Hasil untuk "Materials of engineering and construction. Mechanics of materials"

N. Mulliqi, A. Blilie, X. Ji et al.

The role of artificial intelligence (AI) in pathology has evolved from aiding diagnostics to uncovering predictive morphological patterns in whole slide images (WSIs). Recently, foundation models (FMs) leveraging self-supervised pre-training have been widely advocated as a universal solution for diverse downstream tasks. However, open questions remain about their clinical applicability and generalization advantages over end-to-end learning using task-specific (TS) models. Here, we focused on AI with clinical-grade performance for prostate cancer diagnosis and Gleason grading. We present the largest validation of AI for this task, using over 100,000 core needle biopsies from 7,342 patients across 15 sites in 11 countries. We compared two FMs with a fully end-to-end TS model in a multiple instance learning framework. Our findings challenge assumptions that FMs universally outperform TS models. While FMs demonstrated utility in data-scarce scenarios, their performance converged with - and was in some cases surpassed by - TS models when sufficient labeled training data were available. Notably, extensive task-specific training markedly reduced clinically significant misgrading, misdiagnosis of challenging morphologies, and variability across different WSI scanners. Additionally, FMs used up to 35 times more energy than the TS model, raising concerns about their sustainability. Our results underscore that while FMs offer clear advantages for rapid prototyping and research, their role as a universal solution for clinically applicable medical AI remains uncertain. For high-stakes clinical applications, rigorous validation and consideration of task-specific training remain critically important. We advocate for integrating the strengths of FMs and end-to-end learning to achieve robust and resource-efficient AI pathology solutions fit for clinical use.

Dina A. Emarah, Mostafa A. Mostafa, M. Anwar

This study investigates the influence of curing methods on the mechanical properties and pore structure characteristics of concretes including Sulphate-Resisting Cement (SRC), Ordinary Portland Cement (OPC), and Blast-Furnace Slag Cement (BFSC). Two curing regimes were applied: water immersion (Method I) and controlled humidity (Method II) at 22 °C and 80 % RH, with twice-daily water sprinkled for 7 days. Concrete mixtures with a 0.4 water-to-cement ratio and 400 kg/m3 cement content were assessed in terms of fresh properties, including slump, air content, and unit weight. The hardened properties were evaluated through compressive, flexural, and tensile strength tests, in addition to pulse velocity and dynamic elastic modulus measurements. To examine the impact of curing conditions on porosity, Mercury Intrusion Porosimetry (MIP) was used to quantify cumulative intrusion volume, porosity, pore surface area, and average pore diameter. Unlike previous studies that primarily focus on compressive strength, this research uniquely investigates mechanical performance with pore structure variations induced by curing conditions, filling a critical gap in the existing literature. The findings confirm that Method I significantly improves mechanical properties, particularly for SRC, which achieved the highest compressive strength of 741 kg/cm2 at 180 days. OPC exhibited the highest flexural strength (86.0 kg/cm2 at 28 days), whereas SRC outperformed in tensile strength under Method I. MIP analysis revealed that water immersion curing reduced the average pore diameter of SRC to 0.0266 μm, resulting in denser concrete, making it ideal for aggressive Sulphate-rich and chloride-laden environments. The study further validates nondestructive testing methods, as pulse velocity and dynamic elastic modulus correlated well with compressive strength results, reinforcing their reliability in assessing concrete quality without destructive testing. Additionally, this research provides a practical comparison between standard curing and field-applicable curing methods, addressing real-world construction constraints where continuous water immersion is often impractical. These findings contribute to global research by offering practical insights into curing efficiency, particularly for Sulphate-resistant and blended cementitious systems. Future research should explore extended durability assessments beyond 180 days, alternative curing techniques, and machine learning-based predictive modeling to enhance curing optimization for high-performance concrete in harsh environmental conditions.

The present issue of History of Science and Technology (Vol. 15, Issue 2, 2025) brings together a wide-ranging collection of studies that illuminate the long-term dynamics of scientific knowledge, technological systems, and their social, cultural, and political entanglements. The contributions assembled here reflect the journal’s enduring commitment to interdisciplinary scholarship and to the integration of diverse geographical, chronological, and methodological perspectives. Taken together, the articles demonstrate that science and technology are not isolated domains of technical ingenuity, but historically contingent processes shaped by imagination, institutions, power relations, material practices, and cultural values. A unifying theme of this issue is the continuity between past and present: ancient myths and early mechanical devices resonate with contemporary debates on artificial intelligence; nineteenth-century academic networks prefigure modern systems of scientific communication; industrial technologies mature through decades of negotiation between laboratories, factories, and regulatory regimes; and cultural technologies such as music, cinema, and transport reveal deep interconnections between material innovation and human perception. By juxtaposing case studies from Europe, Asia, the Middle East, and Southeast Asia, this issue underscores the global character of scientific and technological development while remaining attentive to local contexts and specific historical trajectories. The issue opens with Ahmed Shaker Alalaq’s study “Artificial Intelligence and Robotics in Ancient Times: Between Myth and Interpretation”, which explores how ancient civilizations conceptualized artificial beings capable of thought and action. By examining myths such as Automata, the Golem, and other legendary constructs from Greek, Chinese, and Near Eastern traditions, the article demonstrates that the aspiration to create intelligent artifacts is not a product of the digital age alone. Rather, it is embedded in long-standing philosophical and cultural reflections on consciousness, creativity, and the boundaries of human agency. Alalaq’s contribution situates contemporary debates on artificial intelligence within a longue durée perspective, showing how ethical concerns, fears of loss of control, and hopes for human enhancement were already articulated in mythological form. In doing so, the article provides a conceptual bridge between ancient imagination and modern technological realities, reminding readers that innovation is often guided by deeply rooted narratives and symbolic frameworks. Several contributions in this issue focus on the nineteenth century as a formative period for modern scientific institutions and communication networks. Denys Buhor’s article “Development of Ukrainian Mechanics: Context of Scientific Publications by Kharkiv Scientists of the 19th Century” offers a detailed historiographical and bibliometric analysis of the Kharkiv scientific milieu. By examining publications produced at Kharkiv University and the Kharkiv Institute of Technology, the study reveals how theoretical and applied mechanics developed in close institutional synergy. Figures such as Oleksandr Lyapunov and Volodymyr Steklov emerge not only as individual innovators but as representatives of scientific schools shaped by mentoring, academic heredity, and international exchange. Buhor’s work highlights the transition from isolated scholarly efforts to systematic research cultures aligned with industrialization and European scientific standards. Complementing this perspective, the article by Natalya Pasichnyk, Renat Rizhniak, and Hanna Deforzh, “International Relations and Scientific Communication of the Imperial Novorossiya University in the Last Third of the 19th Century”, examines the mechanisms through which Odesa scientists integrated into the European scientific space. Focusing on translations, academic mobility, participation in international congresses, and the role of the Notes of the Novorossiya Society of Naturalists, the authors demonstrate how multilingualism and institutional platforms facilitated knowledge circulation. This study underscores that scientific globalization in the nineteenth century was not a one-way transfer of ideas from Western Europe to the periphery, but a complex process of adaptation, negotiation, and mutual recognition. The transition from scientific knowledge to industrial application is examined in Artemii Bernatskyi’s article “Hybrid Laser-Arc Welding of Low-Alloy Steels: From Scientific Concept to Industrial Technology (1970s–2020s)”. This contribution traces the four-decade trajectory of hybrid welding from laboratory experiments to its selective stabilization in sectors such as shipbuilding, pipeline construction, wind-energy infrastructure, and offshore engineering. By emphasizing institutional conservatism, certification barriers, and capital intensity, Bernatskyi shows that technological diffusion of innovations is rarely linear or inevitable. The article also situates hybrid welding within contemporary sustainability debates, revealing how a technology originally developed for productivity gains later acquired environmental significance through reduced material consumption and extended service life of structures. A cluster of articles addresses the socio-political dimensions of technology in architectural and infrastructural contexts. Bharoto Bharoto, Himasari Hanan, and Andry Widyowijatnoko, in “Institutionalising Concrete Construction Technology: A Socio-Technical Formation of Modern Architecture in Indonesia”, analyze how concrete became the dominant material of postcolonial Indonesian architecture. Drawing on social construction theory, the authors show that technological institutionalization unfolded differently under the Old Order and the New Order regimes, yet resulted in a durable socio-technical system that bridged ideological and economic transformations. This study contributes a valuable Global South perspective to Science and Technology Studies by demonstrating that modernity emerges through negotiated, context-specific processes rather than simple technological transfer. Similarly, Hary Ganjar Budiman and colleagues explore colonial power relations in “Colonial Technopolitics in the Dutch East Indies: A Study of Colonial Hydroelectric Power in Pamanoekan and Tjiasemlanden Plantation”. By combining archival research with historical archaeology, the authors reveal how hydroelectric infrastructure functioned as an instrument of colonial technocracy. Hydropower stations are shown not merely as technical achievements, but as mechanisms for rendering nature calculable and for integrating local environments into global economic networks. The article foregrounds the concept of technopolitics, emphasizing that technology operates simultaneously as material infrastructure and as a means of governance. Petra Hyklová’s contribution, “Negotiating a Great Telescope: The Case of Czechoslovakia”, offers a detailed reconstruction of the political, institutional, and personal negotiations surrounding the construction of the Ondřejov 2-m telescope. The article demonstrates that large scientific instruments are products of complex collaborations involving scientists, manufacturers, state administrations, and international partners. By highlighting the parallel development of similar telescopes in Czechoslovakia and Azerbaijan, Hyklová reveals how scientific ambitions intersected with Cold War politics, economic constraints, and long-term planning. The continued operation of these instruments today underscores the durability of such negotiated technological systems. The cultural dimensions of technology are explored in the article “Pneumatics, Acoustics and Digital Sound: The Organ in the History of Science and Technology” by Olena Spolska and co-authors. Treating the organ as a long-lived technological system, the study traces its evolution from the ancient hydraulis to contemporary digital and hybrid instruments. The article demonstrates how advances in pneumatics, acoustics, metallurgy, electrification, and computation were gradually absorbed into organ building without erasing earlier traditions. Transport history and the culture of speed form the focus of the next article “The History of the Emergence, Development and Improvement of High-Speed Railways”. By combining technical, socio-economic, and cultural analysis, the authors show how high-speed rail transformed perceptions of space and time while serving as a tool of regional integration and economic development. From the Shinkansen and TGV to contemporary maglev and Hyperloop concepts, high-speed rail emerges as a key component of twenty-first-century energy-intelligent mobility. The issue concludes with the article “Silent Cinema as a Technological System: Infrastructure, Innovation, and Institutionalization (1890–1930)” by Liudmyla Vaniuha and colleagues. Challenging the view of silent cinema as a primitive precursor to sound film, the authors demonstrate that this period established the foundational technological and institutional structures of modern cinema. Projection systems, permanent theaters, studio infrastructures, special effects, and genre formation collectively transformed film into a global medium of mass communication. This study highlights cinema as a paradigmatic example of how technology, industry, and culture co-evolve. Together, the articles in this issue of History of Science and Technology illustrate the richness and diversity of contemporary scholarship in the field. They reaffirm that the history of science and technology is best understood through interdisciplinary approaches that connect technical detail with social context, institutional frameworks, and cultural meaning. By bringing ancient myths into dialogue with artificial intelligence, colonial infrastructures with postcolonial modernity, and nineteenth

Declan Kopper, Marina S. Leite

Thermophotovoltaics (TPVs) have the potential to exhibit higher power conversion efficiencies than traditional photovoltaics (PVs), with a broad range of applicability from waste recovery systems to aerospace solutions. They operate by preferentially radiating above bandgap photons via a high temperature optical emitter, whose spectrum is tuned through choice of materials and geometry. For TPV to be practically implemented, the emitters must be designed with a simple optical structure while remaining thermally stable. Here, we demonstrate coating/substrate bilayer thin films as a solution to these design criteria. With the optical data of 53 high melting point materials, we simulate the bilayer emissivity as a function of coating thickness for each thermochemically stable emitter operating at 1,800 °C. Emitter-cell systems are characterized by the cell power density and TPV conversion efficiency, constituting a TPV performance metric space. For a given bilayer and bandgap these coating thickness parameterized figures of merit form a performance metric curve, with the best points defining a tradeoff zone. We screen the resulting performance metric curves, identifying trends based on optical properties of the system, finding a high degree of tunability through the material selection step. For GaSb cells, >49% efficiency is achieved using AlN/W, a 5.6% increase over bulk W. By calculating the figures of merit for all systems with varying bandgap, we find unique emitter choices per PV cell for achieving the highest potential efficiency. Our materials screening approach uses physical data to identify improvements to emitters for experimental TPV designs.

Pankaj Priyadarshi, Vassilios Vargiamidis, Neophytos Neophytou

Using Monte Carlo electronic transport simulations, coupled self-consistently with the Poisson equation for electrostatics, we explore the thermoelectric power factor of nanoengineered materials. These materials consist of alternating highly doped and intrinsic regions on the scale of several nanometers. This structure enables the creation of potential wells and barriers, implementing a mechanism for filtering carrier energy. Our study demonstrates that by carefully designing the nanostructure, we can significantly enhance its thermoelectric power factor compared to the original pristine material. Importantly, these enhancements stem not only from the energy filtering effect that boosts the Seebeck coefficient but also from the utilization of high-energy carriers within the wells and intrinsic barrier regions to maintain relatively high electronic conductivity. These findings can offer guidance for the design and optimization of new-generation thermoelectric materials through improvements in the power factor.

Advances in Materials Science and Engineering

Zhu Xida, Lu Jiasheng, Zhao Yongzhi et al.

Cr12MoV flat steel mainly adopts the long process of die casting ingot， multi-fire forging and rolling， which has low production efficiency， low yield， high cost and high energy consumption. In order to solve the problems of poor thermal conductivity and ductility of cold working die steel， a short process of 90 t EBT-LF-VD-150 mm×630 mm continuous casting rectangular billet and one-fire heating +15-pass rolling was designed. The rectangular continuous casting billet and rolled 19 mm thick flat steel products of Cr12MoV steel were successfully developed， continuous casting center porosity 1.5 grade， center segregation ≤1.0， the finished flat steel eutectic carbide unevenness level ≤3， the defects inspection quality grade reaches grade A， and the performance indexes meet the standard requirements. Cr12MoV cold working die steel products have achieved mass production and achieved good economic benefits.

Aleksandar Nikolov, Lili Dobreva, Svetla Danova et al.

Many antimicrobial coatings deliver a peak release of antimicrobial agent at an early age, after which they lost antimicrobial activity over time. In the present study a novel geopolymer paints with long term antimicrobial activity were developed based on natural zeolite modified with silver and copper ions. The obtained geopolymer paints were applied by brushing on concrete, ceramic, gypsum paperboard and steel. The coating was characterized by excellent adhesive strength and hiding properties. The long-term antimicrobial effect was evaluated by accelerated aging in carbonation chamber. Microstructural changes were analyzed by powder X-ray diffraction and Fourier transformed infrared spectroscopy. Cytotoxicity, antibacterial, antifungal and virucidal properties were investigated on raw and carbonated geopolymer paints. Geopolymer paints based on modified natural zeolite seems promising antimicrobial coating material that can be implemented in the global fight against the spread of diseases and pathogens.

Xianzhe Shi, Xiuxia Wang, Biao Chen et al.

Oxygen has been known as an effective strengthening element in titanium (Ti) and its alloys. However, an over-dose of oxygen can also lead to embrittlement of Ti alloys. To precisely control and push the limit of oxygen in Ti and its alloys, we studied the decomposition process of Ti oxides in pure α-Ti matrix using an in-situ high-temperature scanning electron microscope. The experimental results revealed that TiO particles decomposed in α-Ti at elevated temperatures and the oxygen atoms gradually diffused into the matrix, following the Fick’s second law. Then, the samples with different oxygen contents were produced using the aforementioned strategy, for which the oxygen content, microstructure, and mechanical properties were measured. The results revealed that the oxygen content can be precisely controlled, which can achieve an ultra-high tensile strength of close to 1100 MPa, at no expense of elongation-to-failure, with incorporating 0.87 wt% oxygen. An analysis showed that the strength contribution from oxygen follows the Labusch law. These findings offer a novel approach to design high-performance Ti alloys with non-toxic and cheap elements.

Dibyendu Dey, Liangbo Liang, Liping Yu

The practically unlimited high-dimensional composition space of high-entropy materials (HEMs) has emerged as an exciting platform for functional materials design and discovery. However, the identification of stable and synthesizable HEMs and robust design rules remains a daunting challenge due to the difficulty in determining composition/structure-specific enthalpy and entropy contributions to the stability and formation of HEMs. In this work, using first-principles calculations, we find that (i) the stability and miscibility of HEMs strongly depend on the formation enthalpy of the HEM relative to the most stable completing phase rather than on the conventionally-viewed enthalpies of mixing over all possible competing phases, and (ii) the entropy forming ability of a HEM can be measured from the defect formation energy spectrum of tens of substitutional defects in ordered binary compounds, involving no sampling over numerous alloy configurations. Based on these findings, we propose a highly predictive Mixed Enthalpy-Entropy Descriptor (MEED), which enables the rational high-throughput first-principles design and screening of new HEMs over large chemical spaces. Applying the MEED to two structurally distinct material systems (i.e., 3D rocksalt carbides and 2D layered sulfides), not only all experimentally reported HEMs within each system are successfully identified, but a universal cutoff criterion for assessing their relative synthesizability also revealed. In addition, tens of new high entropy carbides and 2D high-entropy sulfides are also predicted. They have the potential for a wide variety of applications such as coating in aerospace devices, energy conversion and storage, and flexible electronics.

Tommaso Magrini, Chelsea Fox, Adeline Wihardja et al.

Composites with high strength and high fracture resistance are desirable for structural and protective applications. Most composites, however, suffer from poor damage tolerance and are prone to unpredictable fractures. Understanding the behavior of materials with an irregular reinforcement phase offers fundamental guidelines for tailoring their performance. Here, we study the fracture nucleation and propagation in two phase composites, as a function of the topology of their irregular microstructures. We use a stochastic algorithm to design the polymeric reinforcing network, achieving independent control of topology and geometry of the microstructure. By tuning the local connectivity of isodense tiles and their assembly into larger structures, we tailor the mechanical and fracture properties of the architected composites, at the local and global scale. Finally, combining different reinforcing networks into a spatially determined meso-scale assembly, we demonstrate how the spatial propagation of fractures in architected composite materials can be designed and controlled a priori.

Mohamed Zemzem, Ludwig Vinches, Stéphane Hallé

The dispersion and orientation of three different montmorillonite clay nanoparticles embedded in nitrile-based nanocomposites were examined in the current study. Maleic anhydride was grafted onto a nitrile structure for the purpose of enhancing compatibility, and the resulting nanocomposites were investigated. The grafting of maleic anhydride seemed to have a pronounced effect, leading the structure to a near-exfoliation state. Using energy dispersive x-ray spectrometer, the state of distribution of layered silicate clusters in the nanocomposite was assessed, and it was observed that maleic anhydride provided a reduction in the size of agglomerations and enhanced the homogeneity of the system. The intercalation and delamination of the layered silicates over grafting were validated by transmission electron microscopy. Inter-lamellar spacing measurements were found to correlate perfectly with x-ray data. On the other hand, the alignment of the clay nanoparticles was examined by small angle x-ray scattering. A 3D-orientation approach was developed based on the scattering stereographs.

Josiah Cherian Chekotu, Russell Goodall, David Kinahan et al.

In this work, nitinol samples were produced via Laser Powder Bed Fusion (L-PBF) in the horizontal and vertical orientations with systematic variations in laser power, scan speed and hatch spacing parameters. Increased density was positively correlated with increased laser power, scan speed and hatch spacing for the horizontally built samples but not for the vertically built samples. A smaller difference in the average temperature within a printed layer, associated with the vertically built samples, was linked with reduced porosity and reduced porosity variability between samples. Control of the L-PBF parameters was found to allow control of the resulting part chemical composition which also directly affected phase transformation temperatures, and related phase structures. The laser process parameters were found to have a significant effect (p < 0.01) on the martensite start/finish temperature, austenite start/finish temperatures, and the total temperature span. The volumetric energy density was also found to have a direct correlation with both the cooling (r = 0.52) and heating (r = 0.53) enthalpies, which was found to be due to increased nickel evaporation. Such control of phase change properties afforded from L-PBF is important for many of the end applications for nitinol components including within the energy and precision actuation sectors.

Paolo Pegolo, Stefano Baroni, Federico Grasselli

Abstract Despite governing heat management in any realistic device, the microscopic mechanisms of heat transport in all-solid-state electrolytes are poorly known: existing calculations, all based on simplistic semi-empirical models, are unreliable for superionic conductors and largely overestimate their thermal conductivity. In this work, we deploy a combination of state-of-the-art methods to calculate the thermal conductivity of a prototypical Li-ion conductor, the Li3ClO antiperovskite. By leveraging ab initio, machine learning, and force-field descriptions of interatomic forces, we are able to reveal the massive role of anharmonic interactions and diffusive defects on the thermal conductivity and its temperature dependence, and to eventually embed their effects into a simple rationale which is likely applicable to a wide class of ionic conductors.

Xianhui Zhao, Oluwafemi Oyedeji, Erin Webb et al.

Owing to its low cost and sustainable nature, lignocellulosic biomass has been utilized for reinforcing polymers, but it is crucial to understand the impact of high-ash concentrations in biomass on composite strength and processing. Biomass is not only desirable for biofuel production but could also have a strong market, if high-ash biomass is acceptable, for biocomposites. In this work, natural fibers (switchgrass and corn stover) were used to reinforce polylactic acid (PLA) to produce biocomposites. Natural fibers were pretreated to obtain fibers that contain different percentages of ash. The mechanical properties (such as Young's modulus, tensile strength, failure strain, storage modulus) of corn stover/PLA composites remained largely unaffected by the ash concentration of the biomass fibers, despite the large range of ash contents (2.2–11.9 wt%). However, the tensile strengths of switchgrass/PLA composites were slightly negatively affected by the ash concentration of the switchgrass fibers (0.7–2.1 wt%). Both the switchgrass/PLA and the corn stover/PLA composites exhibited a high-enough tensile strength (49–57 MPa) and suitable complex viscosity (2.0−7.0 kPa·s at the frequency of 3.2 rad/s). They are expected to be 3D-printable through an extrusion-based additive manufacturing process.

Devesh Shah, Anirudh Suresh, Alemayehu Admasu et al.

The evaluation of synthetic micro-structure images is an emerging problem as machine learning and materials science research have evolved together. Typical state of the art methods in evaluating synthetic images from generative models have relied on the Fréchet Inception Distance. However, this and other similar methods, are limited in the materials domain due to both the unique features that characterize physically accurate micro-structures and limited dataset sizes. In this study we evaluate a variety of methods on scanning electron microscope (SEM) images of graphene-reinforced polyurethane foams. The primary objective of this paper is to report our findings with regards to the shortcomings of existing methods so as to encourage the machine learning community to consider enhancements in metrics for assessing quality of synthetic images in the material science domain.

Aidan Rinehart, U. Lacis, Shervin Bagheri Linn'e Flow Centre et al.

The Brinkman equation has found great popularity in modelling the interfacial flow between free fluid and a porous medium. However, it is still unclear how to determine an appropriate effective Brinkman viscosity without resolving the flow at the pore scale. Here, we propose to determine the Brinkman viscosity for rough porous media from the interface slip length and the interior permeability. Both slip and permeability can be determined from unit-cell analysis, thus enabling an a priori estimate of the effective viscosity. By comparing the velocity distribution in the porous material predicted from the Brinkman equation with that obtained from pore-scale resolved simulations, we show that modelling errors are $\sim 10\%$ and not larger than $40\%$. We highlight the physical origins of the obtained errors and demonstrate that the Brinkman model can be much more accurate for irregular porous structures.

Mengxue JIAO, Ji QIU, Tao JIN et al.

In this paper, three different shapes of indenters were used to perform quasi-static out-of-plane uniaxial compression and indentation tests on three commercial hexagonal aluminum honeycombs with different densities. In order to distinguish the different tearing conditions of the single-layer and double-layer aluminum honeycomb walls during indentation, a new indentation experiment was designed. By controlling the shape of pattern and the location of indentation, different tearing conditions in indentation experiment were measured separately. The deformation mode of the aluminum honeycomb when pressed was analyzed. It is found that as the size of the pattern increases, the peak stress of the indentation experiment decreases significantly. As the size of the indenter increases, the platform stress of aluminum honeycomb shows a downward trend and tends to approach the compression platform stress, while the tear strength remains basically stable within a certain scale. As the size of the indenter continues to increase, the proportion of tearing force to the total indenting force gradually decreases, and the tearing strength loses its stability. At this time, the tear strength can no longer be used as a stable mechanical parameter to measure the tearing condition during indentation.

Conal E. Murray

The progress witnessed within the field of quantum computing has been enabled by the identification and understanding of interactions between the state of the quantum bit (qubit) and the materials within its environment. Beginning with an introduction of the parameters used to differentiate various quantum computing approaches, we discuss the evolution of the key components that comprise superconducting qubits, where the methods of fabrication can play as important a role as the composition in dictating the overall performance. We describe several mechanisms that are responsible for the relaxation or decoherence of superconducting qubits and the corresponding methods that can be utilized to characterize their influence. In particular, the effects of dielectric loss and its manifestation through the interaction with two-level systems (TLS) are discussed. We elaborate on the methods that are employed to quantify dielectric loss through the modeling of energy flowing through the surrounding dielectric materials, which can include contributions due to both intrinsic TLS and extrinsic aspects, such as those generated by processing. The resulting analyses provide insight into identifying the relative participation of specific sections of qubit designs and refinements in construction that can mitigate their impact on qubit quality factors. Additional prominent mechanisms that can lead to energy relaxation within qubits are presented along with experimental techniques which assess their importance. We close by highlighting areas of future research that should be addressed to help facilitating the successful scaling of superconducting quantum computing.

Zhenyu Chen, Jiahao Li, Yuzhi Xu

Machine learning has been widely verified and applied in chemoinformatics, and have achieved outstanding results in the prediction, modification, and optimization of luminescence, magnetism, and electrode materials. Here, we propose a deepth first search traversal (DFST) approach combined with lightGBM machine learning model to search the classic Organic field-effect transistor (OFET) functional molecules chemical space, which is simple but effective. Totally 2820588 molecules of different structure within two certain types of skeletons are generated successfully, which shows the searching efficiency of the DFST strategy. With the simplified molecular-input line-entry system (SMILES) utilized, the generation of alphanumeric strings that describe molecules directly tackle the inverse design problem, for the generation set has 100% chemical validity. Light Gradient Boosting Machine (LightGBM) model's intrinsic Distributed and efficient features enables much faster training process and higher training efficiency, which means better model performance with less amount of data. 184 out of 2.8 million molecules are finally screened out with density functional theory (DFT) calculation carried out to verify the accuracy of the prediction.