bluuebunny/crossref_metadata_2025 huggingface dataset:
Brief Paper: Quantifying Spatial Heterogeneity of Laminated Perovskite Semiconductors Using Photoluminescence Mapping
Authors: Okia Oluka , Lanaghan Clare , Palmer Jack , Yadavalli Srinivas , Fenning David , Dasgupta Neil
Published: August 2024

Halide perovskite solar cells (PSCs) are a state-of-the-art photovoltaic technology that exhibit high efficiencies and can be manufactured using roll-to-roll systems. However, PSCs are currently fabricated using sequential layer-by-layer deposition, which constrains the selection of suitable functional layers in the solar cell and limits the processing conditions and techniques that can be used.

Lamination via diffusion bonding is a scalable parallel-processing technique that has the capability to overcome some of the challenges of sequential deposition by widening the thermal processing window and reducing the chemical compatibility requirements for PSC manufacturing. However, there remains a lack of detailed understanding of the process-structure-property relationships needed to accelerate the development of high-volume lamination-based manufacturing processes.

In this work, we introduce a method to study the process-structure-property relationships of laminated perovskite semiconductors by using a custom photoluminescence (PL) spectroscopy system to quantify spatial heterogeneity in laminated halide perovskite (HP) materials. PL is an important figure-of-merit used to quantify the optoelectronic properties of semiconductor materials used in PV manufacturing. The spatial variation in PL of a laminated HP film is compared to that of an unlaminated HP film.

The PL system uses servomotors and an Arduino microcontroller to automate a PL mapping procedure. The PL equipment is tunable to achieve a minimum possible spot size of ∼50 μm, enabling high-resolution measurements. The system is used to measure the PL of 19 separate locations on both a laminated and unlaminated HP material.

The results of this study reveal that lamination at optimal conditions will improve the average PL peak intensity of the HP by 55%, indicating that lamination has the potential to improve the optoelectronic characteristics of PSCs. However, lamination also increases the standard deviation of PL peak intensity. Therefore, although lamination improves the PL of HPs, it also induces unwanted spatial heterogeneity. This warrants future studies on the governing physical mechanisms that determine quality control metrics in lamination-based PSC manufacturing.
Variable Friction Model Development and Implementation to the Pulling Force Prediction of the Split-Sleeve Cold Expansion Process for Aluminum 2024-T3
Authors: Hossen Md. Saddam , Westrum Jeremiah J. , Shultz Matthew , Tan Hua , Kim Dave
Published: August 2024

The split-sleeve cold expansion process enhances the durability of metallic structures by imparting deep compressive residual stresses around fastener holes to extend the fatigue lives of the fastened structures. This study aims to improve the accuracy of the pulling force estimation by establishing the variable friction model of the dry-lubricated split sleeve when cold working an aluminum 2024-T3 hole. The variable friction model was empirically obtained from the friction experimental setup simplified from the split-sleeve cold expansion process. The contact-pressure-dependent variable friction model was derived through a systematic design of experiments approach with three different normal stress conditions, namely low normal stress (220 MPa), medium normal stress (440 MPa), and high normal stress (660 MPa) to cover the range of normal stresses occurred in the cold expansion process. A full quadratic response surface model was drawn for the friction coefficient’s nonlinear relationship between the mandrel and the lubricated sleeve depending on the normal stresses. The variable friction model was verified with 3-dimensional friction test finite-element (FE) simulations. This FE modeling validates the variable friction model to predict the pulling forces accurately to show a sound agreement between the estimated values and the experimentally obtained values. We conducted split-sleeve cold expansion experiments with 12.7 mm thick Al 2024-T351 alloy coupons to obtain the pulling force profile. The hole size was an average of 5.746 mm and the sleeve thickness of 0.152 mm to achieve approximately 4% radial expansion. Two 3-dimensional (3D) FE numerical analyses of the same split-sleeve cold expansion process were conducted using the variable friction model and a constant frictional coefficient of 0.05. The pulling force profiles from the FE modeling with the variable friction model closely align with those from the experiments to show the four distinct regions.
Spatial Atomic Layer Deposition: Reduced Order Model Towards In-Line Process Control
Authors: Penley Daniel , Dasgupta Neil P.
Published: August 2024

Spatial atomic layer deposition (SALD) is a thin film deposition technique that could provide precise atomic-scale control at a large enough scale for many applications, such as clean energy technologies, catalytic conversion, batteries, and anti-fouling coatings. The spatially separated precursor zones are sequentially exposed to the substrate surface to deposit a film with precise control. If the precursor zones were to intermix during a deposition process, the precise control over film thickness would be lost. Therefore, it is essential to control the location of the precursors within the process region during a manufacturing process. This is typically achieved by controlling the gas flow rates and/or pressures, however it is challenging to actively monitor the location of the precursors during a deposition process as the process region has a small characteristic length and the vapor/gas precursors are difficult to observe/monitor. Therefore, there is a need to validate the precursor location and consequential process quality during a deposition. This can be of particular importance for substrate surfaces that are highly irregular or for manufacturing conditions where external factors such as temperature and ambient air speeds could change dynamically. In this study, a reduced order COMSOL Multiphysics® model is introduced that can predict the location of precursors in the process region. The model itself is discussed; the mesh size is selected considering accuracy and computation time; the model outputs are shown; and an initial experimental validation of the model is demonstrated.
Support-Structure Decision in 3D Printing With Unsupervised Computer Vision
Authors: Guo Shenghan , Ouidadi Hasnaa , Xu Boyang
Published: August 2024

In 3D printing, support-structure decisions for CAD models heavily rely on expert knowledge. Automatically evaluating CAD geometry and deciding the need for support structures remains challenging. This study adopts the Oriented Fast and Rotated BRIEF feature detector and descriptor to match geometric features among CAD models and predict support-structure decisions for printing a new CAD model. This work demonstrates the potential of automating 3D printing process planning with AI tools.
Unsupervised Anomaly Detection Using 3D Point Cloud Data for Model-Free Products
Authors: Liu Jiayu , Bird Tommy , Nagori Aadit , Samuel Johnson , Wang Yinan
Published: August 2024

Anomaly detection is pivotal in various industrial areas, including automotive, aircraft, and manufacturing. The primary goal of anomaly detection is to minimize human intervention while enhancing detection accuracy. Recently, researchers have achieved considerable progress in pinpointing defects using image-based techniques. However, these methods present two main challenges: (i) the detection accuracy is often influenced by various image factors such as perspective, lighting, and color variations, and (ii) some defects are subtle and challenging to discern in images. Recognizing these constraints shows a growing interest in exploiting three-dimensional (3D) point cloud data. These data offer a detailed and accurate representation of an object’s surface, promising better localization of surface defects. However, the 3D point cloud processing has its challenges. Two key issues include: (i) point cloud-based methods need to be both transformation and permutation invariant, as different transformations or permutations of the 3D point cloud can describe the same object structures, and (ii) at times, anomalies might share similar geometric features (e.g., local surface variations, etc.) with a non-defective surface, especially for objects with a complex shape, which makes it hard to distinguish the normal and abnormal surfaces in the space of geometric features. This paper introduces a novel, lightweight, unsupervised approach to detect and localize surface defects from 3D point cloud data, emulating human recognition capabilities and excelling in localization accuracy. We compare the performance of the proposed method and two classical unsupervised methods, K-means clustering based on cosine similarity between normal vectors and threshold method based on local surface variations on the real scanned dataset. The results show that our proposed method receives the best defect localization accuracy compared with baseline methods.
In Situ Observations of Shear Localization and Fracture in Machining
Authors: Yadav Shwetabh , Chawla Harshit , Sagapuram Dinakar
Published: August 2024

Using direct high-speed imaging, we study the transition between different chip formation modes, and the underlying mechanics, in machining of ductile metals. Three distinct chip formation modes — continuous chip, shear-localized chip, and fragmented chip — are effected in a same material system by varying the cutting speed. It is shown using direct observations that shear-localized chip formation is characterized by shear band nucleation at the tool tip and its propagation towards the free surface, which is then followed by plastic slip along the band without fracture. The transition from shear-localized chip to fragmented chip with increasing cutting speed is triggered by crack initiation at the free surface and propagation towards the tool tip. The extent to which crack travels towards the tool determines whether the chip is partially fragmented or fully fragmented (discontinuous). It is shown that shear localization precedes fracture and controls the crack path in fragmented chip formation. Dynamic strain and strain-rate fields underlying the each chip formation mode are quantified through image correlation analysis of high-speed images. Implications for using machining as an experimental tool for fundamental studies of localization and shear fracture in ductile metals are also discussed.
A Task Allocation and Scheduling Framework to Facilitate Efficient Human-Robot Collaboration in High-Mix Assembly Applications
Authors: Kang Jeon Ho , Dhanaraj Neel , Manyar Omey M. , Wadaskar Siddhant , Gupta Satyandra K.
Published: August 2024

Automating assembly operations effectively increase efficiency while decreasing the need for humans to perform ergonomically challenging tasks. However, full automation of these tasks is still a work in progress. Leveraging the complementary strengths of humans and robots offers a solution. Humans can handle tasks requiring dexterity by working in a team, while robots undertake routine, supportive roles. However, contingency situations created by task execution failures occur more frequently in high-mix applications because of the high variability in the types of tasks. Work cells that enable collaboration between humans and robots are not likely to be economically viable unless contingency situations are detected and efficiently managed. In such situations, additional contingency tasks must be executed to recover from the contingency, and productively utilizing human agents can help the work cell quickly recover from contingencies. This paper presents a framework for automatically assigning and scheduling tasks to humans and robots to complete multiple assemblies while managing the computational complexity of generating optimal task plans. Additionally, we present methods to generate recovery task plans that effectively resolve those contingencies automatically. In our case study, we present an approach to graphically determine the number of tasks and products to consider with limited computing time.
Application of Dielectric Barrier Discharge Plasma Jet for Enhanced Wettability of Ti Grade 23 Alloy
Authors: Bhardwaj Aryan , Bayki Shayan , Mujumdar Soham
Published: August 2024

Numerous methods, including chemical etching, ultraviolet radiation, and plasma treatment, are used to functionalize the surface of metallic biomedical implants and enhance osseointegration. Among these techniques, the atmospheric pressure dielectric barrier discharge (DBD) plasma jet stands out as a promising process due to its numerous advantages, including lower operational power requirements, a cost-effective setup, and short processing times. Moreover, the plasma jet demonstrates superior flexibility in treating surfaces of components with complex geometries, such as biomedical implants. This research investigates the surface treatment process utilizing a DBD plasma jet to improve the surface wettability and decontamination of Titanium (Ti) Grade 23 for biomedical applications. An increase in the surface wettability of the plasma-treated Ti substrate is demonstrated by a reduction in the water contact angle (WCA), which is linked to the changes in the surface chemistry. The X-ray photoelectron spectroscopy (XPS) analysis reveals that the interaction of Argon plasma with the Ti surface results in the formation of oxide metallic bonds, such as TiO2 and Ti2O3, while simultaneously removing carbon bonds like CO, TiC, and other organic components. This dual action leads to an increase in surface hydrophilicity and facilitates carbon-based decontamination. Further exploration of the effects of plasma treatment is conducted via a parametric study incorporating key plasma parameters such as plasma power, treatment time, and gas flow rate. While the water contact angle is insensitive to the gas flow rate, it is affected by the plasma power and treatment time. An increase in power from 2.4 W to 6 W reduces the water contact angle, followed by an increase due to a subsequent increase in power from 6 W to 13 W. The area treated by the plasma jet expands with higher plasma power or increased flow rate. The study demonstrates that a DBD Argon plasma jet operating at 2.4 W power and a 4 slm gas flow rate can effectively modify the Ti surface with just 2 s of plasma treatment. However, the optimum wettability in terms of minimum water contact angle is achieved with a 5 s plasma treatment at an input power of 6 W and a flow rate of 8 slm. Due to the formation of a surface oxide layer and the enhanced wettability of the Ti substrate resulting from plasma treatment, it is anticipated that these modifications could enhance the adhesion of Ti implants to living tissues and promote osseointegration.
A Preliminary Investigation of Input Shaping to Reduce the Residual Vibration of a Wafer-Handling Robot
Authors: Lin Yung-Chun , Qian Chen , Awtar Shorya , Okwudire Chinedum E.
Published: August 2024

Frog-leg robots are widely used for wafer-handling in semiconductor manufacturing. A typical frog-leg robot uses a magnetic coupler to achieve contactless transmission of motion between its driving motors, which operate at atmospheric pressure, and its end effector (blade) which operates within a vacuum chamber. However, the magnetic coupler is a low-stiffness transmission element that induces residual vibration during fast motions of the robot. Excessive residual vibration can cause collisions between the fragile wafer carried by the robot and cassette, hence damaging the wafer. While this problem could be solved by slowing down the robot, it comes at the cost of reduced productivity, which is undesirable. Therefore, this paper reports a preliminary investigation into input shaping (a popular vibration compensation technique) as a tool to reduce residual vibration of a frog-leg robot during high-speed motions. Two types of motions of the robot are considered: rotation and extension. A standard input shaper is shown to be very effective for mitigating residual vibration caused by rotational motion but is much less effective for extensional motion. The rationale is that the resonance frequencies of the robot are constant during rotation but they vary significantly during extension, hence reducing the effectiveness of standard input shaping. This necessitates the use of more advanced input shapers that can handle varying resonance frequencies to mitigate residual vibration during extensional motion in future work.
Analysis of Friction Effect on Backward Extrusion of Wire Splicing Couplers
Authors: Letendre Nicholas , Ebrahim Abrar , Darzi Shayan , Ha Jinjin
Published: August 2024

Backward extrusion is a conventional metal forming process which is traditionally employed to produce symmetric, cylindrical, and hollow shaped products. During the backward extrusion process, the billet is initially placed within the die and subsequently compressed to draw the material flow through the gap between punch and die. This method offers several benefits, including increase the material utilization, improved dimensional precision and surface quality, satisfactory mechanical and microstructural properties, and the elimination of the need for additional post-processing operations for net-shaping. The precision and surface quality of the extruded product is highly dependent on the choice of lubrication used in the tooling. In this study, wire splicing couplers are designed and manufactured through the backward extrusion process using commercially pure aluminum cylindrical billets. The backward extrusion process is systematically examined at various punch velocities, each executed with two distinct commercially used lubricants. Surface quality is observed differently in two lubricants, especially one could not prevent severe surface damage along the wall. Vickers hardness evaluation on the cross-section reveals that the hardness is uniform along the wall. The part with the lubricant of lower surface quality shows higher hardness than the other. This indicates that the friction related to lubrication can alter the mechanical properties of formed parts in the backward extrusion. In contrast, the punch velocity has a marginal impact on the surface quality and hardness. The extrusion load-punch stroke curves for different lubrication and punch velocity combinations are compared to optimize extrusion parameters for achieving the desired product quality.
Dynamic Force Measurement Using an Accelerometer: A Proof-of-Concept Study
Authors: Randolph Otto , Shih Chin-Cheng , Tai Bruce
Published: August 2024

Metal cutting is a dynamic process that produces forces with a wide array of frequencies and amplitudes. Typically, dynamometers are used to measure these forces, but they are usually limited to a frequency bandwidth of 3 kHz. This maximum bandwidth is further limited by the natural frequency of the measurement setup and force transmissibility through the structure to the dynamometer. While this is acceptable for most metals, research shows that additively manufactured metals produce high magnitude vibrations at frequencies above those recorded by a dynamometer. The magnitude of the forces produced is unknown. Accelerometers are small enough to be placed near the tool-chip interface, reducing transmissivity losses, and can measure frequencies an order of magnitude higher than that of a dynamometer. The challenge is that the collected acceleration data cannot be directly translated into exogenous force data. This paper attempts to reconstruct the missing dynamic forces using a mass-spring-damper system approximation. For proof of concept, the experiment is conducted on a cantilever beam to represent a toolholder. Exogenous cyclic forces are applied using a small, lightweight electric motor rotating an eccentric mass. This eccentric mass produces a known force thanks to the centripetal mass equation. Furthermore, the forces are separately verified by mounting the motor directly to a dynamometer and measuring the outputted forces across a range of frequencies. Hammer testing is used to determine the cantilever beam system’s order and the constitutive constants for the system’s equations of motion (EOM). Next, the exogenous cyclic forces are applied to the free end of the beam. The cyclic forces are measured using the attached accelerometer. The EOM is used to convert the collected acceleration data into a predicted force. The frequency of the cyclic forces is varied across a wide frequency range, from fifty percent below the system’s natural frequency to fifty percent above the natural frequency, and the predicted and applied forces are compared. The results show a match between the predicted dynamic force and the applied force across the entire frequency range and reveals the limitations of using a dynamometer in the same frequency range. The study also discusses the potential applications of this method on an actual machine tool and the associated challenges and limitations. One potential application of this research is that of measuring the high frequency cutting forces produced by additively manufactured parts. One limitation of this method is that it does not capture static and low frequency forces.
Brief Paper: Spiral Laser Keyhole Welding of Aluminum and Copper: Composition, Microstructure and Properties
Authors: Yan Guanjin , Pour Masoud M. , Rinker Teresa J. , Carlson Blair E. , Tan Wenda
Published: August 2024

Laser keyhole welding of dissimilar metals has been widely used in industrial applications. One critical challenge for this process is the formation of intermetallic compounds (IMCs) that undermine the electrical and mechanical properties of the joints. Compared with the commonly used linear contours, welding with spiral contours can provide larger areas of joining and hence higher allowable loading. This can be particularly useful for certain applications. In this research, laser welding experiments with different spiral contours were performed, and the chemical composition, microstructure, and mechanical properties of the joints were characterized. Three spiral distances were used in the experiments. As the spiral distance was changed from 0.1 mm to 0.3 mm and 0.5 mm, the average Cu concentration in the upper region of the joints was decreased, lower amounts of IMCs were found in the joints, and the joints were capable of sustaining higher mechanical loading.
Real-Time Print Tracking in Metal Additive Manufacturing Using Acoustic Emission Sensors and Vision Transformer Algorithms
Authors: Akhavan Javid , Xu Ke , Vallabh Chaitanya Krishna , Manoochehri Souran
Published: August 2024

Directed Energy Deposition (DED) is an additive manufacturing (AM) method with applications in the aerospace, automotive, and healthcare sectors. In such complex and high-stakes applications, accurate and reliable monitoring is indispensable for assuring fabrication quality. Conventional monitoring systems using mechanical encoders and optical devices have limitations such as wear susceptibility and line-of-sight issues respectively, thereby necessitating alternative monitoring systems. One crucial aspect often overlooked in conventional monitoring systems is the real-time printing process tracking. Achieving high accuracy in tracking is paramount for identifying and mitigating defects in real-time, ultimately leading to improvements in fabrication quality. To address this problem, this research employs acoustic emission sensors for real-time monitoring in Laser DED. These sensors augment existing monitoring methods to improve both reliability and part quality. We developed and tested two machine learning models to study acoustic data correlation with the print process tracking. The first model, based on a Hybrid Convolutional Auto Encoder (HCAE), achieved over 94% accuracy in the print head spatial localization. The second, a Transformer-based model, excelled with a 98.5% accuracy rate and computational efficiency in process tracking. Our findings promise enhanced printing process tracking and pave the way for advanced AI algorithms incorporation into AM quality monitoring. The AI-enabled methods developed can be generalized to other manufacturing applications such as Laser Powder Bed Fusion.
A General Analytical Approach to Predict Machining Process Damping
Authors: Theraroz Jonathan , Tuysuz Oguzhan
Published: August 2024

Machining process productivity is adversely impacted by the unstable chatter vibrations causing poor surface quality, excessive loads, and premature tool and machine failures. Depending on the position of the cutting edge element (CEE) along the vibration wave on the part surface, its flank face and hone radius dynamically indent into the material and cause process damping (PD), which improves the machining stability. This article proposes a generalized analytical PD model by lifting the straight flank face limitation of authors’ previously developed approach and extends it to any clearance face geometries used in machining operations. The proposed model employs the dimensionality reduction method by discretizing the two-dimensional (2D) contact between the CEE and the part surface with series of springs to simulate the contact mechanics between the two. Elasto-plastic material model of the workpiece is used to calculate the contact pressure considering the work material properties, cutting edge geometry, machining and vibration parameters as inputs. The PD force is evaluated by removing the effect of the static indentation from the overall contact force. The equivalent viscous damping coefficient is calculated to linearize the PD force and can be used for accurate machining stability prediction of difficult-to-cut materials. The model has been validated with the experimentally identified and finite elements-based PD coefficients, and a stability lobes diagram in orthogonal machining. Initial results reveal that the newly proposed analytical model can eliminate the empirical values identified from time-consuming machining tests and computationally expensive numerical simulations. Next, the introduced method will be extended to PD in three-dimensional (3D) machining processes such as milling with general tool geometries having varying cutting speeds and geometries along the tool axis.
Robot-Mounted Ultrasonic Micro-Wire Bonding Tool for Structural Electronics And Sensors
Authors: Tofangchi Alireza , Caid Cassidy , Wei Danming , Hsu Keng , Popa Dan O.
Published: August 2024

This research describes the development of a cost-effective ultrasonic wire bonding system, which was later integrated into an industrial robot to enhance welding automation. Initially, the team developed an innovative 3D printed adapter to attach the ultrasonic transducer to the tool tip, along with a 3D Gantry platform for manual wire bonding to determine the optimal process conditions. The study examined the influence of different variables, such as wire type and size, ultrasonic power and duration, and mechanical pressure.

In the follow-up phase, the system was further enhanced by integrating the ultrasonic tool with a robotic arm having six degrees of freedom. A control law was developed using the calculated arm stiffness. Through experimental testing, which varied compression strength and pulse duration, the team attempted to identify effective operating conditions via destructive bond strength analysis.

This integration significantly improved the system’s functionality, allowing for more precise automated wire bonding and better data collection for process control. Practical applications demonstrated include automated wire bonding and cutting on aluminum plates and printed circuit boards with small features, using aluminum and gold wires of various diameters. The system’s ability to cut wires in-process allows continuous bonding at different locations without halting the process. Future objectives include implementing real-time monitoring of bonding failures using data-driven methods.
Effect of Static Laser Beam Shaping on Lateral and Vertical Gap Bridging for Welding of Rectangular Copper Hairpin Windings
Authors: Al Botros Rehab , Pari Maria Teresa , Fortunato Alessandro , Ceglarek Dariusz , Paolini Bryan , Franciosa Pasquale
Published: August 2024

In the race towards net-zero transportation, research in electric motor manufacturing is of significant value. Although rectangular hairpin winding provides higher power density for the stator compared to round wire, critical joining challenges need to be addressed. Motivated by the inevitable hairpin-to-hairpin gaps caused by misalignments and part tolerances, this paper investigates the impact of laser beam shaping on gap bridging for Cu-ETP hairpins during laser welding process. Two welding setups were investigated, core-only laser beam (100% core power, 0% ring power) and ring-dominant laser beam (40% core power, 60% ring power). The solidification behaviour of the molten pool was studied via high-speed camera to elucidate the impact of laser beam shaping on gap bridging and the stability of the keyhole and molten pool. Findings indicated that welding with a ring-dominant laser beam results in a more stable process, reduces fluctuations of the keyhole opening, widens the molten pool, and, ultimately, helps to bridge lateral gaps up to 1 mm (50% of the hairpin thickness) and vertical gaps up to 4 mm (200% of the hairpin thickness). The significance of the results is underpinned by the robustness of the selected ring-dominant laser beam which allows to bridge lateral and vertical gaps without changing welding parameters (i.e., number of laser passes). This eliminates the need for expensive adaptive control systems. The same level of robustness could not be achieved with a core-only laser beam.
An Industry 4.0 Project With Data Integration – From Part Design to Chip Flow and Physics-Based Machine Learning for AlMg5
Authors: Lortz Wolfgang
Published: August 2024

For decades scientists have leveraged computers to solve the complex chip-formation problem — the hope is that one day the computer will be able to solve every technological problem such as modeling of large plastic deformation occurring under friction conditions. Despite the significant number of modeling and simulation studies, there is still limited knowledge about the real nature of the chip formation process. Until today, better agreement with practical results is still being sought-after. Analyzing this situation, some scientists founded the industry 4.0 project to create new opportunities and benefits for industry. In manufacturing, this initiative requires data integration from CAD to CAM with associated Quality Management (QM), and leveraging advanced analytics such as artificial intelligence (AI) with machine learning (ML) to solve complicated problems. In metal cutting, one such complicated problem is modeling of chip formation. Prior to leveraging AI, or rather to create the premise for a physics-based approach, the phenomena occurring during chip formation need better and more realistic modeling. This paper is presenting advances in physics-based modeling of chip formation with particularization for AlMg5. Adequate process mechanics will be developed resulting in modeling of chip-formation and simulation of chip flow. Moreover, it could be shown that the theoretically developed cutting result is in good agreement with the existing experimental result. There is only one disadvantage during production in the machining cell — the generated chip is very long and it is blocking the production process. Further investigation was necessary. A chip breaker was developed as a function of the existing production spectrum with individual geometry and kinematics. For different cutting conditions and tool geometry considerations for a physics-based machine learning process are proposed.
Brief Paper: Numerical Validation of Fin Cutting As Mechanical Test Under Extreme Thermomechanical Conditions
Authors: Lopez-Hawa Homar , Moscoso-Kingsley Wilfredo , Madhavan Viswanathan
Published: August 2024

A novel mechanical test capable of measuring the flow stress within an adiabatic shear band is described. The test is validated numerically via high resolution finite element analysis. It is shown that a controllable, planar shear zone may be produced by the test, where the effective strain may be as high as 10, the effective strain rate as high as 106 /s, and the temperature as high as near melting. The test can be used for development of constitutive models that may be utilized as inputs for the modeling of severe deformation processes, including machining.
Radiation mode–based microphone array: Experimental verification
Authors: Utsuki Yudai , Kaizuka Tsutomu
Published: August 2024

The mouth of a speaker is generally close to the microphones of speech communication devices, such as headsets and phones, whereas noise sources are more distant from the microphones. Hence, near-field enhancement using microphone arrays is a promising strategy for noise suppression. This study deals with radiation mode–based microphone arrays and mainly focuses on experimentally validating the methodology. Because the radiation mode–based microphone array can be approximated as a gradient microphone, the difference between them and the advantage of the former over the latter are clarified by comparing the beampatterns.
The L-lactate dehydrogenases of
Pseudomonas aeruginosa
are conditionally regulated but both contribute to survival during macrophage infection
Authors: Florek Lindsey C. , Lin Xi , Lin Yu-Cheng , Lin Min-Han , Chakraborty Arijit , Price-Whelan Alexa , Tong Liang , Rahme Laurence , Dietrich Lars E. P.
Published: August 2024

Pseudomonas aeruginosa
is an opportunistic pathogen that thrives in environments associated with human activity, including soil and water altered by agriculture or pollution. Because L-lactate is a significant product of plant and animal metabolism, it can serve as a carbon source for
P. aeruginosa
in the diverse settings that it inhabits. In this study, we evaluate the production and use of two redundant
P. aeruginosa
L-lactate dehydrogenases, termed LldD and LldA. We confirm that the protein LldR represses
lldD
and identify a new transcription factor, called LldS, that activates
lldA
; these distinct regulators and the genomic contexts of
lldD
and
lldA
contribute to their differential expression. We demonstrate that the
lldD
and
lldA
genes are conditionally controlled in response to lactate isomers as well as to glycolate and ɑ-hydroxybutyrate, which, like lactate, are ɑ-hydroxycarboxylates. We also show that
lldA
is induced when iron availability is low. Our examination of
lldD
and
lldA
expression across depth in biofilms indicates a complex pattern that is consistent with the effects of glycolate production, iron availability, and cross-regulation on enzyme preference. Finally, macrophage infection assays reveal that both
lldD
and
lldA
contribute to persistence within host cells, underscoring the potential role of L-lactate as a carbon source during
P. aeruginosa–
eukaryote interactions. Together, these findings help us understand the metabolism of a key resource that may promote
P. aeruginosa
’s success as a resident of contaminated environments and animal hosts.

IMPORTANCE

Pseudomonas aeruginosa
is a major cause of lung infections in people with cystic fibrosis, of hospital-acquired infections, and of wound infections. It consumes L-lactate, which is found at substantial levels in human blood and tissues. In this study, we investigated the spatial regulation of two redundant enzymes, called LldD and LldA, which enable L-lactate metabolism in
P. aeruginosa
biofilms. We uncovered mechanisms and identified compounds that control the preference of
P. aeruginosa
for LldD versus LldA. We also showed that both enzymes contribute to its ability to survive within macrophages, a behavior that is thought to augment the chronicity and recalcitrance of infections. Our findings shed light on a key metabolic strategy used by
P. aeruginosa
and have the potential to inform the development of therapies targeting bacterial metabolism during infection.
Gut bacterial community profile of frugivorous bats from Cathedral Cave in Cavinti, Laguna, Philippines
Authors: Datul Bonie B. , Flores Ronilo Jose D. , Montecillo Andrew D. , De Leon Marian P.
Published: August 2024

Here we report the 16S rRNA gene amplicon analysis of the gut microbiota of three frugivorous cave bat species from the Cathedral Cave in Cavinti, Laguna, Philippines. Among the bat species, the most abundant phyla are Proteobacteria and Firmicutes D.
Draft genome sequence of rhamnolipid-producing bacteria
Thermoanaerobacter thermocopriae
strain CM-CNRG TB177 isolated from an oil reservoir in Mexico
Authors: Segovia Veronica , Martínez Pedro , Hernández-Gama Regina
Published: August 2024

The draft genome of
Thermoanaerobacter thermocopriae
CM-CNRG TB177 isolated from an oil reservoir in Mexico was determined and annotated. The organism is a thermophilic and strict anaerobe bacterium that produces rhamnolipids, using glucose as a carbon source. The predicted genome size is 2,496,169 bp and 2,550 genes.
Complete genome sequence of
Klebsiella pneumoniae
RX.G5M15, a methanol-metabolizing strain recovered from the sole of a shoe
Authors: Xu D. Y. , Leung K. M. , Lai G. K. K. , Leung F. C. C. , Griffin S. D. J.
Published: August 2024

The methanol-metabolizing strain
Klebsiella pneumoniae
RX.G5M15 was isolated from the sole of a shoe in Hong Kong. Its complete genome, a single chromosome and two plasmids totaling 5,381,940 bp (G+C 57.43%), was established through the hybrid assembly.
Draft genome sequence of
Priestia megaterium
strain IMGN3 derived from soil
Authors: Choi Sejin , Jung Hoseong , Kim Yeongjun , Han Jeong A. , Kim Eun Yu , Lee Ho-Seok
Published: August 2024

Priestia megaterium
sp. strain IMGN3 was isolated from the soil in South Korea. Here, we report its draft genome sequence, comprising 12 contigs with a total sequence length of 5.64 Mbp. This genome will provide valuable resources for future genomic studies, particularly focusing on plant growth promotion and biocontrol.
Two draft genome assemblies of
Staphylococcus aureus
strains isolated from a cheek swab of a healthy female participant
Authors: Kula Alex , Jablonska Sandra , Avalos Lexi , Jensen Tyler , Appleberry Helen , Putonti Catherine
Published: August 2024

Staphylococcus aureus
is an opportunistic pathogen often commensal within the nasal and oral cavities. Here we present the genomes of
S. aureus
O139-S and O139-NS, both isolated from the cheek swab of a healthy female participant. While found in the same sample, the two strains displayed distinct colony morphologies.
Epigenetic programming of host lipid metabolism associated with resistance to TST/IGRA conversion after exposure to
Mycobacterium tuberculosis
Authors: Dill-McFarland Kimberly A. , Simmons Jason D. , Peterson Glenna J. , Nguyen Felicia K. , Campo Monica , Benchek Penelope , Stein Catherine M. , Vaisar Tomas , Mayanja-Kizza Harriet , Boom W. Henry , Hawn Thomas R.
Published: August 2024

Mycobacterium tuberculosis
(Mtb) exposure leads to a range of outcomes including clearance, latent TB infection (LTBI), and pulmonary tuberculosis (TB). Some heavily exposed individuals resist tuberculin skin test (TST) and interferon-gamma (IFNγ) release assay (IGRA) conversion (RSTR), which suggests that they employ IFNγ-independent mechanisms of Mtb control. Here, we compare monocyte epigenetic profiles of RSTR and LTBI from a Ugandan household contact cohort. Chromatin accessibility did not differ between uninfected RSTR and LTBI monocytes. By contrast, methylation significantly differed at 174 CpG sites and across 63 genomic regions. Consistent with previous transcriptional findings in this cohort, differential methylation was enriched in lipid- and cholesterol-associated pathways including the genes APOC3, KCNQ1, and PLA2G3. In addition, methylation was enriched in Hippo signaling, which is associated with cholesterol homeostasis and includes CIT and SHANK2. Lipid export and Hippo signaling pathways were also associated with gene expression in response to Mtb in RSTR as well as IFN stimulation in monocyte-derived macrophages (MDMs) from an independent healthy donor cohort. Moreover, serum-derived high-density lipoprotein from RSTR had elevated ABCA1-mediated cholesterol efflux capacity (CEC) compared to LTBI. Our findings suggest that resistance to TST/IGRA conversion is linked to regulation of lipid accumulation in monocytes, which could facilitate early Mtb clearance among RSTR subjects through IFNγ-independent mechanisms.

IMPORTANCE

Tuberculosis (TB) remains an enduring global health challenge with millions of deaths and new cases each year. Despite recent advances in TB treatment, we lack an effective vaccine or a durable cure. While heavy exposure to
Mycobacterium tuberculosis
often results in latent TB latent infection (LTBI), subpopulations exist that are either resistant to infection or contain Mtb with interferon-gamma (IFNγ)-independent mechanisms not indicative of LTBI. These resisters provide an opportunity to investigate the mechanisms of TB disease and discover novel therapeutic targets. Here, we compare monocyte epigenetic profiles of RSTR and LTBI from a Ugandan household contact cohort. We identify methylation signatures in host lipid and cholesterol pathways with potential relevance to early TB clearance before the sustained IFN responses indicative of LTBI. This adds to a growing body of literature linking TB disease outcomes to host lipids.
Deeply branching
Bacillota
species exhibit atypical Gram-negative staining
Authors: Choi Jessica K. , Poudel Saroj , Yee Nathan , Goff Jennifer L.
Published: August 2024

The Gram staining method differentiates bacteria based on their cell envelope structure, with the monoderm and diderm cell envelope types traditionally being synonymous with Gram-positive and Gram-negative stain results, respectively. Monoderms have a single phospholipid membrane surrounded by a thick layer of peptidoglycan, while diderms have a lipopolysaccharide outer membrane exterior to a thin peptidoglycan layer. The
Bacillota
(formerly
Firmicutes
) phylum has members with both cell wall types, and recent phylogenetic analyses have shown that monoderm
Bacillota
evolved from diderm ancestors on multiple occasions. Here, we compiled Gram staining and ultrastructural data for
Bacillota
species with complete genomes to further investigate the evolution of Gram-positive and Gram-negative cell wall types. The results indicate that many deeply branching lineages at the root of
Bacillota
phylum stain Gram-negative but do not harbor genes for outer membrane protein or lipopolysaccharide biosynthesis. Phylogenetic reconstructions suggest that several deeply branching
Bacillota
species have retained a thin peptidoglycan layer in their cell walls, which was inherited from a diderm ancestor. Taxa with this atypical Gram-negative-staining cell wall structure include the thermophilic anaerobe
Symbiobacterium thermophilum
and members of the
Desulfotomaculia, Syntrophamonadia, Desulfitobacteriia, Thermosediminibacteria,
and
Thermoanaerobacteria
. Using Gram-staining results as a proxy for cell wall thickness, our analysis indicates that several independent peptidoglycan thickening events may have occurred in the evolution of the Gram-positive cell envelope.

IMPORTANCE

In this study, we examined the evolution of bacterial cell envelopes, specifically focusing on Gram-positive and Gram-negative cell wall types in the
Bacillota
phylum. Our results indicate that certain bacteria can stain Gram-negative despite having a monoderm cell wall structure, thus challenging the conventional interpretation of Gram-staining results. Our observations also question the assumption that Gram-negative staining is always indicative of a diderm structure. These findings have broader implications for understanding how and when cell walls thicken during the evolution of bacterial cell envelopes.
Genotypic characterization and antimicrobial susceptibility of human
Campylobacter jejuni
isolates in Southern Spain
Authors: Fernández-Palacios Pablo , Galán-Sánchez Fátima , Casimiro-Soriguer Carlos S. , Jurado-Tarifa Estefanía , Arroyo Federico , Lara María , Chaves J. Alberto , Dopazo Joaquín , Rodríguez-Iglesias Manuel A.
Published: August 2024

Campylobacter jejuni
is the main cause of bacterial gastroenteritis and a public health problem worldwide. Little information is available on the genotypic characteristics of human
C. jejuni
in Spain. This study is based on an analysis of the resistome, virulome, and phylogenetic relationship, antibiogram prediction, and antimicrobial susceptibility of 114 human isolates of
C. jejuni
from a tertiary hospital in southern Spain from October 2020 to June 2023. The isolates were sequenced using Illumina technology, and a bioinformatic analysis was subsequently performed. The susceptibility of
C. jejuni
isolates to ciprofloxacin, tetracycline, and erythromycin was also tested. The resistance rates for each antibiotic were 90.3% for ciprofloxacin, 66.7% for tetracycline, and 0.88% for erythromycin. The fluoroquinolone resistance rate obtained is well above the European average (69.1%). CC-21 (
n
= 23), ST-572 (
n
= 13), and ST-6532 (
n
= 13) were the most prevalent clonal complexes (CCs) and sequence types (STs). In the virulome, the
cadF, ciaB
, and
cdtABC
genes were detected in all the isolates. A prevalence of 20.1% was obtained for the genes
wlaN
and
cstIII
, which are related to the pathogenesis of Guillain-Barré syndrome (GBS). The prevalence of the main antimicrobial resistance markers detected were CmeABC (92.1%), RE-cmeABC (7.9%), the T86I substitution in
gyrA
(88.9%),

bla
OXA-61

(72.6%)
, tet(O)
(65.8%), and

ant (
6
)-Ia

(17.1%). High antibiogram prediction rates (>97%) were obtained, except for in the case of the erythromycin-resistant phenotype. This study contributes significantly to the knowledge of
C. jejuni
genomics for the prevention, treatment, and control of infections caused by this pathogen.

IMPORTANCE

Despite being the pathogen with the greatest number of gastroenteritis cases worldwide,
Campylobacter jejuni
remains a poorly studied microorganism. A sustained increase in fluoroquinolone resistance in human isolates is a problem when treating
Campylobacter
infections. The development of whole genome sequencing (WGS) techniques has allowed us to better understand the genotypic characteristics of this pathogen and relate them to antibiotic resistance phenotypes. These techniques complement the data obtained from the phenotypic analysis of
C. jejuni
isolates. The zoonotic transmission of
C. jejuni
through the consumption of contaminated poultry supports approaching the study of this pathogen through “One Health” approach. In addition, due to the limited information on the genomic characteristics of
C. jejuni
in Spain, this study provides important data and allows us to compare the results with those obtained in other countries.