.78 ms and the smallest vertex relative mean square error of 1.57 × 10−3, while our recognizer has the highest accuracy of 92.92%. The ablation experiment verifies that the local constraints can improve the recognition accuracy by 3.02%. Compared with other 3D mask selection methods, the recognition accuracy is improved by 1.03%. In addition, our method shows robust results for meshes of different levels of detail, and the rig has more dimensions of semantic space. The source code will be made available if this paper is accepted for publication.
EFSAttack: Edge Noise-Constrained Black-Box Attack Using Artificial Fish Swarm Algorithm
Authors: Gao Jiaqi , Zheng Kangfeng , Wang Xiujuan , Wu Chunhua , Wu Bin
Published: June 2024

Black-box attacks generate adversarial examples by querying the target model and updating the noise according to the feedback. However, the current black-box attack methods require excessive queries to generate adversarial examples, increasing the risk of detection by target defense systems. Furthermore, the current black-box attack methods primarily focus on controlling the magnitude of perturbations while neglecting the impact of perturbation placement on the stealthiness of adversarial examples. To this end, we propose a novel edge noise-constrained black-box attack method using the artificial fish swarm algorithm (EFSAttack). EFSAttack introduces the concept of edge noise constraint to indicate the low-frequency region of the image where perturbations are added and employs edge noise constraint to improve the population initialization and population evolution process. The experiments on CIFAR-10 and MNIST show notable improvements in the success rates, query efficiency, and adversarial example invisibility.
Technical Feasibility Study of Orange Wood Residues (Citrus sinensis) for Bioenergy Generation
Authors: Dias Luciano C. , Guimarães Damaris , Dias Júnior Ananias F. , Oliveira Michel P.
Published: June 2024

The production of orange (Citrus sinensis) generates many residues, and the few that are used are usually by-products of the fruit juice processing industry. Among the residues, wood is potentially advantageous for use in bioenergy, but with few records in the literature. In this sense, this study sought to evaluate the feasibility of using orange wood for energy purposes by performing chemical characterization, immediate analysis, FTIR, calorific value, thermogravimetry and bulk and energetic densities for three compositions: 100% trunk (100T), 90% trunk + 10% bark (90T10B) and 100% bark (100B). 100T showed a higher fixed carbon content (16.76%) and equality with 90T10B in lignin, holocellulose, useful calorific value and volatile materials. 100B presented higher extractives and ash contents of 19.67% and 10.35%, respectively. The FTIR spectra and thermogravimetric curves were similar in 100T and 90T10B. 100B showed more stages of degradation and a higher incidence of peaks in the range 780–612 cm−1. The bulk density was equal in 100T and 90T10B, but the energy density was higher in 100T (6.16 Gj.m−3). 100T and 90T10B are good options for bioenergy and the chemical composition and thermal degradation of 100B point to new investigations in this composition.
A Review of Voltage Control Studies on Low Voltage Distribution Networks Containing High Penetration Distributed Photovoltaics
Authors: Gao Xiaozhi , Zhang Jiaqi , Sun Huiqin , Liang Yongchun , Wei Leiyuan , Yan Caihong , Xie Yicong
Published: June 2024

Distributed photovoltaic (PV) in the distribution network accounted for an increasing proportion of the distribution network, and the power quality of the distribution network of the power quality problem is more and more significant. In this paper, the voltage regulation methods for low-voltage distribution networks containing high-penetration PV are investigated. First, the working principles of the four voltage control methods are introduced: energy storage system configuration, regulating the reactive power output of PV inverters, restricting the active power output of PV, adjusting the switching positions of on-load regulator trap changer and distribution network reconfiguration, and then, in combination with the recent related research, the optimization of each method is compared horizontally with its respective concerns and characteristics. The optimization of each method is compared horizontally with the recent studies to find out the focus and characteristics of each method, and the shortcomings of each method are explored. Coordinated voltage control through multiple flexibility resources has become the mainstream voltage regulation scheme, and distribution network voltage regulation is considered from the perspective of flexibility resources. The three types of flexibility resources, namely, source, network, and storage, have been widely used in distribution network voltage regulation. Although load-side resources have become one of the main regulation resources of the new type of power system, the current study introduces less about the participation of load-side flexibility resources in voltage regulation of LV distribution networks and advancing the application of load-side resources in voltage regulation of LV distribution networks is the focus of future research. Then, the important role of load-side flexibility resources in voltage regulation is described in three parts, namely, the important role of load-side resources, the development trend, and the suggestions for promoting the coordination of source-network-load-storage flexibility resources, aiming to promote the application of load-side resources in voltage regulation in LV distribution networks, and the suggestions and programs are proposed for the technological challenges faced by voltage regulation. In the context of today’s new power system emphasizing the interaction of source, network, load, and storage, new technologies and methods for solving voltage problems in LV distribution networks are prospected, with a view to providing certain reference value for the actual operation and optimization of distribution network systems.
Integrated Steady-State System Package for Nuclear Thermal Propulsion Analysis Using Multi-Dimensional Thermal Hydraulics and Dimensionless Turbopump Treatment
Authors: Myers Rory , DeHart Mark , Kotlyar Dan
Published: June 2024

Nuclear thermal propulsion is an evolving technology that can be utilized for long-distance space travel. This technology yields the advantage of a high thrust and specific impulse, but requires an examination of the potential design adjustments necessary to enhance its feasibility. The development of nuclear thermal propulsion requires a comprehensive understanding of the system-level behavior during transient and steady-state operation. This paper extends our previous research by including the proper handling of turbomachinery with multi-channel thermal hydraulic simulations only for steady-state solutions. The system-level approach presented here enables the treatment of the turbopump components through non-dimensional analysis that eliminates the assumption of constant efficiencies. All the other components within the system (e.g., reflector and core) can be discretized to multiple channels and layers, in which the full thermal hydraulic solution is established. The approach chosen here enables the realistic modeling of the propellant flow within the expander cycle by capturing the pressure losses, mass flow rate splits, and enthalpy gain for various operational conditions. The verification of the package is completed through point comparisons of previous investigations into similar system designs. Furthermore, sensitivity studies are used to benchmark the capabilities of the package and investigate solution variations due to the perturbation of operational conditions and regimes. The sensitivity studies performed here are important to capture variation in flow characteristics (e.g., temperature, pressure, mass flow rates) for different design objectives such as the thrust and specific impulse. This work demonstrates that system-level simulations lacking multi-channel capability and proper turbomachinery treatment may yield higher uncertainties in understanding the engine’s response and characteristics to changing various requirements. This is extremely important when screening the design space of such propulsion systems and when transient simulations are required.
Economic Analysis of Profitability of Using Energy Storage with Photovoltaic Installation in Conditions of Northeast Poland
Authors: Neugebauer Maciej , d’Obyrn Jakub , Sołowiej Piotr
Published: June 2024

This work presents an economic analysis of the use of electricity storage in PV installations, based on previously adopted assumptions, i.e., the type and location of the tested facility and comparative variants, divided into the share of the storage in the installation, and the billing system. The work takes into account the share of the energy shield and assumes a consumption limit of 2000 kWh. The cost of building the installation is based on July 2023 prices. The work assumes potential directions of changes in electricity prices, based on which the degree of investment profitability for a given price situation is determined. Depending on the adopted change in the direction of electricity prices, with a low price increase rate, for installations in the new billing system (net-billing), the optimal choice is an installation without energy storage with a power exceeding the actual energy demand. Assuming a high increase in electricity prices, the optimal choice is an installation with energy storage with an installation capacity exceeding the actual demand. For installations billed using the net-metering system, the optimal choice is an installation without storage with an appropriately selected installation power. This article shows how much you can gain after installing a PV installation and not only what costs must be incurred to complete the investment. Profit analysis will enable a more complete assessment of the profitability of investing in PV panels (with or without energy storage). It describes the verification of the profitability of a PV installation for a standard user depending on various types of settlements with the electricity supplier and the lack or installation of an energy-storage facility.
Cross-Temporal Hierarchical Forecast Reconciliation of Natural Gas Demand
Authors: Quinn Colin O. , Corliss George F. , Povinelli Richard J.
Published: June 2024

Local natural gas distribution companies (LDCs) require accurate demand forecasts across various time periods, geographic regions, and customer class hierarchies. Achieving coherent forecasts across these hierarchies is challenging but crucial for optimal decision making, resource allocation, and operational efficiency. This work introduces a method that structures the gas distribution system into cross-temporal hierarchies to produce accurate and coherent forecasts. We apply our method to a case study involving three operational regions, forecasting at different geographical levels and analyzing both hourly and daily frequencies. Trained on five years of data and tested on one year, our model achieves a 10% reduction in hourly mean absolute scaled error and a 3% reduction in daily mean absolute scaled error.
Geotechnical Study for Assessing Slope Stability at the Proposed Weito Dam Site in Ethiopia: Implications for Environmental Sustainability and Resilience
Authors: Demisie Tadesse , Getahun Ephrem , Jothimani Muralitharan , Qi Shengwen
Published: June 2024

There is a proposed dam at Weito in Ethiopia’s Southern Nations Nationalities and People Regional State. This embankment-type dam primarily serves irrigation purposes. Weito’s proposed dam’s slope stability is the primary focus of this investigation. The objective is to assess the geological and geotechnical conditions influencing slope stability using the slope mass rating (SMR) classification system. This study examined various slope stability parameters. Uniaxial compressive strength, rock quality designation, joint condition, discontinuity spacing, joint orientation, and groundwater conditions were measured. An analysis of field data, including geological structures and lithology, was used to generate a structural discontinuity map. The slope mass rating was calculated to assess rock mass stability. The study area was examined for faults, joints, fractures, and shear zones during fieldwork. Schmidt hammer tests indicated a range of 10.5–50 MPa uniaxial compressive strength. Rock quality designation values were also within 72.5% to 95%. Additionally, the joint spacing of rocks varied from 3.95 cm to 47.5 cm. Rock mass ratings ranged from 39% to 62%. The study contributes to the understanding of the geological conditions at the Weito dam site and ensures the dam’s safe design and construction.
Chloroplast Spacer DNA Analysis Revealed Insights into Phylogeographical Structure of Phoebe chekiangensis
Authors: Wu Xiankun , Chen Yan , Nan Chenhui , Gao Shucheng , Chen Xiangzhen , Yi Xiangui
Published: June 2024

Research studies on the conservation genetics of endangered plants play a crucial role in establishing management plans for biodiversity conservation. Phoebe chekiangensis is a precious and scarce tree species resource in the East China region. To comprehend the origin, evolutionary history, geographical, and historical factors that has contributed to the current distribution pattern of Phoebe chekiangensis in the East China region, we conducted a phylogeographic analysis that utilized intergenic spacers of chloroplast DNA (cpDNA). We amplified and sequenced three spacer regions of cpDNA (psbC-trnS, trnL-Intro, and Ycf3) intergenic spacer regions of 306 individuals from 11 populations, encompassing the majority of its geographical range in China. Our analysis revealed a total of 11 haplotypes. The research findings show that the spacer regions of the cpDNA genetic diversity of Phoebe chekiangensis was Hd = 0.423, and the nucleotide diversity was Pi × 10−3 = 0.400. At the species level, the population differentiation index Fst = 0.25610 (p < 0.05), and the gene flow Nm = 0.73. The genetic variation between populations was 29.14%, while within populations, it was 70.86%, with the inter-population genetic variation much lower than the within-population variation. The divergence time between the genera Phoebe and Machilus was estimated to be approximately 37.87 mya (PP = 1; 95%HPD: 25.63–44.54 mya), and the crown group time of the genus Phoebe was estimated to be 21.30 mya (PP = 1; 95%HPD: 9.76–34.94 mya). The common ancestor of the 11 Phoebe chekiangensis haplotypes was 7.85 mya, while the H7, H8, and H10 haplotypes of Phoebe chekiangensis (northern region) differentiated relatively late, with a divergence time of 1.90 mya. Neutrality tests (NTs) and mismatch distribution analysis (MDA) suggest that the time frame for Phoebe chekiangensis to expand southwestward along Wuyishan was relatively short and its adaptability to the environment was low, thereby limiting the formation of new haplotypes. These results suggest that Phoebe chekiangensis exhibited greater adaptation to the northern subtropics than to the central subtropics, offering valuable insights for the conservation and utilization of germplasm resources.
Vegetation Dynamics since the Last Glacial Maximum in Central Yunnan, Southwest China
Authors: Wang Min , Shen Caiming , Sun Qifa , Meng Hongwei , Huang Linpei , Zhang Hucai , Sun Huiling
Published: June 2024

Vegetation dynamics data since the Last Glacial Maximum (LGM) are essential for our understanding of ecosystem shifts and vegetation responses to climate change. Here, we present a pollen record covering the last 25,000 years from Lake Fuxian in central Yunnan, southwest China. Our study shows seven stages of vegetation dynamics since the LGM: The early LGM (stage 7 of 25,000–21,200 cal. a BP) witnessed less dense regional vegetation dominated by pine forests, evergreen broadleaved forests (EBFs), deciduous broadleaved forests (DBFs), montane hemlock forests, and fir/spruce forests. The late LGM (stage 6 of 21,200–17,500 cal. a BP) saw an expansion of grasslands, wetlands, and montane fir/spruce forests as well as a shrinkage of EBFs and DBFs. During the last deglaciation (stage 5 of 17,500–13,300 cal. a BP), dense regional vegetation was dominated by EBFs as well as deciduous oak and alder forests. The densest regional vegetation occurred in stage 4 of 13,300–11,200 cal. a BP, roughly equal to the Younger Dryas Chron, when pine forests, DBFs, EBFs, grasslands, and wetlands grew in the Lake Fuxian catchment. During the early to mid-Holocene (stage 3 of 11,200–5000 cal. a BP), dense regional vegetation was dominated by sweetgum forests, in addition to some pine forests and EBFs. After 5000 cal. a BP, the regional vegetation density became lower and lower, and forests became thinner and thinner. Pine forests expanded to their maximum of the entire sequence in stage 2 of 5000–2500 cal. a BP. A big deforestation event occurred in stage 1 (the last 2500 years), when grasslands, wetlands, and cultivated vegetation dominated regional vegetation in the catchment of Lake Fuxian. The regional vegetation since the LGM in the catchment of Lake Fuxian also experienced six major transitions, five centennial shift events, and one big large-scale and long-term deforestation event. These resulted from the responses of regional vegetation to climate changes during the LGM, last deglaciation, and early–mid-Holocene, as well as human influence in the late Holocene. The vegetation density since the LGM has changed with the 25° N summer insolation.
Improving the Site Index and Stand Basal Area Model of Picea asperata Mast. by Considering Climate Effects
Authors: Wang Yuan , Feng Zhongke , Wang Liang , Wang Shan , Liu Kexin
Published: June 2024

The stand basal area, closely related to age, site quality, and stand density, is an important factor for predicting forest growth and yield. The accurate estimation of site quality is especially a key component in the stand basal area model. We utilized sample plots with Picea asperata Mast. as the dominant species in the multi-period National Forest Inventory (NFI) dataset to establish a site index (SI) model including climate effects through the difference form of theoretical growth equations and mixed-effects models. We combined the SI calculated from the SI model, stand age, and stand density index to construct a basal area growth model for Picea asperata Mast. stands. The results show that the Korf model is the best SI base model for Picea asperata Mast. The mean temperatures in summer and winter precipitation were used as the fixed parameters to construct a nonlinear model. Ultimately, elevation, origin, and region, as random effects, were incorporated into the mixed-effects model. The coefficients (R2) of determination of the base model, the nonlinear model including climate, and the nonlinear mixed-effects model are 0.869, 0.899, and 0.921, with root-mean-square errors (RMSEs) of 1.320, 1.315, and 1.301, respectively. Among the basal area models, the Richards model has higher precision. And the basal area model including an SI incorporating climatic factors had a higher determination coefficient (R2) of 0.918 than that of the model including an SI without considering climatic effects. The mixed-effects model incorporating climatic and topographic factors shows a better fitting performance of SI, resulting in a higher precision of the basal area model. This indicates that in the development of forest growth models, both biophysical and climatic factors should be comprehensively considered.
Bending Performance of Water Saturated White Birch and Ash Wood at 20–100 °C
Authors: Li Xiaoling , Zhao Youke
Published: June 2024

Bent wood has the advantages of visually appealing and ergonomic shapes and the disadvantage of processing failure. Understanding how water and temperature influence wood bending is critical to avoid processing failure. Compared with softwood, saturated hardwood has been seldom reported in terms of bending performance at various temperature levels. In this paper, white birch and ash wood were studied in bending using a universal testing machine and a program-controlled water bath. White birch wood exhibited lower proportional limit stress, smaller modulus of elasticity (MOE), and lower failure stress, but higher proportional strain and failure strain than ash wood. At 20 °C, bending of air-dried wood on the tangential direction exhibited much smaller mechanical variation than that on the radial direction. The proportional limit stress, MOE, and failure stress of water-saturated wood were much smaller than those of air-dried wood, while failure strain was much higher. Evidenced by the almost constant proportional limit strain, plastic bending deformation of water-saturated wood happened to a great extent. As the temperature elevated at 20–100 °C, MOE, proportional limit stress, and failure stress of water-saturated wood decreased while proportional limit strain, failure strain, and wood toughness increased. Variation in proportional limit strain resulting from temperature change was ignorable, evidencing that elevated temperature enhanced wood plastic deformation. Furthermore, white birch wood was more susceptible to temperature over 40 °C than ash wood in terms of toughness. Under water-saturated condition, both species exhibited excellent bending performance at relatively high temperature.
Does Soil Acidification Matter? Nutrient Sustainability of Timber Harvesting in Forests on Selected Soils Developed in Sediments of the Early vs. Late Pleistocene
Authors: Zimmermann Stephan , Kurz Daniel , Thrippleton Timothy , Mey Reinhard , Perry Niál Thomas , Posch Maximilian , Schweier Janine
Published: June 2024

With this study, our aim was to estimate the nutrient fluxes relevant for assessing nutrient sustainability as accurately as possible and to calculate nutrient balances for alternative forest management scenarios. Furthermore, we tested whether mapping units from existing geologic maps can serve as a basis for forest practitioners to estimate nutrient sustainability or whether more detailed data are needed. Positive fluxes include deposition and weathering, while negative fluxes include losses due to leaching and nutrient removal through timber harvesting in the balance. Weathering and leachate losses were modeled with a geochemical model. The SwissStandSim model was used to simulate the biomass growth under different harvesting and silvicultural strategies, allowing for sustainability to be assessed for each nutrient at a given intensity of use. This assessment was made per rotation period based on two criteria: (i) nutrient supply and (ii) total stocking volume. As a result, it can be noted that the accurate estimation of individual fluxes is essential for assessing the sustainability of forestry practices and that it needs detailed site-specific data. Various influencing factors turned out to be important, particularly the assumed depth of the root zone.
Thinning Effects on Aboveground Biomass Increments in Both the Overstory and Understory of Masson Pine Forests
Authors: Liu Feng , Liu Xiaolin , Zeng Mengyuan , Li Jianjun , Tan Chang
Published: June 2024

Masson pine (Pinus massoniana Lamb.) is a tree species that is widely distributed throughout southern China and holds significant economic and ecological value. The main objective of our study was to assess the effects of thinning on aboveground biomass increments and tree diversity in both the overstory and understory. Additionally, the underlying factors and mechanisms responsible for driving changes in biomass increment were analyzed. Four different thinning treatments (control, light thinning, moderate thinning, and heavy thinning) were implemented in 214 plots (~1800 tree ha−1) in three Masson pine forests in Hunan Province, China. A robustly designed experiment was used with over six years of repeated measurements. The differences in biomass increment and tree diversity among the different treatments were compared using repeated measures ANOVAs. The Mantel test was used to determine environmental metrics correlated with biomass increments across tree strata. Structural equation modeling was utilized to explore the multivariate relationships among site environment, tree diversity, and post-treatment biomass increment. The results indicated that thinning overall increased biomass increment, the Shannon index, and the Gini index, while decreasing the Dominance index over time. Moderate thinning (25%–35% of trees removed) was found to promote overstory biomass increment to 9.72 Mg·ha−1·a−1 and understory biomass increment to 1.43 Mg·ha−1·a−1 six years post-thinning, which is significantly higher than that of other treatments. Environmental metrics such as light intensity, soil organic matter, and other soil physiochemical properties were positively correlated with biomass increments, and their effects on the overstory and understory differed. Structural equation modeling revealed that thinning treatments, environmental metrics, tree diversity, and their interactions could be the main drivers for biomass increments across tree strata. Specifically, thinning treatments, light intensity, and tree size diversity (Gini index) had significant effects on overstory biomass increment, while understory species richness (Shannon index) and soil organic matter affected understory biomass increment. In conclusion, moderate thinning is an effective silvicultural treatment for stimulating biomass increments of both the overstory and understory in Masson pine forests in southern China if a middle period (e.g., six years) is considered. Some factors, such as species richness, tree size diversity, and environmental metrics (e.g., light and soil), are suggested for consideration to improve the efficiency of thinning.
Effects of Slope Position on Morphological, Anatomical, and Chemical Traits of Cunninghamia lanceolata (Lamb.) Hook. Fine Roots
Authors: Li Linxin , Liang Jing , Tian Yunlong , Li Ming , Ma Xiangqing , Liu Aiqin , Wu Pengfei
Published: June 2024

Fine root traits and their relationships reflect the ecological trade-off strategies of plants in resource investment and are important for understanding the life strategies and growth of plants in response to changes in the environment. We used 16-year-old Chinese fir (Cunninghamia lanceolata Lamb. Hook.) plantations with different slope positions as the research object to explore the morphological, anatomical, and chemical properties of fine roots and their relationships. With increasing root order levels, the morphological, anatomical, and chemical traits of the fine roots of Chinese fir at different slope positions showed similar change trends; however, at the same order level, the differences were large. Under the upper slope site conditions, the average diameter of the second- and third-order roots and the thickness of the third-order root cortex were the highest. However, specific surface area, vascular bundle diameter, and the ratio of third-order roots were higher under the middle-slope site conditions. Under the lower slope site conditions, the specific surface area and specific root length of first-order roots and the root ratio of second-order roots were the highest. The biomasses of the first- and third-order roots on the middle and lower slopes were higher than those on the upper slope. The contents of N and P in fine roots of grades 1–3 Chinese fir showed the order of lower slope > middle slope > upper slope; however, the changes in C/N and C/P ratios showed the opposite trend, indicating differences in the morphological, anatomical, and chemical properties as well as resource acquisition strategies of fine roots of grades 1–3 Chinese fir under different slope positions. There were negative correlations between fine root diameter, N and P contents, and specific root length, indicating an acquisition and conservative resource trade-off relationships between fine root morphological, anatomical, and chemical traits. There were also differences in the relationships between the morphological, anatomical, and chemical traits of Chinese fir fine roots at different slope positions, indicating that the relationships between these traits were affected by slope position change. Chinese fir varieties with root-foraging characteristics ranging from resource conservation to resource acquisition can be selected for planting to improve the productivity of C. lanceolata plantations.
Functional Properties of Microorganisms Isolated from Formulated Sourdough, Coconut Water Kefir, and Kefir
Authors: Limbad Mansi Jayantikumar , Maddox Noemi Gutierrez , Hamid Nazimah , Kantono Kevin
Published: June 2024

Recently, there has been a renewed interest in the fermentation of kefir grains using fruit-based substrates, such as coconut water. Kefir grains contain a mixture of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast, which have important probiotic capacity and play a vital role in improving the nutritional and functional properties of the new product being developed. The principal objective of this study was to determine the functional properties of the microorganisms identified and characterized from kefir, CWK, and sourdough fermented with coconut water kefir (CWKS), such as Limosilactobacillus fermentum, Lactiplantibacillus plantarum, L. fusant, L. reuteri, L. kunkeei, Acetobacter aceti, A. lovaniensis, A. pasteurianus, Candida kefyr, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, C. guilliermondii, and C. colliculosa. In addition to identifying functional properties, such as glutamic acid production, phytase production, phytic acid degradation, and exopolysaccharide production, from this study, it was found that significantly high quantities of glutamic acid, exopolysaccharide, and phytase enzyme were detected in two LAB isolates, Limosilactobacillus fermentum and Lactiplantibacillus plantarum.
Effects of Different Stocking Densities on the Growth, Antioxidant Status, and Intestinal Bacterial Communities of Carp in the Rice–Fish Co-Culture System
Authors: Diao Weixu , Jia Rui , Hou Yiran , Gong Jianyou , Zhang Liqiang , Li Bing , Zhu Jian
Published: June 2024

Common carp (Cyprinus carpio) is a freshwater fish commonly farmed in rice fields, yet there were few studies on the intestinal functions and microbial community structure of common carp in the rice–carp co-culture system. Therefore, this study aimed to explore the effects of different stocking densities on the growth, antioxidant status, and intestinal bacterial composition of common carp in this system. This study was divided into three different stocking densities, including low density (LD, 10 fish, 52.9 g/m2), medium density (MD, 20 fish, 105.8 g/m2), and high density (HD, 30 fish, 158.7 g/m2), with a culturing period of 60 days. The results indicated that HD treatment inhibited the growth of common carp, as evidenced by the reduced final weight, WG, and SGR. In serum, the TG content in the HD group and the Cor content in the MD group were significantly increased. Meanwhile, HD treatment induced oxidative stress, manifesting specifically as increased SOD and CAT activities in the intestine or serum while reducing Gpx, GSH, and T-AOC in the serum. The 16S rDNA analysis indicated that the Simpson and Shannon indices of intestinal microbiota in the HD group were significantly higher than those in the LD group. At the phylum level, Proteobacteria, Cyanobacteria, and Firmicutes were dominant microbial communities in two groups. In addition, there was a significant difference between the two groups in the abundances of Actinobacterota and Bifidobacterium. Based on growth performances, biochemical indicators, and microbial diversity in rice–carp co-culture, low density (52.9 g/m2) may be more suitable in the rice–carp co-culture systems. In summary, this study contributes to a better understanding of common carp response to different stocking densities in the rice–carp co-culture system.
Risk Assessment of Microbiological and Chemical Hazards in Foods
Authors: Esposito Francesco , Cirillo Teresa
Published: June 2024

Food safety constitutes a critical regulatory and quality standard that must be fulfilled by food manufacturers throughout all phases of food production [...]