bluuebunny/crossref_metadata_2025 huggingface dataset:
Total Synthesis and Biological Investigation of Mindapyrroles A and B
Authors: Allen Ryan A. , Wuest William M.
Published: July 2023

In the search for antibacterial compounds that can overcome drug resistant species, molecules that enact novel or polypharmacological mechanisms of action (MoA) are needed. As a preliminary foray into molecules of this background, the total synthesis of mindapyrroles A and B was undertaken leveraging a biomimetic approach. Following their synthesis, they and their monomer pyoluteorin were tested against a range of pathogenic bacteria in minimum inhibitory concentration assays to confirm their activity. These molecules were then tested for their ability to disrupt membrane potential in S. aureus. Our findings indicate that pyoluteorin acts as a protonophore but the mindapyrroles do not. This work encapsulates the first total synthesis of mindapyrrole B and the second total synthesis of mindapyrrole A in 11 % and 30 % overall yields, respectively. It also provides insights into the antibacterial properties and different MoAs between the monomer and dimers.
Deep Eutectic Solvents as Suitable Solvents for Lipase‐Catalyzed Transesterification Reactions
Authors: Noro Jennifer , Cabo Joana , Freitas David S. , Roque Catarina S. , de Castro Mariana , Cavaco‐Paulo Artur , Silva Carla
Published: July 2023

In this work, three deep eutectic mixtures (DES 1: choline chloride/urea; DES 2: choline chloride/glycerol; and DES 3: tetrabutylammonium bromide/imidazole) were investigated as mediums for the synthesis of glucose laurate and glucose acetate. Aiming to achieve a greener and more sustainable approach, the synthesis reactions were catalyzed by lipases from Aspergillus oryzae (LAO), Candida rugosa (LCR), and porcine pancreas (LPP). The hydrolytic activity of lipases against p‐nitrophenyl hexanoate revealed no evidence of enzyme inactivation when DES were used as medium. Regarding the transesterification reactions, combining LAO or LCR with DES 3 resulted in the efficient production of glucose laurate (from glucose and vinyl laurate) (conversion >60 %). The best result for LPP was observed in DES 2, with 98 % of product production after 24 hours of reaction. When replacing vinyl laurate by a smaller hydrophilic substrate, vinyl acetate, a distinct behavior was observed. LCR and LPP performed better in DES 1, yielding more than 80 % of glucose acetate after 48 hours of reaction. The catalytic activity of LAO was less pronounced, reaching only nearly 40 % of product in DES 3. The results highlight the potential of combining biocatalysis with greener and environmentally‐safer solvents, for the synthesis of differentiated chain‐length sugar fatty acid esters (SFAE).
The genetic basis of conspicuous coloration in the Guadeloupean anole: Evolution by sexual and ecological selection
Authors: Crawford Nicholas G. , McGreevy Thomas J. , Mullen Sean P. , Schneider Christopher J.
Published: July 2023

Understanding how natural selection acts on the genome and contributes to the process of speciation is a primary aim of the study of evolution. Here we used natural variation in two subspecies of the Guadeloupean anole (Anolis marmoratus ssp.), from the island of Guadeloupe in the Lesser Antilles, to explore the genomic basis of adaptation and speciation in Anolis lizards. These subspecies inhabit distinct ecological environments and display marked differences in adult male color and pattern. We sequenced the complete genomes of 20 anoles, 10 from each subspecies, at 1.4× coverage. We used genome‐wide scans of population differentiation, allele frequency spectrum, and linkage disequilibrium to characterize the genomic architecture within and between the subspecies. While most of the genome was undifferentiated, we observed five large divergent regions. Within these regions we identified blocks, 5 kb pairs in length, enriched for fixed single nucleotide polymorphisms. These blocks encompass 97 genes, two of which are candidate pigmentation genes. One is melanophilin (mlph), which helps transport melanosomes within melanocytes. The other is a cluster of differentiation 36 (cd36), which regulates carotenoid pigment sequestration. We used high‐pressure liquid chromatography to confirm that carotenoid pigments are significantly more abundant in the conspicuous orange‐pigmented skin of male A. m. marmoratus suggesting that cd36 may be regulating pigment deposition in this tissue. We identified for the first time a carotenoid gene that is a potential target of divergent sexual selection and may be contributing to the early stages of speciation in Anolis lizards.
cGAS‐STING signaling in cell death: Mechanisms of action and implications in pathologies
Authors: Xu Yifan , Chen Chen , Liao Zhiyong , Xu Pinglong
Published: July 2023

Cyclic GMP‐AMP synthase (cGAS) monitors dsDNA in the cytosol in response to pathogenic invasion or tissue injury, initiating cGAS‐STING signaling cascades that regulate various cellular physiologies, including IFN /cytokine production, autophagy, protein synthesis, metabolism, senescence, and distinct types of cell death. cGAS‐STING signaling is crucial for host defense and tissue homeostasis; however, its dysfunction frequently leads to infectious, autoimmune, inflammatory, degenerative, and cancerous diseases. Our knowledge regarding the relationships between cGAS‐STING signaling and cell death is rapidly evolving, highlighting their essential roles in pathogenesis and disease progression. Nevertheless, the direct control of cell death by cGAS‐STING signaling, rather than IFN/NF‐κB‐mediated transcriptional regulation, remains relatively unexplored. This review examines the mechanistic interplays between cGAS‐STING cascades and apoptosis, necroptosis, pyroptosis, ferroptosis, and autophagic/lysosomal cell death. We will also discuss their pathological implications in human diseases, particularly in autoimmunity, cancer, and organ injury scenarios. We hope that this summary will stimulate discussion for further exploration of the complex life‐or‐death responses to cellular damage mediated by cGAS‐STING signaling.
Economic analysis of enzyme recycling during enzymatic hydrolysis of sugar beets for soluble sugars production
Authors: Chen Yike , Zicari Steve , Zhang Ruihong
Published: July 2023

Enzymatic hydrolysis of sugar beets is an efficient alternative to conventional hot water extraction where overall soluble extraction is valued. The economic analysis of a sugar beet soluble sugar production plant was designed and developed using SuperPro Designer software. The commercial scale operation was sized to process 100 million metric ton (MT)/day of sugar beets. The base case process includes transportation, grinding, thermal pretreatment, enzymatic hydrolysis, solid–liquid separation, and evaporation. The final product from the model was assumed to be a sugar syrup stream at 65% total solids content. Since the breakeven selling price was sensitive to the cost of enzymes, alternative scenario A added an ultrafiltration unit operation to separate the enzymes and reuse them in subsequent batches of hydrolysis. Steam was another major contributor to the operating cost. Alternative scenario B included a natural gas boiler to generate steam from biogas produced from a co‐located dairy manure digester. The breakeven selling price of the sugar syrup from the base case, alternative scenario A, and alternative scenario B were $965, $911, and $955 per metric ton, respectively. Sensitivity analysis showed that the breakeven selling price is sensitive to the raw material cost, especially for the pectic enzymes.
Scenario planning: Reflecting on cases of actionable knowledge
Authors: Oliver John J.
Published: July 2023

Scenario planning has a long history of academic inquiry and practice in numerous fields and industries; however, its future as a tool to manage strategic uncertainty may well have reached an impasse. While the academic community perpetuates the view that the field is characterized by methodological chaos, the practitioner community is concerned only with how scenario planning can help solve an organizational problem. This paper argues that the academic community would benefit from adopting a philosophical orientation that is “pragmatic” where theoretical and methodological sophistication should be traded‐off against the need to produce a practical outcome that addresses a specific organizational problem. This would enable more academics to generate new knowledge that was “useful” rather than “generalizable.” Adopting a Pragmatic Philosophy would also address three primary issues asserted in literature on the process, content, and implementation of scenario‐informed strategizing. This position paper provides a reflective account of how the narrative on scenario planning theory can be moved more effectively into scenario planning practice by illustrating the author's commitment to developing scenario‐based actionable knowledge, high levels of implementable validity, and instrumental impact with organizations. As such, it presents a reflection on interventions that demonstrate how scenario‐informed strategies were developed and implemented with successful organizational outcomes.
Advances in the application of functional nanomaterial and cold plasma for the fresh‐keeping active packaging of meat
Authors: Umair Muhammad , Sultana Tayyaba , Xun Song , Jabbar Saqib , Riaz Rajoka Muhammad Shahid , Albahi Amgad , Abid Muhammad , Ranjha Muhammad Modassar Ali Nawaz , El‐Seedi Hesham R. , Xie Fengwei , Khan Kashif ur Rehman , Liqing Zhao , Zhendan He
Published: July 2023

The most recent advancements in food science and technology include cold sterilization of food and fresh‐keeping packaging. Active packaging technology has received much interest due to the photocatalytic activity (PCA) of functional nanoparticles, including titanium dioxide (TiO2) and ferric oxide (Fe2O3). However, there are still significant concerns about the toxicity and safety of these functional nanoparticles. This review emphasizes the bacteriostatic and fresh‐keeping properties of functional nanoparticles as well as their packaging strategies using the ultraviolet photo‐catalysis effect. High‐voltage electric field cold plasma (HVEF‐CP) is the most innovative method of cold‐sterilizing food. HVEF‐CP sterilizes by producing photoelectrons, ions, and active free radicals on food media, which come into contact with the bacteria's surface and destroy their cells. Next, this review also assesses the photocatalytic activity and bacteriostasis kinetics of nanosized TiO2 and Fe2O3 in poultry, beef, and lamb. In addition, this review also emphasizes the importance of exploiting the complex interaction processes between TiO2 and Fe2O3, along with dietary components and their utilization in the fresh meat industry.
The association of pain with suicidal ideation and suicide attempts with depressive symptoms among adults aged ≥50 years from low‐ and middle‐income countries
Authors: Smith Lee , Shin Jae Il , Pizzol Damiano , López Sánchez Guillermo F. , Soysal Pinar , Veronese Nicola , Kostev Karel , Jacob Louis , Butler Laurie T. , Barnett Yvonne , Koyanagi Ai
Published: July 2023

Objectives

We aimed to examine the relationship of pain with suicidal ideation and suicide attempts with depressive symptoms among adults aged ≥50 years from six low‐ and middle‐income countries (LMICs) (China, Ghana, India, Mexico, Russia, and South Africa).

Methods

Cross‐sectional, community‐based, nationally representative data from the WHO Study on global AGEing and adult health were analyzed. Self‐reported information on past 12‐month suicidal ideation and suicide attempts among people with depressive symptoms was collected. Pain was assessed with the question “Overall in the last 30 days, how much of bodily aches or pain did you have?” With answer options: “none”, “mild”, “moderate”, “severe/extreme”. Multivariable logistic regression was done to assess associations.

Results

Data on 34,129 adults aged ≥50 years (mean [SD] age 62.4 [16.0] years; males 47.9%) were analyzed. Compared to no pain, mild, moderate, and severe/extreme pain were associated with 2.83 (95% CI = 1.51–5.28), 4.01 (95% CI = 2.38–6.76), and 12.26 (95% CI = 6.44–23.36) times higher odds for suicidal ideation. For suicide attempt, only severe/extreme pain was associated with significantly increased odds (OR = 4.68; 95% CI = 1.67–13.08).

Conclusions

In this large sample of older adults from multiple LMICs, pain was strongly associated with suicidal thoughts and suicide attempts with depressive symptoms. Future studies should assess whether addressing pain among older people in LMICs may lead to reduction in suicidal thoughts and behaviors.
Every subcubic multigraph is (1,27) $(1,{2}^{7})$‐packing edge‐colorable
Authors: Liu Xujun , Santana Michael , Short Taylor
Published: July 2023

For a nondecreasing sequence of positive integers, an ‐packing edge‐coloring of a graph is a decomposition of edges of into disjoint sets such that for each the distance between any two distinct edges is at least . The notion of ‐packing edge‐coloring was first generalized by Gastineau and Togni from its vertex counterpart. They showed that there are subcubic graphs that are not ‐packing (abbreviated to ‐packing) edge‐colorable and asked the question whether every subcubic graph is ‐packing edge‐colorable. Very recently, Hocquard, Lajou, and Lužar showed that every subcubic graph is ‐packing edge‐colorable and every 3‐edge‐colorable subcubic graph is ‐packing edge‐colorable. Furthermore, they also conjectured that every subcubic graph is ‐packing edge‐colorable.

In this paper, we confirm the conjecture of Hocquard, Lajou, and Lužar, and extend it to multigraphs.
On pathways and blind alleys—The importance of biomarkers in vitamin B6‐dependent epilepsies
Authors: Plecko Barbara
Published: July 2023

Over the past two decades, the field of vitamin B6‐dependent epilepsies has evolved by the recognition of a growing number of gene defects (ALDH7A1, PNPO, ALPL, ALDH4A1, PLPBP as well as defects of the glycosylphosphatidylinositol anchor proteins) that all lead to reduced availability of pyridoxal 5′‐phosphate, an important cofactor in neurotransmitter and amino acid metabolism. In addition, positive pyridoxine response has been observed in other monogenic defects such as MOCS2 deficiency or KCNQ2 and there may be more defects to be discovered. Most entities lead to neonatal onset pharmaco‐resistant myoclonic seizures or even status epilepticus and pose an emergency to the treating physician. Research has unraveled specific biomarkers for several of these entities (PNPO deficiency, ALDH7A1 deficiency, ALDH4A1 deficiency, ALPL deficiency causing congenital hypophosphatasia and glycosylphosphatidylinositol anchoring defects with hyperphosphatasia), that can be detected in plasma or urine, while there is no biomarker to test for PLPHP deficiency. Secondary elevation of glycine or lactate was recognized as diagnostic pitfall. An algorithm for a standardized trial with vitamin B6 should be in place in every newborn unit in order not to miss these well‐treatable inborn errors of metabolism. The Komrower lecture of 2022 provided me with the opportunity to tell the story about the conundrums of research into vitamin B6‐dependent epilepsies that kept some surprises and many novel insights into pathomechanisms of vitamin metabolism. Every single step had benefits for the patients and families that we care for and advocates for a close collaboration of clinician scientists with basic research.
The heat stress during anthesis and the grain‐filling period of spring maize in Northeast China is projected to increase toward the mid‐21st century
Authors: Qiao Suliang , Liu Zhijuan , Zhang Zhentao , Su Zheng'e , Yang Xiaoguang
Published: July 2023

BACKGROUND

Against the background of global warming, heat stress has become more frequent, which adversely affects the growth and development of spring maize plants in Northeast China. To adapt the regional maize production to climate change, it is imperative to understand the spatio‐temporal characteristics of heat stress. In the present study, we analyzed three of the indices for heat stress, including the number of heat stress days, heating degree days (HDD, the total heat degree‐days during critical stages), and the percentage of stations with heat stress.

RESULTS

From 1981 to 2019, the number of heat stress days varied greatly among the study years, ranging from 0 to 14 and 27 days, respectively. The average HDD was 7.8 and 5.0 °C day from 1981 to 2000, respectively, and the main hot‐spots of heat stress occurred in the southwest regions. Moreover, compared with 1981–2000, the region of HDD during anthesis higher than 10 °C day in 2041–2060 under the SSP1‐2.6 and SSP5‐8.5 climate scenarios increased by 9.1–50.1% and 0.1–28.6%. The average HDD during the critical stages from 2041 to 2060 increased under the SSP5‐8.5 climate scenario, being 1.5 times higher than that during 1981‐2000. HDD during maize anthesis and the grain‐filling period showed an overall increasing trend with years. About 19% and 58% of the study locations showed heat stress during the past 39 years, respectively.

CONCLUSION

Heat stress during anthesis and the grain‐filling period for spring maize in Northeast China is projected to increase toward the mid‐21st century. © 2023 Society of Chemical Industry.
An orthogonal matching pursuit optimization method for solving minimum‐monitor‐unit problems: Applications to proton IMPT, ARC and FLASH
Authors: Zhu Ya‐Nan , Zhang Xiaoqun , Lin Yuting , Lominska Chris , Gao Hao
Published: July 2023

Background

The intensities (i.e., number of protons in monitor unit [MU]) of deliverable proton spots need to be either zero or meet a minimum‐MU (MMU) threshold, which is a nonconvex problem. Since the dose rate is proportionally associated with the MMU threshold, higher‐dose‐rate proton radiation therapy (RT) (e.g., efficient intensity modulated proton therapy (IMPT) and ARC proton therapy, and high‐dose‐rate‐induced FLASH effect needs to solve the MMU problem with larger MMU threshold, which however makes the nonconvex problem more difficult to solve.

Purpose

This work will develop a more effective optimization method based on orthogonal matching pursuit (OMP) for solving the MMU problem with large MMU thresholds, compared to state‐of‐the‐art methods, such as alternating direction method of multipliers (ADMM), proximal gradient descent method (PGD), or stochastic coordinate descent method (SCD).

Methods

The new method consists of two essential components. First, the iterative convex relaxation (ICR) method is used to determine the active sets for dose‐volume planning constraints and decouple the MMU constraint from the rest. Second, a modified OMP optimization algorithm is used to handle the MMU constraint: the non‐zero spots are greedily selected via OMP to form the solution set to be optimized, and then a convex constrained subproblem is formed and can be conveniently solved to optimize the spot weights restricted to this solution set via OMP. During this iterative process, the new non‐zero spots localized via OMP will be adaptively added to or removed from the optimization objective.

Results

The new method via OMP is validated in comparison with ADMM, PGD and SCD for high‐dose‐rate IMPT, ARC, and FLASH problems of large MMU thresholds, and the results suggest that OMP substantially improved the plan quality from PGD, ADMM and SCD in terms of both target dose conformality (e.g., quantified by max target dose and conformity index) and normal tissue sparing (e.g., mean and max dose). For example, in the brain case, the max target dose for IMPT/ARC/FLASH was 368.0%/358.3%/283.4% respectively for PGD, 154.4%/179.8%/150.0% for ADMM, 134.5%/130.4%/123.0% for SCD, while it was <120% in all scenarios for OMP; compared to PGD/ADMM/SCD, OMP improved the conformity index from 0.42/0.52/0.33 to 0.65 for IMPT and 0.46/0.60/0.61 to 0.83 for ARC.

Conclusions

A new OMP‐based optimization algorithm is developed to solve the MMU problems with large MMU thresholds, and validated using examples of IMPT, ARC, and FLASH with substantially improved plan quality from ADMM, PGD, and SCD.
Band structures analysis of fluid–solid phononic crystals using wavelet‐based boundary element method and frequency‐independent fundamental solutions
Authors: Wei Qi , Xiang Jiawei , Zhu Weiping , Hu Hongjiu
Published: July 2023

A novel method of combination of wavelet‐based boundary element method (WBEM) with frequency‐independent fundamental solutions is proposed to determine the band structures of fluid–solid phononic crystals (PCs) with square and triangular lattices. Integral equations established are based on the frequency‐independent fundamental solutions, which can avoid nonlinear eigenvalue problems and reduce computing time. Domain integral terms arising from the use of frequency‐independent fundamental solutions are handled with the radial integration method (RIM) and dual reciprocity method (DRM), respectively. The results show the lower precision in high frequency domain of using RIM to handle domain integral terms than that of using DRM, which can be solved by increasing Gauss point. The B‐spline wavelet on the interval and wavelet coefficients are applied to approximate the physical boundary conditions. It is proved that coupling conditions between matrix and scatterers and Bloch theorem are also applicable to wavelet coefficients. Some small matrix entries generated by wavelet vanishing moment characteristics are truncated by the provided matrix compression technique, and the influence of compressed matrices on the results is studied. Furthermore, the final Eigen equations constructed are modified to avoid numerical instability. Some examples are provided to demonstrate the accuracy and efficiency of the proposed method.
Studies of optical, photophysical, and thermal properties of poly(paraphenylenevinylene) (PPV) polymers with symmetric alkoxy side‐chain lengths for potential application in electronic devices
Authors: Zengin Huseyin , Ozer Ahmet , Zengin Gulay
Published: July 2023

Optical, photophysical, and thermal properties of poly(paraphenylenevinylene) (PPV) derivatives of various symmetric alkoxyl substituents were studied with UV–vis and photoluminescence spectroscopy. Molar absorptivity coefficients of the symmetric monomers increased compared to that of hydroquinone and its derivatives. The symmetric polymers exhibited photoluminescence quantum yields in the range of 32%–39% and excited‐state lifetimes of 3.01–3.61 ns. The emission energy values for the calculated band gaps were in the range of 2.16–2.12 eV for the symmetric polymers. The photoluminescent characteristics of these compounds may show great potential in improving the emitting layers of electronic devices. The thermal behavior and heat changes of the symmetric dialkyl PPV polymers were monitored by TGA and DSC. Glass transition temperatures (Tg) for these polymers were observed as being in range of 67–108°C. The heat values of the symmetric dialkyl PPV polymers were found to be in range 220.41–599.98 J/g, and the entropy values of symmetric dialkyl PPV polymers were determined to be in range 0.567–1.754 J/ g °C.

Highlights

• Symmetric poly(phenylene vinylene) (PPV) derivatives were prepared.

• UV–vis spectroscopy was used for optical absorption studies.

• Photophysical properties were examined by photoluminescence spectroscopy.

• TGA was used for the thermal behavior of symmetric dialkyl PPV polymers.

• Heat changes of symmetric dialkyl PPV polymers were investigated by DSC.
Radiation effects on Kevlar fibers through high energy electron beam
Authors: Chen Wentao , Qi Wei , Du Jifu , Zhao Long
Published: July 2023

The Kevlar fibers were irradiated at up to 2500 kGy using a 10 MeV electron accelerator. The effects of radiation on the Kevlar fibers were evaluated in detail. The main structure, crystal structure, and thermal transition temperature of the fibers remained unchanged after electron beam radiation. The mechanical properties of the fibers decreased significantly when the absorbed dose reached 2000 kGy. In addition, viscosity tests revealed that electron beam radiation could damage the long polymer chains of the fibers. The FTIR results showed that the intensity of the CN bond decreased depending on the absorbed dose, indicating that CN bonds may be the degradation site of Kevlar fibers. This work provides a comprehensive radiation resistance evaluation for Kevlar fibers and thus offers some fundamental data for the application of Kevlar fibers in extreme environments.
CBP60‐DB: An AlphaFold‐predicted plant kingdom‐wide database of the CALMODULIN‐BINDING PROTEIN 60 protein family with a novel structural clustering algorithm
Authors: Amani Keaun , Shivnauth Vanessa , Castroverde Christian Danve M.
Published: July 2023

Molecular genetic analyses in the model species Arabidopsis thaliana have demonstrated the major roles of different CALMODULIN‐BINDING PROTEIN 60 (CBP60) proteins in growth, stress signaling, and immune responses. Prominently, CBP60g and SARD1 are paralogous CBP60 transcription factors that regulate numerous components of the immune system, such as cell surface and intracellular immune receptors, MAP kinases, WRKY transcription factors, and biosynthetic enzymes for immunity‐activating metabolites salicylic acid (SA) and N‐hydroxypipecolic acid (NHP). However, their function, regulation, and diversification in most species remain unclear. Here, we have created CBP60‐DB (https://cbp60db.wlu.ca/), a structural and bioinformatic database that comprehensively characterized 1052 CBP60 gene homologs (encoding 2376 unique transcripts and 1996 unique proteins) across 62 phylogenetically diverse genomes in the plant kingdom. We have employed deep learning‐predicted structural analyses using AlphaFold2 and then generated dedicated web pages for all plant CBP60 proteins. Importantly, we have generated a novel clustering visualization algorithm to interrogate kingdom‐wide structural similarities for more efficient inference of conserved functions across various plant taxa. Because well‐characterized CBP60 proteins in Arabidopsis are known to be transcription factors with putative calmodulin‐binding domains, we have integrated external bioinformatic resources to analyze protein domains and motifs. Collectively, we present a plant kingdom‐wide identification of this important protein family in a user‐friendly AlphaFold‐anchored database, representing a novel and significant resource for the broader plant biology community.
Warm plasma catalytic coreforming of dilute bioethanol and methane for hydrogen production
Authors: Lian Hao‐Yu , Sun Zheng‐Wei , Ru Yun , Liu Jing‐Lin , Li Xiao‐Song , Zhu Ai‐Min
Published: July 2023

Toward hydrogen production from renewable sources, coreforming of dilute bioethanol (5 mol% ethanol) and methane using gliding arc discharge warm plasma is reported. For warm plasma alone, increases in methane to ethanol ratio and specific energy input lead to improving hydrogen yield, but low energy efficiency (<60%). The warm plasma coupled with Ni/CeO2/Al2O3 catalyst in a heat‐insulation reactor achieves an energy efficiency of 80%, but the large axial‐temperature drop of the catalyst bed causes low conversions. Therefore, additional heating is provided to maintain the catalyst bed temperature. Under optimal conditions, total carbon conversion of 97% and hydrogen yield of 78% are achieved with an energy cost of 1.16 kWh/Nm3 and energy efficiency of 85%.
Cooperative robust line‐of‐sight guidance law based on high‐gain observers for active defense
Authors: Luo Hongbing , Ji Haibo , Wang Xinghu
Published: July 2023

In this paper, a three‐body confrontation problem of a target‐defender team against an attacker is studied in three dimensions. To eliminate the system deviation that arises from the linearization of the model, a second‐order nonlinear model with normal acceleration as its input is established to describe the relative motion of three vehicles in three‐dimensional space. A high‐gain observer is designed to estimate the line‐of‐sight angular velocity in the case that system states cannot be measured. Based on disturbance rejection technique, a robust line‐of‐sight guidance law is developed in virtue of the estimated information for the target‐defender team so that the defender is able to intercept the attacker. Key features of the developed guidance law lie in that it does not need to know guidance information of the guidance law of the attacker in advance, and is robust to disturbance and uncertainty. Simulation examples are provided to demonstrate the effectiveness of the proposed guidance law.
Field demonstration of advanced autonomous navigation technique for a fully unmanned surface vehicle in complex coastal traffic areas
Authors: Han Jungwook , Park Hansol , Park Kyurin , Kim Sun‐Young , Lee Jae Yong , Pyo Chunseon
Published: July 2023

This study introduces an advanced autonomous navigation algorithm for unmanned surface vehicle (USV) operations in complex coastal traffic areas. To facilitate the undertaking of tests for innovative technologies, the Korean government has designated regulation‐free special zones, thereby enabling field tests for USV demonstrations without an onboard safety person on real manned‐ship navigation routes. To enable real‐world USV operation without onboard safety person, an existing autonomous navigation algorithm is extended to achieve sufficiently reliable and robust USV operation. Accordingly, berthing and unberthing algorithms are newly developed for unmanned operation, and enhanced situational awareness algorithms are applied to detect all types of obstacles, including small‐sized floating objects spread over a wide range, such as a fish farm. In particular, the Korean intelligent maritime transportation service, called e‐Navigation, is incorporated into the autonomous navigation algorithms to overcome the limitations of vehicle autonomy based on onboard sensors. To demonstrate the capability of fully unmanned operation in real marine traffic scenarios, long‐distance navigation (54 km on a single voyage) was conducted by running several missions, including navigation in complex fish farm areas, maritime surveys, collision avoidance, navigation on real traffic routes, and emergency response. The extended navigation algorithms and results of the field tests are presented and discussed in this paper.
Tailoring Writability and Performance of Star Block Copolypeptides Hydrogels through Side‐Chain Design
Authors: Garcia Ronnie V. , Murphy Elizabeth A. , Sinha Nairiti J. , Okayama Yoichi , Urueña Juan Manuel , Helgeson Matthew E. , Bates Christopher M. , Hawker Craig J. , Murphy Robert D. , Read de Alaniz Javier
Published: July 2023

Shear‐recoverable hydrogels based on block copolypeptides with rapid self‐recovery hold potential in extrudable and injectable 3D‐printing applications. In this work, a series of 3‐arm star‐shaped block copolypeptides composed of an inner hydrophilic poly(l‐glutamate) domain and an outer β‐sheet forming domain is synthesized with varying side chains and block lengths. By changing the β‐sheet forming domains, hydrogels with diverse microstructures and mechanical properties are prepared and structure–function relationships are determined using scattering and rheological techniques. Differences in the properties of these materials are amplified during direct‐ink writing with a strong correlation observed between printability and material chemistry. Significantly, it is observed that non‐canonical β‐sheet blocks based on phenyl glycine form more stable networks with superior mechanical properties and writability compared to widely used natural amino acid counterparts. The versatile design available through block copolypeptide materials provides a robust platform to access tunable material properties based solely on molecular design. These systems can be exploited in extrusion‐based applications such as 3D‐printing without the need for additives.
Laboratory-Based Evaluation of Exoskeletons in an Overhead Assembly Task
Authors: Ralfs Lennart , Peck Tobias , Weidner Robert
Published: July 2023

In recent years, the number of industrial exoskeletons has significantly increased. As a large share of assembly tasks still requires the execution of manual work, exoskeletons may help provide support to users and, thus, reduce physical strain on the human musculoskeletal system. However, exoskeletons still lack empirical evidence on their potential relieving effects on the human body and are, thus, not widely deployed in industrial applications yet. To investigate on exoskeleton’s impacts and promote their future adoption in the industry, industrial settings are increasingly modeled as different test scenarios in a laboratory environment. Within this frame, this paper presents a study (n = 4) investigating on effects of both an exemplary passive and active exoskeleton at an overhead screwing task. The qualitative and quantitative analysis by means of a questionnaire study as well as electromyographic investigations reveals significant support potentials of exoskeletons on users in assembly tasks.
Evaluation of the Ergonomic Potential of Adaptive Assembly Jigs for Large-Scale Products Using Human Modelling
Authors: Hogreve Sebastian , Wallmeier Hannah , Tracht Kirsten
Published: July 2023

The implementation of plug and fly principles for the assembly of high-lift systems requires the design of new work processes and jigs. Conventional jigs are inflexibly and lag of capabilities to adapt for product and process designs. Adaptive jigs provide higher flexibility and allow workers to position the product in accordance with their personal needs. This paper presents a novel wheel-shaped adaptive jig and investigates its influence on the ergonomics of assembling a high-lift system. A CAD program is used to model the high-lift system, the adaptive jig and workers. Based on these models, virtual scenes are generated that can be assessed with the key indicator method. The results show that the adaptive jig design improves ergonomics by eliminating the riskiest tasks during the assembly process. The adaptive jig concept has a high potential for improving production processes because it can respond flexibly to changes in the assembly process as well as to changes in product design.
Visual Programming of Robot Tasks with Product and Process Variety
Authors: Riedelbauch Dominik , Sucker Sascha
Published: July 2023

In flexible manufacturing settings, automation is shaped by ever changing conditions (e.g. varying part feeding locations, highly customizable products). Quick adaptation of robot systems is mostly achieved by visual end-user robot (re-)programming. In this paper, we discuss the explicit integration of anticipated product and process variety into visually programmed tasks. We contribute a task model which captures a user-defined range of task variants. To this end, parts are specified in terms of approximate locations and generalized parts families. Workspace exploration and combinatorial assignment planning enable online adaptation to unknown environments. Our experiments show that this adaptation capability can increase the economical efficiency of cobot use.
DOE Laser-assisted Turntable Calibration and Workpiece Registration
Authors: Schmidt Edgar , Ruppert Pascal , Henrich Dominik
Published: July 2023

The ability to review robot programs before they are executed can be used to correct erroneous programming. In complex processes, such a review can only be achieved by integration of additional peripheral devices and workpieces used into the programming framework. In this work, we present a semi-automatic method for the calibration of a turntable and a workpiece registration based on the turntable calibration utilizing only a DOE laser. The turntable pose is calculated by approaching markers on the turntable on a so called acquisition plane. Based on the calibration, workpieces are registered with intersection points between the laser beams with the turntable rotary plate. We evaluated our approach in terms of accuracy and the amount of time for execution. The resulting poses of the turntable and workpieces are used to load models into the 3D simulation of the programming framework and thus can be used to review the robot program.
Use of Autonomous UAVs for Material Supply in Terminal Strip Assembly
Authors: Boshoff Marius , Miro Michael , Sudhoff Martin , Kuhlenkötter Bernd
Published: July 2023

The multi-variant small part assembly of terminal strips requires innovative approaches for automated picking and meeting increased product variability demands with increasing process flexibility. Unmanned Aerial Vehicles (UAVs) are likely to be used in material supply for small parts and, therefore, replace manual picking of parts that are rarely needed in assembly. An autonomous material supply in the 3rd dimension could break up fixed assembly processes, reduce picking time and raise the production flexibility. In this article, the share of manual picking time in a real terminal strip assembly line is determined, and UAVs as a potential transport solution for terminals and jumpers are presented.
Exploratory Pilot Study for the Integration of Task-Specific Load Alternation into a Cyclic Assembly Process
Authors: Jansing Steffen , Rieger Christoph , Jabs Tim , Deuse Jochen , Wagenblast Florestan , Seibt Robert , Gabriel Julia , Spieler Judith , Rieger Monika , Steinhilber Benjamin
Published: July 2023

Takt work represents a significant risk factor for the development of musculoskeletal complaints and diseases, especially in short-cycle processes. The increased risk results primarily from a permanent uniform load on the musculoskeletal system. Studies on motor variability suggest that an increase in load variation can have positive effects on reducing the risk.

The research project “Integration of activity-specific load changes to reduce physical stress during takt work” aims to demonstrate the increase in load variation by introducing specific load changes during takt work as a possible means of preventing musculoskeletal disorders without causing negative effects on productivity. For this purpose, a pilot study was already carried out with ten subjects, which is presented in more detail in this paper.

As foundation for the description of this study, the given paper first provides background on the applied theoretical concepts as well as the design of the overall research project. This is followed by the presentation of the experimental procedure and the results of the pilot study on cyclic assembly. Based on the stress profiles determined via surface electromyography the sequence of the analysed reference assembly process is reconfigured in order to integrate load changes. Future investigations within the research project are planned to compare both processes in terms of risk surrogate parameters for musculoskeletal disorders.
Verification and Integration of Safety Systems for Industrial Robot Cells Using Laser-Based Distance Measurement and Augmented Reality
Authors: Seim Patrick , Theren Benedict , Kutschinski Jürgen , Kuhlenkötter Bernd
Published: July 2023

The commissioning of robot cells requires an individual safety analysis followed by an appropriate dimensioning of safety components to ensure worker safety. With increasing complexity of robot work cells, developing proper safety concepts becomes more challenging. Therefore, updated validation concepts are needed that support safety engineers and reduce delay due to commissioning. This paper presents a solution to decrease the commissioning time for robot cells due to safety considerations and implementation of measurements. Data from a digital twin (DT) is used to generate test programs that are able to automatically measure relevant safety distances. The virtual robot cell is used to generate robot paths for the real cell. A distance sensor (laser based) measures the distance to relevant objects within the real cell. The programs run automatically, and the safety engineer only defines safety relevant points within the DT. Furter on, augmented reality (AR) is used to visualize safety zones specific to the induvial generated safety concept.
Prediction of Thermodynamic Properties of Fluids at Extreme Conditions: Assessment of the Consistency of Molecular-Based Models
Authors: Staubach J. , Stephan S.
Published: July 2023

For machining processes, such as drilling, grinding, and cutting, fluids play a crucial role for lubrication and cooling. For adequately describing such processes, robust models for the thermophysical properties of the fluids are a prerequisite. In the contact zone, extreme conditions prevail, e.g. regarding temperature and pressure. As thermophysical property data at such conditions are presently often not available, predictive and physical models are required. Molecular-based equations of state (EOS) are attractive candidates as they provide a favorable trade-off between computational speed and predictive capabilities. Yet, without experimental data, it is not trivial to assess the physical reliability of a given EOS model. In this work, Brown’s characteristic curves are used to assess molecular-based fluid models. Brown’s characteristic curves provide general limits that are to be satisfied such that a given model is thermodynamically consistent. Moreover, a novel approach was developed, which uses pseudo-experimental data obtained from molecular simulations using high-accurate force fields. The method is generalized in a way that it can be applied to different force field types, e.g. model potentials and complex real substances. The method was validated based on the (scarcely) available data in the literature. Based on this pseudo-experimental data, different thermodynamic EOS models were assessed. Only the SAFT-VR Mie EOS is found to yield thermodynamically consistent results in all cases. Thereby, robust EOS models were identified that can be used for reliably modeling cutting fluids at extreme conditions, e.g. in machining processes.
Physical Modeling of Grinding Forces
Authors: Kästner F. , de Payrebrune K. M.
Published: July 2023

In order to address the increasing demands on precision in manufacturing, the prediction of various processes by model-based methods is increasingly becoming a key technology. With respect to this, the grinding process still reveals a lot of potential in terms of reliable predictions. In order to exploit this potential and to improve the understanding of the process itself, a physical force model is developed. Here, process-typical influencing factors, as well as commonly used cooling lubricants, are considered. In addition to the simulative effort for the actual model, basic experimental investigations have to be carried out. In single scratch tests, it has been found that process and deformation mechanisms such as rubbing, ploughing, and cutting of the material and also the pile-up of this material on both sides of the cutting grain are significantly involved in the development of forces. It also turned out that the resulting forces are greater when cooling lubricants are used and that the topographic characteristics of a scratch are also affected by them. For a realistic mapping of these effects within the force model, the deformation model, according to Johnson and Cook, and a discretization, according to Arbitrary Lagrangian-Eulerian, proved most suitable. For integrating the cooling lubricants, the Reynolds equation using a subroutine proves to be a suitable instrument. The challenge to complete the force model is combining the scratch and the Reynolds equation simulation.
Modeling and Implementation of a 5G-Enabled Digital Twin of a Machine Tool Based on Physics Simulation
Authors: Mertes J. , Glatt M. , Yi L. , Klar M. , Ravani B. , Aurich J. C.
Published: July 2023

The cellular network standard 5G meets the networking requirements for different industrial use cases due to the advantages of low latency, high bandwidth, and high device density while providing a very good quality of service. These capabilities enable the realization of wireless digital twins (DTs), a key element of future cyber-physical production systems. DTs for prediction, monitoring, and control of machine tools need physical modeling as well as the bidirectional exchange of information between the digital and the physical world. 5G is a wireless communication technology with the potential to disruptively change industrial communication. 5G enables wireless, highly scalable, and flexible realization of even safety- and latency-critical connections. In this paper, a 5G enabled DT of a machine tool for process control, monitoring and simulation is developed and implemented. A bidirectional communication between the physical machine tool and the DT is realized via 5G. Moreover, process prediction is enabled based on physics simulation. Next to the physical modeling of the machine behavior, a 5G-capable interface between the input and output signals of the machine control system and the developed DT is implemented. Moreover, the DT is migrated in a wireless form to an edge server. Furthermore, the capabilities of the DT are demonstrated. Therefore, the architecture and implementation of the DT as well as its benefits and challenges are outlined.
A Human-Centered Framework for Scalable Extended Reality Spaces
Authors: Memmesheimer V. M. , Ebert A.
Published: July 2023

Mixed and Virtual Reality technologies have been assigned considerable potential to support training and workflows in various domains. However, available solutions are subject to scalability limitations which evoke temporal and cognitive efforts that outweigh the technology’s intrinsic potential and prevent their application in profit-making, real-world settings. Addressing these issues, we developed a framework for Scalable Extended Reality (XRS) spaces following a human-centered design process. To this end, we derived abstract high-level use cases which exploit key benefits of Mixed and Virtual Reality technologies and can be combined with each other to describe specific low-level use cases in many domains. Based on the defined high-level use cases, i.e., design and development of physical items, training, teleoperation, co-located and distributed collaboration, we specified functional and non-functional requirements and developed a framework design solution that implements multidimensional scalability enhancements: Multiple on-site and off-site users can access the XRS space through customized Mixed or Virtual Reality interfaces and then reference or manipulate real or virtual scene components. Thereby, full scalability regarding options of interaction is provided through the integration of a robotic system that allows off-site users to manipulate real scene components on site. Eventually, the framework’s applicability to different use cases is demonstrated in theoretical walkthroughs.
Simulation-Based Investigation of the Distortion of Milled Thin-Walled Aluminum Structural Parts Due to Residual Stresses
Authors: Weber D. , Kirsch B. , D‘Elia C. R. , Linke B. S. , Hill M. R. , Aurich J. C.
Published: July 2023

Nowadays, aluminum components in aircraft are mainly found in the form of thin-walled monolithic structural parts of the internal fuselage and the wings as spars and ribs [1]. This is because these components have excellent material properties for lightweight applications, such as a high strength-to-weight ratio and good corrosion resistance [2]. A typical manufacturing process to produce such structural components is milling. For these weight-optimized, monolithic components, up to 95% of the material is removed by machining [3]. The challenge with these thin-walled structural components, which are up to 14 m long, is that part distortion can occur because of the manufacturing-specific process chain [4]. Residual stresses due to machining and upstream processes such as forming, and heat-treatments are known to be the key factor for causing those distortions [5].

In this research the effect of the residual stresses, the machining strategy, the part topology and the geometry, including the wall-thickness, on distortion were investigated experimentally, and simulatively by validated virtual models based on the finite-element method. Those models can then be used to predict the distortion. At the end distortion minimization techniques were derived.