Mechanical Work Research Articles

Membrane-Active Antibiotics Affect Domains in Bacterial Membranes as the First Step of Their Activity.

The need to combat antimicrobial resistance is becoming more and more pressing. Here we investigate the working mechanism of a small cationic agent, N-alkylamide 3d, by conventional and high-speed atomic force microscopy. We show that N-alkylamide 3d interacts with the membrane of Staphylococcus aureus, where it changes the organization and dynamics of lipid domains. After this initial step, supramolecular structures of the antimicrobial agent attach on top of the affected membrane gradually, covering it entirely. These results demonstrate that lateral domains in the bacterial membranes might be affected by small antimicrobial agents more often than anticipated. At the same time, we show a new dual-step activity of N-alkylamide 3d that not only destroys the lateral membrane organization but also effectively covers the whole membrane with aggregates. This final step could render the membrane inaccessible from the outside and possibly prevent signaling and waste disposal of living bacteria.

Neuromorphic engineering in GaN HEMTs exploiting dendritic dislocations for neuromodulation behaviors and adaptive intelligent power forecasting systems

Gallium nitride (GaN), a prominent III-V semiconductor, plays a pivotal role in the advancement of sophisticated power systems. This study presents an innovative neuromorphic engineering approach utilizing the unique dendritic dislocations extending from bulk to channel within GaN High Electron Mobility Transistors (HEMTs) for three-dimensional charge modulation. This approach dynamically alters charge states and channel potentials in response to multiple parametric stimuli, effectively mimicking neural processing and transmission functions, as well as emulating direct and indirect neuromodulation behaviors observed in human nervous system. The advanced neuromodulation emulation enhances biomimetic diversity, laying a solid foundation for the design of intelligent systems. Comprehensive material and electrical analyses reveal the charging and discharging behaviors of the defect energy levels, underlying the neuromorphic working mechanisms. Additionally, by incorporating artificial neural network algorithms, an intelligent power forecasting system that leverages the device’s diverse neuromorphic traits is developed for real-time and adaptive power management, optimizing efficiency and accuracy in balancing supply and demand, thereby enhancing the cost-effectiveness and sustainability of power systems. The findings highlight the neuromorphic capabilities of GaN devices and open avenues for further exploration into the intelligent power management.

Analysis of root-environment interactions reveals mechanical advantages of growth-driven penetration of roots.

Plant roots are considered highly efficient soil explorers. As opposed to the push-driven penetration strategy commonly used by many digging organisms, roots penetrate by growing, adding new cells at the tip, and elongating over a well-defined growth zone. However, a comprehensive understanding of the mechanical aspects associated with root penetration is currently lacking. We perform penetration experiments following Arabidopsis thaliana roots growing into an agar gel environment, and a needle of similar dimensions pushed into the same agar. We measure and compare the environmental deformations in both cases by following the displacement of fluorescent beads embedded within the gel, combining confocal microscopy and Digital Volume Correlation (DVC) analysis. We find that deformations are generally smaller for growing roots. To better understand the mechanical differences between the two penetration strategies, we develop a computational model informed by experiments. Simulations show that, compared to push-driven penetration, grow-driven penetration reduces frictional forces and mechanical work, with lower propagation of displacements in the surrounding medium. These findings shed light on the complex interaction of plant roots with their environment, providing a quantitative understanding based on a comparative approach.

ANALISIS DAMPAK PENGGUNAAN CRYPTOCURRENCY TERHADAP PERTUMBUHAN EKONOMI ISLAM DI INDONESIA

This research aims to gain a better understanding of cryptocurrencies, including their working mechanisms and impact in economic and investment contexts. Apart from that, this research also wants to evaluate the potential consequences of the government’s lack of seriousness regarding the spread of cryptocurrency in Indonesia. The method used is a qualitative descriptive approach with normative aspects, including risk analysis and potential profits from investing in cryptocurrency. This research covers the spread of cryptocurrencies across Indonesia and the risks associated with their use. It is hoped that the results of this research will provide a deeper understanding of how cryptocurrencies work, their impact, and the role of governments in regulating their spread. Therefore, this research will provide important information for the government and society in making decisions regarding the regulation and use of cryptocurrency in Indonesia.Keywords: Cryptocurrency; Investment; Islamic Economics

Design of active vibration isolation controller for pointing stabilization mechanism based on feedforward–feedback hybrid control

The use of space technology and small space loads is increasingly common. To address this, a mechanism for isolation vibration in small optical load has been proposed. The mechanism includes a coarse and fine stage parallel pointing platform (CFPP). This paper investigates an active vibration isolation scheme for the novel pointing stabilization mechanism. The kinetic energy minimization principle is derived from the analysis of its working mechanism and dynamic feedforward characteristics. This principle is confirmed by the feedforward of the indeterminate degrees of freedom of the under-constrained mechanism. A hybrid control scheme of feedback and feedforward is developed based on the H∞ algorithm and the optimal feedforward control algorithm. Simulation and experimentation have proven that the vibration isolation efficiency of more than 20 dB can be achieved in all three axis rotation directions. This meets the precision pointing requirements of small optical load effectively.

Insights into effects of conventional and biodegradable microplastics on organic carbon decomposition in different soil aggregates

The impacts of microplastics on soil ecological functions such as carbon recycling and soil structure maintenance have been extensively focused. However, the mechanisms underlying the impacts of microplastics on soil carbon transformation and soil microbial community at soil aggregate scale have not been clarified yet. In this work, the effects and action mechanisms of traditional microplastic polypropylene (PP) and degradable microplastic polylactic acid (PLA) on carbon transformation in three sizes of soil aggregates were investigated. The results showed that both PP and PLA promoted CO2 emission, and the effect depended on the type and content of microplastics, and the size of soil aggregates. Changes in soil carbon stocks were mainly driven by changes in organic carbon associated with macroaggregates. For macroaggregates, PP microplastics decreased soil organic carbon (SOC) as well as dissolved organic carbon (DOC). These changes were reversed in microaggregates and silt and clay. Interestingly, PLA increased the SOC, DOC and CO2 emissions in bulk soil and all three aggregates with a dose-effect response. These changes were associated with soil microbes, functional genes and enzymes associated with the degradation of labile and recalcitrant carbon fractions. Furthermore, PP and PLA reduced bacterial community diversities and shifted bacterial community structures in both the three aggregates and in bulk soil. Alterations of functional genes induced by microplastics were the key driving factors of their impacts on carbon transformation in soil aggregates. This research opened up a new insight into the mechanisms underlying the impacts of microplastics on soil carbon transformation, and helped us make rational assessments of the risks and the disturbances of microplastics on soil carbon cycling.

All‐in‐One: Plasmonic Janus Heterostructures for Efficient Cooperative Photoredox Catalysis

AbstractJanus heterostructures consisting of multiple jointed components with distinct properties have gained growing interest in the photoredox catalytic field. Herein, we have developed a facile low‐temperature method to gain anisotropic one‐dimensional Au‐tipped CdS (Au−CdS) nanorods (NRs), followed by assembling Ru molecular co‐catalyst (RuN5) onto the surface of the NRs. The CdS NRs decorated with plasmonic Au nanoparticles (NPs) and RuN5 complex harness the virtues of metal‐semiconductor and inorganic‐organic interface, giving directional charge transfer channels, spatially separated reaction sites, and enhanced local electric field distribution. As a result, the Au−CdS−RuN5 can act as an efficient dual‐function photocatalyst for simultaneous H2 evolution and valorization of biomass‐derived alcohols. Benefiting from the interfacial charge decoupling and selective chemical bond activation, the optimal all‐in‐one Au−CdS−RuN5 heterostructure shows greatly enhanced photoactivity and selectivity as compared to bare CdS NRs, along with a remarkable apparent quantum yield of 40.2 % at 400 nm. The structural evolution and working mechanism of the heterostructures are systematically analyzed based on experimental and computational results.

All-in-One: Plasmonic Janus Heterostructures for Efficient Cooperative Photoredox Catalysis.

Janus heterostructures consisting of multiple jointed components with distinct properties have gained growing interest in the photoredox catalytic field. Herein, we have developed a facile low-temperature method to gain anisotropic one-dimensional Au-tipped CdS (Au-CdS) nanorods (NRs), followed by assembling Ru molecular co-catalyst (RuN5) onto the surface of the NRs. The CdS NRs decorated with plasmonic Au nanoparticles and RuN5 complex harness the virtues of metal-semiconductor and inorganic-organic interface, giving directional charge transfer channels, spatially separated reaction sites, and enhanced local electric field distribution. As a result, the Au-CdS-RuN5 can act as an efficient dual-function photocatalyst for simultaneous H2 evolution and valorization of biomass-derived alcohols. Benefiting from the interfacial charge decoupling and selective chemical bond activation, the optimal all-in-one Au-CdS-RuN5 heterostructure shows greatly enhanced photoactivity and selectivity as compared to bare CdS NRs, along with a remarkable apparent quantum yield of 40.2 % at 400 nm. The structural evolution and working mechanism of the heterostructures are systematically analyzed based on experimental and computational results.

Precursor‐Mediated Direct Growth of Defect‐Rich Hierarchical Nanocarbons for Electrocatalytic Hydrogen Peroxide Production†

Comprehensive SummaryCarbon‐based nanomaterials show great potential in selective electrochemical oxygen reduction reaction (ORR) through two‐electron (2e−) pathway for H2O2 production, which provides an eco‐friendly alternative to industrial energy‐intensive anthraquinone process. However, it still remains challenging to directly construct topological defects, which makes it difficult to study the working mechanism on 2e– ORR. Herein, we propose a precursor‐mediated chemical vapor deposition (CVD) approach for direct growth of topological defect‐rich hierarchical nanocarbons. Boric acid (H3BO3) is introduced into the precursor for disturbing the nucleation and growth through decomposing B‐containing species, which can in situ induce the formation of pentagon defects. The topological defect is found to be capable of introducing lattice strain, which can modify the electronic structure of nanocarbons and promote the key intermediate (*OOH) formation, thus greatly enhancing the 2e– ORR performance. Experimentally, the 2e– ORR selectivity shows a positive correlation to the topological defect density, where the average H2O2 selectivity reaches above 90% over a wide potential range with optimized concentration of H3BO3 as mediator. Moreover, in a flow cell, the hierarchical nanocarbons achieve a high H2O2 production rate of 998 mmol·gcatalyst−1·h−1 over 20 h of continuous electrocatalysis with stable current density (>100 mA·cm–2) and Faradaic efficiency (> 90%). This work provides a straightforward method for the synthesis of active metal‐free carbon‐based catalyst for sustainable H2O2 production.

Optical coherence tomography quantifies gradient refractive index and mechanical stiffness gradient across the human lens

BackgroundAs a key element of ocular accommodation, the inherent mechanical stiffness gradient and the gradient refractive index (GRIN) of the crystalline lens determine its deformability and optical functionality. Quantifying the GRIN profile and deformation characteristics in the lens has the potential to improve the diagnosis and follow-up of lenticular disorders and guide refractive interventions in the future.MethodsHere, we present a type of optical coherence elastography able to examine the mechanical characteristics of the human crystalline lens and the GRIN distribution in vivo. The concept is demonstrated in a case series of 12 persons through lens displacement and strain measurements in an age-mixed group of human subjects in response to an external (ambient pressure modulation) and an intrinsic (micro-fluctuations of accommodation) mechanical deformation stimulus.ResultsHere we show an excellent agreement between the high-resolution strain map retrieved during steady-state micro-fluctuations and earlier reports on lens stiffness in the cortex and nucleus suggesting a 2.0 to 2.3 times stiffer cortex than the nucleus in young lenses and a 1.0 to 7.0 times stiffer nucleus than the cortex in the old lenses.ConclusionsOptical coherence tomography is suitable to quantify the internal stiffness and refractive index distribution of the crystalline lens in vivo and thus might contribute to reveal its inner working mechanism. Our methodology provides new routes for ophthalmic pre-surgical examinations and basic research.

Microbial phosphate solubilization mechanisms in P solubilizing in andisol

Phosphate (P) nutrient plays a significant role in plant growth and yield. P is an essential element that plays an important role in photosynthesis and root development. Phosphate nutrient availability is deficient in some soil types due to retention, such as in Andisol soil types. High phosphate retention in Andisol soil types causes P nutrients to be unavailable to plants and can reduce crop yields. The availability of P in Andisol soils can be done, among others, by applying phosphate solubilizing microbes. Phosphate solubilizing microorganisms are soil microorganisms consisting of bacteria and fungi that can mineralize organic P, dissolve inorganic P minerals, and store large amounts of P to make it available to plants. This literature review aims to determine the mechanism of phosphate-solubilizing microbes in P dissolution in Andisol soil. The methods used in this systematic review are collecting data through the internet and utilizing recognized sources such as Science Direct, Research Gate, Google Scholar, and Web of Science. Content analysis was performed on the collected data, and the results were organized into thematic categories. Furthermore, the findings are presented descriptively with the help of tables to facilitate understanding. Since phosphate-solubilizing microorganisms can dissolve P in the soil through chemical and biological mechanisms, it can be concluded that phosphate-solubilizing microorganisms also have an important role in the soil P cycle. The implications of this literature review are to understand the retention of P nutrients in Andisols and how the dissolution mechanism works, as well as the use of microbes as a solution to increase phosphate dissolution so that it is available to plants.

Occupational Morbidities and Health-Seeking Behavior among Automobile Mechanics in the Western Region of Nigeria

Background: Automobile mechanic work is associated with illnesses and injuries. These occupational diseases can result in sickness absence, economic loss, disability, or death of these workers. This study assessed self-reported health problems and health-seeking behavior of automobile mechanics in Surulere, Lagos State. Methods: A cross-sectional study was used in this study carried out in December 2014. A systematic sampling method was employed to select 120 respondents from various workshops within their Local Government Area and were interviewed using a structured questionnaire. Data entry and analysis were done using epi-info3.5.1 Results: About 27.5% of the respondents reported at least one work-related illness or injury. Five percent of the respondents had musculoskeletal disease. About 11.5% of the respondents reported having cuts and crushing injuries. Most (86.7%) of these workers do not have health workers available around their workplaces. Slightly less than half (48.3%) visit health facilities between 6 to 15 minutes of estimated walking distance. Most (70%) respondents visit health facilities when ill or injured; 33.3% patronize traditional healers/ herbs/ prayer houses (spiritualists); 25% patronize patent medicine vendors and practice self-medication. The level of education of the workers was inversely significantly associated with the occurrence of occupational injury or illness. Conclusion: High work-related morbidities were managed by a few available health workers who were majoring in the patent medicine vendor category. The importance of level of education in the control of workplace injuries and illnesses was demonstrated by this study.

Features of mechanization of work during the construction of buildings using low-rise construction technologies

Currently, in Uzbekistan, the low-rise housing construction sector is in a stage of dynamic development and, as a rule, is aimed at developing the territories of suburbs and agricultural areas. First of all, the trend of growth in the volume of low-rise residential construction is due to the fact that the construction of low-rise buildings is much less expensive in comparison with the construction of high-rise residential buildings. In addition, the operating costs of low-rise residential buildings are significantly lower than high-rise ones, since there is no need to install expensive engineering equipment (elevator equipment, high-power pumping equipment, fire protection systems, etc.). State programs in the field of providing the country's citizens with affordable and comfortable housing provide for a comprehensive reduction in its sales value, which is primarily achieved by reducing the cost of construction, including by reducing the consumption of fuel and energy resources (FER) during the construction of buildings.

Extraction of Mechanical Work from Collective Motion of Pt Catalytic Particles Induced by Chemical Reactions

Extraction of Mechanical Work from Collective Motion of Pt Catalytic Particles Induced by Chemical Reactions

The pumping performance, mechanism and challenges of low voltage and non-magnetic ion pump based on pyroelectric principle

In this paper, a low voltage non-magnetic ion pump based on pyroelectric materials is proposed, mainly applied in non-magnetic and high vacuum systems such as cold atom inertial sensors. By utilizing the discharge characteristics of pyroelectric materials in vacuum, the discharge current and high-voltage electric field required for the operation of ion pump can be obtained, eliminating the need to apply high voltage to the cathode like traditional ion pumps based on Penning source. The effectiveness of the pyroelectric ion pump is verified by activating it simultaneously with the molecular pump and only activating the ion pump in a 1000 cm3 stainless steel vacuum chamber. The working mechanism of the pyroelectric ion pump is proposed and experimentally verified.

Bending Dielectric Elastomer Actuators

Dielectric Elastomer Actuators (DEAs) are a type of electroactive polymers that transform electric energy into mechanical work and are capable of large strains and high energy densities. DEAs are often described as “artificial muscles” because they exhibit strains, energy density, and responsiveness similar to natural human muscles. Their applications as soft robotic grippers, artificial arms, underwater robots, and aerial robots have previously been demonstrated. Single-layer DEAs have a simple design, with a dielectric layer sandwiched between compliant electrodes. However, by alternating positive and negative electrodes, multilayer DEAs can exhibit larger forces and strains than single-layer DEAs. DEAs are actuated by applying voltage and forming an electric field, generating a Maxwell stress between the electrodes. The process of fabricating a multilayer DEA consists of spin coating and curing layers of elastomer, stamping carbon nanotubes (CNT), and making connections to the electrodes. By alternating positive and negative electrodes, multilayer DEAs are constructed, which can exhibit larger forces and strains than single-layer DEAs. When electrically activated, DEAs expand laterally; however, by fabricating a bimorph DEA actuator, we demonstrate bending DEAs. A bimorph DEA consists of a multilayer DEA layer attached to a thicker inactive elastomer layer. When the bimorph is actuated, only the DEA layer expands, causing the actuator to bend. We study the relationship between the bending and stiffness of the inactive layer. By changing the shape of the DEA to a triangle or wing-like shape, we also emulate the high-frequency flapping of birds. Work begun on characterizing the voltage-controlled deflection of bimorph DEAs and understanding the mechanics of the bending of a simple beam in terms of forces at Harvard University will be continued on the Navajo Reservation at Navajo Technical University.

CO2 Capture By Hybrid Electrolyte Membrane Electrode Assembly

In the pursuit of decarbonizing transportation sectors, there has been considerable enthusiasm from both industries and academia regarding the utilization of atmospheric CO2 as a chemical feedstock. To mitigate the energy requirements associated with carbon capture, utilization, and sequestration, research efforts are focused on developing and exploring electrochemical cell technologies. Here, we present an innovative solid oxide electrochemical cell configuration featuring a hybrid electrolyte membrane electrode assembly (HE-MEA) designed for efficient CO2 capture and separation. Our approach involves optimizing the process through the tuning of electrolyte and electrode compositions and operation conditions, aiming to capture CO2 effectively under various conditions. The investigation of the cathode's working mechanism, employing advanced characterization techniques, will be presented. This study marks a significant step forward in CO2 capture, particularly at elevated temperatures, and contributes to the broader effort of advancing sustainable practices in transportation and combating climate change.

Probing the Depths of Electrocatalysis Systems: X-Ray Absorption Spectroscopy Reveals Catalyst Behavior

X-ray absorption spectroscopy (XAS) is a powerful experimental technique used to study the electronic structure and local environment of atoms in a material. It provides valuable insights into the chemical bonding, oxidation states, and coordination geometry of elements. XAS has been widely applied in various fields of electrochemistry, including popular topics like the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and CO2 reduction reaction (CO2RR).Despite the growing recognition of the practical importance of XAS techniques, correlating experimental spectroscopy with the working mechanisms and deciphering the structure of the electrochemical interface under reaction conditions remains challenging. In the case of CO2RR, we utilized operando XAS to investigate multiple Cu-based catalysts in different cell configurations. Our findings revealed that altering the reaction environment can induce an alternative pathway for catalyst structural changes. Moreover, operando XAS demonstrated that the reduction of Cu oxide catalysts is not solely governed by applied potentials but is also influenced by mass transport and other parameters. For ORR, in situ XAS not only provides information about the local environment changes of Pt-based catalysts but also unveils surface properties through △μ-X-ray adsorption near-edge spectroscopy (△μ-XANES). This further aids in the discovery of degradation mechanisms in proton exchange membrane fuel cells (PEMFCs). In the case of HER, in situ XAS enables characterization beyond catalysts and extends to the electrochemical interface.Overall, XAS techniques play a crucial role in understanding the electronic structure and local environment of atoms in electrochemical systems, shedding light on reaction mechanisms and catalyst performance under realistic conditions Acknowledgement The authors thank the funding source from Liquid Sunlight Alliance under the U.S. DOE, Office of Science, Office of Basic Energy Sciences, Fuels Award Number DE-SC0021266 and the Laboratory Directed Research and Development Program of the Lawrence Berkeley National Laboratory under the U.S. DOE Contract No. DE-AC02-05CH11231.

Interface Engineering of Transition Metal-Based Heterostructure Electrocatalysts for Enhanced Hydrogen Evolution Reaction

Electrochemical water splitting to produce clean hydrogen plays a significant role in the development of the hydrogen economy. The rational design of highly efficient and inexpensive electrocatalysts is critical for improving water electrolysis efficiency. Herein, we report the fabrication of heterostructure monometallic, bimetallic, and trimetallic sulfides on Ni foam (NF) as porous self-supported electrodes for hydrogen evolution reaction (HER) via an energy-saving electrodeposition process. Molybdenum-cobalt-nickel sulfide electrode (MoCoNiS@NF) only requires a low overpotential of 114 mV to produce a current density of 10 mA cm-2 for HER, compared with nickel sulfides (NiS@NF, 142 mV) and cobalt-nickel sulfides (CoNiS@NF, 129 mV). The desirable HER performance of MoCoNiS@NF results from the synergistic effect of heterostructure interfaces of multi-metal sulfides, providing high intrinsic catalytic activity and a large amount of catalytic active sites. Electrochemical impedance spectroscopy and Tafel slope analysis proved the fast reaction kinetics of MoCoNiS@NF toward HER. Our present work provides valuable insights into the working mechanisms behind the HER catalytic process and new perspectives for the future design of cost-effective electrocatalysts for HER.

Hydrogen Contaminant Detectors for Ensuring Hydrogen Fuel Quality

The California Energy Commission tracks Hydrogen Refueling Station (HRSs) installations within California and states that there are 66 light duty retail stations open within the State with another 34 in the planning stages.1 The hydrogen dispensed in these stations is expected to meet SAE J2719 standards for the maximum allowable concentration of various impurities.2 Currently HRSs have their fuel analyzed periodically to verify that they meet fuel specifications. However, this implies that any anomaly in the purification system resulting in contaminated hydrogen can result in significant damage to fuel cell vehicles before being detected. Therefore, the development of hydrogen contaminant detectors that can continuously monitor the hydrogen for impurities like Carbon monoxide (CO) and hydrogen Sulfide (H2S) is of great interest. LANL has developed a hydrogen contaminant detector based on a hydrogen pumping cell that is sensitive to < 200 ppb CO and < 4 ppb H2S.3,4 In this talk we will present details of the working mechanism of this hydrogen contaminant detector and present results from the field testing of the detector at a HRS. Acknowledgements This research is supported by the U.S. Department of Energy Fuel Cell Technologies Office, through the Safety, Codes & Standards (SCS) sub-program (Project Manager: Laura Hill).REFERENCES: https://www.energy.ca.gov/data-reports/energy-almanac/zero-emission-vehicle-and-infrastructure-statistics/hydrogen-refueling.San Marchi, E. S. Hecht, I. W. Ekoto, K. M. Groth, C. LaFleur, B. P. Somerday, R. Mukundan, T. Rockward, T; J. Keller, C. W. James, Int. J. Hydrogen Energy, 42(11), 7263-7274 (2017)Brosha, T. Rockward, C. J. Romero, M. S. Wilson, C. Kreller and R. Mukundan, U.S Patent # 10,490,833 (2019).R. Mukundan, E. L. Brosha, C. J. Romero, D. Poppe, T. Rockward, “Development of an electrochemical hydrogen contaminant detector”, Journal of The Electrochemical Society, 167(14), 147507 (2020)