Individual Blocks Research Articles

Dynamic response of rock landslides and avalanche debris flows impacting flexible barriers based on shaking table tests

Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.

A multi-objective constraint programming approach to address clustering problems in mine planning

PurposeThe mine sequencing problem is NP-hard. Therefore, simplifying it is necessary. One way to do this is to employ clusters as input instead of individual blocks. The mining cut clustering problem has been little addressed in the literature, and the solutions used are almost always heuristic. We solve the mining cut clustering problem, which is NP-hard, through single- and multi-objective optimization, finding results that are local optima in acceptable computational time.Design/methodology/approachWe first elaborate an ILP-based model to address the mining cut clustering problem. We employ a mono-objective approach and two multi-objective approaches, solving all these models by constraint programming. To choose the best solutions generated by multi-objective approaches, we employ two multi-criteria decision analysis approaches, considering different weight configurations. We developed a case study using real data.FindingsWe verified that the approaches based on multi-objective optimization performed better than the mono-objective approach for the economic return criterion. The weighted-sum multi-objective approach presented the best results considering all objective functions used. Once viable solutions were obtained through multi-objective optimization, multi-criteria decision analysis approaches almost always selected the same solution. We obtained solutions that are local optima in acceptable computational time.Research limitations/implicationsThis study solves an instance with 80 blocks. Consequently, it is aimed at short-term mine planning. The methodology has not yet been evaluated in large instances related to medium- and long-term mine planning.Originality/valueThis is the first time that multi-objective optimization has been employed to solve the mining cut custering problem. Even other problems related to mine planning were, at most, solved by goal programming, so that multi-objective optimization is a knowledge that is not widespread among mining researchers. The results are consistent, and the study achieves the objective of finding quality solutions to an NP-hard problem in an acceptable computational time.

Impact of random geometric errors in an elliptical superconducting magnet with application to a compact heavy-ion synchrotron

A compact heavy-ion synchrotron is under development for next-generation cancer therapy. A superconducting magnet is designed with a main dipole field of 3.5 T and a field error less than 5 × 10−4 to maintain compactness. The coil is wound directly with monolithic Nb-Ti wire on a curved elliptical mandrel, comprising 22 laminated layers to achieve the desired magnetic field. Given the critical need for field quality, it is imperative to determine the tolerance of coil fabrication and to devise a method to eliminate field error during the design stage. This paper presents a numerical investigation of possible random geometric errors stemming from fabrication and assembly tolerances in a curved elliptical superconducting magnet. We first provide an analytical formulation derived in a complex plane to estimate the field error of a straight elliptical coil. We then conduct a Monte Carlo simulation to assess cases involving misalignment of individual wires and coil block sectors. Additionally, we compare simulation results with field measurements obtained from a short model magnet tested previously to predict potential random errors in manufacturing. Finally, we calculate the beam dynamic aperture to assess the effects of random geometric errors on beam loss using Monte Carlo simulation results. This method enables the prediction of tolerances for fabricating high-quality high-field magnets and aids in making design decisions concerning the utilization of active shim coils.

Bond-centric modular design of protein assemblies.

We describe a modular bond-centric approach to protein nanomaterial design inspired by the rich diversity of chemical structures that can be generated from the small number of atomic valencies and bonding interactions. We design protein building blocks with regular coordination geometries and bonding interactions that enable the assembly of a wide variety of closed and opened nanomaterials using simple geometrical principles. Experimental characterization confirms successful formation of more than twenty multi-component polyhedral protein cages, 2D arrays, and 3D protein lattices, with a high (10-50 %) success rate and electron microscopy data closely matching the corresponding design models. Because of the modularity, individual building blocks can assemble with different partners to generate distinct regular assemblies, resulting in an economy of parts and enabling the construction of reconfigurable systems.

Shear-Thinning Extrudable Hydrogels Based on Star Polypeptides with Antimicrobial Properties.

Hydrogels with low toxicity, antimicrobial potency and shear-thinning behavior are promising materials to combat the modern challenges of increased infections. Here, we report on 8-arm star block copolypeptides based on poly(L-lysine), poly(L-tyrosine) and poly(S-benzyl-L-cysteine) blocks. Three star block copolypeptides were synthesized with poly(S-benzyl-L-cysteine) always forming the outer block. The inner block comprised either two individual blocks of poly(L-lysine) and poly(L-tyrosine) or a statistical block copolypeptide from both amino acids. The star block copolypeptides were synthesized by the Ring Opening Polymerization (ROP) of the protected amino acid N-carboxyanhydrides (NCAs), keeping the overall ratio of monomers constant. All star block copolypeptides formed hydrogels and Scanning Electron Microscopy (SEM) confirmed a porous morphology. The investigation of their viscoelastic characteristics, water uptake and syringe extrudability revealed superior properties of the star polypeptide with a statistical inner block of L-lysine and L-tyrosine. Further testing of this sample confirmed no cytotoxicity and demonstrated antimicrobial activity of 1.5-log and 2.6-log reduction in colony-forming units, CFU/mL, against colony-forming reference laboratory strains of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, respectively. The results underline the importance of controlling structural arrangements in polypeptides to optimize their physical and biological properties.

The Role of Alkyl Chains in the Thermoresponse of Supramolecular Network.

Supramolecular materials provide a pathway for achieving precise, highly ordered structures while exhibiting remarkable response to external stimuli, a characteristic not commonly found in covalently bonded materials. The design of self-assembled materials, where properties could be predicted/design from chemical nature of the individual building blocks, hinges upon ourability to relate macroscopic properties to individual building blocks - a feat which has thus far remained elusive. Here, a design approach is demonstrated to chemically engineer the thermal expansion coefficient of 2D supramolecular networks by over an order of magnitude (\boldmath 120 to \boldmath 1000 × 10-6K-1). This systematic study provides a clear pathway on how to carefully design the thermal expansion coefficient of a 2D molecular assembly. Specifically, a linear relation has been identified between the length of decorating alkyl chains and the thermal expansion coefficient. Counter-intuitively, the shorter the chains the larger is the thermal expansion coefficient. This precise control over thermo-mechanical properties marks a significant leap forward in the de-novo design of advanced 2D materials. The possibility to chemically engineer their thermo-mechanical properties holds promise for innovations in sensors, actuators, and responsive materials across diversefields.

Evaluation of Multiple Tissue Levels Frequently Upstages Patients With Clinically Localized Thin Primary Cutaneous Melanoma.

Breslow thickness (BT), ulceration, and microsatellitosis are critical prognostic parameters for cutaneous melanoma staging. These parameters can vary depending on the number of tissue levels examined from individual paraffin blocks. We sought to evaluate all prognostic histopathologic parameters in melanoma for their variations between levels, taken at regular intervals, in a single study. We analyzed 40 consecutive cases of primary cutaneous (nonacral) melanoma through five hematoxylin and eosin sections, taken at 100 μm intervals, for staging and prognostic parameters. Examination of additional levels resulted in (a) an increase in BT in 47.5% (19 out of 40) of cases and (b) detection of ulceration in a further 5% (2/40). This resulted in upstaging for 20% (8 out of 40) of patients (15% because of BT, 2.5% because of ulceration, and 2.5% because of BT and ulceration). The upstaging effect was incremental, with approximately 5% of patients upstaged with each additional 100 μm interval (up to 400 μm). Incipient ulceration and epidermal consumption were infrequent (10% of cases); however, when present, ulceration was subsequently observed in half of cases. We encountered no cases where microsatellitosis was detected at deeper levels. The performance of additional tissue levels is a simple and inexpensive procedure that can improve the accuracy of staging for patients with thin (pT1) primary cutaneous melanomas. It may be pertinent for pathologists to consider additional levels for thin melanomas when a BT measurement is close to a staging threshold (e.g., within 0.1-0.3 mm for pT1a vs. pT1b, or pT1b vs. pT2a), or when incipient ulceration is encountered.

THE INFLUENCE OF OBSERVATIONAL ERRORS IN GAIA DR3 ON THE RECONSTRUCTION OF GLOBULAR CLUSTER ORBITS ON A COSMOLOGICAL TIMESCALE

In recent years, the emerging field of astronomy focused on the history of galaxy formation, known as Galactic Archaeology, has been gaining popularity. Globular clusters have been involved in many key processes occurring in the Milky Way, making their study, particularly the reconstruction of their orbits, significantly important. The Gaia DR3 catalog provides parameters for 165 globular clusters, such as proper motions, radial velocity, and heliocentric distance, with certain accuracy. Therefore, it is important to examine the influence of measurement errors in these parameters on the initial data when converting to the Galactocentric coordinate system and, consequently, on the shape of the orbits. We integrated the orbits of globular clusters 10 billion years lookback. For physical justification during the integration, we used the external dynamic potential with the individual number 411321 from the cosmological simulation database IllustrisTNG-100, which best reproduces the potential of the Milky Way. The integration was performed using the parallel N-body code φ-GPU, based on a fourth-order Hermite scheme with hierarchical individual block timesteps. A total of 1,000 randomizations of the initial data were created considering a normal distribution of errors, and the influence of errors on the scatter of initial velocities and on the shape of the orbits was examined. The parameters with the largest relative errors are proper motions and radial velocity, while the smallest errors are in heliocentric distance. It was found that 85% of the globular clusters have relative errors in all parameters of no more than 10%, and 5.4% have errors of no more than 1%. Investigating the influence of measurement errors for clusters with different magnitudes of relative errors, we concluded that for most globular clusters, the influence of measurement errors on the shape of the orbits is not significant. Consequently, it is possible to reconstruct the orbits with high accuracy for these clusters. Since the reconstruction of globular cluster orbits involves cosmological timescales, accounting for measurement errors is an important aspect of the preparatory procedure before the main integration.

The Antecedents of Utilitarian and Hedonic Motivations for Online Shopping Satisfaction

Empirical studies indicate that utilitarian and hedonic shopping motivations have a profound effect on customer satisfaction in a physical brick-and-mortar shopping environment. Studies have also started to surface which underscore the importance of these motivations in the realm of e-commerce. The study, therefore, seeks to determine the antecedents of utilitarian and hedonic motivations for online shopping satisfaction. A quantitative research method with a descriptive research design was implemented in this study. The data was collected through a survey method from a sample of 215 online shoppers in an emerging economy, South Africa. The study utilised previously validated scales. Multivariate regression analysis was performed to determine the factors that influence utilitarian and hedonic motivations for online shopping satisfaction. The results reveal that information availability, cost saving, wider selection, convenience, and efficiency are the antecedents of utilitarian dimensions that determine online shopping satisfaction, while status, adventure, social shopping, idea shopping, and gratification are considered the antecedents of hedonic motivations of online shopping that influence satisfaction. The results of the study offer insight into why consumers engage in online shopping by determining the factors that influence utilitarian and hedonic motivations. Accordingly, the study offers practical recommendations to e-retailers on how to best serve their customers by focusing on the individual building blocks of utilitarian and hedonic shopping motivations.

Dynamic Clock Switching Scheme for Enhanced Power Efficiency in System-on-Chip Architectures

High power consumption and thermal management are critical challenges in traditional System- on-Chip (SoC) architectures due to multiple active clock sources feeding individual IP blocks, even during idle states. This paper introduces a dynamic clock switching power-saving scheme that consolidates clock sources by dynamically switching to a single lower-frequency clock during low-power modes. A Clock Control Agent (CCA) monitors real-time operational status, power consumption, and performance needs, leveraging AI for predictive adjustments. Experimental results demonstrate a significant reduction in idle power consumption and improved thermal management, without compromising performance or data integrity. This scheme addresses inefficiencies in existing methods such as Dynamic Voltage and Frequency Scaling (DVFS) and clock gating, offering a robust and efficient solution for next-generation SoC designs.

Vertical Connectors in Ancient Monuments: Documentation and Experimental Study of the Behaviour of Iron and Titanium Connectors

ABSTRACT Ancient monuments are constructed following the dry construction system. Large dimensional structural members, with perfectly plane interfaces, are placed without mortar. Two types of iron connectors, vertical and horizontal, used to connect individual stone blocks, are activated in case of relative displacements, e.g. earthquakes. The paper focuses on, iron or titanium, vertical connectors, crossing the interfaces between successive stone courses, and investigates their seismic behaviour. In situ and bibliographical documentation of vertical connections in ancient Greek monuments, including their topology, dimensions, and typical pathology attributed to them, served as a basis for the design of an experimental program. First, specimens simulating the original connections are tested under monotonic and cyclic actions. The behaviour of those connections, effectuated using iron vertical connectors, having confirmed the pathology observed in situ, i.e. fracture of the substrate, an alternative connection was tested aiming at avoiding or significantly delaying the failure of the substrate (marble). An unbonded length was provided to the connector, close to the interface, to postpone the contact between the connector and the marble. The test results confirmed the anticipated change of behaviour, associated though with smaller shear resistance and larger displacements at its attainment than for the original connections.

Integrated Platform for Determining Solderability Parameters: Module for Measuring the Surface Tension of Liquid Solders

This article describes a module and method for measuring the surface tension of liquid solders implemented on a measuring device as part of an integrated platform for automatic measurement of brazebility parameters at high temperatures. A concept for constructing a test stand is presented, with a description of the individual functional blocks. The developed stand allows for testing of the solder’s surface tension. The surface tension is one of the parameters that describe the thermodynamics of interfacial reactions and the structure of newly created joints. Determining the physicochemical interactions between liquid and solid substances is crucial for various industrial processes in fields such as metallurgy, electronics, and aviation, mainly where soldering and brazing technologies are employed. A series of bubble experiments in solder for a ceramic capillary is carried out to verify the proposed method using the developed system. One of these experiments is described in this article.

LiFe0.3Mn0.7PO4-on-MXene heterostructures as highly reversible cathode materials for Lithium-ion batteries

Two-dimensional (2D) heterostructure materials, incorporating the collective strengths and synergetic properties of individual building blocks, have attracted great interest as a novel paradigm in electrode materials science. The family of 2D transition metal carbides and nitrides (e.g., MXenes) has become an appealing platform for fabricating functional materials with strong application performance. Herein, a 2D LiFe0.3Mn0.7PO4 (LFMP)–on-MXene heterostructure composite is prepared through an electrostatic self-assembly procedure. The functional groups on the surface of MXenes possess highly electronegative properties that facilitate the incorporation of LFMPs into MXenes to construct heterostructure composites. The special heterostructure of nanosized-LiFe0.3Mn0.7PO4 and MXene provides rapid Li+ and electron transport in the cathodes. This LiFe0.3Mn0.7PO4-3.0 wt% MXene composite can exhibit an excellent rate capability of 98.3 mAh g−1 at 50C and a very stable cycling performance with a capacity retention of 94.3 % at 5C after 1000 cycles. Furthermore, NaFe0.3Mn0.7PO4-3.0 wt% MXene with stable cyclability can be obtained by an electrochemical conversion method with LiFe0.3Mn0.7PO4-3.0 wt% MXene. Ex-situ XRD suggests that LiFe0.3Mn0.7PO4-on-MXene achieves a highly reversible structural evolution with a solid solution phase transformation (LFMP→LixFe0.3Mn0.7PO4 (LxFMP), LxFMP→LFMP) and a two-phase reaction (LxFMP←→Fe0.3Mn0.7PO4 (FMP)). This work provides a new direction for the use of MXenes to fabricate 2D heterostructures for lithium-ion batteries.

One-dimensional Z4 topological superconductor

We describe the mean-field model of a one-dimensional topological superconductor with two orbitals per unit cell. Time-reversal symmetry is absent, but a nonsymmorphic symmetry, involving a translation by a fraction of the unit cell, mimics the role of time-reversal symmetry. As a result, the topological superconductor has Z4 topological phases, two that support Majorana bound states and two that do not, in agreement with a prediction based on K-theory classification [K. Shiozaki, M. Sato, and K. Gomi, ]. As with the Kitaev chain, the presence of Majorana bound states gives rise to the 4π-periodic Josephson effect. A random matrix with nonsymmorphic time-reversal symmetry may be block diagonalized, and every individual block has time-reversal symmetry described by one of the Gaussian orthogonal, unitary, or symplectic ensembles. We show how this is manifested in the energy level statistics of a random system in the Z4 class as the spatial period of the nonsymmorphic symmetry is varied from much less than to of the order of the system size. Published by the American Physical Society 2024

(Keynote) Macroscopic Materials Synthesized from Nanoparticle Superlattices

One of the promises of nanotechnology in its early developmental stages was the ability to make designer materials with precise control over individual building block composition and organization in 3D space. In recent years, material synthesis methods have advanced to be able to create a multitude of nanoparticles of varying sizes, shapes, and compositions, providing a vast array of building blocks to use as materials fabrication components. Additionally, processing methods have been developed to arrange these nanoparticles into ordered arrays, to dry them into thin films, and even to sinter them into more complex bulk solids. However, the fundamental promise of being able to build a material with controlled hierarchical structure across all length scales (atomic crystal structure, molecular composition; nanoscale feature size, shape, and organization; microstructure; macroscopic form) has been challenging to realize. A materials synthesis and processing route that could create free-standing, macroscopic materials or arbitrary three-dimensional shapes with precisely controlled nanoparticle positions across the entirety of the material composition would therefore be a major advancement. Here, we demonstrate a nanoparticle-based building block called a “Nanocomposite Tecton (NCT)” that enables a self-assembly route to fabricating free-standing 3D solids of arbitrary macroscopic shapes that can utilize a multitude of different nanoparticle compositions, and also possess specifically programmed nanoscale particle arrangements and controlled microstructure. This talk will outline the key synthesis and processing steps that enable this method of making materials with programmed material structure across ~7 orders of magnitude in length scale, thereby realizing a long-standing goal of nanomaterials fabrication.

Synthesis of linear chitosan-block-dextran copolysaccharides with dihydrazide and dioxyamine linkers

Dihydrazide (ADH) and dioxyamine (PDHA) were assessed for their efficacy in coupling chitosan and dextran via their reducing ends. Initially, the end-functionalization of the individual polysaccharide blocks was investigated. Under non-reducing conditions, chitosan with a 2,5-anhydro-D-mannose unit at its reducing end exhibited high reactivity with both PDHA and ADH. Dextran, with a normal reducing end, showed superior reactivity with PDHA compared to ADH, although complete conversion with ADH could be achieved under reductive conditions with NaBH3CN. Importantly, the oxime bond in PDHA conjugates exhibited greater stability against hydrolysis compared to the hydrazone bond in ADH conjugates. The optimal block coupling method consisted in reacting chitosan with an excess of dextran pre-functionalized with PDHA. The copolysaccharides could be synthesized in high yields under both reducing and non-reducing conditions. This methodology was applied to relatively long polysaccharide blocks with molecular weight up to 14,000 g/mol for chitosan and up to 40,000 g/mol for dextran. Surprisingly, block copolysaccharides did not self-assemble at neutral or basic pH; rather, they precipitated due to hydrogen bonding between neutralized amino groups of chitosan. However, nanoparticles could be obtained through a nanoprecipitation approach.

Design and engineering of 3D plasmonic superstructure based on Pickering emulsion templates for surface-enhanced Raman spectroscopy applications in chemical and biomedical sensing

The integration of Pickering emulsion as a versatile template facilitates the assembly of nanoscale and microscale NPs, leading to the formation of intricate 3D superstructures. These superstructures exhibit collective properties, including optical, electric, and catalytic functionalities, surpassing individual building block. This review comprehensively explores the design and engineering principles behind the creation of these multifaceted superstructures. The exploration begins with the fundamental aspects of surface chemistry governing nanoparticles, a crucial factor in directing their assembly behavior at the curved liquid–liquid emulsion interface. Emphasis is placed on understanding emulsion stability, a pivotal element guiding the formation of stable 3D architectures. The discussion extends to unraveling the underlying mechanisms promoting the formation of these 3D superstructures. The focus lies in elucidating the optical functionalities of these superstructures, particularly in the context of surface-enhanced Raman spectroscopy application. The surveyed literature showcases diverse Pickering emulsion-based strategies employed in the assembly of plasmonic nanoparticles into intricate superstructures, offering controlled architectures and unlocking unique potentials for chemical and biochemical sensing.

Vibrational spectroscopy data fusion for enhanced classification of different milk types

The aim of this study is to classify seven types of Irish milk (butter, fresh, heart active, lactose free, light, protein, and slimline), supplied by a specific company, using vibrational spectroscopy methods: Near infrared (NIR), mid infrared (MIR), and Raman spectroscopy. In this regard, chemometric methods were used, and the impact of spectral data fusion on prediction accuracy was evaluated. A total of 105 samples were tested, with 21 used in the test set. The study assessed principal component analysis (PCA), partial least square discriminant analysis (PLS-DA), and sequential and orthogonalized partial least squares linear discriminant analysis (SO-PLS-LDA) for classifying different milk types. The prediction accuracy, when applying PLS-DA on individual blocks of data and low-level fused data, did not exceed 85.71 %. However, implementing the SO-PLS-LDA strategy significantly improved the accuracy to 95 %, suggesting a promising method for the development of classification models for milk using data fusion strategies.

Distinctive properties and structure of a block rock massif in assessing the stability of slopes in the deposits of Kyrgyzstan.

Abstract In this paper, the issues of slope stability in the open-pit mining of mineral deposits are considered if the slope is composed of a block structure of an array of rocks. The block structure is usually characteristic of upland quarries. It has been established that the presence of crack systems in the side massif forms a block structure and leads to disjunctive disturbances with loss of stability of individual blocks and it is not possible to calculate the stability of such a rock mass using methods for an isotropic massif. In this regard, the authors carried out work on the study of a blocky rock mass and conducted laboratory studies. The paper presents the results of field observations of the study of the mechanism of destruction of such a rock mass structure and the results of laboratory tests of the shear resistance of a separate block depending on the thickness, humidity between the block filler and the shear angle.

Technical Evaluation of Block Masonry with Pozzolanic Additions

Tests are carried out on various specimens of concrete block masonry, replacing Portland cement with pozzolans available in the region of Antofagasta, Chile (fly ash, volcanic ash and desert dust). To characterize the strength of the masonry, individual blocks, prisms and small walls, made of concrete with different binder combinations cement-pozzolan are tested; the obtained resistances are compared with standard mixture (100% cement). The results indicate that it is feasible to replace a percentage of Portland cement with pozzolans, obtaining very similar resistance, contributing to the reduction of construction costs and also, contributing to the environment by reducing cement demand and thereby reducing emissions of greenhouse gases that are generated in the calcination of the raw material. It is also pretension to enhance the importance of the masonry of concrete blocks in the construction of low-cost housing (economic and ecological).